Cured product using a crosslinking agent

Abstract

The present invention provides a cured product that exhibits excellent electrical properties, thermal stability, flame retardancy, dimensional stability, handling properties, and solvent solubility of the material before curing, while also possessing the superior electrical properties required for next-generation high-frequency and semiconductor packaging. [Solution] In a cured product comprising a crosslinking agent and a crosslinkable compound as needed, The aforementioned crosslinking agent is a crosslinking agent having three or more groups shown in the following formula (1) in its molecule, -OR ···(1) In the formula, R is a hydrocarbon group having at least one unsaturated bond and a cyclic structure, wherein all hydrogen atoms bonded to the cyclic structure are substituted with fluorine. The crosslinkable compound is characterized by being a crosslinkable compound having multiple unsaturated bonds.

Description

[Technical Field] 【0001】 The present invention relates to a cured product of a thermosetting resin crosslinked with a crosslinking agent, and more specifically, to a cured product that, when crosslinked with a crosslinking agent, has superior electrical properties and thermal stability compared to conventional products, and can be suitably used as an electronic substrate material or coating material. [Background technology] 【0002】 Thermosetting resins are used in a wide range of fields, including paints, encapsulants, semiconductor packages, electronic circuit board materials, wire insulation materials, power semiconductors (power devices), and construction materials, due to their mechanical properties, electrical insulation, heat resistance, and dimensional stability. Thermosetting resins used as coatings for electric wires and the like require properties such as thermal stability, hardness, and electrical insulation. As a resin material, for example, an epoxy resin cured product (Patent Document 1) consisting of an epoxy resin and an imide group-containing curing agent is used as a material with excellent electrical stability under high temperature and high electric field conditions. However, Patent Document 1 mentioned above does not take into account the thin-film formability (solvent solubility), high handling properties, and toughness (brittleness) that makes cracks more likely to occur during thin-film molding, which are required in practical applications. 【0003】 Furthermore, in recent years, development has been progressing on next-generation high-frequency technology for information and communication devices such as smartphones and tablet terminals, which enables high-speed and high-capacity transmission. To accommodate this, the substrate materials used are required to have low dielectric constant and low dielectric loss tangent, which can reduce transmission loss. Conventionally, epoxy resins, polyphenylene ether resins (Patent Document 2), fluorinated poly(arylene ethers) and crosslinkable fluorinated poly(arylene ethers) (Patent Documents 3 and 4), or fluororesins such as perfluororesins in which all hydrogen atoms in the molecular chain are replaced with fluorine have been used as resin materials for the above-mentioned high-speed communication and transmission because they have excellent electrical properties. 【0004】 However, in order to fabricate substrates that can handle next-generation high frequencies exceeding 5 GHz, the substrate material also needs to have even better electrical properties, a low coefficient of thermal expansion after heat curing that enables use over a wide temperature range, a high glass transition temperature that allows use and soldering in high-temperature environments, or the ability to reliably form the prepreg used in substrate fabrication. From this perspective, the applicant has proposed a fluororesin as a substrate material for high-speed communication and transmission that has excellent electrical properties (low dielectric constant and low dielectric loss tangent), excellent dimensional stability, high solvent solubility to facilitate thin film molding, and excellent crosslinking properties that enable film formation by heating to about 200°C, as well as excellent heat resistance (Patent Document 5). [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Patent No. 6960705 [Patent Document 2] Japanese Patent Publication No. 2017-128718 [Patent Document 3] U.S. Patent No. 5115082 [Patent Document 4] U.S. Patent No. 5179188 [Patent Document 5] Japanese Patent Publication No. 2022-89150 [Overview of the Initiative] [Problems that the invention aims to solve] 【0006】 While some of the various thermosetting resins mentioned above can be cured on their own, reacting them with a crosslinking agent forms a crosslinked structure, resulting in cured products with a wider variety of structures and properties. This improves performance, such as a higher glass transition temperature and improved dimensional stability. Therefore, conventionally, crosslinking agents consisting of polyfunctional monomers such as isocyanurate derivatives, divinylbenzene, bismaleimides, or bistriazenes, particularly triallyl isocyanate (TAIC), have been used. However, in addition to thermal stability and electrical properties, the coating materials for electric wires and the like are particularly expected to have solvent solubility, high handling properties, toughness, etc. from the ease of processing. In order to produce substrates, semiconductor packages, etc. that can support next-generation high frequencies exceeding 5 GHz, a cured product having more suitable electrical properties, a high glass transition temperature, and excellent heat resistance is particularly expected. 【0007】 Therefore, an object of the present invention is to provide a cured product composed of a crosslinking agent and, if necessary, a crosslinkable compound (prepolymer) contained therein, which has a high glass transition temperature, excellent flame retardancy, high handling properties, and excellent electrical properties required for next-generation high frequencies and semiconductor packages. In particular, a cured product composed of a crosslinking agent having three or more of a specific group in the molecule and a crosslinkable compound which is a specific fluorine-containing compound is provided. 【Means for Solving the Problems】 【0008】 According to the present invention, in a cured product composed of a crosslinking agent and, if necessary, a crosslinkable compound contained, the crosslinking agent is a crosslinking agent having three or more groups represented by the following formula (1) in the molecule, -O-R···(1) In the formula, R is a hydrocarbon group having at least one unsaturated bond and a cyclic structure, and all the hydrogens bonded to the cyclic structure are substituted with fluorine. There is provided a cured product characterized in that the crosslinkable compound is a crosslinkable compound having a plurality of unsaturated bonds. 【0009】 In the present invention, it is preferable that the formula (1) in the crosslinking agent is a group represented by the following formula (2). 【Chemical formula】 In the formula, X is a crosslinking group containing an unsaturated bond. 【0010】 In the cured product of the present invention, the crosslinkable compound includes a structural unit A having a 3- to 12-membered cyclic structure in the main skeleton, and having a structure in which 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms, a structural unit B having a benzene ring in the main skeleton and having a structure in which the fluorine atoms are 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 are C-B-(A-B)n-C or C-A-(B-A)n-C (where n = 0 to 1) It is preferably a fluorine-containing compound bonded in this order. 【0011】 In the present invention, it is preferable that the cured product contains the crosslinking agent and the crosslinkable compound in a mass ratio of 20:80 to 100:0. 【0012】 The cured product of the present invention is more preferably used as a coating material when the crosslinking agent and the crosslinkable compound are contained in a mass ratio of 20:80 to 50:50. 【0013】 The cured product of the present invention is more preferably used for an electronic substrate, a sealing material, or a semiconductor package when the crosslinking agent and the crosslinkable compound are contained in a mass ratio of 50:50 to 80:20. 【Advantages of the Invention】 【0014】 In the cured product of the present invention, by comprising the above-described specific crosslinking agent and, if necessary, a crosslinkable compound (prepolymer) which is a fluorine-containing compound, as is clear from the results of the examples and comparative examples described later, it becomes possible to improve the electrical properties, thermal stability, flame retardancy, dimensional stability, handling properties, and solvent solubility of the material before curing. Furthermore, the cured product of the present invention can have its excellent properties adjusted according to the application by changing the ratio of the crosslinking agent to the crosslinkable compound. That is, as can be seen from the results of the examples described later, when the crosslinking agent content is high, a cured product with particularly excellent electrical properties, thermal stability, dimensional stability, and hardness can be provided, while when the crosslinkable compound content is high, a cured product with particularly excellent handling properties, solvent solubility of the material before curing, and toughness can be provided. [Modes for carrying out the invention] 【0015】 (cured product) The cured product of the present invention is a cured product comprising a crosslinking agent and a crosslinkable compound as needed, wherein the crosslinking agent has three or more groups shown in the following formula (1) in its molecule. -OR ···(1) In the formula, R is a hydrocarbon group having at least one unsaturated bond and a cyclic structure, wherein all hydrogen atoms bonded to the cyclic structure are substituted with fluorine. Furthermore, the crosslinkable compound included as needed is a crosslinkable compound having multiple unsaturated bonds, and is particularly preferably a fluorine-containing compound. In this invention, the term "cured product" refers to a fully cured product with a gel fraction of 100% in the thermosetting properties evaluation (gel fraction) described later. Details of the crosslinking agent and crosslinkable compound will be described later. 【0016】 In the cured product of the present invention, the mass ratio of the crosslinking agent to the crosslinkable compound is preferably in the range of 20:80 to 100:0, and more preferably in the range of 20:80 to 80:20. This makes it possible to obtain a cured product with a high glass transition temperature and decomposition temperature, excellent heat resistance, and superior electrical properties, while also providing sufficient hardness to the cured product. Here, a mass ratio of 100:0 between the crosslinking agent and the crosslinkable compound means that the cured product consists only of the crosslinking agent of the present invention, without containing the crosslinkable compound. In the crosslinking agent of the present invention, all hydrogen atoms in the cyclic structure of the three groups constituting the crosslinking agent are replaced with fluorine atoms, so even a cured product consisting only of the crosslinking agent has excellent electrical properties. Furthermore, even a cured product consisting only of the crosslinking agent has sufficient solubility as a material before curing by using a crosslinking agent that is solvent-soluble. 【0017】 The cured product of the present invention, by possessing the above-mentioned characteristics, has superior electrical properties, thermal stability, flame retardancy, dimensional stability, handling properties, and solvent solubility of the material before curing compared to cured products of conventional thermosetting resins. However, since the properties improved differ depending on the mass ratio of the crosslinking agent and the crosslinkable compound contained as needed, it is preferable to adjust the mass ratio according to the application. In other words, when the mass ratio of the crosslinking agent to the crosslinkable compound is in the range of 20:80 to 50:50, it exhibits particularly excellent solvent solubility, handling properties, and toughness, making it suitable for use in coatings and other applications. Furthermore, when the mass ratio of the crosslinking agent to the crosslinkable compound is in the range of 50:50 to 80:20, it exhibits particularly excellent electrical properties, thermal stability, dimensional stability, and hardness, making it suitable for use in applications such as electronic substrates, encapsulants, and semiconductor packages. 【0018】 Furthermore, since the cured product of the present invention has excellent solvent solubility in the crosslinking agent and crosslinkable compound that constitute the cured product, it can be prepared as a varnish-like composition obtained by dissolving them in a solvent, and since a cured product can be obtained by curing such a varnish-like composition, cured products of various forms can be molded, and it is also possible to coat a substrate such as an electric wire with it and use it as a coating material. The solvent capable of dissolving the crosslinking agent and crosslinkable compound constituting the cured product of the present invention is not limited to the above, but is preferably an aprotic solvent. 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, preferred solvents are hydrocarbons, and particularly preferred are aromatic hydrocarbons. 【0019】 (Crosslinking agent) The crosslinking agent constituting the cured product of the present invention has three or more of the groups shown in formula (1) in its molecule, where R has at least one unsaturated bond and a cyclic structure, and all hydrogen atoms bonded to the cyclic structure are substituted with fluorine, forming a hydrocarbon group. 【0020】 Examples of the cyclic structure of R in formula (1) include a benzene ring, cyclopentenyl, biphenyl, etc., but a benzene ring is particularly preferred. A benzene ring cyclic structure improves electrical properties (dielectric properties) and increases the glass transition temperature and decomposition temperature, thereby imparting excellent heat resistance to the cured product. Furthermore, because all the hydrogen atoms bonded to the cyclic structure are replaced with fluorine, it becomes possible to obtain a cured product that possesses the excellent electrical properties and flame retardancy of fluorine, as well as improved decomposition temperature (heat resistance). Specifically, the following equations (2) and (3) can be given as examples of equation (1). 【0021】 [ka] In the formula, X is a bridging group containing an unsaturated bond. 【0022】 [ka] 【0023】 Furthermore, in formula (2) above, the bridging group X containing the unsaturated bond is preferably located in the para position of the oxygen atom. The para position of the bridging group X reduces steric hindrance, making the bridging reaction more likely to occur, and the molecular structure becomes more symmetrical than when it is in the ortho or meta position, resulting in better electrical properties. In the present invention, the crosslinking agent is preferably one of the following formulas (4) and (5), and is particularly preferably one of the following formulas (4). 【0024】 [ka] 【0025】 [ka] 【0026】 In the present invention, the basic skeleton into which the group represented by formula (1) is introduced in the crosslinking agent is preferably a trivalent or tetravalent organic group. A trivalent or tetravalent organic group is a residue obtained by removing three or four hydrogen atoms from a base organic compound. Examples of the base organic compound include aliphatic compounds such as 2,2-dimethylpropane; cyclic aliphatic compounds such as cyclohexane; aromatic compounds such as benzene, triphenylmethane, and triphenylethane; and heterocyclic compounds such as triazine and isocyanurate. In the present invention, specific examples of crosslinking agents include the following formulas (6) to (9), with formulas (6) and (7) being particularly preferred, and formula (6) being the most preferred. 【0027】 [ka] 【0028】 [ka] 【0029】 [ka] 【0030】 [ka] 【0031】 In the present invention, it is preferable that the crosslinking agent is soluble in the solvent. Solubility of the crosslinking agent in the solvent means that 1 g or more, preferably 10 g or more, of the crosslinking agent is dissolved in 100 g of the solution obtained from a given solvent. The crosslinking agent is preferably soluble in hydrocarbons such as benzene, toluene, xylene, heptane, cyclohexane, methylcyclohexane, and mineral spirits, and is particularly preferred to be soluble in toluene from a cost viewpoint. 【0032】 (Crosslinkable compound) The crosslinkable compound that may be optionally included in the cured product of the present invention is a precursor of a thermosetting resin and is a crosslinkable compound (prepolymer) having multiple unsaturated bonds, such as modified phenylene ether, maleimide, or citraconimide. Among these, the following fluorine-containing compounds, which have excellent electrical properties and flame retardancy, can be preferably used. In other words, it is preferable that the crosslinkable compound is a fluorine-containing compound comprising: a structural unit A having a cyclic structure of 3 to 12 membered rings in its main skeleton, wherein 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms; a structural unit B having a benzene ring in its main skeleton, wherein 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, wherein the structural units A to C are bonded together with structural unit C as the terminal. 【0033】 The above fluorine-containing compound possesses the excellent electrical properties (low dielectric constant and low dielectric loss tangent) and flame retardancy of the above constituent unit A, the excellent solvent solubility and high glass transition temperature of the above constituent unit B, and, because the above constituent unit C is located at the end of the compound, the excellent reactivity of constituent unit C makes it possible to obtain excellent thermosetting properties that enable the formation of cured products with a high gel fraction. 【0034】 This fluorine-containing compound consists of the constituent units A to C, CB-(AB) n -C···(i) or CA-(BA) n -C···(ii) The compounds are bonded in the order shown, with the value of n being in the range of 0 to 4, and it is particularly preferable that the low molecular weight compound has a value of n of 1 or 0. This increases the proportion of crosslinking sites in the compound, resulting in a high gel fraction (crosslinking density) and a hard cured product, as well as the advantage of a low thermal expansion coefficient of the cured product. In formula (i) or (ii) above, n represents the average degree of polymerization. The average degree of polymerization can be predicted from the stoichiometric ratio of monomers, or it can be measured by conventionally known methods such as nuclear magnetic resonance spectroscopy. In this invention, "n is 1" means that the average degree of polymerization of the compound is 0.5 to 1.4. In this invention, n may be expressed as an integer, but this includes those with similar distributions. 【0035】 [Component Unit A] The aforementioned constituent unit A has a structure in which a 3- to 12-membered ring cyclic structure is included in the main skeleton, and 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 constituent unit A with fluorine atoms, it is possible to impart the excellent electrical properties and flame retardancy of fluorine to the fluorine-containing compound. In constituent unit A, the 3- to 12-membered ring structure may have three or more ring structures in the main skeleton, but preferably there are one or two in the main skeleton, and including the side chains, there are preferably one to three ring structures. The elements constituting the ring structure are not particularly limited, and examples include carbon atoms, nitrogen atoms, oxygen atoms, sulfur atoms, silicon atoms, etc. 【0036】 Specifically, constituent unit A may include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclononene, cyclodecene, cyclobutadiene, cyclopentadiene, cyclohexadiene, cycloheptadiene, cyclooctadiene, cyclonononadiene, cyclodecadien, cycloheptatriene, cyclooctatriene, cyclododecatriene, benzene, biphenyl, terphenyl, pentalene, indene, naphthalene, azulene, heptalene, indan, acenaphthylene, fluorene, spirofluorene, benzofluorene, dibenzofluorene, phenalene, phenanthrene, anthracene, fluorantene, triphenylene, pyrene, chrysene, na Examples include phthacen, picen, perylene, pentaphen, hexacene, pentacene, rubicene, coronene, ovalen, 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, galvazole, phenantholidine, acridine, phenanthroline, phenazine, benzimidazole, benzofuran, benzothiophene, isobenzothiazole, benzoxazole, isobenzoxazole, triazole, tetrazole, oxadiazole, triazine, dibenzofuran, dibenzothiophene, benzocarbazole, dibenzocarbazole, thiadiazole, imidazopyridine, etc. In constituent unit A, when it contains multiple cyclic structures of 3 to 12 members, these structures may be identical or different. 【0037】 Examples of substituents include any of the following: Fluorine, chlorine, bromine, iodine, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, hydrazone group, carboxylic acid group or its salt, sulfonic acid group or its salt, phosphate group or its salt, C1-C60 alkyl group, C2-C60 alkenyl group, C2-C60 alkynyl group, and 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 its salt, sulfonic acid group or its salt, phosphate group or its salt, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, biphenyl group, terphenyl group, pentarenyl group, indenyl group, naphthyl group, azulenyl group, heptarenyl group, indanyl group, acenaphthyl group, fluorenyl group, s Pyro-fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, phenalenyl group, phenantrenyl group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, crisenyl group, naphthacenyl group, picenyl group, perilenyl 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, iso Xazolyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridadinyl group, isoindolyl group, indolyl group, indazolyl group, prinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthilidinyl group, quinoxalinyl group, quinazolinyl group, synnolinyl group, carbazolyl group, phenanthridine group, acridinyl group, phenanthrolinyl group, phenadinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothiazolyl C1-C60 alkyl groups, C2-C60 alkenyl groups, C2-C60 alkynyl groups and C1-C60 alkoxy groups substituted with at least one selected from the group consisting of a 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; 【0038】 Cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, biphenyl group, terphenyl group, pentarenyl group, indenyl group, naphthyl group, azulenyl group, heptarenyl group, indanyl group, acenaphthyl group, fluorenyl group, spirofluorenyl group, benzofluorenyl group, dibenzofluorenyl group, phenalenyl group, phenantrenyl Lu group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, crisenyl group, naphthacenyl group, picenyl group, perilenyl 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 Group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridadinyl group, isoindolyl group, indolyl group, indazolyl group, prinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthilidinyl group, quinoxalinyl group, quinazolinyl group, synnolinyl group, carbazolyl group, phenanthridinel 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 imidazopyridinyl group; 【0039】 Fluorine, chlorine, bromine, iodine, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, hydrazone group, carboxylic acid group or its salt, sulfonic acid group or its salt, phosphate group or its salt, 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, pentarenyl group, indenyl group, naphthyl group, azulenyl group, heptare Nyl group, indanyl group, acenaphthyl group, fluorenyl group, spiro-fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, phenalenyl group, phenantrenyl group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, crisenyl group, naphthacenyl group, picenyl group, perilenyl 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, i Soxazolyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridadinyl group, isoindolyl group, indolyl group, indazolyl group, prinyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthilidinyl group, quinoxalinyl group, quinazolinyl group, sinnolinyl group, carbazolyl group, phenanthridine group, acridinyl group, phenanthrolinyl group, phenadinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothiazolyl group, benzoxazolyl group, isobenzoxazolyl group, Cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, biphenyl group, terphenyl group, pentarenyl group, indenyl group, naphthyl group, azulenyl group, heptarenyl group, indanyl group, cyclopentyl group, azulenyl group, heptarenyl group, indanyl group, substituted with at least one selected from the group consisting of triazolyl group, tetrazolyl group, oxadiazolyl group, triazinyl group, dibenzofuranyl group, dibenzothiophenyl group, benzocarbazolyl group, dibenzocarbazolyl group, thiadiazolyl group, imidazopyridinyl group, and imidazopyrimidinyl group,Acenaphthyl group, fluorenyl group, spiro-fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, phenalenyl group, phenantrenyl group, anthracenyl group, fluoranthenyl group, triphenylenyl group, pyrenyl group, crisenyl group, naphthacenyl group, picenyl group, perilenyl 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, pyridinyl group, pyrimidinyl group, pyridadinyl group, isoindolyl group, indolyl group, indazolyl group, p Linyl group, quinolinyl group, isoquinolinyl group, benzoquinolinyl group, phthalazinyl group, naphthilidinyl group, quinoxalinyl group, quinazolinyl group, sinnolinyl group, carbazolyl group, phenanthridinel group, acridinyl group, phenanthrolinyl group, phenazinyl group, benzimidazolyl group, benzofuranyl group, benzothiophenyl group, isobenzothiazolyl group, benzooxazolyl group, isobenzooxazolyl 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. The molecule may have multiple substituents, and these substituents may be identical or different. 【0040】 Constituent unit A preferably contains a benzene ring or cyclopentenyl. More preferably, it includes benzene which may have substituents; cyclopentenyl which may have substituents; compounds in which a benzene ring is bonded to another aromatic ring, such as biphenyl or terphenyl which may have substituents; and compounds in which a benzene ring is condensed to another aromatic ring, such as naphthalene which may have substituents. Particularly preferred are compounds represented by the following structural formulas (A-1) to (A-5). 【0041】 [ka] (In the formula, m represents an independent integer from 0 to 6.) 【0042】 In the above structural formula, each of the R atoms can be independently one of the substituents mentioned above. As mentioned above, a more preferable structural unit A is one in which 100% of the hydrogen atoms in the cyclic structure of the main skeleton are replaced by fluorine atoms. 【0043】 Examples of compounds capable of forming 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, or structural units derived from monomers having a cyclopentenyl, such as octafluorocyclopentene. Among these, those derived from hexafluorobenzene, perfluorobiphenyl, perfluoronaphthalene, and octafluorocyclopentene are preferred, as shown in formulas (A-1) to (A-5) above. 【0044】 [Component Unit B] In the present invention, the constituent unit B of the fluorine-containing compound has a structure in which a benzene ring is included in the main skeleton and fluorine atoms account for 30% or less of the total number of atoms in the constituent unit. It is preferable that constituent unit B does not contain fluorine atoms, and even if it does contain fluorine atoms, it is important that they account for 30% or less of the total number of atoms in constituent unit B. This provides excellent solvent solubility in the fluorine-containing compound and ensures the reliable synthesis of the fluorine-containing compound. In constituent unit B, the benzene ring may have four or more rings in the main skeleton, but preferably there are two or three rings in the main skeleton, and including the side chains, it is preferable to have a ring structure of 1 to 4 rings. 【0045】 Constituent unit B may have substituents, but examples include benzene, biphenyl, terphenyl, indene, naphthalene, indan, acenaphthylene, fluorene, spirofluorene, benzofluorene, dibenzofluorene, phenalene, phenanthrene, anthracene, fluorantene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphene, hexacene, pentacene, rubicene, coronene, ovalene, isoindoline, indoline, indazoline, quinoline, isoquinoline, benzoquinoline, phthalazine, quinoxaline, quinazoline, cinnoline, galvazole, phenantholidine, acridine, phenanthroline, phenazine, benzimidazole, benzofuran, benzothiophene, isobenzothiazole, benzoxazole, isobenzoxazole, dibenzofuran, dibenzothiophene, benzocarbazole, dibenzocarbazole, etc. Examples of substituents here include those exemplified in the above-mentioned structural unit A. 【0046】 Such a constituent unit B is preferably a constituent unit derived from bisphenols represented by the following formula (B). 【0047】 [ka] 【0048】 In the formula, L has the structure of the following formula (b-1) or (b-2): 【0049】 [ka] 【0050】 In the above equations (b-1) and (b-2), R 1 and R 2 These are, independently of each other, hydrogen atoms, C1~C 10 alkyl groups, C1-C 10 Haloalkyl groups, C6~C 10 A group selected from the group consisting of aryl groups, or R1 and R 2 together form a group having a ring structure which may have substituents. C1-C 10 Examples of the alkyl group of C1-C include a methyl group, an ethyl group, a propyl group, a 2-methylpropyl group (isobutyl group), a butyl group, a pentyl group, and the like. Examples of the haloalkyl group of C1-C 10 include a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, and the like. Examples of the aryl group of C6-C 10 include a phenyl group, a naphthyl group (including 1-isomer and 2-isomer). 【0051】 Alternatively, R 1 and R 2 together may form a group having a ring structure which may have substituents. Examples of the group forming the 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), a biphenyl-2,2'-diyl group (forming a fluorene ring), and the like. 【0052】 In the above formula (B), R 3 and R 4 are each independently a hydrogen atom, a fluorine atom, a saturated or unsaturated hydrocarbon group of C1-C in which some or all of the hydrogens may be substituted by halogen, or an aryl group of C6-C in which some or all of the hydrogens may be substituted by halogen. A saturated or unsaturated hydrocarbon group of C1-C in which some or all of the hydrogens may be substituted by halogen 10 or an aryl group of C6-C in which some or all of the hydrogens may be substituted by halogen. 10 Examples of the saturated or unsaturated hydrocarbon group of C1-C in which some or all of the hydrogens may be substituted by halogen 10Examples of saturated or unsaturated hydrocarbon groups include methyl, ethyl, propyl, 2-methylpropyl (isobutyl), butyl, pentyl, trifluoromethyl, pentafluoroethyl, perfluoropropyl, vinyl, allyl, 1-methylvinyl, 2-butenyl, and 3-butenyl groups. Some or all of the hydrogen atoms may be substituted with halogens in C6-C6 groups. 10 Examples of aryl groups include phenyl groups, naphthyl groups (including 1-isomers and 2-isomers), and perfluorophenyl groups. 【0053】 Examples of suitable constituent units B include those 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), 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis4-hydroxy-3-methylphenyl)cyclohexane, 4,6-di-tert-butylresorcinol, 1,7-dihydroxynaphthalene, etc., with constituent units derived from bisphenol AF and bisphenol Z being particularly preferred. 【0054】 [Constituent Unit C] In the present invention, the constituent unit C of the fluorine-containing compound has a structure derived from a reactive compound having an olefinic carbon-carbon double bond or a carbon-carbon triple bond, thereby enabling the formation of a cured product with a high gel fraction even without the use of a crosslinking agent, thereby providing excellent thermosetting properties (crosslinking properties). Furthermore, it is preferable that the constituent unit C contains at least one fluorine atom, and more specifically, it is preferable that it contains fluorine atoms accounting for 50% or less of the total number of atoms in the constituent unit. This, in combination with the fluorine atoms of constituent unit A, can provide excellent electrical properties and flame retardancy. Furthermore, it is preferable that the constituent unit C has a benzene ring. A preferred constituent unit C includes the following structures (C-1) to (C-10). 【0055】 [ka] 【0056】 In the formula, p is an integer between 0 and 4, and in some embodiments, p is 4. In other embodiments, p is 0. R is C1 to C 10 alkyl groups, and C6~C 10 This represents a group selected from the group consisting of aryl groups. R' represents a hydrogen atom or C1~C 10 It represents the alkyl group. 【0057】 The constituent unit C is particularly preferably having the following structures (C-11) to (C-15). 【0058】 [ka] 【0059】 [Other constituent units] The above-mentioned fluorine-containing compound may contain small amounts of other constituent units other than constituent units A to C, as long as it does not impair the various functions obtained by the above-mentioned constituent units A to C. For example, to improve electrical properties, constituent units derived from aliphatic diol compounds or alicyclic diol compounds that do not contain benzene rings or fluorine atoms can be included in an amount of 20 mol% or less of the total constituent units of the fluorine-containing compound. 【0060】 Examples of aliphatic diol compounds that do not contain a benzene ring or 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, and 2-butyl-2-ethyl-1,3-propyl Examples include pandiols, 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-hexaneglycol, 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, and 2-methyl-1,8-octanediol. 【0061】 Furthermore, examples of alicyclic diol compounds that do not contain a benzene ring or 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; norbornanedimethanols such as 2,3-norbornanedimethanol and 2,5-norbornanedimethanol; tricyclodecanedimethanol; pentacyclopentadecanedimethanol; and 1,3-adamantanediol. Examples include 2,2-adamantanediol, decalindimethanol, 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, and 3,9-bis(2-hydroxy-1,1-dipropylethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane. 【0062】 [Preferred embodiment] The fluorine-containing compounds suitable for use in the cured product of the present invention are not limited to those shown, but examples include compounds having the following structure (wherein n is a value from 0 to 4, and "(*)" indicates the bond position). 【0063】 [ka] 【0064】 [ka] 【0065】 Fluorine-containing compounds are preferably soluble in solvents. "Soluble in solvents" means that 1 g or more, preferably 10 g or more, of the fluorine-containing compound is dissolved in 100 g of the solution obtained from a given solvent. Fluorine-containing compounds are preferably soluble in hydrocarbons, as described later. Furthermore, from a cost perspective, fluorine-containing compounds are particularly preferably soluble in toluene. Fluorine-containing compounds are not limited to those specified above, as long as they satisfy the fluorine atom content defined by each of the constituent units A to C, but it is desirable that the fluorine content be 20 to 40% by mass relative to the total mass of the fluorine-containing compound. This results in excellent electrical properties, as well as excellent solvent solubility and flame retardancy. The fluorine-containing compound preferably has a number-average molecular weight in the range of 500 to 4000, particularly 1000 to 2000. Having a number-average molecular weight in this range improves solvent solubility and crosslinking properties, making it possible to increase the gel fraction of the cured product, as described later. 【0066】 (Other ingredients) The cured product of the present invention may further contain fillers. The cured product of the present invention may further contain any additives known in the art, such as defoamers, heat stabilizers, antistatic agents, ultraviolet absorbers, colorants (dyes or pigments), flame retardants, lubricants, and dispersants. The filler may be an organic filler or an inorganic filler. Suitable organic fillers include: engineering plastics such as polyphenylene sulfide, polyether ether ketone (PEEK), polyamide, polyimide, and polyamide-imide; and solvent-insoluble fluororesins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and copolymers of tetrafluoroethylene and hexafluoropropylene (FEP). Suitable inorganic fillers 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 dioxide; silicon carbide; boron nitride; calcium fluoride; carbon black; mica; talc; barium sulfate; molybdenum disulfide, etc. Solvent-insoluble fluororesins are preferred from the viewpoint of improving the electrical properties (dielectric constant, dielectric loss tangent, etc.) of the cured product of the present invention. Furthermore, silica is preferable because it can reduce the coefficient of thermal expansion without impairing the electrical properties (dielectric constant, dielectric loss tangent, etc.) of the cured product of the present invention. 【0067】 (Manufacturing of hardened products) The cured product of the present invention can be produced by mixing a crosslinking agent with a crosslinkable compound having multiple unsaturated bonds, which may be included as needed, and then thermally curing the mixture. For efficient curing reactions, reaction initiators may be used. 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® P, manufactured by NOF Corporation), bis(1-methyl-1-phenylethyl) peroxide (Permil® D, manufactured by NOF Corporation), t-butyl α,α-dimethylbenzyl peroxide (Perbutyl® C, manufactured by NOF Corporation), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexine, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, and azobisisobutyronitrile. 【0068】 The curing conditions cannot be generalized as they depend on the type and mass ratio of the crosslinking agent and crosslinkable compound used. However, when using the aforementioned crosslinking agent and fluorine-containing compound within the aforementioned mass ratio range, and when using the aforementioned reaction initiator, heating at a temperature of 100 to 300°C for 30 to 180 minutes is preferable. Specifically, when manufacturing a cured product by compression molding, as shown in the examples described later, a crosslinking agent and, if necessary, a crosslinkable compound and / or reaction initiator are dissolved together in a good solvent to prepare a uniform mixed solvent, which is then dried to obtain a mixed powder. This mixed powder is then heated in a mold under pressure of 0.5 to 2.0 MPa, above the reaction temperature of the reaction initiator. As a good solvent capable of dissolving the crosslinking agent and crosslinkable compound, the aforementioned aprotic solvent can be used. 【0069】 Furthermore, a mixed solvent obtained by dissolving a crosslinking agent and, if necessary, a crosslinkable compound and / or reaction initiator in a solvent is impregnated into a carrier such as glass cloth or nonwoven fabric to obtain an impregnated material. After removing the solvent by drying the impregnated material, a cured product containing glass cloth or the like can be obtained by maintaining it above the reaction temperature of the initiator. Furthermore, if the cured product is a coating material for electric wires or metal substrates, it can be obtained by dissolving a crosslinking agent and, if necessary, a contained crosslinkable compound and / or reaction initiator in a solvent to obtain a mixed solvent (varnish-like composition), applying it to the electric wire or metal substrate, drying it to remove the solvent, and then holding it at a temperature above the reaction initiation temperature of the initiator. [Examples] 【0070】 (Synthesis of crosslinking agent (a) of formula (6) above) A glass reaction vessel was loaded with 0.126 g (1.0 mmol) of phloroglucinol (anhydrous) and 0.160 g (4.0 mmol) of sodium hydroxide. The glass reaction vessel was then vacuumed and purged with nitrogen. Next, 5 mL of DMAc and 0.582 g (3.0 mmol) of 2,3,4,5,6-pentafluorostyrene were added to the glass reaction vessel. The reaction mixture was shielded from light and heated to 40°C with stirring for 24 hours. After heating, the reaction mixture was cooled to room temperature. Subsequently, the reaction mixture was added to 0.3 L of pure water. The reaction mixture was filtered by suction, and the resulting solid was washed with pure water and methanol. The washed solid was dried under reduced pressure to obtain 0.63 g of the crosslinking agent of formula (6) above. 【0071】 (Fluorine-containing compound (a) Synthesis of formula (10) n=1 above) A glass reaction vessel was loaded with 0.805 g (3.0 mmol) of 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 0.501 g (1.5 mmol) of decafluorobiphenyl, and 0.912 g (6.6 mmol) of potassium carbonate. The glass reaction vessel was then vacuumed and purged with nitrogen. Next, 10 mL of DMAc and 0.582 g (3.0 mmol) of 2,3,4,5,6-pentafluorostyrene were added to the glass reaction vessel. The reaction mixture was shielded from light and heated to 80°C with stirring for 15 hours. After heating, the reaction mixture was cooled to room temperature. Subsequently, the reaction mixture was added to 0.5 L of pure water. The reaction mixture was filtered by suction, and the resulting solid was washed with pure water and methanol. The washed solid was dried under reduced pressure to obtain 1.54 g of a fluorine-containing compound. The obtained fluorine-containing compound has the structural formula of formula (10) above (wherein n is 1). We confirmed that n=1 using nuclear magnetic resonance spectroscopy (X-Plus nuclear magnetic resonance spectrometer, Oxford Instruments). 【0072】 (Fluorine-containing compound (b) Synthesis of formula (10)n=0 above) A glass reaction vessel was loaded with 0.805 g (3.0 mmol) of 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z) and 0.912 g (6.6 mmol) of potassium carbonate. The glass vessel was then vacuumed and purged with nitrogen. Next, 10 mL of DMAc and 1.165 g (6.0 mmol) of 2,3,4,5,6-pentafluorostyrene were added to the glass reaction vessel. The reaction mixture was shielded from light and heated to 80°C with stirring for 15 hours. After heating, the reaction mixture was cooled to room temperature. Subsequently, the reaction mixture was added to 0.5 L of pure water. The reaction mixture was filtered by suction, and the resulting solid was washed with pure water and methanol. The washed solid was dried under reduced pressure to obtain 1.54 g of a fluorine-containing compound. The obtained fluorine-containing compound has the structural formula of formula (10) above, with a fluorine atom substitution rate of 100% for hydrogen atoms in the cyclic structure of constituent unit A, and a 0% proportion of fluorine atoms in constituent unit B. We confirmed that n=0 using nuclear magnetic resonance spectroscopy (X-Plus nuclear magnetic resonance spectrometer, Oxford Instruments). 【0073】 (Example 1) Approximately 10 g of a powder prepared by mixing the above crosslinking agent (a) and the above fluorine-containing compound (a) as a crosslinkable compound in a mass ratio of 25:75 was placed in a sample tube. 2% by mass of α,α'-di(t-butylperoxy)-diisopropylbenzene (Perbutyl® P, manufactured by NOF Corporation) was added relative to the weight of the mixed powder. Methyl ethyl ketone (MEK) was then added until the mixed powder reached 50% by mass. The compound was dissolved by shaking the sample tube by hand to obtain a mixed solution. The obtained mixed solution was transferred to a 300 mL round-bottom flask through a syringe filter, the solvent was removed using an evaporator, and the mixture was vacuum-dried at room temperature to 50°C to obtain a dried powder. 【0074】 (Example 2) A dried powder was obtained in the same manner as in Example 1, except that the mass ratio of the crosslinking agent to the crosslinkable compound was changed to 50:50. 【0075】 (Example 3) A dried powder was obtained in the same manner as in Example 1, except that the mass ratio of the crosslinking agent to the crosslinkable compound was changed to 75:25 and the concentration of the MEK solution in the mixed powder was changed to 45% by mass. 【0076】 (Example 4) A dried powder was obtained in the same manner as in Example 1, except that the mass ratio of the crosslinking agent to the crosslinkable compound was changed to 100:0 and the concentration of the MEK solution in the mixed powder was changed to 40% by mass. 【0077】 (Example 5) A dried powder was obtained in the same manner as in Example 1, except that the crosslinkable compound was the fluorine-containing compound (b) described above, the mass ratio of the crosslinking agent to the crosslinkable compound was changed to 38:62, and the concentration of the MEK solution of the mixed powder was changed to 35% by mass. 【0078】 (Comparative Example 1) A dried powder was obtained in the same manner as in Example 1, using only the fluorine-containing compound (a) without using a crosslinking agent. 【0079】 (Comparative Example 2) A dried powder was obtained in the same manner as in Example 1, except that only the fluorine-containing compound (b) was used without a crosslinking agent, and the concentration of the MEK solution of the mixed powder was changed to 25% by mass. 【0080】 (Comparative Example 3) Polyphenylene ether (PPE) resin As a control to demonstrate the performance of the cured product of the present invention, a dried powder was also obtained from polyphenylene ether (PPE) resin (NORYL SA9000, manufactured by SABIC), which is commonly used as a substrate material for high-frequency transmission, in the same manner as in Example 1. 【0081】 (Comparative Example 4) Perfluoroalkoxyalkanes (PFAs) As a control to demonstrate the performance of the cured product of the present invention, the following various measurements were performed using PFA (Teflon® PFA 440HP-J, manufactured by Mitsui Chemours Fluoroproducts Co., Ltd.). 【0082】 (Evaluation 1: Solvent solubility) Approximately 1 g of powder prepared by mixing the fluorine-containing compounds and crosslinking agents (hereinafter collectively referred to as "compounds") described in Examples 1-5 in the mass ratios shown in Table 1 was placed in a 20 mL sample tube. Methyl ethyl ketone (MEK) was added to achieve concentrations of 50, 45, 40, 35, 30, and 25% by mass, and the compound was dissolved at each concentration by shaking the sample tube by hand. The concentration at which the compound was completely dissolved by visual inspection and the solution became clear was considered soluble, and the concentration at which the compound remained visible was considered insoluble. 【0083】 (Test piece preparation method) The obtained mixed dried powder was placed in a 12mm x 45mm or 80mm square mold with aluminum foil positioned above and below, and vacuum was applied at room temperature using a manual hydraulic vacuum heating press (model MIC-4900) manufactured by Imoto Seisakusho. The vacuumed mold and mixed powder were heated to over 100°C, pressurized to 1.0MPa to 2.0MPa between 100°C and 150°C, and then heated to 240°C under pressure and held for 2 hours. After holding, the pressure was released, and the mold was cooled to obtain a sheet-like sample. For samples used for thermosetting, flame retardancy, glass transition temperature, and storage modulus measurements, the amount of resin and spacer was adjusted so that the film thickness was 1.4mm to 2.0mm, while for samples used for electrical property measurements, the film thickness was adjusted so that it was 0.2mm to 0.4mm. For the PFA sample, aluminum foil was placed in a mold preheated to 350°C, then the PFA was added and held at 350°C for 20 minutes to melt it. After that, a sheet-like sample was prepared by pressurizing it at 3.0 MPa for 1 minute. 【0084】 (Evaluation 2: Toughness of the cured material) The toughness of the cured material was evaluated based on the conditions during the formation of the sheet-like sample described above, and during the cutting of the sheet with a utility knife or similar tool for the preparation of test pieces for various measurements. The symbols (○, △, ×) in Table 1 represent the following evaluation criteria. ○: No cracks occurred during sample molding. Easy to cut out. △: Cracks may occur at the sheet edges during sample molding. The edges may slightly break during cutting. ×: Cracks occur throughout the entire sheet during sample molding. It is also prone to cracking during cutting. 【0085】 (Evaluation 3: Evaluation of thermosetting properties (gel fraction)) Samples were cut from the cured material obtained using the test piece preparation method described above, and their weight was measured. 5 g of methyl ethyl ketone (MEK) and the cured material were placed in a 9 mL sample tube, and the cured material was immersed in MEK for 24 hours. Afterward, the solvent was discarded, and the cured material was dried at 90°C for 3 hours using a hot plate. The mass after drying was measured and used as the mass of the dried cured material after MEK immersion. The gel fraction was calculated using the following formula. Gel fraction (%) = (Mass of dried and hardened material after MEK immersion / Mass of hardened material before MEK immersion) × 100 【0086】 (Rating 4: Electrical characteristics) Sheets approximately 20 mm square and 0.2 mm to 0.4 mm thick, prepared according to the test piece preparation method described above, were used to measure the dielectric constant and dielectric loss tangent using a Keysight dielectric constant measuring device (model: P5007A) under the cavity resonance method (TE mode), 28 GHz, and 25°C conditions. 【0087】 (Evaluation 5: Measurement of glass transition temperature (Tg) and storage modulus at 300°C) The 1.4mm to 2.0mm thick samples prepared using the test piece preparation method described above were cut into 12mm x 45mm squares to serve as test specimens. A dynamic viscoelasticity analyzer (DMA ARES-G2, TA Instruments) was used, with a film jig and a chuck distance of 25 mm to set the test specimen. The measurement was performed in Torsion mode with a frequency of 1.0 Hz and a strain of 0.1%, using the following temperature profile. (1) Hold at 25°C for 60 seconds, then heat from 25°C to 360°C at a rate of 5°C / min. (2) Maintain a temperature of 360°C for 60 seconds, then end the measurement. However, in the case of resins that have a melting point or a flow initiation point, the measurement range was limited to the point where the storage modulus G' value decreased sharply, and the measurement was stopped at that point. Table 1 shows the storage modulus G' at 300°C. 【0088】 By performing dynamic viscoelasticity measurements using the method described above, the storage modulus G' and the loss modulus G'' can be calculated. The loss tangent tanδ can then be calculated using the following formula based on the obtained values. tanδ = Loss modulus G'' / Storage modulus G' The maximum value of tanδ represents the point where molecular motion is at its maximum and is known as the glass transition temperature (Tg). In this measurement, a peak with a peak height of 0.002 or more, where the difference in tanδ at 25°C from the tanδ value measured at an arbitrary temperature is 0.002 or more, was defined as the Tg peak. If a peak exists, the temperature at which the peak is at its maximum was defined as Tg, and if no peak with a height of 0.002 or more was confirmed, it was classified as undetectable (ND). 【0089】 (Evaluation 6: Flame retardancy measurement) Samples with a thickness of 1.4 mm to 2.0 mm, prepared using the method described in the test piece preparation method, were cut into 10 mm square or 20 mm square pieces to be used as measurement samples. Flame retardancy was measured according to the method compliant with IEC60695-11-5 (JIS C6095-11-5). Specifically, the test piece was placed perpendicular to a flame (needle flame) using propane gas with a purity of 95% or higher as the heat source. The sample was held in contact with the center of the lower end of the flame for 10 seconds. The test was deemed to be suitable for the needle flame if it met one of the following conditions. The test was performed three times. a) If the specified mat does not ignite, and after the needle flame is removed, there is no flaming or red-hot combustion in the test specimen. b) The flaming or red-hot combustion of the test specimen and surrounding objects extinguishes in less than 30 seconds after the needle flame is removed, i.e., the burning time (tb) < 30 seconds, and furthermore, the surrounding objects do not burn completely and the specified mat does not ignite. 【0090】 (Evaluation 7: Measurement of linear thermal expansion coefficient) Samples with a thickness of 1.4 mm to 2.0 mm prepared using the method described in the test piece preparation method. Samples cut to approximately 2mm x 20mm were used for measurement, and the temperature was increased from -20°C to 330°C at a rate of 5°C / min using a ULVAC TM-7000 linear expansion meter. If the sample melted during the heating process, making measurement impossible, the measurement was stopped at that temperature. The linear expansion coefficient was calculated in the range of 25°C to 300°C using the following formula. Coefficient of linear expansion [ppm] = ((D 300 -D 25 ) / (300-25)) / L0×10 6 D 300 : Change in length from initial length at 300℃ (μm) D 25 : Change in length from initial length at 25℃ (μm) L0: Initial length (μm) 【0091】 [Table 1] 【0092】 As is clear from the results in Table 1, the cured products of the present invention (Examples 1-5) have a lower dielectric constant and superior electrical properties compared to cured products made of the same crosslinkable compound without a crosslinking agent (Comparative Examples 1-2). Furthermore, Examples 1 and 2 have higher glass transition temperatures than Comparative Examples 1-2, indicating superior heat resistance. Furthermore, Examples 1 and 2, which have a low crosslinking agent content, are soluble in MEK solution at all concentrations and exhibit particularly superior solvent solubility compared to Examples 3-5, which have a high crosslinking agent content, resulting in cured products with excellent handling properties. On the other hand, Examples 3-5 exhibit superior flame retardancy and electrical properties compared to Examples 1 and 2. Furthermore, the cured product of the present invention exhibits superior electrical properties, heat resistance, and solvent solubility compared to PPE resin and PFA (Comparative Examples 3-4), which are used as resin materials for high-speed communication and transmission. [Industrial applicability] 【0093】 The cured product of the present invention has excellent electrical properties (low dielectric constant, low dielectric loss tangent), flame retardancy, dimensional stability, solvent solubility of the material before curing, good handling properties, and a high glass transition temperature, making it suitable for use in electronic substrate materials, encapsulants, semiconductor packages, and coating materials. In particular, cured products with a high crosslinking agent content can be suitably used in electronic substrates, encapsulants, semiconductor packages, etc., where reduced transmission loss and high hardness at high temperatures are required. Cured products with a high crosslinking compound content can be suitably used in coatings, etc., where handling properties, high solvent solubility of the pre-cured material, and toughness are required.

Claims

[Claim 1] In a cured product comprising a crosslinking agent and, if necessary, a crosslinkable compound, The aforementioned crosslinking agent is a crosslinking agent having three or more groups shown in the following formula (1) in its molecule, -OR...(1) In the formula, R is a hydrocarbon group having at least one unsaturated bond and a cyclic structure, wherein all hydrogen atoms bonded to the cyclic structure are substituted with fluorine. A cured product characterized in that the crosslinkable compound is a crosslinkable compound having multiple unsaturated bonds. [Claim 2] The cured product according to claim 1, wherein formula (1) is a group represented by the following formula (2). 【Chemistry 1】 In the formula, X is a bridging group having an unsaturated bond. [Claim 3] The crosslinkable compound comprises a structural unit A having a cyclic structure of 3 to 12 members in its main skeleton, wherein 50% or more of the hydrogen atoms in the cyclic structure are substituted with fluorine atoms; a structural unit B having a benzene ring in its main skeleton, wherein 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, wherein the structural unit is C-B-(A-B) ｎ -C or C-A-(B-A) ｎ -C (where n = 0 to 1) A cured product according to claim 1 or 2, which is a fluorine-containing compound formed by bonding in the order of: [Claim 4] The cured product according to claim 1 or 2, wherein the crosslinking agent and the crosslinkable compound are contained in a mass ratio of 20:80 to 100:

0. [Claim 5] The cured product according to claim 1 or 2, wherein the crosslinking agent and the crosslinkable compound are contained in a mass ratio of 20:80 to 50:50, and used as a coating material. [Claim 6] A cured product according to claim 1 or 2, wherein the crosslinking agent and the crosslinkable compound are contained in a mass ratio of 50:50 to 80:20, and used in electronic substrates, encapsulants, and semiconductor packages.

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