WO2024029537A1

WO2024029537A1 - Substrate with silica film

Info

Publication number: WO2024029537A1
Application number: PCT/JP2023/028164
Authority: WO
Inventors: 彩夏安部
Original assignee: Ａｇｃ株式会社
Priority date: 2022-08-03
Filing date: 2023-08-01
Publication date: 2024-02-08

Abstract

The present invention provides a substrate with a silica film, which has excellent initial oil repellency, while having improved oil repellency after being heated to 300°C.　A substrate with a silica film according to the present invention comprises a substrate and a silica film that is arranged on the substrate; the silica film contains an antioxidant and a hydrolysis condensation product of a hydrolyzable compound that contains a compound represented by Si(-R1)n(-OR2)4-n; the content of the antioxidant is 25% by mass or less relative to the total mass of the silica film; and the ratio of the carbon atom content to the silicon atom content in the silica film is 0.90 or more; and the thickness of the silica film is 15 nm or more. In the formula, R1 represents an alkyl group having 1 to 3 carbon atoms; R2 represents a methyl group or an ethyl group; and n represents an integer of 1 to 3.

Description

Substrate with silica film

The present invention relates to a substrate with a silica film.

2. Description of the Related Art A method is known in which a film is formed on the surface of a substrate for the purpose of protecting the substrate or imparting a desired function to the substrate.
For example, Patent Document 1 discloses a method in which a coating solution containing methyltriethoxysilane, an aqueous hydrochloric acid solution, and ethanol is applied onto a substrate such as a glass substrate or a stainless steel plate, and dried to form a water- and oil-repellent film on the substrate. is disclosed.

Japanese Patent Application Publication No. 2014-185334

In recent years, there has been a demand for further improvements in the performance of films placed on the surface of substrates. There is also a need for membranes with improved oil resistance.
When the present inventor formed a film on a substrate using the coating liquid described in Patent Document 1, the initial oil repellency was excellent, but there was room for improvement in oil repellency after heating to 300 ° C. I found out.

The present invention was made in view of the above problems, and an object of the present invention is to provide a substrate with a silica film that has excellent initial oil repellency and improved oil repellency after heating to 300°C.

As a result of intensive studies on the above-mentioned problems, the present inventors found that the silica film of the silica film-coated substrate contains a hydrolyzed condensate of a hydrolyzable compound including a compound represented by a predetermined formula, and an antioxidant. found that the desired effect can be obtained when the ratio of the carbon atom content to the silicon atom content in the silica film is 0.90 or more and the thickness of the silica film is 15 nm or more, and the present invention reached.

That is, the inventors have found that the above problem can be solved by the following configuration.
[1] Includes a substrate and a silica film disposed on the substrate,
The silica membrane contains a hydrolyzed condensate of a hydrolyzable compound including a compound represented by formula (1), and an antioxidant,
The content of the antioxidant is 25% by mass or less based on the total mass of the silica film,
The ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 0.90 or more,
A substrate with a silica film, wherein the silica film has a thickness of 15 nm or more.
Si(-R ¹ ) _n (-OR ² ) _4-n formula (1)
In the above formula (1),
R ¹ is an alkyl group having 1 to 3 carbon atoms,
R ² is a methyl group or an ethyl group,
n is an integer from 1 to 3.
[2] The substrate with a silica film according to [1], wherein the ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 1.60 or less.
[3] The silica film-coated substrate according to [1] or [2], wherein the ratio of the carbon atom content to the silicon atom content in the silica film is 1.40 to 1.60.
[4] The silica film-coated substrate according to any one of [1] to [3], wherein the silica film has a thickness of 120 nm or less.
[5] The silica film-coated substrate according to any one of [1] to [4], wherein the antioxidant has a 12% weight loss temperature of 300° C. or higher when measured in air.
[6] The silica film-coated substrate according to any one of [1] to [5], wherein the silica film contains two or more types of antioxidants having different reaction mechanisms as the antioxidants.
[7] The silica film-coated substrate according to any one of [1] to [6], wherein the silica film contains a phenolic antioxidant and a phosphorus antioxidant as the antioxidant.
[8] The silica film-coated substrate according to any one of [1] to [7], wherein the content of the antioxidant is 0.05 to 25% by mass based on the total mass of the silica film.
[9] The silica film-coated substrate according to any one of [1] to [8], wherein the silica film further contains silica particles.
[10] The silica film-coated substrate according to any one of [1] to [9], further comprising an intermediate layer between the substrate and the silica film.

According to the present invention, it is possible to provide a substrate with a silica film that has excellent initial oil repellency and improved oil repellency after heating to 300°C.

FIG. 1 is a cross-sectional view schematically showing an example of a silica film-coated substrate of the present invention.

The meanings of terms in the present invention are as follows.
A numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits. In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.
In this specification, for each component, one type of substance corresponding to each component may be used alone, or two or more types may be used in combination. Here, when two or more types of substances are used together for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified.
In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[Substrate with silica film]
A silica film-coated substrate of the present invention includes a substrate and a silica film disposed on the substrate. Further, the content of the antioxidant is 25% by mass or less based on the total mass of the silica film. Further, the silica membrane contains a hydrolyzed condensate of a hydrolyzable compound including a compound represented by formula (1) described below, and an antioxidant. Further, the ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 0.90 or more. Further, the thickness of the silica film is 15 nm or more.
The silica film-coated substrate of the present invention has excellent initial oil repellency and is also improved in oil repellency after heating to 300° C. (hereinafter also referred to as "oil repellency after heating"). Although the details of this reason have not been clarified, it is assumed that it is generally due to the following reasons.

It is believed that the carbon atoms and silicon atoms contained in the silica membrane of the present invention are mainly based on alkyl groups and siloxane bonds contained in the hydrolyzed condensate of the hydrolyzable compound, respectively.
Here, in the silica film of the present invention, since the ratio of the content of carbon atoms to the content of silicon atoms is 0.90 or more, it is considered that alkyl groups are sufficiently present in the silica film. Therefore, it is presumed that the oil repellency effect due to the alkyl group was well expressed and the initial oil repellency was improved.
On the other hand, when the ratio of the carbon atom content to the silicon atom content is 0.90 or more, there are fewer siloxane bonds in the film, so the siloxane film can suppress thermal decomposition when the silica film is heated. In some cases, the effect of the combination cannot be obtained sufficiently. To solve this problem, by using a silica film containing an antioxidant, the effect of the antioxidant suppresses thermal oxidation of the silica film, and as a result, the silica film can exhibit excellent oil repellency even after heating. Guessed. It is also presumed that by using a silica film with a thickness of 15 nm or more, the thickness could be maintained to the extent that excellent oil repellency could be exhibited even after the silica film was heated. In this way, due to the synergistic effect of using an antioxidant and increasing the thickness to 15 nm or more, even after heating the silica film at a high temperature of 300°C, it has better oil repellency than conventional films. It is considered that this has been improved.

FIG. 1 is a cross-sectional view schematically showing an example of a silica film-coated substrate of the present invention. The silica film-coated substrate 1A includes a substrate 10 and a silica film 20 formed on one surface of the substrate 10.
In the example of FIG. 1, the silica film 20 is formed on the entire surface of one side of the substrate 10, but the silica film 20 is not limited to this, and the silica film 20 may be formed only on a part of the surface of the substrate 10. .
In the example of FIG. 1, the silica film 20 is formed only on one side of the substrate 10, but the present invention is not limited to this, and the silica film 20 may be formed on both sides of the substrate 10.
Each member included in the silica film-coated substrate 1A will be described below.

〔substrate〕
Although the type of substrate 10 is not particularly limited, a glass substrate and a metal substrate are preferable.
Specific examples of materials constituting the glass substrate include soda lime glass, aluminosilicate glass, lithium glass, and borosilicate glass. The glass substrate may be chemically strengthened glass, air-cooled strengthened glass, or crystallized glass. The glass substrate may be a glass plate with a smooth surface formed by a float method or the like, a molded glass plate with an uneven surface, or a glass plate with a curved shape.
Specific examples of materials constituting the metal substrate include aluminum, titanium, copper, nickel, stainless steel, brass, magnesium, iron, and alloys thereof. These materials may be used alone or in combination of two or more.

The thickness of the substrate 10 is appropriately selected depending on the application and is not particularly limited, but is preferably 0.1 to 50 mm.
When the substrate 10 is a glass substrate, the thickness of the glass substrate is preferably 1 to 10 mm, more preferably 1 to 5 mm.
When the substrate 10 is a metal substrate, the thickness of the metal substrate is preferably 0.1 to 50 mm, more preferably 1 to 10 mm.

[Silica membrane]
The silica membrane 20 contains a hydrolyzed condensate of a hydrolyzable compound including the compound represented by formula (1), and an antioxidant.

The ratio of the carbon atom content to the silicon atom content (carbon atom content/silicon atom content; hereinafter also referred to as "C/Si") in the silica film 20 is 0.90 or more. , 1.00 or more is preferable, 1.20 or more is more preferable, and 1.40 or more is still more preferable, since the initial oil repellency of the silica film-coated substrate 1A is more excellent.
C/Si is preferably 1.60 or less, more preferably 1.55 or less, and even more preferably 1.50 or less, from the standpoint that the silica film-coated substrate 1A has better oil repellency after heating.
Here, C/Si is determined based on analysis of the surface of the silica film 20 by X-ray photoelectron spectroscopy (XPS) with the angle between the surface of the silica film 20 and the detector being 45 degrees, and specifically, It is calculated as follows.
The surface of the silica film 20 is analyzed by X-ray photoelectron spectroscopy (XPS) in which the angle between the surface of the silica film 20 and the detector is 45 degrees, and the peak intensities of Si _2p and C _1s are determined. Based on the obtained peak intensity, the content of silicon atoms (at%) and the content of carbon atoms (at%) are determined, and the concentration of carbon atoms (at%) relative to the content of silicon atoms (at%) is determined. Calculate the ratio of C/Si. Note that detailed measurement conditions for XPS are as described in the Examples section below.

The thickness of the silica film 20 is 15 nm or more, preferably 20 nm or more, and 25 nm or more from the viewpoint of better chemical resistance, initial oil repellency, oil repellency after heating, and abrasion resistance of the silica film-coated substrate 1A. More preferred.
The thickness of the silica film 20 is preferably 240 nm or less, more preferably 120 nm or less, and even more preferably 100 nm or less, in order to improve the scratch resistance of the silica film-coated substrate 1A.
The thickness of the silica film 20 can be measured by the method described in the Examples section using an apparatus based on ellipsometry.

Specific examples of uses of the silica film 20 include protective films for glass substrates and metal substrates (eg, anti-scratch film, antifouling film).

<Hydrolyzable condensate>
The term "hydrolytic condensate of a hydrolyzable compound" refers to a compound obtained by hydrolyzing a hydrolyzable group in a hydrolyzable compound and condensing the resulting hydrolyzate. In addition, the above-mentioned hydrolyzed condensate is one in which all the hydrolyzable groups are hydrolyzed and all the hydrolysates (compounds obtained by hydrolyzing the hydrolysable groups in the hydrolyzable compound) are condensed. It may be a complete hydrolyzed condensate or a partially hydrolyzed condensate in which some hydrolyzable groups are hydrolyzed and some hydrolysates are condensed. That is, the hydrolyzed condensate may be a complete hydrolyzed condensate, a partially hydrolyzed condensate, or a mixture thereof. In addition, a hydrolyzed condensate is a hydrolyzed condensate obtained by condensing hydrolyzable compounds, their hydrolysates, and hydrolyzed condensates of two or more compounds with each other. There may be.

The hydrolyzable compound includes a compound represented by formula (1).
Si(-R ¹ ) _n (-OR ² ) _4-n formula (1)

In formula (1), R ¹ is an alkyl group having 1 to 3 carbon atoms, specifically a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. Among these, R ¹ is preferably a methyl group or an ethyl group, and more preferably a methyl group, since the silica film-coated substrate 1A has excellent oil repellency.
When n is 2 or more, a plurality of R ¹ 's may be the same or different.

In formula (1), R ² is a methyl group or an ethyl group. That is, the ^-OR2 group in formula (1) is a methoxy group or an ethoxy group, which is a type of hydrolyzable group.
When n is 2 or less, a plurality of R ² 's may be the same or different.

In formula (1), n is an integer from 1 to 3, and is preferably 1 or 2 from the viewpoint that both the initial oil repellency and the post-heating oil repellency of the silica film-coated substrate 1A can be satisfied at a high level.

Among these, the compound represented by formula (1) is preferably methyltriethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. The compounds represented by formula (1) may be used alone or in combination of two or more.

The hydrolyzable compound may contain compounds other than the compound represented by formula (1) (hereinafter also referred to as "other compounds"). Other compounds include tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane.
Addition of tetraalkoxysilane (tetrafunctional silane) increases bonding points and improves wear resistance. The content of tetraalkoxysilane is preferably 15 to 50% by mass, more preferably 25 to 35% by mass, based on the total mass of the hydrolyzable compound including the compound represented by formula (1). When the content of tetraalkoxysilane is above the lower limit, the bonding points are sufficiently increased and the wear resistance improving effect becomes large, and when the content of tetraalkoxysilane is below the upper limit, the oil repellent group (alkyl group) is As the content ratio increases, oil repellency is further improved.

The content of the hydrolyzed condensate is preferably 75 to 99.95% by mass, more preferably 90 to 99.50% by mass, and even more preferably 95 to 99.00% by mass, based on the total mass of the silica membrane 20. .

<Antioxidant>
Specific examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, and sulfur antioxidants.
The antioxidant preferably contains two or more kinds of antioxidants having different reaction mechanisms from each other, from the viewpoint that the silica film-coated substrate 1A has better oil repellency after heating, and includes a phenolic antioxidant and a phosphorus antioxidant. It is more preferable to use both.
Here, the expression "the reaction mechanisms are different from each other" means that the reaction mechanisms for suppressing the oxidation of the silica film by the antioxidant are different from each other.

In order to improve the oil repellency of the silica film-coated substrate 1A after heating, it is preferable to use an antioxidant whose 12% weight loss temperature when measured in air is 300° C. or higher. The upper limit of the above 12% weight loss temperature is usually 400°C or less.
The 12% weight loss temperature of the antioxidant is measured using a thermogravimetric differential thermal analyzer (TG-DTA) at a heating rate of 10° C./min in an air atmosphere.
Specific examples of antioxidants having a 12% weight loss temperature of 300°C or higher when measured in air include 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diylbis. (2-methylpropane-2,1-diyl)bis[3-[3-(t-butyl)-4-hydroxy-5-methylphenyl]propanoate], tris(2,4-di-t-butylphenyl) Examples include phosphite and pentaerythritol tetrakis [3-(dodecylthio)propionate].

The content of the antioxidant is preferably 0.03% by mass or more, more preferably 0.50% by mass or more, and even more preferably 1.0% by mass or more, based on the total mass of the silica film 20. If the content of the antioxidant is 0.03% by mass or more, the oil repellency of the silica film-coated substrate 1A after heating will be more excellent.
The content of the antioxidant is 25% by mass or less, preferably 10% by mass or less, and more preferably 5.0% by mass or less, based on the total mass of the silica film 20. When the content of the silica film is 25% by mass or less, the initial oil repellency and the oil repellency after heating of the silica film-coated substrate 1A are excellent. Furthermore, the appearance characteristics of the silica film are also excellent.

<Silica particles>
The silica film 20 preferably further contains silica particles since the silica film-coated substrate 1A has better wear resistance.

Silica particles are particles containing silica (SiO ₂ ).
Specific examples of the shape of the silica particles include spherical, elliptical, needle-like, plate-like, rod-like, conical, cylindrical, cubic, rectangular, diamond-like, star-like, and irregular shapes.
Silica particles may be solid particles, hollow particles, or porous particles. "Solid particle" means a particle that does not have an internal cavity. "Hollow particle" means a particle having a cavity inside. "Porous particle" means a particle having a plurality of pores on its surface.
The silica particles may exist independently, each particle may be connected in a chain, or each particle may be aggregated.

The average primary particle diameter of the silica particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less, from the viewpoint of excellent transparency of the silica film.
The average primary particle diameter of the silica particles is preferably 0.1 nm or more, more preferably 0.5 nm or more, and even more preferably 1 nm or more, from the viewpoint of excellent dispersibility in the film.
The average primary particle diameter of silica particles is determined by taking an SEM photograph of the particles using a scanning electron microscope (SEM) (for example, an apparatus similar to S-4800 manufactured by Hitachi High Technologies), and determining the long axis of the primary particle in the image. This value is obtained by measuring 100 diameters and taking the arithmetic average. Note that the long axis diameter of the primary particles in the image means the longest line segment when a straight line is drawn from end to end in the primary particles in the image.

As the silica particles, commercially available products may be used, such as the Snowtex series manufactured by Nissan Chemical Industries, Ltd.
The silica particles may be used alone or in combination of two or more.

The content of silica particles is preferably 0.05 to 10.00% by mass, more preferably 0.10 to 5.00% by mass, and 0.10 to 1.00% by mass based on the total mass of the silica membrane 20. % is more preferable.
If the content of silica particles is 0.05% by mass or more, the wear resistance of the silica film-coated substrate 1A will be better. If the content of silica particles is 10.00% by mass or less, the initial oil repellency of the silica film-coated substrate 1A will be more excellent.

<Other ingredients>
The silica film 20 may contain components other than those mentioned above (hereinafter also referred to as "other components"). Specific examples of other components include metal catalysts, acid catalysts (eg, nitric acid), water, alcohols, and other organic solvents.
When the silica membrane 20 contains other components, the content of the other components is preferably more than 0% by mass and 1.00% by mass or less, and more than 0% by mass and 0.50% by mass, based on the total mass of the silica membrane 20. % or less is more preferable.

[Middle layer]
The silica film-covered substrate 1A may further include an intermediate layer (not shown) between the substrate 10 and the silica film 20.
The intermediate layer may be formed on the entire overlapping portion of the substrate 10 and the silica film 20, or may be formed on a part of the overlapping portion of the substrate 10 and the silica film 20.

The intermediate layer is preferably a layer that improves the adhesion between the substrate 10 and the silica film 20, and specifically, it is more preferably a layer formed using a silane coupling agent.
Specific examples of silane coupling agents include:
Tetraethoxysilane, tetramethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyl Epoxysilane such as diethoxysilane;
(meth)acrylic silanes such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane;
Vinylsilanes such as vinyltrimethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropyltrimethoxysilane;
N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-N'-(2-amino Aminosilanes such as ethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane;
Isocyanate silane such as 3-isocyanatepropyltrimethoxysilane;
ureidosilane such as 3-ureidopropyltriethoxysilane;
Examples include mercaptosilanes such as 3-mercaptopropyltrimethoxysilane.
Among these, Q-configuration or T-configuration silane coupling agents are preferred from the viewpoint of reactivity and adhesion.
Commercial products may be used as the silane coupling agent, and specific examples include KBP-90 (product name, manufactured by Shin-Etsu Silicone Co., Ltd., aminosilane) and tetraethoxysilane (Fuji Film Wako Pure Chemical Industries, Ltd.).
Moreover, the intermediate layer may contain a catalyst such as an acid.

The thickness of the intermediate layer is preferably 5.00 to 30.00 nm, more preferably 10.00 to 20.00 nm.
The thickness of the intermediate layer was determined by acquiring a cross-sectional image of the silica film-coated substrate 1A using a scanning electron microscope (SEM), and measuring the thickness at three different positions corresponding to the thickness of the intermediate layer. Means the arithmetic mean value of the thickness at a location.

[Physical properties]
When the substrate 10 is a glass substrate, the contact angle (initial contact angle) of salad oil on the surface of the silica film 20 is preferably 55.0 degrees or more, more preferably 58.0 degrees or more, and still more preferably 60.0 degrees or more. preferable. The upper limit is usually 67.0 degrees or less.
When the substrate 10 is a glass substrate, the contact angle of salad oil on the surface of the silica film 20 after heating the silica film-coated substrate 1A at 300° C. for 400 hours is preferably 35.0 degrees or more, and 37.0 degrees or more. is more preferable, 40.0 degrees or more is still more preferable, and 50.0 degrees or more is particularly preferable. The upper limit is usually 60.0 degrees or less.
When the substrate 10 is a glass substrate, the contact angle of salad oil on the surface of the silica film 20 after heating the silica film-coated substrate 1A at 250° C. for 800 hours is preferably 45.0 degrees or more, and preferably 50.0 degrees or more. is more preferable, and even more preferably 55.0 degrees or more. The upper limit is usually 60.0 degrees or less.
When the substrate 10 is a glass substrate, the contact angle of salad oil on the surface of the silica film 20 after immersing the silica film-coated substrate 1A in a 0.1N aqueous sodium hydroxide solution adjusted to 25° C. for 2 hours is 40.0. It is preferably at least 45.0 degrees, more preferably at least 50.0 degrees. The upper limit is usually 60.0 degrees or less.
The contact angle of salad oil on the surface of these silica films 20 is measured by the method described in the Examples section below.

When the substrate 10 is a metal substrate, the contact angle (initial contact angle) of salad oil on the surface of the silica film 20 is preferably 55.0 degrees or more, more preferably 58.0 degrees or more, and still more preferably 60.0 degrees or more. preferable. The upper limit is usually 67.0 degrees or less.
When the substrate 10 is a metal substrate, the contact angle of salad oil on the surface of the silica film 20 after heating the silica film-coated substrate 1A at 300° C. for 400 hours is preferably 21.0 degrees or more, and preferably 22.0 degrees or more. is more preferable, 23.0 degrees or more is even more preferable, and 24.0 degrees or more is particularly preferable. The upper limit is usually 40.0 degrees or less.
When the substrate 10 is a metal substrate, the contact angle of salad oil on the surface of the silica film 20 after heating the silica film-coated substrate 1A at 250° C. for 800 hours is preferably 47.0 degrees or more, and preferably 48.0 degrees or more. is more preferable, and even more preferably 49.0 degrees or more. The upper limit is usually 55.0 degrees or less.
The contact angle of salad oil on the surface of these silica films 20 is measured by the method described in the Examples section below.

[Application]
The use of the silica film-coated substrate 1A is not particularly limited, but because of its excellent initial oil repellency and oil repellency during heating, it can be used as a stain-proofing member for use on the inside surface of cooking utensils (e.g. ovens, ranges, grills). It is suitable for antifouling members used on the surfaces of kitchen members (for example, stoves, tiles) and antifouling members used for members of machine tools.

[Method for manufacturing substrate with silica film]
Examples of the method for manufacturing the silica film-coated substrate 1A include a method in which a silica film-forming composition is applied onto the substrate 10 and dried if necessary to form the silica film 20 on the substrate 10.

<Silica film forming composition>
The composition for forming a silica film includes hydrolyzable compounds and an antioxidant.

(Hydrolyzable compounds)
The hydrolyzable compound is at least one selected from the group consisting of a hydrolyzable compound including the compound represented by formula (1), a hydrolyzate thereof, and a hydrolyzed condensate thereof. Specific examples and preferred embodiments of the hydrolyzable compound including the compound represented by formula (1) are as described above, so their explanation will be omitted.

The composition for forming a silica film contains a compound in which n in formula (1) is 1 (for example, methyltrimethoxysilane) and a compound in which n in formula (1) is 2 (for example, dimethyl It is preferable to include a hydrolyzed condensate with dimethoxysilane) and a compound in which n in formula (1) is 1 (for example, methyltriethoxysilane, ethyltriethoxysilane) as a hydrolyzable compound. As a result, while maintaining the oil repellency derived from the hydrolyzed condensate, high abrasion resistance and heat resistance can be obtained due to the effect of strengthening the membrane skeleton by adding the hydrolyzable compound.

Here, the term "hydrolyzate of a hydrolyzable compound" refers to a compound obtained by hydrolyzing a hydrolyzable group in a hydrolyzable compound. Note that the above hydrolysates may be those in which all of the hydrolyzable groups have been hydrolyzed (completely hydrolyzed products) or those in which some of the hydrolyzable groups have been hydrolyzed (partially hydrolysed products). It may be a thing). That is, the above-mentioned hydrolyzate may be a complete hydrolyzate, a partial hydrolyzate, or a mixture thereof.
Note that the details of the hydrolyzed condensate of the hydrolyzable compound are as described above, so the explanation thereof will be omitted.

The content of the hydrolyzable compounds is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass, based on the total mass of the silica film-forming composition.

(Antioxidant)
Specific examples and preferred embodiments of the antioxidant are as described above, so their explanation will be omitted.
The content of the antioxidant is preferably 0.0005 to 2.0% by mass, more preferably 0.02 to 0.2% by mass, based on the total mass of the silica film-forming composition.

(Silica particles)
It is preferable that the composition for forming a silica film contains silica particles. Specific examples and preferred embodiments of the silica particles are as described above, so their explanation will be omitted.
The content of silica particles is preferably 0.05 to 10.0% by mass, more preferably 0.1 to 1.0% by mass, based on the total mass of the silica film-forming composition.

(liquid medium)
The composition for forming a silica film preferably contains a liquid medium. The liquid medium is preferably a solvent that dissolves or disperses the hydrolyzable compounds and, if necessary, disperses the silica particles used in the composition.

Specific examples of the liquid medium include organic solvents such as alcohols, ketones, ethers, cellosolves, esters, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds, and water.

Specific examples of alcohols include methanol, ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and diacetone alcohol.
Specific examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Specific examples of ethers include tetrahydrofuran and 1,4-dioxane.
Specific examples of cellosolves include methyl cellosolve, ethyl cellosolve, and butyl cellosolve.
Specific examples of esters include methyl acetate, ethyl acetate, and butyl acetate.
Specific examples of glycol ethers include ethylene glycol monoalkyl ether.
Specific examples of nitrogen-containing compounds include N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.
A specific example of the sulfur-containing compound is dimethyl sulfoxide.

The liquid medium may be used alone or in combination of two or more.
From the viewpoint of hydrolysis of the hydrolyzable compound, the liquid medium preferably contains only water or is a mixed solvent of water and an organic solvent.
When a mixed solvent of water and an organic solvent is used, the organic solvent is preferably an alcohol, particularly isopropanol or a mixed alcohol (for example, Solmix AP-11 (manufactured by Nippon Alcohol Sales Co., Ltd.)).
When adding an antioxidant, it is preferable to dissolve the antioxidant in advance in butyl acetate or acetone, in which the antioxidant has good solubility.

When the composition for forming a silica film contains a liquid medium, the content of the liquid medium is preferably 70.0 to 99.5% by mass, and 88.5 to 99% by mass based on the total mass of the composition for forming a silica film. .0% by mass is more preferable.

(other ingredients)
The composition for forming a silica film may contain other components than those mentioned above. Specific examples of other components include metal catalysts, acid catalysts (for example, nitric acid), silicone oils, surfactants, pH adjusters, and antifoaming agents, among which it is preferable to use acid catalysts.
When the composition for forming a silica film contains the other components mentioned above, the content of the other components is preferably 0.1 to 20% by mass, and 0.5% by mass based on the total mass of the composition for forming a silica film. More preferably 10% by mass.
When the composition for forming a silica film contains an acid catalyst, the content of the acid catalyst is determined based on the total mass of the composition for forming a silica film, from the viewpoint of controllability of hydrolysis and condensation of hydrolyzable compounds. It is preferably 0.0001 to 5.0% by weight, more preferably 0.001 to 3.0% by weight.

(Preparation method)
The composition for forming a silica film can be produced by mixing hydrolyzable compounds, an antioxidant, and optional components (for example, silica particles, a liquid medium, and an acid catalyst). For example, after preparing a sol-gel solution of hydrolyzable compounds, the resulting sol-gel solution, an antioxidant, and optional components may be mixed to produce the sol-gel solution.

<Process>
Application methods include spin coating, spray coating, dip coating, die coating, curtain coating, screen coating, inkjet coating, flow coating, gravure coating, bar coating, flexo coating, and slit coating. , a wet coating method such as a roll coating method.

Drying may be performed by heating, or may be performed by natural drying or air drying without heating.
The drying temperature is preferably 50°C to 400°C, more preferably 100°C to 350°C, and even more preferably 200 to 300°C, in view of the excellent hardness of the silica film.
The drying time may be appropriately set depending on the drying temperature, the size of the substrate, etc., but is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 90 minutes, and even more preferably 30 minutes to 60 minutes.

<Other processes>
When it is desired to obtain a substrate 1A with a silica film including the above-mentioned intermediate layer between the substrate 10 and the silica film 20, an intermediate layer is formed on the surface of the substrate 10 before applying the composition for forming a silica film on the substrate 10. The method may further include a step of applying a layer-forming composition to form an intermediate layer. In this case, the silica film-forming composition is applied to the surface of the intermediate layer formed on the substrate 10.

The intermediate layer forming composition preferably contains a silane coupling agent and a liquid medium, and may also contain a catalyst.
Specific examples and preferred embodiments of the silane coupling agent are as described above, so their explanation will be omitted. The content of the silane coupling agent is preferably 0.1 to 5.0% by mass, more preferably 0.3 to 3.0% by mass, based on the total mass of the intermediate layer forming composition.
The specific example of the liquid medium in the composition for forming an intermediate layer is the same as the specific example of the liquid medium that can be included in the composition for forming a silica film, so a description thereof will be omitted. The content of the liquid medium is preferably 95.0 to 99.9% by mass, more preferably 97.0 to 99.7% by mass, based on the total mass of the intermediate layer forming composition.

The specific example of the method for applying the composition for forming an intermediate layer is the same as the specific example of the method for applying the composition for forming a silica film, so the explanation thereof will be omitted.
The step of forming the intermediate layer may include a process of drying the intermediate layer forming composition applied to the substrate 10. Specific examples of the drying conditions for the composition for forming an intermediate layer applied to the substrate 10 are the same as those for the composition for forming a silica film applied to the substrate 10 described above, so the explanation thereof will be omitted.

Hereinafter, the present invention will be explained in detail by giving examples. Examples 1-1 to 1-23 and 2-1 are examples, and examples 1-24 to 1-29 and 2-2 are comparative examples. However, the present invention is not limited to these examples. Note that the amounts of each component in the table described below are based on mass.

[Calculation of silica film thickness]
Using an ellipsometer (trade name "XLS-100", manufactured by J.A. Woollam Co. Inc.), the measurement angle was measured in 5° increments in the range of 50 to 75° against the silica film of the silica film-coated base material. The thickness of the silica film was determined by fitting the measured spectrum using Cauchy's equation.

[Calculation of C/Si]
C/Si (ratio of carbon atom content to silicon atom content in a silica film) was determined as follows.
First, the surface of the silica film was analyzed by X-ray photoelectron spectroscopy (XPS) with the angle between the surface of the silica film and the detector set at 45 degrees under the following conditions, and Si _2p , C _1s , O _1S , and , each peak intensity of AL _2P was determined.
Based on the obtained peak intensity, the content of silicon atoms (at%) and the content of carbon atoms (at%) are determined, and the concentration of carbon atoms (at%) relative to the content of silicon atoms (at%) is determined. The ratio (C/Si) was calculated.
<Measuring device and measurement conditions>
Equipment: Surface XPS measurement device (PHI Quantera SXM manufactured by ULVAC-PHI)
X-ray source: Al Kα
Acceleration voltage power: 24.8W
Measurement range: φ100.0μm
Detection angle: 45 degrees Pass energy: 224.00eV

[Average primary particle diameter]
The average primary particle diameter of the silica particles was determined by taking an SEM photograph of the silica particles using a scanning electron microscope (S-4800, manufactured by Hitachi High Technologies), and measuring the major axis diameter of 100 primary particles in the image. . The arithmetic mean value was adopted as the average primary particle diameter of the silica particles.

[Initial oil repellency evaluation test]
The contact angle of 1 μL of salad oil (edible vegetable oil that complies with JAS standards) placed on the silica film surface of the silica film-coated substrate of each example was measured using a contact angle measuring device (DM-500 manufactured by Kyowa Interface Science Co., Ltd.). Measured at 20°C. Measurements were taken at three different locations on the surface of the silica membrane, and the average value was calculated and used as the contact angle of salad oil. The 2θ method was used to calculate the contact angle.
When the base material was a glass substrate, when the contact angle of salad oil was 55.0 degrees or more, it was evaluated that the initial oil repellency was excellent.
When the base material was a metal substrate (aluminum substrate) and the contact angle of salad oil was 55.0 degrees or more, it was evaluated that the initial oil repellency was excellent.

[Oil repellency evaluation test after heating at 300°C]
The silica film-coated substrate of each example was placed in a muffle furnace with an internal temperature of 300°C. The contact angle of salad oil was determined in the same manner as in the above "initial oil repellency evaluation test" except that the silica film-coated substrate of each example was taken out from the muffle furnace after 400 hours had elapsed.
When the base material was a glass substrate and the contact angle of salad oil was 35.0 degrees or more, it was evaluated that the oil repellency after heating at 300° C. was excellent.
When the base material was a metal substrate (aluminum substrate) and the contact angle of salad oil was 21.0 degrees or more, it was evaluated that the oil repellency after heating at 300° C. was excellent.

[Oil repellency evaluation test after heating at 250°C]
The silica film-coated substrate of each example was placed in a muffle furnace with an internal temperature of 250°C. The contact angle of salad oil was determined in the same manner as in the above "initial oil repellency evaluation test" except that the silica film-coated substrate of each example was taken out from the muffle furnace after 800 hours had elapsed.
When the base material was a glass substrate and the contact angle of salad oil was 45.0 degrees or more, it was evaluated that the oil repellency after heating at 250° C. was excellent.
When the base material was a metal substrate (aluminum substrate) and the contact angle of salad oil was 47.0 degrees or more, it was evaluated that the oil repellency after heating at 250° C. was excellent.

[Chemical resistance evaluation test]
The silica film-coated substrate of each example was immersed in a 0.1N aqueous sodium hydroxide solution adjusted to 25° C. for 2 hours, washed with pure water, and dried with air blow.
The contact angle of salad oil was determined in the same manner as in the above "initial oil repellency evaluation test" except that the silica film-coated substrate of each example was used after drying.
When the base material was a glass substrate, when the contact angle of salad oil was 40.0 degrees or more, it was evaluated as having excellent chemical resistance.

[Abrasion resistance evaluation test]
Regarding the silica film of the silica film-coated substrate of each example, a nonwoven fabric (material: cellulose) was reciprocated 3000 times using an abrasion tester at a load of 125 g/cm ² and a speed of 40 rpm. The contact angle of salad oil was determined in the same manner as in the above "initial oil repellency evaluation test" except that the silica film-coated substrate of each example after the wear test was used.
When the base material was a glass substrate, when the contact angle of salad oil was 35.0 degrees or more, it was evaluated as having excellent abrasion resistance.

[Evaluation test of appearance characteristics]
The appearance of the silica film surface of each example of the silica film-coated substrate was visually observed, and the film appearance was evaluated according to the following criteria.
○: No unevenness caused by foreign matter is observed.
×: Unevenness caused by foreign matter is confirmed.

[Scratch resistance evaluation test]
A pencil hardness test was conducted on the surface of the silica film of each example of the silica film-coated substrate by a method based on JIS K5600. When the base material was a glass substrate and the pencil hardness was 5H or more, it was evaluated that the scratch resistance was excellent.

[Ingredients used]
A summary of the components used to prepare the composition for forming a silica film is shown below.

[Hydrolyzed condensate of a hydrolyzable compound containing the compound represented by formula (1)]
・X-40-9246: Manufactured by Shin-Etsu Chemical Co., Ltd., a condensate with an average molecular weight of 870 consisting of 50 mol% dimethyldimethoxysilane and 50 mol% methyltrimethoxysilane [compound represented by formula (1) (hydrolyzable Compound)〕
・Methyltriethoxysilane: Manufactured by Tokyo Chemical Industry Co., Ltd. ・Dimethyldimethoxysilane: Manufactured by Tokyo Chemical Industry Co., Ltd. ・Ethyltriethoxysilane: Manufactured by Tokyo Chemical Industry Co., Ltd. [Hydrolyzable compounds other than those represented by formula (1)] Compound〕
・Tetraethoxysilane: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [Silica particles]
・Snowtex ST-OXS: manufactured by Nissan Chemical Industries, Ltd., water-dispersed colloidal silica with an average primary particle diameter of 5 nm and a solid content of 10% by mass [liquid medium]
・Alcohol solvent: Solmix AP-11 (manufactured by Nippon Alcohol Sales Co., Ltd.), mixed solvent of ethanol: isopropyl alcohol: methanol = 85.5:9.8:4.7 (mass ratio) ・Water: pure water [antioxidant Agent]
・Phenolic antioxidant: 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diylbis(2-methylpropane-2,1-diyl)bis[3-[3-( t-butyl)-4-hydroxy-5-methylphenyl]propanoate], trade name: ADEKA STAB AO-80 (manufactured by ADEKA Co., Ltd.)
・Phosphorous antioxidant: Tris (2,4-di-t-butylphenyl) phosphite, trade name: ADEKA STAB 2112 (manufactured by ADEKA Co., Ltd.)
・Sulfur-based antioxidant: Pentaerythritol tetrakis [3-(dodecylthio)propionate], manufactured by ADEKA Co., Ltd. [acid catalyst]
・Nitric acid aqueous solution: 60% nitric acid, manufactured by Junsei Kagaku Co., Ltd.

[Preparation of silica film forming composition 1]
Mix 1.43g of X-40-9246, 3.33g of methyltriethoxysilane (MTES), 2.50g of Snowtex ST-OXS, and 38.83g of Solmix AP-11 (alcohol solvent), and add pure water. After dropping 0.25 g of a 1% nitric acid aqueous solution prepared by diluting 3.67 g of 60% nitric acid aqueous solution and 0.0042 g of a 60% nitric acid aqueous solution with 0.246 g of pure water, the mixture was stirred at 60° C. for 30 minutes to obtain a concentrated liquid. 20 g of the obtained concentrated liquid, 0.02 g of phenolic antioxidant (ADK STAB AO-80), 0.04 g of phosphorous antioxidant (ADK STAB 2112), and 79 g of Solmix AP-11 (alcohol solvent). 9g of the mixture was mixed and thoroughly stirred at room temperature for 2 minutes to obtain Silica film forming composition 1, which is a coating liquid.

[Preparation of silica film forming compositions 2 to 23]
A silica film was formed in the same manner as in the preparation of Composition 1 for forming a silica film, except that the amount of each component used was adjusted so that the content (parts by mass) of each component became the values listed in Tables 1 to 5. Compositions 2 to 23 were obtained.

[Example 1-1]
Silica film-forming composition 1 was applied by spin coating onto soda lime glass (manufactured by AGC, size: 10 x 10 mm, thickness: 2 mm) whose surface had been cleaned, and dried at 200° C. in the atmosphere for 30 minutes. Thus, a silica film-coated substrate of Example 1-1 was obtained.

[Examples 1-2 to 1-19, 1-21, 1-24 to 1-29]
Example 1-1 except that the silica film-forming composition listed in Table 1 was used instead of silica film-forming composition 1, and the coating conditions were adjusted so that the thickness of the silica film was the value shown in Table 1. In the same manner as above, silica film-coated substrates of Examples 1-2 to 1-19, 1-21, and 1-24 to 1-29 were produced.

[Example 1-20]
Intermediate layer forming composition 1 was obtained by mixing 0.11 g of KBP-90 (manufactured by Shin-Etsu Silicone Co., Ltd., an aminosilane-based silane coupling agent) and 49.9 g of 1-butanol.
Intermediate layer forming composition 1 was then applied by spin coating onto soda lime glass (manufactured by AGC, size: 10 x 10 mm, thickness: 2 mm) whose surface had been cleaned, and dried at room temperature for 5 minutes. An intermediate layer (thickness: 15 nm) was formed on the surface of soda lime glass.
Next, the composition 1 for forming a silica film was applied to the surface of the intermediate layer by a spin coating method, and dried in the atmosphere at 200°C for 30 minutes to form an intermediate layer between the soda lime glass and the silica film Example 1 A substrate with a silica film of -17 was obtained.

[Example 1-22]
Silica film-forming composition 1 was applied by spin coating onto soda lime glass (manufactured by AGC, size: 10 x 10 mm, thickness: 2 mm) whose surface had been cleaned, and dried at 300° C. for 60 minutes in the air. Thus, a silica film-coated substrate of Example 1-22 was obtained.

[Example 1-23]
A substrate with a silica film of Example 1-23 was prepared in the same manner as Example 1-22 except that the coating conditions were adjusted so that the thickness of the silica film was as shown in Table 1.

[Example 2-1]
A silica film-coated substrate of Example 2-1 was obtained in the same manner as Example 1-1, except that an aluminum substrate (size: 100 x 100 mm, thickness: 4.0 mm) was used instead of soda lime glass as the substrate. Ta.

[Example 2-2]
A substrate with a silica film of Example 2-2 was produced in the same manner as Example 2-1 except that Composition 22 for forming a silica film was used instead of Composition 1 for forming a silica film.

[Evaluation results]
The various evaluations described above were performed using the silica film-coated substrates of Examples 1-1 to 1-29. The results are shown in Tables 1 to 4.
Further, the various evaluations described above were performed using the silica film-coated substrates of Examples 2-1 and 2-2. The results are shown in Table 5.
Note that the silica film-coated base material of Example 1-29 had extremely poor appearance characteristics (surface condition) of the silica film, so evaluations other than appearance characteristics could not be performed.

As shown in Tables 1 to 5, it contains a hydrolyzed condensate of a hydrolyzable compound including the compound represented by formula (1) above, and an antioxidant, and the antioxidant content is the same as that of the silica film. By using a silica film that is 25% by mass or less based on the mass, has a C/Si of 0.90 or more, and has a thickness of 15 nm or more, the silica film has excellent initial oil repellency and oil repellency after heating at 300°C. It was confirmed that a bonded substrate could be obtained.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2022-123895 filed on August 3, 2022 are cited here, and as a disclosure of the specification of the present invention, It is something to be taken in.

1A Substrate with silica film 10 Substrate 20 Silica film

Claims

comprising a substrate and a silica film disposed on the substrate,
The silica membrane contains a hydrolyzed condensate of a hydrolyzable compound containing the compound represented by formula (1), and an antioxidant,
The content of the antioxidant is 25% by mass or less based on the total mass of the silica film,
The ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 0.90 or more,
A substrate with a silica film, wherein the silica film has a thickness of 15 nm or more.
Si(-R 1 ) n (-OR 2 ) 4-n formula (1)
In the above formula (1),
R 1 is an alkyl group having 1 to 3 carbon atoms,
R 2 is a methyl group or an ethyl group,
n is an integer from 1 to 3.
The substrate with a silica film according to claim 1, wherein the ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 1.60 or less.
The substrate with a silica film according to claim 1 or 2, wherein the ratio of the content of carbon atoms to the content of silicon atoms in the silica film is 1.40 to 1.60.
The silica film-coated substrate according to claim 1 or 2, wherein the silica film has a thickness of 120 nm or less.
The silica film-coated substrate according to claim 1 or 2, wherein the antioxidant has a 12% weight loss temperature of 300°C or higher when measured in air.
The silica film-coated substrate according to claim 1 or 2, wherein the silica film contains two or more types of antioxidants having different reaction mechanisms as the antioxidant.
The substrate with a silica film according to claim 1 or 2, wherein the silica film contains a phenolic antioxidant and a phosphorus antioxidant as the antioxidant.
The silica film-coated substrate according to claim 1 or 2, wherein the content of the antioxidant is 0.05 to 25% by mass based on the total mass of the silica film.
The silica film-coated substrate according to claim 1 or 2, wherein the silica film further contains silica particles.
The silica film-coated substrate according to claim 1 or 2, further comprising an intermediate layer between the substrate and the silica film.