Optical laminate and method for producing the same

Abstract

To provide an optical laminate of which the optical unevenness can be suppressed.SOLUTION: An optical laminate 1 is formed by laminating an antireflection layer 4 having reflectance of 1% or less, a transparent protective film layer 3 and a polarization layer 2 in this order, as a lamination order from a visible side when used in a display device. The transparent protective film layer 3 and the polarization layer 2 are directly laminated with each other, and when the transparent protective film layer 3 and the polarization layer 2 are peeled by the following peeling processing method, arithmetic average roughness Ra of the peeled surface of the transparent protective film layer 3 is 0.01 μm or more. [Peeling processing method] The polarization layer side is joined to a glass plate. The transparent protective film layer is slightly floated from the polarization layer by inserting a cutter blade between the transparent protective film layer and the polarization layer, and the floated transparent protective film layer is pinched with tweezers and is peeled little by little.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical laminate and a method for manufacturing the same.

Background Art

[0002] A polarizing plate applied to a display device such as a liquid crystal display device or an organic electroluminescence display device (organic EL display device) is usually formed by laminating a transparent protective film (hereinafter sometimes referred to as a "protective film") on one or both sides of a polarizing film. Further, a retardation film or an antireflection film is laminated according to the application. In recent years, with the thinning and weight reduction of display devices, the thinning of polarizing plates has progressed. For example, in the case of polarizing films, a thin polarizing film having a thickness of about 3 μm to 5 μm has been developed (see Patent Document 1). More recently, consideration has also been given to thinning the protective film (see Non-Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The antireflection film is provided on the outermost surface of the polarizing plate, and is intended to reduce the surface reflected light observed by the viewer when the external light source and the viewer are located on the same side of the polarizing plate. In the study by the present inventors, in a polarizing plate including an antireflection layer, a protective film layer, and a polarizing layer in this order, when the thickness of the protective film layer was thinned to, for example, 30 μm or less, optical unevenness was visually recognized in the polarizing plate. An object of the present invention is to provide an optical laminate capable of suppressing such optical unevenness. Another object of the present invention is to provide a method for manufacturing the optical laminate.

Means for Solving the Problems

[0006] Generally, at the interface between the protective film layer and the polarizing layer, interface reflection occurs due to the difference in refractive index between the two layers. The reflected light due to this interface reflection is observed by the viewer together with the reflected light on the surface of the polarizing plate. Since the reflected light due to the interface reflection is originally weak, when the polarizing plate does not have an antireflection layer, the strong reflected light on the surface of the polarizing plate is mainly visually recognized, and the reflected light due to the interface reflection is hardly visually recognized. On the other hand, when the polarizing plate is provided with an antireflection layer having a reflectance of, for example, about 1% or less with respect to visible light, the reflected light on the surface of the polarizing plate is prevented, so that the reflected light due to the interface reflection becomes relatively strong and is easily visually recognized. In any case, the reflected light due to the interface reflection interferes with the reflected light on the surface of the polarizing plate and reaches the viewer. According to the study by the present inventor, when the polarizing plate is provided with an antireflection layer having the above reflectance, the reflected light due to the interface reflection becomes easily visually recognized, and the above optical unevenness is caused by the variation in the optical path length of the interface reflection due to the thickness unevenness of the protective film layer, and the difference corresponding to the thickness unevenness occurs in the interference between the reflected light due to the interface reflection and the reflected light on the surface of the polarizing plate. Here, the "optical unevenness" refers to a state in which a striped or mottled pattern composed of a plurality of colors is recognized when observing the surface of the polarizing plate.

[0007] To solve this problem, the present invention provides an optical laminate in which an antireflection layer having a reflectance of 1% or less, a transparent protective film layer, and a polarizing layer are laminated in this order as the lamination order from the viewing side when used in a display device. The transparent protective film layer and the polarizing layer are directly laminated to each other. When the transparent protective film layer and the polarizing layer are peeled off by the following peeling process method, the arithmetic mean roughness Ra obtained by the following arithmetic mean roughness Ra measurement of the peeling surface of the transparent protective film layer is 0.01 μm or more. <Peeling process method> Bond the polarizing layer side to a glass plate. Insert a cutter blade between the transparent protective film layer and the polarizing layer to slightly lift the transparent protective film layer from the polarizing layer, and pick up the lifted transparent protective film layer with tweezers and peel it off little by little. <Arithmetic mean roughness Ra measurement> Measuring device: White interferometer Objective lens: 5 times (magnification) Scan range: -30 μm to 10 μm Field of view size: 640 μm × 480 μm Measurement mode: Wave mode Surface correction: Fourth-order processing

[0008] The arithmetic mean roughness Ra after peeling reflects the surface roughness of the bonding surface when the transparent protective film layer was in a state of being bonded to the polarizing layer. Since the surface of the transparent protective film layer is moderately rough, in the optical laminate, the ratio of the light incident from the antireflection layer side and transmitted and scattered by the surface is high. Since the interface reflection becomes weaker by the amount of the incident light transmitted and scattered, the resulting optical unevenness is suppressed.

[0009] The arithmetic mean roughness Ra may be 0.1 μm or less.

[0010] The transparent protective film layer may contain an acrylic resin or a cellulose resin. Also, the thickness of the transparent protective film layer may be 5 μm to 30 μm.

[0011] The thickness of the polarizing layer may be 5 μm to 20 μm.

[0012] Further, the present invention provides a method for manufacturing an optical laminate, which includes a surface roughening step of roughening the arithmetic mean roughness Ra of one side surface of a transparent protective film to be 0.01 μm or more, and a laminating step of laminating the transparent protective film layer and the polarizing layer by laminating the roughened surface of the transparent protective film layer facing the polarizing layer.

[0013] In this manufacturing method, the transparent protective film layer is made of resin, and in the surface roughening step, it is preferable to bring the surface of the transparent protective film layer into contact with a solvent in which the resin is soluble.

Effect of the Invention

[0014] According to the present invention, an optical laminate capable of suppressing optical unevenness can be provided. Further, a method for manufacturing the optical laminate can be provided.

Brief Description of the Drawings

[0015]

Figure 1

Embodiments for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0017] As shown in FIG. 1, the optical laminate 1 of the present embodiment is a polarizing plate in which a transparent protective film layer 3 and an antireflection layer 4 are laminated on a polarizing layer 2. The optical laminate 1 is used by being laminated on a display device, and is arranged in the order of the antireflection layer 4, the transparent protective film layer 3, and the polarizing layer 2 from the viewing side of the display device. Although not shown, a transparent protective film may also be laminated on the surface of the polarizing layer 2 opposite to the viewing side.

[0018] (Polarizing layer) As the material constituting the polarizing layer 2, known materials conventionally used in the production of polarizing plates can be used. For example, polyvinyl alcohol-based resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, etc. can be mentioned. Among them, polyvinyl alcohol-based resins are preferred. Also, it may be a film that has been uniaxially stretched, dyed with iodine or a dichroic dye, and then boric acid-treated. The thickness of the polarizing layer 2 is preferably 5 μm to 20 μm, more preferably 3 μm to 15 μm, and even more preferably 2 μm to 10 μm.

[0019] (Transparent protective film layer) The transparent protective film layer 3 functions as a protective film layer for protecting the polarizing layer 2. Therefore, it is transparent to visible light (for example, the visible light transmittance is 80% or more). As the material constituting the transparent protective film layer 3, a resin is preferably used. Further, as the resin, for example, cellulose-based resins typified by triacetyl cellulose, polyolefin-based resins typified by polypropylene-based resins (in the category of "polyolefin-based resins", there are alicyclic polyolefin-based resins typified by norbornene-based resins, etc.), acrylic-based resins typified by polymethyl methacrylate-based resins, polyester-based resins typified by polyethylene terephthalate-based resins, etc. can be mentioned. Among them, acrylic-based resins or cellulose-based resins are preferred.

[0020] The thickness of the transparent protective film layer 3 may be 5 μm to 30 μm, may be 10 μm to 28 μm, or may be 15 μm to 25 μm. In this embodiment, even for a polarizing plate in which the thickness of the transparent protective film layer 3 is thinned in this way and has an antireflection layer on the surface, the occurrence of optical unevenness can be efficiently prevented. Here, the "thickness of the transparent protective film layer 3" refers to the thickness before performing surface roughening described later.

[0021] The polarizing layer 2 and the transparent protective film layer 3 are directly laminated to each other. Here, "directly laminated" includes a mode of being laminated to the polarizing layer by the self - adhesiveness of the transparent protective film layer 3, and a mode of being laminated via an adhesive or an adhesive agent.

[0022] (Adhesive layer, Adhesive agent layer) Although not shown in FIG. 1, an adhesive layer or an adhesive agent layer may be interposed between the polarizing layer 2 and the transparent protective film layer 3. As the adhesive forming the adhesive layer, various adhesives conventionally used in the production of polarizing plates can be used. For example, acrylic resins such as acrylamide, acrylate, urethane acrylate, epoxy acrylate, and water - based adhesives of polyvinyl alcohol - based can also be used. Further, from the viewpoints of weather resistance, refractive index, cationic polymerizability, etc., an epoxy resin not containing an aromatic ring in the molecule is preferable. Also, it may be cured by irradiation with active energy rays (ultraviolet rays or heat rays). The thickness of the adhesive layer is preferably 0.01 μm to 5 μm.

[0023] Examples of the adhesive forming the adhesive agent layer include acrylic resins, silicone - based resins, polyesters, polyurethanes, polyethers, etc. As a method of laminating the adhesive agent layer on the polarizing layer 2 or the transparent protective film layer 3, for example, a method of applying a solution containing the above - mentioned resin and any additive components to the polarizing layer 2 or the transparent protective film layer 3 may be used, or a method of forming the adhesive agent layer with the solution on a separately prepared separator and then transferring it onto the polarizing layer 2 or the transparent protective film layer 3 may also be used. The thickness of the adhesive agent layer is preferably 2 μm to 500 μm, more preferably 5 μm to 200 μm, and still more preferably 10 μm to 50 μm.

[0024] (Anti - reflection layer) The antireflection layer is a layer for weakening the external light reflection of the optical laminate 1 for a person observing the optical laminate 1, and usually has a reflectance of 1% or less with respect to visible light. Such an antireflection layer typically consists of a high refractive index layer having a high refractive index and a low refractive index layer having a low refractive index. By adjusting these refractive indices and the thicknesses of the respective layers, the reflected light from each layer can be made to weaken each other, and an excellent antireflection function can be achieved.

[0025] The antireflection layer composed of a high refractive index layer and a low refractive index layer is preferably manufactured using a coating-type composition capable of forming each of the high refractive index layer and the low refractive index layer, as will be described in detail later, because the operation is extremely simple. Here, an example of the coating-type composition capable of forming each of the high refractive index layer and the low refractive index layer will be given. Such a coating-type composition is in a liquid state and contains a suitable curable resin and, if necessary, an additive. The coating-type composition (coating liquid for forming a high refractive index layer) capable of forming a high refractive index layer is, for example, a solution obtained by dissolving a curable resin such as urethane acrylate and a photoinitiator (photoinitiator) for photopolymerization such as acetophenone-based, benzophenone-based, benzyldimethylketal-based, α-hydroxyalkylphenone-based, α-aminoalkylphenone-based or thioxanthone-based in a solvent such as methyl ethyl ketone or methyl isobutyl ketone. In order to improve the coatability, a leveling agent, preferably a fluorine-based leveling agent, may be included. Further, as the coating-type composition (coating liquid for forming a low refractive index layer) capable of forming a low refractive index layer, silica particles are dispersed in a solution obtained by dissolving a photoinitiator (photoinitiator) for photopolymerization such as acetophenone-based, benzophenone-based, benzyldimethylketal-based, α-hydroxyalkylphenone-based, α-aminoalkylphenone-based or thioxanthone-based in a solvent such as 1-methoxy-2-propyl acetate or methyl isobutyl in a binder resin such as polyethylene glycol diacrylate or pentaerythritol (tri / tetra) acrylate as a curable resin. In order to improve the coatability, a fluorine-based leveling agent may be included. It should be noted that the coating-type compositions capable of forming the high refractive index layer and the low refractive index layer for forming the antireflection layer are merely examples, and it is preferable to optimize the coating liquid for forming the high refractive index layer and the coating liquid for forming the low refractive index layer according to the characteristics of the antireflection layer to be formed.

[0026] In addition, when the layer that comes to the outermost surface among the high refractive index layer and the low refractive index layer capable of forming the antireflection layer has appropriate surface strength, that layer also functions as a hard coat layer. The coating liquid for forming a high refractive index layer containing a curable resin such as urethane acrylate exemplified above is also useful as a coating-type composition for forming a hard coat layer.

[0027] Regarding the reflectance of the antireflection layer, the reflectance is the so-called visual sensitivity reflectance, and the measuring means is as follows. A black polyethylene terephthalate (PET) film and a transparent film with an antireflection layer are attached using an appropriate adhesive in the order of antireflection layer, transparent film, adhesive, and black PET film. Subsequently, light with an incident angle of 5 degrees is irradiated on the antireflection layer side, which is the object to be measured, and the reflected light in the specular reflection direction reflected by the antireflection layer is received to measure the reflectance in the wavelength range of 380 nm to 780 nm. Finally, the visual sensitivity reflectance can be calculated by multiplying the measured value by the relative visual sensitivity value. As the device for measurement, a commercially available ultraviolet-visible-near-infrared spectrophotometer (for example, "UV-2450" manufactured by Shimadzu Corporation) can be used.

[0028] (Arithmetic mean roughness Ra) The transparent protective film layer 3 of the present embodiment is characterized by the arithmetic mean roughness Ra of the surface 3a on the side that is bonded to the polarizing layer 2. The arithmetic mean roughness Ra before bonding to the polarizing layer 2 may be 0.01 μm to 0.1 μm, or may be 0.02 μm to 0.08 μm. Also, the arithmetic mean roughness Ra of the surface 3a of the transparent protective film layer 3 after peeling the bonded transparent protective film layer 3 and the polarizing layer 2 may be 0.01 μm to 0.1 μm, or may be 0.02 μm to 0.095 μm.

[0029] When measuring the arithmetic mean roughness Ra after peeling, the peeling process method for peeling the transparent protective film layer 3 and the polarizing layer 2 from the optical laminate 1 is as follows. That is, the polarizing layer 2 side is bonded to a glass plate using an adhesive. A cutter blade is inserted between the transparent protective film layer 3 and the polarizing layer 2 to slightly lift the transparent protective film layer 3 from the polarizing layer 2, and the lifted transparent protective film layer 3 is picked up with tweezers and peeled off little by little.

[0030] The device and conditions used for measuring the arithmetic mean roughness Ra are as follows. Measuring device: White interferometer Objective lens: 5 times (magnification) Scan range: -30μm to 10μm Field of view size: 640μm × 480μm Measurement mode: Wave mode Surface correction: Fourth-order processing

[0031] (Method for manufacturing an optical laminate) The manufacturing method of the optical laminate 1 has at least a surface roughening step and a bonding step. In the surface roughening step, a transparent protective film layer 3 made of resin is prepared, and a solvent in which the resin is soluble is brought into contact with one surface of the transparent protective film layer. Examples of the solvent include methyl ethyl ketone, and examples of the contact method include coating with a bar coater. After a predetermined time has elapsed, it is washed with water. It is preferable to perform this surface roughening until the arithmetic mean roughness Ra of the processed surface becomes 0.01μm or more.

[0032] For example, the transparent protective film layer used in the manufacture of an optical film or the like has extremely small surface irregularities. Even if such a transparent protective film layer and a polarizing layer are bonded together and then an antireflection layer is bonded, in the transparent protective film layer of the present embodiment, the specific arithmetic mean roughness Ra of the present embodiment cannot be achieved. By treating the transparent protective film layer by the surface roughening step of the present embodiment and setting the arithmetic mean roughness Ra of the surface 3a of the transparent protective film layer on the side bonded to the polarizing layer within a specific range, prevention of optical unevenness is realized. The manifestation of such an effect cannot be derived even by those skilled in the art from the manufacture of a polarizing plate formed by directly bonding a commercially available transparent protective film layer, and is based on the unique findings of the present inventor.

[0033] In the surface roughening step, it is preferable and operationally simple to bring the solvent into contact with the transparent protective film layer so that the arithmetic surface roughness Ra of the transparent protective film layer falls within the above range. However, if the contact time between the solvent and the transparent protective film becomes too long, the transparency of the processed transparent protective film layer to visible light may be impaired. Therefore, it is preferable to determine the optimum processing time from the resin contained in the transparent protective film layer to be processed and the type of solvent capable of dissolving the resin. Appropriate preliminary experiments can also be conducted to determine the optimum processing time.

[0034] Next, as the laminating step, a polarizing layer 2 is prepared, and the surface 3a of the roughened transparent protective film layer 3 is oriented toward the polarizing layer 2 side, and the transparent protective film layer 3 and the polarizing layer 2 are laminated to each other.

[0035] Finally, an antireflection layer 4 is formed on the other surface of the transparent protective film layer 3 by a curable coating type composition, thereby completing the optical laminate 1. Note that, on the surface of the optical laminate 1 on the polarizing layer 2 side, another transparent protective film or the like may be appropriately provided.

[0036] Here, specific means for forming a high refractive index layer and a low refractive index layer using each of the above-described coating liquids for forming a high refractive index layer and a coating liquid for forming a low refractive index layer will be described. The antireflection layer applied to this embodiment forms a high refractive index layer first on a suitable transparent resin film, and then forms a low refractive index layer on the formed high refractive index layer. Each of the high refractive index layer and the low refractive index layer may be a single layer, and if necessary, a high refractive index layer may be formed and a low refractive index layer may be formed alternately, and an antireflection layer in which a plurality of high refractive index layers and a plurality of low refractive index layers are alternately laminated on a transparent resin film may be formed, and the antireflection layer may be used. The antireflection layer formed on the transparent resin film can be used by peeling off the transparent resin film used as a substrate if necessary, or can be used with the transparent resin film as a substrate attached.

[0037] Regarding the formation of an antireflection layer including the formation of a high refractive index layer from a coating liquid for forming a high refractive index layer containing a curable resin such as the above urethane acrylate and the formation of a low refractive index layer from a coating liquid for forming a low refractive index layer containing a binder resin such as polyethylene glycol diacrylate or pentaerythritol (tri / tetra) acrylate, it is briefly shown as follows.

[0038] A coating liquid for forming a high refractive index layer is applied onto a triacetyl cellulose film which is a transparent resin film, and dried at 70 ° C for 1 minute to volatilize the solvent. Then, ultraviolet rays are irradiated at 100 mJ / cm 2Irradiate under the conditions of 2 to form a high refractive index layer. Subsequently, apply a coating solution for forming a low refractive index layer on the formed high refractive index layer, and then dry it for 1 minute under the condition of 70 °C to volatilize the solvent. Subsequently, irradiate with ultraviolet rays under the condition of 200 mJ / cm

[0039] (Effect) According to the optical laminate 1 of the present embodiment, optical unevenness when observed from the side of the antireflection layer 4 is suppressed. Generally, at the interface between the transparent protective film layer and the polarizing layer, interface reflection occurs due to the difference in refractive index between the two layers. The reflected light due to this interface reflection is observed by the viewer together with the reflected light on the surface of the optical laminate. Since the reflected light due to the interface reflection is originally weak, when the optical laminate does not have an antireflection layer (reflectance of 1% or less), the strong reflected light on the surface of the optical laminate is mainly visually recognized, and the reflected light due to the interface reflection is hardly visually recognized. On the other hand, when the optical laminate has an antireflection layer, the reflected light on the surface of the optical laminate is reduced, so the reflected light due to the interface reflection becomes relatively strong and is easily visually recognized. In any case, the reflected light due to the interface reflection interferes with the reflected light on the surface of the optical laminate and reaches the viewer.

[0040] According to the study by the present inventor, when the optical laminate has an antireflection layer, the reflected light due to the interface reflection is easily visually recognized, and the above-mentioned optical unevenness is caused by the variation in the optical path length of the interface reflection due to the thickness unevenness of the transparent protective film layer, and the difference corresponding to the thickness unevenness occurs in the interference between the reflected light due to the interface reflection and the reflected light on the surface of the optical laminate. This is particularly prominent when the thickness of the transparent protective film layer is thin.

[0041] In the optical laminate 1 of the present embodiment, when the transparent protective film layer 3 and the polarizing layer 2 are peeled off under the above-mentioned predetermined conditions, the arithmetic mean roughness Ra of the peeling surface 3a on the transparent protective film layer 3 side is 0.01 μm or more. This arithmetic mean roughness Ra after peeling reflects the surface roughness of the bonding surface 3a when the transparent protective film layer 3 was in a state of being bonded to the polarizing layer 2. Since the surface 3a of the transparent protective film layer 3 is moderately rough, in the optical laminate 1, the ratio of the light incident from the antireflection layer 4 side and transmitted and scattered by the surface 3a becomes high. Since the interface reflection becomes weaker by the amount of the transmitted and scattered incident light, the resulting optical unevenness is suppressed. Even when the thickness of the transparent protective film layer 3 is thin, for example, 5 μm to 30 μm, according to the optical laminate 1 of the present embodiment, the occurrence of optical unevenness can be suppressed.

[0042] (Experimental Example) Actual measurement examples are shown. First, three types of triacetyl cellulose films with a thickness of 25 μm as the transparent protective film layer were prepared. That is, for the surface to be bonded to the polyvinyl alcohol film, three types were prepared: an untreated one (Experimental Example 1) and those surface-roughened by applying methyl ethyl ketone with a bar coater (Experimental Example 2, Experimental Example 3). The arithmetic mean roughness Ra of the surfaces of these three types was measured.

[0043] For each triacetyl cellulose film, a polyvinyl alcohol film with a thickness of 8 μm as the polarizing layer was bonded, and an optical laminate was manufactured by laminating a high refractive index layer of 5 μm and a low refractive index layer of 0.15 μm as raw materials for the antireflection layer. The reflectance of such an antireflection layer formed by laminating a high refractive index layer of 5 μm and a low refractive index layer of 0.15 μm with respect to visible light is about 1% or less. A water-based adhesive was used for bonding the polyvinyl alcohol film and the triacetyl cellulose film. This water-based adhesive was prepared by adding 3 parts of carboxy group-modified polyvinyl alcohol (Kuraray Poval KL318 manufactured by Kuraray Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (converted from the solid content concentration of 30% of Sumirez Resin 650, a commercially available product (aqueous solution) manufactured by Tago Chemical Industry Co., Ltd. to the above-mentioned number of parts) to 100 parts of water.

[0044] Thereafter, the lit fluorescent lamp was held on the antireflection layer side, and the degree of interference unevenness (optical unevenness) occurring in the image of the fluorescent lamp reflected on the optical laminate was observed with the naked eye. The evaluation index for the interference unevenness is as follows. A… Almost no interference unevenness was recognized. B… Slight interference unevenness was recognized. C… The interference unevenness was prominent.

[0045] Thereafter, the triacetyl cellulose film was peeled off from the polyvinyl alcohol film by the method described above, and the arithmetic mean roughness Ra of the surface of the triacetyl cellulose film was measured. The measurement results are shown in Table 1. From these descriptions, it can be seen that the interference unevenness of the optical laminate can be suppressed by roughening the surface of the transparent protective film.

[0046]

Table 1

Industrial Applicability

[0047] The present invention can be used in the field of polarizing plates.

Explanation of Signs

[0048] 1… Optical laminate, 2… Polarizing layer, 3… Transparent protective film layer, 3a… Surface of the transparent protective film layer, 4… Antireflection layer.

Claims

1. An optical laminate in which an antireflection layer having a reflectance of 1% or less, a transparent protective film layer, and a polarizing layer are laminated in this order as the lamination order from the viewing side when used by being disposed on the viewing side of a display device, wherein the transparent protective film layer and the polarizing layer are directly laminated to each other, the thickness of the polarizing layer is 5 μm to 20 μm, and when the transparent protective film layer and the polarizing layer are peeled from each other by the following peeling process, the arithmetic mean roughness Ra obtained by measuring the arithmetic mean roughness Ra of the peeling surface of the transparent protective film layer is 0.01 μm or more and 0.1 μm or less. Optical laminate. <Peeling process> Bond the polarizing layer side to a glass plate. Insert a cutter blade between the transparent protective film layer and the polarizing layer to slightly lift the transparent protective film layer from the polarizing layer, and pick up the lifted transparent protective film with tweezers and peel it off little by little. <Measurement of arithmetic mean roughness Ra> Measuring device: White interferometer Objective lens: 5 times (magnification) Scan range: -30 μm to 10 μm Field of view size: 640 μm × 480 μm Measurement mode: Wave mode Surface correction: Fourth-order processing

2. The optical laminate according to claim 1, wherein the transparent protective film layer contains an acrylic resin or a cellulose resin.

3. The optical laminate according to claim 1 or 2, wherein the thickness of the transparent protective film layer is 5 μm to 30 μm.

4. A method for manufacturing an optical laminate in which an antireflection layer having a reflectance of 1% or less, a transparent protective film layer, and a polarizing layer are laminated in this order as the lamination order from the viewing side when used by being disposed on the viewing side of a display device, a surface roughening step of roughening the arithmetic mean roughness Ra of one surface of the transparent protective film layer to be 0.01 μm or more and 0.1 μm or less, and a bonding step of bonding the roughened surface of the transparent protective film layer toward the polarizing layer so that the transparent protective film layer and the polarizing layer are laminated to each other. A method for manufacturing an optical laminate, wherein the thickness of the polarizing layer is 5 μm to 20 μm.

5. the transparent protective film layer is made of resin, and in the surface roughening step, the surface of the transparent protective film layer is brought into contact with a solvent in which the resin is soluble. A method for manufacturing an optical laminate according to claim 4. ​

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