Optical laminate body, lens part, and method for displaying

Abstract

To provide an optical laminate body which can attain reduction of weight of a VR goggle while increasing the visibility.SOLUTION: An optical laminate body 1 includes: a laminate film 31 with a base material 31a and a hard coat layer 31b; and an absorption-type polarization member 28 including an absorption-type polarization film 28a. The contractile force S (unit:N) of the absorption-type polarization film 28a at the temperature of 120°C, and the product of the elastic rate Er120 (unit:GPa) and the thickness T (unit: μm) of the hard coat layer 31b at the temperature of 120°C, pEr120 T(GPa μm), satisfy the relation of Er120 T>0.85×S-4.02.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices) have been rapidly spreading. In an image display device, in order to realize image display and improve the performance of image display, generally, optical members such as a retardation member and a polarizing member are used (see, for example, Patent Document 1). These optical members can be pre-integrated and mounted on an image display device as an optical laminate.

[0003] In recent years, new applications of image display devices have been developed. For example, goggles with a display (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized. Since the VR goggles are considered to be used in various scenes, weight reduction, improvement of visibility, etc. are desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The weight reduction of the VR goggles can be achieved, for example, by thinning the lenses used in the VR goggles. On the other hand, development of an optical laminate including the above optical members suitable for a display system using thin lenses is also desired.

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

Means for Solving the Problems

[0007] 1. The optical laminate according to an embodiment of the present invention includes a laminated film having a base material and a hard coat layer, and an absorption type polarizing member including an absorption type polarizing film. The shrinkage force S (unit: N) of the absorption type polarizing film at 120°C, and the elastic modulus Er 120 (unit: GPa), thickness T (unit: μm), and the product Er 120 ·T (GPa·μm) of the hard coat layer at 120°C satisfy the relationship Er 120 ·T > 0.85×S - 4.02. 2. The optical laminate according to 1 above may include the laminated film, the absorption type polarizing member, and another optical member in this order. The absorption type polarizing member and the other optical member may be laminated via an adhesive layer. 3. In the optical laminate according to 2 above, the other optical member may be a reflective polarizing member. 4. In the optical laminate according to 2 or 3 above, the peel strength of the absorption type polarizing member with respect to the adhesive layer may be 2 N / 25 mm or more. 5. The optical laminate according to any one of 1 to 4 above may include a retardation member disposed between the laminated film and the absorption type polarizing member. 6. In the optical laminate according to any one of 1 to 5 above, the absorption type polarizing member may include a protective layer. 7. The optical laminate according to any one of 1 to 6 above may include an adhesive layer disposed between the laminated film and the absorption type polarizing member, and the thickness of the adhesive layer may be 12 μm or less. 8. In the optical laminate according to any one of 1 to 7 above, the elastic modulus Er of the hard coat layer at room temperature may be 5 GPa or more. 9. In the optical laminate according to any one of 1 to 8 above, the ratio Er 120 of the elastic modulus Er of the hard coat layer at 120°C to the elastic modulus Er 120 of the hard coat layer at room temperature may be 0.25 or more.

[0008] 10. The lens unit according to an embodiment of the present invention is a lens unit used in a display system that displays an image for a user, and is emitted forward from a display surface of a display element representing the image, and reflects the light that has passed through a polarizing member and a first λ / 4 member. The optical laminate according to any one of 3 to 9 above, a first lens unit disposed on the optical path between the display element and the optical laminate, and disposed between the display element and the first lens unit, and transmits the light emitted from the display element, and reflects the light reflected by the reflective polarizing member of the optical laminate toward the reflective polarizing member. A half mirror, and a second λ / 4 member disposed on the optical path between the half mirror and the optical laminate. 11. The display method according to an embodiment of the present invention includes a step of passing light representing an image emitted through a polarizing member and a first λ / 4 member through a half mirror and a first lens unit, and passing the light that has passed through the half mirror and the first lens unit. A step of passing through a second λ / 4 member, a step of reflecting the light that has passed through the second λ / 4 member toward the half mirror with the optical laminate according to any one of 3 to 9 above, and the reflective polarizing member of the optical laminate and the light reflected by the half mirror. And a step of making the reflective polarizing member transmissible by the second λ / 4 member. 12. The method for manufacturing a lens unit according to an embodiment of the present invention is the method for manufacturing a lens unit according to 10 above, and includes heating the optical laminate and integrating the optical laminate with the first lens unit.

Effect of the Invention

[0009] According to the optical laminate according to an embodiment of the present invention, while improving visibility, weight reduction of the VR goggles can be satisfactorily achieved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[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. The drawings may be schematically represented in terms of the width, thickness, shape, etc. of each part compared to the embodiments in order to make the explanation clearer, but this is only an example and does not limit the interpretation of the present invention. Also, for the drawings, the same or equivalent elements may be given the same reference numerals, and duplicate explanations may be omitted.

[0012] (Definition of Terms and Symbols) The definitions of the terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction. (2) In-Plane Phase Difference (Re) “Re(λ)” is the in-plane phase difference measured with light of wavelength λ nm at 23 ° C. For example, “Re(550)” is the in-plane phase difference measured with light of wavelength 550 nm at 23 ° C. Re(λ) is obtained by the formula: Re(λ)=(nx - ny)×d when the thickness of the layer (film) is d (nm). (3) Phase Difference in the Thickness Direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

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

[0014] The optical laminate 1 includes an absorption-type polarizing member 28 and a laminated film 31. The absorption-type polarizing member 28 includes at least an absorption-type polarizing film 28a. In the example shown in FIG. 1, the absorption-type polarizing member 28 includes a protective layer 28b in addition to the absorption-type polarizing film 28a. The absorption-type polarizing film 28a and the protective layer 28b are laminated via an adhesive layer 51. Specifically, the absorption-type polarizing member 28 includes the absorption-type polarizing film 28a, the adhesive layer 51, and the protective layer 28b. Different from the example shown in FIG. 1, the protective layer 28b may be provided on the side where the laminated film 31 is disposed with respect to the absorption-type polarizing film 28a. Also, the protective layer 28b may be omitted. In this case, the absorption-type polarizing member 28 may correspond to the absorption-type polarizing film.

[0015] The laminated film 31 has a base material 31a and a surface treatment layer 31b formed on the base material 31a. The surface treatment layer 31b includes at least a hard coat layer. In the optical laminate 1, the laminated film 31 can be disposed such that the surface treatment layer (hard coat layer) 31b is located outside the base material 31a. The laminated film 31 can protect the absorption-type polarizing member 28. Specifically, the laminated film 31 can function as a protective member in the optical laminate 1.

[0016] In the example shown in FIG. 1, a retardation member 30 is provided between the absorption-type polarizing member 28 and the laminated film 31. An adhesive layer (for example, an adhesive layer) may be used for laminating each member. For example, the laminated film 31 and the retardation member 30 are laminated via an adhesive layer 41. The retardation member 30 and the absorption-type polarizing member 28 are laminated via an adhesive layer 42.

[0017] The absorption-type polarizing film 28a included in the absorption-type polarizing member 28 is typically composed of a film containing a dichroic substance such as iodine or an organic dye. The thickness of the absorption-type polarizing film 28a is, for example, 1 μm or more and 20 μm or less, and may be 2 μm or more and 15 μm or less, may be 12 μm or less, may be 10 μm or less, may be 8 μm or less, or may be 6 μm or less. The absorption-type polarizing film with a small thickness can be excellent in smoothness, for example.

[0018] The optical laminate 1 can be heated. For example, it can be heated when mounted on a display body. The absorption-type polarizing film 28a can contract by heating or the like. In this case, the contraction force S of the absorption-type polarizing film 28a at 120°C is, for example, 0.1 N to 20 N, and may 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, still more preferably 2 μm to 8 μm, and particularly preferably 3 μm to 7 μm.

[0020] The elastic modulus Er of the 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 absorption-type polarizing film 28a at 120°C, the elastic modulus Er 120 (unit: GPa) of the hard coat layer 31b at 120°C, and the thickness T (unit: μm) 120 The product Er 120·It is preferable to satisfy the relationship of T > 0.85×S - 4.02. By satisfying such a relationship, the occurrence of peeling between the members included in the optical laminate can be suppressed. Specifically, the occurrence of peeling between the members that may occur when the optical laminate is heated can be suppressed. The optical laminate can be easily deformed in shape by heating and can be integrated with a curved surface portion such as a lens, for example, and the visibility and weight reduction of a VR goggle can be achieved, for example. Therefore, when the optical laminate satisfies the above relationship, it can be well integrated with a curved surface portion such as a lens. The thin lens can typically be a curved lens.

[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. Also, by having such a hard coat layer, the functions of the functional layers described later (for example, the antireflection 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 ratio Er of the elastic modulus Er of the hard coat layer 31b at 120°C to the elastic modulus Er of the hard coat layer 31b at room temperature 120 of 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 (for example, the occurrence of undulations, the reduction of smoothness) due to heating or the like can be suppressed. The ratio Er of the elastic modulus Er of the hard coat layer 31b at 120°C to the elastic modulus Er of the hard coat layer 31b at room temperature 120 of Er 120 / Er is, for example, 0.7 or less.

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

[0024] The separation distance between the hard coat layer 31b and the absorption-type 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] <Absorption-type polarizing film> The absorption-type polarizing member includes an absorption-type polarizing film. The orthogonal transmittance (Tc) of the absorption-type polarizing member (absorption-type 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 absorption-type polarizing member (absorption-type polarizing film) is, for example, 41.0% to 45.0%, preferably 42.0% or more. The degree of polarization (P) of the absorption-type polarizing member (absorption-type polarizing film) is, for example, 99.0% to 99.997%, preferably 99.8% or more.

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

[0027] As a method for manufacturing an absorption type polarizing film composed of a resin film, for example, a polyvinyl alcohol-based resin (PVA-based resin) layer containing a polyvinyl alcohol-based resin and a halide is formed on one side of a long thermoplastic resin substrate to form a laminate, and the laminate is subjected to an air-assisted stretching treatment, a dyeing treatment, a stretching treatment in water, and a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction, in this order. The thickness of the obtained absorption type polarizing film can be controlled, for example, by adjusting the stretching ratio in the stretching treatment in water. The shrinkage force of the obtained absorption type polarizing film can be controlled, for example, by adjusting the stretching ratio and / or the stretching temperature in the stretching treatment in water.

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

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

[0030] From the viewpoint of improving the adhesion between the thermoplastic resin substrate and the PVA-based resin layer, before forming the PVA-based resin layer, the surface of the thermoplastic resin substrate may be treated, such as corona treatment, 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 it is less than 20 μm, for example, it may be difficult to form the PVA-based resin layer. If it exceeds 300 μm, for example, in the underwater stretching process described later, the thermoplastic resin substrate may take a long time to absorb water and may require an excessive load for stretching.

[0032] The water absorption rate of the thermoplastic resin substrate is preferably 0.2% or more, more preferably 0.3% or more. The thermoplastic resin substrate can absorb water, and the water can act as a plasticizer and plasticize. As a result, the stretching stress can be significantly reduced, and high magnification stretching can be achieved. On the other hand, the water absorption rate of the thermoplastic resin substrate is preferably 3.0% or less, more preferably 1.0% or less. By using such a thermoplastic resin substrate, it is possible to prevent problems such as a significant decrease in the dimensional stability of the substrate during production and deterioration of the appearance of the obtained absorption type polarizing film. In addition, it is possible to prevent the substrate from breaking or the PVA-based resin layer from peeling off from the substrate during underwater stretching. The water absorption rate of the thermoplastic resin substrate can be adjusted, for example, by introducing a modified group into the constituent material. The water absorption rate is a value determined according to 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, while suppressing the crystallization of the PVA-based resin layer, the stretchability of the laminate can be sufficiently ensured. Considering the plasticization of the thermoplastic resin substrate by water and the favorable performance of stretching in water, 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, when applying and drying the above coating solution, problems such as deformation of the substrate (for example, the occurrence of unevenness, sagging, wrinkles, etc.) can be prevented, and a good laminate can be produced. Also, the stretching of the PVA-based resin layer can be carried out at a suitable temperature (for example, about 60°C). Incidentally, 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 crystallization material. The glass transition temperature (Tg) is a value determined in accordance with JIS K 7121.

[0034] Examples of the thermoplastic resin 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, preferably, norbornene resins and amorphous polyethylene terephthalate resins are used.

[0035] In one embodiment, an amorphous (non-crystallized) polyethylene terephthalate resin is preferably used. Among them, an amorphous (difficult 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 dicarboxylic acids, and copolymers further containing cyclohexanedimethanol or diethylene glycol as glycols.

[0036] In a preferred embodiment, the thermoplastic resin substrate is composed of a polyethylene terephthalate-based resin having isophthalic acid units. Such a thermoplastic resin substrate is extremely excellent in stretchability and can suppress crystallization during stretching. This is considered to be due to introducing isophthalic acid units to give a large bend to the main chain. The polyethylene terephthalate-based resin has terephthalic acid units and ethylene glycol units. The content ratio of the isophthalic acid units 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 ratio of the isophthalic acid units 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 in the drying shrinkage treatment described later.

[0037] The thermoplastic resin substrate may be stretched by any suitable method before forming the PVA-based resin layer. For example, it may be stretched in the transverse direction of the long thermoplastic resin substrate. The transverse direction is preferably a direction substantially orthogonal to the stretching direction of the laminate described later. The stretching temperature of the thermoplastic resin substrate is preferably Tg - 10°C to Tg + 50°C with respect 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. Typically, the coating liquid can 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 PVA-based resin concentration is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. The content of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin, more preferably 10 parts by weight to 15 parts by weight.

[0039] Examples of the above PVA-based resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be 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%, more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined according to JIS K 6726-1994. The average polymerization degree of the PVA-based resin is, for example, 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average polymerization degree can be determined according to JIS K 6726-1994. Examples of the above halide include iodides such as potassium iodide, sodium iodide, and lithium iodide, and sodium chloride. Among these, potassium iodide is preferably used.

[0040] Additives may be added to the coating liquid. Examples of the additives include plasticizers and surfactants. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants.

[0041] When the PVA-based resin layer is stretched, the orientation of polyvinyl alcohol molecules in the PVA-based resin can be increased. However, when the stretched PVA-based resin layer is immersed in a liquid containing water, the orientation of the polyvinyl alcohol molecules may be disrupted and the orientation may decrease. In order to stabilize the stretching of the thermoplastic resin substrate, when the laminate of the thermoplastic resin substrate and the PVA-based resin layer is stretched in boric acid water at a relatively high temperature, the tendency of the orientation to decrease is remarkable. On the other hand, by performing high-temperature stretching (auxiliary stretching) in air before stretching the laminate of the PVA-based resin layer containing a halide and the thermoplastic resin substrate in boric acid water, the crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after the auxiliary stretching can be promoted. As a result, when the PVA-based resin layer is immersed in a liquid, the disruption of the orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed as compared with the case where the PVA-based resin layer does not contain a halide. Thereby, the optical properties of the absorption-type polarizing film obtained through processes such as a dyeing process and a stretching process in water, which are performed by immersing the laminate in a liquid, can be improved.

[0042] In order to obtain high optical properties, a two-stage stretching method combining air stretching (auxiliary stretching) and stretching in boric acid water can be selected. By introducing auxiliary stretching, stretching can be performed while suppressing the crystallization of the thermoplastic resin substrate, solving the problem that the stretchability decreases due to excessive crystallization of the thermoplastic resin substrate in subsequent stretching in boric acid water, and enabling the laminate to be stretched at a high magnification. Also, when applying a PVA-based resin onto the thermoplastic resin substrate, in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate, for example, compared to the case of applying the PVA-based resin onto a metal drum, it is necessary to lower the coating temperature. As a result, the crystallization of the PVA-based resin becomes relatively low, and there may arise a problem that sufficient optical properties cannot be obtained. In contrast, by introducing auxiliary stretching, even when applying a PVA-based resin onto the thermoplastic resin substrate, it becomes possible to increase the crystallinity of the PVA-based resin and achieve high optical properties. Also, by simultaneously increasing the orientation of the PVA-based resin in advance, problems such as a decrease in the orientation or dissolution of the PVA-based resin when immersed in water during subsequent dyeing or stretching treatments can be prevented, and high optical properties can be achieved.

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

[0044] The stretching ratio of air auxiliary stretching is preferably 2.0 to 3.5 times. The air auxiliary stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the stretching ratio is the product of the stretching ratios of each stage. The stretching direction in air auxiliary stretching is preferably substantially the same as the stretching direction in water stretching.

[0045] The stretching temperature for air-assisted stretching is preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably Tg + 10°C or higher of the thermoplastic resin substrate, and even more preferably Tg + 15°C or higher of the thermoplastic resin substrate. On the other hand, the upper limit of the stretching temperature is preferably 170°C. By stretching at such a temperature, the crystallization of the PVA-based resin can be suppressed from proceeding rapidly, and defects due to crystallization (for example, hindering the orientation of the PVA-based resin layer by stretching) can be suppressed. The crystallization index of the PVA-based resin after air-assisted 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 carried out using polarized light as the measurement light, and the crystallization index is calculated according to the following formula using the intensities at 1141 cm -1 and 1440 cm -1 of the obtained spectrum. Crystallization index = (I C / I R ) Here, I C is the intensity at 1141 cm -1 when the measurement light is incident and measured, and I R is the intensity at 1440 cm -1 when the measurement light is incident and measured.

[0046] After the air-assisted stretching treatment and before the underwater stretching treatment or the dyeing treatment, an insolubilization treatment may be performed. The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By the insolubilization treatment, water resistance can be imparted to the PVA-based resin layer, and a decrease in the orientation of PVA when immersed in water can be prevented. The concentration of the aqueous boric acid solution for the insolubilization treatment is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilization bath (aqueous boric acid solution) is preferably 20°C to 50°C.

[0047] The above-described dyeing treatment is typically performed by dyeing the PVA-based resin layer with iodine. Specifically, it is carried out by adsorbing iodine onto the PVA-based resin layer. As a method for adsorbing iodine, preferably, a method of immersing the PVA-based resin layer (laminate) in a dyeing solution (dyeing bath) containing iodine is adopted.

[0048] The above-described dyeing solution is preferably an aqueous iodine solution. In this case, the compounding amount of iodine is preferably 0.05 parts by weight to 0.5 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide to the aqueous iodine solution. Examples of the iodide 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 compounding amount of the iodide is preferably 0.1 parts by weight to 10 parts by weight with respect to 100 parts by weight of water, and more preferably 0.3 parts by weight to 5 parts by weight. The liquid temperature during dyeing of the dyeing solution is preferably 20°C to 50°C in order to suppress the dissolution of the PVA-based resin. When the PVA-based resin layer is immersed in the dyeing solution, the immersion time is preferably 5 seconds to 5 minutes, and more preferably 30 seconds to 90 seconds, in order to ensure the transmittance of the PVA-based resin layer.

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

[0050] When a dyeing process is continuously carried out after a process (for example, an insolubilization process) of immersing a laminate in a treatment bath containing boric acid, the boric acid contained in the treatment bath may mix into the dyeing bath, causing the boric acid concentration in the dyeing bath to change over time. As a result, the dyeability may become unstable. In order to suppress such destabilization of dyeability, the upper limit of the boric acid concentration in the dyeing bath is adjusted to be preferably 4 parts by weight, more preferably 2 parts by weight, per 100 parts by weight of water. On the other hand, the lower limit of the boric acid concentration in the dyeing bath is preferably 0.1 part by weight, more preferably 0.2 part by weight, and even more preferably 0.5 part by weight, per 100 parts by weight of water. In one embodiment, a dyeing bath pre-formulated with boric acid is used. Thereby, the rate of change in boric acid concentration when the boric acid in the treatment bath mixes into the dyeing bath can be reduced. The amount of boric acid pre-formulated in the dyeing bath (that is, the content of boric acid not derived from the treatment bath) is preferably 0.1 to 2 parts by weight, more preferably 0.5 to 1.5 parts by weight, per 100 parts by weight of water.

[0051] After the dyeing process and before the stretching process in water, a crosslinking process may be carried out. The crosslinking process is typically carried out by immersing the PVA-based resin layer in an aqueous boric acid solution. By the crosslinking process, water resistance can be imparted to the PVA-based resin layer, and a decrease in the orientation of PVA when immersed in high-temperature water during subsequent stretching in water can be prevented. The concentration of the aqueous boric acid solution for the crosslinking process is preferably 1 to 5 parts by weight per 100 parts by weight of water. Further, when the crosslinking process is carried out after the dyeing process, it is preferable to further incorporate an iodide. By incorporating an iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The amount of iodide incorporated is preferably 1 to 5 parts by weight per 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably 20°C to 50°C.

[0052] The underwater stretching treatment is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment, stretching can be performed at a temperature lower than the glass transition temperature (typically about 80°C) of the above-mentioned thermoplastic resin base material or the PVA-based resin layer, and the PVA-based resin layer can be stretched while suppressing its crystallization. As a result, a polarizing film having excellent optical properties can be manufactured.

[0053] Any suitable method can be adopted as the stretching method of the laminate. Specifically, fixed-end stretching may be used, or free-end stretching (for example, a method of uniaxially stretching the laminate through rolls with different peripheral speeds) may be used. Preferably, free-end stretching is selected. The stretching of the laminate may be performed in one step or in multiple steps. When performed in multiple steps, the stretching ratio of the laminate described below is the product of the stretching ratios of each step.

[0054] The underwater stretching is preferably performed by immersing the laminate in an aqueous boric acid solution (underwater stretching in boric acid water). By using an aqueous boric acid solution as the stretching bath, rigidity to withstand the tension applied during stretching and water resistance that does not dissolve in water can be imparted to the PVA-based resin layer. Specifically, boric acid can generate tetrahydroxyborate anions in an aqueous solution and crosslink with the PVA-based resin through hydrogen bonds. As a result, rigidity and water resistance are imparted to the PVA-based resin layer, enabling good stretching and manufacturing an absorption-type polarizing film having excellent optical properties.

[0055] The above-mentioned aqueous boric acid solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 part by weight to 10 parts by weight, more preferably 2.5 parts by weight to 7 parts by weight, and even more preferably 3 parts by weight to 6 parts by weight, based on 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and an absorption-type polarizing film with higher characteristics can be manufactured. In addition to boric acid or borate, aqueous solutions obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.

[0056] Preferably, an iodide is added to the above-described stretching bath (aqueous boric acid solution). By adding an iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. Specific examples of the iodide are as described above. The concentration of the iodide is preferably 0.05 parts by weight to 15 parts by weight, more preferably 0.5 parts by weight 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, stretching can be performed well. 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, there is a possibility that good stretching cannot be achieved even considering 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, and there is a possibility that excellent optical properties cannot be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

[0058] In one embodiment, the stretching ratio by stretching in water is preferably 1.5 times or more, more preferably 2.0 times or more, may be 2.5 times or more, and may be 3.0 times or more. The total stretching ratio of the laminate exceeds, for example, 4.5 times with respect to the original length of the laminate, is preferably 5.0 times or more, and may be 5.5 times or more. By achieving such a high stretching ratio, an absorption-type polarizing film excellent in optical properties can be manufactured. Such a high stretching ratio can be achieved by adopting a stretching method in water (stretching in aqueous boric acid).

[0059] The above drying and shrinkage treatment may be performed by zone heating that heats the entire zone, or may be performed by heating the conveying rolls (using so-called heating rolls). Preferably, both are used. By drying using heating rolls, the heating curl of the laminate can be efficiently suppressed, and an absorption-type polarizing film with excellent appearance can be manufactured. Specifically, by drying with the laminate along the heating roll, the crystallization of the thermoplastic resin substrate can be efficiently promoted and the degree of crystallization can be increased. Even at a relatively low drying temperature, the degree of crystallization of the thermoplastic resin substrate can be favorably increased. As a result, the thermoplastic resin substrate increases in rigidity and becomes capable of withstanding the shrinkage of the PVA-based resin layer due to drying, and curl is suppressed. Further, by using heating rolls, drying can be performed while maintaining the laminate in a flat state, so that not only curl but also the occurrence of wrinkles can be suppressed. At this time, the optical properties of the laminate can be improved by shrinking it in the width direction by the drying and shrinkage treatment. This is because the orientation of PVA and the PVA / iodine complex can be effectively enhanced. The shrinkage rate in the width direction of the laminate due to the drying and shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using heating rolls, the laminate can be continuously shrunk in the width direction while being conveyed, and high productivity can be achieved.

[0060] For example, the drying conditions can be controlled by adjusting the heating temperature of the conveying rolls (the temperature of the heating rolls), the number of heating rolls, the contact time with the heating rolls, and the like. 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. The degree of crystallization of the thermoplastic resin can be favorably increased, curl can be favorably suppressed, and excellent strength can be imparted to the laminate. The temperature of the heating rolls can be measured by a contact thermometer. Usually, 2 to 40 conveying rolls are used, preferably 4 to 30. The contact time (total contact time) between the laminate and the heating rolls is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and even more preferably 1 to 10 seconds.

[0061] The heating roll may be provided in a heating furnace (for example, an oven), or may be provided on a normal production line (at room temperature environment). Preferably, it is provided in a heating furnace equipped with air blowing means. By using both drying by the heating roll and hot air drying, a sharp temperature change between the heating rolls can be suppressed, and shrinkage in the width direction can be easily controlled. The temperature of the hot air drying is preferably 30°C to 100°C. The hot air drying time is preferably 1 second to 300 seconds. The wind speed of the hot air is preferably about 10 m / s to 30 m / s. Note that the wind speed is the wind speed in the heating furnace and can be measured by a mini-vane type digital anemometer.

[0062] Preferably, a cleaning treatment is performed after the underwater stretching treatment and before the dry shrinkage treatment. The above cleaning treatment is performed, for example, by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

[0063] <Protective layer> The protective layer that can be included in the absorption type polarizing member can be composed of any suitable film. Examples of the material that is 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, cycloolefin-based such as polynorbornene, polyolefin-based, (meth)acrylic-based, acetate-based resins, etc. Among these, (meth)acrylic-based resins and cycloolefin-based resins are preferably used. By adopting these resins, a protective layer excellent in smoothness can be formed by extrusion molding, and an absorption type polarizing member excellent in smoothness can be obtained. In addition, the protective layer composed of a cycloolefin-based resin can be excellent in the durability of the birefringence characteristics (for example, 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. Note that the surface smoothness can be measured by focusing the irradiated light on the surface of the object.

[0065] <Adhesive layer> The adhesive layer 51 that may be included in the absorption type polarizing member 28 can be formed of any suitable adhesive. As the adhesive, for example, an aqueous adhesive, a solvent-based adhesive, a hot melt adhesive, a curable adhesive (e.g., an active energy ray curable adhesive), etc. are used.

[0066] The thickness of the adhesive layer that may be included in the absorption type polarizing member 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 absorption type polarizing member excellent in smoothness can be obtained. The thickness of the adhesive layer that may be included in the absorption type polarizing member is, from the viewpoint of adhesiveness, etc., for example, 0.01 μm or more, preferably 0.5 μm or more.

[0067] <Laminated film> The above laminated film typically includes a base material. The thickness of the base material 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 base material 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 base material can be composed of any suitable film. Examples of the material that is the main component of the film constituting the base material include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based such as polynorbornene, polyolefin-based, (meth)acrylic-based, acetate-based resins, etc. Here, (meth)acrylic refers to acrylic and / or methacrylic. In one embodiment, the base material is preferably composed of a (meth)acrylic resin. By adopting a (meth)acrylic resin, a base material with excellent smoothness (for example, satisfying the above surface smoothness) can be formed into a film by extrusion molding. And a laminated film with excellent smoothness can be obtained.

[0069] As described above, the laminated film typically has a base material and a surface treatment layer formed on the base material. The thickness of the laminated film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and even more preferably 20 μm to 45 μm. The thickness of the surface treatment layer is, 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 the base material and curing the coating layer. The hard coat layer forming material typically contains a curable compound as a layer forming component. Examples of the curing mechanism of the curable compound include thermosetting type and photocuring type. 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 monomers or oligomers having two or more (meth)acryloyl groups, urethane (meth)acrylate or oligomers of urethane (meth)acrylate, epoxy-based monomers or oligomers, and silicone-based monomers or oligomers.

[0071] In addition to the hard coat layer, the surface treatment layer may include a functional 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 from 0.05 μm to 10 μm, more preferably from 0.1 μm to 5 μm, and still more preferably from 0.1 μm to 2 μm.

[0072] The laminated film 31 having the surface treatment layer 31b can be located outermost in the optical laminate 1. The surface treatment layer can have any suitable function. The surface treatment layer preferably has an antireflection function, for example, from the viewpoint of suppressing light loss at the interface with air and from the viewpoint of improving visibility.

[0073] <Retardation member> The retardation member is formed of any suitable material that can satisfy desired optical properties. The retardation member (for example, a λ / 4 member) can be, for example, a stretched film of a resin film or an alignment cured layer of a liquid crystal compound.

[0074] Examples of the resin contained in the resin film include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, acrylic resins, and the like. These resins may be used alone or in combination. Examples of the combination method include blending and copolymerization. When the retardation member exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be preferably used.

[0075] As the above polycarbonate resin, any suitable polycarbonate resin can be used. For example, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from an alicyclic dimethanol and / or a structural unit derived from di-, tri- or polyethylene glycol; More preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri- or polyethylene glycol. The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. The details of the polycarbonate resin and the method for forming the retardation member that can be preferably used for the retardation member are described, for example, in JP-A Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818, and the descriptions of these publications are incorporated herein by reference.

[0076] The thickness of the retardation member composed of the stretched film of the 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 alignment and solidification layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer and its alignment state is fixed. Note that the "alignment and solidification layer" is a concept that includes the alignment and curing layer obtained by curing a liquid crystal monomer as described later. In the retardation member, typically, rod-shaped liquid crystal compounds are aligned in the direction of the slow axis of the retardation member (homogeneous alignment). Examples of the rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. When the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by polymerizing the liquid crystal compound after it is aligned.

[0078] The alignment and solidification layer (liquid crystal alignment and solidification layer) of the liquid crystal compound can be formed by subjecting the surface of a predetermined substrate to an alignment treatment, applying a coating liquid containing the liquid crystal compound to the surface to align the liquid crystal compound in the direction corresponding to the alignment treatment, and fixing the alignment state. As the alignment treatment, any appropriate alignment treatment can be adopted. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of the mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of the chemical alignment treatment include oblique evaporation method and photo-alignment treatment. The treatment conditions of various alignment treatments can be any appropriate conditions according to the purpose.

[0079] The alignment of the liquid crystal compound is performed by treating at the temperature at which the liquid crystal compound exhibits a liquid crystal phase according to the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes a liquid crystal state and the liquid crystal compound is aligned according to the alignment treatment direction of the substrate surface.

[0080] In one embodiment, the fixing of the alignment state is performed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the fixing of the alignment state is performed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0081] As the liquid crystal compound, any suitable liquid crystal polymer and / or liquid crystal monomer can be used. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of the liquid crystal compound and the method for producing the liquid crystal alignment curing layer are described in, for example, JP-A-2006-163343, JP-A-2006-178389, and WO 2018 / 123551. The descriptions in these publications are incorporated herein by reference.

[0082] The thickness of the retardation member composed of the liquid crystal alignment curing layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and still more preferably 1 μm to 4 μm.

[0083] <Adhesive layer> The thickness of the adhesive layer used for laminating the above members can be set to any appropriate thickness respectively. The thickness of each adhesive layer used for laminating the above members is, for example, 15 μm or less, preferably 12 μm or less, more preferably 10 μm or less, and still more preferably 7 μm or less. With such a thickness, excellent smoothness can be obtained. On the other hand, the thickness of each adhesive layer used for laminating the above members is preferably 3 μm or more. For example, the thickness of the adhesive layer disposed between the laminated film 31 and the absorption type polarizing member 28 is preferably 12 μm or less, more preferably 10 μm or less, and still more preferably 7 μm or less. Specifically, the laminated film 31 and the retardation member 30 can be preferably laminated via an adhesive layer having a thickness of 12 μm or less. Also, the thickness of the adhesive layer disposed between the absorption type polarizing member 28 and the retardation member 30 is preferably 12 μm or less, more preferably 10 μm or less, and still more preferably 7 μm or less.

[0084] The adhesive layer can be composed of any suitable adhesive. As specific examples, the adhesive layer can be composed of an adhesive based on a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer. By adjusting the type, number, combination, and blending ratio of the monomers constituting the base polymer of the adhesive, as well as the blending amount of the crosslinking agent, the reaction temperature, the reaction time, etc., an adhesive having desired properties according to the purpose can be prepared. The base polymer of the adhesive may be used alone or in combination of two or more. As the base polymer, an acrylic polymer is preferably used. Specifically, the adhesive layer is preferably composed of an acrylic adhesive.

[0085] Any suitable other optical member may be laminated on the absorption type polarizing member 28 of the optical laminate 1. And the optical laminate 1 can be used for any suitable display body. The optical laminate 1 can be suitably used for, for example, a VR goggles.

[0086] [Display system] FIG. 2 is a schematic diagram showing a schematic configuration of an example of a display system of a 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 member 14, a first lens unit 16, a half mirror 18, a first λ / 4 member 20, a second λ / 4 member 22, and a second lens unit 24. The reflective polarizing member 14 is disposed in front of the display surface 12a side of the display element 12 and can reflect the light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflective polarizing member 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first λ / 4 member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14.

[0087] The half mirror, or components arranged in front of the first lens unit (in the illustrated example, the half mirror 18, the first lens unit 16, the second λ / 4 member 22, the reflective polarizing member 14, and the second lens unit 24) may be collectively referred to as a 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 12a for displaying an image. The light emitted from the display surface 12a passes through, for example, a polarizing member that may be included in the display element 12 and is emitted as 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 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 toward the reflective polarizing member 14. The half mirror 18 is provided integrally with the first lens unit 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 unit 16.

[0092] The first circularly polarized light emitted from the first λ / 4 member 20 passes through the half mirror 18 and the first lens unit 16 and is converted into second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light emitted 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 member 14 is converted into second circularly polarized light by the second λ / 4 member 22, and the second circularly polarized light emitted from the second λ / 4 member 22 passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into third linearly polarized light by the second λ / 4 member 22. The third linearly polarized light passes through the reflective polarizing member 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member 14 is in the same direction as the transmission axis of the reflective polarizing member 14. Therefore, the third linearly polarized light incident on the reflective polarizing member 14 passes through the reflective polarizing member 14.

[0094] The light that has passed through the reflective polarizing member 14 passes through the second lens unit 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 arranged substantially parallel to each other or substantially orthogonally. The angle formed by the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first λ / 4 member 20 is, for example, 40° to 50°, may be 42° to 48°, or may be about 45°. The angle formed by the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second λ / 4 member 22 is, for example, 40° to 50°, may be 42° to 48°, or may be about 45°.

[0096] The in-plane retardation Re(550) of the first λ / 4 member 20 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 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. Re(450) / Re(550) of the first λ / 4 member 20 is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

[0097] The in-plane phase difference Re(550) of the second λ / 4 member 22 is, for example, from 100 nm to 190 nm, may be from 110 nm to 180 nm, may be from 130 nm to 160 nm, or may be from 135 nm to 155 nm. The second λ / 4 member 22 preferably exhibits an inverse-dispersion wavelength characteristic in which the phase difference value increases according to the wavelength of the measurement light. Re(450) / Re(550) of the second λ / 4 member 22 is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

[0098] In the display system 10, a space may be formed between the first lens unit 16 and the second lens unit 24. In this case, the member disposed between the first lens unit 16 and the second lens unit 24 is preferably provided integrally with either the first lens unit 16 or the second lens unit 24. For example, the member disposed between the first lens unit 16 and the second lens unit 24 is integrated with either the first lens unit 16 or the second lens unit 24 via an adhesive layer. According to such a form, for example, the handleability of each member can be excellent. The adhesive layer may be formed of an adhesive or an adhesive agent. Specifically, the adhesive layer may be an adhesive layer or an adhesive agent layer. The thickness of the adhesive layer is, for example, from 0.01 μm to 60 μm.

[0099] The optical laminate according to an embodiment of the present invention can have, for example, a member provided in the above display system. The optical laminate can have other members such as an adhesive layer for integrating adjacent members. The thickness of the optical laminate varies depending on, for example, the type and number of the included members, but is, for example, 50 μm to 400 μm. The optical laminate can be integrated with, for example, the first lens portion 16 or the second lens portion 24. Typically, it can be bonded to the first lens portion 16 or the second lens portion 24, which is an adherend, via an adhesive layer. When bonding (for example, before bonding to the adherend), the optical laminate may be heated. For example, when the adherend surface of the adherend is a curved surface as in the first lens portion 16 shown in FIG. 2, it is preferable to heat the optical laminate. By heating, the optical laminate becomes more deformable, and the optical laminate can be bonded to the curved surface without leaving a gap. 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 member is laminated on the absorption-type polarizing member of the optical laminate shown in FIG. 1. The optical laminate 2 has an absorption-type polarizing member 28 that can be disposed between the reflective polarizing member 14 and the second lens portion 24, a third λ / 4 member 30 corresponding to the retardation member, and a laminated film 31. The in-plane retardation Re(550) of the third λ / 4 member 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 member 30 preferably exhibits an inverse-dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. Re(450) / Re(550) of the third λ / 4 member is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

[0101] The above λ / 4 member preferably exhibits a refractive index characteristic showing a relationship of nx > ny ≧ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny < nz may occur. The Nz coefficient of the λ / 4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0102] The optical laminate 2 has a reflective polarizing member 14. The reflective polarizing member 14 is laminated via an adhesive layer 43 behind the absorptive polarizing member 28. In FIG. 3, the reflective polarizing member 14 is laminated below the absorptive polarizing member 28. The reflection axis of the reflective polarizing member 14 and the absorption axis of the absorptive polarizing member 28 (absorptive polarizing film 28a) can be arranged substantially parallel to each other, and the transmission axis of the reflective polarizing member 14 and the transmission axis of the absorptive polarizing member 28 (absorptive polarizing film 28a) can be arranged substantially parallel to each other. In the optical laminate 2, the absorptive polarizing member 28 is used, for example, from the viewpoint of improving visibility. Further, in the optical laminate 2, by providing a third λ / 4 member (retardation member) 30, for example, reflection of external light from the second lens unit 24 side can be prevented.

[0103] The peel strength of the absorptive polarizing member 28 with respect to the 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, the occurrence of peeling between the members included in the optical laminate can be effectively suppressed.

[0104] The above reflective polarizing member transmits polarized light parallel to its transmission axis (typically linearly polarized light) while maintaining its polarization state, and reflects light in other polarization states (typically light in a polarization state orthogonal to its transmission axis). Typically, the reflective polarizing member is composed of a film having a multilayer structure (which may be referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing member is, for example, 10 μm to 150 μm, preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

[0105] Figure 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure 14a has alternately a layer A having birefringence and a layer B having substantially no birefringence. The total number of layers constituting the multilayer structure may be 50 to 1000. For example, the refractive index nx in the x-axis direction of layer A is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction and the refractive index ny in the y-axis direction of layer B are substantially the same. 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 above layer A is typically composed of a material that exhibits birefringence by stretching. Examples of such materials include naphthalenedicarboxylic acid polyester (e.g., polyethylene naphthalate), polycarbonate, and acrylic resin (e.g., polymethyl methacrylate). The above layer B is typically composed of a material that does not substantially exhibit birefringence even when stretched. Examples of such materials include a copolyester of naphthalenedicarboxylic acid and terephthalic acid. The above multilayer structure can be formed by combining coextrusion and stretching. For example, after extruding the material constituting layer A and the material constituting layer B, they are multilayered (e.g., using a multiplier). Then, the obtained multilayer laminate is stretched. The x-axis direction in the illustrated example may correspond to the stretching direction.

[0107] Examples of commercially available reflective polarizing films include products named "DBEF" and "APF" manufactured by 3M, and a product named "APCF" manufactured by Nitto Denko Corporation.

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

[0109] The above orthogonal transmittance, single transmittance, and degree of polarization can be measured, for example, using an ultraviolet-visible spectrophotometer. The degree of polarization P can be obtained from the following formula using an ultraviolet-visible spectrophotometer to measure the single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc, and the obtained Tp and Tc. Note that Ts, Tp, and Tc are Y values measured by the 2-degree field of view (C light source) of JIS Z 8701 and corrected for visual sensitivity. 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 has a second λ / 4 member 22. The second λ / 4 member 22 is laminated on the reflective polarizing member 14 via an adhesive layer 44.

[0112] The second λ / 4 member 22 is formed of any suitable material that can satisfy the above characteristics. The second λ / 4 member 22 can be, for example, a stretched film of a resin film or an alignment cured layer of a liquid crystal compound. For the second λ / 4 member 22 composed of a stretched film of a resin film or an alignment cured layer of a liquid crystal compound, the same description as that of the above retardation member (λ / 4 member) can be applied. The second λ / 4 member and the third λ / 4 member may be members having the same configuration (for example, forming material, thickness, optical characteristics, etc.), or may be members having different configurations.

[0113] In addition to the second λ / 4 member 22, the optical laminate 2 has another retardation member 23 whose refractive index characteristics exhibit the relationship nz > nx ≥ ny. By using the member 23 exhibiting the relationship nz > nx ≥ ny, light leakage (for example, light leakage in an oblique direction) can be prevented. As shown in FIG. 3, it is preferable that the second λ / 4 member 22 is positioned forward of the member 23 exhibiting the relationship nz > nx ≥ ny. The member 23 exhibiting the relationship nz > nx ≥ ny is laminated on the second λ / 4 member 22 via an adhesive layer 52.

[0114] The in-plane retardation Rth(550) in the thickness direction of the member whose refractive index characteristics exhibit the relationship 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" includes not only the case where nx and ny are exactly equal but also the case where nx and ny are substantially equal. For example, it also includes the case where Re(550) is less than 10 nm. In another embodiment, the other retardation member 23 has a refractive index relationship of 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 whose refractive index characteristics exhibit the relationship nz > nx ≥ ny can be formed of any suitable material. Preferably, it is composed of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and film formation methods include the liquid crystal compounds and formation methods described in paragraphs

[0020] to

[0042] of JP-A-2002-333642. 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 specific example, the member having the refractive index characteristic of nz > nx ≧ ny may be a retardation film formed of a diester fumarate resin described in JP-A-2012-32784. In this case, the thickness is preferably 5 μm to 50 μm, more preferably 10 μm to 35 μm.

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

Examples

[0118] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Note that the thickness, shrinkage force, elastic modulus, peel force, retardation value, and surface smoothness are values measured by the following measurement methods. Also, unless otherwise specified, "parts" and "%" are based on weight. <Thickness> For a thickness of 10 μm or less, it was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). For a thickness exceeding 10 μm, it was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Shrinkage force> The measurement target was punched out using a blade shape of 100 mm (length) × 25 mm (width) to obtain a strip-shaped measurement sample. The punching was performed so that the length direction was along the absorption axis direction or the reflection axis direction of the measurement target. In an autograph with a thermostat (AG-Xplus manufactured by Shimadzu Corporation), in a state where a range of 5 mm from both ends in the length direction of the obtained measurement sample was chucked with a jig without being pulled, it was placed in an environment at a temperature of 120°C, and the shrinkage force (N) generated between the jigs 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 in length × 20 mm in width with a cutting machine to obtain test pieces. The cut surface of the obtained test pieces was cut using a microtome and left (humidity-conditioned) in an environment of 23°C and 55% RH for 3 hours, and then measurement was performed using a nanoindenter. For the measurement using the nanoindenter, "Triboindenter" manufactured by Hysitron Inc was used, and a Berkovich (triangular pyramid) was used as the indenter. Under the following conditions, the load-displacement curve was measured by pressing into the hard coat layer of the laminated film from the cut surface, 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 / second · Indentation depth: 100 nm <Peeling force> A sample cut out from the measurement target to a size of 25 mm in width and 50 mm in length was left in an environment of 23°C and a relative humidity of 50% RH for 30 minutes or more, and then the peeling force (N / 25 mm) when peeling in the length direction at a peeling speed of 300 mm / min and a peeling angle of 180° was measured using a universal tensile testing machine. The measurement was performed in an environment of 23°C and a relative humidity of 50% RH. <Phase difference value> Using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"), the phase difference values at each wavelength at 23°C were measured. <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 stage with a vibration isolator, interference fringes were generated using single white LED illumination, and the interference objective lens (1.4 times) with a reference surface was scanned in the Z direction (thickness direction) to selectively obtain the smoothness (surface smoothness) of the outermost surface of the measurement target in a field of view of 12.4 mm□. When the object to be measured was the adhesive layer, the adhesive layer was bonded 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, an acrylic adhesive layer with a thickness of 5 μm and few irregularities was formed on the above glass, and the film to be measured was laminated on this adhesive surface so that foreign matters, air bubbles, and streaks of deformation did not enter, and the smoothness of the surface on the side opposite to the adhesive layer was measured. Incidentally, the surface smoothness of the acrylic adhesive layer with a thickness of 5 μm and few irregularities was 0.30 arcmin. Regarding the analysis, a value obtained by doubling the angular index "Slope magnitude RMS" (corresponding to 2σ) was defined as the surface smoothness (unit: arcmin).

[0119] [Production Example 1-1] (Formation of Absorptive Polarizing Film) As the thermoplastic resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) in a long strip shape with a water absorption rate of 0.75% and a Tg of about 75 °C was used. One side of the resin substrate was subjected to corona treatment. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, trade name "Gosenex Z410") at a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60 °C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (lengthwise direction) between rolls with different peripheral speeds in an oven at 130 °C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 40 °C (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilizing treatment). Next, it was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizing film became 43.0% in a dyeing bath at a liquid temperature of 30 °C (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) (dyeing treatment). Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40 °C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) (crosslinking treatment). Thereafter, while immersing the laminate in a boric acid aqueous solution at a liquid temperature of 70 °C (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%), uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds so that the total stretching ratio became 5.5 times (the stretching ratio due to stretching in water was 2.3 times) (stretching treatment in water). Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 20 °C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) (washing treatment). Thereafter, while drying in an oven maintained at 90 °C, it was brought into contact with a SUS-made heating roll whose surface temperature was maintained at 75 °C for about 2 seconds (dry shrinkage treatment). The shrinkage ratio in the width direction of the laminate due to the dry shrinkage treatment was 5.2%. In this way, an absorption-type polarizing film with 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 absorption-type polarizing film) An absorption-type polarizing film with 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 of the stretching treatment in water was changed to 68 °C and the stretching was performed so that the total stretching ratio became 5.3 times (the stretching ratio due to stretching in water was 2.2 times) in the stretching treatment in water.

[0121] [Production Example 1-3] (Formation of absorption-type polarizing film) An absorption-type polarizing film with 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 of the stretching treatment in water was changed to 68 °C.

[0122] [Production Example 1-4] (Formation of Absorptive Polarizing Film) An absorptive polarizing film with 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 of the underwater stretching treatment was changed to 65°C and the total stretching ratio was 5.0 times (the stretching ratio due to underwater stretching was 2.1 times) in the underwater stretching treatment.

[0123] [Production Example 1-5] (Formation of Absorptive Polarizing Film) An absorptive polarizing film with 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 of the underwater stretching treatment was changed to 62°C and the total stretching ratio was 5.0 times (the stretching ratio due to underwater stretching was 2.1 times) in the underwater stretching treatment.

[0124] [Production Example 2-1] (Production of Laminated Film) The following hard coat layer forming material 1 was applied to an acrylic film having a lactone ring structure (thickness: 40 μm, surface smoothness: 0.45 arcmin), and heated at 90°C for 1 minute. The applied layer after heating was irradiated with ultraviolet rays having an integrated light amount of 300 mJ / cm 2 from a high-pressure mercury lamp to cure the applied layer, thereby forming a hard coat layer with a thickness of 4 μm, an elastic modulus of 2.4 GPa at 120°C, and an elastic modulus of 5.8 GPa at room temperature. Next, the following coating liquid A for forming an antireflection layer was applied onto the hard coat layer with a wire bar, and the applied coating liquid was heated at 80°C for 1 minute and dried to form a coating film. The coating film after drying was irradiated with ultraviolet rays having an integrated light amount of 300 mJ / cm 2 from a high-pressure mercury lamp to cure the coating film, thereby forming an antireflection layer A with a thickness of 140 nm. Subsequently, the following coating liquid B for forming an antireflection layer was applied onto the antireflection layer A with a wire bar, and the applied coating liquid was heated at 80°C for 1 minute and dried to form a coating film. The coating film after drying was irradiated with ultraviolet rays having an integrated light amount of 300 mJ / cm 2 from a high-pressure mercury lamp to cure the coating film, thereby forming an antireflection layer B with a thickness of 105 nm. Thus, a laminated film (thickness: 44 μm) was obtained.

[0125] (Hard coat layer forming material 1) 50 parts of urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 30 parts of polyfunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100"), and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., "Irgacure 907") were mixed and diluted with methyl isobutyl ketone so that the solid content concentration became 50% to prepare Hard coat layer forming material 1.

[0126] (Coating liquid A for forming antireflection layer) 100 parts by weight of polyfunctional acrylate (manufactured by Arakawa Chemical Industries, Ltd., trade name "Optester KZ6728", solid content 20% by weight), 3 parts by weight of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100"), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name "OMNIRAD 907", solid content 100% by weight) were mixed. Butyl acetate was used as a diluting solvent for the mixture so that the solid content became 12% by weight, and it was stirred to prepare Coating liquid A for forming antireflection layer.

[0127] (Coating liquid B for forming antireflection layer) 100 parts by weight of a polyfunctional acrylate having pentaerythritol triacrylate as a main component (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300", solid content: 100% by weight), 150 parts by weight of hollow nanosilica particles (manufactured by JGC Catalysts & Chemicals Ltd., trade name "Thruia 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 element-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 "OMNIRAD 907", solid content: 100% by weight) were mixed. To the mixture, a mixed solvent obtained by mixing TBA (tert-butyl alcohol), MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15 was added so that the total solid content became 4% by weight, and the mixture was stirred to prepare a coating liquid B for forming an antireflection 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 acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., "NK Oligo UA-53H"), 40 parts of a polyfunctional acrylate having pentaerythritol triacrylate as a main component (manufactured by Osaka Organic Chemical Industry Co., trade name "Biscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100") and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan Co., "Irgacure 907") were mixed and diluted with methyl isobutyl ketone so that the solid content concentration became 50% to prepare a 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 urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 50 parts of polyfunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100"), and 3 parts of photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., "Irgacure 907") were mixed and diluted with methyl isobutyl ketone so that the solid content concentration was 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, 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 urethane acrylate oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 60 parts of polyfunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Biscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100"), and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., "Irgacure 907") were mixed and diluted with methyl isobutyl ketone so that the solid content concentration became 50% to prepare a hard coat layer forming material 4.

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

[0135] [Chemical formula] [Chemical formula]

[0136] [Production Example 4] (Formation of Positive C Plate) 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 molar% of monomer units and are represented by a block polymer for convenience: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal showing 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) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating solution. Then, the coating solution was applied to a vertically aligned PET substrate 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 rays to cure the liquid crystal layer, thereby forming a positive C plate with a thickness of 4 μm and Rth(550) of -100 nm on the substrate. [Chemical formula]

[0137] [Production Example 5] (Formation of Adhesive Layer) 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 was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. Further, 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with 200 parts by weight of ethyl acetate per 100 parts by weight of this monomer mixture, and nitrogen gas was introduced while gently stirring to replace the inside of the flask with nitrogen. Then, the polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 1.78 million. The coating film on the base film obtained by coating an acrylic polymer solution on the base film was dried in an oven to form an adhesive layer with a thickness of 5 μm and a surface smoothness of 0.30 arcmin.

[0138] [Production Example 6] (Production of Optical Laminate) An acrylic film having a lactone ring structure with a thickness of 20 μm and a surface smoothness of 0.10 arcmin was bonded to the absorption type polarizing film of Production Example 1 using an ultraviolet curable adhesive (thickness after curing: 0.7 μm) to obtain an absorption type polarizing member.

[0139] The resin base material was peeled off from the absorption type polarizing member, and the λ / 4 member of Production Example 3 was bonded to the absorption type polarizing film via the adhesive layer of Production Example 5 so that the absorption axis of the absorption type polarizing film and the slow axis of the λ / 4 member formed an angle of 45°. Next, the laminated film of Production Example 2 (acrylic film formed with a hard coat layer and an antireflection layer) was bonded to the λ / 4 member via the adhesive layer of Production Example 5. Here, it was bonded so that the acrylic film of the laminated film was located on the λ / 4 member side.

[0140] Further, a reflective polarizing film ("APCF" manufactured by Nitto Denko Corporation, shrinkage force: 8 N) was bonded to the acrylic film of the absorption type polarizing member via an adhesive layer with a thickness of 9 μm. Here, it was bonded so that the reflection axis of the reflective polarizing film and the absorption axis of the absorption type polarizing film were arranged parallel to each other. Next, the λ / 4 member of Production Example 3 and the positive C plate of Production Example 4 were bonded to the reflective polarizing film via the adhesive layer of Production Example 5 in this order. Here, it was bonded so that the reflection axis of the reflective polarizing film (absorption axis of the absorption type polarizing film) and the slow axis of the λ / 4 member formed an angle of 45°. Also, the λ / 4 member and the positive C plate were bonded using an ultraviolet curable adhesive (thickness after curing: 1 μm). Next, an adhesive layer with a thickness of 50 μm was provided on the positive C plate to obtain an optical laminate.

[0141] In the above Production Example 6, for the optical laminate obtained by combining the absorption-type polarizing film obtained in Production Examples 1-1 to 1-5 and the laminated film obtained in Production Examples 2-1 to 2-4, the reliability was evaluated by the following method. The evaluation results are shown in Table 1. Also, regarding the evaluation results of the reliability, the shrinkage force S (unit: N) of the absorption-type polarizing film at 120°C and the product of the elastic modulus Er 120 (unit: GPa) and the thickness T (unit: μm) of the hard coat layer, Er 120 ·T (GPa·μm) are shown in Fig. 5. In Fig. 5, when the evaluation results were good, they were plotted as white circles, and when the evaluation results were bad, they were plotted as black circles. <Evaluation of Reliability> The obtained optical laminate was bonded to a non-alkali glass plate with a flat surface, and then this was 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 100 times in total to conduct 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 taken for heating and cooling was set to be within 6 minutes. (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. Bad: Peeling occurred in the optical laminate up to a region 100 μm or more from the end face.

[0142]

Table 1

[0143] In the above reliability evaluation, peeling was mainly confirmed between the absorption-type polarizing member and the reflection-type polarizing member (reflection-type polarizing film). Specifically, it was confirmed at the interface between the acrylic film and the adhesive layer of the absorption-type polarizing member. Here, the peeling force of the acrylic film with respect to the adhesive layer was 2.9 N / 25 mm. Note that both the absorption-type polarizing member and the reflection-type polarizing member (reflection-type polarizing film) are members obtained through a stretching process.

[0144] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, it can be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

Industrial Applicability

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

Explanation of Reference Numerals

[0146] 1 Optical laminate, 2 Optical laminate, 4 Lens part, 10 Display system, 12 Display element, 12a Display surface, 14 Reflection-type polarizing member, 14a Multilayer structure, 16 First lens part, 18 Half mirror, 20 First λ / 4 member, 22 Second λ / 4 member, 24 Second lens part, 28 Absorption-type polarizing member, 28a Absorption-type polarizing film, 28b Protective layer, 30 Phase difference member, 31 Laminated film (protective member), 31a Base material, 31b Surface treatment layer (hard coat layer), 41 Adhesive layer, 42 Adhesive layer, 43 Adhesive layer, 44 Adhesive layer, 45 Adhesive layer, 51 Adhesive layer, 52 Adhesive layer.

Claims

1. A laminated film having a base material and a hard coat layer, and An absorption type polarizing member including an absorption type polarizing film, comprising: The shrinkage force S (unit: N) of the absorptive polarizing film at 120°C and the elastic modulus Er １２０ (unit: GPa), the product Er １２０ ·T (GPa·μm) means that Er １２０ ·T satisfies the relationship of T > 0.85 × S - 4.02 An optical laminate.

2. The laminated film, the absorption type polarizing member, and another optical member are provided in this order, The absorption type polarizing member and the other optical member are laminated via an adhesive layer, The optical laminate according to claim 1.

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

4. The optical laminate according to claim 2, wherein the peel strength of the absorption type polarizing member with respect to the adhesive layer is 2 N / 25 mm or more.

5. The optical laminate according to claim 1, further comprising a retardation member disposed between the laminated film and the absorption type polarizing member.

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

7. An adhesive layer is provided between the laminated film and the absorption type polarizing member, The thickness of the adhesive layer is 12 μm or less, The optical laminate according to claim 1.

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

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

10. A lens unit used in a display system for displaying an image to a user, The optical laminate according to claim 3, which reflects light emitted forward from the display surface of a display element representing an image and passing through a polarizing member and a first λ / 4 member, A first lens unit disposed on the optical path between the display element and the optical laminate, A half mirror disposed between the display element and the first lens unit, which transmits light emitted from the display element and reflects light reflected by the reflective polarizing member of the optical laminate toward the reflective polarizing member, A second λ / 4 member disposed on the optical path between the half mirror and the optical laminate, Comprising a lens unit.

11. Passing light representing an image emitted through a polarizing member and a first λ / 4 member through a half mirror and a first lens unit, Passing the light passing through the half mirror and the first lens unit through a second λ / 4 member, Reflecting the light passing through the second λ / 4 member toward the half mirror with the optical laminate according to claim 3, A step of making the light reflected by the reflective polarizing member and the half mirror of the optical laminate transmissible through the reflective polarizing member by the second λ / 4 member; A display method having the above.

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

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