Method for managing optical laminate and method for producing optical laminate piece

Abstract

A method for managing an optical laminate according to an embodiment of the present invention comprises: preparing a first optical laminate stack in which a plurality of sheet-like first optical laminates including optical films are stacked, wherein the optical films that are included in the plurality of first optical laminates are derived from slit films in the same row among slit films which are obtained by slitting, along the longitudinal direction and in a plurality of rows, a long optical film having an optical axis (step A1); slitting the first optical laminate stack along a prescribed direction and obtaining a plurality of second optical laminate stacks in which a plurality of second optical laminates are stacked (step A2); selecting not less than two of the second optical laminates in each of the plurality of second optical laminate stacks, measuring axis angles of the optical films, and setting the axis angle of each of the second optical laminate stacks on the basis of the average value of the axis angles (step A3); and classifying, into the same group, second optical laminate stacks having an axis angle in the range of X±Y° (step A4).

Description

Method for managing optical laminate and method for manufacturing optical laminate piece

[0001] The present invention relates to a method for managing an optical laminate and a method for manufacturing an optical laminate piece.

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices), are rapidly becoming popular. In image display devices, optical components such as polarizing components and phase difference components are generally used to realize image display and improve image display performance (see, for example, Patent Document 1).

[0003] In recent years, new applications of image display devices have been developed. For example, goggles with displays (VR goggles) for realizing virtual reality (VR) have begun to be commercialized. Since the use of VR goggles in various situations is being considered, there is a demand for high-definition images.

[0004] Japanese Patent Application Laid-Open No. 2021-103286

[0005] In view of the above, a main object of the present invention is to provide a method for managing an optical laminate that can contribute to the manufacture of display systems such as high-definition VR goggles.

[0006] [1] According to one aspect of the present invention, there is provided a method for managing optical stacks, the method comprising: preparing a first optical stack in which a plurality of sheet-like first optical stacks each including an optical film are stacked, wherein the optical films included in the plurality of first optical stacks have an optical axis and are optical films derived from the same row of slit films obtained by slitting a long optical film into a plurality of rows along the longitudinal direction (step A1); slitting the first optical stack along a predetermined direction to obtain a plurality of second optical stacks in which a plurality of second optical stacks are stacked (step A2); selecting two or more of the second optical stacks in each of the plurality of second optical stacks, measuring the axial angles of the optical films, and setting the axial angle of each second optical stack based on the average value of the measured axial angles (step A3); and classifying the second optical stacks whose axial angles are within the range of X±Y° into the same group (step A4). [2] In the management method according to [1], all of the optical films included in the plurality of first optical laminates in the first optical laminate stack may be derived from the same slit film, and in step A3, a second optical laminate including the optical films derived from the positions furthest apart in the longitudinal direction of the same slit film may be selected. [3] In the management method according to [1] or [2], in step A3, the axial angle of the second optical laminate stack may be set within the range of the average value ±A°. [4] In the management method according to [3], A may be 0.1. [5] In the management method according to any one of [1] to [4], in step A4, second optical laminate stacks whose axial angle is within the range of X±Y×a° (where a satisfies the relationship 0.6<a<1) may be classified into the same group. [6] In the management method according to any one of [1] to [4], X may include values ​​of 2 to 16 that differ by a certain value. [7] In the management method according to the above item [6], the constant value may be 0.05 to 0.2. [8] In the management method according to any one of the above items [1] to [7], the optical film may be a reflective polarizing member.[9] In the management method according to any one of [1] to [8] above, the first optical laminate may include a reflective polarizing element, an absorptive polarizing element, and a protective element, in this order.

[10] According to another aspect of the present invention, there is provided a method for manufacturing an optical laminate piece, the method including: obtaining a group of the second optical laminate stacks having an axial angle within a range of X±Y° by the method for managing an optical laminate according to any one of [1] to [9] above (step B1); and punching out the second optical laminate stacks included in the same group in the same pattern to obtain optical laminate pieces (step B2).

[0007] The method for managing an optical stack and the method for manufacturing an optical stack piece according to the embodiments of the present invention can contribute to the production of high-definition display systems (for example, VR goggles, etc.).

[0008] 1 is a schematic diagram showing the general configuration of an example of a display system in which an optical laminate piece obtained by a manufacturing method for an optical laminate piece according to an embodiment of the present invention can be used. FIG. 2 is a schematic diagram illustrating an example of a punching pattern for an optical laminate piece. FIG. 3 is a schematic diagram illustrating a management method according to one embodiment of the present invention. FIG. 4 is a schematic diagram illustrating an example of a method for producing a slit film. (a) and (b) are schematic diagrams illustrating an example of a method for producing a sheet-like optical film. FIG. 5 is a schematic cross-sectional view illustrating the configuration of an example of an optical laminate that can be applied to the management method according to an embodiment of the present invention. FIG. 6 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. FIG. 7 is a schematic diagram illustrating an example of an embodiment of step A4. FIG. 8 is a schematic diagram illustrating an example of step B2 of a manufacturing method for an optical laminate piece according to an embodiment of the present invention.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0010] (Definition of Terms and Symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive Index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-Plane Retardation (Re) "Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Thickness Direction Retardation (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (4) Nz Coefficient The Nz coefficient is calculated by Nz = Rth / Re. (5) Angle When an angle is referred to in this specification, unless otherwise specified, the angle includes both clockwise (+) and counterclockwise (-) angles relative to a reference direction. Therefore, for example, "45°" means ±45°. Furthermore, in this specification, "substantially parallel" includes a range of 0° ±10°, preferably within a range of 0° ±5°. "Substantially perpendicular" includes a range of 90° ±10°, preferably within a range of 90° ±5°.

[0011] A. Display System FIG. 1 is a schematic diagram showing the overall configuration of an example of a display system in which an optical laminate piece obtained by a manufacturing method of an optical laminate piece according to an embodiment of the present invention can be used. FIG. 1 schematically illustrates the arrangement and shape of each component of a display system 2. The display system 2 includes a display element 12, a reflector 14 including a reflective polarizing member, a first lens unit 16, a half mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens unit 24. The reflector 14 is disposed in front of the display surface 12a of the display element 12 and can reflect light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflector 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first phase difference member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference member 22 is disposed on the optical path between the half mirror 18 and the reflector 14.

[0012] The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12 a for displaying an image. The light emitted from the display surface 12 a passes through, for example, a polarizing member (typically, a polarizing film) that may be included in the display element 12, and is converted into first linearly polarized light.

[0013] The first phase difference member 20 includes a first λ / 4 member that can convert first linearly polarized light incident on the first phase difference member 20 into first circularly polarized light. When the first phase difference member does not include any member other than the first λ / 4 member, the first phase difference member may correspond to the first λ / 4 member. The first phase difference member 20 may be provided integrally with the display element 12.

[0014] The half mirror 18 transmits light emitted from the display element 12 and reflects light reflected by the reflecting portion 14 back toward the reflecting portion 14. The half mirror 18 is provided integrally with the first lens portion 16.

[0015] The second phase difference member 22 includes a second λ / 4 member that can transmit light reflected by the reflecting unit 14 and the half mirror 18 through the reflecting unit 14. When the second phase difference member does not include any member other than the second λ / 4 member, the second phase difference member may correspond to the second λ / 4 member. The second phase difference member 22 may be provided integrally with the first lens unit 16.

[0016] The first circularly polarized light emitted from the first λ / 4 element included in the first phase difference element 20 passes through the half mirror 18 and the first lens unit 16, and is converted into the second linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The second linearly polarized light emitted from the second λ / 4 element is reflected toward the half mirror 18 without passing through the reflective polarizing element included in the reflecting unit 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element included in the reflecting unit 14 is the same as the reflection axis of the reflective polarizing element. Therefore, the second linearly polarized light incident on the reflecting unit is reflected by the reflective polarizing element.

[0017] The second linearly polarized light reflected by the reflecting unit 14 is converted into second circularly polarized light by the second λ / 4 element included in the second phase difference element 22, and the second circularly polarized light output from the second λ / 4 element passes through the first lens element 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens element 16 and is converted into third linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The third linearly polarized light passes through the reflective polarizing element. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing element included in the reflecting unit 14 is the same as the transmission axis of the reflective polarizing element. Therefore, the third linearly polarized light incident on the reflecting unit 14 passes through the reflective polarizing element.

[0018] The light transmitted through the reflecting portion 14 passes through the second lens portion 24 and enters the user's eye 26 .

[0019] The display system 2 may include an absorptive polarizing element (typically, an absorptive polarizing film) in front of the reflective polarizing element in the reflector 14. The reflection axis of the reflective polarizing element and the absorption axis of the absorptive polarizing element may be arranged substantially parallel to each other, and the transmission axis of the reflective polarizing element and the transmission axis of the absorptive polarizing element may be arranged substantially parallel to each other. This allows the third linearly polarized light that has passed through the reflective polarizing element to pass directly through the absorptive polarizing element.

[0020] For example, the absorption axis of the polarizing member that can be included in the display element 12 and the reflection axis of the reflective polarizing member that can be included in the reflecting section 14 may be disposed approximately parallel to each other or approximately perpendicular to each other. The angle formed between the absorption axis of the polarizing member that can be included in the display element 12 and the slow axis of the first λ / 4 member that can be included in the first phase difference member 20 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°. The angle formed between the absorption axis of the polarizing member that can be included in the display element 12 and the slow axis of the second λ / 4 member that can be included in the second phase difference member 22 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0021] The in-plane retardation Re(550) of the first λ / 4 component is, for example, 100 nm to 190 nm, or may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 component preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 component may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0022] The in-plane retardation Re(550) of the second λ / 4 component is, for example, 100 nm to 190 nm, or may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 component preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 component may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0023] As described above, in the display system 2, linearly polarized light emitted forward from the display surface 12a of the display element 12 passes through the first phase difference member 20 and the second phase difference member 22 in this order, and then passes through the second phase difference member 22 two more times by being reflected by the reflective polarizing member included in the reflecting unit 14 and then reflected again by the half mirror 18. The light then passes through the reflective polarizing member and exits forward, whereby it is perceived by the viewer. Therefore, if the reflection axis direction of the reflective polarizing member deviates from the set value, light leakage occurs, and the light that should be reflected is perceived as being mixed with the light that should be perceived (resulting in a blurred image). To prevent such problems and display high-definition images, it is desirable to strictly control the axial accuracy of the reflective polarizing member.

[0024] B. Method for Managing Optical Stack According to another aspect of the present invention, there is provided a method for managing an optical stack that can be used in manufacturing the display system described in Section A. A method for managing optical stacks according to an embodiment of the present invention includes: (Step A1) preparing a first optical stack in which a plurality of sheet-like first optical stacks each containing an optical film are stacked, wherein the optical films contained in the plurality of first optical stacks have an optical axis and are optical films derived from the same row of slit films obtained by slitting a long optical film into a plurality of rows along the longitudinal direction; (Step A2) slitting the first optical stack along a predetermined direction to obtain a plurality of second optical stacks in which a plurality of second optical stacks are stacked; (Step A3) selecting two or more of the second optical stacks in each of the plurality of second optical stacks, measuring the axial angles of the optical films, and setting the axial angle of each second optical stack based on the average value thereof; and (Step A4) classifying the second optical stacks whose axial angles are within the range of X±Y° into the same group. Optical films having an optical axis are generally manufactured in a long, wide shape, and then cut to the desired size, or, depending on the application, further punched into small pieces for use. However, optical films manufactured in a wide width tend to have variations in the optical axis direction in the width direction. Therefore, when an optical laminate including an optical film having variations in the optical axis direction is punched to obtain an optical laminate piece, as shown in FIG. 2, a punching pattern can be set according to the distribution of the optical axis a of the optical film throughout the optical laminate 110 to obtain an optical laminate piece 130 with improved axial accuracy. On the other hand, in the above-mentioned display system applications, as the axial accuracy becomes stricter, the allowable range of axial misalignment becomes narrower, resulting in complex punching patterns and problems in terms of production management.2 , even if the punching patterns are aligned for each row, if the axial angles (angles relative to the short side direction (0°)) of row A1 are +1.0°, +0.8°, and +0.6°, the axial angles of row A2 are +0.4°, +0.2°, and 0°, the axial angles of row A3 are −0.4°, −0.2°, and 0°, and the axial angles of row A4 are −1.0°, −0.8°, and −0.6°, then there will be a total of 81 punching patterns for the optical laminate 110, making production management complicated. To address the above problem, the method for managing an optical laminate according to an embodiment of the present invention makes it possible to efficiently obtain optical laminates whose axial angles are within a predetermined range, specifically, optical laminates whose axial angles are within the range of X±Y° when the target value of the axial angle is X°. Furthermore, as described in detail in Section C, by punching optical laminates with aligned axial angles using the same punching pattern, optical laminate pieces with high axial accuracy can be obtained with high productivity, and production management is also easy.

[0025] B-1. Step A1 In step A1, as shown in FIG. 3( a), a first optical laminate stack 110S is prepared in which a plurality of sheet-like first optical laminates 110 each including an optical film are stacked. Typically, a plurality of first optical laminate stacks are prepared. The number of first optical laminate stacks can be, for example, 2 to 100, preferably 3 to 50.

[0026] The number of first optical laminates 110 constituting one first optical laminate stack 110S can be, for example, 10 or more or 30 or more, and can be, for example, 500 or less or 300 or less.

[0027] The thickness of the first optical stack 110S can be, for example, 1 mm or more, or 10 mm or more, and, for example, 500 mm or less, or 300 mm or less.

[0028] The sheet-shaped first optical laminate is typically rectangular (rectangular or square). The size of the rectangular first optical laminate 110 may be, for example, 50 mm or more or 100 mm or more in terms of the length of one side, and may be, for example, 1000 mm or less or 500 mm or less. Note that "rectangular" includes a shape that can be recognized as a rectangle as a whole. For example, the rectangular first optical laminate may have at least one corner that is chamfered or notched.

[0029] The thickness of first optical stack 110 can be, for example, 10 μm or more, or 30 μm or more, and, for example, 1000 μm or less, or 500 μm or less.

[0030] Each first optical laminate constituting one first optical laminate stack has an optical axis and includes an optical film (sheet-shaped optical film) derived from a slit film in the same row of slit films obtained by slitting a long optical film into multiple rows along the longitudinal direction. The slit film may be obtained by slitting along the longitudinal direction and the width direction. For example, in the embodiment shown in FIG. 4, a long optical film 30a is slit into six rows B1 to B6 along the longitudinal direction and further slit at predetermined intervals along the width direction. In this embodiment, all of the optical films included in the first optical laminate constituting one first optical laminate stack are derived from any one of the rows B1 to B6.

[0031] Examples of optical films having an optical axis include reflective polarizing elements having a reflection axis (polarization reflection axis) and a transmission axis (polarization transmission axis), absorptive polarizing elements having an absorption axis (polarization absorption axis) and a transmission axis, and phase difference elements having a slow axis and an advanced axis.

[0032] The long optical film may be wound into a roll. The slits may be formed by slitting using a laser or a cutting blade. The term "long" refers to a long and narrow shape having a length that is sufficiently longer than its width, and includes, for example, a long and narrow shape having a length that is 10 times or more, preferably 20 times or more, the length of its width.

[0033] The width of the long optical film may be, for example, 50 mm or more or 100 mm or more, and, for example, 2000 mm or less or 1500 mm or less. The length of the long optical film may be, for example, 100 m or more or 200 m or more, and, for example, 5000 m or less or 3000 m or less.

[0034] The width of the slit film (slit width) may be, for example, 10 mm or more or 20 mm or more, and, for example, 500 mm or less or 300 mm or less. The length of the slit film may be, for example, 1 m or more or 10 m or more, and, for example, 500 m or less or 300 m or less.

[0035] As the long optical film, a stretched film stretched in the longitudinal direction and / or width direction can be preferably used. In such a long optical film, the axial angle in the longitudinal direction has relatively high uniformity, while the axial angle in the width direction may vary due to factors such as necking and bowing. Therefore, in a slit film obtained by slitting along the longitudinal direction, the variation in the axial angle in the width direction can be reduced as the width decreases. Therefore, sheet-like optical films derived from the same row of slit films can be characterized by higher uniformity in the axial angle in the width direction than sheet-like optical films obtained randomly from a long optical film before slitting. In one embodiment, the long optical film is a stretched film stretched in the width direction. Note that the variation in the axial angle in the longitudinal direction can be calculated as the difference between the maximum and minimum values ​​when the axial angle (e.g., the angle of the optical axis when the longitudinal direction or width direction is set to 0°) is measured at any position in the width direction of the target film (e.g., the center in the width direction) over the entire length in the longitudinal direction. Furthermore, the variation in the axial angle in the width direction can be determined by measuring the axial angle at multiple locations at a predetermined interval in the width direction (for example, intervals of 10 mm or less or 50 mm or less) at any position in the longitudinal direction of the target film, and calculating the difference between the maximum and minimum values.

[0036] The variation in the axial angle of a long optical film in the longitudinal direction is preferably 0.5° or less, and may be, for example, 0.05° to 0.5° or 0.1° to 0.3°. The variation in the axial angle of a long optical film in the width direction may be, for example, 0.3° or more, 0.5° or more, or 1° or more, and may be, for example, 5° or less.

[0037] The variation in the axial angle of the slit film in the longitudinal direction is preferably 0.3° or less, and may be, for example, 0.01° to 0.3° or 0.05° to 0.2°. The variation in the axial angle of the slit film in the width direction is preferably smaller than the variation in the axial angle of the long optical film in the width direction. The variation in the axial angle of the slit film in the width direction is preferably 3° or less, and may be, for example, 0.1° to 3° or 0.3° to 2°.

[0038] In one embodiment, all of the optical films (sheet-shaped optical films) included in the first optical laminates constituting one first optical laminate stack are derived from the same slit film. According to such an embodiment, the uniformity of the axis angles of the optical films among the first optical laminates constituting one first optical laminate stack can be further improved.

[0039] The sheet-shaped optical film 30c can be obtained, for example, by cutting the slit film 30b along the width direction as shown in Fig. 5(a). Alternatively, the sheet-shaped optical film 30c can be obtained, for example, by punching the slit film 30b as shown in Fig. 5(b). In this case, the optical film 30c may be punched at an angle so that the angle between the side direction of the rectangular optical film 30c and the direction of the optical axis a is small.

[0040] The first optical laminate may include any optional components in addition to the optical film, depending on the purpose. FIG. 6 is a schematic cross-sectional view showing the configuration of an example of a first optical laminate that can be used in the management method according to an embodiment of the present invention. The first optical laminate 110 includes a reflective polarizing member 30 as the optical film 30c. The first optical laminate 110 further includes a pressure-sensitive adhesive layer 32 arranged on one side of the reflective polarizing member 30. The first optical laminate 110 also includes an absorbing polarizing member 34 and a protective member 36 arranged on the other side of the reflective polarizing member 30. Typically, the reflection axis direction of the reflective polarizing member 30 and the absorption axis direction of the absorbing polarizing member 34 are arranged approximately parallel, and the transmission axis direction of the reflective polarizing member 30 and the transmission direction of the absorbing polarizing member 34 are arranged approximately parallel. A first optical laminate 110 having such a configuration can be suitably used in the reflector 14 of the display system 2 described in Section A. For example, the first optical laminate 110 can function as the reflector 14 in the display system 2 by being integrated with a component on the second retardation member 22 side (the second retardation member or a component (e.g., a lens) arranged between the second retardation member and the reflector) via the pressure-sensitive adhesive layer 32. In the first optical laminate 110, a release liner 38 is bonded to the surface of the pressure-sensitive adhesive layer 32. The release liner 38 can protect the pressure-sensitive adhesive layer 32 and can also form a stack by stacking first optical laminates 110. Although not shown, a surface protection film may be bonded to the surface of the protective member 36.

[0041] The first optical laminate can be obtained, for example, by laminating members having desired shapes, optionally via an adhesive layer. The adhesive layer may be formed of an adhesive or a pressure-sensitive adhesive. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm, preferably 0.5 μm to 20 μm, and more preferably 3 μm to 15 μm.

[0042] <Reflective Polarizing Member> The reflective polarizing member transmits light polarized parallel to its transmission axis (typically, linearly polarized light) while maintaining its polarization state, and can reflect light polarized in other states (typically, light polarized perpendicular to its transmission axis). The reflective polarizing member is typically composed of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing member is, for example, 10 μm to 150 μm, preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

[0043] FIG. 7 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure L has alternating birefringent layers A and substantially non-birefringent layers B. The total number of layers constituting the multilayer structure may be 50 to 1,000. For example, the refractive index nx in the x-axis direction of layer A is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of layer B and the refractive index ny in the y-axis direction are substantially the same, and the refractive index difference between layer A and layer B is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction can be the reflection axis, and the y-axis direction can be the transmission axis. The refractive index difference between layer A and layer B in the x-axis direction is preferably 0.2 to 0.3.

[0044] The A layer is typically made of a material that exhibits birefringence upon stretching. Examples of such materials include naphthalenedicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (e.g., polymethyl methacrylate). The B layer is typically made of a material that does not substantially exhibit birefringence upon stretching. Examples of such materials include copolyesters of naphthalenedicarboxylic acid and terephthalic acid. The multilayer structure can be formed by a combination of coextrusion and stretching. For example, the materials constituting the A layer and the B layer are extruded and then multilayered (e.g., using a multiplier). The resulting multilayer laminate is then stretched. The x-axis direction in the illustrated example may correspond to the stretching direction.

[0045] Commercially available reflective polarizing films include, for example, "DBEF" and "APF" manufactured by 3M, and "APCF" manufactured by Nitto Denko Corporation.

[0046] The crossed transmittance (Tc) of the reflective polarizing element (reflective polarizing film) can be, for example, 0.001% to 3%. The single transmittance (Ts) of the reflective polarizing element (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing element (reflective polarizing film) can be, for example, 92% to 99.99%.

[0047] The crossed transmittance, single transmittance, and degree of polarization can be measured, for example, using an ultraviolet-visible spectrophotometer. The degree of polarization P can be calculated from the obtained Tp and Tc by measuring the single transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc using an ultraviolet-visible spectrophotometer, using the following formula: Ts, Tp, and Tc are Y values ​​measured using a 2-degree visual field (C light source) according to JIS Z 8701 and corrected for visibility. Degree of polarization P (%) = {(Tp - Tc) / (Tp + Tc)} １／２ ×100

[0048] <Absorptive Polarizing Member> The absorptive polarizing member typically includes a film containing a dichroic material (sometimes referred to as an absorptive polarizing film). The absorptive polarizing member may further include a protective layer on one or both sides of the absorptive polarizing film, as necessary. The protective layer is typically attached to the absorptive polarizing film via any suitable adhesive layer. The thickness of the absorptive polarizing film is, for example, 1 μm or more and 20 μm or less, and may be 2 μm or more and 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, or 5 μm or less.

[0049] The crossed transmittance (Tc) of the absorptive polarizing film is preferably 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The single transmittance (Ts) of the absorptive polarizing film is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing film is, for example, 99.0% to 99.997%, and preferably 99.8% or more.

[0050] In one embodiment, the absorptive polarizing film may be formed of a resin film containing a dichroic substance such as iodine or a dichroic dye, etc. Such an absorptive polarizing film may be made of a single-layer resin film or may be made using a laminate of two or more layers.

[0051] When the absorptive polarizing film is produced from a single-layer resin film, for example, an absorptive polarizing film can be obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene-vinyl acetate copolymer-based film to a dyeing treatment with iodine or a dichroic substance such as a dichroic dye, a stretching treatment, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferred.

[0052] The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA-based film may be dyed after stretching. If necessary, the PVA-based film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like.

[0053] Examples of laminates produced using the two or more layer laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, and a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to convert the PVA-based resin layer into an absorptive polarizing film. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may optionally include in-air stretching of the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained through treatment steps in which the laminate is immersed in a liquid, such as dyeing treatment and underwater stretching treatment, etc. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment.The obtained resin substrate / absorptive polarizing film laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the absorptive polarizing film), or any suitable protective layer may be laminated depending on the purpose on the surface obtained by peeling the resin substrate from the resin substrate / absorptive polarizing film laminate or on the surface opposite to the peeled surface. Details of such methods for producing an absorptive polarizing film are described in, for example, JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures of these publications are incorporated herein by reference.

[0054] The protective layer can be formed of any appropriate resin film that can be used as a protective layer for an absorptive polarizing film. Specific examples of the resin that serves as the main component of the resin film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins, polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, cycloolefin-based resins such as polynorbornene, polyolefin-based resins, (meth)acrylic resins, and acetate-based resins.

[0055] The thickness of the protective layer is typically 100 μm or less, for example, 5 μm to 80 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm.

[0056] <Protective Member> The protective member typically includes a substrate. The substrate can be composed of any appropriate film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. Here, (meth)acrylic refers to acrylic and / or methacrylic. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm.

[0057] The protective member is preferably composed of a laminated film having a substrate and a surface treatment layer formed on the substrate. The thickness of the laminated film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and even more preferably 20 μm to 45 μm. The thickness of the surface treatment layer is preferably 0.5 μm to 10 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm.

[0058] The surface treatment layer typically includes a hard coat layer. The hard coat layer is typically formed by applying a hard coat layer-forming material to a substrate and curing the applied layer. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. Examples of the curing mechanism of the curable compound include a thermosetting type and a photocurable type. Examples of the curable compound include a monomer, an oligomer, and a prepolymer. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of the polyfunctional monomer or oligomer include a monomer or oligomer having two or more (meth)acryloyl groups, a urethane (meth)acrylate or a urethane (meth)acrylate oligomer, an epoxy-based monomer or oligomer, and a silicone-based monomer or oligomer.

[0059] The thickness of the hard coat layer is preferably 0.5 μm to 10 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm.

[0060] The surface treatment layer preferably includes a functional layer. The functional layer preferably functions as an antireflection layer. In a preferred embodiment, the surface treatment layer includes the hard coat layer and the antireflection layer in this order from the substrate side. The thickness of the functional layer is preferably 0.05 μm to 10 μm, more preferably 0.1 μm to 5 μm, and even more preferably 0.1 μm to 2 μm.

[0061] <Adhesive Layer> The adhesive layer can be composed of any appropriate adhesive. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and compounding ratio of monomers forming the base resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., it is possible to prepare an adhesive having desired properties according to the purpose. The base resin of the adhesive may be used alone or in combination of two or more types. An acrylic resin is preferably used as the base resin. Specifically, the adhesive layer is preferably composed of an acrylic adhesive.

[0062] For example, the pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition containing a base resin, additives such as a crosslinking agent, and a solvent, followed by drying. The pressure-sensitive adhesive composition may be applied directly to the adherend, or may be applied to a separately prepared substrate such as a base film (e.g., a release liner). Drying is typically performed by heating.

[0063] <Release Liner> The release liner may typically be composed of any suitable plastic film. Specific examples of plastic films include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film. A plastic film whose surface is coated with a release agent is preferably used as the release liner. Examples of the release agent include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.

[0064] The thickness of the release liner is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more, and is, for example, 100 μm or less.

[0065] B-2. Step A2 In step A2, as shown in FIG. 3(b), the first optical laminate stack 110S is slit to obtain a plurality of second optical laminate stacks 120S in which a plurality of second optical laminates 120 are stacked. The second optical laminate 120S may have an elongated rectangular shape in a plan view. The slits are made along a predetermined direction. Preferably, the slits are made along a direction approximately parallel to the first direction of the first optical laminate. The first direction may be, for example, the direction in which the sides of the rectangular first optical laminate extend, and the direction in which the sides that form a small angle with the longitudinal direction of the elongated optical film extend (the long side direction of the rectangular optical film 30c shown in FIGS. 5(a) and 5(b)).

[0066] The width of the second optical laminate (slit width) can be appropriately set depending on the size of the optical laminate piece to be punched out from the second optical laminate, etc. The width of the second optical laminate is, for example, 3 times or less, preferably 1.1 to 2 times, and more preferably 1.2 to 1.5 times the punched width of the optical laminate piece (width D shown in FIG. 9 ). When the slit width is within the above range, it is possible to ensure a punched width equivalent to one or two optical laminate pieces, preferably one optical laminate piece, while significantly reducing the variation in the axial angle of the optical film in the width direction.

[0067] The number of second optical stacks obtained from one first optical stack may be, for example, 2 to 100, or, for example, 3 to 50.

[0068] B-3. ​​Step A3 In step A3, two or more second optical laminates are selected in each of the plurality of second optical laminate stacks, the axial angles of the optical films contained therein are measured, and the axial angle of each second optical laminate stack is set based on the average value of the measured values.

[0069] The number of second optical stacks selected from one second optical stack is typically two or more, for example, 3 to 50, and preferably two (in Figure 3(c) two second optical stacks 120a, 120b are selected from each stack).

[0070] In one embodiment, two second optical laminates including optical films derived from the most distant positions in the longitudinal direction of the long optical film are selected from all the second optical laminates constituting one second optical laminate stack. For example, n first optical laminates constituting one first optical laminate stack are each selected from sheet-like optical films 30c derived in this order from one end of the same slit film 30b to the other end. １ ~30c ｎ When the optical film 30c includes １ Optical laminate and optical film 30c comprising ｎ An optical laminate including the optical film 30c is selected. ２ ~30c ｎ－１ The axis angle of the optical film 30c １ Axis angle and optical film 30c ｎ Since the axial angle of the optical films at both ends is likely to be between the axial angle of the optical films at both ends and the axial angle of the second optical laminate stack can be efficiently set by measuring the axial angles of the optical films at both ends and using the average value. In this embodiment, it is preferable that the first optical laminates in the first optical laminate stack are stacked in the order of the positions from which the optical films originate in the longitudinal direction of the long optical film. With a first optical laminate stack configured in this way, after producing the second optical laminate stack, the desired optical laminate can be easily selected by selecting the top and bottom second optical laminates.

[0071] The axial angle of the optical film included in the second optical laminate can be measured by any appropriate method. For example, for the optical laminate having the configuration shown in FIG. 6, the reflection axis direction of the reflective polarizing member can be measured using a spectrophotometer (e.g., "LPF-200" manufactured by Otsuka Electronics Co., Ltd.). The axial angle is the angle of the optical axis with respect to a reference direction. In step A3, the angle of the optical axis with respect to the side direction (e.g., short side direction) of the second optical laminate can be measured as the axial angle.

[0072] The axial angle of the optical film is measured, for example, in the punching pattern intended for the second optical stack, preferably in two or more, more preferably 2 to 10, for example, two, three, four, or five punched regions of the optical stack pieces, and the average of the measured values ​​can be calculated as the axial angle of the optical film. From the viewpoint of more accurately determining the axial angle of the second optical stack, when measuring the axial angle of the optical film derived from the most distant position in the longitudinal direction of the same slit film, it is preferable to measure the punched region closest to the end. For example, when the second optical stacks 120a and 120b shown in FIG. 3(d) each include optical films derived from both ends of the same slit film in the longitudinal direction, and the axial angle of the punched region for two optical stack pieces is measured, it is preferable to measure the axial angle of the two regions closest to the end (a1 and a2, and b4 and b5) among the five punched regions a1 to a5 and b1 to b5, respectively.

[0073] The axial angle of the second optical laminate stack may be set to the average value of the axial angles of the optical films measured for two or more second optical laminates selected from the stack, or may be set within a range of the average value ± A°. Here, A° is a margin taking into account the axial angles of the optical films in unmeasured second optical laminates, and can be set appropriately depending on the degree of variation in the axial angle in the longitudinal and / or width directions of the long optical film, the width of the second optical laminate stack, etc. From the viewpoint of optimally achieving the effects of the present invention, A is typically Y or less (Y×a or less when the axial angle is classified into the range of X±Y×a°, as described below), for example, 0.5 or less, preferably 0.3 or less, more preferably 0.05 to 0.2, and may be, for example, 0.1. In this manner, the axial angle is set for each of the multiple second optical laminate stacks ( FIG. 3( e) ).

[0074] B-4. Step A4 In step A4, second optical laminate stacks whose set axial angles are within the range of X±Y° are classified into the same group (if the ranges overlap, they may be classified into either group). This makes it possible to efficiently obtain optical laminates whose axial angles are within the range of X±Y°. Y is a value that is appropriately set depending on the tolerance level for axial angle variation, and is set to a smaller value as the requirement for axial accuracy becomes stricter. Y is preferably less than 1, and may be, for example, 0.8 or less, 0.6 or less, or 0.5 or less, or may be, for example, 0.05 or more.

[0075] In one embodiment, second optical laminate stacks having axial angles within the range of X±Y×a° (where a satisfies the relationship of 0.6<a<1, preferably the relationship of 0.65<a<0.95, and more preferably the relationship of 0.7<a<0.9, and may be, for example, 0.8) are classified into the same group. This increases the likelihood that the axial angles of the optical films in the second optical laminate stacks classified into the same group will fall within the range of X±Y°, even if the second optical laminate stacks contain optical films having axial angles within the range of X±Y°. As a result, second optical laminates including optical films having axial angles within the range of X±Y° can be classified into the same group with higher accuracy.

[0076] The X may be a specific value or may include n values ​​that differ by a certain value. More specifically, with reference to FIG. 3(f), X may be a set of X values ​​that differ by a certain value. １ ~X ｎ The second optical stack 120S includes n values ​​up to the axis angle X according to each axis angle. １ ±Y°, X ２ ±Y°, ..., X ｎ－１ ±Y° or X° ｎ The particles can be classified into n groups within the range of ±Y°. From the viewpoint of ease of management, n can be, for example, 2 to 16, preferably 2 to 8, and more preferably 2 to 4.

[0077] The above-mentioned constant value is, for example, 2Y, and from the viewpoint of the precision of the axial angle, it may be, for example, 0.1 to 2.0 (in this case, Y = 0.05 to 1.0), preferably 0.1 to 1.6 (in this case, Y = 0.05 to 0.8), more preferably 0.1 to 1.2 (in this case, Y = 0.05 to 0.6), and even more preferably 0.1 to 1 (in this case, Y = 0.05 to 0.5).

[0078] A specific embodiment of step A4 will be described below with reference to FIG. 8 . In the illustrated example, there are 13 second optical stacks a to m, each having a different average value for the axial angle of the optical film measured for two or more second optical stacks selected from the stack. (1) When the axial angle of the second optical stack is set to the above average value and second optical stacks whose set axial angle is within the range of X±Y° (where X includes X1, X2, and X3) are classified into the same group, second optical stacks a to f are classified into the same group (i.e., the group with an axial angle of X1±Y°), and second optical stacks h to m are classified into the same group (i.e., the group with an axial angle of X2±Y°). Optical stacks whose axial angles fall in the overlapping portion of adjacent ranges may be classified into either group. Thus, second optical stack g may be classified into the group with an axial angle of X1±Y° or the group with an axial angle of X2±Y°. (2) When the axial angle of the second optical laminate stack is set within the range of the above average value ±A°, and second optical laminate stacks whose set axial angle is within the range of X±Y° (where X includes X1, X2, and X3) are classified into the same group, second optical laminate stacks a to e are classified into the same group (i.e., the group with an axial angle of X1±Y°), and second optical laminate stacks i to m are classified into the same group (i.e., the group with an axial angle of X2±Y°). (3) When the axial angle of the second optical stack is set to the above average value and second optical stacks whose set axial angle is within the range of X±Y×0.8° (where X includes X1, X2, and X3) are classified into the same group, second optical stacks a to d are classified into the same group (i.e., the group with an axial angle of X1±Y×0.8°), and second optical stacks j to m are classified into the same group (i.e., the group with an axial angle of X2±Y×0.8°).(4) When the axial angle of the second optical laminate stack is set within the range of the above average value ±A° and second optical laminate stacks whose set axial angle is within the range of X±Y×0.8° (where X includes X1, X2, and X3) are classified into the same group, second optical laminate stacks a to c are classified into the same group (i.e., a group with an axial angle of X1±Y×0.8°), and second optical laminate stacks k to m are classified into the same group (i.e., a group with an axial angle of X2±Y×0.8°). As described above, by providing a margin for the axial angle of the second optical laminate stack and / or setting the classification width of the axial angle narrower than the desired range (i.e., the range of ±Y°), more strict classification can be performed. As a result, it is possible to sufficiently prevent second optical laminates including optical films having axial angles exceeding the desired range from being mixed into second optical laminate stacks classified into the same group. The classification into any of the above embodiments (1) to (4) can be determined appropriately depending on the axial accuracy of the raw optical film, the axial accuracy desired for the optical laminate piece, etc. Furthermore, in the above embodiments (2) to (4), the second optical laminate stack that is not classified into any group may have an axial angle intermediate between two groups whose reference values ​​are adjacent, and therefore may be classified as an intermediate group having an axial angle intermediate between them. For example, in the above embodiment (3), the second optical laminate stacks e to i are classified as a group having an axial angle intermediate between the group of X1±Y×0.8° and the group of X2±Y×0.8°, and can be applied to the subsequent production of optical laminate pieces.

[0079] C. Manufacturing Method of Optical Laminate Piece A manufacturing method of an optical laminate according to an embodiment of the present invention includes: (Step B1) obtaining a group of second optical laminate stacks having axial angles within the range of X±Y° using the optical laminate management method described in Section B; and (Step B2) punching out the second optical laminate stacks included in the same group in the same pattern to obtain optical laminate pieces. As described above, the second optical laminate stacks included in the same group have axial angles of the same level, and the second optical laminates constituting each stack each include an optical film having an axial angle of the same level. Therefore, even when punching out the second optical laminate stacks included in the same group in a constant pattern without changing the punching pattern according to the axial angle of the optical film for each stack or optical laminate, optical laminate pieces with high axial accuracy can be obtained.

[0080] For example, as shown in FIG. 9, the second optical laminated stack 120S has an axial angle (the angle between the short side direction and the optical axis direction) of X １ A group is ±Y°, X ２ Group B is ±Y°, X ３ C group, which is ±Y°, and X ４ When the optical laminate pieces 130 are classified into group D, which is ±Y°, the angle θ between the long axis direction (arrow C direction) of the elliptical optical laminate piece 130 and the short side direction (arrow b direction) of the second optical laminate stack 120S is X, B, C, and D. １ °, X ２ °, X ３ °, and X ４ By punching out the optical laminate piece 130 so that the axial angle with respect to the major axis varies within the range of ±Y°, it is possible to efficiently obtain the optical laminate piece 130.

[0081] The shape of the optical laminate piece can be appropriately set depending on the purpose, and can be, for example, a circle, an ellipse, a rectangle, a rectangle with rounded corners, or the like.

[0082] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose.

[0083] The method for managing an optical laminate according to an embodiment of the present invention can be suitably used in the manufacture of display systems such as VR goggles, for example.

[0084] 2 Display system, 12 Display element, 14 Reflection section, 16 First lens section, 18 Half mirror, 20 First phase difference member, 22 Second phase difference member, 24 Second lens section, 30 Optical film, 110 First optical laminate, 120 Second optical laminate, 130 Optical laminate piece

Claims

1. A method for managing optical stacks, comprising: preparing a first optical stack in which a plurality of sheet-like first optical stacks each including an optical film are stacked, wherein the optical films included in the plurality of first optical stacks have an optical axis and are optical films derived from the same row of slit films obtained by slitting a long optical film into a plurality of rows along the longitudinal direction (step A1); slitting the first optical stack in a predetermined direction to obtain a plurality of second optical stacks in which a plurality of second optical stacks are stacked (step A2); selecting two or more second optical stacks in each of the plurality of second optical stacks, measuring the axial angles of the optical films, and setting the axial angle of each second optical stack based on the average value of the measured axial angles (step A3); and classifying the second optical stacks whose axial angles are within the range of X±Y° into the same group (step A4).

2. The management method described in claim 1, wherein in the first optical laminate stack, all of the optical films contained in the plurality of first optical laminates originate from the same slit film, and in step A3, a second optical laminate is selected that includes optical films originating from the furthest positions in the longitudinal direction of the same slit film.

3. A control method according to claim 1, wherein in step A3, the range of the average value ±A° is set as the axial angle of the second optical laminate stack.

4. The management method according to claim 3, wherein A is 0.

1.

5. The management method described in claim 1, wherein in step A4, the second optical laminate stacks whose axis angles are within the range of X±Y×a° (where a satisfies the relationship 0.6<a<1) are classified into the same group.

6. The management method of claim 1, wherein X includes 2 to 16 values ​​that differ by a fixed value.

7. The management method according to claim 6, wherein the constant value is 0.05 to 0.

2.

8. The management method according to claim 1, wherein the optical film is a reflective polarizing element.

9. The management method according to claim 1, wherein the first optical laminate comprises a reflective polarizing element, an absorptive polarizing element, and a protective element in this order.

10. A method for manufacturing optical laminate pieces, comprising: obtaining a group of second optical laminate stacks having an axial angle within the range of X±Y° by the optical laminate management method described in any one of claims 1 to 9 (step B1); and punching out second optical laminate stacks included in the same group using the same pattern to obtain optical laminate pieces (step B2).

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