Functional films, methods for manufacturing functional films, optical components, optical devices, inkjet heads, and molds

Abstract

The objective is to provide a functional film that can achieve both abrasion resistance and water repellency. [Solution] The functional film is a water-repellent film comprising at least a water-repellent layer and a textured layer. The water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. The textured layer contains inorganic material as its main component and has a fine textured structure.

Description

[Technical Field]

[0001] This invention relates to a functional film, a method for manufacturing a functional film, an optical component, an optical device, an inkjet head, and a mold. [Background technology]

[0002] To date, no water-repellent film with excellent abrasion resistance has existed. If the initial contact angle is around 110 degrees, the deterioration of the contact angle is less than 10 degrees even after abrasion. However, as disclosed in Patent Document 1, for example, water-repellent films with a contact angle exceeding 130 degrees typically show a deterioration of 10 degrees or more in the contact angle after abrasion testing.

[0003] The reasons for this are as follows: (i) Because the water-repellent film utilizes an uneven structure, the brittleness of this structure is the cause of contact angle degradation. (ii) In order to create a water-repellent film, it is necessary to meticulously control the pitch, depth, size, etc. of the uneven structure. The necessary conditions for improvement regarding (i) and (ii) are difficult to satisfy simultaneously, and a water-repellent film with high abrasion resistance has not been realized.

[0004] In particular, optical and mold applications required precisely processing microscopic irregularities into a shape that is unbreakable and water-repellent, making the process even more challenging. Furthermore, from the perspective of mass production and cost, lithography or nanoimprint, which require processing each sheet individually, were unsuitable. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5716679 [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention has been made in view of the above-mentioned problems and circumstances. The problem to be solved is to provide a functional film that can achieve both abrasion resistance and water repellency, and a method for manufacturing the functional film. Furthermore, it is also to provide optical components, optical devices, inkjet heads, and molds equipped with the functional film. [Means for solving the problem]

[0007] The inventors of the present invention investigated the causes of the above problems in order to solve them. As a result, they discovered the following and arrived at the present invention. The functional film comprises at least a water-repellent layer and an uneven layer. The water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. The uneven layer contains inorganic material as its main component and has a fine uneven structure. This makes it possible to achieve both abrasion resistance and water repellency in the functional film. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0008] 1. A water-repellent film comprising at least a water-repellent layer and an uneven layer, The water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. The aforementioned uneven layer is a functional film containing inorganic material as its main component and having a fine uneven structure.

[0009] 2. In the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are in a step-like shape with one or more steps. The functional film according to paragraph 1, wherein the uppermost convex portion in the uneven layer is rounded at its tip.

[0010] 3. In the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are in a multi-step staircase shape. The functional film according to the first or second paragraph, wherein, when the uneven layer is viewed from above, the uppermost part of the protrusions in the uneven layer has an island-like structure, and the lowermost part has a mesh-like structure.

[0011] 4. The uneven layer is a functional film according to paragraph 1 or 2, which contains SiO2 as its main component.

[0012] 5. The first water-repellent material includes a fluorine-based material and the second water-repellent material includes a silicon-based material, the functional film according to claim 1 or 2.

[0013] 6. The functional film according to claim 5, wherein the elemental ratio of fluorine to silicon on the surface of the water-repellent layer is within the range of 99:1 to 50:50.

[0014] 7. A high-hardness layer is provided between the water-repellent layer and the concavo-convex layer, and the hardness of the high-hardness layer is higher than that of the concavo-convex layer, the functional film according to claim 1 or 2.

[0015] 8. The functional film according to claim 7, wherein the high-hardness layer contains an inorganic substance having a Mohs hardness of 9 or higher or a hardness higher than that of SiO2.

[0016] 9. A sliding layer is provided between the water-repellent layer and the concavo-convex layer, the functional film according to claim 1 or 2.

[0017] 10. The functional film according to claim 1 or 2, wherein the contact angle of water at 23 °C is 130 degrees or more.

[0018] 11. A method for manufacturing a functional film, which is a method for manufacturing the functional film according to claim 1 or 2, comprising a step of forming the concavo-convex layer, and a step of forming the water-repellent layer, wherein the step of forming the water-repellent layer <so comprises a step of applying the first water-repellent material onto the concavo-convex layer, and a step of applying the second water-repellent material onto the concavo-convex layer before the layer of the first water-repellent material is formed, the method for manufacturing a functional film.

[0019] 12. The step of forming the concavo-convex layer comprises a step of rounding the corners at a plurality of convex portions included in the fine concavo-convex structure, the method for manufacturing a functional film according to claim 11.

[0020] 13. An optical component comprising the functional film described in paragraph 1 or 2.

[0021] 14. An optical device comprising the optical components described in paragraph 13.

[0022] 15. An inkjet head comprising the functional film described in paragraph 1 or 2.

[0023] 16. A mold comprising the functional film described in paragraph 1 or 2. [Effects of the Invention]

[0024] The above-described means of the present invention make it possible to achieve both abrasion resistance and water repellency in a functional film. Furthermore, optical components, optical devices, inkjet heads, and molds equipped with the functional film can also achieve both abrasion resistance and water repellency.

[0025] Although the mechanism of action or mechanism of the present invention is not yet clear, it is speculated as follows.

[0026] In thin films primarily composed of inorganic materials, water repellency can be achieved by forming a water-repellent layer containing a water-repellent material on its surface. Furthermore, a high level of water repellency can be achieved by creating a fine, uneven surface structure. On the other hand, with a fine, uneven surface structure, the surface is prone to abrasion when rubbed, and the water-repellent layer is easily peeled off. This is because sharp corners in the microstructure are preferentially rubbed, causing the water-repellent material to peel off easily.

[0027] In this embodiment, the water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. In other words, water adhering to the surface of the functional film is affected by two or more types of water-repellent materials. The water repellency of the first water-repellent material, a fluorine-based material, is highly dependent on molecular orientation, while the water repellency of the second water-repellent material, a silicon-based material, is less dependent on molecular orientation. When the surface of the water-repellent layer is rubbed, the degree of molecular orientation tends to decrease. Therefore, by including a silicon-based material with low dependence on molecular orientation in addition to the fluorine-based material, it is possible to prevent the water repellency from decreasing too much even when the surface of the water-repellent layer is rubbed. Furthermore, it is presumed that eliminating sharp angles in the microstructure and providing rounded shapes or tapered angles will result in a structure that is highly resistant to abrasion. [Brief explanation of the drawing]

[0028] [Figure 1] This is a schematic cross-sectional diagram showing an example of the basic structure of a functional film. [Figure 2] This is a schematic cross-sectional diagram showing an example of the basic structure of an uneven layer. [Figure 3] This is a schematic cross-sectional diagram showing an example of the basic structure of an uneven layer. [Figure 4] This is a top view showing an example of the basic structure of the uneven layer. [Figure 5] This is a perspective view showing an example of the basic structure of an uneven layer. [Figure 6] This diagram illustrates a method for calculating the average diameter at the top of the scale, and shows an example of the operation involved in analyzing images captured by an electron microscope. [Figure 7] This diagram illustrates a method for calculating the average diameter at the top of the scale, and shows an example of the operation involved in analyzing images captured by an electron microscope. [Figure 8] This diagram illustrates a method for calculating the average diameter at the top of the scale, and shows an example of the operation involved in analyzing images captured by an electron microscope. [Figure 9] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation involved in image analysis using an electron microscope. [Figure 10]This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation involved in image analysis using an electron microscope. [Figure 11] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation involved in image analysis using an electron microscope. [Figure 12] This diagram illustrates a method for calculating the surface area ratio in the uppermost layer, and shows an example of an image taken with an atomic force microscope. [Figure 13] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of binarized data obtained using an atomic force microscope. [Figure 14] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 15] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 16] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 17] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 18] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 19] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 20] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 21]This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 22] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 23] This diagram illustrates a method for calculating the surface area ratio in the uppermost section, and shows an example of the operation for analyzing images captured by an atomic force microscope. [Figure 24] This is a flowchart showing the manufacturing method for functional membranes. [Figure 25] This is a flowchart of the process for forming the uneven layer. [Figure 26] This is a process diagram showing an example of the process for forming an uneven layer. [Figure 27] This is a flowchart of the water-repellent layer formation process. [Figure 28] This is a photograph of a functional membrane viewed from directly above. [Figure 29] This is a photograph of a functional membrane viewed from a 30-degree angle above. [Figure 30] This is a photograph of a functional membrane viewed from a 45-degree angle above. [Figure 31] This is a photograph of a functional membrane viewed from a 30-degree angle above. [Figure 32] This is a photograph of a functional membrane viewed from directly above. [Figure 33] This is a photograph of a functional membrane viewed from a 30-degree angle above. [Figure 34] This is a schematic diagram of a functional film to explain the radius of curvature R and the taper angle θT. [Modes for carrying out the invention]

[0029] The functional film of the present invention is a water-repellent film comprising at least a water-repellent layer and a textured layer. The water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. The textured layer contains inorganic material as its main component and has a fine textured structure. The present invention is characterized by the above. This feature is a technical feature common to or corresponding to the following embodiments.

[0030] In this embodiment, in the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are preferably in a stepped shape with one or more steps, and the uppermost step of the protrusions in the uneven layer is preferably rounded or tapered at its tip. This makes it possible to achieve both sufficient abrasion resistance and water repellency of the functional film.

[0031] In this embodiment, in the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are preferably arranged in a multi-step staircase shape, and when the uneven layer is viewed from above, the uppermost protrusions have an island-like structure and the lowermost protrusions have a mesh-like structure. This allows for a sufficient balance between abrasion resistance and water repellency of the functional film.

[0032] In this embodiment, it is preferable that the uneven layer contains SiO2 as its main component. This allows the functional film to be applied to optical components.

[0033] In this embodiment, it is preferable that the first water-repellent material includes a fluorine-based material, and the second water-repellent material includes a silicon-based material. This allows for a sufficient balance between abrasion resistance and water repellency of the functional film.

[0034] In this embodiment, the elemental ratio of fluorine to silicon on the surface of the water-repellent layer is preferably within the range of 99:1 to 50:50. This allows for a sufficient balance between abrasion resistance and water repellency of the functional film.

[0035] In this embodiment, a high-hardness layer is provided between the water-repellent layer and the uneven layer, and it is preferable that the hardness of the high-hardness layer is higher than the hardness of the uneven layer. This improves the abrasion resistance of the functional film.

[0036] In this embodiment, it is preferable that the high-hardness layer contains an inorganic substance with a Mohs hardness of 9 or higher, or a hardness higher than SiO2. This improves the abrasion resistance of the functional film.

[0037] In this embodiment, it is preferable to provide a slip-resistant layer between the water-repellent layer and the uneven layer. This prevents clouding of the functional film. Furthermore, it is possible to achieve both sufficient abrasion resistance and water repellency of the functional film.

[0038] In this embodiment, the water contact angle at 23°C is preferably 130 degrees or more. This improves the water repellency of the functional film.

[0039] The present invention relates to a method for manufacturing a functional film, comprising the steps of forming the uneven layer and forming the water-repellent layer. The step of forming the water-repellent layer comprises the steps of applying the first water-repellent material onto the uneven layer and applying the second water-repellent material onto the uneven layer before the layer of the first water-repellent material is formed.

[0040] In this embodiment, the step of forming the uneven layer preferably includes a step of rounding the corners of the multiple protrusions included in the fine uneven structure. This makes it possible to achieve both sufficient abrasion resistance and water repellency of the functional film.

[0041] The optical component of the present invention comprises the functional film.

[0042] The optical device of the present invention comprises the aforementioned optical component.

[0043] The inkjet head of the present invention comprises the functional film.

[0044] The mold of the present invention comprises the functional film.

[0045] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments. In this application, "~" is used to mean that the numerical values ​​described before and after it are included as the lower limit and upper limit.

[0046] 1. Overview of Functional Membranes The functional film of this embodiment is a water-repellent film comprising at least a water-repellent layer and a textured layer, wherein the water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface, and the textured layer contains inorganic material as its main component and has a fine textured structure.

[0047] Figure 1 is a schematic cross-sectional diagram showing an example of the basic structure of a functional film. More specifically, it is a schematic cross-sectional diagram of the functional film 100 in the thickness direction. The functional film 100 comprises a textured layer 31 and a surface adjustment layer 35. The surface adjustment layer 35 is a general term for layers coated with various materials to adjust the surface function of the textured layer 31, and includes a water-repellent layer 34. In addition to the water-repellent layer 34, the surface adjustment layer 35 may also include any functional layers such as a high-hardness layer 32 and a slip-resistant layer 33. When the surface adjustment layer 35 includes a high-hardness layer 32, a slip-resistant layer 33 and a water-repellent layer 34, it is preferable to have each layer in the order of textured layer 31, high-hardness layer 32, slip-resistant layer 33, and water-repellent layer 34. Furthermore, any functional layer such as a reflectivity adjustment layer (not shown) may be provided below the textured layer 31, i.e., on the flat surface side that does not form a fine textured structure.

[0048] The functional film of this embodiment achieves both abrasion resistance and water repellency by comprising a water-repellent layer 34 and an uneven layer 31. Furthermore, its effects can be enhanced by further comprising a high-hardness layer 32, a slip-resistant layer 33, etc.

[0049] In this embodiment, "protrusion" refers to the portion that protrudes upward from the reference surface, and "recess" refers to the portion excluding the protrusion. In the following description of the functional film as a whole, "protrusion" refers to the entire portion from the bottom surface 31b of the uneven layer 31 to the water-repellent layer 34 that protrudes upward. In the description of the uneven layer, "protrusion" refers to the portion from the bottom surface 31b of the uneven layer 31 to the top surface 31a of the uneven layer 31 that protrudes upward. In this embodiment, the side on which the water-repellent function is exhibited (surface side) is called the top surface, and the opposite side is called the bottom surface.

[0050] The surface adjustment layer 35 may cover the entire surface of the functional film 100, as shown by the first protrusion 41 and the first recess 44. Alternatively, the surface adjustment layer 35 may cover only the area near the surface of the functional film 100, as shown by the second protrusion 42, the third protrusion 43 and the second recess 45, and the uneven layer 31 may be exposed in the portion of the functional film 100 that is far from the surface.

[0051] The following describes the details of each layer that can be incorporated into the functional film.

[0052] 2. Uneven layer The fine uneven structure in functional films is mainly formed by the uneven layer. The details of the uneven layer are described below. In Figure 1, the surface adjustment layer 35 has a certain thickness (height), but in reality it is extremely thin compared to the thickness (height) of the protrusions in the uneven layer 31. Therefore, the fine uneven structure in the uneven layer 31 is not eliminated by the application of the surface adjustment layer 35 but is maintained.

[0053] In this embodiment, "micro-uneven structure" refers to a structure having multiple fine uneven shapes that are sufficient to exhibit a water-repellent effect. Specifically, it refers to an uneven structure in which, when the lowest surface of the recess in the uneven layer is used as the reference, the average height of the protrusions in the uneven layer is 1 μm or less, or in other words, the average depth of the recess in the uneven layer is 1 μm or less. Hereinafter, in the description of the uneven layer, "protrusions in the uneven layer" will also be simply referred to as "protrusions".

[0054] Figures 2 and 3 are schematic cross-sectional diagrams showing an example of the basic structure of the uneven layer. Specifically, Figures 2 and 3 are schematic cross-sectional diagrams perpendicular to the thickness direction, showing only the uneven layer 31 of the functional film 100. The uneven layer 31 has a fine uneven structure on one surface. In the perpendicular cross-sectional shape in the thickness direction, the protrusions of the fine uneven structure are in a step-like manner, one or more steps.

[0055] Figure 4 is a top view showing an example of the basic structure of the uneven layer, specifically a top view of only the uneven layer 31 of the functional film 100. Figure 4 is a top view of the uneven layer 31 shown in Figure 3, and Figure 3 corresponds to the vertical cross-sectional view along line L in Figure 4.

[0056] The following describes the characteristics of the uneven layer when viewed from a cross-section perpendicular to the film thickness direction, and when viewed from above (top view).

[0057] (1) Structure of the uneven layer (1.1) Overall shape of the convex portion when viewed from a vertical cross-section (1.1.1) Stair shape In this embodiment, "one or more steps" refers to a step where the distance of the substantially horizontal portion is 10 nm or more. For example, in the case of one step, the average diameter L in Figure 2 corresponds to the distance of the substantially horizontal portion, and in the case of multiple steps, L3 in Figure 3 corresponds to the distance of the substantially horizontal portion. The distance of the substantially horizontal portion is preferably 30 nm or more, and more preferably in the range of 50 to 500 nm.

[0058] In this embodiment, when the number of steps in the convex staircase is n, the steps are numbered sequentially from the top, being the 1st step, the 2nd step, and so on, with the bottom step being the nth step. For example, in Figure 3, the convex staircase has 2 steps, comprising the 1st step 21 (top step) and the 2nd step 22 (bottom step).

[0059] The determination of whether or not "the multiple protrusions included in the micro-rough structure are in a one- or multiple-step staircase shape in the vertical cross-sectional shape in the thickness direction" and the confirmation of the shape are performed by the following methods. This can be determined and confirmed by observing the cross-sectional shape of a three-dimensional image obtained by measurement with an atomic force microscope (AFM) under the conditions described later, or by observing the cross-section of the functional film with an electron microscope. These methods may also be used in combination. In addition, the cross-section of the protrusions may be observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0060] The angle between the step height and the slope direction in the nearly horizontal portion of the staircase, i.e., angle θ1 in Figure 2 for a single step and angle θ2 in Figure 3 for multiple steps, is within the range of 90 to 150 degrees, and preferably within the range of 100 to 140 degrees. In this embodiment, each step of the staircase is preferably tapered, and the taper angle θ at each step is also tapered. T The taper angle θ is preferably within the range of 30 to 80 degrees. T This represents the angle of the step height in the direction of the slope.

[0061] (1.1.2) Total average height of the convex portion As will be explained in more detail later, it is preferable to form the fine uneven structure of the uneven layer by etching after forming an inorganic layer of uniform thickness. In this embodiment, the layer before and during the formation of the fine uneven structure is referred to as the "inorganic layer," and the layer after its formation is referred to as the "uneven layer." When forming the fine uneven structure by etching, the "average height of the protrusions relative to the bottom surface of the recesses" corresponds to the total etching depth when forming the recesses by etching. The "average height of the protrusions relative to the bottom surface of the recesses" is also called the "total average height H."

[0062] For example, if the staircase has one step, as shown in Figure 2, the distance from the bottom surface 21b of the first step to the top surface 21a of the first step is called the total average height H. If the staircase has two steps, as shown in Figure 3, the distance from the bottom surface 22b of the second step to the top surface 21a of the first step is called the total average height H.

[0063] The overall average height H is 1 μm or less, and preferably within the range of 0.05 to 0.25 μm.

[0064] The overall average height H is calculated by measuring image data of the uneven layer using an atomic force microscope (AFM) and then using software from BRUKER. Specifically, any vertical cross-section of 1 μm or more in the film thickness direction is analyzed, and the distance between the surface with the highest number (frequency) of data points on the uppermost surface and the surface with the highest number of data points is calculated. This distance is analyzed for 10 arbitrary cross-sections, and the arithmetic mean is taken as the overall average height H.

[0065] As will be explained in more detail later, by controlling the thickness of the inorganic layer, the thickness of the metal mask, the deposition temperature of the metal mask, the etching time, etc., the total average height H can be reduced to 1 μm or less.

[0066] (1.2) Shape of the uppermost section when viewed from a vertical cross-section (1.2.1) Shape of the tip In this embodiment, the uppermost stage is rounded at the tip. As shown in Figures 2 and 3, the "tip" refers to the upper end of the uppermost stage, and the tip 50 includes the upper surface 21a of the first stage. As will be described in detail later, the sharp corners on the upper surface of the uppermost stage (first stage) are removed by isotropic etching during the manufacturing process. Therefore, the uppermost stage has rounded corners and a rounded shape. In addition, the sides of the uppermost stage (first stage) are easily removed by etching, and the closer to the top surface, the more easily they are removed. Therefore, the uppermost stage may have a tapered shape.

[0067] The rounded shape with fewer sharp corners at the tip is thought to prevent the protrusions from catching on the functional film when rubbed, thus suppressing breakage and chipping. Furthermore, the tapered shape allows the part furthest from the top tip to be relatively thicker, which is thought to suppress breakage and chipping of the protrusions when the functional film is rubbed. Here, "sharp corner" refers to a corner that is not chamfered at approximately 90 degrees. Also, the sharp corner is a corner formed by anisotropic etching in the manufacturing process described later. The radius of curvature R at the rounded tip is preferably in the range of 30 to 1000 nm. More preferably, it is in the range of 50 to 300 nm. The radius of curvature R can be calculated by observing the cross-section of the protrusion with an atomic force microscope (AFM) or a scanning electron microscope (SEM).

[0068] (1.2.2) Average height of the top row In this embodiment, "average height of the top step" refers to the average height from the bottom surface to the top surface of the top step. When the convex staircase has one step, the average height h is the distance from the bottom surface 21b of the first step to the top surface 21a of the first step, as shown in Figure 2. Note that when the convex staircase has one step, the average height h and the overall average height H are the same. When the convex staircase has two steps, the average height h is the distance from the bottom surface 21b of the first step to the top surface 21a of the first step, as shown in Figure 3.

[0069] If the staircase of the protrusion has one step, the average height h of the top step is preferably in the range of 10 to 250 nm, and more preferably in the range of 30 to 200 nm. If the staircase of the protrusion has two steps, the average height h2 of the top step is preferably in the range of 10 to 150 nm, and more preferably in the range of 30 to 100 nm. If the staircase of the protrusion has three steps, the average height of the top step is preferably in the range of 10 to 100 nm, and more preferably in the range of 20 to 50 nm.

[0070] The average height h of the uppermost section can be calculated by observing the cross-section of the convex portion with an atomic force microscope (AFM) or a scanning electron microscope (SEM).

[0071] The average height h of the top step is calculated by measuring image data of the uneven layer using an atomic force microscope (AFM) and then using software from BRUKER. Specifically, it is determined by the difference between the peak in the number of data points at the top surface (top surface of the first step) and the peak in the number of data points below it. That is, if there is one step, the bottom surface is the peak in the number of data points below it, and if there are two steps, the bottom surface of the first step (top surface of the second step) is the peak in the number of data points below it. In this case as well, the difference is calculated for 10 arbitrary cross-sections, and the arithmetic mean is taken as the average height h.

[0072] As will be explained in more detail later, the average height h can be adjusted to within the above range by controlling the thickness of the inorganic layer, the thickness of the metal mask, the deposition temperature of the metal mask, the etching time, etc.

[0073] (1.3) Shape of the protrusion when viewed from above (1.3.1) Island-like structures and network-like structures When the uneven layer is viewed from above, the uppermost part of the protrusions is preferably an island-like structure, and the lowermost part is preferably a mesh-like structure.

[0074] Figure 5 is a perspective view showing an example of the basic structure of the uneven layer, specifically a perspective view of only the uneven layer 31 of the functional film 100. Note that Figure 5 shows a case where the raised section has two steps, with the second step 22 being the bottom step.

[0075] In this embodiment, "island-like structure" refers to a structure in which, when the first stage 21 is viewed from above, multiple relatively circular island-like areas can be observed. In contrast, "network-like structure" refers to a structure in which, when the second stage 22 is viewed from above, a network-like area can be observed in which multiple island-like areas, similar to those seen in the first stage 21, are connected in a continuous manner. Furthermore, if the major axis of the network-like area can be defined as described later, the ratio of the major axis diameter to the minor axis diameter is 5 or more. In addition, the network-like area also includes network shapes in which the major axis cannot be defined as described later. Specifically, the network-like area also includes shapes in which multiple irregularly shaped ellipses are connected or branched. In other words, "the uppermost stage has an island-like structure, and the lowermost stage has a network-like structure" means that the island-like areas of the uppermost stage are connected by the network-like area of ​​the lowermost stage.

[0076] By reducing the average diameter of the uppermost layer, water repellency can be improved. On the other hand, if the average diameter of the uppermost layer is reduced, the protrusions of the functional film are more likely to break and chip when rubbed. Therefore, by making the bottom layer a mesh structure, even if the average diameter of the uppermost layer is reduced, the stress applied to the uppermost layer when the functional film is rubbed can be distributed to the mesh part of the bottom layer, and it is thought that the breaking and chipping of the protrusions can be suppressed.

[0077] (1.3.2) Ratio of major axis diameter to minor axis diameter From the viewpoint of abrasion resistance, when the uneven layer is viewed from above, the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) at each step of the protrusions is preferably 2 or more, and more preferably 5 or more. Furthermore, each step of the protrusions is preferably shaped like a bent, elongated ellipse. For example, each step of the protrusions is preferably L-shaped or S-shaped rather than perfectly circular. By adopting such shapes, it is possible to suppress the breaking and chipping of the protrusions even when the functional film is rubbed.

[0078] The major axis diameter and minor axis diameter are determined by observation using a scanning electron microscope (SEM), as described later. In this embodiment, "major axis diameter at each step of the convex portion" refers to the diameter when the smallest circumscribed circle C1 is drawn on the outer shape (edge) of each step of the convex portion when viewed from above. "Minor axis diameter at each step of the convex portion" refers to the diameter when the largest inscribed circle C2 is drawn on the outer shape (edge) of each step of the convex portion when viewed from above.

[0079] A step in a staircase with a ratio of 2 or more between its major axis diameter and minor axis diameter may be the first step or a subsequent step. Having this ratio of 2 or more in any step of the staircase can improve abrasion resistance. From the viewpoint of abrasion resistance, it is preferable that this ratio be 2 or more in the lowest step of the convex section.

[0080] (1.4) The shape of the top row when viewed from above (1.4.1) Average diameter of the top row The average diameter of the uppermost layer is preferably in the range of 10 to 500 nm, and more preferably in the range of 50 to 200 nm.

[0081] The average diameter of the uppermost layer is determined by photographing the uneven layer with an electron microscope and observing the resulting photograph. In this embodiment, "average diameter of the uppermost layer" refers to the average diameter of the outer shape (edge) when the uppermost layer is viewed from above. For example, if the convex staircase has one step as shown in Figure 2, the average diameter of the uppermost layer refers to the average diameter L of the first step 21 (uppermost layer). Also, if the convex staircase has two steps as shown in Figure 3, the average diameter of the uppermost layer refers to the average diameter L of the first step 21 (uppermost layer). In reality, the uppermost layer is often irregularly shaped, so it is preferable to use the arithmetic mean of the major axis diameter and minor axis diameter of the uppermost layer as its diameter.

[0082] When the raised section has two or more steps, it is preferable that the average diameter L of the top step (the first step) is smaller than the average diameter of the subsequent steps. In other words, it is preferable that the raised section tapers towards the top. This allows for a good balance between abrasion resistance and water repellency.

[0083] For example, as shown in Figure 3, if the convex staircase has two steps, the average diameter L of the first step is preferably in the range of 10 to 500 nm, and the average diameter of the second step is preferably in the range of 100 to 1000 nm. If the convex staircase has three steps, the average diameter L of the first step is preferably in the range of 10 to 500 nm, the average diameter of the second step is preferably in the range of 100 to 600 nm, and the average diameter of the third step is preferably in the range of 100 to 1000 nm.

[0084] As will be explained in more detail later, the average diameter L can be adjusted to within the above range by controlling the thickness of the inorganic layer, the thickness of the metal mask, the deposition temperature of the metal mask, the etching time, etc.

[0085] <Measurement method> The average diameter of the top layer can be calculated using the following procedure. First, take a top-view photograph of the uneven layer using a scanning electron microscope (SEM) or transmission electron microscope (TEM). Then, use the image processing software "ImageJ (ImageJ1.32S created by WayneRasband)" to calculate the average diameter of the top layer.

[0086] The following describes the procedure for image analysis using a scanning electron microscope (SEM).

[0087] 1) Download the free software ImageJ. 2) Perform image processing using the following procedure with the default settings. 3) The surface SEM image of the uneven layer, which was previously taken using a scanning electron microscope at a magnification of 30,000x or more, is imported into a PC using the free software ImageJ.

[0088] 4) Correlate the number of pixels with the physical length. For example, in the case of Figure 6, 1 μm = 504 pixels.

[0089] 5) Measure the diameter of the major axis. As shown in Figure 7, the minimum circumscribed circle C1 is drawn using the circle shape tool for the given uppermost row R. In this case, w=h=353 represents the number of pixels that indicate the diameter (major axis diameter) of the minimum circumscribed circle C1. In this case, the physical length is 353 / 504 = 0.700 μm.

[0090] 6) Measure the diameter of the minor axis. As shown in Figure 8, for the given uppermost row R, the maximum inscribed circle C2 is drawn using the circle shape tool. In this case, w=h=127 above represents the number of pixels indicating the diameter (minor axis diameter) of the maximum inscribed circle C2. In this case, the physical length is 127 / 504 = 0.251 μm.

[0091] 7) Calculate the average diameter. The arithmetic mean of the measured major axis diameter and minor axis diameter is calculated. Specifically, (0.700 + 0.251) / 2 = 0.475 μm is the diameter of the predetermined uppermost R shown in Figures 7 and 8. The diameter is calculated for any 10 uppermost elements using the same method, and the arithmetic mean of the 10 diameters is taken as the average diameter.

[0092] (1.4.2) Surface area of ​​the top row The ratio of the surface area of ​​the uppermost layer to the total surface area of ​​the uneven layer is preferably in the range of 30-70%, and more preferably in the range of 30-55%.

[0093] In this embodiment, "the ratio of the surface area of ​​the uppermost layer to the total surface area of ​​the uneven layer when the uneven layer is viewed from above" refers to the ratio of the surface area of ​​the uppermost layer to the total surface area of ​​the uneven layer, i.e., the sum of the surface areas of the convex and concave parts, when the uneven layer is viewed from above.

[0094] As will be explained in more detail later, the surface area ratio of the uppermost layer can be adjusted within the above range by controlling the thickness of the inorganic layer, the thickness of the metal mask, the deposition temperature of the metal mask, the etching time, etc.

[0095] <Measurement method> The surface area ratio of the uppermost layer can be calculated using either a scanning electron microscope (SEM) or an autofocus (AFM) image analysis method. It is preferable that the value calculated by either of these image analysis methods falls within the specified range.

[0096] In the image analysis method using SEM, first, a top-down (top-view) photograph of the uneven layer is taken using a scanning electron microscope (SEM). The captured photographic image is then analyzed using the free image processing software "ImageJ (ImageJ1.32S created by WayneRasband)" to calculate the structure.

[0097] In image analysis methods using AFM, first, image data of the surface irregularities is measured using an atomic force microscope (AFM). The obtained AFM measurement images are then binarized using software from BRUKER and calculated.

[0098] (Image analysis using SEM) The following describes the procedure for image analysis using a scanning electron microscope (SEM). 1) The surface SEM image of the uneven layer, which was previously taken using a scanning electron microscope at a magnification of 30,000x or more, is imported into a PC using the free software ImageJ. Since the SEM image changes with adjustments to focus, contrast, and brightness, it is preferable to set the focus, contrast, and brightness to predetermined values.

[0099] 2) Define black and white. In the free software ImageJ, checking the "Black Background" option displays a brightness value of 0 as black and a brightness value of 255 as white. If the "Black Background" option is not checked, a brightness value of 0 is displayed as white and a brightness value of 255 as black. It is preferable to check the option and analyze the image with a brightness value of 255 as white.

[0100] 3) Image noise reduction The image will be smoothed.

[0101] 4) Apply a bandpass filter. The bandpass filter value is preferably within the range of 20 to 100. Since the optimal value depends on the initial SEM image, it is preferable to set it appropriately to achieve the optimal value.

[0102] 5) Perform image binarization. Convert to 8-bit in the settings and set the threshold. Set the threshold so that the "above" bar, i.e., the area selected in green, reaches 0% in the settings below. Adjust the threshold until the "below" bar, i.e., the area selected in blue, overlaps with the black area of ​​the pores. Since this threshold changes with the image contrast, it is preferable for the analyst to set the threshold each time rather than fixing it. Once the threshold is set, convert to a black and white image.

[0103] Figure 9 shows an example of a binarized image. In the example shown in Figure 9, the convex staircase has two steps. The white area in Figure 9 is the top step of the convex staircase. The black area in Figure 9 is the uneven layer excluding the top step (first step), i.e., the steps from the second step onward and the recessed areas of the convex staircase.

[0104] 6) Use ImageJ to retrieve the histogram. As shown in Figure 10, pressing the List button to display the histogram data as a List shows the number of pixels for each grayscale level. In the example shown in Figure 10, it is shown that there are 352,791 pixels with Value=0, i.e., black pixels. In the example shown in Figure 11, it is shown that there are 876,009 pixels with Value=255, i.e., white pixels.

[0105] 7) Determine the area ratio. The surface area of ​​the top layer corresponds to the number of white pixels. The total surface area of ​​the uneven layer corresponds to the sum of the number of white pixels and the number of black pixels. The ratio of the surface area of ​​the top layer is expressed by the following formula (I). Equation (I): Ratio of the surface area of ​​the top row = Number of white pixels / (Number of white pixels + Number of black pixels) In the examples shown in Figures 10 and 11, {876009 / (352791+876009)}×100 = 71% represents the proportion of the surface area of ​​the top layer.

[0106] Furthermore, if the analyzed image contains information from the SEM image measurement process, it is preferable to perform image analysis after taking steps to exclude such information beforehand so as not to affect the analysis.

[0107] (Image analysis using AFM) The following describes the procedure for image analysis using an atomic force microscope (AFM). An AFM is a type of scanning probe microscope (SPM) that uses the interatomic force between the sample and the probe to measure nanoscale surface irregularities.

[0108] Specifically, AFM measures the surface topography by bringing a cantilever, which has a sharp probe attached to the tip of a tiny spring plate, within a few nanometers of the sample surface, and measuring the interatomic force acting between the atoms at the probe tip and the atoms in the sample. The AFM scans while feeding back to a piezo scanner to keep the interatomic force constant, i.e., the deflection of the cantilever constant. By measuring the displacement fed back to the piezo scanner, the displacement along the Z axis, i.e., the surface topography structure, is measured.

[0109] If the AFM needle does not fit into the narrow groove of the recess, data will be obtained as if there were only one step in the raised section, even if there are actually two steps. Therefore, it is preferable to choose an AFM needle that is as super sharp or a cantilever designed for high aspect ratios as possible.

[0110] For example, the AFM can be the "L-trace W" (manufactured by Hitachi High-Technologies Corporation), and the probe can be the silicon probe "SI-DF40P2" (manufactured by Hitachi High-Technologies Corporation).

[0111] A) Acquisition of surface texture images using AFM AFM is used to measure three-dimensional surface texture data of the uneven layer. Figure 12 shows an example of an AFM measurement image.

[0112] B) Binarization of AFM data The obtained AFM measurement images were binarized using software from BRUKER. Figure 13 shows the binarized data of the AFM measurement image shown in Figure 12.

[0113] Figure 14 is an AFM measurement image when the convex staircase has one step. Figure 15 is the cross-sectional profile at the cutting line P1 shown in the AFM measurement image in Figure 14. The horizontal axis indicates the scan location. The vertical axis indicates the distance from the deepest point of the AFM measurement image in Figure 14, with the deepest point of the AFM measurement image in Figure 14 set as the zero reference. Figure 16 is a graph plotting the AFM measurement image in Figure 14, with the vertical axis representing depth (distance from the deepest point) and the horizontal axis representing the number of data points at that depth.

[0114] If there is only one step in the staircase, as shown in Figure 16, peaks in the number of data points appear at the top and bottom surfaces of the protrusion. To find the surface area of ​​the top step, the midpoint between the peak in the number of data points at the top surface and the peak in the number of data points at the bottom surface is used as a threshold, and binarization (color editing) is performed.

[0115] In the example shown in Figure 16, the peak height of the data points from the bottom to the top surface of the convex portion is 120 nm, and this position is the top surface. Binarization (color editing) is performed using the midpoint (60 nm) between the peak of data points at the top surface (120 nm) and the peak of data points at the bottom surface (0 nm) as the threshold. Specifically, points higher than the midpoint height are displayed as white, and points lower than the midpoint height are displayed as black.

[0116] Figure 17 is an AFM measurement image when the convex staircase has two steps. Figure 18 is the cross-sectional profile at the cutting line P2 shown in the AFM measurement image in Figure 17. The horizontal axis indicates the scan location. The vertical axis indicates the distance from the deepest point of the AFM measurement image in Figure 17, with the deepest point of the AFM measurement image in Figure 17 set as the zero reference. Figure 19 is a graph plotting the AFM measurement image in Figure 17, with the vertical axis representing depth (distance from the deepest point) and the horizontal axis representing the number of data points at that depth.

[0117] If the staircase has two steps, as shown in Figure 19, peaks in the number of data points appear on the top surface of the first step and on the bottom surface of the first step (the top surface of the second step). To find the surface area of ​​the top step, the first step is binarized (color edited) using the midpoint between the peak in the number of data points on the top surface and the peak in the number of data points on the bottom surface as the threshold.

[0118] In the example shown in Figure 19, the peak heights of the data count from the bottom to the top surface of the convex portion are 225 nm and 140 nm, with the top surface of the first stage at a height of 225 nm and the bottom surface of the first stage at a height of 140 nm. In the first stage, binarization (color editing) is performed using the midpoint (182.5 nm) between the peak of the data count at the top surface (225 nm) and the peak of the data count at the bottom surface (140 nm) as the threshold. Specifically, points higher than the midpoint height are displayed as white, and points lower than the midpoint height are displayed as black.

[0119] Next, based on the binarized image, the surface area ratio of the top row is measured using the same method with the aforementioned free image analysis software, ImageJ. Although binarization has already been completed using the method described above, it is preferable to perform binarization using image processing software as well. As shown in Figures 20 and 21, the image is converted to 8-bit with the default settings, and binarized with a threshold of Threshhold=128.

[0120] Next, as shown in Figures 22 and 23, a histogram of the AFM binarized image is created. The number of black and white data points is counted, and the proportion of data points in the top row (white) is determined. In the example shown in Figures 22 and 23, the proportion of the surface area in the top row is 41%.

[0121] (1.5) Randomness of the convex part It is preferable that the relative positions and shapes of the multiple protrusions have a randomness that lacks regularity in terms of identity or periodicity. This can reduce the generation of diffracted light.

[0122] In this embodiment, "randomness" refers to a state in which there is no overall identity, periodicity, or other regularity in the relative positions and shapes of multiple protrusions, and randomness or unpredictability is recognized. Specifically, it refers to the state shown in the electron microscope images obtained in the embodiments described later. Furthermore, since diffracted light is less likely to be generated if there is randomness, randomness can be determined from the presence or absence of diffracted light.

[0123] (2) Material of the uneven layer In this embodiment, "containing inorganic substances as the main component" means that the proportion of inorganic substances in the total components constituting the functional film is 80% by mass or more. The proportion of inorganic substances is preferably in the range of 90 to 99.9% by mass, and more preferably in the range of 97 to 100% by mass.

[0124] The type of inorganic material is not particularly limited. Examples of main inorganic components include SiO2, SiC, SiOC, and SiCN. Functional films containing SiO2 have high transparency and are suitably used in optical devices, for example. Functional films containing SiC, SiOC, or SiCN have high hardness and are suitably used in inkjet heads or molds, for example.

[0125] From the viewpoint of hardness, the uneven layer preferably contains inorganic materials with a Mohs hardness of 9 or higher in addition to the main inorganic component, and more preferably contains inorganic materials with a Mohs hardness of 13 or higher. In this embodiment, the modified Mohs hardness scale, which has been modified to 15 levels, is used. The Mohs hardness of typical inorganic materials is shown below.

[0126] [Table 1]

[0127] Inorganic materials with a Mohs hardness of 9 or higher include Al2(F,OH)2(SiO4), (Mg,Ca,Fe)3(Al,Cr,Fe)2(SiO4)3, ZrO2, TaC, Al2O3, WC, SiC, B4C, C, SiOC, and SiCN. Among these, Al2O3, SiC, SiOC, or SiCN are preferred.

[0128] When the Mohs hardness of the inorganic material contained in the uneven layer is X, and the number of steps in the raised portion is an integer Y, it is preferable that the following equation (II) is satisfied, and more preferably that the following equation (III) is satisfied. Formula (II): 10≦X×Y Formula (III): 14≦X×Y≦39

[0129] In other words, if the staircase has one step, it is preferable to include an inorganic substance with a Mohs hardness of 10 or higher. If the staircase has two steps, it is preferable to include an inorganic substance with a Mohs hardness of 5 or higher. Furthermore, an inorganic substance satisfying formula (II) or formula (III) may be included in the uneven layer as a main component or as a minor component.

[0130] 3.High hardness layer In this embodiment, the functional film preferably includes a high-hardness layer. Specifically, it is preferable to form the textured layer with a material that is not too hard and easily forms a fine uneven structure, and to form the high-hardness layer with a material that is harder than the material of the textured layer. This allows for a sufficient balance of abrasion resistance and water repellency in the functional film.

[0131] The material of the high-hardness layer is not particularly limited as long as it is harder than the material of the uneven layer. The thickness of the high-hardness layer is not particularly limited, but it is preferably in the range of 0.1 to 20 nm.

[0132] 4.Sliding layer The functional film of this embodiment preferably includes a slip-resistant layer. This prevents the functional film from becoming cloudy. It also improves the adhesion between the water-repellent layer and the textured layer, or between the water-repellent layer and the high-hardness layer, allowing for a sufficient balance of abrasion resistance and water repellency in the functional film.

[0133] In this embodiment, the "slip layer" refers to a layer on a white glass substrate (manufactured by SCHOTT) with a thickness of 100 nm, where the contact angle after being left at room temperature for 3 days is in the range of 40 to 120 degrees. Furthermore, it is preferable that the difference between this contact angle and the contact angle of the uneven layer alone is 20 degrees or more. The material of the slip layer is not particularly limited as long as the above conditions are met.

[0134] Examples of materials used in landslide layers include Ta2O5-TiO2, Ta2O5, TiO2, SiC, Al2O3, and HfO2. A commercially available example of Ta2O5-TiO2 is "OA-600" (manufactured by Canon Optron Co., Ltd.).

[0135] The thickness of the landslide layer is not particularly limited, but it is preferably in the range of 0.1 to 20 nm.

[0136] 5. Water-repellent layer In this embodiment, "water-repellent" means that the contact angle of water at 23°C is 90 degrees or more.

[0137] The water-repellent layer according to this embodiment contains two or more water-repellent materials, namely at least a first water-repellent material and a second water-repellent material. The structure of the water-repellent layer is not particularly limited, but two or more water-repellent materials are exposed on the surface of the water-repellent layer. In other words, water adhering to the surface of the functional film is affected by the two or more water-repellent materials. Therefore, by containing a first water-repellent material with extremely high water repellency and a second water-repellent material that does not have as much water repellency as the first water-repellent material but has higher hardness than the first water-repellent material, the water-repellent layer can achieve both abrasion resistance and water repellency.

[0138] The water-repellent layer does not need to be formed on the entire surface of the functional film, but it is preferable to cover at least the uppermost surface 31a of the uneven layer 31. This ensures sufficient water repellency.

[0139] The water-repellent material is not particularly limited as long as it is a material that can impart water repellency to a functional film. Examples of water-repellent materials include fluorine (F)-based, silicon (Si)-based, and hydrocarbon-based materials. Commercially available water-repellent materials include "Fluorosurf®" (manufactured by Fluorotechnology Inc.), "Optoul®" (manufactured by Daikin Industries, Ltd.), and "SURFCLEAR® 100" (manufactured by Canon Optron Corporation).

[0140] In particular, the water-repellent layer preferably contains a fluorine-based material as the first water-repellent material and a silicon-based material as the second water-repellent material. This allows for a sufficient balance between abrasion resistance and water repellency. Furthermore, the water repellency of fluorine-based materials is highly dependent on molecular orientation, while the water repellency of silicon-based materials is less dependent on molecular orientation. When the surface of the water-repellent layer is rubbed, the degree of molecular orientation tends to decrease. Therefore, by including a silicon-based material, which is less dependent on molecular orientation, in addition to the fluorine-based material, it is possible to prevent the water repellency of the water-repellent layer from decreasing too much even when the surface is rubbed.

[0141] The elemental ratio of fluorine (F) to silicon (Si) on the surface of the water-repellent layer is not particularly limited, but it is preferably in the range of 99:1 to 50:50, and more preferably in the range of 99:1 to 70:30. This allows for a good balance between abrasion resistance and water repellency. The elemental ratio of fluorine (F) to silicon (Si) can be measured by X-ray photoelectron spectroscopy (XPS).

[0142] On the surface of the water-repellent layer, it is preferable that the silicon-based material and the fluorine-based material do not separate, and that the silicon-based material is dispersed to a certain extent uniformly. This allows for a sufficient balance between abrasion resistance and water repellency. For example, even in a narrow area of ​​the water-repellent layer covering a single protrusion, it is preferable that both the fluorine-based material and the silicon-based material are exposed.

[0143] 6. Physical properties of functional films (1) Contact angle From the viewpoint of water repellency, the functional film of this embodiment has a contact angle of 90 degrees or more. From the viewpoint of exhibiting even higher water repellency, a contact angle of 110 degrees or more is preferable, 130 degrees or more is more preferable, and 150 degrees or more is even preferable. When the contact angle is 150 degrees or more, it is also called superhydrophobic.

[0144] The contact angle can be measured by the following method: Using a contact angle measuring device, 10 μL of pure water is dropped onto the functional film in an environment of 23°C and 50% RH, and the static contact angle is measured 5 seconds after dropping. For example, a goniometer "G-1" (manufactured by Elma) can be used as the contact angle measuring device.

[0145] (2) Sliding angle The angle at which a liquid droplet begins to slide off a horizontal surface, when it is gradually tilted, is called the "slide angle." For the same amount of liquid droplet, a smaller slide angle indicates weaker adhesion between the surface and the liquid. In other words, in this embodiment, a smaller slide angle indicates higher water repellency. The slide angle is preferably 60 degrees or less, and more preferably 30 degrees or less. The slide angle can be measured using the same procedure as the contact angle.

[0146] (3)Reflectance When the functional film of this embodiment is used in an optical component, it is preferable that the reflectivity of the functional film is low in the wavelength range corresponding to the application of the optical component. For example, when used in an automotive camera lens as described later, the average reflectivity of the functional film in the wavelength range of 450 to 780 nm is preferably 5% or less, more preferably 3% or less, and preferably 1% or less. From this viewpoint, the refractive index of the functional film is preferably in the range of 1.2 to 1.8. Furthermore, the refractive index of the uneven layer alone is preferably in the range of 1.4 to 1.7.

[0147] 7. Method for manufacturing functional membranes The method for manufacturing a functional film according to this embodiment includes the steps of forming an uneven layer and forming a water-repellent layer. The step of forming the water-repellent layer includes the steps of applying the first water-repellent material onto the uneven layer and applying the second water-repellent material onto the uneven layer before the layer of the first water-repellent material is formed.

[0148] Figure 24 is a flowchart of the manufacturing method for the functional film in this embodiment. In this embodiment, a textured layer, a high-hardness layer, a slip-resistant layer, and a water-repellent layer are formed in order. The high-hardness layer and the slip-resistant layer are formed as needed.

[0149] It is preferable to manufacture the functional film on a substrate. It is preferable to use the functional film without peeling it off the substrate after it has been manufactured on the substrate. For example, when the functional film is used as a water-repellent film to be applied to a lens, it is preferable to apply the functional film directly onto the lens, using the lens as the substrate.

[0150] The material of the substrate is not particularly limited and may be an inorganic material, an organic material, or a combination thereof. Furthermore, the substrate may be an inorganic material such as glass on which a film of organic material is formed.

[0151] Examples of inorganic materials include glass, fused silica glass, synthetic silica glass, silicon, and chalcogenides.

[0152] Examples of organic materials include polyethylene terephthalate (PET), acrylic resin, polyvinyl chloride resin, cycloolefin polymer (COP), cycloolefin copolymer (COC), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), and polyethylene (PE).

[0153] Examples of radical polymerization type UV-curable resins include acrylate resins, urethane acrylates, polyester acrylates, polybutadiene acrylates, epoxy acrylates, silicone acrylates, amino resin acrylates, and ene-thiol resins. Examples of cationic polymerization type UV-curable resins include vinyl ether resins, alicyclic epoxy resins, glycidyl ether epoxy resins, urethane vinyl ethers, and polyester vinyl ethers.

[0154] Examples of thermosetting resins include epoxy resins, phenolic resins, unsaturated polyester resins, urea resins, melamine resins, silicone resins, and polyurethanes.

[0155] As described later, when a functional film is used in an optical device, the substrate is preferably glass from the viewpoint of transparency. When a functional film is used in an inkjet head, the substrate is preferably silicon. When a functional film is used in a mold, the substrate is preferably SiC, cemented carbide, etc.

[0156] (1) Uneven layer formation step S1 Figure 25 is a flowchart of the uneven layer formation process. Figure 26 is a process diagram showing an example of the uneven layer formation process. In the uneven layer formation process S1, first, an inorganic layer of uniform thickness is formed. Next, a mask is formed on the surface of the inorganic layer and etched, and then the mask is peeled off to obtain an inorganic layer with a fine uneven structure, i.e., an uneven layer. The details of each process will be explained below.

[0157] (1.1) Inorganic layer formation step S11 As shown in Figure 26, a reflectance adjustment layer 5 is formed on the substrate 1, and an inorganic layer 2 containing inorganic material as the main component is formed on the reflectance adjustment layer 5, for example by a dry film deposition method. If the reflectance adjustment layer 5 is not provided, the inorganic layer 2 is formed on the substrate 1, although this is not shown in the figure. Details of the reflectance adjustment layer 5 will be described later.

[0158] Dry film deposition methods include vacuum deposition, ion beam deposition, and ion plating. Sputtering-based dry film deposition methods include sputtering, ion beam sputtering, and magnetron sputtering. Among these, ion-assisted deposition (IAD) or sputtering is preferred.

[0159] The thickness of the inorganic layer is preferably adjusted as appropriate depending on the type of inorganic material. When the inorganic material is SiO2, the thickness is preferably in the range of 100 to 600 nm. When the inorganic material is SiC, the thickness is preferably in the range of 100 to 1000 nm. When the inorganic material is SiOC, the thickness is preferably in the range of 100 to 500 nm. When the inorganic material is SiCN, the thickness is preferably in the range of 100 to 500 nm.

[0160] (1.2) Mask formation process S12 Next, as shown in Figure 26, a mask 3 is formed on the inorganic layer 2. In this embodiment, the mask formation step is performed only once.

[0161] The mask preferably consists of a metal portion that covers areas that will not be etched and an exposed portion that exposes areas to be etched. Examples of metals that make up the main component of the mask include silver (Ag), indium, and tin, with silver being the preferred choice. The thickness of the mask is preferably in the range of 2 to 100 nm.

[0162] Depending on the film formation conditions, for example, if a mask is formed using vapor deposition with a substrate temperature of 370°C, a rate of 3 Å, and a thickness of 2 nm, a mask with many dispersed particles is formed. In this case, the metal parts are particulate. Alternatively, if a mask is formed using vapor deposition with a substrate temperature of 170°C, a rate of 3 Å, and a thickness of 12-15 nm, a mesh-like mask with elongated particles or intertwined strings is formed. In this case, the metal parts are mesh-like.

[0163] Furthermore, for example, if a mask is formed using the sputtering method with a substrate temperature of 30°C, a deposition rate of 3 Å, and a thickness of 10 nm, a porous mask is formed. In this case, the exposed areas are the fine pores of the porous structure. Thus, the shape of the mask can be controlled by adjusting the mask deposition method, substrate temperature, deposition rate, and thickness. As a result, the shape of the protrusions can be controlled.

[0164] The film deposition temperature for the mask is preferably within the range of 20 to 400°C. By adjusting the film deposition temperature of the mask, the shape of the mask can be controlled, and the shape of the protrusions can be controlled.

[0165] (1.3) Etching process S13 Next, the inorganic layer 2 is etched. The etching process is performed at least once, and may be performed two or more times.

[0166] In this embodiment, the "number of etching steps" is counted as one step, from the time the object to be etched is placed in the etching apparatus and etching begins until it is released to the atmosphere. In other words, even if the etching conditions are changed during etching, if it is not released to the atmosphere, the etching step is counted as one step.

[0167] In the etching process, it is preferable to combine anisotropic etching conditions and isotropic etching conditions. Specifically, etching is performed first under anisotropic etching conditions, and then under isotropic etching conditions. It is preferable to repeat this combination of anisotropic and isotropic etching multiple times.

[0168] For example, it is preferable to perform anisotropic etching followed by isotropic etching, and then repeat this combination. Furthermore, it is even more preferable to perform the series of etching steps without opening to the atmosphere. In this case, since there is no opening to the atmosphere, the etching step is performed only once.

[0169] Alternatively, after performing anisotropic etching, the mask may be exposed to the air and stored for one hour under atmospheric humidity to promote mask migration, and then anisotropic etching may be performed again. In this case, the etching process is performed twice.

[0170] In particular, if the convex staircase has two or more steps, anisotropic etching and isotropic etching are combined. If the convex staircase has one step, the convex staircase can be formed by anisotropic etching alone.

[0171] In this embodiment, "isotropic etching" refers to etching that proceeds at a uniform speed in all directions of the object. "Anisotropic etching" refers to etching that proceeds at a faster speed in a specific direction of the object. In other words, in anisotropic etching, etching proceeds preferentially only in the specific direction of the object.

[0172] Therefore, by performing anisotropic etching through a mask, etching preferentially proceeds in the depth direction (film thickness direction) of the inorganic layer, and irregularities are formed in the inorganic layer.

[0173] By performing isotropic etching, etching proceeds uniformly in both the depth direction (film thickness direction) and the surface direction of the mask, allowing the size of the mask to be changed. In other words, when changing the size of the mask, it is not necessary to peel off the mask and form a new one. Therefore, it is not necessary to form a mask for each step of the staircase in the convex part, and the number of mask formations can be reduced. As a result, the components of the mask do not get into the grooves formed by etching, and a fine uneven structure of the desired shape can be formed. In addition, since the number of times the mask is peeled off is reduced, the amount of inorganic material layer that is peeled off and removed along with the mask during peeling can be reduced.

[0174] Isotropic etching allows for the rounding of sharp corners in the inorganic layer, creating a more rounded shape. Furthermore, the sides near the sharp corners are also etched, with the material being removed more towards the top surface, resulting in a tapered shape that narrows towards the top.

[0175] (1.3.1) Anisotropic etching In anisotropic etching, the inorganic layer is etched from the top (surface) side through a mask. Anisotropic etching creates recesses in the uneven layer, resulting in the formation of protrusions.

[0176] If the convex portion has two steps, it is preferable that the anisotropic etching consists of a first anisotropic etching and a second anisotropic etching. It is preferable to perform the first anisotropic etching as shown in S131 of Figure 26, then the first isotropic etching as shown in S132 of Figure 26, and then the second anisotropic etching as shown in S133 of Figure 26. From the viewpoint of cost reduction, it is preferable not to expose the etching process to the atmosphere during the series of etching steps.

[0177] In the first anisotropic etching, it is preferable to etch to the extent that the surface of the reflectance adjustment layer is not exposed. For example, it is preferable to control the etching time so that the total average height H is 1 μm or less. The first anisotropic etching forms convex and concave portions. As will be described later, if the reflectance adjustment layer includes a photocatalyst layer, it is preferable for the photocatalyst layer to be exposed, so etching is performed so that the photocatalyst layer is exposed.

[0178] The second anisotropic etching is performed after the first isotropic etching, which will be described later. Since the mask becomes smaller by the first isotropic etching, the inorganic layer is etched from the top side (surface side) through the smaller mask in the second anisotropic etching. In the second anisotropic etching, it is preferable to etch to the extent that the surface of the reflectance adjustment layer is not exposed in the recesses. Specifically, it is preferable to control the etching time so that the height of the lowest step is within the range of 10 to 200 nm. The second anisotropic etching forms a two-step staircase in the convex portion.

[0179] While this range is not always applicable depending on the capabilities of the equipment, it is preferable that the frequency of the RF power supply during anisotropic etching be as low as possible. This reduces the cost of mass production equipment and makes it advantageous to scale up the equipment. In the first anisotropic etching, the frequency of the RF power supply is preferably in the range of 0.5 kHz to 1 MHz, and in the second anisotropic etching, the frequency of the RF power supply is preferably in the range of 0.5 kHz to 1 MHz.

[0180] From the perspective of increasing the selectivity of the mask, the power density for the first anisotropic etching is 0.01 to 1 W / cm². 2 It is preferable that the current is within the range of 0.01 to 1 W / cm² in the second anisotropic etching. 2 It is preferable that it be within this range. Here, "mask selectivity" refers to the value expressed as (rate at which the inorganic layer is removed) / (rate at which the mask is removed). In other words, "a higher mask selectivity" means that the inorganic layer is removed more preferentially than the mask.

[0181] From the viewpoint of increasing the selectivity ratio of the mask, it is preferable that the substrate has a cooling mechanism or a heat dissipation mechanism. If there is no cooling mechanism or heat dissipation mechanism, the power may be stopped and a waiting period may be provided for cooling as appropriate, or the etching process may be completely stopped and the substrate may be opened to the atmosphere for heat dissipation. Alternatively, the power may be intermittently supplied by switching it on and off using a pulse power supply.

[0182] The time for the first anisotropic etching is preferably in the range of 1 minute to 2 hours, and the time for the second anisotropic etching is preferably in the range of 1 minute to 2 hours. The temperature inside the etching apparatus chamber is preferably in the range of 5 to 30°C, and the starting vacuum is preferably in the range of 1 to 20 Pa.

[0183] For the first and second anisotropic etching, it is preferable to use an etching apparatus that performs reactive dry etching, or an apparatus in which etching gas is introduced into an IAD deposition apparatus. The etching apparatus is preferably configured to have a plasma electrode and to be able to cool the plasma electrode.

[0184] It is preferable to use etching gases such as CHF3, CF4, COF2, and SF6. This etches the material from the top surface of the inorganic layer to the vicinity of the top surface of the reflectance adjustment layer to a predetermined size, forming multiple recesses and thus creating protrusions. In other words, the portion of the inorganic layer corresponding to the exposed part of the mask is etched.

[0185] In the first anisotropic etching process, the etching gas flow rate is preferably in the range of 5 to 100 sccm. In the second anisotropic etching process, the etching gas flow rate is preferably in the range of 5 to 100 sccm.

[0186] (1.3.2) Isotropic etching In isotropic etching, the mask is etched. Isotropic etching etches the mask in both the depth direction (thickness direction) and the surface direction, thereby changing the size of the mask.

[0187] Furthermore, in isotropic etching, it is preferable that not only is the size of the mask changed, but that the sharp corners of the inorganic layer are rounded. That is, it is preferable to have a step of rounding the corners of multiple protrusions included in the fine uneven structure. As shown below, by controlling the power density and time, the size of the mask can be changed and the sharp corners of the inorganic layer can be rounded.

[0188] If the convex step has two steps, it is preferable that the isotropic etching includes a first isotropic etching as shown in S132 of Figure 26 and a second isotropic etching as shown in S134 of Figure 26. It is preferable that the second isotropic etching be performed before removing the mask. This allows for the formation of a rounded shape at the tip and prevents excessive removal of the upper surface of the first step.

[0189] In isotropic etching, it is preferable to change the vacuum level or power density at least once during the etching process. For example, initially, the vacuum level should be in the range of 5 to 20 Pa, and the power density should be 0.01 to 0.5 W / cm². 2 Isotropic etching is performed within the specified range. Partway through, the vacuum level is changed to a range of 1 to 10 Pa, and the power density to 0.03 to 1.0 W / cm². 2 It is preferable to change it within the range.

[0190] The initial isotropic etching time is preferably in the range of 1 minute to 2 hours, and the isotropic etching time after the change in conditions is preferably in the range of 1 minute to 1 hour. The chamber of the etching apparatus is preferably in the range of 5 to 30°C and the initial vacuum level is preferably in the range of 1 to 20 Pa.

[0191] Isotropic etching is preferably performed using an etching apparatus that performs reactive dry etching, or an IAD deposition apparatus in which etching gas is introduced. Examples of etching gases used include Ar, O2, N2, CHF3, CF4, COF2, and SF6. This is used to isotropically etch the mask, thereby changing the size of the mask. The flow rate of the etching gas in isotropic etching is preferably in the range of 5 to 100 sccm.

[0192] The mask modified by the first isotropic etching preferably has an average diameter in the range of 10 to 200 nm when viewed from above, and preferably has an average height in the range of 5 to 50 nm in the cross-sectional shape perpendicular to the film thickness direction. The longer the etching time, the closer the mask shape becomes to a circle, that is, the closer the ratio of the major axis diameter to the minor axis diameter approaches 1.

[0193] (1.4) Mask peeling process S14 As shown in Figure 26, the mask formed on the upper surface of the inorganic layer is peeled off and removed. Specifically, the mask is removed by wet etching using chemicals such as nitric acid, acetic acid, iodine, or potassium iodide. Alternatively, the mask may be removed by dry etching using Ar (argon) or O2 (oxygen) as the etching gas. By removing the mask, a layer with a stepped shape in the convex portions is formed.

[0194] (1.5) Mask conditions When forming a textured layer with three steps in the convex portion, the thickness of the mask used to form the third step is preferably in the range of 5 to 100 nm. The thickness of the mask used to form the second step is preferably in the range of 5 to 70 nm. The thickness of the mask used to form the first step is preferably in the range of 2 to 10 nm.

[0195] (2) High hardness layer formation process S2 In the high-hardness layer formation step S2, a high-hardness layer is formed on the upper surface of the formed uneven layer. The method for forming the high-hardness layer is not particularly limited. Examples of formation methods include vacuum deposition, ion-assisted deposition (IAD), sputtering, and CVD. The temperature when forming the high-hardness layer is not particularly limited.

[0196] The high-hardness layer may be formed to cover the entire uneven layer, or to cover only a portion of the uneven layer. When covering only a portion of the uneven layer, it is preferable to cover at least the upper surface of the uppermost layer of the uneven layer.

[0197] (3) Sliding layer formation step S3 In step S3, the slip layer is formed on the upper surface of the formed high-hardness layer. The method for forming the slip layer is not particularly limited. Examples of formation methods include vacuum deposition, ion-assisted deposition (IAD), sputtering, and CVD.

[0198] The slip layer may be formed to cover the entire uneven layer, or to cover only a portion of the uneven layer. If only a portion of the uneven layer is covered, it is preferable to cover at least the upper surface of the uppermost layer of the uneven layer.

[0199] (4) Water repellent layer formation step S4 In step S4, the water-repellent layer formation step, a water-repellent layer is formed on the upper surface of the formed slip-resistant layer. The method for forming the water-repellent layer is not particularly limited. However, from the viewpoint that it is preferable for two or more types of water-repellent materials to be exposed on its surface and for the two or more types of water-repellent materials to be uniformly mixed without separation, it is preferable to form it by the following method.

[0200] Figure 27 is a flowchart of the water-repellent layer formation process. In the water-repellent layer formation process S4, the second water-repellent material application process S42 is performed after the first water-repellent material application process S41. In practice, two types of water-repellent materials are prepared and placed on separate resistance heating boats. Next, it is preferable to apply the first water-repellent composition and the second water-repellent composition to the upper surface of the sliding layer in order by resistance heating deposition. Furthermore, it is desirable to perform the application of the first water-repellent composition and the application of the second water-repellent composition continuously under the same vacuum and without opening to the atmosphere. Normally, the second water-repellent composition cannot adhere after the first water-repellent composition has dried, but this allows the second water-repellent composition to mix on top of the first water-repellent composition and adhere to each other.

[0201] In other words, the application of the second water-repellent composition is performed before the solvent contained in the first water-repellent composition evaporates and dries, forming a layer. This results in the formation of a single layer in which two or more water-repellent materials are mixed to some extent.

[0202] It is believed that the water repellency of water-repellent materials decreases when their molecular orientation is disrupted, and that the better the water-repellent performance of a water-repellent material, the more its performance depends on molecular orientation. In functional films using water-repellent materials with a high degree of dependence on molecular orientation, rubbing with lens paper containing water reduces the degree of orientation of the water-repellent material, causing a rapid deterioration in water repellency. On the other hand, in functional films using water-repellent materials with a low degree of dependence on molecular orientation, even if the degree of orientation of the water-repellent material decreases by rubbing with lens paper containing water, the water repellency does not deteriorate as much and is considered to be relatively durable. Therefore, it is thought that by placing a water-repellent material with a high degree of dependence on molecular orientation and excellent water repellency in the lower layer, and a water-repellent material with a low degree of dependence on molecular orientation on top of it, it is possible to improve abrasion resistance while maintaining water repellency. The reason why water repellency can be maintained is that electrical properties affect surface properties over short distances; in other words, water-repellent materials with a high degree of dependence on molecular orientation greatly influence the water repellency of the outermost surface of the functional film, even in the lower layer. This makes it possible to achieve both abrasion resistance and water repellency in functional films.

[0203] In this embodiment, the water-repellent layer preferably contains a fluorine-based material and a silicon-based material. In this case, since fluorine-based materials generally depend more on molecular orientation than silicon-based materials, it is preferable to apply the fluorine-based material and then the silicon-based material to the upper surface of the water-repellent layer in that order. Furthermore, the silicon-based material is applied before the layer of fluorine-based material is formed, that is, before the solvent applied together with the fluorine-based material evaporates and dries. This is thought to allow the fluorine-based material and the silicon-based material to mix to some extent, and both the silicon-based material and the fluorine-based material to be exposed on the surface of the water-repellent layer.

[0204] Methods for imparting a water-repellent composition include spin coating, dip coating, and vacuum deposition. Apparatus for forming the water-repellent layer includes dry deposition apparatus and wet deposition apparatus.

[0205] Although the above describes the method for forming a water-repellent layer on the upper surface of a slip-resistant layer, the same method can be used to form a water-repellent layer on the upper surface of an uneven layer or a high-hardness layer.

[0206] 8. Applications of functional films By using the functional film of this embodiment, water repellency can be imparted. Furthermore, since the functional film of this embodiment has high transparency and low reflectivity depending on the material, it can be suitably incorporated into optical components.

[0207] Functional films are used for coatings that provide water repellency, antibacterial properties, and mold resistance. Specifically, they are used for coatings on components and casings of electronic devices, tableware, toilets, bathtubs, sinks, and window glass. Furthermore, because functional films are thin, they can be used in precision structures and are suitable for application to inkjet heads, molds, and the like.

[0208] (1) Inkjet head When a functional film is applied to a substrate and the substrate is used as an inkjet head, the substrate is preferably silicon from the viewpoint of durability and processing characteristics. The inorganic material as the main component contained in the uneven layer is preferably SiC from the viewpoint of ink wipeability.

[0209] (2) Mold When a functional film is applied to a substrate and the substrate is used as a mold, the substrate is preferably SiC or cemented carbide from the viewpoint of strength. The inorganic material as the main component contained in the uneven layer is preferably SiC from the viewpoint of strength. In addition, SiC readily yields reaction products with fluorine gas and is easy to etch.

[0210] (3) Optical components The optical device preferably includes optical components to which a functional film is applied. Examples of optical components include lenses and mirrors. The functional film may be applied directly to the lenses, mirrors, etc., or to their cover glass, antibacterial cover member, antifungal coating member, etc.

[0211] Specifically, the functional film is preferably applied to lenses for in-vehicle cameras, lenses for communication cameras, antibacterial lenses for endoscope cameras, etc. In particular, it is preferably applied to lenses for in-vehicle cameras, and it is preferable that the in-vehicle camera is mounted outside the vehicle. Cameras mounted outside the vehicle are prone to contact with water droplets, sand, dust, etc., but by applying the functional film of this embodiment, it is possible to suppress the adhesion and residue of these substances on the lens, which can cause contamination.

[0212] When a functional film is applied to a substrate and the substrate is used as an optical component, the substrate is preferably glass from the viewpoint of transparency. The inorganic substance as the main component contained in the uneven layer is preferably SiO2 from the viewpoint of transparency. Furthermore, SiO2 readily yields reaction products with fluorine gas and is easy to etch.

[0213] When a functional film is applied to a substrate and the substrate is used as an optical component, the optical component may include a reflectivity adjustment layer between the substrate and the uneven layer. The reflectivity adjustment layer may be a single-layer structure or a multi-layer unit. The material of the reflectivity adjustment layer is not particularly limited and examples include Al2O3, ZnS, and SiC.

[0214] Optical components are preferably low reflectivity. The refractive index is preferably increased in the order of functional film, reflectivity adjustment layer, and substrate. Specifically, the reflectivity of the optical component can be sufficiently reduced by having a refractive index of the reflectivity adjustment layer in the range of 1.3 to 3.5 and a refractive index of the substrate in the range of 1.45 to 5.0. The average light reflectivity of the optical component in the wavelength range of 450 to 780 nm is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less. [Examples]

[0215] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, the units "parts" or "%" are used, and unless otherwise specified, they represent "parts by mass" or "mass%". Furthermore, in the following examples, the operations were carried out at room temperature (25°C) unless otherwise specified.

[0216] 1. Fabrication of functional film 1 A reflectivity adjustment layer was formed on a substrate, and a functional film was fabricated on the reflectivity adjustment layer. The steps in the raised portions of the uneven layer were made in two steps. The resulting laminate, i.e., the entire structure consisting of the substrate, reflectivity adjustment layer, and functional film, will hereafter be referred to as an optical component.

[0217] (1) Preparation of the base material As the substrate, we prepared a glass substrate called "TafD lens" (manufactured by HOYA Corporation) (refractive index: 1.84). The following are the details of each substrate shown in the table below. • TafD lens (glass substrate, manufactured by HOYA Corporation) • Si (silicon substrate, manufactured by Furuuchi Chemical Co., Ltd.) • SiC (Silicon carbide substrate, manufactured by Aszac Corporation)

[0218] (2) Formation of reflectance adjustment layer The reflectivity adjustment layer consists of two layers: an SiO2 layer (10 nm thick) and an Al2O3 layer (32 nm thick) from the substrate side.

[0219] The substrate was placed in an IAD vacuum deposition apparatus. SiO2 was loaded as the deposition material, and deposition was carried out at a deposition rate of 1 Å / sec to form a 10 nm thick SiO2 layer on the substrate. The IAD conditions were: acceleration voltage 1000V, acceleration current 1000mA, suppressor voltage 500V, neutralization current 1500mA, and neutral gas Ar10sccm. Heating temperature 160℃ Starting vacuum degree 3.0×10 -3 Pa (Evaporation source for film-forming materials) Electronic gun (IAD Ion Source) Synchron RF Ion Source NIS-175-3 Film deposition material: SiO2 (manufactured by Canon Optron Corporation, product name: SiO2)

[0220] The substrate with the SiO2 layer formed was placed in an IAD vacuum evaporation apparatus. Al2O3 was loaded as the film-forming material and evaporated at a film-forming rate of 3 Å / sec to form an Al2O3 layer with a thickness of 32 nm on the SiO2 layer. The IAD conditions were an acceleration voltage of 1000 V, an acceleration current of 1000 mA, a suppressor voltage of 500 V, a neutralization current of 1500 mA, and 10 sccm of neutral gas Ar. (Chamber internal conditions) Heating temperature: 160 °C Initial vacuum degree: 3.0×10 -3 Pa (Evaporation source of the film-forming material) Electron gun (IAD ion source) RF ion source NIS-175-3 manufactured by Synchron Film-forming material: Al2O3 (trade name: Al2O3 manufactured by Canon Optron Co., Ltd.)

[0221] (3) Formation of the uneven layer 1 (3.1) Formation of the inorganic layer 1 The substrate with the reflectance adjustment layer formed was placed in an IAD vacuum evaporation apparatus. SiO2 was loaded as the film-forming material and evaporated at a film-forming rate of 1 Å / sec to form an inorganic layer (SiO2 layer) with a thickness of 475 nm on the reflectance adjustment layer. The IAD conditions were an acceleration voltage of 1000 V, an acceleration current of 1000 mA, a suppressor voltage of 500 V, a neutralization current of 1500 mA, and 10 sccm of neutral gas Ar. (Chamber internal conditions) Heating temperature: 370 °C Initial vacuum degree: 3.0×10 -3 Pa (Evaporation source of the film-forming material) Electron gun (IAD ion source) RF ion source NIS-175-3 manufactured by Synchron Film-forming material of the inorganic layer: SiO2 (trade name: SiO2 manufactured by Canon Optron Co., Ltd.)

[0222] (3.2) Formation of the Ag mask An Ag mask was formed on the formed inorganic layer. Using a film-forming apparatus (BMC-800T, manufactured by Synchrotron Co., Ltd.), film formation was carried out under the following conditions to form an Ag mask. The thickness of the Ag mask was 20 nm. Heating temperature: 160 °C Initial vacuum degree: 1.33×10 -3 Pa Film-forming rate: 1 Å / sec

[0223] (3.3) Etching (3.3.1) First anisotropic etching In the etching apparatus, the substrate on which the Ag mask was formed was placed on a plasma electrode through which internal cooling water at 20 °C flowed, and the first anisotropic etching was carried out. Etching was performed at an etching rate of 2 nm / min to form the uneven shape of the second stage (the bottommost stage). The etching depth, that is, the total average height H of the convex part, was set to 100 nm. The etching conditions were set to an input power of 300 W, a gas flow rate of 50 sccm, and a vacuum degree of 10 Pa.

[0224] (Chamber internal conditions) Apparatus BIG CUBE manufactured by Upatenter Co., Ltd. Temperature: 20 °C Initial vacuum degree: 10.0 Pa (Etching gas) CHF3 (Etching gas flow rate) 50 sccm (Power density) 0.035 W / cm <00000​​​​​​​​​​​(In-chamber conditions) Device: BIG CUBE manufactured by U-Patentor Co., Ltd. Temperature: 20℃ Starting vacuum degree: 10.0Pa (Etching gas) CHF3 (Etching gas flow rate) 20 sccm (power density) 0.095 W / cm² 2

[0227] (3.3.3) Second anisotropic etching After changing the mask size by isotropic etching, a second anisotropic etching was performed. Etching was carried out at an etching rate of 2 nm / min to form the first layer of uneven surface. The etching depth, i.e., the average height h of the first layer (top layer), was set to 50 nm. The etching conditions were: input power of 300W, gas flow rate of 50 sccm, and vacuum level of 10 Pa.

[0228] (In-chamber conditions) Device: BIG CUBE manufactured by U-Patentor Co., Ltd. Temperature: 20℃ Starting vacuum degree: 10.0Pa (Etching gas) CHF3 (Etching gas flow rate) 50 sccm (power density) 0.035 W / cm² 2

[0229] (3.3.4) Second isotropic etching After forming the first layer of uneven surface, isotropic etching was subsequently performed to round off the edges of the first layer. Etching was performed for 300 seconds under the following conditions: input power of 800W, gas flow rate of 50 sccm, and vacuum level of 10 Pa.

[0230] (In-chamber conditions) Device: BIG CUBE manufactured by U-Patenter Co., Ltd. Temperature: 20°C Initial vacuum degree: 10.0 Pa (Etching gas) CHF3 (Etching gas flow rate) 50 sccm (Power density) 0.095 W / cm 2

[0231] In addition, a series of processes up to the first anisotropic etching, the first isotropic etching, the second anisotropic etching, and the second isotropic etching were carried out without opening to the atmosphere. That is, the number of etching times was 1 time.

[0232] (3.4) Removal of Ag mask After the second isotropic etching, the substrate was immersed in Pure Etch Au100 (manufactured by Hayashi Junyaku Co., Ltd.) for 5 seconds to remove the Ag mask, and an uneven layer was obtained. Then, the substrate was washed with pure water and cleaned in a UV ozone device (manufactured by Technovision Co., Ltd.) for 600 seconds. The refractive index of the uneven layer after mask removal was as shown in the following table.

[0233] (4) Formation of high-hardness layer After removing the Ag mask, a high-hardness layer was formed on the formed uneven layer.<0​​​​​​​​​​​​​​​​​​​​Film deposition material: Ta2O5-TiO2 (manufactured by Canon Optron, product name: OA-600) Using a Gener-1300 vacuum deposition machine (Optron Corporation), the above-mentioned film deposition material was loaded, and deposition was carried out at a deposition rate of 1 Å / sec to form a 2 nm thick slip film. Base material temperature: 25℃ Starting vacuum degree: 3.0×10 -3 Pa (Evaporation source for film-forming materials) Electronic gun

[0235] (6) Formation of a water-repellent layer Subsequently, a water-repellent layer was formed on the slidable layer within the same apparatus.

[0236] (6.1) Application of fluorine-based materials A fluorine-based material was applied to the formed slip-down layer. Using a Gener-1300 (Optron) vacuum deposition machine, the following deposition materials were loaded and deposited at a deposition rate of 1 Å / sec. The thickness of the fluorine-based material immediately after deposition was 25 nm. Film deposition material: Optool UD120 (manufactured by Daikin Industries, Ltd.) Base material temperature: 25℃ Starting vacuum degree: 3.0×10 -3 Pa (Evaporation source for film-forming materials) resistance heating

[0237] (6.2) Provision of silicon-based materials A silicon-based material was deposited onto a previously deposited fluorine-based material. Using a Gener-1300 vacuum deposition machine (Optron), the following deposition materials were loaded and deposited at a deposition rate of 1 Å / sec. Immediately after deposition, the silicon-based material was 5 nm thick. Note that when the silicon-based material was deposited, the previously deposited fluorine-based material had not formed a film and was in a liquid state containing the solvent. Film deposition material: OR-510 (manufactured by Canon Optron Corporation) Base material temperature: 25℃ Starting vacuum degree: 3.0×10 -3 Pa (Evaporation source for film-forming materials) resistance heating

[0238] After applying fluorine-based and silicon-based materials to the slip-resistant layer, the substrate was dried at 120°C for 12 hours to form a 30 nm thick water-repellent layer.

[0239] The functional film 1 (optical component 1) was obtained in the manner described above.

[0240] 2. Fabrication of functional membranes 2-13 Functional films (optical components) 2-11 were obtained using the same procedure as functional film 1 (optical component 1), except for the following changes to the manufacturing conditions. Furthermore, optical components 7-8 were modified using the substrates shown in Table II. Attempts were made to fabricate functional films 12 and 13.

[0241] Functional film 2: Same as functional film 1 except that the time for the first isotropic etching was changed to 400 s, and the thickness of the fluorine-based material was changed to 10 nm and the thickness of the silicon-based material was changed to 10 nm. Functional film 3: Same as functional film 1 except that the thickness of the fluorine-based material is 10 nm and the thickness of the silicon-based material is 10 nm. Functional film 4: Same as functional film 1 except that the time for the first isotropic etching was changed to 450 s. Functional film 5: Same as functional film 1 except that the time for the first isotropic etching was changed to 550 s, and the thickness of the fluorine-based material was changed to 10 nm and the thickness of the silicon-based material was changed to 15 nm. Functional film 6: Same as functional film 1 except that the time for the first isotropic etching was changed to 400 s, and the thickness of the fluorine-based material was changed to 5 nm and the thickness of the silicon-based material was changed to 7 nm. Functional film 7: The main component of the uneven layer was changed to SiC. Except for changing the time of the first isotropic etching to 400 s and setting the thickness of the fluorine-based material to 25 nm and the silicon-based material to 5 nm, it is the same as functional film 1. Functional film 8: The main component of the uneven layer was changed to Si. It is the same as functional film 1 except that the time for the first isotropic etching was changed to 400 s, and the thickness of the fluorine-based material was changed to 25 nm and the thickness of the silicon-based material was changed to 5 nm. Functional film 9: After the first anisotropic etching, the Ag mask for the second stage was removed without performing the first isotropic etching. Then, the Ag mask for the first stage was formed and the second anisotropic etching was performed, and the Ag mask for the first stage was removed without performing the second isotropic etching. In other words, a two-stage staircase was formed in the uneven layer without performing isotropic etching. The thickness of the fluorine-based material was 25 nm, and the thickness of the silicon-based material was 1 nm. Functional film 10: Same as functional film 9 except that the thickness of the fluorine-based material is 1 nm and the thickness of the silicon-based material is 10 nm. Functional film 11: The uneven layer was made into a single step. A high-hardness layer and a slip-resistant layer were not formed, and the water-repellent layer was formed using only one type of water-repellent material. The thickness of the fluorine-based material was set to 25 nm.

[0242] Figure 28 is a photograph of functional film 1 viewed from directly above. Figure 29 is a photograph of functional film 1 viewed from a 30-degree angle above. Figure 30 is a photograph of functional film 9 viewed from a 45-degree angle above. As shown in Figure 29, it can be seen that the uppermost layer (first layer) of the convex portion is rounded at its tip. Also, as shown in Figure 28, it can be seen that the uppermost layer (first layer) has an island-like structure, and the lowermost layer (second layer) has a mesh-like structure.

[0243] The composition and manufacturing conditions of the obtained functional films (optical components) 1 to 11 are shown in Tables II to V below. Note that the uneven layers of the obtained functional films 1 to 10 all had a fine uneven structure. Furthermore, each measurement item was measured using the method described above. A "-" in the table indicates that the corresponding layer was not formed.

[0244] In Table III, "major axis / minor axis" represents the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) at each stage. "Unmeasurable" means that the major axis could not be defined and therefore the ratio of the major axis diameter to the minor axis diameter could not be measured. The radius of curvature R varied greatly depending on the measurement location in the upper stage (first stage), so it was measured at more than 10 randomly selected locations in the upper stage. For functional films 1-8, the minimum measured value was 30 nm, and the maximum value was 1000 nm or 2000 nm. Also, the radius of curvature R was large, and the taper angle θ T The smaller the value, the more rounded the shape.

[0245] Figure 31 is a photograph of the functional film 1 viewed from a 30-degree angle above, and Figure 32 is a photograph of the functional film 1 viewed from directly above. The outlines of the first and second layers are shown in Figures 31 and 32. Figure 33 is a photograph of the functional film 1 viewed from a 30-degree angle above, showing the radius of curvature R and taper angle θ. T The measurement locations are shown. Figure 34 is a schematic diagram of the functional film to explain the radius of curvature R and taper angle θT.

[0246] In Table V, "F / Si elemental ratio" represents the elemental ratio of fluorine (F) to silicon (Si) on the surface of the water-repellent layer. The elemental ratio was measured by X-ray photoelectron spectroscopy (XPS).

[0247] [Table 2]

[0248] [Table 3]

[0249] [Table 4]

[0250] [Table 5]

[0251] (Functional film 12: Comparative example) We attempted to fabricate a functional film 12 by reversing the order in which the first water-repellent material (fluorine-based material) and the second water-repellent material (silicon-based material) were applied. Aside from changing the order of application of the water-repellent materials, the procedure was the same as for functional film 1. In this case, only the fluorine-based material was exposed on the surface of functional film 12, while the silicon-based material was not.

[0252] (Functional film 13: Comparative example) After applying a first water-repellent material (fluorine-based material) and drying it, an attempt was made to fabricate a functional film 13 by applying a second water-repellent material (silicon-based material). The procedure was the same as for functional film 1, except that the fluorine-based material was applied and then dried. In this case, the silicon-based material was repelled from the fluorine-based material film, and it was not possible to apply the silicon-based material to the fluorine-based material film. Ultimately, only the fluorine-based material was exposed on the surface of the obtained functional film 13.

[0253] 3. Evaluation The obtained functional film was evaluated as follows. The functional film was not peeled from the substrate; the evaluation was performed on the optical component consisting of the substrate, reflectivity adjustment layer, and functional film. The water contact angle and sliding angle were evaluated as performance of the functional film, as they are not affected by the substrate and reflectivity adjustment layer. The average light reflectance was evaluated as performance of the optical component, as it is affected by the substrate and reflectivity adjustment layer.

[0254] (1) Water contact angle and sliding angle before the abrasion test (initial stage) Using the "G-1" contact angle measuring device (manufactured by Elma Co., Ltd.), 10 μL of pure water was dropped onto the surface of the functional film (the surface of the water-repellent layer) under conditions of 23°C and 50% RH. The static contact angle was measured 5 seconds after dropping and was defined as the water contact angle before the abrasion test. A water contact angle of 110 degrees or higher was considered acceptable for practical use. Similarly, the sliding angle was measured and a value of 60 degrees or lower was considered acceptable for practical use.

[0255] (2) Water contact angle after abrasion test (after wear) To create the functional film, take three sheets of "Bencott® Clean Wipe P" (manufactured by Asahi Kasei Corporation), wet them with 1 ml of water using a spray bottle, and apply 50 g / cm² of material. 2 The material was subjected to 100 cycles of abrasion under a given load. While measuring the weight on a standard electronic balance, abrasion treatment was performed by hand polishing (abrasion test). Subsequently, 10 μL of pure water was dropped onto the surface of the functional film (the surface of the water-repellent layer) in an environment of 23°C and 50% RH using a contact angle measuring device "G-1" (manufactured by Elma). The static contact angle was measured 5 seconds after dropping and this was defined as the water contact angle after the abrasion test. A difference (deterioration) of 10 degrees or less between the water contact angle before and after the abrasion test, or a water contact angle of 135 degrees or more after the abrasion test, was considered to be practically acceptable. Similarly, the sliding angle was measured, and a value of 60 degrees or less was considered practically acceptable.

[0256] (3) Average light reflectance The average light reflectance of optical components in the wavelength range of 450 to 780 nm was measured using the "USPM-RU," a spectroscopic reflectance analyzer for micro-areas manufactured by Olympus Corporation. The obtained average reflectance was evaluated according to the following criteria. A, AA, and AAA were considered to be acceptable for practical use. As mentioned above, the optical component consists of a substrate, a reflectance adjustment layer, and a functional film. (standard) AAA: The average light reflectance is 1.0% or less. AA: The average light reflectance is greater than 1.0% and less than or equal to 3.0%. A: The average light reflectance is greater than 3.0% and less than or equal to 5.0%.

[0257] The physical properties of the obtained functional films (optical components) 1 to 11 are shown in Table VI below.

[0258] [Table 6]

[0259] The evaluation results for the functional films 12 and 13 (comparative examples) were similar to those for functional film 11, meaning that their performance deteriorated after the abrasion test (after wear), posing practical problems.

[0260] Measurements of the contact angle and sliding angle before the abrasion test show that the functional film of the present invention has high water repellency. Furthermore, measurements of the contact angle and sliding angle after the abrasion test show that the functional film of the present invention has high abrasion resistance. In addition, the optical component of the present invention has a low average light reflectivity.

[0261] Functional films 1, 7-8 show that the uneven layer, primarily composed of SiO2, exhibits high water repellency both before and after the abrasion test. Furthermore, optical components 1, 7-8 show that the uneven layer, primarily composed of SiO2, has a low average light reflectivity, making it suitable for optical components.

[0262] From functional films 1, 9-10, it can be seen that the larger the radius of curvature R of the uppermost layer (first layer) of the uneven surface, i.e., the more rounded the tip, the better the abrasion resistance and water repellency can be achieved. It can also be seen that the smaller the taper angle of the uppermost layer (first layer) of the uneven surface, the better the abrasion resistance and water repellency can be achieved.

[0263] In forming the uneven layer, it can be seen that the shape of each step in the protrusions can be adjusted by controlling the time of the first isotropic etching. In functional film 3, the time of the first isotropic etching is longer compared to functional film 2. As a result, the ratio of the major axis diameter to the minor axis diameter in the first step is close to 1, and the sharp corners on the lower surface of the first step (upper surface of the second step) are rounded. Consequently, in functional film 3, compared to functional film 2, the contact angle is larger and the sliding angle is smaller both before and after the abrasion test, meaning that the water repellency is higher. [Explanation of Symbols]

[0264] 21 Stage 1 21a Top surface of the first stage 21b Bottom of the first stage 21c Side of the first stage 22 2nd stage 22b Bottom of the second stage 22c Side of the second stage 31 Uneven layer 32 High hardness layer 33 Sliding layer 34. Water-repellent layer 35 Surface conditioning layer 41 First protrusion 42 Second protrusion 43 Third protrusion 44 First recess 45 Second recess 50 Tip 100 Functional membranes

Claims

1. A water-repellent film comprising at least a water-repellent layer and an uneven layer, The water-repellent layer has a first water-repellent material and a second water-repellent material exposed on its surface. The aforementioned uneven layer is a functional film containing inorganic material as its main component and having a fine uneven structure.

2. In the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are in the shape of one or more steps. The functional film according to claim 1, wherein the uppermost of the protrusions in the uneven layer is rounded at its tip.

3. In the vertical cross-sectional shape in the thickness direction of the uneven layer, the protrusions in the uneven layer are in a multi-step, stepped shape. The functional film according to claim 1 or claim 2, wherein, when the uneven layer is viewed from above, the uppermost part of the protrusions in the uneven layer has an island-like structure, and the lowermost part has a mesh-like structure.

4. The aforementioned uneven layer is SiO ２ A functional film according to claim 1 or claim 2, containing as a main component.

5. The first water-repellent material includes a fluorine-based material, and The functional film according to claim 1 or claim 2, wherein the second water-repellent material comprises a silicon-based material.

6. The functional film according to claim 5, wherein the elemental ratio of fluorine to silicon on the surface of the water-repellent layer is in the range of 99:1 to 50:

50.

7. A high-hardness layer is provided between the water-repellent layer and the uneven layer, The functional film according to claim 1 or claim 2, wherein the hardness of the high-hardness layer is higher than the hardness of the uneven layer.

8. The functional film according to claim 7, wherein the high-hardness layer contains an inorganic substance having a Mohs hardness of 9 or higher.

9. The functional film according to claim 1 or claim 2, further comprising a sliding layer between the water-repellent layer and the uneven layer.

10. The functional film according to claim 1 or claim 2, wherein the contact angle with water at 23°C is 130 degrees or more.

11. A method for producing a functional film according to claim 1 or claim 2, The process of forming the aforementioned uneven layer, and The process includes forming the water-repellent layer, The step of forming the water-repellent layer is: A step of applying the first water-repellent material onto the uneven layer, and A method for manufacturing a functional film, comprising the step of applying the second water-repellent material onto the uneven layer before the layer of the first water-repellent material is formed.

12. The step of forming the aforementioned uneven layer is: A method for manufacturing a functional film according to claim 11, comprising the step of rounding off the corners of a plurality of protrusions included in the fine uneven structure.

13. An optical component comprising the functional film described in claim 1 or claim 2.

14. An optical device comprising the optical component described in claim 13.

15. An inkjet head comprising the functional film described in claim 1 or claim 2.

16. A mold comprising the functional film described in claim 1 or claim 2.

Images