Optical film with surface protection film and method for inspecting optical film

Abstract

Provided is an optical film with a surface protection film, the optical film comprising an optical film and a surface protection film layer disposed on one side of the optical film. The surface protection film layer includes two or more surface protection films, each including a base material and an adhesive layer. In the optical film with the surface protection film, the peeling force P1, with respect to the optical film, of the innermost-layer surface protection film of the surface protection film layer disposed closest to the optical film, and the peeling force P2, with respect to the surface protection film adjacent thereto, of the outermost-layer surface protection film disposed on an outermost side of the surface protection film layer satisfy the relationship of formula (1). (1) P2 ≤ 3.5 × P1

Description

Optical film with surface protection film and method for inspecting optical film

[0001] The present invention relates to an optical film with a surface protective film and an inspection method for the optical film.

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

[0003] In recent years, new applications of image display devices have been developed. For example, goggles with displays (VR goggles) for realizing virtual reality (VR) have begun to be commercialized. In VR goggles, an image displayed on a display panel is enlarged for viewing by a viewer, and therefore, optical films used in VR goggles require stricter defect control than optical films used in conventional image display devices.

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

[0005] As described above, optical films used in VR goggles require strict defect control, and therefore, precise defect inspections using automated optical inspection (AOI) are performed. Meanwhile, it is preferable that the surface of the optical film be protected until it is subjected to the final assembly process. Therefore, a primary object of the present invention is to provide an optical film with a surface protective film that can be suitably inspected for defects while protected by the surface protective film.

[0006] [1] According to one aspect of the present invention, there is provided an optical film with a surface protective film, comprising an optical film and a surface protective film layer arranged on one side of the optical film, wherein the surface protective film layer includes two or more surface protective films each having a substrate and a pressure-sensitive adhesive layer, and wherein a peel force P1 of an innermost surface protective film arranged closest to the optical film in the surface protective film layer, and a peel force P2 of an outermost surface protective film arranged on the outermost side of the surface protective film layer, from the optical film, satisfy the relationship of the following formula (1): P2≦3.5×P1. [2] In the optical film with surface protective films described in [1] above, the surface protective film layer may be composed of the innermost-layer surface protective film, an intermediate surface protective film, and the outermost-layer surface protective film, and the peel force P2 of the outermost-layer surface protective film from the intermediate surface protective film and the peel force P3 of the intermediate surface protective film from the innermost-layer surface protective film may satisfy the relationships of formula (2): P2≦2.5×P3 and formula (3): P3≦2×P1. [3] In the optical film with surface protective films described in [1] or [2] above, the ratio (T1 / T2) of the thickness T1 of the innermost-layer surface protective film to the thickness T2 of the outermost-layer surface protective film may be 1.03 or more. [4] In the optical film with surface protective films described in any one of [1] to [3] above, the bending strength of the substrate of the innermost-layer surface protective film at 23°C may be equal to or greater than the bending strength of the substrate of the outermost-layer surface protective film at 23°C. [5] In the optical film with a surface protective film according to any one of [1] to [4] above, the surface of the optical film on the side of the surface protective film layer may be an antireflection layer. [6] In the optical film with a surface protective film according to any one of [1] to [5] above, the surface of the optical film on the side of the surface protective film layer may have a water contact angle of 80° or more.[7] According to another aspect of the present invention, there is provided a method for inspecting an optical film, comprising peeling off the outermost surface protective film from an optical film with a surface protective film described in any one of [1] to [6] above to obtain the optical film protected by at least the innermost surface protective film, and subjecting the optical film protected by at least the innermost surface protective film to defect inspection.

[0007] According to an embodiment of the present invention, a surface protective film layer including two or more surface protective films is disposed on one side of an optical film, and the peel strength of the innermost surface protective film relative to the optical film and the peel strength of the outermost surface protective film relative to the adjacent surface protective film are adjusted to satisfy a predetermined relationship. This can prevent the innermost surface protective film from being simultaneously peeled off when the outermost surface protective film is peeled off. With such an optical film with a surface protective film, peeling off the outermost surface protective film can suitably obtain an optical film located inside the outermost surface protective film and protected by the surface protective film that is prevented from adhesion of scratches, dirt, and the like. Even when such an optical film protected by a clean surface protective film is subjected to defect inspection as is, false detection of defects caused by the surface protective film can be prevented.

[0008] FIG. 1 is a schematic diagram showing the general configuration of an example of a display system to which the optical film with a surface protective film according to an embodiment of the present invention can be applied. FIG. 2 is a schematic cross-sectional view showing the general configuration of the optical film with a surface protective film according to one embodiment of the present invention. FIG. 3 is a schematic cross-sectional view illustrating an example of the configuration of an optical film applicable to the optical film with a surface protective film according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view illustrating an example of the configuration of an optical film applicable to the optical film with a surface protective film according to an embodiment of the present invention. FIG. 5 is a schematic plan view illustrating a method for measuring the peel force of a surface protective film. FIG. 6 is a schematic side view illustrating a method for measuring the peel force of a surface protective film. FIG. 7 is a schematic plan view illustrating a peel test method.

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

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

[0011] A. Display System FIG. 1 is a schematic diagram showing the overall configuration of an example of a display system to which the optical film with a surface protective film according to an embodiment of the present invention can be applied. 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 member, a first lens unit 16, a half mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens unit 24. The reflector 14 is disposed in front of the display surface 12a of the display element 12 and can reflect light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflector 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first phase difference member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference member 22 is disposed on the optical path between the half mirror 18 and the reflector 14.

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

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

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

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

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

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

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

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

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

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

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

[0023] As described above, in the display system 2, light representing an image emitted forward from the display surface 12a of the display element 12 is magnified by the first lens unit and the second lens unit and can be viewed by a viewer. Optical films used in such display systems require stricter defect management than conventional image display devices. For example, the defect size allowed for the optical film used in the display system may be, for example, 80 μm or less, 50 μm or less, or 30 μm or less, or may be, for example, 5 μm or more, or 10 μm or more.

[0024] B. Optical Film with Surface Protective Film An optical film with a surface protective film according to an embodiment of the present invention includes an optical film and a surface protective film layer disposed on one side of the optical film. The surface protective film layer includes two or more surface protective films (hereinafter sometimes referred to as "PFs") each having a substrate and a pressure-sensitive adhesive layer. Typically, the peel force P1 of the PF (hereinafter sometimes referred to as the "innermost layer PF") disposed on the innermost side (closest to the optical film) of the surface protective film layer from the optical film and the peel force P2 of the PF (hereinafter sometimes referred to as the "outermost layer PF") disposed on the outermost side (opposite the optical film) of the surface protective film layer from the adjacent PF satisfy the relationship shown in formula (1). P1 and P2 preferably satisfy the relationship shown in formula (1a) or (1b). Furthermore, P1 and P2 may satisfy the relationship shown in formula (1c) or (1d). When P1 and P2 satisfy such a relationship, simultaneous peeling of the innermost layer PF when peeling the outermost layer PF can be suitably suppressed. P2≦3.5×P1 (1) P2≦3×P1 (1a) P2≦2.5×P1 (1b) P2≧0.9×P1 (1c) P2≧1×P1 (1d)

[0025] FIG. 2 is a schematic cross-sectional view showing the general configuration of an optical film with a surface protective film according to one embodiment of the present invention. The optical film with a surface protective film 100A includes an optical film 50 and a surface protective film layer 60 disposed on one side of the optical film 50. The surface protective film layer 60 is composed of an innermost layer PF 62 disposed on the innermost side and an outermost layer PF 64 disposed on the outermost side. The innermost layer PF 62 and the outermost layer PF 64 each have a substrate 62a, 64a and a pressure-sensitive adhesive layer 62b, 64b. In the optical film with a surface protective film 100A, the innermost layer PF 62 is the PF adjacent to the outermost layer PF 64, and the peel force of the outermost layer PF 64 from the innermost layer PF 62 is a peel force P2. The peel force of the innermost layer PF 62 from the optical film 50 is a peel force P1.

[0026] FIG. 3 is a schematic cross-sectional view showing the general configuration of an optical film with a surface protective film according to another embodiment of the present invention. The optical film with a surface protective film 100B includes an optical film 50 and a surface protective film layer 60 disposed on one side of the optical film 50. The surface protective film layer 60 is composed of an innermost layer PF 62 disposed on the innermost side, an outermost layer PF 64 disposed on the outermost side, and an intermediate PF 66 disposed therebetween. The intermediate PF 66 has a substrate 66a and a pressure-sensitive adhesive layer 66b. Typically, the peel strength P1 of the innermost layer PF 62 from the optical film 50 and the peel strength P2 of the outermost layer PF 64 from the intermediate PF 66 satisfy the relationship of formula (1) above. P1 and P2 preferably satisfy the relationship of formula (1a) or (1b) above. Alternatively, P1 and P2 may satisfy the relationship of formula (1c) or (1d) above. Furthermore, the peel forces P3 and P2 of the intermediate PF 66 against the innermost layer PF 62 preferably satisfy the relationship of the following formula (2), more preferably the relationship of the following formula (2a) and / or (2b). P3 and P1 preferably satisfy the relationship of the following formula (3), more preferably the relationship of the following formula (3a) and / or (3b). When P1 to P3 satisfy such relationships, simultaneous peeling of the innermost layer PF when peeling the intermediate PF can be suitably suppressed, in addition to simultaneous peeling of the innermost layer PF and / or intermediate PF when peeling the outermost layer PF. P2≦2.5×P3 (2) P2≦2.3×P3 (2a) P2≧2×P3 (2b) P3≦2×P1 (3) P3≦1.5×P1 (3a) P3≧0.9×P1 (3b)

[0027] The peel force P1 of the innermost layer PF to the optical film may be, for example, 0.06 N / 25 mm or less, 0.055 N / 25 mm or less, or 0.05 N / 25 mm or less. The peel force P1 may be, for example, 0.02 N / 25 mm or more, 0.025 N / 25 mm or more, or 0.03 N / 25 mm or more.

[0028] The peel force P2 of the outermost layer PF from the adjacent PF can be set to satisfy the above formula (1), preferably at least one of (1a) to (1d). The peel force P2 may be, for example, 0.21 N / 25 mm or less, 0.18 N / 25 mm or less, or 0.15 N / 25 mm or less. The peel force P2 may be, for example, 0.018 N / 25 mm or more, 0.02 N / 25 mm or more, or 0.022 N / 25 mm or more.

[0029] The peel force P3 of the intermediate PF relative to the innermost layer PF can be set to satisfy, for example, the above formulas (2) and / or (3), preferably (2a), (2b), (3a), and / or (3b). The peel force P3 may be, for example, 0.12 N / 25 mm or less, 0.11 N / 25 mm or less, or 0.09 N / 25 mm or less. The peel force P3 may be, for example, 0.007 N / 25 mm or more, 0.008 N / 25 mm or more, or 0.018 N / 25 mm or more.

[0030] The peel strengths P1 to P3 were measured under conditions of 23° C. and 50% RH at a peel angle of 180° and a peel speed of 300 mm / min.

[0031] [Surface Protective Film Layer] The surface protective film layer includes two or more PFs. The number of PFs included in the surface protective film layer can be selected depending on the purpose, and is preferably two or three. For example, in the embodiment shown in FIG. 2, the surface protective film layer 60 is composed of an innermost layer PF 62 and an outermost layer PF 64, and includes two PFs. Also, for example, in the embodiment shown in FIG. 3, the surface protective film layer 60 is composed of an innermost layer PF 62, an intermediate PF 66, and an outermost layer PF 64, and includes three PFs. Each PF has a substrate and a pressure-sensitive adhesive layer provided on one side thereof, and can be attached to an adjacent member via the pressure-sensitive adhesive layer. Note that the PFs are processing members that are temporarily attached (temporarily attached) to the optical film and are peeled off and removed when the optical film is used.

[0032] The haze of each PF included in the surface protective film layer is, for example, 10% or less, preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less, and typically 0.05% or more. In particular, the haze of the PF (e.g., the innermost PF, intermediate PF) disposed inside the outermost PF is preferably low, for example, 5% or less. When the haze of the PF disposed inside the outermost PF is low, the optical film can be subjected to precise defect inspection while protected by the PF.

[0033] The total light transmittance of each PF included in the surface protective film layer is, for example, 80% or more, preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. In particular, the total light transmittance of the PF (e.g., the innermost PF, intermediate PF) arranged inside the outermost PF is preferably high, and can be, for example, 85% or more. When the total light transmittance of the PF arranged inside the outermost PF is high, the optical film can be subjected to precise defect inspection while protected by the PF.

[0034] The thickness of the PF contained in the surface protection film layer is, for example, 15 μm to 250 μm, preferably 30 μm to 150 μm, and more preferably 40 μm to 100 μm.

[0035] In one embodiment, the ratio (T1 / T2) of the thickness T1 of the innermost layer PF to the thickness T2 of the outermost layer PF may be 1.03 or greater, for example, 1.03 to 1.2 or 1.2 to 1.5. When the ratio (T1 / T2) is within the above range, simultaneous peeling of the innermost layer PF when peeling the outermost layer PF can be suitably suppressed.

[0036] Any appropriate resin film can be selected as the substrate constituting the PF. Specific examples of materials that serve as the main component of the resin film include transparent resins such as cycloolefin (COP)-based resins such as polynorbornene-based resins, polyester-based resins such as polyethylene terephthalate (PET), cellulose-based resins such as triacetyl cellulose (TAC), polycarbonate (PC), (meth)acrylic resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, polyolefin-based resins, and acetate-based resins. Also included are thermosetting or ultraviolet-curing resins such as (meth)acrylic resins, urethane-based resins, (meth)acrylic urethane-based resins, epoxy-based resins, and silicone-based resins. Note that "(meth)acrylic resin" refers to acrylic resins and / or methacrylic resins. Other examples include glassy polymers such as siloxane-based polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include resin compositions containing a thermoplastic resin having a substituted or unsubstituted imide group in its side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in its side chain, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition. The resin film materials can be used alone or in combination.

[0037] The substrate preferably contains at least one transparent resin selected from the group consisting of COP, PET, TAC, PC, and (meth)acrylic resins, more preferably at least one transparent resin selected from the group consisting of COP, PET, PC, and (meth)acrylic resins, and even more preferably at least one transparent resin selected from the group consisting of COP, PET, and PC. When the substrate contains the transparent resin, false detections due to PF in defect inspection can be more stably reduced.

[0038] The substrate may contain an antioxidant, an ultraviolet absorber, a light stabilizer, a nucleating agent, a filler, a pigment, a surfactant, an antistatic agent, etc. The surface of the substrate (the surface opposite to the pressure-sensitive adhesive layer) may be provided with an easy-adhesion layer, an easy-slip layer, an antiblocking layer, an antistatic layer, an antireflection layer, an oligomer prevention layer, etc.

[0039] The flexural strength of the substrate at 23° C. is, for example, 40 MPa to 200 MPa, preferably 50 MPa to 180 MPa, and more preferably 60 MPa to 150 MPa. The flexural strength can be measured, for example, by a method in accordance with ISO178 and JIS K7171.

[0040] The ratio (E1 / E2) of the bending strength E1 of the substrate constituting the innermost layer PF to the bending strength E2 of the substrate constituting the outermost layer PF is, for example, 1 or more, preferably 1.1 to 1.4, such as 1.1 to 1.2 or 1.2 to 1.4. The ratio (E1 / E3) of the bending strength E1 of the substrate constituting the innermost layer PF to the bending strength E3 of the substrate constituting the intermediate PF is, for example, 1 or more, preferably 1 to 1.17, such as 1 to 1.05, 1.05 to 1.09, or 1.09 to 1.17. The ratio (E3 / E2) of the bending strength E3 of the substrate constituting the intermediate PF to the bending strength E2 of the substrate constituting the outermost layer PF is, for example, 1 or more, preferably 1.1 to 1.4, such as 1.1 to 1.2 or 1.2 to 1.4. Simultaneous peeling can be suitably suppressed when the substrate of the PF to be peeled has flexibility equal to or greater than that of the substrate of the remaining PF.

[0041] The thickness of the substrate is typically 5 μm or more, preferably 20 μm or more, and typically 100 μm or less, preferably 80 μm or less.

[0042] The adhesive layer constituting the PF may be composed of any suitable adhesive. The adhesive constituting the adhesive layer typically contains at least one adhesive selected from the group consisting of (meth)acrylic adhesives, urethane adhesives, and silicone adhesives. Preferably, the adhesive layer contains a (meth)acrylic adhesive.

[0043] The (meth)acrylic pressure-sensitive adhesive contains a polymer (hereinafter referred to as a (meth)acrylic polymer) of a monomer component mainly composed of alkyl(meth)acrylate. In other words, the (meth)acrylic polymer contains structural units derived from alkyl(meth)acrylate. The content of the structural units derived from alkyl(meth)acrylate in the (meth)acrylic polymer is typically 50% by weight or more, preferably 80% by weight or more, more preferably 93% by weight or more, and for example, 100% by weight or less, preferably 98% by weight or less.

[0044] The alkyl group in the alkyl (meth)acrylate may be linear or branched. The number of carbon atoms in the alkyl group is, for example, 1 or more and 18 or less. Examples of the alkyl group include a methyl group, an ethyl group, a butyl group, a 2-ethylhexyl group, a decyl group, an isodecyl group, and an octadecyl group. The alkyl (meth)acrylates can be used alone or in combination. The average number of carbon atoms in the alkyl group is preferably 3 to 10.

[0045] The (meth)acrylic polymer may contain, in addition to the structural unit derived from the alkyl (meth)acrylate, a structural unit derived from a copolymerizable monomer polymerizable with the alkyl (meth)acrylate. Examples of the copolymerizable monomer include a carboxyl group-containing monomer and a hydroxyl group-containing monomer. The copolymerizable monomers can be used alone or in combination.

[0046] The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, maleic acid, fumaric acid, and crotonic acid, and preferably (meth)acrylic acid. When the (meth)acrylic polymer contains a structural unit derived from the carboxyl group-containing monomer, the adhesive properties of the pressure-sensitive adhesive layer can be improved. When the (meth)acrylic polymer contains a structural unit derived from the carboxyl group-containing monomer, the content of the structural unit derived from the carboxyl group-containing monomer is preferably 0.01 wt% or more and 10 wt% or less.

[0047] The hydroxyl group-containing monomer is a compound that contains a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. Preferred examples include 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, and more preferred examples include 2-hydroxyethyl (meth)acrylate. When the (meth)acrylic polymer contains structural units derived from the hydroxyl group-containing monomer, the durability of the pressure-sensitive adhesive layer can be improved. When the (meth)acrylic polymer contains structural units derived from the hydroxyl group-containing monomer, the content of the structural units derived from the hydroxyl group-containing monomer in the (meth)acrylic polymer is preferably 0.01 wt % or more and 10 wt % or less.

[0048] The weight average molecular weight Mw of the (meth)acrylic polymer is, for example, 100,000 to 2,000,000, and preferably 200,000 to 1,000,000.

[0049] The (meth)acrylic adhesive may also contain a crosslinking agent. Typical examples of the crosslinking agent include organic crosslinking agents and polyfunctional metal chelates, with organic crosslinking agents being preferred. Examples of the organic crosslinking agent include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents, with isocyanate crosslinking agents being more preferred. When the adhesive contains a crosslinking agent, the content of the crosslinking agent is typically 0.01 parts by weight or more and 15 parts by weight or less relative to 100 parts by weight of the (meth)acrylic polymer.

[0050] The above-mentioned pressure-sensitive adhesives ((meth)acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, and silicone pressure-sensitive adhesives) may contain various additives in appropriate proportions as necessary. By adjusting the composition of the base polymer (e.g., the type and content of the monomer, the type and content of the cross-linking agent), the molecular weight of the base polymer, the type or content of the additive, etc., a pressure-sensitive adhesive layer having the desired adhesiveness to the adherend can be obtained.

[0051] Examples of the additives include a polymerization initiator, a solvent, a polymerization catalyst, a crosslinking catalyst, a silane coupling agent, a tackifier, a plasticizer, a softener, an antidegradant, a filler, a colorant (pigment, dye, etc.), a light stabilizer, an ultraviolet absorber, an antioxidant, a surfactant, an antistatic agent, and a chain transfer agent.

[0052] The thickness of the pressure-sensitive adhesive layer is, for example, 10 μm or more, preferably 12 μm or more, and for example, 40 μm or less, preferably 30 μm or less, more preferably 25 μm or less.

[0053] The pressure-sensitive adhesive layer may be formed on the surface of the substrate by direct printing or by transfer printing. In the case of direct printing, the pressure-sensitive adhesive layer is formed by directly applying the pressure-sensitive adhesive to the surface of the substrate. In the case of transfer printing, the pressure-sensitive adhesive is applied to the surface of a release liner to form a pressure-sensitive adhesive layer, and then the substrate is attached to the pressure-sensitive adhesive layer. In particular, when the substrate contains an amorphous resin having a relatively low glass transition temperature Tg (e.g., 150°C or less), the pressure-sensitive adhesive layer is preferably formed by a transfer process. The transfer process can prevent the high temperature during drying required to form the pressure-sensitive adhesive layer from affecting the substrate.

[0054] [Optical Film] The optical film may have any appropriate configuration depending on the purpose, application, etc. The optical film may have a single-layer structure or a laminate having a multilayer structure. For example, the optical film may be a laminate having an antireflection layer as one of the outermost layers. For layers with low surface free energy, such as an antireflection layer, it may be difficult for the PF to exert sufficient adhesive strength, resulting in insufficient P1 (e.g., P1 < P2). Even in such cases, according to an embodiment of the present invention, the peel strength between the outer PF and the inner PF is adjusted to a predetermined relationship, thereby suitably preventing the inner PF from peeling off simultaneously when the outer PF is peeled off.

[0055] In one embodiment, the water contact angle of the surface of the optical film on the surface protective film layer side is, for example, 80° or more, and may be 90° or more, or 100° or more. The water contact angle may be, for example, 150° or less, or, for example, 140° or less. When the wettability of the surface of the optical film on the surface protective film layer side is low, the effects of the present invention can be more suitably obtained.

[0056] FIG. 4 is a schematic cross-sectional view illustrating an example of the configuration of an optical film applicable to an embodiment of the present invention. The optical film 50a includes, in this order, a pressure-sensitive adhesive layer 31, a polarizing member 10, a first phase difference member 20, and a first protective member 41. The polarizing member 10, the first phase difference member 20, and the first protective member 41 are laminated via adhesive layers 33 and 34. The adhesive layers 33 and 34 are typically adhesive layers or pressure-sensitive adhesive layers, and are preferably pressure-sensitive adhesive layers. The thickness of the adhesive layers 33 and 34 is, for example, 0.05 μm to 30 μm. The surface of the pressure-sensitive adhesive layer 31 is protected by a release liner 36 until use. A surface protection film layer is disposed on the surface of the optical film 50a facing the first protective member 41.

[0057] The optical film 50a can be suitably used in the display system 2 exemplified in Fig. 1. Specifically, the polarizing member 10 in the optical film 50a is a polarizing member that can be included in the display element 12, and a display system in which the first retardation member 20 is provided integrally with the display element 12 can be manufactured by peeling the release liner 36 from the optical film 50a and bonding it to a component of the display element 12 via the exposed pressure-sensitive adhesive layer 31.

[0058] In the example shown in FIG. 4 , the first phase difference member 20 includes, in addition to a first λ / 4 member 20a, a member (so-called positive C plate) 20b whose refractive index characteristics can exhibit the relationship nz > nx = ny. The first phase difference member 20 has a laminated structure of the first λ / 4 member 20a and the first positive C plate 20b. Unlike the illustrated example, the first positive C plate 20b may be located closer to the polarizing member 10 than the first λ / 4 member 20a, or the first positive C plate 20b may be omitted. The first λ / 4 member 20a and the first positive C plate 20b are laminated, for example, via an adhesive layer (not shown). The first phase difference member 20 is arranged so that the angle between the absorption axis of the polarizing member 10 and the slow axis of the first λ / 4 member 20a is preferably 40° to 50°, more preferably 42° to 48°, e.g., approximately 45°.

[0059] <Polarizing Member> The polarizing member 10 is typically an absorptive polarizing member including a resin film (sometimes referred to as an absorptive polarizing film) containing a dichroic material, and may further include a protective layer on one or both sides thereof, as necessary. The protective layer is typically bonded to the absorptive polarizing film via any appropriate adhesive layer. A typical example of the adhesive that forms the adhesive layer is an ultraviolet-curable adhesive.

[0060] The polarizing member (absorptive polarizing film) preferably has a crossed transmittance (Tc) of 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The polarizing member (absorptive polarizing film) has a single transmittance (Ts) of, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarizing member (absorptive polarizing film) has a degree of polarization (P) of, for example, 99.0% to 99.997%, and preferably 99.9% or more.

[0061] 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 Z8701 and corrected for visibility. Degree of polarization P (%) = {(Tp - Tc) / (Tp + Tc)} １／２ ×100

[0062] The thickness of the absorptive polarizing film is, for example, 1 μm or more and 20 μm or less, or may be 2 μm or more and 15 μm or less, or may be 12 μm or less, or may be 10 μm or less, or may be 8 μm or less, or may be 5 μm or less.

[0063] The absorptive polarizing film may be made from a single layer of resin film or may be made from a laminate of two or more layers.

[0064] When the absorptive polarizing film is produced from a single-layer resin film, for example, an absorptive polarizing film can be obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene-vinyl acetate copolymer-based film to a dyeing treatment with iodine or a dichroic substance such as a dichroic dye, a stretching treatment, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferred.

[0065] The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA-based film may be dyed after stretching. If necessary, the PVA-based film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like.

[0066] Examples of laminates produced using the two or more layer laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, and a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to convert the PVA-based resin layer into an absorptive polarizing film. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may optionally include in-air stretching of the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained through treatment steps in which the laminate is immersed in a liquid, such as dyeing treatment and underwater stretching treatment, etc. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment.The obtained resin substrate / absorptive polarizing film laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the absorptive polarizing film), or any suitable protective layer may be laminated depending on the purpose on the surface obtained by peeling the resin substrate from the resin substrate / absorptive polarizing film laminate or on the surface opposite to the peeled surface. Details of such methods for producing an absorptive polarizing film are described in, for example, JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures of these publications are incorporated herein by reference.

[0067] The protective layer can be formed of any appropriate resin film that can be used as a protective layer for an absorptive polarizing film. Specific examples of the resin that serves as the main component of the resin film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins, polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, cycloolefin-based resins such as polynorbornene, polyolefin-based resins, (meth)acrylic resins, and acetate-based resins.

[0068] 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.

[0069] <First λ / 4 Member> The in-plane retardation Re(550) and dispersion wavelength characteristics of the first λ / 4 member 20a are as described in Section A.

[0070] The first λ / 4 member preferably has a refractive index characteristic that satisfies the relationship nx>ny≧nz. Here, "ny=nz" does not only include the case where ny and nz are completely equal, but also includes the case where they are substantially equal. Therefore, there may be cases where ny<nz, as long as the effects of the present invention are not impaired. The Nz coefficient of the first λ / 4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0071] The first λ / 4 member may be made of any suitable material that satisfies the above-mentioned characteristics, and may be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound.

[0072] Examples of resins contained in the resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic-based resins. These resins may be used alone or in combination. Examples of methods for combining include blending and copolymerization. When the first λ / 4 member 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) can be suitably used.

[0073] Any suitable polycarbonate resin can be used as the polycarbonate resin. For example, the polycarbonate resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate-based resins that can be suitably used for the first λ / 4 member and methods for forming the first λ / 4 member 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 herein by reference.

[0074] The thickness of the first λ / 4 member 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.

[0075] The above-mentioned liquid crystal compound alignment solidified layer 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 term "alignment solidified layer" encompasses an alignment solidified layer obtained by curing a liquid crystal monomer, as described below. In the first λ / 4 member, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first λ / 4 member (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.

[0076] The alignment and solidification layer of the liquid crystal compound (liquid crystal alignment and solidification 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 used as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. 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 vapor deposition and photoalignment treatment. Any appropriate treatment conditions can be used for the various alignment treatments depending on the purpose.

[0077] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction on the substrate surface.

[0078] 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 a crosslinking treatment.

[0079] Any suitable liquid crystal polymer and / or liquid crystal monomer can be used as the liquid crystal compound. The liquid crystal polymer and the liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for producing a 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.

[0080] The thickness of the first λ / 4 member formed of 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 even more preferably 1 μm to 4 μm.

[0081] <First Positive C Plate> The thickness direction retardation Rth(550) of the first positive C plate 20b is preferably −20 nm to −200 nm, more preferably −30 nm to −180 nm, even more preferably −40 nm to −160 nm, and particularly preferably −50 nm to −140 nm. Here, "nx=ny" encompasses not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. The in-plane retardation Re(550) of the first positive C plate is, for example, less than 10 nm.

[0082] The first positive C plate can be formed of any appropriate material. The first positive C plate 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 paragraphs

[0020] to

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

[0083] <First Protective Member> The first protective member 41 typically includes a substrate. The substrate may be composed of any appropriate film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0084] The first protective member preferably has a substrate and a surface treatment layer formed on the substrate. The first protective member having the surface treatment layer may be disposed so that the surface treatment layer is located on the front side. Specifically, the surface treatment layer may be located on the outermost surface of the optical film 50a. The surface treatment layer may have any appropriate function. Examples of the surface treatment layer include a hard coat layer, an anti-reflection layer, an anti-sticking layer, and an anti-glare layer. The first protective member may have two or more surface treatment layers.

[0085] The antireflection layer is provided to prevent reflection of external light, etc. Examples of the antireflection layer include a fluororesin layer, a resin layer containing nanoparticles (typically hollow nanoparticles, e.g., hollow nanosilica particles), or an antireflection layer having a nanostructure (e.g., a moth-eye structure). The thickness of the antireflection layer is preferably 0.05 μm to 1 μm. Examples of methods for forming the resin layer include a sol-gel method, a thermal curing method using an isocyanate, and an ionizing radiation curing method (typically, a photocuring method) using a crosslinkable monomer (e.g., a polyfunctional acrylate) and a photopolymerization initiator. In one embodiment, the antireflection layer is provided on the outermost surface of the first protective member. According to an embodiment in which the antireflection layer is provided on the outermost surface of the first protective member, an excellent antireflection effect can be obtained in a display system in which a space is formed between the half mirror 18 and the first retardation member 20.

[0086] The hard coat layer preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. The hard coat layer can be formed from any appropriate resin. The hard coat layer is typically formed from an ultraviolet-curable resin. Examples of ultraviolet-curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based resins. The thickness of the hard coat layer is, for example, 0.5 μm or more, preferably 1 μm or more, and, for example, 20 μm or less, preferably 15 μm or less.

[0087] <Adhesive Layer> The adhesive layer 31 can be composed of any appropriate adhesive. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and compounding ratio of monomers forming the base resin of the adhesive, as well as the compounding amount of crosslinking agent, reaction temperature, reaction time, etc., it is possible to prepare an adhesive having desired properties according to the purpose. The base resin of the adhesive may be used alone or in combination of two or more types. An acrylic resin is preferably used as the base resin. Specifically, the adhesive layer is preferably composed of an acrylic adhesive.

[0088] The thickness of the pressure-sensitive adhesive layer is typically 1 μm or more, preferably 5 μm or more, more preferably 12 μm or more, and typically 60 μm or less, preferably 30 μm or less, more preferably 23 μm or less.

[0089] <Release Liner> The release liner 36 is formed of any appropriate resin film. Specific examples of materials that are the main components of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The resin film materials can be used alone or in combination. The release liner may be transparent (for example, haze of 5% or less, e.g., 3% or less) or not. When inspecting the optical film with a surface protective film with the release liner attached, it is preferable that the release liner be transparent.

[0090] A release treatment layer may be provided on the surface of the release liner 36 that comes into contact with the pressure-sensitive adhesive layer 31. 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 treatment agents. The release treatment agents 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.

[0091] The thickness of the release liner is typically 5 μm or more, preferably 20 μm or more, and typically 60 μm or less, preferably 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.

[0092] 5 is a schematic cross-sectional view illustrating an example of the configuration of an optical film applicable to an embodiment of the present invention. The optical film 50b includes, in this order, a pressure-sensitive adhesive layer 32, a second retardation member 22, and a second protective member 42. The second retardation member 22 and the second protective member 42 are laminated via an adhesive layer 35. The adhesive layer 35 is typically an adhesive layer or a pressure-sensitive adhesive layer, and is preferably a pressure-sensitive adhesive layer. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm. The surface of the pressure-sensitive adhesive layer 32 is protected by a release liner 37 until use. A surface protection film layer is disposed on the surface of the optical film 50b facing the second protective member 42.

[0093] The optical film 50b can be suitably used in the display system 2 exemplified in Fig. 1. Specifically, by peeling the release liner 37 from the optical film 50b and integrating it with the first lens unit 16 via the exposed pressure-sensitive adhesive layer 32, a display system in which the second retardation member 22 is provided integrally with the first lens unit 16 can be manufactured.

[0094] 5 , the second phase difference member 22 includes, in addition to the second λ / 4 member 22a, a member (so-called positive C plate) 22b whose refractive index characteristics can exhibit the relationship nz > nx = ny. The second phase difference member 22 has a laminated structure of the second λ / 4 member 22a and the second positive C plate 22b. Unlike the illustrated example, the second positive C plate 22b may be located closer to the second protective member 42 than the second λ / 4 member 22a, or the second positive C plate 22b may be omitted. The second λ / 4 member 22a and the second positive C plate 22b are laminated together, for example, via an adhesive layer (not shown).

[0095] <Second λ / 4 Member> The in-plane retardation Re(550) and dispersion wavelength characteristics of the second λ / 4 member 22a are as described in Section A.

[0096] The second λ / 4 member preferably has a refractive index characteristic that satisfies the relationship nx>ny≧nz. Here, "ny=nz" does not only mean that ny and nz are completely equal, but also includes cases where they are substantially equal. Therefore, there may be cases where ny<nz, as long as the effects of the present invention are not impaired. The Nz coefficient of the second λ / 4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0097] The second λ / 4 member is formed of any appropriate material that can satisfy the above characteristics. The second λ / 4 member may be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound. The same explanation as for the first λ / 4 member can be applied to a second λ / 4 member formed of a stretched resin film or an oriented and solidified layer of a liquid crystal compound. The first λ / 4 member and the second λ / 4 member may have the same configuration (e.g., forming material, thickness, optical properties, etc.) or different configurations.

[0098] <Second Positive C Plate> The thickness direction retardation Rth(550) of the second positive C plate 22b is preferably −20 nm to −200 nm, more preferably −30 nm to −180 nm, even more preferably −40 nm to −160 nm, and particularly preferably −50 nm to −140 nm. Here, "nx = ny" encompasses not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. The in-plane retardation Re(550) of the second positive C plate is, for example, less than 10 nm.

[0099] The second positive C plate is formed of any appropriate material that can satisfy the above characteristics. The same explanation as for the first positive C plate can be applied to the constituent material of the second positive C plate. The first positive C plate and the second positive C plate may have the same or different configurations (e.g., forming material, thickness, optical properties, etc.).

[0100] <Second Protective Member> The second protective member 42 typically includes a substrate, and preferably has a substrate and a surface treatment layer formed on the substrate. In this case, the surface treatment layer may be located on the outermost surface of the optical film 50b. Details of the substrate and the surface treatment layer can be similar to those of the first protective member. According to an embodiment in which an anti-reflection layer is provided on the outermost surface of the second protective member 42 as the surface treatment layer, an excellent anti-reflection effect can be obtained in a display system in which the second retardation member 22 is integrated with the first lens unit 16, the reflective unit 14 is integrated with the second lens unit 24, and a space is formed between them.

[0101] The same explanations as for the pressure-sensitive adhesive layer 31 and release liner 36 used in the optical film 50a can be applied to the pressure-sensitive adhesive layer 32 and release liner 37 used in the optical film 50b, respectively.

[0102] <Method for manufacturing optical film with surface protective film> The optical film with surface protective film can be produced by any appropriate method. For example, an optical film with surface protective film can be produced by laminating two or more PFs to produce a surface protective film layer and then bonding the surface protective film layer to an optical film. Alternatively, an optical film with surface protective film can be produced by sequentially bonding two or more PFs to one side of an optical film. Alternatively, an optical film with surface protective film can be obtained by providing a surface protective film layer on the outermost member (e.g., protective member) of the optical film and laminating the member with the surface protective film layer with another member to produce an optical film.

[0103] C. Optical Film Inspection Method An optical film inspection method according to an embodiment of the present invention includes: peeling the outermost layer PF from the optical film with a surface protective film described in Section B to obtain an optical film protected by at least the innermost layer PF; and subjecting the optical film protected by at least the innermost layer PF to defect inspection. As described above, the optical film with a surface protective film described in Section B can suitably suppress peeling of the inner PF (e.g., the innermost layer PF or the intermediate PF) when peeling the outer PF (e.g., the intermediate PF or the outermost layer PF). Therefore, by peeling the outer PF from the optical film with a surface protective film described in Section B, an optical film protected by at least the innermost layer PF can be suitably obtained. Here, the surface of the inner PF exposed by peeling the outer PF is protected from scratches, dirt, and the like. Therefore, by peeling off the outer PF immediately before inspection, the optical film protected by a clean PF can be subjected to defect inspection, thereby suppressing the false detection of defects caused by scratches or dirt on the PF surface.

[0104] The defect inspection can be performed by any suitable defect inspection device. As the defect inspection device, a known defect inspection device can be used, and preferably an automatic optical inspection (AOI) device is used. Examples of documents describing defect inspection devices include International Publication No. 2011 / 148790, Japanese Patent Application Laid-Open No. 2003-344302, Japanese Patent Application Laid-Open No. 2011-226957, Japanese Patent Application Laid-Open No. 2016-70856, and Japanese Patent Application Laid-Open No. 2021-135219. The defect inspection may further include visual inspection as necessary.

[0105] 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 values ​​were measured using the following measurement method. <Thickness> The thickness was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Total Light Transmittance and Haze> With respect to the surface protection film, the release liner was peeled from the pressure-sensitive adhesive layer, and light was irradiated from the substrate side using a haze meter (manufactured by Suga Test Instruments Co., Ltd., "HZ-V3"), and the haze was calculated in accordance with JIS-K-7136 using the formula: haze (%) = (Td / Tt) x 100 (Td: diffuse transmittance, Tt: total light transmittance). The total light transmittance was measured in accordance with JIS-K-7316. <Water Contact Angle> The water contact angle of the antireflection layer side surface of the optical film was measured. Specifically, the contact angle was measured by the sessile drop method using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DMo-501 type," control box "DMC-2," and control and analysis software "FAMAS (version 5.0.30)") in an environment of 23°C and 50% RH. The amount of distilled water dropped was 2 μL, and the contact angle was calculated by the θ / 2 method from the image taken 5 seconds after the drop.

[0106] [Production Example 1-1: Preparation of PF1] <Acrylic Polymer 1> In a reaction vessel equipped with a thermometer, a stirrer, a cooler, and a nitrogen gas inlet tube, 96.2 parts by weight of 2-ethylhexyl acrylate (2EHA), 3.8 parts by weight of 2-hydroxyethyl acrylate (HEA), and 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged together with 150 parts by weight of ethyl acetate, and nitrogen gas was introduced while gently stirring at 23°C to perform nitrogen substitution. Thereafter, the liquid temperature was maintained at around 65°C and a polymerization reaction was carried out for 6 hours to produce a solution of acrylic polymer 1 (concentration 40% by weight). The weight average molecular weight of acrylic polymer 1 was 540,000. The Tg of acrylic polymer 1 was calculated using the FOX formula as follows: (-70°C x 0.962) + (-15°C x 0.038) = (-67.34°C) + (-0.57°C) = -67.91°C. <Adhesive Composition 1> 5 parts by weight of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) was added as a crosslinking agent to 100 parts by weight of the solids content of the acrylic polymer 1 solution. The solution was diluted with toluene to a total solids content of 20% by weight, and 3 parts by weight (solids content: 0.03 parts by weight) of dibutyltin dilaurate (1 wt% solution in ethyl acetate) was added as a crosslinking catalyst and stirred, followed by stirring with a disper to produce adhesive composition 1. <PF1> Pressure-sensitive adhesive composition 1 was applied to the surface (corona-treated surface) of a substrate (cyclic olefin film, manufactured by Zeon Corporation, product number ZF-16, thickness 50 μm) and then dried to form a pressure-sensitive adhesive layer (thickness 10 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the pressure-sensitive adhesive layer opposite the substrate. This resulted in PF1 (thickness 60 μm) having a haze of 1.0% or less and a total light transmittance of 90% or more.

[0107] [Production Example 1-2: Preparation of PF2] <Acrylic Polymer 2> In a reaction vessel equipped with a thermometer, a stirrer, a cooler, and a nitrogen gas inlet tube, 100 parts by weight of 2-ethylhexyl acrylate (2EHA) and 4 parts by weight of hexyl acrylate as monomer components, and 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged together with 150 parts by weight of ethyl acetate, and nitrogen gas was introduced while gently stirring at 23°C to perform nitrogen substitution. The liquid temperature was then maintained at around 65°C, and a polymerization reaction was carried out for 6 hours to prepare a solution of acrylic polymer 2 (concentration 40% by weight). The weight-average molecular weight of acrylic polymer 2 was 530,000. <Adhesive Composition 2> Ethyl acetate was added to the acrylic polymer 2 solution to dilute it to a concentration of 20% by weight. To 500 parts by weight of this solution (100 parts by weight of solids), 4 parts by weight of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) as a crosslinking agent and 0.2 parts by weight of a surfactant ("Aqualon HS-10" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were added and stirred to prepare PSA Composition 2. <PF2> PSA Composition 2 was applied to the surface (corona-treated surface) of a substrate (PET film, manufactured by Mitsubishi Chemical Corporation, product number T100C38, thickness 38 μm) and then dried to form a PSA layer (thickness 20 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the PSA layer opposite the substrate. This resulted in PF2 (thickness 58 μm) with a haze of 3.0% or less and a total light transmittance of 90% or more.

[0108] [Production Example 1-3: Preparation of PF3] <Adhesive Composition 3> To 100 parts by weight of the solids content of the acrylic polymer 1 solution obtained in Production Example 1-1, 4 parts by weight of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) was added as a crosslinking agent. Diluted with toluene to a total solids content of 20% by weight, 3 parts by weight (solids content: 0.03 parts by weight) of dibutyltin dilaurate (1 wt% toluene solution) as a crosslinking catalyst was added and stirred, followed by stirring with a disperser, to produce Adhesive Composition 3. <PF3> Adhesive Composition 3 was applied to the surface (corona-treated surface) of a substrate (PET film, manufactured by Mitsubishi Chemical Corporation, product number T100C38, thickness 38 μm) and then dried to form an adhesive layer (thickness 10 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the adhesive layer opposite the substrate. As a result, PF3 (thickness: 48 μm) having a haze of 3.0% or less and a total light transmittance of 90% or more was obtained.

[0109] [Production Example 1-4: Preparation of PF4] <Adhesive Composition 4> To 100 parts by weight of the solids content of the acrylic polymer 1 solution obtained in Production Example 1-1, 4.0 parts by weight (solids equivalent) of Takenate D-101E (manufactured by Mitsui Chemicals, Inc.) was added as a crosslinking agent. The mixture was diluted with toluene to a total solids content of 29% by weight and stirred with a disperser to produce Adhesive Composition 4. <PF4> Adhesive Composition 4 was applied to the surface (corona-treated surface) of a substrate (PET film, manufactured by Mitsubishi Chemical Corporation, product number T100C38, thickness 38 μm) and then dried to form an adhesive layer (thickness 23 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the adhesive layer opposite the substrate. This resulted in PF4 (thickness 61 μm) with a haze of 3.0% or less and a total light transmittance of 90% or more.

[0110] The peel strength of PF1 to PF4 was measured as follows. Measurements were performed under conditions of 23°C and 50% RH. The results are shown in Table 1. (1) The pressure-sensitive adhesive layer surface of surface protection film A to be measured was roll-pressed onto adherend B at a pressure of 0.25 MPa and a feed rate of 0.3 m / min, and left for 30 minutes to prepare measurement sample C (size: length 150 mm, width 25 mm). (2) Measurement sample C was fixed onto a metal or glass plate with double-sided tape (manufactured by Nitto Denko Corporation, product name "No. 5000NS") so that adherend B was facing downwards. (3) As shown in Figures 6A and 6B, an adhesive tape T (manufactured by Nitto Denko Corporation, product name "No. 31B", size: length 50 mm, width 20 mm) was attached to surface A of surface protection film C so that one end was exposed and the longitudinal directions were parallel, and the peel force when the one end was gripped and pulled in the direction of the arrow was measured (peel angle 180°, peel speed 300 mm / min).

[0111]

[0112] [Production Example 2: Preparation of Polarizing Film 1] A long roll of a 30 μm-thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray Co., Ltd., product name "PE3000") was uniaxially stretched in the longitudinal direction to 5.9 times its original length using a roll stretching machine, while simultaneously undergoing swelling, dyeing, crosslinking, and washing treatments, and finally drying treatment to produce an absorptive polarizing film with a thickness of 12 μm. Specifically, the film was stretched 2.2 times while treated with pure water at 20°C for the swelling treatment. Subsequently, the film was stretched 1.4 times while treated in an aqueous solution at 30°C containing iodine and potassium iodide in a weight ratio of 1:7, with the iodine concentration adjusted, so that the resulting absorptive polarizing film had a single transmittance of 45.0%. Furthermore, a two-stage crosslinking treatment was employed, with the first stage involving stretching 1.2 times while treated in an aqueous solution at 40°C containing boric acid and potassium iodide. The aqueous solution used in the first crosslinking treatment had a boric acid content of 5.0 wt % and a potassium iodide content of 3.0 wt %. The second crosslinking treatment involved stretching the film 1.6 times while treating it in an aqueous solution containing boric acid and potassium iodide dissolved at 65°C. The aqueous solution used in the second crosslinking treatment had a boric acid content of 4.3 wt % and a potassium iodide content of 5.0 wt %. The cleaning treatment involved treating it with an aqueous potassium iodide solution at 20°C. The aqueous solution used in the cleaning treatment had a potassium iodide content of 2.6 wt %. Finally, the film was dried at 70°C for 5 minutes to obtain an absorptive polarizing film. A triacetyl cellulose (TAC)-based resin film with a hard coat (HC) layer (TAC thickness: 25 μm, HC thickness: 7 μm) was laminated to one surface of the obtained absorptive polarizing film, and a cycloolefin-based resin film (thickness: 13 μm) was laminated to the other surface, each as a protective layer. Specifically, the curable adhesive was applied to a total thickness of approximately 1 μm, and the films were laminated using a roller. The adhesive was then cured by irradiating it with UV light from the TAC film side. This resulted in polarizing film 1 having a structure of [TAC film (protective layer) / absorptive polarizing film / COP film (protective layer)].

[0113] [Manufacturing Example 3: Fabrication of protective member 1] (Preparation of hard coat layer-forming material) 50 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 30 parts of a polyfunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by Osaka Organic Chemical Industry Ltd., trade name "Viscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100") and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan KK, "Irgacure 907") were mixed and diluted with methyl isobutyl ketone to a solids concentration of 50%, to prepare a hard coat layer-forming material.

[0114] (Preparation of Coating Liquid for Forming High Refractive Index Layer) 100 parts by weight of a polyfunctional acrylate (manufactured by Arakawa Chemical Industries, Ltd., trade name "Opstar KZ6728", solid content 20 wt%), 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 Corporation, trade name "OMNIRAD907", solid content 100 wt%) were mixed. The mixture was diluted with butyl acetate as a dilution solvent to a solid content of 12 wt%, and the mixture was stirred to prepare a coating liquid for forming a high refractive index layer.

[0115] (Preparation of Coating Liquid for Forming Low Refractive Index Layer) 100 parts by weight of a polyfunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by Osaka Organic Chemical Industry Ltd., trade name "Viscoat #300", solid content 100 wt%), 150 parts by weight of hollow nanosilica particles (manufactured by JGC Catalysts and Chemicals Industries, Ltd., trade name "Surulia 5320", solid content 20 wt%, 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 wt%, 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 wt%), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%) 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, so that the total solid content was 4% by weight, and the mixture was stirred to prepare a coating liquid for forming a low refractive index layer.

[0116] The above hard coat layer-forming material was applied to an acrylic film (thickness: 40 μm) having a lactone ring structure as a substrate, and heated at 90° C. for 1 minute. After heating, the applied layer was irradiated with a high-pressure mercury lamp at an integrated light intensity of 300 mJ / cm 2 ２ The coating layer was cured by irradiating ultraviolet rays of 1000 W / cm 2 with the acrylic film (thickness: 44 μm) on which a hard coat layer of 4 μm in thickness was formed. Next, the coating liquid for forming a high refractive index layer was applied onto the hard coat layer with a wire bar, and the applied coating liquid was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet rays of 1000 W / cm 2 with an integrated light amount of 300 mJ / cm 2 using a high-pressure mercury lamp. ２ The coating film was cured by irradiating it with ultraviolet light of 1000 kJ / cm to form a high refractive index layer having a thickness of 140 nm. Subsequently, the coating liquid for forming the low refractive index layer was applied onto the high refractive index layer using a wire bar, and the applied coating liquid was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet light of 300 mJ / cm to form a high refractive index layer having a thickness of 140 nm. ２The coating film was cured by irradiating it with ultraviolet light of 1000 W at ...

[0117] [Production Example 4: Preparation of Optical Film 1] The substrate surface of Protective Material 1 was bonded via an acrylic pressure-sensitive adhesive layer (thickness: 25 μm) to the TAC film surface of Polarizing Film 1 obtained in Production Example 2. In addition, an acrylic pressure-sensitive adhesive layer (thickness: 25 μm) formed on a release liner was bonded to the COP film surface of Polarizing Film 1 to produce Optical Film 1 having a configuration of [Release liner / Pressure-sensitive adhesive layer / Polarizing Film 1 / Protective Material 1].

[0118] [Example 1] The pressure-sensitive adhesive layer surface of PF2 obtained in Production Example 1-2 was bonded to the substrate surface of PF1 obtained in Production Example 1-1 to form a surface protective film layer 1 composed of PF1 as the innermost layer PF and PF2 as the outermost layer PF. The pressure-sensitive adhesive layer surface of the surface protective film layer 1 (more specifically, the pressure-sensitive adhesive layer surface of PF1) was bonded to the protective member 1 surface of the optical film 1 to obtain an optical film 1 with a surface protective film.

[0119] [Example 2] The pressure-sensitive adhesive layer surface of PF3 obtained in Production Example 1-3 was bonded to the substrate surface of PF1 obtained in Production Example 1-1 to form a surface protective film layer 2 composed of PF1 as the innermost layer PF and PF3 as the outermost layer PF. The pressure-sensitive adhesive layer surface of the surface protective film layer 2 (more specifically, the pressure-sensitive adhesive layer surface of PF1) was bonded to the protective member 1 surface of the optical film 1 to obtain an optical film 2 with a surface protective film.

[0120] [Comparative Example 1] The pressure-sensitive adhesive layer surface of PF4 obtained in Production Example 1-4 was bonded to the substrate surface of PF1 obtained in Production Example 1-1 to form a surface protective film layer 3 composed of PF1 as the innermost layer PF and PF4 as the outermost layer PF. The pressure-sensitive adhesive layer surface of the surface protective film layer 3 (more specifically, the pressure-sensitive adhesive layer surface of PF1) was bonded to the protective member 1 surface of the optical film 1 to obtain an optical film C1 with a surface protective film.

[0121] <Peel Test> The optical films with surface protective films obtained in the Examples and Comparative Examples were cut into rectangles (size: length 32 mm, width 28 mm) and the four corners were chamfered (chamfer dimension: 2 mm) to prepare measurement samples. (1) Peeling Starting from the Short Side As shown in FIG. 7A , a 50 mm long, 20 mm wide adhesive tape T (manufactured by Nitto Denko Corporation, product name "No. 31B") was attached to the surface of the surface protective film layer 60 of the measurement sample 100 so that the length directions were parallel and one end was exposed. The one end was gripped and pulled at a peel speed of 300 mm / min at a peel angle of 90° or 180° to peel the outermost layer PF. For each peel angle, a test was performed with an N number of 25. The number of times the innermost layer PF and the outermost layer PF peeled simultaneously (NG number) is shown in Table 2. (2) Peeling Starting from a Corner As shown in FIG. 7B , a 50 mm long, 20 mm wide adhesive tape T (manufactured by Nitto Denko Corporation, product name "No. 31B") was attached to the surface of the surface protection film layer 60 of the measurement sample 100 so that its length formed a 45° angle with the length of the measurement sample 100 and one end was exposed. The end was gripped and pulled at a peeling speed of 300 mm / min at a peel angle of 90° or 180° to peel the outermost layer PF. For each peel angle, a test was performed with an N number of 25. The number of times the innermost layer PF peeled simultaneously with the outermost layer PF (NG number) is shown in Table 2.

[0122]

[0123] As shown in Table 2, in the optical films with surface protective films of the examples in which P2 was 3.5 times or less than P1, simultaneous peeling of the inner PF when peeling the outermost layer PF was suppressed regardless of the peel starting point and peel angle.

[0124] The optical film with a surface protective film according to the embodiment of the present invention can be suitably used in the manufacture of display systems such as VR goggles, for example.

[0125] 2 Display system, 12 Display element, 14 Reflection section, 16 First lens section, 18 Half mirror, 20 First phase difference member, 22 Second phase difference member, 24 Second lens section, 50 Optical film, 60 Surface protection film layer, 62 Innermost layer surface protection film, 64 Outermost layer surface protection film, 66 Intermediate surface protection film, 100 Optical film with surface protection film

Claims

1. An optical film with a surface protective film, comprising an optical film and a surface protective film layer arranged on one side of the optical film, the surface protective film layer including two or more surface protective films each having a substrate and an adhesive layer, and a peel force P1 of an innermost surface protective film arranged closest to the optical film of the surface protective film layer, and a peel force P2 of an outermost surface protective film arranged on the outermost side of the surface protective film layer, against an adjacent surface protective film, satisfying the relationship of the following formula (1): P2≦3.5×P1 (1).

2. The optical film with surface protective film according to claim 1, wherein the surface protective film layer is composed of the innermost surface protective film, an intermediate surface protective film, and the outermost surface protective film, and the peeling force P2 of the outermost surface protective film to the intermediate surface protective film and the peeling force P3 of the intermediate surface protective film to the innermost surface protective film satisfy the relationships of the following formulas (2) and (3): P2≦2.5×P3 (2), P3≦2×P1 (3).

3. The optical film with a surface protective film according to claim 1, wherein the ratio (T1 / T2) of the thickness T1 of the innermost surface protective film to the thickness T2 of the outermost surface protective film is 1.03 or more.

4. The optical film with a surface protective film according to claim 1, wherein the bending strength of the substrate of the innermost surface protective film at 23°C is equal to or greater than the bending strength of the substrate of the outermost surface protective film at 23°C.

5. The optical film with a surface protective film according to claim 1, wherein the surface of the optical film facing the surface protective film layer is an antireflection layer.

6. The optical film with a surface protective film according to claim 1, wherein the surface of the optical film on the side of the surface protective film layer has a water contact angle of 80° or more.

7. A method for inspecting an optical film, comprising: peeling off the outermost surface protective film from an optical film with a surface protective film according to any one of claims 1 to 6 to obtain the optical film protected by at least the innermost surface protective film; and subjecting the optical film protected by at least the innermost surface protective film to a defect inspection.

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