JP7730864B2 - Laminated Film - Google Patents

Description

The present invention relates to a laminated film.

With the aim of reducing the weight and improving the functionality of electronic products, various composite materials that combine organic and inorganic materials have been developed. One known example of a composite material is a laminate film that comprises a substrate film made of an organic material and an inorganic layer on the substrate film. During the manufacturing process of such a laminate film, for example, before the inorganic layer is formed on the substrate film, the surface of the substrate film is plasma treated to remove dirt and moisture from the surface. Removing dirt and moisture from the surface of the substrate film helps to improve the adhesion of the inorganic layer formed on the surface to the substrate film. Technology related to such laminate films is described, for example, in Patent Document 1 below.

Japanese Patent Application Laid-Open No. 2022-65437

Patent Document 1 describes a laminated film used as an anti-reflection film. This laminated film comprises a substrate film, an adhesive layer, and an inorganic layer serving as an anti-reflection layer, in that order in the thickness direction. The substrate film has a hard coat (HC) layer on the adhesive layer side. This HC layer contains nanosilica particles. As a result, the HC layer has surface irregularities on the adhesive layer side. The anchor effect of the surface irregularities of the HC layer and the physicochemical action of the adhesive layer enhance the adhesion of the inorganic layer to the substrate film. If the adhesion of the inorganic layer to the substrate film is insufficient, the inorganic layer will peel off from the substrate film.

However, nanosilica particles are relatively expensive and increase the manufacturing costs of laminated films.

The present invention provides a laminated film that can ensure adhesion of the inorganic layer to the base film while reducing manufacturing costs.

The present invention [1] relates to a laminate film comprising a base film, an adhesive layer on the base film, and an inorganic layer on the adhesive layer, wherein, in a cross-sectional view in the thickness direction of the laminate film, the ratio of a second interface length at the interface between the adhesive layer and the inorganic layer to a first interface length at the interface between the base film and the adhesive layer is 1.10 or greater.

The present invention [2] includes the laminate film described in [1] above, in which the ratio is 2.0 or less.

The present invention [3] includes the laminate film described in [1] or [2] above, in which the adhesive layer has a thickness of 1 nm or more and 50 nm or less.

The present invention [4] includes the laminate film described in any one of [1] to [3] above, in which the adhesion layer is an inorganic oxide film containing at least one element selected from the group consisting of Si, In, Al, Sn, Ti, Zr, and Nb.

The present invention [5] includes the laminate film described in any one of [1] to [4] above, in which the inorganic layer includes a conductive layer.

The present invention [6] includes the laminate film described in any one of [1] to [5] above, in which the inorganic layer includes an anti-reflection layer, and the anti-reflection layer includes multiple transparent inorganic oxide films stacked in the thickness direction.

As described above, in the laminate film of the present invention, in a cross-sectional view of the laminate film in the thickness direction, the ratio of the second interface length at the interface between the adhesive layer and the inorganic layer to the first interface length at the interface between the substrate film and the adhesive layer is 1.10 or greater. In such a laminate film, the ratio of the first and second interface lengths being 1.10 or greater ensures the anchoring effect of the adhesive layer on the inorganic layer, ensuring adhesion of the inorganic layer to the substrate film via the adhesive layer. This allows the content of particles such as nanosilica particles to be reduced in the surface layer on the adhesive layer side of the substrate film. This reduces the manufacturing cost of the laminate film. Therefore, the laminate film of the present invention ensures adhesion of the inorganic layer to the substrate film while suppressing manufacturing costs.

1 is a cross-sectional view of one embodiment of a laminated film of the present invention. The laminated film shown in FIG. 1 includes an anti-reflection layer as an inorganic layer. 3A and 3B show an example of a method for producing the laminated film shown in Fig. 1. Fig. 3A shows a cured resin layer forming step, Fig. 3B shows an adhesion layer forming step, and Fig. 3C shows an inorganic layer forming step. 2 is a schematic diagram of an apparatus for carrying out a plasma treatment step and a film formation step in the example of the method for producing the laminated film shown in FIG. 1. [0023]FIG. 5 is a perspective view showing the positional relationship between a low inductance antenna and a base film in the plasma processing chamber shown in FIG. 4. FIG. 5 is a cross-sectional view showing the positional relationship between the low inductance antenna and the base film in the plasma processing chamber shown in FIG. 4. 3 is a schematic diagram of an observation image of a cross section of a sample in Example 1. FIG. FIG. 10 is a schematic diagram of an observation image of a cross section of a sample in Comparative Example 1.

As shown in Figure 1, the laminate film X of one embodiment of the present invention comprises a substrate film 10, an adhesive layer 21, and an inorganic layer 22, in this order in the thickness direction H. The laminate film X extends in a direction (plane direction D) perpendicular to the thickness direction H. The laminate film X is, for example, an anti-reflection film or a transparent conductive film. However, the laminate film X may also be another type of film.

In this embodiment, the base film 10 comprises a resin film 11 and a cured resin layer 12, arranged in this order in the thickness direction H. In this embodiment, the resin film 11 and the cured resin layer 12 are in contact with each other. In the base film 10, the cured resin layer 12 forms the first surface 10a, and the resin film 11 forms the second surface 10b.

Resin film 11 is an element that ensures the strength of laminate film X. Resin film 11 is, for example, a flexible, transparent resin film. Examples of materials for resin film 11 include polyester resin, polyolefin resin, cellulose resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, and polystyrene 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 standpoints of transparency and strength, the material for resin film 11 is preferably at least one selected from the group consisting of polyester resin, polyolefin resin, and cellulose resin, and more preferably at least one selected from the group consisting of PET, COP, and TAC. In addition, in this embodiment, the resin film 11 does not contain particles.

The thickness of the resin film 11 is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. When the thickness of the resin film 11 is equal to or greater than the above-mentioned lower limit, the strength of the laminate film X can be ensured. When the thickness of the resin film 11 is equal to or less than the above-mentioned upper limit, the handleability of the base film 10 in the roll-to-roll process described below can be ensured. Furthermore, a carrier film may be laminated to the second surface 10b of the resin film 11 to ensure the transportability and handleability of the base film 10 in the roll-to-roll process.

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, and is, for example, 100% or less. When the total light transmittance of the resin film 11 is equal to or greater than the above lower limit, good transparency can be ensured in the laminate film X.

The cured resin layer 12 is a functional layer containing a resin. Specifically, the cured resin layer 12 is a cured product of a curable resin composition containing a curable resin. An example of a functional layer is a hard coat layer. The hard coat layer is a layer that makes it difficult for scratches to form on the exposed surface of the inorganic layer 22 (the upper surface in Figure 1).

Examples of curable resins include polyester resins, acrylic urethane resins, acrylic resins (excluding acrylic urethane resins), urethane resins (excluding acrylic urethane resins), amide resins, silicone resins, epoxy resins, and melamine resins. These curable resins may be used alone or in combination of two or more. From the perspective of ensuring the hardness of the cured resin layer 12, the curable resin is preferably at least one selected from the group consisting of acrylic urethane resins and acrylic resins.

Examples of curable resins include ultraviolet-curable resins and thermosetting resins. The curable resin is preferably ultraviolet-curable resin. When the curable resin is ultraviolet-curable resin, the curable resin can be cured without high-temperature heating, thereby improving the production efficiency of the laminated film X.

When the substrate film 10 has a cured resin layer 12, it is preferable that the cured resin layer 12 contain fewer inorganic oxide particles. The fewer inorganic oxide particles in the cured resin layer 12, the more effectively the scattering of light incident on the laminate film X caused by particles in the substrate film 10 can be suppressed, and the manufacturing costs of the laminate film X can be reduced. Examples of inorganic oxide particle materials include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. The inorganic oxide particle content of the cured resin layer 12 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.2% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.0% by mass.

The thickness of the cured resin layer 12 is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less. When the thickness of the cured resin layer 12 is equal to or greater than the above-mentioned lower limit, the functionality of the cured resin layer 12 can be ensured. Specifically, when the cured resin layer 12 is a hard coat layer, the scratch resistance of the inorganic layer 22 can be ensured. When the thickness of the cured resin layer 12 is equal to or less than the above-mentioned upper limit, the transparency of the cured resin layer 12 can be ensured.

The total light transmittance (JIS K 7375:2008) of the base film 10 is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more, and is, for example, 100% or less. When the total light transmittance of the base film 10 is equal to or greater than the above lower limit, good transparency can be ensured in the laminate film X.

The surface roughness Sa (arithmetic mean height based on ISO 25178-2:2012) of the first surface 10a of the substrate film 10 is preferably 1.0 nm or more, more preferably 1.2 nm or more, even more preferably 1.3 nm or more, and is preferably 10.0 nm or less, more preferably 7.0 nm or less, and even more preferably 4.5 nm or less. When the surface roughness Sa of the first surface 10a is equal to or greater than the above-mentioned lower limit, the fine irregularities on the first surface 10a act as an anchor for the adhesion layer 21, thereby improving the adhesion of the inorganic layer 22 to the substrate film 10 via the adhesion layer 21. When the surface roughness Sa of the first surface 10a is equal to or less than the above-mentioned upper limit, excessive irregularities at the interface within the inorganic layer 22, as described below, can be suppressed.

The first surface 10a is, for example, a plasma-treated surface. The plasma treatment is preferably an inductively coupled plasma treatment using an oxygen-containing gas (oxygen-LAICP treatment) generated by applying high-frequency power to a low-inductance antenna. The oxygen-LAICP treatment of the first surface 10a will be described in detail later in relation to the manufacturing method of the laminated film X.

The adhesion layer 21 is disposed on one surface of the substrate film 10 in the thickness direction H. Specifically, the adhesion layer 21 is disposed on the first surface 10a of the substrate film 10. The adhesion layer 21 contacts the substrate film 10. The adhesion layer 21 is a layer that enhances the adhesion of the inorganic layer 22 to the substrate film 10. Examples of materials for the adhesion layer 21 include metals such as Si, In, Ni, Cr, Ar, Sn, Au, Ag, Pt, Zn, Ti, W, Zr, Nb, and Pd, alloys of two or more of these metals, and oxides of these metals. From the viewpoint of achieving both adhesion to both the substrate film 10 and the inorganic layer 22 and transparency of the adhesion layer 21, the adhesion layer 21 is preferably an inorganic oxide film containing at least one element selected from the group consisting of Si, In, Al, Sn, Ti, Zr, and Nb. From the viewpoint of achieving both adhesion to both the base film 10 and the inorganic layer 22 and transparency of the adhesion layer 21, indium tin oxide (ITO) or silicon oxide (SiOx) is more preferred as the material for the adhesion layer 21. The silicon oxide used as the material for the adhesion layer 21 is preferably SiOx with a lower oxygen content than the stoichiometric composition, and more preferably SiOx with x between 1.2 and 1.9.

The thickness of the adhesion layer 21 is preferably 1 nm or more, more preferably 2 nm or more, even more preferably 3 nm or more, and is preferably 50 nm or less, more preferably 30 nm or less, even more preferably 10 nm or less, and even more preferably 5 nm or less. When the thickness of the adhesion layer 21 is at least the above-mentioned lower limit, the adhesion between the base film 10 and the inorganic layer 22 can be ensured. When the thickness of the adhesion layer 21 is at most the above-mentioned upper limit, the transparency of the adhesion layer 21 can be ensured.

The inorganic layer 22 is disposed on one surface of the adhesive layer 21 in the thickness direction H. The inorganic layer 22 is in contact with the adhesive layer 21. Examples of the inorganic layer 22 include an anti-reflective layer and a conductive layer. An anti-reflective layer is a layer with anti-reflective properties that suppresses the reflection intensity of external light. A conductive layer is a layer with conductivity. The inorganic layer 22 may be another layer. Alternatively, the inorganic layer 22 may be a composite layer including an anti-reflective layer and another layer. The inorganic layer 22 may be a composite layer including a conductive layer and another layer.

The inorganic layer 22 serving as an anti-reflection layer preferably comprises multiple transparent inorganic oxide films stacked in the thickness direction H. Figure 2 shows an example of such an inorganic layer 22. The inorganic layer 22 (anti-reflection layer) in Figure 2 comprises a high refractive index layer 22a, a low refractive index layer 22b, a high refractive index layer 22c, and a low refractive index layer 22d, in this order from the adhesive layer 21 side in the thickness direction H. The high refractive index layer 22a is in contact with the adhesive layer 21. The high refractive index layer 22a is in contact with the low refractive index layer 22b. The low refractive index layer 22b is in contact with the high refractive index layer 22c. The high refractive index layer 22c is in contact with the low refractive index layer 22d. The high refractive index layers 22a and 22c have relatively high refractive indices, while the low refractive index layers 22b and 22d have relatively low refractive indices. In this layered structure, the intensity of the reflected light is attenuated by interference between reflected light at multiple interfaces in the high-refractive-index layers 22a, 22c and the low-refractive-index layers 22b, 22d. This interference effect can be achieved by adjusting the optical film thickness (the product of the film's refractive index and thickness) of each layer in the inorganic layer 22.

The high-refractive-index layer 22a (first high-refractive-index layer) is made of a high-refractive-index material having a refractive index of preferably 1.9 or more at a wavelength of 550 nm. Examples of high-refractive-index materials include niobium oxide (Nb ₂ O ₅ ), titanium oxide, zirconium oxide, indium tin oxide (ITO), and antimony tin oxide (ATO). From the viewpoint of achieving both a high refractive index and low absorption of visible light, the high-refractive-index material is preferably niobium oxide (refractive index 2.33). The optical film thickness of the high-refractive-index layer 22a is, for example, 20 nm or more and, for example, 55 nm or less.

The low-refractive-index layer 22b (first low-refractive-index layer) is made of a low-refractive-index material having a refractive index of preferably 1.6 or less at a wavelength of 550 nm. Examples of low-refractive-index materials include silicon dioxide ( _SiO2 ) and magnesium fluoride. From the viewpoint of achieving both a low refractive index and low absorption of visible light, the low-refractive-index material is preferably silicon dioxide (refractive index 1.46). The optical film thickness of the low-refractive-index layer 22b is, for example, 15 nm or more and, for example, 70 nm or less.

The high-refractive-index layer 22c (second high-refractive-index layer) is made of a high-refractive-index material having a refractive index of preferably 1.9 or greater at a wavelength of 550 nm. Examples of high-refractive-index materials include the materials described above for the high-refractive-index layer 22a, with niobium oxide being preferred. The optical film thickness of the high-refractive-index layer 22c is, for example, 60 nm or greater and, for example, 330 nm or less.

The low-refractive-index layer 22d (second low-refractive-index layer) is made of a low-refractive-index material whose refractive index at a wavelength of 550 nm is preferably 1.6 or less. Examples of low-refractive-index materials include the materials described above for the low-refractive-index layer 22b, with silicon dioxide being preferred. The optical film thickness of the low-refractive-index layer 22d is, for example, 100 nm or more and, for example, 160 nm or less.

The total thickness of the inorganic layer 22 as an anti-reflection layer is preferably 180 nm or more, more preferably 200 nm or more, even more preferably 220 nm or more, and preferably 320 nm or less, more preferably 280 nm or less, even more preferably 250 nm or less. In this embodiment, the total thickness of the inorganic layer 22 as an anti-reflection layer is the sum of the thicknesses of the high refractive index layers 22a, 22c and the low refractive index layers 22b, 22d. When the total thickness of the inorganic layer 22 is equal to or greater than the above-mentioned lower limit, the inorganic layer 22 can ensure its function of attenuating the reflected light intensity. When the total thickness of the inorganic layer 22 is equal to or less than the above-mentioned upper limit, cracking of the inorganic layer 22 can be suppressed.

The inorganic layer 22 serving as a conductive layer is formed from a conductive material. Examples of conductive materials include metals and metal oxides. Examples of metals include copper, silver, gold, nickel, chromium, and alloys thereof. Examples of metal oxides include indium-containing conductive oxides and antimony-containing conductive oxides. Examples of indium-containing conductive oxides include indium-tin composite oxide (ITO), indium-zinc composite oxide (IZO), indium-gallium composite oxide (IGO), and indium-gallium-zinc composite oxide (IGZO). Examples of antimony-containing conductive oxides include antimony-tin composite oxide (ATO).

The inorganic layer 22 has a surface 22A on the side opposite the substrate film 10. The surface roughness Sa (arithmetic mean height according to ISO 25178-2:2012) of the surface 22A is preferably 4.5 nm or less, more preferably 3.0 nm or less, even more preferably 2.5 nm or less, even more preferably 2.0 nm or less, and even more preferably 1.7 nm or less. When the surface roughness Sa of the surface 22A is equal to or less than the above upper limit, light scattering at the surface 22A can be suppressed. Furthermore, the surface roughness Sa of the surface 22A is preferably 1.0 nm or more, more preferably 1.3 nm or more, even more preferably 1.5 nm or more, and even more preferably greater than 1.5 nm. When the surface roughness Sa of the surface 22A is equal to or greater than the above lower limit, friction at the surface 22A can be reduced, ensuring good transportability of the laminate film X, for example, in a roll-to-roll method for producing the laminate film X. The method for measuring the surface roughness Sa is as described below in the examples.

In a cross-sectional view of the laminate film X in the thickness direction H, the interface between the base film 10 and the adhesive layer 21 has fine irregularities (not shown). The interface between two adjacent layers in the inorganic layer 22 also has fine irregularities (not shown). Microscopic irregularities are, for example, irregularities on the order of nanometers. In a cross-sectional view of such laminate film X in the thickness direction H, the ratio (L2/L1) of the second interface length L2 at the interface (second interface) between the adhesive layer 21 and the inorganic layer 22 to the first interface length L1 at the interface (first interface) between the base film 10 and the adhesive layer 21 is 1.10 or greater, preferably 1.20 or greater, more preferably 1.30 or greater, and even more preferably 1.35 or greater. The first interface length L1 is the length of the first interface within a range of, for example, 70 nm in the plane direction D in one cross-sectional view. The second interface length L2 is the length of the second interface within the same range in the plane direction D in the same cross-sectional view. The method for measuring the first interface length L1 and the second interface length L2 is as described below in the examples. When the ratio (L2/L1) is equal to or greater than the lower limit, the adhesiveness of the inorganic layer 22 in the laminate film X is enhanced by the anchor effect. Furthermore, the ratio (L2/L1) is preferably equal to or less than 2.00, more preferably equal to or less than 1.70, and even more preferably equal to or less than 1.50. When the ratio (L2/L1) is equal to or less than the upper limit, the surface roughness Sa of the surface 22A of the inorganic layer 22 can be reduced. When the inorganic layer 22 is an anti-reflective layer, reducing the surface roughness Sa of the surface 22A can reduce light scattering at the surface 22A. Examples of methods for adjusting the ratio (L2/L1) include adjusting the amount of oxygen gas introduced in the oxygen-LAICP treatment process, adjusting the frequency of the high-frequency power in the high-frequency power source, adjusting the magnitude of the applied power, and adjusting the treatment time.

The second interface length L2 is preferably 90 nm or more, more preferably 100 nm or more, even more preferably 110 nm or more, and even more preferably 115 nm or more, and is preferably 160 nm or less, more preferably 140 nm or less, and even more preferably 130 nm or less. When the second interface length L2 is equal to or greater than the above-mentioned lower limit, the adhesion of the inorganic layer 22 to the substrate film 10 via the adhesion layer 21 can be improved. When the second interface length L2 is equal to or less than the above-mentioned upper limit, the roughness of the surface 22A of the inorganic layer 22 can be adjusted.

The peeling rate of the inorganic layer 22 of laminate film X in the second test described below after the first test (accelerated weather resistance test) described below is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less, from the perspective of ensuring the adhesion of the inorganic layer 22. More specific methods for the first and second tests are as described below in the examples. When the peeling rate of the inorganic layer 22 is equal to or less than the above upper limit, it is possible to suppress a decrease in the actual functionality of the inorganic layer 22 due to peeling of the inorganic layer 22.

First test:
First, the substrate film 10 side of the laminate film X is fixed to a glass plate. Next, the inorganic layer 22 of the laminate film X on the glass plate is irradiated with light for 32.5 hours under conditions of a temperature of 85°C, a relative humidity of 45%, and an irradiation intensity (integrated illuminance from 290 nm to 450 nm) of 150 mW/ ^cm2 .

Second test:
First, eleven parallel first incisions (1 mm apart) extending linearly in a first direction and eleven parallel second incisions (1 mm apart) extending linearly in a second direction perpendicular to the first direction were made with a cutter knife on the inorganic layer 22 and the adhesive layer 21 of the laminate film X on the glass plate after the first test. The first and second incisions formed 100 grids. Next, isopropyl alcohol was continuously dripped at 2 mL/min on the 100 grid areas of the laminate film X, while a polyester wiper was slid over the area under the following conditions: a wiper contact surface of 20 mm x 20 mm, a load of 1.5 kg/20 mm, a sliding speed of 50 mm/sec, and 1,000 reciprocations. Next, the number of grids that exhibited peeling of 0.25 ^mm or more was counted. The count was then divided by 100 to calculate the peeling rate (%).

As described above, in laminate film X, the ratio (L2/L1) of the second interface length L2 at the interface between the adhesive layer 21 and the inorganic layer 22 to the first interface length L1 at the interface between the base film 10 and the adhesive layer 21 in a cross-sectional view in the thickness direction H is 1.10 or greater. In such laminate film X, the ratio (L2/L1) of 1.10 or greater ensures the anchoring effect of the adhesive layer 21 on the inorganic layer 22, ensuring adhesion of the inorganic layer 22 to the base film 10 via the adhesive layer 21. This reduces the content of particles such as nanosilica particles in the surface layer of the base film 10 facing the adhesive layer 21. This reduces the manufacturing cost of laminate film X. Therefore, laminate film X ensures adhesion of the inorganic layer 22 to the base film 10 while suppressing manufacturing costs.

Figures 3A to 3C show an example of a method for manufacturing laminated film X. This manufacturing method includes a cured resin layer formation process (Figure 3A), a plasma treatment process, and a film formation process (Figures 3B and 3C).

In the cured resin layer formation process, as shown in FIG. 3A, a cured resin layer 12 is formed on a long resin film 11. This results in a substrate film 10. The cured resin layer 12 can be formed by applying the above-described curable resin composition to the resin film 11 to form a coating film, and then curing the coating film. The curable resin composition may contain other components in addition to the above-described curable resin, as necessary. Examples of other components include solvents and leveling agents. Examples of solvents include butyl acetate, ethyl acetate, toluene, and cyclopentanone. When the curable resin composition contains an ultraviolet-curable resin as the curable resin, the curable resin composition preferably contains a photopolymerization initiator. When the curable resin composition contains a thermosetting resin as the curable resin, the curable resin composition preferably contains a thermal polymerization initiator.

If the curable resin composition contains a solvent, the coating on the resin film 11 is dried after the curable resin composition is applied. The drying temperature is, for example, 50°C or higher and, for example, 120°C or lower. The drying time is, for example, 10 seconds or longer and, for example, 10 minutes or shorter.

When the curable resin composition contains an ultraviolet-curable resin, the coating film on the resin film 11 is cured by ultraviolet irradiation. Examples of light sources for ultraviolet irradiation include high-pressure mercury lamps and LED lights. The cumulative irradiation amount of the ultraviolet light is, for example, 100 mJ/ ^cm2 or more and, for example, 500 mJ/ ^cm2 or less.

When the curable resin composition contains a thermosetting resin, the coating on the resin film 11 is cured by heating. The heating temperature is, for example, 100°C or higher and, for example, 150°C or lower. The heating time is, for example, 10 seconds or higher and, for example, 10 minutes or shorter.

In this manner, a long substrate film 10 can be produced. In this embodiment, a roll of the long substrate film 10 is prepared. Specifically, the substrate film 10 is wound so that the first surface 10a of the substrate film 10 faces inward in the radial direction of the roll.

In this manufacturing method, the substrate film 10 is then transported as a workpiece film W using a roll-to-roll method under reduced pressure, while a plasma treatment process and a film formation process are carried out sequentially. The device Y shown in Figure 4 is an example of a device for carrying out the plasma treatment process and the film formation process. Device Y includes a feed chamber R1, a winding chamber R2, a connection chamber C1, a plasma treatment chamber C2, a connection chamber C3, a film formation chamber C4, a connection chamber C5, a connection chamber C6, and a PEM device (not shown).

The unwinding chamber R1 is equipped with a unwinding roller 51 for unwinding the workpiece film W. A roll of long base film 10 is attached to the unwinding roller 51 as the workpiece film W. Also, a predetermined number of guide rollers G for guiding the workpiece film W are provided within the unwinding chamber R1.

The winding chamber R2 is equipped with a winding roller 52 for winding up the workpiece film W. A predetermined number of guide rollers G for guiding the workpiece film W are provided within the winding chamber R2.

The connecting chamber C1 is located next to the unwinding chamber R1 in the travel direction of the workpiece film W and before the plasma processing chamber C2. A predetermined number of guide rollers G for guiding the workpiece film W are provided within the connecting chamber C1. The connecting chamber C1 is connected to a vacuum pump (not shown) and is configured to allow the pressure within the chamber to be adjusted. When the device Y is in operation, the pressure within the connecting chamber C1 is maintained at a predetermined pressure between the pressure within the unwinding chamber R1 and the pressure within the plasma processing chamber C2. This ensures a pressure difference between the unwinding chamber R1 and the plasma processing chamber C2.

Plasma processing chamber C2 is located between connection chamber C1 and connection chamber C3 in the running direction of the workpiece film W. In plasma processing chamber C2, the plasma processing process is carried out as described below.

In this embodiment, the plasma processing chamber C2 is equipped with multiple low-inductance antennas (LA) 71. A low-inductance antenna is an antenna that has a low inductance of 7.5 μH or less and is capable of generating inductively coupled plasma when high-frequency power is applied. In this embodiment, the LAs 71 are supported by mounting fixtures 72 and covered by cover blocks 73 (not shown in FIG. 5) and are placed inside the plasma processing chamber C2, as shown in FIGS. 5 and 6 (an example is shown in which there are four LAs 71).

The multiple LAs 71 are aligned in the running direction of the base film 10 and in a direction perpendicular to the running direction (the width direction of the base film 10). The fixture 72 is a vacuum flange. As shown in FIG. 6, the LAs 71 are fixed to the fixture 72 via feedthroughs 74. As shown in FIG. 4, the fixture 72 is attached to an opening 75 in the wall of the plasma processing chamber C2. Specifically, the fixture 72 is attached to the opening 75 with a seal member (not shown) sandwiched between the wall of the plasma processing chamber C2 and the fixture 72. The LAs 71 are electrically connected to a high-frequency power source (RF power source) outside the plasma processing chamber C2 via an impedance matcher. The LAs 71 are formed of a conductor. Examples of conductors include copper and silver, with copper being preferred. The LAs 71 may be covered with an insulator. Examples of insulators include glass and quartz.

The cover block 73 comprises a block body 73A and multiple partition plates 73B. The block body 73A has multiple storage spaces 73a. Each storage space 73a houses one LA 71. The partition plates 73B are arranged to close the storage spaces 73a. The storage spaces 73a are sealed spaces. In the cover block 73, the block body 73A is made of, for example, aluminum. Examples of aluminum include aluminum A5052. The partition plates 73B are made of an insulating material. Examples of insulating materials include quartz and glass. The separation distance d' (shown in Figure 6) between the substrate film 10 traveling within the plasma processing chamber C2 and the cover block 73 is, for example, 50 to 200 mm. Such a cover block 73 helps to avoid damage and contamination of the LA 71 due to plasma treatment without excessively reducing the plasma conversion efficiency caused by the power applied to the LA 71, and also helps to suppress damage to the substrate film 10 being plasma treated.

As shown in FIG. 5 , in this embodiment, the LA 71 has an open loop shape. Having an open loop shape for the LA 71 is advantageous for reducing the inductance of the LA 71. Therefore, the open loop LA 71 can suppress an increase in voltage due to an increase in power applied to the LA 71. This suppresses abnormal discharge during plasma processing, as described below. Suppressing abnormal discharge also suppresses damage to the substrate film 10 being plasma-processed. Specifically, the LA 71 has a U-shape with two free ends. For each LA 71, the two free ends are fixed to a fixture 72 so as to be aligned in the width direction of the substrate film 10. In this embodiment, the LA 71 also has an extension portion 71a on the side opposite the two free ends. The extension portion 71a extends parallel to the substrate film 10 passing through the plasma processing chamber C2. The extension portion 71a extends in the width direction of the substrate film 10. Each extension 71a may extend in the running direction of the base film 10 (four LAs 71 may be arranged in this manner). The length of the extension 71a is, for example, 50 to 150 mm (FIG. 5 exemplarily illustrates a case where the length of the extension 71a is the same as the maximum length _d2 of the LA 71, which will be described later). The LA 71 may have a coil shape instead of an open loop shape.

The LA 71 extends from the fixture 72 toward the base film 10. The LA 71 preferably extends perpendicular to the fixture 72. The extension length d ₁ of the LA 71 from the fixture 72 is, for example, 30 to 150 mm. The maximum length d ₂ of the LA 71 in the plane direction of the base film 10 is, for example, 50 to 150 mm. The separation distance d ₃ (shown in FIG. 6 ) between the LA 71 and the base film 10 is, for example, 50 to 200 mm. The extension length d ₁ and the separation distance d ₃ are preferably the same. The ratio (d ₃ /d ₁ ) of the separation distance d ₃ to the extension length d ₁ is, for example, 0.5 to 3.5. The number of LAs 71 (rows) spaced apart in the running direction of the base film 10 may be 1, 2, or 3, or may be 4 or more if necessary, depending on the running speed of the base film 10 (i.e., plasma treatment time). The center-to-center distance _d4 between adjacent LAs 71 in the running direction of the base film 10 is, for example, 100 to 500 mm. The center-to-center distance d5 between adjacent LAs 71 in the width direction of the base film ₁₀ is, for example, 200 to 500 mm. By adjusting the center-to-center distance _d5 , the uniformity of the plasma density (described below) in the width direction of the base film 10 can be controlled. The center-to-center distances _d4 and _d5 are preferably the same. The ratio ( _d5 / _d4 ) of the center-to-center distance _d5 to the center-to-center distance _d4 is, for example, 0.5 to 2.0. The centers of the extensions 71a of the four LAs 71 preferably form a square with their vertices as vertices. High density plasma with high in-plane uniformity can be generated by using such a set of LAs 71. As the LAs 71, for example, a high frequency antenna for plasma generation described in Japanese Patent Laid-Open No. 2013-258153 can be used.

In this embodiment, the plasma processing chamber C2 further includes a transport roller 53. The transport roller 53 is a main guide roller for transporting the workpiece film W within the plasma processing chamber C2. The transport roller 53 has a temperature control function that allows it to heat or cool the workpiece film W. In other words, the transport roller 53 is a transport roller with a temperature control function. When the device Y is operating, the transport roller 53 transports the base film 10 while contacting the second surface 10b of the base film 10. The LA71 is positioned opposite the transport roller 53. With the device Y equipped with this plasma processing chamber C2, in the plasma processing step S2, the transport roller 53 with a temperature control function that contacts the base film 10 can perform plasma processing on the base film 10 while cooling or heating the base film 10. By controlling the temperature of the base film 10, thermal deformation of the base film 10 can be suppressed, and the effect of this thermal deformation on the transport of the base film 10 can also be suppressed.

The PEM device is used to perform plasma emission monitoring (PEM) during plasma processing, and comprises a device main body and an optical fiber for collecting light. The tip (one end) of the optical fiber is positioned within the plasma processing chamber C2, between the workpiece film W and LA71 in the direction of separation between them. The other end of the optical fiber is connected to the device main body. In addition, a first line L1 equipped with a flow control valve for introducing gas into the chamber is connected to the plasma processing chamber C2.

The connecting chamber C3 is located next to the plasma processing chamber C2 in the travel direction of the workpiece film W and before the film deposition chamber C4. A predetermined number of guide rollers G are provided within the connecting chamber C3 to guide the workpiece film W. The connecting chamber C3 is connected to a vacuum pump (not shown) and is configured to allow the pressure within the chamber to be adjusted. When the device Y is in operation, the pressure within the connecting chamber C3 is maintained at a predetermined pressure between the pressure within the plasma processing chamber C2 and the pressure within the film deposition chamber C4. This ensures a pressure difference between the plasma processing chamber C2 and the film deposition chamber C4.

The film-forming chamber C4 is located next to the connection chamber C3 in the running direction of the workpiece film W. The film-forming chamber C4 is also connected to a vacuum pump (not shown), allowing the chamber to be adjusted to a predetermined vacuum level. The film-forming process is carried out in the film-forming chamber C4, as described below.

In this embodiment, the film-forming chamber C4 is a sputtering chamber. The film-forming chamber C4 includes a film-forming roller 54 and multiple sputtering chambers 60 (sputtering chambers 60a-60e) (five sputtering chambers 60 are shown as an example). The film-forming roller 54 is a main guide roller for transporting the workpiece film W within the film-forming chamber C4. The film-forming roller 54 has a temperature control function that allows the workpiece film W to be heated or cooled. The sputtering chamber 60 is a partitioned space within the film-forming chamber C4. The multiple sputtering chambers 60 are arranged circumferentially around the film-forming roller 54. Each sputtering chamber 60 opens toward the film-forming roller 54. A cathode 61 is provided within the sputtering chamber 60. A target (not shown) is placed on the cathode 61 as a film-forming material supply. The target is placed on the target so as to face the film-forming roller 54. Each sputtering chamber 60 is equipped with a power supply (not shown) for applying voltage to the target to generate a glow discharge. Examples of power supplies include DC power supplies, AC power supplies, MF power supplies, RF power supplies, and MF-AC power supplies. MF-AC power supplies refer to AC power supplies with frequencies ranging from several kHz to several MHz. Each sputtering chamber 60 is connected to a required number of second lines (not shown) equipped with flow control valves for introducing gas into the chamber. Additionally, a predetermined number of guide rollers G for guiding the workpiece film W are installed within deposition chamber C4.

Connecting chambers C5 and C6 are arranged, in this order, between the film forming chamber C4 and the winding chamber R2 in the running direction of the workpiece film W. A predetermined number of guide rollers G are provided within connecting chamber C5 for guiding the workpiece film W. A predetermined number of guide rollers G are provided within connecting chamber C6 for guiding the workpiece film W. Connecting chamber C5 is connected to a vacuum pump (not shown) and is configured to allow the pressure inside the chamber to be adjusted. Connecting chamber C6 is connected to a vacuum pump (not shown) and is configured to allow the pressure inside the chamber to be adjusted. When device Y is operating, the pressure inside connecting chambers C5 and C6 is maintained at a predetermined pressure between the pressure inside film forming chamber C4 and the pressure inside winding chamber R2. This ensures a pressure difference between film forming chamber C4 and winding chamber R2.

Using the above-described device Y, the plasma treatment process and film formation process are carried out sequentially. Specifically, they are as follows:

The workpiece film W is unwound from the unwinding chamber R1. After being unwound from the unwinding chamber R1, the workpiece film W passes through the connecting chamber C1, plasma treatment chamber C2, connecting chamber C3, film formation chamber C4, connecting chamber C5, and connecting chamber C6 in sequence, before being wound up in the winding chamber R2. The running speed of the workpiece film W is, for example, 0.5 m/min or more and, for example, 5 m/min or less. Furthermore, the entire line from the unwinding chamber R1 to the winding chamber R2 is not open to the atmosphere along the way, and the process is carried out in this line under a reduced pressure atmosphere. The reduced pressure atmosphere is preferably under vacuum. Under vacuum preferably means a reduced pressure atmosphere of 7 Pa or less.

The plasma treatment process is carried out in the plasma treatment chamber C2. In the plasma treatment process, the first surface 10a of the substrate film 10 is plasma-treated in a reduced pressure atmosphere in the plasma treatment chamber C2 (chamber) while the plasma emission intensity is monitored. In this embodiment, the plasma treatment is a treatment using inductively coupled plasma of an oxygen-containing gas (oxygen-LAICP treatment) generated by applying high-frequency power to the LA71. Specifically, it is as follows:

During plasma treatment, oxygen is supplied into the plasma treatment chamber C2 via the first line L1. In addition to oxygen, an inert gas may also be supplied into the plasma treatment chamber C2. Examples of inert gases include argon, krypton, and xenon. The oxygen concentration of the gas (oxygen-containing gas) in the plasma treatment chamber C2 is preferably 30% by volume or more, more preferably 50% by volume or more, even more preferably 80% by volume or more, even more preferably 90% by volume or more, even more preferably 95% by volume or more, and particularly preferably 100% by volume. When the oxygen concentration is above the above-mentioned lower limit, high-density oxygen plasma can be generated. This is useful for creating nanometer-order fine irregularities on the first surface 10a of the substrate film 10 and for highly activating the first surface 10a by cleaning it.

The pressure (first pressure) within the plasma processing chamber C2 during plasma processing is preferably 0.1 Pa or more, more preferably 0.2 Pa or more, even more preferably 0.3 Pa or more, and preferably 7 Pa or less, more preferably 5 Pa or less, and even more preferably 3 Pa or less. When the first pressure is equal to or greater than the above-mentioned lower limit, a plasma environment of sufficient density for surface modification of the first surface 10a of the substrate film 10 can be formed within the plasma processing chamber C2. When the first pressure is equal to or less than the above-mentioned upper limit, thermal damage to the first surface 10a caused by excessively high-density plasma can be suppressed during plasma processing, and excessive roughening of the first surface 10a can be suppressed. Suppressing excessive roughening helps to prevent a decrease in the mechanical strength of the first surface 10a. The first pressure can be adjusted by the amount of oxygen gas supplied into the plasma processing chamber C2.

The frequency of the high-frequency power applied to LA71 during plasma treatment is preferably 1 MHz or higher, more preferably 5 MHz or higher, even more preferably 10 MHz or higher, and preferably 100 MHz or lower, more preferably 80 MHz or lower, and even more preferably 60 MHz or lower. When the frequency is above the lower limit, plasma current density can be increased while stabilizing plasma discharge during plasma treatment. When the frequency is below the upper limit, the antenna potential can be suppressed, thereby suppressing damage to the substrate film 10 caused by the plasma. Furthermore, the high-frequency power is preferably 0.1 kW or higher, more preferably 0.3 kW or higher, even more preferably 1.0 kW or higher, and preferably 10 kW or lower, more preferably 8 kW or lower, and even more preferably 6 kW or lower. When the high-frequency power is above the lower limit, a high-density plasma environment can be formed in the plasma treatment chamber C2 during inductively coupled plasma treatment. When the high-frequency power is below the upper limit, excessive damage to the substrate caused by the plasma can be suppressed.

In the plasma treatment process, the plasma emission intensity during the plasma treatment is preferably monitored using a PEM device. Then, based on the monitoring results, the amount of oxygen gas introduced, the high-frequency power, the travel speed, etc. are controlled.

In the plasma treatment step, the plasma current density at the intermediate position between the LA 71 and the substrate film 10 is preferably 1.0 mA/ ^cm³ or more, more preferably 2.0 mA/ ^cm³ or more, even more preferably 3.0 mA/ ^cm³ or more, and preferably 10 mA/cm³ or ^less , more preferably 8 mA/cm³ or ^less , and even more preferably 4 mA/cm³ or ^less . Inductively coupled plasma treatment using a low-inductance antenna can achieve a higher plasma current density than capacitively coupled plasma treatment (e.g., a plasma density approximately 100 times higher). When the plasma current density is equal to or greater than the lower limit, sufficient plasma-converted oxygen particles can be secured in the plasma treatment chamber C2 during plasma treatment, allowing for appropriate surface modification of the first surface 10a of the substrate film 10. When the plasma current density is equal to or less than the upper limit, damage to the first surface 10a due to excessively high density plasma-converted oxygen particles can be suppressed during plasma treatment. The plasma current density can be adjusted by, for example, adjusting the amount of oxygen gas introduced into the plasma processing chamber C2, adjusting the frequency of the high frequency power in the high frequency power supply, and adjusting the magnitude of the applied power.

In the film formation process, following the plasma treatment process, an adhesion layer 21 and an inorganic layer 22 are sequentially formed on the first surface 10a of the substrate film 10 by sputtering in a reduced pressure atmosphere. The reduced pressure atmosphere is preferably a vacuum.

In the sputtering method, a sputtering gas (inert gas) is introduced into each sputtering chamber 60 via a second line, while a negative voltage is applied to a target (film-forming material) placed on a cathode 61 inside the sputtering chamber 60. This generates a glow discharge, ionizing the gas atoms, causing the gas ions to collide with the target surface at high speed, ejecting the target material from the target surface and depositing it on the workpiece film W. Examples of sputtering gases include argon, krypton, and xenon.

When the film-forming material is a metal oxide, the sputtering method may be reactive sputtering. In reactive sputtering, oxygen (a reactive gas) is introduced into the sputtering chamber 60 in addition to the sputtering gas. The oxygen is introduced into the sputtering chamber 60 via another second line. In reactive sputtering, the target is made of, for example, a metal in the metal oxide that forms each layer.

In the sputtering method, the pressure (second pressure) inside the sputtering chamber 60 is, for example, 0.1 to 5.0 Pa depending on the type of layer being formed. The film formation temperature (the temperature of the workpiece film W, which is adjusted by the film formation roller 54) is, for example, -10°C to 150°C.

In the film formation process, first, an adhesion layer 21 is formed on the substrate film 10 by sputtering in the sputtering chamber 60a. When an ITO layer is formed as the adhesion layer 21, an ITO target is used as the target placed on the cathode 61 in the sputtering chamber 60a. Then, sputtering is performed while introducing argon into the sputtering chamber 60a. Alternatively, reactive sputtering is performed while introducing argon and oxygen into the sputtering chamber 60a.

In the film formation process, an inorganic layer 22 is then formed on the adhesion layer 21 by sputtering in at least one sputtering chamber selected from sputtering chambers 60b to 60e. For example, when forming an inorganic layer 22 (Figure 2) as an anti-reflection layer, a high refractive index layer 22a is formed on the adhesion layer 21 in sputtering chamber 60b, a low refractive index layer 22b is formed on the high refractive index layer 22a in sputtering chamber 60c, a high refractive index layer 22c is formed on the low refractive index layer 22b in sputtering chamber 60d, and a high refractive index layer 22d is formed on the high refractive index layer 22c in sputtering chamber 60e.

In device Y, after the plasma treatment process and film formation process, the laminated film X serving as the workpiece film W passes through connecting chambers C5 and C6 and enters winding chamber R2, where it is wound up by winding roller 52.

In this way, a long laminated film X can be produced.

The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to these examples. Furthermore, the specific numerical values of the compounding amounts (contents), physical properties, parameters, etc. described below can be substituted for the upper limits (numerical values defined as "equal to or less than") or lower limits (numerical values defined as "equal to or greater than") of the corresponding compounding amounts (contents), physical properties, parameters, etc. described in the "Description of the Invention" above.

Example 1
The laminated film of Example 1 was produced by carrying out the following steps in order.

First, a hard coat layer was formed on one side of a triacetyl cellulose (TAC) film as a resin film to prepare a substrate film (preparation step). Specifically, 100 parts by weight (solids equivalent) of a butyl acetate solution of UV-curable acrylic urethane resin (product name "Luxidia 17-806," solids concentration 80% by weight, manufactured by DIC Corporation), 5 parts by weight of a photopolymerization initiator (product name "Omnirad 907," manufactured by IGM Resins), 0.03 parts by weight of a leveling agent (product name "GRANDIC PC4100," manufactured by DIC Corporation), and butyl acetate as a solvent were mixed to prepare a first resin composition with a solids concentration of 75% by weight. Next, cyclopentanone was added as an additional solvent to the first resin composition to prepare a second resin composition with a solids concentration of 50% by weight. Meanwhile, a long TAC film (length 100 m, width 340 mm, thickness 40 μm) was prepared. Next, a second resin composition was applied to one side of the TAC film to form a coating film. This coating film was then dried by heating and then cured by ultraviolet irradiation. This resulted in a 5 μm-thick hard coat (HC) layer being formed on the TAC film. The heating temperature was 100°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 irradiated onto the coating film, with an integrated irradiation dose of 300 mJ/cm ^2. In this manner, a TAC film with an HC layer was prepared as a substrate film.

Next, a plasma treatment process and a subsequent film-forming process were performed on the substrate film while the substrate film was transported in a vacuum using a roll-to-roll method (roll-to-roll process). For the plasma treatment and film-forming processes, an apparatus (first apparatus) capable of performing roll-to-roll processes on a workpiece film was used. The first apparatus included a payout chamber, a plasma treatment chamber, a film-forming chamber, and a winding chamber. The payout chamber, plasma treatment chamber (first plasma treatment), film-forming chamber, and winding chamber were arranged in this order and were connected to each other. The payout chamber included a payout roller. A roll of the substrate film was set on the payout roller as the workpiece film. The plasma treatment chamber included a temperature-controlled transport roller (transport roller 53 in FIG. 4 ) and four low-inductance antennas (LA71 in FIG. 5 and FIG. 6 ) covered by cover blocks (cover block 73 in FIG. 6 ), as shown in FIG. 5 and FIG. 6 . Each low-inductance antenna has an extension (extension 71a in FIG. 5) parallel to the substrate film. The four low-inductance antennas have an extension length _d1 of 88 mm, a maximum length _d2 (length of the extension) of 100 mm, a separation distance _d3 of 112 mm, a center-to-center distance _d4 of 290 mm, and a center-to-center distance _d5 of 280 mm (FIGS. 5 and 6). Each low-inductance antenna is electrically connected to a high-frequency power source (RF power source, frequency 13.56 MHz) via an impedance matcher outside the plasma processing chamber. The separation distance d' between the substrate film traveling within the plasma processing chamber and the cover block is 100 mm. The deposition chamber is a sputtering deposition chamber and includes a deposition roller (deposition roller 54 in FIG. 4) and first and second sputtering chambers (sputtering chambers 60a and 60b in FIG. 4). Each sputtering chamber is a partitioned space within the deposition chamber. The first and second sputtering chambers are arranged in this order along the circumferential direction of the deposition roller and in the running direction of the substrate film. Each sputtering chamber is equipped with a cathode arranged opposite the deposition roller. Each sputtering chamber is connected to a required number of second lines (not shown) equipped with flow rate control valves for introducing gas into the chamber. The winding chamber is equipped with a winding roller.

In the roll-to-roll process, the HC surface (first side) of the base film was plasma treated in the plasma treatment chamber (plasma treatment process). The running speed of the base film (film running speed) was 0.5 m/min. The temperature of the temperature-controlled transport roller was -8°C. The plasma treatment conditions were as follows:

The inside of the apparatus was evacuated until the ultimate vacuum of the plasma treatment chamber reached 1.0 × 10 ⁻⁴ Pa, and then oxygen gas was introduced into the plasma treatment chamber to set the pressure inside the plasma treatment chamber to 0.5 Pa. By applying high-frequency power of 5.0 kW from a high-frequency power supply to the four low-inductance antennas, inductively coupled plasma of an oxygen-containing gas was formed around the antennas (the surface of the HC layer of the substrate film was treated with this plasma).

In the film-forming chamber, an adhesive layer and an inorganic layer were sequentially formed on the plasma-treated substrate film (film-forming process: adhesive layer formation process and inorganic layer formation process). Specifically, while the substrate film was cooled and transported by the film-forming roll in the film-forming chamber, an adhesive layer was formed on the HC layer of the substrate film in the first sputtering chamber, and an inorganic layer was formed on the adhesive layer in the second sputtering chamber. The film-forming temperature (temperature of the film-forming roll) was set to -8°C. More specifically, the process is as follows:

In the first sputtering chamber, a 5 nm thick ITO layer was formed as an adhesion layer by sputtering (adhesion layer formation process). In this process, the film formation chamber was evacuated to an ultimate vacuum of 1.0 × 10 ^-4 Pa, and then argon was introduced as an inert gas into the first sputtering chamber, setting the pressure in the first sputtering chamber to 0.3 Pa. A sintered body of indium oxide and tin oxide (ITO with a tin oxide concentration of 10% by mass) was used as the target. A DC power supply was used as the power source for applying voltage to the target. The discharge power was 1.0 kW.

In the second sputtering chamber, a 20 nm thick _SiO2 layer was formed as an inorganic layer by reactive sputtering. In this process, after the film formation chamber was evacuated as described above, argon as an inert gas and oxygen as a reactive gas were introduced into the second sputtering chamber, and the pressure in the second sputtering chamber was set to 0.3 Pa. The amount of oxygen introduced per 100 volume parts of argon introduced into the second sputtering chamber was 30 volume parts. A Si target was used as the target. A MF-AC power supply (60 kHz) was used as the power source for applying voltage to the target. The discharge power was 3.0 kW.

In this manner, the laminate film of Example 1 was produced. The laminate film of Example 1 included a substrate film with an HC layer, an adhesion layer (ITO) on the HC layer, and an inorganic layer (SiO ₂ ) on the adhesion layer. The substrate film of the laminate film of Example 1 had the HC layer surface plasma-treated. This plasma treatment was an inductively coupled plasma treatment using an oxygen-containing gas generated by application of high-frequency power to a low-inductance antenna (oxygen-LAICP treatment).

Example 2
The laminated film of Example 2 was produced in the same manner as the laminated film of Example 1, except for the following: The running speed of the base film was 1.0 m/min, and the high-frequency power applied in the plasma treatment step was 3.5 kW.

Comparative Example 1
First, in the same manner as in Example 1, an HC layer was formed on one side of a TAC film to prepare a substrate film (TCA film/HC layer).

Next, the substrate film was transported under vacuum using a roll-to-roll method, while undergoing a plasma treatment process and a subsequent film deposition process (roll-to-roll process). A second device capable of performing roll-to-roll processes on workpiece films was used for the plasma treatment and film deposition processes. The second device had the same configuration as the first device, except that it had a second plasma treatment chamber instead of the first plasma treatment chamber. The second plasma treatment chamber had a pair of planar electrodes for generating plasma: a cathode electrode and an anode electrode (both rectangular electrodes made of SUS304). The pair of planar electrodes were spaced 50 mm apart and positioned parallel to the substrate film passing through the second plasma treatment chamber. The anode electrode was positioned 35 mm away from the substrate film passing through the second plasma treatment chamber and was grounded outside the plasma treatment chamber. The cathode electrode was positioned facing the HC layer surface of the substrate film and was electrically connected to a high-frequency power source (RF power source, 13.56 MHz) via an impedance matcher. The length of each electrode facing the base film in the film running direction is 110 mm, and the length in the width direction is 430 mm.

In the roll-to-roll process, the HC surface (first side) of the substrate film was plasma treated (bombardment treatment) in the second plasma treatment chamber. The running speed of the substrate film (film running speed) was 1.0 m/min. The plasma treatment conditions were as follows:

The apparatus was evacuated until the ultimate vacuum in the second plasma treatment chamber reached 1.0 × 10 ^-4 Pa, and then argon was introduced into the second plasma treatment chamber to set the pressure in the plasma treatment chamber to 0.5 Pa. A capacitively coupled plasma (CCP) was generated by applying 550 W of power between the planar electrodes using a high-frequency power supply. In this plasma environment, the surface of the HC layer of the substrate film was subjected to argon ion bombardment treatment (Ar-BB treatment).

In the film formation chamber, an adhesive layer and an inorganic layer were formed sequentially on the plasma-treated substrate film in the same manner as described above for Example 1.

In this manner, a laminate film of Comparative Example 1 was produced. The laminate film of Comparative Example 1 included a substrate film with an HC layer, an adhesion layer (ITO) on the HC layer, and an inorganic layer (SiO ₂ ) on the adhesion layer. The substrate film of the laminate film of Comparative Example 1 had the HC layer surface plasma-treated. This plasma treatment was an ion bombardment treatment (Ar-BB treatment) using capacitively coupled plasma using argon-containing gas.

Comparative Example 2
A laminated film of Comparative Example 2 was produced in the same manner as the laminated film of Example 1, except for the following: The running speed of the base film was 1.0 m/min, and the high-frequency power applied in the plasma treatment step was 2.0 kW.

<Surface free energy>
For each of the laminated films of Examples 1 and 2 and Comparative Examples 1 and 2, the surface free energy of the plasma-treated surface of the substrate film was determined as follows.

First, a substrate film was sampled after plasma treatment but before the formation of an adhesive layer during the manufacturing process of the laminated film, and a sample film of a predetermined size was cut from the substrate film. Next, the sample film was placed on a horizontally placed glass slide. Specifically, the sample film was placed on the glass slide with the plasma-treated surface (HC layer surface) of the sample film facing upward. Next, 2 μL of a predetermined liquid was dropped onto the plasma-treated surface of the sample film on the glass slide in an atmosphere of 23°C and 50% relative humidity to form a droplet (droplet formation). Next, the contact angle of the droplet with respect to the sample film surface (plasma-treated surface) was measured using a contact angle meter (product name "DMs-401", manufactured by Kyowa Interface Science Co., _Ltd. ) (contact angle measurement). The liquids used were water (H _O ), methylene iodide (CH _I ), and 1-bromonaphthalene. For each liquid, a series of steps including droplet formation and subsequent contact angle measurement was performed five times. The measurements were carried out within 24 hours after the plasma treatment of the substrate film. The average of five measurements for each liquid was taken as the contact angle for that liquid. In this way, the contact angle of water (θw), the contact angle of methylene iodide (θi), and the contact angle of 1-bromonaphthalene (θb) for the sample film were obtained.

Next, for each sample film, the contact angle of water θw, the contact angle of methylene iodide θi, and the contact angle of 1-bromonaphthalene θb were used to solve the three simultaneous equations of the Kitazaki-Hata theory, thereby deriving ^γd , γp, and ^γh in the equation γ = ^γd + ^γp + ^γh , which represents the surface free energy ^γ . The Kitazaki-Hata theory is described, for example, in Journal of the Japan Adhesion Association, Vol. 8, No. 3, pp. 131-141 (1972). In this equation, ^γd is the dispersion component of the surface free energy, ^γp is the polar component of the surface free energy, and ^γh is the hydrogen bond component of the surface free energy. The value (γ) obtained by adding ^γd , ^γp , and ^γh was then calculated as the surface free energy of the plasma-treated surface of the sample film. The values required for derivation were: the dispersion component ^γd of the surface free energy of water was set to 29.1 mN/m, the polar component ^γp was set to 1.3 mN/m, and the hydrogen bond component ^γh was set to 42.4 mN/m. The dispersion component ^γd of the surface free energy of methylene iodide was set to 46.8 mN/m, the polar component ^γp was set to 4.0 mN/m, and the hydrogen bond component ^γh was set to 0.0 mN/m. The dispersion component ^γd of the surface free energy of 1-bromonaphthalene was set to 44.4 mN/m, the polar component ^γp was set to 0.1 mN/m, and the hydrogen bond component ^γh was set to 0.0 mN/m. The surface free energies (mN/m) of the plasma-treated surfaces of the sample films are shown in Table 1.

<Surface roughness>
The surface roughness of the first surface of the substrate film was examined for each of the laminate films of Examples 1 and 2 and Comparative Examples 1 and 2. Specifically, first, a substrate film was sampled after plasma treatment and before the formation of the adhesive layer during the manufacturing process of the laminate film, and the surface roughness Sa (arithmetic mean height based on ISO 25178) of the first surface (HC layer surface) of the substrate film was measured in a 1 μm square observation image using an atomic force microscope (product name "Dimension Edge", manufactured by Bruker). In this measurement, the measurement mode was set to tapping mode, and an antimony-doped Si cantilever (product name "RTESP-300", manufactured by Bruker) was used as a probe. The measurement results are shown in Table 1.

<Interface length ratio>
The ratio of the second interface length L2 between the adhesive layer and the inorganic layer to the first interface length L1 between the base film and the adhesive layer in a cross-sectional view was examined for each of the laminate films of Examples 1 and 2 and Comparative Examples 1 and 2. Specifically, the ratio is as follows:

First, a sample for cross-sectional observation of the laminate film was prepared using the FIB microsampling method. For the FIB microsampling method, an FIB device (product name "FB2200", manufactured by Hitachi) was used, with an initial acceleration voltage of 40 kV and a finishing acceleration voltage of 10 kV. Next, the cross-section of the sample was observed using an FE-TEM. For this observation, an FE-TEM device (product name "JEM-2800", manufactured by JEOL) was used, with an acceleration voltage of 200 kV. Figure 7 shows a schematic representation of an example of a cross-sectional image of the sample in Example 1. The HC layer 11, adhesion layer 21, and inorganic layer 22 of the substrate film 10 were observed in the image in Example 1. Figure 8 shows a schematic representation of a cross-sectional image of the sample in Comparative Example 1, as another example. In the observation image of Comparative Example 1, the HC layer 11', adhesive layer 21', and inorganic layer 22' of the base film 10' were observed. The observation image was then analyzed using image processing software ImageJ. As a result, the first interface length L1 of the interface between the base film 10 (10') and adhesive layer 21 (21') and the second interface length L2 of the interface between the adhesive layer 21 (21') and inorganic layer 22 (22') were determined within a predetermined image range in the observation image (cross-sectional view). The ratio of the second interface length L2 to the first interface length L1 (L2/L1) was then calculated. The values are shown in Table 1.

<Adhesion>
The laminated films of Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to the following first and second tests to examine the adhesion of the inorganic layer.

First test:
First, the substrate film side of the laminate film was fixed to a glass plate. Next, the inorganic layer of the laminate film on the glass plate was irradiated with light from a metal halide lamp for 32.5 hours under conditions of a temperature of 85°C, a relative humidity of 45%, and an irradiation intensity (integrated illuminance from 290 nm to 450 nm) of 150 mW/ ^cm2 (accelerated weathering test). This test was performed using an "Eye Super UV Tester SUV-W161" manufactured by Iwasaki Electric Co., Ltd.

Second test:
First, eleven parallel first incisions (1 mm apart) extending linearly in a first direction and eleven parallel second incisions (1 mm apart) extending linearly in a second direction perpendicular to the first direction were made with a cutter knife on the inorganic layer and adhesive layer of the laminate film on the glass plate after the first test. The first and second incisions formed 100 grids. Next, isopropyl alcohol was continuously dripped at 2 mL/min onto the 100 grid areas of the laminate film, while a polyester wiper (trade name "Anticon Gold", manufactured by Sanplatec Co., Ltd.) was slid over the wiper contact surface of 20 mm x 20 mm, a load of 1.5 kg/20 mm, a sliding speed of 50 mm/sec, and 1,000 reciprocations. Next, the number of grids that exhibited peeling of 0.25 ^mm or more was counted. The peeling rate (%) was calculated by dividing the count by 100.

A peeling rate of 5% or less was evaluated as "good," and a peeling rate of more than 5% was evaluated as "poor." The results are shown in Table 1.

[evaluation]
In the laminate film of Comparative Example 1, the HC layer of the substrate film does not contain particles. Therefore, as shown in FIG. 8 , the surface of the substrate film 10′ (the surface on the adhesive layer 21′ side) does not have irregularities due to particles. Furthermore, as described above, the plasma treatment used in the manufacturing process of the laminate film of Comparative Example 1 is ion bombardment treatment (Ar-BB treatment) using capacitively coupled plasma with argon-containing gas. Compared to oxygen-LAICP treatment, Ar-BB treatment is less effective at activating the substrate film surface. This is reflected in the fact that the surface free energy of the plasma-treated surface of the substrate film in Comparative Example 1 is lower than that of the plasma-treated surface of the substrate film in Example 1. Additionally, the inventors have found that Ar-BB treatment is less effective at roughening the substrate film surface compared to oxygen-LAICP treatment. In the laminate film of Comparative Example 1, the ratio of the second interface length L2 to the first interface length L1 (L2/L1) was significantly lower than 1.10. Therefore, in the laminated film of Comparative Example 1, the adhesion of the inorganic layer could not be ensured.

In the laminate film of Comparative Example 2, the HC layer of the base film does not contain particles, so the surface of the base film (the surface on the adhesive layer side) does not have irregularities caused by particles. Furthermore, as described above, the plasma treatment in the manufacturing process of the laminate film of Comparative Example 2 is an inductively coupled plasma treatment using an oxygen-containing gas (oxygen-LAICP treatment) generated by applying high-frequency power to a low-inductance antenna, but the applied high-frequency power is insufficient. In such a laminate film of Comparative Example 2, the ratio of the second interface length L2 to the first interface length L1 (L2/L1) was significantly less than 1.10. Therefore, the laminate film of Comparative Example 2 was unable to ensure adhesion of the inorganic layer.

In the laminate film of Example 1, the HC layer of the substrate film does not contain particles. Therefore, as shown in Figure 7, the surface of the substrate film 10 (the surface on the adhesive layer 21 side) does not have irregularities due to particles. However, as described above, the plasma treatment in the manufacturing process of the laminate film of Example 1 is an inductively coupled plasma treatment using an oxygen-containing gas (oxygen-LAICP treatment) generated by applying high-frequency power to a low-inductance antenna, and the applied high-frequency power is sufficiently high. This oxygen-LAICP treatment roughens and activates the substrate film surface with nanometer-order fine irregularities, compared to Ar-BB treatment and oxygen-LAICP treatment with insufficient applied power. This is evident in the surface of the inorganic layer 22 side of the adhesive layer 21 formed on the substrate film 10, as shown in Figure 7. The surface of the adhesive layer is formed with irregularities that originate from the fine irregularities on the highly activated surface of the substrate film 10 and grow from these fine irregularities during the deposition process of the adhesive layer. Specifically, in the laminate film of Example 1, the ratio of the second interface length L2 to the first interface length L1 (L2/L1) was 1.10 or greater. Therefore, the laminate film of Example 1 was able to ensure adhesion of the inorganic layer.

In the laminate film of Example 2, the HC layer of the substrate film does not contain particles. Therefore, like the laminate film of Example 1, the surface of the substrate film 10 (the surface on the adhesive layer 21 side) does not have irregularities caused by particles. However, like the plasma treatment in Example 1, the plasma treatment in the manufacturing process of the laminate film of Example 2 is an inductively coupled plasma treatment using an oxygen-containing gas (oxygen-LAICP treatment) generated by applying high-frequency power to a low-inductance antenna, and the applied high-frequency power is sufficiently high. This oxygen-LAICP treatment roughens the substrate film surface with nanometer-order fine irregularities and activates the substrate film surface, compared to Ar-BB treatment and oxygen-LAICP treatment with insufficient applied power. The surface of the adhesive layer is formed with irregularities that originate from the fine irregularities on the highly activated surface of the substrate film 10 and grow from these fine irregularities during the deposition process of the adhesive layer. Specifically, in the laminate film of Example 2, the ratio of the second interface length L2 to the first interface length L1 (L2/L1) was 1.10 or greater. Therefore, the laminate film of Example 2 was able to ensure adhesion of the inorganic layer.

X: Laminated film H; Thickness direction D: Plane direction 10: Base film 10a; First surface 10b; Second surface 11: Resin film 12; Cured resin layer 21; Adhesion layer 22; Inorganic layers 22a, 22c; High refractive index layers 22b, 22d; Low refractive index layer

Claims (5)

A laminated film comprising: a substrate film including a resin film and a cured resin layer on the resin film; an adhesive layer on the cured resin layer of the substrate film; and an inorganic layer on the adhesive layer,
the content of inorganic oxide particles in the cured resin layer is 20% by mass or less,
A laminated film, wherein, in a cross-sectional view in the thickness direction, a ratio of a second interface length at the interface between the adhesive layer and the inorganic layer to a first interface length at the interface between the base film and the adhesive layer is 1.10 or more and 2.00 or less . The laminated film according to claim 1, wherein the adhesive layer has a thickness of 1 nm or more and 50 nm or less. The laminated film according to claim 1, wherein the adhesion layer is an inorganic oxide film containing at least one element selected from the group consisting of Si, In, Al, Sn, Ti, Zr, and Nb. The laminate film according to claim 1, wherein the inorganic layer includes a conductive layer. The laminate film according to claim 1 , wherein the inorganic layer includes an anti-reflection layer, and the anti-reflection layer includes a plurality of transparent inorganic oxide films laminated in a thickness direction.