JP7406310B2 - Curable resin compositions, dry films, cured products, electronic components - Google Patents

Description

The present invention relates to a curable resin composition containing organic-inorganic composite particles in which the surfaces of inorganic particles are coated with a polymer, as well as a dry film, a cured product, and an electronic component.

In recent years, in the field of electronic equipment, miniaturization and higher performance have progressed, and multilayer printed wiring boards have been widely studied. When such multilayer printed wiring boards are used in high- or low-temperature environments, due to differences in thermal expansion properties of the copper circuits and insulating layers that make up the printed wiring boards, the printed wiring boards may deform or cause internal stress. Problems such as circuit disconnections have been a problem. Therefore, in order to provide thermal dimensional stability (low thermal expansion) against temperature changes to interlayer insulation materials that form the insulation layers of multilayer printed wiring boards, studies have been conducted on methods of highly filling inorganic particles such as silica. .

However, with the method of highly filling inorganic particles, although a low thermal expansion property of the insulating layer can be obtained, there is a problem that the flexibility is reduced and cracks are likely to occur even with a slight stress, and the low thermal expansion property and toughness ( There is a need for interlayer insulating materials that have both high tensile elongation at break.
Patent Document 1 describes a method for achieving both low thermal expansion and toughness by filling a curable resin composition such as an epoxy resin with a combination of an inorganic filler and cellulose nanofibers (sometimes abbreviated as CNF). A technique for doing so has been disclosed.

International Publication No. 2018/181802

Indeed, according to the method described in Patent Document 1, it is possible to achieve low thermal expansion of the cured product, but there is still room for improvement in toughness (tensile elongation at break).

Therefore, the object of the present invention is to provide a curable resin composition having excellent low thermal expansion and toughness in a cured product, and a dry film, cured product, and electrical component using this curable resin composition. Our goal is to provide the following.

The inventors of the present invention, while making intensive studies to achieve the above object, found that when a curable resin composition containing an epoxy resin as a main component is filled with a combination of inorganic particles and CNF, the inorganic particles It was noticed that toughness deteriorated due to agglomeration (deterioration of dispersibility), and further investigation was carried out. As a result, the inventors discovered that aggregation of the inorganic particles and CNF can be suppressed by coating the surfaces of the inorganic particles with an acrylate polymer, thereby completing the present invention.

That is, the present invention
A curable resin composition comprising an epoxy resin, a curing agent, organic-inorganic composite particles, and cellulose nanofibers,
The organic-inorganic composite particles are inorganic particles whose surfaces are coated with a polymer,
The present invention provides a curable resin composition, wherein the polymer is a polymer or copolymer of a (meth)acrylic monomer.

Here, the (meth)acrylic monomer may include a (meth)acrylic monomer containing a hydroxyl group and/or a cyclic ether group.

The present invention provides a dry film characterized by having a resin layer formed by coating and drying the curable resin composition on a base material.

The present invention provides a cured product obtained by curing the curable resin composition or the resin layer.

The present invention provides an electronic component comprising the cured product.

According to the present invention, a curable resin composition having excellent low thermal expansion and toughness in a cured product after curing, and a dry film, a cured product, and an electrical component using this curable resin composition are provided. can do.

This is a photograph of a fractured surface as a standard for evaluating the dispersibility of a cured product.

In addition, when isomers exist in the described compound, all possible isomers can be used in the present invention unless otherwise specified.

In the present invention, the term (meth)acrylate refers to methacrylate, acrylate, or a mixture of methacrylate and acrylate.

Furthermore, in the present invention, inorganic particles mean inorganic particles whose surfaces have not been subjected to any modification treatment such as a coupling agent, unless otherwise specified.

In the present invention, the SP value of the (meth)acrylic monomer and organic solvent used can be calculated by the Fedors method.

The solid content of a composition in the present application means components constituting the composition other than the solvent (particularly organic solvent), or the mass or volume thereof.

<<<<Curable resin composition>>>>
The curable resin composition of the present invention includes an epoxy resin, a curing agent, organic-inorganic composite particles, and cellulose nanofibers.

<<<Epoxy resin>>>
The curable resin composition of the present invention contains an epoxy resin as a curable resin.

The epoxy resin is not particularly limited as long as it does not inhibit the curing of the present invention, and any conventionally known epoxy resin can be used. Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol E epoxy resin, bisphenol M epoxy resin, bisphenol P epoxy resin, and bisphenol Z epoxy resin. Bisphenol type epoxy resin, bisphenol A novolac type epoxy resin, phenol novolac type epoxy resin, novolac type epoxy resin such as cresol novolac epoxy resin, biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, aryl alkylene type epoxy resin, tetraphenylole ethane type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, trihydroxyphenylmethane type epoxy resin, hydantoin type epoxy resin, tetraphenylolethane type epoxy Resin, brominated epoxy resin, hydrogenated (bisphenol) type resin, glycidylamine type epoxy resin, alicyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl xylenoylethane resin, glycidyl methacrylate copolymerized epoxy resin, cyclohexyl Copolymerized epoxy resin of maleimide and glycidyl methacrylate, epoxy-modified polybutadiene rubber derivative, CTBN-modified epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, 1,6-hexanediol diglycidyl ether , ethylene glycol or propylene glycol diglycidyl ether, sorbitol polyglycidyl ether, tris(2,3-epoxypropyl)isocyanurate, triglycidyltris(2-hydroxyethyl)isocyanurate, and other epoxy resins. These epoxy resins can be used alone or in combination of two or more, and from the viewpoint of increasing the toughness of the cured product, epoxy resins having two epoxy groups are more preferable.

Commercially available epoxy resins include, for example, jER828, jER834, jER1001, and jER1004 manufactured by Mitsubishi Chemical Corporation, EPICLON840, EPICLON850, EPICLON1050, and EPICLON2055 manufactured by DIC Corporation, and EPOTOTO manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. YD-011, YD-013, YD-127, YD-128, D. E. R. 317, D. E. R. 331, D. E. R. 661, D. E. R. 664, Sumi-epoxy ESA-011, ESA-014, ELA-115, ELA-128 manufactured by Sumitomo Chemical Co., Ltd., jERYL903 manufactured by Mitsubishi Chemical Corporation, EPICLON152, EPICLON165 manufactured by DIC Corporation, Nippon Steel & Sumikin Chemical Co., Ltd. Epototo YDB-400, YDB-500 manufactured by Dow Chemical Company, D. E. R. 542, Sumie-Epoxy ESB-400 and ESB-700 manufactured by Sumitomo Chemical Co., Ltd., jER152 and jER154 manufactured by Mitsubishi Chemical Corporation, D. E. N. 431, D. E. N. 438, EPICLONN-730, EPICLONN-770, EPICLONN-865 manufactured by DIC Corporation, EPOTOTO YDCN-701, YDCN-704 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., EPPN-201, EOCN-1025 manufactured by Nippon Kayaku Co., Ltd. , EOCN-1020, EOCN-104S, RE-306, Sumi-Epoxy ESCN-195X, ESCN-220 manufactured by Sumitomo Chemical Co., Ltd., EPICLON830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, Nippon Steel & Sumikin Chemical Co., Ltd. Bisphenol F-type epoxy resins such as Epototh YDF-170, YDF-175, and YDF-2004 (all trade names) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; Epototh ST-2004, ST-2007, and ST-3000 (trade names) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. ) and other hydrogenated bisphenol A type epoxy resins; jER604 manufactured by Mitsubishi Chemical Corporation, Epototo YH-434 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., Sumie-Epoxy ELM-120 manufactured by Sumitomo Chemical Co., Ltd. (all product names) ) glycidylamine type epoxy resins; hydantoin type epoxy resins; alicyclic epoxy resins such as Celoxide 2021P (trade name) manufactured by Daicel Corporation; YL-933 manufactured by Mitsubishi Chemical Corporation; T. E. N. Trihydroxyphenylmethane type epoxy resins such as , EPPN-501, EPPN-502 (all trade names); Xylenol type or biphenol type epoxy resin or mixture thereof; bisphenol S type epoxy such as EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by Asahi Denka Co., Ltd., EXA-1514 (trade name) manufactured by DIC Corporation Resin: Bisphenol A novolac type epoxy resin such as jER157S (trade name) manufactured by Mitsubishi Chemical Corporation; Tetraphenyloleethane type epoxy resin such as jERYL-931 (both trade names) manufactured by Mitsubishi Chemical Corporation; Nissan Chemical Industries, Ltd. Heterocyclic epoxy resins such as TEPIC (trade name) manufactured by Nippon Oil & Fats Corporation; diglycidyl phthalate resins such as Blenmar DGT manufactured by Nippon Oil & Fats Corporation; tetraglycidyl xylenoylethane resins such as ZX-1063 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; Naphthalene group-containing epoxy resins such as ESN-190, ESN-360 manufactured by Nippon Steel Chemical Co., Ltd., HP-4032, EXA-4750, EXA-4700 manufactured by DIC Corporation; Epoxy resins having a cyclopentadiene skeleton; glycidyl methacrylate copolymer epoxy resins such as CP-50S and CP-50M manufactured by NOF Corporation; further copolymer epoxy resins of cyclohexyl maleimide and glycidyl methacrylate; epoxy-modified polybutadiene rubber derivatives (for example, PB-3600 manufactured by Daicel Chemical Industries, etc.), CTBN-modified epoxy resin (for example, YR-102, YR-450, etc. manufactured by Toto Kasei Co., Ltd.), and the like.

The content of the epoxy resin can be, for example, 0% by mass or more, 10% by mass or more, 30% by mass or more, 65% by mass or more, based on the total curable resin. The upper limit can be 100% by mass or less, 90% by mass or less, 70% by mass or less, 50% by mass or less, and 35% by mass or less. Note that the fully curable resin includes all curable resins.

<<Curing agent>>
The curable resin composition of the present invention contains a curing agent.

A known curing agent can be used and is not particularly limited. Examples of hardening agents include phenol resins, polycarboxylic acids and their acid anhydrides, cyanate ester resins, active ester resins, melamine, triazine-containing resins, amines such as tertiary amines and polyamines, polyamide resins, dicyandiamide, and polyamides. Examples include mercaptan. The curing agent can be used alone or in combination of two or more types. Among these, phenol resins are preferred because they provide excellent toughness as a cured product of the curable resin composition.

Preferred examples of phenol resin and amines are illustrated below.

The above phenolic resins include phenol novolak resin, alkylphenol volac resin, bisphenol A novolac resin, dicyclopentadiene type phenol resin, Xylok type phenol resin, terpene modified phenol resin, cresol/naphthol resin, polyvinylphenols, phenol/naphthol resin. , α-naphthol skeleton-containing phenol resin, triazine-containing cresol novolac resin, and other conventionally known resins can be used alone or in combination of two or more.

As amines, for example, compounds having two or more of one or more types selected from the group consisting of primary amino groups and secondary amino groups (hereinafter also simply referred to as "amino groups") in one molecule are preferable. Compounds having 2 to 4 groups are more preferred, and diamine compounds having 2 amino groups are even more preferred.

Examples of the amines include aliphatic amine compounds, aromatic amine compounds, and the like. Among these, curable resin compositions that can provide excellent dispersibility of inorganic particles and cellulose nanofibers in the curable resin composition or cured product, and also allow the cured product to have low thermal expansion and high toughness. Aromatic amine compounds are preferred because they can provide the following. Note that the aromatic amine compound refers to a compound in which at least one hydrogen atom in an aromatic ring is substituted with an amino group. The aromatic amine compound is preferably a liquid aromatic amine compound.

Examples of aromatic amine compounds include diethyltoluenediamine, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3 , 5-triethyl-2,6-diaminobenzene, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,5,3',5'-tetramethyl-4,4'-diaminodiphenylmethane, dimethylthio Examples include toluenediamine. These can be used alone or in combination. Among these, from the viewpoint of storage stability, for example, diethyltoluenediamine, 3,3'-diethyl-4,4'-diaminodiphenylmethane and dimethylthiotoluenediamine are preferable, and diethyltoluenediamine and 3,3'-diethyl -4,4'-diaminodiphenylmethane is more preferred.

As the aromatic amine compound, commercially available products may be used. Examples of commercially available aromatic amine compounds include jER Cure (registered trademark) W (manufactured by Mitsubishi Chemical Corporation, trade name), Kayahard (registered trademark) AA, Kayahard (registered trademark) AB, Kayahard (registered trademark) Registered trademark) A-S (manufactured by Nippon Kayaku Co., Ltd., trade name), Totoamine HM-205 (manufactured by Toto Kasei Co., Ltd., trade name), ADEKA Hardener (registered trademark) EH-101 (manufactured by ADEKA Co., Ltd.) , trade name), Epomic (registered trademark) Q-640, Epomic (registered trademark) Q-643 (manufactured by Mitsui Chemicals, Inc., trade name), DETDA80 (manufactured by Lonza, trade name), etc. .

As for the content of the curing agent, the reactive functional group/epoxy equivalent of the curing agent is preferably 0.7 to 1.4, more preferably 0.8 to 1.2. Within this range, the cured product of the curable resin composition can have excellent storage stability, curability, mechanical properties, thermal properties, and insulation reliability.

<<<Organic-inorganic composite particles>>>
The curable resin composition of the present invention contains organic-inorganic composite particles.

In the organic-inorganic composite particles according to the present invention, the surfaces of the inorganic particles are coated with a polymer. Here, the expression that the surface of the inorganic particle is "coated" with a polymer only requires that part or all of the surface of the inorganic particle is coated with the polymer, and it is sufficient that the surface of the inorganic particle is coated with the polymer. The amount of coating can be analyzed by thermogravimetric thermal analysis (TG/DTA). From the viewpoint of dispersibility in a resin or an organic solvent, the organic-inorganic composite particles are preferably coated with 1.5% by mass or more of a polymer based on the inorganic particles.

This coating polymer is a polymer or copolymer obtained by polymerizing a (meth)acrylic monomer.

Such organic-inorganic composite particles include, for example, inorganic particles, an organic solvent, a (meth)acrylic monomer serving as a raw material for the polymer, and a polymerization initiator (radical polymerization initiator) for polymerizing the (meth)acrylic monomer. The (meth)acrylic monomer is adsorbed onto the surface of the inorganic particles in a treatment solution containing the inorganic particle and polymerized on the surface of the inorganic particles to form a polymer. Here, the polymer is a product obtained by polymerization or copolymerization of (meth)acrylic monomers, and the degree of polymerization as a polymer is determined by the amount of each component (meth)acrylic monomer, organic solvent, polymerization initiator, and inorganic particles. It can be adjusted by the type and amount, reaction temperature, reaction time, stirring treatment, etc.

Moreover, it is preferable that the SP value of the (meth)acrylic monomer and the SP value of the organic solvent according to the present invention have the following relationship.
(SP value of (meth)acrylic monomer) - (SP value of organic solvent) ≧0.5

In such a relationship, the compatibility between the (meth)acrylic monomer and the organic solvent becomes poor, and as a result, the (meth)acrylic monomer is generally more hydrophilic than the organic solvent on the surface of the inorganic particles. It is thought that it will be efficiently adsorbed by.

Further, the polymer may be a polymer of a single (meth)acrylic monomer or a copolymer of multiple types of (meth)acrylic monomers. In the case of forming a copolymer, a plurality of (meth)acrylic monomers are contained in the solution. The copolymer is not particularly limited, and may be a random copolymer, a block copolymer, a graft copolymer, a block-graft copolymer, or the like.

<<Inorganic particles>>
The inorganic particles used in the present invention refer to inorganic particles whose surfaces are not modified, but if they have lower hydrophilicity than an organic solvent, it is preferable to perform a hydrophilic treatment.

Generally, inorganic particles whose surfaces are not modified are not particularly limited as long as their surfaces have sufficiently high polarity and are more hydrophilic than the organic solvent used in combination. Examples of such inorganic particles include silica, crystalline silica, Neuburg silica, aluminum oxide, aluminum hydroxide, boron nitride, aluminum nitride, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic Using inorganic particles such as mica, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, calcium zirconate, zinc oxide, solder particles, silver powder, copper powder, etc. be able to. Among these, in electronic materials such as solder resists and sealants, it is preferable to use silica, which has excellent thermal dimensional stability and dielectric properties, and aluminum oxide, boron nitride, and the like, which have excellent thermal conductivity. Further, as the silica and aluminum oxide, spherical silica, calcium zirconate, and spherical aluminum oxide are more preferable from the viewpoint of improving filling properties into the composition.

The average particle size of the inorganic particles is not particularly limited, but can be, for example, 10 nm to 20,000 nm, preferably 20 nm to 10,000 nm, more preferably 50 nm to 5,000 nm. The average particle diameter of the inorganic particles can be the value of D50 measured by laser diffraction method. An example of a measuring device using a laser diffraction method is Microtrac MT3300EXII manufactured by Microtrac Bell.

<<Method for manufacturing organic-inorganic composite particles>>
Below, as a method for producing organic-inorganic composite particles of the present invention, a method for producing organic-inorganic composite particles of the present invention, which is a preferred example, will be described in detail.
<Raw materials>
(Organic solvent)
The organic solvent used in the present invention is not particularly limited as long as it satisfies the numerical relationship of the SP value of the present invention. Organic solvents usually exhibit hydrophobicity and have an SP value in the range of 7.0 to 12.0. For example, those with an SP value of 7.2 to 10.0 are preferable, and those with an SP value of 7.0 to 12.0 are preferable. Those with an SP value of 5 to 9.5 are more preferred, and those with an SP value of 8.0 to 9.2 are even more preferred.

Specifically, as organic solvents, toluene (SP value 9.14), methyl ethyl ketone (SP value 9.9), PMA (SP value 9.25), ethyl acetate (SP value 9.1), carbitol acetate ( Examples include SP value 9.98), cyclohexanone (SP value 8.56), acetone (SP value 10.0), and 1-propanol (SP value 11.84). These can be used alone or in combination. Among these, toluene and ethyl acetate are preferred because they do not interfere with the radical polymerization reaction.

Further, the SP value when a plurality of organic solvents are mixed and used can be calculated according to the following formula. The following formula is a calculation formula when two organic solvents are mixed.
δsm=Xs1×δs1+(1-Xs1)×δs2
In the formula, δsm means the SP value of the mixed solvent, δs1 means the SP value of organic solvent 1, δs2 means the SP value of organic solvent 2, and Xs1 means the molar fraction of organic solvent 1.

The amount of the organic solvent blended in the treatment solution is preferably 100 parts by mass to 500 parts by mass, when the blended amount of the inorganic particles is 100 parts by mass. When the amount of the organic solvent is within this range, the organic solvent in which the (meth)acrylic monomer is dissolved will spread over the surface of the inorganic particles, making it possible to coat them efficiently.

((meth)acrylic monomer)
The (meth)acrylic monomer used in the present invention is a monomer having a radically polymerizable reactive group, and is particularly limited as long as it contains at least one type of (meth)acrylic monomer that satisfies the numerical relationship of the SP value in the present invention. Not done. By satisfying the numerical relationship of the SP value, the (meth)acrylic monomer becomes more hydrophilic than the organic solvent that is blended with it, and its compatibility becomes lower, allowing it to be efficiently adsorbed onto the hydrophilic inorganic particles. be done. As such a (meth)acrylic monomer, for example, one having an SP value of 9.0 to 15.0 can be used, and one having an SP value of 9.5 to 13.5 is preferable. .

Furthermore, at least one of the (meth)acrylic monomers preferably has a cyclic ether group in its structure. It is presumed that the cyclic ether group reacts with the epoxy resin and curing agent in the curable resin composition, thereby chemically bonding the organic-inorganic composite particles and the cured resin, thereby making the cured product tough.

Furthermore, when the (meth)acrylic monomer has a hydroxyl group and/or a cyclic ether group, it can be easily modified with a monomer containing a functional group that is reactive with them. Therefore, depending on the use of the organic-inorganic composite particles, various properties and functions can be easily imparted to the organic-inorganic composite particles.

Examples of (meth)acrylic monomers containing such a hydroxyl group or a cyclic ether group include 2-hydroxyethyl acrylate (SP value 12.45), 4-hydroxybutyl acrylate (SP value 11.64), and 2-hydroxypropyl. Acrylate (SP value 11.83), Tetrahydrofurfuryl acrylate (SP value 9.99), Benzyl acrylate (SP value 10.24), 2-phenoxyethyl acrylate (SP value 10.12), 4-hydroxybutyl acrylate glycidyl Ether (SP value 9.99), 2-hydroxyethyl methacrylate (SP value 10.80), 4-hydroxybutyl methacrylate (SP value 10.59), 2-hydroxypropyl methacrylate (SP value 10.80), glycidyl methacrylate (SP value 10.21). These can be used alone or in combination. In addition, when a plurality of polymers are used in combination, the polymer that coats the inorganic particles becomes a copolymer.

In addition, when using a plurality of monomers as a mixture, it is sufficient that at least one type of (meth)acrylic monomer satisfying the following formula is included. If one or more (meth)acrylic monomers that satisfy the following formula are contained, the (meth)acrylic monomer that satisfies the following formula will preferentially be inorganic, even if other monomers do not satisfy the following formula. The monomer is adsorbed onto the particle surface, and a polymer is formed using the adsorbed monomer as a starting point to coat the inorganic particles.
(SP value of (meth)acrylic monomer) - (SP value of organic solvent) ≧0.5

The blending amount of the (meth)acrylic monomer in the treatment solution is 0.5 parts by mass to 15 parts by mass, and 1 part by mass to 10 parts by mass, when the blending amount of the inorganic particles is 100 parts by mass. It is preferably 1.5 parts by mass to 7.5 parts by mass. When the amount of the monomer is within this range, the surfaces of the inorganic particles can be coated.

(radical polymerization initiator)
The radical polymerization initiator used in the present invention is not particularly limited as long as it does not impede the effects of the present invention, and a photo radical polymerization initiator, a thermal radical polymerization initiator, etc. can be used. The radical polymerization initiator generates active species (also referred to as free radicals) by heat or ultraviolet rays, causes the (meth)acrylic monomer to undergo a polymerization reaction, and can easily form a polymer. Radical polymerization initiators can be used alone or in combination of two or more.

Thermal radical polymerization initiators are not particularly limited, but include, for example, azo polymerization initiators (for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2 , 2'-azobis(2-methylpropionate) dimethyl, 4,4'-azobis-4-cyanovalerianic acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2, 2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N , N'-dimethyleneisobutyramidine) dihydrochloride, etc.); peroxide polymerization initiators (for example, dibenzoyl peroxide, t-butyl permaleate, lauroyl peroxide, etc.); redox polymerization initiators, etc. .

Examples of the photoradical polymerization initiator include, but are not particularly limited to, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, and photopolymerization initiators. Active oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, ketal photoinitiator, thioxanthone photoinitiator, acylphosphine oxide photoinitiator Initiators and the like can be mentioned.

Specifically, benzoin ether photopolymerization initiators include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethane. Examples include 1-one [trade name: Irgacure 651, manufactured by BASF], anisoin, and the like. Examples of acetophenone photopolymerization initiators include 1-hydroxycyclohexylphenylketone [trade name: Irgacure 184, manufactured by BASF], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-( 2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF], 2-hydroxy-2-methyl-1-phenyl-propane- Examples include 1-one [trade name: Darocure 1173, manufactured by BASF], methoxyacetophenone, and the like. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropane-1- Ong et al. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime.

Furthermore, the benzoin-based photopolymerization initiator includes, for example, benzoin. Benzyl photoinitiators include, for example, benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Ketal-based photopolymerization initiators include, for example, benzyl dimethyl ketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, These include 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

Examples of acylphosphine-based photopolymerization initiators include bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis( 2,6-dimethoxybenzoyl)-n-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-t-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)cyclohexylphosphine oxide, bis(2,6-dimethoxybenzoyl)octylphosphine oxide, bis(2-methoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2-methoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide, bis(2,6-diethoxy) benzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,6-diethoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide, bis(2,6-dibutoxybenzoyl)(2 -methylpropan-1-yl)phosphine oxide, bis(2,4-dimethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)(2,4-dimethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, pentoxyphenyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenyl Ethylphosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylethylphosphine oxide , 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diisopropylphenylphosphine oxide, bis(2,4, 6-trimethylbenzoyl)-2-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-4-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diethylphenyl Phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,3,5,6-tetramethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxy Phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)isobutylphosphine oxide, 2,6-dimethythoxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl) )-2,4-dibutoxyphenylphosphine oxide, 1,10-bis[bis(2,4,6-trimethylbenzoyl)phosphine oxide]decane, tri(2-methylbenzoyl)phosphine oxide,
Examples include.

The amount of the radical polymerization initiator in the treatment solution is preferably 0.1 parts by mass to 6 parts by mass, when the amount of the (meth)acrylic monomer is 100 parts by mass. When the amount of the polymerization initiator is within this range, the inhibitory effect of the photopolymerization initiator on absorbing ultraviolet rays is suppressed, and by obtaining a sufficient molecular length of the polymer, the polymer is peeled off from the surface of the inorganic particles. The surface of the inorganic particles can be coated efficiently.

<Preferred example of method for producing organic-inorganic composite particles>
A preferred method for producing organic-inorganic composite particles is to immerse inorganic particles in a treatment solution containing an organic solvent, a (meth)acrylic monomer that is a raw material for the coating polymer, and a polymerization initiator that polymerizes the monomer. The method also includes a step of adsorbing the (meth)acrylic monomer onto the surface of the inorganic particles, preferably by stirring.

In particular, in this step, it is preferable that at least one type of monomer among the (meth)acrylic monomers and the organic solvent have the following relationship in terms of SP value.
(SP value of (meth)acrylic monomer) - (SP value of organic solvent) ≧0.5
In such a relationship, the compatibility between the (meth)acrylic monomer and the organic solvent becomes poor, and as a result, the (meth)acrylic monomer is generally more hydrophilic than the organic solvent on the surface of the inorganic particles. It is thought that it will be efficiently adsorbed by.

Here, in the present invention, the stirring method (including conditions) is not particularly limited, and any known method can be used. In particular, adjusting the stirring temperature (temperature of the treatment solution) is effective in efficiently performing the polymerization reaction in that it is possible to adjust the adsorption efficiency of the (meth)acrylic monomer onto the surface of the inorganic particles.

The above numerical relationship of the SP value is based on the affinity (wettability) between the organic solvent and the (meth)acrylic monomer in the treatment solution for coating the surface of the inorganic particles with an organic polymer by polymerizing the (meth)acrylic monomer. A small difference in SP value between the components indicates a high affinity between the components. Furthermore, since the SP value of water is larger than that of organic solvents and (meth)acrylic monomers (SP value of water: 23.4), a high SP value also indicates high hydrophilicity.

Therefore, in the above treatment solution, in order to efficiently adsorb the (meth)acrylic monomer on the surface of the inorganic particles, while reducing the affinity between the (meth)acrylic monomer and the organic solvent, the (meth) It is important to improve the affinity between the acrylic monomer and inorganic particles, and in terms of the SP value, the SP value of the (meth)acrylic monomer and the SP value of the organic solvent are It is preferable that the value is large and the difference in SP value is 0.5 or more.

According to this numerical relationship of SP values, in a treatment solution containing a mixture of a (meth)acrylic monomer, an organic solvent, and inorganic particles to coat the surface of the inorganic particles, the (meth)acrylic monomer is coated on the surface of the inorganic particles. is efficiently adsorbed, and problems such as separation of the (meth)acrylic monomer and organic solvent and aggregation of inorganic particles do not occur. Furthermore, as will be described later, when (meth)acrylic monomers are polymerized using the radical polymerization initiator blended in the treatment solution, the (meth)acrylic monomers adsorbed on the surface of the inorganic particles are preferentially polymerized. It is presumed that a film made of a good organic polymer can be efficiently formed on the surface of the inorganic particles.

Further, the method for producing organic-inorganic composite particles includes a step of polymerizing the (meth)acrylic monomer adsorbed onto the inorganic particles in the above step by applying heat or ultraviolet rays to a radical polymerization initiator. include. Thereby, the organic-inorganic composite particles of the present invention can be obtained by forming an organic polymer film on the surface of the inorganic particles, and further mixing and reacting with a compound having an isocyanate group.

The organic-inorganic composite particles thus obtained may be taken out of the processing solution and used in a dried state, or may be used in a state dispersed in the processing solution. When used in a dry state, the organic-inorganic composite particles are separated by filtration or the like using a known method. After separation, the organic-inorganic composite particles can be washed with an organic solvent or the like to remove unreacted monomers and polymers that are not bonded to the surface of the inorganic particles, and then dried by heating to a predetermined temperature. The drying method can be performed using a known method such as a drying oven.

<<<Cellulose nanofiber>>>
The curable resin composition according to the present invention contains cellulose nanofibers (hereinafter sometimes abbreviated as CNF).

CNF according to the present invention is not particularly limited. Examples of CNF include mechanically defibrated CNF; 2,2,6,6-tetramethylpiperidine 1-oxyl (also referred to as TEMPO), and amino acid after oxidation treatment with a compound having a phosphate group or/and its salt. Examples include CNF that has been covalently modified with a compound and defibrated, or CNF that has been subjected to hydrophobization treatment, such as CNF that has been modified with an ionic bond and defibrated with a quaternary ammonium compound after the oxidation treatment. Among these, hydrophobized CNF is preferred because it has excellent dispersibility in the resin hydrophobe, and the curable resin composition can have excellent low-temperature curability and storage stability. Among these, hydrophobized CNF has excellent dispersibility in resin hydrophobes, and the cured product of the curable resin composition has excellent tensile properties, low thermal expansion, and insulation reliability. It is preferable because it can be done.

In the present invention, the average fiber diameter of CNF is, for example, 0.1 nm or more and 200 nm or less, preferably 1 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and even more preferably 2.5 nm or more and 20 nm or less. When the average fiber diameter is within this range, it is possible to obtain a cured product that has excellent adhesion to conductors of wiring boards and the like.

The average fiber length of CNF is, for example, 600 nm or less, preferably 50 nm or more and 600 nm or less, more preferably 100 nm or more and 500 nm or less, and still more preferably 100 nm or more and 400 nm or less. By setting the average fiber length to 600 nm or less, it becomes easy to disperse the composition. By increasing the dispersibility of CNF, the cured product of the curable resin composition can have excellent tensile properties, low thermal expansion, and insulation reliability.

The average aspect ratio of CNF is, for example, 1 or more and 200 or less, preferably 5 or more and 180 or less, more preferably 9 or more and 170 or less, particularly preferably 9 or more and 100 or less. If the average aspect ratio is less than 1, it is difficult to manufacture. If the average aspect ratio is 200 or less, the adhesion between the metal conductor and the cured product will be good, and the smaller the average aspect ratio, the better the bond between the metal conductor and the cured product. It has excellent adhesion and can lower the viscosity of the composition.

The average fiber diameter, average fiber length, and average aspect ratio of CNF can be measured as follows.

Water was added to CNF to prepare a dispersion liquid with a concentration of 0.0001% by mass, and this dispersion liquid was dropped onto mica (mica) and dried. This was used as an observation sample using an atomic force microscope (AFM). The fiber height of CNF in the observation sample is measured using a Nanoscope III Tapping mode AFM (manufactured by Digital Instruments, Inc.; the probe is a Point Probe (NCH) manufactured by Nanosensors). At that time, five or more CNFs are extracted from the microscopic image in which CNFs can be confirmed, and the average fiber diameter is calculated from the heights of these fibers. Furthermore, the average fiber length is calculated from the distance in the fiber direction. The average aspect ratio is calculated from average fiber length/average fiber diameter.

The method for producing the CNF is not particularly limited, and any known method can be used.

Examples of the method for producing mechanically defibrated CNF include a method in which cellulose fibers are swollen with water in a large amount of water, and in a softened state, are pulverized by a powerful mechanical device such as a high-pressure homogenizer to form nanofibers.

As a method for producing hydrophobized CNF, a method disclosed in JP-A No. 2018-24878 can be mentioned.

The content of CNF in the curable resin composition according to the present invention is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 1 part by mass, based on 100 parts by mass of the total amount of the curable resin (based on solid content) The content is from 2 parts by mass to 20 parts by mass, more preferably from 2 parts by mass to 10 parts by mass. By keeping the content within this range, the cured product of the curable resin composition can have excellent tensile properties, low thermal expansion properties, and insulation reliability.

<<<Other ingredients>>>
The curable resin composition according to the present invention may contain other components other than the above-mentioned essential components, such as conventional additives, depending on the intended use. Other conventional additives include, but are not limited to, resins and elastomers, curing catalysts, colorants, dispersants, antifoaming agents/leveling agents, thixotropic agents, coupling agents, flame retardants, etc. . Further, the curable resin composition according to the present invention may contain an organic solvent or the like, if necessary.

<<Resins and elastomers>>
Resins and elastomers include resin components other than the above-mentioned curable resins and curing agents, such as unsaturated polyester resins, acrylate resins, diallyl phthalate resins, silicone resins, norbornene resins, isocyanate resins, urethane resins, benzocyclobutene resins, Examples include polyazomethine resin, block copolymer, natural rubber, diene rubber, non-diene rubber, thermoplastic elastomer, and the like.

<<Curing catalyst>>
Among curable resins, the curing catalyst is mainly for curing thermosetting resins, and examples thereof include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 2-ethyl-4-methylimidazole. Imidazole derivatives such as phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4-(dimethylamino) -Amine compounds such as N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; Hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; Examples include phosphorus compounds such as phenylphosphine, dimethylaminopyridine, and the like. In addition, commercially available products include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (manufactured by Shikoku Kasei Kogyo Co., Ltd.), U-CAT3503N, U-CAT3502T, DBU, DBN, U-CATSA102, U- Examples include CAT5002 (manufactured by San-Apro Co., Ltd.), which may be used alone or in combination of two or more. Similarly, guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6 S-triazine derivatives such as -diamino-S-triazine/isocyanuric acid adduct and 2,4-diamino-6-methacryloyloxyethyl-S-triazine/isocyanuric acid adduct can also be used. These curing catalysts can be used alone or in combination.

The content of the curing catalyst is, for example, 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the total thermosetting resin.

<<Colorant>>
Examples of the colorant include coloring pigments, dyes, and the like that are given color index (C.I.; published by The Society of Dyers and Colorists) numbers. For example, red colorants include monoazo, dizuazo, azo lake, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone. Examples of the blue coloring agent include phthalocyanine type and anthraquinone type, and as the pigment type, compounds classified as pigments can be used. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Similarly, green coloring agents include phthalocyanine-based, anthraquinone-based, and perylene-based colorants. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Examples of yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, and anthraquinone. Examples of the white colorant include rutile type or anatase type titanium oxide. Black colorants include carbon black, graphite, iron oxide, titanium black, iron oxide, anthraquinone, cobalt oxide, copper oxide, manganese, antimony oxide, nickel oxide, perylene, and aniline. These include molybdenum sulfide, bismuth sulfide, etc. In addition, coloring agents such as purple, orange, and brown may be added for the purpose of adjusting the color tone.

<<Dispersant>>
Examples of dispersants include polymeric dispersants such as polycarboxylic acid, naphthalene sulfonic acid formalin condensation, polyethylene glycol, polycarboxylic acid partial alkyl ester, polyether, and polyalkylene polyamine, alkyl sulfonic acid, and polyalkylene polyamine. Low-molecular-weight dispersants such as grade ammonium, higher alcohol alkylene oxide, polyhydric alcohol ester, and alkyl polyamine can be used, and sufficient dispersion effects can be obtained, as well as good coating properties of the cured product. be able to.

(defoaming agent/leveling agent)
Defoamers and leveling agents include compounds such as silicone, modified silicone, mineral oil, vegetable oil, fatty alcohol, fatty acid, metal soap, fatty acid amide, polyoxyalkylene glycol, polyoxyalkylene alkyl ether, and polyoxyalkylene fatty acid ester. etc. can be used, the generation of voids can be prevented, and the adhesion to the adherend can be improved.

<<Thixotropic agent>>
As the thixotropic agent, fine particulate silica, silica gel, amorphous inorganic particles, polyamide additives, modified urea additives, wax additives, etc. can be used, which improves the film forming properties of the curable resin composition and improves the coating properties. The film has excellent adhesion to the adherend.

<<Coupling agent>>
As coupling agents, alkoxy groups include methoxy, ethoxy, acetyl, etc., and reactive functional groups include vinyl, methacrylic, acrylic, epoxy, cyclic epoxy, mercapto, amino, diamino, acid anhydride, ureido, sulfide, etc. Isocyanates, for example, vinyl silane compounds such as vinyl ethoxyrane, vinyl trimethoxysilane, vinyl tris(β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxyrane, γ-aminopropyltrimethoxyrane, Amino-based silane compounds such as N-β-(aminoethyl)γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glyside Epoxy silane compounds such as xypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxylane, γ-glycidoxypropylmethyldiethoxysilane, mercapto silanes such as γ-mercaptopropyltrimethoxysilane compounds, silane coupling agents such as phenylamino silane compounds such as N-phenyl-γ-aminopropyltrimethoxysilane, isopropyl triisostearoylated titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate) ) Oxyacetate titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetra(1,1-diallyloxymethyl-1-butyl)bis-(ditridecyl) Phosphite titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyl dimethacrylic isostearoyl titanate, isopropyl tristearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, dicumylphenyl Titanate coupling agents such as oxyacetate titanate and diisostearoyl ethylene titanate, ethylenically unsaturated zirconate-containing compounds, neoalkoxyzirconate-containing compounds, neoalkoxytrisneodecanoylzirconate, neoalkoxytris(dodecyl)benzenesulfonylzirconate Neoalkoxytris(dioctyl)phosphate zirconate, Neoalkoxytris(dioctyl)pyrophosphate zirconate, Neoalkoxytris(ethylenediamino)ethylzirconate, Neoalkoxytris(m-amino)phenylzirconate, Tetra(2, 2-diallyloxymethyl)butyl, di(ditridecyl)phosphite zirconate, neopentyl(diallyl)oxy, trineodecanoylzirconate, neopentyl(diallyl)oxy, tri(dodecyl)benzene-sulfonylzirconate, neopentyl(diallyl) Oxy, tri(dioctyl)phosphatozirconate, neopentyl(diallyl)oxy, tri(dioctyl)pyro-phosphatozirconate, neopentyl(diallyl)oxy, tri(N-ethylenediamino)ethylzirconate, neopentyl(diallyl)oxy , tri(m-amino)phenylzirconate, neopentyl(diallyl)oxy, trimethacrylzirconate, neopentyl(diallyl)oxy, triacrylzirconate, dineopentyl(diallyl)oxy, dip-aminobenzoylzirconate, dineopentyl(diallyl)oxy , di(3-mercapto)propionic zirconate, zirconium(IV) 2,2-bis(2-propenolatomethyl)butanolate, cyclodi[2,2-(bis2-propenolatomethyl)butanolate]pyrophosphatate Zirconate coupling agents such as -O and O, aluminate coupling agents such as diisobutyl (oleyl) acetoacetyl aluminate, and alkyl acetoacetate aluminum diisopropylate can be used to improve adhesion to the substrate and , an improvement in the hardness of the cured product can be expected.

<<Flame retardant>>
Flame retardants include hydrated metals such as aluminum hydroxide and magnesium hydroxide, red phosphorus, ammonium phosphate, ammonium carbonate, zinc borate, zinc stannate, molybdenum compounds, bromine compounds, chlorine compounds, and phosphate esters. , phosphorus-containing polyol, phosphorus-containing amine, melamine cyanurate, melamine compound, triazine compound, guanidine compound, silicone polymer, etc. can be used, and a high level of self-extinguishing property and heat resistance of the cured product can be achieved in a well-balanced manner.

<<Organic solvent>>
Examples of organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, and diethylene glycol. Glycol ethers such as monoethyl ether, dipropylene glycol monoethyl ether, and triethylene glycol monoethyl ether; Esters such as ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate, and esterified products of the above glycol ethers; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol; amides such as dimethylformamide and dimethylacetamide; aliphatic hydrocarbons such as octane and decane; petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, solvent naphtha, etc. Examples include petroleum solvents.

The content of the organic solvent is not particularly limited, and can be adjusted as appropriate depending on the use of the curable resin composition.

Note that such a curable resin composition can be obtained by mixing and dispersing each raw material.

<<<<Dry film>>>>
The dry film according to the present invention is a resin layer obtained by coating or impregnating a base material with the above-mentioned curable composition and drying it.

Here, examples of the base material include metal foil such as copper foil, films such as polyimide film, polyester film, and polyethylene naphthalate (PEN) film, glass cloth, and fibers such as aramid fiber.

The dry film can be obtained, for example, by applying a curable composition onto a polyethylene terephthalate film, drying it, and laminating a polypropylene film as necessary.

<<<<cured product>>>>
The cured product is obtained by curing the above-mentioned curable composition (including the resin layer included in the dry film).

The method for obtaining a cured product from a curable composition is not particularly limited, and can be changed as appropriate depending on the composition of the curable composition. As an example, after carrying out the step of coating the curable composition on the substrate as described above (e.g., coating with an applicator, etc.), a drying step of drying the curable composition is carried out as necessary. Then, a thermosetting step may be performed in which the curable resin and the curing agent are thermally crosslinked by heating (for example, heating using an inert gas oven, hot plate, vacuum oven, vacuum press machine, etc.). Note that the conditions for implementing each step (for example, coating thickness, drying temperature and time, heating temperature and time, etc.) may be changed as appropriate depending on the composition, use, etc. of the curable composition.

<<<<Electronic parts>>>>
Such a cured product has excellent mechanical properties, heat resistance, and transparency, and thus can be used for electronic parts and the like. In particular, it is used in printed wiring boards as interlayer insulating films and solder resist dry films.

Hereinafter, the present invention will be explained in more detail using Examples. In addition, all compounding amounts in the table below indicate parts by mass.

<Preparation of cellulose nanofiber dispersion>
The cellulose nanofibers used in each example and comparative example and the method for producing a dispersion thereof will be shown.
After thoroughly stirring 100 g of bleached hardwood kraft pulp (manufactured by CENIBRA) fibers with 9900 g of ion-exchanged water, 1.25% by mass of TEMPO (manufactured by ALDRICH, Free radical, 98% by mass) was added to 100g of this pulp. , 12.5% by mass of sodium bromide, and 28.4% by mass of sodium hypochlorite were added in this order. The pH was maintained at 10.5 using a pH stud by adding 0.5M sodium hydroxide dropwise. After the reaction was carried out for 120 minutes (20° C.), dropping of sodium hydroxide was stopped to obtain oxidized pulp. The obtained oxidized pulp was sufficiently washed with ion-exchanged water, and then dehydrated to obtain an oxidized pulp with a solid content of 30.4%.
The obtained 105.3 g of oxidized pulp was diluted with 1000 g of ion-exchanged water, and 346 g of concentrated hydrochloric acid was added to prepare a dispersion with an oxidized pulp solid content of 2.34 wt% and a hydrochloric acid concentration of 2.5 M. Reflux for minutes. The oxidized pulp was then thoroughly washed to obtain acid-hydrolyzed TEMPO oxidized pulp with a solid content of 41%. Thereafter, 0.88 g of oxidized pulp and 35.12 g of ion-exchanged water were micronized 10 times at 150 MPa using a high-pressure homogenizer to obtain a carboxyl group-containing fine cellulose fiber dispersion (solid content concentration 5.0% by mass). Ta. The average fiber diameter of this fine cellulose fiber was 11.0 nm, the average fiber length was 187 nm, the average aspect ratio was 17, and the carboxyl group content was 1.1 mmol/g.
Next, the fine cellulose fiber dispersion was charged into a beaker equipped with a magnetic stirrer and a stirrer. Subsequently, dodecylamine was added in an amount equivalent to 1.2 mol of amino groups per 1 mol of carboxyl groups of the fine cellulose fibers, 0.34 g of 4-methylmorpholine, and a condensing agent of 4-(4,6-dimethoxy-1, 1.98 g of 3,5-triazin-2-yl)-4-methylmorpholinium chloride (hereinafter referred to as DMT-MM) was charged and dissolved in 300 g of N,N-dimethylformamide (hereinafter referred to as DMF). . The reaction solution was allowed to react at room temperature (25°C) for 14 hours. After completion of the reaction, filtering, washing with ethanol, removing DMT-MM salt, washing with DMF, and replacing the solvent yielded CNF/DMF in which aliphatic hydrocarbon groups were linked to fine cellulose fibers via amide bonds. A dispersion was obtained. The solid content concentration of the obtained CNF/DMF dispersion was 2.2% by mass.

<Preparation of organic-inorganic composite particles 1>
・Raw material Silica particles (SQ-C6 manufactured by Admatex Co., Ltd., average particle size 500 nm): 15 g
Toluene (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., SP value 9.14): 36 g
Glycidyl methacrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd., SP value 10.21): 0.3 g
Azo polymerization initiator V65 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., 2,2'-azobis(2,4-dimethylvaleronitrile)): 27 mg

・Manufacturing method The above raw materials toluene, glycidyl methacrylate, and azo polymerization initiator are weighed out in a container and stirred to prepare a treatment solution.Then, separately weighed silica particles as the above raw materials are immersed in the treatment solution, and the mixture is heated in a nitrogen atmosphere. The mixture was reacted at 60° C. for 20 hours. The reactant was removed by filtration, washed with propylene glycol monomethyl ether acetate (manufactured by Sankyo Kagaku Co., Ltd.) to completely remove remaining monomers and polymers not covering the surface of the inorganic particles, and then dried at 80°C. It was dried in a furnace for 5 hours to obtain organic-inorganic composite particles 1, which are inorganic particles coated with a glycidyl methacrylate polymer. By performing FT-IR measurement on the organic-inorganic composite particles, a peak derived from a carbonyl group was confirmed, and it was confirmed that the inorganic particles were coated with a glycidyl methacrylate polymer. Further, the organic-inorganic composite particles were subjected to TG/DTA measurement, and it was confirmed from the weight loss that 96% of the glycidyl methacrylate coated the inorganic particles as a polymer.

<Preparation of organic-inorganic composite particles 2>
・Raw material Silica particles (SQ-C6 manufactured by Admatex Co., Ltd., average particle size 500 nm): 15 g
Toluene (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., SP value 9.14): 36 g
2-Hydroxyethyl acrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd., SP value 12.45): 0.3 g
Azo polymerization initiator V65 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., 2,2'-azobis(2,4-dimethylvaleronitrile)): 27 mg

・Manufacturing method The above raw materials toluene, 2-hydroxyethyl acrylate, and azo polymerization initiator are weighed into a container and stirred to prepare a treatment solution, and then the separately weighed raw materials silica particles are immersed in the treatment solution. The reaction was carried out at 60° C. for 20 hours under a nitrogen atmosphere. The reactant was removed by filtration, washed with propylene glycol monomethyl ether acetate (manufactured by Sankyo Kagaku Co., Ltd.) to completely remove remaining monomers and polymers not covering the surface of the inorganic particles, and then dried at 80°C. The particles were dried in a furnace for 5 hours to obtain organic-inorganic composite particles 2, which were inorganic particles coated with a polymer of 2-hydroxyethyl acrylate. By performing FT-IR measurement on the organic-inorganic composite particles, a peak derived from a carbonyl group was confirmed, and it was confirmed that the inorganic particles were coated with a 2-hydroxyethyl acrylate polymer. Further, the organic-inorganic composite particles were subjected to TG/DTA measurement, and it was confirmed from the weight loss that 96% of the 2-hydroxyethyl acrylate coated the inorganic particles as a polymer.

<Preparation of curable resin composition>
The curable resin compositions of Examples and Comparative Examples were prepared by mixing and stirring the respective components and kneading them using a three-roll mill in accordance with the description in Table 1 below. The numerical values in Table 1 indicate parts by mass.

<Thermal expansion coefficient (α1 and α2)>
The compositions of each example and comparative example were applied to a 38 μm thick PET film using an applicator so that the film thickness after curing would be 55 μm, and dried at 90 ° C. for 10 minutes in a hot air circulation drying oven. A dry film having a resin layer of each composition was obtained. Thereafter, the resin layer of each composition was laminated by pressing onto a copper foil having a thickness of 18 μm using a vacuum laminator at 60° C. and a pressure of 0.5 MPa for 60 seconds, and the PET film was peeled off. Next, it was cured by heating at 180° C. for 30 minutes in a hot air circulation drying oven and peeled off from the copper foil to obtain a film sample consisting of a cured product of each composition. The obtained film sample was cut into a size of 3 mm width x 30 mm length, and was used as a test piece for measuring the coefficient of thermal expansion.

This test piece was heated at 5°C/min from 20 to 250°C in a nitrogen atmosphere using TMA (Thermomechanical Analysis) Q400 manufactured by TA Instruments in tensile mode with a chuck distance of 16 mm and a load of 30 mN. The temperature was then lowered from 250 to 20°C at a rate of 5°C/min, and the coefficients of thermal expansion α1 and α2 (ppm/K) were measured. α1 was the average value of the coefficient of thermal expansion during the temperature decreasing process from 50°C to 30°C, and α2 was the average value of the thermal expansion coefficient during the temperature decreasing process from 200°C to 150°C. α1 was evaluated as ◎ when it was less than 23, ◯ when it was 23 or more and less than 26, △ when it was 26 or more and less than 30, and × when it was 30 or more. α2 was evaluated as ◎ when it was less than 60, ◯ when it was 60 or more and less than 70, △ when it was 70 or more and less than 100, and × when it was 100 or more. The results are shown in Table 1.

<Tensile elongation at break>
For the compositions of each Example and Comparative Example, the cured coating film prepared in the thermal expansion coefficient evaluation was cut into 5 mm x 10 cm to prepare test pieces for evaluation. Regarding this test piece, the elongation [%] at the break point was measured using a small tabletop testing machine EZ-SX manufactured by Shimadzu Corporation at a tensile speed of 10 mm/min. Those with an elongation [%] at break of 5% or more were evaluated as ◎, those with an elongation of 4% or more but less than 5% were evaluated as ○, and those with an elongation of less than 4% were evaluated as ×. The results are shown in Table 1 below.

<Dispersibility>
For the compositions of each example and comparative example, cross-sections of the cured coating films prepared for thermal expansion coefficient evaluation were carried out using HITACHI's IM4000PLUS ion milling device, and a 2 nm cross-section was formed using Meiwaforsys' carbon coater CADE. Coated with carbon film. This sample was observed using a JEOL JSM-6010PLUS/LV scanning electron microscope at an accelerating voltage of 10 kV to evaluate dispersibility. The dispersibility was evaluated by comparing the photographs of the fractured surfaces of each cured film sample using the photographs in FIGS. 1(a) to (d) as a reference, and taking the closest one as the dispersibility. The results are shown in Table 1 below.
◎: Same level as Figure 1(a) ○: Same level as Figure 1(b) △: Same level as Figure 1(c) ×: Same level as Figure 1(d)

Epoxy resin 1: JER828 manufactured by Mitsubishi Chemical Corporation Bisphenol A type cyclic ether compound epoxy resin 2: NC-7300 manufactured by Nippon Kayaku Co., Ltd. Cyclic ether compound epoxy resin with a naphthalene skeleton 3: EPICLON HP-7200 manufactured by DIC Corporation Dicyclopentadiene skeleton cyclic ether compound epoxy resin 4: EPICLON 830 manufactured by DIC Corporation Bisphenol F type cyclic ether compound phenol resin: HF4M Phenol novolac resin diamine compound manufactured by Meiwa Kasei Co., Ltd.: KAYAHARD AA Nippon Kayaku Co., Ltd. ) Aromatic diamine compound curing catalyst: 2E4MZ (2-ethyl-4-methyl-imidazole)
Organic-inorganic composite particle 1: GMA (glycidyl methacrylate) coated silica Organic-inorganic composite particle 2: HEA (2-hydroxyethyl acrylate) coated silica Silica particle: Adma Fine SO-C2 Manufactured by Admatex Co., Ltd.

As detailed above, the cured product of the curable resin composition containing the epoxy resin, the curing agent, the organic-inorganic composite particles, and the cellulose nanofibers contains the organic-inorganic composite particles and It was confirmed that cellulose nanofibers have excellent dispersibility, and the cured product can have low thermal expansion and toughness.

Claims (5)

A curable resin composition comprising an epoxy resin, a curing agent, organic-inorganic composite particles, and cellulose nanofibers,
The organic-inorganic composite particles are coated with 1.5% by mass or more of a polymer based on 100% by mass of the inorganic particles,
A curable resin composition, wherein the polymer is a polymer or copolymer of a (meth)acrylic monomer. The curable resin composition according to claim 1, wherein the (meth)acrylic monomer includes a (meth)acrylic monomer containing a hydroxyl group and/or a cyclic ether group. A dry film comprising a resin layer formed by applying and drying the curable resin composition according to claim 1 or 2 on a base material. A cured product obtained by curing the curable resin composition according to claim 1 or 2 or the resin layer according to claim 3. An electronic component comprising the cured product according to claim 4.