JP6634417B2 - Manufacturing method of polarizing plate - Google Patents

Description

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

  A polarizing plate is one of optical components that constitute an image display device such as a liquid crystal television, an organic EL television, and a smartphone. The polarizing plate includes a film-shaped polarizer and an optical film (for example, a protective film) overlapping the polarizer. A cut-out portion may be formed at the end of the polarizing plate due to the design of the image display device. For example, Patent Literature 1 below describes that a notch is formed at an end of a polarizing plate as a liquid crystal injection port.

JP 2000-155325 A

  As a result of a study by the present inventors, it has been found that when a notch is formed on a polarizing plate by punching, a crack is easily formed in a corner located inside the notch. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a polarizing plate capable of suppressing cracks in a notch of the polarizing plate.

  The method for manufacturing a polarizing plate according to one aspect of the present invention includes a step of producing a first laminate including a film-shaped polarizer and at least one optical film overlapping the polarizer, and punching the first laminate, The method includes a step of producing a second laminated body having a concave cutout, and a step of polishing a corner located inside the cutout to reduce the radius of curvature of the corner.

In one aspect of the present invention, before the corner is polished, the corner seen from the laminating direction of the second laminate may be substantially curved, and the radius of curvature of the corner may be _RL. , after the corner has been polished may curvature of the corner portion as viewed from the stacking direction of the second laminate radius a R _S, R _L may be greater than Rs.

  In one aspect of the invention, the corners may be polished by an endmill.

  In one aspect of the present invention, the second laminate may have a first end that is not orthogonal to the absorption axis A of the polarizer, and a notch may be formed at the first end. In other words, in the step of manufacturing the second laminate, the angle θ formed between the first end and the absorption axis A of the polarizer may be adjusted to 0 ° or more and less than 90 °. Further, the second laminate may have a second end located opposite the first end, and the notch may extend from the first end toward the second end. The direction E in which the notch extends may not be parallel to the absorption axis A. In other words, in the step of manufacturing the second laminate, the angle α between the direction E in which the notch extends and the absorption axis A of the polarizer may be adjusted to be larger than 0 ° and 90 ° or less.

  In one aspect of the present invention, the second stacked body may have a first end and a second end located on the opposite side of the first end, and the notch is the first end. The notch may extend from the first end to the second end, and the direction E in which the notch extends may not be parallel to the absorption axis A of the polarizer. In other words, in the step of manufacturing the second laminate, the angle α between the direction E in which the notch extends and the absorption axis A of the polarizer may be adjusted to be larger than 0 ° and 90 ° or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the polarizing plate which can suppress the crack in the notch part of a polarizing plate is provided.

FIG. 1 is a schematic perspective view of a first laminate according to one embodiment of the present invention. (A) in FIG. 2 is a top view of the second laminate before being polished, and (b) in FIG. 2 is a deformation of the second laminate shown in (a) in FIG. It is an example. FIG. 3 is an enlarged view of (a) in FIG. FIG. 4 is an enlarged view of (a) in FIG. 2 and the second laminate shown in FIG. 3, and shows a notched portion before being polished. FIG. 5 is an enlarged view of the second laminate (polarizing plate), showing a cutout portion after being polished. FIG. 6 is a schematic perspective view of the second laminate (polarizing plate) shown in FIG. FIG. 7 is an enlarged view of a second laminated body according to another embodiment of the present invention, showing a notched portion before being polished. FIG. 8 is an enlarged view of a second laminate (polarizing plate) according to another embodiment of the present invention, and shows a cutout portion after being polished.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, equivalent components are denoted by the same reference numerals. The present invention is not limited to the following embodiments. X, Y and Z shown in each figure mean three coordinate axes orthogonal to each other. The direction indicated by each coordinate axis is common to all drawings.

  The method for manufacturing a polarizing plate according to this embodiment includes a step of manufacturing a first laminate including a film-shaped polarizer and at least one optical film overlapping the polarizer, and punching of the first laminate to form a concave. A step (punching) of producing a second laminate having a notch formed therein, and polishing the inside of the notch with a cutting / polishing tool to reduce a radius of curvature of a corner located inside the notch. Reducing (polishing). Punching may be referred to as blanking. The punching process is, for example, a method in which the first laminate is sandwiched between a male die (punch) and a female die (die), and the male die is pushed into the female die, thereby extracting the second laminate from the first laminate. It may be. The punching process is, for example, sandwiching the first laminate between a cutting die and a face plate, and pressing the first laminate with the die and the face plate to thereby press the second laminate into the first laminate. It may be a method of extracting from the laminate. The second laminate may be manufactured from the first laminate by combining the punching with the cutting using a cutting tool or a laser. Hereinafter, each step (particularly, punching and polishing) will be described in detail. The cutting / polishing tool used for polishing the inside of the notch is selected from the group consisting of, for example, a file, a tap, a grinder, a leutor, and a milling cutter. It may be at least one type of tool. A plurality of types of cutting / polishing tools may be used for polishing.

  The first laminate is produced by laminating a film-shaped polarizer and at least one optical film and laminating them. The optical film means a film-like member constituting the polarizing plate (excluding the polarizer itself). The optical film may be called a layer or an optical layer. The optical film may be, for example, a protective film and a release film. Each of the polarizer and the optical film may have a long strip shape, and the first laminate may have a long strip shape. The type, number, and composition of the optical films included in the first laminate are not limited. The laminated structure of the first laminate is not limited.

  For example, as shown in FIG. 1, the first laminate 107 includes a film-shaped polarizer 8 and a plurality of optical films (3, 5, 9, 13) overlapping the polarizer 8. Each of the polarizer 8 and the plurality of optical films (3, 5, 9, 13) is rectangular. The plurality of optical films (3, 5, 9, 13) are the first protective film 5, the second protective film 9, the third protective film 3, and the release film 13 (separator). That is, the first laminate 107 includes the polarizer 8, the first protective film 5, the second protective film 9, the third protective film 3, and the release film 13. The first laminate 107 also includes the adhesive layer 11 located between the second protective film 9 and the release film 13. The first protective film 5 overlaps one surface of the polarizer 8, and the second protective film 9 overlaps the other surface of the polarizer 8. That is, the protective films adhere to both surfaces of the polarizer 8. The third protective film 3 overlaps the first protective film 5. That is, the first protective film 5 is located between the polarizer 8 and the third protective film 3. The release film 13 overlaps the second protective film 9 via the adhesive layer 11. In other words, the second protective film 9 is located between the polarizer 8 and the adhesive layer 11.

  By punching the first laminate 107, a second laminate 7 'as shown in FIG. 2 or 3 is manufactured. A plurality of second laminates 7 'may be made from the first laminate 107.

  At an end (first end 7e) of the second laminate 7 ', a concave cut-out portion 7C' (concave cut-out port) is formed. The notch 7C 'penetrates all of the polarizer 8, the optical films (3, 5, 9, 13) and the adhesive layer 11 in the laminating direction (Z-axis direction) of the second laminate 7'. . That is, a concave cutout portion 7C 'common to all of the polarizer 8, the optical films (3, 5, 9, 13) and the adhesive layer 11 is formed on the end face of the second laminate 7'. The shape of the notch of the polarizer 8 as viewed from the stacking direction (Z-axis direction) may be the same as or similar to the shape of the notch 7C 'of the second laminate 7' as viewed from the stacking direction. The shape of the notch 7C 'of the second laminate 7' as viewed from the lamination direction may be regarded as the shape of the notch of the polarizer 8 as viewed from the lamination direction. The notch 7C 'is rectangular. However, the shape of the notch 7C 'is not limited to a rectangle.

As shown in FIG. 4, the inside of the second stacked body 7 'notch 7C viewed from the laminating direction (Z axis direction) of the' corners 7C _L is located. Corners 7C _L is substantially curvilinear. In other words, in the prior corners 7C _L is polished by cutting and polishing tool, corners 7C _L as viewed from the stacking direction of the second stacked body 7 'is substantially curved. In three-dimensional space, a corner portion 7C _L located inside the 'notch 7C' of the second stacked body 7 has a substantially curved shape. If the corner portion 7C _L before being polished by the cutting and polishing tools as viewed from the stacking direction of the second stacked body 7 ', the curvature radius of the corner portion 7C _L is R _L. That is, if the corner portion 7C _L as viewed from the stacking direction of the second stacked body 7 'is approximated by an arc of a great circle C _L, the radius of curvature R _L of the corner portion 7C _L is equal to the radius of the great circle C _L.

Following stamping, polishing with cutting and polishing tools corners 7C _L located inside the 'notch 7C' of the second stack 7. In other words, following the stamping, by grinding the cutting and polishing tools corners 7C _L notches 7C ', reducing the radius of curvature R _L of the corner portion 7C _L. The cutting and polishing tools for use in polishing corners 7C _L, end mill (endmill) preferably is a kind of milling cutter. By using an end mill, the object is easily polished linearly or curvedly depending on the shape of the object to be polished. An end mill is a type of milling cutter for cutting and polishing. The blade of the end mill is located on the side surface of the end mill substantially parallel to the rotation axis of the end mill. By the rotation of the end mill, the surface of the workpiece (work) against which the blade of the end mill is pressed is cut and polished. By cutting and polishing in the end mill corners 7C _L notches 7C ', corners 7C _L is finished smooth. The entire inside of the notched portion 7C 'including the corner portion 7C _L may be polished with the end mill. 'In addition to the inside of the (corner 7C _L), the notch portion 7C' notch 7C end of the second stacked body 7 'located outside of (end surface) may be polished with the end mill. A part or the whole of the end (outer edge) of the second laminate 7 'may be polished by an end mill.

  Hereinafter, the second laminate before polishing may be referred to as “second laminate 7 ′”. The second laminate after the polishing process may be referred to as “second laminate 7”. In addition, the notched portion of the second stacked body 7 'before polishing may be referred to as "notched portion 7C'". The notched portion of the second laminate 7 after the polishing process may be referred to as “notched portion 7C”.

As shown in FIG. 5, when the corner portion 7C _S after being polished by the cutting and polishing tools as viewed from the stacking direction of the second stacked body 7, the curvature radius of the corner portion 7C _S is R _S. That is, if the corner portion 7C _S viewed from the laminating direction of the second stacked body 7 is approximated by an arc of a small circle C _S, the radius of curvature R _S of the corner portion 7C _S is equal to the radius of the small circle C _S. 4 and as fit shown in Figure 5, the radius of curvature R _L of the corner portion 7C _L before being polished by the cutting and polishing tools, the curvature of the corner portion 7C _S after being polished by the cutting and polishing tools It is smaller than the radius _RS .

Second stacked body 7 which has undergone polishing of corners 7C _L by cutting and polishing tools (second stacked body 7 shown in FIG. 6) may be the finished polarizer.

In this embodiment, the punching, the polishing subsequent, are chamfered is corner 7C _S notches 7C, the surface of the corner portion 7C _S becomes smooth. As a result, cracks are suppressed in the notch 7C (especially corners 7C _S). As the radius of curvature R _{S of the} polished corner 7C _S is larger, cracks are more likely to be suppressed in the notch 7C (particularly, the corner 7C _S ) of the completed polarizing plate.

If, only by a single stamping, 'when adjusting the corner 7C smaller radius of curvature _L of (R _S), in the course of punching, the notch portion 7C' notch 7C corners 7C _L of Stress tends to concentrate on As a result, many large cracks are likely to be formed in the notch 7C '(particularly, the corner 7C _L ) with the punching. After a large number of large cracks are formed in the notch 7C '(corner 7C _L ) by punching, even if the inside of the notch 7C' (corner 7C _L ) is polished with a cutting / polishing tool, Cracks may remain.

On the other hand, in the present embodiment, when the punching is adjusted to _(greater than R _S) relatively large value R _L of the curvature radius of the corner portion 7C _L notches 7C '. Then, the polishing following the punching, reducing the radius of curvature R _L of the corner portion 7C _L notches 7C 'to R _S. In other words, the two steps of polishing and punching, the curvature radius R _L of the corner portion 7C _L notches 7C 'stepwise (gradually) decreases. As a result, once as compared with the case of adjusting the radius of curvature of the corner portion 7C _L to a small value R _S by punching only, cracks suppression in accompanying punching notch 7C '(especially the corner portion 7C _L) Is done. As the radius of curvature R _L of the corner portion 7C _L is adjusted in punching is large, easy to crack at the accompanying punching notch 7C '(especially the corner portion 7C _L) is suppressed. As the radius of curvature R _L of the corner portion 7C _L is adjusted in punching is large, a crack formed in the notched portion 7C '(especially the corner portion 7C _L) with the stamping, cutting and polishing tools (especially end mill ) Is easy to remove by polishing.

The shape of the notch 7C 'formed by the punching corresponds to the shape of a punch or a punch used for the punching. The radius of curvature R _L of the corner portion 7C _L before polishing processing, by adjusting the shape of the punch or cutting dies may be freely controlled. The radius of curvature R _S of the corner 7 C _S of the notch 7 C after the polishing may be freely controlled by adjusting the movement path of the cutting / polishing tool. When using an end mill as a cutting and polishing tools, the radius of curvature R _S of the corner portion 7C _S after polishing is by adjusting the thickness of the end mill, it may be freely controlled. For example, the lower limit of the radius of curvature R _S may be about １ ／ of the thickness (diameter) of the end mill. The radius of curvature R _S of the corner portion 7C _S after polishing is by adjusting the size of the blade of the end mill, it may be freely controlled.

The radius of curvature _{R L} of the corner portion 7C _L before being polished by the cutting and polishing tools may be, for example, 2.3～20Mm. The radius of curvature R _S of the corner 7C _S after being polished by the cutting / polishing tool may be, for example, 2.0 to 10 mm. _RL / _RS may be, for example, from 1.2 to 2.0. R _L, when each _{R S} and _R L / _{R S} is within the above range, cracks are easily suppressed in notch 7C passing through the polishing by cutting and polishing tools (especially corners 7C _S).

The length of the crack which may be formed in the cutout portion 7C with the punching '(especially the corner portion 7C _L) may be, for example, about 300～600Myuemu. Width of the portion cut away by the cutting and polishing tools from the corner portion 7C _L of the second stack 7 'may be, for example, 300 to 500 [mu] m.

  By punching the first laminate 107, a second laminate 7 'having a first end 7e that is not orthogonal to the absorption axis A of the polarizer 8 may be manufactured, and the cutout 7C' is formed in the first end 7e. May be formed. As shown in FIG. 2 (a), FIG. 2 (b) or FIG. 3, the reference line L is a straight line connecting a pair of corners 7C1 and 7C2 located at both ends of the notch 7C '. When defined, the reference line L need not be orthogonal to the absorption axis A of the polarizer 8. In other words, the angle θ between the reference line L of the notch 7C 'and the absorption axis A of the polarizer 8 may be 0 ° or more and less than 90 °. The reference line L may be referred to as a straight line connecting the pair of corners 7C1 and 7C2 in a direction perpendicular to the stacking direction (Z-axis direction) of the second stacked body 7 '.

  The absorption axis A may be, for example, a straight line that is substantially parallel to the orientation direction of the polyvinyl alcohol (PVA) molecules in the polarizer 8. The absorption axis A may be, for example, a straight line that is substantially parallel to the orientation direction of a dye molecule (for example, polyiodine or an organic dye) adsorbed on polyvinyl alcohol in the polarizer 8. It can be said that a large number of carbon atoms constituting one PVA molecule are connected to each other by a covalent bond (CC bond) along the absorption axis A. On the other hand, in a direction substantially perpendicular to the absorption axis A, the PVA molecules are bonded by a cross-linking via a cross-linking agent (for example, boric acid). In other words, in a direction substantially perpendicular to the absorption axis A, the hydroxy group of each PVA molecule forms a hydrogen bond or an oxygen-boron bond (OB bond) with boric acid located between the PVA molecules. Thereby, PVA molecules are cross-linked. CC bonds formed along the absorption axis A are stronger than cross-links formed along a direction substantially perpendicular to the absorption axis A. Therefore, the mechanical strength of the polarizer 8 in a direction substantially parallel to the absorption axis A is higher than the mechanical strength of the polarizer 8 in a direction substantially perpendicular to the absorption axis A. In other words, the heat shrinkage of the polarizer 8 in a direction substantially parallel to the absorption axis A is less likely to cause cracks than the heat shrinkage of the polarizer 8 in a direction substantially perpendicular to the absorption axis A.

  If the reference line L is orthogonal to the absorption axis A (when the angle θ is 90 °), a weak cross-link is formed in the direction parallel to the reference line L as compared with the CC bond in the PVA molecule. I have. Therefore, when the reference line L is orthogonal to the absorption axis A, when the deep part 7Cd (rear part) of the notch part 7C ′ contracts in a direction substantially parallel to the reference line L, cracks occur in the deep part of the notch part 7C ′. Easy to form.

  On the other hand, when the reference line L is not orthogonal to the absorption axis A of the polarizer 8 (that is, when the angle θ is equal to or greater than 0 ° and less than 90 °), the strength of the PVA molecule is stronger than the cross-linking between PVA molecules. The CC bond increases the mechanical strength of the polarizer 8 in a direction parallel to the reference line L. As a result, even if the deep portion 7Cd of the notch 7C 'shrinks in a direction substantially parallel to the reference line L, cracks are not easily formed in the notch 7C'. In particular, when the reference line L is parallel to the absorption axis A (when the angle θ is 0 °), CC bonds in most PVA molecules constituting the polarizer 8 are formed along the absorption axis A. Have been. Therefore, when the reference line L is parallel to the absorption axis A, the mechanical strength of the polarizer 8 in the direction parallel to the reference line L is significantly high, and the formation of cracks in the cutouts 7C 'is significantly suppressed. . However, even when the reference line L is orthogonal to the absorption axis A of the polarizer 8, the effect of the present invention is achieved.

  The smaller the angle θ between the reference line L and the absorption axis A, the more difficult it is for a crack to be formed in the notch 7C '. May be between 0 ° and 75 °, or between 0 ° and 60 °.

  As shown in (a) in FIG. 2, (b) in FIG. 2 or FIG. 3, the second laminated body 7 ′ obtained by the punching process has a first end portion in which a cutout portion 7C ′ is formed. 7e and a second end 17e opposite to the first end 7e. In the punching process, the notch 7C 'may be extended from the first end 7e toward the second end 17e. Then, the direction E in which the notch 7C 'extends may be adjusted to a direction that is not parallel to the absorption axis A of the polarizer 8. In other words, the angle α formed by the direction E in which the notch 7C 'extends and the absorption axis A may be greater than 0 ° and 90 ° or less. The direction E in which the notch 7C 'extends may be equal to the longitudinal direction of the notch 7C'. That is, the longitudinal direction of the notch 7C 'may be along the direction E in which the notch 7C' extends. Both the first end 7e and the second end 17e may be linear, and the first end 7e may be parallel to the second end 17e.

  When the direction E in which the notch portion 7C 'extends is not parallel to the absorption axis A of the polarizer 8, the CC bond in the PVA molecule which is stronger than the cross-linking between PVA molecules becomes a direction perpendicular to the direction E. , The mechanical strength of the polarizer 8 is increased. As a result, even if the deep portion 7Cd of the notch 7C 'contracts in a direction substantially perpendicular to the direction E, a crack is not easily formed in the notch 7C'. The larger the angle α between the direction E and the absorption axis A, the more difficult it is for a crack to be formed in the notch 7C '. In particular, when the direction E is perpendicular to the absorption axis A (when the angle α is 90 °), CC bonds in most PVA molecules constituting the polarizer 8 are formed perpendicular to the direction E. Have been. Therefore, when the direction E is perpendicular to the absorption axis A, the mechanical strength of the polarizer 8 in the direction perpendicular to the direction E is significantly high, and the formation of cracks in the notch 7C 'is significantly suppressed. However, even when the direction E in which the notch 7C 'extends is parallel to the absorption axis A of the polarizer 8, the effect of the present invention is achieved.

  The width Wc of the notch 7C in the direction parallel to the reference line L may be, for example, 2 mm or more and less than 600 mm, or 5 mm or more and 30 mm or less. The width Wc may be rephrased as the width of the notch 7C in a direction parallel to the end (first end 7e) of the second stacked body 7. The width W'c of the notch 7C 'may increase with the polishing by the cutting / polishing tool. That is, the width Wc of the notch 7C after polishing may be larger than the width W'c of the notch 7C 'before polishing. The width W of the entire second laminate 7 in a direction parallel to the reference line L may be, for example, 30 mm or more and 600 mm or less. The width W of the entire second laminate 7 may be rephrased as the width of the entire second laminate 7 in a direction parallel to the reference line L. The width W of the entire second laminate 7 may be reduced with the polishing by the cutting / polishing tool. The width W of the entire second laminate 7 may be rephrased as the width of the entire polarizing plate (the entire second laminate 7 after polishing). The width Wc of the notch 7C may be smaller than the width W of the entire second laminate 7. When the width Wc of the notch 7C is 5 mm or more and 30 mm or less, the width W of the entire second laminate 7 (the width of the entire polarizing plate) is greater than 20 mm and 160 mm or less, preferably greater than 25 mm and 130 mm or less, more preferably. May be greater than 30 mm and less than or equal to 100 mm, more preferably greater than 30 mm and less than or equal to 70 mm (Wc <W). The ratio Wc / W of the width Wc of the notch 7C to the width W of the entire second laminate 7 is 0.05 or more and less than 1.0, 0.08 or more and less than 1.0, or 0.10 or more and 1.0 or less. Less than, or 0.13 or more and less than 1.0, preferably 0.15 or more and less than 1.0, or 0.17 or more and less than 1.0, more preferably 0.20 or more and less than 1.0, or 0.22 or more It may be less than 1.0, more preferably 0.30 or more and less than 1.0, 0.33 or more and less than 1.0, or 0.40 or more and less than 1.0. The ratio Wc / W is 0.05 to 0.90, 0.05 to 0.80, 0.05 to 0.78, 0.05 to 0.45, or 0.40 to 0.80. It may be as follows. Wc / W may be rephrased as the ratio of the width Wc of the notch 7C to the width W of the entire first end 7e. When Wc / W is in the above range, cracks in notch 7C are likely to be suppressed. The reason is as follows. As the width Wc of the notch 7C is smaller than the width W of the entire second laminate 7, a force for expanding the width Wc of the notch 7C is more likely to be generated due to the contraction of the entire second laminate 7 due to the temperature change. In addition, cracks are easily generated in the notch 7C. That is, as Wc / W is smaller, cracks are more likely to occur in the notch 7C. On the other hand, as Wc / W increases (the width W of the entire second laminate 7 decreases), the amount of contraction of the entire second laminate 7 due to a temperature change is reduced. That is, as the width W of the entire second laminate 7 is smaller, the absolute value of the amount of change in the overall width W of the second laminate 7 is reduced. Since the amount of shrinkage of the entire second laminate 7 due to the temperature change is reduced, a force for expanding the width Wc of the notch 7C is not easily generated, and cracks in the notch 7C are easily suppressed. However, even when Wc / W is out of the above numerical range, it is possible to suppress the crack in the notch 7C.

  The length (depth) Dc of the notch 7C in a direction perpendicular to the reference line L may be, for example, 1 mm or more and 30 mm or less. The length Dc may be rephrased as the depth of the notch 7C in a direction perpendicular to the reference line L. The length D'c of the notch 7C 'may be extended with the polishing by the cutting / polishing tool. That is, the length Dc of the notched portion 7C after the polishing process may be longer than the length D'c of the notched portion 7C 'after the polishing process. The overall length D of the second laminate 7 in a direction perpendicular to the reference line L may be, for example, 30 mm or more and 600 mm or less. The length D of the entire second laminate 7 may be reduced with the polishing by the cutting / polishing tool. The entire length D of the second stacked body 7 may be referred to as the length of the entire polarizing plate (the entire second stacked body 7 after polishing) in a direction perpendicular to the reference line L. The thickness of the second laminate 7 may be, for example, 10 μm or more and 1200 μm or less, 10 μm or more and 500 μm or less, 10 μm or more and 300 μm or less, or 10 μm or more and 200 μm or less. The thickness of the second laminate 7 may be the same as the thickness of the entire polarizing plate (the whole second laminate 7 after polishing). The width Wc of the notch 7C may be larger than the length Dc of the notch 7C. The width Wc of the notch 7C may be smaller than the length Dc of the notch 7C. The width Wc of the notch 7C may be equal to the length Dc of the notch 7C.

  The details of the method for producing the first laminate before the punching may be as follows.

  A laminate (first laminate) may be produced by laminating a long strip-shaped polarizer film and a plurality of long strip-shaped optical films. The long strip-shaped polarizer film is the polarizer 8 before processing and molding. The absorption axis of the polarizer film may be the same as the absorption axis A of the polarizer 8 after processing and molding. The plurality of long strip-shaped optical films are the optical films (3, 5, 9, 13) before processing and molding.

  The direction of the absorption axis A of the polarizer 8 included in the second laminate 7 'has already been grasped before the punching. Therefore, the angle θ may be adjusted to 0 ° or more and less than 90 ° by adjusting the punching direction of the first laminate 107. When the notch 7C 'is formed at the first end 7e of the second laminate 7', by adjusting the direction of the notch 7C ', the angle α is larger than 0 ° and equal to or less than 90 °. May be controlled in a range. The direction itself of the absorption axis A in the polarizer film (polarizer 8) may be adjusted and controlled by the stretching direction and the stretching ratio of the PVA film performed before the punching.

  The polarizer 8 may be a film-shaped polyvinyl alcohol-based resin (PVA film) produced by processes such as stretching, dyeing, and crosslinking. Details of the polarizer 8 are as follows.

  For example, first, the PVA film is stretched uniaxially or biaxially. The dichroic ratio of the polarizer 8 stretched in the uniaxial direction tends to be high. Subsequent to the stretching, the PVA film is dyed with iodine, a dichroic dye (polyiodine) or an organic dye using a dye solution. The staining solution may contain boric acid, zinc sulfate, or zinc chloride. Before dyeing, the PVA film may be washed with water. Washing removes dirt and an anti-blocking agent from the surface of the PVA film. In addition, as a result of swelling of the PVA film by washing with water, spots of dyeing (uneven dyeing) are easily suppressed. The dyed PVA film is treated with a solution of a crosslinking agent (for example, an aqueous solution of boric acid) for crosslinking. After treatment with the crosslinking agent, the PVA film is washed with water and subsequently dried. Through the above procedure, the polarizer 8 is obtained. The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate resin is, for example, polyvinyl acetate which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and another monomer (for example, an ethylene-vinyl acetate copolymer). Good. Other monomers copolymerized with vinyl acetate may be, 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 dehydrated polyvinyl alcohol or a dehydrochlorinated polyvinyl chloride. Dyeing may be performed before stretching, or stretching may be performed in a dyeing solution. The length of the stretched polarizer 8 may be, for example, 3 to 7 times the length before stretching.

  The thickness of the polarizer 8 may be, for example, 1 μm to 50 μm, 1 μm to 10 μm, 1 μm to 8 μm, 1 μm to 7 μm, or 4 μm to 30 μm. As the polarizer 8 is thinner, the shrinkage of the polarizer 8 itself due to the temperature change is suppressed, and the change in the dimension of the polarizer 8 itself is suppressed. As a result, stress does not easily act on the polarizer 8, and cracks in the polarizer 8 are easily suppressed.

  The first protective film 5 and the second protective film 9 may be a thermoplastic resin having a light transmitting property, and may be an optically transparent thermoplastic resin. The resin constituting the first protective film 5 and the second protective film 9 is, for example, a chain polyolefin resin, a cyclic olefin polymer resin (COP resin), a cellulose ester resin, a polyester resin, a polycarbonate resin, or It may be a (meth) acrylic resin, a polystyrene resin, or a mixture or copolymer thereof. The composition of the first protective film 5 may be exactly the same as the composition of the second protective film 9. The composition of the first protective film 5 may be different from the composition of the second protective film 9.

  The chain polyolefin-based resin may be, for example, 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 chain olefins.

  The cyclic olefin polymer-based resin (cyclic polyolefin-based resin) may be, for example, a ring-opened (co) polymer of a cyclic olefin or an addition polymer of a cyclic olefin. The cyclic olefin polymer-based resin may be, for example, a copolymer of a cyclic olefin and a chain olefin (for example, a random copolymer). The chain olefin constituting the copolymer may be, for example, ethylene or propylene. The cyclic olefin polymer-based resin may be a graft polymer obtained by modifying the above polymer with an unsaturated carboxylic acid or a derivative thereof, or a hydride thereof. The cyclic olefin polymer-based resin may be, for example, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer.

  The cellulose ester-based resin may be, for example, cellulose triacetate (triacetyl cellulose (TAC)), cellulose diacetate, cellulose tripropionate, or cellulose dipropionate. These copolymers may be used. A cellulose ester resin in which a part of hydroxyl groups is modified with another substituent may be used.

  A polyester resin other than the cellulose ester resin may be used. The polyester resin may be, for example, a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. The polycarboxylic acid or a derivative thereof may be a dicarboxylic acid or a derivative thereof. The polycarboxylic acid or derivative thereof may be, for example, terephthalic acid, isophthalic acid, dimethyl terephthalate, or dimethyl naphthalenedicarboxylate. The polyhydric alcohol may be, for example, a diol. The polyhydric alcohol may be, for example, ethylene glycol, propanediol, butanediol, neopentyl glycol, or cyclohexanedimethanol.

  The polyester resin may be, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, or polycyclohexane dimethyl naphthalate. .

  The polycarbonate resin is a polymer in which polymerized units (monomers) are bonded via a carbonate group. The polycarbonate resin may be a modified polycarbonate having a modified polymer skeleton, or may be a copolymerized polycarbonate.

  (Meth) acrylic resin is, for example, poly (meth) acrylate (for example, polymethyl methacrylate (PMMA)); methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylic Acid ester copolymer; methyl methacrylate-acrylate- (meth) acrylic acid copolymer; methyl (meth) acrylate-styrene copolymer (for example, MS resin); methyl methacrylate and alicyclic hydrocarbon It may be a copolymer with a compound having a group (for example, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate-norbornyl (meth) acrylate copolymer).

  At least one of the pair of optical films (the first protective film 5 and the second protective film 9) sandwiching the polarizer 8 may include triacetyl cellulose (TAC). At least one of the pair of optical films (the first protective film 5 and the second protective film 9) sandwiching the polarizer 8 may include a cyclic olefin polymer-based resin (COP-based resin). At least one of the pair of optical films (the first protective film 5 and the second protective film 9) sandwiching the polarizer 8 may include polymethyl methacrylate (PMMA). Both of the pair of optical films (the first protective film 5 and the second protective film 9) sandwiching the polarizer 8 may include triacetyl cellulose. One of the pair of optical films sandwiching the polarizer 8 (the first protective film 5 and the second protective film 9) includes triacetyl cellulose, and the other of the pair of optical films sandwiching the polarizer 8 includes , A cyclic olefin polymer. One of the pair of optical films sandwiching the polarizer 8 (the first protective film 5 and the second protective film 9) includes triacetyl cellulose, and the other of the pair of optical films sandwiching the polarizer 8 includes , Polymethyl methacrylate. One of the pair of optical films (the first protective film 5 and the second protective film 9) sandwiching the polarizer 8 includes a cyclic olefin polymer-based resin, and the other one of the pair of optical films sandwiching the polarizer 8 The film may include polymethyl methacrylate. When the polarizer 8 is sandwiched between a pair of optical films (the first protective film 5 and the second protective film 9), the optical film (protective film) adheres to the polarizer 8, and the polarizer 8 accompanying the temperature change. The expansion or contraction of the polarizer 8 is suppressed, so that cracks in the polarizer 8 hardly occur. For example, when the polarizer 8 is sandwiched between the first protective film 5 made of TAC and the second protective film 9 made of a COP-based resin, cracks in the polarizer 8 hardly occur.

  The first protective film 5 or the second protective film 9 is at least one member 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. It may contain additives.

  The thickness of the first protective film 5 may be, for example, 5 μm or more and 90 μm or less, 5 μm or more and 80 μm or less, or 5 μm or more and 50 μm or less. The thickness of the second protective film 9 may be, for example, 5 μm or more and 90 μm or less, 5 μm or more and 80 μm or less, or 5 μm or more and 50 μm or less.

  The first protective film 5 or the second protective film 9 may be a film having an optical function, such as a retardation film or a brightness enhancement film. For example, a retardation film having an arbitrary retardation value can be obtained by stretching a film made of the thermoplastic resin or forming a liquid crystal layer or the like on the film.

  The first protective film 5 may be bonded to the polarizer 8 via an adhesive layer. The second protective film 9 may also be bonded to the polarizer 8 via an adhesive layer. The adhesive layer may include a water-based adhesive such as polyvinyl alcohol, and may include an active energy ray-curable resin described later.

  The active energy ray-curable resin is a resin that cures when irradiated with an active energy ray. The active energy ray may be, for example, an ultraviolet ray, a visible light, an electron beam, or an X-ray. The active energy ray-curable resin may be an ultraviolet-curable resin.

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

  The cationically polymerizable curable compound may be, for example, an epoxy compound (a compound having at least one epoxy group in a molecule) or an oxetane compound (a compound having at least one oxetane ring in a molecule). The radical polymerizable curable compound may be, for example, a (meth) acrylic compound (a compound having at least one (meth) acryloyloxy group in a molecule). The radical polymerizable curable compound may be a vinyl compound having a radical polymerizable double bond.

  The active energy ray-curable resin may be, if necessary, a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoamer. Agents, antistatic agents, leveling agents, or solvents.

  The adhesive layer 11 may include, for example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or a urethane-based pressure-sensitive adhesive. The thickness of the adhesive layer 11 may be, for example, 2 μm or more and 500 μm or less, 2 μm or more and 200 μm or less, or 2 μm or more and 50 μm or less.

  The resin constituting the third protective film 3 may be the same as the above-mentioned resins listed as the resin constituting the first protective film 5 or the second protective film 9. The thickness of the third protective film 3 may be, for example, not less than 5 μm and not more than 200 μm.

  The resin constituting the release film 13 may be the same as the resin listed above as the resin constituting the first protective film 5 or the second protective film 9. The thickness of the release film 13 may be, for example, 5 μm or more and 200 μm or less.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

For example, a plurality of notches may be formed in the second laminate by punching the first laminate. The radius of curvature _RL of a corner located inside some of the notches of the plurality of notches may be reduced by polishing. The radius of curvature _RL of a corner located inside all the notches of the plurality of notches may be reduced by polishing. There may be one corner inside one notch. There may be a plurality of corners inside one notch. The radius of curvature _RL of some of the plurality of corners may be reduced by polishing. The radius of curvature _RL of all the plurality of corners may be reduced by polishing.

  The shapes of the polarizing plate and the notch may be various shapes depending on the application. For example, as shown in FIG. 7, the shape of the notch 7C 'before polishing may be substantially triangular. As shown in FIG. 8, the shape of the notch 7C after the polishing process may be substantially triangular. The entire shape of the notch (7C ', 7C) may be a semicircle or an arc. The shape of the notch (7C ', 7C) is not limited to a square or a triangle, and may be another polygon. The deep portion of the notch (7C ', 7C) may be branched into a plurality.

  The entire outer edge of the second laminate (7 ', 7) may be a polygon other than a square. The entire outer edge of the second laminate (7 ', 7) may be a closed curve. For example, the entire outer edge of the second laminate (7 ', 7) may be circular or oval. A part of the outer edge of the second laminate (7 ', 7) may be linear, and the remaining outer edge of the second laminate (7', 7) may be curved. The shape of the outer edge of the completed polarizing plate may be substantially the same as the shape of the outer edge of the second laminate (7 ', 7).

  The first end 7e in which the cutout 7C 'is formed may not be parallel to the second end 17e. When the first end 7e is not parallel to the second end 17e and the deep portion 7Cd (bottom) of the notch 7C is straight, the “direction E in which the notch 7C ′ extends” is defined as a pair of A line segment connecting the corners 7C1 and 7C2 may be bisected, and may be parallel to a straight line bisecting the deep portion 7Cd of the notch 7C '. When the first end 7e is not parallel to the second end 17e and the deep portion 7Cd of the notch 7C is curved, the “direction E in which the notch 7C extends” is the deep portion 7Cd of the notch 7C. It may be flat as a straight line connecting the (deepest part) and the midpoint of the line connecting the corners 7C1 and 7C2.

  The type and number of optical films constituting the second laminate (7 ', 7) or the polarizing plate and the order of lamination are not limited. The optical film is a reflective polarizing film, a film with an antiglare function, a film with a surface antireflection function, a reflective film, a transflective film, a viewing angle compensation film, an optical compensation layer, a touch sensor layer, an antistatic layer, or an antifouling layer. It may be. The second laminate (7 ', 7) or the polarizing plate may further include a hard coat layer.

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

(Example 1)
A rectangular first laminate 107 composed of a polarizer film (polarizer 8 before cutting), four optical films (3, 5, 9, 13), and a pressure-sensitive adhesive layer 11 was produced. The first laminate 107 includes a release film 13, an adhesive layer 11 overlapping the release film 13, a second protective film 9 overlapping the adhesive layer 11, and a polarizer film (7) overlapping the second protective film 9. , A first protective film 5 overlapping the polarizer film (7), and a third protective film 3 overlapping the first protective film 5. Stretched and dyed film-like polyvinyl alcohol was used as the polarizer film (7). As the first protective film 5, a triacetyl cellulose (TAC) film was used. As the second protective film 9, a film composed of a cyclic olefin polymer-based resin (COP-based resin) was used. As the third protective film 3, a PET protect film was used. As the release film 13, a PET separator was used. The thickness of the release film 13 was 38 μm. The thickness of the adhesive layer 11 was 20 μm. The thickness of the second protective film 9 was 13 μm. The thickness of the polarizer 8 was 7 μm. The thickness of the first protective film 5 was 25 μm. The thickness of the third protective film 3 was 58 μm.

  By punching the first laminated body 107, a second laminated body 7 'having a cutout 7C' was formed. The entire shape (outer edge) of the second laminate 7 'was substantially rectangular. In the punching process, the width W of the side (the first end 7e where the notch 7C 'was formed) of the second laminate 7' was adjusted to 150 mm. The width of the vertical side of the second laminate 7 '(the entire length D of the second laminate 7') was adjusted to 80 mm.

In the punching process, a concave cutout portion 7C 'was formed substantially at the center of the first end 7e of the second laminate 7'. As shown in FIG. 4, the shape of the notch 7C ′ was substantially rectangular. The radius of curvature R _L of the corner portion 7C _L of the second 'notch 7C viewed from the laminating direction of the' stacked body 7 was adjusted to 3.0 mm. In other words, the radius of curvature _{R L} of the corner portion 7C _L before polishing was 3.0 mm. The width W'c of the notch 7C 'was adjusted to 20 mm. The length D'c of the notch 7C 'was adjusted to 10 mm.

  The entire cutout 7C 'before polishing was observed with an optical microscope. As a result of the observation, it was confirmed that a small number of cracks were formed in the notch 7C '. The length of each crack was measured. As the length of the crack, a distance between one end of the crack and the other end of the crack was measured. The maximum value of the crack length was 300 μm.

Following stamping, and the whole inside of the notched portion 7C 'including the corner portion 7C _L uniformly polished end mill. That is, by polishing, reduced the curvature radius R _L of the corner portion 7C _L. Width of the portion shaved off from the corner portion 7C _L of the second stacked body 7 'by end mill was adjusted to 300 [mu] m. As shown in FIG. 5, the curvature radius R _S of the corner portion 7C _S notches 7C after polishing viewed from the laminating direction of the second stacked body 7 was adjusted to 2.0 mm.

  Through the steps described above, the polarizing plate (second laminated body 7) of Example 1 was completed. The whole of the concave notch formed in the polarizing plate was observed with an optical microscope. No crack was formed in the notch 7C of Example 1 (notch 7C after polishing).

(Example 2)
The stamping of Example 2, the curvature radius _{R L} of the corner portion 7C _L notches 7C ', was adjusted to 2.5 mm. A second laminate 7 'of Example 2 (a second laminate 7' before polishing) was produced in the same manner as in Example 1, except for the value of the radius of curvature _RL . The entire cutout 7C 'formed in the second laminate 7' of Example 2 was observed with an optical microscope. As a result of the observation, it was confirmed that a small number of cracks were formed in the notch 7C '. The maximum value of the crack length was 350 μm.

A polarizing plate (second laminate 7) of Example 2 was completed in the same manner as in Example 1 except for the value of the radius of curvature _RL before polishing. The entire cutout 7C formed in the polarizing plate of Example 2 was observed with an optical microscope. No crack was formed in the notch 7C of Example 2 (notch 7C after polishing).

(Example 3)
The stamping of Example 3, the curvature radius _{R L} of the corner portion 7C _L notches 7C ', was adjusted to 2.3 mm. A second laminate 7 'of Example 3 (a second laminate 7' before polishing) was produced in the same manner as in Example 1 except for the value of the radius of curvature _RL . The entire cutout 7C 'formed in the second laminate 7' of Example 3 was observed with an optical microscope. As a result of the observation, it was confirmed that a small number of cracks were formed in the notch 7C '. The maximum value of the crack length was 350 μm.

A polarizing plate (second laminated body 7) of Example 3 was completed in the same manner as in Example 1 except for the value of the radius of curvature _RL before polishing. The entire cutout 7C formed in the polarizing plate of Example 3 was observed with an optical microscope. No crack was formed in the notch 7C of Example 3 (the notch 7C after polishing).

(Example 4)
The stamping of the fourth embodiment, the curvature radius _{R L} of the corner portion 7C _L notches 7C ', was adjusted to 2.1 mm. A second laminate 7 'of Example 4 (a second laminate 7' before polishing) was produced in the same manner as in Example 1 except for the value of the radius of curvature _RL . The entire cutout 7C 'formed in the second laminate 7' of Example 4 was observed with an optical microscope. As a result of the observation, it was confirmed that a small number of cracks were formed in the notch 7C '. The maximum value of the crack length was 400 μm.

A polarizing plate (second laminated body 7) of Example 4 was completed in the same manner as in Example 1 except for the value of the radius of curvature _RL before polishing. The entire cutout 7C formed in the polarizing plate of Example 4 was observed with an optical microscope. A small number of cracks remained in the notched portion 7C of Example 4 (notched portion 7C after polishing). However, the number of cracks remaining in the notch 7C after the polishing was smaller than the number of cracks formed in the notch 7C 'before the polishing. The maximum value of the length of the crack remaining in the notch 7C after the polishing was smaller than the maximum value of the length of the crack formed in the notch 7C 'before the polishing.

(Comparative Example 1)
The stamping of Comparative Example 1, the curvature radius _{R L} of the corner portion 7C _L notches 7C ', was adjusted to 2.0 mm. In Comparative Example 1, the polishing was not performed. That is, in Comparative Example 1, a polarizing plate having the same shape and dimensions as those of Examples 1 to 4 was manufactured by only one punching process without going through two steps of punching and polishing.

  The entire cutout formed in the polarizing plate of Comparative Example 1 was observed with an optical microscope. Many cracks were formed in the notched portion of Comparative Example 1. The number of cracks formed in the notch portion of Comparative Example 1 was larger than the number of cracks formed in the notched portion 7C after polishing in Examples 1 to 4. The maximum value of the length of the crack formed in the notch of Comparative Example 1 was larger than the maximum value of the length of the crack formed in the notch 7C after the polishing in Examples 1 to 4. .

  The polarizing plate according to the present invention is attached to, for example, a liquid crystal cell or an organic EL device, and is applied as an optical component constituting an image display device such as a liquid crystal television, an organic EL television, or a smartphone.

7: Second laminated body (polarizing plate) after polishing, 7 ': Second laminated body before polishing, 3: Third protective film, 5: First protective film, 8: Film-shaped polarizer, 7C .., A concave notch after polishing, 7C ′: a concave notch before polishing, 7C1, 7C2, a pair of corners located at both ends of the notch 7C ′, 7C _L , before polishing. notch 7C 'corners of the corner portions of 7C S _... notch 7C after polishing, 7e ... second laminate 7' first end of the, 9 ... second protective film, 7Cd ... notch 7C 'deep, 11 ... adhesive layer, 13 ... release film, 17e ... second laminate 7' second end of the, 107 ... first laminate curvature R L _... polished front corner portion 7C _L radius, R S _... curvature radius of the corner portion 7C _S after polishing, L ... reference line, a ... absorption axis, E ... notch 7C 'extend direction, theta ... reference line L Angle between Osamujiku line A, alpha ... notch 7C 'of extending direction E absorption axis A and the angle of the polarizer 8.

Claims (6)

A step of producing a first laminate including a film-shaped polarizer and at least one optical film overlapping the polarizer,
By punching the first laminate, a step of producing a second laminate in which a concave notch is formed,
Polishing a corner located inside the notch to reduce the radius of curvature of the corner,
Equipped with a,
Before the corner is polished, the corner seen from the laminating direction of the second laminate is substantially curved, and the radius of curvature of the corner is _RL ,
After the corner is polished, the radius of curvature of the corner as viewed from the laminating direction of the second laminate is R _S ,
The _RL is greater than the Rs;
A method for manufacturing a polarizing plate. Polishing the corner by an end mill,
A method for manufacturing the polarizing plate according to claim 1 . The second laminate has a first end that is not orthogonal to the absorption axis A of the polarizer,
The notch is formed in the first end,
Method for producing a polarizing plate according to claim 1 or 2. The second laminate has a second end located opposite to the first end,
The notch is formed in the first end,
The notch extends from the first end toward the second end,
The direction E in which the notch extends is not parallel to the absorption axis A;
A method for producing the polarizing plate according to claim 3 . The second laminate has a first end and a second end located on the opposite side of the first end,
The notch is formed in the first end,
The notch extends from the first end toward the second end,
The direction E in which the notch extends is not parallel to the absorption axis A of the polarizer,
Method for producing a polarizing plate according to claim 1 or 2. The first end as viewed from the stacking direction of the second stacked body is linear.
A method for producing the polarizing plate according to claim 3.

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