WO2025126954A1 - Optical laminate, lens part, and display method - Google Patents

Abstract

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

Description

Optical laminate, lens portion and display method

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

Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices), are rapidly becoming popular. In image display devices, optical components such as phase difference components and polarizing components are generally used to realize image display and improve image display performance (see, for example, Patent Document 1). These optical components can be integrated in advance and mounted on the image display device as an optical laminate.

In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) that realize Virtual Reality (VR) have begun to be commercialized. As VR goggles are being considered for use in a variety of situations, there is a demand for them to be lightweight and have improved visibility.

JP 2021-103286 A

The weight of the VR goggles can be reduced, for example, by making the lenses used in the VR goggles thinner. On the other hand, there is also a need to develop an optical laminate that includes the optical component described above and is suitable for a display system that uses thin lenses.

In view of the above, the primary objective of the present invention is to provide an optical laminate that can effectively reduce the weight of VR goggles while improving visibility.

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

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

The optical laminate according to the embodiment of the present invention can effectively reduce the weight of VR goggles while improving visibility.

1 is a schematic cross-sectional view showing a general configuration of an optical laminate according to one embodiment of the present invention. 1 is a schematic diagram showing a general configuration of an example of a display system for VR goggles. 2 is a schematic cross-sectional view showing an example of a state in which another optical member is laminated on the absorptive polarizing member of the optical laminate shown in FIG. 1 . FIG. 2 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. 1 is a graph showing the relationship between the contraction force S of an absorptive polarizing film at 120° C. and the product Er ₁₂₀ ·T of the elastic modulus Er ₁₂₀ at 120° C. and the thickness T of a hard coat layer, as a result of reliability evaluation.

Below, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to make the description clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. In addition, in the drawings, the same or equivalent elements are given the same reference numerals, and duplicate descriptions may be omitted.

(Definition of terms and symbols)
The definitions of terms and symbols used in this specification are as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23° C. Re(λ) is calculated by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Retardation in the thickness direction (Rth)
"Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23° C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23° C. Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is calculated by Nz=Rth/Re.
(5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise angles with respect to a reference direction. Thus, for example, "45°" means ±45°.

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

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

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

In the example shown in FIG. 1, the phase difference member 30 is provided between the absorptive polarizing member 28 and the laminated film 31. An adhesive layer (e.g., a pressure-sensitive adhesive layer) may be used to laminate the various members. For example, the laminated film 31 and the phase difference member 30 are laminated via a pressure-sensitive adhesive layer 41. The phase difference member 30 and the absorptive polarizing member 28 are laminated via a pressure-sensitive adhesive layer 42.

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

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

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

The elastic modulus Er ₁₂₀ of the hard coat layer 31b at 120°C is, for example, 0.1 GPa to 5.0 GPa, and may be 0.1 GPa to 3.0 GPa. The contraction force S (unit: N) of the absorptive polarizing film 28a at 120°C and the product Er ₁₂₀ ·T (GPa·μm) of the elastic modulus Er ₁₂₀ (unit: GPa) and thickness T (unit: μm) of the hard coat layer 31b at 120°C preferably satisfy the relationship Er ₁₂₀ ·T>0.85×S−4.02. By satisfying such a relationship, peeling between members included in the optical laminate can be suppressed. Specifically, peeling between members that may occur when the optical laminate is heated can be suppressed. The optical laminate can be easily deformed by heating, and can be integrated with a curved surface of a lens, for example, to improve the visibility and reduce the weight of VR goggles. Therefore, by satisfying the above-mentioned relationship, the optical laminate can be well integrated with a curved surface of a lens, etc. The thin lens can be a curved lens, for example.

The elastic modulus Er of the hard coat layer 31b at room temperature is preferably 5 GPa or more, and 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. In addition, by having such a hard coat layer, the function of the functional layer described below (e.g., anti-reflection function) can be ensured. The elastic modulus Er of the hard coat layer at room temperature is, for example, 10 GPa or less.

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

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

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

<Absorptive polarizing film>
The absorptive polarizing member includes an absorptive polarizing film. The crossed transmittance (Tc) of the absorptive polarizing member (absorptive polarizing film) is preferably 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The single transmittance (Ts) of the absorptive polarizing member (absorptive polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing member (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.8% or more.

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

A method for producing an absorptive polarizing film made of a resin film includes, for example, forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) and a halide on one side of a long thermoplastic resin substrate to form a laminate, and subjecting the laminate to an auxiliary air-stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process in which the laminate is heated while being transported in the longitudinal direction to shrink the laminate by 2% or more in the width direction, in that order. The thickness of the resulting absorptive polarizing film can be controlled, for example, by adjusting the stretching ratio in the underwater stretching process. The shrinkage force of the resulting absorptive polarizing film can be controlled, for example, by adjusting the stretching ratio and/or the stretching temperature in the underwater stretching process.

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

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

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

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

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 to plasticize the substrate. As a result, the stretching stress can be significantly reduced, and the substrate can be stretched at a high ratio. 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, which leads to a deterioration in the appearance of the resulting absorptive polarizing film. It is also possible to prevent the substrate from breaking during underwater stretching, and the PVA-based resin layer from peeling off from the substrate. The water absorption rate of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material. The water absorption rate is a value determined in accordance with JIS K 7209.

The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 120°C or less. By using such a thermoplastic resin substrate, the stretchability of the laminate can be sufficiently ensured while suppressing the crystallization of the PVA-based resin layer. Considering the plasticization of the thermoplastic resin substrate by water and the good underwater stretching, the Tg is more preferably 100°C or less, and even more preferably 90°C or less. On the other hand, the Tg of the thermoplastic resin substrate is preferably 60°C or more. By using such a thermoplastic resin substrate, defects such as deformation of the substrate (e.g., generation of unevenness, sagging, wrinkles, etc.) when the coating liquid is applied and dried can be prevented, and a laminate can be produced well. In addition, the stretching of the PVA-based resin layer can be performed at a suitable temperature (e.g., about 60°C). The glass transition temperature of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material and heating it using a crystallizing material. The glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121.

Examples of thermoplastic resins include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins of these. Of these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are preferably used.

In one embodiment, amorphous (uncrystallized) polyethylene terephthalate resins are preferably used. Among them, amorphous (hardly crystallized) polyethylene terephthalate resins are preferably used. Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acids, and copolymers further containing cyclohexanedimethanol or diethylene glycol as glycols.

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

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

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

The above-mentioned PVA-based resins include, for example, polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymers are obtained by saponifying ethylene-vinyl acetate copolymers. The saponification degree of the PVA-based resin is, for example, 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined in accordance with JIS K 6726-1994. The average polymerization degree of the PVA-based resin is, for example, 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average polymerization degree can be determined in accordance with JIS K 6726-1994. Examples of the above-mentioned halides include iodides such as potassium iodide, sodium iodide, and lithium iodide, and sodium chloride. Among these, potassium iodide is preferably used.

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

The orientation of the polyvinyl alcohol molecules in the PVA-based resin can be increased by stretching the PVA-based resin layer, but when the stretched PVA-based resin layer is immersed in a liquid containing water, the orientation of the polyvinyl alcohol molecules may be disturbed and the orientation may decrease. When a laminate of a thermoplastic resin substrate and a PVA-based resin layer is stretched in boric acid water at a relatively high temperature to stabilize the stretching of the thermoplastic resin substrate, the tendency for the orientation to decrease is remarkable. In contrast, by high-temperature stretching (auxiliary stretching) in air before stretching a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate in boric acid water, crystallization of the PVA-based resin in the PVA-based resin layer of the laminate after auxiliary stretching can be promoted. As a result, when the PVA-based resin layer is immersed in a liquid, the disturbance of the orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained by immersing the laminate in a liquid through processes such as dyeing and underwater stretching.

In order to obtain high optical properties, a two-stage stretching method can be selected that combines air stretching (auxiliary stretching) and stretching in boric acid water. By introducing auxiliary stretching, it is possible to stretch while suppressing crystallization of the thermoplastic resin substrate, which solves the problem of reduced stretchability due to excessive crystallization of the thermoplastic resin substrate in the subsequent stretching in boric acid water, and the laminate can be stretched at a high magnification. In addition, when applying a PVA-based resin to a thermoplastic resin substrate, it is necessary to lower the application temperature compared to, for example, applying a PVA-based resin to a metal drum in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate. As a result, the crystallization of the PVA-based resin becomes relatively low, which can cause a problem that sufficient optical properties cannot be obtained. In contrast, by introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA-based resin even when applying a PVA-based resin to a thermoplastic resin substrate, and it is possible to achieve high optical properties. At the same time, by increasing the orientation of the PVA-based resin in advance, problems such as a decrease in the orientation of the PVA-based resin or dissolution can be prevented when the resin is immersed in water during subsequent dyeing or stretching processes, making it possible to achieve high optical properties.

The method of the in-air auxiliary stretching may be fixed-end stretching (e.g., stretching using a tenter stretching machine) or free-end stretching (e.g., uniaxial 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.

The stretching ratio of the auxiliary air stretching is preferably 2.0 to 3.5 times. The auxiliary air 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 in each stage. The stretching direction in the auxiliary air stretching is preferably approximately the same as the stretching direction in the underwater stretching.

The stretching temperature of the auxiliary air stretching is preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably equal to or higher than Tg+10°C of the thermoplastic resin substrate, and even more preferably equal to or higher than Tg+15°C 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 progressing rapidly, and defects due to crystallization (for example, preventing the orientation of the PVA-based resin layer due to stretching) can be suppressed. The crystallization index of the PVA-based resin after the auxiliary air stretching is preferably 1.3 to 1.8, more preferably 1.4 to 1.7. The crystallization index of the PVA-based resin can be measured by the ATR method using a Fourier transform infrared spectrophotometer. Specifically, the measurement is performed using polarized light as the measurement light, and the crystallization index is calculated according to the following formula using the intensities of 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.

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

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

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

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

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

　After the dyeing process, a crosslinking process may be performed before the underwater stretching process. The crosslinking process is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. The crosslinking process imparts water resistance to the PVA-based resin layer, and prevents the orientation of the PVA from decreasing when the layer is immersed in high-temperature water during the subsequent underwater stretching process. The concentration of the aqueous boric acid solution used in the crosslinking process is preferably 1 to 5 parts by weight per 100 parts by weight of water. In addition, when the crosslinking process is performed after the dyeing process, it is preferable to further add an iodide. By adding an iodide, it is possible to suppress the elution of iodine adsorbed to the PVA-based resin layer. The amount of iodide added is preferably 1 to 5 parts by weight per 100 parts by weight of water. Specific examples of iodides are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably 20°C to 50°C.

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

Any appropriate method can be used for stretching the laminate. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method in which the laminate is uniaxially stretched by passing it between rolls with different peripheral speeds). Free-end stretching is preferably selected. The stretching of the laminate may be performed in one stage or in multiple stages. When it is performed in multiple stages, the stretch ratio of the laminate described below is the product of the stretch ratios in each stage.

The underwater stretching is preferably performed by immersing the laminate in an aqueous solution of boric acid (stretching in boric acid water). By using an aqueous solution of boric acid as the stretching bath, it is possible to impart to the PVA-based resin layer the rigidity required to withstand the tension applied during stretching, and the water resistance required to prevent dissolution in water. Specifically, boric acid can generate tetrahydroxyborate anions in the aqueous solution and crosslink with the PVA-based resin through hydrogen bonds. As a result, the PVA-based resin layer is imparted with rigidity and water resistance, allowing it to be stretched well, and an absorptive polarizing film with excellent optical properties can be produced.

The boric acid aqueous solution is preferably obtained by dissolving boric acid and/or a borate in water, which is a solvent. The boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 7 parts by weight, and even more preferably 3 to 6 parts by weight, per 100 parts by weight of water. By making the boric acid concentration 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and an absorptive polarizing film with higher characteristics can be produced. In addition to boric acid or a borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.

It is preferable to add iodide to the stretching bath (boric acid aqueous solution). Adding iodide can suppress the elution of iodine adsorbed in the PVA-based resin layer. Specific examples of iodide are as described above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of water.

The stretching temperature (liquid temperature of the stretching bath) is preferably 40°C or higher, and more preferably 60°C or higher. At such a temperature, the stretching can be performed satisfactorily. 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 below 40°C, there is a risk that the substrate cannot be stretched satisfactorily, even when 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, and 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 risk that excellent optical properties cannot be obtained. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

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

The drying shrinkage treatment may be performed by zone heating, which heats the entire zone, or by heating the transport roll (using a so-called heating roll). Preferably, both are used. By drying using a heating roll, it is possible to efficiently suppress the heat curl of the laminate and produce an absorptive polarizing film with excellent appearance. Specifically, by drying the laminate in a state where it is aligned with the heating roll, it is possible to efficiently promote the crystallization of the thermoplastic resin substrate and increase the crystallinity, and even at a relatively low drying temperature, it is possible to satisfactorily increase the crystallinity of the thermoplastic resin substrate. As a result, the rigidity of the thermoplastic resin substrate increases and it becomes in a state where it can withstand the shrinkage of the PVA-based resin layer due to drying, and curling is suppressed. In addition, by using a heating roll, the laminate can be dried while being maintained in a flat state, so that not only curling but also the occurrence of wrinkles can be suppressed. At this time, the laminate can be shrunk in the width direction by the drying shrinkage treatment, thereby improving the optical properties. This is because the orientation of the PVA and the PVA/iodine complex can be effectively increased. The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment is preferably 1% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using a heated roll, the laminate can be continuously shrunk in the width direction while being transported, achieving high productivity.

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

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

Preferably, after the underwater stretching process, a cleaning process is performed before the drying shrinkage process. The cleaning process is performed, for example, by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

<Protective layer>
The protective layer that may be included in the absorptive polarizing member may be composed of any suitable film. Examples of materials that are the main components of the film that constitutes 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, acetate-based, and other resins. Among these, (meth)acrylic resins and cycloolefin-based resins are preferably used. By adopting these resins, a protective layer with excellent smoothness can be formed by extrusion molding, and an absorptive polarizing member with excellent smoothness can be obtained. In addition, the protective layer composed of a cycloolefin-based resin may have excellent durability of birefringence characteristics (for example, little change over time).

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

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

The thickness of the adhesive layer that may be included in the absorptive 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 absorptive polarizing member with excellent smoothness can be obtained. From the viewpoint of adhesion, etc., the thickness of the adhesive layer that may be included in the absorptive polarizing member is, for example, 0.01 μm or more, and preferably 0.5 μm or more.

<Laminated film>
The laminated film typically includes a substrate. The substrate has a thickness of preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm. The substrate has a surface smoothness of preferably 0.7 arcmin or less, more preferably 0.6 arcmin or less, and even more preferably 0.5 arcmin or less.

The substrate may be made of any suitable film. Examples of materials that are the main components of the film that constitutes the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based such as polynorbornene, polyolefin-based, (meth)acrylic, acetate-based, and other resins. Here, (meth)acrylic refers to acrylic and/or methacrylic. In one embodiment, the substrate is preferably made of a (meth)acrylic resin. By using a (meth)acrylic resin, a substrate with excellent smoothness (for example, satisfying the above-mentioned surface smoothness) can be formed by extrusion molding. A laminated film with excellent smoothness can then be obtained.

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

As described above, the surface treatment layer includes a hard coat layer. The hard coat layer is typically formed by applying a hard coat layer-forming material to a substrate and curing the applied layer. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. Examples of the curing mechanism of the curable compound include a thermosetting type and a photocurable type. Examples of the curable compound include a monomer, an oligomer, and a prepolymer. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. Examples of the polyfunctional monomer or oligomer include a monomer or oligomer having two or more (meth)acryloyl groups, a urethane (meth)acrylate or an oligomer of a urethane (meth)acrylate, an epoxy-based monomer or oligomer, and a silicone-based monomer or oligomer.

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

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

<Retardation Member>
The retardation member is made of any suitable material that can satisfy the desired optical characteristics. The retardation member (e.g., λ/4 member) can be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound.

The resins contained in the resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, acrylic-based resins, and the like. These resins may be used alone or in combination. Methods for combining include blending and copolymerization, for example. When the phase difference member exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter sometimes simply referred to as a polycarbonate-based resin) may be suitably used.

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

The thickness of the phase difference member made of a stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

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

The orientation solidified layer of the liquid crystal compound (liquid crystal orientation solidified layer) can be formed by performing an orientation treatment on the surface of a specified substrate, applying a coating liquid containing a liquid crystal compound to the surface to orient the liquid crystal compound in a direction corresponding to the orientation treatment, and fixing the orientation state. Any appropriate orientation treatment can be adopted as the orientation treatment. Specific examples include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of chemical orientation treatment include oblique deposition method and photo-alignment treatment. Any appropriate conditions can be adopted as the processing conditions for the various orientation treatments depending on the purpose.

The alignment of liquid crystal compounds is achieved by treating them at a temperature that exhibits a liquid crystal phase according to the type of liquid crystal compound. By carrying out such temperature treatment, the liquid crystal compounds take on a liquid crystal state, and the liquid crystal compounds are aligned according to the alignment treatment direction of the substrate surface.

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

Any suitable liquid crystal polymer and/or liquid crystal monomer can be used as the liquid crystal compound. The liquid crystal polymer and the liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for producing a liquid crystal alignment solidified layer are described in, for example, JP 2006-163343 A, JP 2006-178389 A, and WO 2018/123551 A. The descriptions in these publications are incorporated herein by reference.

The thickness of the phase difference member composed of the liquid crystal alignment solidified layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm.

<Adhesive Layer>
The thickness of the adhesive layer used for laminating each of the above members can be set to any appropriate thickness. The thickness of each of the adhesive layers used for laminating each of the above members is, for example, 15 μm or less, preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. With such a thickness, the smoothness can be excellent. On the other hand, the thickness of each of the adhesive layers used for laminating each of 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 absorbing polarizing member 28 is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less. Specifically, the laminated film 31 and the phase difference member 30 can be laminated via an adhesive layer having a thickness of preferably 12 μm or less. In addition, the thickness of the adhesive layer disposed between the absorbing polarizing member 28 and the phase difference member 30 is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 7 μm or less.

The adhesive layer may be made of any suitable adhesive. As a specific example, the adhesive layer may be made of an adhesive having an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, or the like as a base polymer. By adjusting the type, number, combination, and compounding ratio of the monomers constituting the base polymer of the adhesive, as well as the compounding amount of the crosslinking agent, the reaction temperature, the reaction time, etc., an adhesive having the 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 types. An acrylic polymer is preferably used as the base polymer. Specifically, the adhesive layer is preferably made of an acrylic adhesive.

Any other suitable optical member may be laminated on the absorptive polarizing member 28 of the optical laminate 1. The optical laminate 1 may then be used in any suitable display. The optical laminate 1 may be suitably used in, for example, VR goggles.

[Display system]
FIG. 2 is a schematic diagram showing an example of a general configuration of a display system of VR goggles, and shows the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing member 14, a first lens unit 16, a half mirror 18, a first λ/4 member 20, a second λ/4 member 22, and a second lens unit 24. The reflective polarizing member 14 is disposed in front of the display surface 12a side of the display element 12, and can reflect light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflective polarizing member 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first λ/4 member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ/4 member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14.

The half mirror, or the components arranged in front of the first lens section (in the illustrated example, the half mirror 18, the first lens section 16, the second λ/4 member 22, the reflective polarizing member 14, and the second lens section 24) may be collectively referred to as the lens section (lens section 4).

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

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

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

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 integrally formed with the first lens portion 16.

The first circularly polarized light emitted from the first λ/4 member 20 passes through the half mirror 18 and the first lens portion 16, and is converted into the second linearly polarized light by the second λ/4 member 22. The second linearly polarized light 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.

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

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

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

The in-plane phase difference Re(550) of the first λ/4 member 20 is, for example, 100 nm to 190 nm, and may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ/4 member 20 preferably exhibits an inverse dispersion wavelength characteristic in which the phase difference value increases according to the wavelength of the measurement light. The Re(450)/Re(550) of the first λ/4 member 20 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

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

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

The optical laminate according to the embodiment of the present invention may have, for example, a member provided in the display system. The optical laminate may have other members such as an adhesive layer for integrating adjacent members. The thickness of the optical laminate may vary depending on the type and number of members included, but is, for example, 50 μm to 400 μm. The optical laminate may be integrated with, for example, the first lens portion 16 or the second lens portion 24. Typically, the optical laminate may be bonded to the first lens portion 16 or the second lens portion 24, which is the adherend, via an adhesive layer. When bonding (for example, before bonding to the adherend), the optical laminate may be heated. For example, when the adherend has a curved surface, such as the first lens portion 16 shown in FIG. 2, it is preferable to heat the optical laminate. The optical laminate becomes more easily deformed by heating, 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.

FIG. 3 is a schematic cross-sectional view showing an example of a state in which another optical member is laminated on the absorptive polarizing member of the optical laminate shown in FIG. 1. The optical laminate 2 has an absorptive 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 above-mentioned phase difference member, and a laminated film 31. The in-plane phase difference 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 phase difference value increases according to the wavelength of the measurement light. The 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.

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

The optical laminate 2 has a reflective polarizing member 14. The reflective polarizing member 14 is laminated behind the absorptive polarizing member 28 via an adhesive layer 43. 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 approximately 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 approximately parallel to each other. In the optical laminate 2, the absorptive polarizing member 28 is used, for example, from the viewpoint of improving visibility. In addition, by providing a third λ/4 member (phase difference member) 30 in the optical laminate 2, for example, reflection of external light from the second lens portion 24 side can be prevented.

The peel strength of the absorptive polarizing member 28 relative 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, peeling between the members included in the optical laminate can be effectively suppressed.

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

FIG. 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure 14a has alternating layers A having birefringence and layers 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, and the refractive index difference between layers A and 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 layers A and B in the x-axis direction is preferably 0.2 to 0.3.

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

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

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

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

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.

The optical laminate 2 has a second λ/4 member 22. The second λ/4 member 22 is laminated to the reflective polarizing member 14 via an adhesive layer 44.

The second λ/4 member 22 is formed of any appropriate material that can satisfy the above characteristics. The second λ/4 member 22 can be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound. The second λ/4 member 22 composed of a stretched resin film or an oriented and solidified layer of a liquid crystal compound can be described in the same manner as the phase difference member (λ/4 member) described above. The second λ/4 member and the third λ/4 member may be members having the same configuration (e.g., forming material, thickness, optical properties, etc.) or may be members having different configurations.

In addition to the second λ/4 member 22, the optical laminate 2 has another phase difference 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 located forward of the member 23 exhibiting the relationship nz>nx≧ny. The member 23 exhibiting the relationship nz>nx≧ny is laminated to the second λ/4 member 22 via an adhesive layer 52.

The phase difference Rth(550) in the thickness direction of the member whose refractive index characteristic shows 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 phase difference member 23 is a so-called positive C plate whose refractive index shows the relationship nx=ny. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. For example, it also includes the case where Re(550) is less than 10 nm. In another embodiment, the other phase difference member 23 has a refractive index that shows the relationship nx>ny. In this case, the in-plane phase difference Re(550) of the other phase difference member 23 is preferably 10 nm to 150 nm, and more preferably 10 nm to 80 nm.

The member whose refractive index characteristic shows the relationship nz>nx≧ny may be formed of any appropriate material. It is preferably composed of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods of forming the film include the liquid crystal compounds and forming methods described in [0020] to [0042] of JP 2002-333642 A. In this case, the thickness is preferably 0.1 μm to 5 μm, and more preferably 0.5 μm to 4 μm.

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

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

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The thickness, shrinkage force, elastic modulus, peeling force, retardation value, and surface smoothness are values measured by the following measurement methods. Furthermore, unless otherwise specified, "parts" and "%" are based on weight.
<Thickness>
The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"), and the thickness of more than 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C").
<Contraction force>
The measurement object was punched out using a blade having a size of 100 mm (length) x 25 mm (width) to obtain a rectangular measurement sample. The punching was performed so that the length direction was aligned with the absorption axis direction or the reflection axis direction of the measurement object.
In an autograph equipped with a thermostatic bath ("AG-Xplus" manufactured by Shimadzu Corporation), the obtained measurement sample was chucked with a jig within a range of 5 mm from each end in the longitudinal direction without being pulled, and placed in an environment at a temperature of 120°C, and the contraction force (N) generated between the 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 length x 20 mm width with a cutter to obtain a test piece. The cut surface of the obtained test piece was cut using a microtome, and after placing it in an environment of 23 ° C. and 55% RH for 3 hours (humidification), it was measured by a nanoindenter. For the measurement by the nanoindenter, a "Triboindenter" manufactured by Hysitron Inc. was used, and a Berkovich (triangular pyramid) was used as the indenter. Under the following conditions, the hard coat layer of the laminated film was pressed from the cut surface to measure the load-displacement curve, and the elastic modulus (GPa) was calculated.
(Measurement conditions)
Measurement method: Single indentation measurement Measurement temperature: Room temperature and 120°C
Indentation speed: 10 nm/sec Indentation depth: 100 nm
<Peeling Force>
A sample cut out from the measurement object to a size of 25 mm in width and 50 mm in length was left in an environment of 23°C and 50% RH for 30 minutes or more, and then the peel force (N/25 mm) was measured when peeled in the length direction at a peel speed of 300 mm/min and a peel angle of 180° using a universal tensile tester. The measurement was performed in an environment of 23°C and 50% RH.
<Phase difference value>
The phase difference value at each wavelength at 23° C. was measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan").
<Surface smoothness>
The surface smoothness was measured using a scanning white light interferometer (manufactured by Zygo, product name "NewView9000"). Specifically, the measurement sample was placed on a measurement table with a vibration-proof table, interference fringes were generated using a single white LED illumination, and an interference objective lens (1.4x) 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 within a 12.4 mm square field of view.
When the measurement object is an adhesive layer, the adhesive layer is attached to a microslide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200200"), and the smoothness of the exposed adhesive surface is measured. When the measurement object is a film, an acrylic adhesive layer with a thickness of 5 μm and little unevenness is formed on the glass, and the film to be measured is laminated on this adhesive surface so that foreign matter, air bubbles, and deformation lines do not enter, and the smoothness of the surface opposite to the adhesive layer is measured. The surface smoothness of the acrylic adhesive layer with a thickness of 5 μm and little unevenness was 0.30 arcmin.
For the analysis, the surface smoothness (unit: arcmin) was defined as a value obtained by multiplying the angle index "slope magnitude RMS" (corresponding to 2σ).

[Production Example 1-1]
(Formation of Absorptive Polarizing Film)
As the thermoplastic resin substrate, a long amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) was used, which had a water absorption rate of 0.75% and a Tg of about 75° C. One side of the resin substrate was subjected to a corona treatment.
A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4,200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, product name "GOHSENEX Z410") in a ratio of 9:1, and dissolving the resultant in water.
The above PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate.
The resulting laminate was uniaxially stretched at its free end to 2.4 times its original size in the machine direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130° C. (auxiliary air stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment).
Next, the laminate was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30° C. for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizing film would be 43.0% (dyeing treatment).
Next, the laminate was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (crosslinking treatment).
Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4 wt %, potassium iodide concentration: 5 wt %) at a liquid temperature of 70° C., and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds so that the total stretch ratio was 5.5 times (stretch ratio by underwater stretching was 2.3 times) (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven maintained at 90° C., the laminate was brought into contact with a SUS heated roll having a surface temperature maintained at 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.
In this manner, an absorptive polarizing film having a thickness of 5 μm and a shrinkage force of 6.5 N was formed on the resin substrate.

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

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

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

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

[Production Example 2-1]
(Preparation of Laminated Film)
The following hard coat layer forming material 1 was applied to an acrylic film (thickness 40 μm, surface smoothness 0.45 arcmin) having a lactone ring structure, and heated at 90° C. for 1 minute. After heating, the coating layer was irradiated with ultraviolet light from a high-pressure mercury lamp at an integrated light quantity of 300 mJ/ ^cm2 to harden the coating layer, thereby forming a hard coat layer with a thickness of 4 μm and 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 solution A for forming an antireflection layer was applied onto the hard coat layer using a wire bar, and the applied coating solution was heated at 80° C. for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet light from a high-pressure mercury lamp at an integrated light quantity of 300 mJ/cm ² to cure the coating film, forming an antireflection layer A having a thickness of 140 nm.
Next, the following coating solution B for forming an antireflection layer was applied onto the antireflection layer A with a wire bar, and the applied coating solution was heated at 80° C. for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet rays from a high-pressure mercury lamp at an integrated light quantity of 300 mJ/ ^cm2 to cure the coating film, thereby forming an antireflection layer B with a thickness of 105 nm.
In this way, a laminated film (thickness: 44 μm) was obtained.

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

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

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

[Production Example 2-2]
(Preparation 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 hard coat layer forming material 2 described below.

(Hard Coat Layer Forming Material 2)
A hard coat layer-forming material 2 was prepared by mixing 40 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 40 parts of a multifunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100") and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan KK, "Irgacure 907") and diluting with methyl isobutyl ketone to a solids concentration of 50%.

[Production Example 2-3]
(Preparation 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 hard coat layer forming material 3 described below.

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

[Production Example 2-4]
(Preparation 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 hard coat layer-forming material 4 described below.

(Hard Coat Layer Forming Material 4)
20 parts of a urethane acrylic oligomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Oligo UA-53H"), 60 parts of a multifunctional acrylate mainly composed of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #300"), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part of a leveling agent (manufactured by DIC Corporation, "GRANDIC PC4100") and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan KK, "Irgacure 907") were mixed and diluted with methyl isobutyl ketone to a solids concentration of 50%, to prepare hard coat layer forming material 4.

[Production Example 3]
(Fabrication of λ/4 Members)
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 the mixture was heated to 60°C and stirred to dissolve. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 parts of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added and further stirred 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 having a thickness of 0.7 mm by spin coating, dried at 100°C for 10 minutes, and then baked 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 cooling the obtained coating film to room temperature, a high-pressure mercury lamp was used to irradiate ultraviolet light at an intensity of 30 mW/ ^cm2 for 30 seconds to obtain a liquid crystal alignment solidified layer having a thickness of 3 μm. The obtained liquid crystal alignment solidified layer had an in-plane retardation Re(550) of 140 nm, Re(450)/Re(550) of 0.851, and showed reverse dispersion wavelength characteristics.

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

[Production Example 5]
(Formation of Pressure-Sensitive 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-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. Furthermore, 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 atmosphere in the flask with nitrogen. The liquid temperature in the flask was kept at about 55°C, and a polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 1.78 million.
The acrylic polymer solution was applied to the substrate film, and the resulting coating film on the substrate film was dried in an oven to form a pressure-sensitive adhesive layer having a thickness of 5 μm and a surface smoothness of 0.30 arcmin.

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

The resin substrate was peeled off from the absorptive polarizing member, and the λ/4 member of Production Example 3 was attached to the absorptive polarizing film via the pressure-sensitive adhesive layer of Production Example 5 so that the absorption axis of the absorptive polarizing film and the slow axis of the λ/4 member formed an angle of 45°.
Next, the laminated film (acrylic film having a hard coat layer and an antireflection layer formed thereon) of Production Example 2 was attached to the λ/4 member via the pressure-sensitive adhesive layer of Production Example 5. Here, the laminated film was attached so that the acrylic film was positioned on the λ/4 member side.

A reflective polarizing film ("APCF" manufactured by Nitto Denko Corporation, contraction force 8 N) was attached to the acrylic film of the absorptive polarizing member via a 9 μm thick adhesive layer, in such a manner that the reflection axis of the reflective polarizing film and the absorption axis of the absorptive 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 attached to the reflective polarizing film in this order via the adhesive layer of Production Example 5. Here, the reflective polarizing film was attached so that the reflection axis (absorption axis of the absorptive polarizing film) of the reflective polarizing film and the slow axis of the λ/4 member formed an angle of 45°. The λ/4 member and the positive C plate were attached to each other using an ultraviolet-curing adhesive (thickness after curing: 1 μm).
Next, a pressure-sensitive adhesive layer having a thickness of 50 μm was provided on the positive C plate to obtain an optical laminate.

In the above Production Example 6, the reliability of the optical laminate obtained by combining the absorptive polarizing films obtained in the above Production Examples 1-1 to 1-5 and the laminate films obtained in the above Production Examples 2-1 to 2-4 was evaluated by the following method. The evaluation results are shown in Table 1. Regarding the reliability evaluation results, the relationship between the contraction force S (unit: N) of the absorptive polarizing film at 120° C. and the product Er ₁₂₀ ·T (GPa·μm) of the elastic modulus Er ₁₂₀ (unit: GPa) and thickness T (unit: μm) of the hard coat layer at 120° C. is shown in FIG. 5. In FIG. 5, the good evaluation results are plotted with white circles, and the bad evaluation results are plotted with black circles.
<Reliability evaluation>
The obtained optical laminate was bonded to a non-alkali glass plate having a flat surface, and then the plate was placed in an environment at a temperature of −40° C. for 30 minutes using a thermal shock device (manufactured by Espec Corp., “TSA-303EL-W”), and then placed in an environment at a temperature of 85° C. for 30 minutes. This operation was repeated a total of 100 times to perform a heat cycle test, and then it was confirmed using a differential interference microscope whether peeling occurred in the optical laminate. In the heat cycle test, the time required for heating and cooling was 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. Poor: peeling occurred in a region 100 μm or more from the end face of the optical laminate.

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

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

The optical laminate according to the embodiment of the present invention can be used, for example, in displays such as VR goggles.

1 Optical laminate, 2 Optical laminate, 4 Lens section, 10 Display system, 12 Display element, 12a Display surface, 14 Reflective polarizing member, 14a Multilayer structure, 16 First lens section, 18 Half mirror, 20 First λ/4 member, 22 Second λ/4 member, 24 Second lens section, 28 Absorptive polarizing member, 28a Absorptive polarizing film, 28b Protective layer, 30 Retardation 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 (12)

A laminated film having a substrate and a hard coat layer;
an absorptive polarizing member including an absorptive polarizing film;
the contraction force S (unit: N) of the absorptive polarizing film at 120° C. and the product Er ₁₂₀ ·T (GPa·μm) of the elastic modulus Er 120 (unit: GPa) and thickness T (unit: μm) of the hard coat layer at _{120° C. satisfy the relationship Er 120 ·} T>0.85×S−4.02;
Optical laminate. The laminated film, the absorptive polarizing member, and another optical member are provided in this order,
The absorptive polarizing member and the other optical member are laminated via a pressure-sensitive adhesive layer.
The optical laminate according to claim 1 . The optical laminate according to claim 2, wherein the other optical component is a reflective polarizing component. The optical laminate according to claim 2, wherein the peel strength of the absorptive polarizing member against the adhesive layer is 2 N/25 mm or more. The optical laminate of claim 1, comprising a phase difference member disposed between the laminate film and the absorptive polarizing member. The optical laminate of claim 1, wherein the absorptive polarizing member includes a protective layer. a pressure-sensitive adhesive layer disposed between the laminate film and the absorptive polarizing member;
The thickness of the pressure-sensitive adhesive layer is 12 μm or less.
The optical laminate according to claim 1 . The optical laminate according to claim 1, wherein the hard coat layer has an elastic modulus Er of 5 GPa or more at room temperature. 2. The optical laminate according to claim 1, wherein a ratio Er ₁₂₀ /Er of a modulus of elasticity Er ₁₂₀ of the hard coat layer at 120° C. to a modulus of elasticity Er of the hard coat layer at room temperature is 0.25 or more. 1. A lens unit for use in a display system for displaying an image to a user, comprising:
The optical laminate according to claim 3, which reflects light that is emitted forward from a display surface of a display element that displays an image and passes through a polarizing member and a first λ/4 member;
A first lens portion disposed on an optical path between the display element and the optical laminate;
a half mirror disposed between the display element and the first lens portion, the half mirror transmitting light emitted from the display element and reflecting light reflected by the reflective polarizing member of the optical laminate toward the reflective polarizing member;
A second λ/4 member disposed on an optical path between the half mirror and the optical laminate;
A lens unit comprising: A step of passing light representing an image outputted through the polarizing member and the first λ/4 member through a half mirror and a first lens unit;
A step of passing the light that has passed through the half mirror and the first lens portion through a second λ/4 member;
A step of reflecting the light having passed through the second λ/4 member toward the half mirror by the optical laminate according to claim 3;
A step of allowing light reflected by the reflective polarizing member and the half mirror of the optical laminate to pass through the reflective polarizing member by the second λ/4 member;
A display method comprising: A method for manufacturing a lens portion according to claim 10, comprising the steps of:
Heating the optical laminate to integrate the optical laminate with the first lens portion.
A manufacturing method of the lens portion.

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