Optical laminate

Abstract

Provided is an optical laminate in which a surface protection film is temporarily affixed to an optical film, and in which the generation of air bubbles at the end of the surface protection film after autoclave treatment is suppressed. An optical laminate according to an embodiment of the present invention comprises: an optical film having a polarizing plate including a polarizer and an anti-glare layer disposed on one side of the polarizing plate; and a surface protection film which comprises a base film and an adhesive layer and is temporarily affixed to the anti-glare layer side of the optical film in a peelable manner by means of the adhesive layer. The arithmetic average roughness Ra of the surface of the optical film on the surface protection film side is 0.15 [mu] m or more; the difference between the cetane contact angle of the surface of the optical film on the surface protection film side and the cetane contact angle of the adhesive layer is 50 DEG or less.

Description

Technical Field

[0001] This invention relates to optical laminates. Background Technology

[0002] In recent years, image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (such as organic EL displays and inorganic EL displays), have been rapidly gaining popularity. Various optical thin films are used in image display devices depending on the purpose and desired characteristics. However, in practical applications, surface protective films are often temporarily adhered to the optical thin films in a peelable manner during the manufacturing, inspection, and transportation processes. These surface protective films are frequently used to protect the optical thin films from damage, dirt, and other contaminants.

[0003] Optical laminates, such as those with a temporary protective film adhered to the optical film, are sometimes subjected to autoclave processing to remove air bubbles from the entire optical film. However, depending on the type and composition of the optical film, air bubbles may sometimes form at the ends of the protective film during autoclave processing. As a result, this can sometimes hinder the inspection of the optical film.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-38254 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The main objective of this invention is to provide an optical laminate in which a surface protective film is temporarily attached to an optical thin film, and the generation of bubbles at the ends of the surface protective film is suppressed after autoclaving.

[0009] means for solving problems

[0010] [1] According to an embodiment of the present invention, an optical laminate is provided. The optical laminate comprises: an optical film having a polarizer including a polarizer and an anti-glare layer disposed on one side of the polarizer; and a surface protection film comprising a substrate film and an adhesive layer, wherein the surface protection film is temporarily adhered to the anti-glare layer side of the optical film in a peelable manner by means of the adhesive layer. The arithmetic mean roughness Ra of the surface of the surface protection film side of the optical film is 0.15 μm or more; the difference between the hexadecane contact angle of the surface of the surface protection film side of the optical film and the hexadecane contact angle of the adhesive layer is 50° or less.

[0011] [2] In the above [1], the hexadecane contact angle of the surface of the above optical thin film on the surface protection film side is 50° or more, and the water contact angle is 105° or more.

[0012] [3] In [1] or [2] above, the difference between the hexadecane contact angle of the surface of the optical film on the surface protection film side and the hexadecane contact angle of the adhesive layer is 15° or less, and the difference between the water contact angle of the surface of the optical film on the surface protection film side and the water contact angle of the adhesive layer is 15° or less.

[0013] [4] In any of the above [1] to [3], the polarizer includes a non-polarizing portion, the anti-glare layer includes a non-anti-glare portion, and the non-polarizing portion and the non-anti-glare portion are disposed at corresponding positions.

[0014] [5] In any of the above [1] to [4], the optical laminate also has an anti-reflective layer on the side of the anti-glare layer opposite to the polarizer, and the surface protective film is temporarily attached to the anti-reflective layer in a peelable manner by means of the adhesive layer.

[0015] [6] In the above [5], the haze of the anti-reflective layer is less than 1.0%, and the haze of the anti-glare layer is 5.0% or more.

[0016] [7] In any of the above [1] to [6], the optical laminate also has an anti-fouling layer on the side of the anti-reflective layer opposite to the anti-glare layer, and the surface protective film is temporarily attached to the anti-fouling layer in a peelable manner by means of the adhesive layer.

[0017] Invention Effects

[0018] According to an embodiment of the present invention, an optical laminate is realized, which is an optical laminate on which a surface protective film is temporarily attached, and the generation of bubbles at the end of the surface protective film is suppressed after autoclaving. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of an optical laminate according to one embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures

[0021] 10 Substrate Film

[0022] 20 adhesive layers

[0023] 100 Surface Protective Film

[0024] 120 polarizer

[0025] 121 polarizer

[0026] 122 protective layer

[0027] 123 protective layer

[0028] 125 Unpolarized Part

[0029] 130 anti-glare layer

[0030] 135 Non-anti-glare section

[0031] 140 anti-reflective layer

[0032] 150 anti-fouling layer

[0033] 200 optical thin film

[0034] 300 optical laminate Detailed Implementation

[0035] Hereinafter, representative embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. It should be noted that, for ease of observation and understanding, the drawings are schematic depictions, and the length, width, thickness, ratio, etc. do not reflect the actual shape.

[0036] A. Overview of Optical Laminates

[0037] Figure 1 This is a cross-sectional schematic diagram of an optical laminate according to one embodiment of the present invention. The optical laminate 300 in the example includes an optical thin film 200 and a surface protective film 100. The optical thin film 200 has a polarizer 120 and an anti-glare layer 130 disposed on one side of the polarizer 120. If necessary, the optical laminate 300 (essentially the optical thin film 200) may further have an anti-reflective layer 140 on the side of the anti-glare layer 130 opposite to the polarizer 120, as shown in the example. Furthermore, if necessary, an anti-fouling layer 150 may be provided on the side of the anti-reflective layer 140 opposite to the anti-glare layer 130. If the anti-reflective layer 140 is omitted, the anti-fouling layer 150 may be provided on the surface of the anti-glare layer 130. The surface protective film 100 includes a substrate film 10 and an adhesive layer 20, which is temporarily adhered to the anti-glare layer side of the optical thin film 200 in a peelable manner by means of the adhesive layer 20. In the example, the surface protective film 100 is temporarily adhered to the anti-fouling layer 150 in a peelable manner. If the antifouling layer is omitted, the surface protective film 100 can be temporarily adhered to the antireflective layer 140 in a peelable manner. If both the antifouling layer and the antireflective layer are omitted, the surface protective film 100 can be temporarily adhered to the antiglare layer 130 in a peelable manner.

[0038] In embodiments of the present invention, the arithmetic mean roughness Ra of the surface of the protective film 100 side of the optical film 200 is 0.15 μm or more, for example, 0.15 μm to 0.50 μm, and further, for example, 0.20 μm to 0.40 μm. This is because the anti-glare layer, as described later, has an uneven surface. According to embodiments of the present invention, even when the protective film is temporarily adhered to the optical film having an uneven surface, the generation of bubbles at the ends of the protective film after autoclaving can be suppressed. It should be noted that the arithmetic mean roughness Ra can be measured according to JIS B 0601.

[0039] Furthermore, in an embodiment of the present invention, the hexadecane contact angle CAH of the surface of the optical thin film 200 on the surface of the protective film 100 side is... OF cetane contact angle CAH with adhesive layer 20 PSA The difference (CAH) OF -CAH PSA The angle is 50° or less, preferably 45° or less, more preferably 40° or less, further preferably 35° or less, particularly preferably 30° or less, and especially preferably 15° or less. (CAH) OF -CAH PSA The smaller the value, the better; the lower limit can be, for example, 5°, or even 10°. (CAH) OF -CAH PSA When the value is within this range, in an optical laminate in which a surface protective film is temporarily adhered to an optical thin film with an uneven surface, the generation of bubbles at the ends of the surface protective film after autoclave treatment can be significantly suppressed. The hexadecane contact angle (CAH) of the surface protective film side of the optical thin film... OF Preferably, the angle is 35° or higher, more preferably 45° or higher, even more preferably 50° or higher, and particularly preferably 55° or higher. (Hexadecane contact angle CAH) OF For example, it can be below 75°, or even below 70°. The hexadecane contact angle (CAH) of the adhesive layer. PSA Preferably, the angle is 15° or more, more preferably 25° or more, and even more preferably 30° or more. (Hexadecane contact angle CAH) PSA For example, it can be below 65°, or below 60°.

[0040] In one embodiment, the water contact angle (CAW) of the surface of the optical thin film 200 on the surface of the protective film 100 side is... OF Water contact angle CAW with adhesive layer 20 PSA The difference (CAW) OF -CAW PSAPreferably, the angle is 25° or less, more preferably 22° or less, even more preferably 20° or less, particularly preferably 15° or less, and especially preferably 10° or less. (CAW) OF -CAW PSA The smaller the value, the better; its lower limit can be, for example, 1°, or even 2°. (CAW) OF -CAW PSA When the value is within this range, in an optical laminate in which a surface protective film is temporarily adhered to an optical thin film with an uneven surface, the generation of bubbles at the ends of the surface protective film after autoclaving can be further significantly suppressed. The water contact angle (CAW) of the surface of the optical thin film on the surface protective film side is... OF Preferably, the angle is 80° or higher, more preferably 85° or higher, even more preferably 90° or higher, particularly preferably 100° or higher, and especially preferably 105° or higher. Water contact angle (CAW) OF For example, it can be below 125°, or even below 120°. Water contact angle (CAW) of the adhesive layer. PSA Preferably 85° or higher, more preferably 90° or higher, and even more preferably 95° or higher. Water contact angle (CAW) PSA For example, it can be below 115°, or below 110°.

[0041] Polarizer 120 has a polarizer 121, a protective layer 122 disposed on one side of the polarizer (the anti-glare layer side in the example), and a protective layer 123 disposed on the other side of the polarizer. At least one of the protective layers 122 and 123 may be omitted depending on the purpose, application, and desired characteristics of the optical thin film. Therefore, the polarizer may be a so-called double-protected polarizer, a so-called single-sided protected polarizer, or may be constituted solely by the polarizer.

[0042] In one embodiment, the polarizer 121 includes a non-polarizing portion 125, and the anti-glare layer 130 includes a non-anti-glare portion 135. The non-polarizing portion 125 and the non-anti-glare portion 135 are typically positioned at corresponding locations. In this specification, "positioned at corresponding locations" means that the non-polarizing portion and the non-anti-glare portion overlap when viewed from above the optical film. The non-polarizing portion and the non-anti-glare portion can be positioned at any suitable location depending on the purpose. Typically, when the optical film is applied to an image display device, the non-polarizing portion and the non-anti-glare portion can be positioned corresponding to the camera section of the image display device. With this configuration, when the optical film is applied to an image display device, the impact on the camera performance of the image display device can be minimized. The non-polarizing portion and the non-anti-glare portion can each be formed in only one or more (e.g., two, three, four, or five) of the optical film (cut to the size and shape corresponding to the applied image display device) as the final product.

[0043] The following describes the constituent elements of optical laminates.

[0044] B. Optical thin films

[0045] B-1. Polarizer

[0046] A polarizer typically has a polarizing section and an unpolarizing section. The polarizing section is essentially all of the part except for the unpolarizing section.

[0047] Polarizers are typically made of a polyvinyl alcohol (PVA)-based resin film containing a dichroic substance (such as iodine). Examples of PVA-based resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and partially saponified ethylene-vinyl acetate copolymers.

[0048] The PVA-based resin preferably includes an acetyl-modified PVA-based resin. With this configuration, a polarizer with desired mechanical strength can be obtained. When the total PVA-based resin is set at 100% by weight, the blending amount of the acetyl-modified PVA-based resin is preferably 5% to 20% by weight, more preferably 8% to 12% by weight. With a blending amount within this range, a polarizer with superior mechanical strength can be obtained.

[0049] The polarizer preferably contains iodides or sodium chloride (sometimes collectively referred to as halides). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The content of halide in the polarizer is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of the PVA-based resin. The halide is mixed into a coating solution forming a PVA-based resin layer as a precursor for the polarizer in the manufacturing method described later, and can ultimately be introduced into the polarizer. By introducing halide into the polarizer, the orientation of PVA molecules in the polarizer can be improved, thus enabling the realization of a polarizer with excellent optical properties (typically, a combination of high polarization degree and high monomer transmittance).

[0050] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of a single polarizer is preferably 41.0% to 46.0%, more preferably 42.0% to 45.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. According to embodiments of the present invention, even if the transmittance of a single polarizer is in the range described above, the degree of polarization can be maintained within such a range.

[0051] The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. If the thickness of the polarizer is within the range described above, curling during heating can be effectively suppressed, and good appearance durability during heating can be obtained.

[0052] The polarizer can be manufactured by any suitable method. For example, the resin film forming the polarizer can be a single-layer resin film or a laminate of two or more layers.

[0053] Specific examples of polarizers composed of single-layer resin films include polarizers obtained by dyeing and stretching hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films using dichroic substances such as iodine and dichroic dyes; and polyene-based oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA-based films with iodine and then uniaxially stretching them are preferred.

[0054] The aforementioned dyeing using iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA-based film may undergo swelling treatment, crosslinking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA-based film in water for washing before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be removed, but the PVA-based film can also swell to prevent uneven dyeing.

[0055] Specific examples of polarizers obtained using laminates include those using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or those using a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizer from the PVA-based resin layer. In this embodiment, it is preferable to form a polyvinyl alcohol (PVA) resin layer comprising a halide and a polyvinyl alcohol resin on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, as needed, further include air stretching the laminate at a high temperature (e.g., above 95°C) before stretching in the aqueous boric acid solution. Furthermore, in this embodiment, it is preferable that the laminate is subjected to a drying shrinkage treatment, which causes it to shrink by more than 2% in the width direction by heating while being transported along the length direction. Typically, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, achieving high optical properties. Additionally, by simultaneously improving the orientation of PVA beforehand, problems such as reduced orientation and dissolution of PVA can be prevented when immersed in water during subsequent dyeing and stretching processes, achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, compared to the case where the PVA-based resin layer does not contain halides, orientation disorder of polyvinyl alcohol molecules and reduction of orientation can be suppressed. Therefore, the optical properties of the polarizer obtained by immersing the laminate in liquid through dyeing and underwater stretching treatments can be improved. Furthermore, the drying shrinkage treatment shrinks the laminate in the width direction, thereby improving optical properties. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or it can be used by laminating any suitable protective layer corresponding to the purpose on the peeled surface from which the resin substrate has been peeled off, or on the surface opposite to the peeled surface. Detailed methods for manufacturing such a polarizer are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0056] The non-polarized portion 125 can be a portion that is not dyed with a dichroic substance, or it can be a portion that has been dyed with a dichroic substance and then decolorized by any suitable method (decolorized portion). The non-polarized portion is preferably a decolorized portion. By decolorizing after dyeing, the strength of the non-polarized portion can be improved.

[0057] The top view shape of the non-polarizing part can be any suitable shape as long as it does not adversely affect the camera performance of the image display device using optical thin films. Specific examples of the top view shape of the non-polarizing part include circles, ellipses, squares, rectangles, rhombuses, polygons, and irregular shapes.

[0058] The transmittance of the non-polarized portion (e.g., transmittance measured using light at a wavelength of 550 nm at 23°C) is preferably 50% or more, more preferably 60% or more, even more preferably 75% or more, and particularly preferably 90% or more. Such transmittance ensures the desired transparency of the non-polarized portion. As a result, when the polarizer is configured such that the non-polarized portion corresponds to the camera section of the image display device, adverse effects on the camera's shooting performance can be suppressed.

[0059] Preferably, the non-polarized portion is a low-concentration portion with a relatively low content of dichroic material. Specifically, it is a low-concentration portion with a lower content of dichroic material than the polarized portion. With this configuration, compared to forming the non-polarized portion mechanically (e.g., by using a carving knife, plotter, water jet, etc.), quality problems such as cracks, delamination (interlayer peeling), and excess adhesive can be avoided. Furthermore, because the low-concentration portion itself has a low content of dichroic material, the transparency of the non-polarized portion can be well maintained compared to forming the non-polarized portion by decomposing the dichroic material using a laser or similar method.

[0060] The aforementioned low-concentration portion refers to the portion where the content of the dichroic substance is lower than that of the polarizing portion. The content of the dichroic substance in the low-concentration portion is preferably 1.0% by weight or less, more preferably 0.5% by weight or less, and even more preferably 0.2% by weight or less. When the content of the dichroic substance in the low-concentration portion is within such a range, the desired transparency can be sufficiently imparted to the low-concentration portion. For example, when the low-concentration portion corresponds to the camera section of an image display device, excellent imaging performance can be achieved from both the viewpoints of brightness and hue. On the other hand, the lower limit value of the dichroic substance content in the low-concentration portion is generally below the detection limit value. It should be noted that when iodine is used as the dichroic substance, the iodine content is determined, for example, based on the X-ray intensity measured by fluorescence X-ray analysis, using a standard curve prepared in advance using a standard sample.

[0061] The difference between the content of dichroic material in the polarization section and the content of dichroic material in the low-concentration section is preferably 0.5% by weight or more, and more preferably 1% by weight or more. When the content difference is within such a range, a low-concentration section with desired transparency can be formed.

[0062] B-2. Protective layer

[0063] Protective layers 122 and 123 are each composed of any suitable resin film. Representative materials constituting the resin film include cellulose resins such as triacetyl cellulose (TAC), cyclic olefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. As a representative example of (meth)acrylic resins, (meth)acrylic resins having a lactone ring structure can be cited. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Application Publication Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005-146084. These publications are cited in this specification for reference. From the viewpoint of ease of processing irregular shapes, cellulose-based resins are preferred, and TAC is more preferred. From the viewpoint of obtaining polarizers with low moisture permeability and excellent durability, cyclic olefin-based resins and (meth)acrylic resins are preferred.

[0064] In one embodiment, the protective layer 123 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm, and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0065] The thicknesses of the protective layers 122 and 123 are preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0066] B-3. ​​Anti-glare layer

[0067] The anti-glare layer 130 typically has an anti-glare portion and a non-anti-glare portion. The anti-glare portion is essentially all of the part except for the non-anti-glare portion.

[0068] The anti-glare layer can be of any suitable composition as long as it has the desired anti-glare function. Specifically, the anti-glare layer can be formed from a curable resin composition comprising a binder resin and particles. The binder resin typically comprises a curable compound. Examples of curable compounds include, for instance, multifunctional monomers, oligomers derived from such multifunctional monomers, or prepolymers. The curable resin composition may, as needed, contain a photopolymerization initiator.

[0069] Examples of granules include inorganic granules and organic granules. Specific examples of inorganic granules include silica granules, titanium dioxide granules, alumina granules, zinc oxide granules, tin oxide granules, calcium carbonate granules, barium sulfate granules, talc granules, kaolin granules, and calcium sulfate granules. Specific examples of organic granules include polymethyl methacrylate resin granules (PMMA granules), silicone resin granules, polystyrene resin granules, polycarbonate resin granules, styrene acrylic resin granules, benzoguanamine resin granules, melamine resin granules, polyolefin resin granules, polyester resin granules, polyamide resin granules, polyimide resin granules, and polyvinyl fluoride resin granules. Granules can be used alone or in combination.

[0070] The weight-average particle size is preferably 1 μm to 10 μm, more preferably 2 μm to 7 μm. The weight-average particle size can be determined, for example, by the Coulter counting method.

[0071] The refractive index of the particles is preferably 1.1 to 1.9, more preferably 1.2 to 1.7. Examples of particles with such a refractive index include silicone particles, polystyrene particles, polymethyl methacrylate, and copolymers of styrene and methacrylic acid. Furthermore, the difference (n1-n2) between the refractive index n1 of the particles and the refractive index n2 of the binder resin is preferably -0.01 or less, more preferably -0.03 or less, and even more preferably -0.05 or less. With this configuration, an anti-glare layer with excellent transparency can be obtained.

[0072] The amount of particles mixed relative to 100 parts by weight of the binder resin is preferably 0.2 to 12 parts by weight, more preferably 0.5 to 12 parts by weight.

[0073] The thickness of the anti-glare layer is preferably 1μm to 20μm, more preferably 3μm to 15μm, and even more preferably 4μm to 10μm.

[0074] The anti-glare layer (essentially the anti-glare part) typically has an uneven surface. The arithmetic mean roughness Ra of the uneven surface is preferably 0.01 μm to 1 μm, more preferably 0.05 μm to 0.5 μm. The maximum height Ry of the uneven surface is preferably 0.5 μm to 5 μm, more preferably 1 μm to 3 μm. The average tilt angle θa of the uneven surface is preferably 0.3° to 5°, more preferably 0.5° to 4°. With such a configuration, an anti-glare layer with sufficient anti-glare function and suppressing adverse effects on the visual recognizability of the image display device can be obtained. The definitions of arithmetic mean roughness Ra, maximum height Ry, and average tilt angle θa are based on JIS B 0601 (1994 edition). Furthermore, these characteristic values ​​can be measured using a stylus-type surface roughness measuring instrument (e.g., the high-precision micro-shape measuring instrument manufactured by Kosaka Research Institute, trade name "Surfcorder ET4000"). It should be noted that the average tilt angle θa is derived from θa = tan -1 The value of Δa is defined by the formula. Δa is the sum of the differences (height h) between the vertices of adjacent convex parts and the lowest points of concave parts in the roughness curve specified in JIS B 0601 (1994 edition), divided by the reference length L of the roughness curve. That is, it is expressed by the formula Δa = (h1 + h2 + h3 + ... + hn) / L. It should be noted that non-anti-glare parts can have flat surfaces.

[0075] Since the anti-glare layer can have a specific uneven surface as described above, the outermost surface of the optical film can also have an uneven surface corresponding to that uneven surface. According to an embodiment of the present invention, even when a surface protective film is temporarily adhered to an optical film having such a specific uneven surface, the generation of bubbles at the ends of the surface protective film after autoclave treatment can be suppressed.

[0076] The haze of the anti-glare layer is 5.0% or more, preferably 15% to 55%, more preferably 25% to 45%, and even more preferably 30% to 40%. When the haze of the anti-glare layer is within this range, it can impart good anti-glare function when the optical thin film is applied to an image display device. The haze of the non-anti-glare portion can typically be equivalent to that of the anti-reflective layer described later. The haze of the non-anti-glare portion is, for example, less than 1.0%, preferably 0.8% or less, more preferably 0.5% or less, and even more preferably 0.3% or less. Lower haze is more preferred, and the lower limit of haze can be, for example, 0.1%.

[0077] B-4. Anti-reflective layer

[0078] The anti-reflective layer can be of any suitable composition as long as it has the desired anti-reflective properties. Specifically, the anti-reflective layer can be a cured layer of a curable resin composition or a layer formed by a dry process.

[0079] As representative components of antireflective layers formed by dry processes, examples include (1) a single layer of low refractive index layer with an optical film thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (2) a stack of layers having a medium refractive index layer, a high refractive index layer and a low refractive index layer in sequence from the polarizer side; and (3) a multilayer stack of alternating high refractive index layer and low refractive index layer.

[0080] Examples of materials capable of forming low-refractive-index layers include silicon oxide (SiO2) and magnesium fluoride (MgF2). The refractive index of a low-refractive-index layer is typically around 1.35 to 1.55. Examples of materials capable of forming high-refractive-index layers include titanium oxide (TiO2), niobium oxide (Nb2O3 or Nb2O5), indium tin oxide (ITO), tin oxide (ATO), and ZrO2-TiO2. The refractive index of a high-refractive-index layer is typically around 1.60 to 2.20. Examples of materials capable of forming medium-refractive-index layers include titanium oxide (TiO2), and mixtures of materials capable of forming low-refractive-index layers and materials capable of forming high-refractive-index layers (e.g., a mixture of titanium oxide and silicon oxide). The refractive index of a medium-refractive-index layer is typically around 1.50 to 1.85. The thicknesses of the low-refractive-index, medium-refractive-index, and high-refractive-index layers can be set to achieve an appropriate optical thin film thickness corresponding to the layer structure of the anti-reflective layer and the desired anti-reflective performance.

[0081] Specific examples of dry processes include PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). PVD methods include vacuum evaporation, reactive evaporation, ion beam assisted deposition, sputtering, and ion plating. CVD methods include plasma CVD. Sputtering is preferred because it allows for more uniform film formation with smaller thickness variations.

[0082] The thickness of the antireflective layer formed by the dry process is, for example, about 20nm to 300nm.

[0083] As described above, the antireflective layer can be a cured layer of a curable resin composition. The curable resin composition contains a curable resin. Typical examples of curable resins include thermosetting resins, ultraviolet-curing resins, light (visible light) curable resins, and electron beam curable resins. Examples of curable resins include silicone resins, polyester resins, polyether resins, epoxy resins, polyurethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiol polyene resins. Furthermore, the curable resin can be a curable compound having acrylate and / or methacrylate groups that cure by heat, light (ultraviolet light, etc.), or electron beams. Specific examples include oligomers or prepolymers such as acrylates and / or methacrylates of polyfunctional compounds like polyols. The curable resin can be used alone or in combination of two or more. The curable resin composition may further include reactive diluents, fluorine-containing additives, hollow particles, and / or solid particles, depending on the purpose. Commercially available products can be used as such antireflective layers. As a specific example of commercially available products, one could cite the AR film manufactured by Dexerials Co., Ltd.

[0084] The thickness of the antireflective layer, which is the curing layer of the curable resin composition, can be, for example, 0.1 μm to 50 μm, or, for example, 0.3 μm to 40 μm, or, for example, 0.5 μm to 30 μm, or, for example, 1.0 μm to 20 μm, or, for example, 2.0 μm to 10 μm.

[0085] The reflectivity of the anti-reflective layer is preferably 1.5% or less, more preferably 1.3% or less, and even more preferably 1.0% or less. Lower reflectivity is preferred, with a lower limit of, for example, 0.2%. Such a reflectivity prevents the reflection of external light.

[0086] The haze of the anti-reflective layer is less than 1.0%, preferably less than 0.8%, more preferably less than 0.5%, and even more preferably less than 0.3%. Lower haze is more preferred, and the lower limit of haze can be, for example, 0.1%. When the haze of the anti-reflective layer is in such a range, when the optical thin film is applied to an image display device, anti-reflective function can be imparted without adversely affecting the display performance.

[0087] B-5. Anti-fouling layer

[0088] As an antifouling layer, any suitable composition can be used as long as the antifouling effect can be achieved. The antifouling layer may contain, for example, fluorinated silane compounds (e.g., alkoxysilane compounds with perfluoropolyether groups) or fluorinated organic compounds.

[0089] The thickness of the antifouling layer is preferably 5 nm to 13 nm, more preferably 5 nm to 10 nm. The refractive index of the antifouling layer can be, for example, 1.0 to 2.0. The antifouling layer preferably exhibits hydrophobicity with a water contact angle of 110 degrees or more.

[0090] C. Surface protective film

[0091] C-1. Overview of Surface Protective Films

[0092] As described above, the surface protective film 100 includes a substrate film 10 and an adhesive layer 20.

[0093] The descent of the surface protective film is, for example, 52 mm or less, preferably 50 mm or less, more preferably 48 mm or less, even more preferably 46 mm or less, particularly preferably 44 mm or less, and especially preferably 42 mm or less. If the descent of the surface protective film is within this range, sufficient strength as a surface protective film can be ensured. On the other hand, the descent can be, for example, 5 mm or more, and furthermore, for example, 10 mm or more. The descent can be measured, for example, as follows: The surface protective film is cut into 50 mm × 100 mm pieces, exposing the adhesive layer, as a test sample. 20 mm of the 100 mm length is placed on a stage, and the test sample is attached to the stage with 80 mm protruding from the stage. A weight is placed on it for fixation. The amount by which the protruding portion descends from the stage is measured as the descent.

[0094] In one embodiment, the peel force between the substrate film 10 and the adhesive layer 20 is greater than the peel force between the adhesive layer 20 and the optical film 200. This configuration helps suppress poor peeling when the surface protective film is removed. More specifically, the difference between the peel force between the substrate film 10 and the adhesive layer 20 and the peel force between the adhesive layer 20 and the optical film 200 is preferably 1.0 N / 25 mm or more, more preferably 2.0 N / 25 mm or more, and even more preferably 3.0 N / 25 mm or more. This difference can, for example, be 30 N / 25 mm or less. It should be noted that the peel force between the substrate film 10 and the adhesive layer 20 can, for example, be 3.0 N / 25 mm to 30 N / 25 mm; and the peel force between the adhesive layer 20 and the optical film 200 can, for example, be 0.001 N / 25 mm to 2.0 N / 25 mm.

[0095] In one embodiment, the initial peel force when peeling off the surface protective film is, for example, 10.0 N or less, and further, for example, 5.0 N or less, and further, for example, 3.0 N or less, and further, for example, 2.0 N or less, and further, for example, 1.0 N or less, and further, for example, 0.8 N or less, and further, for example, 0.6 N or less, and further, for example, 0.5 N or less. The lower limit of the initial peel force can be, for example, 0.01 N. When the initial peel force is in such a range, the surface protective film can be easily peeled off, and poor peeling can be significantly suppressed. The initial peel force can be measured, for example, according to JIS Z 0237. Specifically, the peel force when a pick-up tape is attached to the surface of the surface protective film of the optical laminate along the peel direction and peeled off at a stretch direction of 90° using the pick-up tape can be measured as the initial peel force. The width of the pick-up tape can be, for example, 10 mm, and the stretching speed can be, for example, 300 mm / min.

[0096] The following is a detailed explanation of the components of a surface protective film.

[0097] C-2. Substrate film

[0098] The substrate film can be made of any suitable material as long as the effects of the embodiments of the present invention can be obtained. Specific examples of constituent materials include polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); cellulose polymers such as diacetylcellulose and triacetylcellulose; polycarbonate polymers; (meth)acrylic polymers such as polymethyl methacrylate; and cyclic olefin polymers such as polynorbornene. They can be used alone or in combination of two or more. Polyester polymers are preferred, and polymers with excellent optical properties (e.g., transparency), mechanical strength, thermal stability, moisture barrier properties, isotropy, flexibility, and dimensional stability are preferred. In particular, polyester films with low stiffness can easily achieve the above-mentioned desired properties. PET is a representative example of such a polyester polymer. The properties of the polyester film can be controlled by adjusting the type and combination of polycarboxylic acid components and polyol components. For example, PET and PEN can be used in combination as constituent materials of the substrate film.

[0099] Other examples of materials constituting the substrate film include: styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; vinyl chloride-based polymers; amide-based polymers such as nylon 6, nylon 6,6, and aromatic polyamides; imide-based polymers; sulfone-based polymers; polyethersulfone-based polymers; polyetheretherketone-based polymers; polyphenylene sulfide-based polymers; vinyl alcohol-based polymers; vinylidene chloride-based polymers; vinyl butyral-based polymers; aromatic ester-based polymers; polyoxymethylene-based polymers; and epoxy-based polymers. These can be used individually or in combination of two or more.

[0100] The tensile modulus of the substrate film is, for example, 2300 MPa or less, preferably 1500 MPa or less, more preferably 1300 MPa or less, even more preferably 10 MPa to 1300 MPa, and particularly preferably 100 MPa to 1300 MPa. When the tensile modulus of the substrate film is within this range, the aforementioned desired characteristics can be easily achieved. It should be noted that the tensile modulus is measured according to JIS K 7161.

[0101] The thickness of the substrate film is, for example, 20 μm to 100 μm, or, for example, 25 μm to 80 μm, or, for example, 30 μm to 50 μm. When the thickness of the substrate film is within such a range, poor peeling can be prevented very well when peeling off the surface protective film.

[0102] C-3. Adhesive layer

[0103] As the adhesive layer 20, any suitable composition can be adopted as long as the desired contact angle with hexadecane and water can be achieved. The adhesive constituting the adhesive layer typically includes a base polymer, a crosslinking agent, and, as needed, a silane coupling agent and / or additives. Specific examples of adhesives based on the base polymer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. The base polymer can be used alone or in combination of two or more. The base polymer is preferably a (meth)acrylic polymer (i.e., the adhesive layer is preferably composed of an acrylic adhesive). It should be noted that (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0104] (Meth)acrylate polymers contain alkyl (meth)acrylates as the main monomer component. Alkyl (meth)acrylates may be present in at least 50% by weight, more preferably 60% by weight, further preferably 70% by weight, particularly preferably 80% by weight, and especially preferably 90% by weight or more of all monomer components forming the (meth)acrylate polymer.

[0105] Alkyl methacrylates are preferably linear or branched alkyl esters with 1 to 18 carbon atoms. More preferably, the alkyl group has 2 to 10 carbon atoms, and even more preferably 3 to 8 carbon atoms. Examples of alkyl methacrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate. Alkyl methacrylates can be used alone or in combination.

[0106] (Meth)acrylic polymers may contain comonomers capable of copolymerizing with alkyl (meth)acrylates as monomer components. Examples of comonomers include carboxyl-containing monomers and hydroxyl-containing monomers. Carboxyl-containing monomers are compounds that contain a carboxyl group and polymerizable unsaturated double bonds such as (meth)acryloyl or vinyl groups in their structure. Examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Acrylic acid is preferred. Hydroxyl-containing monomers are compounds that contain a hydroxyl group and polymerizable unsaturated double bonds such as (meth)acryloyl or vinyl groups in their structure. Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. From the viewpoint of adjusting the properties of the adhesive layer, comonomers other than those mentioned above may be used. Examples of such comonomers include amino-containing monomers, amide-containing monomers, multifunctional monomers, cyclizable monomers, sulfonic acid-containing monomers, phosphate-containing monomers, (meth)acrylates with alicyclic hydrocarbon groups, (meth)acrylates with aromatic hydrocarbon groups, vinyl esters, aromatic vinyl compounds, olefins, dienes, and vinyl ethers. Comonomers can be used alone or in combination.

[0107] As crosslinking agents, organic crosslinking agents and multifunctional metal chelates can be used. Examples of organic crosslinking agents include isocyanate-based, peroxide-based, epoxy-based, and imine-based crosslinking agents. Multifunctional metal chelates are formed by covalent or coordination bonding of multivalent metals with organic compounds.

[0108] The amount of crosslinking agent can be, for example, 0.01 to 5 parts by weight relative to 100 parts by weight of the base polymer.

[0109] Silane coupling agents preferably contain reactive functional groups. The reactive functional groups in silane coupling agents are typically functional groups other than anhydride groups. Examples of functional groups other than anhydride groups include, for example, epoxy, mercapto, amino, isocyanate, isocyanurate, vinyl, styryl, acetoacetyl, urea, thiourea, (meth)acryloyl, heterocyclic groups, and combinations thereof. Silane coupling agents containing reactive functional groups can be used alone or in combination.

[0110] The amount of silane coupling agent containing reactive functional groups can be, for example, 0.001 to 2 parts by weight relative to 100 parts by weight of the base polymer.

[0111] The adhesive layer (which is essentially the adhesive constituting the adhesive layer) may preferably contain an oxyalkylene compound. Examples of oxyalkylene compounds include ionic surfactants, nonionic surfactants, and oxyalkylene-modified organosilicones.

[0112] The amount of the oxyalkylene compound can be, for example, 0.005 to 1.0 parts by weight relative to 100 parts by weight of the base polymer.

[0113] The adhesive layer (essentially the adhesive that constitutes the adhesive layer) may preferably contain an antistatic agent (conductive agent). Ionic compounds are representative examples of antistatic agents.

[0114] Ionic compounds can be, for example, organic cation-anion salts. Representative examples of cations constituting the cation portion of organic cation salts include organonium compounds where onionions are formed through substitution of organic groups. Examples of onions in organonium compounds include nitrogen-containing onions, sulfur-containing onions, and phosphorus-containing onions. Nitrogen-containing and sulfur-containing onions are preferred. Examples of nitrogen-containing onions include ammonium cations, piperidinium cations, pyrrolidine onion cations, pyridinium cations, cations having a pyrroline skeleton, cations having a pyrrole skeleton, imidazolium cations, tetrahydropyrimidine onion cations, dihydropyrimidine onion cations, pyrazolium onion cations, and pyrazoline onion cations. Examples of sulfur-containing onions include sulfonium cations. Examples of phosphorus-containing onions include phosphonium cations. Examples of organic groups in organonium compounds include alkyl, alkoxy, and alkenyl groups. Preferred examples of organo-cations include tetraalkylammonium cations (e.g., tributylmethylammonium cations), alkylpiperidinium cations, and alkylpyrrolidine-onium cations. The anions constituting the anionic portion of the organic cation salt are as described regarding the anions constituting the anionic portion of the inorganic cation. Preferred organic cation salts that can be used in embodiments of the invention are 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

[0115] The amount of antistatic agent mixed with 100 parts by weight of the base polymer can be, for example, 0.005 parts by weight to 1.0 parts by weight.

[0116] Specific examples of additives include colorants, pigments and other powders, dyes, plasticizers, thickeners, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, granules, and foils. Additionally, within controllable limits, redox systems with added reducing agents can be used. The type, quantity, combination, and content of additives can be appropriately determined according to the intended purpose.

[0117] By adjusting the type, quantity, combination and mixing ratio of monomers in the base polymer that forms the adhesive, the type and mixing amount of crosslinking agent, the type, quantity, combination and mixing amount of additives, as well as the reaction temperature and reaction time, adhesives with desired properties corresponding to the purpose can be prepared.

[0118] The thickness of the adhesive layer is, for example, 5 μm to 50 μm, or more specifically, 10 μm to 40 μm, or even 10 μm to 30 μm. When the thickness of the adhesive layer is within such a range, the aforementioned desired characteristics of the surface protective film can be easily achieved.

[0119] The indentation hardness of the adhesive layer is, for example, 1.00 MPa or less, preferably 0.74 MPa or less, more preferably 0.50 MPa or less, even more preferably 0.35 MPa or less, particularly preferably 0.25 MPa or less, and especially preferably 0.10 MPa or less. The indentation hardness of the adhesive layer can be, for example, 0.02 MPa or more, and further, for example, 0.04 MPa or more. The indentation hardness can be determined, for example, by a nanoindentation test.

[0120] The glass transition temperature (Tg) of the adhesive layer (which is essentially the adhesive constituting the adhesive layer) is preferably below -60°C, more preferably below -62°C, even more preferably below -64°C, and particularly preferably below -66°C. The Tg of the adhesive can, for example, be above -70°C.

[0121] C-4. Examples of variations of surface protective films

[0122] The surface protective film may, for example, have two substrate films and two adhesive layers. Specifically, the surface protective film may have a first substrate film, a second substrate film adhered to the first substrate film by means of a first adhesive layer, and a second adhesive layer disposed on the side of the second substrate film opposite to the first adhesive layer. In this case, the second adhesive layer serves as an adhesive layer for temporarily adhering the surface protective film to the optical film. The first adhesive layer may have any suitable configuration. The first substrate film and the second substrate film may have the same configuration or different configurations.

[0123] Example

[0124] The present invention will now be specifically described through examples, but the present invention is not limited to these examples. It should be noted that the methods for measuring each characteristic are as described below. Furthermore, unless otherwise specified, "%" and "parts" in the examples are based on weight.

[0125] (1) Indentation hardness of adhesive layer

[0126] The indentation hardness of the adhesive layer was determined by nanoindentation testing. Specifically, the surface protective films obtained in the examples and comparative examples were cut into pieces approximately 1 cm × 1 cm, fixed to a specified support, and the release liner was peeled off to expose the adhesive layer as test samples. A Triboindenter (manufactured by Hysitron Inc.) was used as the apparatus, and a Conical (spherical: radius of curvature 10 μm) indenter was used as the indenter. A single indentation measurement was performed at a measurement temperature of 25°C. The indentation depth was set to 1300 nm. The indentation hardness (MPa) of the adhesive layer was calculated based on the following formula.

[0127] Indentation hardness = Load at maximum indentation (maximum load Pmax) / Area of ​​contact between indenter and specimen (projected contact area A)

[0128] (2) Contact angle

[0129] The contact angles were measured as follows for the surface of the protective film side (essentially an anti-reflective layer or anti-fouling layer) of the optical films used in the embodiments and comparative examples, and for the surface of the adhesive layer of the protective films used in the embodiments and comparative examples. Hexadecane and water were used as the measuring liquid. A droplet with a diameter of 1.5 mm was formed at the needle tip, and the droplet was brought into contact with the surface of the optical film or adhesive layer. The stationary contact angle between the droplet and the surface was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.).

[0130] (3) Arithmetic mean roughness

[0131] The optical thin film was placed on a white interferometer (Zygo NewView 7300) with its surface facing the objective lens. Interference data of the optical thin film surface were measured under the following conditions to obtain a two-dimensional image. The arithmetic mean roughness was then calculated from this image. It should be noted that the arithmetic mean roughness is obtained by averaging data from three randomly selected points.

[0132] Measurement conditions for white light interferometer

[0133] Objective lenses: ×10

[0134] Internal lens: ×1.0

[0135] Resolution: 1.09μm

[0136] Measured field area: 0.3641 mm 2

[0137] Removed: Cylinder

[0138] (4) Bubbles after autoclave treatment

[0139] The optical laminates obtained in the examples and comparative examples were treated in an autoclave set at 30°C and 0.5 MPa for 15 minutes. Then, they were left to stand at 23°C and 50% relative humidity, and the number of bubbles at the interface between the surface protective film and the optical film was visually confirmed after 1 day and 3 days.

[0140] [Manufacturing Example 1: Preparation of the adhesive constituting the adhesive layer]

[0141] In a flask equipped with a reflux reflux device, stirrer, nitrogen inlet tube, and thermometer, 96 parts of 2-ethylhexyl acrylate (2EHA) and 4 parts of hydroxyethyl acrylate (HEA), along with ethyl acetate (polymerization solvent), were added at a solids concentration of 40%. Then, 0.2 parts of azobisisobutyronitrile (AIBN) was added as a polymerization initiator. Nitrogen gas was introduced while stirring slowly, and the liquid temperature in the flask was maintained at approximately 65°C for 6 hours for polymerization. The mixture was then cured at 70°C for 4 hours to obtain a solution of acrylic polymer 1. The weight-average molecular weight (Mw) of the obtained acrylic polymer 1 was 540,000. Furthermore, the Tg derived from the Fox equation was -68.3°C.

[0142] The above-obtained acrylic polymer 1 solution (40%) was diluted to 20% with ethyl acetate. 3 parts (0.3 parts solids) of a solution obtained by diluting an ionic compound (1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, manufactured by Kanto Chemical Co., Ltd., CIL-312) to 10% with ethyl acetate were added to 500 parts (100 parts solids). 0.3 parts (0.3 parts solids) of polyether-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-6004) as an organosilicon component, 2.5 parts (2.5 parts solids) of toluene diisocyanate (manufactured by Mitsui Chemicals Co., Ltd., TAKENATE D-101E) as a crosslinking agent, and 3 parts (0.03 parts solids) of dioctyltin dilaurate (1% ethyl acetate solution) as a crosslinking catalyst were mixed and stirred to prepare an adhesive composition (solution) (adhesive 1).

[0143] [Manufacturing Example 2: Preparation of the Adhesive Constituting the Adhesive Layer]

[0144] The acrylic polymer 1 solution (40%) obtained in Manufacturing Example 1 was diluted to 20% with ethyl acetate. 1.5 parts (0.15 parts solids) of a solution obtained by diluting an oxyalkylene compound (KH-10, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) to 10% with ethyl acetate, 4 parts (4 parts solids) of hexamethylene diisocyanate (manufactured by Tosoh Corporation, Coronate HX) as a crosslinking agent, and 3 parts (0.03 parts solids) of dioctyltin dilaurate (1% ethyl acetate solution) as a crosslinking catalyst were added and mixed to prepare the adhesive composition (solution) (Adhesive 2).

[0145] [Manufacturing Example 3: Preparation of the Adhesive Constituting the Adhesive Layer]

[0146] In a flask equipped with a reflux reflux device, stirrer, nitrogen inlet tube, and thermometer, 95 parts of n-butyl acrylate (BA) and 5 parts of acrylic acid (AA) as monomers, along with ethyl acetate (polymerization solvent), were added at a solids concentration of 30%. Then, 0.2 parts of azobisisobutyronitrile (AIBN) as the polymerization initiator were added. Nitrogen gas was introduced while stirring slowly, and the liquid temperature in the flask was maintained at approximately 63°C for 7 hours to obtain a solution of acrylic polymer 2. The weight-average molecular weight (Mw) of the obtained acrylic polymer 2 was 630,000. Furthermore, the Tg derived from the Fox equation was -49.3°C.

[0147] The above-obtained acrylic polymer 2 solution (40%) was diluted to 20% with ethyl acetate. 6 parts (6 parts solid) of a multifunctional epoxy resin (manufactured by Mitsui Chemicals Co., Ltd., TETRAD-C) as a crosslinking agent were added to 500 parts (100 parts solid) of the solution and mixed to prepare an adhesive composition (solution) (adhesive 3).

[0148] [Manufacturing Example 4: Fabrication of a Surface Protective Film]

[0149] In Example 1, the adhesive 1 obtained by coating one surface of a PET film (38 μm thick) was dried at 130°C for 1 minute to remove the solvent and form an adhesive layer (20 μm thick). Then, the surface of the adhesive layer was covered with a release liner and aged at 50°C for 2 days to obtain a surface protective film SPV1 having a PET film / adhesive layer structure.

[0150] [Manufacturing Example 5: Fabrication of a Surface Protective Film]

[0151] In Example 2, the adhesive 2 obtained by coating one surface of a PET film (38 μm thick) was dried at 130°C for 1 minute to remove the solvent and form an adhesive layer (20 μm thick). Then, the surface of the adhesive layer was covered with a release liner and aged at 50°C for 2 days to obtain a surface protective film SPV2 having a PET film / adhesive layer structure.

[0152] [Manufacturing Example 6: Fabrication of a Surface Protective Film]

[0153] The adhesive 3 obtained in Example 3, which involves coating one surface of a PET film (38 μm thick), was dried at 130°C for 1 minute to remove the solvent and form an adhesive layer (21 μm thick). Then, a release liner was used to cover the surface of the adhesive layer, and the film was aged at 50°C for 2 days to obtain a surface protective film SPV3 having a PET film / adhesive layer structure.

[0154] [Manufacturing Example 7: Fabrication of Optical Thin Films]

[0155] 1. Fabrication of the polarizer

[0156] As a thermoplastic resin substrate, a strip-shaped amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) with a Tg of about 75 °C is used to perform corona treatment on one side of the resin substrate.

[0157] 13 parts by weight of potassium iodide were added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1. The resulting product was dissolved in water to prepare a PVA aqueous solution (coating solution).

[0158] The above-mentioned PVA aqueous solution is coated on the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

[0159] The resulting laminate was stretched uniaxially in the longitudinal direction (length direction) to 2.4 times its original size in an oven at 130°C (air-assisted stretching treatment).

[0160] Next, the laminate was immersed in an insoluble bath (an aqueous solution of boric acid prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insoluble treatment).

[0161] Next, the polarizer is immersed in a staining bath (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the final polarizer's monomer transmittance (Ts) becomes the desired value (staining treatment).

[0162] Next, it was immersed in a crosslinking bath at a liquid temperature of 40°C (an aqueous solution of boric acid prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (crosslinking treatment).

[0163] Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4 wt% and potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, uniaxial stretching (water stretching treatment) was performed between rollers with different circumferential speeds along the longitudinal direction (length direction) with a total stretching ratio of 5.5 times.

[0164] Then, the laminate was immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution of 4 parts by weight of potassium iodide mixed with 100 parts by weight of water) (cleaning treatment).

[0165] Then, while drying in an oven maintained at approximately 90°C, it comes into contact with SUS heated rollers maintained at a surface temperature of approximately 75°C (drying shrinkage treatment).

[0166] This process forms a polarizer with a thickness of approximately 5 μm on the resin substrate, resulting in a strip-shaped polarizer with a resin substrate / polarizer configuration. The polarizer's single-unit transmittance Ts is 43.3%. The polarizer has an absorption axis along its length. Hereinafter, the absorption axis direction (length direction) will be designated as the "0° direction," and the transmission axis direction (width direction) will be designated as the "90° direction."

[0167] 2. Fabrication of Polarizing Films

[0168] An HC-COP film is bonded to the surface of the obtained polarizer (the side opposite to the resin substrate) using a UV-curable adhesive. It should be noted that the HC-COP film is a film with an HC layer (4 μm thick) formed on a cyclic olefin resin (COP) film (25 μm thick), bonded with the COP film facing the polarizer side. Next, the resin substrate is peeled off, and a triacetyl cellulose (TAC) film (25 μm thick) is bonded to the peeled surface using a UV-curable adhesive. This process yields a polarizer with the following structure: HC layer / COP film (protective layer) / polarizer / TAC film (protective layer).

[0169] 3. Fabrication of optical thin films

[0170] Prepare 50 parts of UV-curable urethane acrylate resin (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "UA53H-80MB", 80% solid content) and 50 parts of polyfunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat#300", 100% solid content) with pentaerythritol triacrylate as the main component. Relative to 100 parts of the total resin solids content of these resins, 0.5 parts of acrylic acid-styrene copolymer particles (manufactured by Sekisui Chemicals Co., Ltd., trade name "Techpolymer SSX1055QXE"), 1.5 parts of synthetic montmorillonite (manufactured by Kunimine Industries Co., Ltd., trade name "SUMECTON SAN"), 5 parts of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), and 0.1 parts of leveling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", 20% solids content) were mixed. This mixture was diluted with a toluene / cyclopentanone mixed solvent (70 / 30) to a solids content concentration of 40% to prepare a coating liquid.

[0171] A triacetyl cellulose film (manufactured by Konica Minolta, trade name "KC4UA") was prepared as a transparent substrate. The coating solution was applied to the corona-treated surface of the substrate using a wire rod to form a coating film. Next, the substrate with the coating film was heated at 100°C for 1 minute to dry the coating film. Then, it was irradiated with a high-pressure mercury lamp with a cumulative light intensity of 300 mJ / cm². 2 Ultraviolet light is used to cure the coating, creating an anti-glare layer with a thickness of 4 μm. The substrate of the substrate / anti-glare layer laminate is then bonded to the HC layer of the polarizer obtained above, resulting in an optical film 1 having a structure of anti-glare layer (substrate) / HC layer / COP film (protective layer) / polarizer / TAC film (protective layer).

[0172] [Manufacturing Example 8: Fabrication of Optical Thin Films]

[0173] Except for the absence of an anti-fouling layer, the optical film 2 was obtained by operating in the same manner as in manufacturing example 7, having a structure of anti-glare layer ( / substrate) / HC layer / COP film (protective layer) / polarizer / TAC film (protective layer).

[0174] [Manufacturing Example 9: Fabrication of Optical Thin Films]

[0175] No anti-glare layer was formed. Otherwise, the process was carried out in the same manner as in Manufacturing Example 7, and an optical film 3 with a structure of anti-fouling layer / HC layer / COP film (protective layer) / polarizer / TAC film (protective layer) was obtained.

[0176] [Example 1]

[0177] An optical laminate was fabricated by temporarily attaching the surface protective film SPV1 obtained in Manufacturing Example 4 to the surface of the antifouling layer of the optical film 1 obtained in Manufacturing Example 7 using an adhesive layer. The resulting optical laminate was evaluated in (1) to (4) above. The results are shown in Table 1.

[0178] [Examples 2-5, Comparative Example 1, and Reference Examples 1-3]

[0179] As shown in Table 1, the optical thin film and surface protective film were modified, but the optical laminate was fabricated in the same manner as in Example 1. The resulting optical laminate was subjected to the same evaluation as in Example 1.

[0180] The results are shown in Table 1.

[0181]

[0182] Industrial availability

[0183] The optical laminate of the embodiments of the present invention can be used as an intermediate for protecting the optical film in the manufacturing process, inspection process and transportation of the optical film, and in particular it can be used as an intermediate for optical films with uneven surfaces.

Claims

1. An optical laminate, comprising: An optical film having a polarizer including a polarizer and an anti-glare layer disposed on one side of the polarizer; and a surface protective film having a substrate film and an adhesive layer, wherein the adhesive layer is temporarily adhered to the anti-glare layer side of the optical film in a peelable manner. The arithmetic mean roughness Ra of the surface of the protective film side of the optical thin film is 0.15 μm or more. The difference between the hexadecane contact angle of the surface of the protective film side of the optical film and the hexadecane contact angle of the adhesive layer is less than 50°.

2. The optical laminate according to claim 1, wherein, The hexadecane contact angle of the surface of the optical thin film on the surface protection film side is 50° or more, and the water contact angle is 105° or more.

3. The optical laminate according to claim 1, wherein, The difference between the hexadecane contact angle of the surface of the optical film on the surface protective film side and the hexadecane contact angle of the adhesive layer is less than 15°, and the difference between the water contact angle of the surface of the optical film on the surface protective film side and the water contact angle of the adhesive layer is less than 15°.

4. The optical laminate according to claim 1, wherein, The polarizer includes a non-polarizing portion, and the anti-glare layer includes a non-anti-glare portion, with the non-polarizing portion and the non-anti-glare portion disposed at corresponding positions.

5. The optical laminate according to any one of claims 1 to 4, wherein, An anti-reflective layer is also provided on the side of the anti-glare layer opposite to the polarizer, and the surface protective film is temporarily attached to the anti-reflective layer in a peelable manner by means of the adhesive layer.

6. The optical laminate according to claim 5, wherein, The haze of the anti-reflective layer is less than 1.0%, and the haze of the anti-glare layer is greater than 5.0%.

7. The optical laminate according to claim 6, wherein, On the opposite side of the anti-reflective layer to the anti-glare layer, there is also an anti-fouling layer, to which the surface protective film is temporarily adhered in a peelable manner by means of the adhesive layer.

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