Optical laminate, lens part, and display method

Abstract

Provided is an optical laminate that makes it possible to satisfactorily reduce the weight of VR goggles while improving visibility. This optical laminate comprises: a laminated film having a base material and a hard coat layer; and an absorption-type polarization member including an absorption-type polarization film. The shrinkage force S (unit: N) at 120°C of the absorption-type polarization film and the product Er120•T (GPa•μm) of the elastic modulus Er120 (unit: GPa) and the thickness T (unit: μm) at 120°C of the hard coat layer satisfy the relationship of Er120•T > 0.85×S-4.02.

Description

Optical laminate, lens part and display method

[0001] The present invention relates to an optical laminate, a lens portion, and a display method.

[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. Optical components such as retardation components and polarizing components are generally used in image display devices to realize image display and improve image display performance (see, for example, Patent Document 1). These optical components can be integrated in advance and mounted on the image display device as an optical laminate.

[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] The weight of the VR goggles can be reduced by, for example, thinning the lenses used in the VR goggles. On the other hand, there is also a need for the development of an optical laminate including the optical member described above that is suitable for a display system using thin lenses.

[0006] In view of the above, the main object of the present invention is to provide an optical laminate that can effectively achieve weight reduction of VR goggles while improving visibility.

[0007] 1. An optical laminate according to an embodiment of the present invention comprises a laminate film having a substrate and a hard coat layer, and an absorptive polarizing member including an absorptive polarizing film, and is characterized in that the contraction force S (unit: N) of the absorptive polarizing film at 120°C and the elastic modulus Er of the hard coat layer at 120°C are １２０ (unit: GPa) and thickness T (unit: μm) １２０ T (GPa μm) is Er １２０The relationship T > 0.85 × S - 4.02 is satisfied. 2. The optical laminate described in 1 above may include the laminate film, the absorptive polarizing element, and another optical element in this order, and the absorptive polarizing element and the other optical element may be laminated via a pressure-sensitive adhesive layer. 3. In the optical laminate described in 2 above, the other optical element may be a reflective polarizing element. 4. In the optical laminate described in 2 or 3 above, the peel force of the absorptive polarizing element from the pressure-sensitive adhesive layer may be 2 N / 25 mm or more. 5. The optical laminate described in any one of 1 to 4 above may include a retardation element disposed between the laminate film and the absorptive polarizing element. 6. In the optical laminate described in any one of 1 to 5 above, the absorptive polarizing element may include a protective layer. 7. The optical laminate described in any one of 1 to 6 above may include a pressure-sensitive adhesive layer disposed between the laminate film and the absorptive polarizing element, and the pressure-sensitive adhesive layer may have a thickness of 12 μm or less. 8. 9. In the optical laminate according to any one of the above items 1 to 7, the hard coat layer may have an elastic modulus Er at room temperature of 5 GPa or more. 10. In the optical laminate according to any one of the above items 1 to 8, the hard coat layer may have an elastic modulus Er at 120°C relative to the elastic modulus Er at room temperature of the hard coat layer. １２０ The ratio Er １２０ / Er may be 0.25 or more.

[0008] 10. A lens unit according to an embodiment of the present invention is a lens unit used in a display system that displays an image to a user, and includes: the optical laminate according to any one of 3 to 9 above, which reflects light that is emitted forward from a display surface of a display element that displays an image and that has passed through a polarizing element and a first λ / 4 element; a first lens unit that is arranged on an optical path between the display element and the optical laminate; a half mirror that is arranged between the display element and the first lens unit, which transmits light that is emitted from the display element and reflects light reflected by the reflective polarizing element of the optical laminate toward the reflective polarizing element; and a second λ / 4 element that is arranged on the optical path between the half mirror and the optical laminate. A display method according to an embodiment of the present invention includes the steps of passing light representing an image emitted through a polarizing element and a first λ / 4 element through a half mirror and a first lens element, passing the light that has passed through the half mirror and the first lens element through a second λ / 4 element, reflecting the light that has passed through the second λ / 4 element toward the half mirror with the optical laminate described in any one of items 3 to 9 above, and allowing the light reflected by the reflective polarizing element and the half mirror of the optical laminate to transmit through the reflective polarizing element with the second λ / 4 element. 12. A method for manufacturing a lens element according to an embodiment of the present invention is the method for manufacturing a lens element described in item 10 above, and including heating the optical laminate to integrate the optical laminate with the first lens element.

[0009] According to the optical laminate according to the embodiment of the present invention, it is possible to effectively achieve a reduction in the weight of VR goggles while improving visibility.

[0010] 1 is a schematic cross-sectional view showing the general configuration of an optical laminate according to one embodiment of the present invention; FIG. 2 is a schematic diagram showing the general configuration of an example of a display system for VR goggles; FIG. 3 is a schematic cross-sectional view showing an example of a state in which another optical member is laminated on the absorptive polarizing member of the optical laminate shown in FIG. 1; FIG. 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film; and FIG. 5 is a schematic cross-sectional view showing the general configuration of an optical laminate according to one embodiment of the present invention; and FIG. 6 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. Regarding the reliability evaluation results, the contraction force S of the absorptive polarizing film at 120°C and the elastic modulus Er of the hard coat layer at 120°C were measured. １２０and the thickness T １２０ Graph showing the relationship between the temperature and T.

[0011] 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.

[0012] (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) x 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 mentioned in this specification, the angle includes both clockwise and counterclockwise angles relative to the reference direction. Therefore, for example, "45°" means ±45°.

[0013] [Optical Laminate] FIG. 1 is a schematic cross-sectional view showing the general configuration of an optical laminate according to one embodiment of the present invention.

[0014] The optical laminate 1 includes an absorptive polarizing element 28 and a laminate film 31. The absorptive polarizing element 28 includes at least an absorptive polarizing film 28a. In the example shown in FIG. 1 , the absorptive polarizing element 28 includes a protective layer 28b in addition to the absorptive polarizing film 28a. The absorptive polarizing film 28a and the protective layer 28b are laminated via an adhesive layer 51. Specifically, the absorptive polarizing element 28 includes the absorptive polarizing film 28a, the adhesive layer 51, and the protective layer 28b. Unlike the example shown in FIG. 1 , the protective layer 28b may be provided on the side of the absorptive polarizing film 28a where the laminate film 31 is disposed. Alternatively, the protective layer 28b may be omitted. In this case, the absorptive polarizing element 28 may correspond to an absorptive polarizing film.

[0015] The laminate film 31 has a substrate 31a and a surface treatment layer 31b formed on the substrate 31a. The surface treatment layer 31b includes at least a hard coat layer. In the optical laminate 1, the laminate film 31 can be arranged so that the surface treatment layer (hard coat layer) 31b is located outside the substrate 31a. The laminate film 31 can protect the absorptive polarizing member 28. Specifically, the laminate film 31 can function as a protective member in the optical laminate 1.

[0016] 1 , the retardation member 30 is provided between the absorptive polarizing member 28 and the laminate film 31. An adhesive layer (e.g., a pressure-sensitive adhesive layer) may be used to laminate the respective members. For example, the laminate film 31 and the retardation member 30 are laminated via a pressure-sensitive adhesive layer 41. The retardation member 30 and the absorptive polarizing member 28 are laminated via a pressure-sensitive adhesive layer 42.

[0017] The absorptive polarizing film 28a included in the absorptive polarizing member 28 is typically composed of a film containing a dichroic material such as iodine or an organic dye. The thickness of the absorptive polarizing film 28a 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 6 μm or less. An absorptive polarizing film with a small thickness may have excellent smoothness, for example.

[0018] The optical laminate 1 may be heated. For example, it may be heated when it is mounted on a display. The absorptive polarizing film 28a may shrink due to heating or the like. In this case, the shrinkage force S of the absorptive polarizing film 28a at 120°C is, for example, 0.1 N to 20 N, and may also be 5 N to 15 N.

[0019] The thickness T of the hard coat layer 31b of the laminated film 31 is preferably 0.5 μm to 10 μm, more preferably 1 μm to 9 μm, even more preferably 2 μm to 8 μm, and particularly preferably 3 μm to 7 μm.

[0020] Elastic modulus Er of hard coat layer 31b at 120°C １２０ is, for example, 0.1 GPa to 5.0 GPa, and may be 0.1 GPa to 3.0 GPa. The contraction force S (unit: N) of the absorptive polarizing film 28a at 120°C and the elastic modulus Er of the hard coat layer 31b at 120°C are １２０ (unit: GPa) and thickness T (unit: μm) １２０ T (GPa μm) is Er １２０ It is preferable to satisfy the relationship T > 0.85 × S - 4.02. By satisfying such a relationship, peeling between components included in the optical laminate can be suppressed. Specifically, peeling between components that may occur when the optical laminate is heated can be suppressed. The optical laminate can be easily deformed by heating, and can be integrated into curved surfaces such as lenses, thereby achieving improved visibility and weight reduction in VR goggles, for example. Therefore, by satisfying the above relationship, the optical laminate can be well integrated into curved surfaces such as lenses. The thin lens can be a curved lens, for example.

[0021] The elastic modulus Er of the hard coat layer 31b at room temperature is preferably 5 GPa or more, more preferably 5.5 GPa or more. By having such a hard coat layer, it can function sufficiently as a hard coat layer or a protective member. Furthermore, by having such a hard coat layer, the function of the functional layer described below (e.g., anti-reflection function) can be ensured. The elastic modulus Er of the hard coat layer at room temperature is, for example, 10 GPa or less.

[0022] The elastic modulus Er of the hard coat layer 31b at 120°C relative to the elastic modulus Er of the hard coat layer 31b at room temperature １２０ The ratio Er １２０ / Er is preferably 0.25 or more, more preferably 0.35 or more. By having such a hard coat layer, defects that may occur in the optical laminate due to heating or the like (for example, the occurrence of waviness, a decrease in smoothness) can be suppressed. The elastic modulus Er of the hard coat layer 31b at 120°C relative to the elastic modulus Er of the hard coat layer 31b at room temperature is １２０ The ratio Er １２０ / Er is, for example, 0.7 or less.

[0023] The optical characteristics (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient) of the phase difference member 30 can be appropriately set depending on the purpose. When the phase difference member 30 has an optical axis (e.g., a slow axis), the optical axis of the phase difference member 30 and the optical axis (e.g., an absorption axis) of the absorbing polarizing film 28a can be aligned at any appropriate angle depending on the purpose, application, etc. For example, when the phase difference member 30 is a λ / 4 member, the angle formed between the absorption axis of the absorbing polarizing film 28a and the slow axis of the phase difference member 30 is, for example, 40° to 50°, may be 42° to 48°, or may be approximately 45°.

[0024] The distance between the hard coat layer 31b and the absorptive polarizing film 28a is, for example, 20 μm or more and 100 μm or less, preferably 90 μm or less, and more preferably 80 μm or less.

[0025] <Absorptive Polarizing Film> The absorptive polarizing element includes an absorptive polarizing film. 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%, 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%, preferably 99.8% or more.

[0026] As described above, the absorptive polarizing film is typically made of a film containing a dichroic substance such as iodine or an organic dye. For example, the absorptive polarizing film may be made of a resin film. In this case, the absorptive polarizing film is preferably a polyvinyl alcohol (PVA) film containing iodine.

[0027] Examples of methods for producing an absorptive polarizing film made of a resin film include forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) and a halide on one side of a long thermoplastic resin substrate to form a laminate, and 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, in which the laminate is heated while being transported in the longitudinal direction to shrink the laminate by 2% or more in the width direction. The thickness of the resulting absorptive polarizing film can be controlled, for example, by adjusting the stretching ratio in the underwater stretching treatment. The shrinkage force of the resulting absorptive polarizing film can be controlled, for example, by adjusting the stretching ratio and / or the stretching temperature in the underwater stretching treatment.

[0028] The PVA-based resin layer is preferably formed by applying a coating liquid containing a PVA-based resin and a halide to a thermoplastic resin substrate and drying the coating liquid. The content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight per 100 parts by weight of the PVA-based resin. The thickness of the PVA-based resin layer is preferably 3 to 40 μm, more preferably 3 to 20 μm.

[0029] Examples of the method for applying the coating liquid include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.), etc. The temperature for applying and drying the coating liquid is preferably 50° C. or higher.

[0030] In order to improve the adhesion between the thermoplastic resin substrate and the PVA-based resin layer, the thermoplastic resin substrate may be subjected to a surface treatment such as a corona treatment before forming the PVA-based resin layer, or an easy-adhesion layer may be formed on the thermoplastic resin substrate.

[0031] The thickness of the thermoplastic resin substrate is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. If the thickness is less than 20 μm, for example, it may be difficult to form a PVA-based resin layer. If the thickness is more than 300 μm, for example, in the underwater stretching treatment described below, it may take a long time for the thermoplastic resin substrate to absorb water, and an excessive load may be required for stretching.

[0032] The water absorption of the thermoplastic resin substrate is preferably 0.2% or more, more preferably 0.3% or more. The thermoplastic resin substrate can absorb water, which acts as a plasticizer to plasticize the substrate. As a result, the stretching stress can be significantly reduced, allowing the substrate to be stretched at a high ratio. On the other hand, the water absorption of the thermoplastic resin substrate is preferably 3.0% or less, more preferably 1.0% or less. Use of such a thermoplastic resin substrate can prevent problems such as a significant decrease in the dimensional stability of the substrate during production, resulting in poor appearance of the resulting absorptive polarizing film. Furthermore, it can prevent breakage of the substrate and peeling of the PVA-based resin layer from the substrate during underwater stretching. The water absorption of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent materials. The water absorption is a value determined in accordance with JIS K 7209.

[0033] The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 120°C or lower. By using such a thermoplastic resin substrate, the stretchability of the laminate can be sufficiently ensured while suppressing crystallization of the PVA-based resin layer. Considering the plasticization of the thermoplastic resin substrate with water and the smooth underwater stretching, the Tg is more preferably 100°C or lower, and even more preferably 90°C or lower. On the other hand, the Tg of the thermoplastic resin substrate is preferably 60°C or higher. By using such a thermoplastic resin substrate, defects such as deformation of the substrate (e.g., the occurrence of unevenness, sagging, wrinkles, etc.) during the application and drying of the coating liquid can be prevented, allowing for the production of a satisfactory laminate. Furthermore, the PVA-based resin layer can be stretched at a suitable temperature (e.g., about 60°C). The glass transition temperature of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material or by heating using a crystallizing material. The glass transition temperature (Tg) is a value determined in accordance with JIS K 7121.

[0034] Examples of thermoplastic resins include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Among these, norbornene resins and amorphous polyethylene terephthalate resins are preferably used.

[0035] In one embodiment, an amorphous (non-crystallized) polyethylene terephthalate resin is preferably used. Among them, an amorphous (hard to crystallize) polyethylene terephthalate resin is preferably used. Specific examples of the amorphous polyethylene terephthalate resin include copolymers further containing isophthalic acid and / or cyclohexanedicarboxylic acid as a dicarboxylic acid, and copolymers further containing cyclohexanedimethanol or diethylene glycol as a glycol.

[0036] In a preferred embodiment, the thermoplastic resin substrate is composed of a polyethylene terephthalate resin having an isophthalic acid unit. Such a thermoplastic resin substrate has excellent stretchability and can suppress crystallization during stretching. This is thought to be due to the introduction of the isophthalic acid unit, which imparts a large curvature to the main chain. The polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit. The content of the isophthalic acid unit is preferably 0.1 mol% or more, more preferably 1.0 mol% or more, based on the total of all repeating units. This is because a thermoplastic resin substrate with extremely excellent stretchability can be obtained. On the other hand, the content of the isophthalic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all repeating units. By setting such a content ratio, the crystallinity can be favorably increased during the drying shrinkage treatment described below.

[0037] The thermoplastic resin substrate may be stretched by any appropriate method before forming the PVA-based resin layer. For example, the long thermoplastic resin substrate may be stretched in the transverse direction. The transverse direction is preferably a direction approximately perpendicular to the stretching direction of the laminate described below. The stretching temperature of the thermoplastic resin substrate is preferably Tg-10°C to Tg+50°C relative to the glass transition temperature (Tg). The stretching ratio of the thermoplastic resin substrate is preferably 1.5 to 3.0 times.

[0038] As described above, the coating liquid may contain a PVA-based resin and a halide. The coating liquid may typically be a solution in which a PVA-based resin and a halide are dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. Among these, water is preferably used. The concentration of the PVA-based resin is preferably 3 to 20 parts by weight per 100 parts by weight of the solvent. The content of the halide in the coating liquid is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, per 100 parts by weight of the PVA-based resin.

[0039] Examples of the PVA-based resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer is obtained by saponifying ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is, for example, 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined in accordance with JIS K 6726-1994. The average polymerization degree of the PVA-based resin is, for example, 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. The average polymerization degree can be determined in accordance with JIS K 6726-1994. Examples of the halide include iodides such as potassium iodide, sodium iodide, and lithium iodide, and sodium chloride. Of these, potassium iodide is preferably used.

[0040] The coating liquid may contain additives. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Examples of surfactants include nonionic surfactants.

[0041] Stretching a PVA-based resin layer can increase the orientation of polyvinyl alcohol molecules in the PVA-based resin. However, immersing the stretched PVA-based resin layer in a liquid containing water can disrupt the orientation of the polyvinyl alcohol molecules, resulting in a decrease in the orientation. When a laminate of a thermoplastic resin substrate and a PVA-based resin layer is stretched in boric acid water at a relatively high temperature to stabilize the stretching of the thermoplastic resin substrate, the orientation tends to decrease significantly. In contrast, high-temperature stretching (auxiliary stretching) in air of a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate before stretching in boric acid water can promote crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after auxiliary stretching. As a result, when the PVA-based resin layer is immersed in a liquid, the disruption of the orientation of polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained by immersing the laminate in a liquid, such as through a dyeing treatment and an underwater stretching treatment.

[0042] To obtain high optical properties, a two-stage stretching method can be selected, combining in-air stretching (auxiliary stretching) and stretching in boric acid water. By introducing auxiliary stretching, stretching can be performed while suppressing crystallization of the thermoplastic resin substrate, thereby solving the problem of reduced stretchability due to excessive crystallization of the thermoplastic resin substrate during subsequent stretching in boric acid water, and allowing the laminate to be stretched at a high magnification. Furthermore, when a PVA-based resin is applied to a thermoplastic resin substrate, the application temperature must be lower than, for example, when the PVA-based resin is applied to a metal drum in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate. As a result, the crystallization of the PVA-based resin is relatively low, which can lead to problems such as insufficient optical properties being obtained. In contrast, by introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA-based resin, even when the PVA-based resin is applied to a thermoplastic resin substrate, and high optical properties can be achieved. At the same time, by increasing the orientation of the PVA-based resin in advance, problems such as a decrease in the orientation of the PVA-based resin or dissolution when the PVA-based resin is immersed in water during subsequent dyeing or stretching treatments can be prevented, and high optical properties can be achieved.

[0043] The method of the auxiliary in-air stretching may be fixed-end stretching (e.g., a method of stretching using a tenter stretching machine) or free-end stretching (e.g., a method of uniaxially stretching a laminate by passing it between rolls having different peripheral speeds). From the viewpoint of obtaining high optical properties, free-end stretching is preferably used.

[0044] The draw ratio of the auxiliary in-air stretching is preferably 2.0 to 3.5. The auxiliary in-air stretching may be carried out in one stage or in multiple stages. When carried out in multiple stages, the draw ratio is the product of the draw ratios in each stage. The stretching direction in the auxiliary in-air stretching is preferably approximately the same as the stretching direction in the underwater stretching.

[0045] The stretching temperature for the auxiliary in-air stretching is preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably equal to or higher than Tg of the thermoplastic resin substrate + 10°C, and even more preferably equal to or higher than Tg of the thermoplastic resin substrate + 15°C. On the other hand, the upper limit of the stretching temperature is preferably 170°C. By stretching at such a temperature, rapid crystallization of the PVA-based resin can be suppressed, thereby suppressing defects due to crystallization (for example, preventing the orientation of the PVA-based resin layer due to stretching). The crystallization index of the PVA-based resin after the auxiliary in-air stretching is preferably 1.3 to 1.8, more preferably 1.4 to 1.7. The crystallization index of the PVA-based resin can be measured by the ATR method using a Fourier transform infrared spectrophotometer. Specifically, the measurement is performed using polarized light as the measurement light, and the crystallization index at 1141 cm of the obtained spectrum is measured. －１ and 1440 cm －１ The crystallization index is calculated using the intensity according to the following formula: Crystallization index = (I Ｃ / I Ｒ ) where I Ｃ is 1141 cm when measured with incident measuring light －１ is the intensity of I Ｒ is 1440 cm when measured with incident measuring light －１ is the strength.

[0046] After the auxiliary air-stretching treatment, an insolubilization treatment may be carried out before the underwater stretching treatment or the dyeing treatment. The insolubilization treatment is typically carried out by immersing the PVA-based resin layer in an aqueous boric acid solution. The insolubilization treatment imparts water resistance to the PVA-based resin layer, thereby preventing a decrease in the orientation of the PVA when immersed in water. The concentration of the aqueous boric acid solution used in the insolubilization treatment is preferably 1 to 4 parts by weight per 100 parts by weight of water. The liquid temperature of the insolubilization bath (aqueous boric acid solution) is preferably 20 to 50°C.

[0047] The dyeing treatment is typically carried out by dyeing the PVA-based resin layer with iodine. Specifically, the dyeing treatment is carried out by allowing the PVA-based resin layer to adsorb iodine. A preferred method for adsorbing iodine is to immerse the PVA-based resin layer (laminate) in a dye solution (dye bath) containing iodine.

[0048] The dye solution is preferably an aqueous iodine solution. In this case, the amount of iodine blended is preferably 0.05 to 0.5 parts by weight per 100 parts by weight of water. To increase the solubility of iodine in water, it is preferable to blend an iodide into the aqueous iodine solution. Examples of iodides include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is preferably used. The amount of iodide blended is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, per 100 parts by weight of water. The temperature of the dye solution during dyeing is preferably 20 to 50°C to suppress dissolution of the PVA-based resin. When the PVA-based resin layer is immersed in the dye solution, the immersion time is preferably 5 seconds to 5 minutes, more preferably 30 seconds to 90 seconds, in order to ensure the transmittance of the PVA-based resin layer.

[0049] The dyeing conditions (concentration, solution temperature, and immersion time) can be set so that the single transmittance and polarization degree of the resulting absorptive polarizing film fall within the above-mentioned ranges. For example, the ratio of the iodine content to the potassium iodide content in the iodine aqueous solution used as the dyeing solution is preferably 1:5 to 1:20, and more preferably 1:5 to 1:10.

[0050] When a dyeing process is performed consecutively after a treatment (e.g., an insolubilization treatment) in which a laminate is immersed in a treatment bath containing boric acid, the boric acid contained in the treatment bath may be mixed into the dye bath, causing the boric acid concentration of the dye bath to change over time, resulting in unstable dyeability. To prevent this instability in dyeability, the upper limit of the boric acid concentration of the dye bath is preferably adjusted to 4 parts by weight, more preferably 2 parts by weight, per 100 parts by weight of water. Meanwhile, the lower limit of the boric acid concentration of the dye bath is preferably 0.1 parts by weight, more preferably 0.2 parts by weight, and even more preferably 0.5 parts by weight, per 100 parts by weight of water. In one embodiment, a dye bath containing boric acid is used in advance. This can reduce the rate of change in boric acid concentration when the boric acid from the treatment bath is mixed into the dye bath. The amount of boric acid to be blended in advance into the dye bath (i.e., the content of boric acid not derived from the treatment bath) is preferably 0.1 to 2 parts by weight, and more preferably 0.5 to 1.5 parts by weight, per 100 parts by weight of water.

[0051] A crosslinking treatment may be performed after the dyeing treatment and before the underwater stretching treatment. The crosslinking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. The crosslinking treatment imparts water resistance to the PVA-based resin layer, thereby preventing a decrease in the orientation of the PVA when the layer is immersed in high-temperature water during the subsequent underwater stretching treatment. The concentration of the aqueous boric acid solution used in the crosslinking treatment is preferably 1 to 5 parts by weight per 100 parts by weight of water. Furthermore, when the crosslinking treatment is performed after the dyeing treatment, it is preferable to further incorporate an iodide. The incorporation of an iodide can suppress the elution of iodine adsorbed to the PVA-based resin layer. The amount of iodide incorporated is preferably 1 to 5 parts by weight per 100 parts by weight of water. Specific examples of iodides are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably 20 to 50°C.

[0052] The underwater stretching treatment is carried out by immersing the laminate in a stretching bath. Underwater stretching treatment allows stretching at a temperature lower than the glass transition temperatures (typically, about 80° C.) of the thermoplastic resin substrate and the PVA-based resin layer, and allows the PVA-based resin layer to be stretched while suppressing crystallization. As a result, a polarizing film having excellent optical properties can be produced.

[0053] Any appropriate method can be adopted as the stretching method for the laminate. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method in which the laminate is uniaxially stretched by passing it between rolls with different peripheral speeds). Preferably, free-end stretching is selected. The stretching of the laminate may be carried out in one stage or in multiple stages. When it is carried out in multiple stages, the stretching ratio of the laminate described below is the product of the stretching ratios in each stage.

[0054] The underwater stretching is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid solution). Using an aqueous boric acid solution as a stretching bath can impart to the PVA-based resin layer rigidity sufficient to withstand the tension applied during stretching and water resistance sufficient to prevent dissolution in water. Specifically, boric acid generates tetrahydroxyborate anions in the aqueous solution, which can crosslink with the PVA-based resin through hydrogen bonding. As a result, the PVA-based resin layer is imparted with rigidity and water resistance, allowing for satisfactory stretching, and an absorptive polarizing film with excellent optical properties can be produced.

[0055] The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or a borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 7 parts by weight, and even more preferably 3 to 6 parts by weight, per 100 parts by weight of water. By adjusting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, allowing for the production of an absorptive polarizing film with even higher performance. In addition to boric acid or a borate, aqueous solutions obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

[0056] Preferably, an iodide is added to the stretching bath (boric acid aqueous solution). By adding an iodide, it is possible to suppress the elution of iodine adsorbed in the PVA-based resin layer. Specific examples of iodides are as described above. The concentration of the iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of water.

[0057] The stretching temperature (liquid temperature of the stretching bath) is preferably 40°C or higher, more preferably 60°C or higher. At such a temperature, good stretching can be achieved. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60°C or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40°C, good stretching may not be achieved, even taking into account the plasticization of the thermoplastic resin substrate by water. On the other hand, the stretching temperature (liquid temperature of the stretching bath) is preferably 85°C or lower, more preferably 75°C or lower. The higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, which may result in poor optical properties. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

[0058] In one embodiment, the stretching ratio in underwater stretching is preferably 1.5 times or more, more preferably 2.0 times or more, and may be 2.5 times or more, or even 3.0 times or more. The total stretching ratio of the laminate is, for example, more than 4.5 times, preferably 5.0 times or more, and may be 5.5 times or more, relative to the original length of the laminate. By achieving such a high stretching ratio, an absorptive polarizing film with excellent optical properties can be produced. Such a high stretching ratio can be achieved by employing an underwater stretching method (stretching in boric acid water).

[0059] The drying shrinkage treatment may be performed by zone heating, which heats the entire zone, or by heating the transport rolls (using so-called heated rolls). Preferably, both methods are used. Drying using heated rolls efficiently suppresses heat curling of the laminate, resulting in the production of an absorptive polarizing film with excellent appearance. Specifically, drying the laminate while it is aligned with heated rolls efficiently promotes crystallization of the thermoplastic resin substrate, thereby increasing the crystallinity. Even at relatively low drying temperatures, the crystallinity of the thermoplastic resin substrate can be favorably increased. As a result, the rigidity of the thermoplastic resin substrate increases, enabling it to withstand shrinkage of the PVA-based resin layer due to drying, thereby suppressing curling. Furthermore, using heated rolls allows the laminate to be dried while maintaining a flat state, thereby suppressing not only curling but also wrinkling. In this case, the optical properties of the laminate can be improved by shrinking it in the width direction through the drying shrinkage treatment. This is because the orientation of the PVA and the PVA / iodine complex can be effectively enhanced. The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using a heated roll, the laminate can be continuously shrunk in the width direction while being transported, thereby achieving high productivity.

[0060] For example, drying conditions can be controlled by adjusting the heating temperature of the transport rolls (temperature of the heating rolls), the number of heating rolls, the contact time with the heating rolls, etc. The temperature of the heating rolls is preferably 60°C to 120°C, more preferably 65°C to 100°C, and even more preferably 70°C to 80°C. This effectively increases the crystallinity of the thermoplastic resin, effectively suppressing curling and imparting excellent strength to the laminate. The temperature of the heating rolls can be measured using a contact thermometer. Typically, 2 to 40 transport rolls, preferably 4 to 30 rolls, are used. The contact time between the laminate and the heating rolls (total contact time) is preferably 1 to 300 seconds, more preferably 1 to 20 seconds, and even more preferably 1 to 10 seconds.

[0061] The heating rolls may be installed in a heating furnace (e.g., an oven) or in a normal production line (under room temperature). Preferably, they are installed in a heating furnace equipped with a blower. By using both heating roll drying and hot air drying, it is possible to suppress abrupt temperature changes between the heating rolls, and to easily control shrinkage in the width direction. The hot air drying temperature is preferably 30°C to 100°C. The hot air drying time is preferably 1 second to 300 seconds. The hot air speed is preferably about 10 m / s to 30 m / s. Note that this air speed is the air speed inside the heating furnace and can be measured using a mini-vane type digital anemometer.

[0062] Preferably, after the underwater stretching treatment and before the drying shrinkage treatment, a washing treatment is carried out by, for example, immersing the PVA-based resin layer in an aqueous potassium iodide solution.

[0063] <Protective Layer> The protective layer that can be included in the absorptive polarizing element can be composed of any appropriate film. Examples of materials that form the main component of the film constituting the protective layer 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, and cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. Among these, (meth)acrylic resins and cycloolefin-based resins are preferably used. By using these resins, a protective layer with excellent smoothness can be formed by extrusion molding, and an absorptive polarizing element with excellent smoothness can be obtained. Furthermore, a protective layer composed of a cycloolefin-based resin can have excellent durability of birefringence properties (e.g., little change over time).

[0064] The thickness of the protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm. The surface smoothness of the protective layer is preferably 0.7 arcmin or less, more preferably 0.6 arcmin or less, and even more preferably 0.5 arcmin or less. The surface smoothness can be measured by focusing irradiated light on the surface of the object.

[0065] <Adhesive Layer> The adhesive layer 51 that may be included in the absorptive polarizing member 28 may be formed of any appropriate adhesive. Examples of the adhesive that may be used include a water-based adhesive, a solvent-based adhesive, a hot-melt adhesive, and a curable adhesive (for example, an active energy ray-curable adhesive).

[0066] The thickness of the adhesive layer that may be included in the absorptive polarizing element is, for example, 3 μm or less, preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm or less. With such a thickness, an absorptive polarizing element with excellent smoothness can be obtained. The thickness of the adhesive layer that may be included in the absorptive polarizing element is, from the viewpoint of adhesiveness, for example, 0.01 μm or more, preferably 0.5 μm or more.

[0067] <Laminate Film> The laminate film typically includes a substrate. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm. The surface smoothness of the substrate is preferably 0.7 arcmin or less, more preferably 0.6 arcmin or less, and even more preferably 0.5 arcmin or less.

[0068] The substrate may be composed of any suitable film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. Here, (meth)acrylic refers to acrylic and / or methacrylic. In one embodiment, the substrate is preferably composed of a (meth)acrylic resin. By using a (meth)acrylic resin, a substrate with excellent smoothness (e.g., satisfying the above-mentioned surface smoothness) can be formed by extrusion molding. Thus, a laminated film with excellent smoothness can be obtained.

[0069] As described above, a laminate film typically has a substrate and a surface treatment layer formed on the substrate. The thickness of the laminate film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and even more preferably 20 μm to 45 μm. The thickness of the surface treatment layer is, for example, 0.5 μm to 10 μm.

[0070] As described above, the surface treatment layer includes a hard coat layer. The hard coat layer is typically formed by applying a hard coat layer-forming material to a substrate and curing the applied layer. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. Examples of the curable compound's curing mechanism include heat curing and photocuring. Examples of the curable compound include monomers, oligomers, and prepolymers. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of the polyfunctional monomer or oligomer include a monomer or oligomer having two or more (meth)acryloyl groups, a urethane (meth)acrylate or a urethane (meth)acrylate oligomer, an epoxy-based monomer or oligomer, and a silicone-based monomer or oligomer.

[0071] The surface treatment layer may include a functional layer in addition to the hard coat layer. The functional layer preferably functions as an antireflection layer. In a preferred embodiment, the surface treatment layer includes the hard coat layer and the antireflection layer in this order from the substrate side. The thickness of the functional layer is preferably 0.05 μm to 10 μm, more preferably 0.1 μm to 5 μm, and even more preferably 0.1 μm to 2 μm.

[0072] The laminate film 31 having the surface treatment layer 31b may be located on the outermost side of the optical laminate 1. The surface treatment layer may have any appropriate function. For example, the surface treatment layer preferably has an anti-reflection function from the viewpoint of suppressing light loss at the interface with air and improving visibility.

[0073] <Retardation Member> The retardation member is formed of any appropriate material that can satisfy desired optical properties. The retardation member (e.g., λ / 4 member) may be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound.

[0074] 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 retardation 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.

[0075] 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 resins suitable for use in phase difference members and methods for forming phase difference members are described in, for example, 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.

[0076] The thickness of the retardation 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.

[0077] 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 a retardation member, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the retardation 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] The thickness of the retardation 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.

[0083] <Adhesive Layer> The thickness of the adhesive layer used to laminate the above-mentioned components can be set to any appropriate thickness. The thickness of each adhesive layer used to laminate the above-mentioned components is, for example, 15 μm or less, preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. Such a thickness can provide excellent smoothness. On the other hand, the thickness of each adhesive layer used to laminate the above-mentioned components is preferably 3 μm or more. For example, the thickness of the adhesive layer disposed between the laminate film 31 and the absorbing polarizing member 28 is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. Specifically, the laminate film 31 and the retardation member 30 can be laminated via an adhesive layer having a thickness of preferably 12 μm or less. Furthermore, the thickness of the adhesive layer disposed between the absorbing polarizing member 28 and the retardation member 30 is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less.

[0084] The pressure-sensitive adhesive layer may be composed of any appropriate pressure-sensitive adhesive. Specific examples of the pressure-sensitive adhesive layer include pressure-sensitive adhesives whose base polymer is an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, or the like. By adjusting the type, number, combination, and compounding ratio of the monomers constituting the base polymer of the pressure-sensitive adhesive, as well as the compounding amount of the crosslinking agent, the reaction temperature, the reaction time, and the like, a pressure-sensitive adhesive having desired properties according to the purpose can be prepared. The base polymer of the pressure-sensitive adhesive may be used alone or in combination of two or more types. An acrylic polymer is preferably used as the base polymer. Specifically, the pressure-sensitive adhesive layer is preferably composed of an acrylic pressure-sensitive adhesive.

[0085] Any other appropriate optical member may be laminated on the absorptive polarizing member 28 of the optical laminate 1. The optical laminate 1 can be used in any appropriate display. For example, the optical laminate 1 can be suitably used in VR goggles.

[0086] [Display System] Figure 2 is a schematic diagram showing the general configuration of an example of a display system for VR goggles, and schematically illustrates the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing element 14, a first lens unit 16, a half mirror 18, a first λ / 4 element 20, a second λ / 4 element 22, and a second lens unit 24. The reflective polarizing element 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 element 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first λ / 4 element 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 element 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing element 14.

[0087] The half mirror or the components arranged forward from the first lens unit (in the illustrated example, the half mirror 18, first lens unit 16, second λ / 4 member 22, reflective polarizing member 14, and second lens unit 24) may be collectively referred to as the lens unit (lens unit 4).

[0088] 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 that may be included in the display element 12, and is converted into first linearly polarized light.

[0089] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into the first circularly polarized light. The first λ / 4 member 20 may be provided integrally with the display element 12.

[0090] 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.

[0091] The second λ / 4 member 22 can transmit the light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. The second λ / 4 member 22 may be provided integrally with the first lens portion 16.

[0092] The first circularly polarized light output from the first λ / 4 member 20 passes through the half mirror 18 and the first lens portion 16, and is converted into the second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light output from the second λ / 4 member 22 is reflected toward the half mirror 18 without passing through the reflective polarizing member 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member 14 is the same as the reflection axis of the reflective polarizing member 14. Therefore, the second linearly polarized light incident on the reflective polarizing member 14 is reflected by the reflective polarizing member 14.

[0093] 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 22, and the second circularly polarized light emitted from the second λ / 4 element 22 passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into third linearly polarized light by the second λ / 4 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 direction 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.

[0094] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 and enters the user's eye 26 .

[0095] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be disposed approximately parallel to each other or approximately perpendicular to each other. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first λ / 4 member 20 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second λ / 4 member 22 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0096] The in-plane retardation Re(550) of the first λ / 4 member 20 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 member 20 preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 member 20 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0097] The in-plane retardation Re(550) of the second λ / 4 member 22 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 member 22 preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 member 22 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0098] In the display system 10, a space may be formed between the first lens portion 16 and the second lens portion 24. In this case, it is preferable that the member disposed between the first lens portion 16 and the second lens portion 24 is integrally formed with either the first lens portion 16 or the second lens portion 24. For example, the member disposed between the first lens portion 16 and the second lens portion 24 is integrated with either the first lens portion 16 or the second lens portion 24 via an adhesive layer. This configuration may provide, for example, excellent ease of handling of each member. The adhesive layer may be formed of an adhesive or a pressure-sensitive adhesive. Specifically, the adhesive layer may be an adhesive layer or a pressure-sensitive adhesive layer. The thickness of the adhesive layer is, for example, 0.01 μm to 60 μm.

[0099] The optical laminate according to an embodiment of the present invention may include, for example, components included in the display system. The optical laminate may include other components, such as an adhesive layer, for integrating adjacent components. The thickness of the optical laminate varies depending on the type and number of components included, but is, for example, 50 μm to 400 μm. The optical laminate may be integrated with, for example, the first lens portion 16 or the second lens portion 24. Typically, the optical laminate may be bonded to the first lens portion 16 or the second lens portion 24, which is the adherend, via an adhesive layer. The optical laminate may be heated during bonding (e.g., before bonding to the adherend). For example, when the adherend surface is curved, such as the first lens portion 16 shown in FIG. 2, it is preferable to heat the optical laminate. Heating makes the optical laminate more deformable, allowing the optical laminate to be bonded to the curved surface without leaving any gaps. The heating temperature of the optical laminate is, for example, 50°C or higher and 150°C or lower.

[0100] FIG. 3 is a schematic cross-sectional view showing an example of a state in which another optical element is laminated on the absorptive polarizing element of the optical laminate shown in FIG. The optical laminate 2 includes an absorptive polarizing element 28 that can be disposed between the reflective polarizing element 14 and the second lens portion 24, a third λ / 4 element 30 corresponding to the retardation element, and a laminate film 31. The in-plane retardation Re(550) of the third λ / 4 element 30 is, for example, 100 nm to 190 nm, may be 110 nm to 180 nm, may be 130 nm to 160 nm, or may be 135 nm to 155 nm. The third λ / 4 element 30 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 element is, for example, 0.75 or more but less than 1, or may be 0.8 or more and 0.95 or less.

[0101] The refractive index characteristics of the λ / 4 member preferably exhibit the relationship nx>ny≧nz. Here, "ny=nz" includes not only the case where ny and nz are completely equal, but also 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 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.

[0102] The optical laminate 2 includes a reflective polarizing element 14. The reflective polarizing element 14 is laminated behind the absorbing polarizing element 28 via an adhesive layer 43. In FIG. 3 , the reflective polarizing element 14 is laminated below the absorbing polarizing element 28. The reflection axis of the reflective polarizing element 14 and the absorption axis of the absorbing polarizing element 28 (absorbing polarizing film 28 a) can be arranged substantially parallel to each other, and the transmission axis of the reflective polarizing element 14 and the transmission axis of the absorbing polarizing element 28 (absorbing polarizing film 28 a) can be arranged substantially parallel to each other. In the optical laminate 2, the absorbing polarizing element 28 is used, for example, from the perspective of improving visibility. Furthermore, by providing a third λ / 4 element (phase difference element) 30 in the optical laminate 2, it is possible to prevent, for example, reflection of external light from the second lens portion 24 side.

[0103] The peel strength of the absorptive polarizing member 28 from the pressure-sensitive adhesive layer 43 is preferably 2 N / 25 mm or more and 10 N / 25 mm or less, and more preferably 4 N / 25 mm or more. By satisfying such a peel strength, peeling between the members included in the optical laminate can be effectively suppressed.

[0104] 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.

[0105] FIG. 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure 14a has alternating birefringent layers A and substantially non-birefringent layers B. The total number of layers constituting the multilayer structure may be 50 to 1,000. For example, the refractive index nx in the x-axis direction of layer A is greater than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of layer B and the refractive index ny in the y-axis direction are substantially the same. The refractive index difference between layer A and layer B is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction can be the reflection axis, and the y-axis direction can be the transmission axis. The refractive index difference between layer A and layer B in the x-axis direction is preferably 0.2 to 0.3.

[0106] The A layer is typically made of a material that exhibits birefringence upon stretching. Examples of such materials include naphthalenedicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (e.g., polymethyl methacrylate). The B layer is typically made of a material that does not substantially exhibit birefringence upon stretching. Examples of such materials include copolyesters of naphthalenedicarboxylic acid and terephthalic acid. The multilayer structure can be formed by a combination of coextrusion and stretching. For example, the materials constituting the A layer and the B layer are extruded and then multilayered (e.g., using a multiplier). The resulting multilayer laminate is then stretched. The x-axis direction in the illustrated example may correspond to the stretching direction.

[0107] Commercially available reflective polarizing films include, for example, "DBEF" and "APF" manufactured by 3M, and "APCF" manufactured by Nitto Denko Corporation.

[0108] The crossed transmittance (Tc) of the reflective polarizing element (reflective polarizing film) can be, for example, 0.001% to 3%. The single transmittance (Ts) of the reflective polarizing element (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing element (reflective polarizing film) can be, for example, 92% to 99.99%.

[0109] 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

[0110] The shrinkage force S (unit: N) of the reflective polarizing member (reflective polarizing film) at 120° C. can be, for example, 0.1 N to 10 N.

[0111] The optical laminate 2 includes a second λ / 4 member 22. The second λ / 4 member 22 is laminated on the reflective polarizing member 14 via a pressure-sensitive adhesive layer 44.

[0112] The second λ / 4 member 22 is formed of any appropriate material that can satisfy the above characteristics. The second λ / 4 member 22 can be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound. The same explanation as for the above-mentioned retardation member (λ / 4 member) can be applied to the second λ / 4 member 22 that is formed of a stretched resin film or an oriented and solidified layer of a liquid crystal compound. The second λ / 4 member and the third λ / 4 member may be members with the same configuration (e.g., forming material, thickness, optical properties, etc.) or may be members with different configurations.

[0113] In addition to the second λ / 4 member 22, the optical laminate 2 includes another phase difference member 23 whose refractive index characteristics satisfy the relationship nz > nx ≧ ny. By using the member 23 satisfying the relationship nz > nx ≧ ny, light leakage (for example, light leakage in an oblique direction) can be prevented. As shown in FIG. 3 , the second λ / 4 member 22 is preferably positioned forward of the member 23 satisfying the relationship nz > nx ≧ ny. The member 23 satisfying the relationship nz > nx ≧ ny is laminated to the second λ / 4 member 22 via an adhesive layer 52.

[0114] The thickness direction retardation Rth(550) of the member having the refractive index characteristics of nz > nx ≥ ny is preferably -260 nm to -10 nm, more preferably -230 nm to -15 nm, and even more preferably -215 nm to -20 nm. In one embodiment, the other retardation member 23 is a so-called positive C plate whose refractive index exhibits the relationship nx = ny. 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. For example, it also encompasses the case where Re(550) is less than 10 nm. In another embodiment, the other retardation member 23 has a refractive index exhibiting the relationship nx > ny. In this case, the in-plane retardation Re(550) of the other retardation member 23 is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm.

[0115] The member having refractive index characteristics satisfying the relationship nz > nx ≥ ny can be formed from any appropriate material. Preferably, it is 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 the film include the liquid crystal compounds and formation methods described in paragraphs

[0020] to

[0042] of JP 2002-333642 A. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 4 μm.

[0116] As another preferred example, the member having refractive index characteristics satisfying the relationship nz > nx ≥ ny may be a retardation film formed from a fumaric acid diester resin as described in JP 2012-32784 A. In this case, the thickness is preferably 5 μm to 50 μm, and more preferably 10 μm to 35 μm.

[0117] The optical laminate 2 has, for example, a pressure-sensitive adhesive layer 45 for bonding to an adherend (e.g., the first lens portion 16). A release liner (not shown) can be bonded to the surface of the pressure-sensitive adhesive layer 45. For example, the pressure-sensitive adhesive layer 45 can be protected by the release liner.

[0118] The present invention will be described in detail below using examples, but the present invention is not limited to these examples. The thickness, shrinkage force, modulus of elasticity, peel force, retardation value, and surface smoothness were measured using the following measurement methods. Unless otherwise specified, "parts" and "%" are based on weight. <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"). <Shrinkage Force> The measurement object was punched using a blade die measuring 100 mm (length) x 25 mm (width) to obtain a rectangular measurement sample. The punching was performed so that the length direction was aligned with the absorption axis direction or reflection axis direction of the measurement object. In an autograph equipped with a thermostatic bath (Shimadzu Corporation's "AG-Xplus"), the obtained measurement sample was chucked with a jig within a range of 5 mm from each end in the longitudinal direction without being pulled, and placed in an environment at a temperature of 120°C, and the contraction force (N) generated between the jig over time was measured. <Elastic modulus> The elastic modulus was measured by the nanoindentation method. Specifically, the laminated film was cut into a size of 20 mm length x 20 mm width using a cutting machine to obtain a test specimen. The cut surface of the obtained test specimen was cut using a microtome, and after placing it in an environment of 23°C and 55% RH for 3 hours (humidification), it was measured using a nanoindenter. For nanoindenter measurements, a "Triboindenter" manufactured by Hysitron Inc. was used, and a Berkovich (triangular pyramid) indenter was used. Under the following conditions, the hard coat layer of the laminated film was indented from the cut surface to measure the load-displacement curve, and the elastic modulus (GPa) was calculated. (Measurement conditions) Measurement method: Single indentation measurement Measurement temperature: Room temperature and 120°C Indentation speed: 10 nm / sec Indentation depth: 100 nm <Peel force> A sample cut to a size of 25 mm wide and 50 mm long from the measurement object was left in an environment of 23°C and 50% RH for 30 minutes or more, and then the peel force (N / 25 mm) was measured using a universal tensile tester when peeled in the longitudinal direction at a peel speed of 300 mm / min and a peel angle of 180°. The measurement was performed in an environment of 23°C and 50% RH.<Retardation Value> The retardation value at each wavelength at 23°C was measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"). <Surface Smoothness> The surface smoothness was measured using a scanning white light interferometer (manufactured by Zygo, product name "NewView9000"). Specifically, the measurement sample was placed on a measurement table with a vibration-isolating table, interference fringes were generated using a single white LED light, and an interference objective lens (1.4x magnification) with a reference plane was scanned in the Z direction (thickness direction) to selectively obtain the smoothness (surface smoothness) of the outermost surface of the measurement object within a 12.4 mm square field of view. When the measurement object was an adhesive layer, the adhesive layer was attached to a microslide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200200"), and the smoothness of the exposed adhesive surface was measured. When the object to be measured was a film, a 5 μm thick acrylic pressure-sensitive adhesive layer with minimal unevenness was formed on the glass, and the film to be measured was laminated onto the adhesive surface so as to prevent the inclusion of foreign matter, air bubbles, or deformation lines, and the smoothness of the surface opposite to the pressure-sensitive adhesive layer was measured. The surface smoothness of the 5 μm thick acrylic pressure-sensitive adhesive layer with minimal unevenness was 0.30 arcmin. For analysis, the value obtained by doubling the angle index "Slope magnitude RMS" (equivalent to 2σ) was defined as the surface smoothness (unit: arcmin).

[0119] [Production Example 1-1] (Formation of Absorptive Polarizing Film) A long, amorphous, isophthalic acid-copolymerized polyethylene terephthalate film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of approximately 75°C was used as the thermoplastic resin substrate. One side of the resin substrate was subjected to a corona treatment. A PVA-based resin (a 9:1 mixture of polyvinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, trade name "GOHSENEX Z410") was prepared by mixing 100 parts by weight of the resin with 13 parts by weight of potassium iodide, and the resulting solution was dissolved in water to prepare an aqueous PVA solution (coating solution). The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a 13 μm-thick PVA-based resin layer, producing a laminate. The resulting laminate was free-end uniaxially stretched 2.4 times in the longitudinal direction (machine direction) between rolls with different peripheral speeds in an oven at 130°C (in-air auxiliary stretching treatment). The laminate was then immersed in an insolubilizing bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment). The laminate was then immersed in a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the final polarizing film had a single transmittance (Ts) of 43.0% (dyeing treatment). The laminate was then immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls operating at different peripheral speeds to a total stretch ratio of 5.5 (stretch ratio by underwater stretching: 2.3) (underwater stretching treatment). The laminate was then immersed in a cleaning bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (washing treatment). The laminate was then dried in an oven maintained at 90°C and brought into contact with a SUS heated roll maintained at a surface temperature of 75°C for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.In this manner, an absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 6.5 N was formed on the resin substrate.

[0120] [Production Example 1-2] (Formation of Absorptive Polarizing Film) An absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 7.4 N was formed in the same manner as in Production Example 1-1, except that the liquid temperature in the underwater stretching treatment was changed to 68° C. and the film was stretched in the underwater stretching treatment so that the total stretch ratio became 5.3 times (the stretch ratio by underwater stretching was 2.2 times).

[0121] [Production Example 1-3] (Formation of Absorptive Polarizing Film) An absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 8.3 N was formed in the same manner as in Production Example 1-1, except that the liquid temperature in the underwater stretching treatment was changed to 68°C.

[0122] [Production Example 1-4] (Formation of Absorptive Polarizing Film) An absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 10.0 N was formed in the same manner as in Production Example 1-1, except that the liquid temperature in the underwater stretching treatment was changed to 65° C. and the film was stretched in the underwater stretching treatment so that the total stretch ratio became 5.0 times (the stretch ratio by underwater stretching was 2.1 times).

[0123] [Production Example 1-5] (Formation of Absorptive Polarizing Film) An absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 11.5 N was formed in the same manner as in Production Example 1-1, except that the liquid temperature in the underwater stretching treatment was changed to 62° C. and the film was stretched in the underwater stretching treatment so that the total stretch ratio became 5.0 times (the stretch ratio by underwater stretching was 2.1 times).

[0124] [Production Example 2-1] (Preparation of Laminated Film) The following hard coat layer-forming material 1 was applied to an acrylic film (thickness: 40 μm, surface smoothness: 0.45 arcmin) having a lactone ring structure, 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 ２The coating layer was cured by irradiating it with ultraviolet light of 1000 W at 120°C, forming a hard coat layer with a thickness of 4 μm and an elastic modulus of 2.4 GPa at 120°C and 5.8 GPa at room temperature. Next, the antireflection layer-forming coating solution A described below was applied onto the hard coat layer with a wire bar, and the applied coating solution was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet light of 300 mJ / cm2 with an integrated light amount of 300 mJ / cm2 from a high-pressure mercury lamp. ２ The coating film was cured by irradiating it with ultraviolet light of 1000 kJ / cm to form an antireflection layer A having a thickness of 140 nm. Subsequently, the following coating solution B for forming an antireflection layer was applied onto the antireflection layer A using a wire bar, and the applied coating solution was heated at 80°C for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet light of 1000 kJ / cm to form an antireflection layer A having a thickness of 140 nm. ２ The coating film was cured by irradiation with ultraviolet light of 1000 .ANG. to form an antireflection layer B having a thickness of 105 nm. In this way, a laminated film (thickness: 44 .mu.m) was obtained.

[0125] (Hard Coat Layer-Forming Material 1) 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 hard coat layer-forming material 1.

[0126] (Anti-reflection layer-forming coating solution A) 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. This mixture was diluted with butyl acetate as a dilution solvent to a solid content of 12 wt%, and the mixture was stirred to prepare anti-reflection layer-forming coating solution A.

[0127] (Anti-Reflection Layer-Forming Coating Solution B) 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% by weight), 150 parts by weight of hollow nanosilica particles (manufactured by JGC Catalysts and Chemicals Industries, Ltd., trade name "Surulia 5320", solid content 20% by weight, weight average particle diameter 75 nm), 50 parts by weight of solid nanosilica particles (manufactured by Nissan Chemical Industries, Ltd., trade name "MEK-2140Z-AC", solid content 30% by weight, weight average particle diameter 10 nm), 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", solid content 20% by weight), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100% by weight) were mixed. To this 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 coating solution B for forming an anti-reflection layer.

[0128] [Production Example 2-2] (Production of Laminated Film) A laminated film was produced in the same manner as in Production Example 2-1, except that a hard coat layer having a thickness of 4 μm and an elastic modulus of 1.2 GPa at 120° C. and an elastic modulus of 5.6 GPa at room temperature was formed using the following hard coat layer-forming material 2.

[0129] (Hard Coat Layer-Forming Material 2) 40 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 40 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 hard coat layer-forming material 2.

[0130] [Production Example 2-3] (Production of Laminated Film) A laminated film was produced in the same manner as in Production Example 2-1, except that a hard coat layer having a thickness of 6 μm, an elastic modulus of 0.6 GPa at 120° C., and an elastic modulus of 5.4 GPa at room temperature was formed using the following hard coat layer-forming material 3.

[0131] (Hard Coat Layer-Forming Material 3) 30 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 50 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 hard coat layer-forming material 3.

[0132] [Production Example 2-4] (Production of Laminated Film) A laminated film was produced in the same manner as in Production Example 2-1, except that a hard coat layer having a thickness of 6 μm and an elastic modulus of 0.3 GPa at 120° C. and an elastic modulus of 5.2 GPa at room temperature was formed using the following hard coat layer-forming material 4.

[0133] (Hard Coat Layer-Forming Material 4) 20 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 60 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 hard coat layer-forming material 4.

[0134] [Production Example 3] (Preparation of λ / 4 Member) 55 parts of a compound represented by formula (I), 25 parts of a compound represented by formula (II), and 20 parts of a compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN), heated to 60°C, and stirred to dissolve. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 parts of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added, followed by further stirring to obtain a solution. The solution was transparent and homogeneous. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. The polyimide solution for alignment film was applied to a 0.7 mm thick glass substrate using a spin coating method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The resulting coating film was subjected to a rubbing treatment using a commercially available rubbing device to form an alignment film. The polymerizable composition obtained above was applied to an alignment film (substrate) by spin coating and dried for 2 minutes at 100° C. After the obtained coating film was cooled to room temperature, it was irradiated with 30 mW / cm using a high-pressure mercury lamp. ２ The film was irradiated with ultraviolet light at an intensity of 1000 nm for 30 seconds to obtain a 3 μm thick liquid crystal alignment solidified layer. The obtained liquid crystal alignment solidified layer had an in-plane retardation Re(550) of 140 nm, an Re(450) / Re(550) ratio of 0.851, and exhibited reverse dispersion wavelength characteristics.

[0135]

[0136] [Production Example 4] (Formation of a Positive C Plate) A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (1) (the numbers 65 and 35 in the formula indicate the mole percent of the monomer unit, and are conveniently expressed as a block polymer; weight-average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a PET substrate that had been subjected to a vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet light to harden the liquid crystal layer, forming a positive C plate with a thickness of 4 μm and an Rth(550) of −100 nm on the substrate.

[0137] [Production Example 5] (Formation of Pressure-Sensitive Adhesive Layer) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 92 parts by weight of butyl acrylate, 2.9 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, and 5 parts by weight of N-acryloylmorpholine. Furthermore, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator and 200 parts by weight of ethyl acetate were charged to 100 parts by weight of this monomer mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere in the flask with nitrogen, and the liquid temperature in the flask was maintained at around 55°C for 8 hours to carry out a polymerization reaction, thereby preparing an acrylic polymer solution having a weight-average molecular weight (Mw) of 1,780,000. The acrylic polymer solution was applied to a substrate film, and the resulting coating on the substrate film was dried in an oven to form a pressure-sensitive adhesive layer having a thickness of 5 μm and a surface smoothness of 0.30 arcmin.

[0138] [Production Example 6] (Preparation of optical laminate) An acrylic film having a thickness of 20 μm and a surface smoothness of 0.10 arcmin and having a lactone ring structure was bonded to the absorptive polarizing film of Production Example 1 above using an ultraviolet-curable adhesive (thickness after curing: 0.7 μm), to obtain an absorptive polarizing member.

[0139] The resin substrate was peeled from the absorptive polarizing member, and the λ / 4 member of Production Example 3 was attached to the absorptive polarizing film via the pressure-sensitive adhesive layer of Production Example 5, so that the absorption axis of the absorptive polarizing film and the slow axis of the λ / 4 member formed an angle of 45°. Next, the laminate film of Production Example 2 (an acrylic film on which a hard coat layer and an antireflection layer were formed) was attached to the λ / 4 member via the pressure-sensitive adhesive layer of Production Example 5. The acrylic film of the laminate film was attached so that it faced the λ / 4 member.

[0140] A reflective polarizing film ("APCF" manufactured by Nitto Denko Corporation, contraction force 8N) was bonded to the acrylic film of the absorptive polarizing element via a 9 μm-thick adhesive layer. The reflective axis of the reflective polarizing film and the absorption axis of the absorptive polarizing film were aligned parallel to each other. The λ / 4 element of Production Example 3 and the positive C plate of Production Example 4 were then bonded to the reflective polarizing film in this order via the adhesive layer of Production Example 5. The reflective axis of the reflective polarizing film (the absorption axis of the absorptive polarizing film) and the slow axis of the λ / 4 element were bonded at an angle of 45°. The λ / 4 element and the positive C plate were bonded together using an ultraviolet-curable adhesive (thickness 1 μm after curing). A 50 μm-thick adhesive layer was then provided on the positive C plate to obtain an optical laminate.

[0141] In the above Production Example 6, the reliability of the optical laminate obtained by combining the absorptive polarizing films obtained in Production Examples 1-1 to 1-5 and the laminate films obtained in Production Examples 2-1 to 2-4 was evaluated by the following method. The evaluation results are shown in Table 1. The reliability evaluation results were also evaluated using the shrinkage force S (unit: N) of the absorptive polarizing film at 120°C and the elastic modulus Er of the hard coat layer at 120°C. １２０ (unit: GPa) and thickness T (unit: μm) １２０The relationship between the coefficient of friction coefficient and T (GPa μm) is shown in FIG. 5. In FIG. 5, good evaluation results are plotted with white circles, and bad evaluation results are plotted with black circles. <Evaluation of Reliability> The obtained optical laminate was bonded to a flat-surfaced alkali-free glass plate, and then placed in an environment at a temperature of -40°C for 30 minutes using a thermal shock device (manufactured by Espec Corporation, "TSA-303EL-W"), and then placed in an environment at a temperature of 85°C for 30 minutes. This operation was repeated a total of 100 times to perform a heat cycle test, and then it was confirmed using a differential interference microscope whether peeling had occurred in the optical laminate. In the heat cycle test, the time required for temperature increase and decrease was set to 6 minutes or less. (Evaluation Criteria) Good: No peeling occurred in the optical laminate, or peeling occurred in a region less than 100 μm from the end face of the optical laminate. Poor: Peeling occurred in the optical laminate up to a region 100 μm or more from the end face.

[0142]

[0143] In the reliability evaluation, peeling was observed mainly between the absorptive polarizing element and the reflective polarizing element (reflective polarizing film). Specifically, peeling was observed at the interface between the acrylic film of the absorptive polarizing element and the adhesive layer. Here, the peel force of the acrylic film to the adhesive layer was 2.9 N / 25 mm. Note that both the absorptive polarizing element and the reflective polarizing element (reflective polarizing film) were obtained through a stretching process.

[0144] 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.

[0145] The optical laminate according to the embodiment of the present invention can be used in a display such as VR goggles, for example.

[0146] REFERENCE SIGNS LIST 1 Optical laminate, 2 Optical laminate, 4 Lens portion, 10 Display system, 12 Display element, 12a Display surface, 14 Reflective polarizing member, 14a Multilayer structure, 16 First lens portion, 18 Half mirror, 20 First λ / 4 member, 22 Second λ / 4 member, 24 Second lens portion, 28 Absorptive polarizing member, 28a Absorptive polarizing film, 28b Protective layer, 30 Retardation member, 31 Laminated film (protective member), 31a Substrate, 31b Surface treatment layer (hard coat layer), 41 Pressure-sensitive adhesive layer, 42 Pressure-sensitive adhesive layer, 43 Pressure-sensitive adhesive layer, 44 Pressure-sensitive adhesive layer, 45 Pressure-sensitive adhesive layer, 51 Adhesive layer, 52 Adhesive layer.

Claims

1. A laminated film having a substrate and a hard coat layer, and an absorptive polarizing member including an absorptive polarizing film, wherein the contraction force S (unit: N) of the absorptive polarizing film at 120° C. and the elastic modulus Er of the hard coat layer at 120° C. are １２０ (unit: GPa) and thickness T (unit: μm) Er １２０ T (GPa μm) is Er １２０ An optical laminate that satisfies the relationship T>0.85×S−4.

02.

2. The optical laminate according to claim 1, comprising the laminate film, the absorptive polarizing element, and another optical element in this order, the absorptive polarizing element and the other optical element being laminated via an adhesive layer.

3. The optical laminate according to claim 2, wherein the other optical component is a reflective polarizing component.

4. The optical laminate according to claim 2, wherein the peel strength of the absorptive polarizing member relative to the pressure-sensitive adhesive layer is 2 N / 25 mm or more.

5. The optical laminate according to claim 1, further comprising a phase difference member disposed between the laminate film and the absorptive polarizing member.

6. The optical laminate according to claim 1, wherein the absorptive polarizing member includes a protective layer.

7. The optical laminate according to claim 1, further comprising an adhesive layer disposed between the laminate film and the absorptive polarizing member, the adhesive layer having a thickness of 12 μm or less.

8. The optical laminate according to claim 1, wherein the hard coat layer has an elastic modulus Er of 5 GPa or more at room temperature.

9. The elastic modulus Er of the hard coat layer at 120° C. relative to the elastic modulus Er of the hard coat layer at room temperature. １２０ The ratio of Er １２０ The optical laminate according to claim 1 , wherein / Er is 0.25 or more.

10. A lens unit used in a display system that displays an image to a user, comprising: an optical laminate according to claim 3 that reflects light that is emitted forward from a display surface of a display element that displays an image and that has passed through a polarizing element and a first λ / 4 element; a first lens unit that is arranged on an optical path between the display element and the optical laminate; a half mirror that is arranged between the display element and the first lens unit, that transmits light emitted from the display element and reflects light reflected by the reflective polarizing element of the optical laminate toward the reflective polarizing element; and a second λ / 4 element that is arranged on the optical path between the half mirror and the optical laminate.

11. A display method comprising the steps of: passing light representing an image emitted through a polarizing element and a first λ / 4 element through a half mirror and a first lens unit; passing the light that has passed through the half mirror and the first lens unit through a second λ / 4 element; reflecting the light that has passed through the second λ / 4 element toward the half mirror with the optical laminate described in claim 3; and making the light reflected by the reflective polarizing element and the half mirror of the optical laminate transmittance through the reflective polarizing element by the second λ / 4 element.

12. A method for manufacturing a lens portion according to claim 10, comprising heating the optical laminate to integrate the optical laminate with the first lens portion.

Images