Method for manufacturing optical member, and optical laminate

Abstract

A method for manufacturing an optical member according to an embodiment of the present invention comprises heating an optical laminate including a retardation film and integrating the optical laminate with a member having a curved surface part. Where a glass transition temperature of the retardation film is denoted by A°C, a temperature of the optical laminate at the time of the integration is denoted by B°C, and a minimum temperature at which the retardation film can be stretched by 5% in a direction orthogonal to a slow axis at a drawing speed of 2 mm / sec is denoted by C°C, A, B, and C satisfy a relationship of C ≤ B ≤ A × 1.05. A change amount of Re (550) when the retardation film is stretched by 5% in a direction orthogonal to the slow axis at a drawing speed of 2 mm / sec at C°C is less than 25 nm.

Description

Manufacturing method for optical member and optical laminate

[0001] The present invention relates to a method for producing an optical member and an optical laminate.

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

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

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

[0005] While the weight reduction of the VR goggles can be achieved by, for example, thinning the lenses used in the VR goggles, there is also a need for the development of optical components suitable for display systems using thin lenses.

[0006] In view of the above, a main object of the present invention is to provide a method for manufacturing an optical member that can satisfactorily achieve both visibility and weight reduction for a display system such as VR goggles.

[0007] 1. According to one aspect of the present invention, there is provided a method for producing an optical member, comprising heating an optical laminate including a retardation film and integrating it with a member having a curved surface, wherein, when the glass transition temperature of the retardation film is A°C, the temperature of the optical laminate during the integration is B°C, and the lowest temperature at which the retardation film can be stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec is C°C, A, B, and C satisfy the relationship C≦B≦A×1.05, and when the retardation film is stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at C°C, a change in Re(550) is less than 25 nm. 2. In the production method described in 1. above, B may be 140 or less. 3. In the production method described in 1. or 2. above, B may be 130 or less. 4. Any of 1. to 3. above. 5. In the manufacturing method described in any one of 1. to 4. above, the member having the curved surface may be the first lens unit in a display system that displays an image to a user, comprising: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member that is disposed in front of the display element and reflects the light emitted from the display element; a first lens unit that is disposed on an optical path between the display element and the reflective polarizing member; a half mirror that is disposed between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing member toward the reflective polarizing member; a first λ / 4 member that is disposed on the optical path between the display element and the half mirror; and a second λ / 4 member that is disposed on the optical path between the half mirror and the reflective polarizing member.6. In the manufacturing method described in any one of 1. to 4. above, the member having the curved surface may be the first lens unit and / or the second lens unit in a display system that displays an image to a user, comprising: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member that is arranged in front of the display element and reflects the light emitted from the display element; a first lens unit that is arranged on an optical path between the display element and the reflective polarizing member; a half mirror that is arranged between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing member toward the reflective polarizing member; a second lens unit that is arranged in front of the reflective polarizing member; a first λ / 4 member that is arranged on the optical path between the display element and the half mirror; a second λ / 4 member that is arranged on the optical path between the half mirror and the reflective polarizing member; and a third λ / 4 member that is arranged between the reflective polarizing member and the second lens unit. According to another aspect of the present invention, there is provided an optical laminate including a retardation film having a change in Re(550) of less than 25 nm when stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the lowest temperature at which the film can be stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec. 8. In the optical laminate described in 7. above, the Re(550) of the retardation film may be 100 nm to 190 nm. 9. In the optical laminate described in 7. or 8. above, a pressure-sensitive adhesive layer may be disposed on one of the outermost surfaces. 10. In the optical laminate described in any one of 7. to 9. above, the retardation film may be a biaxially stretched film. 11. In the optical laminate described in any one of 7. to 10. above, the Nz coefficient of the retardation film may be 0.9 or less or 1.05 or more. 12. In the optical laminate described in 7. to 11. above, 13. In the optical laminate according to any one of items 7 to 12 above, the smoothness of the retardation film may be 0.5 arcmin or less. 14. The optical laminate according to any one of items 7 to 12 above may be one to be integrated with a member having a curved surface.

[0008] According to the method for manufacturing an optical member according to the embodiment of the present invention, a display system that satisfies both good visibility and light weight can be suitably obtained.

[0009] Fig. 5A is a schematic diagram showing a schematic configuration of an example of a display system to which an optical laminate according to an embodiment of the present invention can be applied. Fig. 5B is a schematic cross-sectional view showing a schematic configuration of an optical laminate according to an embodiment of the present invention. Fig. 5C is a schematic cross-sectional view showing a schematic configuration of an optical laminate according to an embodiment of the present invention. Fig. 5A to Fig. 5C are diagrams showing an example of a method for integrating an optical laminate including a retardation film with a member having a curved surface portion. Fig. 5A is a diagram continuing from Fig. 5A. Fig. 5B is a diagram continuing from Fig. 5B.

[0010] 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 schematically show the width, thickness, shape, etc. of each part compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in the drawings, the same or equivalent elements are given the same reference numerals, and redundant explanations may be omitted.

[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 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 with respect to the reference direction. Therefore, for example, "45°" means ±45°. Furthermore, in this specification, "substantially parallel" includes the range of 0° ±10°, preferably within the range of 0° ±5°, more preferably within the range of 0° ±3°, and even more preferably within the range of 0° ±1°. "Approximately perpendicular" encompasses the range of 90°±10°, preferably within the range of 90°±5°, more preferably within the range of 90°±3°, and even more preferably within the range of 90°±1°.

[0012] A. Display System FIG. 1 is a schematic diagram showing the general configuration of an example of a display system to which an optical laminate according to an embodiment of the present invention can be applied. FIG. 1 schematically illustrates the arrangement and shape of each component of a display system 2. The display system 2 includes a display element 12, a reflective polarizing member 14, 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 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 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 reflective polarizing member 14.

[0013] The half mirror or the components arranged in front of the first lens unit (in the illustrated example, the half mirror 18, the first lens unit 16, the second phase difference member 22, the reflective polarizing member 14, and the second lens unit 24) may be collectively referred to as the lens unit (lens unit 4).

[0014] 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.

[0015] 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.

[0016] The half mirror 18 transmits the light emitted from the display element 12 and reflects the light reflected by the reflective polarizing member 14 back toward the reflective polarizing member 14. The half mirror 18 is provided integrally with the first lens portion 16.

[0017] The second phase difference member 22 includes a second λ / 4 member that can transmit light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 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 portion 16.

[0018] 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 portion 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 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element 14 is the same as the reflection axis of the reflective polarizing element 14. Therefore, the second linearly polarized light incident on the reflective polarizing element 14 is reflected by the reflective polarizing element 14.

[0019] The second linearly polarized light reflected by the reflective polarizing element 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 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 third linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The third linearly polarized light is transmitted through the reflective polarizing element 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing element 14 is the same as the transmission axis of the reflective polarizing element 14. Therefore, the third linearly polarized light incident on the reflective polarizing element 14 is transmitted through the reflective polarizing element 14.

[0020] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 and enters the user's eye 26 .

[0021] 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 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 included in the first retardation member 20 is, for example, 40° to 50°, 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 included in the second retardation member 22 is, for example, 40° to 50°, may be 42° to 48°, or may be approximately 45°.

[0022] 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 with the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 component may be, for example, 0.75 or greater but less than 1, or 0.8 or greater but 0.95. Alternatively, the first λ / 4 component may exhibit a flat wavelength dispersion characteristic in which the retardation value changes little with the wavelength of the measurement light. In this case, the Re(450) / Re(550) of the first λ / 4 component may be, for example, 0.99 to 1.03, and the Re(650) / Re(550) may be, for example, 0.98 to 1.02.

[0023] 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 with the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 component may be, for example, 0.75 or greater but less than 1, or 0.8 or greater but 0.95. Furthermore, for example, the second λ / 4 component may exhibit a flat wavelength dispersion characteristic in which the retardation value changes little with the wavelength of the measurement light. In this case, the Re(450) / Re(550) of the second λ / 4 component may be, for example, 0.99 to 1.03, and the Re(650) / Re(550) may be, for example, 0.98 to 1.02.

[0024] Although not shown, a third phase difference element including an absorptive polarizing element and / or a third λ / 4 element may be disposed in front of the reflective polarizing element 14. The absorptive polarizing element and / or the third phase difference element may be disposed between the reflective polarizing element 14 and the second lens portion 24. When both an absorptive polarizing element and a third phase difference element are disposed, the third phase difference element may be disposed in front of the absorptive polarizing element. The reflection axis of the reflective polarizing element and the absorption axis of the absorptive polarizing element may be disposed approximately parallel to each other, and the transmission axis of the reflective polarizing element and the transmission axis of the absorptive polarizing element may be disposed approximately parallel to each other. The angle between the reflection axis of the reflective polarizing element and the slow axis of the third λ / 4 element is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0025] The in-plane retardation Re(550) of the third λ / 4 component is, for example, 100 nm to 190 nm, but may also be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The third λ / 4 component preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. The Re(450) / Re(550) of the third λ / 4 component may be, for example, 0.75 or greater but less than 1, or 0.8 or greater but 0.95. Furthermore, for example, the third λ / 4 component may exhibit a flat wavelength dispersion characteristic in which the retardation value changes little with the wavelength of the measurement light. In this case, the Re(450) / Re(550) of the third λ / 4 component may be, for example, 0.99 to 1.03, and the Re(650) / Re(550) may be, for example, 0.98 to 1.02.

[0026] In the lens unit 4, a space may be formed between the first lens unit 16 and the second lens unit 24. In this case, the member disposed between the first lens unit 16 and the second lens unit 24 is preferably provided integrally with either the first lens unit 16 or the second lens unit 24. For example, the member disposed between the first lens unit 16 and the second lens unit 24 is preferably integrated with either the first lens unit 16 or the second lens unit 24 via an adhesive layer. Such an embodiment can provide excellent handleability of each member, for example.

[0027] In the example shown in FIG. 1 , the first lens unit 16 and the second lens unit 24 have curved surfaces. When a component disposed between the first lens unit 16 and the second lens unit 24 is integrated with the curved first lens unit 16 and / or the second lens unit 24, these components are typically stretched under heat to conform to the surface shape of the curved surfaces. Furthermore, such curved surface processing can cause the optical properties of the component after integration to change from the desired values ​​due to heating and stretching, potentially reducing the visibility of the display system. Therefore, it is desirable for the component integrated with the curved surface to have minimal change in optical properties before and after integration. Note that, unlike the illustrated example, in the display system 2, only one of the first lens unit 16 and the second lens unit 24 may have a curved surface.

[0028] B. Optical Laminate The optical laminate according to an embodiment of the present invention includes a retardation film that exhibits a change in Re(550) of less than 25 nm when stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the lowest temperature (hereinafter also referred to as the "lowest temperature at which 5% stretching is possible") at which 5% stretching is possible in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec (in other words, stretching at a stretch ratio of 1.05 times). A retardation film that exhibits a small change in in-plane retardation when stretched at the lowest possible temperature can suppress retardation changes during curved surface processing (for example, integration with a component having a curved surface). Therefore, by integrating the optical laminate according to an embodiment of the present invention with a first lens unit and / or a second lens unit having a curved surface to form the display system, a display system exhibiting excellent visibility can be suitably obtained.

[0029] 2 is a schematic cross-sectional view showing an outline of the configuration of an optical laminate according to one embodiment of the present invention. The first optical laminate 100 includes a retardation film 21 and a first pressure-sensitive adhesive layer 40. The first pressure-sensitive adhesive layer 40 is located on one outermost surface of the first optical laminate 100. The first optical laminate 100 can be attached to a curved surface portion of a member having a curved surface portion via the first pressure-sensitive adhesive layer 40.

[0030] As the retardation film 21, a retardation film that shows a change in Re(550) of less than 25 nm when stretched by 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the lowest temperature at which 5% stretching is possible can be used.

[0031] The change in Re(550) when the retardation film is stretched 5% in the direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the lowest temperature at which 5% stretching is possible (|Re(550) before 5% stretching - Re(550) after 5% stretching|) is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less. The lower limit of the change in Re(550) can be 0 nm or more.

[0032] The minimum temperature at which the retardation film can be 5% stretched is, for example, the Tg of the retardation film or less, preferably Tg-10°C or less, more preferably Tg-15°C or less, and even more preferably Tg-20°C or less. The lower limit of the temperature is not particularly limited, and may be, for example, Tg-30°C or more. The temperature may be, for example, 140°C or less, 130°C or less, 120°C or less, or 110°C or less, and may be, for example, 80°C or more, 90°C or more, or 100°C or more. A retardation film having a minimum 5% stretchable temperature within the above range and a small change in Re(550) when stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the minimum 5% stretchable temperature can be subjected to curved surface processing at a relatively low heating temperature, and the change in retardation at that time can be suppressed.

[0033] The glass transition temperature (Tg) of the retardation film is preferably 140° C. or lower, for example, 135° C. or lower, or for example, 130° C. or lower. The Tg is preferably 120° C. or higher, for example, 125° C. or higher.

[0034] The smoothness of at least one surface of the retardation film is, for example, 0.5 arcmin or less, preferably 0.45 arcmin or less, more preferably 0.42 arcmin or less. When the smoothness of the retardation film is within the above range, the surface smoothness after curved surface processing is good, and as a result, a display system with excellent visibility can be obtained.

[0035] In one embodiment, the retardation film can function as a λ / 4 component. The in-plane retardation Re(550) of the retardation film functioning as a 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.

[0036] The refractive index characteristics of the retardation film typically exhibit a relationship of nx > ny, preferably a relationship of nx > ny ≥ nz or a relationship of nx > nz > ny, more preferably a relationship of nx > ny > nz or a relationship of nx > nz > ny. Here, "ny = nz" includes not only cases where ny and nz are completely equal, but also cases where they are substantially equal. Therefore, within the scope that does not impair the effects of the present invention, there may be cases where ny < nz. The Nz coefficient of a retardation film whose refractive index characteristics exhibit the relationship of nx > ny ≥ nz is preferably greater than 0.9 and not more than 3, more preferably 1 to 3, even more preferably 1.05 to 3, for example, 1.1 to 3, or for example, 1.4 to 2. The Nz coefficient of a retardation film whose refractive index characteristics exhibit the relationship of nx > nz > ny (hereinafter also referred to as a "Z plate") is preferably 0.9 or less, for example, 0.2 to 0.8, or for example, 0.3 to 0.7.

[0037] The Z-plate can be made of any suitable material that satisfies the above characteristics. The Z-plate is made of, for example, a resin film. Examples of resins that can be used for the Z-plate include polyarylate resins, polyamide resins, polyimide resins, polyester resins, polyaryletherketone resins, polyamideimide resins, polyesterimide resins, polyvinyl alcohol resins, polyfumaric acid ester resins, polyethersulfone resins, polysulfone resins, cycloolefin resins, polycarbonate resins, cellulose resins, and polyurethane resins. These resins can be used alone or in combination.

[0038] As the resin constituting the Z-plate, a cycloolefin resin or a polycarbonate resin is preferable, and a norbornene resin is more preferable.

[0039] Norbornene-based resins are resins polymerized using norbornene-based monomers as polymerization units. Examples of norbornene-based monomers include norbornene and its alkyl and / or alkylidene substituted derivatives such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, and 5-ethylidene-2-norbornene, as well as polar group-substituted derivatives thereof such as halogen; dicyclopentadiene; 2,3-dihydrodicyclopentadiene; Dimethanooctahydronaphthalene, its alkyl and / or alkylidene substituted derivatives, and polar group substituted derivatives such as halogen, for example, 6-methyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4:5,8-dimethano-1,4,4a,5,6, 7,8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:5,8-dimethano and trimers and tetramers of cyclopentadiene, such as 4,9:5,8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene and 4,11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentaanthracene. The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.

[0040] 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 the polycarbonate resins are described, for example, in JP-A-2014-10291, JP-A-2014-26266, JP-A-2015-212816, JP-A-2015-212817, and JP-A-2015-212818, the disclosures of which are incorporated herein by reference.

[0041] In one embodiment, the Z-plate can be obtained by biaxially stretching a resin film containing the above resin as a main component in the in-plane direction and the thickness direction. For example, the Z-plate can be produced by laminating a high-shrinkage film (e.g., a polypropylene film) to both sides of the resin film and heat-stretching the film using a longitudinal uniaxial stretching method using a roll stretching machine. The high-shrinkage film is used to impart a shrinkage force in a direction perpendicular to the stretching direction during heat stretching, thereby increasing the refractive index (nz) of the Z-plate in the thickness direction. There are no particular limitations on the method for laminating the high-shrinkage film to both sides of the resin film, but examples include a method in which an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer is provided between the resin film and the high-shrinkage film to bond them together.

[0042] The thickness of the Z-plate is, for example, 20 μm to 200 μm, or, for example, 30 μm to 150 μm.

[0043] A retardation film whose refractive index characteristics exhibit the relationship nx > ny ≥ nz can be made of any appropriate material that can satisfy the above characteristics. The retardation film is made of, for example, a stretched resin film. Examples of resins contained in the resin film include cycloolefin-based resins (e.g., the above-mentioned norbornene-based resins), polycarbonate-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polysulfone-based resins, etc. Such resins can be used alone or in combination. The resin film preferably contains a norbornene-based resin and / or a polycarbonate-based resin.

[0044] Stretching methods for the resin film include uniaxial stretching, in which the film is stretched in one in-plane direction, and biaxial stretching, in which the film is stretched in two in-plane directions (resulting in the nx and ny directions). From the viewpoint of suitability for curved surface processing, biaxial stretching is more preferred. Stretching may be free-end stretching or fixed-end stretching. While free-end uniaxial stretching can cause neck-in in a direction perpendicular to the stretching direction, in this specification, stretching in one in-plane direction that prevents such neck-in is treated as biaxial stretching. Therefore, for example, longitudinal stretching performed while fixing the width, or widthwise stretching performed while transporting a long film in the longitudinal direction, are treated as biaxial stretching because they do not cause neck-in in a direction perpendicular to the stretching direction. Stretching conditions can be appropriately set depending on the material forming the resin film, the desired optical properties, and the like. The stretching temperature is, for example, 135°C to 165°C, or, for example, 140°C to 160°C. The stretching ratio is, for example, 1.2 to 3.2 times, or, for example, 1.3 to 3.1 times. Details of the method for producing a retardation film whose refractive index characteristics show the relationship of nx>ny≧nz are described in JP 2018-205485 A and the like, and the description of this publication is incorporated herein by reference.

[0045] The thickness of the retardation film whose refractive index characteristics satisfy the relationship nx>ny≧nz is, for example, 10 μm to 80 μm, or, for example, 15 μm to 60 μm.

[0046] The adhesive constituting the first adhesive layer 40 typically contains a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. Preferably, the adhesive is a (meth)acrylic adhesive containing a (meth)acrylic polymer as a main component. The thickness of the first adhesive layer 40 is, for example, 12 μm or more, preferably 15 μm or more, and for example, 100 μm or less, preferably 80 μm or less.

[0047] FIG. 3 is a schematic cross-sectional view showing the overall configuration of an optical laminate according to one embodiment of the present invention. The second optical laminate 200 includes a second retardation member 22 and a second pressure-sensitive adhesive layer 41. The second pressure-sensitive adhesive layer 41 is disposed on one outermost surface of the second optical laminate 200. The second optical laminate 200 can be integrally formed with the first lens unit 16 via the second pressure-sensitive adhesive layer 41, thereby providing a display system 2 in which the second retardation member 22 is integrally formed with the first lens unit 16. The second optical laminate 200 further includes a first protective member 31 disposed in front of the second retardation member 22. The first protective member 31 is laminated to the second retardation member 22 via an adhesive layer (e.g., an adhesive layer or a pressure-sensitive adhesive layer) not shown. The first protective member 31 can be located on the outermost surface of the second optical laminate 200. Although not shown, until the second optical laminate 200 is put into use, a release liner may be temporarily attached to the surface of the second adhesive layer 41, and a surface protection film may be temporarily attached to the surface of the first protective member 31.

[0048] In the example shown in FIG. 3 , the second phase difference member 22 includes, in addition to a 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 positive C plate 22b. By using the positive C plate, light leakage (e.g., light leakage in oblique directions) can be prevented in the display system 2. As shown in FIG. 3 , in the second phase difference member 22, the second λ / 4 member 22a is preferably positioned further forward than the positive C plate 22b. The second λ / 4 member 22a and the positive C plate 22b are laminated together, for example, via an adhesive layer (not shown).

[0049] The second λ / 4 member 22a can be described in the same manner as the retardation film 21 that can function as a λ / 4 member in the first optical laminate shown in Fig. 2. According to the second optical laminate 200 including, as the second λ / 4 member, a retardation film that has a small amount of change in Re(550) when stretched by 5% in a direction perpendicular to the slow axis at the lowest temperature at which 5% stretching is possible, a change in the in-plane retardation of the second λ / 4 member 22a when integrated with the first lens portion having a curved surface portion can be suppressed.

[0050] The thickness direction retardation Rth(550) of the positive C plate 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 positive C plate is, for example, less than 10 nm.

[0051] The positive C plate can be formed from 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 paragraphs

[0020] to

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

[0052] The first protective member 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.

[0053] 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 can be arranged so that the surface treatment layer is located on the front side. The surface treatment layer can have any appropriate function. For example, from the viewpoint of improving visibility, the surface treatment layer preferably has an anti-reflection function. The surface treatment layer may also include a hard coat layer. The thickness of the surface treatment layer is preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and even more preferably 3 μm to 10 μm.

[0054] The same explanation as for the first pressure-sensitive adhesive layer 40 shown in FIG. 2 can be applied to the second pressure-sensitive adhesive layer.

[0055] FIG. 4 is a schematic cross-sectional view showing the overall configuration of an optical laminate according to one embodiment of the present invention. The third optical laminate 300 includes, in this order, a reflective polarizing member 14, a third phase difference member 26, and a third pressure-sensitive adhesive layer 42. The third pressure-sensitive adhesive layer 42 is disposed on one outermost surface of the third optical laminate 300. The third optical laminate 300 can be integrally provided with the second lens unit 24 via the third pressure-sensitive adhesive layer 42, thereby providing a display system 2 in which the reflective polarizing member 14 is integrally provided with the second lens unit 24. The third optical laminate 300 further includes, for example, an absorbing polarizing member 28 disposed between the reflective polarizing member 14 and the third phase difference member 26, from the viewpoint of improving visibility. The reflection axis of the reflective polarizing member 14 and the absorption axis of the absorbing polarizing member 28 can be disposed approximately parallel to each other, and the transmission axis of the reflective polarizing member 14 and the transmission axis of the absorbing polarizing member 28 can be disposed approximately parallel to each other.

[0056] The third phase difference member 26 includes a third λ / 4 member. The angle between the transmission axis of the reflective polarizing member 14 and the slow axis of the third λ / 4 member included in the third phase difference member 26 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°. By providing the third phase difference member, for example, in the display system 2, it is possible to prevent reflection of external light from the second lens unit 24 side. When the third phase difference member does not include any member other than the third λ / 4 member, the third phase difference member may correspond to the third λ / 4 member.

[0057] The third λ / 4 member can be described in the same manner as the retardation film 21 that can function as a λ / 4 member in the first optical laminate shown in Fig. 2. According to the third optical laminate 300 including, as the third λ / 4 member, a retardation film that exhibits a small change in Re(550) when stretched by 5% in the direction perpendicular to the slow axis at the lowest temperature at which 5% stretching is possible, a change in the in-plane retardation of the third λ / 4 member when integrated with the second lens portion having a curved surface portion can be suppressed.

[0058] The third optical stack 300 further includes a second protective member 32 disposed behind the reflective polarizing member 14. The second protective member 32 may be located on the outermost surface of the third optical stack 300. In the display system 2, the first protective member 31 and the second protective member 32 may be disposed opposite each other with a space therebetween. Like the first protective member, the second protective member may typically be a laminate film having a substrate and a surface treatment layer. In this case, the surface treatment layer may be located on the outermost surface of the third optical stack. The same description as for the first protective member can be applied to the details of the second protective member.

[0059] In the third optical laminate 300, the second protective member 32, the reflective polarizing member 14, the absorptive polarizing member 28, and the third phase difference member 26 are typically laminated via an adhesive layer (e.g., an adhesive layer or a pressure-sensitive adhesive layer) not shown. Although not shown, a release liner may be temporarily attached to the surface of the third pressure-sensitive adhesive layer 42, and a surface protection film may be temporarily attached to the surface of the second protective member 32 until the third optical laminate 300 is used.

[0060] The reflective polarizing element transmits light polarized parallel to its transmission axis (typically, linearly polarized light) while maintaining its polarization state, and can reflect light polarized in other states (typically, light polarized perpendicular to its transmission axis). The reflective polarizing element is typically composed of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing element is, for example, 10 μm to 150 μm, preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

[0061] Commercially available reflective polarizing films include, for example, "DBEF" and "APF" manufactured by 3M, and "APCF" manufactured by Nitto Denko Corporation.

[0062] The crossed transmittance (Tc) of the reflective polarizing element (reflective polarizing film) can be, for example, 0.01% to 3%. The single transmittance (Ts) of the reflective polarizing element (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing element (reflective polarizing film) can be, for example, 92% to 99.99%.

[0063] The crossed transmittance, single transmittance, and degree of polarization can be measured, for example, using an ultraviolet-visible spectrophotometer. The degree of polarization P can be calculated from the obtained Tp and Tc by measuring the single transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc using an ultraviolet-visible spectrophotometer, using the following formula: Ts, Tp, and Tc are Y values ​​measured using a 2-degree visual field (C light source) according to JIS Z 8701 and corrected for visibility. Degree of polarization P (%) = {(Tp - Tc) / (Tp + Tc)} １／２ ×100

[0064] The absorptive polarizing member may typically include a resin film (sometimes referred to as an absorptive polarizing film) containing a dichroic material. 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, 12 μm or less, 10 μm or less, 8 μm or less, or 5 μm or less.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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 further 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, as necessary. 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 a dyeing treatment and an underwater stretching treatment.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.

[0069] The crossed transmittance (Tc) of the absorptive polarizing element (absorptive polarizing film) is preferably 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The single transmittance (Ts) of the absorptive polarizing element (absorptive polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing element (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.9% or more.

[0070] The same explanation as for the first pressure-sensitive adhesive layer 40 shown in FIG. 2 can be applied to the third pressure-sensitive adhesive layer.

[0071] C. Manufacturing Method of Optical Member A manufacturing method of an optical member according to an embodiment of the present invention includes heating an optical laminate including a retardation film to integrate it with a member having a curved surface portion. As the optical laminate, for example, the optical laminate described in Section B is used. As the member having a curved surface portion, any appropriate member can be used depending on the purpose, and a lens is a preferred example. The member having a curved surface portion can be, for example, the first lens portion and / or the second lens portion in the display system described in Section A.

[0072] The radius of curvature of the curved surface of the member having a curved surface is, for example, 20 mm or more, for example, 25 mm or more, or for example, 30 mm or more, and is, for example, 150 mm or less, preferably 125 mm or less, more preferably 110 mm or less, and may be 90 mm or less. The diameter (major axis) of the member having a curved surface can be, for example, 20 mm to 80 mm, or for example, 30 mm to 70 mm.

[0073] The optical laminate is integrated with a member having a curved surface while the optical laminate is heated. The temperature of the optical laminate during the integration is, for example, 140° C. or lower, preferably 130° C. or lower, more preferably 120° C. or lower, and even more preferably 110° C. or lower. The lower limit of the temperature is not limited as long as the integration can be performed without causing breakage of the optical laminate, and can be, for example, 100° C. or higher.

[0074] When the glass transition temperature of the retardation film is A°C and the heating temperature (temperature of the optical laminate) during the integration is B°C, A and B typically satisfy the relationship B≦A×1.05. A and B preferably satisfy the relationship B≦A, more preferably the relationship B≦A×0.95, and even more preferably the relationship B≦A×0.9. When A and B satisfy the above relationship, the change in retardation of the retardation film during curved surface processing can be suppressed.

[0075] When the minimum temperature at which the retardation film can be stretched by 5% is C°C, B and C typically satisfy the relationship B≧C (therefore, A, B, and C typically satisfy the relationship C≦B≦A×1.05). B and C preferably satisfy the relationship C≦B<C+20, more preferably the relationship C≦B<C+15, and even more preferably the relationship C≦B<C+10. When B and C satisfy the above relationship, curved surface processing can be suitably performed while suppressing breakage and retardation change of the retardation film.

[0076] The optical laminate can be integrated with a member having a curved surface by any suitable method. Figures 5A to 5C are diagrams showing an example of a method for integrating an optical laminate including a retardation film with a member having a curved surface.

[0077] 5A shows a state in which a workpiece 4 is prepared by cutting an optical laminate into a desired shape and the workpiece 4 is placed above an adherend, which is a member (lens) L. In Figures 5A to 5C, the surface of the workpiece 4 facing the lens L is an adhesive layer.

[0078] The lens L is, for example, circular in plan view and has an upwardly concave shape in cross section. The workpiece 4 is held above the concave surface (top surface) of the lens L by a holder (not shown). In this state, the workpiece 4 can be heated. The shape of the workpiece 4 can easily be deformed by heating. The shape of the workpiece 4 in plan view is not limited to a circle. Specifically, the shape of the workpiece 4 in plan view may be approximately elliptical or rectangular with rounded corners.

[0079] Once the workpiece 4 has reached a state where it is easily deformed, the entire surface of the workpiece 4 is bonded to the lens L by any appropriate method (for example, by utilizing a pressure difference), as shown in Fig. 5B. Thereafter, as shown in Fig. 5C, unnecessary portions of the workpiece 4 (for example, portions that do not overlap with the lens L in a plan view) are removed, thereby obtaining the optical element 5. In the illustrated example, the workpiece 4 is integrated with the concave surface of the lens L, but in the method for manufacturing an optical element according to an embodiment of the present invention, the optical laminate may be integrated with the convex surface of a member having a convex portion.

[0080] The present invention will be described in detail below using examples, but the present invention is not limited to these examples. The measurement methods used in the examples are as follows. <Thickness> Thicknesses of 10 μm or less were measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <In-plane retardation Re (λ) and thickness direction retardation Rth> Retardation film not integrated into a curved member A sample was prepared by cutting a retardation film into a square shape 50 mm wide and 50 mm long, with one side parallel to the width direction of the film. The in-plane retardation and thickness direction retardation of this sample at each wavelength at 23°C were measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"). Retardation film integrated into a curved member The in-plane retardation at each wavelength at 23 ° C was measured using a retardation / ellipsometry device (manufactured by Oji Scientific Instruments, product names "KOBRA-HBR" and "KOBRA-HBPR"). <Refractive index> The average refractive index was measured using an Abbe refractometer manufactured by Atago Co., Ltd., and the refractive indices nx, ny, and nz were calculated from the in-plane retardation and thickness direction retardation. <Smoothness> Smoothness was measured using a phase-shifting laser interferometer (manufactured by Zygo, product name "DynaFiz"). Specifically, the retardation film was laminated onto a microslide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200200") to prevent the inclusion of foreign matter, bubbles, and deformation streaks. Next, degassing was performed using a pressure degassing device (autoclave) to remove the influence of minute bubbles. The degassing conditions were 50 ° C, 0.5 MPa, and 30 minutes. After degassing, the sample was allowed to cool at room temperature for 30 minutes or more to obtain a measurement sample. The measurement sample was placed on a measurement table with an anti-vibration table, and a single-wavelength (633 nm) laser was used to interfere with a standard whose flatness was guaranteed, and the relative displacement within a specified area (a circle with a diameter of 30 mm) was measured. For analysis, the smoothness (unit: arcmin) was defined as doubling the "Slope magnitude RMS" angle index obtained by extracting frequency values ​​from 0.1 / mm to 1 / mm (corresponding to 2σ).<Glass Transition Temperature (Tg)> The glass transition temperature of the resin film was measured using a differential scanning calorimeter (DSC6220, manufactured by SII NanoTechnology Inc.). Approximately 10 mg of a resin or resin film sample was placed in an aluminum pan manufactured by the same company, sealed, and heated from 30°C to 200°C at a heating rate of 20°C / min under a nitrogen gas flow of 50 mL / min. After holding the temperature for 3 minutes, the sample was cooled to 30°C at a rate of 20°C / min. The sample was held at 30°C for 3 minutes and then heated again to 200°C at a rate of 20°C / min. From the DSC data obtained in the second heating run, the extrapolated glass transition onset temperature was determined, which was the temperature at the intersection of a straight line extending the low-temperature baseline to the high-temperature side and a tangent drawn at the point where the gradient of the stepwise change in the glass transition curve was maximized, and this was taken as the glass transition temperature.

[0081] Example 1 A commercially available long biaxially stretched resin film containing a cycloolefin polymer as a main component (manufactured by Zeon Corporation, trade name "ZEONORFILM ZD12", thickness: 32 μm, glass transition temperature: 128° C.) was used as the retardation film 1. This retardation film 1 exhibited refractive index characteristics of nx>ny>nz, with an Re(550) of 141 nm and an Nz coefficient of 1.6. The smoothness of the retardation film 1 was 0.20 arcmin. An acrylic pressure-sensitive adhesive layer was transferred from a laminate of a release liner and an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to one side of the retardation film 1 to obtain an optical laminate 1 having a configuration of [retardation film 1 / acrylic pressure-sensitive adhesive]. The optical laminate 1 was bonded, via the acrylic pressure-sensitive adhesive layer, to the concave surface of a lens having a circular shape with a diameter of 50 mm in plan view and a concave surface with a radius of curvature of 40 mm. 5A to 5C, the optical laminate 1 was set so that the surface of the pressure-sensitive adhesive layer was in contact with the edge of the concave side of the lens, and the optical laminate 1 was heated to a predetermined temperature and pressed into the concave side to be bonded to the concave surface of the lens. In this way, an optical member 1, which is an integrated product of the optical laminate 1 and the lens, was obtained. The temperature of the optical laminate during the curved surface processing was measured using a non-contact thermometer.

[0082] Example 2 A commercially available long resin film (manufactured by Zeon Corporation, trade name "ZEONORFILM ZF14", thickness: 40 μm, glass transition temperature: 132° C.) containing a cycloolefin polymer as a main component was uniaxially stretched in the MD direction (longitudinal direction) while adjusting the stretching temperature and stretching ratio so that the Re (550) was 139 nm and the Nz coefficient was 1.0, thereby obtaining a retardation film 2. The retardation film 2 exhibited refractive index characteristics of nx > ny = nz. The smoothness of the retardation film 2 was 0.60 arcmin. An acrylic pressure-sensitive adhesive layer was transferred from a laminate of a release liner and an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to one side of the retardation film 2, thereby obtaining an optical laminate 2 having a configuration of [retardation film 2 / acrylic pressure-sensitive adhesive]. An optical member 2, which is an integrated product of the optical laminate 2 and a lens, was obtained in the same manner as in Example 1, except that the optical laminate 2 was used.

[0083] Example 3 A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was charged with 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spiroglycol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10 mol of calcium acetate monohydrate as a catalyst. －２ Part by weight (6.78 x 10 －５mol) was charged. After purging the reactor with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was initiated when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was initiated. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and a small amount of monomer components contained in the phenol vapor were returned to the reactor, while uncondensed phenol vapor was introduced into a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor, and the pressure was temporarily restored to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, heating and pressure reduction in the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was achieved. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, and the resulting polyester carbonate resin was extruded into water and cut into strands to obtain pellets. The obtained polyester carbonate resin (pellets) was vacuum-dried at 80 ° C for 5 hours, and then 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 200 mm, setting temperature: 250 ° C), a chill roll (setting temperature: 120-130 ° C) and a winder was used to produce a long resin film having a Tg of 138 ° C and a thickness of 130 μm. The obtained long resin film was stretched 2.7 times in the width direction at a stretching temperature of 140 ° C and wound into a roll. In this way, a retardation film 3 having a thickness of 47 μm, an Re (590) of 140 nm, and an Nz coefficient of 1.2 was obtained. The obtained retardation film 3 had an Re(450) / Re(550) of 0.856, and exhibited reverse dispersion wavelength characteristics. The smoothness of the retardation film 3 was 0.25 arcmin. An acrylic pressure-sensitive adhesive layer was transferred from a laminate of a release liner and an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to one surface of the retardation film 3, thereby obtaining an optical laminate 3 having a configuration of [retardation film 3 / acrylic pressure-sensitive adhesive]. An optical member 3, which was an integrated product of the optical laminate 3 and a lens, was obtained in the same manner as in Example 1, except that the optical laminate 3 was used.

[0084] Example 4 A commercially available long resin film (manufactured by JSR Corporation, trade name "Arton (R5000)", thickness: 130 μm, glass transition temperature: 135°C) containing a cycloolefin polymer as a main component was used. A 60 μm thick shrinkable film (manufactured by Toray Industries, trade name "Torayfan BO2873") was attached to both sides of the film via an acrylic pressure-sensitive adhesive layer (thickness: 15 μm), and subjected to free-end uniaxial stretching to obtain a retardation film 4. The stretching temperature was 165°C, and the stretching ratio was 1.20 times. The retardation film 4 was a biaxially stretched film stretched in the slow axis direction and thickness direction. The retardation film 4 exhibited refractive index characteristics of nx>nz>ny, had an Re(550) of 140 nm, and an Nz coefficient of 0.5. The smoothness of the retardation film 4 was 0.40 arcmin. An acrylic pressure-sensitive adhesive layer was transferred from a laminate of a release liner and an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to one surface of a retardation film 4, thereby obtaining an optical laminate 4 having a configuration of [retardation film 4 / acrylic pressure-sensitive adhesive]. An optical member 4, which is an integrated product of the optical laminate 4 and a lens, was obtained in the same manner as in Example 1, except that the optical laminate 4 was used.

[0085] [Comparative Example 1] In the same manner as in Example 3, a long polyester carbonate resin film having a Tg of 138 ° C. and a thickness of 130 μm was produced. The obtained long resin film was free-end uniaxially stretched in the MD direction at a stretching temperature of 140 ° C. at 1.8 times. In this way, a retardation film C1 having a thickness of 47 μm, an Re (590) of 147 nm, and an Nz coefficient of 1.0 was obtained. The obtained retardation film C1 had an Re (450) / Re (550) of 0.856 and exhibited reverse dispersion wavelength characteristics. The smoothness of the retardation film C1 was 0.52 arcmin. An acrylic pressure-sensitive adhesive layer was transferred from a laminate of a release liner and an acrylic pressure-sensitive adhesive layer (thickness: 23 μm) to one side of the retardation film C1 to obtain an optical laminate C1 having a configuration of [retardation film C1 / acrylic pressure-sensitive adhesive]. An optical member C1, which was an integrated product of the optical laminate C1 and a lens, was obtained in the same manner as in Example 1, except that the optical laminate C1 was used.

[0086] <Evaluation of Stretchability of Retardation Film> The retardation films obtained in the above Examples and Comparative Examples were cut into rectangular shapes with a length of 40 mm and a width of 40 mm. The obtained retardation films were stretched under the following conditions. Processing device: Batch-type biaxial stretching machine Stretching temperature: 100°C to 150°C Stretching ratio: 1.05 times Stretching speed: 2 mm / sec Stretching direction: Direction perpendicular to the slow axis The minimum temperature at which stretching was possible without breaking under the above conditions (minimum temperature at which 5% stretching was possible) and the change in Re(550) of the retardation film after stretching at the minimum temperature (|Re(550) before stretching - Re(550) after stretching|) are shown in Tables 1-1 to 1-5.

[0087] <Evaluation of Appearance of Optical Member> The appearance of the optical members obtained in the above Examples and Comparative Examples was visually observed and evaluated according to the following criteria. The results are shown in Table 1. Good (◯): An optical member with no problems in appearance could be obtained. Fair (Δ): Slight wrinkles were observed in the optical laminate. Poor (×): The retardation film in the optical laminate was broken, making it impossible to obtain an optical member, or an optical member was obtained but large wrinkles occurred in the optical laminate.

[0088] <Retardation Evaluation of Optical Members> The Re(550) of the retardation film at the center of the curved surface of each of the optical members obtained in the above Examples and Comparative Examples was measured and used as the Re(550) of the retardation film after integration. Next, the change in Re(550) of the retardation film due to integration (|Re(550) of the retardation film before integration - Re(550) of the retardation film after integration|) was calculated.

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] <Retardation Change Due to Heating of Retardation Film> The retardation films obtained in the above Examples and Comparative Examples were cut into rectangular shapes of 40 mm in length and 40 mm in width, and were attached to a glass plate via an acrylic adhesive layer. This resulted in a measurement sample having a configuration of [retardation film / adhesive layer / glass plate]. This measurement sample was placed on a hot plate at 80°C to 150°C and heated for 60 seconds. At this time, the measurement sample was positioned so that the surface on the retardation film side was in contact with the hot plate. The difference in Re(550) of the measurement sample before and after heating (|Re(550) before heating - Re(550) after heating|) is shown in Table 2.

[0095]

[0096] As shown in Table 2, the in-plane retardation of each retardation film changed when heated at a high temperature. Therefore, it can be seen that sufficient visibility may not be obtained in a display system using a retardation film that has been curved at a high temperature. In contrast, as shown in Tables 1-1 to 1-5, a retardation film that can be stretched at a relatively low heating temperature, which suppresses the change in in-plane retardation, can be curved in a heated state without significantly changing the in-plane retardation of the retardation film. For example, an optical laminate including a retardation film whose change in Re (550) when stretched 5% at the lowest possible temperature for 5% stretching is less than 25 nm can be integrated with a curved portion at a heating temperature of, for example, 140 ° C. or less, preferably 130 ° C., more preferably 120 ° C. or less. While suppressing the occurrence of breakage and wrinkles in the retardation film, the change in Re (550) before and after integration can be, for example, 30 nm or less, preferably 25 nm or less, more preferably 20 nm or less.

[0097] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose.

[0098] The method for manufacturing an optical member according to an embodiment of the present invention can be suitably used in manufacturing a display such as VR goggles, for example.

[0099] 2 Display system 12 Display element 14 Reflective polarizing member 16 First lens portion 18 Half mirror 20 First phase difference member 22 Second phase difference member 24 Second lens portion 100 First optical laminate 200 Second optical laminate 300 Third optical laminate

Claims

1. A method for producing an optical member, comprising heating an optical laminate including a retardation film and integrating it with a member having a curved surface, wherein, when the glass transition temperature of the retardation film is A°C, the temperature of the optical laminate during the integration is B°C, and the lowest temperature at which the retardation film can be stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec is C°C, A, B, and C satisfy the relationship C≦B≦A×1.05, and the amount of change in Re(550) when the retardation film is stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at C°C is less than 25 nm.

2. The manufacturing method according to claim 1, wherein B is 140 or less.

3. The manufacturing method according to claim 1, wherein B is 130 or less.

4. The manufacturing method according to claim 1, wherein the radius of curvature of the curved surface portion is 20 mm to 150 mm.

5. The manufacturing method according to claim 1, wherein the component having the curved surface is the first lens component in a display system that displays an image to a user, comprising: a display element having a display surface that emits light representing an image forward via a polarizing component; a reflective polarizing component that is disposed in front of the display element and reflects the light emitted from the display element; a first lens component that is disposed on an optical path between the display element and the reflective polarizing component; a half mirror that is disposed between the display element and the first lens component and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing component towards the reflective polarizing component; a first λ / 4 component that is disposed on an optical path between the display element and the half mirror; and a second λ / 4 component that is disposed on an optical path between the half mirror and the reflective polarizing component.

6. The manufacturing method according to claim 1, wherein the component having a curved surface is the first lens component and / or the second lens component in a display system that displays an image to a user, comprising: a display element having a display surface that emits light representing an image forward via a polarizing component; a reflective polarizing component arranged in front of the display element and reflecting the light emitted from the display element; a first lens component arranged on an optical path between the display element and the reflective polarizing component; a half mirror arranged between the display element and the first lens component, that transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing component towards the reflective polarizing component; a second lens component arranged in front of the reflective polarizing component; a first λ / 4 component arranged on the optical path between the display element and the half mirror; a second λ / 4 component arranged on the optical path between the half mirror and the reflective polarizing component; and a third λ / 4 component arranged between the reflective polarizing component and the second lens component.

7. An optical laminate comprising a retardation film whose change in Re(550) is less than 25 nm when stretched 5% in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec at the lowest temperature at which 5% stretching is possible in a direction perpendicular to the slow axis at a stretching rate of 2 mm / sec.

8. The optical laminate according to claim 7, wherein the retardation film has an Re(550) of 100 nm to 190 nm.

9. The optical laminate according to claim 7, wherein a pressure-sensitive adhesive layer is disposed on one of the outermost surfaces.

10. The optical laminate according to claim 7, wherein the retardation film is a biaxially stretched film.

11. The optical laminate according to claim 7, wherein the retardation film has an Nz coefficient of 0.9 or less or 1.05 or more.

12. The optical laminate according to claim 7, wherein the smoothness of the retardation film is 0.5 arcmin or less.

13. The optical laminate according to claim 7, which is to be integrated into a member having a curved surface.

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