JP7720178B2 - Epoxy resin composition and epoxy resin composition product - Google Patents

Description

The present invention relates to an epoxy resin composition and an epoxy resin composition product.

Epoxy resins have traditionally been used in a wide range of applications, including as insulating materials for electrical and electronic components, sealing materials, adhesives, conductive materials, matrix resins for fiber-reinforced plastics, and impregnating and fixing agents for motor coils.

Recent demands for electronic devices are diverse, including miniaturization, high performance, lightweight design, and multi-functionality. Semiconductor chip mounting technology is also seeing advances in miniaturization, miniaturization, and high density due to finer electrode pad pitches. An underfill material made from a thermosetting resin composition that protects the bump connections and the chip's circuit surface is used in the gap between the semiconductor chip and substrate, and epoxy resin compositions are commonly used as such underfill materials.

Fiber-reinforced plastics are manufactured using reinforcing fibers and a matrix resin. The matrix resin is often a thermosetting resin containing an epoxy resin, and fiber-reinforced plastics are obtained by impregnating reinforcing fibers with a resin composition containing the epoxy resin and then curing it.

Motor coils are also protected from deterioration due to moisture and environmental waste by impregnating the spaces between the coils with an epoxy resin composition and then curing it. For example, Patent Document 1 discloses a one-component epoxy resin composition for electrical insulation that has excellent storage stability and short curing time. Patent Document 2 also discloses an epoxy resin composition for impregnation and fixing that has excellent storage stability and is easy to process.

Japanese Patent Application Laid-Open No. 2005-220306 Patent No. 5400383

In recent years, the automotive industry has been increasing production of hybrid and electric vehicles in response to environmental issues, leading to increased demand for motor coils. Furthermore, from the perspective of improving fuel efficiency, vehicle weight reduction technology is important, and the use of lightweight, high-strength fiber-reinforced plastics is expanding.

In response to the increasing demand for motor coils and fiber-reinforced plastics, improving productivity by shortening production takt time and reducing environmental impact have become issues. To solve these issues, there is a need for a one-component epoxy resin composition that can shorten impregnation time and curing time, has high storage stability, and eliminates the need for a mixing step during use.
However, in one-component epoxy resin compositions, there is a trade-off between high storage stability and shortened curing time, and it is extremely difficult to achieve both at a high level. Furthermore, during transportation of one-component epoxy resin products, coolants, refrigeration equipment, and suitable special packaging materials are required to maintain quality. Refrigeration equipment has the problem of imposing a heavy burden on the environment, and the coolants and special packaging materials used become waste.
To address these issues, the one-component epoxy resin compositions described in Patent Documents 1 and 2 have the problem that there is still room for improvement in terms of low viscosity, short-time curing property, high storage stability, suitability for transportation at room temperature, reduction of environmental load during transportation, and reduction of waste generated after transportation.

In view of the problems with the prior art discussed above, the present invention aims to provide a one-component epoxy resin composition that has low viscosity, short-time curing properties, high storage stability, is suitable for transportation at room temperature, reduces the environmental impact during transportation, and is excellent at reducing waste generated after transportation, as well as a packaged product containing the composition.

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 arrived at the present invention.
That is, the present invention is as follows.

[1]
Component (A): a bisphenol A epoxy resin in which the ratio of the peak area Sα derived from α-glycol represented by formula (1) to the sum of all peak areas S _Total , as calculated by liquid chromatography measurement, is 0.4% or more and less than 1.4%;

Component (B): bisphenol F type epoxy resin,
Component (C): an acid anhydride,
Component (D): a microcapsule-type curing accelerator;
An epoxy resin composition comprising:

[2]
The epoxy resin composition according to [1] above, wherein the content of the component (B): bisphenol F epoxy resin is 10 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the total amount of the epoxy compounds.
[3]
The epoxy resin composition according to [1] or [2] above, further comprising a component (E) reactive diluent.
[4]
The epoxy resin composition according to any one of [1] to [3] above, wherein the component (C) is an acid anhydride having a structure of the following formula (2) or formula (3):

In formula (2), the C ₁ to C ₆ carbons may be saturated or unsaturated. In the case of unsaturated carbons, adjacent carbons may form an unsaturated bond.
Each of R ₁ to R ₁₄ is one selected from the group consisting of hydrogen, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom.
R ₁ to R ₁₄ may be the same or different.
It may also be a fused ring compound in which any one selected from R ₁ to R ₁₄ is present in the same ring.

In formula (3), the C ₁ to C ₆ carbons may be saturated or unsaturated. In the case of unsaturated carbons, adjacent carbons may form an unsaturated bond.
Each of R ₁ to R ₁₂ is one selected from the group consisting of hydrogen, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom.
R ₁ to R ₁₂ may be the same or different.
It may also be a fused ring compound in which any one selected from R ₁ to R ₁₂ is present in the same ring.

[5]
The epoxy resin composition according to any one of [1] to [4] above,
a resin or metal container containing the epoxy resin composition;
and a renewable or reusable paper or plastic outer packaging material for packaging the container.

The present invention provides a one-component epoxy resin composition that has low viscosity, short-time curing properties, high storage stability, is suitable for transportation at room temperature, reduces the environmental impact during transportation, and reduces waste generated after transportation.

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): a bisphenol A epoxy resin in which the ratio of the peak area Sα derived from α-glycol represented by formula (1) to the sum of all peak areas S _Total , as calculated by liquid chromatography (hereinafter sometimes referred to as LC), is 0.4% or more and less than 1.4%;

Component (B): bisphenol F type epoxy resin,
Component (C): an acid anhydride,
Component (D): a microcapsule-type curing accelerator;
Contains:
The epoxy resin composition of the present embodiment contains components (A) to (D), and thus exhibits low viscosity, short-time curing properties, and high storage stability despite being a one-component epoxy resin composition.

(Component (A))
The epoxy resin composition of the present embodiment contains, as component (A), a bisphenol A epoxy resin in which the proportion of the peak area Sα derived from α-glycol represented by the formula (1) is 0.4% or more and less than 1.4% of the sum of all peak areas S _Total , as calculated by LC measurement.
By including the component (A), high storage stability, sufficient reactivity, and appropriate viscosity are achieved.
Examples of component (A) include, but are not limited to, BE-186EL (trade name, manufactured by Changchun Co., Ltd.) and DER383J (trade name, manufactured by Olin Co., Ltd.).
The component (A) may be used alone or in combination of two or more types.

The α-glycol represented by formula (1) contained in component (A) is a compound having a hydroxyl group at the molecular terminal, and from the viewpoint of storage stability, the proportion of the peak area Sα derived from the α-glycol, calculated by LC measurement, is less than 1.4% of the sum of all peak areas S _Total , preferably 1.3% or less, more preferably 1.1% or less, and even more preferably 1.0% or less.
On the other hand, in the epoxy resin composition of the present embodiment, from the viewpoint of ensuring sufficient reactivity while maintaining high storage stability, the content is set to 0.40% or more, preferably 0.41% or more, and more preferably 0.42% or more.

The mechanism by which the ratio of the peak area Sα derived from α-glycol represented by the formula (1) calculated by LC measurement to the sum of all peak areas S _Total is effective in achieving high storage stability and sufficient reactivity is thought to be, but not limited to, the following.
The hydroxyl groups in the structure of α-glycol coordinate to the acid anhydride (component (C)) described below, thereby accelerating the ring-opening reaction of the acid anhydride, which deteriorates the storage stability of the epoxy resin composition and increases the water absorption of the epoxy resin composition. When the water absorption of the epoxy resin composition is thus increased, the water that has entered the epoxy resin composition further accelerates the ring-opening reaction of the acid anhydride (component (C)) described below, further deteriorating the storage stability of the epoxy resin composition.
Therefore, reducing the amount of α-glycol can improve storage stability. On the other hand, including α-glycol within a range that does not impair storage stability can effectively improve the reactivity of the acid anhydride (component (C)) described below.
From the above, the epoxy resin composition of the present embodiment contains, as component (A), a bisphenol A epoxy resin in which the proportion of the peak area Sα derived from α-glycol represented by the formula (1) is 0.4% or more and less than 1.4% of the sum of all peak areas S _Total , as calculated by LC measurement.
The proportion of the peak area of α-glycol represented by the formula (1) in component (A), calculated by LC measurement, can be controlled to fall within the above-mentioned range by controlling the water content in the production process or by purifying the component (A) by distillation or the like after production.

From the viewpoint of imparting an appropriate viscosity to the epoxy resin composition of this embodiment, the content of component (A) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, relative to 100 parts by mass of the total amount of epoxy compounds. Furthermore, since component (B), which will be described later, is added to achieve low viscosity, high storage stability, and short-time curing properties, the content of component (A) need only be an amount sufficient to achieve these effects, and from the viewpoint of preventing excessive addition, the content is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less.
Here, the appropriate viscosity refers to a viscosity that allows the one-component epoxy resin composition of the present embodiment to sufficiently penetrate into coils, carbon fibers, and narrow gaps in a short time, and also prevents dripping and spreading to unwanted areas after application.
The total amount of epoxy compounds refers to an amount that includes at least the epoxy resins of component (A) and component (B), and further refers to an amount that also includes component (E), which will be described later, when the component (E) is an epoxy compound.

(Component (B))
The epoxy resin composition of the present embodiment contains a bisphenol F epoxy resin as component (B).
By including component (B), the composition has low viscosity, short curing time, and high storage stability.
Examples of liquid bisphenol F epoxy resins include, but are not limited to, jER806, jER806H, jER807, jER1750, YL983U (trade names manufactured by Mitsubishi Chemical), 830, 830-S, EXA-830CRP, EXA-830LVP, 835, EXA-835LV (trade names manufactured by DIC), EP-4901, EP-4901E (trade names manufactured by ADEKA), YDF-8170C, YDF-170, YDF-170N (trade names manufactured by Nippon Steel Chemical), and the like.
Examples of solid bisphenol F epoxy resins include, but are not limited to, jER4005PP, jER4007P, and jER4010P (trade names manufactured by Mitsubishi Chemical Corporation), YDF-2001, YDF-2004, and YDF-2005RD (trade names manufactured by Nippon Steel Chemical Co., Ltd.).
These may be used alone or in combination of two or more.
In this embodiment, a liquid bisphenol F epoxy resin is preferred from the viewpoint of low viscosity and ease of handling.

The mechanism by which the inclusion of component (B): bisphenol F type epoxy resin is effective in achieving low viscosity, short curing time, and high storage stability is thought to be, but is not intended to be limiting, as follows.
The inclusion of the bisphenol F epoxy resin suppresses aggregation of the bisphenol A epoxy resins, improving the uniformity of the epoxy resin composition of the present embodiment and increasing the molecular diffusivity at the curing temperature, thereby exhibiting low viscosity, high storage stability, and short-term reactivity.

The content of the bisphenol F epoxy resin component (B), relative to 100 parts by mass of the total amount of epoxy compounds, is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, from the viewpoints of achieving low viscosity, short-time curing, and high storage stability. Furthermore, since component (A) is added to impart sufficient viscosity, the content of component (B) need only be an amount sufficient to achieve this effect, and from the viewpoint of preventing excessive addition, the content is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less.
The total amount of epoxy compounds refers to an amount that includes at least the epoxy resins of component (A) and component (B), and further refers to an amount that also includes component (E), which will be described later, when the component (E) is an epoxy compound.

(Component (C))
The epoxy resin composition of the present embodiment contains an acid anhydride as component (C).
The acid anhydride functions as a curing agent.
Component (C): Acid anhydride is not limited to the following, but examples thereof include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhimic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

In the epoxy resin composition of this embodiment, from the viewpoints of storage stability and reactivity, component (C) is preferably an acid anhydride having a phthalic anhydride structure or an acid anhydride having a structure represented by the following formula (2) or formula (3), and from the viewpoint of storage stability, an acid anhydride having a structure represented by formula (2) is more preferred.

In formula (2), the C ₁ to C ₆ carbons may be saturated or unsaturated. In the case of unsaturated carbons, adjacent carbons may form an unsaturated bond.
Each of R ₁ to R ₁₄ is one selected from the group consisting of hydrogen, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom.
R ₁ to R ₁₄ may be the same or different.
It may also be a fused ring compound in which any one selected from R ₁ to R ₁₄ is present in the same ring.

In formula (3), the C ₁ to C ₆ carbons may be saturated or unsaturated. In the case of unsaturated carbons, adjacent carbons may form an unsaturated bond.
Each of R ₁ to R ₁₂ is one selected from the group consisting of hydrogen, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom.
R ₁ to R ₁₂ may be the same or different.
It may also be a fused ring compound in which any one selected from R ₁ to R ₁₂ is present in the same ring.

Examples of acid anhydrides having the structure of general formula (2) include, but are not limited to, nadic anhydrides such as methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, hydrogenated methyl nadic anhydride, and chlorendic anhydride.
Examples of acid anhydrides having the structure of general formula (3) include, but are not limited to, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.
These acid anhydrides as component (C) may be used alone or in combination of two or more.

The content of component (C) is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, from the viewpoint of appropriate viscosity, reactivity, strength, and heat resistance, when the total amount of component (A), component (B), and component (E) described later is taken as 100 parts by mass.
From the viewpoint of storage stability, the amount is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less.

(Component (D))
The epoxy resin composition of the present embodiment contains component (D): a microcapsule-type curing accelerator.
Component (D) has excellent storage stability because the curing accelerator component is physically isolated from components (A), (B), and (C) by the capsule membrane.

From the viewpoint of ensuring sufficient reactivity, the content of the microcapsule-type curing accelerator (D) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, when the total of components (A), (B), and (E) described below is taken as 100 parts by mass.
Furthermore, from the viewpoint of appropriate viscosity, the amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less, and even more preferably 11 parts by mass or less.

Examples of the curing accelerator component in the microcapsules of component (D) include amine compounds, amide compounds, and phenol compounds.

Examples of the amine compounds include, but are not limited to, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, diaminodiphenylmethane, m-phenylenediamine, and diaminodiphenylsulfonyl. Benzyldimethylamine, N,N-dimethyl-ethylamine, N,N-dimethyl-butylamine, N,N-dimethyldecylamine, N,N-dimethyl-m-toluidine, N,N-dimethyl-p-toluidine, 2,6,10-trimethyl-2,6,10-triazaundecane, N,N'-dimethylpiperazine, 1 tertiary amines such as 1,4-diazabicyclo[2.2.2]octane, 1-azabicyclo[2.2.2]octan-3-one, 1,8-diazabicyclo(5,4,0)-undecene-7, 1,5-diazabicyclo(4,3,0)-nonene-5, and hexamethylenetetramine; imidazoles such as 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 1-vinylimidazole, 1-allylimidazole, 2-methyl-1-vinylimidazole, and N-acetylimidazole; Examples of the aromatic tertiary amines include dimethylaminobenzhydrol, bis[4-(dimethylamino)phenyl]methane, 4,4'-bis(dimethylamino)benzophenone, and 2-diethylamino-N-(2,6-dimethylphenyl)acetamide; aminopyridines having a tertiary amino group, such as 2-dimethylaminopyridine and 4-dimethylaminopyridine; and products obtained by reacting an amine compound with a carboxylic acid compound, a sulfonic acid compound, a urea compound, an isocyanate compound, or an epoxy compound.
These amine compounds may be used alone or in combination of two or more.
In this embodiment, imidazole compounds are preferred because they have high reactivity and can be cured in a short time.

Examples of amide 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, maleic acid dihydrazide, dicyandiamide, methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, toluoylguanidine, and compounds obtained by reacting an amine compound with an acid anhydride.
These amide compounds may be used alone or in combination of two or more.

Examples of the phenolic compound include, but are not limited to, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, cresol aralkyl resin, naphthol aralkyl resin, biphenyl-modified phenol resin, biphenyl-modified phenol aralkyl resin, dicyclopentadiene-modified phenol resin, aminotriazine-modified phenol resin, naphthol novolac resin, naphthol-phenol co-condensed novolac resin, naphthol-cresol co-condensed novolac resin, and allyl acrylic phenol resin.
These phenolic compounds may be used alone or in combination of two or more.

These curing accelerator components in the microcapsules may be used alone or in combination of two or more types.

From the perspective of storage stability, it is preferable that the hardening accelerator component in the microcapsules contains a hardener that is solid at 25°C and 1013 hPa. This prevents leaching out of the capsule, even if the capsule is damaged when the components are mixed, and maintains storage stability.

Examples of microcapsule-type curing accelerators containing a curing agent that is solid at 25°C and 1013hPa include Novacure HX-3721, HX-3722, HX-3742, HX-3088, HX-3792, HX-3921HP, HXA3922HP, HXA3932HP, HXA9322HP, and HXA9382HP, and also include AER Hardener D1301 (manufactured by Asahi Kasei).
These microcapsule type hardening accelerators may be used alone or in combination of two or more.

(Component (E))
The epoxy resin composition of the present embodiment may contain component (E), a reactive diluent (hereinafter sometimes referred to as component (E)), as needed.

Examples of the reactive diluent (E) include, but are not limited to, polyfunctional acrylate compounds containing acrylic groups and epoxy compounds that can reduce viscosity without impairing reactivity.
An epoxy compound that does not belong to the bisphenol type epoxy resin and has a lower viscosity than the bisphenol A type epoxy resin of component (A) is sometimes called an epoxy type reactive diluent.

Examples of polyfunctional acrylates containing acrylic groups 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 polyfunctional (meth)acrylate, pentaerythritol-type polyfunctional (meth)acrylate, and dipentaerythritol-type polyfunctional (meth)acrylate.

The epoxy-type reactive diluent is not particularly limited, but includes the following:
Examples of nitrogen-free epoxy-type reactive diluents include ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, (o-, m-, or p-)cresyl glycidyl ether, 2-biphenyl glycidyl ether, p-tert-butoxyphenyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol (400) diglycidyl ether, polyethylene glycol diglycidyl ether, dimer acid glycidyl ester, 1,4-cyclohexanedimethanol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether.
Examples of the epoxy-type reactive diluent containing a nitrogen atom include glycidyl aniline and glycidyl toluidine.
The epoxy resin composition of the present embodiment contains the acid anhydride as component (C), and therefore preferably contains an epoxy-type reactive diluent containing no nitrogen atoms as component (E) from the viewpoints of achieving high storage stability and low viscosity, and more preferably contains an epoxy-type reactive diluent containing no nitrogen atoms and having a linear structure with 4 or more carbon atoms from the viewpoint of increasing the tensile strength of the cured product.

Component (E) reactive diluent may be used alone or in combination of two or more types.

The content of component (E) is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, from the viewpoint of exhibiting an appropriate viscosity and sufficient mechanical properties, when the total of components (A), (B), and (E) is taken as 100 parts by mass.
From the viewpoint of preventing excessive viscosity reduction and deterioration of mechanical properties, the amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less.

(Other additives)
The epoxy resin composition of the present embodiment may further contain, as necessary, additives other than the components described above, such as epoxy resins other than components (A) and (B), organic fillers, inorganic fillers, pigments, dyes, flow modifiers, thickeners, release agents, wetting agents, flame retardants, surfactants, resins, and the like.

Epoxy resins other than components (A) and (B) include, but are not limited to, 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, methylhydroquinone type epoxy resins, dibutylhydroquinone type epoxy resins, resorcinol type epoxy resins, bifunctional epoxy resins such as alkoxy resin, methylresorcinol-type epoxy resin, catechol-type epoxy resin, and N,N-diglycidylaniline-type epoxy resin; trifunctional epoxy resins such as N,N-diglycidylaminobenzene-type epoxy resin, o-(N,N-diglycidylamino)toluene-type epoxy resin, and triazine-type epoxy resin; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane-type epoxy resin and diaminobenzene-type epoxy resin; multifunctional epoxy resins such as phenol novolac-type epoxy resin, cresol novolac-type epoxy resin, triphenylmethane-type epoxy resin, tetraphenylethane-type epoxy resin, dicyclopentadiene-type epoxy resin, naphthol aralkyl-type epoxy resin, and brominated phenol novolac-type epoxy resin; and alicyclic epoxy resins.
These epoxy resins other than components (A) and (B) may be used alone or in combination of two or more.

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, organic fine particles of acrylic resin, silicone resin, butadiene rubber, polyester, polyurethane, polyvinyl butyral, polyarylate, polymethyl methacrylate, acrylic rubber, polystyrene, NBR, SBR, silicone-modified resin, and copolymers containing any of these as components.
From the viewpoint of improving adhesiveness, examples of organic fine particles include alkyl (meth)acrylate-butadiene-styrene copolymers, alkyl (meth)acrylate-silicone copolymers, silicone-(meth)acrylic copolymers, complexes of silicone and (meth)acrylic acid, complexes of alkyl (meth)acrylate-butadiene-styrene and silicone, and complexes of alkyl (meth)acrylate and silicone.
Alternatively, organic fine particles having a core-shell structure, in which the core layer and the shell layer have different compositions, may be used. 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 resin grafted to an acrylic copolymer.
These organic fillers may be used alone or in combination of two or more.

When an inorganic filler is contained, adjusting the thermal expansion coefficient of the epoxy resin composition of the present embodiment tends to contribute to improving the heat resistance and moisture resistance when 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 scale-like 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, 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 synthetic thickeners such as polyacrylics, modified polyacrylics, polyethers, urethane-modified polyethers, 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.

[Epoxy resin composition products]
The epoxy resin composition product of the present embodiment includes the epoxy resin composition of the present embodiment, a resin or metal container containing the epoxy resin composition therein, and a recyclable or reusable paper or plastic exterior packaging material for packaging the container.
Because the epoxy resin composition of this embodiment has high storage stability, even when stored at room temperature without the use of coolants, refrigeration, or special packaging to maintain quality, changes in viscosity characteristics and curing properties are minimal, allowing for transportation at room temperature. Therefore, there is no need to consider the effects of condensation, the ease of installing coolants, or changes in internal temperature when packaging the product, and renewable or reusable paper or plastic materials can be used. Furthermore, the elimination of the need for coolants or special packaging materials such as polystyrene foam reduces post-transport waste. Furthermore, the elimination of the need for refrigeration contributes to the reduction of greenhouse gas emissions. Examples of renewable or reusable paper or plastic materials include, but are not limited to, cardboard and recyclable and reusable plastic packaging materials.

[Method for producing epoxy resin composition]
The epoxy resin composition of the present embodiment is obtained by mixing the above-mentioned components (A), (B), (C), and (D).
The method for mixing the components is not particularly limited, and general mixing equipment and processing conditions can be applied.
Specifically, there are no particular limitations on the method, but an example of a method for obtaining an epoxy resin composition includes thoroughly mixing the above-mentioned components (A) to (D), and, if necessary, component (E), and other additive components, etc., until a homogeneous mixture is obtained using a mixing roll such as a three-roll mill, a dissolver, a planetary mixer, a kneader, an extruder, or the like.

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.

[Preparation of Epoxy Resin Composition]
Components (A) to (E) described below were weighed out in the blending ratios shown in Table 1 below, and then these components were mixed in a non-bubbling kneader while stirring for 2 minutes and degassing for 3 minutes to prepare epoxy resin compositions.
The blending amount of each component in Table 1 below is shown in parts by mass, where the total amount of component (A), component (B), component (E), or epoxy resins not corresponding to component (A), component (B), and component (E) is taken as 100 parts by mass.

[Methods for measuring physical properties]
(Ratio of peak area derived from α-glycol in bisphenol A epoxy resin by LC measurement)
A bisphenol A type epoxy resin was dissolved in acetonitrile to prepare a 0.5% by mass solution, and then measurement was carried out using a UPLC manufactured by Waters Corporation under the following conditions.
Equipment: UPLC H-Class/QDa (Waters Corporation)
Column: Waters ACQUITY UPLC BEH C18 1.7 μm (2.1 mm I.D. x 50 mm)
Column temperature: 40°C
Flow rate: 0.2 mL/min Detection: Photodiode Array 280.4 nm
Mobile phase A: Water/methanol (80%/20%)
B: Acetonitrile (100%)
Gradient 0 min = A: 70% / B: 30%
30 minutes = A: 0% / B: 100%
36 minutes = A: 70% / B: 30%
40 minutes = A: 80% / B: 20%
Injection volume 1μL
Measurement was carried out under the above conditions, and the peak appearing at 4.5 minutes corresponds to α-glycol represented by formula (1).
The area value corresponding to α-glycol is Sα, and the sum of all peak areas detected by liquid chromatography is S _Total . The ratio of the peak area Sα derived from α-glycol to the sum of all peak areas S _Total was calculated using the following formula (1).
Sα/S _Total ×100 (%)...Formula (1)

[Method of measuring characteristics]
(Low Viscosity: Initial Viscosity Measurement of Epoxy Resin Composition)
The viscosity (initial viscosity) of the epoxy resin composition immediately after preparation was measured at room temperature (25°C) using an E-type viscometer (TVE-35H, manufactured by Toki Sangyo Co., Ltd.).
The initial viscosity was evaluated as being preferably 1700 mPa·s or less from the viewpoint of impregnation into coils and carbon fibers in a short time and penetration into narrow gaps.
On the other hand, from the viewpoint of reducing dripping and spreading to unwanted areas after application, a viscosity of 750 mPa·s or more was evaluated as being preferable, and a viscosity of 1000 mPa or more was evaluated as being more preferable.

(Storage stability: Storage stability viscosity magnification)
The initial viscosity immediately after the preparation of the epoxy resin composition and the viscosity after leaving the epoxy resin composition at 40°C for 7 days were measured at room temperature (25°C) using an E-type viscometer, and the storage stability viscosity ratio was calculated using the following mathematical formula (2).
Storage stability viscosity ratio = viscosity after 7 days at 40°C / initial viscosity (Equation 2)
The storage stability viscosity factor was evaluated as preferably 2 or less, more preferably 1.6 or less, and even more preferably 1.3 or less.

(Short-time curing: 150°C curastometer torque rise time)
A torque-vulcanization time chart of the epoxy resin composition was obtained at a set temperature of 150°C using a Curastometer (Curastometer V, manufactured by TS Engineering Co., Ltd.).
For the obtained chart, the time when the torque value started to increase slightly was taken as the torque rise time.
The faster the torque rise time, the faster the gelation rate of the epoxy resin composition, indicating that it is suitable for short-time curing.
A torque rise time of less than 200 seconds was evaluated as being preferable, and 190 seconds or less was evaluated as being particularly preferable.

(Tensile elongation measurement)
The epoxy resin composition was poured fully into a Teflon (registered trademark) mold measuring 550 mm in length, 350 mm in width, and 2 mm in thickness, up to the opening, and heated in a heating furnace at a set temperature of 100° C. for 30 minutes, and then at 150° C. for 60 minutes. After heating was completed, the composition was removed from the Teflon (registered trademark) mold, and the resulting cured piece was cut into a size of 40 mm in length, 5 mm in width, and 2 mm in thickness to obtain a cured product sample as a test piece for measuring tensile strength.
The obtained test pieces were subjected to a tensile test in a constant temperature and humidity chamber at 23°C and 50% RH using an AUTOGRAPH AGS-X 5kN (manufactured by SHIMADZU) at a unit moving speed of 5 mm/min to obtain the tensile elongation (%).
The tensile test was carried out five times in total, and the median value of the obtained results was taken as the positive tensile elongation (%).

(suitable for transportation at room temperature: suitable for storage at room temperature)
50 g of the epoxy resin composition was weighed into a resin container, which was then sealed and placed in a cardboard packaging material or a plastic packaging material to obtain an evaluation sample.
This evaluation sample was stored in a metal container exposed to the outside air for 10 days in May 2021 at a location of 35.14 north latitude and 138.68 east longitude, and the changes in the viscosity increase ratio and 150°C curastometer torque rise time of the epoxy resin composition after 10 days were evaluated.
<Criteria for determining the viscosity increase ratio in this evaluation>
1x or more but less than 1.3x... ◎
1.3 times or more but less than 1.6 times: 〇 1.6 times or more but less than 2 times: △
More than twice as large... ×
<Criteria for evaluation of change in torque rise time at 150°C using a curastometer>
5% or less: 〇 More than 5% and 50% or less: △
Greater than 50%... ×

[Ingredients]
The components are shown in Table 1 below.
The viscosity of each epoxy resin was measured in the same manner as in measuring the initial viscosity of the epoxy resin composition.
(Bisphenol A epoxy resin corresponding to component (A))
BE-186EL (product name manufactured by Choshunsha)
Epoxy equivalent 178g/eq. , viscosity 9410mPa・s, Sα/Stotal×100=1.03%
DER383J (Olin product name)
Epoxy equivalent: 178 g/eq., viscosity: 9780 mPa·s, Sα/Stotal×100=0.42%
(Bisphenol A epoxy resin not corresponding to component (A))
jER828 (product name manufactured by Mitsubishi Chemical Corporation)
Epoxy equivalent 184g/eq. , viscosity 13385mPa・s, Sα/Stotal×100=1.40%
(Component (B) Bisphenol F type epoxy resin)
EXA-830CRP (product name manufactured by DIC)
Epoxy equivalent weight 161g/eq.
(Component (C) acid anhydride)
MHAC-P (product name of Showa Denko Materials)
Methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride (methyl nadic anhydride)
HN-5500 (product name manufactured by Showa Denko Materials)
3 or 4-Methyl-hexahydrophthalic anhydride (Component (D) Microcapsule-type curing accelerator)
Novacure HX-3742 (trade name, manufactured by Asahi Kasei)
A masterbatch-type curing agent containing an imidazole-based curing agent that is solid at 25°C and 1013 hPa (component (E) reactive diluent)
YED216D (product name manufactured by Mitsubishi Chemical)
1,6-Hexanediol diglycidyl ether, viscosity 121 mPa·s

[Example 1 , Reference Example 2, Examples 3 to 6] and [Comparative Examples 1 to 3]
The components were mixed in the proportions shown in Table 1, and epoxy resin compositions were prepared by the method described above.
The properties of the prepared epoxy resin compositions were measured by the above-mentioned methods.

A comparison of Example 1 and Comparative Example 1 reveals that by combining component (A) and component (B) so that the epoxy resin composition contains a bisphenol A epoxy resin and a bisphenol F epoxy resin, excellent effects can be achieved in all of the properties of low viscosity, improved storage stability, and improved short-time curing properties, and an epoxy resin composition with an excellent balance of properties can be obtained.
Furthermore, when comparing Reference Example 2 with Comparative Example 2, the bisphenol A type epoxy resin (component (A
)) was found to have the effects of lowering viscosity and improving storage stability.
Furthermore, when Example 1 is compared with Comparative Example 3, by including the component (A) and the component (B),
It was found that the effects of lowering viscosity, improving storage stability, and improving reactivity were obtained.

Comparing Reference Example 2 with Example 3, it was found that the inclusion of the component (C) having the structure of formula (2): an acid anhydride, had the effect of improving storage stability.

Comparing Examples 3, 4, and 5, it was found that increasing the amount of component (B), bisphenol F epoxy resin, improved storage stability but also reduced viscosity. Examples 3 and 4 were found to be in a particularly desirable viscosity range.

The tensile test results for Examples 4 and 6 are shown in Table 2 below.

Comparing Example 4 and Example 6, it was found that the inclusion of an epoxy-type reactive diluent (component (E)) with a nitrogen-free, linear structure containing 4 or more carbon atoms improves tensile elongation while maintaining appropriate viscosity, good storage stability, and short-time curing properties.

The test results for room temperature transport suitability (room temperature storage stability) using Examples 1 to 6 are shown in Table 3 below.

From the results of Examples 7 to 18, it was found that even when Examples 1 to 6 were placed in a resin container, packaged using cardboard packaging material or plastic packaging material without using a coolant, refrigeration equipment, or special packaging material, and stored at room temperature for 10 days, the product exhibited good viscosity and reactivity.
Although the present embodiment has been described above, the present invention is not limited to this embodiment, and can be modified as appropriate within the scope of the invention.

The epoxy resin composition of the present invention has industrial applicability as an insulating material for electronic components, a sealing material, an adhesive, a conductive material, a matrix resin for fiber-reinforced plastics, an impregnating adhesive for motor coils, and the like.

Claims (4)

Component (A): a bisphenol A epoxy resin in which the ratio of the peak area Sα derived from α-glycol represented by formula (1) to the sum of all peak areas S _Total , as calculated by liquid chromatography measurement, is 0.4% or more and less than 1.4%;
Component (B): bisphenol F type epoxy resin,
Component (C): an acid anhydride,
Component (D): a microcapsule-type curing accelerator;
An epoxy resin composition comprising:
The component (C) is an acid anhydride having a structure of the following formula (2):
the content of the component (D) is 1 part by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total amount of the epoxy compounds in the epoxy resin composition;
Epoxy resin composition.
In formula (2), the C ₁ to C ₆ carbons may be saturated or unsaturated. In the case of unsaturated carbons, adjacent carbons may form an unsaturated bond.
Each of R ₁ to R ₁₄ is one selected from the group consisting of hydrogen, an alkyl group, an aromatic group, a substituent containing a hetero atom, and a substituent containing a halogen atom.
R ₁ to R ₁₄ may be the same or different.
It may also be a fused ring compound in which any one selected from R ₁ to R ₁₄ is present in the same ring. the content of the component (B): bisphenol F epoxy resin is 10 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the total amount of the epoxy compounds;
The epoxy resin composition according to claim 1. Further comprising component (E) a reactive diluent;
The epoxy resin composition according to claim 1 or 2. The epoxy resin composition according to any one of claims 1 to 3 ,
a resin or metal container containing the epoxy resin composition;
and a renewable or reusable paper or plastic outer packaging material for packaging the container.