JP2024095021A - Optical laminate having surface protective film and manufacturing method of display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical laminate to be applied to a goggle having a display, the optical laminate capable of performing a defect inspection plural times in a state where a surface is protected.

SOLUTION: An optical laminate having a surface protective film includes: an optical laminate including at least one optical member and to be used for a goggle having a display; and a first surface protective film and a second surface protective film laminated outward in this order on one face of the optical laminate. The first surface protective film includes a first substrate and a first adhesive layer laminated on the first substrate. The second surface protective film includes a second substrate and a second adhesive layer laminated on the second substrate. The second adhesive layer is 8 μm thick or more. A peel force P1 of the first surface protective film against the optical laminate and a peel force P2 of the second surface protective film against the first surface protective film satisfy a relation P2/P1≤0.8.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an optical laminate with a surface protective film and a method for manufacturing a display system using the optical laminate with a surface protective film.

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

In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized. In VR goggles, the image displayed on the display panel is enlarged for viewing by the viewer, so the optical laminates used in VR goggles require stricter defect management than the optical laminates used in conventional image display devices.

JP 2021-103286 A

As described above, strict defect management is required for the optical laminate applied to VR goggles, and therefore multiple defect inspections may be performed before the final product is produced, more specifically, before the final assembly process is performed. Meanwhile, it is preferable that the surface of the optical laminate is protected until the final assembly process is performed. Therefore, the main object of the present invention is to provide an optical laminate applied to VR goggles, which can be subjected to multiple defect inspections while the surface is protected.

The inventors of the present invention have conducted studies to solve the above problems, and have come up with the idea that the above problems can be solved by subjecting an optical laminate protected by a surface protective film to a defect inspection, and further protecting the inspection target (i.e., the optical laminate protected by a surface protective film) with another surface protective film. Based on this idea, an optical laminate with a surface protective film in which two surface protective films are laminated was produced and subjected to a defect inspection, and it was found that air bubbles were generated between the two surface protective films, and that these air bubbles may be erroneously detected as defects in the optical laminate. It was also found that when peeling off the outer surface protective film to obtain an optical laminate protected only by the inner surface protective film, the inner surface protective film may also be peeled off together.

In response to the above problems, the inventors discovered that by increasing the thickness of the adhesive layer of the outer surface protection film and adjusting the relationship between the peel strength of the outer surface protection film and the peel strength of the inner surface protection film, it is possible to solve the above problems while avoiding these problems, and thus completed the present invention.

According to one aspect of the present invention, there are provided an optical laminate with a surface protective film according to [1] to [8], and a method for producing a display system according to [9].
[1] An optical laminate with a surface protective film, the optical laminate including at least one optical component and used for goggles with a display, and a first surface protective film and a second surface protective film attached in this order toward the outside to one surface of the optical laminate, wherein the first surface protective film has a first substrate and a first pressure-sensitive adhesive layer laminated to the first substrate, the second surface protective film has a second substrate and a second pressure-sensitive adhesive layer laminated to the second substrate, the second pressure-sensitive adhesive layer has a thickness of 8 μm or more, and a peel force P1 of the first surface protective film to the optical laminate and a peel force P2 of the second surface protective film to the first surface protective film satisfy the relationship P2/P1≦0.8.
[2] The optical laminate with a surface protective film according to [1], wherein the peel strength P2 of the second surface protective film from the first surface protective film is 0.5 N/50 mm or less.
[3] The optical laminate with a surface protective film according to [1] or [2], wherein the first surface protective film and the second surface protective film each have a total light transmittance of 85% or more.
[4] The optical laminate with a surface protective film according to any one of [1] to [3], wherein the ratio (L2/L1) of the total light transmittance L1 of the first surface protective film to the total light transmittance L2 of the second surface protective film is 0.8 to 1.2.
[5] An optical laminate with a surface protective film described in any one of [1] to [4], wherein the optical laminate has (1) an absorptive polarizing member, a first phase difference member, and a protective member, in this order toward the first surface protective film, or (2) a second phase difference member and a protective member, in this order toward the first surface protective film, or (3) a reflective polarizing member and a protective member, in this order toward the first surface protective film.
[6] The optical laminate with a surface protective film according to [5], wherein the protective member includes a surface treatment layer, and the first surface protective film is attached to the surface treatment layer.
[7] The optical laminate with a surface protective film according to [6], wherein the surface treatment layer includes an antireflection layer, and the first surface protective film is attached to the antireflection layer.
[8] The optical laminate with a surface protective film described in any one of [1] to [7], wherein the optical laminate has a pressure-sensitive adhesive layer on the side opposite to the side to which the first surface protective film and the second surface protective film are attached.
[9] A manufacturing method for a display system, comprising the steps of, in this order: inspecting an optical laminate with a surface protective film described in any one of [1] to [8] for defects; attaching another member to the side of the optical laminate with a surface protective film opposite to the side to which the first surface protective film and the second surface protective film are attached, to obtain a secondary laminate with a surface protective film; peeling the second surface protective film from the secondary laminate with a surface protective film; inspecting the secondary laminate with a surface protective film for defects; and peeling the first surface protective film from the secondary laminate with a surface protective film to obtain a secondary laminate, wherein the display system is goggles with a display.

The optical laminate with surface protective film according to the embodiment of the present invention can be inspected for defects multiple times while the surface of the optical laminate is protected, while suppressing the generation of air bubbles between the surface protective films (resulting in erroneous detection of defects) and problems with peeling failure.

FIG. 1 is a schematic cross-sectional view of an optical laminate with a surface protective film according to one embodiment of the present invention. 1 is a schematic diagram showing a schematic configuration of a display system in which an optical laminate according to an embodiment of the present invention can be used. 3 is a schematic cross-sectional view showing an example of an optical laminate that can be used in the display system shown in FIG. 2. 3 is a schematic cross-sectional view showing an example of an optical laminate that can be used in the display system shown in FIG. 2. 3 is a schematic cross-sectional view showing an example of an optical laminate that can be used in the display system shown in FIG. 2. 1A-1C are schematic diagrams illustrating a method for manufacturing a display system according to one embodiment of the present invention. This is a figure continuing from Figure 6A. This is a continuation of Figure 6B. This is a figure continuing from Figure 6C. This is a continuation of Figure 6D.

Below, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, in order to make the description clearer, the drawings may show the width, thickness, shape, etc. of each part more diagrammatically than the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

(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 retardation (Re)
"Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23° C. Re(λ) is calculated by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) 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° clockwise or counterclockwise. In this specification, "substantially parallel" includes the case where the angle is within a range of 0°±10°, for example, within a range of 0°±5°, preferably within a range of 0°±3°, more preferably within a range of 0°±1°, and "substantially perpendicular" includes the case where the angle is within a range of 90°±10°, for example, within a range of 90°±5°, preferably within a range of 90°±3°, more preferably within a range of 90°±1°.

A. Optical laminate with surface protective film FIG. 1 is a schematic cross-sectional view of an optical laminate with a surface protective film according to one embodiment of the present invention. The optical laminate with a surface protective film 200 includes an optical laminate 100 that includes at least one optical member and is used for goggles with a display, and a first surface protective film 110 and a second surface protective film 120 that are attached in this order outward to one surface of the optical laminate 100. The first surface protective film 110 has a first substrate 112 and a first adhesive layer 114 laminated on the first substrate 112. The second surface protective film 120 has a second substrate 122 and a second adhesive layer 124 laminated on the second substrate 122. The first surface protective film 110 and the second surface protective film 120 are process members that are temporarily attached (temporarily attached) to the optical laminate 100, and are peeled off and removed when the optical laminate 100 is used. In this specification, the first surface protective film may be referred to as an inner surface protective film, and the second surface protective film may be referred to as an outer surface protective film.

The optical laminate with a surface protective film can be produced by adhering a first surface protective film and a second surface protective film to one surface of the optical laminate. The first surface protective film and the second surface protective film may be adhered in this order to one surface of the optical laminate, or a laminate of the first surface protective film and the second surface protective film may be adhered to the optical laminate. The first surface protective film and the second surface protective film may each have their pressure-sensitive adhesive layer side surface protected by a release liner until they are used.

A-1. First surface protective film (inner surface protective film)
As shown in FIG. 1, a first surface protective film 110 has a first substrate 112 and a first pressure-sensitive adhesive layer 114 laminated on the first substrate 112 .

The total light transmittance L1 of the first surface protective film is, for example, 85% or more, preferably 88% or more, and more preferably 90% or more. If the total light transmittance L1 is within the above range, precise defect inspection can be suitably performed even when the surface of the optical laminate is protected by the first surface protective film.

The haze of the first surface protective film is, for example, 5% or less, preferably 4% or less, more preferably 3% or less, and typically 0.05% or more. If the haze is within the above range, precise defect inspection can be suitably performed even when the surface of the optical laminate is protected by the first surface protective film. A surface protective film having a haze in the above range can be obtained, for example, by using a low-haze substrate and/or adhesive layer.

The peeling force P1 of the first surface protective film against the optical laminate (peel speed: 300 mm/min, peel angle: 180°) is, for example, 1.0 N/50 mm or less, preferably 0.5 N/50 mm or less, more preferably 0.3 N/50 mm or less, and, for example, 0.05 N/50 mm or more, preferably 0.08 N/50 mm or more, more preferably 0.10 N/50 mm or more. If the peeling force P1 is within the above range, it is possible to suitably prevent the problem of poor peeling in which the first surface protective film peels off together with the second surface protective film when the second surface protective film is peeled off.

<First substrate>
The first substrate is formed of any suitable resin film that can be used as a surface protective film. Specific examples of materials that are the main components of the resin film include cycloolefin (COP)-based materials such as polynorbornene-based materials, polyester-based materials such as polyethylene terephthalate (PET)-based materials, cellulose-based materials such as triacetyl cellulose (TAC), polycarbonate (PC)-based materials, (meth)acrylic-based materials, polyvinyl alcohol-based materials, polyamide-based materials, polyimide-based materials, polyethersulfone-based materials, polysulfone-based materials, polystyrene-based materials, polyolefin-based materials, and acetate-based materials. In addition, examples of the resin film include thermosetting resins or ultraviolet-curing resins such as (meth)acrylic-based materials, urethane-based materials, (meth)acrylic urethane-based materials, epoxy-based materials, and silicone-based materials. The term "(meth)acrylic resin" refers to acrylic resins and/or methacrylic resins. In addition, examples of the resin film include glassy polymers such as siloxane-based polymers. In addition, the polymer films described in JP 2001-343529 A (WO01/37007) can also be used. As the material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above-mentioned resin composition. The materials for the resin film can be used alone or in combination.

The first substrate preferably contains at least one transparent resin selected from the group consisting of COP, PET, TAC, PC and (meth)acrylic, more preferably contains at least one transparent resin selected from the group consisting of COP, PET, PC and (meth)acrylic, and even more preferably contains at least one transparent resin selected from the group consisting of COP, PET and PC. When the first substrate contains the above transparent resin, false detections caused by the surface protection film during defect inspection can be more stably reduced.

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

The thickness of the first substrate is typically 5 μm or more, preferably 20 μm or more, and typically 200 μm or less, preferably 100 μm or less.

<First Pressure-Sensitive Adhesive Layer>
The first pressure-sensitive adhesive layer is composed of any suitable pressure-sensitive adhesive. The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer typically contains at least one pressure-sensitive adhesive selected from the group consisting of (meth)acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, and silicone pressure-sensitive adhesives. Preferably, the first pressure-sensitive adhesive layer contains a (meth)acrylic pressure-sensitive adhesive.

The (meth)acrylic adhesive contains a polymer (hereinafter referred to as a (meth)acrylic polymer) of a monomer component whose main component is alkyl (meth)acrylate. In other words, the (meth)acrylic polymer contains structural units derived from alkyl (meth)acrylate. The content of structural units derived from alkyl (meth)acrylate in the (meth)acrylic polymer is typically 50% by mass or more, preferably 80% by mass or more, more preferably 93% by mass or more, and is, for example, 100% by mass or less, preferably 98% by mass or less.

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

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

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

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

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

The (meth)acrylic adhesive may also contain a crosslinking agent. Representative examples of the crosslinking agent include organic crosslinking agents and polyfunctional metal chelates, and preferably organic crosslinking agents. Examples of the organic crosslinking agent include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents, and more preferably isocyanate crosslinking agents. When the adhesive contains a crosslinking agent, the content of the crosslinking agent is usually 0.01 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the (meth)acrylic polymer.

The above adhesives ((meth)acrylic adhesives, urethane adhesives, and silicone adhesives) may contain various additives in appropriate proportions as necessary. By adjusting the composition of the base polymer (e.g., type and content of monomer, type and content of crosslinking agent, etc.), molecular weight of the base polymer, type or content of additives, etc., it is possible to obtain an adhesive layer having the desired adhesion to the adherend.

Additives include polymerization initiators, solvents, polymerization catalysts, crosslinking catalysts, silane coupling agents, tackifiers, plasticizers, softeners, anti-degradation agents, fillers, colorants (pigments, dyes, etc.), light stabilizers, UV absorbers, antioxidants, surfactants, antistatic agents, chain transfer agents, etc.

The thickness of the first adhesive layer is, for example, 10 μm or more, preferably 12 μm or more, and, for example, 40 μm or less, preferably 30 μm or less, more preferably 25 μm or less. When the first adhesive layer has the above thickness, good protection for the optical laminate can be achieved.

In one embodiment, the ratio (T1/T2) of the thickness T1 of the first pressure-sensitive adhesive layer to the thickness T2 of the second pressure-sensitive adhesive layer of the second surface protective film is, for example, 2 or less, preferably 1.8 or less, more preferably 1.5 or less, even more preferably 1.2 or less, even more preferably 1 or less, and particularly preferably 0.8 or less, and is, for example, 0.1 or more, preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and even more preferably 0.5 or more. If the ratio (T1/T2) is within the above range, the generation of air bubbles between the first surface protective film and the second surface protective film and peeling failure can be suitably suppressed. In addition, good protection of the optical laminate can be achieved.

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

A-2. Second surface protective film (outer surface protective film)
As shown in FIG. 1, the second surface protective film 120 has a second substrate 122 and a second pressure-sensitive adhesive layer 124 laminated to the second substrate.

The total light transmittance L2 of the second surface protective film is, for example, 85% or more, preferably 88% or more, and more preferably 90% or more. If the total light transmittance L2 is within the above range, precise defect inspection can be suitably performed even when the surface of the optical laminate is protected by the first surface protective film and the second surface protective film.

The ratio (L2/L1) of the total light transmittance L1 of the first surface protective film to the total light transmittance L2 of the second surface protective film is, for example, 0.8 to 1.2, preferably 0.85 to 1.15, and more preferably 0.9 to 1.1. If the ratio (L2/L1) is within the above range, precise defect inspection can be suitably performed even when the surface of the optical laminate is protected by the first surface protective film and the second surface protective film.

The haze of the second surface protective film is, for example, 5% or less, preferably 4% or less, more preferably 3% or less, and typically 0.05% or more. If the haze is within the above range, precise defect inspection can be suitably performed even when the surface of the optical laminate is protected by the first surface protective film and the second surface protective film.

The peeling force P2 of the second surface protective film against the first surface protective film (peel speed: 300 mm/min, peel angle: 180°) is, for example, 0.5 N/50 mm or less, preferably 0.3 N/50 mm or less, more preferably 0.2 N/50 mm or less, and even more preferably 0.1 N/50 mm or less, and is, for example, 0.01 N/50 mm or more, preferably 0.03 N/50 mm or more, and even more preferably 0.05 N/50 mm or more. If the peeling force P2 is within the above range, the problem of poor peeling in which the first surface protective film peels off together with the second surface protective film when the second surface protective film is peeled off can be suitably prevented. In addition, the generation of air bubbles between the first surface protective film and the second surface protective film can be suitably suppressed.

The ratio (P2/P1) of the peeling force P2 (peel speed: 300 mm/min, peel angle: 180°) of the second surface protective film to the first surface protective film relative to the peeling force P1 (peel speed: 300 mm/min, peel angle: 180°) of the first surface protective film relative to the optical laminate is typically 0.8 or less, preferably 0.6 or less, more preferably 0.5 or less, for example 0.2 or more. If the peeling force ratio (P2/P1) is within the above range, it is possible to suitably prevent the problem of poor peeling in which the first surface protective film peels off together with the second surface protective film when the second surface protective film is peeled off. In addition, it is possible to suitably suppress the generation of air bubbles between the first surface protective film and the second surface protective film.

<Second substrate>
The second substrate is made of any suitable resin film that can be used as a surface protection film. Specific examples of the material that is the main component of the resin film are as described above for the first substrate.

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

The thickness of the second substrate is typically 5 μm or more, preferably 20 μm or more, and typically 200 μm or less, preferably 100 μm or less.

<Second Pressure-Sensitive Adhesive Layer>
The second pressure-sensitive adhesive layer is composed of any suitable pressure-sensitive adhesive. The pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer typically contains at least one pressure-sensitive adhesive selected from the group consisting of (meth)acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, and silicone pressure-sensitive adhesives. Preferably, the second pressure-sensitive adhesive layer contains a (meth)acrylic pressure-sensitive adhesive. Details of the (meth)acrylic pressure-sensitive adhesive are as described above for the first pressure-sensitive adhesive layer.

The above adhesives ((meth)acrylic adhesives, urethane adhesives, and silicone adhesives) may contain a base polymer (or its constituent monomer components) and, if necessary, additives. Specific examples of additives are as described above for the first adhesive layer. By adjusting the composition of the base polymer (e.g., type and content of monomer, type and content of crosslinking agent, etc.), the molecular weight of the base polymer, the type or content of additives, etc., it is possible to obtain an adhesive layer having the desired adhesion to an adherend.

The thickness of the second adhesive layer is typically 8 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and is, for example, 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. When the second adhesive layer has the above thickness, the generation of air bubbles between the first surface protection film and the second surface protection film is suppressed, and defect inspection of the optical laminate can be performed well with these surface protection films attached.

The method for forming the second adhesive layer can be the same as the method for forming the first adhesive layer.

A-3. Optical laminate The optical laminate includes at least one optical member and is used in goggles with a display. Examples of the optical member include an absorptive polarizing member, a reflective polarizing member, and a phase difference member. The optical laminate may have a pressure-sensitive adhesive layer on the side opposite to the side on which the first surface protective film and the second surface protective film are attached.

A-3-1. Display system to which the optical laminate can be applied FIG. 2 is a schematic diagram showing the general configuration of a display system (goggles with a display) to which the optical laminate can be applied. In FIG. 2, the arrangement and shape of each component of the display system 2 are illustrated. The display system 2 includes a display element 12, a reflective polarizing member 14, a first lens unit 16, a half mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens unit 24. The reflective polarizing member 14 is disposed in front of the display surface 12a 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 phase difference member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14. Although not shown, the display system 2 can further include an absorptive polarizing member between the reflective polarizing member 14 and the second lens portion 24 .

The components arranged in front of the half mirror (in the illustrated example, the half mirror 18, the first lens section 16, the second phase difference 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 10 that may be included in the display element 12, and is converted into a first linearly polarized light.

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

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 formed with the first lens portion 16.

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

The first circularly polarized light emitted from the first λ/4 member included in the first phase difference 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 included in the second phase difference member 22. The second linearly polarized light emitted from the second λ/4 member 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 the second circularly polarized light by the second λ/4 element included in the second phase difference element 22, and the second circularly polarized light emitted from the second λ/4 element passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into the third linearly polarized light by the second λ/4 element included in the second phase difference element 22. The third linearly polarized light passes through the reflective polarizing element 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.

As described above, the display system 2 may include an absorptive polarizing member (typically, an absorptive polarizing film) in front of the reflective polarizing member 14 (the side closer to the eye). The reflection axis of the reflective polarizing member 14 and the absorption axis of the absorptive polarizing member may be arranged approximately parallel to each other. This allows the third linearly polarized light that has passed through the reflective polarizing member 14 to pass through the absorptive polarizing member as is. The reflective polarizing member and the absorptive polarizing member may be laminated, for example, via an adhesive layer.

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

For example, the absorption axis of the polarizing member 10 included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be arranged substantially parallel to each other or substantially perpendicular to each other. The angle between the absorption axis of the polarizing member 10 included in the display element 12 and the slow axis of the first λ/4 member included in the first phase difference 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 included in the second phase difference member 22 is, for example, 40° to 50°, may be 42° to 48°, or may be about 45°.

In the lens portion 4, 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, it is preferable that 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 such a configuration, for example, each member may be excellent in ease of handling. 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, 0.05 μm to 30 μm.

A-3-2. Configuration of the optical laminate FIG. 3 is a schematic cross-sectional view of an optical laminate that can be used in the display system illustrated in FIG. 2. The optical laminate 100a includes, in this order, a pressure-sensitive adhesive layer 31, a polarizing member 10, a first phase difference member 20, and a first protective member 41. The polarizing member 10, the first phase difference member 20, and the first protective member 41 are laminated via adhesive layers 51 and 52. The adhesive layers 51 and 52 are typically adhesive layers or pressure-sensitive adhesive layers, and are preferably pressure-sensitive adhesive layers. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm. The surface of the pressure-sensitive adhesive layer 31 is protected by a release liner 61 until it is used. The first surface protective film and the second surface protective film are attached to the surface of the first protective member 41 side of the optical laminate 100a.

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

The optical laminate 100a may be applied to the manufacture of a display system according to an embodiment in which the first phase difference member 20 is integrally provided with the display element 12 in the display system illustrated in FIG. 2, for example. For example, the release liner 61 is peeled off from the optical laminate 100a, and the polarizing member 10 is attached to the liquid crystal cell together with the rear polarizing member so that the polarizing member 10 becomes the front side (viewing side) polarizing member of the liquid crystal cell, thereby manufacturing a display system in which the first phase difference member 20 is integrally provided with the liquid crystal panel (display element). Also, for example, the release liner 61 is peeled off from the optical laminate 100a, and the polarizing member 10 is attached to the front of the organic EL panel via the adhesive layer 31, thereby manufacturing a display system in which the first phase difference member 20 is integrally provided with the organic EL panel (display element). In this case, from the viewpoint of anti-reflection, a third phase difference member including a third λ/4 member may be disposed between the optical laminate 100a and the organic EL panel. The third phase difference member may be included in the optical laminate. For example, the optical laminate may have an adhesive layer, a third phase difference member, a polarizing member, a first phase difference member, and a protective member in this order. The same explanation as for the first λ/4 member can be applied to the third λ/4 member. The third phase difference member can be arranged so that the slow axis of the third λ/4 member forms an angle of, for example, 40° to 50°, 42° to 48°, or about 45° with the absorption axis of the polarizing member 10.

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

The crossed transmittance (Tc) of the 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 polarizing member (absorptive polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The degree of polarization (P) of the polarizing member (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.9% or more.

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

The thickness of the absorptive polarizing film 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 5 μm or less.

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

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

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

Examples of the laminate produced using the above-mentioned two or more layer laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. The absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer into an absorptive polarizing film. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. The stretching typically includes immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution, if necessary. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is applied onto a thermoplastic resin, and it is possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, problems such as a decrease in the orientation of PVA or dissolution can be prevented when the PVA is immersed in water in the subsequent dyeing step or stretching step, and it is possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained by immersing the laminate in a liquid in a treatment process such as a dyeing process and an underwater stretching process. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction by a drying shrinkage process. The obtained resin substrate/absorptive polarizing film laminate may be used as it is (i.e., the resin substrate may be used as a protective layer for the absorptive polarizing film), or any suitable protective layer may be laminated on the peeled surface obtained by peeling the resin substrate from the resin substrate/absorptive polarizing film laminate, or on the surface opposite to the peeled surface. Details of the manufacturing method of such an absorptive polarizing film are described in, for example, JP 2012-73580 A and JP 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

The protective layer is formed of any suitable film that can be used as a protective layer for an absorptive polarizing film. Specific examples of materials that are the main components of the film include cycloolefin (COP) resins such as polynorbornene resins, polyester resins such as polyethylene terephthalate (PET) resins, cellulose resins such as triacetyl cellulose (TAC), transparent resins such as polycarbonate (PC), (meth)acrylic resins, polyvinyl alcohol resins, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polyolefins, and acetate resins. In addition, thermosetting resins or ultraviolet-curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, and silicone resins are also included. Note that "(meth)acrylic resin" refers to acrylic resins and/or methacrylic resins. In addition, glassy polymers such as siloxane polymers are also included. Also usable is the polymer film described in JP 2001-343529 A (WO 01/37007). As the material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain, and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition. The materials for the resin film can be used alone or in combination.

The thickness of the protective layer is typically 100 μm or less, for example, 5 μm to 80 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm.

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

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

The first λ/4 member is formed of any suitable material that can satisfy the above characteristics. The first λ/4 member can be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound.

Examples of resins contained in the resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, acrylic-based resins, and the like. These resins may be used alone or in combination. Examples of methods for combining include blending and copolymerization. When the first λ/4 member exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter sometimes simply referred to as a polycarbonate-based resin) 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 a structural unit derived from another dihydroxy compound as necessary. Details of polycarbonate-based resins that can be suitably used for the first λ/4 member and methods for forming the first λ/4 member are described, for example, in JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, and JP 2015-212818 A, and the descriptions in these publications are incorporated herein by reference.

The thickness of the first λ/4 member, which is 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 alignment solidified layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. The "alignment solidified layer" is a concept that includes an alignment solidified layer obtained by hardening a liquid crystal monomer as described below. In the first λ/4 member, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first λ/4 member (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it.

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

As the liquid crystal compound, any suitable liquid crystal polymer and/or liquid crystal monomer can be used. The liquid crystal polymer and the liquid crystal monomer 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, for example, in 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 first λ/4 member consisting of the liquid crystal alignment solidification 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.

<First positive C plate>
The thickness direction retardation Rth(550) of the first positive C plate 20b is preferably −50 nm to −300 nm, more preferably −70 nm to −250 nm, even more preferably −90 nm to −200 nm, and particularly preferably −100 nm to −180 nm. 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. The in-plane retardation Re(550) of the first positive C plate is, for example, less than 10 nm.

The first positive C plate may be formed of any suitable material. The first positive C plate is preferably composed of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods for forming a positive C plate include the liquid crystal compounds and methods for forming the retardation layer described in [0020] to [0028] of JP-A-2002-333642. In this case, the thickness of the first positive C plate is preferably 0.5 μm to 5 μm.

<First Protective Member>
The first protective member 41 typically includes a substrate. 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-based, acetate-based, and other resins. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

The first protective member preferably has a substrate and a surface treatment layer formed on the substrate. The first protective member having the surface treatment layer may be arranged so that the surface treatment layer is located on the front side. Specifically, the surface treatment layer may be located on the outermost surface of the optical laminate 100a. The surface treatment layer may have any appropriate function. Examples of the surface treatment layer include a hard coat layer, an anti-reflection layer, an anti-sticking layer, and an anti-glare layer. The first protective member may have two or more surface treatment layers.

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

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

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

The thickness of the adhesive layer is typically 1 μm or more, preferably 5 μm or more, more preferably 12 μm or more, and typically 60 μm or less, preferably 30 μm or less, more preferably 23 μm or less.

<Release liner>
The release liner 61 is formed of any suitable resin film. Specific examples of materials that are the main components of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The resin film materials can be used alone or in combination. The release liner may be transparent (e.g., haze of 5% or less, e.g., 3% or less) or may not be transparent. When inspecting the optical laminate with the surface protective film in a state where the release liner is attached, it is preferable that the release liner is transparent.

A release treatment layer may be provided on the contact surface of the release liner 61 with the adhesive layer 31. Examples of release treatment agents that form the release treatment layer include silicone-based release treatment agents, fluorine-based release treatment agents, and long-chain alkyl acrylate-based release treatment agents. The release treatment agents may be used alone or in combination. The thickness of the release treatment layer is typically 50 nm or more and 400 nm or less.

The thickness of the release liner is typically 5 μm or more, preferably 20 μm or more, and typically 60 μm or less, preferably 45 μm or less. If a release treatment layer is applied, the thickness of the release liner includes the thickness of the release treatment layer.

Figure 4 is a schematic cross-sectional view of another optical laminate that can be used in the display system illustrated in Figure 2. The optical laminate 100b includes an adhesive layer 32, a second phase difference member 22, and a second protective member 42 in this order. The second phase difference member 22 and the second protective member 42 are laminated via an adhesive layer 53. The adhesive layer 53 is typically an adhesive layer or an adhesive layer, and is preferably an adhesive layer. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm. The surface of the adhesive layer 32 is protected by a release liner 62 until it is used. The inner surface protection film and the outer surface protection film are attached to the surface of the optical laminate 100b on the second protective member 42 side.

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

The optical laminate 100b can be used to manufacture a display system in an embodiment in which the second phase difference member 22 is integrally provided with the first lens portion 16, for example, in the display system illustrated in FIG. 2. Specifically, the release liner 62 is peeled off from the optical laminate 100b, and the optical laminate 100b is bonded to the first lens portion 16 via the adhesive layer 32, thereby manufacturing a display system in which the second phase difference member 22 is integrally provided with the first lens portion 16.

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

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

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

<Second Positive C Plate>
The thickness direction retardation Rth(550) of the second positive C plate 22b is preferably −50 nm to −300 nm, more preferably −70 nm to −250 nm, even more preferably −90 nm to −200 nm, and particularly preferably −100 nm to −180 nm. 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. The in-plane retardation Re(550) of the second positive C plate is, for example, less than 10 nm.

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

<Second Protective Member>
The second protective member 42 typically includes a substrate, and preferably has a substrate and a surface treatment layer formed on the substrate. In this case, the surface treatment layer may be located on the outermost surface of the optical laminate 100b. The details of the substrate and the surface treatment layer can be described in the same manner as for the first protective member. According to an embodiment in which an anti-reflection layer is provided on the outermost surface of the second protective member 42 as the surface treatment layer, an excellent anti-reflection effect can be obtained in a display system in which the second phase difference member 22 is integrated with the first lens unit 16, the reflective polarizing member 14 is integrated with the second lens unit 24, and a space is formed between them.

The same explanations as for the adhesive layer 31 and release liner 61 used in the optical laminate 100a can be applied to the adhesive layer 32 and release liner 62 used in the optical laminate 100b.

Figure 5 is a schematic cross-sectional view of yet another optical laminate that can be used in the display system illustrated in Figure 2. The optical laminate 100c includes an adhesive layer 33, an absorptive polarizing member 11, a reflective polarizing member 14, and a third protective member 43, in this order. The absorption axis of the absorptive polarizing member 11 and the reflection axis of the reflective polarizing member 14 are arranged to be approximately parallel to each other, and the transmission axis of the absorptive polarizing member 11 and the transmission axis of the reflective polarizing member 14 are arranged to be approximately parallel to each other. The absorptive polarizing member 11, the reflective polarizing member 14, and the third protective member 43 are laminated via adhesive layers 54 and 55. The adhesive layers 54 and 55 are typically adhesive layers or adhesive layers, and are preferably adhesive layers. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm. The surface of the adhesive layer 33 is protected by a release liner 63 until it is used. The inner surface protection film and the outer surface protection film are attached to the surface of the optical laminate 100c on the third protective member 43 side.

The optical laminate 100c can be used to manufacture a display system of an embodiment further including an absorptive polarizing member between the reflective polarizing member 14 and the second lens portion 24 in the display system illustrated in FIG. 2, for example. Specifically, by peeling the release liner 63 from the optical laminate 100c and attaching it to the second lens portion 24 via the adhesive layer 33, a display system can be manufactured in which the reflective polarizing member 14 and the absorptive polarizing member 11 are integrally provided with the second lens portion 24.

<Reflective polarizing member>
The reflective polarizing element 14 can transmit light polarized parallel to its transmission axis (typically, linearly polarized light) while maintaining its polarization state, and can reflect light in other polarization states. The orthogonal transmittance (Tc) of the reflective polarizing element can be, for example, 0.01% to 3%. The single transmittance (Ts) of the reflective polarizing element can be, for example, 43% to 49%, preferably 45 to 47%. The polarization degree (P) of the reflective polarizing element can be, for example, 92% to 99.99%. The reflective polarizing element is typically composed of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). Commercially available reflective polarizing films include, for example, 3M's product names "DBEF" and "APF" and Nitto Denko's product name "APCF".

<Third Protective Member>
The third protective member 43 typically includes a substrate, and preferably has a substrate and a surface treatment layer formed on the substrate. In this case, the surface treatment layer may be located on the outermost surface of the optical laminate 100c. The details of the substrate and the surface treatment layer can be similar to those of the first protective member. According to an embodiment in which an anti-reflection layer is provided on the outermost surface of the third protective member 43 as the surface treatment layer, an excellent anti-reflection effect can be obtained in a display system in which the second phase difference member 22 is integrated with the first lens unit 16, the reflective polarizing member 14 is integrated with the second lens unit 24, and a space is formed between them.

The same explanations as for the polarizing member 10, adhesive layer 31, and release liner 61 used in the optical laminate 100a can be applied to the absorptive polarizing member 11, adhesive layer 33, and release liner 63 used in the optical laminate 100c, respectively.

B. Manufacturing method of a display system According to another aspect of the present invention, there is provided a manufacturing method of a display system (goggles with a display) using the optical laminate with a surface protective film described in section A. The manufacturing method of a display system according to one embodiment of the present invention includes the following steps:
Inspecting the optical laminate with the surface protective film described in item A for defects;
Attaching another member to the side of the optical laminate with a surface protective film opposite to the side to which the inner surface protective film and the outer surface protective film are attached, thereby obtaining a secondary laminate with a surface protective film;
Peeling off the outer surface protective film from the secondary laminate with the surface protective film;
inspecting the secondary laminate with the surface protective film for defects; and peeling off the inner surface protective film from the secondary laminate with the surface protective film to obtain a secondary laminate.
Includes, in this order.
The obtained secondary laminate is subjected to an assembly process, and assembled with other members to form a display system. Hereinafter, an example of a manufacturing method of a display system using an optical laminate with a surface protective film having the optical laminate 100a illustrated in FIG. 3 will be described with reference to FIGS. 6A to 6E.

As shown in FIG. 6A, the optical laminate 200 with the surface protective film to be inspected has an optical laminate 100a, and the inner surface protective film 110 and the outer surface protective film 120 are attached outwardly in this order to the surface of the first protective member 41 side of the optical laminate 100a. Examples of defect inspections performed on the optical laminate with the surface protective film include visual defect inspection and automatic optical inspection (AOI) using a known automatic defect inspection device. The defect inspection may be a transmission type or a reflection type. In one embodiment, the defect inspection is a reflection type. In this case, for example, inspection light is irradiated from a light source to the surface of the outer surface protective film 120 side of the optical laminate 200 with the surface protective film, and the reflected light image is acquired by an imaging device C such as a line sensor or a two-dimensional camera, and defect detection is performed based on the acquired image data. In another embodiment, the defect inspection is a transmission type. In this case, for example, inspection light is irradiated from a light source onto the surface of the release liner 61 side of the optical laminate 200 with a surface protective film, and the transmitted light image is acquired by the imaging device C, and defect detection is performed based on the acquired image data. If necessary, the reflection type inspection and the transmission type inspection may be combined. The inspection is preferably performed in a clean room. Examples of defects to be detected include scratches, foreign matter, air bubbles, dirt, etc. The size of the defect may be, for example, 45 μm to 500 μm. Note that, another surface protective film may be provided on the outside of the outer surface protective film and/or release liner of the optical laminate with a surface protective film to be inspected until it is subjected to inspection. By peeling off the other surface protective film immediately before inspection, it is possible to prevent scratches, foreign matter, dirt, etc. from adhering to the surface of the outer surface protective film and/or release liner, and as a result, it is possible to prevent these from being erroneously detected as defects in the optical laminate. As such a separate surface protective film, one whose adhesive strength to the outer surface protective film or release liner is weaker than the adhesive strength of the outer surface protective film or release liner to the substrate is preferably used.

Next, another member is attached to the side opposite to the side to which the inner surface protection film and the outer surface protection film are attached of the optical laminate with surface protection film that has been determined to be a non-defective product in the defect inspection, to obtain a secondary laminate with surface protection film. Specifically, as shown in FIG. 6B, the release liner 61 is peeled off from the optical laminate with surface protection film 200, and the exposed adhesive layer 31 is attached to another member 300 to obtain a secondary laminate with surface protection film 400a. In one embodiment, the other member 300 is an optical member such as an organic EL panel or a liquid crystal cell, and the optical laminate with surface protection film is attached to the viewing side (front) surface of the optical laminate.

When attached to another member 300, the optical laminate 200 with a surface protective film may have a shape corresponding to the shape of the other member 300. For example, the optical laminate 200 with a surface protective film may be formed in a long shape and processed into the desired shape by cutting, punching, machining, etc. after the above-mentioned defect inspection. Alternatively, the optical laminate 200 with a surface protective film may be processed into the desired shape and then subjected to defect inspection.

Next, as shown in Figures 6C and 6D, the outer surface protective film 120 is peeled off from the secondary laminate 400a with the surface protective film, and the resulting secondary laminate 400b with the surface protective film is inspected for defects. Examples of defect inspections performed on the secondary laminate with the surface protective film include inspections similar to the defect inspections performed on the optical laminate 200 with the surface protective film.

Next, as shown in FIG. 6E, the inner surface protective film 110 is peeled off from the secondary laminate 400b with the surface protective film that has been determined to be a non-defective product in the above defect inspection, to obtain the secondary laminate 400c.

The secondary laminate 400c is subjected to an assembly process and assembled with other components (e.g., the optical laminate shown in Figure 4 or Figure 5) to form a display system.

The above manufacturing method allows the optical laminate to be inspected for defects multiple times while its surface is protected, and can effectively prevent scratches, dirt, etc. from adhering to its surface until immediately before incorporation into a display system. This effect is particularly advantageous when processes such as the manufacture of the optical laminate, the manufacture of an intermediate product (e.g., a display element) using the optical laminate, and the manufacture (assembly) of a display system using the intermediate product are carried out in separate locations. In one embodiment, the optical laminate manufactured by the optical laminate manufacturer is inspected for defects in the state of an optical laminate with surface protective films to which inner and outer surface protective films are attached (e.g., FIG. 6A); those judged to be good in the defect inspection are shipped to a display element manufacturer as a first semi-finished product; the display element manufacturer attaches the optical laminate with surface protective films to optical components such as liquid crystal cells and organic EL panels to manufacture display elements (liquid crystal display elements, organic EL display elements, etc.) (e.g., FIG. 6B); from this, the outer surface protective film is peeled off and a defect inspection is performed on the display element protected by the inner surface protective film (e.g., FIGS. 6C and D); the display element judged to be good in the defect inspection is shipped to a display system manufacturer as a second semi-finished product protected by the inner surface protective film; the display element, from which the inner surface protective film has been peeled off and put into use, can be provided for assembly with other components by the display system manufacturer (e.g., FIG. 6E). According to the manufacturing method of this embodiment, it is possible to effectively inspect the first semi-finished product, the optical laminate, for defects, prevent defects (scratches, foreign matter, dirt, etc.) when shipping the first semi-finished product that has been determined to be non-defective in the defect inspection, inspect the second semi-finished product, the display element, for defects when manufacturing it, and prevent defects (scratches, foreign matter, dirt, etc.) when shipping the second semi-finished product, which can contribute to the efficient manufacture of final products.

The manufacturing method of the display system is not limited to the illustrated example. For example, the outer surface protective film may be peeled off before the release liner is peeled off and the film is attached to another member, and the second defect inspection may be performed before the film is attached to another member. Also, for example, the inner surface protective film may be peeled off after the optical laminate is placed in a predetermined position in the display system.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The thicknesses are values measured by the following measuring method.
<Thickness>
The thickness was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C").
<In-plane retardation or thickness direction retardation>
A sample was prepared by cutting out a square 50 mm wide and 50 mm long from the center of the width of the member to be measured, with one side parallel to the width of the member. The in-plane retardation and thickness retardation of the sample were measured using a "KOBRA-WPR" manufactured by Oji Scientific Instruments.

[Production Example 1A: Preparation of Surface Protection Film A]
<Acrylic Polymer A>
In a reaction vessel equipped with a thermometer, a stirrer, a cooler and a nitrogen gas inlet tube, 100 parts by mass of 2-ethylhexyl acrylate (2EHA) and 4 parts by mass of hexyl acrylate as monomer components, and 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged together with 150 parts by mass of ethyl acetate, and nitrogen gas was introduced while gently stirring at 23°C to perform nitrogen substitution. Thereafter, the liquid temperature was kept at around 65°C and a polymerization reaction was carried out for 6 hours to prepare a solution of acrylic polymer A (concentration 40% by mass). The weight average molecular weight of acrylic polymer A was 530,000.

<Pressure-sensitive adhesive composition A>
Ethyl acetate was added to the solution of acrylic polymer A to dilute it to a concentration of 20% by mass. 5 parts by mass of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) as a crosslinking agent and 0.3 parts by mass of a surfactant ("Aqualon HS-10" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added to 500 parts by mass of this solution (100 parts by mass of solid content) and stirred to prepare a pressure-sensitive adhesive composition A.

<Surface Protection Film A>
The pressure-sensitive adhesive composition A was applied to the surface (corona-treated surface) of a substrate (PET film, "CE901-38" manufactured by KOLON Corporation, thickness 38 μm) and then dried to form a pressure-sensitive adhesive layer (thickness 10 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the pressure-sensitive adhesive layer opposite the substrate.

[Production Example 1B: Preparation of Surface Protection Film B]
<Pressure-sensitive adhesive composition B>
Ethyl acetate was added to the solution of acrylic polymer A obtained in Production Example 1A to dilute it to a concentration of 20% by mass. 4 parts by mass of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) as a crosslinking agent and 0.2 parts by mass of a surfactant ("Aqualon HS-10" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were added to 500 parts by mass of this solution (100 parts by mass of solid content) and stirred to prepare a pressure-sensitive adhesive composition B.

<Surface Protection Film B>
The pressure-sensitive adhesive composition B was applied to the surface (corona-treated surface) of a substrate (PET film, manufactured by Mitsubishi Chemical Corporation, product number T100C38, thickness 38 μm) and then dried to form a pressure-sensitive adhesive layer (thickness 20 μm). Next, a release liner (manufactured by Toyobo Co., Ltd., product number TG704) was attached to the surface of the pressure-sensitive adhesive layer opposite to the substrate.

[Production Example 1C: Preparation of Surface Protection Film C]
<Acrylic Polymer C>
In a reaction vessel equipped with a thermometer, a stirrer, a cooler and a nitrogen gas inlet tube, 96.2 parts by mass of 2-ethylhexyl acrylate (2EHA) and 3.8 parts by mass of hydroxyethyl acrylate (HEA) as monomer components, and 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged together with 150 parts by mass of ethyl acetate, and nitrogen gas was introduced while gently stirring at 23 ° C. to perform nitrogen substitution. Thereafter, the liquid temperature was kept at around 65 ° C. and a polymerization reaction was carried out for 6 hours to prepare a solution of acrylic polymer C (concentration 40% by mass). The weight average molecular weight of acrylic polymer C was 540,000.

<Pressure-sensitive adhesive composition C>
Ethyl acetate was added to the solution of acrylic polymer C to dilute it to a concentration of 20% by mass. 4 parts by mass of an isocyanurate of hexamethylene diisocyanate ("Coronate HX" manufactured by Tosoh Corporation) as a crosslinking agent and 3 parts by mass (solid content 0.03 parts by mass) of dibutyltin dilaurate (1% by mass solution in ethyl acetate) as a crosslinking catalyst were added to 500 parts by mass (solid content 100 parts by mass) of this solution and stirred to prepare a pressure-sensitive adhesive composition C.

<Surface Protective Film C>
A PET film (Mitsubishi Chemical Corporation, product number T100C38, thickness 38 μm) was used as the substrate, and the pressure-sensitive adhesive composition C was applied to its corona-treated surface, which was then dried to form a pressure-sensitive adhesive layer (thickness 5 μm). Next, a release liner (Toyobo Co., Ltd., product number TG704) was attached to the surface of the pressure-sensitive adhesive layer opposite the substrate. This resulted in a surface protection film C.

[Production Example 1D: Preparation of Surface Protective Film D]
A surface protection film D was obtained in the same manner as in Production Example 1C, except that a PET film ("CE905-38" manufactured by KOLON Corporation, thickness 38 μm) was used as the substrate and pressure-sensitive adhesive composition C was applied to one side of the substrate to form a pressure-sensitive adhesive layer having a thickness of 15 μm.

The following evaluations (1) and (2) were carried out for the above surface protection films A to D. The results are shown in Table 1 together with the thicknesses of the substrate and the pressure-sensitive adhesive layer.
(1) Total Light Transmittance and Haze For each surface protection film, the release liner was peeled off from the pressure-sensitive adhesive layer, and light was irradiated from the substrate side using a haze meter ("HZ-V3" manufactured by Suga Test Instruments Co., Ltd.), and the haze was calculated according to JIS-K-7136 by the formula: Haze (%) = (Td/Tt) x 100 (Td: diffuse transmittance, Tt: total light transmittance). The total light transmittance was measured according to JIS-K-7316.
(2) Peeling force The surface protective film was cut into a size of 50 mm wide and 100 mm long, the release liner was peeled off from the adhesive layer, and the adherend was roll-pressed at a pressure of 0.25 MPa and a feed rate of 0.3 m/min. The sample was left to stand in an environment of 23°C and 50% relative humidity for 30 minutes, and then a peel test was performed in the same environment at a peel angle of 180° and a tensile speed of 300 mm/min to measure the 180° peeling force. For the surface protective films A to C, the surface protective film D was used as the adherend, and the peeling force of the surface protective film D against the substrate side surface was measured. For the surface protective film D, the optical laminate A prepared in Example 1 described later was used as the adherend, and the peeling force against the protective member A side surface was measured. The measurement was performed with N=10, and the average value was taken as the peeling force.

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

[Manufacturing Example 3: Preparation of λ/4 member A]
Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 x 10 ^-2 parts by mass (6.78 x 10 ^-5 mol) of calcium acetate monohydrate as a catalyst were charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the inside temperature reached 100°C. The internal temperature was allowed to reach 220°C 40 minutes after the start of the temperature rise, and the pressure was controlled to maintain this temperature while simultaneously starting decompression, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 220°C. Phenol vapor by-produced during the polymerization reaction was led to a reflux condenser at 100°C, a small amount of monomer components contained in the phenol vapor were returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure once, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature rise and decompression in the second reactor were started, and the internal temperature was set to 240°C and the pressure to 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. Nitrogen was introduced into the reactor at the time the predetermined power was reached to restore the pressure, and the polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets.

The obtained polyester carbonate resin (pellets) was vacuum dried at 80°C for 5 hours, and then a long resin film with a thickness of 135 μm was produced using a film-making device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chill roll (set temperature: 120-130°C) and a winder. The obtained long resin film was stretched in the width direction at a stretching temperature of 143°C and a stretch ratio of 2.8 times. This resulted in a stretched film (λ/4 member A) with a thickness of 47 μm. The Re(590) of the λ/4 member A was 143 nm, the Re(450)/Re(550) was 0.86, and the Nz coefficient was 1.12.

[Production Example 4: Preparation of positive C plate A]
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 by 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 A having a thickness of 4 μm and an Rth (550) of −100 nm on the substrate.

[Production Example 5: Preparation of protective member A]
The material for forming a hard coat layer shown below was applied to an acrylic film (thickness 40 μm) having a lactone ring structure, and the coating layer was dried to form a hard coat layer with a thickness of 0.5 μm. Next, the coating liquid for forming an antireflection layer shown below was applied to the surface of the hard coat layer and heated at 80° C. for 1 minute, and the coating layer after heating was irradiated with ultraviolet light with an integrated light amount of 300 mJ/cm ² from a high-pressure mercury lamp to harden the coating layer, forming an antireflection layer with a thickness of 0.1 μm. This resulted in a protective member A having a configuration of [acrylic film/hard coat layer/antireflection layer].

(Hard Coat Layer Forming Material)
A hard coat layer forming material was prepared by adding 0.5% by weight of a leveling agent to an acrylic resin raw material (manufactured by Dai Nippon Ink Co., Ltd., product name: GRANDIC PC1071) and further diluting with ethyl acetate to a solid content concentration of 50% by weight. The leveling agent is a copolymer copolymerized in a molar ratio of dimethylsiloxane: hydroxypropylsiloxane: 6-isocyanatehexylisocyanuric acid: aliphatic polyester = 6.3: 1.0: 2.2: 1.0.

(Anti-reflection layer forming coating solution)
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, 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 was added as a dilution solvent so that the total solid content was 4% by weight, and the mixture was stirred to prepare a coating liquid for forming an anti-reflection layer.

[Production Example 6: Preparation of Pressure-Sensitive Adhesive Layer A]
A monomer mixture containing 80.3 parts of butyl acrylate, 16 parts of phenoxyethyl acrylate, 3 parts of N-vinyl-2-pyrrolidone (NVP), 0.3 parts of acrylic acid, and 0.4 parts of 4-hydroxybutyl acrylate was charged into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with 100 parts of ethyl acetate for 100 parts of the above monomer mixture (solid content), and nitrogen gas was introduced to replace the nitrogen gas while gently stirring. Next, the liquid temperature in the flask was kept at about 55°C and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. The weight average molecular weight of the acrylic polymer was 1.5 million. 0.3 parts of benzoyl peroxide (BPO: Niper BMT manufactured by NOF Corporation) was mixed as a crosslinking agent for 100 parts of the solid content of the obtained acrylic polymer solution to prepare an acrylic adhesive solution.
The obtained adhesive composition was applied onto the release treated layer surface of a release liner (Therapeel, manufactured by Toray Industries, Inc.) and dried at 155° C. for 3 minutes to form an adhesive layer having a thickness of 20 μm.

[Example 1]
The pressure-sensitive adhesive layer A was attached to the COP protective layer side surface of the polarizing film A together with a release liner.
On the other hand, a positive C plate A was attached to the λ/4 member A via an ultraviolet-curing adhesive (thickness after curing: 1 μm), and then the base material was peeled off and removed to obtain a retardation member.
The obtained retardation member was attached via an acrylic pressure-sensitive adhesive layer (thickness: 15 μm) to the TAC film side surface of the polarizing film A. At this time, the retardation member was attached so that the surface of the retardation member on the λ/4 member A side was the polarizing film A side, and the angle between the absorption axis of the absorptive polarizing film and the slow axis of the λ/4 member A was 45°.
Next, the protective member A was attached to the surface of the retardation member via an acrylic adhesive layer (thickness 12 μm). At this time, the protective member A was attached so that the acrylic film side surface of the protective member A was on the retardation member side (in other words, so that the antireflection layer was the outermost surface). In this way, an optical laminate A having a configuration of [release liner/adhesive layer A/polarizing film A/λ/4 member A/positive C plate A/protective member A] was obtained.
Next, the release liner was peeled off from the surface protective film D, and the inner surface protective film was attached to the protective member A side surface (antireflection layer surface) of the optical laminate A. Next, the release liner was peeled off from the surface protective film A, and the outer surface protective film was attached to the substrate side surface of the surface protective film D. This resulted in an optical laminate with a surface protective film having a configuration of [optical laminate A/surface protective film D/surface protective film A].

[Example 2]
An optical laminate with a surface protective film having a structure of [optical laminate A/surface protective film D/surface protective film B] was obtained in the same manner as in Example 1, except that surface protective film B was used as the outer surface protective film.

[Comparative Example 1]
An optical laminate with a surface protective film having a structure of [optical laminate A/surface protective film D/surface protective film C] was obtained in the same manner as in Example 1, except that surface protective film C was used as the outer surface protective film.

<Air bubble evaluation>
The optical laminates with surface protective films obtained in the above examples and comparative examples were cut into a size of 371.87 mm x 236.58 mm and used as evaluation samples. The evaluation samples were set in an automatic optical inspection device, and a reflective appearance inspection was performed to count the number of bubbles present between the inner surface protective film and the outer surface film. The number of bubbles generated per ^m2 is shown in Table 2.

<Evaluation of peeling stability>
The optical laminates with surface protective films obtained in the Examples and Comparative Examples were placed on a laboratory bench at room temperature with the surface protective film side facing up, and the outer surface protective film was peeled off at a peeling angle of 180° and a peeling speed of 300 mm/min, and evaluated according to the following criteria. The results are shown in Table 2.
Good: Only the outer surface protective film was peeled off. Bad: Both the outer surface protective film and the inner surface protective film were peeled off.

As shown in Table 2, the optical laminate with surface protective film of the embodiment suppresses the generation of air bubbles between the inner surface protective film and the outer surface protective film, and therefore, when subjected to defect inspection, it is found that erroneous detection of air bubbles as defects is prevented. Furthermore, an optical laminate with surface protective film having such a configuration can be subjected to multiple defect inspections with the surface protective film attached, and the surface of the optical laminate can be suitably protected until it is subjected to final assembly. Furthermore, the optical laminate with surface protective film of the embodiment also has excellent peel stability.

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

The optical laminate with protective film according to an embodiment of the present invention can be used, for example, in the manufacture of goggles with a display, such as VR goggles.

2 Display system 4 Lens section 10 Polarizing member 12 Display element 14 Reflective polarizing member 16 First lens section 18 Half mirror 20 First phase difference member 22 Second phase difference member 24 Second lens section 100 Optical laminate 110 First surface protective film 120 Second surface protective film 200 Optical laminate with surface protective film

Claims (9)

An optical laminate including at least one optical member and used in goggles with a display;
a first surface protective film and a second surface protective film attached in this order outwardly to one surface of the optical laminate;
An optical laminate with a surface protective film, comprising:
the first surface protective film has a first substrate and a first pressure-sensitive adhesive layer laminated on the first substrate,
the second surface protective film has a second substrate and a second pressure-sensitive adhesive layer laminated on the second substrate,
The thickness of the second pressure-sensitive adhesive layer is 8 μm or more,
An optical laminate with a surface protective film, wherein a peeling force P1 of the first surface protective film to the optical laminate and a peeling force P2 of the second surface protective film to the first surface protective film satisfy the relationship P2/P1≦0.8. The optical laminate with a surface protective film according to claim 1, wherein the peeling force P2 of the second surface protective film relative to the first surface protective film is 0.5 N/50 mm or less. The optical laminate with surface protective film according to claim 1, wherein the total light transmittance of the first surface protective film and the second surface protective film is 85% or more. The optical laminate with surface protective film according to claim 1, wherein the ratio (L2/L1) of the total light transmittance L1 of the first surface protective film to the total light transmittance L2 of the second surface protective film is 0.8 to 1.2. The optical laminate,
(1) An absorptive polarizing member, a first phase difference member, and a protective member are provided in this order toward the first surface protective film,
(2) A second retardation member and a protective member are provided in this order toward the first surface protective film, or (3) A reflective polarizing member and a protective member are provided in this order toward the first surface protective film.
The optical laminate with the surface protective film according to claim 1 . The protective member includes a surface treatment layer,
The optical laminate with a surface protective film according to claim 5 , wherein the first surface protective film is attached to the surface treatment layer. the surface treatment layer includes an anti-reflection layer,
The optical laminate with a surface protective film according to claim 6 , wherein the first surface protective film is attached to the antireflection layer. The optical laminate with surface protective film according to claim 1, wherein the optical laminate has a pressure-sensitive adhesive layer on the side opposite to the side on which the first surface protective film and the second surface protective film are attached. 1. A method for manufacturing a display system, comprising:
Inspecting a defect of an optical laminate with a surface protective film according to any one of claims 1 to 8;
Attaching another member to the side of the optical laminate with a surface protective film opposite to the side to which the first surface protective film and the second surface protective film are attached, thereby obtaining a secondary laminate with a surface protective film;
Peeling off the second surface protective film from the secondary laminate with the surface protective film;
inspecting the secondary laminate with the surface protective film for defects; and peeling off the first surface protective film from the secondary laminate with the surface protective film to obtain a secondary laminate.
in that order,
The method of manufacturing, wherein the display system is goggles with a display.

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