JP7577472B2 - Water- and oil-repellent film-forming liquid composition and method for producing same - Google Patents

Description

The present invention relates to a liquid composition for forming a water- and oil-repellent film having water and oil repellency, and a method for producing the same. More specifically, the present invention relates to a liquid composition for forming a water- and oil-repellent film containing metal oxide particles, and a method for producing the same.

So far, a method for producing fluorine-containing nanocomposite particles has been disclosed, which includes a step (first step) of preparing a dispersion of an inorganic compound by dispersing an inorganic compound such as _SiO2 , _CaCO3 , _TiO2 , etc. in an organic solvent such as an alcohol, and a step (second step) of adding a fluorine compound containing a perfluoroalkyl group and a catalyst to the dispersion of the inorganic compound to synthesize a composite material in which the inorganic compound and the fluorine compound are nanocomposite (for example, see Patent Document 1 (paragraphs [0047], [0057], and paragraphs [0067] to [0070]).

Patent Document 1 describes that in the second step, a silane coupling agent containing a silicon alkoxide such as tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS) may be added to the dispersion of the inorganic compound. Patent Document 1 also describes that by dispersing fluorine-containing nanocomposite particles in water or an organic solvent such as alcohol, a dispersion of fluorine-containing nanocomposite particles is prepared, and when this dispersion is used as a coating agent, it is possible to impart functions such as water- and oil-repellency and hydrophilic oil-repellency to the surfaces of various materials.

However, in the dispersion of fluorine-containing nanocomposite particles (film-forming liquid composition) made by the manufacturing method described in Patent Document 1, the inorganic compound (metal oxide particles) is hydrophilic and oil-repellent, so it was not possible to improve the hardness and strength of the film formed while maintaining the oil-repellent properties.

For this reason, fluorine-containing composite particles that can exhibit higher water repellency and oil repellency than conventional ones have been proposed (for example, see Patent Document 2 (Claim 1, paragraphs [0008], [0039] to [0054])). The fluorine-containing composite particles are composite particles in which the surface of silica-based fine particles is coated with at least one of 1) a fluorine-containing compound and 2) a fluorine-containing group formed by siloxane bonding between the silicon of the silica-based fine particles, the fluorine-containing compound is a compound containing a functional group A represented by [-Si(OR) ₃ ] (wherein the three Rs are the same or different and represent hydrogen or an alkyl group having 1 to 10 carbon atoms) at at least one end side of a main chain made of perfluoropolyether, and the fluorine content per unit surface area of the silica-based fine particles is 0.8 mg/m ² to 1.0 g/m ² .

The fluorine-containing composite particles are produced by mixing silica-based microparticles or a dispersion thereof with a solution of a fluorine-containing compound, and in particular by mixing the two and then stirring the mixture. The dispersion of silica-based microparticles and the solution of the fluorine-containing compound are each prepared by dispersing in water, a water-soluble organic solvent, or a mixture of these. By mixing the dispersion of silica-based microparticles with the solution of the fluorine-containing compound and then stirring the mixture, it becomes possible for part or all of the functional group A to sufficiently react with the silica on the surface of the silica-based microparticles or the functional groups on the silica surface to reliably form siloxane bonds.

After the stirring is completed, the fluorine-containing composite particles described in Patent Document 2 are obtained in the form of a slurry. Depending on the application, the fluorine-containing composite particles can be used as is in the form of a slurry, or can be used in the form of a substantially dried powder after subjecting the slurry to solid-liquid separation, washing, or other treatments as necessary. The fluorine-containing composite particles can also be used in the form of a dispersion obtained by further dispersing them in a solvent. In addition, the slurry can be separated into solid and liquid, and the cake obtained is dispersed in another solvent to be used in the form of a dispersion.

JP 2018-39987 A International Publication No. WO2019/026816

In the film-forming liquid compositions disclosed in Patent Document 2, such as a slurry of fluorine-containing composite particles and a dispersion obtained by dispersing fluorine-containing composite particles in a solvent, the liquid composition can be applied to various articles to form a coating film on the surface of the article, thereby imparting water repellency and/or oil repellency to the article. However, there are problems such as the oil repellency being still insufficient, and the binding strength between the fluorine-containing composite particles being insufficient, resulting in the strength and hardness of the formed film being low, and further improvements were required.

The object of the present invention is to provide a liquid composition for forming a water- and oil-repellent film, which has higher water repellency, oil repellency, strength and hardness than films formed with conventional liquid compositions, and which makes fingerprints less noticeable on the film surface, and a method for producing the same.

The inventors of the present invention have arrived at the present invention by noting that by bonding fluorine-based functional group components to metal oxide particles and by incorporating fluorine-based functional group components into silica sol-gel, the formed film is endowed with high oil repellency, and that by forming a film by bonding metal oxide particles together with fluorine-containing silica sol-gel, the hardness and abrasion resistance of the film are improved, and unevenness is formed on the film surface, improving fingerprint resistance.

A first aspect of the present invention is a water- and oil-repellent film-forming liquid composition comprising: fluorine-containing metal oxide particles (B) having an average particle size of 2 nm to 90 nm and bonded to a first fluorine-based compound (A1) containing a perfluoroether structure , which is represented by any one of the following formulas (19) to (27); fluorine-containing silica sol-gel (C) containing a second fluorine-based compound (A2) containing a perfluoroether structure , which is represented by any one of the following formulas (19) to (27); and a solvent (D), wherein, when the amount of all components excluding the solvent (D) is taken as 100 mass%, the total content of the first fluorine compound (A1) and the second fluorine compound (A2) is 1 mass% to 30 mass%, and the mass ratio (C:B) of the fluorine-containing silica sol-gel (C) to the fluorine-containing metal oxide particles (B) is in the range of 10:90 to 90:10.

In the above formulas (19) to (27), R is a methyl group or an ethyl group.

A second aspect of the present invention is an invention based on the first aspect, which is a water- and oil-repellent film-forming liquid composition, wherein a content ratio of the first fluorine compound (A1) is equal to or greater than a content ratio of the second fluorine compound (A2) by mass ratio.

A third aspect of the present invention is the invention based on the first aspect, wherein the metal oxide particles used for the fluorine-containing metal oxide particles (B) are oxide particles of one or more metals selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr.

A fourth aspect of the present invention is the invention based on the first aspect, wherein the fluorine-containing silica sol-gel (C) is a water- and oil-repellent film-forming liquid composition containing 0.5% by mass to 20% by mass of an alkylene group component having 2 to 7 carbon atoms, when the fluorine-containing silica sol-gel (C) is taken as 100% by mass.

The fifth aspect of the present invention is an invention based on the first aspect, and is a liquid composition for forming a water- and oil-repellent film, in which the solvent (D) is a mixed solvent of water and an alcohol having 1 to 4 carbon atoms, or a mixed solvent of water, an alcohol having 1 to 4 carbon atoms, and an organic solvent other than the alcohol.

A sixth aspect of the present invention is a method for producing a water- and oil-repellent film-forming liquid composition according to the first aspect , as shown in FIG. 1, which comprises mixing a dispersion of fluorine-containing metal oxide particles (B) and a fluorine-containing silica sol-gel liquid (C) to produce the water- and oil-repellent film-forming liquid composition .

A seventh aspect of the present invention is an invention based on the fifth aspect, and relates to a method for producing a water- and oil-repellent film-forming liquid composition, in which the dispersion of fluorine-containing metal oxide particles (B) is prepared by adding and mixing a fluorine-based compound (A1) to a dispersion of metal oxide particles, and then adding and mixing water and a catalyst to the mixture, as shown in FIG.

An eighth aspect of the present invention is an invention based on the sixth aspect, and relates to a method for producing a water- and oil-repellent film-forming liquid composition, wherein the metal oxide particles used for the fluorine-containing metal oxide particles (B) are oxide particles of one or more metals selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr.

A ninth aspect of the present invention is an invention based on the fifth aspect, and relates to a method for producing a water- and oil-repellent film-forming liquid composition, in which the fluorine-containing silica sol-gel liquid (C) is prepared by adding a catalyst to a mixed liquid of a silicon alkoxide, an alcohol, a fluorine-based compound (A2) and water, as shown in FIG. 1 .

In the water- and oil-repellent film-forming liquid composition according to the first aspect of the present invention, when a film is formed, the film has very high oil repellency because the metal oxide particles are bound together by the fluorine-containing silica sol-gel (C) containing the first fluorine compound (A1) and the second fluorine compound (A2). In addition , the film has high hardness and abrasion resistance. The surface of the film formed is not smooth, so that fingerprints are not easily noticeable on the film surface after they are applied to the film surface.

In the water/oil repellent film-forming liquid composition according to the second aspect of the present invention, the first fluorine compound (A1) is contained in the same mass proportion as the second fluorine compound (A2) or in a larger amount than the second fluorine compound (A2), and therefore the binder component, silica sol-gel (C ), contains a small amount of fluorine components, resulting in excellent appearance and adhesion of the coating film.

In the liquid composition according to the third aspect of the present invention, the metal oxide particles used for the fluorine-containing metal oxide particles (B) are one or more types of metal oxide particles selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr, and therefore it is possible to include metal oxide particles suitable for the application or usage environment of the film to be formed from among the many types of metal oxide particles.

In the liquid composition according to the fourth aspect of the present invention, the fluorine-containing silica sol-gel contains 0.5% by mass to 20% by mass of an alkylene group component having 2 to 7 carbon atoms, and therefore the water- and oil-repellent film adheres well to the substrate on which it is formed, and the thickness of the water- and oil-repellent film becomes uniform, making it possible to impart even more excellent oil repellency to the water- and oil-repellent film.

In the liquid composition according to the fifth aspect of the present invention, the solvent (D) is a mixed solvent of water and an alcohol having 1 to 4 carbon atoms, or a mixed solvent of water, an alcohol having 1 to 4 carbon atoms, and an organic solvent other than this alcohol, so that the drying speed of the liquid composition is improved and the viscosity of the liquid composition is reduced. Therefore, this liquid composition is easy to handle and has excellent film-forming properties on a substrate.

In the method for producing a liquid composition according to the sixth aspect of the present invention, a liquid composition for forming a water- and oil-repellent film is produced by mixing a dispersion of fluorine-containing metal oxide particles (B) with a fluorine-containing silica sol-gel liquid (C) as shown in Fig. 1. As a result, metal oxide particles having water- and oil-repellent particle surfaces are present in a silica sol-gel containing a fluorine-based compound, and when the liquid composition is formed into a film, an even greater layer of water- and oil-repellency is imparted to the film.

In the method for producing a liquid composition according to the seventh aspect of the present invention, a fluorine-based compound is added and mixed into a dispersion of metal oxide particles, and water and a catalyst are then added and mixed into this mixture, thereby obtaining a dispersion in which the fluorine-containing metal oxide particles (B) are uniformly dispersed.

In the liquid composition production method according to the eighth aspect of the present invention, the metal oxide particles used for the fluorine-containing metal oxide particles (B) are one or more types of metal oxide particles selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr, so that it is possible to produce a liquid composition containing metal oxide particles suitable for the application or usage environment of the film to be formed, from among many types of metal oxide particles.

In the method for producing a liquid composition according to the ninth aspect of the present invention, the fluorine-containing silica sol-gel liquid (C) prepared by adding and mixing a catalyst to a mixed liquid of a silicon alkoxide, an alcohol, a fluorine-based compound and water acts as a binder for the fluorine-containing metal oxide particles, and when the liquid composition is formed into a film on the surface of a substrate, it firmly binds the film to the surface of the substrate and imparts further water and oil repellency to the film.

FIG. 2 is a flow diagram for producing the water- and oil-repellent film-forming liquid composition of the present embodiment. FIG. 2 is an enlarged cross-sectional view of a water- and oil-repellent film formed on a substrate according to the present embodiment.

Next, the embodiment of the present invention will be described with reference to the drawings.

[Method for producing water- and oil-repellent film-forming liquid composition]
The water- and oil-repellent film-forming liquid composition is generally produced by the following method.
As shown in Fig. 1, metal oxide particles 11 and an organic solvent 12 are mixed to prepare a dispersion liquid 13 of metal oxide particles. A fluorine-based compound 14 containing a first fluorine-based functional group component (A1) is mixed with this dispersion liquid 13, and water 15 and a catalyst 16 are further mixed to prepare a dispersion liquid 17 of fluorine-containing metal oxide particles. Meanwhile, a silicon alkoxide 21, an alcohol 22, a fluorine-based compound 23 containing a second fluorine-based functional group component (A2), water 25, and optionally an alkylene group component 24 are mixed, and a catalyst 26 is added to this mixture to prepare a fluorine-containing silica sol-gel liquid 27.
A solvent 28 is mixed with this fluorine-containing silica sol-gel liquid 27, and this mixture is mixed with the above-mentioned dispersion liquid 17 of fluorine-containing metal oxide particles to produce a water- and oil-repellent film-forming liquid composition 30. Each step will be described in detail below.

[Preparation of Metal Oxide Particle Dispersion]
First, the metal oxide particles are dispersed in an organic solvent to prepare a dispersion liquid of the metal oxide particles. The metal oxide particles have an average particle size of 2 nm to 90 nm, preferably 2 nm to 85 nm. If the average particle size is less than 2 nm, the metal oxide particles are likely to aggregate and are difficult to disperse in the medium. If the average particle size exceeds 90 nm, the metal oxide particles will fall off from the water-repellent and oil-repellent film when the liquid composition is formed into a film. Examples of the metal oxide particles include particles of SiO ₂ , Al ₂ O ₃ , MgO, CaO, TiO ₂ , ZnO, and ZrO ₂ , mixed particles of these, and composite oxide particles such as MgAl ₂ O ₄ .
Examples of organic solvents include methanol, ethanol, isopropanol (hereinafter sometimes referred to as IPA), tetrahydrofuran, hexane, chloroform, toluene, ethyl acetate, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, and fluorine-based solvents. Among these, alcohols having a boiling point of less than 120° C. and a carbon number in the range of 1 to 4, such as methanol, ethanol, and isopropanol, are preferred. In this specification, the average particle size of the metal oxide particles refers to the average value of the particle sizes of 200 points among the particle shapes observed with a transmission electron microscope (TEM) measured by image analysis.

[Preparation of Fluorine-Containing Metal Oxide Particle Dispersion]
Next, a fluorine-based compound containing the first fluorine-based functional group component (A1) represented by the above formula (1) or formula (2) is added to the prepared dispersion of metal oxide particles to synthesize a composite material in which the metal oxide particles and the first fluorine-based functional group component (A1) are nanocomposite. In order to further promote the reaction, water and a catalyst are added. In this way, a dispersion of fluorine-containing metal oxide particles is prepared.

The catalyst may be an organic acid, an inorganic acid, or a titanium compound. Examples of organic acids include formic acid and oxalic acid. Examples of inorganic acids include hydrochloric acid, nitric acid, and phosphoric acid. Examples of titanium compounds include titanium tetrapropoxide, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium lactate. The catalyst is not limited to the above. As the water, it is preferable to use ion-exchanged water or pure water to prevent the inclusion of impurities.

The fluorine-based compound containing the first fluorine-based functional group component (A1) is represented by the following general formula (3) or formula (4). More specifically, the perfluoroether group in formula (3) or formula (4) may be the perfluoroether structure represented by the following formulas (5) to (13).

In addition, examples of X in the above formulas (3) and (4) include structures shown in the following formulas (14) to (18). Note that the following formula (14) shows an example containing an ether bond, the following formula (15) an ester bond, the following formula (16) an amide bond, the following formula (17) a urethane bond, and the following formula (18) a sulfonamide bond.

In the above formulas (14) to (18), ^R2 and ^R3 are hydrocarbon groups having 0 to 10 carbon atoms, and ^R4 is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group for ^R3 include alkylene groups such as a methylene group and an ethylene group, and examples of the hydrocarbon group for ^R4 include alkyl groups such as a methyl group and an ethyl group, as well as a phenyl group.

In the above formulas (3) and (4), R ¹ may be a methyl group, an ethyl group, or the like.

In addition, in the above formulas (3) and (4), Z is not particularly limited as long as it is a hydrolyzable group that can be hydrolyzed to form a Si-O-Si bond. Specific examples of such hydrolyzable groups include alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy groups, aryloxy groups such as phenoxy and naphthoxy groups, aralkyloxy groups such as benzyloxy and phenethyloxy groups, and acyloxy groups such as acetoxy, propionyloxy, butyryloxy, valeryloxy, pivaloyloxy, and benzoyloxy groups. Among these, it is preferable to apply a methoxy group or an ethoxy group.

Specific examples of fluorine-based compounds containing the first fluorine-based functional group component (A1) having a perfluoroether structure represented by the above formula (3) or formula (4) include structures represented by the following formulas (19) to (27). In the following formulas (19) to (27), R is a methyl group or an ethyl group.

[Preparation of fluorine-containing silica sol-gel liquid]
First, a mixed solution is prepared by mixing tetramethoxysilane or tetraethoxysilane as silicon alkoxide, alcohol having a boiling point of less than 120° C. and a carbon number in the range of 1 to 4, a fluorine-based compound containing the second fluorine-based functional group component (A2) represented by the above formula (1) or formula (2), and water. At this time, an epoxy group-containing silane as an alkylene group component may be mixed together. Specific examples of this silicon alkoxide include tetramethoxysilane (TMOS) and its oligomers, or tetraethoxysilane (TEOS) and its oligomers. For example, in order to obtain a highly durable water-repellent and oil-repellent film, it is preferable to use tetramethoxysilane, while in order to avoid methanol generated during hydrolysis, it is preferable to use tetraethoxysilane.

The second fluorine-based functional group component (A2) contained in the fluorine-based compound is represented by the above-mentioned formula (1) or formula (2), and the specific fluorine-based compound containing the first fluorine-based functional group component (A1) and the specific fluorine-based compound containing the second fluorine-based functional group component (A2) may be the same or different.

Specific examples of the epoxy group-containing silane that is the alkylene group component include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and polyfunctional epoxysilane. The alkylene group component is contained in an amount of 1% to 40% by mass, preferably 2.5% to 20% by mass, based on the total mass of the silicon alkoxide and the alkylene group component. If the alkylene group component is less than the lower limit of 1% by mass, when a film is formed on a substrate that does not contain hydroxyl groups, the adhesion to the substrate becomes insufficient. If the amount exceeds the upper limit of 40% by mass, the durability of the formed film decreases. If the epoxy group-containing silane is included so that the alkylene group component falls within the above-mentioned range of 1% by mass to 40% by mass, the epoxy group also opens during the hydrolysis polymerization process and contributes to the polymerization, thereby improving the leveling property during the drying process and making the film thickness uniform. If the substrate contains a hydrophilic group such as glass, the content of the alkylene group component may be very small or may be zero. On the other hand, if the substrate does not contain a hydrophilic group, it is preferable that the alkylene group component is included in the silica sol-gel (C) at 0.5% by mass to 20% by mass.

Examples of alcohols having a carbon number of 1 to 4 and a boiling point of less than 120°C include the alcohols mentioned above. Methanol or ethanol are particularly preferred because these alcohols are easily mixed with silicon alkoxides. As the water, it is preferable to use ion-exchanged water or pure water to prevent the inclusion of impurities. A mixture is prepared by adding an alcohol having a carbon number of 1 to 4 and water to silicon alkoxide, or to silicon alkoxide and epoxy group-containing silane, and stirring for 5 to 20 minutes at a temperature of 10°C to 30°C.

A catalyst is added to the mixed liquid prepared above. Examples of the catalyst include an organic acid, an inorganic acid, or a titanium compound. At this time, the liquid temperature is preferably kept at 30°C to 80°C, and the mixture is stirred for preferably 1 hour to 24 hours. This prepares a fluorine-containing silica sol-gel liquid. Note that alcohol may be added to the fluorine-containing silica sol-gel liquid for the next step.

When the above alcohol is added and mixed, the fluorine-containing silica sol-gel liquid contains 2% by mass to 50% by mass of silicon alkoxide, 20% by mass to 98% by mass of alcohol having 1 to 4 carbon atoms, 0.1% by mass to 40% by mass of water, and 0.01% by mass to 5% by mass of catalyst. When an epoxy group-containing silane, which is an alkylene group component, is mixed, the epoxy group-containing silane can be contained up to a maximum of 30% by mass.

The proportion of alcohol having 1 to 4 carbon atoms is limited to the above range because if the proportion of alcohol is less than the lower limit, the silicon alkoxide does not dissolve in the solution and separates, and the reaction liquid is prone to gelling during the hydrolysis reaction of the silicon alkoxide, while if the proportion exceeds the upper limit, the amount of water and catalyst required for hydrolysis becomes relatively small, which reduces the reactivity of the hydrolysis, prevents polymerization, and reduces the adhesion of the film. The proportion of water is limited to the above range because if the proportion is less than the lower limit, the hydrolysis rate becomes slow, which prevents polymerization from proceeding and results in insufficient adhesion of the water- and oil-repellent film, while if the proportion exceeds the upper limit, the reaction liquid gels during the hydrolysis reaction, and the silicon alkoxide compound does not dissolve in the alcohol aqueous solution due to the excessive water, resulting in the problem of separation.

The _SiO2 concentration ( _SiO2 content) in the silica sol-gel is preferably 1% by mass to 40% by mass. If the _SiO2 concentration is less than the lower limit, polymerization is insufficient, and the adhesion of the film is reduced and cracks are likely to occur, while if the SiO2 concentration exceeds the upper limit, the proportion of water becomes relatively high, silicon alkoxide does not dissolve, and the reaction solution gels.

The organic acid, inorganic acid, or titanium compound functions as a catalyst to promote the hydrolysis reaction. Examples of organic acids include formic acid and oxalic acid, examples of inorganic acids include hydrochloric acid, nitric acid, and phosphoric acid, and examples of titanium compounds include tetrapropoxytitanium, tetrabutoxytitanium, tetraisopropoxytitanium, and titanium lactate. The catalyst is not limited to the above. The proportion of the catalyst is limited to the above range because if it is less than the lower limit, the reactivity is poor and polymerization is insufficient, so a film is not formed, while if it exceeds the upper limit, there is no effect on reactivity, but the substrate on which the film is formed is prone to corrosion due to the remaining acid.

[Water- and oil-repellent film-forming liquid composition]
The water- and oil-repellent film-forming liquid composition of the present embodiment is produced by the above-mentioned production method, and contains metal oxide particles (B) to which the first fluorine-based functional group component (A1) is bonded, silica sol-gel (C) containing the second fluorine-based functional group component (A2), and a solvent (D) (indicated by reference numeral 28 in FIG. 1). Examples of the solvent (D) include water, methanol, ethanol, isopropanol (hereinafter sometimes referred to as IPA), tetrahydrofuran, hexane, chloroform, toluene, ethyl acetate, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, and fluorine-based solvents. These fluorine-based functional group components (A1) and (A2) have a perfluoroether structure represented by the above general formula (1) or formula (2), and are contained in the liquid composition in a total amount of 1% by mass to 30% by mass when the total amount of all components excluding the solvent (D) is taken as 100% by mass. If the total content ratio of the fluorine-based functional group components (A1+A2) is less than 1 mass%, the formed film cannot be imparted with oil repellency, and if it exceeds 30 mass%, the film repels, etc., resulting in poor film-forming properties. The total content ratio of the fluorine-based functional group components (A1+A2) is preferably 2 mass% to 28 mass%.

In addition, it is preferable that the first fluorine functional group component (A1) is contained in the same mass proportion as the second fluorine functional group component (A2) or in a larger amount than the second fluorine functional group component (A2), since this leads to excellent appearance and adhesion of the coating film.

As described above, the fluorine-based compound contained in the water- and oil-repellent film-forming liquid composition of this embodiment has a perfluoroether group in which multiple short-chain perfluoroalkyl groups and perfluoroalkylene groups having 6 or less carbon atoms are bonded to an oxygen atom in the molecule, and the high fluorine content in the molecule can impart excellent water- and oil-repellency to the formed film. Specific examples of perfluoroether structures include the structures shown by the above formulas (19) to (27).

Furthermore, in the liquid composition for forming a water- and oil-repellent film of this embodiment, the mass ratio (C:B) of silica sol-gel (C) to metal oxide particles (B) must be in the range of 10:90 to 90:10. That is, when the total amount of silica sol-gel (C) and metal oxide particles (B) is taken as 100 mass%, if the amount of silica sol-gel (C) is less than 10 mass% and the amount of metal oxide particles (B) is more than 90 mass%, the binder component in the liquid composition becomes too small, and the formed film is easily peeled off from the substrate in the Cellophane Tape (registered trademark) test of the film described below. On the other hand, if the amount of metal oxide particles (B) is less than 10 mass% and the amount of silica sol-gel (C) is more than 90 mass%, the amount of metal oxide particles is too small, and the film is easily peeled off from the substrate in the film strength test described below. The preferred mass ratio (C:B) is 20:80 to 80:20.

The liquid composition for forming a water- and oil-repellent film of this embodiment contains a dispersion of fluorine-containing metal oxide particles and a fluorine-containing silica sol-gel liquid, and therefore when formed on the surface of a substrate, it imparts even better oil repellency than conventional liquid compositions, and also provides a water- and oil-repellent film with excellent adhesion to the substrate surface and high strength that is difficult to peel off.

[Method of forming a water-repellent and oil-repellent film on a substrate surface]
To form the water-repellent and oil-repellent film on the surface of a substrate, the water-repellent and oil-repellent film-forming liquid composition is applied to the substrate, and then dried at room temperature in the air to harden the liquid composition.The substrate is not particularly limited, but includes metal plates such as stainless steel (SUS), aluminum, and iron, glass such as window glass and mirror, tiles, plastics such as polyvinyl chloride (PVC), and polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate.The coating method of the liquid composition includes screen printing, bar coating, die coating, doctor blade, spin coating, brush coating, and the like.

As shown in FIG. 2, the water- and oil-repellent film 2 formed on the surface of the substrate 1 is composed of a large number of metal oxide particles 3 whose particle surfaces are covered with fluorine-based functional group components and bound together by fluorine-containing silica sol-gel 4 as a binder. The water- and oil-repellent film 2 contains metal oxide particles 3 bound to fluorine-based functional group components and fluorine-containing silica sol-gel 4, so the oil-repellent performance of the film is maintained. In addition, the metal oxide particles 3 with an average particle size of 2 nm to 90 nm are bound together in the film 2 by the silica sol-gel 4, so the hardness and abrasion resistance of the film 2 can be improved. In addition, the presence of the metal oxide particles 3 makes the film surface uneven, which has the advantage that fingerprints are less noticeable on the film surface after they are attached to the film 2 surface. The film thickness can be controlled by changing the particle size of the metal oxide particles and the content ratio of the metal oxide particles in the film components.

Next, examples of the present invention will be described in detail together with comparative examples. First, Synthesis Examples 1 to 9 and Comparative Synthesis Examples 1 and 2 for preparing a dispersion liquid of metal oxide particles will be described, followed by Synthesis Examples 10 to 13 and Comparative Synthesis Example 3 for preparing a fluorine-containing silica sol-gel liquid, and then Examples 1 to 9 and Comparative Examples 1 to 7 for producing a water- and oil-repellent film-forming liquid composition using these Synthesis Examples and Comparative Synthesis Examples will be described.

[Synthesis Examples 1 to 9 for preparing metal oxide particle dispersion liquid, and Comparative Synthesis Examples 1 to 2]
<Synthesis Example 1>
To a beaker containing 50.0 g of an IPA dispersion of silicon dioxide having an average particle size of 12 nm (IPA-ST, manufactured by Nissan Chemical Industries, Ltd., _SiO2 concentration 30%), 1.50 g of the fluorine-based compound represented by the above formula (19) was added and mixed. Next, 0.10 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the mixture was mixed at 40° C. for 2 hours to obtain a dispersion of silicon dioxide (silica) particles in which the fluorine-based compound is bonded to the silicon dioxide particles.

<Synthesis Example 2>
1.50 g of the fluorine-based compound represented by the above formula (20) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of silicon dioxide having an average particle size of 45 nm (IPA-ST-L, manufactured by Nissan Chemical Industries, Ltd., _SiO2 concentration 30%). Next, 0.10 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of silicon dioxide (silica) particles.

<Synthesis Example 3>
1.50 g of the fluorine-based compound represented by the above formula (21) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of silicon dioxide having an average particle size of 80 nm (IPA-ST-ZL, manufactured by Nissan Chemical Industries, Ltd., _SiO2 concentration 30%). Next, 0.10 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of silicon dioxide (silica) particles.

<Synthesis Example 4>
0.75 g of the fluorine-based compound represented by the above formula (22) was added and mixed into a beaker containing 50.0 g of the same silicon dioxide IPA dispersion as in Synthesis Example 3. Next, 0.05 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of silicon dioxide (silica) particles.

<Synthesis Example 5>
2.25 g of the fluorine-based compound represented by the above formula (23) was added and mixed into a beaker containing 50.0 g of the same silicon dioxide IPA dispersion as in Synthesis Example 3. Next, 0.15 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of silicon dioxide (silica) particles.

<Synthesis Example 6>
In a beaker containing 50.0 g of a methanol dispersion of zirconium dioxide having an average particle size of 3 nm (SZR-M, manufactured by Sakai Chemical Industry Co., Ltd., _ZrO2 concentration 30%), 8.00 g of the fluorine-based compound represented by the above formula (27) was added and mixed. Next, 4.05 g of water was added and mixed. Furthermore, 0.035 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of zirconium dioxide particles.

<Synthesis Example 7>
2.70 g of the fluorine-based compound represented by the above formula (27) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of _titanium dioxide having an average particle size of 6 nm (TKD-701, manufactured by Teika Corporation, TiO2 concentration 18%). Next, 0.97 g of water was added and mixed. Furthermore, 0.010 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of titanium dioxide particles.

<Synthesis Example 8>
0.03 g of the fluorine-based compound represented by the above formula (27) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of alumina and silicon dioxide having an average particle size of 60 nm ( _Baylal AS- _L10 , manufactured by Taki Chemical Industry Co., Ltd., _3Al2O3.2SiO2 concentration 10%). Next, 0.02 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of alumina and silicon dioxide particles.

<Synthesis Example 9>
0.30 g of the fluorine-based compound represented by the above formula (27) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of zinc oxide having an average particle size of 25 nm (MZ-500, manufactured by Teika Corporation, ZnO concentration 30%). Next, 0.11 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of zinc oxide particles.

Comparative Synthesis Example 1
0.75 g of the fluorine-based compound represented by the above formula (27) was added and mixed into a beaker containing 50.0 g of an IPA dispersion of _titanium dioxide having an average particle size of 230 nm (R32, manufactured by Sakai Chemical Industry Co., Ltd., TiO2 concentration 30%). Next, 0.27 g of water was added and mixed. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of titanium dioxide particles.

Comparative Synthesis Example 2
To a beaker containing 50.0 g of the same IPA dispersion as in Synthesis Example 1, 0.10 g of water was added and mixed without adding any fluorine-based compound. Furthermore, 0.005 g of nitric acid was added, and the same procedure as in Synthesis Example 1 was repeated to obtain a dispersion of silicon dioxide particles.

The following Table 1 shows the contents of the dispersions of fluorine-containing metal oxide particles in Synthesis Examples 1 to 9 and Comparative Synthesis Example 1, and the dispersion of fluorine-free metal oxide particles in Comparative Synthesis Example 2. In Table 1, the R in the formulas of the fluorine-containing silanes represented by formulas (19) to (22) and (27) as fluorine-based compounds is all an ethyl group.

[Synthesis Examples 10 to 13 for preparing fluorine-containing silica sol-gel liquid, and Comparative Synthesis Example 3]
<Synthesis Example 10>
0.24 g (0.8 mass%) of the fluorine-based compound represented by the above formula (27) was added to a beaker containing 28.5 g of trimer to pentamer of tetramethoxysilane (TMOS) (manufactured by Mitsubishi Chemical Corporation, product name: MKC Silicate MS51) and 59.7 g of ethanol, and mixed. Next, 1.5 g of 3-glycidoxypropyltrimethoxysilane (GPTMS: manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM-403), which is an epoxy group-containing silane as an alkylene group component, and 10 g of water were added and mixed. Furthermore, 0.1 g of nitric acid was added, and the mixture was mixed at 30° C. for 3 hours to obtain a fluorine-containing silica sol-gel liquid.

<Synthesis Example 11>
To a beaker containing 24.0 g of the same TMOS trimer to pentamer as in Synthesis Example 10 and 59.7 g of ethanol, 0.06 g (0.2 mass%) of the fluorine-based compound represented by the above formula (27) was added and mixed. Next, 6.0 g of the same GPTMS as in Synthesis Example 10 as an alkylene group component and 10 g of water were added and mixed. Furthermore, 0.1 g of nitric acid was added and mixed at 30° C. for 3 hours to obtain a fluorine-containing silica sol-gel liquid.

<Synthesis Example 12>
To a beaker containing 29.8 g of the same TMOS trimer to pentamer as in Synthesis Example 10 and 59.8 g of ethanol, 3.00 g (10.0 mass%) of the fluorine-based compound represented by the above formula (27) was added and mixed. Next, 0.2 g of the same GPTMS as in Synthesis Example 10 as an alkylene group component and 10 g of water were added and mixed. Furthermore, 0.1 g of nitric acid was added and mixed at 30° C. for 3 hours to obtain a fluorine-containing silica sol-gel liquid.

<Synthesis Example 13>
0.30 g (1.0 mass%) of the fluorine-based compound represented by the above formula (27) was added to a beaker containing 30.0 g of tetraethoxysilane (TEOS) and 56.9 g of ethanol, and mixed. Next, 10 g of water was added without adding any alkylene group component, and mixed. Furthermore, 0.1 g of nitric acid was added, and mixed at 30° C. for 3 hours to obtain a fluorine-containing silica sol-gel liquid.

Comparative Synthesis Example 3
To a beaker containing 28.5 g of the same TMOS trimer to pentamer as in Synthesis Example 11 and 59.6 g of ethanol, 1.5 g of the same GPTMS as in Synthesis Example 10 as an alkylene group component and 10 g of water were added and mixed without adding any fluorine-based compound. Furthermore, 0.1 g of nitric acid was added and mixed at 30° C. for 3 hours to obtain a fluorine-free silica sol-gel liquid.

Table 2 below shows the contents of the fluorine-containing silica sol-gel liquids of Synthesis Examples 10 to 13 and the fluorine-free silica sol-gel liquid of Comparative Synthesis Example 3.

[Examples 1 to 9 and Comparative Examples 1 to 7 for the production of water- and oil-repellent film-forming liquid compositions]
Example 1
26.0 g of a solvent was added to 1.9 g of the fluorine-containing silica sol-gel liquid obtained in Synthesis Example 10 and mixed. The solvent was prepared by mixing 1.0 g of diacetone alcohol and 3.0 g of isopropyl glycol with 22.0 g of industrial alcohol (AP-7, manufactured by Japan Alcohol Industry Co., Ltd.). Then, 1.5 g of the dispersion of metal oxide particles of Synthesis Example 1 was added and mixed to prepare a water- and oil-repellent film-forming liquid composition. The details are shown in Table 3 below.

<Examples 2 to 9 and Comparative Examples 1 to 7>
For Examples 2 to 9 and Comparative Examples 1 to 7, the type and weight of the dispersion liquid of the fluorine-containing metal oxide particles, the type and weight of the fluorine-containing silica sol-gel liquid, and the weight of the same solvent as in Example 1 were determined as shown in Table 3, and the water- and oil-repellent film-forming liquid compositions of Examples 2 to 9 and Comparative Examples 1 to 7 were prepared.

<Comparative testing and evaluation>
The 16 types of liquid compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 7 were applied to a SUS304 substrate having a thickness of 2 mm, a length of 150 mm, and a width of 75 mm using a brush (Nylon Brush Meister manufactured by Suematsu Brush Co., Ltd.) so that the thickness after drying was 1 to 3 μm, and 16 types of coating films were formed. All coating films were left to stand in an atmospheric atmosphere at room temperature for 3 hours, and the coating films were dried to obtain 16 types of films on the SUS304 substrate. For these films, the water wettability (water repellency), oil repellency, n-hexadecane sliding property, and appearance of the film were evaluated, and a film strength test, a cellophane tape peeling test, and a fingerprint resistance test were performed. The results are shown in Table 4. The fingerprint resistance of the film is a property in which fingerprints are not easily noticeable on the film surface after they are attached to the film, and fingerprints are easily wiped off when they are attached, and fingerprints are not easily attached to the film.

(1) Water repellency of the film surface (contact angle)
Using a Dropmaster DM-700 manufactured by Kyowa Interface Science, ion-exchanged water at 22°C ± 1°C was prepared in a syringe, and a 2μL droplet was ejected from the tip of the needle of the syringe. The film on the SUS304 substrate to be evaluated was then brought close to the droplet, and the droplet was attached to the film. The contact angle of the attached water was measured. The contact angle after 1 second when the water touched the film surface in a stationary state was analyzed by the θ/2 method, and the water wettability (water repellency) of the film surface was evaluated. If it was 84 degrees or more, it was rated as "good".

(2) Oil repellency of the film surface (contact angle)
Using a Dropmaster DM-700 manufactured by Kyowa Interface Science, n-hexadecane at 22°C±1°C was prepared in a syringe, and a 2μL droplet was ejected from the tip of the needle of the syringe. Next, the film on the SUS304 substrate to be evaluated was brought close to the droplet, and the droplet was attached to the film. The contact angle of the attached n-hexadecane was measured. The contact angle 1 second after n-hexadecane touched the film surface in a stationary state was analyzed by the θ/2 method, and the value was taken as the contact angle of n-hexadecane, and the oil repellency of the film surface was evaluated. If it was 42 degrees or more, it was rated as "good".

(3) n-Hexadecane sliding test Using a Kyowa Interface Science Dropmaster DM-700, n-hexadecane at 25±1°C was prepared in a syringe, and 9 μL of n-hexadecane was dropped from the syringe onto a horizontally placed polypropylene substrate. The substrate was tilted at a rate of 2 degrees/min, and the tilt angle of the substrate was measured when the n-hexadecane droplet began to move. Even if the contact angle in (2) is low, a smaller sliding angle means better antifouling properties. If it was 50 degrees or less, it was rated as "good." In addition, if there was a trace of the droplet on the surface of the substrate after the n-hexadecane droplet moved and fell off the substrate, it was rated as "oil stains present."

(4) Appearance of the film The film on the SUS304 substrate to be evaluated was visually observed to check whether the film was transparent or not, and whether the film was cloudy or not. A transparent film was rated as "good", and a cloudy film was rated as "bad cloudiness".

(5) Film strength test The contactor described below was applied with a specified load to the film on the SUS304 substrate to be evaluated, and after 10 reciprocating movements under the following conditions, the film on the substrate was visually inspected for peeling from the substrate. If the film did not peel off, it was judged as "passed", and if it peeled off, it was judged as "failed".
(a) Measuring instrument: Static and dynamic friction measuring instrument TL201Tt (Trinity Lab Co., Ltd.)
(b) Measurement conditions:
・Traveling distance: 30mm
Vertical load: 500 g; Movement speed: 50 mm/sec.; Contact: 5 mm x 15 mm square neoprene rubber

(6) Cellotape (registered trademark) peeling test of film A 1 mm wide cross cut was made in a grid pattern on the film on the SUS304 substrate to be evaluated, and an adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") was applied to the cross cut film in the grid pattern, and a Cellotape (registered trademark) peeling test (hereinafter simply referred to as peeling test) was performed in accordance with the grid tape method of JIS K5600-5-6 (cross cut method). The denominator was the number of 100 cross cut squares, and the numerator was the number of squares remaining on the substrate after the peel test.

(6) Fingerprint resistance test of film A continuous cellulose fiber nonwoven fabric (manufactured by Asahi Kasei Corporation, product name: BEMCOT M-3II) was placed on the film on the SUS304 substrate to be evaluated, and 100 microliters of artificial fingerprint liquid (based on JIS K 2246) was dropped onto the nonwoven fabric. Black rubber No. 24 (mass 300 g) was placed on the nonwoven fabric, and a weight of 1 kg was placed on top. The film was left to stand for 30 seconds to allow the fingerprint liquid to adhere to the film. The nonwoven fabric was then peeled off, and the fingerprint resistance of the film was visually observed. Films that had no fingerprint liquid on the surface were rated as "good", and films that had fingerprint liquid on the surface were rated as "poor".

As is clear from Table 4, in Comparative Example 1, a liquid composition for forming a water- and oil-repellent film was prepared from a dispersion of titanium dioxide particles in Comparative Synthesis Example 1, which contained metal oxide (titanium dioxide) particles with an average particle diameter of 230 nm, and a film was formed using this liquid composition. As a result, the average particle diameter of the metal oxide particles in the film was too large, and the metal oxide particles were difficult to bind to the substrate surface with the silica sol-gel binder component. As a result, the contact angles of water and n-hexadecane were poor, the film was cloudy, and the appearance of the film was poor. In addition, in the strength test of the film, the film peeled off from the substrate, and in the peel test, only 20 squares remained on the substrate, with most peeling off. Furthermore, the fingerprint resistance of the film was poor.

In Comparative Example 2, a liquid composition for forming a water- and oil-repellent film was prepared from the silica sol-gel liquid of Comparative Synthesis Example 3, which does not contain a fluorine-based compound, and a film was formed using this liquid composition, resulting in a poor sliding angle of n-hexadecane.

In Comparative Example 3, when the total amount of silica sol-gel (C) and metal oxide particles (B) is taken as 100% by mass, the amount of silica sol-gel (C) was 5% by mass, so the binder component in the liquid composition was too little, and in the film peeling test, only 10 squares remained on the substrate, with most peeling off. In addition, the n-hexadecane had a poor sliding angle and was "oil stained." The film was also cloudy and had a poor appearance. Furthermore, the film had poor fingerprint resistance.

In Comparative Example 4, when the total amount of the silica sol-gel (C) and the metal oxide particles (B) was taken as 100 mass %, the metal oxide particles (B) were 5 mass %, so the amount of metal oxide particles in the liquid composition was too small, and the film peeled off from the substrate in the film strength test. Furthermore, the fingerprint resistance of the film was poor.

In Comparative Example 5, the combined content (A1+A2) of the fluorine-based functional group component (A1) and the fluorine-based functional group component (A2) was 0.8% by mass, so the formed film could not be imparted with oil repellency, the contact angles of water and n-hexadecane were poor, and the n-hexadecane sliding angle test showed "oil stains." Furthermore, the film had poor fingerprint resistance.

In Comparative Example 6, the combined content (A1+A2) of the fluorine-based functional group component (A1) and the fluorine-based functional group component (A2) was 33.4% by mass, so the formed film could not be imparted with oil repellency, and the n-hexadecane sliding angle test showed a value of 70 degrees. In addition, the film was cloudy and had a poor appearance. Furthermore, the film had poor fingerprint resistance.

In Comparative Example 7, a liquid composition for forming a water- and oil-repellent film was prepared from a dispersion of metal oxide particles of Comparative Synthesis Example 2 that did not contain a fluorine-based compound, and a film was formed using this liquid composition. As a result, the contact angles of water and n-hexadecane were poor, and the n-hexadecane sliding angle test showed "oil stains." Furthermore, the fingerprint resistance of the film was poor.

In contrast, in Examples 1 to 9, the first and second fluorine-based functional group components (A1, A2) are represented by the above formulas (19) to (23) and (27), the average particle size of the metal oxide particles is in the range of 2 nm to 90 nm, the total content (A1+A2) of the first and second fluorine-based functional group components (A1, A2) in the liquid composition excluding the solvent (D) is 1% by mass to 30% by mass, and the mass ratio (C:B) of the silica sol-gel (C) to the metal oxide particles (B) is in the range of 10:90 to 90:10, which satisfies the scope of the invention of the first aspect. Therefore, the contact angles of water and n-hexadecane, the sliding properties of n-hexadecane, and the appearance of the film are all good, and the film strength test, peel test, and fingerprint resistance test all passed.

The water- and oil-repellent film-forming liquid composition of the present invention is used in fields where oil stains need to be prevented, such as in factories where machine oil is used, in kitchens where oil is scattered, and on range hoods, ventilation fans, refrigerator doors, and other areas where oil vapor is present.

1 Substrate 2 Water- and oil-repellent film 3 Metal oxide particles 4 Silica sol-gel

Claims (9)

Fluorine- containing metal oxide particles (B) having an average particle size of 2 nm to 90 nm and to which a first fluorine-based compound (A1) containing a perfluoroether structure is bonded , the first fluorine-based compound (A1) being represented by any one of the following formulas (19) to (27):
A fluorine-containing silica sol-gel (C) containing a second fluorine-based compound (A2) having a perfluoroether structure represented by any one of the following formulas (19) to (27) :
A solvent (D),
the total content of the first fluorine compound (A1) and the second fluorine compound (A2) is 1% by mass to 30% by mass when the total amount of all components excluding the solvent (D) is 100% by mass,
A water- and oil-repellent film-forming liquid composition, characterized in that a mass ratio (C:B) of the fluorine-containing silica sol-gel (C) to the fluorine-containing metal oxide particles (B) is in the range of 10:90 to 90:10.

In the above formulas (19) to (27), R is a methyl group or an ethyl group . 2. The water/oil repellent film forming liquid composition according to claim 1, wherein the content ratio of the first fluorine compound (A1) is equal to or greater than the content ratio of the second fluorine compound (A2) in terms of mass ratio. 2. The water- and oil-repellent film-forming liquid composition according to claim 1, wherein the metal oxide particles used for the fluorine-containing metal oxide particles (B) are oxide particles of one or more metals selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr. 2. The water- and oil-repellent film-forming liquid composition according to claim 1, wherein the fluorine-containing silica sol-gel (C) contains an alkylene group component having 2 to 7 carbon atoms in an amount of 0.5% by mass to 20% by mass when the fluorine-containing silica sol-gel (C) is taken as 100% by mass. The water- and oil-repellent film-forming liquid composition according to claim 1, wherein the solvent (D) is a mixed solvent of water and an alcohol having 1 to 4 carbon atoms, or a mixed solvent of water, an alcohol having 1 to 4 carbon atoms, and an organic solvent other than the alcohol. A method for producing the water- and oil-repellent film-forming liquid composition according to claim 1, comprising the steps of:
A method for producing a water- and oil-repellent film-forming liquid composition, which is prepared by mixing a dispersion of fluorine-containing metal oxide particles (B) and a fluorine-containing silica sol-gel liquid (C) . 7. The method for producing a water- and oil-repellent film-forming liquid composition according to claim 6, wherein the dispersion of the fluorine-containing metal oxide particles (B) is prepared by adding and mixing the fluorine-based compound (A1) to a dispersion of the metal oxide particles, and then adding and mixing water and a catalyst to the mixture. 8. The method for producing a water- and oil-repellent film-forming liquid composition according to claim 7, wherein the metal oxide particles used for the fluorine-containing metal oxide particles (B) are oxide particles of one or more metals selected from the group consisting of Si, Al, Mg, Ca, Ti, Zn and Zr. 7. The method for producing a water- and oil-repellent film-forming liquid composition according to claim 6, wherein the fluorine-containing silica sol-gel liquid (C) is prepared by adding a catalyst to a mixed liquid of a silicon alkoxide, an alcohol, a fluorine-based compound (A2) and water.

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