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

Abstract

To provide a method for managing an optical laminate that can contribute to producing a display system such as a high-definition VR goggle.SOLUTION: The method for managing an optical laminate includes: preparing a first optical laminate stack in which a plurality of sheet-like first optical laminates including optical films are stacked one on another. Therein: the optical films are derived from slit films in the same row among slit films obtained by slitting an elongated optical film having an optical axis into a plurality of rows along a longitudinal direction; 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 one on another; selecting two or more second optical laminates and measuring the axial angle of the optical film in each of these, and setting the axial angle of each second optical laminate stack on the basis of the average value thereof; and classifying, into the same group, second optical laminate stacks whose axial angles are within the range X±Y°.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[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 the performance of the image display (see, for example, Patent Document 1).

[0003] In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized. As VR goggles are being considered for use in a variety of situations, there is a demand for higher resolution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-103286 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[0006] [1]According to one aspect of the present invention, a first optical laminate stack in which a plurality of first optical laminates each including an optical film and being in sheet form are stacked is prepared. Here, the optical films included in the plurality of first optical laminates are optical films derived from the slit films in the same column in the slit film obtained by slitting an optical film having an optical axis and being in a long shape into a plurality of columns along the longitudinal direction (step A1); the first optical laminate stack is slit along a predetermined direction to obtain a plurality of second optical laminate stacks in which a plurality of second optical laminates are stacked (step A2); in each of the plurality of second optical laminate stacks, two or more of the second optical laminates are selected, the axis angle of the optical film is measured, and the axis angle of each second optical laminate stack is set based on the average value thereof (step A3); and the second optical laminate stacks in which the axis angle is within the range of X±Y° are classified into the same group (step A4); a method for managing an optical laminate is provided. [2]In the management method according to [1] above, in the first optical laminate stack, all of the optical films included in the plurality of first optical laminates may be derived from the same slit film, and in step A3, a second optical laminate including the optical film derived from the position most distant in the longitudinal direction of the same slit film may be selected. [3]In the management method according to [1] or [2] above, in step A3, the range of the average value ±A° may be set as the axis angle of the second optical laminate stack. [4]In the management method according to [3] above, A may be 0.1. [5]In the management method according to any one of [1] to [4] above, in step A4, the second optical laminate stacks in which the axis angle is within the range of X±Y×a° (where a satisfies the relationship of 0.6 < a < 1) may be classified into the same group. [6]In the management method according to any one of [1] to [4] above, X may include 2 to 16 values that are different by a certain value each. [7] In the management method described in [6] above, the certain value may be 0.05 to 0.2. [8] In the management method according to any one of the above [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 member, an absorptive polarizing member, and a protective member 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 comprising: obtaining a group of the 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 [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 an optical laminate piece (step B2). [Effects of the Invention]

[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 manufacture of high-definition display systems (for example, VR goggles, etc.). [Brief explanation of the drawings]

[0008] [Figure 1] 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 method for producing an optical laminate piece according to an embodiment of the present invention can be used. [Figure 2] 5A and 5B are schematic diagrams illustrating an example of a punching pattern for an optical laminate piece. [Figure 3] FIG. 2 is a schematic diagram illustrating a management method according to one embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram illustrating an example of a method for producing a slit film. [Figure 5] 1(a) and 1(b) are schematic diagrams illustrating an example of a method for producing a sheet-like optical film. [Figure 6]1 is a schematic cross-sectional view illustrating a configuration of an example of an optical laminate that can be applied to a management method according to an embodiment of the present invention. [Figure 7] FIG. 1 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. [Figure 8] FIG. 10 is a schematic diagram illustrating an example of an embodiment of step A4. [Figure 9] FIG. 4 is a schematic diagram illustrating an example of step B2 of the method for producing an optical laminated piece according to the 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 greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 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) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 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 angles are referred to herein, unless otherwise specified, the angles include both clockwise (+) and counterclockwise (-) angles relative to a reference direction. Thus, for example, "45°" means ±45°. Furthermore, in this specification, "substantially parallel" includes the range of 0°±10°, preferably within the range of 0°±5°. "Substantially perpendicular" includes the range of 90°±10°, preferably within the 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 for an optical laminate piece according to an embodiment of the present invention can be used. FIG. 1 also shows the layout 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 element, a first lens element 16, a half mirror 18, a first retardation element 20, a second retardation element 22, and a second lens element 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 element 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 element 16. The first retardation element 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second retardation element 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 12a for displaying an image. The light emitted from the display surface 12a 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 the 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 element 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element included in the reflecting element 14 is the same as the reflection axis of the reflective polarizing element. Therefore, the second linearly polarized light incident on the reflecting element 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 eye 26 of the user.

[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 reflector 14 may be disposed approximately parallel to each other or approximately perpendicular to each other. The angle 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 retardation member 20 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°. The angle 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 retardation 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 alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 component preferably exhibits inverse dispersion wavelength characteristics 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 alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 component preferably exhibits inverse dispersion wavelength characteristics 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 element and the second phase difference element in this order, then passes through the second phase difference element twice more by being reflected by the reflective polarizing element and reflected again by the half mirror 18, and then passes through the reflective polarizing element and emerges forward, whereby it is viewed by a viewer. Therefore, if the reflection axis direction of the reflective polarizing element 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 axis precision of the reflective polarizing element.

[0024] B. Management method for optical laminate 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. The method for managing an optical stack according to an embodiment of the present invention includes the steps of: (Step A1) preparing a first optical laminate stack in which a plurality of sheet-like first optical laminates each including an optical film are stacked, wherein the optical films included in the plurality of first optical laminates have optical axes and are optical films derived from slit films in the same row among slit films obtained by slitting a long optical film into a plurality of rows along the longitudinal direction; (Step A2) slitting the first optical laminate stack along a predetermined direction to obtain a plurality of second optical laminate stacks each including a plurality of second optical laminates; (Step A3) selecting two or more of the second optical laminates in each of the plurality of second optical laminate stacks, measuring the axial angles of the optical films, and setting the axial angle of each second optical laminate stack based on the average value of the measured axial angles; and (Step A4) classifying the second optical laminate stacks having the axis angles within the range of X±Y° into the same group; Includes. An optical film having an optical axis is generally manufactured in a long, wide shape, and then cut to a desired size, and depending on the application, further punched into small pieces for use. However, an optical film manufactured in a wide width tends 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, by setting a punching pattern according to the distribution of the optical axis a of the optical film throughout the entire optical laminate 110, an optical laminate piece 130 with improved axial accuracy can be obtained. On the other hand, in the above-mentioned display system applications, as the axial accuracy becomes stricter, the allowable axial misalignment range becomes narrower, which results in complex punching patterns and problems in terms of production management. For example, in the example shown in Figure 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 three: +1.0°, +0.8°, and +0.6°, the axial angles of row A2 are three: +0.4°, +0.2°, and 0°, the axial angles of row A3 are three: -0.4°, -0.2°, and 0°, and the axial angles of row A4 are three: -1.0°, -0.8°, and -0.6°, then there are a total of 81 punching patterns for the optical laminate 110, which makes production management complicated. In response to the above problem, the method for managing an optical laminate according to an embodiment of the present invention makes it possible to efficiently obtain an optical laminate having an axial angle within a predetermined range, specifically, an optical laminate having an axial angle within the range of X±Y° when the target value of the axial angle is X°. Furthermore, as will be described in detail in Section C, by punching optical laminates having uniform 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. Process A1 In step A1, as shown in Fig. 3(a), a first optical laminate stack 110S is prepared in which a plurality of first optical laminates 110 each including an optical film and each having a sheet shape are stacked. Typically, a plurality of first optical laminate stacks are prepared. The number of first optical laminate stacks may 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 laminate 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, at least one corner of the rectangular first optical laminate may be 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 among 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 whose length is sufficiently longer than its width, and includes, for example, a long and narrow shape whose length is 10 times or more, preferably 20 times or more, 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) can 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 can 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 is relatively uniform, while the axial angle in the width direction may vary due to factors such as necking and bowing. 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, a sheet-like optical film derived from the same slit film can be characterized by a higher uniformity in the axial angle in the width direction than a sheet-like optical film randomly obtained from a long optical film before slitting. In one embodiment, the long optical film is a stretched film stretched in the width direction. 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, at 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 can 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 can 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 a 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 out the slit film 30b as shown in Fig. 5(b). At this time, the optical film 30c may be punched out 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 stack may include 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 stack that can be used in the management method according to an embodiment of the present invention. The first optical stack 110 includes a reflective polarizing member 30 as the optical film 30c. The first optical stack 110 further includes a pressure-sensitive adhesive layer 32 disposed on one side of the reflective polarizing member 30. The first optical stack 110 also includes an absorptive polarizing member 34 and a protective member 36 disposed 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 absorptive polarizing member 34 are arranged approximately parallel, and the transmission axis direction of the reflective polarizing member 30 and the transmission direction of the absorptive polarizing member 34 are arranged approximately parallel. A first optical stack 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) disposed 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 component> The reflective polarizing element 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 element is typically made of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing element 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 layers A having birefringence and layers B having substantially no birefringence. The total number of layers constituting the multilayer structure may be 50 to 1000. 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 and the refractive index ny in the y-axis direction of layer B 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 corresponds 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 member (reflective polarizing film) can be, for example, 0.001% to 3%. The single transmittance (Ts) of the reflective polarizing member (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing member (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. Note that 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 luminosity. Polarization degree P(%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0048] <Absorptive polarizing material> The absorptive polarizing element typically includes a film containing a dichroic material (sometimes referred to as an absorptive polarizing film). The absorptive polarizing element may further include a protective layer on one or both sides of the absorptive polarizing film, as needed. 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, from 1 μm to 20 μm, and may be from 2 μm to 15 μm, 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 fabricating from a single-layer resin film, an absorptive polarizing film can be obtained by dyeing a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified ethylene-vinyl acetate copolymer film with iodine or a dichroic substance such as a dichroic dye, stretching, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred.

[0052] The dyeing with iodine is carried out, for example, by immersing the PVA 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 stretching may be followed by dyeing. If necessary, the PVA film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc.

[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, or 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 resin substrate 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 and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment by heating 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 in-air auxiliary 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 PVA, even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing and 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 orientation of 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 an absorptive polarizing film obtained by immersing the laminate in a liquid through treatment steps such as dyeing and underwater stretching. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through 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 absorptive polarizing films are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0054] The protective layer may 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 materials> The protective member typically includes a substrate. The substrate can be made 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 heat curing and photocuring. Examples of the curable compound include monomers, oligomers, and prepolymers. 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, from the substrate side, the hard coat layer and the antireflection layer in this order. 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 pressure-sensitive adhesive layer can be composed of any appropriate pressure-sensitive adhesive. Specific examples include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, epoxy pressure-sensitive adhesives, and polyether pressure-sensitive adhesives. By adjusting the type, number, combination, and compounding ratio of monomers forming the base resin of the pressure-sensitive adhesive, as well as the compounding amount of cross-linking agent, reaction temperature, reaction time, etc., a pressure-sensitive adhesive having desired properties according to the purpose can be prepared. The base resin of the pressure-sensitive 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 pressure-sensitive adhesive layer is preferably composed of an acrylic pressure-sensitive 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 made 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. Process 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, each of which includes a plurality of second optical laminates 120 stacked on top of one another. The second optical laminate 120S may have a long, narrow rectangular shape in a plan view. The slits are formed along a predetermined direction. Preferably, the slits are formed along a direction substantially 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 which forms a small angle with the longitudinal direction of the elongated optical film (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. 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 is, for example, 2 to 100, or, for example, 3 to 50.

[0068] B-3.Process A3 In step A3, in each of the multiple second optical stacks, two or more second optical stacks are selected, the axial angles of the optical films contained therein are measured, and the axial angle of each second optical stack is set based on the average value of those 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 2 (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 30c1 to 30c2 derived in this order from one end of the same slit film 30b toward the other end. n When the optical film 30c1 is included, the optical laminate including the optical film 30c1 and the optical film 30c n The optical laminate including the optical films 30c2 to 30c is selected. n-1 The axial angle of the optical film 30c1 is equal to the axial angle of the optical film 30c nSince 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 relative to a reference direction. In step A3, the angle of the optical axis relative 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 laminate, preferably in two or more, more preferably 2 to 10, e.g., two, three, four, or five, punched regions of the optical laminate 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 laminate stack, when measuring the axial angle of the optical film originating from the furthest 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 laminates 120a and 120b shown in FIG. 3(d) each include optical films originating from both ends of the same slit film in the longitudinal direction and the axial angle of the punched region for two optical laminate 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 may be appropriately set 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.Process 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 allows optical laminates whose axial angles are within the range of X±Y° to be efficiently obtained. 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, a second optical laminate stack with an axis angle within the range of X ± Y × a° (where a satisfies the relationship 0.6 < a < 1, preferably 0.65 < a < 0.95, more preferably 0.7 < a < 0.9, and can be, for example, 0.8) is classified into the same group. Thus, even if there is an optical film having an axis angle deviation exceeding the above margin in the second optical laminate stack, in the second optical laminate stack classified into the same group, the axis angle of the optical film is likely to fall within the range of X ± Y°. As a result, the second optical laminate including an optical film with an axis angle within the range of X ± Y° can be classified into the same group with higher accuracy.

[0076] The above X may be a specific single value or may include n values that differ by a certain value. More specifically, referring to FIG. 3(f), X includes n values from X1 to X n up to, and a plurality of second optical laminate stacks 120S can be classified into n groups with axis angles within the ranges of X1 ± Y°, X2 ± Y°, ···, X n-1 ± Y°, or X n ± Y°. From the perspective of ease of management, n can be, for example, 2 to 16, preferably 2 to 8, more preferably 2 to 4.

[0077] The above certain value is, for example, 2Y, and from the perspective of the accuracy of the axis angle, it can 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 still 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 laminate stacks a to m in which the average values of the axis angles of the optical films measured for two or more second optical laminates selected from the stack are different from each other. (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., a group with an axial angle of X1±Y°), and second optical laminate stacks i to m are classified into the same group (i.e., a group with an axial angle of X2±Y°). (3) When the axial angle of the second optical laminate stack is set to the above average value and the 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 d are classified into the same group (i.e., the group with an axial angle of X1±Y×0.8°), and second optical laminate 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 the 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, the second optical laminate stacks a to c are classified into the same group (i.e., the group with an axial angle of X1±Y×0.8°), and the second optical laminate stacks k to m are classified into the same group (i.e., the group with an axial angle of X2±Y×0.8°). As described above, by providing a margin for the axis angle of the second optical laminate stack and / or by setting the classification width of the axis angle narrower than the desired range (i.e., the range of ±Y°), more precise classification can be performed. As a result, it is possible to sufficiently prevent second optical laminates including optical films having axis angles outside the desired range from being mixed into second optical laminate stacks classified in 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, and the like. In the above embodiments (2) to (4), the second optical laminate stack that is not classified into any group may have an axis angle intermediate between two groups whose reference values ​​are adjacent, and therefore may be classified into an intermediate group having an axis angle intermediate therebetween. For example, in the above embodiment (3), the second optical laminate stacks e to i are classified into a group having an axis angle intermediate between the group of X1±Y×0.8° and the group of X2±Y×0.8°, and may be applied to the subsequent production of optical laminate pieces.

[0079] C. Method for manufacturing optical laminate pieces A method for producing an optical laminate according to an embodiment of the present invention includes: (Step B1) Obtaining a group of second optical laminate stacks having an axis angle within the range of X±Y° by the optical laminate management method described in A; and (Step B2) punching a second optical laminate stack included in the same group with the same pattern to obtain an optical laminate piece; Includes. As described above, the second optical laminate stacks included in the same group have the same level of axial angles, and the second optical laminates constituting each stack each include an optical film having the same level of axial angle. Therefore, for the second optical laminate stacks included in the same group, even when punching is performed using 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 Figure 9, if the second optical laminate stack 120S is classified into group A where the axial angle (angle between the short side direction and the optical axis direction) is X1±Y°, group B where X2±Y°, group C where X3±Y°, and group D where X4±Y°, by punching out elliptical optical laminate pieces 130 for groups A, B, C, and D so that the angle θ between their long axis direction (direction of arrow c) and the short side direction (direction of arrow b) of the second optical laminate stack 120S is X1°, X2°, X3°, and X4°, respectively, optical laminate pieces 130 whose axial angle variation with respect to the long axis direction is within ±Y° can be efficiently obtained.

[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. [Industrial Applicability]

[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. [Explanation of symbols]

[0084] 2 display system, 12 display element, 14 reflecting portion, 16 first lens portion, 18 half mirror, 20 first phase difference member, 22 second phase difference member, 24 second lens portion, 30 optical film, 110 first optical laminate, 120 second optical laminate, 130 optical laminate piece

Claims

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

2. In the first optical laminate stack, all of the optical films included in the plurality of first optical laminates are derived from the same slit film; The management method according to claim 1 , wherein in step A3, a second optical laminate including the optical films derived from the most distant positions in the longitudinal direction of the same slit film is selected.

3. The management 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 laminated 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 according to 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 includes a reflective polarizing member, an absorptive polarizing member, and a protective member in this order.

10. A method for manufacturing an optical laminate piece, comprising: Obtaining a group of the second optical stacks having an axis angle within the range of X±Y° by the method for managing optical stacks according to any one of claims 1 to 9 (step B1); and A second optical laminate stack included in the same group is punched out in the same pattern to obtain an optical laminate piece (step B2); A manufacturing method comprising:

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