Optical film

Abstract

To provide a an optical film which may contribute to improvement in visibility of image display devices.SOLUTION: An optical film according to an embodiment of the present invention comprises at least either of a polarizing member and a retardation member, and the amount of foreign matter with a major axis diameter greater than 50 μm and less than or equal to 150 μm is 10 or less per unit length of 10 mm in a direction perpendicular to a thickness direction of an end face.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical film. [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 widespread. In image display devices, optical members such as polarizing members and phase difference members are generally used to realize image display and to 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. Applications of VR goggles in various situations are being considered, and improvements in visibility such as high resolution are desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-103286 A Summary of the Invention [Problem to be solved by the invention]

[0005] In VR goggles, images are viewed through lenses, so tiny foreign objects inside the VR goggles tend to be easily visible.

[0006] In view of the above, the present invention provides an optical film that can contribute to improving the visibility of an image display device. [Means for solving the problem]

[0007] 1. The optical film according to an embodiment of the present invention is an optical film including at least one of a polarizing member or a retardation member, and the number of foreign particles having a major axis exceeding 50 μm and not exceeding 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face is 10 or less. 2. In the optical film described in 1 above, the number of foreign particles having a major axis exceeding 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face may be 3 or less. 3. In the optical film according to 1 or 2 above, the number of foreign particles having a major axis exceeding 100 μm and not exceeding 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face may be 3 or less. 4. In the optical film according to any one of 1 to 3 above, the amount of foreign matter having a major axis exceeding 15 μm and not exceeding 50 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face may be 60 or less. 5. In the optical film according to any one of 1 to 4 above, the amount of foreign matter having a major axis exceeding 5 μm and not exceeding 15 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face may be 30 or less. 6. In the optical film according to any one of the above items 1 to 5, the foreign matter may include a component derived from a member contained in the optical film. Effect of the Invention

[0008] According to the embodiment of the present invention, it is possible to improve the visibility of an image display device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view illustrating an optical film according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic perspective view for explaining an example of cutting processing. [Diagram 3] FIG. 1 is a schematic diagram showing a general configuration of an example of a display system for VR goggles. [Figure 4] FIG. 2 is a schematic cross-sectional view showing an example of the details of an optical film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the width, thickness, shape, etc. of each part may be shown more diagrammatically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0011] (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 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, the angles include both clockwise and counterclockwise angles relative to a reference direction, so for example, "45°" means ±45°.

[0012] FIG. 1 is a perspective view showing an optical film according to one embodiment of the present invention, showing a state in which a plurality of optical films are stacked. The optical film 2 can be obtained, typically, by cutting the outer peripheral surface of the optical film body into a desired shape in plan view. The end surface 2a of the optical film 2 is a processed surface that has been subjected to cutting processing. For example, from the viewpoint of manufacturing efficiency, cutting can be performed simultaneously on a plurality of optical film bodies. Specifically, cutting can be performed on the plurality of optical film bodies in a stacked state by stacking a plurality of optical film bodies to form an assembly (also called a work). Note that FIG. 1 shows a state after cutting processing has been performed on the work.

[0013] The cutting process is typically performed using a cutting blade. FIG. 2 is a schematic perspective view for explaining an example of the cutting process. A plurality of optical film bodies 3 are stacked to form a workpiece 4. When forming the workpiece 4, each optical film body 3 is cut in advance into any appropriate shape according to the purpose. In the example shown in FIG. 2, the optical film body 3 is cut into a rectangle, but may be cut into other shapes (for example, a circle). The number of optical film bodies 3 forming the workpiece 4 is not particularly limited, and may be, for example, 10 to 200, or may be, for example, 10 to 100. The thickness of the workpiece 4 is, for example, 5 mm to 50 mm.

[0014] In the example shown in FIG. 2, the outer peripheral surface 4a of the workpiece 4 is cut by the cutting part 6 of the cutting tool. Specifically, a cutting blade 8 provided on the cutting part 6 is brought into contact with the outer peripheral surface 4a of the workpiece 4 to cut the outer peripheral surface 4a of the workpiece 4. In the example shown in FIG. 2, the cutting part 6 of the end mill, which is a cutting tool, is rotated on its axis while the end mill is moved along the outer peripheral surface 4a of the workpiece 4 to cut the workpiece 4. The rotation speed of the cutting part 6 is, for example, 1000 rpm to 60000 rpm. The feed speed of the cutting part 6 is, for example, 500 mm / min to 10000 mm / min. The cutting process may be performed over the entire outer peripheral surface 4a of the workpiece 4, or may be selectively performed at a predetermined portion. During cutting, the workpiece 4 may be fixed by a fixture not shown.

[0015] It is preferable that fuzz generated by cutting is removed from the end surface 2a, which is the processed surface of the optical film 2. Specific examples of fuzz include poor cutting or uncut areas. For example, the fuzz may be whisker-like protrusions, some of which are connected to the end surface of the optical film. The fuzz may contain components derived from the materials contained in the optical film.

[0016] The number of foreign particles having a major axis exceeding 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face 2a of the optical film 2 is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0. The number of foreign particles having a major axis exceeding 50 μm and 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face 2a of the optical film 2 is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, and particularly preferably 1 or less. The number of foreign particles having a major axis exceeding 100 μm and 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face 2a of the optical film 2 is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0 or less. The number of foreign matters having a major axis exceeding 50 μm and not exceeding 100 μm per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face 2a of the optical film 2 is preferably not more than 10, more preferably not more than 5, even more preferably not more than 3, and particularly preferably not more than 1. Here, the major axis refers to the longest straight-line distance between any two points on the cross-sectional shape.

[0017] The optical film can be typically applied to an image display device. In the image display device, foreign matter generated from the optical film may affect visibility. Specifically, foreign matter generated from the optical film may be visually recognized as a defect. Removing the fuzz generated by the cutting process can contribute to improving the visibility of the image display device. Specifically, removing the fuzz generated by the cutting process can reduce foreign matter generated from the optical film in the manufacturing process of the image display device or image display panel, thereby suppressing the occurrence of defects. In VR goggles, foreign matter may be magnified and tends to be easily visually recognized as a defect. Therefore, removing the fuzz generated by the cutting process can greatly contribute to improving visibility.

[0018] The amount (number) of foreign matter per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face of the optical film can be obtained by using an adhesive film. Specifically, the amount of foreign matter per unit length can be obtained by counting the number of foreign matter adhering to the adhesive surface of the adhesive film when the adhesive film is attached to the end face of the optical film and peeled off. In one embodiment, as shown in FIG. 1, a plurality of optical films are aligned and stacked so that their end faces are flush with each other, an adhesive film F of a predetermined size is attached to the formed flush surface, and then peeled off, and the number of foreign matter adhering to the adhesive surface of the adhesive film F within a predetermined range is counted, and the counted number is divided by the number of optical films present within the predetermined range. When cutting is performed in a state where a plurality of optical film bodies are stacked, the above-mentioned flush surface can be formed without aligning the optical films after cutting. The above-mentioned counting can be performed, for example, using PartSens manufactured by Intechnos Japan Co., Ltd.

[0019] The peeling force of the adhesive film F used when counting the amount of the above-mentioned foreign matter (for example, the peeling force from a glass plate) may be about 3.5 N / 25 mm.

[0020] The number of foreign particles having a major axis of more than 15 μm and not more than 50 μm per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face of the optical film is preferably not more than 80, more preferably not more than 60, and even more preferably not more than 40. The number of foreign particles having a major axis of more than 15 μm and not more than 50 μm per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face of the optical film may be, for example, 20 or more, or 30 or more.

[0021] The number of foreign particles having a major axis of more than 5 μm and not more than 15 μm per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face of the optical film is preferably not more than 30, more preferably not more than 20, and even more preferably not more than 10. The number of foreign particles having a major axis of more than 5 μm and not more than 15 μm per unit length of 10 mm in the direction perpendicular to the thickness direction of the end face of the optical film may be, for example, 1 or more, or 10 or more.

[0022] As a method for removing the fuzz, any appropriate method capable of achieving the amount of foreign matter described above may be adopted. In one embodiment, the fuzz is removed using tape. By using tape, the fuzz can be removed efficiently. It is preferable to remove the fuzz using tape multiple times. Specifically, it is preferable to remove the fuzz by performing an operation of attaching tape to the cutting surface and peeling it off multiple times.

[0023] The peeling force of the tape used for removal is preferably 2N / 25mm or more, more preferably 3N / 25mm or more. With such a peeling force, fuzz can be removed well. On the other hand, the peeling force of the tape is preferably 10N / 25mm or less, more preferably 5N / 25mm or less. With such a peeling force, the occurrence of defects such as delamination and lifting in the optical film can be suppressed.

[0024] In another embodiment, the machined surface is blown with gas (e.g., air) to remove the fuzz, preferably with pressurized gas.

[0025] The optical film according to the embodiment of the present invention typically includes an optical member such as a polarizing member or a retardation member. The optical film can be used in any suitable image display device. The optical film can be suitably used in, for example, VR goggles.

[0026] FIG. 3 is a schematic diagram showing an outline of an example of a display system of VR goggles, and shows the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing member 14, a first lens unit 16, a half mirror 18, a first λ / 4 member 20, a second λ / 4 member 22, and a second lens unit 24. The reflective polarizing member 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 reflective polarizing member 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first λ / 4 member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14.

[0027] 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 that may be included in the display element 12, and is converted into a first linearly polarized light.

[0028] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into the first circularly polarized light. The first λ / 4 member 20 may be provided integrally with the display element 12.

[0029] The half mirror 18 transmits the light emitted from the display element 12 and reflects the light reflected by the reflective polarizing member 14 toward the reflective polarizing member 14. The half mirror 18 is provided integrally with the first lens portion 16.

[0030] The second λ / 4 member 22 can transmit the light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. The second λ / 4 member 22 may be provided integrally with the first lens portion 16.

[0031] The first circularly polarized light output from the first λ / 4 member 20 passes through the half mirror 18 and the first lens portion 16, and is converted into the second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light output from the second λ / 4 member 22 is reflected toward the half mirror 18 without passing through the reflective polarizing member 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member 14 is the same as the reflection axis of the reflective polarizing member 14. Therefore, the second linearly polarized light incident on the reflective polarizing member 14 is reflected by the reflective polarizing member 14.

[0032] The second linearly polarized light reflected by the reflective polarizing member 14 is converted into the second circularly polarized light by the second λ / 4 member 22, and the second circularly polarized light emitted from the second λ / 4 member 22 passes through the first lens unit 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 unit 16 and is converted into the third linearly polarized light by the second λ / 4 member 22. The third linearly polarized light passes through the reflective polarizing member 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member 14 is the same as the transmission axis of the reflective polarizing member 14. Therefore, the third linearly polarized light incident on the reflective polarizing member 14 passes through the reflective polarizing member 14.

[0033] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 and enters the eye 26 of the user.

[0034] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 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 included in the display element 12 and the slow axis of the first λ / 4 member 20 is, for example, 40° to 50°, may be 42° to 48°, or may be about 45°. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second λ / 4 member 22 is, for example, 40° to 50°, may be 42° to 48°, or may be about 45°.

[0035] The in-plane retardation Re(550) of the first λ / 4 member 20 is, for example, 100 nm to 190 nm, and may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 member 20 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 member 20 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0036] The in-plane retardation Re(550) of the second λ / 4 member 22 is, for example, 100 nm to 190 nm, and may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 member 22 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 member 22 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0037] Although not shown, display system 10 may also include an absorptive polarizer disposed in front of reflective polarizer 14. The reflection axis of the reflective polarizer and the absorption axis of the absorptive polarizer may be disposed approximately parallel to each other.

[0038] The optical film according to an embodiment of the present invention can include, for example, members provided in the above display system. Specifically, the optical film can include polarizing members such as a reflective polarizing member and an absorptive polarizing member. Further, the optical film can include a retardation member such as a λ / 4 member. Furthermore, the optical film can include other members such as a protective member, an adhesive layer for integrating adjacent members, a surface protective film, and a release liner. The thickness of the optical film varies depending on, for example, the types and numbers of the included members, but is, for example, 200 μm to 400 μm.

[0039] FIG. 4 is a schematic cross-sectional view showing an example of the details of the optical film. FIG. 4 can also be a schematic cross-sectional view showing an example of the details of the optical film body before cutting. The optical film 2 includes a first λ / 4 member 20, a polarizing member 12b disposed on one side of the first λ / 4 member 20, and a protective member 30 disposed on the other side of the first λ / 4 member 20. The polarizing member 12b can correspond to the polarizing member that can be included in the above display element (display element 12). An adhesive layer (for example, an adhesive layer) 40 is provided on the side of the polarizing member 12b, and a release liner 50 is bonded to the surface thereof. Further, a surface protective film 60 is bonded to the surface of the protective member 30.

[0040] The first λ / 4 member 20 preferably exhibits a refractive index characteristic of nx > ny ≧ nz. Here, “ny = nz” includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, ny < nz may occur. The Nz coefficient of the first λ / 4 member 20 is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0041] The first λ / 4 member 20 is formed of any suitable material that can satisfy the above characteristics. The first λ / 4 member 20 can be, for example, a stretched film of a resin film or an alignment solidified layer of a liquid crystal compound.

[0042] Examples of the resin contained in the resin film include polycarbonate-based resin, polyester carbonate-based resin, polyester-based resin, polyvinyl acetal-based resin, polyarylate-based resin, cyclic olefin-based resin, cellulose-based resin, polyvinyl alcohol-based resin, polyamide-based resin, polyimide-based resin, polyether-based resin, polystyrene-based resin, and acrylic-based resin. These resins may be used alone or in combination. Examples of the combination method include blending and copolymerization. When the first λ / 4 member 20 exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, sometimes simply referred to as a polycarbonate-based resin) may be suitably used.

[0043] Any suitable polycarbonate-based resin can be used as the polycarbonate-based resin. For example, the polycarbonate-based resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diol, alicyclic dimethanol, di-, tri- or polyethylene glycol, and alkylene glycol or spiro glycol. Preferably, the polycarbonate-based resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or a structural unit derived from a di-, tri- or polyethylene glycol; more preferably, it contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from a di-, tri- or polyethylene glycol. The polycarbonate-based resin may contain a structural unit derived from another dihydroxy compound as necessary. Details of polycarbonate-based resins that can be suitably used for the first λ / 4 member 20 and methods for forming the first λ / 4 member 20 are described, for example, in JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, and JP 2015-212818 A, and the descriptions in these publications are incorporated by reference into this specification.

[0044] The thickness of the first λ / 4 member 20 made of a stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0045] The above-mentioned alignment and solidification layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer, and the alignment state is fixed. The "alignment and solidification layer" is a concept that includes an alignment and solidification layer obtained by solidifying a liquid crystal monomer as described later. In the first λ / 4 member 20, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first λ / 4 member 20 (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it.

[0046] The alignment solidified layer of the liquid crystal compound (liquid crystal alignment solidified layer) can be formed by performing an alignment treatment on the surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. Any appropriate alignment treatment can be adopted as the alignment treatment. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique deposition method and photoalignment treatment. As the treatment conditions of various alignment treatments, any appropriate conditions can be adopted depending on the purpose.

[0047] The alignment of the liquid crystal compound is performed by treating the liquid crystal compound at a temperature at which the liquid crystal compound exhibits a liquid crystal phase according to the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes on a liquid crystal state and is aligned according to the alignment treatment direction of the substrate surface.

[0048] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or crosslinking treatment.

[0049] As the liquid crystal compound, any suitable liquid crystal polymer and / or liquid crystal monomer is used. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of the liquid crystal compound and the method for producing the liquid crystal alignment solidified layer are described in, for example, JP 2006-163343 A, JP 2006-178389 A, and WO 2018 / 123551 A. The descriptions in these publications are incorporated herein by reference.

[0050] The thickness of the first λ / 4 member 20 constituted by the liquid crystal alignment solidified layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and further preferably 1 μm to 4 μm.

[0051] The polarizing member 12b may include, for example, a resin film containing a dichroic material (sometimes referred to as an absorptive polarizing film). 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.

[0052] The absorptive polarizing film may be prepared from a single layer of resin film, or may be prepared using a laminate of two or more layers.

[0053] When preparing 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 an ethylene-vinyl acetate copolymer-based partially saponified film to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, a stretching treatment, etc. Among them, an absorptive polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferable.

[0054] 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 the dyeing is being carried out. Alternatively, the stretching may be followed by dyeing. If necessary, the PVA film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like.

[0055] Examples of the laminate produced using the laminate of two or more layers 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. The 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 coating a PVA-based resin solution on the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer into an absorptive polarizing film. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. The stretching typically includes immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may further include, as necessary, stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the aqueous boric acid 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 air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it is possible to increase the crystallinity of PVA, and to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, problems such as a decrease in the orientation or dissolution of PVA when immersed in water in the subsequent dyeing and stretching steps can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in the 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 a dyeing treatment and an underwater stretching treatment. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through drying shrinkage treatment.The obtained laminate of resin substrate / absorptive polarizing film may be used as it 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 on the peeled surface of the resin substrate / absorptive polarizing film laminate after peeling the resin substrate from the laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of the method for producing such an absorptive polarizing film are described in, for example, JP2012-73580A and JP6470455A. The entire disclosures of these publications are incorporated herein by reference.

[0056] The crossed transmittance (Tc) of the polarizing member (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 polarizing member (absorptive polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The degree of polarization (P) of the polarizing member (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.9% or more.

[0057] 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 visibility. Polarization degree P(%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0058] The protective member 30 typically includes a substrate. The substrate may be made of any appropriate film. Examples of materials that are the main components of the film that constitutes 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 such as polynorbornene, polyolefin-based, (meth)acrylic-based, acetate-based, and other resins. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and further preferably 15 μm to 35 μm.

[0059] The protective member 30 may preferably have a surface treatment layer formed on the substrate in addition to the substrate. The protective member having the surface treatment layer may be disposed so that the substrate is located on the first λ / 4 member 20 side. The surface treatment layer may have any appropriate function. For example, the surface treatment layer preferably has an anti-reflection function. The thickness of the surface treatment layer is preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and further preferably 3 μm to 10 μm.

[0060] Although not shown, a member (so-called positive C plate) whose refractive index characteristics can show the relationship of nz>nx=ny may be provided in the optical film 2 (for example, between the first λ / 4 member 20 and the protective member 30). The positive C plate has a thickness direction retardation Rth(550) of preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, further preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. The positive C plate has an in-plane retardation Re(550) of, for example, less than 10 nm.

[0061] The positive C plate may be formed of any suitable material, but is preferably composed of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods for forming a positive C plate include the liquid crystal compounds and methods for forming the retardation layer described in

[0020] to

[0028] of JP-A-2002-333642. In this case, the thickness of the positive C plate is preferably 0.5 μm to 5 μm.

[0062] The release liner 50 is formed of any suitable resin film. Specific examples of materials that are the main components of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials of the resin film can be used alone or in combination.

[0063] A release treatment layer may be provided on the contact surface of the release liner 50 with the adhesive layer 40. Examples of release treatment agents that form the release treatment layer include silicone-based release treatment agents, fluorine-based release treatment agents, and long-chain alkyl acrylate-based release agents. These can be used alone or in combination. The thickness of the release treatment layer is typically 50 nm or more and 400 nm or less. The thickness of the release liner is, for example, 5 μm or more and 60 μm or less, and preferably 20 μm or more and 45 μm or less. When a release treatment layer is applied, the thickness of the release liner includes the thickness of the release treatment layer.

[0064] A typical example of the surface protection film 60 is a laminate of a base film and an adhesive layer. Materials for forming the base film include polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate-based polymers; (meth)acrylic polymers such as polymethyl methacrylate; and cycloolefin-based polymers such as polynorbornene. These may be used alone or in combination of two or more. The thickness of the base film is, for example, 5 μm or more and 200 μm or less, and preferably 20 μm or more and 100 μm or less.

[0065] Any suitable structure may be adopted as the adhesive layer of the laminate. 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 compounding amount of the crosslinking agent, reaction temperature, reaction time, and the like, an adhesive having desired properties according to the purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more kinds. The base resin is preferably an acrylic resin (specifically, the adhesive layer is preferably composed of an acrylic adhesive). The thickness of the adhesive layer is, for example, 5 μm to 15 μm.

[0066] Although not shown, each member included in the optical film is preferably integrated 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 3 μm to 20 μm, and more preferably 5 μm to 15 μm. EXAMPLES

[0067] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The thickness, retardation value and peel strength were measured by the following measuring methods. <Thickness> The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by JEOL, product name "JSM-7100F"), and the thickness of more than 10 μm was measured using a digital micrometer (manufactured by Anritsu, product name "KC-351C"). <Phase difference value> The phase difference value at each wavelength at 23°C was measured using a Mueller matrix polarimeter (Axometrics, product name "Axoscan"). <Peeling force> The peel strength was measured by laminating a sample cut to a size of 25 mm wide and 150 mm long to a glass plate, and then peeling the sample in the length direction at a peel speed of 300 mm / min and a peel angle of 90° using a universal tensile tester, and measuring the peel strength (N / 25 mm) in an environment of 23°C and 50% RH. The same sample was measured five times, and the average value was calculated.

[0068] [Example 1] (Fabrication of λ / 4 components) Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100° C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 parts by mass (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by mass (0.298 mol), and calcium acetate monohydrate 1.19×10 as a catalyst. -2 Part of mass (6.78×10 -5mol) was charged. After the inside of the reactor was purged with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was started when the inside temperature reached 100 ° C. 40 minutes after the start of the temperature increase, the inside temperature was reached 220 ° C., and while controlling to maintain this temperature, the pressure was reduced and 90 minutes after reaching 220 ° C., the pressure was reduced to 13.3 kPa. Phenol vapor by-produced with the polymerization reaction was led to a reflux condenser at 100 ° C., a small amount of monomer components contained in the phenol vapor were returned to the reactor, and the uncondensed phenol vapor was led to a condenser at 45 ° C. and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were started, and the inside temperature was set to 240 ° C. and the pressure to 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until the specified stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the produced polyester carbonate resin was extruded into water and the strands were cut to obtain pellets.

[0069] The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours, and then a long resin film having a thickness of 135μm was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200mm, setting temperature: 250°C), a chill roll (setting temperature: 120-130°C) and a winder. The obtained long resin film was stretched in the width direction at a stretching temperature of 143°C and a stretching ratio of 2.8 times to obtain a stretched film having a thickness of 47μm. The Re(550) of the obtained stretched film was 143nm, Re(450) / Re(550) was 0.86, and the Nz coefficient was 1.12.

[0070] (Positive C-plate formation) A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (1) (the numbers 65 and 35 in the formula indicate the mole percent of the monomer unit, and are conveniently represented as a block polymer: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a PET substrate that had been subjected to a vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet light to harden the liquid crystal layer, thereby forming a positive C plate with a thickness of 4 μm and an Rth(550) of -100 nm on the substrate. [ka]

[0071] (Creating protective materials) The following hard coat layer forming material was applied to an acrylic film (thickness 40 μm) having a lactone ring structure and heated at 90° C. for 1 minute. After heating, the coating layer was irradiated with a high-pressure mercury lamp with an integrated light intensity of 300 mJ / cm. 2 The coating layer was cured by irradiation with ultraviolet light of 1000 .mu.m to prepare an acrylic film (thickness 44 .mu.m) on which a hard coat layer with a thickness of 4 .mu.m was formed. Next, the following coating solution A for forming an anti-reflection layer was applied onto the hard coat layer using a wire bar, and the applied coating solution was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was then irradiated with a high-pressure mercury lamp with an integrated light quantity of 300 mJ / cm2. 2 The coating was cured by irradiation with ultraviolet light of 1500 nm to form an antireflection layer A having a thickness of 140 nm. Next, the following coating solution B for forming an antireflection layer was applied onto the antireflection layer A using a wire bar, and the applied coating solution was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was irradiated with a high-pressure mercury lamp with an integrated light amount of 300 mJ / cm 2 The coating was cured by irradiation with ultraviolet light of 1000 ohms to form an antireflection layer B having a thickness of 105 nm. In this way, a protective member (thickness: 44 μm) was obtained.

[0072] (Hard Coat Layer Forming Material) A hard coat layer forming material was prepared by mixing 50 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 30 parts of a multifunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100") and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan, "Irgacure 907") and diluting with methyl isobutyl ketone to a solids concentration of 50%.

[0073] (Anti-reflection layer forming coating solution A) 100 parts by weight of a multifunctional acrylate (manufactured by Arakawa Chemical Industries, Ltd., product name "Opstar KZ6728", solid content 20% by weight), 3 parts by weight of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100"), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "OMNIRAD907", solid content 100% by weight) were mixed. The mixture was diluted with butyl acetate as a diluting solvent to a solid content of 12% by weight, and the mixture was stirred to prepare coating solution A for forming an anti-reflection layer.

[0074] (Anti-reflection layer forming coating solution B) 100 parts by weight of a polyfunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #300", solid content 100% by weight), 150 parts by weight of hollow nanosilica particles (manufactured by JGC Catalysts and Chemicals Co., Ltd., trade name "Surulia 5320", solid content 20% by weight, weight average particle diameter 75 nm), 50 parts by weight of solid nanosilica particles (manufactured by Nissan Chemical Industries, Ltd., trade name "MEK-2140Z-AC", solid content 30% by weight, weight average particle diameter 10 nm), 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", solid content 20% by weight), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100% by weight) were mixed. To the mixture was added a mixed solvent of TBA (tertiary butyl alcohol), MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15 as a dilution solvent until the total solids content was 4% by weight, and the mixture was stirred to prepare coating solution B for forming an anti-reflection layer.

[0075] (Preparation of polarizing member) As a thermoplastic resin substrate, a long amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating liquid) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA-based resin made by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, product name "GOHSENEX Z410") in a ratio of 9:1, and dissolving the mixture in water. The above PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130° C. (auxiliary air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained absorptive polarizing film would be the desired value (dyeing process). Next, the piece was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment). Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment). Thereafter, while drying in an oven maintained at about 90° C., it was brought into contact with a SUS heated roll whose surface temperature was maintained at about 75° C. (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%. In this manner, an absorptive polarizing film having a thickness of about 5 μm was formed on the resin substrate. A cycloolefin resin film (thickness: 25 μm) was attached as a protective layer to the surface of the obtained absorptive polarizing film (the surface opposite to the resin substrate) via an ultraviolet-curable adhesive. Specifically, the curable adhesive was applied so that the total thickness was about 1 μm, and the layers were attached using a rolling machine. Thereafter, the adhesive was cured by irradiating it with UV light from the cycloolefin resin film side. Then, the resin substrate was peeled off. This resulted in a polarizing member having a cycloolefin resin film / absorption-type polarizing film structure. The polarizing member had a single transmittance (Ts) of 43.4% and a polarization degree of 99.993%.

[0076] (Formation of adhesive layer) A monomer mixture containing 94.9 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, and 0.1 parts by weight of 2-hydroxyethyl acrylate was charged into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. Furthermore, 0.3 parts by weight of dibenzoyl peroxide as a polymerization initiator was charged together with ethyl acetate for 100 parts by weight of this monomer mixture, and nitrogen gas was introduced while gently stirring to replace the atmosphere in the flask with nitrogen. The liquid temperature in the flask was kept at 60°C and a polymerization reaction was carried out for 7 hours. Next, ethyl acetate was added to the resulting reaction liquid to adjust the solid concentration to 30% by weight, and a solution of an acrylic polymer with a weight average molecular weight (Mw) of 2.2 million was prepared. An acrylic adhesive was prepared by blending 100 parts by weight of the solid content of the obtained acrylic polymer solution with 0.6 parts by weight of a trimethylolpropane / tolylene diisocyanate adduct (product name: Coronate L, manufactured by Tosoh Corporation) and 0.075 parts by weight of a silane coupling agent (product name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.). The obtained acrylic pressure-sensitive adhesive composition was applied to a substrate film and dried to form a pressure-sensitive adhesive layer having a thickness of 12 μm and a pressure-sensitive adhesive layer having a thickness of 15 μm.

[0077] (Production Example 1A: Preparation of Surface Protection Film A) <Acrylic polymer A> In a reaction vessel equipped with a thermometer, a stirrer, a cooler and a nitrogen gas inlet tube, 96.2 parts by mass of 2-ethylhexyl acrylate (2EHA) and 3.8 parts by mass of hydroxyethyl acrylate (HEA) as monomer components, and 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged together with 150 parts by mass of ethyl acetate, and nitrogen gas was introduced while gently stirring at 23°C to perform nitrogen substitution. Thereafter, the liquid temperature was kept at around 65°C and a polymerization reaction was carried out for 6 hours to prepare a solution of acrylic polymer A (concentration 40% by mass). The weight average molecular weight of acrylic polymer A was 540,000.

[0078] <Adhesive composition A> Ethyl acetate was added to the solution of acrylic polymer A to dilute it to a concentration of 20% by mass. 4 parts by mass of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) as a crosslinking agent and 3 parts by mass of dibutyltin dilaurate (1% by mass solution in ethyl acetate) as a crosslinking catalyst (0.03 parts by mass of solids) were added to 500 parts by mass of this solution (100 parts by mass of solids) and stirred to prepare adhesive composition A.

[0079] <Surface protection film A> The adhesive composition A was applied to one side of a substrate (PET film, KOLON's "CE905-38", thickness 38 μm) and then dried to form an adhesive layer (thickness 15 μm). Next, a release liner (Toyobo Co., Ltd., product number TG704) was attached to the surface of the adhesive layer opposite the substrate. Thus, a surface protection film A was obtained.

[0080] (Production Example 1C: Preparation of Surface Protection Film C) Surface protection film C was obtained in the same manner as in Production Example 1A, except that a PET film (Mitsubishi Chemical Corporation, "Part No. T100C38", thickness 38 μm) was used as the substrate and adhesive composition A was applied to its corona-treated surface to form an adhesive layer 5 μm thick.

[0081] (Preparation of laminated film) The positive C plate was attached to the λ / 4 member (stretched film) via an ultraviolet-curing adhesive (thickness after curing: 1 μm) to obtain a retardation member. The protective member (acrylic film with hard coat layer and antireflection layer) was attached to the positive C plate side of the obtained retardation member via the pressure sensitive adhesive layer (thickness: 12 μm). Here, the acrylic film of the protective member was attached to the positive C plate side. Then, the surface protective film A and the surface protective film C were attached to the antireflection layer side of the protective member in this order after peeling off the release liners. Next, the polarizing member was attached to the λ / 4 member side of the retardation member via the above-mentioned adhesive layer (thickness: 12 μm). Here, the lamination was performed so that the angle between the slow axis of the λ / 4 member and the absorption axis of the absorptive polarizing film was 45°. The polarizing member was also attached so that the absorptive polarizing film was located on the λ / 4 member side. Then, the above-mentioned adhesive layer (thickness: 15 μm) was attached to the cycloolefin resin film side of the polarizing member, and a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached. In this way, a laminated film having a thickness of 330 μm was obtained.

[0082] From the obtained laminated film, 20 optical film bodies measuring 50 mm in length and 60 mm in width were punched out, and these were stacked to form a workpiece as shown in Figure 2. The obtained workpiece was fixed with a clamp, and the outer circumferential surface of the workpiece was end milled as shown in Figure 2. The feed speed of the end mill was 1200 mm / min, and the rotation speed was 4500 rpm.

[0083] After cutting, a tape (acrylic adhesive tape with a substrate) with a peel strength of 3.5 N / 25 mm was attached to the cut surface of the workpiece and then peeled off. This operation was continued until no fuzz caused by cutting could be visually confirmed. Thus, an optical film was obtained.

[0084] [Example 2] An optical film was obtained in the same manner as in Example 1, except that in cutting, the rotation speed of the end mill was set to 3000 rpm.

[0085] [Example 3] An optical film was obtained in the same manner as in Example 1, except that in cutting, the rotation speed of the end mill was set to 6000 rpm.

[0086] [Comparative Example 1] After cutting, an optical film was obtained in the same manner as in Example 1, except that the fuzz was not removed using tape.

[0087] [Comparative Example 2] After cutting, an optical film was obtained in the same manner as in Example 2, except that the fuzz was not removed using tape.

[0088] [Comparative Example 3] After cutting, an optical film was obtained in the same manner as in Example 3, except that the fuzz was not removed using tape.

[0089] An adhesive film with a peeling force of 3.5N / 25mm and a size of 30mm x 30mm was attached to the end surface of the optical film of the example and the comparative example. Specifically, the adhesive film was attached to the cutting surface of the workpiece while 20 sheets were stacked. After that, the adhesive film was peeled off from the end surface of the optical film, and the number of foreign objects attached to the adhesive surface of this adhesive film was counted using a surface cleanliness particle monitor (PartSens manufactured by Intechnos Japan Co., Ltd.). Here, the number of foreign objects within a range of 7mm (in the direction of stacking) x 5mm (in the direction of stacking) in the adhesive film was counted, and the counted number was divided by the number of optical films present within a range of 7mm (in the direction of stacking) x 5mm (in the direction of stacking) to convert it into the amount of foreign objects per unit length of 10mm in the direction perpendicular to the thickness direction of the end surface of the optical film. The results are summarized in Table 1.

[0090] [Table 1]

[0091] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the above-described embodiment may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiment, a configuration that provides the same effect, or a configuration that can achieve the same purpose. [Industrial Applicability]

[0092] The optical film according to the embodiment of the present invention can be used in an image display device, and can be suitably used in, for example, VR goggles. [Explanation of symbols]

[0093] 2. Optical Film 4 Work 6 Cutting section 8 cutting blade 10 Display System 12 Display element 14 Reflective polarizing element 16 First lens section 18 Half Mirror 20 First λ / 4 member 22 Second λ / 4 member 24 Second lens section

Claims

1. An optical film including at least one of a polarizing member and a phase difference member, The number of foreign particles having a major axis of more than 50 μm and not more than 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end surface is 10 or less. Optical film.

2. 2. The optical film according to claim 1, wherein the number of foreign particles having a major axis exceeding 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face is 3 or less.

3. 2. The optical film according to claim 1, wherein the number of foreign particles having a major axis of more than 100 μm and not more than 150 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face is 3 or less.

4. 2. The optical film according to claim 1, wherein the number of foreign particles having a major axis of more than 15 μm and not more than 50 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face is 60 or less.

5. 2. The optical film according to claim 1, wherein the number of foreign particles having a major axis of more than 5 μm and not more than 15 μm per unit length of 10 mm in a direction perpendicular to the thickness direction of the end face is 30 or less.

6. The optical film according to claim 1 , wherein the foreign matter includes a component derived from a member contained in the optical film.

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