Optical film with antifouling layer and method for producing same

Abstract

To provide a manufacturing method of an optical film having an anti-fouling layer, capable of manufacturing an optical film having an anti-fouling layer in a roll-to-roll system while preventing adhesion of an anti-fouling layer material onto a rear face of a transparent base material film.SOLUTION: A manufacturing method of an optical film having an anti-fouling layer includes: an anti-fouling layer formation process of forming an anti-fouling layer on one side in a thickness direction of a transparent base material film while conveying the transparent base material film in a roll-to-roll system; a bonding process of bonding a protective film onto the other side in the thickness direction of the transparent base material film prior to the anti-fouling layer formation process; and a rolling-up process of taking up, with a taking-up roller, an optical film having an anti-fouling layer being the transparent base material film with the anti-fouling layer formed after the anti-fouling layer formation process, into a roll state. In the anti-fouling layer formation process, the anti-fouling layer is composed of a perfluoropolyether group-containing alkoxysilane compound. In the optical film having an anti-fouling layer in the roll state, the other side in the thickness direction of the protective film has contact with the anti-fouling layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical film with an antifouling layer and a method for producing the same. [Background technology]

[0002] For example, an optical film with an antifouling layer is attached to the outer surface of a display, such as a touch panel display, on the image display side, from the viewpoint of antifouling properties. The optical film with an antifouling layer includes a transparent substrate film and an antifouling layer disposed on the outermost surface on one side of the transparent substrate film. The antifouling layer prevents adhesion of contaminants such as hand oils to the outer surface of the display and also makes it easier to remove adhered contaminants. Technology relating to such an optical film with an antifouling layer is described, for example, in Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-227898 Summary of the Invention [Problem to be solved by the invention]

[0004] From the viewpoint of production efficiency, optical films with antifouling layers are manufactured, for example, by a roll-to-roll process. In the antifouling layer formation process using the roll-to-roll process, for example, a long transparent substrate film is run as a work film along a pass line of the process, and an antifouling layer is formed on one surface of the substrate film in the thickness direction at a predetermined location on the pass line. The antifouling layer is formed from a highly water-repellent material, for example, by a wet coating method or a dry coating method. At the end of the pass line, the optical film with an antifouling layer (having an antifouling layer on its surface) is taken up by a take-up roller. In the roll-shaped optical film with an antifouling layer obtained in this manner, the antifouling layer on the outermost surface on one side of the transparent substrate film is in contact with the other surface (back surface) of the film. In addition, a load is applied to the roll-shaped optical film with an antifouling layer in the film thickness direction (roll diameter direction).

[0005] The present inventors have discovered the following about the optical film with an antifouling layer produced as described above. In a roll-shaped optical film with an antifouling layer, the material of the antifouling layer is likely to be transferred from the antifouling layer to the back surface of the transparent substrate film. This problem is particularly likely to occur when the antifouling layer is formed by a dry coating method. Furthermore, the thicker the antifouling layer formed, the more likely this problem is to occur.

[0006] The present invention provides a method for producing an optical film with an antifouling layer, which can produce an optical film with an antifouling layer by a roll-to-roll process while preventing adhesion of an antifouling layer material to the back surface of a transparent substrate film, and an optical film with an antifouling layer. [Means for solving the problem]

[0007] The present invention [1] includes a method for producing an optical film with an antifouling layer, the method including: an antifouling layer forming step of forming an antifouling layer on one surface of a transparent substrate film in a thickness direction while transporting the transparent substrate film by a roll-to-roll method; and a laminating step of laminating a protective film on the other surface of the transparent substrate film in the thickness direction before the antifouling layer forming step or after the antifouling layer forming step and before winding up the transparent substrate film with the antifouling layer.

[0008] The present invention [2] includes a method for producing an optical film with an antifouling layer, which includes an antifouling layer forming step of forming an antifouling layer on the side of the transparent substrate film opposite to the protective film while transporting a composite film comprising a transparent substrate film and a protective film bonded to one side of the transparent substrate film in a roll-to-roll manner.

[0009] The present invention [3] includes the method for producing an optical film with an antifouling layer according to the above [1] or [2], wherein the antifouling layer is formed by a dry coating method in the antifouling layer forming step.

[0010] The present invention [4] includes a method for producing an optical film with an antifouling layer according to any one of the above [1] to [3], wherein the surface free energy of the other surface in the thickness direction of the protective film is 45 mN / m or less.

[0011] The present invention [5] includes the method for producing an optical film with an antifouling layer according to any one of the above [1] to [4], wherein the antifouling layer has a thickness of 6 nm or more.

[0012] The present invention [6] includes an optical film with an antifouling layer, which comprises a transparent substrate film, an antifouling layer disposed on one side of the transparent substrate film in the thickness direction, and a protective film disposed on the other side of the transparent substrate film in the thickness direction.

[0013] The present invention [7] includes the optical film with an antifouling layer according to the above [6], wherein the antifouling layer is a dry coating film.

[0014] The present invention [8] includes the optical film with an antifouling layer according to the above [6] or [7], wherein the antifouling layer has a thickness of 6 nm or more.

[0015] The present invention [9] includes an optical film with an antifouling layer according to any one of the above [6] to [8], wherein the surface free energy of the other surface in the thickness direction of the protective film is 45 mN / m or less. [Effects of the Invention]

[0016] As described above, the method for producing an optical film with an antifouling layer of the present invention includes a laminating step prior to the antifouling layer forming step, or after the antifouling layer forming step and prior to winding up the transparent substrate film with the antifouling layer. In the laminating step, a protective film is laminated to the other surface in the thickness direction of the transparent substrate film. Alternatively, in the method for producing an optical film with an antifouling layer of the present invention, an antifouling layer is formed on the transparent substrate film side of a composite film (a transparent substrate film with a protective film on one side). Therefore, these production methods allow the production of an optical film with an antifouling layer by a roll-to-roll process while preventing adhesion of the antifouling layer material to the back surface of the transparent substrate film by the protective film.

[0017] As described above, the optical film with an antifouling layer of the present invention includes a transparent substrate film, an antifouling layer disposed on one surface of the transparent substrate film in the thickness direction, and a protective film disposed on the other surface of the transparent substrate film in the thickness direction. Such an optical film with an antifouling layer can be produced by a roll-to-roll process while preventing adhesion of the antifouling layer material to the back surface of the transparent substrate film. [Brief explanation of the drawings]

[0018] [Figure 1] 1A shows some steps in one embodiment of a method for producing an optical film with an antifouling layer of the present invention, where Fig. 1A shows a step of preparing a transparent substrate film, Fig. 1B shows a step of forming a hard coat layer, and Fig. 1C shows an example of a lamination step. [Figure 2] 2A shows a step subsequent to the step shown in Fig. 1C. Fig. 2A shows a step of forming an adhesion layer, Fig. 2B shows a step of forming an antireflection layer, and Fig. 2C shows a step of forming an antifouling layer. [Figure 3] 10 shows a modified example of the lamination step. [Figure 4] 1 shows a modified example of an optical film with an antifouling layer of the present invention, in which an antireflection layer is not provided. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 and 2 are process diagrams of one embodiment of the method for producing an optical film with an antifouling layer of the present invention. In this embodiment, the method for producing an optical film with an antifouling layer includes a preparation step (FIG. 1A), a hard coat layer forming step (FIG. 1B), a lamination step (FIG. 1C), an adhesion layer forming step (FIG. 2A), an antireflection layer forming step (FIG. 2B), and an antifouling layer forming step (FIG. 2C). Specifically, the steps are as follows.

[0020] First, in the preparation step, a resin film 11 is prepared as shown in Fig. 1A. In this embodiment, the resin film 11 has a long shape so that the present manufacturing method can be carried out using a roll-to-roll system. The resin film 11 also has a front surface 11a and a back surface 11b opposite to the front surface 11a.

[0021] The resin film 11 is a flexible, transparent resin film. Examples of materials for the resin film 11 include polyester resin, polyolefin resin, polystyrene resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyamide resin, polyimide resin, cellulose resin, norbornene resin, polyarylate resin, and polyvinyl alcohol resin. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of cellulose resins include triacetyl cellulose (TAC). These materials may be used alone or in combination. From the viewpoints of transparency and strength, the resin film 11 is made of a material selected from the group consisting of polyester resin, polyolefin resin, and cellulose resin, and more preferably, a material selected from the group consisting of PET, COP, and TAC.

[0022] The surface 11a of the resin film 11 (the surface on which the hard coat layer 12 described below is laminated) may be subjected to a surface modification treatment, such as a corona treatment, a plasma treatment, an ozone treatment, a primer treatment, a glow treatment, or a coupling agent treatment.

[0023] From the viewpoint of strength, the thickness of the resin film 11 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. From the viewpoint of handleability, the thickness of the resin film 11 is preferably 300 μm or less, and more preferably 200 μm or less.

[0024] The total light transmittance (JIS K 7375-2008) of the resin film 11 is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. Such a configuration is suitable for ensuring the transparency required of an optical film when the optical film is provided on the surface of a display such as a touch panel display. The total light transmittance of the resin film 11 is, for example, 100% or less.

[0025] Next, in the hard coat layer forming step, as shown in FIG. 1B, a hard coat layer 12 is formed on the resin film 11. This results in a transparent substrate film 10 comprising the resin film 11 and the hard coat layer 12. The hard coat layer 12 forms one surface (surface 10a) in the thickness direction D of the transparent substrate film 10. The hard coat layer 12 is a layer that makes it difficult for scratches to form on the exposed surface of the optical film F (the upper surface in the optical film F shown in FIG. 2C). In this embodiment, the hard coat layer forming step is performed by a roll-to-roll method.

[0026] The hard coat layer 12 can be formed, for example, by applying a curable resin composition (varnish) to the surface 11a of the resin film 11 to form a coating film, and then drying and curing the coating film. The curable resin composition contains a curable resin and a solvent. The hard coat layer 12 is a cured product of the curable resin composition (specifically, the curable resin).

[0027] Examples of the curable resin include polyester resin, acrylic resin, urethane resin, acrylic urethane resin, amide resin, silicone resin, epoxy resin, and melamine resin. These curable resins may be used alone or in combination of two or more. From the viewpoint of ensuring high hardness of the hard coat layer 12, an acrylic urethane resin is preferably used as the curable resin.

[0028] Examples of the curable resin include ultraviolet-curable resins and thermosetting resins. When the curable resin composition contains an ultraviolet-curable resin, the coating film is cured by ultraviolet irradiation. When the curable resin composition contains a thermosetting resin, the coating film is cured by heating. UV-curable resins are preferably used as the curable resin because they can be cured without high-temperature heating, which helps improve the production efficiency of the optical film F. The UV-curable resin includes at least one selected from the group consisting of an ultraviolet-curable monomer, an ultraviolet-curable oligomer, and an ultraviolet-curable polymer. A specific example of a composition containing an ultraviolet-curable resin is the hard coat layer-forming composition described in JP 2016-179686 A.

[0029] Examples of solvents contained in the curable resin composition include ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, xylene, methanol, ethanol, isopropanol, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, dichloromethane, and chloroform.

[0030] The curable resin composition may contain fine particles. Adding fine particles to the curable resin composition helps adjust the hardness, surface roughness, refractive index, and antiglare properties of the hard coat layer 12. Examples of fine particles include metal oxide particles, glass particles, and organic particles. Examples of materials for metal oxide particles include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of materials for organic particles include polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate.

[0031] The thickness of the hard coat layer 12 is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, from the viewpoint of ensuring the hardness of the hard coat layer 12 and thereby ensuring the hardness of the surface 23 a of the antifouling layer 23 described below. The thickness of the hard coat layer 12 is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 35 μm or less, and particularly preferably 30 μm or less, from the viewpoint of ensuring the flexibility of the optical film F.

[0032] The surface 12a of the hard coat layer 12, which is one side in the thickness direction D (the surface on which the adhesion layer 21 described below is laminated), is subjected to a surface modification treatment as necessary. Examples of surface modification treatments include plasma treatment, corona treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment. From the viewpoint of ensuring high adhesion between the hard coat layer 12 and the adhesion layer 21, the surface 12a is preferably plasma treated. When the surface 12a is plasma treated, argon gas, for example, is used as an inert gas. The discharge power in the plasma treatment is, for example, 10 W or more and, for example, 10,000 W or less.

[0033] Next, in the laminating step, as shown in FIG. 1C , a protective film 30 is laminated to the other surface (rear surface 10b) in the thickness direction D of the transparent substrate film 10 using a roll-to-roll laminating machine (laminating step). In this embodiment, the protective film 30 includes a substrate film 31 and an adhesive layer 32. In this step, the adhesive layer 32 side of the protective film 30 is laminated to the rear surface 10b of the transparent substrate film 10. Through this step, a long, roll-shaped composite film 100 including the transparent substrate film 10 and the protective film 30 is obtained.

[0034] The base film 31 has a first surface 31a and a second surface 31b opposite the first surface 31a. The base film 31 is, for example, a flexible resin film. Examples of materials for the resin film include polyolefin, polyester, polyvinyl chloride, polyvinylidene chloride, cellulose, polystyrene, and polycarbonate. Examples of polyolefin include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer. Examples of polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. The thickness of the base film 31 is, for example, 12 μm or more, preferably 25 μm or more, and, for example, 200 μm or less, preferably 150 μm or less.

[0035] The pressure-sensitive adhesive layer 32 is formed on the first surface 31a of the base film 31. The pressure-sensitive adhesive layer 32 contains a base polymer that imparts adhesiveness to the pressure-sensitive adhesive layer 32. Examples of the base polymer include acrylic polymers, rubber-based polymers, polyester-based polymers, urethane-based polymers, polyether-based polymers, silicone-based polymers, polyamide-based polymers, and fluorine-based polymers. The thickness of the pressure-sensitive adhesive layer 32 is, for example, 5 μm or more, preferably 10 μm or more, and, for example, 100 μm or less, preferably 75 μm or less.

[0036] The other surface of the protective film 30 in the thickness direction D (the second surface 31b of the base film 31) may be subjected to a transfer suppression treatment. Examples of the transfer suppression treatment include attaching a lubricant to the second surface 31b and forming a resin layer (transfer suppression layer) containing a lubricant.

[0037] Examples of lubricants include wax esters, natural waxes containing the wax esters, silicone-based lubricants, and fluorine-based lubricants. Wax esters are esters of higher fatty acids and higher alcohols. Examples of wax esters include myricyl cerotate, myricyl palmitate, cetyl palmitate, and stearyl stearate. Examples of natural waxes containing wax esters include vegetable waxes and animal waxes. Examples of vegetable waxes include carnauba wax (containing myricyl cerotate as a major component) and palm wax. Examples of animal waxes include beeswax and spermaceti. Examples of silicone-based lubricants include dimethylpolysiloxane and its modified products, carboxyl-modified silicone, α-methylstyrene-modified silicone, α-olefin-modified silicone, polyether-modified silicone, epoxy-modified silicone, amino-modified silicone, amide-modified silicone, and alcohol-modified silicone.

[0038] In the transfer suppression treatment step, it is preferable to form a transfer suppression layer on the second surface 31b of the protective film 30 or the base film 31. The transfer suppression layer constitutes the second surface 31b of the protective film 30. The transfer suppression layer can be formed, for example, by applying a curable resin composition (varnish) to the second surface 31b of the base film 31 to form a coating film, and then drying and curing the coating film. The curable resin composition for forming the transfer suppression layer contains, for example, a curable resin, the above-mentioned lubricant, and a solvent, and may further contain other components such as an antistatic agent as necessary. The transfer suppression layer is a cured product of such a curable resin composition. Examples of the curable resin and solvent include the curable resin and solvent described above for the hard coat layer 12.

[0039] The content of the lubricant in the transfer suppression layer is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of appropriately controlling the surface free energy of the second surface 31b of the protective film 30, for example, within the range described below, and is also preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. Wax esters and natural waxes containing such wax esters are preferred as lubricants in the transfer suppression layer, as they are resistant to whitening even under high-temperature and high-humidity conditions. The resistance of the components in the transfer suppression layer to whitening is important for a film that requires optical transparency.

[0040] The transfer suppression layer preferably contains an antistatic agent. The inclusion of an antistatic agent in the transfer suppression layer is preferable for imparting antistatic properties to the optical film F and suppressing adhesion of foreign matter to the optical film F. Examples of antistatic agents include organic and inorganic antistatic agents. Examples of organic antistatic agents include cationic antistatic agents (having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary amino groups, secondary amino groups, and tertiary amino groups), anionic antistatic agents (having anionic functional groups such as sulfonates, sulfate ester salts, phosphonates, and phosphate ester salts), amphoteric antistatic agents (such as alkylbetaines and their derivatives, imidazolines and their derivatives, alanine and their derivatives), nonionic antistatic agents (such as aminoalcohols and their derivatives, glycerin and its derivatives, polyethylene glycol and its derivatives), and conductive polymers. Examples of conductive polymers include polythiophenes, polyanilines, polypyrroles, polyethyleneimines, and allylamines. Examples of inorganic antistatic agents include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, copper iodide, indium-tin composite oxide (ITO), and antimony-tin composite oxide (ATO).

[0041] In order to ensure good antistatic properties, the content of the antistatic agent in the transfer suppression layer is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, and is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0042] The thickness of the transfer suppression layer is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more, from the viewpoint of appropriately controlling the surface free energy of the second surface 31b of the protective film 30 within the range described below. The thickness of the transfer suppression layer is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 100 nm or less, from the viewpoint of ensuring a good appearance of the optical film F and reducing production costs.

[0043] The surface free energy of the second surface 31b of the protective film 30 is 45 mN / m or less, preferably 43 mN / m or less, and more preferably 40 mN / m or less. The surface free energy is measured by a method described later in the Examples. The lower the surface free energy of the second surface 31b, the lower the affinity between the second surface 31b and antifouling layer materials, such as the organic fluorine compounds having terminal fluoroalkyl groups described below. Furthermore, from the viewpoint of properly transporting the composite film 100 (workpiece film) in a roll-to-roll manufacturing process, the surface free energy of the second surface 31b of the protective film 30 is, for example, 15 mN / m or more, preferably 20 mN / m or more, more preferably 25 mN / m or more, and even more preferably 30 mN / m or more. The lower the surface free energy of the second surface 31b, the more slippery the second surface 31b becomes in a roll-to-roll manufacturing process, making it more difficult to continue transporting the composite film 100 (workpiece film) at a constant speed.

[0044] In this embodiment, the surface free energy γ is γ=γ d +γ p +γ hThe value is expressed by the Kitazaki-Hata theory (Journal of the Japan Adhesion Association, Vol. 8, No. 3, pp. 131-141, 1972). d is the dispersive component of the surface free energy, and γ p is the polar component of the surface free energy, and γ h is the hydrogen bond component of the surface free energy. The method for determining the surface free energy is specifically as described below in the examples.

[0045] Next, in the adhesion layer forming step, as shown in FIG. 2A , an adhesion layer 21 is formed on the surface 12a of the hard coat layer 12. The adhesion layer 21 is a layer for ensuring adhesion of the inorganic oxide layer (the anti-reflection layer 22 described later in this embodiment) to the organic layer (the hard coat layer 12 in this embodiment). Examples of materials for the adhesion layer 21 include metals such as silicon, nickel, chromium, aluminum, tin, gold, silver, platinum, zinc, titanium, tungsten, zirconium, and palladium, alloys of two or more of these metals, and oxides of these metals. From the viewpoint of achieving both adhesion to both the organic layer (the hard coat layer 12 in this embodiment) and the inorganic oxide layer (the anti-reflection layer 22 in this embodiment) and transparency of the adhesion layer 21, indium tin oxide (ITO) or silicon oxide (SiOx) is preferably used as the material for the adhesion layer 21. When silicon oxide is used as the material of the adhesion layer 21, preferably SiOx having a lower oxygen content than the stoichiometric composition is used, and more preferably SiOx having x between 1.2 and 1.9.

[0046] The adhesive layer 21 is formed by depositing a material by, for example, a dry coating method, which includes sputtering, vacuum deposition, and CVD, with sputtering being preferred.

[0047] In sputtering, a gas is introduced into a sputtering chamber under vacuum conditions while a negative voltage is applied to a target placed on a cathode. This generates a glow discharge, ionizing the gas atoms. The gas ions collide with the target surface at high speed, ejecting target material from the target surface and depositing the ejected target material on a predetermined surface. From the viewpoint of film formation speed, reactive sputtering is preferred as a sputtering method. In reactive sputtering, a metal target is used as the target, and a mixed gas of an inert gas such as argon and oxygen (reactive gas) is used as the above-mentioned gas. The proportion of oxygen contained in the inorganic oxide film can be adjusted by adjusting the flow rate ratio (sccm) of the inert gas and oxygen.

[0048] Examples of power sources for carrying out the sputtering method include DC power sources, AC power sources, RF power sources, and MFAC power sources (AC power sources with a frequency band of several kHz to several MHz). The discharge voltage in the sputtering method is, for example, 200 V or more, and, for example, 1000 V or less. The film formation pressure in the sputtering chamber where the sputtering method is carried out is preferably 0.01 Pa or more, more preferably 0.05 Pa or more, and even more preferably 0.1 Pa or more. From the viewpoint of discharge stability, the film formation pressure is, for example, 2 Pa or less.

[0049] The thickness of the adhesive layer 21 is preferably 1 nm or more and 10 nm or less, from the viewpoint of ensuring both the adhesive strength between the hard coat layer 12 and the antireflection layer 22 and the transparency of the adhesive layer 21.

[0050] Next, in the antireflection layer forming step, as shown in Fig. 2B, an antireflection layer 22 is formed on one surface of the adhesive layer 21 in the thickness direction D. The antireflection layer 22 is a layer for suppressing the reflection intensity of external light.

[0051] The antireflection layer 22 has high-refractive-index layers with a relatively high refractive index and low-refractive-index layers with a relatively low refractive index alternately arranged in the thickness direction. In the antireflection layer 22, the net reflected light intensity is attenuated by interference between reflected light at multiple interfaces between multiple thin layers (high-refractive-index layers, low-refractive-index layers) included in the same layer. Furthermore, in the antireflection layer 22, the interference effect that attenuates the reflected light intensity can be exerted by adjusting the optical film thickness (product of refractive index and thickness) of each thin layer. In this embodiment, the antireflection layer 22 specifically has a first high-refractive-index layer 22a, a first low-refractive-index layer 22b, a second high-refractive-index layer 22c, and a second low-refractive-index layer 22d, arranged in this order toward one side in the thickness direction D.

[0052] The first high-refractive index layer 22a, the first low-refractive index layer 22b, the second high-refractive index layer 22c, and the second low-refractive index layer 22d can each be formed by depositing a material using a dry coating method. Dry coating methods include sputtering, vacuum deposition, and CVD, with sputtering being preferred. From the viewpoint of film deposition rate, reactive sputtering is preferred as the sputtering method. The conditions for the sputtering method in this step are the same as those for the adhesion layer formation step described above.

[0053] The first high-refractive-index layer 22a and the second high-refractive-index layer 22c are each made of a high-refractive-index material having a refractive index of preferably 1.9 or more at a wavelength of 550 nm. From the viewpoint of achieving both a high refractive index and low absorption of visible light, examples of the high-refractive-index material include niobium oxide (NbO), titanium oxide, zirconium oxide, indium tin oxide (ITO), and antimony tin oxide (ATO), with niobium oxide being preferred.

[0054] The optical thickness (product of refractive index and thickness) of the first high refractive index layer 22a is, for example, 20 nm or more and, for example, 55 nm or less, and the optical thickness of the second high refractive index layer 22c is, for example, 60 nm or more and, for example, 330 nm or less.

[0055] The first low-refractive-index layer 22b and the second low-refractive-index layer 22d are each made of a low-refractive-index material whose refractive index at a wavelength of 550 nm is preferably 1.6 or less. From the viewpoint of achieving both a low refractive index and low absorption of visible light, examples of the low-refractive-index material include silicon dioxide (SiO2) and magnesium fluoride, with silicon dioxide being preferred.

[0056] The optical thickness of the first low refractive index layer 22b is, for example, 15 nm or more and, for example, 70 nm or less, and the optical thickness of the second low refractive index layer 22d is, for example, 100 nm or more and, for example, 160 nm or less.

[0057] Next, in the antifouling layer forming step, as shown in Fig. 2C , an antifouling layer 23 is formed by a roll-to-roll method on one surface of the antireflection layer 22 in the thickness direction D. The antifouling layer 23 is a layer having an antifouling function. The antifouling function of the antifouling layer 30 includes the function of inhibiting adhesion of contaminants such as hand oils to the exposed surface (upper surface in the figure) of the optical film F, and the function of facilitating removal of adhered contaminants.

[0058] The antifouling layer 23 is formed by depositing an antifouling layer material on the antireflection layer 22 by a dry coating method. That is, the antifouling layer 23 is a film formed by a dry coating method (dry coating film). Examples of dry coating methods include vacuum deposition, sputtering, and CVD. The antifouling layer 23 is preferably a film formed by vacuum deposition (vacuum deposition film). A dry coating film (preferably a vacuum deposition film) for the antifouling layer 23 is suitable for ensuring high adhesion of the antifouling layer 23 to the substrate, and therefore is suitable for ensuring peel resistance of the antifouling layer 23. High peel resistance of the antifouling layer 23 helps maintain the antifouling function of the antifouling layer 23.

[0059] An organic fluorine compound having a terminal fluoroalkyl group is preferably used as the material for the antifouling layer 23. The organic fluorine compound exhibits both high hydrophobicity and high lipophobicity due to the terminal fluoroalkyl group, and is therefore suitable for imparting excellent antifouling properties to the antifouling layer 23. As such an organic fluorine compound, an alkoxysilane compound having a perfluoropolyether group, represented by the following general formula (1), is preferably used.

[0060] R 1 -R 2 -X-(CH2) m -Si(OR 3 )3(1)

[0061] In general formula (1), R 1 represents a linear or branched fluorinated alkyl group (having, for example, 1 to 20 carbon atoms) in which one or more hydrogen atoms in the alkyl group have been substituted with fluorine atoms, and preferably represents a perfluoroalkyl group in which all hydrogen atoms in the alkyl group have been substituted with fluorine atoms.

[0062] R 2 represents a structure containing at least one repeating unit of a perfluoropolyether (PFPE) group, and preferably represents a structure containing two repeating units of a PFPE group. Examples of the repeating unit of a PFPE group include a repeating unit of a linear PFPE group and a repeating unit of a branched PFPE group. Examples of the repeating unit of a linear PFPE group include -(OC n F 2n ) p (n represents an integer of 1 or more and 20 or less, and p represents an integer of 1 or more and 50 or less; the same applies hereinafter). Examples of the repeating structure of the branched PFPE group include a structure represented by -(OC(CF3)2) p - and -(OCF2CF(CF3)CF2) p The repeating structure of the PFPE group is preferably a repeating structure of a linear PFPE group, more preferably -(OCF2) p -and-(OC2F4)p - are some examples.

[0063] R 3 represents an alkyl group having 1 to 4 carbon atoms, and preferably represents a methyl group.

[0064] X represents an ether group, a carbonyl group, an amino group, or an amide group, and preferably represents an ether group.

[0065] m represents an integer of 1 or more, and preferably represents an integer of 20 or less, more preferably 10 or less, and even more preferably 5 or less.

[0066] Of such alkoxysilane compounds having a perfluoropolyether group, the compound represented by the following general formula (2) is preferably used.

[0067] CF3-(OCF2) q -(OC2F4) r -O-(CH2)3-Si(OCH3)3(2)

[0068] In the general formula (2), q represents an integer of 1 or more and 50 or less, and r represents an integer of 1 or more and 50 or less.

[0069] The alkoxysilane compounds having a perfluoropolyether group may be used alone or in combination of two or more kinds.

[0070] In this step, the thickness of the antifouling layer 23 is preferably 6 nm or more, more preferably 7 nm or more, from the viewpoint of ensuring the antifouling properties of the antifouling layer 23. Furthermore, the thickness of the antifouling layer 23 is preferably 25 nm or less, more preferably 20 nm or less, and even more preferably 18 nm or less, from the viewpoint of preventing peeling of the antifouling layer material.

[0071] Preferably, the series of processes from the adhesion layer forming process to the antifouling layer forming process are carried out on a single pass line while the workpiece film is transported by a roll-to-roll method. During the process on a single pass line, the workpiece film is never exposed to the atmosphere. The workpiece film is wound up by a winding roller located at the end of the pass line.

[0072] The lamination step (FIG. 1C) may be performed before the antifouling layer formation step (FIG. 2C), or may be performed after the antifouling layer formation step by the roll-to-roll method and before the transparent substrate film 10 with the antifouling layer 23 is wound up. FIG. 3 schematically shows an example of such a lamination step after the antifouling layer formation step.

[0073] In FIG. 3, a workpiece film W that has undergone a preparation process (FIG. 1A), a hard coat layer forming process (FIG. 1B), an adhesion layer forming process (FIG. 2A), and an anti-reflection layer forming process (FIG. 2B) is transported using a roll-to-roll system. A long, roll-shaped protective film 30 is attached to a payout roller 202, and the protective film 30 is unwound from the protective film roll toward rollers 203, 203 of a roll-to-roll laminating machine. After a film of an antifouling layer material 201 is formed on the workpiece film W using a dry coating method (antifouling layer forming process), the workpiece film W is laminated to the protective film 30 (laminating process) before being taken up by a take-up roller 204. In the laminating process, the rollers 203, 203 laminate the adhesive layer 32 of the protective film 30 to the back surface 10b of the transparent substrate film 10 of the workpiece film W. Then, an optical film F serving as the workpiece film W is taken up by the take-up roller 204.

[0074] In this manner, the optical film F is produced. The optical film F comprises a protective film 30, a transparent substrate film 10, an adhesion layer 21, an antireflection layer 22, and an antifouling layer 23, in this order, toward one side in the thickness direction D. The optical film F has a shape that extends in a direction (plane direction) perpendicular to the thickness direction D. After the protective film 30 is peeled off from the transparent substrate film 10, the optical film F is used by bonding the transparent substrate film 10 side to an adherend, for example, via an adhesive. An example of the adherend is a transparent cover that is placed on the image display side of a display such as a touch panel display.

[0075] As described above, the method for producing an optical film with an antifouling layer includes a laminating step (FIGS. 1C and 3) before the antifouling layer forming step (FIG. 2C) or after the antifouling layer forming step and before the transparent substrate film 10 with the antifouling layer 23 is wound up. In the laminating step, a protective film 30 is laminated to the back surface 10b of the transparent substrate film 10. Therefore, this production method makes it possible to produce an optical film F (optical film with an antifouling layer) by a roll-to-roll method while using the protective film 30 to prevent adhesion of the antifouling layer material to the back surface 10b of the transparent substrate film 10.

[0076] In the method for producing an optical film with an antifouling layer of the present invention, an already produced composite film 100 (transparent substrate film 10 with a protective film 30 on one side) may be separately prepared, and then the above-mentioned film-forming steps (including the antifouling layer forming step shown in FIG. 2C ) may be performed on the transparent substrate film 10 for the composite film 100. Even with this production method, the protective film 30 can prevent adhesion of the antifouling layer material to the back surface 10b of the transparent substrate film 10, and an optical film F (optical film with an antifouling layer) can be produced by a roll-to-roll process.

[0077] Furthermore, the optical film F including the protective film 30 disposed on the back surface 10b of the transparent substrate film 10 can be produced by a roll-to-roll process while preventing adhesion of an antifouling layer material to the back surface 10b. With such an optical film F, when the protective film 30 is peeled off from the transparent substrate film 10 and the transparent substrate film 10 side is attached to an adherend via an adhesive, the adhesive can exert good adhesive strength to the back surface 10b.

[0078] As described above, the surface free energy of the second surface 31b of the protective film 30 is 45 mN / m or less, preferably 43 mN / m or less, and more preferably 40 mN / m or less. The lower the surface free energy of the second surface 31b, the lower the affinity between the antifouling layer material, such as the above-mentioned organic fluorine compound having a fluoroalkyl group at its terminal, and the second surface 31b, and the more the antifouling layer material is prevented from being transferred to the second surface 31b. This prevention of transfer of the antifouling layer material helps to achieve good antifouling properties in the antifouling layer 23.

[0079] The optical film F may not include the antireflection layer 22. To produce such an optical film F, it is preferable to form an inorganic oxide underlayer 24 in place of the antireflection layer 22 in the step shown in Fig. 2B in order to ensure peel resistance of the antifouling layer 23. The optical film F obtained by carrying out the antifouling layer forming step (Fig. 2C) after such a step is shown in Fig. 4.

[0080] The inorganic oxide underlayer 24 is formed by depositing a material using a dry coating method. Dry coating methods include sputtering, vacuum deposition, and CVD, with sputtering being preferred. Materials for the inorganic oxide underlayer 24 include, for example, silicon dioxide (SiO2) and magnesium fluoride, with silicon dioxide being preferred. The thickness of the inorganic oxide underlayer 24 is preferably 50 nm or more, more preferably 65 nm or more, and even more preferably 80 nm or more, from the perspective of ensuring peel resistance of the antifouling layer 23. The thickness of the inorganic oxide underlayer 24 is, for example, 300 nm or less. [Example]

[0081] The present invention will be specifically described below with reference to examples. The present invention is not limited to these examples. The specific numerical values ​​of the blending amounts (contents), physical property values, parameters, etc. described below can be substituted for the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than") of the corresponding blending amounts (contents), physical property values, parameters, etc. described in the above-mentioned "Description of the Invention."

[0082] Example 1 The following steps were carried out in order to produce an optical film with an antifouling layer.

[0083] First, a hard coat layer was formed on one side (front surface) of a long polyethylene terephthalate (PET) film (50 μm thick) serving as a transparent substrate film (hard coat layer formation process). Specifically, 100 parts by weight (solids equivalent) of a butyl acetate solution (trade name "UNIDIC 17-806", solids concentration 80% by weight, manufactured by DIC Corporation) of a mixture of UV-curable monomers and oligomers (mainly containing urethane acrylate) was mixed with 5 parts by weight of a photopolymerization initiator (trade name "IRGACURE 906", manufactured by BASF), and 0.01 parts by weight of a leveling agent (trade name "GRANDIC PC4100", manufactured by DIC Corporation) to obtain a mixed solution. Next, a mixed solvent of cyclopentanone (CPN) and propylene glycol monomethyl ether (PGM) (mass ratio of CPN to PGM: 45:55) was added to adjust the solids concentration of the mixed solution to 36% by weight. This resulted in the preparation of an ultraviolet-curable resin composition (varnish). Next, the resin composition was applied to one side of the PET film to form a coating film. Next, this coating film was dried by heating and then cured by ultraviolet irradiation. The heating temperature was 90°C and the heating time was 60 seconds. For ultraviolet irradiation, a high-pressure mercury lamp was used as the light source, and ultraviolet rays with a wavelength of 365 nm were used, with an integrated irradiation dose of 300 mJ / cm. 2The entire process from forming the coating to curing was carried out using a single pass line in a roll-to-roll system. This resulted in a 5 μm thick hard coat layer (HC) being formed on the PET film, yielding a transparent substrate film (PET film with an HC layer).

[0084] Next, a first protective film was bonded to the other surface (rear surface) of the PET film with the HC layer using a roll-to-roll laminating machine (bonding process). The first protective film comprises a base film (product name "Diafoil T100C38", thickness 38 μm, manufactured by Mitsubishi Chemical Corporation) and an acrylic adhesive layer. The base film has a first surface and a second surface opposite to the first surface. An acrylic adhesive layer (thickness 23 μm) is formed on the first surface of the base film. In this process, the adhesive layer side of the first protective film is bonded to the rear surface of the PET film. This process yielded a long, roll-shaped composite film comprising the PET film with the HC layer and the first protective film on the rear surface of the PET film.

[0085] After this, the following series of processes (from the HC layer pretreatment process described below to the antifouling layer formation process described below) were carried out on one pass line while the work film was transported using the roll-to-roll method. The above roll-shaped composite film was placed as the work film on the pay-off roller located at the start of the pass line, and the work film was paid out from the pay-off roller. During the process, the work film was never exposed to the atmosphere. The work film was taken up by the take-up roller located at the end of the pass line.

[0086] First, in a plasma treatment device, the surface of the HC layer of the PET film with the HC layer was plasma treated in a vacuum atmosphere of 1.0 Pa (HC layer pretreatment step). In this plasma treatment, argon gas was used as the inert gas, and the discharge power was set to 780 W.

[0087] Next, an adhesion layer and an anti-reflection layer were sequentially formed on the HC layer of the PET film with the HC layer after plasma treatment (sputter deposition process). Specifically, a 1.5 nm thick indium tin oxide (ITO) layer as an adhesion layer, a 12 nm thick Nb2O5 layer as a first high refractive index layer, a 28 nm thick SiO2 layer as a first low refractive index layer, a 100 nm thick Nb2O5 layer as a second high refractive index layer, and an 85 nm thick SiO2 layer as a second low refractive index layer were sequentially formed on the HC layer of the PET film with the HC layer using a sputter deposition apparatus. The adhesion layer was formed by MFAC sputtering using an ITO target, argon gas as an inert gas, and oxygen gas as a reactive gas (10 parts by volume per 100 parts by volume of argon gas). The discharge voltage was 400 V, and the pressure in the deposition chamber (deposition pressure) was 0.2 Pa. The first high-refractive index layer was formed by MFAC sputtering using a Nb target, 100 parts by volume of argon gas, and 5 parts by volume of oxygen gas, at a discharge voltage of 415 V and a deposition pressure of 0.42 Pa. The first low-refractive index layer was formed by MFAC sputtering using a Si target, 100 parts by volume of argon gas and 30 parts by volume of oxygen gas, at a discharge voltage of 350 V and a deposition pressure of 0.3 Pa. The second high-refractive index layer was formed by MFAC sputtering using a Nb target, 100 parts by volume of argon gas and 13 parts by volume of oxygen gas, at a discharge voltage of 460 V and a deposition pressure of 0.5 Pa. For the formation of the second low refractive index layer, a Si target was used, and an SiO2 layer was formed by MFAC sputtering using 100 parts by volume of argon gas and 30 parts by volume of oxygen gas, with a discharge voltage of 340 V and a deposition pressure of 0.25 Pa. In this manner, an antireflection layer (first high refractive index layer, first low refractive index layer, second high refractive index layer, second low refractive index layer) was laminated on the HC layer of the PET film with an HC layer, with an adhesive layer interposed therebetween.

[0088] Next, an antifouling layer was formed on the antireflection layer (antifouling layer forming step). Specifically, a 10 nm thick antifouling layer was formed on the antireflection layer by vacuum deposition using a vacuum deposition apparatus. In this vacuum deposition method, a perfluoropolyether group-containing alkoxysilane compound was used as the deposition source. This deposition source was a solid obtained by drying "KY1903-1" (perfluoropolyether group-containing alkoxysilane compound, solid content concentration 20% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. The heating temperature of the deposition source in the vacuum deposition method was 260°C.

[0089] In this manner, an optical film (a long roll-shaped optical film with an antifouling layer) of Example 1 was produced. The optical film of Example 1 included a first protective film, a transparent substrate film (one side of which was provided with a hard coat layer), an adhesion layer, an antireflection layer, and an antifouling layer, in this order.

[0090] Example 2 The optical film of Example 2 was produced in the same manner as the optical film of Example 1, except that a second protective film was used instead of the first protective film in the lamination step. In the lamination step of this example, the second protective film was laminated to the back surface (the exposed surface of the PET film) of a PET film (transparent substrate film) with an HC layer using a roll-to-roll laminator. This resulted in a long, rolled composite film (transparent substrate film with an HC layer / second protective film). The second protective film was the same as the first protective film, except that the second surface of the substrate film was subjected to a transfer-inhibiting treatment.

[0091] The second protective film used in this example was prepared by forming a transfer suppression layer on the second surface (exposed surface of the substrate film) of the first protective film (substrate film / acrylic adhesive layer). To form the transfer suppression layer, a binder aqueous dispersion containing a polyester resin (product name "Binalol MD-1480", an aqueous dispersion of saturated copolymer polyester resin, resin content 25% by mass, manufactured by Toyobo Co., Ltd.), a slip agent aqueous dispersion containing carnauba wax, and a conductive polymer aqueous solution containing 0.5% by mass of poly(3,4-ethylenedioxythiophene) (PEDT) and 0.8% by mass of polystyrene sulfonate (number average molecular weight 150,000) (PSS) (product name "Baytron P", manufactured by H.C. Stark Co., Ltd.) were prepared. Next, 100 parts by solids of the binder aqueous dispersion, 30 parts by solids of the slip agent aqueous dispersion, 50 parts by solids of the conductive polymer aqueous solution, and 20 parts by solids of the melamine-based crosslinking agent were added to a mixed solvent of water and ethanol, and the mixture was stirred for approximately 20 minutes. This resulted in a coating solution with a solids concentration of approximately 0.15% by mass. Next, a corona treatment was applied to the second surface of the substrate film of the first protective film. Next, the coating solution was applied to the second surface (corona-treated surface) using a bar coater to form a coating film, and the coating film was then dried by heating at 130°C for 2 minutes. This resulted in a transfer suppression layer with a thickness of 10 nm being formed on the second surface. In this manner, a long, roll-shaped second protective film (transfer suppression layer / substrate film / acrylic adhesive layer) was obtained.

[0092] The optical film of Example 2 (a long, roll-shaped optical film with an antifouling layer) comprises a second protective film, a transparent substrate film (with a hard coat layer on one side), an adhesion layer, an antireflection layer, and an antifouling layer, in that order.

[0093] Comparative Example 1 Except for not performing the lamination step, the optical film of Comparative Example 1 was produced in the same manner as the optical film of Example 1. The optical film of Comparative Example 1 (a long roll-shaped optical film with an antifouling layer) comprises a transparent substrate film, a hard coat layer, an adhesion layer, an antireflection layer, and an antifouling layer in this order.

[0094] <Thickness of antifouling layer> The thickness of the antifouling layer was measured for each of the optical films of Examples 1 and 2 and Comparative Example 1. A scanning X-ray fluorescence analyzer (trade name "ZSX Primus II", manufactured by Rigaku Corporation) was used for the measurement. The measured thickness T1 (nm) of the antifouling layer is shown in Table 1.

[0095] <Transfer of antifouling layer material> The degree of transfer of the antifouling layer material to the back surface of the transparent substrate film in each of the optical films of Examples 1 and 2 and Comparative Example 1 was investigated. Specifically, the thickness of the antifouling layer material transferred to the back surface of the transparent substrate film was measured. For each of the optical films of Examples 1 and 2, the measurement was performed after peeling off the protective film. A scanning X-ray fluorescence analyzer (trade name "ZSX Primus II", manufactured by Rigaku Corporation) was used for the measurement. The measured thickness T2 (nm) is shown in Table 1.

[0096] <Surface free energy of the back surface> The surface free energy of the surface opposite the antifouling layer of each of the optical films in Examples 1 and 2 and Comparative Example 1 was determined as follows: In Example 1, the surface opposite the antifouling layer was the exposed surface of the substrate film of the first protective film, in Example 2, the exposed surface of the substrate film (release treatment layer surface) of the second protective film, and in Comparative Example 1, the exposed surface of the transparent substrate film.

[0097] First, under conditions of 23°C and 55% relative humidity, the contact angles of droplets (approximately 1 μL) of water (HO), methylene iodide (CHI), and 1-bromonaphthalene in contact with the surface of a film placed horizontally to be characterized for surface free energy were measured using a contact angle meter. A contact angle meter (product name: "CA-X Type Contact Angle Meter," manufactured by Kyowa Interface Science Co., Ltd.) was used for these measurements. Next, using the measured contact angles of water (θw), methylene iodide (θi), and 1-bromonaphthalene (θb), the three simultaneous equations were solved according to the method (Kitazaki-Hata theory) described in the Journal of the Japan Adhesion Association, Vol. 8, No. 3, pp. 131-141 (1972) to obtain the equation γ = γ d +γ p +γ h γ in the formula d ,γ p ,γ h was calculated. d is the dispersive component of the surface free energy, and γ p is the polar component of the surface free energy, and γ h is the hydrogen bonding component of the surface free energy, and γ d ,γ p ,γ h The value (γ) obtained by adding up the above values ​​was determined as the surface free energy of the surface to be identified. The surface free energy (mN / m) is shown in Table 1.

[0098] [Table 1]

[0099] The above-described embodiments are merely examples of the present invention, and the present invention should not be construed as being limited by these embodiments. Modifications of the present invention that are obvious to those skilled in the art are included in the scope of the following claims. [Industrial Applicability]

[0100] The optical film with an antifouling layer of the present invention can be applied to, for example, an antireflection film with an antifouling layer, a transparent conductive film with an antifouling layer, and an electromagnetic wave shielding film with an antifouling layer. [Explanation of symbols]

[0101] F Optical film (optical film with anti-fouling layer) D thickness direction 10 Transparent substrate film 11 Resin film 10a surface 10b back side 12 Hard coat layer 13 Transfer suppression layer 21 Adhesion layer 22 Anti-reflection layer 22a First high refractive index layer 22b First low refractive index layer 22c Second high refractive index layer 22d Second low refractive index layer 23 Antifouling layer 23a surface 30 Protective Film 31 Base film 31a 1st page 31b 2nd side 32 adhesive layer

Claims

1. an antifouling layer forming step of forming an antifouling layer on one surface of a transparent substrate film in a thickness direction while transporting the transparent substrate film by a roll-to-roll method; a lamination step of laminating a protective film to the other surface side in the thickness direction of the transparent substrate film before the antifouling layer forming step; a winding step of winding the antifouling layer-attached optical film, which is the transparent substrate film on which the antifouling layer has been formed, around a winding roller to form a roll after the antifouling layer-forming step, In the antifouling layer forming step, the antifouling layer is formed from a perfluoropolyether group-containing alkoxysilane compound, In the roll-shaped optical film with an antifouling layer, the other surface of the protective film in the thickness direction is in contact with the antifouling layer, A method for producing an optical film with an antifouling layer, wherein the surface free energy of the other surface in the thickness direction of the protective film is 15 mN / m or more and 45 mN / m or less.

2. an antifouling layer forming step of forming an antifouling layer on a side of the transparent substrate film opposite to the protective film while transporting a composite film including a transparent substrate film and a protective film bonded to one side of the transparent substrate film in a roll-to-roll manner; a winding step of winding the antifouling layer-attached optical film, which is the transparent substrate film on which the antifouling layer has been formed, around a winding roller to form a roll after the antifouling layer-forming step, In the antifouling layer forming step, the antifouling layer is formed from a perfluoropolyether group-containing alkoxysilane compound, In the roll-shaped optical film with an antifouling layer, the surface of the protective film opposite to the transparent substrate film is in contact with the antifouling layer, A method for producing an optical film with an antifouling layer, wherein the surface of the protective film opposite to the transparent substrate film has a surface free energy of 15 mN / m or more and 45 mN / m or less.

3. The method for producing an optical film with an antifouling layer according to claim 1 , wherein the antifouling layer is formed by a dry coating method in the antifouling layer forming step.

4. The method for producing an optical film with an antifouling layer according to claim 1 or 2, wherein the antifouling layer has a thickness of 6 nm or more.

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