Fluorine-containing composition, varnish containing the fluorine-containing composition and insulated wire

Abstract

To provide a fluorine-containing composition achieving both high flexibility and low dielectric constant.SOLUTION: There is provided a fluorine-containing composition comprising a fluorine-containing compound and a bifunctional cross-linking agent, wherein the fluorine-containing compound contains a structural unit A having a structure containing a 3 to 12-membered cyclic structure in the main skeleton in which 50% or more of the hydrogen atoms in the cyclic structure are replaced by fluorine atoms, a structural unit B having a structure containing a benzene ring in the main skeleton in which fluorine atoms account for 30% or less of the number of atoms in the structural unit and a structural unit C having an olefinic carbon-carbon double bond or a carbon-carbon triple bond, the structural units A through C are bonded together with the structural unit C as the terminal end and the fluorine-containing compound contains more than 30 mass% and less than 70 mass% of the bifunctional cross-linking agent when the total of the fluorine-containing compound and the bifunctional cross-linking agent is defined as 100 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a fluorine-containing composition, more specifically to a fluorine-containing composition useful for insulating coatings and flexible copper-clad laminates, a varnish containing the fluorine-containing composition, and an insulated wire having an insulating coating. [Background technology]

[0002] Insulated wires with a resin insulating coating on the outer surface of a linear metal conductor are used for coils for electric and electronic devices such as high-speed switching elements, inverter motors, and transformers. The insulating coating is produced by a method such as extrusion coating with a thermoplastic resin, a method of applying a thermosetting resin varnish and then baking it, or a combination of these methods. Such insulating coatings are required to have high insulating properties, high adhesion to metal conductors, and flexibility that allows them to withstand processing such as bending and stretching.

[0003] As a material for forming an insulating coating by extrusion coating, for example, Patent Document 1 discloses a composition containing a polyarylene sulfide resin and a fluororesin, and Patent Document 2 discloses a composition containing a resin having a specific relative dielectric constant and a fluororesin. Known materials for forming an insulating coating from a resin varnish include polyimide, polyamideimide, polyesterimide, and the like, and fluorinated polyimide has been disclosed as an example containing fluorine atoms (Patent Document 3).

[0004] Another application requiring flexibility and insulation is flexible copper-clad laminates, which have a structure in which copper foil is bonded to one or both sides of a flexible insulating film via an adhesive layer, and polyimide resin is often used as the base material for the insulating film.

[0005] On the other hand, the present applicant has proposed fluororesins having a specific structure as materials exhibiting low dielectric constant and low dielectric loss (Patent Documents 4 and 5). Although these exhibit excellent physical properties, the flexibility of the cured products thereof has not been examined. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2023-64193 A [Patent Document 2] International Publication No. 2014 / 112405 [Patent Document 3] International Publication No. 2015 / 002278 [Patent Document 4] Patent Publication No. 2022-89150 [Patent Document 5] JP 2023-65203 A Summary of the Invention [Problem to be solved by the invention]

[0007] Demands for high flexibility and low dielectric constant for insulating coatings and copper-clad laminates are increasing year by year, and further improvements are required. An object of the present invention is to provide a fluorine-containing composition that combines high flexibility with a low dielectric constant. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems and have discovered that by adding a specific amount of a specific crosslinking agent to a specific fluorine-containing compound, a cured product having both a low dielectric constant and excellent flexibility can be obtained, thereby completing the present invention.

[0009] According to the present invention, there is provided a fluorine-containing composition comprising a fluorine-containing compound and a bifunctional crosslinking agent, the fluorine-containing compound comprising a structural unit A having a structure in which a 3- to 12-membered cyclic structure in the main skeleton is substituted with fluorine atoms for 50% or more of the hydrogen atoms in the cyclic structure, a structural unit B having a structure in which a benzene ring is included in the main skeleton and fluorine atoms account for 30% or less of the number of atoms in the structural unit, and a structural unit C having an olefinic carbon-carbon double bond or a carbon-carbon triple bond, the structural units A to C being bonded in the order of CB-(AB)nC or CA-(BA)nC (wherein n is greater than 1 and less than 30), and the fluorine-containing composition comprising more than 30% by mass and less than 70% by mass of the bifunctional crosslinking agent is provided, when the total amount of the fluorine-containing compound and the bifunctional crosslinking agent is taken as 100% by mass.

[0010] In the fluorine-containing composition of the present invention, [1] It is preferable that the fluorine-containing compound has a structure represented by the following formula (I): [ka] In the formula, L is a structure represented by the following formula (II) or (III): [ka] R 1 and R 2 are each independently a group selected from the group consisting of a hydrogen atom, a C1-C10 alkyl group, a C1-C10 haloalkyl group, and a C6-C10 aryl group, or R 1 and R 2 are groups which together form a ring structure which may have a substituent, R 3 and R 4 are each independently a group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C10 saturated or unsaturated hydrocarbon group in which some or all of the hydrogen atoms may be substituted with halogen, and a C6-C10 aryl group in which some or all of the hydrogen atoms may be substituted with halogen, n is greater than 1 and less than 30; X is a group containing an olefinic carbon-carbon double or triple bond.

[0011] In the fluorine-containing composition of the present invention, [2] X contains at least one fluorine atom, and L is selected from the group consisting of a cyclopentylidene group which may have a substituent, a cyclohexylidene group which may have a substituent, and a cyclododecylidene group which may have a substituent; [3] The fluorine-containing compound has a structure of the following formula: [ka] where n is greater than 1 and less than 30. [4] The bifunctional crosslinking agent does not contain a fluorine atom; is preferred.

[0012] The present invention also provides a varnish comprising the above fluorine-containing composition and a solvent.

[0013] The present invention further provides an insulated wire comprising a conductor and an insulating coating, the insulating coating being made of the above-mentioned fluorine-containing composition. Effect of the Invention

[0014] According to the present invention, a cured product having excellent flexibility and a low dielectric constant can be obtained. According to the present invention, a varnish for easily coating with the cured product can be obtained. Furthermore, according to the present invention, an insulated wire having an insulating coating having excellent flexibility and a low dielectric constant can be obtained. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram showing a flexibility evaluation using a steel rod in the examples. [Diagram 2] FIG. 2 is a schematic diagram showing a flexibility evaluation after removing a steel bar in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (Fluorine-containing composition) A first important feature of the fluorine-containing composition of the present invention is that it is a composition containing a fluorine-containing compound and a bifunctional crosslinking agent described below, and a second important feature is that the content of the bifunctional crosslinking agent is more than 30 mass% and less than 70 mass%, when the total amount of the fluorine-containing compound and the bifunctional crosslinking agent is taken as 100 mass%. That is, as is clear from the results of the Examples described later, the composition of the present invention exhibits excellent flexibility, whereas when a trifunctional or tetrafunctional crosslinking agent is used instead of a bifunctional crosslinking agent, or when a bifunctional crosslinking agent is used in an amount outside the above range, a cured product having excellent flexibility cannot be obtained. The content of the bifunctional crosslinking agent is more preferably 35% by mass or more and 65% by mass or less, and further preferably 40% by mass or more and 60% by mass or less.

[0017] [Fluorine-containing compounds] The fluorine-containing compound constituting the fluorine-containing composition of the present invention comprises a structural unit A having a structure containing a 3- to 12-membered cyclic structure in the main skeleton in which 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms, a structural unit B having a structure containing a benzene ring in the main skeleton in which fluorine atoms account for 30% or less of the number of atoms in the structural unit, and a structural unit C having an olefinic carbon-carbon double bond or a carbon-carbon triple bond, thereby enabling the fluorine-containing compound to have the respective functions possessed by the above structural units A to C. That is, the compound has excellent electrical properties (low dielectric constant) and flame retardancy that are possessed by the structural unit A, and excellent solvent solubility and high glass transition temperature that are possessed by the structural unit B. In addition, since the structural unit C is positioned at the end of the compound, the excellent reactivity of the structural unit C makes it possible to provide excellent thermosetting properties.

[0018] In the fluorine-containing compound constituting the fluorine-containing composition of the present invention, the structural units A to C are The order of bonding is preferably CB-(AB)nC···(i) or CA-(BA)nC···(ii), which makes it possible to obtain a cured product with a high gel fraction (crosslink density). In the above formulas (i) and (ii), the value of n is preferably greater than 1 and less than 30, more preferably 2 or more and 20 or less, and even more preferably 5 or more and 10 or less. In the above fluorine-containing compound, n represents an average degree of polymerization. The average degree of polymerization can be predicted from the stoichiometric ratio of monomers, and can also be measured by a conventionally known method such as nuclear magnetic resonance spectroscopy. In the present invention, "n is 1" means that the average degree of polymerization of the compound is 0.5 to 1.4. In the present invention, n may be expressed as an integer, but similarly includes those having a distribution.

[0019] <Constituent unit A> The structural unit A constituting the above fluorine-containing compound contains a 3- to 12-membered cyclic structure in the main skeleton, and has a structure in which 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms. By substituting 50% or more, preferably 100%, of the hydrogen atoms in the cyclic structure of the structural unit A with fluorine atoms, it is possible to impart the excellent electrical properties and flame retardancy that fluorine possesses to the fluorine-containing compound. In the structural unit A, the main skeleton may have three or more 3- to 12-membered ring structures, but the main skeleton preferably has one or two ring structures, and the main skeleton preferably has one to three ring structures including the side chains. The elements constituting the ring structures are not particularly limited, and examples thereof include carbon atoms, nitrogen atoms, oxygen atoms, sulfur atoms, and silicon atoms.

[0020] Specific examples of the structural unit A include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclononene, cyclodecene, cyclobutadiene, cyclopentadiene, cyclohexadiene, cycloheptadiene, cyclooctadiene, cyclononadiene, cyclodecadiene, cycloheptatriene, cyclooctatriene, cyclododecatriene, benzene, biphenyl, terphenyl, pentalene, indene, naphthalene, azulene, heptalene, indane, acenaphthylene, fluorene, spirofluorene, benzofluorene, dibenzofluorene, phenalene, phenanthrene, anthracene, fluoranthene, triphenylene, pyrene, chrysene, naphthal ... Futacene, picene, perylene, pentaphene, hexacene, pentacene, rubicene, coronene, ovalene, pyrrole, thiophene, furan, imidazole, pyrazole, thiazole, isothiazole, oxazole, isoxazole, pyridine, pyrazine, pyrimidine, pyridazine, isoindoline, indoline, indazoline, purine, quinoline, isoquinoline, benzoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, galbazole, phenanthridine, acridine, phenanthroline, phenazine, benzimidazole, benzofuran, benzothiophene, isobenzothiazole, benzoxazole, isobenzoxazole, triazole, tetrazole, oxadiazole, triazine, dibenzofuran, dibenzothiophene, benzocarbazole, dibenzocarbazole, thiadiazole, imidazopyridine, and the like. When the structural unit A contains a plurality of 3- to 12-membered cyclic structures, they may be the same structure or different structures.

[0021] Examples of the substituent include any of the following substituents. fluorine, chlorine, bromine, iodine, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphate group or a salt thereof, a C1-C60 alkyl group, a C2-C60 alkenyl group, a C2-C60 alkynyl group, and a C1-C60 alkoxy group; Fluorine, chlorine, bromine, iodine, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, hydrazone group, carboxylic acid group or a salt thereof, sulfonic acid group or a salt thereof, phosphoric acid group or a salt thereof, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, biphenyl group, terphenyl group, pentalenyl group, indenyl group, naphthyl group, azulenyl group, heptalenyl group, indanyl group, acenaphthyl group, fluorenyl group , spiro-fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, phenalenyl group, phenanthrenyl group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, picenyl group, perylenyl group, pentaphenyl group, hexacenyl group, pentacenyl group, rubicenyl group, coronenyl group, ovalenyl group, pyrrolyl group, thiophenyl group, furanyl group, imidazolyl group, pyrazolyl group, thiazolyl group, isothiazolyl group, oxazolyl group , isoxazolyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, isoindolyl group, indolyl group, indazolyl group, purinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthyridinyl group, quinoxalinyl group, quinazolinyl group, cinnolinyl group, carbazolyl group, phenanthridinyl group, acridinyl group, phenanthrolinyl group, phenazinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothio a C1-C60 alkyl group, a C2-C60 alkenyl group, a C2-C60 alkynyl group, and a C1-C60 alkoxy group substituted with at least one selected from the group consisting of an azolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group;

[0022] Cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl, cyclohexenyl, phenyl, biphenyl, terphenyl, pentalenyl, indenyl, naphthyl, azulenyl, heptalenyl, indanyl, acenaphthyl, fluorenyl, spiro-fluorenyl, benzofluorenyl, dibenzofluorenyl, phenalenyl, phenanthrenyl, nyl group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, picenyl group, perylenyl group, pentaphenyl group, hexacenyl group, pentacenyl group, rubicenyl group, coronenyl group, ovalenyl group, pyrrolyl group, thiophenyl group, furanyl group, imidazolyl group, pyrazolyl group, thiazolyl group, isothiazolyl group, oxazolyl group, isoxazolyl group groups, pyridinyl groups, pyrazinyl groups, pyrimidinyl groups, pyridazinyl groups, isoindolyl groups, indolyl groups, indazolyl groups, purinyl groups, quinolinyl groups, isoquinolinyl groups, benzoquinolinyl groups, phthalazinyl groups, naphthyridinyl groups, quinoxalinyl groups, quinazolinyl groups, cinnolinyl groups, carbazolyl groups, phenanthridinyl groups, acridinyl groups, phenanthrolinyl groups, phenazinyl groups, benzimidazolyl groups, benzofuranyl groups, benzothiophenyl groups, isobenzothiazolyl groups, benzoxazolyl groups, isobenzoxazolyl groups, triazolyl groups, tetrazolyl groups, oxadiazolyl groups, triazinyl groups, dibenzofuranyl groups, dibenzothiophenyl groups, benzocarbazolyl groups, dibenzocarbazolyl groups, thiadiazolyl groups, imidazopyridinyl groups and imidazopyrimidinyl groups;

[0023] Fluorine, chlorine, bromine, iodine, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, hydrazone group, carboxylic acid group or a salt thereof, sulfonic acid group or a salt thereof, phosphoric acid group or a salt thereof, C1-C60 alkyl group, C2-C60 alkenyl group, C2-C60 alkynyl group, C1-C60 alkoxy group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, biphenyl group, terphenyl group, pentalenyl group, indenyl group, naphthyl group, azulenyl group, heptalenyl group, isopropyl group, butyl ... acenaphthyl, fluorenyl, spiro-fluorenyl, benzofluorenyl, dibenzofluorenyl, phenalenyl, phenanthrenyl, anthracenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, picenyl, perylenyl, pentaphenyl, hexacenyl, pentacenyl, rubicenyl, coronenyl, ovalenyl, pyrrolyl, thiophenyl, furanyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, isoindolyl group, indolyl group, indazolyl group, purinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthyridinyl group, quinoxalinyl group, quinazolinyl group, cinnolinyl group, carbazolyl group, phenanthridinyl group, acridinyl group, phenanthrolinyl group, phenazinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothiazolyl group, benzoxazolyl group, isobenzoxazolyl group, triazolyl group a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indanyl group, or an acenaphthyl group, each of which is substituted with at least one selected from the group consisting of a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group;Fluorenyl, spiro-fluorenyl, benzofluorenyl, dibenzofluorenyl, phenalenyl, phenanthrenyl, anthracenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, picenyl, perylenyl, pentaphenyl, hexacenyl, pentacenyl, rubicenyl, coronenyl, ovalenyl, pyrrolyl, thiophenyl, furanyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, isoindolyl, indolyl, indazolyl, purinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthyridinyl group, quinoxalinyl group, quinazolinyl group, cinnolinyl group, carbazolyl group, phenanthridinyl group, acridinyl group, phenanthrolinyl group, phenazinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothiazolyl group, benzoxazolyl group, isobenzoxazolyl group, triazolyl group, tetrazolyl group, oxadiazolyl group, triazinyl group, dibenzofuranyl group, dibenzothiophenyl group, benzocarbazolyl group, dibenzocarbazolyl group, thiadiazolyl group, imidazopyridinyl group and imidazopyrimidinyl group; etc., A group may have a plurality of substituents, and in this case, the substituents may be the same or different.

[0024] The structural unit A preferably contains a benzene ring or cyclopentenyl. More preferably, it may be benzene which may have a substituent; cyclopentenyl which may have a substituent; a compound in which a benzene ring such as biphenyl or terphenyl which may have a substituent is bonded to another aromatic ring; or a compound in which a benzene ring such as naphthalene which may have a substituent is condensed to another aromatic ring. Particularly preferred are compounds represented by the following structural formulas (A-1') to (A-5').

[0025] [ka] (In the formula, each m independently represents an integer of 0 to 6.)

[0026] In the above structural formula, each R is independently the substituent described above. As described above, the structural unit A is more preferably a structure in which 100% of the hydrogen atoms in the cyclic structure of the main skeleton are substituted with fluorine atoms. That is, the most suitable structures include compounds represented by the following structural formulas (A-1) to (A-5).

[0027] [ka]

[0028] Examples of compounds capable of forming the structural unit A include structural units derived from monomers having a benzene ring, such as hexafluorobenzene, perfluorobiphenyl, perfluoronaphthalene, 4,4-difluorobenzophenone, 1,1'-(1,1,2,2,3,3,4,4,5,5,6,6-dodecafluoro-1,6-hexanediyl)bis-4-fluorobenzene, and structural units derived from monomers having a cyclopentenyl, such as octafluorocyclopentene. Among these, those derived from hexafluorobenzene, perfluorobiphenyl, perfluoronaphthalene, and octafluorocyclopentene, as represented by the above formulas (A-1) to (A-5), are preferred.

[0029] <Structural unit B> The structural unit B constituting the above fluorine-containing compound has a structure containing a benzene ring in the main skeleton, and fluorine atoms account for 30% or less of the number of atoms in the structural unit. It is preferable that the structural unit B does not contain fluorine atoms, and even if it does contain fluorine atoms, it is important that the number of atoms in the structural unit B is 30% or less. This allows the fluorine-containing compound to have excellent solvent solubility and ensures the synthesis of the fluorine-containing compound. The structural unit B may have four or more benzene rings in the main skeleton, but preferably has two or three benzene rings in the main skeleton, and more preferably has a ring structure of 1 to 4 rings including the side chains.

[0030] Examples of the structural unit B include benzene, biphenyl, terphenyl, indene, naphthalene, indane, acenaphthylene, fluorene, spirofluorene, benzofluorene, dibenzofluorene, phenalene, phenanthrene, anthracene, fluoranthene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphene, hexacene, pentacene, rubicene, coronene, ovalene, isoindoline, indoline, indazoline, quinoline, isoquinoline, benzoquinoline, phthalazine, quinoxaline, quinazoline, cinnoline, galbazole, phenanthridine, acridine, phenanthroline, phenazine, benzimidazole, benzofuran, benzothiophene, isobenzothiazole, benzoxazole, isobenzoxazole, dibenzofuran, dibenzothiophene, benzocarbazole, and dibenzocarbazole, which may have a substituent. Examples of the substituent include those exemplified for the structural unit A.

[0031] Such a structural unit B is preferably a structural unit derived from a bisphenol represented by the following formula (B).

[0032] [ka]

[0033] In the formula, L is a structure represented by the following formula (b-1) or (b-2):

[0034] [ka]

[0035] R in the above formulas (b-1) and (b-2) 1 and R 2 are each independently a group selected from the group consisting of a hydrogen atom, a C1-C10 alkyl group, a C1-C10 haloalkyl group, and a C6-C10 aryl group, or R1 and R 2 are groups which together form a ring structure which may have a substituent. Examples of C1-C10 alkyl groups include methyl, ethyl, propyl, 2-methylpropyl (isobutyl), butyl, pentyl, etc. Examples of C1-C10 haloalkyl groups include trifluoromethyl, pentafluoroethyl, perfluoropropyl, etc. Examples of C6-C10 aryl groups include phenyl and naphthyl groups (including 1- and 2-isomers).

[0036] Alternatively, R 1 and R 2 may be a group that, together with each other, forms a ring structure that may have a substituent. Examples of the group that forms a ring structure include a tetramethylene group (forming a cyclopentane ring), a pentamethylene group (forming a cyclohexane ring), an undecamethylene group (forming a cyclododecane ring), a 2-methyl-pentamethylene group (forming a methylcyclohexane ring), a 2,2,4-trimethyl-pentamethylene group (forming a trimethylcyclohexane ring), and a biphenyl-2,2'-diyl group (forming a fluorene ring).

[0037] In the above formula (B), R 3 and R 4may each independently be a hydrogen atom, a fluorine atom, a C1-C10 saturated or unsaturated hydrocarbon group in which some or all of the hydrogen may be substituted with halogen, or a C6-C10 aryl group in which some or all of the hydrogen may be substituted with halogen. Examples of C1-C10 saturated or unsaturated hydrocarbon groups in which some or all of the hydrogen may be substituted with halogen include a methyl group, an ethyl group, a propyl group, a 2-methylpropyl group (isobutyl group), a butyl group, a pentyl group, a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, a vinyl group, an allyl group, a 1-methylvinyl group, a 2-butenyl group, and a 3-butenyl group. Examples of C6-C10 aryl groups in which some or all of the hydrogen may be substituted with halogen include a phenyl group, a naphthyl group (including 1-isomer and 2-isomer), and a perfluorophenyl group.

[0038] Suitable examples of the structural unit B include structural units derived from bisphenol AF (2,2-bis(4-hydroxyphenyl)hexafluoropropane), bisphenol F (bis(4-hydroxyphenyl)methane), bisphenol Z (1,1-bis(hydroxyphenyl)cyclohexane), bisphenol A (2,2'-bis(4-hydroxyphenyl)propane), bisphenol C (2,2-bis(3-methyl-4-hydroxyphenyl)propane), 4-hydroxyphenylbutane, 4,4'-(1,3-dimethylbutylidene)diphenol, bisphenol P (1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene), and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane. Of these, structural units derived from bisphenol AF and bisphenol Z are preferred.

[0039] <Constituent unit C> The structural unit C constituting the above fluorine-containing compound has a structure derived from a reactive compound having an olefinic carbon-carbon double bond or a carbon-carbon triple bond, which makes it possible to impart excellent thermosetting (crosslinking) properties that allow a cured product with a high gel fraction to be molded even without using a crosslinking agent. In addition, the structural unit C preferably contains at least one fluorine atom, and more preferably contains fluorine atoms that account for 50% or less of the number of atoms in the structural unit. This, in combination with the fluorine atoms of the structural unit A, can impart excellent electrical properties and flame retardancy. Furthermore, it is preferable that the structural unit C has a benzene ring. Suitable structural units C include the following structures (C-1) to (C-10).

[0040] [ka]

[0041] In the formula, p is an integer of 0 to 4, and in some embodiments, p is 4. In other embodiments, p is 0. R represents a group selected from the group consisting of C1 to C10 alkyl groups and C6 to C10 aryl groups. R' represents a hydrogen atom or a C1 to C10 alkyl group.

[0042] The structural unit C particularly preferably has the following structures (C-11) to (C-15).

[0043] [ka]

[0044] <Other> The fluorine-containing compound constituting the fluorine-containing composition of the present invention does not exclude containing a small amount of other structural units than the structural units A to C, within the range not impairing the above-mentioned various functions obtained by the structural units A to C. For example, in order to improve electrical properties, a constituent unit derived from an aliphatic diol compound that does not contain a benzene ring or a fluorine atom, or an alicyclic diol compound that does not contain a benzene ring or a fluorine atom, may be contained in an amount of 20 mol % or less of all constituent units constituting the fluorine-containing compound.

[0045] Examples of such aliphatic diol compounds that do not contain a benzene ring or a fluorine atom include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, Panediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexane glycol, 1,2-octyl glycol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 2,3-diisobutyl-1,3-propanediol, 2,2-diisoamyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,8-octanediol, and the like.

[0046] Examples of alicyclic diol compounds not containing a benzene ring or a fluorine atom include cyclohexanediols such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 2-methyl-1,4-cyclohexanediol; cyclohexanedimethanols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol; norbornane dimethanols such as 2,3-norbornane dimethanol and 2,5-norbornane dimethanol; tricyclodecane dimethanol, pentacyclopentadecanedimethanol, 1,3-adamantanediol, 2 ,2-adamantanediol, decalin dimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, isosorbide, 3,9-bis(2-hydroxyethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane, 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane, 3,9-bis(2-hydroxy-1,1-diethylethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane, 3,9-bis(2-hydroxy-1,1-dipropylethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane, and the like.

[0047] [Preferred embodiment] Examples of fluorine-containing compounds suitable for use in the present invention include, but are not limited to, compounds having the following structures (wherein "(*)" indicates the bond position): As described above, the value of n in the following formulas (1) to (10) is preferably greater than 1 and less than 30, more preferably 2 or more and 20 or less, and even more preferably 5 or more and 10 or less.

[0048] [ka]

[0049] [ka]

[0050] In the present invention, the fluorine-containing compound is preferably soluble in a solvent. The term "soluble in a solvent" means that 1 g or more, preferably 10 g or more of the fluorine-containing compound is dissolved in 100 g of a solution obtained from a given solvent. The fluorine-containing compound of the present embodiment is preferably soluble in a hydrocarbon to be described later. In addition, the fluorine-containing compound of the present embodiment is particularly preferably soluble in toluene from the viewpoint of cost. In the fluorine-containing composition of the present invention, the fluorine-containing compound is not limited as long as it satisfies the fluorine atom content specified in each of the above-mentioned structural units A to C, but it is preferable that the fluorine content is 20 to 40 mass% based on the total mass of the fluorine-containing compound, which provides excellent electrical properties as well as excellent solvent solubility and flame retardancy.

[0051] [Bifunctional crosslinking agent] The bifunctional crosslinking agent constituting the fluorine-containing composition of the present invention includes a compound having two olefinic carbon-carbon double bonds in the molecule. Examples of such crosslinking agents include methacrylate compounds, acrylate compounds, allyl compounds, vinyl compounds, etc. Because of their high crosslinking reactivity, methacrylate compounds or acrylate compounds are preferred, and acrylate compounds are particularly preferred. Examples of these crosslinking agents include cyclohexane dimethanol divinyl ether (CHDVE), diethylene glycol divinyl ether (DEGDVE), tri(ethylene glycol) divinyl ether (TEGDVE), butanediol divinyl ether (BDVE), etc. Commercially available products can also be used, such as Karenz (registered trademark) MOI-EG (2-(2-methacryloyloxyethyloxy)ethyl isocyanate) manufactured by Resonac Co., Ltd., Ebecryl (registered trademark) 8402 (bifunctional aliphatic urethane acrylate) and Ebecryl (registered trademark) 150 (EO-modified bisphenol A diacrylate) manufactured by Daicel-Allnex Corporation. The bifunctional crosslinking agent used in the present invention preferably does not contain fluorine atoms, since the composition has high adhesion to conductors and other resin layers. In addition, when the bifunctional crosslinking agent of the present invention has a cyclic structure in its main skeleton, the flexibility of the resulting cured product tends to be high. Therefore, when higher flexibility is required, it is preferable to use a bifunctional crosslinking agent having a cyclic structure in its main skeleton.

[0052] [Other additives] The fluorine-containing composition of the present invention may further contain, as an optional component, any additive known in the art, such as a reaction initiator, a filler, an antifoaming agent, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a colorant (dye or pigment), a flame retardant, a lubricant, a dispersant, etc.

[0053] [Preparation of Composition] The fluorine-containing composition of the present invention can be prepared by mixing a fluorine-containing compound, a bifunctional crosslinking agent, and the other optional components described above. Heating may be performed during mixing. Mixing can be performed using any mixing device known in the art, such as various stirrers, ball mills, bead mills, planetary mixers, and roll mills.

[0054] (varnish) Another embodiment of the present invention is a varnish comprising the fluorine-containing composition of the present invention described above and a solvent. As the solvent, various solvents can be used, but in the present invention, it is preferable to use an aprotic solvent from the viewpoint of solvent solubility. Such aprotic solvents include hydrocarbons such as benzene, toluene, xylene, heptane, cyclohexane, methylcyclohexane, and mineral spirits; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and diisobutyl ketone (DIBK); cyclic ketones such as cyclohexanone, cycloheptanone, and cyclooctanone; esters such as ethyl acetate, butyl acetate, and γ-butyrolactone; cyclic ethers such as tetrahydrofuran (THF), and 1,3-dioxolane; amides such as N,N-dimethylformamide (DMF), diethylformamide (DEF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and N-cyclohexylpyrrolidone; sulfones such as sulfolane and dimethyl sulfone; and sulfoxides such as dimethyl sulfoxide (DMSO). In the present invention, the preferred solvents are hydrocarbons, and aromatic hydrocarbons are particularly preferred. The concentration of the varnish is not particularly limited as long as the fluorine-containing compound and the bifunctional crosslinking agent are uniformly dispersed, but the solid content concentration is desirably 40 to 70 mass%, preferably 45 to 65 mass%, and more preferably 50 to 60 mass%.

[0055] It is preferable to use a reaction initiator because it enables more efficient crosslinking and curing under milder conditions. Examples of reaction initiators that can be used include benzoyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, dicumyl peroxide, cumyl hydroperoxide, α,α'-di(t-butylperoxy)-diisopropylbenzene (Perbutyl (registered trademark) P, manufactured by NOF Corp.), bis(1-methyl-1-phenylethyl)peroxide (Percumyl (registered trademark) D, manufactured by NOF Corp.), t-butyl α,α-dimethylbenzyl peroxide (Perbutyl (registered trademark) C, manufactured by NOF Corp.), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, azobisisobutyronitrile, and the like.

[0056] In the present invention, the filler may be an organic filler or an inorganic filler. Examples of organic fillers that can be used include engineering plastics such as polyphenylene sulfide, polyether ether ketone (PEEK), polyamide, polyimide, and polyamideimide; and solvent-insoluble fluororesins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and copolymers of tetrafluoroethylene and hexafluoropropylene (FEP). Examples of inorganic fillers that can be used include metals; metal oxides such as aluminum oxide, zinc oxide, tin oxide, and titanium oxide; metal hydroxides; metal titanates; zinc borate; zinc stannate; boehmite; silica; glass; silicon oxide; silicon carbide; boron nitride; calcium fluoride; carbon black; mica; talc; barium sulfate; and molybdenum disulfide. Solvent-insoluble fluororesins are preferred in terms of improving the electrical properties (dielectric constant, dielectric loss, etc.) of the cured product of the fluorine-containing composition. Silica is also preferred in that it can reduce the thermal expansion coefficient without impairing the electrical properties (dielectric constant, dielectric loss, etc.) of the cured product of the fluorine-containing composition.

[0057] (Insulated Wire) Another embodiment of the present invention is an insulated wire comprising a conductor and an insulating coating, the insulating coating comprising the above-mentioned fluorine-containing composition of the present invention. The insulated wire may be one in which an insulating coating is formed around the outer periphery of a conductor so that the conductor and the insulating coating are in contact with each other, or another resin layer or the like may be interposed between the conductor and the insulating coating.

[0058] The conductor used in the present invention may be any of those conventionally used in insulated wires, including metal conductors such as copper, copper alloys, copper-clad aluminum, aluminum, silver, gold, and galvanized iron. The cross-sectional shape perpendicular to the longitudinal direction of the conductor used in the present invention is not particularly limited, and examples thereof include conductors with circular or rectangular (rectangular) cross-sectional shapes. Among them, rectangular conductors are preferably used because they have a high space factor when wound. The insulating coating of the present invention has excellent flexibility, so it can be preferably used in applications where many insulated wires are incorporated into a narrow space, i.e., applications where more bending is required. The size of the conductor is not particularly limited, but in the case of a rectangular conductor, the width (long side) of the rectangular cross-sectional shape is preferably 1.0 to 10.0 mm, more preferably 1.0 to 5.0 mm, and even more preferably 1.4 to 4.0 mm, and the thickness (short side) is preferably 0.4 to 3.0 mm, and more preferably 0.5 to 2.5 mm. The ratio of the length of the width (long side) to the thickness (short side) (thickness:width) is preferably 1:1 to 1:20, and more preferably 1:1 to 1:4. On the other hand, in the case of a conductor with a circular cross-sectional shape, the diameter is preferably 0.3 to 3.0 mm, and more preferably 0.4 to 2.7 mm.

[0059] The insulating coating of the insulated wire of the present invention is formed by applying the varnish of the present invention directly or through another layer onto a conductor and baking it. The method of applying the varnish may be a method of immersing the conductor or a conductor on which another layer has already been formed in the varnish in the varnish, a method of using a varnish application die, or any other method known in the art. The baking method is not particularly limited, and for example, a baking furnace can be used, in which the material is heated at 100 to 600° C. for 10 seconds to 12 hours. The thickness of the insulating coating is, for example, 1 to 300 μm, and preferably 10 to 150 μm. The application and / or baking may be repeated until the desired insulating coating is obtained.

[0060] The other layer is a layer different from the insulating coating, and examples thereof include layers made of aromatic polyether ketone resin, fluororesin, polyamide imide, polyether imide, polyether sulfone, and polyphenylene sulfide. EXAMPLES

[0061] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0062] The crosslinking agents used in the present examples and comparative examples are as follows: Cyclohexanedimethanol divinyl ether (CHDVE): Manufactured by Nippon Carbide Industries Co., Ltd., divinyl compound (bifunctional crosslinking agent) Tri(ethylene glycol) divinyl ether (TEGDVE): Manufactured by Nippon Carbide Industries Co., Ltd., divinyl compound (bifunctional crosslinking agent) 1,4-Butanediol divinyl ether (BDVE): Manufactured by Nippon Carbide Industries Co., Ltd., divinyl compound (bifunctional crosslinking agent) 2-(2-methacryloyloxyethyloxy)ethyl isocyanate: Karenz (registered trademark) MOI-EG manufactured by Resonac Co., Ltd., a bifunctional crosslinking agent having both a methacrylate group and an isocyanate group Bifunctional urethane acrylate: Ebecryl (registered trademark) 8402 manufactured by Daicel-Allnex Corporation, an aliphatic urethane acrylate compound (bifunctional crosslinking agent) EO modified bisphenol A diacrylate: Ebecryl (registered trademark) 150 manufactured by Daicel-Allnex Corporation, diacrylate compound (bifunctional crosslinking agent) Triallyl isocyanurate: Shinryo Corporation, TAIC (registered trademark), triallyl compound (trifunctional crosslinking agent) Trifunctional urethane acrylate: Daicel-Allnex Corporation's KRM8667, an aliphatic urethane acrylate compound (trifunctional crosslinking agent) 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione: manufactured by Resonac Corporation, KarenzMT (registered trademark) NR1, trithiol compound (trifunctional crosslinking agent) Pentaerythritol tetrakis(3-mercaptobutyrate): manufactured by Resonac Corporation, KarenzMT (registered trademark) PE1, tetrathiol compound (tetrafunctional crosslinking agent)

[0063] Example 1 0.400g of a fluorine-containing compound represented by the following formula was added to 0.600g of methyl ethyl ketone (MEK) and stirred at 60°C for 20 minutes to dissolve. The mixture was allowed to cool to room temperature, and 0.267g of cyclohexane dimethanol divinyl ether (CHDVE) as a bifunctional crosslinking agent and 0.013g of bis(1-methyl-1-phenylethyl) peroxide (Percumyl (registered trademark) D, manufactured by NOF Corporation) as a reaction initiator were added and stirred at room temperature for another 10 minutes to obtain a composition. When the total of the fluorine-containing compound and the bifunctional crosslinking agent is 100% by mass, the content of the bifunctional crosslinking agent is 40% by mass.

[0064] [ka] (n=7.)

[0065] The above composition was applied to an aluminum metal plate of 100 mm x 100 mm x 0.1 mm thickness using an applicator (wet film coater "Jieoto" (registered trademark) No. 5) with a gap size of 400 μm. The plate was pre-dried for 10 minutes in a thermostatic chamber (STPH-202M manufactured by Espec Corporation) set at 210 ° C., and then baked for 2 minutes in a thermostatic chamber set at 500 ° C. to obtain a test piece. The coating thickness after baking was 70 μm.

[0066] (Examples 2 to 9, Comparative Examples 1 to 12) Similarly to Example 1, compositions were prepared so as to have the crosslinking agents and crosslinking agent contents shown in Table 1 below, and test pieces were obtained.

[0067] Comparative Example 13 A test piece was obtained in the same manner as in Example 2, except that a fluorine-containing compound represented by the following formula was used.

[0068] [ka] (n=1.)

[0069] Comparative Example 14 A test piece was obtained in the same manner as in Example 2, except that a fluorine-containing compound represented by the following formula was used.

[0070] [ka] (n=36.)

[0071] (Reference example) A commercially available polyimide resin precursor varnish was applied to an aluminum metal plate instead of the fluorine-containing compound in Example 1. The plate was pre-dried in a thermostatic chamber set at 150°C for 10 minutes, and then baked and imidized in a thermostatic chamber set at 500°C for 2 minutes to obtain a metal plate (test piece) coated with a polyimide resin.

[0072] (Flexibility evaluation) The test pieces obtained in the Examples, Comparative Examples, and Reference Examples were used, with the coating surface facing outward, and the metal surface was placed against a steel rod with a diameter of 4 mm, and bent 180 degrees (in a U-shape) (see FIG. 1). The coating was checked for cracks on the edges of the bent portion, and those that showed no cracks were rated as ◯, and those that showed cracks were rated as ×. For test pieces rated as ◯, the steel rod was removed and the pieces were further bent until the metal plates were in close contact with each other, and those that showed no cracks on the edges of the bent portion were rated as ◎ (see FIG. 2). The results are shown in Table 1.

[0073] [Table 1]

[0074] From the results in Table 1, Examples 1 to 9 using a bifunctional crosslinking agent showed excellent flexibility, whereas Comparative Examples 6 to 11 using a trifunctional crosslinking agent and Comparative Example 12 using a tetrafunctional crosslinking agent showed no flexibility. Furthermore, compared to Examples 1 and 2, Comparative Examples 2 and 3 using the same bifunctional crosslinking agent but with a small addition ratio of the crosslinking agent, and Comparative Example 4 with a large addition ratio showed no flexibility. Furthermore, in Comparative Examples 13 and 14, which differ from Example 2 only in the degree of polymerization of the fluorine-containing compound, no flexibility was observed.

[0075] (Dielectric constant evaluation) The compositions of Examples 2, 7 to 9 and Reference Example were dropped onto a boat-shaped aluminum foil pan with a width of 3 mm, a length of 40 mm and a height of 7 mm. The MEK was removed by heating at 150°C for 40 minutes using a hot plate. The mixture was then heated to 250°C at a heating rate of 10°C / min using a hot plate. The mixture was then held at 250°C for 80 minutes to obtain a cured product. After cooling to room temperature, the cured product was peeled off from the aluminum pan. The cured product was ground with abrasive paper to a length of 30 mm±0.1 mm to obtain a rod-shaped sample. The dielectric constant of the obtained sample was measured in accordance with ASTM D2520 using a 1 GHz cavity resonator (Keycom Corporation DPS18). The measurement of the dielectric constant was carried out in an environment of a temperature of 23°C ± 1°C and a humidity of 50% RH ± 5% RH. The obtained results are shown in Table 2.

[0076] [Table 2]

[0077] The results in Table 2 make it clear that all of the compositions of the Examples exhibit a dielectric constant superior to that of the conventionally used polyimide resin (Reference Example). [Industrial Applicability]

[0078] According to the present invention, it is possible to obtain a cured product having both excellent flexibility and low dielectric constant. The cured product is useful not only as an insulating coating for insulated electric wires, but also in a wide range of fields requiring both flexibility and insulation, such as flexible circuit board materials. [Explanation of symbols]

[0079] 1 Test piece 2 steel rod

Claims

1. A fluorine-containing composition comprising a fluorine-containing compound and a bifunctional crosslinking agent, The fluorine-containing compound is a structural unit A having a structure which contains a 3- to 12-membered cyclic structure in its main skeleton, and in which 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms; A structural unit B having a structure that includes a benzene ring in the main skeleton and in which fluorine atoms account for 30% or less of the total number of atoms in the structural unit; and A structural unit C having an olefinic carbon-carbon double bond or carbon-carbon triple bond, Including, The structural units A to C are C-B-(AB)n-C or C-A-(B-A)n-C (wherein n is greater than 1 and less than 30), A fluorine-containing composition comprising more than 30 mass% and less than 70 mass% of the bifunctional crosslinking agent, when the total amount of the fluorine-containing compound and the bifunctional crosslinking agent is 100 mass%.

2. 2. The fluorine-containing composition of claim 1, wherein the fluorine-containing compound has a structure of formula (I): 【Chemistry 1】 In the formula, L is a structure represented by the following formula (II) or (III): 【Chemistry 2】 R １ and R ２ are each independently a group selected from the group consisting of a hydrogen atom, a C1-C10 alkyl group, a C1-C10 haloalkyl group, and a C6-C10 aryl group, or R １ and R ２ are groups which together form a ring structure which may have a substituent, R ３ and R ４ are each independently a group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1 to C10 saturated or unsaturated hydrocarbon group in which some or all of the hydrogen atoms may be substituted with halogens, and a C6 to C10 aryl group in which some or all of the hydrogen atoms may be substituted with halogens; n is greater than 1 and less than 30; X is a group containing an olefinic carbon-carbon double bond or carbon-carbon triple bond.

3. said X containing at least one fluorine atom; 3. The fluorine-containing composition according to claim 2, wherein said L is selected from the group consisting of an optionally substituted cyclopentylidene group, an optionally substituted cyclohexylidene group, and an optionally substituted cyclododecylidene group.

4. 4. The fluorine-containing composition of claim 3, wherein the fluorine-containing compound has the structure: 【Chemistry 3】 wherein n is greater than 1 and less than 30.

5. The fluorine-containing composition according to any one of claims 1 to 4, wherein the bifunctional crosslinking agent does not contain a fluorine atom.

6. A varnish comprising the fluorine-containing composition according to any one of claims 1 to 4 and a solvent.

7. The varnish of claim 6 , wherein the difunctional crosslinker does not contain fluorine atoms.

8. 5. An insulated wire comprising a conductor and an insulating coating, the insulating coating comprising the fluorine-containing composition according to claim 1.

9. The insulated wire of claim 8 , wherein the difunctional crosslinking agent does not contain fluorine atoms.

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