JP7514751B2 - Antifouling structure and automobile part having the same - Google Patents

Description

The present invention relates to an antifouling structure and an automobile part having the same.

When a finger touches the surface of an object, sebum (fingerprints) adheres to it. In an automobile, sebum on the instrument panel, console, doorknob, etc. reduces the design and leaves an unpleasant impression. Furthermore, sebum on the rearview mirror, room mirror, and display screen of a car navigation system reduces visibility. Therefore, there is a demand for providing the surfaces of these objects with anti-fouling properties (fingerprint resistance).

Patent Document 1 describes how the fine uneven structure made of a material containing a fluorine-containing compound makes it difficult for sebum to adhere to the surface, and even if it does adhere, the oil droplets are broken down into fine particles, making the dirt less noticeable.

International Publication No. 2013/008645

However, even the technology described in Patent Document 1 may not be able to provide sufficient stain resistance to articles, and further improvements are desired.

Therefore, the present invention aims to provide a means for improving the stain resistance of articles.

The inventors of the present invention conducted extensive research to solve the above problems. As a result, they discovered that the above problems could be solved by laminating a porous layer having pores of a specific size and a modified layer on the surface of a substrate having a specific uneven structure, and by retaining an antifouling liquid on the surface of the modified layer, thus completing the present invention.

That is, one aspect of the present invention is an antifouling structure having a substrate having an uneven structure with a surface roughness (Rz) of 0.30 μm or more and 1.25 μm or less, a porous layer having pores with an average opening diameter of 200 nm or less formed on the surface of the uneven structure of the substrate, a modified layer formed on the surface of the porous layer, and an antifouling liquid held on the surface of the modified layer.

The present invention provides a means for improving the stain resistance of an article.

1 is a cross-sectional view of an antifouling structure according to one embodiment of the present invention cut in the lamination direction (thickness direction). FIG. 2 is an enlarged view of the antifouling layer in FIG. 1A to 1C are diagrams for explaining the antifouling function of an antifouling structure according to one embodiment of the present invention.

<Anti-fouling structure>
One aspect of the present invention is an antifouling structure comprising a substrate having an uneven structure with a surface roughness (Rz) of 0.30 μm or more and 1.25 μm or less, a porous layer having pores with an average opening diameter of 200 nm or less formed on the surface of the uneven structure of the substrate, a modified layer formed on the surface of the porous layer, and an antifouling liquid held on the surface of the modified layer. Note that in this specification, the porous layer, the modified layer, and the antifouling liquid film made of the antifouling liquid are collectively referred to as the "antifouling layer".

The antifouling structure according to this embodiment can reduce the contact area between the antifouling structure and a finger due to the macro uneven structure on the substrate surface. This can reduce the amount of sebum remaining on the antifouling liquid film when the finger is removed, improving the antifouling properties of the article.

Below, an embodiment of the present invention will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description of the claims, and is not limited to the following embodiments. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation, and may differ from the actual ratios.

Figure 1 is a cross-sectional view of an antifouling structure according to one embodiment of the present invention cut in the lamination direction (thickness direction). As shown in Figure 1, the antifouling structure 10 according to this embodiment has an antifouling layer 2 on the surface of a substrate 1 having a macroscopic uneven structure. Figure 2 is an enlarged view of the antifouling layer 2 in Figure 1. As shown in Figure 2, the antifouling layer 2 is composed of a porous layer 3 having fine pores, a modified layer 4 formed on the surface of the porous layer 3, and an antifouling liquid film 5 consisting of an antifouling liquid present on the outermost surface. Although not shown, the antifouling liquid may be present not only in the antifouling liquid film 5 but also in the pores of the porous layer 3 and inside the modified layer 4.

Figure 3 is a diagram for explaining the antifouling function of an antifouling structure according to one embodiment of the present invention. Generally, when sebum attached to a finger comes into contact with an antifouling liquid and then separates, the antifouling liquid, which has a smaller surface tension, is dragged by the sebum and is separated on the antifouling liquid side. As a result, some of the antifouling liquid adheres to the sebum side. Meanwhile, due to gravity and the cohesive force with the antifouling liquid, a small amount of sebum remains on the antifouling liquid side. According to the present invention, as shown in Figure 3, an antifouling layer 2 is formed on a substrate 1 having a macroscopic uneven structure, so that the contact area between the sebum 6 and the antifouling liquid film 5 is reduced. This reduces the influence of gravity and the cohesive force with the antifouling liquid, and the remaining sebum can be further suppressed, thereby improving the antifouling properties.

[Base material]
The substrate plays a role in maintaining the structure of the antifouling structure. The material constituting the substrate is not particularly limited, and glass, metal, plastic, ceramic, wood, stone, and composite materials combining these materials can be appropriately adopted. Among them, it is preferable to use a transparent substrate such as glass or transparent plastic as the substrate material. That is, in a preferred embodiment of the antifouling structure of the present invention, the substrate is a transparent substrate. Such an antifouling structure can be suitably used for imparting antifouling properties to mirrors, display screens of image display devices, and the like. In this specification, a transparent substrate refers to a substrate having a visible light transmittance of 80% or more at a wavelength of 550 nm.

The substrate has an uneven structure with a surface roughness (Rz) of 0.30 μm or more and 1.25 μm or less. The surface roughness (Rz) is preferably 0.50 μm or more and 1.10 μm or less, and more preferably 0.70 μm or more and 1.00 μm or less. If the surface roughness (Rz) is less than 0.30 μm, the uneven structure is too small, and the contact area between sebum and the anti-soiling liquid film cannot be sufficiently reduced, and the remaining sebum may not be suppressed. If the surface roughness (Rz) exceeds 1.25 μm, the design of the anti-soiling structure may be reduced. In addition, when a transparent substrate is used as the substrate and the anti-soiling structure is applied to a display screen as described above, the haze of the anti-soiling structure may be high (exceeding 5%), and sufficient visibility may not be obtained. In this specification, the surface roughness (Rz) is a value obtained by the measurement method described in the examples.

A substrate having this surface roughness (Rz) can be manufactured by using a conventional method, such as etching the surface of the material or coating the surface with a coating liquid containing fine particles and a matrix, followed by hardening the matrix.

[Porous layer]
The porous layer has a so-called sponge-like structure in which a plurality of pores are interconnected and randomly arranged in a three-dimensional manner, and retains the antifouling liquid within the pores and/or on the surface.

The porous layer is preferably made of a metal oxide containing silicon oxide as a main component. When the porous layer is made of a metal oxide containing silicon oxide with high hardness, the sliding resistance is improved, and the durability of the antifouling structure can be improved. In addition, such a porous layer made of a metal oxide can be formed using a conventionally known method, such as a sol-gel method.

Examples of the metal oxide constituting the porous layer include quartz glass, soda glass, borosilicate glass, and the like, which contain 60 mass % or more of silicon oxide (SiO ₂ ).

The average opening diameter of the pores is 200 nm or less, preferably 10 nm or more and 200 nm or less, more preferably 20 nm or more and 180 nm or less, even more preferably 50 nm or more and 150 nm or less, and particularly preferably 70 nm or more and 120 nm or less. If the average opening diameter exceeds 200 nm, the antifouling liquid may volatilize at high temperatures, and sufficient durability may not be obtained. If the average opening diameter is 10 nm or more, the modified layer described below is well formed in the pores, and a sufficient amount of antifouling liquid can be retained. In this specification, the average opening diameter is the value obtained by the measurement method described in the examples.

The average opening diameter of the pores can be controlled, for example, by adjusting the amount of acid or base used during hydrolysis and polycondensation in the sol-gel method. Specifically, by increasing the amount of acid or base, the gel size increases, and pores with a large average opening diameter can be formed.

The average thickness of the porous layer is preferably 50 nm or more and 1000 nm or less, and more preferably 100 nm or more and 500 nm or less. When the average thickness is 50 nm or more, the antifouling liquid can be sufficiently retained, and the durability of the antifouling structure can be improved. Furthermore, when the average thickness is 1000 nm or less, the occurrence of cracks due to volume shrinkage, etc., when the porous layer is formed can be prevented. The average thickness of the porous layer can be adjusted, for example, by the dilution ratio (viscosity) of the coating solution used when forming the porous layer, the coating speed, etc.

[Modified layer]
The modified layer has the role of increasing the retention of the antifouling liquid. In addition, the modified layer can form a smooth surface (antifouling liquid film) made of the antifouling liquid on its surface. Even if the antifouling liquid is pushed aside by the pressure of a contacted object such as a finger, the presence of the modified layer can prevent the adhesion of sebum.

The modified layer is preferably formed from a material having affinity for the antifouling liquid, and is preferably formed from a modifier containing at least one type selected from the group consisting of perfluoroether group-containing compounds and perfluoroalkyl group-containing compounds. That is, in a preferred embodiment of the antifouling structure of the present invention, the modified layer is formed by bonding the bonding portion of at least one type of modifier selected from the group consisting of perfluoropolyether group-containing compounds and perfluoroalkyl group-containing compounds to the porous layer.

Perfluoroether group-containing compounds include perfluoroether alkoxysilanes, such as OPTOOL (registered trademark) DSX manufactured by Daikin Industries, Ltd., which are commercially available.

Perfluoroalkyl group-containing compounds include perfluoroalkylalkoxysilanes, specifically tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, etc.

The fluorine content of the modified layer is preferably 38 mol% or more and 60 mol% or less, and more preferably 44 mol% or more and 60 mol% or less. If the fluorine content is within the above range, even if the antifouling liquid is pushed aside by pressing, the presence of the modified layer makes it possible to prevent adhesion of sebum. The fluorine content can be controlled by the type of modifier used. In this specification, the fluorine content is the value obtained by the measurement method described in the Examples.

The average thickness of the modified layer is preferably 2 nm or more and 20 nm or less, and more preferably 5 nm or more and 15 nm or less. When the average thickness is 2 nm or more, modification defects are less likely to occur and the retention of the antifouling liquid is increased, so that the durability of the antifouling structure can be improved. Furthermore, when the average thickness is 20 nm or less, the pore volume present on the surface of the porous layer can be secured, and the retention of the antifouling liquid is increased, so that the durability of the antifouling structure can be improved. The average thickness can be controlled by adjusting the amount of vapor deposition of the modifier when forming the modified layer.

In the present invention, the film thickness of the laminate consisting of the porous layer and the modified layer preferably has a variation of 20% or less, more preferably 1% to 20%, and even more preferably 5% to 15%. If the variation is 20% or less, the antifouling layer is formed uniformly so as to follow the macro uneven structure of the surface of the substrate, so that the contact area between the antifouling structure and the finger can be reduced, and as a result, the effect of the present invention is further exerted. There is no particular limit to the lower limit of the variation, but from the viewpoint of manufacturing, it is preferable that it is 1% or more.

In particular, in the present invention, it is preferable that the average thickness of the porous layer, the average thickness of the modified layer, and the thickness variation of the laminate consisting of the porous layer and the modified layer are each within a specific range. That is, in a preferred embodiment of the antifouling structure of the present invention, the average thickness of the porous layer is 100 nm or more and 500 nm or less, the average thickness of the modified layer is 2 nm or more and 20 nm or less, and the thickness variation of the laminate consisting of the porous layer and the modified layer is 20% or less. In this specification, the above-mentioned variations are values obtained by the measurement method described in the examples.

The method of forming the modified layer is not particularly limited, but first, the surface of the porous layer is cleaned by irradiating the porous layer with an ion beam in a clean deposition chamber. This cleaning process can prevent the occurrence of modification defects caused by the adhesion of contaminants such as hydrocarbons in the air. Then, the modified layer can be formed by depositing an excess of a modifier relative to the OH group on the surface of the porous layer in the deposition chamber. In addition, after the cleaning process, it is preferable to deposit SiO ₂ on the surface of the porous layer and then deposit the modifier. By depositing SiO ₂ before depositing the modifier, OH groups derived from SiO ₂ are formed on the surface of the porous layer, and this OH group makes it easier for the modifier to bind to the porous layer, thereby preventing the occurrence of modification defects. After depositing the modifier on the surface of the porous layer, a heat treatment is performed to fix the modifier to the surface of the porous layer. The heating temperature depends on the modifier, but is preferably 120°C or more and 180°C or less.

[Anti-fouling liquid]
The anti-soiling liquid has a role of suppressing adhesion of sebum when touched by a finger. The anti-soiling liquid exists as an anti-soiling liquid film on the outermost surface of the anti-soiling structure, and can also exist in the pores of the porous layer and inside the modified layer.

The type of anti-soiling liquid is not particularly limited, but is preferably a fluorine-based oil, and preferably contains at least one type selected from the group consisting of perfluoropolyether oil and perfluoroalkyl oil. Fluorine-based oils are highly repellent to sebum. Furthermore, when sebum adhering to a finger comes into contact with the anti-soiling liquid and then separates, the anti-soiling liquid, which has a smaller surface tension, is dragged by the sebum, and separation occurs on the anti-soiling liquid side. This prevents sebum from remaining on the surface of the anti-soiling structure.

In particular, by using an antifouling liquid having a group similar to that contained in the modifier when forming the modified layer, the affinity between the modified layer and the antifouling liquid is improved, and the consumption of the antifouling liquid can be suppressed. That is, in a preferred embodiment of the antifouling structure of the present invention, the modified layer is formed by bonding at the bonding portion of at least one modifier selected from the group consisting of perfluoropolyether group-containing compounds and perfluoroalkyl group-containing compounds to the porous layer, and the antifouling liquid is at least one selected from the group consisting of perfluoropolyether oils and perfluoroalkyl oils. In this embodiment, the modified layer is at least one selected from the group consisting of perfluoropolyether group-containing compounds, and the antifouling liquid is at least one selected from the group consisting of perfluoropolyether oils; or, more preferably, the modified layer is at least one selected from the group consisting of perfluoroalkyl group-containing compounds, and the antifouling liquid is at least one selected from the group consisting of perfluoroalkyl.

The surface free energy of the antifouling liquid is preferably 20 mJ/ ^m2 or less, more preferably 10 mJ/ ^m2 or more and 20 mJ/ ^m2 or less, and more preferably 15 mJ/ ^m2 or more and 18 mJ/ ^m2 or less. Since the surface energy of sebum is about 30 mJ/ ^m2 , if the surface free energy of the antifouling liquid is 20 mJ/ ^m2 or less, the remaining sebum can be further suppressed. If the surface free energy of the antifouling liquid is 10 mJ/ ^m2 or more, the evaporation loss of the antifouling liquid does not become too large, so the heat resistance of the antifouling structure can be maintained. In this specification, the surface free energy is a value obtained by the measurement method described in the examples.

When a fluorine-based oil is used as the antifouling liquid, the average molecular weight of the fluorine-based oil is preferably 1500 to 4000, and more preferably 2000 to 3500. If the average molecular weight is 1500 or more, it becomes entangled with the modifier molecules, and wear can be suppressed. If the average molecular weight is 4000 or less, the entanglement with the modifier molecules is not too strong, and the fluorine-based oil can easily migrate to the sebum side, suppressing the remaining of sebum, etc.

The structure of the fluorine-based oil may be either a straight-chain type without side chains or a side-chain type with side chains, but side-chain fluorine-based oil is preferable. Side-chain fluorine-based oil has a smaller van der Waals force than straight-chain oil, so the bonding force with the modifier is not too large and the fluorine-based oil can easily migrate to the sebum side, thereby suppressing the remaining of sebum, etc. Examples of side-chain fluorine-based oils include Krytox (registered trademark) 100 to 102 manufactured by DuPont. Examples of straight-chain fluorine-based oils include Fomblin (registered trademark) M03 manufactured by Solvay.

The fluorine-based oil preferably has an evaporation loss of 35% by mass or less when left at 120°C for 24 hours. If the evaporation loss is 35% by mass or less, the durability of the antifouling structure can be maintained.

The anti-soiling liquid film can be formed by applying an anti-soiling liquid to the surface of the modified layer and then wiping off the excess anti-soiling liquid.

The antifouling structure of the present invention can be applied to any article requiring antifouling properties. In a preferred embodiment of the antifouling structure of the present invention, the substrate is a transparent substrate and has a haze of less than 5%. Such an antifouling structure is suitable for use in articles requiring visibility.

Examples of articles to which the antifouling structure can be applied include automobile parts. For example, the structure can be suitably used for automobile parts such as automobile rearview mirrors, room mirrors, LCD screens for car navigation systems, and meter panels, where visibility is reduced by fingerprints, as well as for automobile parts such as instrument panels, consoles, and doorknobs, where design is reduced by fingerprint stains. Therefore, according to a preferred embodiment of the present invention, an automobile part having the above-mentioned antifouling liquid is provided.

The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples.

<Method of measuring physical properties>
[Surface roughness (Rz)]
The surface roughness of a 30 μm × 30 μm substrate was measured using a scanning probe microscope (JSPM-5200: manufactured by JEOL), and the Rz value was calculated from the data in accordance with JIS B0601:2013.

[Average opening diameter]
The openings on the surface of the porous layer were observed at a magnification of 50,000 times using a scanning electron microscope (SEM). The diameter of a circle having the same area as each opening was calculated by image analysis, and the average value was taken as the average opening diameter.

[Average film thickness]
The antifouling structure was cut in the lamination direction (thickness direction), and the cross section was observed by a scanning electron microscope (SEM). The thickness of the porous layer and the thickness of the modified layer were measured at 50 points from a 50,000x field of view. The average values were then calculated to determine the average thickness of the porous layer and the average thickness of the modified layer.

[scattering]
The variation in the thickness of the laminate consisting of the porous layer and the modified layer was determined by the following method. First, the antifouling structure was cut in the lamination direction (thickness direction), and the cross section was observed by a scanning electron microscope (SEM). The thickness of the laminate consisting of the porous layer and the modified layer was measured at 50 points from a 50,000x field of view. Of the obtained values, the maximum value was taken as the "maximum thickness" and the minimum value was taken as the "minimum thickness". In addition, the average value of the 50 values was taken as the "average thickness". From these values, the variation in thickness was calculated according to the following formula.

[Surface free energy]
The surface free energy of the antifouling liquid was determined by measuring at 25° C. using the hanging drop method with a contact angle meter DropMaster 700 manufactured by Kyowa Interface Science Co., Ltd.

[Fluorine content]
The fluorine content of the modified layer was determined by measuring the elemental composition using the following apparatus and conditions and calculating the ratio of fluorine atoms to all elements.

Device name: X-ray photoelectron spectrometer, PHI Quantum-2000
X-ray source: Monochromated Al Kα radiation (1486.6 eV) 40 W
Photoelectron take-off angle: 45° (measurement depth: approx. 4 nm)
Measurement area: 200 μmφ.

<Production of antifouling structure>
[Example 1]
(Base material)
Anti-glare glass (Rz=0.992 μm) manufactured by NSC Corporation was used as the substrate.

(Porous Layer)
Solution A was prepared by mixing 1.16 g of pure water, 1.50 g of TEG (triethylene glycol), 0.78 g of IPA (isopropyl alcohol), and 0.30 g of concentrated sulfuric acid (concentration 96% by mass) in this order. Also, 8.04 g of Si ₅ O ₄ (OEt) ₁₂ (Ethyl silicate 40, manufactured by Colcoat Co., Ltd.) and 0.78 g of IPA in this order were mixed to prepare solution B. Solution A was stirred at 1500 rpm with a magnetic stirrer while adding solution B, and after the temperature rise stopped, the solution was stirred for 30 minutes, and then IPA was added so as to be diluted 5 times, and the solution was further stirred at 1500 rpm for 1 minute to obtain a coating solution. The coating solution was spin-coated on a substrate (5 cm x 10 cm x 0.5 mm thick) treated with atmospheric plasma under the following conditions, and then immediately removed from the spinner and left to stand on a flat surface for 2 minutes to air dry.
Spin coating conditions:
The amount of the coating solution dropped was 1500 μL, and the coating was performed at 100 rpm for 3 seconds, and then at 500 rpm for 5 seconds and at 1000 rpm for 15 seconds.
After that, the mixture was left in a dryer at 150° C. for 1 hour for pre-baking, then removed from the dryer and left to stand at room temperature.Furthermore, the mixture was placed in a muffle furnace at room temperature, heated to 400° C. over 30 to 45 minutes, held at that temperature for 1 hour, and then the heating was stopped.The mixture was gradually cooled to 150° C. in the muffle furnace, removed and left to stand at room temperature to form a porous layer with an average opening diameter of 20 nm.

(Modified layer)
The substrate on which the porous layer was formed was placed in a clean deposition chamber, and the porous layer was irradiated with an ion beam to clean the surface. Then, a pretreatment was performed in the deposition chamber to deposit _SiO2 . An excess of a perfluoropolyether-based modifier (Optool DSX, manufactured by Daikin Industries, Ltd.) was deposited on the porous layer on which _SiO2 was deposited to form a modified layer with an average thickness of 7 nm.

(Anti-fouling liquid)
Perfluoropolyether oil (Krytox 101, manufactured by DuPont, molecular weight: 1780, surface free energy: 16.6 mJ/ ^m2 , dynamic viscosity: 17.4 cSt) was applied as an antifouling liquid to the laminate consisting of the porous layer and the modified layer, and excess antifouling liquid was wiped off to obtain an antifouling structure with an antifouling liquid retention amount of 0.0013 g.

[Example 2]
An antifouling structure was obtained in the same manner as in Example 1, except that anti-glare glass (Rz = 0.77 μm) manufactured by NSC Corporation was used as the substrate, and 1.00 g of concentrated sulfuric acid (concentration: 96 mass%) was used in the preparation of solution A. In the obtained antifouling structure, the average opening diameter of the porous layer was 100 nm, and the retention amount of the antifouling liquid was 0.0011 g.

[Example 3]
An antifouling structure was obtained in the same manner as in Example 1, except that anti-glare glass (Rz = 0.77 μm) manufactured by NSC Corporation was used as the substrate, and 1.30 g of concentrated sulfuric acid (concentration: 96 mass%) was used in the preparation of solution A. In the obtained antifouling structure, the average opening diameter of the porous layer was 180 nm, and the retention amount of the antifouling liquid was 0.0015 g.

[Example 4]
Except for using anti-glare glass (Rz=0.31 μm) manufactured by NSC Corporation as the substrate, an anti-soiling structure was obtained in the same manner as in Example 1. In the obtained anti-soiling structure, the average opening diameter of the porous layer was 20 nm, and the retention amount of the anti-soiling liquid was 0.0011 g.

[Example 5]
An antifouling structure was obtained in the same manner as in Example 1, except that anti-glare glass (Rz=1.23 μm) manufactured by NSC Corporation was used as the substrate, and a modified layer with an average thickness of ₂ nm was formed by depositing an excess of perfluoroalkyl-based modifier (C ₁₀ F ₂₁ Si(OCH ₃ ) ₃ manufactured by Kanto Chemical Co., Ltd.) without performing pretreatment for depositing SiO 2. Note that, in the obtained antifouling structure, the average opening diameter of the porous layer was 20 nm, and the amount of antifouling liquid held was 0.0012 g.

[Comparative Example 1]
An antifouling structure was obtained in the same manner as in Example 1, except that soda lime glass (Rz=0.002 μm) was used as the substrate, and a modified layer with an average thickness of ₂ nm was formed by depositing an excess of a perfluoroalkyl-based modifier (C ₁₀ F ₂₁ Si(OCH ₃ ) ₃ manufactured by Kanto Chemical Co., Ltd.) without performing pretreatment for depositing SiO 2. In addition, in the obtained antifouling structure, the average opening diameter of the porous layer was 20 nm, and the retention amount of the antifouling liquid was 0.0011 g.

[Comparative Example 2]
Except for using anti-glare glass (Rz=2.87 μm) manufactured by NSC Corporation as the substrate, an anti-soiling structure was obtained in the same manner as in Example 1. In the obtained anti-soiling structure, the average opening diameter of the porous layer was 20 nm, and the retention amount of the anti-soiling liquid was 0.0010 g.

<Evaluation>
[Haze]
The haze of the soil-resistant structure was measured using a haze/transmittance meter (manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K7136:2000.

[sensory evaluation]
The antifouling structure with the simulated fingerprints was fixed on the LCD screen of a car navigation system under clear skies, and ten panelists seated in the driver's seat gave a score on the degree to which fingerprints were noticeable, using the absolute evaluation below. The average score of all panelists was calculated, and the score was judged according to the following four-level evaluation criteria. If it was ◯ or higher, it was acceptable for practical use.

Absolute evaluation criteria (score): (evaluation)
5 points: Not at all bothersome 4 points: Hardly bothersome 3 points: Not very bothersome 2 points: Somewhat bothersome 1 point: Very bothersome 4-level rating scale (Rating): (Average score)
⊚: 5 points: very good ◯: 3 points or more but less than 5 points: good △: 2 points or more but less than 3 points: slightly poor ×: 1 point or more but less than 2 points: poor.

[Heat resistance test]
The antifouling structure was placed vertically in a high-temperature, high-humidity chamber (90° C., relative humidity 90% RH) and left for 200 hours. The antifouling structure after the heat resistance test was frozen using liquid nitrogen, cut in the lamination direction (thickness direction), and the cross section was observed by SEM. The film thickness of the antifouling liquid was measured at 50 points from a 50,000x field of view, and the average value was calculated.

The results are shown in Table 1 below.

As shown in Table 1, the antifouling structure of the present invention reduced fingerprint adhesion and improved antifouling properties.

1. Substrate,
2 Antifouling layer,
3 porous layer,
4 modified layer,
5 Antifouling liquid membrane,
6 Sebum,
10. Antifouling structure.

Claims (7)

A substrate having an uneven structure with a surface roughness (Rz) of 0.30 μm or more and 1.25 μm or less;
a porous layer having pores with an average opening diameter of 200 nm or less formed on the surface of the uneven structure of the substrate;
A modified layer formed on the surface of the porous layer;
an antifouling liquid held on the surface of the modified layer;
The antifouling structure has The average thickness of the porous layer is 100 nm or more and 500 nm or less,
The average thickness of the modified layer is 2 nm or more and 20 nm or less,
The antifouling structure according to claim 1 , wherein the thickness of the laminate consisting of the porous layer and the modified layer has a variation of 20% or less. The antifouling structure according to claim 1 or 2, wherein the surface free energy of the antifouling liquid is 20 mJ/ ^m2 or less. the modified layer is formed by bonding a bonding portion of at least one modifier selected from the group consisting of a perfluoropolyether group-containing compound and a perfluoroalkyl group-containing compound to the porous layer,
The antifouling structure according to any one of claims 1 to 3, wherein the antifouling liquid is at least one selected from the group consisting of perfluoropolyether oils and perfluoroalkyl oils. The antifouling structure according to any one of claims 1 to 4, wherein the fluorine content of the modified layer is 38 mol% or more and 60 mol% or less. The substrate is a transparent substrate,
The antifouling structure according to any one of claims 1 to 5, having a haze of less than 5%. An automobile part having an antifouling structure according to any one of claims 1 to 6.