Fluorinated compound, and fluoropolymer and surface treatment agent using same

Abstract

Provided are: a fluorinated compound represented by the formula; a fluoropolymer having constituent units formed from the fluorinated compound; and a surface treatment agent comprising the fluoropolymer and a solvent. In the formula, X is an oxygen atom, a sulfur atom, or a linking group represented by a specific formula; R1 is a phenyl group in which at least one hydrogen atom has been replaced with a trifluoromethoxy group, and R2, R3, and R4 are each independently a hydrogen atom or a C1-C4 alkyl group.

Description

Fluorine-containing compounds, fluorine-containing polymers, and surface treatment agents using the same

[0001] The present invention relates to a fluorine-containing compound, a fluorine-containing polymer, and a surface treatment agent using the same. This application claims priority to Japanese Patent Application No. 2023-159062, filed on September 22, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, compositions containing a fluorine-containing polymer and a solvent have been known as waterproof / moisture-proof coating agents. It is also known that the fluorine-containing polymer may contain structural units formed from a (meth)acrylic acid ester having a phenyl group or the like (see, for example, Patent Document 1).

[0003] Patent No. 6670615

[0004] Compounds containing perfluoroalkyl groups are known to generate perfluorocarboxylic acids and the like during the decomposition process. Among perfluorocarboxylic acids, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are known to be highly chemically stable but resistant to degradation in the environment and highly bioaccumulative. Therefore, various international scientific discussions have been held regarding target values ​​and standards for these compounds, and they are becoming regulated substances in various countries. On the other hand, perfluorohexanoic acid (PFHxA) and other perfluorocarboxylic acids with shorter carbon chains have been confirmed to be far less biotoxic and bioaccumulative than PFOS and PFOA. Therefore, perfluoroalkyl group-containing compounds whose decomposition products are PFHxA or perfluorocarboxylic acids with shorter carbon chains are widely used as alternative technologies. However, even with these alternative compounds, the decomposition products, perfluorocarboxylic acids, remain chemically stable. Concerns remain that if continuously released into the environment, they will accumulate in the environment over long periods of time, potentially posing a threat to the human body and the environment. Therefore, there is a demand for new alternative compounds. On the other hand, compounds containing trifluoromethoxy groups are expected to generate CF during their decomposition process. ３It is known that OH is a very unstable compound and therefore easily decomposes in the environment (for example, in an environment above -20°C).

[0005] Therefore, an object of the present invention is to provide a novel fluorine-containing compound having a trifluoromethoxy group and capable of forming a polymer having excellent water and oil repellency. Another object of the present invention is to provide a fluorine-containing polymer and a surface treatment agent.

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0007] [1] A fluorine-containing compound represented by the following formula (M): In formula (M), X is an oxygen atom, a sulfur atom, or a linking group represented by the following formula (A), and R １ is a phenyl group in which at least one hydrogen atom is substituted with a trifluoromethoxy group, and R ２ , R ３ , R ４ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (A), n is an integer of 0 to 8, and Q １ is an oxygen atom or a divalent group represented by -NH-, R is a linear or branched alkylene group having 1 to 4 carbon atoms or a phenylene group, and Y is any one of the linking groups represented by the following formulas (y1) to (y4): In formulas (y2) to (y4), R ５ , R ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group represented by the following formula (B), and R ７ , R ８ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (B), m is an integer of 0 to 8, and Q ２ is an oxygen atom or a divalent group represented by —NH—, and R ａ is a linear or branched alkylene group or a phenylene group having 1 to 4 carbon atoms, and R ｂ , R ｃ , R ｄare each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Z is a linking group represented by the following formula (z1) or (z2): In formula (z2), R ｅ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. [2] The R １ The fluorine-containing compound according to [1], wherein the trifluoromethoxy group is bonded to the para-position of the phenyl group. [3] The fluorine-containing compound according to [1] or [2], wherein in formula (M), X is a linking group represented by formula (A). [4] The fluorine-containing compound according to [3], wherein Y in formula (A) is a linking group represented by formula (y1) or (y2). [5] A fluorine-containing polymer having a structural unit formed by the fluorine-containing compound according to any one of [1] to [4]. [6] A surface treatment agent containing the fluorine-containing polymer according to [5] and a solvent.

[0008] According to the present invention, there is provided a novel fluorine-containing compound having a trifluoromethoxy group and capable of forming a polymer having excellent water and oil repellency. The present invention also provides a fluorine-containing polymer and a surface treatment agent.

[0009] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to". In this specification, each component can be used alone or in combination of two or more. In this specification, when two or more components are used in combination, the "content" of the component refers to the total content of those two or more components, unless otherwise specified. In this specification, the method for producing each component is not particularly limited unless otherwise specified. Examples include conventionally known methods. In this specification, (meth)acrylic acid refers to acrylic acid or methacrylic acid. In this specification, the polymer obtained from the fluorine-containing compound of the present invention, the fluorine-containing polymer of the present invention, or the surface treatment agent of the present invention exhibiting superior water repellency and oil repellency is also referred to as "excellent effects of the present invention."

[0010] [Fluorine-containing compound of the present invention] The fluorine-containing compound of the present invention will be described below. The fluorine-containing compound of the present invention is a fluorine-containing compound represented by the following formula (M). In formula (M), X is an oxygen atom, a sulfur atom, or a linking group represented by formula (A) described below, and R １ is a phenyl group in which at least one hydrogen atom is substituted with a trifluoromethoxy group, and R ２ , R ３ , R ４ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ is preferably a hydrogen atom or a methyl group. ３ and R ４ is preferably a hydrogen atom.

[0011] Even if the fluorine-containing compound of the present invention or the fluorine-containing polymer of the present invention is unexpectedly released into the environment, CF4 that can be generated from the trifluoromethoxy group by decomposition will not be generated. ３OH is an unstable compound and easily decomposes in the environment (for example, in an environment above −20° C.), and therefore the risk of it remaining in the environment and traveling long distances can be significantly reduced. It is considered that the fluorine-containing polymer etc. of the present invention can reduce the environmental load.

[0012] In the present invention, in formula (M), X is an oxygen atom, a sulfur atom, or a linking group represented by the following formula (A). From the viewpoint of achieving better effects of the present invention and not impairing water repellency and oil repellency, X is preferably a linking group represented by the following formula (A). The linking group represented by formula (A) is as follows.

[0013] In formula (A), n is an integer of 0 to 8. From the viewpoint of achieving superior effects of the present invention and not impairing water repellency and oil repellency, n is preferably 0 or 1, and more preferably 0.

[0014] In formula (A), R is a linear or branched alkylene group or a phenylene group having 1 to 4 carbon atoms. Examples of the linear or branched alkylene group having 1 to 4 carbon atoms include linear alkylene groups such as a methylene group, an ethylene group, a trimethylene group, and a tetramethylene group; and branched alkylene groups such as an isopropylene group and an isobutylene group. When the above n is 1 or more, R is preferably a linear alkyl group or a phenylene group having 2 to 4 carbon atoms, and more preferably a phenylene group, from the viewpoints of achieving better effects of the present invention and not impairing water repellency and oil repellency.

[0015] In formula (A), Q １ is an oxygen atom or a divalent group represented by —NH—.

[0016] In formula (A), Y is any one of linking groups represented by the following formulae (y1) to (y4): When the linking groups represented by formulae (y1) to (y4) are incorporated into Y in formula (A), formulae (y1) to (y4) can be incorporated into Y in formula (A) in the state described below or by flipping them left and right, but it is preferable to incorporate the linking groups represented by formulae (y1) to (y4) into Y in formula (A) in the state described below.

[0017] In formulas (y2) to (y4), R ５ , R ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group represented by the following formula (B):

[0018] R ５ , R ６ Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0019] The group represented by formula (B) is as follows.

[0020] In formula (B), m is an integer of 0 to 8.

[0021] In formula (B), Ra is a linear or branched alkylene group or a phenylene group having 1 to 4 carbon atoms. Examples of the linear or branched alkylene group having 1 to 4 carbon atoms as Ra include linear alkylene groups such as a methylene group, an ethylene group, a trimethylene group, and a tetramethylene group; and branched alkylene groups such as an isopropylene group and an isobutylene group.

[0022] In formula (B), Q ２ is an oxygen atom or a divalent group represented by —NH—.

[0023] In formula (B), Rb, Rc, and Rd each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms represented by Rb, Rc, and Rd include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0024] In formula (B), Z is a linking group represented by the following formula (z1) or (z2): The linking group represented by formula (z1) or (z2) may be incorporated into Z in formula (B) in the state described below.

[0025] In formula (z2), R ｅ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ｅ Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0026] In formulas (y2) to (y4), R ７ , R ８ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ７ , R ８ Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0027] From the viewpoint of achieving a more excellent effect of the present invention, Y is preferably any one of the linking groups represented by formula (y1) to (y2), and is preferably a linking group represented by formula (y1) or a linking group represented by formula (y2), and R ５ is more preferably a linking group in which the group is a hydrogen atom.

[0028] In the present invention, in formula (M), R １ is a phenyl group in which at least one hydrogen atom is substituted with a trifluoromethoxy group. １ In the formula (R), at least one of the five hydrogen atoms of one phenyl group may be substituted with a trifluoromethoxy group. Two or more hydrogen atoms in the phenyl group may be substituted with trifluoromethoxy groups. １ In order to achieve the effects of the present invention, at least one hydrogen atom of the phenyl group must be substituted with a trifluoromethoxy group.

[0029] The trifluoromethoxy group may be bonded to any of the ortho (o-), meta (m-) and para (p-) positions of the phenyl group.

[0030] R １ In view of achieving better effects of the present invention, it is preferred that the trifluoromethoxy group be bonded to the para-position of the phenyl group.

[0031] In the present invention, in formula (M), R ２ , R ３ , R ４ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ , R ３ , R ４ Examples of the alkyl group having 1 to 4 carbon atoms as R include a methyl group, an ethyl group, a propyl group, and a butyl group.２ , R ３ , R ４ From the viewpoint of more excellent effects of the present invention, the combination of ２ , R ３ , R ４ are all hydrogen atoms, or R ２ is a methyl group, and R ３ , R ４ is preferably a hydrogen atom. ２ , R ３ , R ４ are all hydrogen atoms.

[0032] Specific examples of more preferred structures of the fluorine-containing compound of the present invention are shown below, from the viewpoint of achieving better effects of the present invention.

[0033] Examples of methods for synthesizing the fluorine-containing compound of the present invention include the following synthesis methods 1 and 2. - Synthesis method 1 When the fluorine-containing compound of the present invention has the formula (y1) or (y2) as Y in formula (M), synthesis method 1 corresponding to that synthesis method is, for example, a method of reacting trifluoromethoxyphenol, trifluoromethoxyaniline, or a precursor represented by the following formula (pre1) with (meth)acrylic acid chloride in a solvent (e.g., dichloromethane, methylene chloride) in the presence of a catalyst (e.g., triethylamine, triethylenediamine). After the reaction, appropriate purification can be carried out. In formula (pre1), x1 is an oxygen atom or a divalent group represented by —NH—.

[0034] Synthesis Method 2 When the fluorine-containing compound of the present invention has the formula (y3) or (y4) as Y in formula (M), an example of Synthesis Method 2 corresponding to that synthesis method is a method in which trifluoromethoxyphenol or trifluoromethoxyaniline is reacted with a (meth)acrylic acid ester having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate, in a solvent (e.g., tetrahydrofuran). In the above reaction, a catalyst (e.g., N,N-diisopropylethylamine, triethylamine, triethylenediamine) may be used. After the reaction, the product can be appropriately purified.

[0035] Uses The fluorine-containing compound of the present invention can be used, for example, as a monomer for producing a polymer.

[0036] [Fluorine-containing polymer of the present invention] The fluorine-containing polymer of the present invention is a fluorine-containing polymer having a structural unit formed by the fluorine-containing compound of the present invention. The structural unit of the fluorine-containing polymer of the present invention is not particularly limited as long as it contains a structural unit formed by the fluorine-containing compound of the present invention. The structural unit formed by the fluorine-containing compound of the present invention has a structure in which the double bond in the above formula (M) is cleaved. The structural unit formed by the fluorine-containing compound of the present invention is a structure in which the double bond in the above formula (M) is cleaved. １and has a phenyl group in which at least one hydrogen atom is substituted with a trifluoromethoxy group. The fluorine-containing polymer of the present invention can have the structural units formed by the fluorine-containing compound of the present invention either alone or in combination of two or more. The structural units that the fluorine-containing polymer of the present invention has may further have structural units (other structural units) other than the structural units formed by the fluorine-containing compound of the present invention. The other structural units are not particularly limited as long as they are structural units formed by monomers copolymerizable with the fluorine-containing compound of the present invention. From the viewpoint of reducing the environmental burden, it is desirable that the fluorine-containing polymer of the present invention does not contain structural units containing perfluoroalkyl groups other than trifluoromethoxy groups. Furthermore, from the viewpoint of maintaining water repellency and oil repellency, it is desirable that the structural units formed by the fluorine-containing compound of the present invention account for 50% by mass or more and 100% by mass or less, more preferably 80% by mass or more, and even more preferably 90% by mass or more, of the total mass of all structural units that the fluorine-containing polymer of the present invention has.

[0037] The mass-average molecular weight of the fluoropolymer of the present invention is not particularly limited, but from the viewpoint of oil resistance and water resistance, the lower limit of the mass-average molecular weight is preferably 10,000 or more, and from the viewpoint of solubility in solvents, the upper limit of the mass-average molecular weight is preferably 1,000,000 or less. The mass-average molecular weight is a weight-average molecular weight measured by gel permeation chromatography (GPC).

[0038] The method for producing the fluorine-containing polymer of the present invention is not particularly limited. As an example of the method for producing the fluorine-containing polymer of the present invention, for example, the fluorine-containing polymer of the present invention can be produced by polymerizing the fluorine-containing compound of the present invention in a solvent (e.g., ethyl acetate) in the presence of a polymerization initiator (e.g., dimethyl 2,2'-azobis(2-methylpropionate)) under conditions of 60 to 80°C. Furthermore, during the polymerization, a monomer copolymerizable with the fluorine-containing compound of the present invention may also be used, if necessary.

[0039] The fluorine-containing polymer of the present invention can be used, for example, in a surface treatment agent.

[0040] [Surface treatment agent of the present invention] The surface treatment agent of the present invention is a surface treatment agent containing the fluoropolymer of the present invention and a solvent. The surface treatment agent of the present invention has excellent water and oil repellency and can be used as a water / oil repellent composition and a water / oil repellent.

[0041] The fluorine-containing polymer contained in the surface treatment agent of the present invention is not particularly limited as long as it is the fluorine-containing polymer of the present invention.

[0042] The solvent contained in the surface treatment agent of the present invention is not particularly limited as long as it can disperse and / or dissolve the fluorine-containing polymer of the present invention. Examples of the solvent include fluorine-containing solvents, hydrocarbon organic solvents, esters (ethyl acetate, butyl acetate, etc.), and ketones (acetone, methyl ethyl ketone, etc.).

[0043] The fluorine-based solvent may be a hydrofluorocarbon (HFC) or a hydrofluoroether (HFE).

[0044] Specific examples of fluorine-based solvents include m-xylene hexafluoride, p-xylene hexafluoride, CF ３ CH ２ CF ２ CH ３ , C.F. ３ CH ２ CF ２ H, C ６ F １３ OCH ３ , C ６ F １３ O.C. ２ H ５ , C ６ F １３ CH ２ CH ３ , C ３ F ７ OCH ３ , C ３ F ７ O.C. ２ H ５ , C ６ F １３ H, C.F. ２ HCF ２ CH ２ OCF ２ CF ２ H, C.F.３ CFHCFHCF ２ CH ３ , C.F. ３ (OCF ２ CF ２ ) ｎ (OCF ２ ) ｍ OCF ２ H, C ８ F １７ OCH ３ , C ７ F １５ OCH ３ , C ７ F １３ OCH ３ , C ４ F ９ OCH ３ , C ４ F ９ O.C. ２ H ５ , C ４ F ９ CH ２ CH ３ , C.F. ３ CH ２ OCF ２ CF ２ CF ２ H, C.F. ３ CF (CH ２ CF ３ ) CF(OCH ３ )CF ２ CF ３ , C.F. ２ HCF ２ OCH ２ CF ３ and mixtures thereof. Examples of the mixture include C ４ F ９ OCH ２ CH ３ (ethyl nonafluorobutyl ether), an isomer of CF ３ (CF ２ ) ３ O.C. ２ H ５ and (CF ３ ) ２ CFCF ２ O.C. ２ H ５In the above examples, the subscripts m and n each independently represent an integer of 1 to 20.

[0045] Examples of hydrocarbon organic solvents include aromatic hydrocarbons (xylene, toluene, ethylbenzene, etc.), alicyclic hydrocarbons (cyclohexane, cyclohexene, methylcyclohexane, ethylcyclohexane, etc.), and chain aliphatic hydrocarbons (hexane, heptane, octane, decane, etc.).

[0046] The concentration of the fluoropolymer of the present invention contained in the surface treatment agent of the present invention is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, of the total amount of the surface treatment agent of the present invention, from the viewpoint of fully exerting the effects of the present invention. The content of the solvent is not particularly limited, but from the viewpoint of handleability as a surface treatment agent, it is preferably 80% by mass or more of the total amount of the surface treatment agent of the present invention.

[0047] The surface treatment agent of the present invention may further contain, if necessary, additives such as a pH adjuster, a rust inhibitor, a dye, a flame retardant, an antifoaming agent or an antistatic agent, or a polymer or resin other than the fluorine-containing polymer of the present invention, within limits that do not impair the effects of the present invention.

[0048] An example of a method for producing the surface treatment agent of the present invention is a method in which the fluoropolymer of the present invention, a solvent, and additives that can be contained as necessary are mixed to obtain the surface treatment agent of the present invention.

[0049] An example of a method for using the surface treatment agent of the present invention is a method of applying the surface treatment agent of the present invention to a substrate. By applying the surface treatment agent, a layer of the surface treatment agent is formed on the surface of the substrate, thereby improving the oil repellency of the surface of the substrate. Furthermore, by applying the surface treatment agent, excellent water repellency can be further imparted to the surface of the substrate. The method for applying the surface treatment agent of the present invention to a substrate is not particularly limited. For example, coating can be used. After applying the surface treatment agent of the present invention to a substrate, the solvent can be dried, for example, under conditions of 10 to 120°C.

[0050] Examples of materials for the substrate include glass, plastic, rubber, metal, ceramic, etc. Specific examples of the substrate include daily necessities (umbrellas, shoes, bags, etc.), wet area molded products (bathroom components, washroom components, kitchen components, etc.), building exteriors (bridge piers, roofs, exterior walls, etc.), interiors (floors, interior walls, etc.), housing products (furniture, home appliances, etc.), vehicle bodies (including exterior and interior materials, such as ships, airplanes, automobiles, etc.), electronic substrates, etc.

[0051] The present invention will be described in more detail below with reference to examples. Examples 1 to 15 are working examples, and Examples 16 to 19 are comparative examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below. Hereinafter, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass". In this specification, the fluorine-containing compound produced in Example 1 will be referred to as Monomer 1, the fluorine-containing polymer produced using Monomer 1 will be referred to as Fluorine-containing Polymer 1, and the surface treatment agent containing Fluorine-containing Polymer 1 will be referred to as Surface Treatment Agent 1. The same applies to other examples. Unless otherwise specified, the compounds used as raw materials, etc. in these examples were commercially available.

[0052] < １ H-NMR Measurement> The substance to be measured (each monomer synthesized in the examples) was dissolved in a heavy solvent, chloroform-d, and the concentration of the substance to be measured was adjusted to about 0.2 mass %. ４ (Tetramethylsilane) was used. The prepared solution １ The measurement conditions are as follows: Apparatus: JNM-ECZ400R / S1 (manufactured by JEOL Ltd.) Nuclide: proton Number of accumulations: 16

[0053] Example 1 - Synthesis of Monomer 1 9.21 g (51.7 mmol) of 4-trifluoromethoxyphenol and 78 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 7.85 g (77.5 mmol) of triethylamine was added dropwise, followed by 5.61 g (62.0 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 11.25 g of the target product.

[0054] The compound obtained by the above reaction １ The H-NMR chemical shifts were as follows: δ (ppm): 6.04 (dd, 1H, CH), 6.32 (dd, 1H, CH), 6.62 (dd, 1H, CH), 7.17 (m, 2H, 2CH), 7.25 (m, 2H, 2CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0055] Example 2 - Synthesis of Monomer 2 9.21 g (51.7 mmol) of 4-trifluoromethoxyphenol and 60 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 7.85 g (77.5 mmol) of triethylamine was added dropwise, followed by 6.53 g (62.0 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 11.45 g of the target product.

[0056] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 2.06 (m, 3H, CH ３), 5.78 (m, 1H, CH), 6.36 (m, 1H, CH), 7.16 (m, 2H, 2CH), 7.24 (m, 2H, 2CH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0057] Example 3 - Synthesis of Monomer 3 8.05 g (45.4 mmol) of 4-trifluoromethoxyaniline and 80 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 5.25 g (51.9 mmol) of triethylamine was added dropwise, followed by 3.92 g (43.3 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 8.38 g of the target product.

[0058] The compound obtained by the above reaction １ The H-NMR chemical shifts were as follows: δ (ppm): 5.78 (dd, 1H, CH), 6.26 (dd, 1H, CH), 6.44 (dd, 1H, CH), 7.18 (m, 2H, 2CH), 7.63 (m, 3H, 2CH, NH) １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0059] Example 4 - Synthesis of Monomer 4 9.65 g (54.5 mmol) of 4-trifluoromethoxyaniline and 96 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 5.78 g (57.1 mmol) of triethylamine was added dropwise, followed by 5.43 g (51.9 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 11.50 g of the target product.

[0060] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 2.06 (m, 3H, CH ３ ), 5.49 (m, 1H, CH), 5.80 (m, 1H, CH), 7.19 (m, 2H, 2CH), 7.59 (m, 3H, 2CH, NH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0061] Example 5 - Synthesis of Monomer 5 11.51 g (64.6 mmol) of 3-trifluoromethoxyphenol and 90 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 9.81 g (96.9 mmol) of triethylamine was added dropwise, followed by 7.02 g (77.5 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 14.67 g of the target product.

[0062] The compound obtained by the above reaction １ The H-NMR chemical shifts were as follows: δ (ppm): 6.05 (dd, 1H, CH), 6.32 (dd, 1H, CH), 6.63 (dd, 1H, CH), 7.06 (m, 1H, CH), 7.12 (m, 2H, 2CH), 7.41 (t, 1H, CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0063] Example 6 - Synthesis of Monomer 6 10.85 g (60.9 mmol) of 3-trifluoromethoxyphenol and 90 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 9.25 g (91.4 mmol) of triethylamine was added dropwise, followed by 8.60 g (82.3 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 13.71 g of the target product.

[0064] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 2.05 (m, 3H, CH ３ ), 5.78 (m, 1H, CH), 6.35 (m, 1H, CH), 7.04 (m, 1H, CH), 7.10 (m, 2H, 2CH), 7.40 (t, 1H, CH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0065] Example 7 - Synthesis of Monomer 7 9.65 g (54.5 mmol) of 3-trifluoromethoxyaniline and 96 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 7.88 g (77.9 mmol) of triethylamine was added dropwise, followed by 4.70 g (51.9 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 11.44 g of the target product.

[0066] The compound obtained by the above reaction １The chemical shifts of H-NMR were as follows: δ (ppm): 5.80 (dd, 1H, CH), 6.25 (dd, 1H, CH), 6.45 (dd, 1H, CH), 6.98 (dd, 1H, CH), 7.33 (t, 1H, CH), 7.44 (d, 1H, CH), 7.57 (brs, 1H, NH), 7.64 (s, 1H, CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0067] Example 8 - Synthesis of Monomer 8 9.86 g (55.7 mmol) of 3-trifluoromethoxyaniline and 104 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 8.05 g (79.5 mmol) of triethylamine was added dropwise, followed by 7.20 g (68.8 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 13.85 g of the target product.

[0068] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 2.06 (m, 3H, CH ３ ), 5.50 (m, 1H, CH), 5.80 (m, 1H, CH), 6.98 (m, 1H, CH), 7.33 (t, 1H, CH), 7.42 (m, 1H, CH), 7.62 (m, 2H, CH, NH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0069] Example 9 - Synthesis of Monomer 9 11.51 g (64.6 mmol) of 2-trifluoromethoxyphenol and 120 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 9.81 g (96.9 mmol) of triethylamine was added dropwise, followed by 8.18 g (90.3 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 14.04 g of the target product.

[0070] The compound obtained by the above reaction １ The H-NMR chemical shifts were as follows: δ (ppm): 6.07 (dd, 1H, CH), 6.34 (dd, 1H, CH), 6.65 (dd, 1H, CH), 7.31 (m, 4H, 4CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0071] Example 10 - Synthesis of Monomer 10 In a four-neck flask, 10.85 g (60.9 mmol) of 2-trifluoromethoxyphenol and 90 mL of dichloromethane were mixed and immersed in ice water to cool. 9.25 g (91.4 mmol) of triethylamine was added dropwise, followed by 8.92 g (85.4 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 14.85 g of the target product.

[0072] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 2.07 (m, 3H, CH ３ ), 5.80 (m, 1H, CH), 6.38 (m, 1H, CH), 7.30 (m, 4H, 4CH) １From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0073] Example 11 - Synthesis of Monomer 11 12.07 g (68.1 mmol) of 2-trifluoromethoxyaniline and 120 mL of dichloromethane were mixed in a four-neck flask and cooled by immersion in ice water. 9.85 g (97.3 mmol) of triethylamine was added dropwise, followed by 7.04 g (77.8 mmol) of acrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 13.70 g of the target product.

[0074] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 5.83 (dd, 1H, CH), 6.29 (dd, 1H, CH), 6.45 (dd, 1H, CH), 7.12 (m, 1H, CH), 7.28 (m, 2H, 2CH), 7.54 (brs, 1H, NH), 8.50 (d, 1H, CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0075] Example 12 - Synthesis of Monomer 12 In a four-neck flask, 12.73 g (71.9 mmol) of 2-trifluoromethoxyaniline and 120 mL of dichloromethane were mixed and immersed in ice water to cool. 10.80 g (106.7 mmol) of triethylamine was added dropwise, followed by 10.57 g (101.1 mmol) of methacrylic acid chloride, and the mixture was warmed to room temperature. After stirring overnight, hydrochloric acid (1 mol / L) was added to terminate the reaction, and the mixture was separated into an aqueous layer and an organic layer. The resulting organic layer was washed with an aqueous sodium bicarbonate solution (2.5% by mass) and water, and the solvent was then evaporated under reduced pressure to obtain 13.74 g of the target product.

[0076] The compound obtained by the above reaction１ The chemical shifts of H-NMR were as follows: δ (ppm): 2.09 (m, 3H, CH ３ ), 5.53 (m, 1H, CH), 5.87 (m, 1H, CH), 7.13 (m, 1H, CH), 7.30 (m, 2H, 2CH), 7.90 (brs, 1H, NH), 8.49 (dd, 1H, CH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0077] Example 13 - Synthesis of Monomer 13 10.00 g (56.2 mmol) of 4-trifluoromethoxyphenol and 56 mL of tetrahydrofuran were mixed in a four-neck flask, and 0.36 g (2.81 mmol) of N,N-diisopropylethylamine and 8.72 g (61.8 mmol) of 2-isocyanatoethyl acrylate were added, followed by heating under reflux for 21 hours. The target product was then isolated by column chromatography (hexane / acetone), and the solvent was distilled off under reduced pressure, yielding 16.10 g of the target product. The yield of the target product was 89.8%.

[0078] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 3.58 (m, 2H, CH ２ ), 4.31 (m, 2H, CH ２ ), 5.38 (brs, 1H, NH), 5.89 (dd, 1H, CH), 6.15 (dd, 1H, CH), 6.46 (dd, 1H, CH), 7.17 (m, 4H, 4CH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0079] Example 14 Synthesis of Monomer 14 8.00 g (45.2 mmol) of 4-trifluoromethoxyaniline and 45 mL of tetrahydrofuran were mixed in a four-neck flask, and 7.01 g (49.68 mmol) of 2-isocyanatoethyl acrylate was added, followed by heating under reflux for 14 hours. The target product was then isolated by column chromatography (hexane / ethyl acetate), and the solvent was distilled off under reduced pressure to obtain 10.80 g of the target product. The yield of the target product was 74.9%.

[0080] The compound obtained by the above reaction １ The chemical shifts of H-NMR were as follows: δ (ppm): 3.51 (t, 2H, CH ２ ), 4.24(t, 2H, CH ２ ), 5.81 (m, 2H, CH, NH), 6.08 (dd, 1H, CH), 6.39 (dd, 1H, CH), 7.07 (m, 2H, 2CH), 7.26 (m, 2H, 2CH), 7.53 (m, 1H, NH) Above １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0081] Example 15 - Synthesis of Precursor 15-1 First, 5.56 g (30.9 mmol) of 4-acetoxybenzoic acid and 56 mL of tetrahydrofuran were mixed in a four-neck flask, and 4.01 g (33.7 mmol) of thionyl chloride was added dropwise. The mixture was then heated to reflux. After confirming the disappearance of the raw materials by GC, the mixture was concentrated under reduced pressure. 56 mL of tetrahydrofuran, 3.99 g (30.9 mmol) of diisopropylethylamine, and 5.00 g (28.1 mmol) of 4-trifluoromethoxyphenol were added and stirred overnight. After confirming the disappearance of the raw materials by GC (gas chromatography), water was added to terminate the reaction. After extraction with ethyl acetate, the organic layer was dried over magnesium sulfate. The resulting organic layer was separated by silica gel column chromatography (hexane / ethyl acetate) and concentrated under reduced pressure. The resulting crystals were recrystallized using methylene chloride and hexane, and the crystals were dried under reduced pressure to obtain 4.12 g of Precursor 15-1. The reaction scheme for obtaining precursor 15-1 is as follows:

[0082] Synthesis of Precursor 15-2 Next, 4.12 g (12.1 mmol) of precursor 15-1 synthesized as described above was dissolved in a four-necked flask in a mixed solvent of 24 mL of tetrahydrofuran and 24 mL of methanol, and a 1:1 mixed solution of aqueous ammonium chloride (1 mol / L) and aqueous sodium hydroxide (1 mol / L) was added dropwise. After confirming the disappearance of the raw materials by TLC, the solution was neutralized with hydrochloric acid (1 mol / L) and extracted with methylene chloride. The resulting organic layer was concentrated under reduced pressure to obtain 3.72 g of a white solid, precursor 15-2. The reaction formula for obtaining precursor 15-2 is as follows:

[0083] Synthesis of Monomer 15: In a four-neck flask, 3.72 g (12.5 mmol) of precursor 15-2 synthesized as described above was dissolved in 25 mL of methylene chloride, and 1.77 g (13.7 mmol) of diisopropylethylamine was added dropwise. Next, 1.24 g (13.7 mmol) of acrylic acid chloride was added, and the mixture was stirred at room temperature for 2 hours. After confirming the disappearance of the raw materials by GC, water was added to stop the reaction. After extraction with methylene chloride, the organic layer was dried over magnesium sulfate. The obtained organic layer was separated by silica gel column chromatography (hexane / methylene chloride) and concentrated under reduced pressure. The obtained crystals were washed with hexane and dried under reduced pressure to obtain 2.48 g of the target product.

[0084] The compound obtained by the above reaction １ The H-NMR chemical shifts were as follows: δ (ppm): 6.08 (d, 1H, CH), 6.35 (dd, 1H, CH), 6.66 (d, 1H, CH), 7.28 (m, 6H, 6CH), 8.25 (m, 2H, 2CH). １ From the results of H-NMR, it was confirmed that the compound obtained by the above reaction had the structure of the reaction product shown in the above reaction formula.

[0085] [Production of Fluoropolymer] Production of Fluoropolymer 1 Monomer 1 (100 parts) synthesized in Example 1 as described above, ethyl acetate (300 parts), and V-601 (1 part; dimethyl 2,2'-azobis(2-methylpropionate); manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a reaction vessel, which was then purged with nitrogen and tightly sealed. A polymerization reaction was carried out at 70°C for 18 hours to obtain an ethyl acetate solution containing fluoropolymer 1, which is a polymer of Monomer 1. The reaction formula for the above polymerization reaction is as follows. A portion of the reaction solution after 18 hours was taken, and by confirming that the peak derived from Monomer 1 had completely disappeared by gas chromatography, it was determined that the polymerization reaction had progressed quantitatively. The above confirmation based on the reaction rate was also carried out in the same way in other examples.

[0086] Production of Fluoropolymers 2, 4 to 11, and 13 to 14 Fluoropolymer 2 was produced by carrying out polymerization in the same manner as in the production of Fluoropolymer 1 described above, except that 100 parts of Monomer 1 was changed to 100 parts of Monomer 2. The same was true for Fluoropolymers 4 to 11 and 13 to 14.

[0087] - Production of Fluoropolymer 3 Monomer 3 (100 parts) synthesized in Example 3 as described above, ethyl acetate (700 parts), and V-601 (1 part, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a reaction vessel, and after nitrogen substitution, the vessel was sealed. A polymerization reaction was carried out at 70°C for 18 hours, to obtain an ethyl acetate solution containing fluoropolymer 3. The reaction formula of the above polymerization reaction is as follows:

[0088] - Production of Fluoropolymer 12 Monomer 12 (100 parts) synthesized in Example 12 as described above, ethyl acetate (400 parts), and V-601 (1 part, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a reaction vessel, which was then purged with nitrogen and tightly sealed. A polymerization reaction was carried out at 70°C for 18 hours, yielding an ethyl acetate solution containing fluoropolymer 12. The reaction formula for the above polymerization reaction is as follows:

[0089] - Production of Fluoropolymer 15 Monomer 15 (100 parts) synthesized in Example 15 as described above, ethyl acetate (500 parts), and V-601 (1 part, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a reaction vessel, and after nitrogen substitution, the vessel was sealed. A polymerization reaction was carried out at 70°C for 18 hours, to obtain an ethyl acetate solution containing fluoropolymer 15. The reaction formula of the above polymerization reaction is as follows:

[0090] Comparative Example 1 Phenyl acrylate (100 parts) as a monomer, ethyl acetate (300 parts), and V-601 (1 part, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a reaction vessel, and after replacing the atmosphere with nitrogen, the vessel was sealed. A polymerization reaction was carried out at 70°C for 18 hours to obtain an ethyl acetate solution containing polyphenyl acrylate. The reaction formula for the above polymerization reaction is as follows:

[0091] Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1 above, except that 100 parts of phenyl acrylate was changed to 100 parts of phenyl methacrylate, to obtain an ethyl acetate solution containing polyphenyl methacrylate.

[0092] Comparative Example 3 A reaction vessel was charged with N-phenylacrylamide (100 parts) as a monomer, ethyl acetate (700 parts), and V-601 (1 part, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the atmosphere was replaced with nitrogen, followed by sealing. A polymerization reaction was carried out at 70°C for 18 hours, yielding an ethyl acetate solution containing poly-N-phenylacrylamide. The reaction formula for the above polymerization reaction is as follows:

[0093] Comparative Example 4 Polymerization was carried out in the same manner as in Comparative Example 1, except that 100 parts of phenyl acrylate was changed to 100 parts of N-phenylmethacrylamide, to obtain an ethyl acetate solution containing poly(N-phenylmethacrylamide).

[0094] [Production of Surface Treatment Agent] Ethyl acetate was added to each of the polymer-containing solutions obtained as described above to produce surface treatment agents containing the polymer and a solvent. In each surface treatment agent, the solid content of the polymer in the surface treatment agent was 2 mass%.

[0095] [Evaluation] <Preparation of Evaluation Specimen> A glass plate was immersed in each of the surface treatment agents prepared as described above for 1 minute. After removing the glass plate from the surface treatment agent, the glass plate was dried in a dryer at 120°C for 5 minutes to obtain an evaluation specimen.

[0096] <Contact Angle Measurement> Water or n-hexadecane (n-HD) was dropped onto the evaluation test piece obtained as described above, and the contact angle (unit: degrees) of water or n-hexadecane (n-HD) was measured using a contact angle meter DMo-501 (manufactured by Kyowa Interface Science Co., Ltd.). The contact angle was measured at five points for water or n-hexadecane, and the average was used as the evaluation value. The evaluation results are shown in Table 1, along with the structural formula of each monomer.

[0097] (Evaluation Criteria for Oil Repellency) In the present invention, when the contact angle of n-hexadecane is 30 degrees or more, the oil repellency is deemed to be excellent. The larger the contact angle is 30 degrees, the better the oil repellency is. From the viewpoint of better oil repellency, the contact angle is preferably 40 degrees or more. On the other hand, when the contact angle is less than 30 degrees, the oil repellency is deemed to be poor.

[0098] (Evaluation Criteria for Water Repellency) In this specification, when the contact angle of water is 80 degrees or more, the water repellency is considered to be excellent. The larger the contact angle is 80 degrees, the better the water repellency is. From the viewpoint of better water repellency, the contact angle is preferably 100 degrees or more. On the other hand, when the contact angle is less than 80 degrees, the water repellency is evaluated as poor.

[0099]

[0100]

[0101] From the results in Table 1, it was confirmed that the fluorine-containing polymer of the present invention having structural units formed from the fluorine-containing compound of the present invention and the surface treatment agent of the present invention exhibit the desired effects (Examples 1 to 15).

[0102] On the other hand, the polymers and surface treatment agents having structural units formed from compounds that do not have trifluoromethoxy groups exhibited poor oil repellency (Examples 16 to 19).

Claims

1. A fluorine-containing compound represented by the following formula (M): In formula (M), X is an oxygen atom, a sulfur atom, or a linking group represented by the following formula (A), R １ is a phenyl group in which at least one hydrogen atom is substituted with a trifluoromethoxy group, R ２ , R ３ , R ４ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (A), n is an integer from 0 to 8; Q １ is an oxygen atom or a divalent group represented by -NH-, R is a linear or branched alkylene group having 1 to 4 carbon atoms or a phenylene group, and Y is any one of the linking groups represented by the following formulas (y1) to (y4): In formulas (y2) to (y4), R ５ , R ６ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group represented by the following formula (B), ７ , R ８ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In formula (B), m is an integer from 0 to 8; ２ is an oxygen atom or a divalent group represented by -NH-, R ａ is a linear or branched alkylene group or a phenylene group having 1 to 4 carbon atoms; R ｂ , R ｃ , R ｄ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Z is a linking group represented by the following formula (z1) or (z2). In formula (z2), R ｅ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

2. The above R １ 2. The fluorine-containing compound according to claim 1, wherein the trifluoromethoxy group is bonded to the para position of the phenyl group.

3. The fluorine-containing compound according to claim 1, wherein in said formula (M), X is a linking group represented by said formula (A).

4. The fluorine-containing compound according to claim 3, wherein the Y in the formula (A) is a linking group represented by the formula (y1) or (y2).

5. A fluorine-containing polymer having structural units formed from the fluorine-containing compound according to any one of claims 1 to 4.

6. A surface treatment agent comprising the fluorine-containing polymer according to claim 5 and a solvent.

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