Curable resin composition and dry film

Abstract

To provide a curable resin composition that allows viscosity reduction during heating.SOLUTION: One embodiment of the present invention is a curable resin composition, the curable resin composition comprising a curable resin and a latent crosslinking agent, wherein the latent crosslinking agent is a maleimide compound protected with a blocking agent, and the blocking agent is a conjugated ene compound having a melting point of 100°C or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curable resin composition and a dry film. [Background technology]

[0002] 2. Description of the Related Art Conventionally, curable resin compositions containing various curable resins have been used as materials for forming interlayer insulating materials, solder resists, and the like.

[0003] For example, in the invention of Patent Document 1, epoxy resin, polyimide resin, fluororesin, polyphenylene ether resin, and the like, which are excellent in mechanical properties, are used as the insulating resin constituting the multilayer wiring board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-209360 A Summary of the Invention [Problem to be solved by the invention]

[0005] Methods for forming a resin layer using these curable resin compositions include a method in which a curable resin composition containing an uncured curable resin is applied to a substrate, and the curable resin is cured after drying as necessary; and a method in which a curable resin composition containing an uncured curable resin is applied to a support film to prepare a dry film having an uncured resin layer, the dry film is laminated to a substrate to transfer the uncured resin layer, and the curable resin contained in this resin layer is cured.

[0006] When forming a resin layer (uncured resin layer) by such a method, the viscosity (melt viscosity) during heating (dry film lamination or curing) may be important. If the melt viscosity of the resin layer is high, the resin layer cannot conform to the surface shape of the substrate, and the embedding ability of the resin layer and its cured product into the substrate becomes insufficient, and the resin layer may peel off from the substrate. Even if the resin layer is embedded in the substrate along the surface shape, the flatness of the substrate surface may be impaired.

[0007] Therefore, an object of the present invention is to provide a curable resin composition capable of reducing the viscosity when heated. [Means for solving the problem]

[0008] The present inventors have conducted extensive research and found that the above problems can be solved by a curable resin composition containing a specific component.

[0009] One aspect of the present invention is a curable resin composition. The curable resin composition includes a curable resin and a latent crosslinking agent, the latent crosslinking agent is a maleimide compound protected with a blocking agent, The blocking agent is a conjugated ene compound having a melting point of 100° C. or less.

[0010] The blocking agent is preferably a furan compound. The furan compound preferably has an alkyl group. The curable resin is preferably at least one selected from the group consisting of an epoxy resin, a curable polyphenylene ether resin, and a maleimide resin different from the latent crosslinking agent.

[0011] Another embodiment of the present invention is a dry film having a resin layer obtained by applying the curable resin composition to a film and drying the applied film. Effect of the Invention

[0012] According to the present invention, it is possible to provide a curable resin composition capable of reducing the viscosity when heated. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a 1H-NMR (DMSO-d6, room temperature) spectrum of the latent crosslinker 1 used in the examples. [Diagram 2] FIG. 2 is a 1H-NMR (DMSO-d6, room temperature) spectrum of the latent crosslinker 2 used in the examples. [Diagram 3] FIG. 3 is a 1H-NMR (DMSO-d6, room temperature) spectrum of the latent crosslinker 3 used in the examples. [Figure 4] FIG. 4 is a 1H-NMR (DMSO-d6, room temperature) spectrum of the latent crosslinker 4 used in the examples. [Diagram 5] FIG. 5 shows the results of thermogravimetric analysis of the maleimide compound, latent crosslinking agent 1, and latent crosslinking agent 2 used in the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] When isomers exist in the described compounds, all possible isomers can be used in the present invention unless otherwise specified.

[0015] All measurements in this specification were carried out at room temperature (25° C.) unless otherwise specified.

[0016] In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) are determined by gel permeation chromatography (GPC) using a Shodex K-805L column at a column temperature of 40° C., a flow rate of 1 mL / min, chloroform as the eluent, and polystyrene as the standard.

[0017] In this specification, when the upper limit and the lower limit of a numerical range are separately described, all combinations of the lower limit and the upper limit are substantially described, provided that there is no contradiction.

[0018] In this specification, unless otherwise specified, the term "unsaturated carbon bond" refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond).

[0019] In this specification, examples of the functional group having an unsaturated carbon bond include, but are not limited to, an alkenyl group (e.g., a vinyl group, an allyl group), an alkynyl group (e.g., an ethynyl group), a (meth)acryloyl group, and a maleimide group.

[0020] Hereinafter, the curable resin composition, and a dry film, a cured product, an electronic component, and the like obtained by using the curable resin composition will be described.

[0021] <<<<Curable resin composition>>>> The curable resin composition contains a curable resin and a latent crosslinking agent. The curable resin composition may also contain other components.

[0022] <<<Latent crosslinking agent>>> The latent crosslinking agent is a crosslinking agent blocked by a blocking agent. More specifically, the curable resin composition of the present disclosure uses a maleimide compound protected by a blocking agent as the latent crosslinking agent. Preferred maleimide compounds and blocking agents constituting the latent crosslinking agent are described in detail below.

[0023] <<Maleimide compounds>> A maleimide compound is a compound having one or more maleimide groups in one molecule. More specifically, the maleimide compound is (1) Monofunctional aliphatic / alicyclic maleimides, (2) monofunctional aromatic maleimide, (3) polyfunctional aliphatic / alicyclic maleimide, (4) polyfunctional aromatic maleimides, Examples include:

[0024] <(1) Monofunctional aliphatic / alicyclic maleimides> Examples of monofunctional aliphatic / alicyclic maleimides include N-methylmaleimide, N-ethylmaleimide, and the reaction product of maleimide carboxylic acid and tetrahydrofurfuryl alcohol disclosed in JP-A-11-302278.

[0025] <(2) Monofunctional aromatic maleimide> Examples of the monofunctional aromatic maleimide include N-phenylmaleimide and N-(2-methylphenyl)maleimide.

[0026] <(3) Polyfunctional aliphatic / alicyclic maleimide> Examples of polyfunctional aliphatic / alicyclic maleimides include isocyanurate-skeleton polymaleimides such as N,N'-methylene bismaleimide, N,N'-ethylene bismaleimide, maleimide ester compounds having an isocyanurate skeleton obtained by dehydrating and esterifying tris(hydroxyethyl)isocyanurate with aliphatic / alicyclic maleimide carboxylic acid, and maleimide urethane compounds having an isocyanurate skeleton obtained by urethanizing tris(carbamate hexyl)isocyanurate with aliphatic / alicyclic maleimide alcohol, isophorone bisurethane bis(N-ethylmaleimide), triethylene glycol bis(maleimide ethyl carbo esters), aliphatic / alicyclic polymaleimide ester compounds obtained by dehydrating esterification of aliphatic / alicyclic maleimide carboxylic acids with various aliphatic / alicyclic polyols, or by transesterification of aliphatic / alicyclic maleimide carboxylic acid esters with various aliphatic / alicyclic polyols, aliphatic / alicyclic polymaleimide ester compounds obtained by subjecting aliphatic / alicyclic maleimide carboxylic acids to an ether ring-opening reaction with various aliphatic / alicyclic polyepoxides, and aliphatic / alicyclic polymaleimide urethane compounds obtained by subjecting aliphatic / alicyclic maleimide alcohols to a urethanization reaction with various aliphatic / alicyclic polyisocyanates.

[0027] Specific examples include aliphatic bismaleimide compounds represented by the following general formulas (X1) and (X2), which are obtained by subjecting a maleimide alkyl carboxylic acid or a maleimide alkyl carboxylic acid ester having an alkyl group having 1 to 6 carbon atoms, more preferably a linear alkyl group, to a dehydration esterification reaction or an ester exchange reaction with a polyethylene glycol having a number average molecular weight of 100 to 1000 and / or a polypropylene glycol having a number average molecular weight of 100 to 1000 and / or a polytetramethylene glycol having a number average molecular weight of 100 to 1000.

[0028] [ka]

[0029] In formula (X1), m is an integer of 1 to 6, n is an integer of 2 to 23, R 1 represents a hydrogen atom or a methyl group.

[0030] [ka] In formula (X2), m represents an integer of 1 to 6, and p represents an integer of 2 to 14.

[0031] Further, examples of polyfunctional aliphatic / alicyclic maleimides include maleimide compounds having a dimer acid skeleton represented by formula (X3), which are reaction products of dimer diamine and maleic anhydride.

[0032] [ka] In formula (X3), R 1 represents a divalent hydrocarbon group derived from a dimer acid skeleton.

[0033] <(4) Polyfunctional aromatic maleimide> Examples of polyfunctional aromatic maleimides include maleimide compounds represented by the following formula (X4), maleimide compounds represented by the following formula (X5), 2,2'-bis-(4-(4-maleimidophenoxy)propane, N,N'-(4,4'-diphenyloxy)bismaleimide, N,N'-p-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-2,4-tolylene bismaleimide, N,N'-2,6-tolylene bismaleimide, aromatic polymaleimide ester compounds obtained by dehydrating and esterifying maleimide carboxylic acid with various aromatic polyols or by transesterifying maleimide carboxylic acid ester 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.

[0034] [ka]

[0035] In formula (X4), q is an integer of 1 to 10 (preferably, 1 to 5, 1 to 3, or 1), and R1, R2, R3, and R4 are each independently a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms (preferably, 1 to 3 carbon atoms).

[0036] Specific examples of the maleimide compound represented by the formula (X4) include N,N'-(4,4'-diphenylmethane)bismaleimide, bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane, and the like.

[0037] [ka] In formula (X5), r represents an integer of 1 to 5, and R5, R6, R7, and R8 are each independently a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms (preferably, 1 to 3 carbon atoms).

[0038] Among these, the maleimide compound is preferably polyfunctional. The maleimide compound preferably has a bismaleimide skeleton. The maleimide compound may be used alone or in combination of two or more.

[0039] The maleimide compounds can be used alone or in combination of two or more kinds.

[0040] 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.

[0041] <<Blocking agent>> The blocking agent according to the present disclosure is a conjugated ene compound. In the present disclosure, the conjugated ene compound is a compound having at least two carbon-carbon double bonds in a conjugated relationship. The conjugated ene compound may have three or more carbon-carbon double bonds in a conjugated relationship, or may further have a carbon-carbon double bond that is not in a conjugated relationship. The conjugated ene compound is preferably a conjugated diene compound having two carbon-carbon double bonds in a conjugated relationship. As the conjugated ene compound, a conventionally known compound can be used, and is not particularly limited. The conjugated ene compound may contain a heteroatom.

[0042] As described later, the conjugated ene compound preferably has a melting point of 100° C. or lower.

[0043] Examples of the conjugated ene compound include butadiene, isoprene, 1,3-pentadiene, 2,4-hexadiene, 1,3,5-hexatriene, and cycloheptatriene.

[0044] The conjugated ene compound may be a linear conjugated ene compound or a cyclic conjugated ene compound, preferably a cyclic conjugated ene compound, and more preferably a cyclic conjugated diene compound.

[0045] Examples of the cyclic conjugated diene compound include those having a five-membered ring structure or a six-membered ring structure as represented by the following formula (A).

[0046] [ka]

[0047] In formula (A), R 11 , R 12 , R 13 , R 14 are each independently any group, preferably hydrogen, a halogen group, or a hydrocarbon group (having 1 to 5 or 1 to 4 carbon atoms) which may or may not have a heteroatom (for example, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a halogen atom, and preferably an oxygen atom), and more preferably hydrogen, or a hydrocarbon group (having 1 to 5 or 1 to 4 carbon atoms) which may or may not have a heteroatom. In formula (A), X is a group represented by -O-, -CH2-, -NH-, -C(=O)-, or -S- (form 1), or a group represented by -CH2-O-, -CH2-CH2-, -CH2-NH-, -CH2-C(=O)-, -CH2-S-, or -C(=O)-O- (form 2). In the case of Form 1, the cyclic conjugated diene compound represented by formula (A) has a five-membered ring structure. In the case of Form 2, the cyclic conjugated diene compound represented by formula (A) has a six-membered ring structure.

[0048] In formula (A), R 11 , R 12 , R 13 , R 14 At least one of these is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms.

[0049] In the formula (A), a preferred example of the hydrocarbon group having an oxygen atom as a heteroatom is -(CH2) n -OR AIn addition, n is a natural number of 1 to 3, and R A is -CO-R B A group represented by (R B is a hydrocarbon group having 1 to 2 carbon atoms, preferably 1 carbon atom, or -R C A group represented by (R C represents a hydrocarbon group having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms.

[0050] Representative examples of preferred cyclic conjugated diene compounds include furan compounds and 2-pyrone compounds, such as those represented by formula (A) in which X has a group represented by -O- or -C(=O)-O-. In particular, by using a furan compound as the cyclic conjugated diene compound, the resulting cured film tends to have excellent low dielectric tangent characteristics.

[0051] When a latent crosslinking agent is obtained by blocking a maleimide compound using a compound represented by formula (A) in which X has a group represented by -O-, the latent crosslinking agent has a structure represented by the following formula (B) as a terminal group.

[0052] [ka]

[0053] In formula (B), * represents a bond. In formula (B), R 11 , R 12 , R 13 , R 14 are the same as those represented by formula (A) and each independently represents an arbitrary group, preferably hydrogen, a halogen group, or a hydrocarbon group (having 1 to 5 or 1 to 4 carbon atoms), and more preferably hydrogen or a hydrocarbon group (having 1 to 5 or 1 to 4 carbon atoms). In formula (B), R 12 , R 13 is preferably hydrogen.

[0054] From the viewpoint of easily obtaining a cured film with excellent low dielectric tangent characteristics, the cyclic conjugated diene compound is a compound represented by the formula (A), in which X is a group represented by -O-, and R 12 and R 13 is preferably hydrogen. In other words, the cyclic conjugated diene compound is preferably a furan compound represented by the following formula (A1).

[0055] [ka] In formula (A1), R 11 , R 14 are each independently hydrogen, a halogen group, or a hydrocarbon group having 1 to 5 carbon atoms (preferably 1 to 4 carbon atoms) which may or may not have a heteroatom (for example, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a halogen atom, preferably an oxygen atom), and are preferably hydrogen or a hydrocarbon group having 1 to 5 carbon atoms (preferably 1 to 4 carbon atoms).

[0056] Examples of the compound represented by formula (A1) include furan, 2-methylfuran, 2-ethylfuran, 2-propylfuran, 2-butylfuran, 2-pentylfuran, 2,5-dimethylfuran, etc. Furan compounds also include furan compounds having an ester bond such as furfuryl acetate.

[0057] When the cyclic conjugated diene compound is a furan compound, it is preferable that the furan compound has an alkyl group. In the formula (A), X has a group represented by -O-, and R 11 , R 12 , R 13 , R 14 and wherein at least one of the groups is an alkyl group. By using a furan compound having an alkyl group as the cyclic conjugated diene compound, the boiling point of the cyclic conjugated diene compound is appropriately increased, and the effect of reducing the viscosity of the curable resin composition described below is easily maintained even at high temperatures. In addition, air bubbles generated by the rapid evaporation of the cyclic conjugated diene compound during curing are appropriately suppressed, making it easy to increase the mechanical strength of the obtained cured film.

[0058] From the same viewpoint, the conjugated ene compound preferably has a boiling point of 50° C. or more, 60° C. or more, or 80° C. or more. The upper limit of the boiling point of the conjugated ene compound depends on the curing conditions, but is, for example, 200° C. or less, or 180° C. or less, from the viewpoint of sufficiently drying and removing the conjugated ene compound during curing.

[0059] The conjugated ene compound may have a polycyclic structure such as anthracene.

[0060] The conjugated ene compounds can be used alone or in combination of two or more kinds.

[0061] The curable resin composition according to the present disclosure can reduce its viscosity when heated by containing the latent crosslinking agent. The mechanism behind this is not clear, but is presumed to be as follows.

[0062] The latent crosslinking agent composed of a maleimide compound and a conjugated ene compound can be controlled in its activated and inactivated states by the Diels-Alder reaction and its reverse reaction, the retro Diels-Alder reaction. More specifically, when the latent crosslinking agent according to the present disclosure is used, during storage of the curable resin composition (low temperature state), the maleimide group of the maleimide compound is blocked (modified) by the conjugated ene compound that has undergone the Diels-Alder reaction, and the function of the maleimide compound as a crosslinking agent is inactivated. On the other hand, during heating of the curable resin composition, the conjugated ene compound, which is a blocking agent, is dissociated from the latent crosslinking agent by the retro Diels-Alder reaction, and the maleimide group of the maleimide compound is restored, and the function of the maleimide compound as a crosslinking agent is activated. Furthermore, the dissociated conjugated ene compound functions as a solvent in the curable resin composition, contributing to a lower viscosity of the curable resin composition. The time when the curable resin composition is heated refers to, for example, when laminating the dry film (for example, at 140° C.) or when curing the curable resin composition (for example, at 200° C.).

[0063] Here, the conjugated ene compound preferably has a melting point of 100°C or less, 90°C or less, or 80°C or less. When the melting point of the conjugated ene compound as the blocking agent is set to 100°C or less, the blocking agent dissociated from the latent crosslinking agent is likely to exist as a solvent for a sufficient period of time at any timing during heating such as lamination of the dry film (e.g., 140°C, etc.) or curing of the curable resin composition (e.g., 200°C), and the like, so that the effect of reducing the viscosity of the curable resin composition can be significantly enhanced. Therefore, when a resin layer made of the curable resin composition is formed on a substrate, a curable resin composition having excellent embedding properties of the curable resin composition and the resin layer into the substrate can be obtained.

[0064] Furthermore, when the conjugated ene compound dissociated by the retro Diels-Alder reaction is cooled to, for example, 80°C or less, it can again undergo a Diels-Alder reaction with the maleimide compound and function as a blocking agent. Therefore, it is possible to inactivate the maleimide compound that has been activated once, and the storage stability is likely to be excellent even after lamination of the dry film. Furthermore, the conjugated ene compound that functions as a solvent during heating may lose its function as a solvent after cooling by reacting with the maleimide compound. Therefore, even if the conjugated ene compound dissociated during lamination is not sufficiently removed by drying or the like, it is possible to make the viscosity high at low temperatures, and the tackiness of the resin layer is likely to be excellent.

[0065] In particular, when a dry film is formed using the curable resin composition of the present disclosure, the crosslinking agent is blocked, thereby improving storage stability, and the components that can dissociate as a solvent are held as solids, so that workability is less likely to be hindered, and since the blocking agent can be dissociated as a solvent when heated (when curing or laminating), the softness / flexibility of the dry film is improved, and the adhesion to and embeddability with the substrate can be improved. Thus, the dry film obtained using the curable resin composition of the present disclosure is a dry film with a new concept.

[0066] In addition, since the dissociation temperature of the conjugated ene compound can vary depending on the compound used, the heating temperature (curing temperature or lamination temperature) may be adjusted depending on the conjugated ene compound used. As an example, the temperature at which a typical furan compound dissociates from a latent crosslinking agent is about 100°C. Therefore, when a latent crosslinking agent blocked with a furan compound is used, the curing temperature or the lamination temperature of the dry film can be set to more than 100°C to remove the furan compound.

[0067] <<How to manufacture latent crosslinking agents>> A latent crosslinking agent can be produced by reacting a maleimide group of a maleimide compound with a blocking agent according to a conventionally known method. More specifically, a latent crosslinking agent can be produced by heating a maleimide compound and a conjugated ene compound in a solvent at a temperature that takes into consideration the Diels-Alder reaction.

[0068] Regarding the mixing ratio of the maleimide compound and the conjugated ene compound, the amount of the conjugated ene compound may be adjusted so that the maleimide group reacts sufficiently.

[0069] <<Latent crosslinker content>> The content of the latent crosslinking agent in the curable resin composition is not particularly limited, and for example, the amount of the latent crosslinking agent equivalent to the blocking agent relative to 100 parts by mass of the total solid content of the curable resin composition is preferably 0.1 parts by mass or more, 1 part by mass or more, or 3 parts by mass or more, and is preferably 200 parts by mass or less, 100 parts by mass or less, 50 parts by mass or less, or 30 parts by mass or less. Also, for example, the crosslinking agent equivalent amount of the latent crosslinking agent relative to 100 parts by mass of the curable resin in the curable resin composition is preferably 1 part by mass or more, 5 parts by mass or more, 10 parts by mass or more, or 20 parts by mass or more, and is preferably 200 parts by mass or less, 150 parts by mass or less, 100 parts by mass or less, or 80 parts by mass or less. When the curable resin composition of the present disclosure further contains a crosslinking agent different from the latent crosslinking agent, it is preferable that the total content of the crosslinking agent equivalent amount of the latent crosslinking agent and the crosslinking agent is within the above range. In addition, in the present disclosure, the crosslinking agent component of the latent crosslinking agent is treated as a solid content, and the blocking agent component is treated as a solvent component.

[0070] <<<Curing resin>>> The curable resin is not particularly limited as long as it is a resin having a curable reactive group (e.g., a functional group containing an unsaturated double bond, an epoxy group, a thiol group, an amino group, etc.) capable of undergoing a crosslinking reaction with the above-mentioned crosslinking agent (maleimide compound). In other words, a resin component having such a curable reactive group is defined as a curable resin.

[0071] As the curable resin, it is preferable to use an epoxy resin, a curable polyphenylene ether resin (thermosetting polyphenylene ether resin), a maleimide resin different from the latent crosslinking agent, or the like.

[0072] <<Curable polyphenylene ether resin>> The curable polyphenylene ether resin is not particularly limited, and any conventionally known resin may be used. The curable polyphenylene ether preferably has a functional group containing an unsaturated double bond as a curable reactive group.

[0073] The curable polyphenylene ether resin may be a polyphenylene ether having a linear structure, or a polyphenylene ether having a branched structure.

[0074] Hereinafter, 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."

[0075] Hereinafter, 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.

[0076] Hereinafter, when simply expressed as "ortho position" or the like, it means "at least one of the ortho positions", etc. Therefore, unless there is any particular contradiction, 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.

[0077] Examples of the raw material phenols for polyphenylene ether include phenols that satisfy the following condition 1.

[0078] (Condition 1) Contains hydrogen atoms at the ortho and para positions

[0079] Phenols satisfying condition 1 also have a hydrogen atom at the ortho position. Therefore, when they are oxidatively polymerized with phenols, ether bonds can be formed not only at the ipso and para positions but also at the ortho position. Therefore, polyphenylene ether obtained by using such phenols as raw material phenols can form a branched chain structure. More specifically, a polyphenylene ether obtained from a phenol satisfying condition 1 has a structure in which a part of the structure is branched by benzene rings ether-bonded at least at three positions, i.e., the ipso position, the ortho position, and the para position. Such polyphenylene ether having a branched structure in the skeleton is sometimes called a “branched polyphenylene ether.” The branched polyphenylene ether has excellent solubility in organic solvents.

[0080] By using, as the raw material phenols, phenols that satisfy at least condition 1, it is possible to synthesize polyphenylene ether having a branched structure. On the other hand, by not using phenols that satisfy at least condition 1, it is possible to synthesize polyphenylene ether having a linear structure.

[0081] Furthermore, by including a phenol as a raw material for polyphenylene ether that satisfies the following condition 2, polyphenylene ether having a functional group containing an unsaturated carbon bond, which is one of the curable reactive groups, can be synthesized.

[0082] (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0083] Furthermore, since the phenols satisfying the condition 2 have a functional group containing an unsaturated carbon bond, the polyphenylene ether obtained by using such a phenol as the raw material phenol has a functional group containing an ethylenic or acetylenic carbon-carbon multiple bond. More specifically, a polyphenylene ether obtained from a phenol satisfying condition 2 has, as a part of its structure, a functional group containing an unsaturated carbon bond at least at the meta position or at either of two ortho positions of the benzene ring.

[0084] The functional group containing an unsaturated carbon bond is not particularly limited, but from the viewpoint of excellent curability, a vinyl group, an allyl group, or a (meth)acryloyl group is preferable. From the viewpoint of excellent low dielectric properties, the functional group containing an unsaturated carbon bond is preferably a hydrocarbon group containing an unsaturated carbon bond, and more preferably an allyl group.

[0085] When polyphenylene ether is synthesized using phenols satisfying at least condition 1, the phenols satisfying at least condition 1 may be either (1) phenols satisfying only condition 1 and not condition 2, or (2) phenols satisfying both conditions 1 and 2, and the raw material phenols may contain both of these phenols.

[0086] Examples of phenols that satisfy only condition 1 but not condition 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. As phenols that satisfy condition 1, only one type may be used, or two or more types may be used.

[0087] Examples of phenols satisfying both the condition 1 and the condition 2 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. As the phenols satisfying the condition 1 and the condition 2, only one kind may be used, or two or more kinds may be used.

[0088] In the synthesis of polyphenylene ether, when phenols satisfying at least condition 1 are used, the content of the phenols satisfying at least condition 1 relative to the total amount of raw material phenols is preferably 1 mol% or more, 2 mol% or more, 3 mol% or more, or 5 mol% or more, and is preferably 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, or 15 mol% or less.

[0089] In the synthesis of polyphenylene ether, the content of phenols satisfying at least condition 2 relative to the total amount of raw material phenols is preferably 1 mol% or more, 5 mol% or more, or 10 mol% or less, and is preferably 99 mol% or less, 95 mol% or less, or 90 mol% or less.

[0090] Although monohydric phenols are mainly disclosed as the raw material phenols shown here, polyhydric phenols may be used as the raw material phenols as long as they do not impair the effects of the present disclosure.

[0091] Such polyphenylene ether can be produced by a known polyphenylene ether synthesis method, except that the raw material phenols and the ratio of the raw material phenols used are as described above. For example, it can be produced by the synthesis method disclosed in International Publication WO2020 / 017570.

[0092] <<Epoxy resin>> The epoxy resin is not particularly limited, and any conventionally known epoxy resin can be used. Examples of epoxy resins include bisphenol type epoxy resins (bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol E type epoxy resins, bisphenol M type epoxy resins, bisphenol P type epoxy resins, bisphenol Z type epoxy resins, etc.), novolac type epoxy resins (bisphenol A novolac type epoxy resins, phenol novolac type epoxy resins, cresol novolac epoxy resins, etc.), biphenyl type epoxy resins, biphenyl novolac type epoxy resins, biphenyl aralkyl type epoxy resins, aryl alkylene type epoxy resins, tetraphenylol ethane type epoxy resins, naphthalene type epoxy resins, etc. Examples of the epoxy resin include epoxy resins such as benzene-type epoxy resins, anthracene-type epoxy resins, phenoxy-type epoxy resins, dicyclopentadiene-type epoxy resins, norbornene-type epoxy resins, trihydroxyphenylmethane-type epoxy resins, hydantoin-type epoxy resins, tetraphenylolethane-type epoxy resins, brominated epoxy resins, glycidylamine-type epoxy resins, alicyclic epoxy resins, diglycidyl phthalate resins, tetraglycidyl xylenoylethane resins, glycidyl methacrylate copolymer epoxy resins, copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, epoxy-modified polybutadiene rubber derivatives, and CTBN-modified epoxy resins. The epoxy resins may be used alone or in combination of two or more.

[0093] The epoxy resin is preferably a bisphenol type epoxy resin, a novolac type epoxy resin, a biphenyl type epoxy resin, or a biphenyl novolac type epoxy resin.

[0094] <<Maleimide resin>> The maleimide resin is not particularly limited, and any maleimide compound that can be used in the latent crosslinking agent described above can be used. In the present disclosure, the maleimide resin differs from the latent crosslinking agent in that it is not protected with a blocking agent.

[0095] <<Content of hardening resin>> The content of the curable resin in the curable resin composition is not particularly limited, but is preferably 10 to 90 mass %, and more preferably 20 to 80 mass %, based on the total solid content of the curable resin composition excluding the filler.

[0096] <<<Other ingredients>>> Examples of other components include fillers, peroxides, polymerization initiators, resins and polymer components such as styrene-based elastomers, crosslinking agents other than latent crosslinking agents, sensitizers, adhesive assistants, surfactants, leveling agents, plasticizers, adhesion agents, colorants, fibers, silane coupling agents, flame retardants, cellulose nanofibers, dispersants, thermosetting catalysts, thickeners, defoamers, antioxidants, rust inhibitors, and adhesion-imparting agents. The curable resin composition may also contain a catalyst or the like according to the type of curable resin (or the type of curable reactive group of the curable resin), etc.

[0097] The other components may be appropriately selected depending on the application, etc.

[0098] Peroxides include methyl ethyl ketone peroxide, methyl acetoacetate peroxide, acetylacetonate peroxide, 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 the peroxide 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. Only one type of peroxide may be used, or two or more types may be used.

[0099] Examples of the filler include inorganic fillers and organic fillers. Examples of inorganic fillers that can be used include metal oxides such as silica, alumina, and titanium oxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; clay minerals such as talc and mica; fillers having a ferovskite crystal structure such as barium titanate and strontium titanate; boron nitride, aluminum borate, barium sulfate, and calcium carbonate. Examples of organic fillers that can be used include fluororesin fillers such as polytetrafluoroethylene (PTFE), tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF); and hydrocarbon resin fillers such as cycloolefin polymer (COP) and cycloolefin copolymer (COC).

[0100] The curable resin composition may be in the form of a varnish containing a solvent. The solvent can be appropriately selected according to the type of curable resin, and is not particularly limited. Examples of the solvent include chloroform, methylene chloride, toluene, 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.

[0101] <<<<Dry film, prepreg>>>> The dry film has a resin layer made of the curable resin composition of the present disclosure on a carrier film (support film). The dry film is used by laminating the resin layer so as to be in contact with a substrate.

[0102] The dry film can be produced by uniformly applying the curable resin composition onto a carrier film (support film) by an appropriate method such as a blade coater, lip coater, comma coater, or film coater, drying the composition to form the above-mentioned resin layer, and preferably laminating a cover film (protective film) thereon. The cover film and the carrier film may be made of the same film material or different films.

[0103] The film materials for the carrier film and the cover film may be any of those known to be used for dry films.

[0104] As the carrier film, for example, a thermoplastic film such as a polyester film, eg, polyethylene terephthalate, having a thickness of 2 to 150 μm is used.

[0105] The cover film may be a polyethylene film, a polypropylene film, or the like, but it is preferable that the adhesive strength with the resin layer is smaller than that of the carrier film.

[0106] The thickness of the resin layer on the dry film is preferably 100 μm or less, and more preferably in the range of 5 to 50 μm.

[0107] As described above, the dry film according to the present disclosure is easily made low-viscosity by the blocking agent (e.g., furan compound) dissociated from the latent crosslinking agent when heated. As a result, the dry film is easily conformable to the substrate while maintaining its shape, and the adhesion between the obtained cured product and the substrate can be improved.

[0108] The prepreg can be obtained, for example, by impregnating a substrate such as a glass cloth with a curable resin composition and drying it.

[0109] <<<<Cured product>>>> A cured product can be produced by using the curable resin composition or a dry film having a resin layer made of the curable resin composition.

[0110] The method for obtaining a cured product from the curable resin composition is not particularly limited, and can be appropriately changed depending on the composition of the curable resin composition.

[0111] For example, the cured product can be formed by the following method. After the curable resin composition is applied (for example, applied by an applicator or the like) onto the substrate as described above, a drying step is carried out as necessary to dry the curable resin composition to form a resin layer on the substrate, or a dry film is laminated onto the substrate to transfer the resin layer made of the curable resin composition. Next, a thermal curing step is carried out in which the curable resin is thermally cured by heating (for example, heating with an inert gas oven, a hot plate, a vacuum oven, a vacuum press machine, or the like), thereby curing the resin layer.

[0112] The conditions for carrying out 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 resin composition.

[0113] <<<<Electronic Components>>>> The electronic component has the cured product of the present disclosure. The cured product of the present disclosure can be used for various purposes including as a material for constituting electronic components.

[0114] Its applications are not particularly limited, but preferred examples include insulating materials in electronic components such as large-capacity, high-speed communications typified by the fifth-generation communication system (5G) and millimeter-wave radars for automotive ADAS (advanced driving systems). EXAMPLES

[0115] <<<Raw materials>>> (curable resin) Polyphenylene Ether (PPE) Details will be provided below. Epoxy resin Biphenyl novolac epoxy resin Product name: NC3000H CA75 (manufactured by Nippon Kayaku Co., Ltd.) Maleimide resin Product name: BMI-6000 (manufactured by Daiwa Kasei Kogyo Co., Ltd.) (crosslinking component) Latent crosslinkers 1-6 Details will be provided below. Crosslinking agent 1 [Bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane Product name: BMI-70 (manufactured by K.I. Kasei Co., Ltd.) Hereafter, this will be referred to as "BMI-70." Crosslinking agent 2 Triallyl isocyanurate Product name: TAIC (Mitsubishi Chemical) (Other ingredients) Elastomer Hydrogenated styrene-based thermoplastic elastomer Product name: H1051 (Asahi Kasei Corporation) Dispersants Additive-based A mixture of BYK (registered trademark)-1791 (manufactured by BYK Japan, surfactant), BYK (registered trademark)-352 (manufactured by BYK Japan, surfactant), and Polyflow No. 90 (manufactured by Kyoeisha Chemical Co., Ltd., surfactant) in a mass ratio of 4:2:1. Filler silica Product name: SC2050-HNF (Admatechs) Peroxide Product name: Perbutyl P (manufactured by NOF Corporation) ·catalyst Imidazole Product name: 2E4MZ (Tokyo Chemical Industry Co., Ltd.)

[0116] In this embodiment, the crosslinking agent and the latent crosslinking agent are collectively referred to as the crosslinking component.

[0117] <<Synthesis of latent crosslinkers 1-4>> As shown in formula 1, about 10 g of a maleimide compound [bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane (manufactured by K.I. Chemicals Co., Ltd., product name: BMI-70)] was added to 50 ml of toluene, and 4 to 6 equivalents of a furan compound [(furan, 2,5-dimethylfuran, 2-butylfuran or furfuryl acetate)] was added, followed by heating at 80°C for 24 hours. The solvent and the furan compound were then removed by distillation under reduced pressure to obtain latent crosslinker 1 (BMI70-Fu), latent crosslinker 2 (BMI70-DMFu), latent crosslinker 3 (BMI70-BuFu), and latent crosslinker 4 (BMI70-FuAc), as shown in Formula 1.

[0118] formula 1 TIFF2025059604000009.tif72170

[0119] Latent crosslinking agents 1-4, and the maleimide compounds and furan compounds which are the raw materials for each latent crosslinking agent, 1 The H-NMR (DMSO-d6, room temperature) spectra are shown in Figures 1-4, respectively.

[0120] In addition, thermogravimetric analysis was performed on the maleimide compound (BMI-70), latent crosslinker 1 (BMI70-Fu), latent crosslinker 2 (BMI70-DMFu), latent crosslinker 3 (BMI70-BuFu), and latent crosslinker (BMI70-FuAc). The measurement results are shown in FIG. 5. As shown in FIG. 5, for latent crosslinkers 1 to 4, weight loss associated with dissociation and volatilization of the furan compound was observed from around 100°C, which is the assumed drying temperature of the resin composition, and it was confirmed that the furan compound was sufficiently generated and could function as a solvent even at 140°C, which is the assumed lamination temperature of the dry film. In addition, it was confirmed that the dissociated furan compound was sufficiently volatilized around 200°C, which is the assumed curing temperature of the resin composition, and it is considered that the furan compound is removed by drying during curing and does not remain in the cured product. The percentages shown in Figure 5 represent the weight loss of the maleimide compound or each latent crosslinking agent at 300°C. It is believed that each latent crosslinking agent can dissociate and volatilize almost the entire amount of the furan compound by sufficiently heating it at 200°C or higher.

[0121] <<Synthesis of latent crosslinker 5>> 10 g of a maleimide compound [product name: MIR-3000 (manufactured by Nippon Kayaku Co., Ltd., compound represented by formula (X5)), MEK / toluene mixed solution with a solid content concentration of 70 mass%] was added to 12 g of toluene, and 9.0 g of a furan compound [(2-butylfuran)] was added, followed by heating at 80°C for 24 hours. The solvent and the furan compound were then removed by distillation under reduced pressure to obtain latent crosslinker 5 (MIR3000-BuFu).

[0122] <<Synthesis of latent crosslinker 6>> 10 g of a maleimide compound [product name: SLK-6895 (manufactured by Shin-Etsu Chemical Co., Ltd., a mixture of 90 mass % of the compound represented by formula (X3) and 10 mass % of MEK)] was added to 8.3 g of toluene, and 9.7 g of a furan compound [(2-butylfuran)] was added, followed by heating at 80° C. for 24 hours. The solvent and the furan compound were then removed by distillation under reduced pressure to obtain latent crosslinker 6 (SLK6895-BuFu).

[0123] <<Synthesis of Polyphenylene Ether: PPE>> In a 500 mL separable flask, 19.8 g of 2,6-dimethylphenol and 2.42 g of 2-allylphenol were added, and the resulting mixture was dissolved in 261 g of toluene. Furthermore, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) was adjusted to 0.18 wt% and tetramethylethylenediamine (TMEDA) to 0.16 wt%, and the reaction solution was stirred at a stirring speed of 200 rpm using a four-blade paddle blade while blowing dry air into the reaction solution at a flow rate of 75 mL / min, and reacted at 40°C for a predetermined time to obtain a reaction solution containing polyphenylene ether. After stopping heating the reaction solution and blowing in dry air, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) was removed by filtration, reprecipitated in a mixture of 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, and 7.0 mL of H2O2, filtered under reduced pressure, washed with methanol, and dried at 80°C for 24 hours to obtain a branched polyphenylene ether. The number average molecular weight of the obtained branched polyphenylene ether was 13,000 and the weight average molecular weight was 45,000. This branched polyphenylene ether is called PPE.

[0124] <<<Curable resin composition>>> <<First curable resin composition: Polyphenylene ether-containing system>> The PPE, crosslinking component, elastomer, dispersant, filler, and peroxide were added to a solvent (cyclohexane) in the ratios shown in Table 1 to prepare the curable resin compositions according to Examples 1-4 and Comparative Examples 1-2.

[0125] [Table 1]

[0126] In each of the Examples and Comparative Examples, the solid content ratios of the components were adjusted to be equal. In Table 1, the solid content ratio of the latent crosslinking agent is calculated as the amount of the crosslinking agent after the blocking agent is dissociated, taking the amount of the crosslinking agent as the solid content.

[0127] <<Evaluation of the first curable resin composition>> <Melt viscosity> The melt viscosity of each curable resin composition was measured according to the following method. The evaluation results are shown in Table 2.

[0128] (Measurement method) The curable resin composition of each Example and Comparative Example was applied and dried on a PET film so that the film thickness after drying was 25 μm, and 20 dry films each having a resin layer made of the curable resin composition were obtained. Using a vacuum laminator MVLP-500 manufactured by Meiki Seisakusho, dry films having the same resin layer were laminated so that the resin layers were in contact with each other, and the PET film was peeled off repeatedly to prepare a test piece for melt viscosity measurement having a resin layer thickness of 500 μm. Using this test piece, the melt viscosity was measured using a HAAKE rheometer (MARS 40) under the following conditions: oscillation heating method (5°C / min.), measurement temperature range: 70 to 200°C, frequency: 1Hz, strain control: 2%, compression stress: 2.5N hold, parallel plates: 20mm, initial gap: 450μm, thermogap application: G"<1000Pa, sample size: 2.5 x 2.5cm. For each curable resin composition, the temperature at which the viscosity was lowest in the temperature range of 70 to 200°C and the viscosity at that time, as well as the viscosity at specific temperatures (100°C, 120°C, 140°C) are shown in Table 2.

[0129] [Table 2]

[0130] As shown in Table 2, the curable resin compositions according to Examples 1 to 4 achieved a low viscosity when heated (melted) by using a predetermined latent crosslinking agent.

[0131] <Dielectric properties> For Comparative Example 2 and Examples 1 to 4, Df was measured according to the following method. The cured product obtained using the curable resin composition of Comparative Example 2 had a Df of 0.0082. The cured product obtained using the curable resin composition of Example 1 had a Df of 0.0052. The cured product obtained using the curable resin composition of Example 2 had a Df of 0.0052. The cured product obtained using the curable resin composition of Example 3 had a Df of 0.0023. The cured product obtained using the curable resin composition of Example 4 had a Df of 0.0045. In this way, it was confirmed that the use of a specific latent crosslinking agent reduced Df.

[0132] (Measurement method) Each curable resin composition was applied to the glossy surface of a 18 μm thick copper foil with an applicator so that the film thickness after drying was 40 μm, and then dried in a hot air circulation drying oven at 90° C. for 5 minutes. Then, after curing in an inert oven at 200° C. for 1 hour, the copper foil was etched to obtain a cured product (cured film) made of each composition. The prepared cured film was cut into a length of 80 mm and a width of 45 mm to be used as a test piece, and the dielectric loss tangent Df was measured by the SPDR (Split Post Dielectric Resonator) resonator method. The measuring equipment used was a vector network analyzer E5071C manufactured by Keysight Technologies, LLC, 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.

[0133] <<Second curable resin composition: latent crosslinking agent change>> The PPE, crosslinking component, elastomer, dispersant, filler, and peroxide were added to a solvent (cyclohexane, etc.) in the proportions shown in Table 3 to prepare the curable resin compositions of Examples 5 and 6 and Comparative Examples 3 and 4.

[0134] [Table 3] In each of the Examples and Comparative Examples, the solid content ratios of the components were adjusted to be equal. In Table 3, the solid content ratio of the latent crosslinking agent is calculated as the amount of the crosslinking agent after the blocking agent is dissociated, taking the amount of the crosslinking agent as the solid content.

[0135] <<Evaluation of the second curable resin composition>> <Melt viscosity> For each of the curable resin compositions, a dry film was prepared in the same manner as described above, and then the melt viscosity was measured. The evaluation results are shown in Table 4.

[0136] [Table 4]

[0137] As shown in Table 4, the curable resin compositions according to Examples 5 and 6 achieved a low viscosity when heated (melted) by using a predetermined latent crosslinking agent.

[0138] <Dielectric properties> For Comparative Example 3, Comparative Example 4, Example 5, and Example 6, the Df of the resulting cured products was measured in the same manner as described above. The cured product obtained using the curable resin composition of Comparative Example 3 had a Df of 0.0082. The cured product obtained using the curable resin composition of Comparative Example 4 had a Df of 0.0019. The cured product obtained using the curable resin composition of Example 5 had a Df of 0.0035. The cured product obtained using the curable resin composition of Example 6 had a Df of 0.0020. A comparison between Comparative Example 3 and Example 5 confirmed that the use of a specific latent crosslinking agent resulted in a decrease in Df. A comparison between Comparative Example 4 and Example 6 confirmed that the use of a specific latent crosslinking agent allowed the excellent low dielectric tangent characteristic of the cured product of Comparative Example 4 to be maintained in Example 6 as well. Thus, it was confirmed that the use of a specific latent crosslinking agent resulted in excellent low dielectric tangent characteristics.

[0139] <<Third curable resin composition: epoxy-containing system>> Curable resins [epoxy resin (NC3000H CA75) and maleimide resin (BMI-6000)], crosslinking components, dispersants, fillers, and catalysts were added to a solvent (cyclohexane) in the proportions shown in Table 5 to prepare curable resin compositions.

[0140] [Table 5] In each of the Examples and Comparative Examples, the solid content ratios of the components were adjusted to be equal. In Table 5, the solid content ratio of the latent crosslinking agent is calculated as the amount of the crosslinking agent after the blocking agent is dissociated, taking the amount of the crosslinking agent as the solid content.

[0141] <<Evaluation of the second curable resin composition>>> <Melt viscosity> For each of the curable resin compositions, a dry film was prepared in the same manner as described above, and then the melt viscosity was measured. The evaluation results are shown in Table 6.

[0142] [Table 6]

[0143] As shown in Table 6, the curable resin composition according to Example 7 achieved a low viscosity when heated (melted) by using a predetermined latent crosslinking agent.

[0144] <Dielectric properties> For each curable resin composition, Df of the resulting cured product was measured in the same manner as described above. The cured product obtained using the curable resin composition of Comparative Example 5 had a Df of 0.0116. The cured product obtained using the curable resin composition of Example 7 had a Df of 0.0107. In this way, it was confirmed that the use of a specific latent hardener reduced Df.

Claims

1. A curable resin composition comprising a curable resin and a latent crosslinking agent, the latent crosslinking agent is a maleimide compound protected with a blocking agent, The curable resin composition, wherein the blocking agent is a conjugated ene compound having a melting point of 100° C. or less.

2. The curable resin composition according to claim 1 , wherein the blocking agent is a furan compound.

3. The curable resin composition according to claim 2 , wherein the furan compound has an alkyl group.

4. The curable resin composition according to claim 1 , wherein the curable resin is at least one selected from the group consisting of an epoxy resin, a curable polyphenylene ether resin, and a maleimide resin different from the latent crosslinking agent.

5. A dry film having a resin layer obtained by applying the curable resin composition according to any one of claims 1 to 4 to a film and drying it.

6. A cured product of the curable resin composition according to any one of claims 1 to 4.

7. An electronic component comprising the cured product according to claim 6.

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