Curable composition, dry film, cured product, and electronic component

Abstract

To provide a curable composition capable of yielding a cured product which contains a thermosetting polyphenylene ether soluble in various solvents and has excellent dielectric properties and self-extinguishing properties.SOLUTION: A curable composition according to an embodiment comprises: a polyphenylene ether comprising raw material phenols (A) which at least satisfy both the following condition 1 and the following condition 2, or raw material phenols comprising a mixture of phenols (B) which satisfy at least the condition 1 and do not satisfy the condition 2 and phenols (C) which do not satisfy the condition 1 and satisfy the condition 2; and silica. The raw material phenols (A) are phenols represented by formula (1), the raw material phenols (B) are phenols represented by formula (2), and the raw material phenols (C) are phenols represented by formula (3).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable composition, a dry film, a prepreg, a cured product, a laminate, and an electronic component, each containing a polyphenylene ether. [Background technology]

[0002] With the spread of high-capacity, high-speed communications, such as those typified by fifth-generation communications systems (5G), and millimeter-wave radar for automotive ADAS (Advanced Driver Assistance Systems), signals from communications equipment are becoming increasingly high-frequency.

[0003] However, when epoxy resins and other materials are used as wiring board materials, their relative permittivity (Dk) and dielectric loss tangent (Df) are not sufficiently low, so as the frequency increases, transmission loss due to dielectric loss increases, causing problems such as signal attenuation and heat generation. For this reason, polyphenylene ether, which has excellent low dielectric properties, has been used, but because polyphenylene ether is a thermoplastic resin, it has problems with heat resistance.

[0004] As a means for solving this problem, Non-Patent Document 1 proposes introducing an allyl group into the molecule of polyphenylene ether to form a thermosetting resin. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] J. Nunoshige, H. Akahoshi, Y. Shibasaki, M. Ueda, J. Polym. Sci. Part A: Polym. Chem. 2008, 46, 5278-5282. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] However, polyphenylene ether is soluble in only limited solvents, and the polyphenylene ether obtained by the method of Non-Patent Document 1 is soluble only in highly toxic solvents such as chloroform and toluene. This has led to problems such as difficulty in handling the resin varnish and in controlling solvent exposure during the process of forming a coating and curing it for use in wiring boards.

[0007] In light of the above-mentioned problems, the present inventors invented, in Japanese Patent Application No. 2018-134338, a polyphenylene ether that maintains low dielectric properties while also being soluble in various solvents (organic solvents other than highly toxic organic solvents, such as cyclohexanone). However, there is a demand for lower dielectric loss tangents to accommodate high frequencies and for improved self-extinguishing properties of electronic components.

[0008] Therefore, an object of the present invention is to provide a curable composition containing polyphenylene ether that is soluble in various solvents (organic solvents other than highly toxic organic solvents, for example, cyclohexanone), and that is suitable for obtaining a cured product that has a low dielectric loss tangent and self-extinguishing properties. [Means for solving the problem]

[0009] As a result of extensive research aimed at achieving the above object, the present inventors have completed the present invention by using a polyphenylene ether made from specific phenols as raw materials in combination with silica.

[0010] That is, the present invention provides a polyphenylene ether comprising raw material phenols (A) that satisfy at least both the following condition 1 and the following condition 2, or raw material phenols including a mixture of phenols (B) that satisfy at least the following condition 1 but do not satisfy the following condition 2, and phenols (C) that do not satisfy the following condition 1 but do satisfy the following condition 2; and silica. (Condition 1) Contains hydrogen atoms in the ortho and para positions (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0011] The present invention preferably relates to a polyphenylene ether comprising raw material phenols (A) that satisfy at least both the following condition 1 and the following condition 2, or raw material phenols including a mixture of phenols (B) that satisfy at least the following condition 1 but do not satisfy the following condition 2, and phenols (C) that do not satisfy the following condition 1 but do satisfy the following condition 2, and having a slope calculated in a conformation plot of less than 0.6; and silica. (Condition 1) Contains hydrogen atoms in the ortho and para positions (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0012] The curable composition may further contain a thermoplastic elastomer.

[0013] The curable composition may further contain a phosphorus-containing flame retardant.

[0014] The present invention also provides a dry film or prepreg obtained by applying the curable composition to a substrate.

[0015] The present invention also provides a cured product obtained by curing the curable composition.

[0016] The present invention also provides a laminate comprising the cured product.

[0017] The present invention also provides an electronic component comprising the cured product. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a curable composition containing polyphenylene ether that is soluble in various solvents, and that is suitable for obtaining a cured product that has a low dielectric loss tangent and self-extinguishing properties. DETAILED DESCRIPTION OF THE INVENTION

[0019] When the compounds described herein have isomers, all possible isomers can be used in the present invention unless otherwise specified.

[0020] In the present invention, unless otherwise specified, the term "unsaturated carbon bond" refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond).

[0021] In the present invention, when describing the raw material phenols, expressions such as "ortho position" and "para position" refer to the position of the phenolic hydroxyl group as the reference (ipso position) unless otherwise specified.

[0022] In the present invention, when simply expressed as "ortho position" or the like, it means "at least one of the ortho positions", etc. Therefore, unless a particular contradiction occurs, when simply expressed as "ortho position", it may be interpreted as indicating either one of the ortho positions, or it may be interpreted as indicating both ortho positions.

[0023] In the present invention, phenols that are used as raw materials for polyphenylene ether and can become structural units of polyphenylene ether are collectively referred to as "raw material phenols."

[0024] The curable compositions of the present invention contain certain polyphenylene ethers (PPEs) as described below.

[0025] The content of this predetermined polyphenylene ether is the remainder excluding other components described below, and although it depends on the content of these other components, it is typically 5 to 30 mass % based on the total solid content of the composition.

[0026] The solid content of the composition means the components constituting the composition other than the solvent (particularly the organic solvent), or the mass or volume thereof.

[0027] The curable composition (also simply referred to as the composition) of the present invention will be described below.

[0028] The composition of the present invention is characterized by containing silica and a polyphenylene ether made from raw material phenols, which include a phenol (A) that satisfies at least both the following condition 1 and the following condition 2, or a mixture of a phenol (B) that satisfies at least the following condition 1 but not the following condition 2, and a phenol (C) that does not satisfy the following condition 1 but satisfies the following condition 2:

[0029] Specifically, the polyphenylene ether is (Form 1) A raw material phenol containing, as an essential component, at least a phenol (A) that satisfies both the following condition 1 and the following condition 2, or (Mode 2) A raw material phenol containing, as essential components, at least a mixture of a phenol (B) that satisfies the following condition 1 but does not satisfy the following condition 2 and a phenol (C) that does not satisfy the following condition 1 but satisfies the following condition 2, It is obtained by oxidative polymerization of (Condition 1) Contains hydrogen atoms in the ortho and para positions (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0030] Here, phenols satisfying condition 1 {e.g., phenols (A) and (B)} have hydrogen atoms at the ortho-positions. Therefore, when oxidatively polymerized with phenols, ether bonds can be formed not only at the ipso-position and para-position but also at the ortho-position, making it possible to form a branched-chain structure.

[0031] When phenols that do not satisfy condition 1 (for example, phenols (C) and the following phenols (D)) are oxidatively polymerized, ether bonds are formed at the ipso and para positions, and the phenols are polymerized in a linear chain.

[0032] Furthermore, phenols satisfying condition 2 (e.g., phenols (A) and (C)) have at least a hydrocarbon group containing an unsaturated carbon bond. Therefore, polyphenylene ether synthesized using phenols satisfying condition 2 as raw materials has a hydrocarbon group containing an unsaturated carbon bond as a functional group, and thus has crosslinkability.

[0033] In this way, a part of the structure of polyphenylene ether is branched by benzene rings ether-bonded at least at three positions, i.e., the ipso, ortho, and para positions. Polyphenylene ether is, for example, a polyphenylene ether having a branched structure in its skeleton as represented by at least formula (5), and is considered to be a compound having a hydrocarbon group containing at least one unsaturated carbon bond as a functional group.

[0034] [ka]

[0035] In formula (5), R a ~R k is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 1 to 12 carbon atoms), provided that R a ~R k At least one of the groups is a hydrocarbon group having an unsaturated carbon bond.

[0036] Next, the above-mentioned Form 1 may be a form further containing phenol (B) and / or phenol (C) as raw material phenols, and the above-mentioned Form 2 may be a form further containing phenol (A) as raw material phenols.

[0037] The polyphenylene ether is preferably in the above-mentioned form 2 or in the above-mentioned form 1 containing a phenol (B) and / or a phenol (C) as an additional essential component.

[0038] Furthermore, the raw material phenols may contain other phenols within the range that does not impair the effects of the present invention.

[0039] Examples of other phenols include phenols (D) which have a hydrogen atom at the para position, no hydrogen atom at the ortho position, and no functional group containing an unsaturated carbon bond.

[0040] In both of the above-mentioned Form 1 and Form 2, it is preferable to further contain a phenol (D) as a raw material phenol in order to increase the molecular weight of the polyphenylene ether.

[0041] In the above-mentioned embodiment 2, the polyphenylene ether is most preferably in a form further containing a phenol (D) as a raw material phenol.

[0042] Furthermore, in the above-mentioned embodiment 2, from an industrial and economical viewpoint, it is preferable that the phenol (B) is at least one of o-cresol, 2-phenylphenol, 2-dodecylphenol, and phenol, and the phenol (C) is 2-allyl-6-methylphenol.

[0043] The phenols (A) to (D) will be described in more detail below.

[0044] As described above, the phenol (A) is a phenol that satisfies both the condition 1 and the condition 2, i.e., a phenol that has hydrogen atoms at the ortho- and para-positions and has a functional group containing an unsaturated carbon bond, and is preferably a phenol (a) represented by the following formula (1):

[0045] [ka]

[0046] In formula (1), R1 to R3 are hydrogen atoms or hydrocarbon groups having 1 to 15 carbon atoms. However, at least one of R1 to R3 is a hydrocarbon group having an unsaturated carbon bond. From the viewpoint of facilitating polymerization by oxidative polymerization, the hydrocarbon group preferably has 1 to 12 carbon atoms.

[0047] Examples of the phenol (a) represented by formula (1) include o-vinylphenol, m-vinylphenol, o-allylphenol, m-allylphenol, 3-vinyl-6-methylphenol, 3-vinyl-6-ethylphenol, 3-vinyl-5-methylphenol, 3-vinyl-5-ethylphenol, 3-allyl-6-methylphenol, 3-allyl-6-ethylphenol, 3-allyl-5-methylphenol, 3-allyl-5-ethylphenol, etc. The phenol represented by formula (1) may be used alone or in combination of two or more.

[0048] As described above, the phenol (B) is a phenol that satisfies the condition 1 but does not satisfy the condition 2, i.e., a phenol that has hydrogen atoms at the ortho- and para-positions and does not have a functional group containing an unsaturated carbon bond, and is preferably a phenol (b) represented by the following formula (2):

[0049] [ka]

[0050] In formula (2), R4 to R6 are hydrogen atoms or hydrocarbon groups having 1 to 15 carbon atoms. However, R4 to R6 do not have an unsaturated carbon bond. From the viewpoint of facilitating polymerization by oxidative polymerization, the hydrocarbon groups preferably have 1 to 12 carbon atoms.

[0051] Examples of the phenol (b) represented by formula (2) include phenol, o-cresol, m-cresol, o-ethylphenol, m-ethylphenol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, o-tert-butylphenol, m-tert-butylphenol, o-phenylphenol, m-phenylphenol, 2-dodecylphenol, etc. The phenols represented by formula (2) may be used alone or in combination of two or more.

[0052] As described above, the phenol (C) is a phenol that does not satisfy condition 1 but satisfies condition 2, i.e., a phenol that has a hydrogen atom at the para position, does not have a hydrogen atom at the ortho position, and has a functional group containing an unsaturated carbon bond, and is preferably a phenol (c) represented by the following formula (3):

[0053] [ka]

[0054] In formula (3), R7 and R 10 is a hydrocarbon group having 1 to 15 carbon atoms, and R8 and R9 are hydrogen atoms or hydrocarbon groups having 1 to 15 carbon atoms. 10 At least one of the above is a hydrocarbon group having an unsaturated carbon bond. From the viewpoint of facilitating polymerization by oxidative polymerization, the hydrocarbon group preferably has 1 to 12 carbon atoms.

[0055] Examples of the phenol (c) represented by formula (3) include 2-allyl-6-methylphenol, 2-allyl-6-ethylphenol, 2-allyl-6-phenylphenol, 2-allyl-6-styrylphenol, 2,6-divinylphenol, 2,6-diallylphenol, 2,6-diisopropenylphenol, 2,6-dibutenylphenol, 2,6-diisobutenylphenol, 2,6-diisopentenylphenol, 2-methyl-6-styrylphenol, 2-vinyl-6-methylphenol, 2-vinyl-6-ethylphenol, etc. The phenol represented by formula (3) may be used alone or in combination of two or more.

[0056] As described above, the phenol (D) is a phenol having a hydrogen atom at the para position, no hydrogen atom at the ortho position, and no functional group containing an unsaturated carbon bond, and is preferably a phenol (d) represented by the following formula (4):

[0057] [ka]

[0058] In formula (4), R 11 and R 14 is a hydrocarbon group having 1 to 15 carbon atoms and no unsaturated carbon bond, and R 12 and R 13 is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms and no unsaturated carbon bond. From the viewpoint of facilitating polymerization by oxidative polymerization, the hydrocarbon group preferably has 1 to 12 carbon atoms.

[0059] Examples of the phenol (d) represented by formula (4) include 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-methyl-6-ethylphenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-n-butylphenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2,6-ditolylphenol, etc. The phenol represented by formula (4) may be used alone or in combination of two or more.

[0060] In the present invention, examples of hydrocarbon groups include alkyl groups, cycloalkyl groups, aryl groups, alkenyl groups, and alkynyl groups, with alkyl groups, aryl groups, and alkenyl groups being preferred. Examples of hydrocarbon groups having an unsaturated carbon bond include alkenyl groups and alkynyl groups. These hydrocarbon groups may be linear or branched.

[0061] Furthermore, other phenols may include phenols that do not have a hydrogen atom at the para position.

[0062] The ratio of the phenols satisfying condition 1 to the total amount of the raw material phenols is preferably 1 to 50 mol %.

[0063] The proportion of the phenols satisfying condition 2 relative to the total amount of the raw material phenols is preferably 0.5 to 99 mol %, more preferably 1 to 99 mol %.

[0064] The polyphenylene ether obtained by oxidatively polymerizing the raw material phenols described above by a known, commonly used method preferably has a number-average molecular weight of 2,000 to 30,000. It is more preferably 5,000 to 30,000, even more preferably 8,000 to 30,000, and particularly preferably 8,000 to 25,000. Furthermore, the polyphenylene ether preferably has a polydispersity index (PDI: weight-average molecular weight / number-average molecular weight) of 1.5 to 20. The number-average molecular weight and weight-average molecular weight were measured by gel permeation chromatography (GPC) and converted using a calibration curve prepared using standard polystyrene.

[0065] Here, the branched structure (degree of branching) of polyphenylene ether can be confirmed based on the following analytical procedure.

[0066] <Analysis Procedure> After preparing polyphenylene ether chloroform solutions at 0.1, 0.15, 0.2, and 0.25 mg / mL intervals, a graph of refractive index difference versus concentration is created while the solution is pumped at 0.5 mL / min, and the refractive index increment dn / dc is calculated from the slope. Next, the absolute molecular weight is measured under the following instrument operating conditions. Using the chromatograms from the RI detector and MALS detector as a reference, a regression line is calculated using the least squares method from a logarithmic graph (conformation plot) of molecular weight versus radius of gyration, and its slope is calculated.

[0067] <Measurement conditions> Device name: HLC8320GPC Mobile phase: Chloroform Column: TOSOH TSKguard column HHR-H +TSKgelGMHHR-H (2 tubes) +TSKgelG2500HHR Flow rate: 0.6mL / min. Detector: DAWN HELEOS (MALS detector) +Optilab rEX (RI detector, wavelength 254 nm) Sample concentration: 0.5 mg / mL Sample solvent: Same as mobile phase. Dissolve 5 mg of sample in 10 mL of mobile phase. Injection volume: 200μL Filter: 0.45 μm STD Reagent: Standard Polystyrene Mw 37,900 STD concentration: 1.5mg / mL STD solvent: Same as mobile phase. Dissolve 15 mg of sample in 10 mL of mobile phase. Analysis time: 100min

[0068] For resins with the same absolute molecular weight, the more branching of the polymer chain progresses, the smaller the distance from the center of gravity to each segment (radius of gyration). Therefore, the slope of the logarithmic plot of absolute molecular weight and radius of gyration obtained by GPC-MALS indicates the degree of branching, with a smaller slope indicating a greater degree of branching. In the present invention, a smaller slope calculated from the above conformation plot indicates a greater degree of branching of the polyphenylene ether, and a larger slope indicates a lesser degree of branching of the polyphenylene ether.

[0069] In the polyphenylene ether, the gradient is, for example, less than 0.6, and is preferably 0.55 or less, 0.50 or less, 0.45 or less, or 0.40 or less. When the gradient is within this range, the polyphenylene ether is considered to have sufficient branching. The lower limit of the gradient is not particularly limited, but is, for example, 0.05 or more, 0.10 or more, 0.15 or more, or 0.20 or more.

[0070] The slope of the conformation plot can be adjusted by changing the temperature, catalyst amount, stirring speed, reaction time, oxygen supply amount, and solvent amount during synthesis of polyphenylene ether. More specifically, increasing the temperature, increasing the catalyst amount, increasing the stirring speed, extending the reaction time, increasing the oxygen supply amount, and / or decreasing the solvent amount tends to decrease the slope of the conformation plot (making the polyphenylene ether more likely to branch).

[0071] 1 g of polyphenylene ether is preferably soluble in 100 g of cyclohexanone at 25°C (more preferably, 100 g of cyclohexanone, DMF, and PMA). The solubility of 1 g of polyphenylene ether in 100 g of a solvent (e.g., cyclohexanone) means that when 1 g of polyphenylene ether is mixed with 100 g of the solvent, no turbidity or precipitation is visually observed. More preferably, the polyphenylene ether of the present invention is soluble in an amount of 1 g or more in 100 g of cyclohexanone at 25°C.

[0072] Such polyphenylene ether can be produced by applying a conventionally known method for synthesizing polyphenylene ether (polymerization conditions, the presence or absence of a catalyst, the type of catalyst, etc.), except for using a specific raw material phenol.

[0073] The curable composition of the present invention contains silica. By blending silica into the composition, it is possible to achieve high levels of self-extinguishing properties and low dielectric loss tangent of the cured product.

[0074] The average particle size of the silica is preferably 0.02 to 10 μm, more preferably 0.02 to 3 μm. Here, the average particle size can be determined as the median diameter (d50, volume basis) based on cumulative distribution from particle size distribution measured by a laser diffraction / scattering method using a commercially available laser diffraction / scattering particle size distribution analyzer.

[0075] It is also possible to use silica with different average particle sizes in combination. From the viewpoint of achieving a high silica loading, for example, silica with an average particle size of 1 μm or more may be used in combination with fine silica with an average particle size of less than 1 μm, on the order of nanometers.

[0076] The silica may be surface-treated with a coupling agent. Treating the surface with a silane coupling agent can improve dispersibility with polyphenylene ether and affinity with organic solvents.

[0077] Examples of silane coupling agents that can be used include epoxy silane coupling agents, mercapto silane coupling agents, and vinyl silane coupling agents. Examples of epoxy silane coupling agents that can be used include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane. Examples of mercapto silane coupling agents that can be used include γ-mercaptopropyltriethoxysilane. Examples of vinyl silane coupling agents that can be used include vinyltriethoxysilane.

[0078] The amount of the silane coupling agent used may be, for example, 0.1 to 5 parts by mass, or 0.5 to 3 parts by mass, per 100 parts by mass of silica.

[0079] The amount of silica may be 200 to 600 parts by mass relative to 100 parts by mass of polyphenylene ether, in other words, the amount of silica may be 40 to 80% by mass based on the total solid content of the composition.

[0080] The curable composition of the present invention preferably contains a thermoplastic elastomer. By blending a thermoplastic elastomer into the composition, the tensile properties of the cured product can be improved. The cured product of the polyphenyl ether used in the present invention has a low elongation at break and tends to be brittle, but by using a thermoplastic elastomer in combination, the elongation at break can be improved while maintaining the dielectric properties.

[0081] Examples of thermoplastic elastomers include styrene elastomers, olefin elastomers, urethane elastomers, polyester elastomers, polyamide elastomers, acrylic elastomers, and silicone elastomers. Styrene elastomers are particularly preferred because of their compatibility with polyphenylene ether and high dielectric properties.

[0082] Examples of styrene-based elastomers include styrene-butadiene copolymers such as styrene-butadiene-styrene block copolymers, styrene-isoprene copolymers such as styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, styrene-ethylene-propylene-styrene block copolymers, etc. In addition, hydrogenated products of these copolymers can be used.

[0083] The content of the styrene block in the styrene elastomer is preferably 20 to 70 mol %.

[0084] Here, raw material monomers for styrene elastomers include not only styrene but also styrene derivatives such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, and 4-cyclohexylstyrene.

[0085] The weight-average molecular weight of the thermoplastic elastomer may be 1,000 to 300,000 or 2,000 to 150,000. When the weight-average molecular weight is equal to or greater than the lower limit, the elastomer exhibits excellent low thermal expansion, while when the weight-average molecular weight is equal to or less than the upper limit, the elastomer exhibits excellent compatibility with other components. The weight-average molecular weight of the thermoplastic elastomer is measured by GPC and converted using a calibration curve prepared using standard polystyrene.

[0086] The amount of thermoplastic elastomer may be 30 to 100 parts by mass per 100 parts by mass of polyphenylene ether. In other words, the amount of thermoplastic elastomer may be 3 to 20% by mass based on the total solid content of the composition. When the amount is within the above range, a good balance of good curability, moldability, and chemical resistance can be achieved.

[0087] The curable composition preferably contains a phosphorus-containing flame retardant. By incorporating a phosphorus-containing flame retardant into the composition, the self-extinguishing properties of the cured product obtained by curing the composition can be improved.

[0088] Examples of the phosphorus-containing flame retardant include phosphoric acid or its ester, phosphorous acid or its ester, and condensates thereof.

[0089] From the viewpoint of high silica loading, it is preferable that the phosphorus-containing flame retardant is compatible with polyphenylene ether. However, there is a risk that the phosphorus-containing flame retardant may bleed out.

[0090] In a preferred embodiment that reduces the risk of bleeding out, the phosphorus-containing flame retardant has one or more unsaturated carbon bonds in its molecular structure. When the composition is cured, the phosphorus-containing flame retardant having an unsaturated carbon bond can react with the unsaturated carbon bond of the polyphenylene ether to form an integrated compound. As a result, the risk of bleeding out of the phosphorus-containing flame retardant is reduced.

[0091] In a particularly preferred embodiment of the present invention, the phosphorus-containing flame retardant has a plurality of unsaturated carbon bonds in its molecular structure. Such phosphorus-containing flame retardants having a plurality of unsaturated carbon bonds can also function as a crosslinking curing agent, which will be described later. From the viewpoint of contributing to crosslinking of the polyphenylene ether of the present invention, the phosphorus-containing flame retardant having a plurality of unsaturated carbon bonds can also be expressed as a phosphorus-containing crosslinking curing agent or a phosphorus-containing crosslinking coagent.

[0092] The phosphoric acid or its ester is a compound represented by the following formula (6).

[0093] [ka]

[0094] In formula (6), R 61 ~R 63are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 1 to 12). The hydrocarbon group may have an unsaturated carbon bond. The hydrocarbon group may also contain one or more heteroatoms such as oxygen, nitrogen, or sulfur. However, since the inclusion of these heteroatoms increases polarity and may adversely affect dielectric properties, it is preferable that the hydrocarbon group does not contain heteroatoms. Typical examples of such hydrocarbon groups include methyl, ethyl, octyl, phenyl, cresyl, butoxyethyl, vinyl, allyl, acryloyl, and methacryloyl groups.

[0095] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, tri(2-ethylhexyl)phosphate, diisopropylphenyl phosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, trinaphthyl phosphate, bisphenol A bisphosphate, hydroquinone bisphosphate, resorcinol bisphosphate, resorcinol-diphenyl phosphate, and trioxybenzene triphosphate.

[0096] Examples of the phosphate ester having an unsaturated carbon bond in the molecular structure include trivinyl phosphate, triallyl phosphate, triacryloyl phosphate, trimethacryloyl phosphate, trisacryloyloxyethyl phosphate, and trismethacryloyloxyethyl phosphate.

[0097] The phosphorous acid or its ester is a compound represented by the following formula (7).

[0098] [ka]

[0099] In formula (7), R 71 ~R 73 is R in Eq. (6). 61 ~R 63 The explanation in paragraph 1 applies.

[0100] Examples of phosphite esters include trimethyl phosphite, triethyl phosphite, tributyl phosphite, trioctyl phosphite, tributoxyethyl phosphite, triphenyl phosphite, tricresyl phosphite, cresyl diphenyl phosphite, octyl diphenyl phosphite, tri(2-ethylhexyl)phosphite, diisopropylphenyl phosphite, trixylenyl phosphite, tris(isopropylphenyl)phosphite, trinaphthyl phosphite, bisphenol A bisphosphite, hydroquinone bisphosphite, resorcinol bisphosphite, resorcinol-diphenyl phosphite, and trioxybenzene triphosphite.

[0101] Examples of the phosphite ester having an unsaturated carbon bond in the molecular structure include trivinyl phosphite, triallyl phosphite, triacryloyl phosphite, and trimethacryloyl phosphite.

[0102] The content of the phosphorus-containing flame retardant may be 1 to 5 mass % in terms of phosphorus based on the total solid content of the composition. Within this range, the cured product obtained by curing the composition can achieve high levels of self-extinguishing property, heat resistance, and dielectric properties in a well-balanced manner.

[0103] The curable composition may contain a peroxide. The curable composition may also contain a crosslinking curing agent. The curable composition may also contain other components within a range that does not impair the effects of the present invention.

[0104] The peroxide has the effect of opening the unsaturated carbon bonds contained in the polyphenylene ether of the present invention and accelerating the crosslinking reaction.

[0105] Peroxides include methyl ethyl ketone peroxide, methyl acetoacetate peroxide, acetylacetonperoxide, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, 2,5-di Examples of peroxides include methyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-butene, acetyl peroxide, octanoyl peroxide, lauroyl peroxide, benzoyl peroxide, m-toluyl peroxide, diisopropyl peroxydicarbonate, t-butylene peroxybenzoate, di-t-butyl peroxide, t-butylperoxyisopropyl monocarbonate, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, etc. One type of peroxide may be used alone, or two or more types may be used.

[0106] Among these, from the viewpoints of ease of handling and reactivity, peroxides having a one-minute half-life temperature of 130° C. to 180° C. are desirable. Such peroxides have a relatively high reaction initiation temperature, and therefore do not readily promote curing when curing is not required, such as during drying, and do not impair the storage stability of the polyphenylene ether resin composition. In addition, due to their low volatility, they do not volatilize during drying or storage, and therefore have good stability.

[0107] The amount of peroxide added is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, and particularly preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the solid content of the curable composition. By keeping the total amount of peroxide within this range, it is possible to prevent deterioration of the film quality when formed into a coating film while ensuring sufficient effect at low temperatures.

[0108] If necessary, the composition may contain an azo compound such as azobisisobutyronitrile or azobisisovaleronitrile, or a radical initiator such as dicumyl or 2,3-diphenylbutane.

[0109] The crosslinking curing agent is a compound that three-dimensionally crosslinks polyphenylene ether. Note that a crosslinking curing agent that is also a phosphorus-containing compound (phosphorus-containing flame retardant) is specifically referred to as a phosphorus-containing crosslinking curing agent. The crosslinking curing agent may also specifically refer to a crosslinking curing agent that does not contain phosphorus (phosphorus-free crosslinking curing agent).

[0110] As the crosslinking curing agent, one with good compatibility with polyphenylene ether is used, and examples thereof include polyfunctional vinyl compounds such as divinylbenzene, divinylnaphthalene, and divinylbiphenyl; vinylbenzyl ether compounds synthesized by the reaction of phenol with vinylbenzyl chloride; allyl ether compounds synthesized by the reaction of styrene monomer, phenol with allyl chloride; and trialkenyl isocyanurate. As the crosslinking curing agent, trialkenyl isocyanurate, which has particularly good compatibility with polyphenylene ether, is preferred, and specifically, triallyl isocyanurate (hereinafter referred to as TAIC®) and triallyl cyanurate (hereinafter referred to as TAC) are particularly preferred. These exhibit low dielectric properties and can enhance heat resistance. TAIC® is particularly preferred due to its excellent compatibility with polyphenylene ether.

[0111] Furthermore, as the crosslinking curing agent, a (meth)acrylate compound (a methacrylate compound and an acrylate compound) may be used. In particular, it is preferable to use a tri- to pentafunctional (meth)acrylate compound. As the tri- to pentafunctional methacrylate compound, trimethylolpropane trimethacrylate or the like may be used, while as the tri- to pentafunctional acrylate compound, trimethylolpropane triacrylate or the like may be used. The use of these crosslinking agents can improve heat resistance. Only one type of crosslinking curing agent may be used, or two or more types may be used.

[0112] The polyphenylene ether of the present invention has a branched structure, which improves its solubility in various solvents, but it may be difficult to improve its dielectric properties. However, since it contains a hydrocarbon group having an unsaturated carbon bond, it can be cured with a cross-linking curing agent to give a cured product with excellent dielectric properties.

[0113] The blending ratio of polyphenylene ether to crosslinking curing agent is preferably 20:80 to 90:10 in parts by mass, and more preferably 30:70 to 90:10. When the blending amount of polyphenylene ether is 20 parts by mass or more, appropriate toughness is obtained, and when it is 90 parts by mass or less, excellent heat resistance is obtained.

[0114] The curable composition is usually provided or used in a state in which the polyphenylene ether is dissolved in a solvent. The polyphenylene ether of the present invention has higher solubility in solvents than conventional polyphenylene ethers, and therefore a wider range of solvents can be selected depending on the application of the curable composition.

[0115] Examples of solvents that can be used in the curable composition of the present invention include conventionally usable solvents such as chloroform, methylene chloride, and toluene, as well as relatively safe solvents such as N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), cyclohexanone, propylene glycol monomethyl ether acetate (PMA), diethylene glycol monoethyl ether acetate (CA), methyl ethyl ketone, and ethyl acetate. Only one type of solvent may be used, or two or more types may be used.

[0116] The content of the solvent in the curable composition is not particularly limited and can be adjusted appropriately depending on the application of the curable composition.

[0117] The curable composition may contain known and commonly used raw materials such as resins other than the polyphenylene ether of the present invention and other additives, within the range that does not impair the effects of the present invention. For example, the curable composition may contain inorganic fillers other than silica and flame retardants that do not contain phosphorus atoms.

[0118] Such a curable composition can be obtained by mixing and dispersing the respective raw materials. The composition of the present invention contains polyphenylene ether that is soluble in various solvents, and is suitable for obtaining a cured product that has a low dielectric loss tangent and self-extinguishing properties, and therefore can be used in a variety of applications.

[0119] <Cured product> The cured product can be obtained by curing the above-described curable composition.

[0120] The method for obtaining a cured product from the curable composition is not particularly limited and can be appropriately changed depending on the composition of the curable composition. For example, after carrying out the step of applying the curable composition to a substrate (e.g., application using an applicator, etc.) as described above, a drying step of drying the curable composition may be carried out as needed, and then a thermal curing step of thermally crosslinking the polyphenylene ether by heating (e.g., heating using an inert gas oven, hot plate, vacuum oven, vacuum press, etc.) may be carried out. The conditions for carrying out each step (e.g., coating thickness, drying temperature and time, heating temperature and time, etc.) may be appropriately changed depending on the composition and application of the curable composition, etc.

[0121] <Dry film, prepreg> The dry film or prepreg of the present invention is obtained by applying the above-mentioned curable composition to a substrate.

[0122] Examples of the substrate include metal foil such as copper foil, films such as polyimide film, polyester film, and polyethylene naphthalate (PEN) film, and fibers such as glass cloth and aramid fiber.

[0123] The dry film can be obtained, for example, by applying a curable composition onto a polyethylene terephthalate film, drying the composition, and laminating a polypropylene film thereon as needed.

[0124] The prepreg can be obtained, for example, by impregnating a glass cloth with a curable composition and drying the impregnated glass cloth.

[0125] <Laminate> In the present invention, a laminate can be produced using the above-mentioned prepreg.

[0126] More specifically, one or more prepregs of the present invention are stacked, and then a metal foil such as copper foil is placed on either one or both of the upper and lower surfaces of the prepreg, and the resulting laminate is then heated and pressurized to produce a laminate having metal foil on both surfaces or one surface of the laminate.

[0127] <Electronic components> Such a cured product has excellent dielectric properties and heat resistance, and can be used for electronic parts, etc.

[0128] The electronic component having the cured product is not particularly limited, but preferred examples include millimeter-wave radar for high-capacity, high-speed communications such as the fifth-generation communication system (5G) and automotive ADAS (Advanced Driver Assistance Systems). [Example]

[0129] The curable composition of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these in any way.

[0130] <<<Preparation of composition>>> The procedures for preparing each composition (compositions of Examples 1 to 6, Reference Examples 1 to 3, and Comparative Examples 1 and 2) will be described below.

[0131] <Description of Synthesis Example A of Polyphenylene Ether for Examples and Reference Examples> 5.3 g of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 5.7 mL of tetramethylethylenediamine (TMEDA) were added to a 3 L two-necked flask and thoroughly dissolved. Oxygen was supplied at 10 mL / min. The raw phenols, 10.1 g of o-cresol, 13.8 g of 2-allyl-6-methylphenol, and 91.1 g of 2,6-dimethylphenol, were dissolved in 1.5 L of toluene to prepare a raw material solution. This raw material solution was added dropwise to the flask and reacted at 40 °C for 6 hours while stirring at 600 rpm. After the reaction was complete, the mixture was reprecipitated in a mixture of 20 L of methanol and 22 mL of concentrated hydrochloric acid, filtered, and dried at 80 °C for 24 hours to obtain a terpolymer PPE resin.

[0132] The PPE resin of Synthesis Example A was soluble in various organic solvents such as cyclohexanone, N,N-dimethylformamide (DMF), and propylene glycol monomethyl ether acetate (PMA). The number-average molecular weight of the PPE resin of Synthesis Example A was 12,700, and the weight-average molecular weight was 77,470.

[0133] The slope of the conformation plot of Synthesis Example A was 0.32.

[0134] <Description of Synthesis Example B of Comparative Polyphenylene Ether> A di-copolymer PPE resin was obtained using the same synthesis method as for the ter-copolymer PPE resin, except that a raw material solution prepared by dissolving 13.8 g of the raw material phenols 2-allyl-6-methylphenol and 103 g of 2,6-dimethylphenol in 0.38 L of toluene was used.

[0135] The PPE resin of Synthesis Example B was insoluble in cyclohexanone but soluble in chloroform. The number-average molecular weight of the PPE resin of Synthesis Example B was 19,000 and the weight-average molecular weight was 39,900.

[0136] The slope of the conformation plot of Synthesis Example B was 0.61.

[0137] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of each PPE resin were determined by gel permeation chromatography (GPC) using a Shodex K-805L column at 40°C, a flow rate of 1 mL / min, chloroform as the eluent, and polystyrene as the standard.

[0138] <Preparation of the composition of Example 1> To 15.9 parts by mass of the PPE resin from Synthesis Example A, 80 parts by mass of cyclohexanone was added as a solvent, and the mixture was mixed and stirred at 40°C for 30 minutes to completely dissolve the resin. To the resulting PPE resin solution, 15.9 parts by mass of TAIC (manufactured by Mitsubishi Chemical Corporation) as a crosslinking curing agent and 60.2 parts by mass of spherical silica (manufactured by Admatechs Co., Ltd., product name "SC2500-SVJ") were added, mixed, and then dispersed using a three-roll mill. Finally, 0.6 parts by mass of α,α'-bis(t-butylperoxy-m-isopropyl)benzene (manufactured by Nippon Oil & Fats Co., Ltd., product name "Perbutyl P") as a curing catalyst was added, mixed, and then dispersed using a three-roll mill. In this way, a varnish of the resin composition of Example 1 was obtained.

[0139] <Preparation of the composition of Example 2> A varnish of the resin composition of Example 2 was obtained in the same manner as in Example 1, except that 7.5 parts by mass of a hydrogenated styrene-based thermoplastic elastomer was further added.

[0140] <Preparation of Compositions of Examples 3 to 5> Varnishes of the resin compositions of Examples 3 to 5 were obtained in the same manner as in Example 2, except that TAIC was changed to triallyl phosphite, trisacryloyloxyethyl phosphate, and trismethacrylolyloxyethyl phosphate, respectively.

[0141] <Preparation of the composition of Example 6> A varnish of the resin composition of Example 6 was obtained in the same manner as in Example 5, except that the silica was changed to one that had not been surface-treated.

[0142] <Preparation of Compositions of Reference Examples 1 and 2> Varnishes of the resin compositions of Reference Examples 1 and 2 were obtained in the same manner as in Examples 1 and 2, respectively, except that silica was not added.

[0143] <Preparation of the composition of Reference Example 3> A varnish of the resin composition of Reference Example 3 was obtained in the same manner as in Example 2, except that silica was changed to 20 parts by mass of alumina.

[0144] <Preparation of Compositions of Comparative Examples 1 and 2> Varnishes of the resin compositions of Comparative Examples 1 and 2 were obtained in the same manner as in Examples 2 and 3, except that the PPE resin of Synthesis Example B was used instead of the PPE resin according to the present invention.

[0145] The composition and amount of each composition are shown in Table 3. The numbers are in parts by mass.

[0146] The varnish of the obtained resin composition was applied to the shine side of 18 μm thick copper foil using an applicator so that the thickness of the cured product was 50 μm. Next, it was dried at 90 ° C for 30 minutes in a hot air circulation drying oven. After that, it was completely filled with nitrogen using an inert oven and heated to 200 ° C, and then cured for 60 minutes. The copper foil was then etched to obtain a cured product (cured film).

[0147] <<Evaluation>> Each composition and the cured film obtained therefrom were evaluated for the following items by the following evaluation methods.

[0148] <Film forming properties> The varnishes that gave a cured film were evaluated as "◯", and the varnishes that did not give a cured film were evaluated as "X". Naturally, the varnishes that did not give a cured film could not be evaluated for the cured film described below.

[0149] <Dielectric properties> The dielectric properties, ie, the relative permittivity Dk and the dielectric loss tangent Df, were measured according to the following method. The cured film was cut into a length of 80 mm, width of 45 mm, and thickness of 50 μm and used as a test piece for measurement using the SPDR (Split Post Dielectric Resonator) resonator method. The measuring equipment used was a Keysight Technologies, LLC, Vector Network Analyzer E5071C, an SPDR resonator, and a calculation program manufactured by QWED. The conditions were a frequency of 10 GHz and a measurement temperature of 25°C.

[0150] (Evaluation criteria) The dielectric properties were evaluated as follows. Those with a Dk of less than 3.0 were evaluated as "A", those with a Dk of less than 3.5 as "O", and those with a Dk of 3.5 or more as "X". Those with Df less than 0.003 were evaluated as "A", those with Df of 0.003 or more but less than 0.01 were evaluated as "Good", and those with Df of 0.01 or more were evaluated as "Poor".

[0151] <Self-extinguishing property> The cured film was cut into a length of 200 mm, width of 15 mm, and thickness of 50 μm, and the flame of a gas burner was applied to the bottom of the test piece for 5 seconds to measure the burning duration. Specifically, five test pieces were tested twice each, and the average burning duration of a total of 10 tests was calculated.

[0152] (Evaluation criteria) The average burning duration was marked as "◎" when it was less than 20 seconds, "〇" when it was 20 seconds or more but less than 30 seconds, and "×" when it was 30 seconds or more.

[0153] <Tensile properties> The cured film was cut into a piece 8 cm long, 0.5 cm wide and 50 μm thick, and the tensile elongation at break was measured under the following conditions. [Measurement conditions] Testing machine: Tensile testing machine EZ-SX (Shimadzu Corporation) Chuck distance: 50mm Test speed: 1mm / min Elongation calculation: (Tensile movement amount / Distance between chucks) x 100

[0154] (Evaluation criteria) Those with a tensile elongation at break of 1.0% or more and less than 2.0% were evaluated as "Good", and those with a tensile elongation at break of 2.0% or more were evaluated as "Excellent".

[0155] [Table 1]

Claims

1. Polyphenylene ether, Contains silica, The polyphenylene ether is obtained from raw material phenols containing a phenol (A) that satisfies both the following condition 1 and the following condition 2, or is obtained from raw material phenols containing a mixture of a phenol (B) that satisfies the following condition 1 but does not satisfy the following condition 2, and a phenol (C) that does not satisfy the following condition 1 but satisfies the following condition 2, The phenol (A) is a phenol represented by the following formula (1): The phenol (B) is a phenol represented by the following formula (2): The phenol (C) is a phenol represented by the following formula (3): The curable composition is characterized in that the amount of the silica blended is 200 parts by mass or more per 100 parts by mass of the polyphenylene ether. (Condition 1) Contains hydrogen atoms in the ortho and para positions (Condition 2) A hydrogen atom is present at the para position, and the alkenyl group has 2 to 15 carbon atoms or the alkynyl group has 2 to 15 carbon atoms. (In formula (1), R １ ~R ３ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. １ ~R ３ at least one of which is an alkenyl group having 2 to 15 carbon atoms or an alkynyl group having 2 to 15 carbon atoms) (In formula (2), R ４ ~R ６ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. ４ ~R ６ does not have unsaturated carbon bonds.) (In formula (3), R ７ and R １０ is a hydrocarbon group having 1 to 15 carbon atoms, and R ８ and R ９ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms. ７ ~R １０ At least one of is an alkenyl group having 2 to 15 carbon atoms or an alkynyl group having 2 to 15 carbon atoms.

2. The curable composition of claim 1 further comprising a thermoplastic elastomer.

3. The curable composition of claim 1 or 2, further comprising a phosphorus-containing flame retardant.

4. A dry film or prepreg obtained by applying the curable composition according to any one of claims 1 to 3 to a substrate.

5. A cured product obtained by curing the curable composition according to any one of claims 1 to 3.

6. A laminate comprising the cured product according to claim 5.

7. An electronic part comprising the cured product according to claim 5.

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