Functional film, functional film manufacturing method, optical device, inkjet head and mold

Abstract

A functional film 100 according to the present invention is a functional film 100 containing an inorganic material as a principal ingredient and having a fine concave-convex structure 20b on the surface thereof, wherein in the vertical cross-section shape thereof in the film thickness direction, a plurality of convex parts 21, 22 that constitute the fine concave-convex structure 20B are formed in one stage or a plurality of stages in a stepped shape, and if the Mohs hardness of the inorganic material is X and the number of steps of the convex parts 21, 22 is an integer Y, formula (I) is satisfied, and the average height from the bottom-most surface 21b of the convex part 21 of the lowest stage to the top-most surface 22a of the convex part 22 of the highest stage is 1 μm or less.　Formula (I): 10≤X×Y

Description

[Technical Field]

[0001] The present invention relates to a functional film, a method for manufacturing the functional film, and an optical device, an inkjet head, and a mold each equipped with the functional film. In particular, the present invention relates to a functional film that is both abrasion-resistant and super-water-repellent and that can be mass-produced. [Background technology]

[0002] To date, there have been no superwater-repellent films with excellent abrasion resistance. If the initial contact angle is around 110 degrees, the contact angle will deteriorate by 10 degrees or less even after rubbing. However, as disclosed in Patent Document 1, for example, for superwater-repellent films with an initial contact angle of over 130 degrees, the contact angle usually deteriorates by 10 degrees or more after a rubbing test. The reasons for this are: (i) because superwater-repellent films utilize a concave-convex structure, the fragility of this structure is the cause of the deterioration of the contact angle; and (ii) to create a superwater-repellent film, the pitch, depth, and size of the concave-convex structure must be carefully controlled. Furthermore, because the necessary conditions for improvement regarding (i) and (ii) above have not been met simultaneously, it has not been possible to achieve a durable superwater-repellent film. In particular, for optical and mold applications, it is necessary to precisely process the material into a shape that does not break and has invisible irregularities, and also has water-repellent properties, making it even more difficult. Furthermore, from the viewpoint of mass production and cost, lithography and nanoimprinting, which require processing for each individual substrate, were not suitable. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5716679 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above problems and circumstances, and aims to provide a functional film that is both abrasion-resistant and super-water-repellent and that can be mass-produced, a method for manufacturing the functional film, and an optical device, inkjet head, and mold that include the functional film. [Means for solving the problem]

[0005] In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that it is possible to provide a functional film and a method for manufacturing a functional film that can achieve both abrasion resistance and ultra-water repellency by making the fine uneven structure on the surface of the functional film have one or more stepped convex portions, by ensuring that the relationship between the Mohs hardness of the inorganic substance contained as a main component and the number of steps in the convex portions satisfies specific conditions, and by ensuring that the average height from the bottom surface of the lowest convex portion to the top surface of the highest convex portion is within a specific range, and thus arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0006] 1. A functional film containing an inorganic substance as a main component and having a fine uneven structure on the surface, In a vertical cross section in the film thickness direction, the plurality of convex portions constituting the fine concave-convex structure are Complex It is formed in a stepped shape with several steps, and When the Mohs hardness of the inorganic material is X and the number of steps of the convex portion is an integer Y, the following formula (I) is satisfied: the average height from the bottom surface of the lowest protrusion to the top surface of the highest protrusion is 1 μm or less; When the fine concave-convex structure is viewed from above, among the plurality of convex portions, 1st row The convex portion has a mesh shape. ,and, The inorganic material is SiO 2 , SiOC or SiCN Functional membrane. Formula (I): 10≦X×Y 2. A functional film containing an inorganic substance as a main component and having a fine uneven structure on the surface, In a vertical cross section in the film thickness direction, the plurality of convex portions constituting the fine concave-convex structure are Complex It is formed in a stepped shape with several steps, and When the Mohs hardness of the inorganic material is X and the number of steps of the convex portion is an integer Y, the following formula (I) is satisfied: the average height from the bottom surface of the lowest protrusion to the top surface of the highest protrusion is 1 μm or less; When the fine concave-convex structure is viewed from above, among the plurality of convex portions, 1st row The ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) of the convex portion is within a range of 2.0 to 6.2, and, The inorganic material is SiO 2 , SiOC or SiCN Functional membrane. Formula (I): 10≦X×Y

[0007] 3 When the fine uneven structure is viewed from above, the average diameter of the convex portions on the uppermost level is within a range of 10 to 500 nm, The ratio of the surface area of the uppermost convex portion to the surface area of the entire fine concave-convex structure is within a range of 30 to 70%, and Item 1, in a vertical cross section of the fine uneven structure, an average height from the bottom surface of the uppermost convex portion to the outermost surface of the uppermost convex portion is within a range of 10 to 250 nm. or paragraph 2 The functional film according to claim 1.

[0010] 4 The mutual positional relationship and shape of each of the plurality of convex portions are random with no regularity in terms of identity or periodicity. 3 The functional film according to any one of claims 1 to 5.

[0011] 5 The inorganic substance contains an inorganic substance with a Mohs hardness of at least 9 or more. 4 The functional film according to any one of claims 1 to 5.

[0012] 6 The main component of the inorganic material is silicon dioxide, The first to second terms in which the integer Y is 2 5 The functional film according to any one of claims 1 to 5.

[0013] 7 The convex portion is provided with a sliding membrane. 6 A functional membrane is included in any one of the items up to item 1.

[0014] 8 The convex portion is provided with a film containing a water-repellent material. 7 The functional film according to any one of claims 1 to 5.

[0015] 9 The contact angle of water at 25°C is 130° or more, Bemcot Clean Wipe P (Asahi Kasei Corporation) was used, 250 g / cm 2 Wear occurred 2000 times under the load The deterioration of the contact angle is 10 degrees or less. 8 The functional film according to any one of claims 1 to 5.

[0016] 10 .Items 1 to 5 9 A method for producing a functional film according to any one of claims 1 to 5, A method for manufacturing a functional film, wherein the fine uneven structure is formed through a process of forming a metal mask on an inorganic layer and processing the inorganic layer by dry etching.

[0017] 11 The method includes at least two steps of forming the metal mask and processing it by dry etching. 10 Item 1. A method for producing a functional film according to item 1.

[0018] 12 .Items 1 to 5 9 An optical device comprising the functional film according to any one of claims 1 to 5.

[0019] 13 .Items 1 to 5 9 An inkjet head comprising the functional film according to any one of claims 1 to 5.

[0020] 14 .Items 1 to 5 9 A mold provided with the functional film according to any one of claims 1 to 5. [Effects of the Invention]

[0021] The above-mentioned means of the present invention provide a functional film that can achieve both abrasion resistance and super-water repellency and that can be mass-produced, and a method for manufacturing the functional film. It is also possible to provide an optical device, an inkjet head, and a mold that include the functional film. The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows. As described above, it has been found that in order to achieve both abrasion resistance and super water repellency and ensure mass productivity, the following conditions must be satisfied. (a) To prevent light diffraction, the surface must have random irregularities of submicron or submeter size. (b) To prevent deterioration due to the rub test, it is necessary to eliminate breaks in the structure. (c) To achieve super-water repellency, it is necessary to control the size, pitch, and depth of the irregularities. (d) In order to improve abrasion resistance, it is desirable that the material be inorganic and be formed by a method other than coating. (e) The process does not use lithography such as exposure or stampers. In order to satisfy the above conditions, it is presumed that the relationship between the number of steps (Y) of the convex portions of the fine concave-convex structure on the surface of the functional film and the Mohs hardness (X) of the inorganic substance contained as a main component satisfies the above-mentioned specific condition, and the average height from the bottom surface of the lowest convex portion to the top surface of the highest convex portion is within the above-mentioned specific range, thereby making it possible to control the aspect ratio of the concave-convex structure, achieving both super-water repellency and abrasion resistance, and ensuring mass productivity. That is, by forming a fine uneven structure, water repellency is excellent, and in particular, by having a plurality of stepped convex portions, the aspect ratio of each step can be reduced, and breaking of the structure due to deterioration in a rubbing test can be prevented. On the other hand, when a fine uneven structure having a single-step convex portion is formed, not only is water repellency excellent, but breaking can also be prevented by having the Mohs hardness satisfy the above-mentioned formula (I). As a result, both abrasion resistance and super-water repellency can be achieved. Furthermore, by forming the microstructure of the functional film by a process of forming a metal mask on the inorganic layer and processing the inorganic layer by dry etching, abrasion resistance can be improved and mass production becomes possible. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view showing an example of the basic structure of the functional film of the present invention; [Figure 2] 1 is a cross-sectional view showing an example of the basic structure of the functional film of the present invention; [Figure 3] This is a diagram for explaining a method for calculating the average diameter of the topmost convex portion, and is a screen showing an example of the operation of analyzing images taken with an electron microscope. [Figure 4] This is a diagram for explaining a method for calculating the average diameter of the topmost convex portion, and is a screen showing an example of the operation of analyzing images taken with an electron microscope. [Figure 5] This is a diagram for explaining a method for calculating the average diameter of the topmost convex portion, and is a screen showing an example of the operation of analyzing images taken with an electron microscope. [Figure 6] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an electron microscope. [Figure 7] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an electron microscope. [Figure 8A] FIG. 10 is a diagram illustrating a method for calculating the surface area ratio of the topmost convex portion, showing an image taken by an atomic force microscope. [Figure 8B]This figure is for explaining the method for calculating the surface area ratio of the topmost convex portion, and shows binarized data obtained by an atomic force microscope. [Figure 9A] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 9B] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 9C] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 10A] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 10B] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 10C] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 11A] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 11B] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 11C] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 12A] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 12B] FIG. 1 is a diagram for explaining a method for calculating the ratio of the surface area of the topmost convex portion, and is a screen showing an example of the operation of analyzing an image captured by an atomic force microscope. [Figure 13A] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13B] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13C] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13D] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13E] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13F] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 13G] A process diagram showing an example of the method for producing a functional film of the present invention. [Figure 14] 1 is a cross-sectional view showing another example of the basic structure of the functional film of the present invention. [Figure 15] 1 is a cross-sectional view showing another example of the basic structure of the functional film of the present invention. [Figure 16] FIG. 1 is a cross-sectional view showing an example of a specific configuration of a first reflectance adjustment layer unit provided in the functional film of the present invention. [Figure 17] FIG. 1 is a cross-sectional view showing an example of a specific configuration of a second reflectance adjustment layer unit provided in the functional film of the present invention. [Figure 18A] Electron microscope image of functional film 1 in an embodiment of the present invention [Figure 18B] Electron microscope image of functional film 1 in an embodiment of the present invention [Figure 18C] Electron microscope and binarized data of the functional film 1 in the embodiment of the present invention [Figure 19A] Electron microscope image of functional film 2 in an embodiment of the present invention [Figure 19B] Electron microscope image of functional film 2 in an embodiment of the present invention [Figure 19C] Binary data of functional film 2 in an embodiment of the present invention obtained by an electron microscope [Figure 20A] Electron microscope image of the functional film 3 in the embodiment of the present invention [Figure 20B] Electron microscope image of the functional film 3 in the embodiment of the present invention [Figure 20C]Electron microscope image of the functional film 3 in the embodiment of the present invention [Figure 20D] Binary data of the functional film 3 in the embodiment of the present invention obtained by an electron microscope [Figure 21] Electron microscope image of functional film 4 in an embodiment of the present invention [Figure 22A] Electron microscope image of the functional film 5 in the embodiment of the present invention [Figure 22B] Electron microscope image of the functional film 5 in the embodiment of the present invention [Figure 23A] Electron microscope image of functional film 6 in an embodiment of the present invention [Figure 23B] Electron microscope image of functional film 6 in an embodiment of the present invention [Figure 24A] Electron microscope image of the functional film 7 in the embodiment of the present invention [Figure 24B] Binary data of the functional film 7 in the embodiment of the present invention obtained by an electron microscope [Figure 25A] Electron microscope image of the functional film 8 in the embodiment of the present invention [Figure 25B] Electron microscope image of the functional film 8 in the embodiment of the present invention [Figure 26A] Electron microscope image of the functional film 9 in the embodiment of the present invention [Figure 26B] Electron microscope image of the functional film 9 in the embodiment of the present invention [Figure 26C] Binary data of the functional film 9 in the embodiment of the present invention obtained by an electron microscope [Figure 27A] Electron microscope image of the functional film 11 in the embodiment of the present invention [Figure 27B] Binary data of the functional film 11 in the embodiment of the present invention obtained by an electron microscope [Figure 27C] Electron microscope image of the functional film 11 in the embodiment of the present invention [Figure 28A] Electron microscope images showing evaluation of the initial clouding characteristics of the functional film 9 in an example of the present invention. [Figure 28B] Electron microscope binarized data showing evaluation of the initial cloudiness characteristics of the functional film 9 in an example of the present invention. [Figure 29A] Electron microscope images showing evaluation of the initial clouding characteristics of the functional film 10 in an embodiment of the present invention. [Figure 29B] Binary data obtained by an electron microscope showing evaluation of the initial clouding characteristics of the functional film 10 in an embodiment of the present invention. [Figure 30A] Electron microscope images showing evaluation of the initial clouding characteristics of the functional film 12 in an embodiment of the present invention. [Figure 30B] Electron microscope binarized data showing evaluation of the initial cloudiness characteristics of the functional film 12 in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The functional film of the present invention is a functional film containing an inorganic material as a main component and having a fine uneven structure on its surface, wherein, in a vertical cross section in the film thickness direction, the plurality of convex portions constituting the fine uneven structure are formed in a step-like shape with one or more steps, and when the Mohs hardness of the inorganic material is X and the number of steps in the convex portions is an integer Y, the following formula (I) is satisfied, and the average height from the bottom surface of the lowest convex portion to the top surface of the highest convex portion is 1 μm or less. Formula (I): 10≦X×Y This feature is a technical feature common to or corresponding to each of the following embodiments.

[0024] As an embodiment of the present invention, it is more preferable from the viewpoint of achieving both abrasion resistance and super-water repellency that the average diameter of the convex portions in the uppermost stage when the fine concave-convex structure is viewed from above is within a range of 10 to 500 nm, the ratio of the surface area of the convex portions in the uppermost stage to the surface area of the entire fine concave-convex structure is within a range of 30 to 70%, and the average height from the bottom surface of the convex portions in the uppermost stage to the outermost surface of the convex portions in the uppermost stage in a vertical cross section of the fine concave-convex structure is within a range of 10 to 250 nm.

[0025] When the fine uneven structure is viewed from above, it is preferable from the viewpoint of durability that the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) of at least some of the multiple convex portions is 2 or more.

[0026] It is more preferable from the viewpoint of achieving both abrasion resistance and super-water repellency that at least some of the plurality of convex portions have a mesh-like shape when the fine concave-convex structure is viewed from above.

[0027] It is preferable that the mutual positional relationship and shape of each of the multiple convex portions have randomness with no regularity in terms of identity or periodicity, in that this can prevent light diffraction when the functional film is applied to an optical device.

[0028] It is preferable that the inorganic material contains an inorganic material having a Mohs hardness of at least 9 in terms of excellent abrasion resistance.

[0029] It is preferable that the main component of the inorganic material is silicon dioxide and the integer Y is 2, since this allows for both abrasion resistance and super-water repellency, and the film is applicable to optical device applications that require transparency.

[0030] Providing a sliding film on the convex portion is advantageous in that it helps prevent fogging, improves adhesion, and can suppress deterioration of the contact angle after a rubbing test. Furthermore, it is preferable in terms of water repellency that the convex portions are provided with a film containing a water repellent material.

[0031] It is preferable that the contact angle of water at 25° C. is 130 degrees or more and that the deterioration of the contact angle due to abrasion is 10 degrees or less, from the viewpoint of achieving both abrasion resistance and super-water repellency.

[0032] In the method for producing a functional film of the present invention, the fine relief structure is formed through a process of forming a metal mask on an inorganic layer and processing the inorganic layer by dry etching. In particular, it is preferable to include at least two or more processes of forming a metal mask and processing by dry etching. This process does not require lithography such as exposure or a stamper, making mass production possible and easy to manufacture.

[0033] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values before and after it are included as lower and upper limits.

[0034] [Outline of the functional film of the present invention] The functional film of the present invention is a functional film containing an inorganic material as a main component and having a fine uneven structure on its surface, wherein, in a vertical cross section in the film thickness direction, the convex portions of the fine uneven structure are formed in a step shape of one or more steps, and when the Mohs hardness of the inorganic material is X and the number of steps in the convex portions is an integer Y, the following formula (I) is satisfied, and the average height from the bottom surface of the lowest convex portion to the top surface of the highest convex portion (hereinafter also referred to as the "total average height") is 1 μm or less. Formula (I): 10≦X×Y

[0035] In the present invention, the term "fine uneven structure" refers to a structure having a plurality of fine uneven shapes that are large enough to exhibit a water-repellent effect, and in which the average height of the convex parts is at least 1 μm or less, based on the lowest surface of the concave parts, i.e., the average depth of the concave parts is 1 μm or less. The single or multiple steps of the convex portion according to the present invention refer to a portion having a distance of 10 nm or more in the substantially horizontal plane (average diameter L in FIG. 1 for a single step, L3 in FIG. 2 for multiple steps). It is preferably 30 nm or more, and particularly preferably in the range of 50 to 500 nm. Furthermore, the angle formed by the substantially horizontal plane portion of the step with the vertical direction (angle θ1 in FIG. 1 for a single step, angle θ2 in FIG. 2 for multiple steps) is in the range of 60 to 140 degrees, preferably 70 to 120 degrees. Furthermore, in the case of a multi-stage structure, specifically, it is preferable that at least one of the convex portions satisfies any one of the following conditions (1) to (3), and it is preferable that all of the conditions (1) to (3) are satisfied. (1) In the vertical cross section of the fine uneven structure, the average height of the upper convex portion of adjacent steps (for example, h2 in FIG. 2) is 10 nm or more. (2) When the fine uneven structure is viewed from above, the difference between the average diameter of the convex portion of the upper step (e.g., L2 in Figure 2) and the average diameter of the convex portion of the lower step (e.g., L1 in Figure 2) of adjacent steps is 10 nm or more. (3) When the fine concave-convex structure is viewed from above, the difference between the surface area ratio of the convex portion of the upper step and the surface area ratio of the convex portion of the lower step between adjacent steps is 5% or more. In (1), the average height h2 is preferably 30 nm or more, and more preferably in the range of 50 to 500 nm.In (3), the difference in the surface area ratio is more preferably 10% or more. The measurement can be performed by general cross-sectional SEM observation or AFM observation, and the average value measured at 10 or more locations satisfies the above-mentioned condition.

[0036] The "bottom surface of the lowest protrusion" refers to a surface that is included in the same reference plane as the "bottom surface of the recess." Meanwhile, the "bottom surface of the uppermost convex portion" described below refers to a surface that is included in the same plane as the bottom surface of the concave portion adjacent to the uppermost convex portion. The above definition will be explained in detail in the explanation regarding shape observation using an atomic force microscope (AFM). The definitions of the above "average height of the protrusions," "average diameter of the protrusions," and "proportion of the surface area of the protrusions" will also be described later.

[0037] 1 and 2 are cross-sectional schematic diagrams showing an example of the basic structure of the functional film of the present invention. 1 and 2, the functional film 100 is formed on, for example, a substrate 1 described below, contains an inorganic substance as a main component, and has a fine uneven structure 20A or 20B on its surface. In a vertical cross section in the film thickness direction, the convex portions of the fine uneven structure 20A or 20B are formed in a one-step or multiple-step staircase shape.

[0038] In the present invention, the determination of whether or not "the convex portions of the fine uneven structure are formed in a step-like shape with one or more steps in the vertical cross-sectional shape in the film thickness direction" and the confirmation of the shape can be carried out by observing the cross-sectional shape of a three-dimensional image obtained by measurement using an atomic force microscope (AFM), by observing the cross-section of the functional film with an electron microscope, or by a combination of both methods under the conditions described below.

[0039] Specifically, Fig. 1 is a cross-sectional schematic diagram of a functional film having one-step convex portions, and Fig. 2 is a cross-sectional schematic diagram of a functional film having two-step convex portions. In Fig. 1, a functional film 100 is formed on a substrate 1, the functional film 100 having a fine concave-convex structure 20A consisting of a plurality of one-step convex portions (first-step convex portions 21) containing an inorganic substance. 2, a functional film 100 having a microrelief structure 20B consisting of a plurality of two-step convex portions containing an inorganic substance is formed on a substrate 1. That is, the microrelief structure 20B has first-step convex portions 21 formed on the substrate 1 and second-step convex portions 22 formed on the first-step convex portions 21. In this application, the "first-stage protrusion 21" refers to a protrusion formed on the substrate 1 side, and the "second-stage protrusion 22" refers to a protrusion formed on the first-stage protrusion 21.

[0040] <Mohs hardness> The Mohs hardness used in the present invention is the modified Mohs hardness scale, which is modified into 15 stages. In the present invention, when the Mohs hardness of the inorganic substance contained as a main component in the functional film is X and the number of steps of the convex portion is an integer Y, the above formula (I) is satisfied. Preferably, 14≦X×Y≦39. That is, when the protrusion has one step, that is, a single-step protrusion, it contains an inorganic material having a Mohs hardness of 10 or more. When the protrusion has two or more steps, it is sufficient to contain an inorganic material having a Mohs hardness of 5 or more. The Mohs hardness of typical inorganic materials is shown below.

[0041] [Table 1]

[0042] In the present invention, "containing inorganic substances as the main component" means that the proportion of inorganic substances in all components constituting the functional film is 80% by mass or more, preferably 90% by mass or more and 99.9% by mass or less, and particularly preferably 97% by mass or more and 100% by mass or less.

[0043] The inorganic substance is not particularly limited as long as it satisfies formula (I), but it preferably contains an inorganic substance having a Mohs hardness of at least 9, and more preferably contains an inorganic substance having a Mohs hardness of at least 13. When the convex portions of the fine uneven structure have a single step, formula (I) is satisfied, and therefore the inorganic substance must contain an inorganic substance having a Mohs hardness of 10 or more, and when the convex portions have a two or more step shape, the inorganic substance may contain an inorganic substance having a Mohs hardness of 5 or less. Inorganic substances with a Mohs hardness of 9 or more include Al2(F,OH)2(SiO4), (Mg,Ca,Fe)3(Al,Cr,Fe)2(SiO4)3, ZrO2, TaC, Al2O3, WC, SiC, B4C, C, SiOC, SiCN, etc., and in particular Al2O 3、 S It is preferable to use iC, SiOC, or SiCN. Here, when the convex portion has a single step shape, it is preferable to use SiC, SiOC or SiCN. A functional film using SiC, SiOC or SiCN is suitably used for, for example, an inkjet head or a mold. Furthermore, when the convex portion has two or more steps, transparent SiO2 is preferably used, and specifically, such a functional film is suitably used in, for example, optical devices.

[0044] <Shape and randomness of convex parts> It is an essential or preferred condition that the shape of the convex portions in the fine concave-convex structure according to the present invention, for example, the height and size, is within the range of conditions described below. However, when observing the convex portions in the fine uneven structure as a whole, it is preferable in terms of preventing light diffraction that the mutual positional relationship and shape of each of the multiple convex portions have randomness with no regularity in terms of identity or periodicity within the range of conditions described below.

[0045] In the present invention, "randomness" refers to a state in which randomness or unpredictability is recognized, with no regularity such as overall identity or periodicity, in the relative positions and shapes of the convex portions in the fine concave-convex structure formed under conditions that are assumed to be controlled within the range of conditions for the shape described below. Specifically, this refers to the state shown in the electron microscope photographs obtained in the examples described below. It also refers to a state in which no diffracted light is generated. In the present invention, "a state in which no diffracted light is generated" means that no diffracted light is generated due to interference between multiple reflected lights from the concave-convex portions of the fine concave-convex structure or interference between incident light and reflected light. When a fine uneven structure is formed by an etching process using lithography or nanoimprinting using a mold, diffracted light occurs because the structure has a regular unevenness. However, in the present invention, the fine uneven structure is formed by dry film deposition as described below, so an irregular (random) fine structure is formed, which does not generate diffracted light. The presence or absence of the diffracted light can be confirmed by, for example, placing a sample of the functional film between a helium-neon laser and a screen, irradiating light onto the screen through the sample, and visually checking the light irradiated onto the screen.

[0046] Furthermore, when the fine concave-convex structure is viewed from above, it is more preferable that at least some of the plurality of convex portions have a mesh-like shape, from the viewpoint of achieving both abrasion resistance and super-water repellency. Here, "at least some of the protrusions have a mesh-like shape" refers to a state in which the protrusions are continuously connected with no disconnected portions when viewed from above, as shown in Fig. 25A, for example. In other words, it refers to a network-like state in which the long axis of the protrusions cannot be defined.

[0047] <Total average height> In a vertical cross section of the fine uneven structure in the film thickness direction, the average height from the bottom surface of the lowest protrusion to the top surface of the highest protrusion is 1 μm or less. In the present invention, the "average height from the bottom surface of the lowest convex portion to the top surface of the highest convex portion (also referred to as the "total average height H")" refers to the total etching depth when forming recesses by etching the formed inorganic layer in a vertical cross section (cross section in the thickness direction) of the fine uneven structure, for example.

[0048] Specifically, when the convex portion has a two-stage shape, as shown in FIG. 2, it refers to the distance H from the bottom surface (base end surface) 21b of the first stage (lowest stage) convex portion 21 to the outermost surface (top surface) 22a of the second stage (uppermost stage) convex portion 22. Therefore, as shown in FIG. 13, it refers to the distance H obtained by subtracting the thickness M2 of the unetched inorganic layer 2 from the total thickness M1 of the inorganic layer 2 formed by the manufacturing method of the functional film 100.

[0049] When the convex portion has a single step shape, it refers to the distance H from the bottom surface (base end surface) 21b to the top surface (top surface) 21a of the uppermost convex portion 21, as shown in Figure 1. As above, it refers to the distance H obtained by subtracting the thickness M2 of the unetched inorganic layer 2 from the total thickness M1 of the inorganic layer 2 formed by the manufacturing method of the functional film. The total average height H is 1 μm or less, and preferably in the range of 0.05 to 0.25 μm. The total average height H can be calculated by an image analysis method using an atomic force microscope (AFM), as will be described later.

[0050] In order to set the total average height to 1 μm or less, for example, the thickness of the inorganic layer to be formed, and as described below, the thickness of the metal mask, the film formation temperature of the metal mask, the etching time, etc. can be controlled.

[0051] <Average diameter, surface area ratio, and average height of the topmost convex part> From the viewpoint of achieving both abrasion resistance and super-water repellency, it is more preferable that, when the fine uneven structure is viewed from above, the average diameter of the convex portions in the uppermost layer is within a range of 10 to 500 nm, the ratio of the surface area of the convex portions in the uppermost layer to the surface area of the entire fine uneven structure is within a range of 30 to 70%, and the average height from the bottom surface of the convex portions in the uppermost layer to the outermost surface of the convex portions in the uppermost layer in a vertical cross section of the fine uneven structure is within a range of 10 to 250 nm.

[0052] The average diameter of the uppermost convex portion is preferably within a range of 10 to 500 nm, and more preferably within a range of 50 to 200 nm. In the present invention, the "average diameter of the uppermost convex portion" refers to the average diameter of the uppermost convex portion when the fine concave-convex structure is viewed from above, i.e., when the entire fine concave-convex structure is photographed from above with an electron microscope and the photograph is observed. For example, in the case of a fine concave-convex structure 20A having one-stage convex portions as shown in Fig. 1, this refers to the average diameter L of the first-stage (uppermost) convex portion 21. Furthermore, in the case of a fine concave-convex structure 20B having two-stage convex portions as shown in Fig. 2, this refers to the average diameter L of the second-stage (uppermost) convex portion 22. The average diameter L of the uppermost convex portion can be calculated by taking a photograph using an electron microscope as described below, and then using the image processing free software "ImageJ (ImageJ1.32S created by Wayne Rasband)" to calculate the average diameter L of the uppermost convex portion.

[0053] The ratio of the surface area of the uppermost projection to the total surface area of the entire fine uneven structure is preferably within a range of 30 to 70%, and more preferably within a range of 30 to 55%. In the present invention, "the ratio of the surface area of the uppermost convex portion to the surface area of the entire fine concave-convex structure when the fine concave-convex structure is viewed from above" refers to the ratio of the surface area of the uppermost convex portion to the surface area of the entire fine concave-convex structure (the entire structure including all convex portions and concave portions) when the fine concave-convex structure is viewed from above, i.e., when the entire fine concave-convex structure is photographed from above with an electron microscope and the photograph is observed. The surface area ratio of the uppermost convex portion can be calculated by taking a photograph using an electron microscope as described below, and then using the image processing software "ImageJ (ImageJ1.32S created by Wayne Rasband)" to process the photograph. Alternatively, the surface area ratio may be calculated by measuring image data of the fine concave-convex structure using an AFM, and then binarizing the obtained AFM measurement image using software manufactured by BRUKER. Furthermore, if the AFM needle cannot enter the narrow groove (concave), data obtained from a two-step convex portion will appear to be data from a single-step convex portion, so it is preferable to use a super-sharp or high aspect ratio cantilever whenever possible.

[0054] Furthermore, the average height from the bottom surface of the topmost protrusion is preferably within the range of 10 to 250 nm, more preferably within the range of 30 to 200 nm, in the case of one step, preferably within the range of 10 to 150 nm, more preferably within the range of 30 to 100 nm, in the case of two steps, preferably within the range of 10 to 100 nm, more preferably within the range of 20 to 50 nm, in the case of three steps. In the present invention, the "average height from the bottom surface of the uppermost convex portion to the outermost surface (also referred to as "average height h")" refers to, for example, in the case of a fine concave-convex structure 20B having two-stage convex portions as shown in FIG. 2, the average height from the bottom surface of the second stage ( The total average height H is the distance h from the bottom surface 22b of the first (top) protrusion 22 to the top surface (top face) 22a of the second protrusion 22. In the case of the micro concave-convex structure 20A having one-stage protrusions, the total average height h is the distance from the bottom surface 21b to the top surface (top face) 21a of the first (top) protrusion 21, which is the same as the total average height H. The average height h from the bottom surface to the outermost surface of the uppermost projection can be calculated using an atomic force microscope as described below, or by observing the cross section of the projection with an SEM.

[0055] In order to keep the average diameter L, surface area ratio, and average height h of the uppermost convex portion within the above-mentioned ranges, it is possible to control the thickness of the inorganic layer to be formed, and as described below, the thickness of the metal mask, the film formation temperature of the metal mask, the etching time, etc.

[0056] Furthermore, from the viewpoint of durability, it is preferable that the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) of at least some of the convex portions among the plurality of convex portions when the microrelief structure is viewed from above is 2 or more. The ratio is more preferably 5 or more. Specifically, for example, when viewed from above, it is preferable that the convex portions have an L-shape rather than a perfect circle. Here, the "major axis diameter of the convex portion" refers to the diameter when the smallest circumscribing circle C1 is drawn around the convex portion when the fine uneven structure is observed with an SEM in the "method for calculating the average diameter of the topmost convex portion" described below, and the "minor axis diameter of the convex portion" refers to the diameter when the largest inscribing circle C2 is drawn around the convex portion. Furthermore, the convex portions having such a ratio of major axis diameter to minor axis diameter of 2 or more may be convex portions in the first tier, or convex portions in the second tier or higher, and it is preferable that any of the convex portions have a convex portion with such a ratio because it will have excellent durability. In practice, it is preferable that the convex portions with such a ratio are in the first tier.

[0057] Furthermore, from the viewpoint of achieving both super-water repellency and abrasion resistance, it is preferable that the average diameter of the uppermost convex portion when the micro-relief structure is viewed from above is smaller than the average diameter of the convex portions below the uppermost convex portion. For example, in the case of a microrelief structure 20B having two-stage convex portions as shown in Fig. 2, the average diameter L of the top (second) convex portions 22 is preferably in the range of 10 to 500 nm, as described above, and the average diameter of the bottom (first) convex portions 21 is preferably in the range of 100 to 1000 nm. In the case of a three-stage structure, the average diameter of the top (third) convex portions is preferably in the range of 10 to 500 nm, as described above, the average diameter of the middle (second) convex portions is preferably in the range of 100 to 600 nm, and the average diameter of the bottom (first) convex portions is preferably in the range of 100 to 1000 nm. The average diameter of the lower projections may be calculated by the above-described method before the upper projections are formed.

[0058] The plurality of convex portions 21 and convex portions 22 may be formed regularly, but as described above, it is preferable that they are formed randomly, since this can prevent light diffraction when the functional film is applied to an optical device.

[0059] <Calculation method for the average diameter of the topmost convex part> The average diameter of the uppermost convex portion can be calculated by taking a photograph of the fine uneven structure using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and then using the image processing free software "ImageJ (ImageJ1.32S created by Wayne Rasband)" to calculate the average diameter of the uppermost convex portion. The procedure for image analysis using scanning electron microscope (SEM) photographs is explained below.

[0060] 1) Download the free software ImageJ. 2) Process the image using the following procedure with the default settings. 3) A surface SEM image of the micro-texture structure, previously taken at a magnification of 30,000 times or more using a scanning electron microscope, is loaded into a computer using the free software ImageJ.

[0061] 4) Correlate the number of pixels with the physical length. For example, in the case of Figure 3, 1 μm = 504 pixels.

[0062] 5) Measure the major axis diameter. As shown in Figure 4, for a given particle (e.g., particle R), use the circle tool to draw the minimum circumscribing circle C1. In this case, w = h = 353 above is the number of pixels indicating the diameter (major axis diameter) of the minimum circumscribing circle C1. In other words, the physical length is 353 / 504 = 0.700 μm.

[0063] 6) Measure the minor axis diameter. As shown in Figure 5, for particle R, use the circle tool to draw the maximum inscribed circle C2. In this case, w = h = 127 above is the number of pixels indicating the diameter (minor axis diameter) of the maximum inscribed circle C2. In other words, the physical length is 127 / 504 = 0.251 μm.

[0064] 7) Calculate the average diameter. The average value of the measured major axis diameter and minor axis diameter is calculated. Specifically, (0.700+0.251) / 2=0.475 μm is called the diameter of particle R shown in FIG. In this way, the diameters of 10 random particles are calculated in the same manner, and the average value of the 10 diameters is taken as the average diameter of the sample.

[0065] <Surface area ratio of the topmost convex part> The ratio of the surface area of the topmost convex portion to the surface area of the entire micro-convex structure can be calculated by taking a photograph using an SEM and then performing structural analysis on the photograph using the free image processing software "ImageJ (ImageJ1.32S created by Wayne Rasband)," or by measuring image data of the micro-convex structure using an AFM and binarizing the obtained AFM measurement image using software manufactured by BRUKER. In the present invention, either an image analysis method using an SEM or an image analysis method using an AFM can be used, and it is sufficient that the value calculated by either image analysis method falls within the range specified in the present invention.

[0066] (SEM image analysis) The procedure for image analysis using scanning electron microscope (SEM) photographs is explained below. 1) An SEM image of the surface of the micro-convex / concave structure, previously taken at a magnification of 30,000 or more using a scanning electron microscope, is loaded into a computer using the free software ImageJ. The SEM image changes depending on the adjustment of focus, contrast, and brightness, so it is preferable not to manipulate it artificially.

[0067] 2) Set the black and white definition. In the free software ImageJ, if you check Black Background, a brightness value of 0 will be displayed as black and a brightness value of 255 will be displayed as white. If you do not check Black Background, a brightness value of 0 will be displayed as white and a brightness value of 255 will be displayed as black. In this analysis, the value was checked (i.e., 255 is white).

[0068] 3) Image noise reduction Performs smoothing processing.

[0069] 4) Apply a bandpass filter. For example, the recommended bandpass filter value is 20 to 100. This setting value depends on the initial SEM image, so it is preferable to set it optimally as needed.

[0070] 5) The image is binarized. Convert to 8-bit and set the threshold. Set the above bar (area selected in green) to the right end so that it is 0%. Adjust the below bar (area selected in blue) until it overlaps with the black area of the pore. This threshold value varies depending on the contrast of the image, so it is preferable that the analyst sets it each time rather than fixing it. Once the threshold value is determined, the image is converted into black and white. For example, in the binarized image shown in Fig. 18C, the white part is the topmost convex part (e.g., the second convex part 22 in Fig. 2), and the black part is the part other than the topmost convex part 22 (e.g., the first convex part 21 in Fig. 2).

[0071] 6) Use ImageJ to call up the histogram (see Figures 6 and 7). The histogram will be displayed, so next, press the round List button with the mouse as shown in Figure 6 to display the histogram data in a list, which will show the number of pixels for each tone. In the example of Figure 6, there are 352,791 pixels with Value=0 (i.e., black pixels). Similarly, the example in FIG. 7 indicates that there are 876,009 pixels with a value of 255 (i.e., white pixels).

[0072] 7) Calculate the area ratio. Since the topmost convex part is made up of white pixels, the area ratio of the topmost convex part to the whole is the number of white pixels / (number of white pixels+number of black pixels). In the examples of FIGS. 6 and 7, the area ratio of the topmost convex portion is {876009 / (352791+876009)}×100=71%.

[0073] If the analysis image contains information from the SEM image measurement, it is preferable to perform image analysis after a process such as excluding the information in advance so that it does not affect the analysis.

[0074] (AFM image analysis) Next, the procedure for image analysis using AFM will be explained. An atomic force microscope (AFM) is a type of scanning probe microscope (SPM) that uses the atomic force between a sample and a probe to measure nano-level uneven structures. Specifically, AFM measures the surface roughness of a sample 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 atomic force acting between the atoms at the tip of the probe and the atoms of the sample. Atomic force microscopes (AFMs) scan while feeding back information to a piezoelectric scanner to keep the atomic force constant, i.e., to keep the cantilever deflection constant, and by measuring the amount of displacement fed back to the piezoelectric scanner, they can measure the Z-axis displacement, i.e., the surface roughness structure.

[0075] In the present invention, an L-trace W manufactured by Hitachi High-Technologies Corporation was used as the atomic force microscope (AFM), and an SI-DF40P2 silicon probe also manufactured by Hitachi High-Technologies Corporation was used as the probe.

[0076] A) Acquisition of an AFM image of a micro-structure Using the atomic force microscope (AFM), three-dimensional image data of the fine uneven structure of the functional film is measured (see FIG. 8A).

[0077] B) Binarization of AFM data The obtained AFM measurement image was binarized using software manufactured by BRUKER. Figure 8B shows the binarized data.

[0078] AFM data consists of a collection of three-dimensional data. If you plot this data with the vertical axis representing the depth direction and the horizontal axis representing the number of data points at that depth, you will get the following example. In the case of a single-stage structure, peaks in the number of data points appear on the top and bottom surfaces, as shown in Figure 9C. (In the case of a two-stage structure, peaks in the number of data points appear on the top surface of the first stage and the top surface of the second stage, as shown in Figure 10C.) To find the area occupied by the convex part on the top surface, binarization (color editing) is performed using the midpoint between the peak number of data on the surface and the peak number of data below it (i.e., in the case of a single layer, the bottom surface is the peak number of data below it, and in the case of a two-layer structure, the surface of the first layer is the peak number of data below it) as the threshold.

[0079] Specifically, Figure 9 shows the case of a single-level structure, and Figure 9B shows the cross-sectional profile at the cutting line P1 shown in Figure 9A. The horizontal axis indicates the scan location, and the vertical axis indicates the data in the depth direction. The vertical axis indicates the distance from the deepest point in Figure 9A, which is set as the zero reference point. Figure 9C shows the number of data points in the depth direction. As shown in Figure 9C, the data number peak height from the bottom surface to the top surface is 120 nm, which is the top surface of the first (top) convex part. Therefore, binarization (color editing) is performed using the midpoint (60 nm) of the data number peak (120 nm) on the top surface as the threshold. Specifically, points higher than the midpoint height are displayed in white, and points lower than the midpoint height are displayed in black.

[0080] Fig. 10 shows the case of a two-stage structure, and Fig. 10B shows a cross-sectional profile taken along the cutting line P2 shown in Fig. 10A, with the vertical and horizontal axes being as explained in Fig. 9B. Fig. 10C shows the number of data points in the depth direction. As shown in Figure 10C, the height of the data peak from the bottom surface to the top surface is 225 nm, which is the top surface of the second (top) convex portion. Also, a data peak indicating the surface of the first convex portion is detected at a height of 140 nm from the bottom surface. Therefore, binarization (color editing) is performed using the midpoint (182.5 nm) between the peak data count on the second surface (225 nm) and the peak data count on the first surface (140 nm) as the threshold. Specifically, points higher than this midpoint height are displayed in white, and points lower than this midpoint height are displayed in black.

[0081] In addition, in the present invention, the "outermost surface of the uppermost convex portion" refers to the surface having the height at which the number of data points (frequency) on the surface side is greatest in a histogram such as that shown in FIG. 9, which was created based on data obtained by AFM measurement (see FIGS. 9C and 10C). The "bottom surface of the lowest convex part" refers to the surface included in the same plane as the surface having the deepest depth and the largest number of data points among the bottom surfaces of the concave parts in the histogram (see Figures 9C and 10C). The "bottom surface of the topmost convex portion" refers to the surface included in the same plane as the bottom surface of the recess adjacent to the topmost convex portion, i.e., the surface included in the same plane as the surface having the deepest depth and the largest number of data points among the bottom surfaces of the adjacent recesses in the histogram (see Figure 10C).

[0082] Next, the image thus created is similarly measured for the proportion of the surface area of the uppermost convex portion using the free software ImageJ, which is the image analysis software mentioned above. The specific measurement method is shown below. Although binarization has already been completed using the method described above, it is recommended to also perform binarization using image processing software just to be sure. Convert to 8 bits using the default settings, and then binarize using Threshold = 128 (see Figure 11).

[0083] Next, a histogram of the binarized AFM image is created (see Figure 12). Count the number of black and white data points and calculate the percentage of data points for the outermost surface structure (white). In this case, the percentage of surface area was 41%.

[0084] <Total average height and average height of the topmost convex part> The total average height H and the average height h of the uppermost convex portion are calculated by measuring image data of the fine concave-convex structure using an AFM and using software manufactured by BRUKER. Specifically, any cross section of 1 μm or greater is analyzed, and the distance between the surface with the highest height and the surface with the deepest depth is calculated. This distance is analyzed for 10 arbitrary cross sections, and the average value is taken as the total average height H. The average height h of the topmost convex part is calculated as the difference between the peak number of data points on the surface and the peak number of data points below it (i.e., in the case of a single layer, the bottom surface is the peak number of data points below it, and in the case of a two-layer structure, the surface of the first layer is the peak number of data points below it). In this case, too, the difference is calculated for 10 arbitrary cross sections, and the average value is taken as the average height h.

[0085] <Synovial membrane> The functional film of the present invention is preferably provided with a sliding film on the convex portions, as this is effective in preventing fogging, provides good adhesion, achieves both abrasion resistance and super-water repellency, and is applicable to optical device applications. The sliding film is preferably selected so that a single film of 100 nm is deposited on a white glass substrate manufactured by SCHOTT and left at room temperature for 3 days, and the contact angle is between 40 and 120 degrees. In particular, a film with a difference of 20 degrees or more from the contact angle of the main component constituting the microstructure is even more preferable. The sliding film may be, for example, Ta2O5-TiO2 (trade name, Canon Optron Co., Ltd.) OA-600), Ta2O5, TiO2, SiC, Al2O3, HfO2, etc. do. Examples of methods for forming the sliding film include, in addition to the usual vacuum deposition method, ion-assisted deposition method (IAD method), sputtering method, CVD method, etc. The thickness of the sliding film is preferably within the range of 0.1 to 20 nm.

[0086] <Water-repellent film> In terms of improving water repellency, the functional film of the present invention preferably has a film containing a water repellent material (hereinafter also referred to as a "water repellent film") on the convex portion. The water-repellent material may be a fluorine-based or silicone-based water-repellent material, and specific examples include Fluorosurf (manufactured by Fluoro Technology Co., Ltd.), Optool (manufactured by Daikin Industries, Ltd.), and SC100 (manufactured by Canon Optron Inc.). Examples of methods for forming the water-repellent film include spin coating, dip coating, and vacuum deposition.

[0087] [Method of manufacturing functional films] In the method for producing a functional film of the present invention, a metal mask is formed on an inorganic layer, and the inorganic layer is processed by dry etching to form the fine uneven structure.

[0088] Specifically, an inorganic layer containing an inorganic substance as a main component is formed on a substrate, a metal mask is formed on the inorganic layer, and the metal mask is processed by dry etching to form a fine uneven structure. In particular, it is preferable to perform the process of forming the metal mask and processing by dry etching at least twice.

[0089] 13 is a process diagram showing an example of a method for producing a functional film. In the following description, a method for producing a functional film having a fine uneven structure consisting of two-stage convex portions will be described, but the present invention is not limited to the production method described below.

[0090] (1) Formation of inorganic layer As shown in FIG. 13A, an inorganic layer 2 containing an inorganic substance as a main component is formed on a substrate 1 by, for example, a dry film formation method. The thickness of the inorganic layer varies depending on the type of inorganic material, and is preferably within the range of 100 to 400 nm when the inorganic material is SiO2, preferably within the range of 100 to 1000 nm when the inorganic material is SiC, preferably within the range of 100 to 500 nm when the inorganic material is SiOC, and preferably within the range of 100 to 500 nm when the inorganic material is SiCN.

[0091] (2) First mask deposition 13B, a mask 3 is formed on the inorganic layer 2. An example of the mask 3 is a metal mask composed of a metal portion and an exposed portion. The thickness of the metal mask is preferably in the range of 20 to 100 nm. Although it depends on the film formation conditions, for example, if a metal mask is formed using a vapor deposition method with a substrate temperature of 370°C and a deposition rate of 3 Å to a layer thickness of 2 nm, it will be particulate. Also, for example, if a metal mask is formed using a vapor deposition method with a substrate temperature of 170°C and a deposition rate of 3 Å to a layer thickness of 12 to 15 nm, it will tend to be mesh-like. Furthermore, for example, if a metal mask is formed using a sputtering method with a substrate temperature of 30°C and a deposition rate of 3 Å to a layer thickness of 10 nm, it will tend to be porous. In this way, the average diameter, surface area ratio and average height of the projections formed by etching are controlled by the film formation conditions of the metal mask, the substrate temperature, the film formation rate and the film thickness.

[0092] Therefore, in the case of a functional film having a fine uneven structure consisting of two-stage convex portions as in this embodiment, it is preferable that the thickness of the metal mask used to form the first stage convex portions is in the range of 20 to 100 nm, and that the thickness of the metal mask used to form the second stage convex portions described below is in the range of 5 to 70 nm.

[0093] In the present invention, the metal mask is made of, for example, silver (Ag) or Al, and is particularly preferably made of silver. The film formation temperature for the metal mask is preferably within the range of 20 to 400°C. The average diameter L, surface area ratio, and average height h of the projections formed by etching are also controlled by the film formation temperature of the metal mask.

[0094] Therefore, in the case of a functional film having a fine uneven structure consisting of two-stage convex portions as in this embodiment, it is preferable that the film formation temperature of the metal mask when forming the first stage convex portions is in the range of 150 to 400°C, and that the film formation temperature of the metal mask when forming the second stage convex portions is in the range of 100 to 400°C.

[0095] (3) First etching 13C, etching is performed from the surface side using an etching device (not shown) through a mask 3, from the inorganic layer 2 to the vicinity of the upper surface of the substrate 1, to form recesses, thereby forming protrusions 21. At this time, it is preferable that the etching is performed to such an extent that the surface of the substrate 1 is not exposed, and specifically, the etching time is controlled so that the total average height H is 1 μm or less. Although it is not necessarily within this range depending on the capacity of the equipment, it is preferable that the frequency of the RF power source during etching is as low as possible, as this reduces the cost of mass production equipment and makes it advantageous for larger sizes. It is preferable that the etching power is 1 MHz or less, and 400 KHZ is more preferable. The etching power is 1 W / cm because the selectivity of the metal mask is increased. 2 Preferably less than 0.1 W / cm 2 Furthermore, it is desirable for the substrate to have a cooling device or heat dissipation mechanism in order to increase the mask selectivity, and if there is no cooling mechanism, it is desirable to stop the power and provide a waiting time for cooling, or to stop the power completely and expose it to the atmosphere to dissipate heat, or to use a pulse power supply to turn the power on and off intermittently. The etching time is preferably within a range of 30 to 3000 seconds.

[0096] Etching is performed by reactive dry etching using an etching device, or by using an IAD deposition device with an etching gas introduced into it. Examples of etching gases include CHF3, CF4, COF2, and SF6. This allows etching of a predetermined size from the inorganic layer 2 to the vicinity of the upper surface of the substrate 1, forming multiple recesses and thus forming protrusions 21. In other words, the constituent layers corresponding to the exposed portions of the metal mask 3 are etched.

[0097] (4) First time removing the mask Next, as shown in FIG. 13D, the mask 3 formed on the surface is removed. Specifically, the metal mask is removed by wet etching using chemicals such as acetic acid, iodine, potassium iodide, etc. Alternatively, the metal mask may be removed by dry etching using, for example, Ar or O2 as an etching gas. By removing the mask 3, a fine concave-convex structure 20A having first-stage convex portions 21 is formed.

[0098] (5) Second mask deposition 13E, a mask 4 is formed on the first-stage protrusion 21. The mask 4 used at this time can be the same as the mask 3 used when forming the first-stage protrusion 21. The thickness of the mask used to form the second-stage convex portion and the film formation temperature are as described above.

[0099] (6) Second etching 13F, an etching device is used to etch the inorganic layer 2 from the surface side through a mask 4 to a predetermined area, thereby forming recesses and forming protrusions 22. At this time, it is preferable to control the etching time so that the average height h of the uppermost protrusions 22 falls within the above-mentioned range. The etching time is preferably within a range of 30 to 2000 seconds.

[0100] (7) Second mask removal Next, the mask 4 formed on the surface is removed as shown in Fig. 13G. In this way, a fine concave-convex structure 20B having first-stage convex portions 21 and second-stage convex portions 22 is formed.

[0101] (8) Formation of sclerotial and water-repellent membranes Next, it is preferable to form a sliding film (not shown) on the two-step convex portion (first convex portion 21 and second convex portion 22) using, for example, a dry film forming device. Finally, it is preferable to form a water-repellent film (not shown) on the sliding film using a wet film forming device. Through the above steps, the functional film 100 of the present invention can be obtained.

[0102] In the above manufacturing method, a method for manufacturing a functional film having a fine uneven structure 20B consisting of two-stage convex portions has been described. However, depending on the Mohs hardness of the inorganic material, a functional film having a fine uneven structure consisting of one-stage convex portions may be used. Furthermore, a fine uneven structure consisting of three or more stages of convex portions may be used. It may also be a functional film having a structure.

[0103] When producing a functional film having a fine uneven structure consisting of three-stage convex portions, the thickness of the metal mask used to form the first stage convex portions is preferably within a range of 20 to 100 nm, the thickness of the metal mask used to form the second stage convex portions is preferably within a range of 5 to 70 nm, and the thickness of the metal mask used to form the third stage convex portions is preferably within a range of 2 to 10 nm. Furthermore, the deposition temperature of the metal mask used to form the first stage convex portions is preferably within a range of 150 to 400°C, the deposition temperature of the metal mask used to form the second stage convex portions is preferably within a range of 100 to 400°C, and the deposition temperature of the metal mask used to form the third stage convex portions is preferably within a range of 100 to 400°C.

[0104] In addition, in the above manufacturing method, a metal mask is formed on an inorganic layer and then etched to form a fine uneven structure having a plurality of convex portions. However, the present invention is not limited to this method. For example, a metal mask may be formed on a substrate in advance, and an inorganic material may be deposited through the metal mask using a dry film forming device to form a fine uneven structure having a plurality of convex portions.

[0105] <Base material> The substrate on which the functional film of the present invention is formed is not particularly limited, and is preferably made of, for example, an inorganic material, an organic material, or a combination thereof. Inorganic materials include glass, fused silica glass, synthetic quartz glass, silicon, chalcogenides, etc. Organic materials include PET (polyethylene terephthalate), acrylic resin, vinyl chloride resin, cycloolefin polymer (COP), cycloolefin copolymer (COC), polymethyl methacrylate resin (PMMA), polycarbonate resin (PC), polypropylene (PP), polyethylene (PE), etc. UV-curable resins include radical polymerization type acrylate resin, urethane acrylate, polyester acrylate, polybutadiene acrylate, epoxy acrylate, silicone acrylate, amino resin acrylate, ene-thiol resin, cationic polymerization type vinyl ether resin, alicyclic epoxy resin, glycidyl ether epoxy resin, urethane vinyl ether, polyester vinyl ether, etc. Thermosetting resins include epoxy resin, phenolic resin, unsaturated polyester resin, urea resin, melamine resin, silicone resin, polyurethane, etc. The substrate may be an inorganic material such as glass on which a film made of an organic material is formed. In the present invention, when the functional film of the present invention is used in an optical device as described below, it is preferable to use glass as the substrate from the viewpoint of transparency. Also, when the functional film of the present invention is used in an inkjet head, it is preferable to use silicon as the substrate. Furthermore, when the functional film is used in a mold, it is preferable to use SiC, cemented carbide, etc. as the substrate.

[0106] <Reflectance Adjustment Layer Unit> At least one reflectance adjusting layer unit may be provided between the functional film of the present invention and the substrate. The reflectance adjusting layer unit will be described below. Fig. 14 is a cross-sectional view showing an example of a configuration in which a reflectance adjustment layer unit is provided between the functional film of the present invention and a substrate. As shown in Fig. 14, it is preferable that the reflectance adjustment layer unit U is provided on a substrate 1, and the functional film 100 of the present invention is provided thereon. Note that Fig. 14 and subsequent figures show an example in which the functional film 100 of the present invention has a fine concavo-convex structure 20A consisting of one-stage convex portions, but a fine concavo-convex structure consisting of two or more stage convex portions may also be used.

[0107] The reflectance adjusting layer unit includes a first reflectance layer unit composed of at least one low refractive index layer and at least one high refractive index layer, and a second reflectance layer unit composed of at least one low refractive index layer, one high refractive index layer, and It is preferable that the first reflectance adjustment layer unit has the second reflectance adjustment layer unit in this order, and further that in the first reflectance adjustment layer unit, the layer located farthest from the substrate is a photocatalytic layer containing a metal oxide having photocatalytic function, for example, TiO2.

[0108] FIG. 15 is a cross-sectional view showing an example of a configuration in which first and second reflectance adjustment layer units are provided between the functional film of the present invention and the substrate.

[0109] The configuration shown in FIG. 15 shows an example in which the reflectance control layer unit U shown in FIG. 14 is composed of a first reflectance adjustment layer unit 5 and a second reflectance adjustment layer unit 6. In the configuration shown in FIG.

[0110] (First reflectance adjustment layer unit 5) FIG. 16 is a cross-sectional view showing an example of a specific configuration of the first reflectance adjustment layer unit that constitutes the functional film shown in FIG.

[0111] An example of the configuration of the first reflectance adjustment layer unit 5 shown in FIG. 16 is composed of a first low refractive index layer 11A, a high refractive index layer 12, a second low refractive index layer 11B, and a photocatalytic layer 13 described below.

[0112] 1) First low refractive index layer 11A: Constituent material = SiO2, layer thickness = 22 nm 2) High refractive index layer 12: Constituent material = Ta2O5-TiO2, layer thickness = 18 nm 3) Second low refractive index layer 11B: Constituent material = SiO2, layer thickness = 33 nm 4) Photocatalyst layer 13: Constituent material = TiO2, layer thickness = 112 nm Next, each component of the first reflectance adjustment layer unit will be described in detail.

[0113] <First Low Refractive Index Layer and Second Low Refractive Index Layer> The first and second low refractive index layers according to the present invention are made of a material having a refractive index of less than 1.7, and in the present invention, the layer preferably contains SiO2 as a main component. However, it is also preferable that the layer contains other metal oxides, and a mixture of SiO2 and a portion of Al2O3, or MgF2, is also preferable from the viewpoint of light reflectance.

[0114] <High refractive index layer> In the present invention, the high refractive index layer is made of a material having a refractive index of 1.7 or higher, such as a mixture of Ta oxide and Ti oxide, or Ti oxide, Ta oxide, or a mixture of La oxide and Ti oxide. The metal oxide used in the high refractive index layer preferably has a refractive index of 1.9 or higher. In the present invention, Ta2O5 or TiO2 is preferred, and Ta2O5 is more preferred.

[0115] In the present invention, the thickness of the first reflectance adjusting layer unit composed of a high refractive index layer and a low refractive index layer is not particularly limited, but from the viewpoint of antireflection performance, it is preferably 500 nm or less, more preferably in the range of 50 to 500 nm. If the thickness is 50 nm or more, antireflection optical properties can be exhibited, and if the thickness is 500 nm or less, error sensitivity can be reduced and the yield rate of the lens's spectral characteristics can be improved.

[0116] <Photocatalyst layer> In the first reflectance adjustment layer unit according to the present invention, a preferred embodiment is one in which a photocatalytic layer having a photocatalytic function is provided as the outermost layer.

[0117] The photocatalytic layer according to the present invention is preferably made of TiO2 as a metal oxide having a photocatalytic function, which is preferable in that it has a high refractive index and can reduce the light reflectance of the dielectric multilayer film.

[0118] The "photocatalytic function" in this invention refers to the organic matter decomposition effect of the photocatalyst. When ultraviolet light is irradiated onto TiO2, which has photocatalytic properties, electrons are released, and then active oxygen and hydroxyl radicals (·OH radicals) are generated, which decompose organic matter with their strong oxidizing power. By adding a functional layer containing TiO2 to the dielectric multilayer film of this invention, it is possible to prevent organic matter adhering to optical components from contaminating the optical system as dirt.

[0119] Whether or not a material has a photocatalytic effect can be determined, for example, by irradiating a sample colored with a methylene blue ink pen with ultraviolet light at a cumulative dose of 20 J in an environment of 20°C and 80% RH, and evaluating the color change of the pen in stages.Specific photocatalytic performance test methods for self-cleaning by ultraviolet light irradiation include the methylene blue decomposition method (ISO 10678 (2010)) and the resazurin ink decomposition method (ISO 21066 (2018)).

[0120] In the present invention, it is preferable to form a reflectance adjustment layer unit on a substrate, the reflectance adjustment layer unit having, in this order, a first reflectance adjustment layer unit composed of at least one low refractive index layer and at least one high refractive index layer, and a second reflectance adjustment layer unit composed of a low refractive index layer, a high refractive index layer and a low refractive index layer, in which the layer of the first reflectance adjustment layer unit farthest from the substrate is a photocatalytic layer containing a metal oxide having photocatalytic function, and then form a functional film having a fine uneven structure of the present invention, as described below.

[0121] (Second reflectance adjustment layer unit) FIG. 17 shows an example of a specific configuration of the second reflectance adjustment layer unit.

[0122] In the present invention, the second reflectance adjustment layer unit 6 preferably has a configuration including at least a low refractive index layer, a high refractive index layer, and a salt spray prevention layer. The configuration example of the second reflectance adjustment layer unit 6 shown in FIG. 17 shows an example of a configuration in which the following constituent layers (five layers) are stacked from the bottom (substrate side).

[0123] 1) Low refractive index layer 7A: Constituent material = SiO2, layer thickness = 28 nm 2) High refractive index layer 8: constituent material = TiO2, layer thickness = 1 nm 3) Low refractive index layer 7B: Constituent material = SiO2, layer thickness = 30 nm 4) Salt spray protection layer 15: constituent material = TiO2, layer thickness = 1 nm 5) Low refractive index layer 7B: Constituent material = SiO2, layer thickness = 3 nm The salt spray protective layer here refers to a layer that has the function of preventing damage to the lower layer caused by salt water in a salt spray test.

[0124] By providing the second reflectance adjustment layer unit between the first reflectance adjustment layer unit and the functional film, the average light reflectance of the functional film can be controlled to a desired condition, for example, 3.0% or less, even while providing a photocatalytic layer. In addition, when a photocatalytic layer is provided, it is preferable to form the convex portion by etching down to the photocatalytic layer.

[0125] (Method of forming layers constituting reflectance control layer units) (Method for forming salt spray protective layer) There are no particular restrictions on the method for forming the first reflectance adjustment layer unit consisting of a low refractive index layer and a high refractive index layer, and the second reflectance adjustment layer unit consisting of a low refractive index layer, a high refractive index layer, and a salt spray protection layer, but a dry film formation method is preferred.

[0126] Dry film formation methods applicable to the present invention include vacuum deposition and ion beam deposition. Examples of the sputtering method include the ion beam deposition method and the ion plating method, and the sputtering method, the ion beam sputtering method and the magnetron sputtering method, among which the above-mentioned ion-assisted deposition method (IAD method) or the sputtering method is preferred.

[0127] [Applications of functional membranes] <Optical devices> The functional film of the present invention is a functional film that combines abrasion resistance and super-water repellency, and the present invention is an optical device comprising the functional film of the present invention. Furthermore, the optical device is preferably a lens, a lens cover glass, an antibacterial cover member, an antifungal coating member, or a mirror, and is suitable for use in, for example, in-vehicle lenses, communication lenses, antibacterial lenses for endoscopes, components and antibacterial covers for PCs and smartphones, eyeglasses, ceramics such as toilets and tableware, antifungal coatings for baths and sinks, or building materials (window glass), and is particularly suitable as an in-vehicle lens. Furthermore, in the optical device to which the functional film of the present invention is applied, the substrate is preferably glass from the viewpoint of transparency, and the inorganic substance contained as the main component in the functional film is preferably SiO2, a Si-containing material, from the viewpoint that reaction products with fluorine gas are easily produced and etching is easy.

[0128] <Inkjet head> The functional film of the present invention can also be applied to an inkjet head, that is, the inkjet head of the present invention includes the functional film. In addition, in the inkjet head to which the functional film of the present invention is applied, the substrate is preferably silicon from the viewpoint of durability and processing characteristics, and the inorganic substance contained as the main component in the functional film is preferably SiC from the viewpoint of ink wiping ability.

[0129] <Mold> The functional film of the present invention can also be applied to a mold. That is, the mold of the present invention includes the functional film. Furthermore, from the viewpoint of strength, it is preferable that the base material of the mold to which the functional film of the present invention is applied is SiC or cemented carbide, and the inorganic substance contained as the main component in the functional film is preferably SiC, a Si-containing material, from the viewpoints of ease of forming reaction products with fluorine gas, ease of etching, and hardness. [Example]

[0130] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively.

[0131] [Production of functional membrane 1] <Preparing the substrate> As the substrate, a white glass substrate (refractive index: 1.523) manufactured by SCHOTT was prepared.

[0132] <Deposition of inorganic layer 1> On the substrate, an inorganic layer 1 containing SiO2 (SiO2 layer) was formed under the following conditions. (Chamber conditions) Heating temperature: 370℃ Starting vacuum degree: 5.0×10 -3 Pa (evaporation source of film forming material) electron gun (IAD ion source) Synchron RF ion source NIS-175-3 Inorganic layer deposition material: SiO2 (Canon Optron Inc. product name SiO2) The substrate was placed in an IAD vacuum deposition apparatus, and SiO2 was loaded into the first evaporation source as a film-forming material. Vapor deposition was carried out at a film-forming rate of 3 Å / sec to form an inorganic layer 1 (SiO2 layer) with a thickness of 360 nm. The IAD conditions were an acceleration voltage of 1000 V, an acceleration current of 1000 mA, a suppressor voltage of 500 V, and a neutralization current of 1500 mA, and the IAD introduced gases were O 250 sccm, Ar gas 0 sccm, and neutral gas Ar 10 sccm.

[0133] <First deposition of Ag mask> An Ag mask was deposited on the deposited inorganic layer. For the deposition of the Ag mask, a deposition apparatus (BMC-800T, manufactured by Synchron Corporation) was used, and deposition was carried out under the following conditions to form an Ag mask. The thickness of the Ag mask was 30 nm. Heating temperature: 370 °C Initial vacuum degree: 1.33×10 -3 Pa Deposition rate: 3 Å / sec

[0134] <First etching> After forming the Ag mask, as an etching apparatus, CE-300I (manufactured by Ulvac) was used, and etching was carried out under the following conditions. By changing the etching time, the average diameter L and average height h of the convex portions were adjusted. Antenna RF: 400 W Bias RF: 38 W APC pressure: 0.5 Pa CHF3 flow rate: 20 sccm Total etching time: 160 seconds In addition, when the sample was heated, etching was carried out while cooling in multiple stages so that the total etching time became 160 seconds as described above. In this way, the first-stage convex portions were formed.

[0135] <First peeling of Ag mask> After forming the first-stage convex portions, the sample was immersed in Pure Etch Au100 (Hayashi Junyaku Co., Ltd.) for 5 seconds to peel off the Ag mask. Then, it was washed with pure water and cleaned in a UV ozone apparatus (Technovision Co., Ltd.) for 600 seconds. After forming the first-stage convex portions in this way, an electron micrograph was taken using a scanning electron microscope, and the result is shown in Fig. 18A.

[0136] <Second deposition of Ag mask> In the above-mentioned "First deposition of Ag mask", an Ag mask was formed on the first-stage convex portions in the same manner except that the thickness of the Ag mask was changed to 15 nm.

[0137] <Second etching> After forming the Ag mask, as an etching apparatus, CE-300I (manufactured by ULVAC) was used, and film formation was performed under the following conditions. By changing the etching time, the average diameter L and average height h of the convex portions were adjusted. Antenna RF: 400 W Bias RF: 38 W APC pressure: 0.5 Pa CHF3 flow rate: 20 sccm Total etching time: 40 seconds In addition, when the sample was heated, etching was performed while cooling it in multiple steps so that the total etching time became 40 seconds as described above. In this way, the second-stage convex portions were formed.

[0138] <Second peeling of Ag mask> After forming the second-stage convex portions, the Ag mask was peeled off by the same procedure as the above-described "First peeling of Ag mask", washed with pure water, and cleaned with a UV ozone apparatus. After forming the second-stage convex portions in this way, an electron micrograph was taken using a scanning electron microscope, and the result is shown in FIG. 18B. Also, the binary data at this time is shown in FIG. 18C.

[0139] <Formation of water-repellent film> After forming the second-stage convex portions, the sample was cleaned for 600 s with a UV ozone apparatus (manufactured by Technovision), and then 100 μL of Fluorosurf (manufactured by Fluoro Technology) was spin-coated under the condition of a rotation speed of 3000 rpm, and then dried at room temperature for 24 hours to form a water-repellent film. Thus, the functional film 1 was obtained.

[0140] [Manufacture of functional film 2] In the manufacture of the functional film 1, the functional film 2 was manufactured in the same manner except that the thickness of the Ag mask was changed as shown in Table II below. Regarding the functional film 2, SEM photographs after the formation of the first-stage convex portions are shown in Fig. 19A, SEM photographs after the formation of the second-stage convex portions are shown in Fig. 19B, and the binarized data of Fig. 19B are shown in Fig. 19C.

[0141] [Manufacture of Functional Film 3] In the manufacture of the functional film 1, after the second peeling of the Ag mask, the following "third film formation of the Ag mask", "third etching", and "third peeling of the Ag mask" were performed, and the thickness, film formation temperature, total etching time, etc. of the Ag mask in the first and second times were changed as shown in Table II below. Further, after the third peeling of the Ag mask, the following sliding film was formed, and then the functional film 3 was manufactured in the same manner except that a water-repellent film similar to the water-repellent film in the functional film 1 was formed. Regarding the functional film 3, SEM photographs after the formation of the first-stage convex portions are shown in Fig. 20A, SEM photographs after the formation of the second-stage convex portions are shown in Fig. 20B, SEM photographs after the formation of the third-stage convex portions are shown in Fig. 20C, and the binarized data of Fig. 20C are shown in Fig. 20D.

[0142] <Third Film Formation of Ag Mask> In the above-mentioned "first film formation of the Ag mask", an Ag mask was formed on the convex portions of the second stage in the same manner except that the film was formed at 300 °C so that the thickness of the Ag mask was 5 nm.

[0143] <Third Etching> After forming the Ag mask, as an etching apparatus, CE-300I (manufactured by ULVAC) was used, and film formation was performed under the following conditions. By changing the etching time, the average diameter L and average height h of the convex portions were adjusted. Antenna RF: 400 W Bias RF: 38 W APC Pressure: 0.5 Pa CHF3 Flow Rate: 20 sccm Total Etching Time 30 Seconds In addition, when the sample was heated, etching was performed while cooling in multiple steps so that the total etching time was 30 seconds as described above. In this way, the convex portions of the third stage were formed.

[0144] <Third peeling of Ag mask> After forming the convex portion in the third stage, the Ag mask was peeled off in the same procedure as the above-mentioned "First peeling of Ag mask", washed with pure water, and cleaned with a UV ozone apparatus.

[0145] <Formation of sliding film> After peeling off the Ag mask, the following film-forming material was loaded using a film-forming apparatus (BMC-800T, manufactured by Synchrotron Co., Ltd.), and EB evaporation was performed at a film-forming rate of 1 Å / sec to form a 2-nm sliding film. Film-forming material for sliding film: Ta2O5-TiO2 (trade name OA-6 00) Performed under heating conditions of 370 °C.

[0146] [Manufacture of functional film 4] In the manufacture of the functional film 1, the "film formation of inorganic layer 1" was changed to the "film formation of inorganic layer 2" shown below, and the total etching time for the first and second times was changed as shown in Table II below. Furthermore, after the second peeling of the Ag mask in the same manner as the manufacture of the functional film 3, a sliding film was formed, and then a water-repellent film was formed, and the functional film 4 was manufactured in the same manner except for this. Also, for the functional film 4, a SEM photograph after forming the convex portion in the second stage is shown in Fig. 21.

[0147] <Film formation of inorganic layer 2> An inorganic layer 2 (SiC layer) containing SiC was formed on the Si substrate under the following conditions. (Chamber conditions) Upper electrode: 100 °C, 0 W Lower electrode: 100 °C, 500 W Initial vacuum degree: 15 Pa (Film-forming material) Tetramethylsilane (manufactured by Yamana Khyutech Co., Ltd.) 50 sccm Using a CVD apparatus (PE-CVD apparatus) of YOUTEC, while supplying 50 sccm of tetramethylsilane, film formation was performed for 130 seconds under the above chamber conditions to form an inorganic layer 2 (SiC layer) with a thickness of 250 nm.

[0148] [Production of functional film 5] Functional film 5 was produced in the same manner as in producing functional film 4, except that the total etching time was changed as shown in Table II below. In addition, regarding the functional film 5, an SEM photograph after the formation of the first step of convex portions is shown in FIG. 22A, and an SEM photograph after the formation of the second step of convex portions is shown in FIG. 22B.

[0149] [Production of functional membrane 6] Functional film 6 was produced in the same manner as in the production of functional film 4, except that "deposition of inorganic layer 2" was changed to "deposition of inorganic layer 3" shown below, and the thickness of the Ag mask for the first and second etchings and the total etching time were changed as shown in Table II below. The etching apparatus used was as shown below. In addition, regarding the functional film 6, an SEM photograph after the formation of the first step of convex portions is shown in FIG. 23A, and an SEM photograph after the formation of the second step of convex portions is shown in FIG. 23B.

[0150] <Deposition of inorganic layer 3> An inorganic layer 3 (SiOC layer) containing SiOC was formed on the above-mentioned white glass substrate under the following conditions. (Chamber conditions) Upper electrode: 100℃, 0W Lower electrode: 100℃, 500W Starting vacuum degree: 15Pa (film forming materials) Tetramethylsilane (Yamanaka Hewtech Co., Ltd.) 50sccm Adeka Super TMS (ADEKA) 50sccm Using a YOUTEC CVD apparatus (PE-CVD apparatus), tetramethylsilane and Adeka Super TMS were supplied at 50 sccm each under the above chamber conditions for 130 seconds to form an inorganic layer 3 (SiOC layer) with a thickness of 250 nm.

[0151] <First etching> After the first Ag mask film formation, a BIG Cube (manufactured by YOUTEC) was used as an etching device to form a film under the following conditions. Antenna RF: 120W APC pressure: 3.0Pa CHF3 flow rate: 20sccm Total etching time: 3000 seconds In addition, when the sample was heated, etching was performed in several steps while cooling, so that the total etching time was 3000 seconds as described above. In this way, the first protrusion was formed.

[0152] <Second etching> After the second Ag mask film formation, a BIG Cube (manufactured by YOUTEC) was used as an etching device, and film formation was carried out under the following conditions. Antenna RF: 120W APC pressure: 3.0Pa CHF3 flow rate: 20sccm Total etching time: 1200 seconds In addition, when the sample was heated, etching was performed in several steps while cooling, so that the total etching time was 1200 seconds as described above. In this way, the second protrusion was formed.

[0153] [Production of functional membrane 7] Functional film 7 was produced in the same manner as in the production of functional film 2, except that "deposition of inorganic layer 1" was changed to "deposition of inorganic layer 4" shown below and the total time for the first etching was changed as shown in Table II below. Furthermore, in the same manner as in the production of functional film 3, after the first peeling of the Ag mask, a sliding film was formed, and then a water-repellent film was formed. Furthermore, for the functional film 7, an SEM photograph after the formation of the first stage of convex portions is shown in FIG. 24A, and binarized data is shown in FIG. 24B.

[0154] <Deposition of inorganic layer 4> (Chamber conditions) Upper electrode: 250℃, 0W Lower electrode: 250℃, 500W Starting vacuum degree: 15Pa (film forming materials) Hexamethyldisilazane (Kanto Chemical): 5 sccm Adeka Super TMS (ADEKA): 50sccm Using a YOUTEC CVD device (PE-CVD device), hexamethyldisilazane and Adeka Super TMS were supplied at 5 and 50 sccm, respectively, and an inorganic layer 4 (SiCN layer) was formed for 130 seconds under the above chamber conditions. The film thickness was 250 nm.

[0155] [Production of functional membrane 8] Functional film 8 was produced in the same manner as in the production of functional film 1, except that the thickness of the Ag mask, the film formation temperature, and the total etching time were changed as shown in Table II below. The etching apparatus used was the BIG Cube (manufactured by YOUTEC) used in the production of functional film 6, and the etching conditions other than the total etching time were the same as for functional film 6. In addition, a sliding film and a water-repellent film similar to those of functional film 3 were also formed. Regarding the functional film 8, an SEM photograph after the formation of the first-stage projections is shown in FIG. 25A, and an SEM photograph after the formation of the second-stage projections is shown in FIG. 25B.

[0156] [Production of functional membrane 9] In the production of functional film 8, the thickness of the Ag mask, the film formation temperature, and the total etching time were changed as shown in Table II below, and functional film 9 was produced in the same manner except that no water-repellent film was formed. Regarding the functional film 9, an SEM photograph after the formation of the first convex portion is shown in FIG. 26A, an SEM photograph after the formation of the second convex portion is shown in FIG. 26B, and the binarized data of FIG. 26B is shown in FIG. 26C.

[0157] [Production of functional film 10] A functional film 10 was produced in the same manner as in the production of the functional film 9, except that a sliding film was not formed. The SEM photographs of this functional film 10 after the formation of the first convex portion, the SEM photographs of the functional film 10 after the formation of the second convex portion, and the binarized data are the same as those in Figures 26A to 26C, due to the difference in the presence or absence of the functional film 9 and the sliding film.

[0158] [Production of Functional Film 11] (Comparative Example 1) In the production of the functional film 1, inorganic layer 1 (SiO2 layer) was formed on a white glass substrate, and the thickness of the first Ag mask, the Ag mask formation temperature, and the total etching time were changed as shown in Table II below. Furthermore, functional film 11 was produced in the same manner as in the production of functional film 3, except that after the first Ag mask peeling, a sliding film was formed, and then a water-repellent film was formed. 27A shows an SEM photograph of the functional film 11 after the formation of the first protrusion, FIG. 27B shows the binarized data, and FIG. 27C shows an SEM photograph of the functional film 11 after abrasion. As shown in FIG. 27C, it can be seen that the first protrusion is broken after abrasion.

[0159] [Production of functional film 12] (Comparative Example 2) In the production of the functional film 1, an inorganic layer 1 (SiO2 layer) was formed on a white glass substrate, and then a sliding film similar to the functional film 3 was formed without performing the Ag mask film formation or etching process, thereby producing the functional film 12.

[0160] [Table 2]

[0161] For the functional film obtained above, the total average height H, the average height h of the topmost convex portion, the average diameter of the first to third convex portions, and the surface area ratio were calculated by the following method and are shown in the table below. Furthermore, the ratio of the major axis diameter to the minor axis diameter of the convex portions (major axis diameter / minor axis diameter) was calculated. was also calculated. The Mohs hardness of the inorganic materials contained in the inorganic material layer is as shown in Table III below.

[0162] <Total average height> The total average height H was calculated by image analysis using an atomic force microscope (AFM) as described above. Alternatively, it may be calculated by observing the cross section of the convex portion with an electron microscope as described above.

[0163] <Average height of the topmost convex part> The average height h of the topmost convex portion was calculated by image analysis using an atomic force microscope (AFM) as described above. Alternatively, it may be calculated by observing the cross section of the convex portion with an electron microscope as described above.

[0164] <Average diameter of the first to third convex sections> The average diameter of the first to third protrusions when the microrelief structure was viewed from above was calculated using the free image processing software "ImageJ (ImageJ1.32S created by Wayne Rasband)" after photographing the image using an electron microscope as described above. The average diameter of the first protrusion was calculated before the second protrusion was formed, and the average diameter of the second protrusion was also calculated before the third protrusion was formed.

[0165] <Surface area ratio of the 1st to 3rd protrusions> The ratio of the surface area of each of the first to third protrusions to the surface area of the entire microrelief structure when viewed from above was calculated by taking a photograph using an electron microscope and then using the image processing software "ImageJ (ImageJ 1.32S created by Wayne Rasband)." Here, the "ratio of the surface area of the first protrusion" refers to the ratio of the surface area of the first protrusion before the second protrusion is formed on the first protrusion. Similarly, when the third protrusion is formed on the second protrusion, the "ratio of the surface area of the second protrusion" refers to the ratio of the surface area of the second protrusion before the third protrusion is formed.

[0166] <Ratio of major axis diameter to minor axis diameter of the convex part> The major axis diameter and minor axis diameter were calculated for at least 10 random convex portions in each step, such as the first step, second step, and third step. Specifically, similar to the "method for calculating the average diameter of convex portions in the top step" described above, the microrelief structure was observed with an SEM, and the diameter (major axis diameter) of the smallest circumscribing circle C1 of the convex portions and the diameter (minor axis diameter) of the largest inscribing circle C2 of the convex portions were measured. The ratio of the major axis diameter to the minor axis diameter was calculated from these measurement results, and the maximum of these was taken as the ratio of the major axis diameter to the minor axis diameter of this functional film.

[0167] [evaluation] The functional film obtained above was evaluated as follows. <Initial water contact angle> Using a contact angle measuring device G-1 manufactured by Elma, 10 μL of pure water was dropped onto the functional film under an environment of 23°C and 50% RH, and the static contact angle was measured 5 seconds after the drop. This was taken as the initial water contact angle. A water contact angle of 110° or more was considered acceptable for practical use.

[0168] <Water contact angle after abrasion> Bemcot Clean Wipe P (Asahi Kasei Corporation) was used, 250 g / cm 2 20 with a load of The film was abraded 0 times. The weight was measured on a general electronic balance, and the abrasion treatment was performed by manual polishing. After that, 10 μL of pure water was dropped onto the functional film in an environment of 23°C and 50% RH using a contact angle measuring device G-1 (manufactured by Elma Co.), and the static contact angle was measured 5 seconds after the drop, and this was taken as the water contact angle after abrasion. A difference (deterioration) of 10° or less between the initial water contact angle and the water contact angle after abrasion is considered to be a practical problem. I loved it.

[0169] <Initial clouding characteristics> In an environment of 25°C and 50% RH, the sample surface was photographed as a video using an optical microscope (VH-Z100R, manufactured by Keyence Corporation) with a 500x optical lens and evaluated. Specifically, the degree of condensation was compared by spraying water vapor at 35°C and 90% RH onto the surface of the resulting functional film using a 6.35 mm diameter tube. Photographs of the condensation were taken from the start of spraying, and the video was frozen 3 seconds later, and a screenshot was taken to create a comparison photograph. The aforementioned ImageJ software was used for image processing, and the percentage (%) of the area occupied by water particles on the entire screen was calculated. The binarization was performed so that the water particles (droplets) appeared black. It was determined that a ratio of this area of 50% or less would be acceptable for practical use. Incidentally, the initial fogging characteristics and the fogging characteristics after abrasion described below were evaluated only for the functional films 10, 11 and 13. FIG. 28 is a diagram showing the evaluation of the initial cloudiness characteristics of the functional film 9, where FIG. 28A is an image taken by an electron microscope and FIG. 28B is binarized data. 29A and 29B show an image of the functional film 10 photographed by an electron microscope and binarized data, and FIGS. 30A and 30B show an image of the functional film 12 photographed by an electron microscope and binarized data.

[0170] <Fog characteristics after wear> Bemcot Clean Wipe P (Asahi Kasei Corporation) was used, 250 g / cm 2 20 with a load of The sample was abraded 0 times. The weight was measured on a standard electronic balance, and the abrasion treatment was performed by hand polishing. After that, water vapor was sprayed onto the sample, and the image was processed in the same manner as in the evaluation method for "initial fogging characteristics" described above, and the percentage (%) of the area occupied by water particles on the entire screen was calculated. It was determined that a ratio of this area of 60% or less would be acceptable for practical use.

[0171] <Initial average reflectance> The average reflectance of the functional film in the wavelength range of 420 to 670 nm was measured using a USPM-RU, a micro-area spectral reflectance measuring device manufactured by Olympus Corp. An initial average reflectance of 1.69% or less was considered practically preferable.

[0172] <Average reflectance after abrasion> Bemcot Clean Wipe P (Asahi Kasei Corporation) was used, 250 g / cm 2 20 with a load of The film was abraded 0 times. The weight was measured on a standard electronic balance, and the abrasion treatment was performed by manual polishing. Thereafter, the average reflectance of the functional film in the wavelength range of 420 to 670 nm was measured in the same manner as in the evaluation method for "initial average reflectance" described above. An average reflectance of 3.0% or less after abrasion was considered practically preferable.

[0173] [Table 3]

[0174] As is clear from the above results, the functional film of the present invention has a lower average reflectance and superior optical performance than the functional film of the comparative example, and is also capable of achieving both abrasion resistance and super-water repellency. Furthermore, comparing the functional film 10 with the functional film 12, it is found that the fine uneven structure of the present invention provides an anti-fogging effect. In particular, the provision of a sliding film is effective in preventing fogging. [Industrial Applicability]

[0175] The present invention relates to optical devices, inkjet heads, and molds, and in particular to a functional film that is both abrasion resistant and super water repellent and that can be mass-produced, a method for manufacturing the functional film, and optical devices, inkjet heads, and molds that include the functional film. [Explanation of symbols]

[0176] 1 Base material 2 Inorganic layer 3, 4 Metal mask 20A Micro-relief structure with one-step convex part 20B Micro-relief structure with two-step convex portions 21 First step convex part 22 Second ridge 21b Bottom surface of the first protrusion 22a The outermost surface of the second convex part 22b Bottom of the second convex part 100 Functional membranes H Total average height h Average height of the topmost convex part 5. First reflectance adjustment layer unit 6. Second reflectance adjustment layer unit 7A, 7B Low refractive index layer 8, 12 High refractive index layer 11A First low refractive index layer 11B Second low refractive index layer 13 Photocatalyst layer 15 Salt spray barrier

Claims

1. A functional film containing an inorganic substance as a main component and having a fine uneven structure on its surface, In a vertical cross section in the film thickness direction, the plurality of convex portions constituting the fine concave-convex structure are formed in a step-like shape with a plurality of steps, and When the Mohs hardness of the inorganic material is X and the number of steps of the convex portion is an integer Y, the following formula (I) is satisfied: the average height from the bottom surface of the lowest protrusion to the top surface of the highest protrusion is 1 μm or less; When the fine concave-convex structure is viewed from above, among the plurality of convex portions, a first-stage convex portion has a mesh shape, and The functional film, wherein the inorganic material is SiO 2 , SiOC or SiCN. Formula (I): 10≦X×Y

2. A functional film containing an inorganic substance as a main component and having a fine uneven structure on its surface, In a vertical cross section in the film thickness direction, the plurality of convex portions constituting the fine concave-convex structure are formed in a step-like shape with a plurality of steps, and When the Mohs hardness of the inorganic material is X and the number of steps of the convex portion is an integer Y, the following formula (I) is satisfied: the average height from the bottom surface of the lowest protrusion to the top surface of the highest protrusion is 1 μm or less; When the fine uneven structure is viewed from above, the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) of the first-stage convex portions among the plurality of convex portions is within a range of 2.0 to 6.2, and The functional film, wherein the inorganic material is SiO 2 , SiOC or SiCN. Formula (I): 10≦X×Y

3. When the fine uneven structure is viewed from above, the average diameter of the convex portions of the uppermost stage is within a range of 10 to 500 nm, a ratio of the surface area of the uppermost projection to the surface area of the entire microrelief structure is within a range of 30 to 70%, and 3. The functional film according to claim 1, wherein in a vertical cross section of the fine uneven structure, the average height from the bottom surface of the uppermost convex portion to the outermost surface of the uppermost convex portion is within a range of 10 to 250 nm.

4. 4. The functional film according to claim 1, wherein the mutual positional relationship and shape of the plurality of convex portions are random and have no regularity in terms of identity or periodicity.

5. 5. The functional film according to claim 1, wherein the inorganic substance contains an inorganic substance having a Mohs hardness of 9 or more.

6. The main component of the inorganic material is silicon dioxide, The functional film according to claim 1 , wherein the integer Y is 2.

7. The functional film according to any one of claims 1 to 6, wherein the convex portion is provided with a sliding film.

8. The functional film according to claim 1 , wherein the convex portion is provided with a film containing a water-repellent material.

9. The contact angle of water at 25°C is 130 degrees or more, Bemcot Clean Wipe P (manufactured by Asahi Kasei Corporation) was used, and the pressure was 250 g / cm ２ 20 with a load of 9. The functional film according to claim 1, wherein the deterioration of the contact angle after 00 abrasions is 10 degrees or less.

10. A method for producing a functional film according to any one of claims 1 to 9, comprising: A method for manufacturing a functional film, wherein the fine uneven structure is formed through a process of forming a metal mask on an inorganic layer and processing the inorganic layer by dry etching.

11. The method for producing a functional film according to claim 10, further comprising the steps of forming the metal mask and processing it by dry etching at least twice.

12. An optical device comprising the functional film according to any one of claims 1 to 9.

13. An inkjet head comprising the functional film according to any one of claims 1 to 9.

14. A mold comprising the functional film according to any one of claims 1 to 9.

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