JP7770912B2 - Epoxy resin composition, film material, and cured product - Google Patents

Description

The present invention relates to an epoxy resin composition, a film material, and a cured product.

Epoxy resins have excellent properties in a variety of areas, including curability, electrical insulation, mechanical properties, thermal properties, chemical resistance, and adhesive properties, and have traditionally been used in a wide range of applications, including as insulating materials, sealing materials, adhesives, conductive materials, and thermally conductive materials for electrical and electronic components, as well as matrix resins for fiber-reinforced plastics.

In recent years, as electronic materials have become smaller and thinner, film materials using epoxy resin compositions have become increasingly important in order to make adhesive and insulating layers thinner. A known method for obtaining film materials using such epoxy resin compositions involves preparing a coating liquid containing an epoxy resin composition in which components such as an epoxy resin, a curing agent, a curing accelerator, and a thermoplastic resin are dissolved in a solvent, applying the coating liquid to a specified support, and then drying the coating liquid to obtain a film material.

As an example of an epoxy resin composition, Patent Document 1 discloses a thermosetting epoxy resin composition that is excellent in thin film formability, storage stability, and curability by using a solvent-soluble imidazole that does not contain a benzene ring as a curing accelerator.
Furthermore, Patent Document 2 discloses an epoxy resin composition that has excellent curing latency by using a pyridine compound or imidazole compound having a specific structure as a curing accelerator.
Furthermore, Patent Document 3 discloses a method for producing an epoxy resin composition that is a film-like circuit connecting material that is excellent in heat resistance, moisture resistance, and workability, by using a latent curing agent, particularly a microcapsule-type latent curing agent, as a curing agent.

JP 2020-152780 A Patent No. 5915610 Patent No. 5013028

The epoxy resin composition used to obtain the above-mentioned film material must be stable as a coating liquid during the production process, and stable when the coating liquid is applied and dried. Furthermore, the formed film material must be stable during storage to prevent hardening from progressing during storage. It is also desirable for the stored film to maintain sufficient adhesive strength for practical use to the specified substrate, such as copper, in order to ensure high reliability as an adhesive material.

In recent years, film materials have become known that incorporate polyimides or other polymers with rigid backbones containing aromatic rings into a specific resin composition to improve the heat resistance of the resulting film. However, polyimides and polymers with rigid backbones generally have low solubility in solvents, and so the use of solvents with high dissolving power and high boiling points is becoming more common. When an epoxy resin composition is obtained by incorporating polyimides or polymers with rigid backbones using such solvents with high dissolving power and high boiling points, it is expected that the epoxy resin composition will be dried at higher temperatures than conventional methods in order to reduce residual solvent and shorten working time. Therefore, epoxy resin compositions are required to be stable during high-temperature drying, have storage stability for film materials, and maintain adhesiveness.

A solvent-soluble curing accelerator is used in the epoxy resin compositions disclosed in Patent Documents 1 and 2. This is because a solvent-soluble curing accelerator is selected as being suitable from the viewpoint of the uniformity of the coating film, etc.
However, when a solvent-soluble curing accelerator is used in an epoxy resin composition, the curing accelerator becomes molecularly dispersed in the epoxy resin composition, and if the curing accelerator itself is highly reactive, the curing reaction proceeds during high-temperature drying or storage of the film material. Conversely, if the reactivity of the curing accelerator itself is reduced, high-temperature drying resistance and storage stability are improved, but the reactivity as a film material is reduced. In other words, the epoxy resin compositions using solvent-soluble curing accelerators disclosed in Patent Documents 1 and 2 have the problem that it is difficult to achieve both stability during high-temperature drying and storage and reactivity as a film material.
Furthermore, the film material obtained by the manufacturing method of the film-shaped circuit connecting material described in Patent Document 3 also has the same problem as above, that there is room for improvement in terms of achieving both stability during high-temperature drying and storage and reactivity as a film material.

In view of the problems of the prior art described above, the present invention aims to provide an epoxy resin composition that combines stability and reactivity, exhibiting high stability during high-temperature drying, high storage stability in a film form, and excellent curing and adhesive properties.

As a result of extensive research, the present inventors have found that the above object can be achieved by the following technical means, and have thus completed the present invention.
That is, the present invention is as follows.

[1]
(A) an epoxy resin;
(B) at least one first curing agent selected from the group consisting of an active ester curing agent, an amide curing agent, and a phenolic resin curing agent;
(C) a second curing agent that is a solvent-insoluble, solid, and microcapsule-type curing agent that is a latent curing agent ;
An epoxy resin composition comprising:
the second curing agent comprises a reactive diluent;
the reactive diluent is an epoxy compound having an aromatic ring, the aromatic ring being a monocyclic and monofunctional epoxy compound;
the content of the reactive diluent is 2 mass% or less based on the solid content of the epoxy resin composition;
Epoxy resin composition.
[2]
The epoxy resin composition according to [1] above, further comprising (D) a thermoplastic resin.
[3]
The epoxy resin composition according to [1] or [2] above, which is an epoxy resin composition for forming a film.
[4]
A support;
a resin layer formed on the support;
and
The resin layer contains the epoxy resin composition according to any one of [1] to [3] above.
Film material.
[5]
A cured product of the epoxy resin composition according to any one of [1] to [3] above, or the resin layer of the film material according to [4] above.

The present invention provides an epoxy resin composition that exhibits high stability during high-temperature drying, high storage stability in a film form, and excellent curability and adhesive properties.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail.
The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[Epoxy resin composition]
The epoxy resin composition of the present embodiment comprises:
Component (A): an epoxy resin;
Component (B): at least one first curing agent selected from the group consisting of active ester curing agents, amide curing agents, and phenolic resin curing agents;
Component (C): at least one second curing agent which is solvent-insoluble and solid and is selected from the group consisting of imidazole derivatives, urea derivatives, and microcapsule-type curing agents;
Includes.

(Component (A): Epoxy resin)
The epoxy resin composition of the present embodiment contains an epoxy resin (hereinafter, may be referred to as an (A) epoxy resin or component (A)).
(A) Epoxy resins include, but are not limited to, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol M type epoxy resins, bisphenol P type epoxy resins, tetrabromobisphenol A type epoxy resins, biphenyl type epoxy resins, tetramethylbiphenyl type epoxy resins, tetrabromobiphenyl type epoxy resins, diphenyl ether type epoxy resins, benzophenone type epoxy resins, phenyl benzoate type epoxy resins, diphenyl sulfide type epoxy resins, diphenyl sulfoxide type epoxy resins, diphenyl sulfone type epoxy resins, diphenyl disulfide type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, hydroquinone type epoxy resins, methyl hydrochloride type epoxy resins, methyl hydroxybenzoates ... Examples of epoxy resins include bifunctional epoxy resins such as quinone-type epoxy resins, dibutylhydroquinone-type epoxy resins, resorcinol-type epoxy resins, methylresorcinol-type epoxy resins, and catechol-type epoxy resins; trifunctional epoxy resins such as N,N-diglycidylaminobenzene-type epoxy resins and triazine-type epoxy resins; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane-type epoxy resins and diaminobenzene-type epoxy resins; polyfunctional epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, triphenylmethane-type epoxy resins, tetraphenylethane-type epoxy resins, dicyclopentadiene-type epoxy resins, naphthol aralkyl-type epoxy resins, and brominated phenol novolac-type epoxy resins; and alicyclic epoxy resins.
These may be used alone or in combination of two or more.
Furthermore, epoxy resins modified with isocyanate or the like can also be used in combination.

From the viewpoints of handleability and heat resistance, the epoxy resin composition of this embodiment preferably contains a bisphenol-type epoxy resin as component (A), and from the viewpoint of imparting sufficient mechanical properties, it preferably contains a bisphenol A-type epoxy resin.

(Component (B): First Curing Agent)
The epoxy resin composition of the present embodiment contains at least one first curing agent (hereinafter, may be referred to as (B) first curing agent, or component (B)) selected from the group consisting of (B1) active ester curing agents, (B2) amide curing agents, and (B3) phenolic resin curing agents.
By including the first curing agent (B), the dielectric properties, strength, and heat resistance of the film can be improved.
Furthermore, since the reactivity of these (B) first curing agents alone is low, by appropriately selecting the component (C) second curing agent described below, the epoxy resin composition of the present embodiment can be imparted with high-temperature drying resistance and can improve the storage stability of the resulting film while maintaining good curability.
The component (C) described below functions as a curing accelerator.

(Component (B1): Active ester curing agent)
The active ester curing agent (B1) is not particularly limited as long as it functions as a curing agent for the epoxy resin (A) and has an active ester, but a compound having two or more active ester groups in one molecule is preferred.
From the viewpoint of heat resistance and the like, an active ester compound obtained by reacting a carboxylic acid compound and/or a thiocarboxylic acid compound with a hydroxy compound and/or a thiol compound is more preferred, and an active ester compound obtained by reacting a carboxylic acid compound with one or more compounds selected from the group consisting of a phenol compound, a naphthol compound, and a thiol compound is even more preferred.
Furthermore, aromatic compounds having two or more active ester groups in one molecule, which are obtained by reacting a carboxylic acid compound with an aromatic compound having a phenolic hydroxyl group, are even more preferred.
Furthermore, an aromatic compound obtained by reacting a compound having at least two carboxylic acids in one molecule with an aromatic compound having a phenolic hydroxyl group, and having two or more active ester groups in one molecule of the aromatic compound, is even more preferred.

The compound constituting the active ester curing agent (B1) may be either linear or multi-branched.
Furthermore, if the compound having at least two or more carboxylic acids in one molecule is a compound containing an aliphatic chain, the compatibility of the (B1) active ester curing agent obtained using this compound with the (A) epoxy resin can be increased, and if the compound having at least two or more carboxylic acids in one molecule is a compound having an aromatic ring, the heat resistance of the resulting cured product can be increased.

The carboxylic acid compound used to form the (B1) active ester curing agent includes, but is not limited to, benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. In particular, from the viewpoint of enhancing the heat resistance of the resulting cured product, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, and terephthalic acid are preferred, with isophthalic acid and terephthalic acid being more preferred.

The thiocarboxylic acid compound used to form the (B1) active ester curing agent includes, but is not limited to, thioacetic acid, thiobenzoic acid, etc.

Furthermore, examples of the phenol compound or naphthol compound used to form the (B1) active ester curing agent include, but are not limited to, hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadienyl diphenol, and phenol novolak.
In particular, from the viewpoint of the solubility of the active ester curing agent and the heat resistance of the obtained cured product, bisphenol A, bisphenol F, bisphenol S, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadienyldiphenol, and phenol novolak are preferred, and catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadienyldiphenol, and phenol novolak are preferred. More preferred are 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, dicyclopentadienyl diphenol, and phenol novolac, still more preferred are dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, dicyclopentadienyl diphenol, and phenol novolac, still more preferred are dicyclopentadienyl diphenol and phenol novolac, and particularly preferred is dicyclopentadienyl diphenol.

The thiol compound used to form the (B1) active ester curing agent includes, but is not limited to, benzenedithiol, triazinedithiol, etc.

The active ester compound constituting the active ester curing agent (B1) may be used alone or in combination of two or more.
As the active ester compound, the active ester compounds disclosed in JP-A-2004-277460 may be used, or commercially available compounds may also be used.
Commercially available active ester compounds include, for example, those containing a dicyclopentadienyldiphenol structure, acetylated phenol novolac, and benzoated phenol novolac, and more preferably those containing a dicyclopentadienyldiphenol structure. Examples of those containing a dicyclopentadienyldiphenol structure include, but are not limited to, EXB9451, EXB9460, EXB9460S, and HPC-8000-65T (manufactured by DIC Corporation), DC808 (manufactured by Japan Epoxy Resins Co., Ltd.) as an acetylated phenol novolac, and YLH1026 (manufactured by Japan Epoxy Resins Co., Ltd.) as a benzoated phenol novolac.

In the epoxy resin composition of the present embodiment, the content of the active ester curing agent (B1) in the solid content is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of electrical properties.
From the viewpoint of foldability after film formation, the content is preferably 40% by mass or less, and more preferably 35% by mass or less.

(Component (B2): Amide-based curing agent)
The (B2) amide-based curing agent is not particularly limited as long as it can cure the (A) epoxy resin, but examples include dicyandiamide having four active hydrogens and its derivative, a guanidine compound, or an amine-based curing agent to which an acid anhydride is added, and a hydrazide-based compound.

Hydrazide-based curing agents made from hydrazide compounds include, but are not limited to, succinic acid dihydrazide, adipic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, p-oxybenzoic acid hydrazide, salicylic acid hydrazide, phenylaminopropionic acid hydrazide, and maleic acid dihydrazide.

Guanidine-based curing agents made from guanidine compounds include, but are not limited to, dicyandiamide, methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, and toluylguanidine.

Among the above-mentioned (B2) amide-based curing agents, from the viewpoint of increasing the number of crosslinking points, thereby making the crosslinked structure more complex, and improving the strength of the cured product, it is preferable that the (B2) amide-based curing agent contains a compound containing four or more active hydrogen atoms, such as dicyandiamide.

The content of the amide curing agent (B2) in the solid content of the epoxy resin composition of the present embodiment is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more, from the viewpoint of strength of the cured product.
From the viewpoint of coating film uniformity, the content is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

(Component (B3): Phenolic resin-based curing agent)
The (B3) phenolic resin-based curing agent is not particularly limited as long as it can cure the (A) epoxy resin, but examples thereof include phenol novolak, bisphenol A novolak, cresol novolak, naphthol novolak, and triazine ring-containing phenol novolak.
From the viewpoint of the dielectric loss tangent of the resulting cured product, triazine ring-containing phenol novolaks are preferred, and specific examples include LA-3018, LA-3018-50P, EXB9808, and EXB9829 (manufactured by DIC Corporation).

From the viewpoint of the curability of the epoxy resin composition of the present embodiment, the content of the phenolic resin curing agent (B3) in the solid content of the epoxy resin composition of the present embodiment is preferably 2.0 mass% or more, more preferably 3.0 mass% or more, and even more preferably 4.0 mass% or more.
Furthermore, from the viewpoint of the stability of the epoxy resin composition of the present embodiment, the content is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

(Component (C): Second Curing Agent)
The epoxy resin composition of the present embodiment is a solvent-insoluble solid and contains at least one second curing agent (hereinafter, may be referred to as (C) second curing agent, component (C)) selected from the group consisting of (C1) imidazole derivatives, (C2) urea derivatives, and (C3) microcapsule-type curing agents.
In this specification, the term "solid" refers to a substance that has the properties of a solid at room temperature (25°C).
Furthermore, in the case where component (C) is a masterbatch in which it is dispersed in an epoxy resin, it is considered to be solid if it contains a solid core.
In this specification, "solvent-insoluble" means being insoluble in all of the following solvents: toluene, ethyl acetate, methyl ethyl ketone (MEK), cyclohexanone, and propylene glycol monomethyl ether acetate (PGMEA). In this embodiment, when the second curing agent (C) is added to the solvent, the soluble concentration of the second curing agent (C) is less than 3 mass %, i.e., the second curing agent (C) does not dissolve in the solvent at a concentration of 3 mass % or more.

The second curing agent (C) is preferably a latent curing agent.
Since the second curing agent (C) is a solvent-insoluble, solid latent curing agent, the epoxy resin composition of the present embodiment can improve high-temperature drying resistance and storage stability while also ensuring reactivity. The mechanism behind this is thought to be, but is not intended to be limiting, as follows.
Since solvent-insoluble, solid latent curing agents undergo dissolution or decomposition from a solid dispersion state upon heating, a reaction begins after a grace period. In addition, during the solvent drying process, the applied thermal energy is used as the latent heat of vaporization of the solvent, resulting in an additional grace period before the internal temperature of the epoxy resin composition reaches the set drying temperature. Because the heating time required for the drying process is short compared to the curing reaction time, utilizing this grace period allows the solid dispersion state to be maintained, making it possible to prevent the progress of the curing reaction even during drying. Furthermore, since the solid dispersion state is maintained even after drying, the storage stability of films made from the epoxy resin of this embodiment can be improved. Meanwhile, during the curing reaction, the solid state changes to a highly reactive molecular dispersion state through dissolution and decomposition, ensuring reactivity.
In this embodiment, among these solvent-insoluble, solid latent curing agents, the microcapsule-type curing agent (C3) is preferred because it has an excellent balance between the grace period and reactivity.

(Component (C1): Imidazole derivative)
The imidazole derivative (C1) may be any one that is insoluble in a solvent and solid, and among these, imidazole adducts are preferred from the viewpoint of storage stability.
Examples of the imidazole adduct include compounds obtained by reacting an imidazole compound with a carboxylic acid compound, a sulfonic acid compound, a urea compound, an isocyanate compound, or an epoxy resin.

Examples of the carboxylic acid compound include, but are not limited to, succinic acid, adipic acid, sebacic acid, phthalic acid, and dimer acid.
The sulfonic acid compound is not limited to the following, but examples thereof include ethanesulfonic acid and p-toluenesulfonic acid.
Examples of the urea compound include, but are not limited to, urea, methyl urea, dimethyl urea, ethyl urea, and t-butyl urea.

The isocyanate compound is not limited to the following, but examples thereof include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aliphatic triisocyanates, and polyisocyanates.
Examples of the aliphatic diisocyanate include, but are not limited to, ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate.
Examples of alicyclic diisocyanates include, but are not limited to, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane, and 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane.
Examples of aromatic diisocyanates include, but are not limited to, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, and 1,5-naphthalene diisocyanate.
Examples of the aliphatic triisocyanate include, but are not limited to, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, and 1,3,6-triisocyanate methyl hexane.
Examples of polyisocyanates include, but are not limited to, polymethylene polyphenyl polyisocyanate and polyisocyanates derived from the diisocyanate compounds, such as isocyanurate polyisocyanates, biuret polyisocyanates, urethane polyisocyanates, allophanate polyisocyanates, and carbodiimide polyisocyanates.

Examples of epoxy resins include the compounds described above under ((A) Epoxy resin).

Imidazole compounds include, but are not limited to, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, and 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole.

Additionally, commercially available curing agents containing imidazole adducts can also be used as imidazole compounds. Examples of such curing agents include, but are not limited to, Amicure PN-23, PN-23J, PN-40, and PN-40J (manufactured by Ajinomoto Fine-Techno Co., Inc.). PN-40 and PN-40J are particularly preferred due to their excellent dispersibility in solvents.

(Component (C2): urea derivative)
The urea derivative (C2) may be any one that is insoluble in a solvent and is solid, and includes, but is not limited to, 3,4-dichlorophenyl-N,N-dimethylurea (DCMU), 3-(4-chlorophenyl)-1,1-dimethylurea, etc. In particular, 3,4-dichlorophenyl-N,N-dimethylurea (DCMU) is preferred because it has an excellent balance between cure acceleration and stability.

(Component (C3): Microcapsule-type curing agent)
The microcapsule-type curing agent (C3) may be any agent as long as it is solvent-insoluble and solid, and is preferably one containing a reactive diluent (c1) described below as a component from the viewpoint of solvent resistance.
Here, the microcapsule-type curing agent (C3) is a curing agent having at least a core containing a curing agent component and a shell covering the core, and also includes a masterbatch-type curing agent containing an epoxy resin. Note that the term "solvent-insoluble and solid" in the microcapsule-type curing agent (C3) means that the core and/or shell are solvent-insoluble and solid.
Furthermore, the phrase "containing a reactive diluent as a component" means that the reactive diluent is contained in at least one component of the core, shell, or, in the case of a masterbatch type, epoxy resin to be dispersed, which are components of the microcapsule-type curing agent. In particular, from the viewpoint of solvent resistance, it is preferable that the reactive diluent is contained in at least the shell.

The core constituting the (C3) microcapsule-type curing agent may be any curing agent used in epoxy resins, and is not particularly limited. Examples include amine-based curing agents, amide-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, catalyst-based curing agents, and modified versions of these. These may be used alone or in combination of two or more types. From the standpoint of storage stability, amine adducts are preferred among amine-based curing agents.

The particle size of the core constituting the microcapsule-type curing agent (C3) is preferably an average particle size defined as the median size of more than 0.3 μm and not more than 12 μm, more preferably 1.0 μm or more and 10 μm or less, and even more preferably 1.5 μm or more and 5.0 μm or less.
Here, the average particle size refers to the Stokes diameter measured by a laser diffraction/light scattering method. When the average particle size is 12 μm or less, a homogeneous cured product tends to be obtained, and when the particle size is more than 0.3 μm, aggregation between particles can be suppressed, and a thin shell tends to be easily formed.

The shell constituting the microcapsule-type curing agent (C3) preferably has, at least on its surface, a bonding group that absorbs infrared rays with a wave number of 1630 to 1680 cm ⁻¹ , a bonding group that absorbs infrared rays with a wave number of 1680 to 1725 cm ⁻¹ , and a bonding group that absorbs infrared rays with a wave number of 1730 to 1755 ^cm −1 . This reduces the aggregation rate of curing agent particles, and tends to result in excellent curability and storage stability.

((c1) Reactive Diluent)
From the viewpoint of solvent resistance, the microcapsule-type curing agent (C3) preferably contains a reactive diluent (c1), which is a compound having a reactive functional group that can be incorporated into the cured structure, such as an epoxy group or an acrylic group.

(c1) The reactive diluent is not limited to the following, but examples thereof include acrylate compounds and epoxy compounds that can reduce viscosity without impairing reactivity.
In this specification, compounds excluding the compounds exemplified in the above-mentioned (A) epoxy resin and having a viscosity at 25°C of 1 mPa·s or more and less than 3 Pa·s are defined as (c1) reactive diluents.
In the epoxy resin composition of the present embodiment, the reactive diluent (c1) is preferably an epoxy compound, from the viewpoints of its compatibility with the epoxy resin (A) described above and its incorporation into the cured structure after the reaction.

(c1) Examples of acrylate compounds used as reactive diluents include, but are not limited to, compounds having (meth)acryloyl groups at both ends of a polyalkylene oxide, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, trimethylolpropane-type multifunctional (meth)acrylate, pentaerythritol-type multifunctional (meth)acrylate, and dipentaerythritol-type multifunctional (meth)acrylate.

(c1) The epoxy compound used as the reactive diluent is not limited to the following, but examples thereof include the following epoxy compounds having no aromatic ring and epoxy compounds having an aromatic ring.
Examples of monofunctional epoxy compounds having no aromatic ring include compounds such as n-butyl glycidyl ether, t-butyl glycidyl ether, allyl glycidyl ether, and 2-ethylhexyl glycidyl ether.
Examples of monofunctional epoxy compounds having an aromatic ring include styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether, t-butylphenyl glycidyl ether, and compounds such as SY-OPG (trade name) manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.
Examples of bifunctional epoxy compounds having no aromatic ring include 1,4-cyclohexanedimethanol diglycidyl ether, 1,3-cyclohexanedimethanol diglycidyl ether, (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, dicyclopentadiene dimethanol diglycidyl ether, vinylcyclohexene dioxide, and compounds such as Mitsubishi Chemical Corporation (trade name: YX-8000) and Sakamoto Yakuhin Kogyo Co., Ltd. (trade name: SR-8EGS).
Examples of bifunctional epoxy compounds having one or more aromatic rings include hexahydrophthalic acid diglycidyl ether, resorcinol diglycidyl ether, tert-butylhydroquinone diglycidyl ether, diglycidyl ether of polyoxyalkylene bisphenol A, N,N-diglycidylaniline, and N,N-diglycidyl-o-toluidine.
Examples of trifunctional epoxy compounds include trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, and N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline.

In the epoxy resin composition of this embodiment, it is preferable that the reactive diluent (c1) has an aromatic ring from the viewpoint of enhancing solvent resistance, and it is more preferable that the reactive diluent (c1) is an epoxy compound having the aromatic ring, the aromatic ring being monocyclic and monofunctional, from the viewpoint of further enhancing the solvent resistance of the microcapsule-type curing agent (C3).
Furthermore, it is even more preferable that the monofunctional group is an epoxy group, from the viewpoint of exhibiting sufficient mechanical strength by being incorporated into the cured product after the reaction.
Furthermore, it is more preferable that the number of carbon atoms in each substituent on the aromatic ring is 3 or less, from the viewpoint of improving penetration into the capsule membrane and solvent resistance, as will be described later.

The mechanism by which the (c1) reactive diluent is a monocyclic aromatic compound and a monofunctional compound as described above improves solvent resistance is thought to be as follows, although it is not intended to be limiting.
When the reactive diluent (c1) has an aromatic ring, the aromatic rings of the reactive diluent compound incorporated into the shell exhibit a stacking effect to form a network, thereby enhancing the cohesive strength of the shell, thereby constructing a shell that is resistant to swelling in solvents, and improving the solvent resistance of the microcapsule-type curing agent (C3).
In addition, since the aromatic ring of (c1) reactive diluent is a monocyclic and monofunctional compound, steric hindrance is small, which facilitates penetration into the interior of the shell and allows for the formation of a denser and wider simultaneous stacking network of aromatic rings. Here, since the number of carbon atoms of each substituent of the aromatic ring is 3 or less, steric hindrance is further reduced, which enhances penetration into the interior of the shell and further improves solvent resistance.
The above-mentioned mechanism significantly improves solvent resistance compared to conventional microcapsule-type curing agents that do not contain reactive diluents. In addition, the number of applicable solvents increases, which broadens the options for (A) epoxy resins and (D) thermoplastic resins (described below) that can be used in film materials, making it easier to impart desired physical properties to film materials.

(C3) Commercially available products can also be used as the microcapsule-type curing accelerator. Examples of commercially available products that contain a reactive diluent include, but are not limited to, Novacure LSA-H2104 (manufactured by Asahi Kasei Corporation, which contains phenyl glycidyl ether as a reactive diluent). Additionally, products from the Novacure series (manufactured by Asahi Kasei Corporation), such as Novacure HX-3742, HX-3088, HXA3792, HXA9322HP, and HXA9382HP, which do not contain a reactive diluent, can also be used. Microcapsule-type curing agents containing a reactive diluent made using these products are also included in embodiments of the present invention.

When the microcapsule-type curing agent (C3) is a masterbatch, the content of the reactive diluent (c1) in the microcapsule-type curing agent (C3) is preferably 3% by mass or more, more preferably 4% by mass or more, even more preferably 5% by mass or more, and even more preferably 6% by mass or more in the masterbatch from the viewpoint of imparting sufficient solvent resistance. Also, from the viewpoint of preventing excessive viscosity reduction, deterioration of storage stability, and reduction in mechanical strength of the cured product, the content is preferably 15% by mass or less, more preferably 13% by mass or less, even more preferably 12% by mass or less, and even more preferably 11% by mass or less.
When the reactive diluent (c1) is added during the production of the epoxy resin composition of this embodiment, the content of the reactive diluent in the solid content is preferably 0.05% by mass or more from the viewpoint of imparting solvent resistance, and is preferably 2% by mass or less, more preferably 1% by mass or less from the viewpoint of storage stability.

In the epoxy resin composition of this embodiment, the content of the second curing agent (C) in the solids is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more, from the viewpoint of curability. Furthermore, from the viewpoint of coating film uniformity, it is preferably 14% by mass or less, more preferably 13% by mass or less, and even more preferably 12% by mass or less.

When used in combination with the first curing agent (B), the second curing agent (C) also functions as a curing accelerator. In other words, it complements the curing achieved by the first curing agent (B), allowing the epoxy resin composition of this embodiment to exhibit even better curing properties.

(Component (D): thermoplastic resin)
The epoxy resin composition of the present embodiment may further contain (D) a thermoplastic resin (hereinafter sometimes referred to as component (D)).
By including the thermoplastic resin (D) in the epoxy resin composition of the present embodiment, when the epoxy resin composition is cast or applied to a predetermined thickness and dried to form a film-like molded article, cracks and breaks can be prevented and the film shape can be maintained.
Examples of the thermoplastic resin (D) include, but are not limited to, phenoxy resin, polyvinyl butyral resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyimide resin, polyamide-imide resin, polyether sulfone resin, polyphenylene ether resin, polysulfone resin, and elastomers having functional groups such as carboxyl groups, hydroxyl groups, vinyl groups, and amino groups.
The thermoplastic resin used in the epoxy resin composition of the present embodiment is also called a film-forming polymer or a binder polymer.

As the thermoplastic resin (D), a phenoxy resin is preferred because of its excellent long-term reliability.
Here, "long-term reliability" means that when applied to sealing materials, insulating materials, and adhesives for electric and electronic components, the desired sealing performance, insulating performance, adhesive performance, etc. do not easily deteriorate over time.
Examples of phenoxy resins include, but are not limited to, bisphenol A phenoxy resins, bisphenol F phenoxy resins, bisphenol A-bisphenol F mixed phenoxy resins, bisphenol A-biphenyl mixed phenoxy resins, bisphenol A-bisphenol S mixed phenoxy resins, fluorene ring-containing phenoxy resins, and caprolactone-modified bisphenol A phenoxy resins.

The number average molecular weight of the thermoplastic resin (D) is preferably 9,000 to 23,000, more preferably 9,500 to 21,000, and even more preferably 10,000 to 20,000. Here, the number average molecular weight is the number average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter referred to as GPC), and is the average value calculated for the range of polystyrene-equivalent molecular weights of 728 or more.
By setting the number average molecular weight of the (D) thermoplastic resin to 9,000 or more, it is possible to prevent the (D) thermoplastic resin from slipping through the crosslinked structure of the cured (A) epoxy resin, and to prevent a decrease in the cohesive strength of the cured product, which is preferable because it prevents a decrease in long-term reliability.
On the other hand, by making the number average molecular weight 23,000 or less, the adhesive film obtained from the epoxy resin composition of the present embodiment can maintain high adhesion to the adherend, such as a substrate or an IC chip, and can suppress the occurrence of localized curing defects during connection, prevent the occurrence of corrosion of wiring and electrodes, and obtain high insulation reliability, which are therefore preferred.

The content of the thermoplastic resin (D) in the epoxy resin composition of this embodiment is preferably 3% by mass or more, more preferably 4% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of preventing cracking after the epoxy resin of this embodiment is formed into a film. Furthermore, from the viewpoint of ease of handling the varnish and ease of film production, the content is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

((E) Solvent)
The epoxy resin composition of the present embodiment may further contain (E) a solvent (hereinafter sometimes referred to as component (E)).
The solvent (E) is not particularly limited, and known solvents can be used. Examples include, but are not limited to, hydrocarbons such as toluene, xylene, cyclohexane, mineral spirits, and solvent naphtha; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol monomethyl ethyl ether acetate; alcohols such as isopropanol, n-butanol, butyl cellosolve, butyl carbitol, and 1-methoxy-2-propanol; and amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. In particular, solvents that have low solubility for the second curing agent (C) and allow uniform dispersion are preferred from the viewpoint of film coatability and stability. From this viewpoint, but not limited to, it is preferable to include at least one solvent selected from toluene, ethyl acetate, methyl ethyl ketone (MEK), cyclohexanone, and propylene glycol monomethyl ether acetate (PGMEA).

The phrase "uniformly dispersible" refers to a state in which, when a solvent is added to an epoxy resin composition containing 30% by mass or more of (C) the second curing agent in an amount of 20% by mass of the total, the mixture is stirred and mixed, and then allowed to stand at room temperature; no agglomerates with a diameter of 2 mm or more are visually observed within 30 minutes.

The content of the (E) solvent in the epoxy resin composition of this embodiment is not particularly limited and can be adjusted appropriately depending on the viscosity, solubility, film coatability, etc. of the resin used.

(Other additives)
In addition to the components (A) to (E) described above, the epoxy resin composition of the present embodiment may further contain, as necessary, a curing agent that does not fall under the category of component (B), and additives such as organic fillers, inorganic fillers, pigments, dyes, flow modifiers, thickeners, release agents, wetting agents, flame retardants, surfactants, and resins.

As for curing agents that do not fall under component (B), there are no particular restrictions and any known curing agents can be used as long as they are used as curing agents for epoxy resins, excluding the curing agents listed in component (B).

The organic filler functions as a shock absorber, capable of mitigating stress generated by impact.
By including an organic filler, the epoxy resin composition of the present embodiment can further improve adhesion to various connecting members and also tends to suppress the occurrence and propagation of fillet cracks.
Examples of organic fillers include, but are not limited to, acrylic resin, silicone resin, butadiene rubber, polyester, polyurethane, polyvinyl butyral, polyarylate, polymethyl methacrylate, acrylic rubber, polystyrene, NBR (acrylonitrile-butadiene rubber), SBR (styrene-butadiene rubber), silicone-modified resin, and organic fine particles of copolymers containing these as components.
From the viewpoint of improving adhesiveness, preferred organic fine particles include, for example, alkyl (meth)acrylate-butadiene-styrene copolymer, alkyl (meth)acrylate-silicone copolymer, silicone-(meth)acrylic copolymer, a complex of silicone and (meth)acrylic acid, a complex of alkyl (meth)acrylate-butadiene-styrene and silicone, and a complex of alkyl (meth)acrylate and silicone.
The organic fine particles may also have a core-shell structure, with the core and shell layers having different compositions. Examples of core-shell organic fine particles include particles having a silicone-acrylic rubber core to which an acrylic resin is grafted, and particles having an acrylic copolymer to which an acrylic resin is grafted.
These organic fillers may be used alone or in combination of two or more.

The inorganic filler can adjust the thermal expansion coefficient of the epoxy resin composition of the present embodiment, and therefore tends to contribute to improving the heat resistance and moisture resistance when the epoxy resin composition of the present embodiment is used as an underfill material.
Examples of inorganic fillers include, but are not limited to, silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as silica oxides such as titanium oxide, aluminum oxide (alumina), fused silica (fused spherical silica, fused crushed silica), synthetic silica, and crystalline silica; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate; sulfites such as calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; and nitrides such as aluminum nitride, boron nitride, and silicon nitride.
Among these, fused silica, crystalline silica, and synthetic silica powder are preferred from the viewpoint of improving heat resistance, moisture resistance, and strength, and silicon oxide, aluminum oxide, and boron nitride are also preferred. Use of these materials can suppress the coefficient of linear thermal expansion, which is expected to improve performance in thermal cycle tests.
The shape of the inorganic filler is not particularly limited, and may be, for example, any of amorphous, spherical, and flaky shapes.
These inorganic fillers may be used alone or in combination of two or more.

Pigments include, but are not limited to, kaolin, aluminum oxide trihydrate, aluminum hydroxide, chalk powder, gypsum, calcium carbonate, antimony trioxide, pentone, silica, aerosol, lithopone, baryte, titanium dioxide, etc.

Dyes include, but are not limited to, natural dyes such as plant-derived dyes such as madder and indigo, mineral-derived dyes such as yellow ochre and red clay, synthetic dyes such as alizarin and indigo, and fluorescent dyes.

Examples of flow control agents include, but are not limited to, organic silane compounds such as silane coupling agents; organic titanium compounds such as titanium tetraisopropoxide and titanium diisopropoxybis(acetylacetonate); and organic zirconium compounds such as zirconium tetra-n-butoxide and zirconium tetraacetylacetonate.

Thickeners include, but are not limited to, animal-based thickeners such as gelatin; plant-based thickeners such as polysaccharides and cellulose; and chemically synthesized thickeners such as polyacrylic thickeners, modified polyacrylic thickeners, polyether thickeners, urethane-modified polyether thickeners, and carboxymethyl cellulose.

Releasing agents include, but are not limited to, fluorine-based releasing agents, silicone-based releasing agents, and acrylic-based releasing agents made from a copolymer of glycidyl (meth)acrylate and a linear alkyl (meth)acrylate ester having 16 to 22 carbon atoms.

Wetting agents include, but are not limited to, unsaturated polyester copolymer wetting agents having acidic groups, such as acrylic polyphosphate esters.

Flame retardants include, but are not limited to, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, halogen-based flame retardants such as chlorine compounds and bromine compounds, phosphorus-based flame retardants such as condensed phosphate esters, antimony-based flame retardants such as antimony trioxide and antimony pentoxide, and inorganic oxides such as silica fillers.

Surfactants include, but are not limited to, anionic surfactants such as alkylbenzene sulfonates and alkyl polyoxyethylene sulfates, cationic surfactants such as alkyldimethylammonium salts, amphoteric surfactants such as alkyldimethylamine oxides and alkylcarboxybetaines, and nonionic surfactants such as linear alcohols and fatty acid esters having 25 or more carbon atoms.

Resins include, but are not limited to, polyester resin, polyurethane resin, acrylic resin, polyether resin, melamine resin, and modified epoxy resins such as urethane-modified epoxy resin, rubber-modified epoxy resin, and alkyd-modified epoxy resin.

[Method for producing epoxy resin composition]
The epoxy resin composition of the present embodiment can be obtained by mixing the above-described (A) epoxy resin, (B) at least one first curing agent selected from the group consisting of active ester-based curing agents, amide-based curing agents, and phenolic resin-based curing agents, and (C) at least one second curing agent that is solvent-insoluble and solid and selected from the group consisting of imidazole derivatives, urea derivatives, and microcapsule-type curing agents.
The mixing method is not particularly limited, and examples thereof include a method using a planetary mixer and a method using a three-roll mill. The various components described above can be thoroughly mixed until homogeneous using a mixing roll such as a three-roll mill, a dissolver, a planetary mixer, a kneader, an extruder, or the like to obtain the composition.

Furthermore, when producing the epoxy resin composition, (D) thermoplastic resin, (E) solvent, and other additives can also be added, and in this case, the mixing method described above can also be used.

The epoxy resin composition of the present embodiment is suitable for forming a film.
By using the epoxy resin composition of the present embodiment, a film can be obtained that has high stability when dried at high temperatures, high storage stability in a film form, and excellent curability and adhesiveness.

[Film material]
The film material of the present embodiment has a support and a resin layer formed on the support, and the resin layer contains the epoxy resin composition of the present embodiment.
If necessary, the film material may have a protective layer on the surface of the resin layer opposite to the support.

(Support)
The support is made of a material that does not change in quality or deform due to heat under the temperature conditions during the drying process of the organic solvent in the resin layer. Examples of such a support include, but are not limited to, polyethylene terephthalate film, polyvinyl alcohol film, polyvinyl chloride film, vinyl chloride copolymer film, polyvinylidene chloride film, vinylidene chloride copolymer film, polymethyl methacrylate copolymer film, polystyrene film, polyacrylonitrile film, styrene copolymer film, polyamide film, cellulose derivative film, etc.
These films may be stretched as required.

(protective layer)
The protective layer is preferably made of a material capable of sufficiently maintaining the smoothness of the surface of the resin layer, and examples of such a protective layer include, but are not limited to, polyethylene film, polypropylene film, polyethylene terephthalate film treated for easy peeling, and oriented polypropylene film.

[Method for producing film material]
The film material of this embodiment can be produced by sequentially laminating a support, a resin layer, and, if necessary, a protective layer.
As a method for laminating the support, the resin layer, and the protective layer, a known method can be adopted.
For example, the epoxy resin composition of the present embodiment is first prepared and applied to a support using a known method such as an applicator or a bar coater, followed by drying to form an epoxy resin composition layer on the support, and then, if necessary, a protective layer is laminated on the formed epoxy resin composition layer, thereby producing a film material.

There are no particular restrictions on the drying method used to obtain the film material; heating in an oven or hot air blowing may be used. The drying temperature may be constant, or a temperature gradient may be applied. Furthermore, since the epoxy resin composition of this embodiment has high resistance to high-temperature drying, drying at temperatures below 100°C is acceptable, but drying at high temperatures such as 120 to 180°C is also possible. There are no particular restrictions on the drying time, but it is, for example, 3 to 10 minutes. From the perspective of achieving excellent film storage stability, the drying temperature is preferably 150°C or less, and the drying time at high temperatures such as 120 to 180°C is preferably 5 minutes or less, and more preferably 3 minutes or less.

[Cured product]
The cured product of the present embodiment is a cured product of the epoxy resin composition of the present embodiment and the film material of the present embodiment, and can be produced by curing the epoxy resin composition of the present embodiment and the resin layer of the film material.
The curing method includes, but is not limited to, heating in an oven and thermocompression bonding, and curing may be carried out by utilizing heating conditions applicable to the manufacturing process of various electronic components and the like incorporating a film material containing the epoxy resin composition of the present embodiment in a resin layer.
The conditions for thermally curing the epoxy resin composition of the present embodiment are not particularly limited and can be appropriately selected depending on the composition of the epoxy resin composition and the like.
The cured product of the present embodiment has excellent reliability and can satisfactorily perform functions such as adhesion and sealing when used as an adhesive or sealant for various electronic components, etc. The mechanism behind this is thought to be, but is not intended to be limiting, as follows.
The epoxy resin composition and film material of this embodiment have excellent stability during high-temperature drying, allowing the epoxy group reaction rate during drying to be kept low. In other words, because they remain uncured until the desired curing conditions are met, they soften upon heating in the early stages of curing, allowing them to conform well to the irregularities of the adherend. Furthermore, the second curing agent (C) has excellent reactivity during curing, allowing for rapid curing while maintaining the desired adhesive surface area.
As a result, a cured product can be obtained that is free of voids between the adherend and the cured product and free of any extrusion defects.
Furthermore, since the film material has high storage stability, it can be cured after storage in the same manner as before storage, and the cured product can perform functions such as adhesion and sealing well.
From the above, the cured product of the present embodiment can be suitably used as a cured product for constituting various electronic components using film materials such as an interlayer insulating film, a die attach film, a film-type solder resist, a sealing sheet, a conductive film, an anisotropic conductive film, and a thermally conductive film.

Hereinafter, the present embodiment will be described with reference to specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples.
In the following, "parts" and "%" are by mass unless otherwise specified.

[Ingredients]
Components (A) to (E) in Tables 1 and 2 below are shown below.
(Component (A): Epoxy resin)
jER828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, epoxy equivalent: 186 g/eq)

(Component (B): First Curing Agent)
HPC-8000-65T (DIC Corporation, activated ester resin solids content 65% toluene solution)
-Dicyandiamide (Wako Pure Chemical Industries, Ltd.)
LA-3018-50P (DIC Corporation, 1-methoxy-2-propanol solution of phenol novolac resin with a solids content of 50%)

(Component (C): Second Curing Agent)
<Solvent-insoluble, solid, latent curing agent>
LSA-H2104 (manufactured by Asahi Kasei Corporation, a microcapsule-type curing agent masterbatch containing a solid core and phenyl glycidyl ether (10%) as a reactive diluent)
Amicure PN-40 (Ajinomoto Fine-Techno Co., Ltd., imidazole-based adduct-type solid latent hardener)
DCMU (Tokyo Chemical Industry Co., Ltd., 3,4-dichlorophenyl-N,N-dimethylurea, solid)
<Solvent-soluble curing agent>
DMAP (Tokyo Chemical Industry Co., Ltd., 4-dimethylaminopyridine, solid)
1B2PZ (manufactured by Shikoku Kasei Corporation, 1-benzyl-2-phenylimidazole, liquid or solid)
4-benzoylpyridine (Tokyo Chemical Industry Co., Ltd., solid)

(Component (D): thermoplastic resin)
PKHB (Inchem, phenoxy resin, number average molecular weight of 14,600 in the range of polystyrene equivalent molecular weight of 728 or more)
(Component (E): Solvent)
Methyl ethyl ketone (Wako Pure Chemical Industries, Ltd.)
- Cyclohexanone (Wako Pure Chemical Industries, Ltd.)

[Preparation of epoxy resin composition and film material]
Each component was weighed and mixed so as to obtain the blending ratio shown in Table 1 below, thereby obtaining an epoxy resin composition.
Next, the epoxy resin composition was applied onto a polyethylene terephthalate film (thickness: 50 μm) as a support so that the dry film thickness was 40 μm, and then the coating was dried by heating for a predetermined time in an oven preheated to a predetermined temperature. After that, the surface opposite the support was protected with a polyethylene terephthalate film that had been treated to be easily peeled, thereby obtaining a film material.
The drying conditions were as follows:
Condition A: 120°C for 5 minutes Condition B: 150°C for 3 minutes

[Methods for measuring and evaluating characteristics]
(Coating film uniformity)
The surface condition of the film material obtained by drying under the above-mentioned condition A was visually observed and evaluated according to the following criteria.
◯: No protruding structures are observed and no holes are formed.
×: Protrusions were observed or holes were formed.

(180℃ curability)
The film material obtained by drying under the above-mentioned condition A was heat-cured for 1 hour in an oven preheated to 180° C. Thereafter, the FT-IR spectrum of the cured resin layer of the obtained film material was measured using a Fourier transform infrared spectrophotometer (FT/IR-6600, manufactured by JASCO Corporation).
The intensity ratio P2/P1, which is the absorption P1 at around 2920 cm ⁻¹ due to the methylene groups of the epoxy resin and phenoxy resin, which do not change in strength upon heat curing, and the absorption P2 at around 915 cm ⁻¹ due to the epoxy groups, was used as a reference. This was compared with the intensity ratio P2 ₀ /P1 ₀ (P1 ₀ is the absorption at around 2920 cm ⁻¹ , P2 ₀ is the absorption at around 915 cm ⁻¹ due to the epoxy groups) when a film material was prepared in the same manner but with a composition excluding the first curing agent component and the second curing agent component, and the epoxy group reaction rate was calculated using the following formula (1).
Epoxy group reaction rate=100−(P2/P1)/(P2 ₀ /P1 ₀ )×100 Equation (1)
The epoxy group reaction rate was evaluated according to the following criteria.
◯: Epoxy group reaction rate is 90% or more ×: Epoxy group reaction rate is less than 90%

(Stability when drying at high temperature)
The FT-IR spectrum of the film materials prepared by drying under conditions A and B was measured, and the epoxy group reaction rate (%) upon drying was calculated using the above formula (1).

(Film storage stability)
The film materials prepared by drying under conditions A and B were stored in an oven at 40° C. for 7 days.
The FT-IR spectrum of the film material after storage was measured, and the epoxy group reaction rate (%) after storage was calculated by using the value after storage as the value of P2/P1 in the above formula (1).

(copper adhesion)
The film material prepared under condition A was cut out together with the support and placed between two copper plates ("C1100P" manufactured by Standard Test Piece Co., Ltd.) so as to have an adhesive area of 25 mm x 5 mm.
In this state, the film material was transferred to the copper plate by heating in an oven at 60°C for 10 minutes, and the support was peeled off and removed. Subsequently, the film was heated in an oven preheated to 180°C for 1 hour to be thermoset and bonded, thereby obtaining a test specimen.
The tensile shear adhesive strength (N/ ^mm2 ) of the obtained test pieces was measured using an AUTOGRAPH AGS-X 5kN (manufactured by Shimadzu Corporation) in a constant temperature and humidity room at 23°C and 50% RH, and the median of the obtained values was used as the initial evaluation of copper adhesion.
Furthermore, the film material prepared under condition A was stored in an oven at 40°C for 7 days, and then the copper adhesion of the film after storage was evaluated in the same manner as above, and the evaluation was made after storage at 40°C for 1 week.

[Example 1 , Reference Example 2, Example 3, Reference Examples 4-5, Example 6, Reference Example 7, Example 8, Reference Examples 9-10 ], [Comparative Examples 1-5]
The components were blended in the proportions shown in Tables 1 and 2, and epoxy resin compositions and film materials were prepared by the methods described above.
The properties of the prepared epoxy resin compositions were measured by the above-mentioned methods.

In the examples and comparative examples shown in Tables 1 and 2, no defects were observed during coating, and the coating film uniformity was good.
Focusing on the examples in which the same type of first curing agent was blended, a comparison of Example 1, Reference Example 2 with Comparative Example 1, Example 3 , Reference Examples 4 to 5 with Comparative Example 3, and Example 8 , Reference Examples 9 to 10 with Comparative Example 5 revealed that the use of a solvent-insoluble second curing agent resulted in excellent high-temperature drying stability, film storage stability, and copper adhesion.
On the other hand, in Comparative Example 2, the high-temperature drying stability and film storage stability were good, but the curing property was low, and even after heating at 180°C for 1 hour, the epoxy group reaction rate was only 14%, and the copper adhesion was also low.
In Comparative Example 4, the stability during high-temperature drying was relatively good, but in terms of film storage stability, Examples 6 and 7, which used a solvent-insoluble second curing agent, were superior.
Furthermore, it has been found that among the second curing agents used, when a microcapsule-type curing agent containing a reactive diluent or a urea derivative is used, stability during high-temperature drying and film stability are particularly excellent.
In terms of copper adhesion, the adhesion of urea derivatives decreased after storage, whereas when a microcapsule-type curing agent containing a reactive diluent was used, no decrease in adhesion was observed after storage, and it was found that all physical properties, including curability, stability at high temperatures and when dried, film storage stability, and copper adhesion after storage, were extremely good.

The epoxy resin composition of the present invention has industrial applicability in a wide range of applications, including film materials such as interlayer insulating films, die attach films, film-type solder resists, sealing sheets, conductive films, anisotropically conductive films, and thermally conductive films, as well as various paste materials such as insulating adhesive pastes, conductive pastes, anisotropically conductive pastes, and thermally conductive pastes, as well as various coating materials and paints.

Claims (5)

(A) an epoxy resin;
(B) at least one first curing agent selected from the group consisting of an active ester curing agent, an amide curing agent, and a phenolic resin curing agent;
(C) a second curing agent that is a solvent-insoluble, solid, and microcapsule-type curing agent that is a latent curing agent ;
An epoxy resin composition comprising:
the second curing agent comprises a reactive diluent;
the reactive diluent is an epoxy compound having an aromatic ring, the aromatic ring being a monocyclic and monofunctional epoxy compound;
the content of the reactive diluent is 2 mass% or less based on the solid content of the epoxy resin composition;
Epoxy resin composition. (D) further containing a thermoplastic resin;
The epoxy resin composition according to claim 1 . A film-forming epoxy resin composition,
The epoxy resin composition according to claim 1 or 2 . A support;
a resin layer formed on the support;
and
The resin layer contains the epoxy resin composition according to any one of claims 1 to 3 .
Film material. A cured product of the epoxy resin composition according to any one of claims 1 to 3 or the resin layer of the film material according to claim 4 .