JP2024070685A - Optical film with antifouling layer, and method for manufacturing the same - Google Patents

Abstract

To provide a method for manufacturing an optical film with an antifouling layer which is suitable for achieving good transparent appearance in an antifouling layer, and an optical film with an antifouling layer.SOLUTION: A method for manufacturing an optical film Z with an antifouling layer includes the steps of: forming an antifouling layer 15 on one surface side of a transparent base material film 11; bonding an adhesive surface 16a of a peeling film 16 to the antifouling layer 15; peeling the peeling film 16 from the antifouling layer 15; and bonding an adhesive surface 17a of a protective film 17 to the antifouling layer 15. Adhesive force of the peeling film 16 to the antifouling layer 15 is 0.008 N/50 mm or more. The optical film Z has the transparent base material film 11, the antifouling layer 15, and the protective film 17 in this order. The protective film 17 is bonded to the antifouling layer 15 on the adhesive surface 17a. A ratio of a thickness of the antifouling layer 15 after removal of the protective film to a thickness of the antifouling layer 15 in a state of having the protective film 17 is 0.9 or more and 1.0 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical film with an antifouling layer and a method for producing the same.

For example, an optical film with an anti-smudge layer is attached to the outer surface of the image display side of a display such as a touch panel display from the viewpoint of anti-smudge properties. The optical film with an anti-smudge layer comprises a transparent substrate film and an anti-smudge layer disposed on the outermost surface on one side of the transparent substrate film. The anti-smudge 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 optical films with an anti-smudge layer is described, for example, in Patent Document 1 below.

JP 2017-227898 A

In the manufacturing process of an optical film with an antifouling layer, the antifouling layer is formed from a highly water-repellent material, for example, by a wet coating method or a dry coating method. However, the present inventors have found that the exposed surface of the antifouling layer may have opaque parts (material unfixed parts) because the highly water-repellent material is not sufficiently fixed to the antifouling layer structure. This defect is particularly likely to occur when the antifouling layer is formed by a dry coating method. On the other hand, the antifouling layer needs to be formed with a sufficient thickness from the viewpoint of film strength and antifouling function. However, the thicker the antifouling layer formed, the thicker the above-mentioned material unfixed parts tend to be formed. The formation of opaqueness on the surface of the antifouling layer is undesirable from the viewpoint of transparent appearance.

The present invention provides a method for producing an optical film with an antifouling layer that is suitable for achieving good transparent appearance in the antifouling layer, and an optical film with an antifouling layer.

The present invention [1] is a method for producing an optical film with an antifouling layer by a roll-to-roll process, and includes an antifouling layer forming step of forming an antifouling layer on one side in the thickness direction of a transparent substrate film, a first lamination step of laminating an adhesive surface of a release film having an adhesive surface to the antifouling layer, a peeling step of peeling the release film from the antifouling layer, and a second lamination step of laminating an adhesive surface of a protective film having an adhesive surface to the antifouling layer, in which the adhesive strength of the release film to the antifouling layer is 0.008 N/50 mm or more.

In the first lamination step of the method for manufacturing an optical film with an antifouling layer of the present invention, the antifouling layer material (unfixed material) that is not sufficiently fixed to the antifouling layer structure adheres to the adhesive surface of the release film. In the subsequent peeling step, a release film having an adhesive strength to the antifouling layer of 0.008 N/50 mm or more is peeled off from the antifouling layer. When the release film is peeled off, at least a part of the unfixed material is removed from the antifouling layer along with the release film. In this way, the first lamination step and peeling step described above are performed after the antifouling layer formation step, which is suitable for removing the unfixed material from the antifouling layer surface. Then, in the second lamination step, the antifouling layer from which the unfixed material has been removed is covered and protected by a protective film. Therefore, this manufacturing method is suitable for suppressing the cloudiness caused by the unfixed material in the antifouling layer and achieving good transparent appearance.

The present invention [2] includes the method for producing an optical film with an antifouling layer described in [1] above, in which the antifouling layer forming step forms the antifouling layer by a dry coating method.

Such a configuration is preferable for ensuring high adhesion of the antifouling layer to the substrate on which it is laminated, and therefore is preferable for ensuring peel resistance of the antifouling layer. High peel resistance of the antifouling layer helps maintain the antifouling function of the antifouling layer. This manufacturing method is suitable for achieving good transparent appearance in the antifouling layer, even when the antifouling layer is formed by a dry coating method.

The present invention [3] includes an optical film with an antifouling layer, which comprises a transparent substrate film, an antifouling layer, and a protective film in this order, the protective film having an adhesive surface on the side of the antifouling layer and attached to the antifouling layer with the adhesive surface, and the ratio of the thickness of the antifouling layer after removing the protective film to the thickness of the antifouling layer with the protective film is 0.9 or more and 1.0 or less.

When unfixed material remains on the surface of the antifouling layer, such an optical film with an antifouling layer is suitable for removing the unfixed material from the surface of the antifouling layer by peeling the protective film from the antifouling layer. Therefore, this optical film with an antifouling layer is suitable for suppressing cloudiness caused by unfixed material in the antifouling layer and achieving good transparent appearance.

The present invention [4] includes the optical film with an antifouling layer described in [3] above, in which the antifouling layer is a dry coating film.

Such a configuration is preferable for ensuring high adhesion of the antifouling layer to the base on which it is laminated, and therefore is preferable for ensuring peel resistance of the antifouling layer. High peel resistance of the antifouling layer helps maintain the antifouling function of the antifouling layer.

The present invention [5] includes an optical film with an antifouling layer according to the above [3] or [4], in which the F intensity ratio of the antifouling layer after removing the protective film is 0.18 or more.

This type of configuration is preferable for ensuring antifouling function and durability in the antifouling layer.

The present invention [6] includes an optical film with an antifouling layer according to any one of [3] to [5] above, in which the F intensity ratio of the antifouling layer after removing the protective film is 0.98 or less.

This type of configuration is preferable from the viewpoint of making the optical film with the antifouling layer thinner.

1A shows some steps in one embodiment of a method for producing an antifouling layer-attached optical film of the present invention, in which Fig. 1A shows a step of preparing a transparent substrate film, Fig. 1B shows a step of forming a hard coat layer, Fig. 1C shows a step of forming an adhesion layer, and Fig. 1D shows a step of forming an antireflection layer. Fig. 2A shows a step following the step shown in Fig. 1D. Fig. 2A shows a step of forming an antifouling layer, Fig. 2B shows a step of laminating a release film to the antifouling layer, and Fig. 2C shows a step of peeling the release film from the antifouling layer. This shows a step following the step shown in FIG. 2C, in which a protective film is attached. 1 shows a modified example of an antifouling layer-attached optical film of the present invention, in which no antireflection layer is provided.

Figures 1A to 3 are process diagrams of one embodiment of the method for producing an optical film with an antifouling layer of the present invention. The method for producing an optical film with an antifouling layer is carried out by a roll-to-roll method, and in this embodiment, includes a preparation step (Figure 1A), a hard coat layer forming step (Figure 1B), an adhesion layer forming step (Figure 1C), an antireflection layer step (Figure 1D), an antifouling layer forming step (Figure 2A), a first lamination step (Figure 2B), a peeling step (Figure 2C), and a second lamination step (Figure 3). In this embodiment, an optical film Z shown in Figure 3 is produced. Specifically, it is as follows.

First, in the preparation step, a transparent substrate film 11 is prepared as shown in FIG. 1A. In this embodiment, the transparent substrate film 11 has a long shape so that the present manufacturing method can be carried out by a roll-to-roll method.

The transparent substrate film 11 is a transparent resin film having flexibility. Examples of the material of the transparent substrate 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 the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resin include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of the cellulose resin include triacetyl cellulose (TAC). These materials may be used alone or in combination of two or more. As the material of the transparent substrate film 11, one selected from the group consisting of polyester resin, polyolefin resin, and cellulose resin is used from the viewpoint of transparency and strength, and more preferably one selected from the group consisting of PET, COP, and TAC is used.

Surface 11a (the surface on which hard coat layer 12 described below is laminated) as one side in the thickness direction D of transparent substrate film 11 may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

From the viewpoint of strength, the thickness of the transparent substrate 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 transparent substrate film 11 is preferably 300 μm or less, and more preferably 200 μm or less.

The total light transmittance (JIS K 7375-2008) of the transparent substrate 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 the optical film Z when the optical film Z is provided on the surface of a display such as a touch panel display. The total light transmittance of the transparent substrate film 11 is, for example, 100% or less.

Next, in the hard coat layer formation process, as shown in FIG. 1B, a hard coat layer 12 is formed on the surface 11a (one surface in the thickness direction D) of the transparent substrate film 11. The hard coat layer 12 is a layer that makes it difficult for scratches to form on the exposed surface (the upper surface in the figure of the optical film Z shown in FIG. 2C) when the optical film Z is used. The hard coat layer formation process is carried out by the roll-to-roll method.

The hard coat layer 12 can be formed, for example, by applying a curable resin composition (varnish) onto the transparent substrate 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).

Examples of the curable resin include polyester resin, acrylic urethane resin, acrylic resin (excluding acrylic urethane resin), urethane resin (excluding 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 kinds. From the viewpoint of ensuring high hardness of the hard coat layer 12, it is preferable to use an acrylic urethane resin as the curable resin.

Examples of the curable resin include ultraviolet-curable resin and thermosetting resin. 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. As the curable resin, an ultraviolet-curable resin is preferably used because it can be cured without high-temperature heating and is useful for improving the production efficiency of the optical film Z. The ultraviolet-curable resin includes at least one type 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 a composition for forming a hard coat layer described in JP-A-2016-179686.

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.

The curable resin composition may contain fine particles. The incorporation of fine particles into the curable resin composition is useful for adjusting the hardness, surface roughness, and refractive index of the hard coat layer 12, and for imparting anti-glare properties. 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.

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 of the antifouling layer 15. 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 Z.

Surface 12a (the surface on which adhesion layer 13 described below is laminated) as one side of hard coat layer 12 in thickness direction D is subjected to surface modification treatment as necessary. Examples of surface modification treatment include plasma treatment, corona treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment. From the viewpoint of ensuring high adhesion between hard coat layer 12 and adhesion layer 13, surface 12a is preferably plasma treated. When 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.

Next, in the adhesion layer forming process, as shown in FIG. 1C, an adhesion layer 13 is formed on the surface 12a (one side in the thickness direction D) of the hard coat layer 12. The adhesion layer 13 is a layer for ensuring the adhesion of the inorganic oxide layer (the anti-reflection layer 14 described later in this embodiment) to the organic layer (the hard coat layer 12 in this embodiment). Examples of materials for such an adhesion layer 13 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 14 in this embodiment) and the transparency of the adhesion layer 13, indium tin oxide (ITO) or silicon oxide (SiOx) is preferably used as the material for the adhesion layer 13. When silicon oxide is used as the material for the adhesion layer 13, it is preferable to use SiOx with a lower oxygen content than the stoichiometric composition, and more preferably, SiOx with x being 1.2 or more and 1.9 or less.

The adhesion layer 13 is formed, for example, by depositing a material using a dry coating method. Dry coating methods include sputtering, vacuum deposition, and CVD, with sputtering being preferred.

In the sputtering method, a negative voltage is applied to a target placed on a cathode while gas is introduced into a sputtering chamber under vacuum conditions. This generates a glow discharge to ionize gas atoms, and 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 formed can be adjusted by adjusting the flow rate ratio (sccm) of the inert gas and oxygen.

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 in which 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.

The thickness of the adhesion layer 13 is preferably 1 nm or more and 10 nm or less from the viewpoint of ensuring both the adhesion between the hard coat layer 12 and the anti-reflection layer 14 and the transparency of the adhesion layer 13.

Next, in the anti-reflection layer formation process, as shown in FIG. 1D, an anti-reflection layer 14 is formed on one surface of the adhesion layer 13 in the thickness direction D. The anti-reflection layer 14 is a layer for suppressing the reflection intensity of external light.

The anti-reflection layer 14 has high-refractive index layers with a relatively large refractive index and low-refractive index layers with a relatively small refractive index alternately in the thickness direction. In the anti-reflection layer 14, the net reflected light intensity is attenuated by the interference between reflected light at multiple interfaces in multiple thin layers (high-refractive index layers, low-refractive index layers) contained in the same layer. In addition, in the anti-reflection layer 14, the interference effect of attenuating the reflected light intensity can be expressed by adjusting the optical film thickness (product of refractive index and thickness) of each thin layer. In this embodiment, specifically, such an anti-reflection layer 14 has a first high-refractive index layer 14a, a first low-refractive index layer 14b, a second high-refractive index layer 14c, and a second low-refractive index layer 14d in this order toward one side of the thickness direction D.

The first high refractive index layer 14a, the first low refractive index layer 14b, the second high refractive index layer 14c, and the second low refractive index layer 14d can each be formed by depositing a material using a dry coating method. Dry coating methods include sputtering, vacuum deposition, and CVD, and sputtering is preferably used. From the viewpoint of deposition speed, reactive sputtering is preferred as the sputtering method. The conditions for the sputtering method in this process are the same as those described above as the conditions for the sputtering method in the adhesion layer formation process.

The first high refractive index layer 14a and the second high refractive index layer 14c 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 ( _Nb2O5 ), _titanium oxide, zirconium oxide, indium tin oxide (ITO), and antimony tin oxide (ATO), and preferably niobium oxide is used.

The optical thickness (product of refractive index and thickness) of the first high refractive index layer 14a is, for example, 20 nm or more and, for example, 55 nm or less. The optical thickness of the second high refractive index layer 14c is, for example, 60 nm or more and, for example, 330 nm or less.

The first low-refractive index layer 14b and the second low-refractive index layer 14d are each made of a low-refractive index material having a refractive index of preferably 1.6 or less at a wavelength of 550 nm. 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 (SiO ₂ ) and magnesium fluoride, and preferably silicon dioxide is used.

The optical thickness of the first low refractive index layer 14b is, for example, 15 nm or more and, for example, 70 nm or less. The optical thickness of the second low refractive index layer 14d is, for example, 100 nm or more and, for example, 160 nm or less.

The exposed surface of the anti-reflection layer 14 is subjected to a surface modification treatment as necessary. When a plasma treatment is used as the surface modification treatment, examples of the treatment gas include oxygen gas and argon gas. The discharge power in the plasma treatment is, for example, 10 W or more, and preferably 50 W or more. The discharge power is, for example, 10,000 W or less, preferably 8,000 W or less, more preferably 5,000 W or less, even more preferably 4,000 W or less, and particularly preferably 3,000 W or less.

Next, in the anti-stain layer forming process, as shown in FIG. 2A, an anti-stain layer 15 is formed on one surface of the anti-reflection layer 14 in the thickness direction D. The anti-stain layer 15 is a layer that has an anti-stain function. The anti-stain function of the anti-stain layer 15 includes a function of suppressing adhesion of contaminants such as hand oils to the exposed surface of the film when the optical film Z is in use, and a function of making it easier to remove the adhered contaminants.

The antifouling layer 15 is formed by depositing an antifouling layer material on the antireflection layer 14 by a dry coating method. That is, the antifouling layer 15 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 15 is preferably a film formed by a vacuum deposition method (vacuum deposition film). The configuration in which the antifouling layer 15 is a dry coating film (preferably a vacuum deposition film) is suitable for ensuring high adhesion of the antifouling layer 15 to the base, and therefore is suitable for ensuring peel resistance of the antifouling layer 15. The high peel resistance of the antifouling layer 15 helps maintain the antifouling function of the antifouling layer 15.

As the material for the antifouling layer 15, an organic fluorine compound having a fluoroalkyl group at the end is preferably used. This organic fluorine compound is suitable for imparting excellent antifouling properties to the antifouling layer 15 due to the combined expression of high hydrophobicity and high oleophobicity resulting from the terminal fluoroalkyl group. As such an organic fluorine compound, an alkoxysilane compound having a perfluoropolyether group, represented by the following general formula (1), is preferably used.

R ¹ -R ² -X-(CH ₂ ) _m -Si(OR ³ ) ₃ (1)

In general formula (1), ^R1 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 are substituted with fluorine atoms, and preferably represents a perfluoroalkyl group in which all of the hydrogen atoms in the alkyl group are substituted with fluorine atoms.

R ² represents a structure containing at least one repeating structure of a perfluoropolyether (PFPE) group, and preferably represents a structure containing two repeating structures of a PFPE group. Examples of the repeating structure of a PFPE group include a repeating structure of a linear PFPE group and a repeating structure of a branched PFPE group. Examples of the repeating structure of a linear PFPE group include a structure represented by -(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 below). Examples of the repeating structure of a branched PFPE group include a structure represented by -(OC(CF ₃ ) ₂ ) _p - and a structure represented by -(OCF ₂ CF(CF ₃ )CF ₂ ) _p -. The repeating structure of the PFPE group preferably includes a repeating structure of a linear PFPE group, more preferably --(OCF ₂ ) _p -- and --(OC ₂ F ₄ ) _p --.

^R3 represents an alkyl group having 1 to 4 carbon atoms, and preferably represents a methyl group.

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

m represents an integer of 1 or more. In addition, m represents an integer of preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less.

Among such alkoxysilane compounds having a perfluoropolyether group, the compound shown in the following general formula (2) is preferably used.

_CF3- ( _OCF2 ) _q- ( _OC2F4 ) _r -O-( _CH2 ) _{3 -} Si( _OCH3 ) ₃ (2)

In 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.

Alkoxysilane compounds having perfluoropolyether groups may be used alone or in combination of two or more types.

In this step, the antifouling layer 15 is formed having a thickness T0 greater than the thickness _T1 (thickness of the antifouling layer 15 after the peeling step) and thickness _T2 (thickness of the antifouling layer ₁₅ after the protective film is removed, final target thickness) of the antifouling layer 15 described below. As long as the thickness _T0 is greater than the thicknesses _T1 and _T2 , it is, for example, 6 nm or more, preferably 8 nm or more, more preferably 10 nm or more, even more preferably 12 nm or more, and particularly preferably 15 nm or more. The difference between the thickness _T1 and the thickness _T0 ( _T0 - _T1 ) is preferably 0.1 nm or more, more preferably 0.2 nm or more, even more preferably 0.3 nm or more, and is preferably 8 nm or less, more preferably 7 nm or less, and even more preferably 6 nm or less. The ratio of thickness _T1 to thickness _T0 ( _T1 / _T0 ) is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.85 or more, and is preferably 0.99 or less, more preferably 0.94 or less, even more preferably 0.90 or less. These configurations for thickness _T0 are preferable for obtaining a significant thickness _T2 in the antifouling layer 15 after the protective film is removed.

When the F intensity ratio is used as an index of the thickness of the antifouling layer 15, the F intensity ratio (F intensity ratio _R0 ) of the antifouling layer 15 formed in this step is, for example, 0.20 or more, preferably 0.26 or more, more preferably 0.33 or more, even more preferably 0.39 or more, and particularly preferably 0.49 or more. The ratio ( _R1 / _R0 ) of the F intensity ratio (F intensity ratio _R1 ) of the antifouling layer 15 after the peeling step described below to the F intensity ratio _R0 is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.85 or more, and preferably 0.99 or less, more preferably 0.94 or less, and even more preferably 0.90 or less (the F intensity ratio ratio ( _R1 / _R0 ) reflects the above-mentioned thickness ratio ( _T1 / _T0 ) of the antifouling layer 15. That is, the F intensity ratio ratio ( _R1 / _R0 ) and the thickness ratio ( _T1 / _T0 ) are the same). These configurations regarding the F intensity ratio R ₀ are preferable for obtaining a significant thickness T ₂ in the antifouling layer 15 after removing the protective film. The F intensity ratio is the ratio of the X-ray intensity (F intensity) of fluorine (F) obtained by fluorescent X-ray analysis under predetermined conditions for the film to be measured to the X-ray intensity of fluorine (F) obtained by fluorescent X-ray analysis under the same conditions for a standard sample glass containing 4.96 mass% fluorine atoms. The glass as the standard sample is "XRF-PF3" manufactured by LGC Standards. The method for measuring the F intensity ratio is specifically as described below in the examples.

In addition, in this process, unfixed areas (not shown) are generated on the surface 15a of the antifouling layer 15, where the antifouling layer material is not sufficiently fixed to the antifouling layer structure. The unfixed areas on the surface 15a are cloudy and cause color unevenness.

Preferably, the series of processes from the adhesion layer forming process to the stain-resistant layer forming process described above is carried out on one continuous line while the work film is running in a roll-to-roll manner. During the process on one continuous line, the work film is never exposed to the atmosphere, and preferably is not wound into a roll.

Next, in the first lamination step, as shown in FIG. 2B, a release film 16 is laminated to the antifouling layer 15. The release film 16 has an adhesive surface 16a on one side of the film. Specifically, in this step, the adhesive surface 16a of the release film 16 is laminated to the surface 15a of the antifouling layer 15 using a roll-to-roll lamination device. In this step, the adhesive surface 16a of the release film 16 is laminated to the surface 15a of the antifouling layer 15, so that the above-mentioned unfixed portion of the antifouling layer 15 (the antifouling layer material) adheres to the adhesive surface 16a.

The release film 16 includes a film substrate and an adhesive layer on the film substrate. The surface of the adhesive layer opposite to the film substrate forms the adhesive surface 16a. Examples of the film substrate include the resin films described above for the transparent substrate film 11. The thickness of the film substrate is preferably 5 μm or more, more preferably 10 μm or more, and preferably 300 μm or less, more preferably 200 μm or less. Examples of materials for the adhesive layer include acrylic adhesives, rubber adhesives, silicone-based adhesives, polyester adhesives, polyurethane adhesives, polyamide adhesives, epoxy adhesives, and vinyl alkyl ether adhesives. The thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, and preferably 50 μm or less, more preferably 30 μm or less.

In the lamination device, the lamination temperature is preferably 10°C or higher, more preferably 20°C or higher, and is preferably 100°C or lower, more preferably 50°C or lower. The lamination pressure in this process is preferably 0.05 MPa or higher, more preferably 0.1 MPa or higher, and is preferably 1 MPa or lower, more preferably 0.8 MPa or lower.

The adhesive strength of the release film 16 attached to the antifouling layer 15 in this step to the antifouling layer 15 is 0.008 N/50 mm or more, preferably 0.015 N/50 mm or more, and more preferably 0.02 N/50 mm or more. This configuration is suitable for ensuring good adhesion of the unfixed portion to the release film 16 to such an extent that the unfixed portion can be attached to the release film 16 and removed from the antifouling layer 15 in the peeling step described below. In addition, from the viewpoint of the releasability of the release film 16, the adhesive strength is preferably 0.1 N/50 mm or less, more preferably 0.09 N/50 mm or less, and even more preferably 0.08 N/50 mm or less. This adhesive strength is measured by the method described later in the Examples.

Next, in the peeling process, as shown in FIG. 2C, the release film 16 is peeled off from the antifouling layer 15. The peeling speed is, for example, 5 to 20 m/min. This process is performed by a roll-to-roll method. In this process, at least a part of the unfixed portion (antifouling layer material) adhering to the adhesive surface 16a of the release film 16 is removed from the antifouling layer 15 together with the release film 16. As a result, at least a part of the unfixed portion is removed from the antifouling layer 15. The above-mentioned first bonding process and peeling process are performed as a functional series of processes. In other words, the first bonding process and peeling process constitute a process (transfer process) of transferring the unfixed portion of the surface 15a of the antifouling layer 15 to the release film 16.

The antifouling layer 15 becomes thinner due to the removal of the unfixed portion (antifouling layer material) in the peeling step. The thickness _T1 of the antifouling layer 15 after this step is preferably 4 nm or more, more preferably 6 nm or more, even more preferably 8 nm or more, and particularly preferably 10 nm or more, from the viewpoint of achieving both the antifouling function and the antifouling durability of the antifouling layer 15. Moreover, from the viewpoint of making the optical film Z thinner, the thickness _T1 is preferably 30 nm or less, more preferably 25 nm or less, and even more preferably 20 nm or less.

When the F intensity ratio is used as an index of the thickness of the antifouling layer 15, the F intensity ratio of the antifouling layer 15 after the peeling step (F intensity ratio R ₁ ) is preferably 0.080 or more, more preferably 0.125 or more, even more preferably 0.170 or more, and still more preferably 0.180 or more, from the viewpoint of achieving both the antifouling function and the antifouling durability of the antifouling layer 15. Moreover, from the viewpoint of reducing the thickness of the optical film Z, the F intensity ratio R ₁ is preferably 1.00 or less, more preferably 0.800 or less, and even more preferably 0.600 or less.

Next, in the second lamination step, as shown in FIG. 3, a protective film 17 is laminated to the antifouling layer 15. The protective film 17 has an adhesive surface 17a on one side of the film. In this step, specifically, the adhesive surface 17a of the protective film 17 is laminated to the surface 15a of the antifouling layer 15 using a roll-to-roll lamination device. If unfixed material remains on the surface of the antifouling layer 15 after the above-mentioned first lamination step and peeling step, in this step, the adhesive surface 17a of the protective film 17 is laminated to the surface 15a of the antifouling layer 15, so that the remaining unfixed portion of the antifouling layer 15 (antifouling layer material) adheres to the adhesive surface 17a.

The protective film 17 includes a film substrate and an adhesive layer on the film substrate. The surface of the adhesive layer opposite to the film substrate forms the adhesive surface 17a. Examples of the film substrate include the resin films described above for the transparent substrate film 11. The thickness of the film substrate is preferably 5 μm or more, more preferably 10 μm or more, and preferably 300 μm or less, more preferably 200 μm or less. Examples of materials for the adhesive layer include acrylic adhesives, rubber adhesives, silicone-based adhesives, polyester adhesives, polyurethane adhesives, polyamide adhesives, epoxy adhesives, and vinyl alkyl ether adhesives. The thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, and preferably 50 μm or less, more preferably 30 μm or less.

In the lamination device, the lamination temperature is preferably 10°C or higher, more preferably 20°C or higher, and is preferably 100°C or lower, more preferably 50°C or lower. The lamination pressure in this process is preferably 0.05 MPa or higher, more preferably 0.1 MPa or higher, and is preferably 1 MPa or lower, more preferably 0.8 MPa or lower.

The adhesive strength of the protective film 17 laminated to the antifouling layer 15 in this step is preferably 0.008 N/50 mm or more, more preferably 0.015 N/50 mm or more, and even more preferably 0.02 N/50 mm or more. This configuration is suitable for ensuring good adhesion of the remaining unfixed portion to the protective film 17 to such an extent that the remaining unfixed portion adheres to the protective film 17 and can be removed from the antifouling layer 15 when the protective film 17 is peeled off. In addition, from the viewpoint of the peelability of the protective film 17, the adhesive strength is preferably 0.1 N/50 mm or less, more preferably 0.09 N/50 mm or less, and even more preferably 0.08 N/50 mm or less. This adhesive strength is measured by the method described later in the Examples.

In this manner, the optical film Z is manufactured. The optical film Z includes the transparent substrate film 11, the hard coat layer 12, the adhesive layer 13, the anti-reflection layer 14, the antifouling layer 15, and the protective film 17, in this order, toward one side of the thickness direction D. The optical film Z has a shape that spreads in a direction (plane direction) perpendicular to the thickness direction D. The optical film Z is used by bonding the transparent substrate film 11 side to an adherend, for example, via an adhesive. The adherend can be, for example, a transparent cover disposed on the image display side of a display such as a touch panel display. In the optical film Z, the antifouling layer 15 can be protected by the protective film 17. Therefore, the optical film Z is suitable for ensuring durability as an optical film with an antifouling layer, such as maintaining the antifouling function of the antifouling layer 15, until the protective film 17 is peeled off and the optical film Z is used as an optical film with an antifouling layer.

In the optical film Z, the ratio (T2 _/ T1) of the thickness _T2 of the antifouling layer 15 after the protective film ₁₇ has been removed (peeled off) to the thickness _T1 of the antifouling layer 15 with the protective film 17 in place is preferably 0.9 or more, more preferably 0.92 or more, and is also preferably 1.0 or less or 0.99 or less. When the F intensity ratio is used as an index of the thickness of the antifouling layer 15, the ratio ( _R2 / _R1 ) of the F intensity ratio (F intensity ratio _R2 ) of the antifouling layer 15 after removing the protective film 17 to the above-mentioned F intensity ratio _R1 after the peeling step is preferably 0.9 or more, more preferably 0.92 or more, and preferably 1.0 or less or 0.99 or less (the F intensity ratio ratio ( _R2 / _R1 ) reflects the thickness ratio ( _T2 / _T1 ) of the antifouling layer 15. That is, the F intensity ratio ratio ( _R2 / _R1 ) and the thickness ratio ( _T2 / _T1 ) are the same). These configurations are suitable for removing unfixed material from the antifouling layer surface 15a by peeling the protective film 17 from the antifouling layer 15 when unfixed material remains on the surface 15a of the antifouling layer 15. Therefore, this configuration is suitable for suppressing cloudiness caused by unfixed material in the stain-resistant layer 15 and realizing good transparent appearance.

The thickness _T2 of the antifouling layer 15 after removing the protective film 17 is preferably 6 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more, from the viewpoint of achieving both the antifouling function and the antifouling durability of the antifouling layer 15. Moreover, from the viewpoint of making the optical film Z thinner, the thickness _T2 is preferably 30 nm or less, more preferably 25 nm or less, even more preferably 20 nm or less, and even more preferably 15 nm or less.

When the F intensity ratio is used as an index of the thickness of the antifouling layer 15, the F intensity ratio _R2 of the antifouling layer 15 after removing the protective film 17 is preferably 0.18 or more, more preferably 0.20 or more, even more preferably 0.30 or more, still more preferably 0.35 or more, still more preferably 0.40 or more, and particularly preferably 0.42 or more, from the viewpoint of achieving both the antifouling function and the antifouling durability of the antifouling layer 15. Moreover, from the viewpoint of reducing the thickness of the optical film Z, the F intensity ratio _R2 is preferably 0.98 or less, more preferably 0.80 or less, still more preferably 0.66 or less, and still more preferably 0.50 or less.

The water contact angle (pure water contact angle) of the surface 15a of the antifouling layer 15 after the protective film 17 is peeled off is preferably 110° or more, more preferably 111° or more, even more preferably 112° or more, even more preferably 113° or more, and particularly preferably 114° or more. A configuration in which the water contact angle on the surface 15a is this high is suitable for realizing high antifouling properties in the antifouling layer 15. The water contact angle is, for example, 130° or less. The water contact angle is determined by forming a water droplet (pure water droplet) with a diameter of 2 mm or less on the surface 15a (exposed surface) of the antifouling layer 15 and measuring the contact angle of the water droplet with respect to the surface 15a. The water contact angle of the surface 15a can be adjusted, for example, by adjusting the composition of the antifouling layer 15, the roughness of the surface 15a, the composition of the hard coat layer 12, and the surface roughness of the hard coat layer 12 on the antifouling layer 15 side.

In the first lamination step (FIG. 2B) of this manufacturing method, as described above, the antifouling layer material (unfixed material) that is not sufficiently fixed to the structure of the antifouling layer 15 adheres to the adhesive surface 16a of the release film 16. In the peeling step (FIG. 2C), the release film 16 having an adhesive strength of 0.008 N/50 mm or more to the antifouling layer 15 is peeled off from the antifouling layer 15. As a result, at least a part of the unfixed portion of the antifouling layer material described above is removed from the antifouling layer 15. That is, the fact that this manufacturing method includes the first lamination step and the peeling step after the antifouling layer formation step (FIG. 2A) is suitable for removing the unfixed material from the antifouling layer 15. Then, in the second lamination step (FIG. 3), the antifouling layer 15 from which the unfixed material has been removed is covered and protected by the protective film 17. Such a manufacturing method is suitable for suppressing the cloudiness caused by the unfixed material in the antifouling layer 15 and realizing a good transparent appearance.

The optical film Z may be an optical film that does not include an anti-reflection layer 14. To manufacture such an optical film Z, it is preferable to form an inorganic oxide underlayer 18 in place of the anti-reflection layer 14 in the process shown in FIG. 1D to ensure the peeling resistance of the anti-smudge layer 15. The optical film Z obtained by carrying out the anti-smudge layer forming process (FIG. 2A), the first lamination process (FIG. 2B), the peeling process (FIG. 2C), and the second lamination process (FIG. 3) after such a process is shown in FIG. 4.

The inorganic oxide underlayer 18 is formed by depositing a material by a dry coating method. Examples of the dry coating method include sputtering, vacuum deposition, and CVD, and preferably, sputtering is used. Examples of the material for the inorganic oxide underlayer 18 include silicon dioxide (SiO ₂ ) and magnesium fluoride, and preferably, silicon dioxide is used. In addition, the thickness of the inorganic oxide underlayer 18 is preferably 50 nm or more, more preferably 65 nm or more, and even more preferably 80 nm or more, from the viewpoint of ensuring the peeling resistance of the antifouling layer 15. The thickness of the inorganic oxide underlayer 18 is, for example, 300 nm or less.

The present invention will be specifically described below with reference to examples. The present invention is not limited to the examples. In addition, the specific numerical values of the compounding amounts (contents), physical property values, parameters, etc. described below can be replaced with 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 compounding amounts (contents), physical property values, parameters, etc. described in the above-mentioned "Form for carrying out the invention".

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

First, a hard coat layer was formed on one side of a polyethylene terephthalate (PET) film (thickness 50 μm) as a transparent substrate film (hard coat layer formation process). Specifically, first, 100 parts by mass (solid content equivalent) of a butyl acetate solution (product name "UNIDIC 17-806", solid content concentration 80 mass%, manufactured by DIC Corporation) of a mixture of ultraviolet curing type monomers and oligomers (containing urethane acrylate as a main component), 5 parts by mass of a photopolymerization initiator (product name "IRGACURE 906", manufactured by BASF Corporation), and 0.01 parts by mass of a leveling agent (product name "GRANDIC PC4100", manufactured by DIC Corporation) were mixed to obtain a mixed solution. Next, the solid content concentration of the mixed solution was adjusted to 36 mass% by adding a mixed solvent of cyclopentanone (CPN) and propylene glycol monomethyl ether (PGM) (mass ratio of CPN to PGM is 45:55). This prepared 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 a light source, ultraviolet rays with a wavelength of 365 nm were used, and the cumulative irradiation amount was 300 mJ/ ^cm2 . This formed a hard coat layer (HC) with a thickness of 5 μm on the PET film.

Next, the HC layer surface of the PET film with the HC layer was plasma-treated in a vacuum atmosphere of 1.0 Pa using a roll-to-roll type plasma treatment device (HC layer pretreatment process). In this plasma treatment, argon gas was used as the inert gas, and the discharge power was 780 W.

Next, an adhesive layer and an anti-reflection layer were formed in sequence on the HC layer of the PET film with the HC layer after the plasma treatment (sputtering film formation process). Specifically, a 1.5 nm thick indium tin oxide (ITO) layer as an adhesive layer, a 12 nm thick Nb ₂ O ₅ layer as a first high refractive index layer, a 28 nm thick SiO ₂ layer as a first low refractive index layer, a 100 nm thick Nb ₂ O ₅ layer as a second high refractive index layer, and a 85 nm thick SiO ₂ layer as a second low refractive index layer were formed in sequence on the HC layer of the PET film with the HC layer by a roll-to-roll sputtering film formation device. In the formation of the adhesion layer, an ITO target was used, argon gas as an inert gas and oxygen gas as a reactive gas of 10 volume parts per 100 volume parts of argon gas were used, the discharge voltage was set to 400 V, the pressure in the film-forming chamber (film-forming pressure) was set to 0.2 Pa, and the ITO layer was formed by MFAC sputtering. In the formation of the first high refractive index layer, an Nb target was used, 100 volume parts of argon gas and 5 volume parts of oxygen gas were used, the discharge voltage was set to 415 V, the film-forming pressure was set to 0.42 Pa, and the Nb ₂ O ₅ layer was formed by MFAC sputtering. In the formation of the first low refractive index layer, an Si target was used, 100 volume parts of argon gas and 30 volume parts of oxygen gas were used, the discharge voltage was set to 350 V, the film-forming pressure was set to 0.3 Pa, and the SiO ₂ layer was formed by MFAC sputtering. In the formation of the second high refractive index layer, a Nb 2 O 5 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, a discharge voltage of 460 V, and a deposition pressure of _0.5 Pa. In the formation of the second low refractive index layer, a Si target was used, 100 parts by volume of argon gas and 30 parts by volume of oxygen gas, a discharge voltage of 340 V, and a deposition pressure of 0.25 Pa, and a SiO ₂ layer was formed by MFAC sputtering. In this manner, the anti-reflection layers (first high refractive index layer, first low refractive index layer, second high refractive index layer, and second low refractive index layer) were laminated on the HC layer of the PET film with the HC layer via the adhesive layer.

Next, an anti-smudge layer was formed on the anti-reflection layer (anti-smudge layer formation process). Specifically, an anti-smudge layer with a thickness of 10 nm was formed on the anti-reflection layer by a vacuum deposition method using an alkoxysilane compound containing a perfluoropolyether group as a deposition source. The deposition source was a solid obtained by drying "KY1903-1" (alkoxysilane compound containing a perfluoropolyether group, 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.

The entire process from the HC layer pretreatment process to the anti-fouling layer formation process was carried out on a single continuous line with the work film running using the roll-to-roll method. During this process, the work film was never exposed to the atmosphere.

Next, a release film was attached to the exposed surface of the antifouling layer (first lamination process). Specifically, a roll-to-roll lamination device was used to attach the adhesive surface of a first release film having an adhesive surface on one side to the surface of the antifouling layer. The lamination pressure in the device used was 0.2 MPa. The first release film was prepared as follows.

First, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, a mixture containing 90 parts by mass of butyl acrylate (BA), 10 parts by mass of acrylic acid (AA), 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and 234 parts by mass of ethyl acetate was stirred and reacted under a nitrogen atmosphere at 63°C for about 7 hours (polymerization reaction). As a result, a first polymer solution (solid concentration 30% by mass) containing a first acrylic polymer was obtained. Next, this polymer solution was diluted to 20% by mass with ethyl acetate. Next, 11 parts by mass of an epoxy crosslinking agent (product name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added to the polymer solution per 100 parts by mass of the first acrylic polymer, and the solution was stirred at about 25°C for about 1 minute. As a result, a pressure-sensitive adhesive composition C1 was obtained. Next, the pressure-sensitive adhesive composition C1 was applied to one side of a polyethylene terephthalate (PET) substrate to form a coating film. Next, the coating film on the PET substrate was heated at 150°C for 60 seconds to form a 20 μm thick adhesive layer. Next, the silicone-treated surface of a PET release liner (25 μm thick) with one side silicone-treated was attached to the exposed surface of the adhesive layer. In this way, a first release film was produced. When using the first release film, the PET release liner was removed from the adhesive layer.

Next, the release film was peeled off from the antifouling layer using a roll-to-roll method (peeling process). The peeling speed in this process was 10 m/min.

Next, a protective film was attached to the exposed surface of the antifouling layer (second attachment process). Specifically, a roll-to-roll attachment device was used to attach the adhesive surface of a first protective film having an adhesive surface on one side to the surface of the antifouling layer. The attachment pressure in the device used was 0.2 MPa. The first protective film was the same as the first release film.

In this manner, the optical film of Example 1 (optical film with an antifouling layer) was produced. The optical film of Example 1 comprises a transparent substrate film, a hard coat layer, an adhesion layer, an antireflection layer, an antifouling layer, and a protective film in this order.

Example 2
The optical film of Example 2 was produced in the same manner as the optical film of Example 1, except for the following: In the first lamination step, a second release film was used instead of the first release film, and in the second lamination step, a second protective film was used instead of the first protective film. The second release film was produced as follows (the second protective film used was produced in the same manner as the second release film).

First, a binder dispersion, a slip agent dispersion, and a conductive polymer aqueous solution were prepared. The binder dispersion was "Binalol MD-1480" manufactured by Toyobo Co., Ltd., and was an aqueous dispersion of saturated copolymerized polyester resin as a binder, with a polyester resin concentration of 25% by mass. The slip agent dispersion was an aqueous dispersion of carnauba wax as a slip agent. The conductive polymer aqueous solution was "Baytron P" manufactured by H.C. Stark Co., Ltd., and contained 0.5% by mass of poly(3,4-ethylenedioxythiophene) (PEDT) as a first conductive polymer and 0.8% by mass of polystyrene sulfonate (number average molecular weight 150,000) (PSS) as a second conductive polymer. Next, 100 parts by mass of the binder dispersion in terms of solid content, 30 parts by mass of the slip agent dispersion in terms of solid content, 50 parts by mass of the conductive polymer aqueous solution in terms of solid content, and a melamine-based crosslinking agent were added to a mixed solvent of water and ethanol, and the mixture was stirred for about 20 minutes. This resulted in a coating material with a solids concentration of approximately 0.15%. A transparent polyethylene terephthalate (PET) film (thickness 38 μm, width 30 cm, length 40 cm) with one side subjected to corona treatment was also prepared. The above-mentioned coating material was then applied to the corona-treated surface of this PET film with a bar coater to form a coating film. The coating film on the PET film was then heated at 130°C for 2 minutes and dried. In this way, a substrate (substrate with topcoat) was produced that had a transparent topcoat layer with a thickness of 10 nm on one side of the PET film.

Meanwhile, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, a mixture containing 100 parts by mass of 2-ethylhexyl acrylate, 4 parts by mass of 2-hydroxyethyl acrylate, 0.15 parts by mass of 2,2'-azobisisobutyronitrile (AIBN), and 200 parts by mass of toluene as a polymerization solvent was stirred and reacted under a nitrogen atmosphere at 70°C for 6 hours (polymerization reaction). This resulted in a second polymer solution containing a second acrylic polymer. Next, 4 parts by mass of an isocyanate crosslinking agent (product name: "Coronate L", manufactured by Tosoh Corporation), 0.2 parts by mass of dibutyltin dilaurate (1% ethyl acetate solution) as a crosslinking catalyst, and toluene were added to this second polymer solution per 100 parts by mass of the second acrylic polymer, and the solution was stirred at around 25°C for about 1 minute. This resulted in a pressure-sensitive adhesive composition C2 (solid content concentration 20% by mass). Next, the adhesive composition C2 was applied to the silicone-treated surface of a PET release liner (thickness 25 μm) that had been silicone-treated on one side to form a coating film. The coating film on the PET release liner was then heated at 150° C. for 60 seconds to form an adhesive layer with a thickness of 15 μm. Next, the exposed surface of the adhesive layer was bonded to the surface of the above-mentioned topcoat-coated substrate that did not have a topcoat layer, and then aged (aged) for 3 days in an environment of 50° C. and relative humidity 15%. In this way, a second release film (second protective film) was produced. When using this film, the PET release liner was removed from the adhesive layer.

Example 3
The optical film of Example 3 was produced in the same manner as the optical film of Example 1, except for the following. In the first lamination step, the third release film was used instead of the first release film, and in the second lamination step, the third protective film was used instead of the first protective film. The third release film was produced in the same manner as the above-mentioned second release film, except that the adhesive composition C3 was used instead of the adhesive composition C2. The adhesive composition C3 was prepared in the same manner as the adhesive composition C2, except that the solid content concentration was changed from 20% by mass to 25% by mass. As the third protective film, one produced in the same manner as the third release film was used.

Example 4
The optical film of Example 4 was produced in the same manner as the optical film of Example 1, except for the following: In the first lamination step, a fourth release film was used instead of the first release film, and in the second lamination step, a fourth protective film was used instead of the first protective film. The fourth release film was produced as follows (the fourth protective film used was produced in the same manner as the fourth release film).

First, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, a mixture containing 90 parts by mass of butyl acrylate (BA), 10 parts by mass of acrylic acid (AA), 0.1 parts by mass of 2-hydroxyethyl acrylate (2HEA), 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and a predetermined amount of ethyl acetate was stirred and reacted in a nitrogen atmosphere at 55°C for about 8 hours (polymerization reaction). This resulted in a third polymer solution containing a third acrylic polymer (weight average molecular weight 2.2 million). Next, 0.8 parts by mass of an isocyanate crosslinking agent (product name "Coronate L", manufactured by Tosoh Corporation) and 0.2 parts by mass of a silane coupling agent (product name "KBM403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed per 100 parts by mass of the third acrylic polymer to this polymer solution. This resulted in the production of a pressure-sensitive adhesive composition C4. Next, the adhesive composition C4 was applied to the silicone-treated surface of a first PET film (product name "MRF38", thickness 38 μm, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) serving as a release liner with one side silicone-treated to form a coating film. Next, the coating film on the first PET film was heated at 155°C for 60 seconds to form an adhesive layer with a thickness of 23 μm. Next, a second PET film (thickness 38 μm) that was not silicone-treated was attached as a substrate to the exposed surface of the adhesive layer. In this manner, a fourth release film was produced. When using the fourth release film, the first PET film serving as a release liner was removed from the adhesive layer.

Example 5
The optical film of Example 5 was produced in the same manner as the optical film of Example 1, except for the following: In the first lamination step, a fifth release film was used instead of the first release film, and in the second lamination step, a fifth protective film was used instead of the first protective film. As the fifth release film, "TORAYFAN BS MS06" (a resin film with an adhesive layer) manufactured by Toray Advanced Film Co., Ltd. was used. As the fifth protective film, the same film as the fifth release film was used.

Example 6
An optical film of Example 6 was produced in the same manner as the optical film of Example 1, except that the thickness of the antifouling layer formed in the antifouling layer-forming step was 5.7 nm instead of 10 nm.

Example 7
The optical film of Example 7 was produced in the same manner as the optical film of Example 1, except for the following: In the formation of the second low refractive index layer during the sputtering film formation process, the film formation pressure was 0.5 Pa instead of 0.25 Pa. In the anti-stain layer formation process (vacuum deposition method), the heating temperature of the deposition source was 270° C. instead of 260° C., and the thickness of the anti-stain layer formed was 16.1 nm instead of 10 nm. In the first lamination process, a second release film was used instead of the first release film. In the second lamination process, a second protective film was used instead of the first protective film.

Example 8
The optical film of Example 8 was produced in the same manner as the optical film of Example 1, except for the following: In the formation of the second low refractive index layer during the sputtering film formation process, the film formation pressure was 0.5 Pa instead of 0.25 Pa. In the anti-stain layer formation process (vacuum deposition method), the heating temperature of the deposition source was 245° C. instead of 260° C., and the thickness of the anti-stain layer formed was 16.8 nm instead of 10 nm. In the first lamination process, a second release film was used instead of the first release film. In the second lamination process, a second protective film was used instead of the first protective film.

Example 9
The optical film of Example 9 was manufactured in the same manner as the optical film of Example 1, except for the following: In the formation of the second low refractive index layer during the sputtering film formation process, the film formation pressure was changed from 0.25 Pa to 0.5 Pa. Between the sputtering film formation process and the antifouling layer formation process, a base layer pretreatment process was carried out. Specifically, the surface of the formed antireflection layer was plasma-treated (treatment gas: oxygen gas, discharge power: 50 W) in a vacuum atmosphere by a roll-to-roll type plasma treatment device. In the antifouling layer formation process (vacuum deposition method), the heating temperature of the deposition source was changed from 260° C. to 270° C., and the thickness of the formed antifouling layer was changed from 10 nm to 16.3 nm. In the first lamination process, a second release film was used instead of the first release film. In the second lamination process, a second protective film was used instead of the first protective film.

Example 10
The optical film of Example 10 was produced in the same manner as the optical film of Example 1, except for the following: In the formation of the second low refractive index layer during the sputtering film formation process, the film formation pressure was changed from 0.25 Pa to 0.5 Pa. In the antifouling layer formation process (vacuum deposition method), the heating temperature of the deposition source was changed from 260° C. to 270° C., and the thickness of the antifouling layer formed was changed from 10 nm to 17.0 nm. In the first lamination process, a third release film was used instead of the first release film. In the second lamination process, a third protective film was used instead of the first protective film.

Comparative Example 1
The optical film of Comparative Example 1 was produced in the same manner as the optical film of Example 1, except for the following. In the first lamination step, a sixth release film was used instead of the first release film, and in the second lamination step, a sixth protective film was used instead of the first protective film. As the sixth release film, "FSA020" (a resin film with an adhesive layer) manufactured by Futamura Chemical Co., Ltd. was used. As the sixth protective film, the same film as the sixth release film was used.

<Evaluation of Adhesive Strength>
The adhesive strength of the release film laminated to the antifouling layer in each of the manufacturing methods of Examples 1 to 10 and Comparative Example 1 was examined. Specifically, first, in the optical film manufacturing process, a film piece (50 mm x 100 mm) was cut out from the work film (optical film with release film) after the first lamination step. Next, the surface of the film piece facing the transparent substrate film was attached to a glass plate via a predetermined adhesive layer (this adhesive layer is an adhesive layer formed from the above-mentioned adhesive composition C4). This resulted in a measurement sample. Next, a peel test was performed to peel the release film from the measurement sample, and the peel strength was measured as adhesive strength (N/50 mm). For this measurement, a tensile tester (product name "Autograph AG-X plus", manufactured by Shimadzu Corporation) was used. In this measurement, the measurement temperature was 25°C, the peel angle of the release film to the antifouling layer surface was 180°, the pulling speed of the release film was 30 cm/min, and the peel length was 50 mm. The results are shown in Table 1. For each optical film, the adhesion of the protective film to the antifouling layer is expected to be similar to the measured adhesion of the release film to the antifouling layer.

<F intensity ratio of antifouling layer>
In each of the manufacturing methods of Examples 1 to 10 and Comparative Example 1, the F intensity ratio R ₀ of the antifouling layer before the first lamination step and the F intensity ratio R ₁ of the antifouling layer after the peeling step were measured. In addition, the F intensity ratio R ₂ of the antifouling layer after removing the protective film from the manufactured optical film was also measured. The F intensity ratio is the ratio of the X-ray intensity (F intensity) of fluorine (F) obtained by X-ray fluorescence analysis under specified conditions for the measurement target film to the X-ray intensity of fluorine (F) obtained by X-ray fluorescence analysis under the same conditions for glass as a standard sample containing 4.96 mass% fluorine atoms. For this measurement, a scanning X-ray fluorescence analyzer (product name "ZSX Primus II", manufactured by Rigaku Corporation) was used. In this measurement, the "XRF-PF3" manufactured by LGC Standards was used as the standard sample, and the fluorine atom intensity in the surface layer and the fluorine atom intensity in the standard sample were measured under the following conditions: measurement diameter: 30 mm, measurement line: F-Kα, filter: OUT, slit: standard, analyzing crystal: RX35 (manufactured by Rigaku Corporation), detector: PC, PHA: 100-300, peak angle: 38.794 deg. (20 sec), B.G. angle: 43.000 deg. (10 sec). Table 1 shows the F intensity ratios R ₀ , R ₁ , and R ₂ , the ratio of the F intensity ratio R ₁ to the F intensity ratio R ₀ (R ₁ /R ₀ ), and the ratio of the F intensity ratio R ₂ to the F intensity ratio R ₁ (R ₂ /R ₁ ). The F intensity ratio ratio ( _R1 /R0) reflects the ratio (T1/ _T0 ) of the thickness _T1 of the antifouling layer after the peeling step to the thickness _T0 of the antifouling layer before the first bonding step _. That is, the F intensity ratio ratio ( _R1 / _R0 ) and the thickness ratio ( _T1 / _T0 ) are the same. In addition, the F intensity ratio ratio ( _R2 / _R1 ) reflects the ratio ( _T2 / _T1 ) of the thickness _T2 of the antifouling layer after the protective film is removed to the thickness _T1 of the antifouling layer before the peeling step _. That is, the F intensity ratio ratio ( _R2 / _R1 ) and the thickness ratio ( _T2 / _T1 ) are the same.

<Transparent appearance>
After the second lamination step in each of the manufacturing methods of Examples 1 to 10 and Comparative Example 1, the transparent appearance of the antifouling layer was evaluated. Specifically, first, whether or not a cloudy part was formed on the surface of the antifouling layer and color unevenness occurred was confirmed by visual observation through the protective film. In the visual observation, observation was performed from a direction at an elevation angle of about 20° to the surface of the antifouling layer. Then, the transparent appearance of the antifouling layer was evaluated as "good" when no color unevenness occurred, and as "poor" when color unevenness occurred. The results are shown in Table 1.

<Anti-stain durability>
The durability of the antifouling layer of each optical film in Examples 1 to 10 and Comparative Example 1 was examined as follows. First, the protective film was removed from the optical film, and then the water contact angle of the antifouling layer surface was measured. Next, an eraser sliding test was performed on the antifouling layer surface, and then the water contact angle of the antifouling layer surface was measured again. In measuring each water contact angle before and after the eraser sliding test, first, a water droplet was formed on the antifouling layer surface of the optical film by dropping about 1 μL of pure water. Next, the angle formed between the surface of the water droplet on the antifouling layer surface and the antifouling layer surface was measured. For the measurement, a contact angle meter (trade name "DMo-501", manufactured by Kyowa Interface Science Co., Ltd.) was used. In the eraser sliding test, an eraser (Φ6 mm) manufactured by Minoan was used, the load of the eraser on the antifouling layer surface was 1 kg/6 mmΦ, the sliding distance of the eraser on the antifouling layer surface (one way in reciprocating motion) was 20 mm, the sliding speed of the eraser was 40 reciprocations/min, and the eraser was reciprocated 3,000 times against the antifouling layer surface.

On the surface of the antifouling layer, the degree of decrease in water contact angle due to the eraser sliding test indicates the degree of decrease in antifouling properties. Regarding the antifouling durability of the antifouling layer, a decrease in water contact angle due to the eraser sliding test of less than 15° was evaluated as "excellent", a decrease of 15° or more but less than 20° was evaluated as "good", and a decrease of 20° or more was evaluated as "poor". The results are shown in Table 1.

F Optical film (optical film with antifouling layer)
D Thickness direction 11 Transparent substrate film 12 Hard coat layer 13 Adhesive layer 14 Antireflection layer 14a First high refractive index layer 14b First low refractive index layer 14c Second high refractive index layer 14d Second low refractive index layer 15 Antifouling layer 15a Surface 16 Release film 16a Adhesive surface 17 Protective film 17a Adhesive surface 18 Inorganic oxide underlayer

Claims (6)

A method for producing an optical film with an antifouling layer by a roll-to-roll process, comprising the steps of:
an antifouling layer forming step of forming an antifouling layer on one surface of a transparent substrate film in a thickness direction;
a first bonding step of bonding an adhesive surface of a release film having an adhesive surface to the antifouling layer;
a peeling step of peeling the release film from the antifouling layer;
a second bonding step of bonding an adhesive surface of a protective film having an adhesive surface to the antifouling layer,
A method for producing an optical film with an antifouling layer, wherein the adhesive strength of the release film to the antifouling layer is 0.008 N/50 mm or more. 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. A transparent substrate film, an antifouling layer, and a protective film are provided in this order,
the protective film has an adhesive surface on the antifouling layer side and is attached to the antifouling layer by the adhesive surface,
An optical film with an antifouling layer, wherein a ratio of a thickness of the antifouling layer after removing the protective film to a thickness of the antifouling layer with the protective film is 0.9 or more and 1.0 or less. The optical film with an antifouling layer according to claim 3, wherein the antifouling layer is a dry coating film. The optical film with an antifouling layer according to claim 3, wherein the F intensity ratio of the antifouling layer after removing the protective film is 0.18 or more. An optical film with an antifouling layer according to any one of claims 3 to 5, wherein the F intensity ratio of the antifouling layer after removing the protective film is 0.98 or less.

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