Curable resin compositions, dry films, prepregs, cured products, laminates, and electronic components

Abstract

To provide a curable resin composition, a cured product of which has low dielectric constants and low dielectric loss tangents.SOLUTION: A curable resin composition includes: an episulfide resin; and at least one curing agent selected from the group consisting of a maleimide compound, a benzoxazine compound and a carbodiimide compound.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, mobile communication devices compatible with the fifth generation mobile communication system (5G) have appeared, and Development has begun with an eye on the next generation. In mobile communication devices and the like, the use of high-frequency (GHz order) electrical signals is increasing in order to transmit and process large volumes of information at high speed. High-frequency signals are prone to attenuation, so materials used are required to be designed to suppress transmission loss.

[0003] Against this background, development of materials having low dielectric constants and low dielectric loss tangents that enable reduction of transmission loss is underway.

[0004] Conventionally, epoxy resins have been used as materials having low dielectric constants and low dielectric loss tangents, but for example, Patent Document 1 proposes a resin material using an episulfide resin. The resin material in Patent Document 1 contains an episulfide resin, a curing agent, and an inorganic filler, and the curing agent is an active ester compound or a cyanate ester compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-60553 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the resin material of Patent Document 1 requires an active ester compound or a cyanate ester compound, and further an inorganic filler, and there is still a demand for a resin material that does not require these and that achieves a low dielectric constant and a low dielectric loss tangent in a highly cured product.

[0007] An object of the present invention is to provide a resin material that, when cured, has a low dielectric constant and a low dielectric loss tangent. [Means for solving the problem]

[0008] The present inventors have found that a curable resin composition comprising an episulfide resin in combination with one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds can provide a cured product having a low dielectric constant and a low dielectric loss tangent, and have completed the present invention. In these resin compositions, for example, the thiirane group and maleimide group form a carbon-sulfur bond in a curing reaction, thereby providing flexibility (elongation), and an excellent cured product can be obtained due to its low dielectric constant; the thiirane group and benzoxazine group form a cured product with excellent low thermal expansion properties, due to the promotion of ring-opening of the benzoxazine group by the acidity of the thiol generated by the ring-opening of the thiirane group, and the promotion of ring-opening of the thiirane group by the hydroxyl group generated by the ring-opening of the benzoxazine group; and the thiirane group and carbodiimide group form an imidazolidinethione ring bond in a curing reaction, resulting in a cured product with excellent low thermal expansion and heat resistance.

[0009] The gist of the present invention is as follows. [1] A curable resin composition comprising an episulfide resin and one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds. [2] The curable resin composition according to [1], wherein the ratio of the number of moles of functional groups in the curing agent to the number of moles of thiirane groups contained in the episulfide resin is 0.1 or more and 1.5 or less. [3] The curable resin composition according to [1] or [2], further comprising an inorganic filler. [4] A dry film comprising a substrate and a resin layer formed on the substrate, the resin layer being made of the curable resin composition according to any one of [1] to [3]. [5] A prepreg obtained by impregnating a substrate with the curable resin composition of any one of [1] to [3]. [6] A cured product obtained by curing the curable resin composition of any one of [1] to [3], the curable resin composition in the resin layer of the dry film of [4], or the curable resin composition in the prepreg of [5]. [7][6] A laminate containing the cured product. [8][6] An electronic component containing the cured product. [Effects of the Invention]

[0010] The curable resin composition of the present invention can provide a cured product having a low dielectric constant and a low dielectric loss tangent. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Curable resin composition> The curable resin composition of the present invention contains an episulfide resin and one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds.

[0012] [Episulfide resin] The episulfide resin is not particularly limited, and a resin having one or more thiirane groups can be used. From the viewpoints of good curability and mechanical strength of the cured product, the number of thiirane groups is preferably two or more, and more preferably two to four.

[0013] Examples of episulfide resins having two or more thiirane groups include bisphenol A episulfide resins, bisphenol F episulfide resins, bisphenol S episulfide resins, hydrogenated bisphenol A episulfide resins, hydrogenated bisphenol F episulfide resins, hydrogenated bisphenol S episulfide resins, dicyclopentadiene episulfide resins, biphenol episulfide resins, fluorene episulfide resins, episulfide resins having a triazine nucleus in the skeleton, naphthalene episulfide resins, anthracene episulfide resins, and naphthol aralkyl episulfide resins. Polyfunctional episulfide resins such as phenol novolac episulfide resins, biphenyl novolac episulfide resins, and phenol aralkyl episulfide resins may also be used. Aliphatic episulfide resins such as episulfide resins having a tricyclodecane skeleton and episulfide resins having an adamantane skeleton may also be used.

[0014] The episulfide resin is preferably an episulfide resin such as a bisphenol A type, a bisphenol F type, or a biphenyl type, or an episulfide resin having a hydrogenated (alicyclic) structure, and more preferably an episulfide resin having a hydrogenated (alicyclic) structure from the viewpoint of achieving lower dielectric properties.

[0015] The episulfide resins may be used alone or in combination of two or more kinds in any ratio.

[0016] The molecular weight of the episulfide resin can be 200 or more and 2,000 or less, and is preferably 350 or more from the viewpoint of safety, and is preferably 1,000 or less from the viewpoint of handling properties such as fluidity of the composition. Unless otherwise specified, the molecular weight in this specification means the number average molecular weight.

[0017] The episulfide equivalent of the episulfide resin (mass of resin per equivalent of episulfide group) can be from 100 to 1,000. It is preferably 500 or less because good reactivity can be obtained.

[0018] Episulfide resins can be easily obtained by converting the epoxy groups of epoxy resins to thiirane groups using a sulfurizing agent. Examples of sulfurizing agents include thiourea and potassium thiocyanate. To suppress the polymerization reaction caused by ring-opening of the thiirane groups, the reaction temperature is preferably 70°C or lower. From the viewpoint of reaction efficiency, the reaction temperature can be set to 40°C or higher.

[0019] [Hardening agent] The curing agent is selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds, and may be any one of maleimide compounds, benzoxazine compounds, and carbodiimide compounds, or a combination of two or all of these compounds in any ratio. Among these, maleimide compounds are preferred because they have excellent mechanical properties and a low dielectric constant, benzoxazine compounds are preferred because they provide good thermal dimensional stability, and carbodiimide compounds are preferred because they provide good thermal dimensional stability and high heat resistance.

[0020] (Maleimide compounds) The maleimide compound is not particularly limited, and a compound having one or more maleimide groups can be used. From the viewpoints of good curability and toughness of the cured product, the number of maleimide groups is preferably two or more, and more preferably two to four.

[0021] Examples of the maleimide compound include polyfunctional aliphatic maleimides and polyfunctional aromatic maleimides. The polyfunctional aliphatic maleimides include maleimides containing an alicyclic structure, and the aromatic ring in the polyfunctional aromatic maleimide may be a carbon ring or a heterocyclic ring.

[0022] Examples of polyfunctional aliphatic maleimides include isocyanurate-skeleton polymaleimides such as maleimide ester compounds having an isocyanurate skeleton obtained by dehydration esterification of tris(hydroxyethyl)isocyanurate and aliphatic maleimide carboxylic acid; isocyanurate-skeleton polymaleimides such as maleimide urethane compounds having an isocyanurate skeleton obtained by urethanization of tris(carbamatehexyl)isocyanurate and aliphatic maleimide alcohol; aliphatic polymaleimide ester compounds obtained by dehydration esterification of aliphatic maleimide carboxylic acid and various aliphatic polyols, or by transesterification of aliphatic maleimide carboxylic acid esters and various aliphatic polyols; aliphatic polymaleimide ester compounds obtained by ether ring-opening reaction of aliphatic maleimide carboxylic acid and various aliphatic polyepoxides; and aliphatic polymaleimide urethane compounds obtained by urethanization reaction of aliphatic maleimide alcohol and various aliphatic polyisocyanates.

[0023] Examples of polyfunctional aromatic maleimides include aromatic polymaleimide ester compounds obtained by dehydration esterification of maleimide carboxylic acid with various aromatic polyols or transesterification reaction of maleimide carboxylic acid ester with various aromatic polyols; aromatic polymaleimide ester compounds obtained by ether ring-opening reaction of maleimide carboxylic acid with various aromatic polyepoxides; and aromatic polymaleimide urethane compounds obtained by urethanization reaction of maleimide alcohol with various aromatic polyisocyanates.

[0024] The polyfunctional aliphatic maleimides and polyfunctional aromatic maleimides can include heterocycles, and specific examples thereof include maleimide group-containing imide compounds obtained by polymerizing tetracarboxylic acid dianhydrides (e.g., alicyclic tetracarboxylic acids, aromatic tetracarboxylic acid dianhydrides, etc.) and diamines (e.g., diamines having an aliphatic chain structure, aromatic diamines, etc.) and capping the terminal amines with maleic anhydride; and maleimide group-containing benzoxazole compounds obtained by polymerizing dicarboxylic acid derivatives and bis(o-aminophenol) and capping the terminal amines with maleic anhydride.

[0025] Of the maleimide compounds, those containing an alicyclic structure in the skeleton are preferred from the viewpoint of improving the low dielectric properties of the cured product, those containing an aliphatic chain in the skeleton are preferred from the viewpoint of increasing the toughness of the cured product, and those containing an aromatic ring or heterocycle, or a structure in which these are condensed, are preferred from the viewpoint of increasing the rigidity of the cured product.

[0026] The molecular weight of the maleimide compound may be from 300 to 8,000. From the viewpoint of flexibility of the cured product, it is preferably 1,000 or more.

[0027] The maleimide compound may have a maleimide equivalent (mass of the compound per equivalent of maleimide group) of 150 to 4000. From the viewpoint of toughness of the cured product, the maleimide equivalent is preferably 1000 or more.

[0028] These maleimide compounds may be synthesized by known methods, or commercially available products may be used. Commercially available products include, for example, BMI, BMI-70, and BMI-80 (manufactured by KI Chemical Industry Co., Ltd.), BMI-1000, BMI-1000H, BMI-1000S, BMI-1100, BMI-1100H, BMI-2000, BMI-2300, BMI-3000, BMI-3000H, BMI-4000, BMI-5100, BMI-7000, BMI-7000H, and BMI-TMH (all manufactured by Daiwa Chemical Industry Co., Ltd.), MIA-200 (manufactured by DIC Corporation), BMI-2500, BMI-3000J, BMI-6000, and BMI-6100 (manufactured by Designer Chemical Industry Co., Ltd.), and BMI-1000 (manufactured by Designer Chemical Industry Co., Ltd.). Examples of suitable ion exchangers include SLK-2600 (manufactured by Shin-Etsu Chemical Co., Ltd.), SLK-2600 (manufactured by Shin-Etsu Chemical Co., Ltd.), and MIR-3000-70MT (manufactured by Nippon Kayaku Co., Ltd.).

[0029] (benzoxazine compounds) The benzoxazine compound is not particularly limited, and a compound having one or more benzoxazine rings can be used. From the viewpoints of good curability and brittleness of the cured product, the number of benzoxazine rings is preferably two or more, and more preferably two to four.

[0030] As the benzoxazine compound, known benzoxazine compounds can be used, and examples thereof include Pd-type benzoxazine compounds, Fa-type benzoxazine compounds, ALP-d-type benzoxazine compounds, and T-ala-type benzoxazine compounds.

[0031] The benzoxazine compounds may be used alone or in combination of two or more kinds in any ratio.

[0032] The molecular weight of the benzoxazine compound can be 300 or more and 2,000 or less, and is preferably 300 or more and 1,000 or less.

[0033] The benzoxazine equivalent of the benzoxazine compound (the mass of the compound per equivalent of benzoxazine ring) can be from 150 to 1,000. The benzoxazine equivalent is preferably 500 or less, and more preferably 300 or less.

[0034] (Carbodiimide compounds) The carbodiimide compound is not particularly limited, and a compound containing two or more carbodiimide groups (-N=C=N-) can be used. From the viewpoint of good curability, the number of carbodiimide groups is preferably two or more, and more preferably 2 to 10.

[0035] The carbodiimide compound can be synthesized by a known method (for example, see JP 2019-38960 A). Specifically, it can be synthesized by condensation polymerization of diisocyanate.

[0036] Diisocyanates used in the synthesis of carbodiimide compounds include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Specific examples include aromatic diisocyanates such as 1,5-naphthylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and tetramethylxylylene diisocyanate; methylene diisocyanate; and Examples of the diisocyanate include aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; and alicyclic diisocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexane diisocyanate, 2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, and 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane. These diisocyanates may be used alone or in combination of two or more. Aromatic diisocyanates may be used as appropriate from the viewpoints of reactivity and heat resistance as a cured product, and aliphatic diisocyanates and alicyclic diisocyanates may be used as appropriate from the viewpoints of solubility in organic solvents, flexibility as a cured product, and low dielectric properties. In particular, the carbodiimide compound used in the present invention is preferably a compound obtained by condensation polymerization of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate in combination, as this provides a good balance of properties such as solubility in organic solvents, storage stability, reactivity, and heat resistance of the cured product.

[0037] The terminal isocyanate groups of the carbodiimide compound thus obtained are preferably capped with a compound having one functional group reactive with an isocyanate group, such as a monoisocyanate, a monoalcohol, a monoamine, or an acid anhydride.

[0038] Examples of monoisocyanates include lower alkyl isocyanates such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, n-, sec-, or tert-butyl isocyanate, alicyclic aliphatic isocyanates such as cyclohexyl isocyanate, and aromatic isocyanates such as phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, and 2,6-diisopropylphenyl isocyanate. Examples of the monoalcohol include methanol, ethanol, cyclohexanol, polyethylene glycol monomethyl ether, and polypropylene glycol monomethyl ether. Examples of the monoamine include primary amines such as butylamine and cyclohexylamine, and secondary amines such as diethylamine, dibutylamine and dicyclohexylamine. Examples of the acid anhydride include phthalic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, and benzoic anhydride. These may be used alone or in combination of two or more. Among them, from the viewpoint of reactivity, phenyl isocyanate and tolyl isocyanate are preferred, and phenyl isocyanate is more preferred.

[0039] The carbodiimide compounds may be used alone or in combination of two or more kinds in any ratio.

[0040] The molecular weight of the carbodiimide compound may be 500 or more and 8,000 or less, and from the viewpoint of good film-forming properties, it is preferably 1,000 or more, more preferably 1,400 or more, and from the viewpoint of compatibility in the composition, it is preferably 5,000 or less, more preferably 3,500 or less.

[0041] The carbodiimide equivalent of the carbodiimide compound (mass of the compound per equivalent of carbodiimide group) can be from 50 to 4,000. From the viewpoint of toughness of the cured product, it is preferably 100 or more, more preferably 130 or more, and from the viewpoint of good curability, it is preferably 1,000 or less, more preferably 500 or less, and even more preferably 260 or less.

[0042] [Amount] In the curable resin composition of the present invention, the ratio of the number of moles of functional groups in the curing agent to the number of moles of thiirane groups in the episulfide resin is preferably 0.1 or more and 1.5 or less. Within this range, the thiirane groups react with the functional groups in the curing agent in just the right amount, making it possible to simultaneously achieve excellent low dielectric properties, mechanical properties, and thermal properties. Here, the functional group of the curing agent is a maleimide group for a maleimide compound, a benzoxazine ring for a benzoxazine compound, or a carbodiimide group for a carbodiimide compound. Specifically, the ratio of the number of moles of maleimide groups in the maleimide compound to the number of moles of thiirane groups in the episulfide resin is more preferably 0.1 or more and 0.5 or less, since a cured product having excellent mechanical properties can be obtained; the ratio of the number of moles of benzoxazine rings in the benzoxazine compound to the number of moles of thiirane groups in the episulfide resin is more preferably 0.1 or more and 1.5 or less, since a cured product having excellent thermal properties can be obtained; and the ratio of the number of moles of carbodiimide groups in the carbodiimide compound to the number of moles of thiirane groups in the episulfide resin is more preferably 0.8 or more and 1.5 or less, since a cured product having excellent thermal properties can be obtained.

[0043] In the curable resin composition of the present invention, the total proportion of the episulfide resin and the one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds in the non-volatile components is preferably 30 mass% or more, and more preferably 40 mass% or more.

[0044] [Optional ingredients] The curable resin composition of the present invention can contain optional components in addition to the episulfide resin and one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds, within a range that does not impair the effects of the present invention.

[0045] (inorganic filler) In order to improve the thermal dimensional stability of the cured product, it is preferable to blend an inorganic filler. The inorganic filler is not particularly limited, and examples thereof include silica (fused silica, amorphous silica, crystalline silica, etc.), talc, barium sulfate, barium titanate, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, alumina, silicon nitride, boron nitride, and aluminum nitride. Among these, silica is preferred in terms of low thermal expansion and low dielectric loss tangent.

[0046] The average particle size of the inorganic filler can be 0.1 μm or more and 1.0 μm or less, and is preferably 0.3 μm or more from the viewpoint of reducing the dielectric constant. Here, the average particle size is a value measured by a laser analysis particle size distribution analyzer.

[0047] The inorganic filler may be surface-treated with a coupling agent, such as a silane coupling agent or a titanate coupling agent.

[0048] The content of the inorganic filler is not particularly limited, but in order to obtain a sufficient effect of the blending, it is preferably 40% by mass or more, more preferably 50% by mass or more, of the non-volatile components of the curable resin composition of the present invention, and is preferably 80% by mass or less, more preferably 75% by mass or less. When an inorganic filler is used, the inorganic filler may be used alone or in combination of two or more kinds in any ratio.

[0049] (curing accelerator) From the viewpoint of controlling the curing rate and the crosslinked structure of the cured product, it is preferable to add a curing accelerator. The curing accelerator is not particularly limited, and examples thereof include imidazole compounds, amine compounds, phosphorus compounds, organometallic complexes, and organometallic salts. Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole. Examples of the amine compound include dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine. Examples of phosphorus compounds include triphenylphosphine. Examples of organometallic complexes or salts include acetylacetonate complexes of cobalt, copper, zinc, iron, nickel, manganese, etc.

[0050] The content of the curing accelerator is not particularly limited, but in order to obtain a sufficient effect of the addition, it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and is preferably 1% by mass or less, more preferably 0.6% by mass or less, based on the solid content of the curable resin composition of the present invention. When a curing accelerator is used, the inorganic filler may be used alone or in combination of two or more kinds in any ratio.

[0051] (thermoplastic resin) The curable resin composition of the present invention may contain a thermoplastic resin for the purposes of film-forming properties, flexibility, adhesion, etc. Examples of the thermoplastic resin include a phenoxy resin, a polyvinyl acetal resin, and a thermoplastic elastomer. When a thermoplastic resin is used, the inorganic filler may be used alone or in combination of two or more kinds in any ratio.

[0052] (solvent) The curable resin composition of the present invention may contain a solvent to adjust the viscosity during application, etc. The solvent is not particularly limited, and an organic solvent is preferred. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, diethylene glycol ethyl ether acetate, and dipropylene glycol. Examples of suitable solvents include esters such as methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; and aprotic polar solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and acetonitrile. Ketones and esters are preferred in terms of solubility and volatility during curing. The solvent may be used alone or in combination of two or more kinds in any ratio.

[0053] (Other ingredients) The curable resin composition of the present invention may contain other components to the extent that the effects of the present invention are not impaired, such as conductive particles, colorants, wetting and dispersing agents, ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, antioxidants, antioxidants, antibacterial and antifungal agents, antifoaming agents, leveling agents, thickeners, adhesion-imparting agents, thixotropy-imparting agents, release agents, surface treatment agents, dispersants, dispersion aids, surface modifiers, stabilizers, and phosphors.

[0054] The curable resin composition of the present invention is thermosetting, but may be imparted with photosensitivity or photocurability by blending various components (e.g., compounds having an ethylenically unsaturated group such as photopolymerizable monomers and photopolymerizable oligomers; photosensitizers such as photopolymerization initiators, photoacid generators and photobase generators; photoinitiation assistants; sensitizers, etc.).

[0055] The curable resin composition of the present invention may contain, but preferably does not contain, a thermosetting resin other than an episulfide resin (e.g., an epoxy resin, an oxetane resin, etc.), and may contain, but preferably does not contain, a curing agent other than a maleimide compound, a benzoxazine compound, or a carbodiimide compound (e.g., an active ester compound, a cyanate ester compound, etc.).

[0056] [Manufacturing method] The curable resin composition of the present invention can be prepared by mixing an episulfide resin, one or more curing agents selected from the group consisting of maleimide compounds, benzoxazine compounds, and carbodiimide compounds, and optional components. From the viewpoint of coatability, the viscosity of the composition is preferably 100 mPa·s or more and 100,000 mPa·s or less. The viscosity can be adjusted by adding a solvent, which can be added in any amount considering compatibility with the components in the composition, coatability, and drying properties of the composition.

[0057] <Dry film> The curable resin composition of the present invention can be made into a dry film by applying it to a substrate and drying it to form a resin layer. Examples of the substrate include metal foil (for example, copper foil), carrier film, and the like. The carrier film is not particularly limited, and examples of films that can be used include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, and polystyrene films. The methods for application and drying are not particularly limited, and known methods can be used. A protective film may be laminated on the surface of the resin layer of the dry film, and examples of the protective film include polyester film, polyethylene film, and polypropylene film.

[0058] <Prepreg> The curable resin composition of the present invention can be impregnated into a substrate to form a prepreg. Examples of the substrate include glass cloth, glass nonwoven fabric, and aramid nonwoven fabric. After the substrate is impregnated with the curable resin composition, the substrate may be dried to form a semi-cured product.

[0059] <Cured product> A cured product can be obtained by curing the curable resin composition of the present invention, the resin layer of the dry film of the present invention, or the curable resin composition in the prepreg of the present invention. When using the curable resin composition of the present invention, a cured product can be obtained by applying the composition to a desired object, drying it, and heating it at a temperature of 160°C or higher and 280°C or lower. The heating time can be set appropriately, for example, 30 minutes or higher and 120 minutes or lower. When using the dry film of the present invention, a cured product of the resin layer can be obtained by laminating the dry film to a desired object and heating it at a temperature of 160°C or higher and 280°C or lower. The heating time can be set appropriately, for example, 40 minutes or higher and 90 minutes or lower.

[0060] <Laminate> The present invention also relates to a laminate comprising the cured product of the present invention. The laminate of the present invention can be produced using the prepreg of the present invention. For example, by stacking one or more prepregs of the present invention, and then stacking a metal foil such as copper foil on both sides or one side of the prepreg, and then heat-pressuring the laminate, a laminate having a metal foil on both sides or one side of the laminate and a cured product of the curable resin composition can be obtained.

[0061] <Electronic components> The present invention further relates to an electronic component comprising the cured product of the present invention. Examples of electronic components include printed wiring boards and inductors. Electronic components comprising the cured product of the present invention are preferably used as a cured film for solder resist, interlayer insulating material, coverlay, etc., or as a hole filler for through holes, via holes, etc. [Example]

[0062] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0063] The following ingredients were used: <Episulfide resin> Episulfide resin 1: TBIS-AHSP manufactured by Taoka Chemical Co., Ltd. Hydrogenated bisphenol A episulfide resin, episulfide equivalent weight 214 g / eq Episulfide resin 2: A bisphenol A type episulfide resin in which the epoxy groups of the following epoxy resin 2 have been converted to thiirane groups as follows. Episulfide equivalent: approximately 207 g / eq A solution of 2.1 g of thiourea dissolved in 42 mL of methanol in a 50 mL vial was added dropwise over 6 minutes at room temperature (approximately 25°C) to a 120 mL vial containing a solution of 2.9 g of epoxy resin 2 dissolved in 18 mL of tetrahydrofuran (THF), and the mixture was then heated to 50°C and maintained at that temperature for 2.5 hours. The mixture was then cooled to room temperature and allowed to stand for 24 hours. The resulting reaction mixture was transferred to a 200 mL flask with 10 mL of methanol and concentrated using an evaporator. 29 mL of distilled water was added, and the mixture was extracted with 32 mL of ethyl acetate (AcOEt) and then with 16 mL of AcOEt. The extract was washed with 30 mL of brine, dried over magnesium sulfate, and filtered. The solvent was removed by distillation to obtain 3.7 g of bisphenol A episulfide resin as a residue.

[0064] <Other resins> Epoxy resin 1: Mitsubishi Chemical YX-8034. Hydrogenated bisphenol A epoxy resin, epoxy equivalent weight 270g / eq Epoxy resin 2: Mitsubishi Chemical Corporation's JER828. Bisphenol A epoxy resin, epoxy equivalent weight 185g / eq Thiol compound: SS32 manufactured by Kawaguchi Chemical Industry Co., Ltd. Trifunctional thiol compound, molecular weight 532. Thiol equivalent weight 177.3 g / eq

[0065] <Curing agent> Maleimide compound: Designer Molecules BMI-6000, terminal bismaleimide resin, number average molecular weight 6626, weight average molecular weight 21733, maleimide equivalent weight 3313 g / eq Benzoxazine compound: Pd-type benzoxazine compound manufactured by Shikoku Kasei Co., Ltd., molecular weight 435, benzoxazine equivalent weight 217.5 g / eq Carbodiimide compound: A compound prepared as follows. Number average molecular weight: 2997, weight average molecular weight: 17193, carbodiimide group equivalent weight: 205 g / eq A reaction vessel equipped with a reflux condenser and a stirrer was charged with a mixture of 54 parts by mass of 2,4'-diphenylmethane diisocyanate and 46 parts by mass of 4,4'-diphenylmethane diisocyanate (manufactured by Tosoh Corporation, Monomeric MDI; Millionate NM) as a diisocyanate, 10 parts by mass of phenyl isocyanate as a compound having one functional group reactive with an isocyanate group, and 0.6 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide as a carbodiimide catalyst, and the mixture was stirred at 100°C for 2 hours under a nitrogen stream. The mixture was then analyzed by infrared absorption (IR) spectroscopy at a wavelength of 2270 cm -1 After confirming that the absorption peaks due to the isocyanate groups before and after the reaction had almost disappeared, a carbodiimide compound was obtained. Active ester compound: DIC HPC-8000-65T, non-volatile content 65% by weight, active ester group equivalent weight 223 g / eq Cyanate compound: BA-230S manufactured by Lonza Japan, non-volatile content 75% by weight, cyanate ester group equivalent weight 235g / eq

[0066] <Other ingredients> Inorganic filler: Silica filler (spherical, average particle size 0.5 μm) Solvent 1: Cyclohexanone Solvent 2: Methyl ethyl ketone

[0067] The various measurements were carried out as follows. <Preparation of Resin Composition> The components were mixed in the amounts shown in Table 1 (in Table 1, the amount of each component is expressed in parts by mass) using a revolutionary rotation stirring and degassing apparatus (Shashin Kagaku Co., Ltd., Kakuhunter SK-300S) at 2000 rpm for 5 minutes and then degassed at 2200 rpm for 2 minutes to prepare the compositions of the examples and comparative examples.

[0068] <Preparation of cured film> The compositions of the Examples and Comparative Examples were applied to copper foil with an applicator and dried in a box drying oven at 90°C for 10 minutes. The copper foil with the dried coating was then placed in a drying oven with an internal temperature of room temperature (approximately 25°C), heated to the temperature shown in Table 1 over 30 minutes, and then maintained at that temperature for 1 hour for heat treatment. The copper foil with the cured coating was removed from the drying oven, the copper foil was removed with an etching solution, and washed with water to obtain a cured film with a thickness of approximately 30 μm.

[0069] <Dielectric properties> The cured film prepared by the above method was dried in a box drying oven at 120°C for 10 minutes, and the dielectric constant and dielectric loss tangent at 10 GHz were measured using the SPDR method.

[0070] <Mechanical properties> Film samples made from the cured products of each composition prepared in the same manner as above were cut into 5 mm wide x 70 mm long specimens. Tensile tests were carried out five times on this test piece using an EZ-SX made by Shimadzu Corporation, with a gripping distance of 30 mm and a tensile speed of 3 mm / min. The modulus of elasticity was measured at a tensile strength of 5 to 10 MPa, and the average value was taken as the modulus of elasticity (GPa). The stress until the test piece broke was measured, and the average of the maximum values ​​was taken as the maximum point stress (MPa). The elongation until the test piece broke was measured, and the maximum value was taken as the tensile elongation at break (%).

[0071] <Thermal properties> The cured film prepared by the above method was cut into a piece of 3 mm width x 30 mm length, and the thermal expansion coefficient and glass transition temperature were measured using a TA Instruments TMA "Q400-1330" at a temperature rise rate of 10°C / min over a measurement temperature range of 30 to 300°C.

[0072] [Table 1]

[0073] As shown in Table 1, the cured products of the examples have low dielectric constants and low dielectric dissipation factors, and are improved over the comparative examples in which an epoxy resin or a thiol compound was used in combination, particularly in terms of low dielectric dissipation factor. In particular, Examples 1 and 2, which used a maleimide compound as a curing agent, showed significant improvements in maximum stress and elongation at break. Moreover, Example 4, which uses a carbodiimide compound as a curing agent, has an improved thermal expansion coefficient and a high glass transition temperature.

[0074] The resin compositions of the Examples and Comparative Examples were prepared using the components in the amounts shown in Table 2 (the amounts of each component are expressed in parts by mass), and cured films were prepared in the same manner as above, and various properties were measured. The resin compositions shown in Table 2 contain an inorganic filler.

[0075] [Table 2]

[0076] As shown in Table 2, even when an inorganic filler was used, the cured products of the examples had low dielectric constants and low dielectric dissipation factors, and were improved over the comparative examples in which an epoxy resin was used in combination, particularly in terms of low dielectric dissipation factor. Among these, Example 5, which used a maleimide compound as a curing agent, showed significant improvements in maximum stress and elongation at break. Moreover, Example 7, which uses a carbodiimide compound as a curing agent, has an improved thermal expansion coefficient and a high glass transition temperature. On the other hand, it can be seen that Comparative Examples 6 and 7, which used an active ester compound or a cyanate compound as a curing agent, had inferior induction properties to the Examples. [Industrial Applicability]

[0077] The curable resin composition of the present invention is highly useful industrially because it can provide a cured product having a low dielectric constant and a low dielectric loss tangent.

Claims

1. A curable resin composition comprising an episulfide resin and at least one curing agent selected from the group consisting of a maleimide compound and a benzoxazine compound.

2. 2. The curable resin composition according to claim 1, wherein a ratio of the number of moles of functional groups in the curing agent to the number of moles of thiirane groups contained in the episulfide resin is 0.1 or more and 1.5 or less.

3. The curable resin composition of claim 1 further comprising an inorganic filler.

4. A dry film comprising a substrate and a resin layer formed on the substrate, the resin layer comprising the curable resin composition according to any one of claims 1 to 3.

5. A prepreg obtained by impregnating a substrate with the curable resin composition according to any one of claims 1 to 3.

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

7. A laminate comprising the cured product of claim 6.

8. An electronic part comprising the cured product according to claim 6.

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