Curable composition containing polyphenylene ether, dry film, cured product, and electronic component

Abstract

To provide a curable composition useful for the formation of a dry film having low dielectric characteristics and excellent processability and handling property.SOLUTION: There is provided a curable composition which comprises a polyphenylene ether and a compound containing a functional group having an unsaturated carbon bond. The polyphenylene ether is obtained from a raw material phenol including phenols satisfying at least Condition 1 and has a slope calculated by a conformation plot of less than 0.6. In addition, the compound containing a functional group having an unsaturated carbon bond is liquid at 20°C under atmospheric pressure and has a weight loss rate in thermogravimetric analysis (at 30 to 110°C, with a temperature increase rate of 10°C / min.) of 3 mass% or less. (Condition 1) Having hydrogen atoms at the ortho position and the para position.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, with the spread of high-capacity, high-speed communications such as fifth-generation communication systems (5G) and millimeter-wave radar for automotive ADAS (Advanced Driver Assistance Systems), signals from electronic devices are becoming increasingly high-frequency.

[0003] The wiring boards built into such electronic devices have traditionally used curable resin compositions containing epoxy resins or other resins as insulating materials. However, cured products made from such compositions have high dielectric constants (Dk) and dielectric loss tangents (Df), resulting in increased transmission loss for high-frequency signals, and problems such as signal attenuation and heat generation. For this reason, polyphenylene ether, which has excellent low dielectric properties, has attracted attention.

[0004] On the other hand, for insulating materials used in wiring boards, from the viewpoints of controlling film thickness, preventing foreign matter contamination, and simplifying the process, there is a demand for dry film-type products in which a dry coating film made of a curable resin composition is formed on a substrate such as a polyethylene terephthalate (PET) film.

[0005] Patent Document 1 discloses a curable composition and a dry film containing a polyphenylene ether having a branched structure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-15909 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the dry film having a resin layer made of a curable composition containing polyphenylene ether described in Patent Document 1 has low dielectric properties, it is prone to defects such as cracking and peeling from the base film when the dry film is cut to a desired size or bent during handling, and has problems such as poor processability and handleability.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a curable composition useful for forming a dry film having low dielectric properties and excellent processability and handling properties. [Means for solving the problem]

[0009] The present inventors have found that the above-mentioned problems can be solved by making a curable composition contain a polyphenylene ether having a branched structure and further contain a specific compound, and have completed the present invention. That is, the present invention is as follows.

[0010] The curable composition is characterized by comprising: a polyphenylene ether obtained from raw material phenols containing at least phenols that satisfy condition 1, and having a slope of less than 0.6 as calculated in a conformation plot; and a compound that contains a functional group with an unsaturated carbon bond, which is liquid at 20°C under atmospheric pressure and exhibits a weight loss rate of 3% by mass or less in thermogravimetric analysis (30 to 110°C, heating rate 10°C / min). (Condition 1) Contains hydrogen atoms in the ortho and para positions

[0011] The functional group having an unsaturated carbon bond in the compound of the present invention may be an allyl group. The polyphenylene ether of the present invention may contain a functional group having an unsaturated carbon bond.

[0012] The present invention may also be a dry film having a resin layer made of the curable composition. The present invention may also be a cured product of the curable composition or the resin layer. The present invention may also relate to an electronic component having the cured product. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a curable composition that is useful for forming a dry film having low dielectric properties and excellent processability and handling properties. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a curable composition containing polyphenylene ether will be described, but the present invention is not limited to the following in any way.

[0015] When the compounds described have isomers, all possible isomers can be used in the present invention unless otherwise specified.

[0016] 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).

[0017] In the present invention, the functional group having an unsaturated carbon bond is not particularly limited, but is preferably an alkenyl group (e.g., a vinyl group, an allyl group), an alkynyl group (e.g., an ethynyl group), or a (meth)acryloyl group, more preferably a vinyl group, an allyl group, or a (meth)acryloyl group from the viewpoint of excellent curability, and even more preferably an allyl group from the viewpoint of excellent low dielectric properties. Note that the number of carbon atoms in these functional groups having an unsaturated carbon bond can be, for example, 15 or less, 10 or less, 8 or less, 5 or less, 3 or less, etc.

[0018] In the present invention, phenols that are used as raw materials for polyphenylene ether (PPE) and can become structural units of polyphenylene ether are collectively referred to as "raw material phenols."

[0019] 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.

[0020] 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.

[0021] In this specification, monohydric phenols are mainly disclosed as the raw material phenols, but polyhydric phenols may also be used as the raw material phenols within the range that does not impair the effects of the present invention.

[0022] In this specification, the term "resin composition" may be used to mean a "curable composition."

[0023] In this specification, when the upper and lower limits of a numerical range are separately stated, all combinations of each lower limit and each upper limit are considered to be substantially stated within a consistent range.

[0024] <<<<Curable composition>>>> In this embodiment, the curable composition contains polyphenylene ether and a compound having a functional group containing an unsaturated carbon bond (hereinafter also referred to as an "unsaturated carbon compound"). The curable composition may also contain other components within a range that does not impair the effects of this embodiment. Each component will be described below.

[0025] <<<Polyphenylene ether (prescribed polyphenylene ether)>>> The polyphenylene ether of this embodiment is a polyphenylene ether having a branched structure obtained from raw material phenols containing phenols that at least satisfy condition 1. Such a polyphenylene ether is referred to as a predetermined polyphenylene ether. (Condition 1) Contains hydrogen atoms in the ortho and para positions

[0026] Phenols satisfying condition 1 {for example, phenols (A) and (B) described below} have a hydrogen atom at the ortho position. Therefore, when oxidatively polymerized with a phenol, an ether bond can be formed not only at the ipso position and the para position but also at the ortho position, making it possible to form a branched-chain structure.

[0027] Such a polyphenylene ether having a branched structure may be expressed as a predetermined polyphenylene ether or a branched polyphenylene ether.

[0028] In this way, the structure of the predetermined polyphenylene ether is partly branched by benzene rings ether-bonded at at least three positions, i.e., the ipso, ortho, and para positions. This predetermined polyphenylene ether is considered to be, for example, a polyphenylene ether compound having at least a branched structure represented by formula (i) in its skeleton.

[0029] [ka]

[0030] In formula (i), R a ~R k are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 1 to 12 carbon atoms).

[0031] Here, the raw material phenols constituting the predetermined polyphenylene ether may contain other phenols that do not satisfy condition 1, within the range that does not impair the effects of this embodiment.

[0032] Examples of such other phenols include phenols (C) and (D) described below, and phenols that do not have a hydrogen atom at the para position. In particular, when phenols (C) and (D) described below are oxidatively polymerized, ether bonds are formed at the ipso and para positions, resulting in linear polymerization. Therefore, in order to increase the molecular weight of polyphenylene ether, it is preferable to further include phenols (C) and (D) as raw material phenols.

[0033] The polyphenylene ether may also have a functional group containing an unsaturated carbon bond, which provides crosslinkability and excellent reactivity, resulting in improved properties of the cured product.

[0034] The method for introducing such a functional group containing an unsaturated carbon bond into a predetermined polyphenylene ether is not particularly limited, but may be, for example, As raw material phenols, This method comprises adding a phenol (A) that satisfies at least both the following condition 1 and the following condition 2 (Mode 1), or adding 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 (Mode 2). (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.

[0035] The predetermined polyphenylene ether obtained by the above method has crosslinkability due to a hydrocarbon group containing at least an unsaturated carbon bond, since it uses, as at least a phenol raw material, a phenol satisfying condition 2 {for example, either phenol (A) or phenol (C)}. When the predetermined polyphenylene ether has a hydrocarbon group containing such an unsaturated carbon bond, it is also possible to carry out modification such as epoxidation using a compound that reacts with the hydrocarbon group and has a reactive functional group such as an epoxy group.

[0036] That is, the predetermined polyphenylene ether obtained by the above method is, for example, a polyphenylene ether having at least a branched structure represented by formula (i) in the skeleton, and is considered to be a compound having a hydrocarbon group containing at least one unsaturated carbon bond as a functional group. a ~R k At least one of the above is a hydrocarbon group having an unsaturated carbon bond.

[0037] In particular, 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.

[0038] The phenols (A) to (D) will be described in more detail below.

[0039] 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):

[0040] [ka]

[0041] In formula (1), R1 to R3 are each independently a hydrogen atom or a hydrocarbon group 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.

[0042] 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.

[0043] 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):

[0044] [ka]

[0045] In formula (2), R4 to R6 are each independently a hydrogen atom or a hydrocarbon group 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 group preferably has 1 to 12 carbon atoms.

[0046] 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.

[0047] 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):

[0048] [ka]

[0049] In formula (3), R7 and R 10 are each independently a hydrocarbon group having 1 to 15 carbon atoms, and R8 and R9 are each independently a hydrogen atom or a hydrocarbon group 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.

[0050] 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.

[0051] As described above, the phenol (D) is a phenol having a hydrogen atom at the para position, not having a hydrogen atom at the ortho position, and not having a functional group containing an unsaturated carbon bond, and is preferably a phenol (d) represented by the following formula (4):

[0052] [ka]

[0053] In formula (4), R 11 and R 14 are each independently a hydrocarbon group having 1 to 15 carbon atoms and no unsaturated carbon bond, and R 12 and R 13 are each independently 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.

[0054] 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.

[0055] In this embodiment, 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.

[0056] When the predetermined polyphenylene ethers as described above are used as components of a curable composition, they may be used alone or in combination of two or more.

[0057] The ratio of the phenols satisfying condition 1 to the total of the raw material phenols used in synthesizing the predetermined polyphenylene ether is preferably 1 to 50 mol %.

[0058] Furthermore, it is not necessary to use phenols that satisfy the above condition 2, but if they are used, the ratio of phenols that satisfy the condition 2 to the total amount of raw material phenols is preferably 0.5 to 99 mol%, more preferably 1 to 99 mol%.

[0059] <<Physical properties and characteristics of specific polyphenylene ethers>> <Degree of branching> The branched structure (degree of branching) of a given polyphenylene ether can be confirmed based on the following analytical procedure.

[0060] (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 found by the least squares method from a logarithmic graph (conformation plot) of molecular weight versus radius of gyration, and its slope is calculated.

[0061] (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.

[0062] 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 this embodiment, 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.

[0063] In the polyphenylene ether constituting the curable composition of this embodiment, the slope is preferably less than 0.6, and is preferably 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, or 0.35 or less. When the slope is within this range, the polyphenylene ether is considered to have sufficient branching. The lower limit of the slope is not particularly limited, and is, for example, 0.05 or more, 0.10 or more, 0.15 or more, or 0.20 or more.

[0064] 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).

[0065] <Molecular weight of specified polyphenylene ether> The predetermined polyphenylene ether constituting the curable composition of this embodiment preferably has a number average molecular weight of 2,000 to 30,000, more preferably 5,000 to 30,000, even more preferably 8,000 to 30,000, and particularly preferably 8,000 to 25,000. By setting the molecular weight within this range, the film-forming properties of the curable composition can be improved while maintaining solubility in solvents. Furthermore, the predetermined polyphenylene ether constituting the curable composition of this embodiment preferably has a polydispersity index (PDI: weight average molecular weight / number average molecular weight) of 1.5 to 20.

[0066] In this embodiment, the number average molecular weight and the weight average molecular weight are measured by gel permeation chromatography (GPC) and converted using a calibration curve prepared using standard polystyrene.

[0067] <Hydroxyl value of specified polyphenylene ether> The hydroxyl value of the predetermined polyphenylene ether constituting the curable composition of this embodiment is preferably 15.0 or less, more preferably 2 or more and 10 or less, and even more preferably 3 or more and 8 or less, when the number average molecular weight (Mn) is in the range of 2,000 to 30,000.

[0068] <Solubility of specific polyphenylene ether in solvent> 1 g of the predetermined polyphenylene ether constituting the curable composition of this embodiment 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 no turbidity or precipitation is visually observed when 1 g of polyphenylene ether is mixed with 100 g of the solvent. More preferably, at least 1 g of this predetermined polyphenylene ether is soluble in 100 g of cyclohexanone at 25°C.

[0069] The branched structure of the specific polyphenylene ether constituting the curable composition of this embodiment improves solubility in various solvents and the dispersibility and compatibility of the components in the composition (unsaturated carbon compounds and other components). This allows each component of the composition to be uniformly dissolved or dispersed, making it possible to obtain a uniform dried coating film or cured product. As a result, the dry film has excellent processability and handleability, and the mechanical properties of the cured product are extremely excellent. In particular, when the specific polyphenylene ether contains functional groups with unsaturated carbon bonds, it can be crosslinked with each other or with unsaturated carbon compounds. As a result, the mechanical properties and low thermal expansion of the resulting cured product are improved.

[0070] <<Method of producing a specified polyphenylene ether>> The specified polyphenylene ether constituting the curable composition of the present embodiment 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.

[0071] Next, an example of a method for producing this predetermined polyphenylene ether will be described.

[0072] A specific polyphenylene ether can be produced, for example, by preparing a polymerization solution containing a specific phenol, a catalyst, and a solvent (polymerization solution preparation step), bubbling oxygen into at least the solvent (oxygen supply step), and oxidatively polymerizing the phenol in the oxygen-containing polymerization solution (polymerization step).

[0073] The polymerization solution preparation step, oxygen supply step, and polymerization step will be described below. The steps may be carried out continuously, or part or all of one step may be carried out simultaneously with part or all of another step, or one step may be interrupted and another step carried out in between. For example, the oxygen supply step may be carried out during the polymerization solution preparation step or the polymerization step. The method for producing polyphenylene ether of this embodiment may also include other steps as needed. Examples of other steps include a step of extracting the polyphenylene ether obtained by the polymerization step (e.g., steps of reprecipitation, filtration, and drying), the modification step described above, and the like.

[0074] <Polymerization solution preparation process> The polymerization solution preparation step is a step of preparing a polymerization solution by mixing raw materials including phenols to be polymerized in the polymerization step described below. The raw materials for the polymerization solution include raw material phenols, a catalyst, and a solvent.

[0075] (catalyst) The catalyst is not particularly limited, and any suitable catalyst used in the oxidative polymerization of polyphenylene ether may be used.

[0076] Examples of catalysts include amine compounds and metal amine compounds composed of a heavy metal compound such as copper, manganese, or cobalt and an amine compound such as tetramethylethylenediamine. In particular, to obtain a copolymer with a sufficient molecular weight, it is preferable to use a copper-amine compound in which a copper compound is coordinated with an amine compound. Only one type of catalyst may be used, or two or more types may be used.

[0077] The content of the catalyst is not particularly limited, but may be, for example, 0.1 to 0.6 mol % relative to the total amount of the raw material phenols in the polymerization solution.

[0078] Such a catalyst may be dissolved in advance in a suitable solvent.

[0079] (solvent) The solvent is not particularly limited, and may be any suitable solvent used in the oxidative polymerization of polyphenylene ether. It is preferable to use a solvent that can dissolve or disperse the phenolic compound and the catalyst.

[0080] Specific examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, halogenated aromatic hydrocarbons such as chloroform, methylene chloride, chlorobenzene, dichlorobenzene, and trichlorobenzene, nitro compounds such as nitrobenzene, methyl ethyl ketone (MEK), cyclohexanone, tetrahydrofuran, ethyl acetate, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), propylene glycol monomethyl ether acetate (PMA), and diethylene glycol monoethyl ether acetate (CA). Only one type of solvent may be used, or two or more types may be used.

[0081] The solvent may include water or a solvent compatible with water.

[0082] The content of the solvent in the polymerization solution is not particularly limited and may be adjusted appropriately.

[0083] (Other ingredients) The polymerization solution may contain other raw materials as long as the effects of this embodiment are not impaired.

[0084] <Oxygen supply process> The oxygen supply step is a step of bubbling an oxygen-containing gas into the polymerization solution.

[0085] The time for passing oxygen gas and the oxygen concentration in the oxygen-containing gas used can be changed as appropriate depending on the atmospheric pressure, temperature, and the like.

[0086] <Polymerization process> The polymerization step is a step in which phenols in a polymerization solution are oxidatively polymerized under conditions in which oxygen is supplied to the polymerization solution.

[0087] Specific polymerization conditions are not particularly limited, but may be, for example, stirring at 25 to 100° C. for 2 to 24 hours.

[0088] In producing a predetermined polyphenylene ether through the steps described above, a specific method for introducing a functional group containing an unsaturated carbon bond into a branched polyphenylene ether can be understood by referring to the above-mentioned method. That is, by using a specific type of raw material phenol, a predetermined polyphenylene ether having a functional group containing an unsaturated carbon bond can be obtained.

[0089] <<<Unsaturated carbon compounds>>> The unsaturated carbon compound of this embodiment is liquid at 20° C. under atmospheric pressure. Here, "liquid at 20° C." specifically refers to a sample prepared by placing 0.2 ml of the unsaturated carbon compound in a vial with an inner diameter of 1.0 cm and a height of 3.2 cm, with a marked line 2 cm from the bottom, and then allowing the vial to stand at -20° C. for 3 hours in an upright position, and then leaving the vial to stand at 20° C. for 30 minutes, and then quickly turning the vial over horizontally. The unsaturated carbon compound flows, and it takes less than 60 seconds for the leading edge of the liquid surface of the compound to reach the marked line.

[0090] The unsaturated carbon compound of this embodiment exhibits a weight loss rate of 3% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less, in thermogravimetric analysis (30 to 110°C, heating rate of 10°C / min). The weight loss rate can be measured in an air atmosphere at a flow rate of 10 mL / min. For the thermogravimetric analysis, for example, a thermogravimetric analyzer TGA5500 manufactured by TA Instruments can be used.

[0091] The number of functional groups having an unsaturated carbon bond in the unsaturated carbon compound is not particularly limited, but from the viewpoint of reacting with polyphenylene ether and the mechanical properties of the cured product, it is preferable that there are multiple functional groups and that they are located at the terminals.

[0092] Furthermore, the structure of the unsaturated carbon compound is not particularly limited, but it is preferable that the unsaturated carbon compound contains a cyclic structure (for example, an aromatic ring, an aliphatic ring, or a heterocyclic ring) from the viewpoint of heat resistance, and it is more preferable that the unsaturated carbon compound contains an aromatic ring.

[0093] The molecular weight of the unsaturated carbon compound is not particularly limited, but is preferably 150-300, and more preferably 180-280.

[0094] Examples of unsaturated carbon compounds include diallyl phthalate, diallyl isophthalate, and diallyl 1,4-cyclohexanedicarboxylate. Among these, diallyl phthalate and diallyl isophthalate are preferred because they have excellent compatibility with polyphenylene ether. Only one type of unsaturated carbon compound may be used, or two or more types may be used.

[0095] When the component of the curable composition containing the specified polyphenylene ether contains a hydrocarbon group having an unsaturated carbon bond, a cured product having excellent mechanical strength can be obtained by curing the composition with an unsaturated carbon compound in particular.

[0096] In the curable composition, the blending ratio of the unsaturated carbon compound (e.g., diallyl phthalate) is preferably 10 to 50 mass % relative to the total amount of organic components (excluding inorganic fillers such as silica) in the composition from the viewpoint of flexibility as a dry film and low dielectric properties as a cured product, and more preferably 15 to 35 mass % from the viewpoint of releasability of the base film and suppression of bleeding when the dry film is thermocompression bonded (laminated).

[0097] <<<Other ingredients>>> Examples of other components include conventionally known additives that can be blended into curable compositions, and more specifically, preferred components include silica, peroxides, maleimide compounds, elastomers, and the like.

[0098] Furthermore, the other components may include, within the scope that does not impair the effects of this embodiment, components such as a flame retardancy improver (phosphorus-based compounds, etc.), cellulose nanofibers, polymer components (resin components such as cyanate ester resins, epoxy resins, and phenol novolac resins, and organic polymers such as unbranched polyphenylene ethers, polyimides, and polyamides), dispersants, thermosetting catalysts, thickeners, antifoaming agents, antioxidants, rust inhibitors, adhesion promoters, and solvents. These may be used alone or in combination of two or more.

[0099] <<Silica>> The curable composition may contain silica. By including silica in the composition, the film-forming properties of the composition can be improved. Furthermore, the resulting cured product can be imparted with flame retardancy. More specifically, by incorporating silica into the composition, the cured product can be made to have high levels of self-extinguishing properties and low dielectric loss tangent.

[0100] The average particle size of the silica is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm. 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.

[0101] It is also possible to use silica with different average particle sizes in combination. When a high silica loading is desired, 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 nano order.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The content of silica may be 50 to 400 parts by mass or 100 to 400 parts by mass relative to 100 parts by mass of polyphenylene ether, or 10 to 30% by mass based on the total solid content of the composition.

[0106] <<Peroxide>> The above-mentioned curable composition preferably contains a peroxide.

[0107] 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.

[0108] 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 shelf life of the curable composition containing polyphenylene ether. In addition, due to their low volatility, they do not volatilize during drying or storage, resulting in good stability.

[0109] The content of the peroxide in the curable composition is preferably 0.01 to 20 mass%, more preferably 0.05 to 10 mass%, and particularly preferably 0.1 to 10 mass%, of the total 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.

[0110] 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.

[0111] <<Maleimide compounds>> The maleimide compound is not particularly limited as long as it contains at least one maleimide group in one molecule.

[0112] Examples of the maleimide compound include: (1) monofunctional aliphatic / alicyclic maleimides, (2) monofunctional aromatic maleimide, (3) polyfunctional aliphatic / alicyclic maleimide, (4) polyfunctional aromatic maleimides, Examples include:

[0113] <(1) Monofunctional Aliphatic / Alicyclic Maleimides> Examples of the monofunctional aliphatic / alicyclic maleimide (1) include N-methylmaleimide, N-ethylmaleimide, and the reaction product of maleimidocarboxylic acid with tetrahydrofurfuryl alcohol disclosed in JP-A-11-302278.

[0114] <<(2) Monofunctional aromatic maleimide>> Examples of the monofunctional aromatic maleimide (2) include N-phenylmaleimide and N-(2-methylphenyl)maleimide.

[0115] <(3) Polyfunctional aliphatic / alicyclic maleimide> Examples of the polyfunctional aliphatic / alicyclic maleimide (3) include isocyanurate-skeleton polymaleimides such as N,N'-methylene bismaleimide, N,N'-ethylene bismaleimide, maleimide ester compounds having an isocyanurate skeleton obtained by dehydration esterification of tris(hydroxyethyl)isocyanurate and aliphatic / alicyclic maleimide carboxylic acid, and maleimide urethane compounds having an isocyanurate skeleton obtained by urethanization of tris(carbamate hexyl)isocyanurate and aliphatic / alicyclic maleimide alcohol, isophorone bisurethane bis(N-ethylmaleimide), triethylene glycol bis(maleimide ethyl carboxylic acid), and the like. Examples of such compounds include aliphatic / alicyclic polymaleimide ester compounds obtained by dehydrating an aliphatic / alicyclic maleimide carboxylic acid with various aliphatic / alicyclic polyols or by transesterification of an aliphatic / alicyclic maleimide carboxylic acid ester with various aliphatic / alicyclic polyols, aliphatic / alicyclic polymaleimide ester compounds obtained by subjecting an aliphatic / alicyclic maleimide carboxylic acid to an ether ring-opening reaction with various aliphatic / alicyclic polyepoxides, and aliphatic / alicyclic polymaleimide urethane compounds obtained by subjecting an aliphatic / alicyclic maleimide alcohol to a urethanization reaction with various aliphatic / alicyclic polyisocyanates.

[0116] Specific examples include aliphatic bismaleimide compounds represented by the following general formulas (X1) and (X2), which are obtained by subjecting a maleimide alkylcarboxylic acid or a maleimide alkylcarboxylic acid ester having an alkyl group of 1 to 6 carbon atoms, more preferably a linear alkyl group, to a dehydration esterification reaction or a transesterification reaction with polyethylene glycol having a number average molecular weight of 100 to 1000 and / or polypropylene glycol having a number average molecular weight of 100 to 1000 and / or polytetramethylene glycol having a number average molecular weight of 100 to 1000.

[0117] [ka] (wherein m is an integer of 1 to 6, n is a value of 2 to 23, R 1 represents a hydrogen atom or a methyl group.

[0118] [ka] (In the formula, m represents an integer of 1 to 6, and p represents a value of 2 to 14.)

[0119] <(4) Polyfunctional aromatic maleimide> Examples of the polyfunctional aromatic maleimide (4) include N,N'-(4,4'-diphenylmethane)bismaleimide, bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane, 2,2'-bis-(4-(4-maleimidophenoxy)propane, N,N'-(4,4'-diphenyloxy)bismaleimide, N,N'-p-phenylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-2,4-tolylenebismaleimide, and N,N'-2,6-tolylenebismaleimide. Examples of such compounds include aromatic polymaleimide ester compounds obtained by dehydrating and esterifying maleimide carboxylic acid with various aromatic polyols or by transesterifying maleimide carboxylic acid esters with various aromatic polyols, aromatic polymaleimide ester compounds obtained by subjecting maleimide carboxylic acid to an ether ring-opening reaction with various aromatic polyepoxides, and aromatic polymaleimide urethane compounds obtained by subjecting maleimide alcohol to a urethanization reaction with various aromatic polyisocyanates.

[0120] Among these, the maleimide compound is preferably polyfunctional. The maleimide compound preferably has a bismaleimide skeleton. The maleimide compounds can be used alone or in combination of two or more.

[0121] The weight average molecular weight of the maleimide compound is not particularly limited, but can be 100 or more, 200 or more, 500 or more, 750 or more, 1,000 or more, 2,000 or more, or 100,000 or less, 50,000 or less, 10,000 or less, 5,000 or less, 4,000 or less, or 3,500 or less.

[0122] The content of the maleimide compound can typically be 0.5 to 50 mass %, 1 to 40 mass %, or 1.5 to 30 mass % based on the total solid content in the curable composition. From another perspective, the blending ratio of the predetermined polyphenylene ether to the maleimide compound in the curable composition can be set to 9:91 to 99:1, 17:83 to 95:5, or 25:75 to 90:10 in terms of solid content ratio. Furthermore, when the curable composition contains a maleimide compound and an unsaturated carbon compound, the blending ratio of the maleimide compound to the unsaturated carbon compound, expressed as a solids ratio (maleimide compound:unsaturated carbon compound), is preferably 80:20 to 10:90, and more preferably 70:30 to 20:80. By setting the ratio within this range, a cured product having excellent dielectric properties and heat resistance can be obtained.

[0123] <<Elastomer>> Examples of the elastomer include diene-based synthetic rubbers such as polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber, and ethylene-propylene rubber; non-diene-based synthetic rubbers such as ethylene-propylene rubber, butyl rubber, acrylic rubber, polyurethane rubber, fluororubber, silicone rubber, and epichlorohydrin rubber; natural rubber, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic elastomers, and silicone-based elastomers.

[0124] From the viewpoints of compatibility with polyphenylene ether and dielectric properties, at least a portion of the elastomer is preferably a styrene-based elastomer. Examples of styrene-based elastomers include styrene-butadiene copolymers such as styrene-butadiene-styrene block copolymer and styrene-butadiene-butylene-styrene block copolymer; styrene-isoprene copolymers such as styrene-isoprene-styrene block copolymer; styrene-ethylene-butylene-styrene block copolymer and styrene-ethylene-propylene-styrene block copolymer. Styrene-based elastomers without unsaturated carbon bonds, such as styrene-ethylene-butylene-styrene block copolymer, are preferred because they provide particularly good dielectric properties to the resulting cured product.

[0125] The content of the styrene block in the styrene-based elastomer is preferably 10 to 70 mass%, 30 to 60 mass%, or 40 to 50 mass%. 1 It can be determined from the integral ratio of the spectrum measured by H-NMR.

[0126] 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.

[0127] The content of the styrene-based elastomer in 100% by mass of the elastomer may be, for example, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass.

[0128] The elastomer may have functional groups (including bonds) that react with other components.

[0129] For example, the reactive functional group may have an unsaturated carbon bond. By configuring the elastomer in this way, it is possible to crosslink the unsaturated carbon bond (for example, the unsaturated carbon bond of a branched polyphenylene ether), which has the effect of reducing the risk of bleed-out.

[0130] The elastomer may be modified with (meth)acrylic acid, maleic acid, anhydrides or esters thereof, or may be obtained by adding water to the remaining unsaturated bonds of a diene-based elastomer.

[0131] The number average molecular weight of the elastomer may be 1,000 to 150,000. When the number average molecular weight is equal to or greater than the lower limit, low thermal expansion is excellent, and when it is equal to or less than the upper limit, compatibility with other components is excellent.

[0132] The content of the elastomer in the curable composition may be 10 to 300 parts by mass per 100 parts by mass of the specified polyphenylene ether. Alternatively, the content of the elastomer may be 3 to 65% by mass based on the total solid content of the curable composition. When the content is within the above range, a good balance of good tensile properties, adhesion, and heat resistance can be achieved.

[0133] <<<<Dry film>>>> The dry film of this embodiment is obtained by applying the above-described curable composition to a substrate and drying it.

[0134] A method for producing a dry film includes, for example, applying a solution of the curable composition described above onto a substrate film using an applicator or the like, followed by drying. After drying, a step of providing other layers (e.g., a cover film) may be carried out as necessary.

[0135] The coating and drying of the curable composition can be carried out by known methods and conditions, for example, by known coating methods such as a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, or spray coater, to obtain a curable composition with a uniform thickness.

[0136] Thereafter, the resin layer can be formed by heating and drying the curable composition obtained by coating for 1 to 30 minutes at a temperature of 50 to 130° C. Heat drying can be carried out by known heating means such as a hot air circulation drying oven, an IR oven, a hot plate, or a convection oven.

[0137] The thickness of the resin layer can be adjusted by changing the coating conditions and the viscosity of the curable composition.

[0138] Examples of the substrate include films such as polyethylene terephthalate (PET) film, polyimide film, polyester film, and polyethylene naphthalate (PEN) film.

[0139] The dry film can be obtained, for example, by applying a curable composition onto a polyethylene terephthalate (PET) film, drying the composition, and, if necessary, laminating a polypropylene film as a protective film.

[0140] The dry film of this embodiment has low dielectric properties and excellent flexibility, that is, according to this embodiment, a dry film with improved processability and handling properties can be obtained.

[0141] <<<<Cured product>>>> The cured product of this embodiment is obtained by curing the above-described dry film.

[0142] The method for obtaining a cured product from the above-mentioned dry film is not particularly limited, and one example involves peeling off the protective film from the dry film, thermocompressing the dried coating film side consisting of the curable composition to a copper-clad laminate or a glass substrate using a press, vacuum laminator, roll laminator, or the like, and then peeling off the PET film, followed by a thermal curing step in which the polyphenylene ether is thermally crosslinked by heating (for example, heating with an inert gas oven, hot plate, vacuum oven, vacuum press, or the like). Note that the conditions for each step (for example, 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.

[0143] <<<<Electronic Components>>>> The electronic component of this embodiment has the cured product of this embodiment described above, and has excellent dielectric properties and heat resistance, so that it can be used in a variety of applications.

[0144] Its use is not particularly limited, but preferred applications include large-capacity, high-speed communications such as those typified by fifth-generation communication systems (5G) and millimeter-wave radar for automotive ADAS (Advanced Driver Assistance Systems). [Example]

[0145] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to the following in any way.

[0146] <<<Synthesis of branched PPE>>> 2.6 g of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 3.18 mL of tetramethylethylenediamine (TMEDA) were added to a 3 L two-necked flask and thoroughly dissolved. Oxygen was supplied at 10 mL / min. A raw material solution was prepared by dissolving 105 g of 2,6-dimethylphenol and 13 g of 2-allylphenol, the raw phenols, in 1.5 L of toluene. 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 product 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 branched PPE.

[0147] The branched PPE had a number-average molecular weight of 20,000 and a weight-average molecular weight of 60,000. The slope of the conformation plot of the branched PPE was 0.31.

[0148] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the branched PPE 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.

[0149] <<<Determining the liquidity of unsaturated carbon compounds and measuring the weight loss rate>>> <<Liquid judgment>> To prepare the evaluation samples, 0.2 ml of each unsaturated carbon compound shown in Table 1 was placed in a 1.0 cm inner diameter, 3.2 cm high vial with a marked line 2 cm from the bottom. The evaluation samples were then left standing upright at -20°C for 3 hours, and then at 20°C for 30 minutes. The evaluation samples were then quickly turned horizontally, and the time it took for the unsaturated carbon compound to flow and reach the marked line was measured. A sample that took less than 60 seconds was evaluated as a liquid, and a sample that took 60 seconds or more was evaluated as a solid. The evaluation results are shown in Table 1.

[0150] <<Weight loss rate measurement>> The weight loss rate of each unsaturated carbon compound shown in Table 1 was measured under the following conditions. The measurement results are shown in Table 1. Apparatus: TA Instruments TGA5500 Thermogravimetric Analyzer Sample size: 10g Measurement atmosphere: Air Flow rate: 10mL / min. Measurement temperature range: 30 to 110°C Heating rate: 10℃ / min.

[0151] <<<Preparation of curable composition / production of dry film>>> Varnishes and dry films of the curable compositions of the Examples and Comparative Examples were obtained as follows.

[0152] <<Preparation of Curable Composition>> Example 1 A solvent was added to 100 parts by weight of branched PPE and 49 parts by weight of styrene-based elastomer (Asahi Kasei Corporation: trade name "Tuftec H1051"), and the mixture was stirred at 40°C for 30 minutes to completely dissolve the mixture. To the resulting PPE resin solution, 60 parts by weight of diallyl phthalate (Tokyo Chemical Industry Co., Ltd.), 560 parts by weight of spherical silica filler (Admatechs Co., Ltd.: trade name "SC2050-HNF"), and 16 parts by weight of maleimide resin (Designer Molecules: trade name "BMI-3000J", Mw=3,000) were added and mixed, followed by dispersion using a triple-roll mill. Finally, 4 parts by weight of α,α'-bis(t-butylperoxy-m-isopropyl)benzene (NOF Corporation: trade name "Perbutyl P-40"), a peroxide, was added and stirred using a magnetic stirrer. In this way, a varnish of the curable composition of Example 1 was obtained.

[0153] <Examples 2 and 3, Comparative Examples 1 to 4> As shown in Table 1, varnishes of the curable compositions of Examples 2 and 3 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1, except that the unsaturated carbon compounds used (all manufactured by Tokyo Chemical Industry Co., Ltd.) were changed.

[0154] <<Dry film production>> The varnishes of the curable compositions of the Examples and Comparative Examples were applied to a 38 μm thick PET film (manufactured by Toyobo Co., Ltd. under the trade name "TN-200") using an applicator so that the thickness of the resin layer after drying would be the value shown in Table 1, and the film was dried at 90°C for 5 minutes to obtain dry films of the Examples and Comparative Examples.

[0155] <<Preparation of cured product>> Each dry film of the Examples and Comparative Examples was placed on a low-roughness copper foil (FV-WS (Furukawa Electric Co., Ltd.): Rz = 1.2 μm) so that the resin composition of the dry film was in contact with the glossy surface, and the film was laminated using a vacuum laminator. The film was then heated to 200°C in an inert oven, completely filled with nitrogen, and cured for 60 minutes. The copper foil was then peeled off to obtain each cured film of the Examples and Comparative Examples.

[0156] <<<Evaluation>>> The above-described curable compositions, dry films, and cured films were evaluated as follows.

[0157] <Flexibility> The dry film was wrapped around an acrylic rod to check for cracks. Specifically, the dry film was wrapped around an acrylic rod with an outer diameter (φ) of 3 mm, 6 mm, or 9 mm, with the resin composition of the dry film facing outward, and the dry film was observed for cracks and evaluated according to the following criteria. (Evaluation criteria) ◎: No cracks were observed in the dry film at any outer diameter. 〇: Cracks in the dry film were observed at φ3mm △: Cracks in the dry film were observed at φ3mm and 6mm. ×: Cracks in the dry film were observed for all outer diameters

[0158] <Film forming properties> During the preparation of the cured film, cracks in the cured film were observed and evaluated according to the following criteria. (Evaluation criteria) ◯: No cracks in the cured film are observed ×: Cracks in the cured film are observed

[0159] <Dielectric constant> 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 and a width of 45 mm 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 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. Note that if cracks were observed in the cured film, the test piece could not be obtained, and therefore measurement was not possible.

[0160] [Table 1]

Claims

1. a polyphenylene ether obtained from raw material phenols containing at least phenols satisfying condition 1, and having a slope calculated from a conformation plot of less than 0.6; a compound containing a functional group having an unsaturated carbon bond, which is liquid at 20°C under atmospheric pressure and exhibits a weight loss rate of 3% by mass or less in thermogravimetric analysis (30 to 110°C, heating rate 10°C / min.), A curable composition wherein the polyphenylene ether comprises a functional group having an unsaturated carbon bond. (Condition 1) Contains hydrogen atoms in the ortho and para positions

2. The curable composition according to claim 1 , wherein the functional group having an unsaturated carbon bond of the compound is an allyl group.

3. A dry film having a resin layer made of the curable composition according to claim 1 or 2.

4. A cured product of a resin layer comprising the curable composition according to claim 1 or 2, or the curable composition in the dry film according to claim 3.

5. An electronic part comprising the cured product according to claim 4.

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