WO2024162205A1

WO2024162205A1 - Water- and oil-repellent agent, and article

Info

Publication number: WO2024162205A1
Application number: PCT/JP2024/002399
Authority: WO
Inventors: 遼平吉田; 智之朝日; 峻義島田
Original assignee: 信越化学工業株式会社
Priority date: 2023-02-01
Filing date: 2024-01-26
Publication date: 2024-08-08
Also published as: TW202448980A

Abstract

This water- and oil-repellent agent contains a polymer of a monomer represented by general formula (I) (in the formula, R represents a hydrogen atom, a halogen atom, an alkyl group, or an aryl group, X represents a single bond or a substituted or unsubstituted divalent hydrocarbon group optionally including one or more selected from an oxygen atom, an amino bond, an amide bond, a urethane bond, and a urea bond, and Rf represents a monovalent fluoropolyether group that has a molecular weight of 1,000-5,000 and that has the terminal thereof blocked with a perfluoro alkyl group having not more than 5 carbon atoms). The water- and oil-repellent agent exhibits excellent water- and oil-repellency not only at an initial stage but also under heat-resistant conditions even though the number of carbon atoms in the perfluoro alkyl group is less than 6 (not more than 5).

Description

Water and oil repellents and articles

The present invention relates to a water/oil repellent and an article that contains a fluorine-containing polymer as an active ingredient. More specifically, the present invention relates to a water/oil repellent that contains a polymer of an acrylic monomer that contains a fluoropolyether group as an active ingredient, and an article that has a coating of the water/oil repellent on its surface.

　Conventionally, to provide surface modification functions such as water and oil repellency to substrates, polymers of fluorine-based acrylic or methacrylic monomers have been applied, as shown in Patent Document 1 (JP Patent Publication No. 1-42983) and Patent Document 2 (JP Patent Publication No. 7-109317).

Long-chain perfluoroalkyl groups with eight or more carbon atoms have been used to achieve surface modification functions such as high-level water and oil repellency. However, it has been pointed out that long-chain perfluorocarboxylic acids with perfluoroalkyl groups with eight or more carbon atoms, such as perfluorooctanoic acid (PFOA), have a tendency to accumulate in the human body.

To reduce the risk to living organisms and the environment, PFOA has been replaced with, for example, perfluorohexanoic acid (PFHxA), which has six carbon atoms. For example, Patent Document 3 (JP Patent Publication 2020-050757 A) discloses a surface modifier whose active ingredient is a polymer of a (meth)acrylic acid derivative containing a perfluoroalkyl group with six carbon atoms.

However, similar risks remain a concern for PFHxA.

Special Publication No. 1-42983 Japanese Patent Application Publication No. 7-109317 JP 2020-050757 A

The present invention has been made in consideration of the above circumstances, and aims to provide a water/oil repellent that has a perfluoroalkyl group with less than 6 carbon atoms (5 or less) and yet exhibits good water/oil repellency not only initially but also under heat-resistant conditions, and an article having a coating of the water/oil repellent on its surface.

As a result of intensive research conducted by the inventors to achieve the above object, they discovered that a water/oil repellent agent containing a polymer obtained by polymerizing an acrylic acid ester monomer having a specific linker structure and a monovalent fluoropolyether group with a molecular weight of 1,000 to 5,000, the end of which is capped with a perfluoroalkyl group having 5 or less carbon atoms, maintains good water/oil repellency not only in the initial state but also under heat-resistant conditions, thereby completing the present invention.

Accordingly, the present invention provides the following water/oil repellent and article.
[1]
The following general formula (I)

(In the formula, R is a hydrogen atom, a halogen atom, an alkyl group or an aryl group; X is a single bond, or an unsubstituted or substituted divalent hydrocarbon group which may contain one or more bonds selected from an oxygen atom, an amino bond, an amide bond, a urethane bond and a urea bond; and Rf is a monovalent fluoropolyether group having a molecular weight of 1,000 to 5,000 and end-capped with a perfluoroalkyl group having 5 or less carbon atoms.)
A water- and oil-repellent agent comprising a polymer of a monomer represented by the formula:
[2]
The water/oil repellent according to [1], wherein R in the general formula (I) is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, or a phenyl group.
[3]
The water/oil repellent according to [1] or [2], wherein X in the general formula (I) is any one selected from a single bond, an unsubstituted or substituted alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, and structures represented by the following general formulas (1) to (5):

(In each of formulas (1) to (5), the site indicated by * is the site of bonding to the oxygen atom in general formula (I), and the site indicated by ** is the site of bonding to the Rf group in general formula (I).)
[4]
The water/oil repellent according to any one of [1] to [3], wherein the Rf group in the general formula (I) is represented by the following general formula (7) or (8):

(In the formula, n is an integer from 5 to 28.)

(In the formula, p is an integer of 0 to 41, and q is an integer of 0 to 73, which satisfies p+q=8 to 73. Each repeating unit shown in parentheses with p and q may be bonded randomly.)
[5]
The water- and oil-repellent agent according to any one of [1] to [4], which gives a coating having a water contact angle of 115° or more when applied to a glass plate.
[6]
The water/oil repellent according to any one of [1] to [5], which gives a coating having a hexadecane contact angle of 75° or more when applied to a glass plate.
[7]
The water/oil repellent according to any one of [1] to [6], which gives a coating having an oil repellency of grade 7 or higher according to AATCC test method 118-2020 when applied to a substrate, and whose oil repellency after heating at 150°C for 100 hours does not decrease from the initial oil repellency.
[8]
The water/oil repellent according to any one of [1] to [7], wherein the substrate to which the water/oil repellent is applied is a fiber or a porous film.
[9]
The water/oil repellent according to [8], wherein the porous membrane is made of PTFE (polytetrafluoroethylene).
[10]
An article having a coating film of the water/oil repellent according to any one of [1] to [9] on its surface.

The water- and oil-repellent agent of the present invention has a perfluoroalkyl group portion with less than 6 carbon atoms (5 or less), yet exhibits good water- and oil-repellency not only initially but also under heat-resistant conditions, and can provide an article having a coating of the water- and oil-repellent agent on its surface.

The water/oil repellent of the present invention contains a polymer of a monomer represented by the following general formula (I).

(In the formula, R is a hydrogen atom, a halogen atom, an alkyl group or an aryl group; X is a single bond, or an unsubstituted or substituted divalent hydrocarbon group which may contain one or more bonds selected from an oxygen atom, an amino bond, an amide bond, a urethane bond and a urea bond; and Rf is a monovalent fluoropolyether group having a molecular weight of 1,000 to 5,000 and end-capped with a perfluoroalkyl group having 5 or less carbon atoms.)

In the general formula (I), R is a hydrogen atom, a halogen atom, an alkyl group, or an aryl group. Examples of the halogen atom, alkyl group, or aryl group include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, and a phenyl group. R is preferably a hydrogen atom or a methyl group.

In the general formula (I), X is a single bond, or an unsubstituted or substituted divalent hydrocarbon group which may contain one or more bonds selected from oxygen atoms, amino bonds, amide bonds, urethane bonds, and urea bonds, and is a linking group (linker) between the Rf group and the oxygen atom at the acrylic acid ester terminal. Examples of unsubstituted or substituted divalent hydrocarbon groups which may contain one or more bonds selected from oxygen atoms, amino bonds, amide bonds, urethane bonds, and urea bonds include alkylene groups such as methylene groups, ethylene groups, propylene groups (trimethylene groups, methylethylene groups), butylene groups (tetramethylene groups, methylpropylene groups), hexamethylene groups, octamethylene groups, and the like, arylene groups such as phenylene groups, and combinations of two or more of these groups (alkylene-arylene groups, etc. ) and the like, and the divalent hydrocarbon group having 1 to 20 carbon atoms may contain one or more bonds selected from an ether bond (-O-(oxygen atom)), an amino bond (-NH-), an amide bond (-C(=O)NH-), a urethane bond (-OC(=O)NH-) and a urea bond (-NHC(=O)NH-), or may be a substituted divalent hydrocarbon group in which some or all of the hydrogen atoms bonded to the carbon atom are replaced with halogen atoms such as fluorine or iodine. The divalent hydrocarbon group having 1 to 20 carbon atoms may contain a bond in which two amide bonds are repeated.

X is preferably any one of a single bond, an unsubstituted or substituted alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, and the structures represented by the following general formulas (1) to (5).

(In each of formulas (1) to (5), the site indicated by * is the site of bonding to the oxygen atom in general formula (I), and the site indicated by ** is the site of bonding to the Rf group in general formula (I).)

In the general formula (I), Rf is a monovalent fluoropolyether group having a molecular weight of 1,000 to 5,000 and end-capped with a perfluoroalkyl group having 5 or less carbon atoms, preferably a monovalent perfluoropolyether group having a molecular weight of 1,000 to 5,000, and more preferably one containing a repeating unit represented by the following general formula (6):

(In the formula, a is a positive number from 0 to 28, b is a positive number from 0 to 41, and c is a positive number from 0 to 73, and these numbers satisfy a+b+c=5 to 73. The repeating units shown in parentheses with a, b, and c may be bonded randomly.)

Examples of the repeating unit represented by the general formula (6) include units represented by the following formulas:

Among these, the repeating units represented by the following formula are particularly preferred.

Rf (monovalent fluoropolyether group) is _one whose end is _blocked with a _{perfluoroalkyl} group having 5 or less carbon atoms, such as _CF3- , _C2F5- ₍ _CF3CF2- ) _, _C3F7- ₍ CF3CF2CF2- _, (CF3) _2CF- ), _{C4F9-(CF3(CF2)3-), C5F11-} ₍ _CF3 ₍ _CF2 ₎ _4- ₎ _, _etc.

In the present invention, preferred Rf groups are those having structures represented by the following general formulas (7) and (8).

(In the formula, n is an integer from 5 to 28.)

(In the formula, p is an integer of 0 to 41, and q is an integer of 0 to 73, which satisfies p+q=8 to 73. Each repeating unit shown in parentheses with p and q may be bonded randomly.)

The Rf group is more preferably a structure represented by the following general formula (9).

In the present invention, the molecular weight of the Rf group portion is 1,000 to 5,000, and preferably 1,300 to 3,500. If the molecular weight of Rf is less than 1,000, the heat resistance of the coating (water and oil repellency after a heat resistance test) is poor, and if it exceeds 5,000, not only is the viscosity high and the coating difficult to handle during polymerization, but the initial water and oil repellency and heat resistance (water and oil repellency after a heat resistance test) of the coating are also poor. In the present invention, the molecular weight of the Rf group portion can be determined, for example, by ¹⁹ F-NMR or the like.

Examples of the monomer represented by the above general formula (I) include those represented by the following formula:

(In the formula, n, p, and q are the same as above.)

The polymer of the present invention can be obtained by polymerizing the monomer represented by formula (I) dissolved in a solvent using a radical polymerization initiator by a known method such as solution polymerization.

The solvent used in the method for producing a polymer according to the present invention is not particularly limited as long as it can dissolve the monomer represented by formula (I), but a fluorine-based solvent is preferred. Examples of the fluorine-based solvent include Novec7300, Novec7200, Novec7100 (manufactured by 3M), AC-6000, AE-3000 (manufactured by AGC Inc.), hexafluoroacetone, hexafluoroisopropanol, and m-xylene hexafluoride (manufactured by Central Glass Co., Ltd.). Among them, Novec7300 is preferable from the viewpoint of solubility.
The amount of the solvent used is not particularly limited, but is preferably 50 to 2,000 parts by mass, more preferably 100 to 1,000 parts by mass, and even more preferably 200 to 400 parts by mass, per 100 parts by mass of the monomer represented by formula (I).

Examples of radical polymerization initiators that can be used in the method for producing a polymer according to the present invention include dimethyl azobisisobutyrate (V-601), cumene hydroperoxide, succinic acid peroxide, di-t-butyl peroxide, diisobutyryl peroxide, diisobutyl peroxydicarbonate, dicumyl peroxide, cyclohexanone peroxide, dimethyl 2,2'-azobisisobutyrate, benzoyl peroxide, methyl ethyl ketone peroxide, lauroyl peroxide, 2,2'-azobis(2-methylamidoxime) dihydrochloride, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(isobutylamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propionate], and the like. Pan] and its disulfate, 2,2'-azobisisobutyronitrile (AIBN), 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethylhexane-2,5-dihydroperoxide, t-butyl-α-cumyl peroxide, t-butylperoxyacetate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxyisopropylcarbonate, t-butylhydroperoxide, α,α'-bis(t-butylperoxy)-p-diisopropylbenzene and other azo compounds and organic peroxides, potassium persulfate, sodium persulfate, ammonium persulfate, etc. These radical polymerization initiators may be used alone or in combination of two or more.
The amount of the radical polymerization initiator used is not particularly limited, but is preferably 0.05 to 10 parts by mass, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the monomer represented by formula (I).

The polymerization conditions for the monomer represented by formula (I) in the polymerization method using the above solvent and radical polymerization initiator are preferably an inert gas atmosphere at 40 to 120°C, particularly 65 to 70°C, for 4 to 30 hours, particularly 18 to 24 hours.

The polymer of the monomer represented by formula (I) thus obtained preferably has a 15% by mass solvent dissolution kinetic viscosity of 1 to 100 mm ² /s, more preferably 5 to 50 mm ² /s. If the dissolution kinetic viscosity is too small, the surface properties may be low when applied to a substrate, and if the dissolution kinetic viscosity is too large, the workability during application may be poor. The dissolution kinetic viscosity can be measured by the method described in JIS Z8803:2011 using a Cannon-Fenske viscometer. The solvent is not particularly limited as long as it can dissolve the polymer of the monomer represented by formula (I), but a fluorine-based solvent is preferred in terms of solubility and stability. Examples of fluorine-based solvents include Novec7300, Novec7200, Novec7100 (manufactured by 3M), AC-6000, AE-3000 (manufactured by AGC Inc.), hexafluoroacetone, hexafluoroisopropanol, and m-xylene hexafluoride (manufactured by Central Glass Co., Ltd.), etc. Among these, Novec7300 is preferable from the viewpoint of solubility.

The water/oil repellent of the present invention contains a polymer of the monomer represented by the above-mentioned formula (I). The water/oil repellent of the present invention is usually provided as a solvent solution of the above-mentioned polymer. Here, it is desirable that the amount of polymer (polymer concentration) in the solvent solution is 1 to 50 mass%, particularly 3 to 30 mass%, and especially 3 to 15 mass%.

The solvent used for the water- and oil-repellent agent is not particularly limited as long as it can dissolve the monomer, but a fluorine-based solvent is preferred. Examples of fluorine-based solvents include Novec 7300, Novec 7200, Novec 7100 (manufactured by 3M), AC-6000, AE-3000 (manufactured by AGC Inc.), hexafluoroacetone, hexafluoroisopropanol, and m-xylene hexafluoride (manufactured by Central Glass Co., Ltd.). Among these, Novec 7300 is preferable from the viewpoint of solubility. The solvent used in the method for producing the polymer may be used as it is as the solvent used for the water- and oil-repellent agent, or the above solvent may be further added after the production of the polymer to adjust the concentration of the polymer.

The water/oil repellent of the present invention can be applied to a substrate by, for example, spin coating, dip coating, spraying, roll coating, meniscus coating, or screen printing.

The water- and oil-repellent agent of the present invention can be easily applied to a substrate such as glass, fiber, or porous membrane, and then the solvent can be dried to form a coating on the substrate surface. Specifically, it is preferable to dry the agent at room temperature (25°C ± 10°C) for 30 minutes to 24 hours. To speed up the drying process, the agent may be heated to, for example, 40 to 150°C for 30 seconds to 24 hours, within a range that does not affect the substrate. This coating exhibits excellent water- and oil-repellent properties due to the fluorine atoms contained in the polymer. Therefore, the agent can be used as a water- and oil-repellent coating agent for glass, fiber, porous membranes, and the like, particularly for fiber and porous membranes.

The fiber substrate to which the water/oil repellent of the present invention is applied may be in the form of, for example, fiber, thread, cloth, etc. Examples of fibers constituting the fiber substrate include glass fiber, carbon fiber, aramid fiber, polyethylene fiber, polytetrafluoroethylene (PTFE) fiber, Zylon fiber, boron fiber, basalt fiber, metal fiber, polyamide fiber, silicon carbide fiber, polyester fiber, ceramic fiber, alumina fiber, mineral fiber, rock fiber, slug fiber, polyoxymethylene fiber, aromatic polyamide fiber, polyparaphenylene benzobisoxazole fiber, vegetable fiber, cellulose fiber, and lignin fiber. These fibers may be used alone or in combination of two or more types.

Examples of the porous membrane substrate to which the water- and oil-repellent agent of the present invention is applied include nonwoven fabrics, perforated membranes, microporous membranes, and porous bodies. Materials constituting the porous membrane substrate include resins such as PTFE (polytetrafluoroethylene), ceramics, and metals, with PTFE (polytetrafluoroethylene) being preferred.

The thickness of the coating is appropriately selected depending on the type of substrate, but is usually 0.01 to 50 μm, and particularly 1 to 10 μm. The thickness can be calculated, for example, by the following formula:
[Film thickness (μm)]=[Increase in substrate mass before and after coating (g)]÷[Density of water/oil repellent (g/cm ³ )]÷[Substrate area (cm ² )]×10,000

The film thickness can also be measured by other methods, such as spectroscopic reflectance measurement, X-ray reflectance measurement, spectroscopic ellipsometry measurement, and X-ray fluorescence measurement.

Examples of articles having a coating of the water- and oil-repellent agent of the present invention on their surfaces include in-vehicle products, textile products, nonwoven fabrics, and filtration materials used in the presence of organic solvent liquids or their vapors.

The contact angle of the coating formed by applying the water- and oil-repellent agent of the present invention to a glass plate at a temperature of 25°C and a relative humidity of 40% (water contact angle) is preferably 115° or more, and more preferably 120° or more. In the present invention, the contact angle of water is a value measured using a contact angle meter Drop Master (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of a droplet of 2 μl.

Furthermore, it is preferable that the contact angle of the coating formed by applying the water/oil repellent of the present invention to a glass plate with hexadecane (hexadecane (HD) contact angle) at a temperature of 25°C and a relative humidity of 40% is 75° or more, and preferably 78° or more. Note that in the present invention, the contact angle with hexadecane is a value measured using a contact angle meter Drop Master (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of a droplet of 2 μl.

Furthermore, it is preferable that the coating formed using the water and oil repellent of the present invention has an oil repellency of grade 7 or higher according to AATCC test method 118-2020, and that the oil repellency after heating at 150°C for 100 hours does not decrease from the initial oil repellency.

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the molecular weight of the fluoropolyether group (Rf in general formula (I)) is a value calculated from the characteristic peak intensity ratio between the terminal structure and the main chain structure based on ^19F -NMR analysis, the dissolution kinetic viscosity of a polymer of a monomer in a 15% by mass solvent (Novec7300) (hereinafter referred to as dissolution kinetic viscosity) is a value measured using a Cannon-Fenske viscometer according to the method described in JIS Z8803:2011, and the film thickness is a value calculated from the following formula. Room temperature is 25°C.
[Film thickness (μm)]=[Increase in substrate mass before and after coating (g)]÷[Density of water/oil repellent (g/cm ³ )]÷[Substrate area (cm ² )]×10,000

[Example 1]
Into a 200 ml four-neck flask equipped with a thermometer, an inert gas inlet, a reflux condenser, and a stirrer, was added a solution of the following formula (A):

30 parts by mass of a monomer represented by formula (I) (corresponding to the molecular weight of Rf in formula (I) of approximately 1,430), 70 parts by mass of Novec 7300 (manufactured by 3M) as a solvent, and 0.15 parts by mass of Perbutyl O (t-butylperoxy-2-ethylhexanoate, manufactured by NOF Corporation) as a radical polymerization initiator were charged, and reacted at 70° C. for 24 hours while passing nitrogen gas through. The solution kinetic viscosity of the obtained polymer of the monomer was 6.17 mm ² /s. Thereafter, Novec 7300 was added so that the active ingredient concentration was 15% by mass, and a coating liquid of a polymer of the monomer represented by formula (A) was prepared.

[Example 2]
A polymer of the monomer (dissolved kinetic viscosity: 5.90 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (B) (corresponding to the molecular weight of Rf in general formula ( ^I ) of approximately 1,430).

[Example 3]
A polymer of the monomer (dissolved kinetic viscosity: 6.30 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (C) (corresponding to the molecular weight of Rf in general formula ( ^I ) of approximately 1,430).

[Example 4]
A polymer of the monomer (dissolved kinetic viscosity: 7.36 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (D) (corresponding to the molecular weight of Rf in general formula ( ^I ) of approximately 4,100).

[Example 5]
A polymer of the monomer (dissolved kinetic viscosity: 6.23 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (E) (corresponding to the molecular weight of Rf in general formula ( ^I ) of approximately 1,500).

[Comparative Example 1]
A polymer of the monomer (dissolved kinetic viscosity: 73.6 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (F) (corresponding to the molecular weight of Rf in general formula ( ^I ); approximately 432).

[Comparative Example 2]
A polymer of the monomer (dissolved kinetic viscosity: 9.58 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to a monomer represented by the following formula (G) (corresponding to the molecular weight of Rf in general formula ( ^I ); approximately 5,740).

[Comparative Example 3]
A polymer of the monomer (dissolved kinetic viscosity: 12.0 mm2/s) and a coating liquid were prepared in the same manner as in Example 1, except that the monomer was changed from formula (A) to the monomer represented by formula (H) below (a urethane-modified acrylate derived from a perfluorohexanoic acid ( ^PFHxA )-related substance, which is of concern for its accumulation in the human body).

[Preparation of glass samples]
The coating solutions prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were dip-coated on slide glass (S1127, 76 mm x 26 mm, manufactured by Matsunami Glass Industrial Co., Ltd.) under the following conditions to prepare glass samples with coating thicknesses of 2.0 to 2.2 μm.
<Dip coating conditions>
Coating device: Tabletop dip coater (manufactured by SDI Corporation)
Immersion time: 30 seconds Pull-up speed: 0.3 mm/sec
Drying after coating: Room temperature, 30 minutes

[Preparation of PTFE samples]
A fluorine-based solvent (Novec7300/m-hexafluoroxylene = 7:3 (parts by mass)) was added to the coating liquids prepared in Examples 1 to 5 and Comparative Examples 1 to 3 so that the concentration of the active ingredient was 3 mass%, to prepare a diluted solution. Next, a PTFE (polytetrafluoroethylene) porous membrane (PF-100, manufactured by Advantec Co., Ltd.) cut to 70 mm x 26 mm was dip-coated under the following conditions to prepare a PTFE sample to which 0.0692 g of the active ingredient of the diluted solution was attached.
<Dip coating conditions>
Coating device: Tabletop dip coater (manufactured by SDI Corporation)
Immersion time: 30 seconds Pull-up speed: 3.0 mm/sec
Drying after coating: Room temperature, 30 minutes

[Water contact angle, hexadecane (HD) contact angle]
The contact angles of the glass sample surfaces to water and hexadecane (HD) were measured using a contact angle meter under the following conditions. The results are shown in Table 2.
<Contact angle measurement conditions>
Measuring device: Drop Master (manufactured by Kyowa Interface Science Co., Ltd.)
Droplet: 2 μL
Temperature: 25℃
Relative humidity: 40%
[Evaluation Criteria]
Pure water contact angle: ○: 125° or more △: 115° or more, less than 125° ×: less than 115° HD contact angle: ○: 75° or more △: 65° or more, less than 75° ×: less than 65°

[Initial oil repellency]
The initial oil repellency was evaluated according to AATCC test method 118-2020. A drop of the test liquid shown in Table 1 was dropped onto the PTFE sample obtained above with a Pasteur pipette. If the drop did not penetrate after 30 seconds, the test liquid was deemed to have passed. The highest grade of the test liquid that passed was determined to be the oil repellency. The results are shown in Table 2.

[Heat resistance]
The PTFE sample evaluated for the initial oil repellency was left at 150° C. for 100 hours. Thereafter, the oil repellency after the heat resistance test was measured according to AATCC test method 118-2020, and the heat resistance was evaluated based on the following criteria. The results are shown in Table 2.
[Evaluation Criteria]
○: [Initial oil repellency] - [Oil repellency after heat resistance test] = Grade 0 △: [Initial oil repellency] - [Oil repellency after heat resistance test] = Grade 1 ×: [Initial oil repellency] - [Oil repellency after heat resistance test] ≧ Grade 2

[Whether or not PFOA and PFHxA-related substances are contained]
The monomers in the coating solutions prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated as follows: those that did not contain PFOA (perfluorooctanoic acid), which has been pointed out as having a tendency to accumulate in the human body and the environment, and PFHxA (perfluorohexanoic acid)-related substances, which are of concern for similar risks, were rated as O; those that contained PFOA and PFHxA-related substances were rated as X. The results are shown in Table 2.

Claims

The following general formula (I)

(In the formula, R is a hydrogen atom, a halogen atom, an alkyl group or an aryl group; X is a single bond, or an unsubstituted or substituted divalent hydrocarbon group which may contain one or more bonds selected from an oxygen atom, an amino bond, an amide bond, a urethane bond and a urea bond; and Rf is a monovalent fluoropolyether group having a molecular weight of 1,000 to 5,000 and end-capped with a perfluoroalkyl group having 5 or less carbon atoms.)
A water- and oil-repellent agent comprising a polymer of a monomer represented by the formula:
The water/oil repellent according to claim 1, wherein R in the general formula (I) is a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, or a phenyl group.
The water/oil repellent according to claim 1, wherein X in the general formula (I) is any one selected from a single bond, an unsubstituted or substituted alkylene group having 1 to 20 carbon atoms which may contain an oxygen atom, and structures represented by the following general formulas (1) to (5):

(In each of formulas (1) to (5), the site indicated by * is the site of bonding to the oxygen atom in general formula (I), and the site indicated by ** is the site of bonding to the Rf group in general formula (I).)
2. The water/oil repellent according to claim 1, wherein the Rf group in the general formula (I) is represented by the following general formula (7) or (8):

(In the formula, n is an integer from 5 to 28.)

(In the formula, p is an integer of 0 to 41, and q is an integer of 0 to 73, which satisfies p+q=8 to 73. Each repeating unit shown in parentheses with p and q may be bonded randomly.)
The water- and oil-repellent agent according to claim 1, which when applied to a glass plate, gives a coating having a water contact angle of 115° or more.
The water- and oil-repellent agent according to claim 1, which gives a coating having a hexadecane contact angle of 75° or more when applied to a glass plate.
The water and oil repellent according to claim 1, which when applied to a substrate, gives a coating that has an oil repellency of grade 7 or higher according to AATCC test method 118-2020, and whose oil repellency after heating at 150°C for 100 hours does not decrease from the initial oil repellency.
The water- and oil-repellent agent according to any one of claims 1 to 7, wherein the substrate to which the agent is applied is a fiber or a porous film.
The water- and oil-repellent agent according to claim 8, wherein the porous membrane is made of PTFE (polytetrafluoroethylene).
An article having a coating of the water- and oil-repellent agent according to any one of claims 1 to 7 on its surface.