WO2025249411A1 - Curable resin composition, use of curable resin composition, cured product, and method for producing cured product - Google Patents

Abstract

The present invention addresses the problem of providing a curable resin composition capable of providing a cured product having an excellent balance between heat resistance and toughness when cured at a low temperature. This curable resin composition contains (i) an epoxy resin, (ii) one or more types selected from the group consisting of polymer particles, a blocked urethane, a rubber-modified epoxy resin and a urethane-modified epoxy resin, (iii) an epoxy curing agent containing an alicyclic amine and/or a polyamideamine, and (iv) an epoxy-based reactive diluent.

Description

CURABLE RESIN COMPOSITION, USE OF CURABLE RESIN COMPOSITION, CURED PRODUCT, AND METHOD FOR PRODUCING CURED PRODUCT

The present invention relates to a curable resin composition, uses of the curable resin composition, a cured product, and a method for producing the cured product.

Curable resin compositions containing epoxy resins are used in many fields.

In recent years, from the perspective of environmental friendliness, there has been a demand for curable resin compositions that can be cured at lower temperatures and provide cured products that exhibit excellent physical properties.

For example, Patent Document 1 discloses a curable resin composition that can be used as a room-temperature curing two-component or multi-component adhesive.

JP 2023-146870 A

However, the conventional techniques described above were not sufficient in terms of the balance between heat resistance and toughness of the cured products obtained by curing at low temperatures, and there was room for further improvement.

One embodiment of the present invention has been developed in consideration of the above-mentioned problems, and its purpose is to provide a novel curable resin composition that can provide a cured product that exhibits an excellent balance between heat resistance and toughness when cured at low temperatures.

A curable resin composition according to one embodiment of the present invention is a curable resin composition for low-temperature curing, and includes the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
Satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

A curable resin composition according to one embodiment of the present invention is a two-component or multi-component curable resin composition for low-temperature curing, comprising a first component and a second component, wherein the first component comprises the following components (A) and (D):
Component (A): epoxy resin;
Component (D): an epoxy-based reactive diluent;
The second component includes the following component (C):
Component (C): epoxy curing agent;
The curable resin composition further contains the following component (B):
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

A cured product according to one embodiment of the present invention is obtained by curing a curable resin composition containing the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A degree of cure by differential scanning calorimetry (DSC) of 50% to 95%;
The curable resin composition satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
The active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq.

One embodiment of the present invention has the effect of providing a novel curable resin composition that can provide a cured product that exhibits an excellent balance between heat resistance and toughness when cured at low temperatures.

One embodiment of the present invention is described below, but the present invention is not limited to this. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be created by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including A and greater than A) and less than or equal to B (including B and less than B)."

1. Technical Concept of the Present Invention
In recent years, from the viewpoint of environmental friendliness, there has been a demand for curable resin compositions that can be cured at low temperatures and that can provide cured products having excellent physical properties even when cured at low temperatures.

Amine-based epoxy curing agents can be selected as epoxy curing agents because they are effective at low temperatures. There are many types of amine-based epoxy curing agents. Examples include linear aliphatic polyamines, polyether amines, amine-terminated butadiene nitrile rubber, polyamidoamines, which are modified linear aliphatic polyamines, and alicyclic amines (cyclic aliphatic polyamines).

The present inventors have discovered the following in the course of investigating amine-based epoxy curing agents: (i) when triethylenetetramine (TETA), a chain aliphatic polyamine, is used, the cured product has excellent heat resistance but poor toughness;
(ii) When polyetheramine is used, the cured product has excellent toughness but poor heat resistance.

Furthermore, the present inventors have discovered the following in the course of studying polyamidoamines:
(iii) When a polyamidoamine is used as an epoxy curing agent in a certain amount or more and the active hydrogen equivalent of the epoxy curing agent is small, the cured product has excellent heat resistance but poor toughness;
(iv) When a polyamidoamine is used as an epoxy curing agent in an amount exceeding a certain level and the active hydrogen equivalent of the epoxy curing agent is large, the cured product has excellent toughness but poor heat resistance.

In other words, it was difficult to achieve both heat resistance and toughness.

The inventors also independently discovered the novel finding that, while cured products obtained by curing at high temperatures using alicyclic amines have excellent heat resistance and toughness, cured products obtained by curing at low temperatures using alicyclic amines surprisingly have poor toughness.

Therefore, the present inventors have further conducted extensive research with the aim of providing a curable resin composition that can provide a cured product having an excellent balance between heat resistance and toughness when cured at a low temperature. As a result, the present inventors have independently discovered the following novel findings, which have led to the completion of the present invention:
(1) A novel finding that a curable resin composition containing a certain amount or more of an alicyclic amine as an epoxy curing agent and an epoxy-based reactive diluent can surprisingly provide a cured product having an excellent balance between heat resistance and toughness even when cured at low temperatures;
(2) A novel finding that, surprisingly, a curable resin composition containing a certain amount or more of polyamidoamine as an epoxy curing agent, in which the active hydrogen equivalent of the epoxy curing agent is within a specific range, and containing an epoxy-based reactive diluent can provide a cured product that has an excellent balance between heat resistance and toughness even when cured at low temperatures.

[2. Curable resin composition]
A curable resin composition according to one embodiment of the present invention is a curable resin composition for low-temperature curing, and includes the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
Satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

In this specification, the "curable resin composition" may be referred to as the "composition," and the "curable resin composition according to one embodiment of the present invention" may be referred to as the "composition."

Because this composition has the above-mentioned structure, it has the advantage of being able to provide a cured product that has an excellent balance of heat resistance and toughness when cured at low temperatures.

In this specification, a "cured product having an excellent balance between heat resistance and toughness" is intended to mean a cured product that satisfies one or more requirements selected from the group consisting of the following (i-1) and (i-2) and also satisfies one or more requirements selected from the group consisting of the following (ii-1), (ii-2), (ii-3), and (ii-4):
(i-1) The glass transition temperature (Tg), which is an index of heat resistance, is 80°C or higher;
(i-2) The storage modulus at 70°C, which is an index of heat resistance, is 0.14 GPa or more;
(ii-1) The fracture toughness (K1c), which is an index of toughness, is 1.10 MPa·m ^1/2 or more;
(ii-2) The shear bond strength, which is an index of toughness, is 18 MPa or more;
(ii-3) The T-peel adhesive strength, which is an index of toughness, is 100 N/25 mm or more;
(ii-4) Impact Peel strength, which is an index of toughness, is 17 kN/m or more.

<2-1. Component (A): Epoxy resin>
The present composition contains an epoxy resin as component (A). In this specification, the term "epoxy resin" refers to a resin having at least one epoxy group per molecule. The epoxy resin as component (A) is preferably a resin having two or more epoxy groups per molecule.

In this specification, "rubber-modified epoxy resins" and "urethane-modified epoxy resins" are not included in component (A), but are included in component (B). Furthermore, "epoxy resins with a viscosity of 500 mPa·s or less at 25°C" are sometimes referred to as "epoxy-based reactive diluents." In this specification, "epoxy resins with a viscosity of 500 mPa·s or less at 25°C," i.e., "epoxy-based reactive diluents," are not included in component (A), but are included in component (D). In other words, component (A) can also be referred to as "epoxy resins other than components (B) and (D)" or "epoxy resins other than component (B) that have a viscosity of more than 500 mPa·s at 25°C."

A resin with X epoxy groups per molecule is sometimes referred to as an "X-functional epoxy resin." For example, a resin with one epoxy group per molecule is called a "monofunctional epoxy resin," and a resin with two epoxy groups per molecule is called a "difunctional epoxy resin." Furthermore, a resin with two or more epoxy groups per molecule is sometimes called a "multifunctional epoxy resin."

Various epoxy resins can be used as the epoxy resin. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, novolac type epoxy resins, glycidyl ether type epoxy resins of bisphenol A propylene oxide adducts, hydrogenated bisphenol A (or F) type epoxy resins, fluorinated epoxy resins, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, and p-oxybenzoic acid glycidyl ether ester type epoxy resins. Examples include resins, m-aminophenol-type epoxy resins, diaminodiphenylmethane-based epoxy resins, various alicyclic epoxy resins, N,N-diglycidylaniline, N,N-diglycidyl-o-toluidine, triglycidyl isocyanurate, divinylbenzene dioxide, resorcinol diglycidyl ether, chelate-modified epoxy resins, hydantoin-type epoxy resins, epoxidized products of unsaturated polymers such as petroleum resins, aminoglycidyl ether resins, and epoxy compounds obtained by addition reaction of the above epoxy resins with bisphenol A (or F) or polybasic acids, etc.

Examples of commercially available bisphenol A type epoxy resins include those sold under the trade name jER by Mitsubishi Chemical Corporation (e.g., jER828, jER825, jER827, jER828EL, jER828US, jER828XA, jER834, jER1001, jER1002, jER1004, jER1007, jER1009, jER1010), and those sold by Momentive Specialty Chemicals, Inc. those commercially available under the trademark EPON from Olin Epoxy Co. (e.g., EPON 1510, EPON 1310, EPON 828, EPON 872, EPON 1001, EPON 1004, EPON 2004); Examples of such resins include, but are not limited to, those sold by ADEKA Corporation under the trade name DER (e.g., DER 331, DER 332, DER 336, and DER 439), those sold by ADEKA Corporation under the trade name ADEKA RESIN (e.g., EP-4100, EP-4300, EP-4400, EP-4530, EP-4504), and those sold by DIC Corporation under the trade name EPICLON (e.g., EPICLON 840, EPICLON 850).

Examples of commercially available bisphenol F epoxy resins include, but are not limited to, those sold under the jER trademark by Mitsubishi Chemical Corporation (e.g., jER806, jER806H, jER807, jER4005P, jER4007P, jER4010P), those sold under the DER trademark by Olin Epoxy Co. (e.g., DER 334), those sold under the ADEKA RESIN trademark by ADEKA Corporation (e.g., EP-4901, EP-4901E), and those sold under the EPICLON trademark by DIC Corporation (e.g., EPICLON 830).

Alicyclic epoxy resins are compounds that contain (i) one or more saturated or unsaturated aliphatic hydrocarbon rings and (ii) one or more epoxy groups in the molecule, and also include epoxy resins that contain cycloalkane rings. Examples of alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, tetrahydroindene diepoxide, vinylcyclohexene oxide, dipentene dioxide, bis(3,4-epoxycyclohexylmethyl) adipate, dicyclopentadiene dioxide, bis(2,3-epoxycyclopentyl)ether, 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, and epoxidized butanetetracarboxylic acid tetrakis. Examples of suitable epoxy resins include bis-(3-cyclohexenylmethyl)-modified epsilon-caprolactone, bi-7-oxabicyclo[4.1.0]heptane, dodecahydrobisphenol A diglycidyl ether, dodecahydrobisphenol F diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, hexahydroterephthalic acid diglycidyl ester, and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane (generic name: hydrogenated bisphenol A liquid epoxy resin). The alicyclic epoxy resin preferably contains one or more selected from the group consisting of 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, epoxidized butanetetracarboxylic acid tetrakis-(3-cyclohexenylmethyl)-modified epsilon-caprolactone, and diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane, more preferably consisting of only one or more selected from this group, more preferably containing diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane, and even more preferably consisting solely of diglycidyl ether of 2,2-bis(4-hydroxycyclohexyl)propane. This configuration has the advantages of providing a composition with low viscosity and excellent processability, and further providing a cured product obtained by curing the composition with excellent strength, elastic modulus, and heat resistance (high Tg). The elastic modulus of the cured product can be, for example, the storage modulus.

An example of an epoxy compound obtained by subjecting an epoxy resin to an addition reaction with a polybasic acid is the addition reaction product of a dimer of tall oil fatty acid (dimer acid) with a bisphenol A-type epoxy resin, as described in International Publication No. 2010-098950.

As the chelate-modified epoxy resin, for example, the resins described in paragraphs [0018] to [0019] of WO2016-163491 can be used.

Epoxy resins are not limited to these, and commonly used epoxy resins can be used. These epoxy resins may be used alone or in combination of two or more.

Among these epoxy resins, polyfunctional epoxy resins containing at least two epoxy groups per molecule are highly curable, produce highly flexible cured products, and are effective in improving the toughness of the cured product when polymer particles, as described below, are added. Furthermore, among polyfunctional epoxy resins, bifunctional epoxy resins produce cured products with high strength and an excellent balance between elastic modulus and elongation. Therefore, component (A) preferably contains a polyfunctional epoxy resin, more preferably consists solely of a polyfunctional epoxy resin, more preferably contains a bifunctional epoxy resin, and even more preferably is (consists solely of) a bifunctional epoxy resin.

The epoxy equivalent of the epoxy resin is preferably less than 220 g/eq, more preferably 90 g/eq or more but less than 210 g/eq, and even more preferably 135 g/eq or more but less than 200 g/eq. This configuration has the advantage of producing a cured product with a high elastic modulus and heat resistance.

In this specification, the term "epoxy equivalent" refers to the molecular weight per epoxy group contained in a compound having an epoxy group, and specifically, is a value calculated based on the following formula:
Epoxy equivalent (g/eq) = mass average molecular weight (Mw) of a compound / number of epoxy groups per molecule of a compound (average number).
The epoxy equivalent can also be measured in accordance with JIS K7236.

In this specification, bisphenol A epoxy resins are also referred to as component (a1), and bisphenol F epoxy resins are also referred to as component (a2). Among the above-mentioned epoxy resins, bisphenol A epoxy resins (component (a1)) and bisphenol F epoxy resins (component (a2)) produce cured products with high elastic modulus, excellent heat resistance and adhesion, and are relatively inexpensive. For this reason, component (A) preferably contains component (a1) and/or component (a2), and more preferably is component (a1) and/or component (a2) (composed exclusively of component (a1) and/or component (a2)). Furthermore, because a curable resin composition capable of providing a cured product with excellent heat resistance can be obtained at a low cost, component (A) further preferably contains component (a1), and particularly preferably is component (a1) (composed exclusively of component (a1)).

In this specification, difunctional bisphenol A epoxy resins are also referred to as component (a1'), and difunctional bisphenol F epoxy resins are also referred to as component (a2'). From the standpoint of the balance between elastic modulus and elongation, and strength, component (A) preferably contains component (a1') and/or component (a2'), and more preferably is component (a1') and/or component (a2') (composed solely of component (a1') and/or component (a2')).

From the standpoint of the balance between elastic modulus and elongation, and strength, the lower the content of tri- or higher functional epoxy resins as component (A) in this composition, the better. In this composition, the total content of tri- or higher functional epoxy resins per 100% by mass of component (A) is preferably 40% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 0% to 5% by mass. In this composition, the total content of tri- or higher functional epoxy resins per 100% by mass of component (A) may be 0% by mass. In other words, the composition does not need to contain tri- or higher functional epoxy resins as component (A).

The total content of components (a1) and (a2) in 100% by mass of component (A) is preferably 5% to 100% by mass, more preferably 10% to 100% by mass, more preferably 20% to 100% by mass, more preferably 30% to 100% by mass, more preferably 40% to 100% by mass, more preferably 50% to 100% by mass, more preferably 60% to 100% by mass, more preferably 70% to 100% by mass, more preferably 80% to 100% by mass, even more preferably 90% to 100% by mass, and even more preferably 95% to 100% by mass. This configuration has the advantage that the resulting cured product has superior toughness, impact resistance, heat resistance, and adhesion. The total content of components (a1) and (a2) in 100% by mass of component (A) may be 100% by mass. In other words, component (A) may be component (a1) and/or component (a2) (or may consist solely of component (a1) and/or component (a2)).

Of 100% by mass of component (A), the total content of components (a1') and (a2') is preferably 5% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, more preferably 20% by mass to 100% by mass, more preferably 30% by mass to 100% by mass, more preferably 40% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass. According to this configuration, the resulting cured product has the advantages of (i) superior toughness, impact resistance, heat resistance, and adhesion, and (ii) an excellent balance between elastic modulus and elongation. The total content of components (a1') and (a2') in 100% by mass of component (A) may be 100% by mass. In other words, component (A) may consist of components (a1') and/or (a2') (or may consist solely of components (a1') and/or (a2')).

In this specification, bisphenol A epoxy resins with an epoxy equivalent of less than 220 g/eq are also referred to as component (a1"), and bisphenol F epoxy resins with an epoxy equivalent of less than 220 g/eq are also referred to as component (a2"). In addition, in this specification, difunctional bisphenol A epoxy resins with an epoxy equivalent of less than 220 g/eq are also referred to as component (a1'"), and difunctional bisphenol F epoxy resins with an epoxy equivalent of less than 220 g/eq are also referred to as component (a2'").

Bisphenol A epoxy resins (a1"), which are component (a1") with an epoxy equivalent of less than 220 g/eq, and bisphenol F epoxy resins (a2"), which are component (a2") with an epoxy equivalent of less than 220 g/eq, are both liquid at room temperature and have excellent handleability. Therefore, it is more preferable that component (A) contains component (a1") and/or component (a2"). Furthermore, from the standpoint of the balance between elastic modulus and elongation, and strength, it is particularly preferable that component (A) contains component (a1"") and/or component (a2"").

The total content of components (a1") and (a2"), based on 100% by mass of component (A), is preferably 5% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, more preferably 20% by mass to 100% by mass, more preferably 30% by mass to 100% by mass, more preferably 40% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass. This configuration offers the following advantages: (i) the resulting cured product has superior toughness, impact resistance, heat resistance, and adhesion, and (ii) the composition has superior handleability. The total content of component (a1") and component (a2") may be 100% by mass of component (A). In other words, component (A) may consist of component (a1") and/or component (a2") (or may consist solely of component (a1") and/or component (a2")).

Of 100% by mass of component (A), the total content of components (a1''') and (a2''') is preferably 5% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, more preferably 20% by mass to 100% by mass, more preferably 30% by mass to 100% by mass, more preferably 40% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass. This configuration has the following advantages: (i) the resulting cured product has excellent toughness, impact resistance, heat resistance, and adhesion; (ii) the composition has excellent handleability; and (iii) the composition has an excellent balance between elastic modulus and elongation. The total content of components (a1''') and (a2''') in 100% by mass of component (A) may be 100% by mass. In other words, component (A) may be component (a1''') and/or component (a2''') (or may be composed solely of component (a1''') and/or component (a2''')).

From the viewpoint of toughness, the content of component (A) is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and even more preferably 30% by mass to 80% by mass, out of a total of 100% by mass of components (A) to (D).

<2-2. (B) Component>
The present composition includes, as component (B), one or more selected from the group consisting of polymer particles having a core-shell structure including a core layer and a shell layer (component (b1)), a blocked urethane (component (b2)), a rubber-modified epoxy resin (component (b3)), and a urethane-modified epoxy resin (component (b4)). The present composition may include, as component (B), at least component (b1), component (b2), component (b3), or component (b4). The present composition does not necessarily include, as component (B), all of component (b1), component (b2), component (b3), and component (b4).

[Component (b1): Polymer particles]
In this specification, "polymer particles having a core-shell structure comprising a core layer and a shell layer" refers to particles in which a core layer made of a core polymer and a shell layer made of a shell polymer form a layer structure. In this specification, "polymer particles having a core-shell structure comprising a core layer and a shell layer" may also be referred to as "core-shell polymer particles" or simply as "polymer particles."

When the present composition contains polymer particles, which are component (b1), as component (B), the polymer particles can exhibit a toughness-improving effect within the composition. As a result, by including polymer particles as component (B), the present composition has the advantage of being able to provide a cured product (e.g., adhesive layer) with excellent toughness, even when cured at low temperatures. Furthermore, when the present composition contains polymer particles as component (B), the adhesive strength (e.g., impact peel strength) of the resulting cured product tends to be excellent.

Polymer particles can be obtained by graft polymerizing a graft-copolymerizable monomer (a monomer for forming a shell layer) in the presence of a core layer to form a shell layer. More specifically, this polymerization operation can be carried out by adding a monomer for forming a shell layer (shell polymer) to a latex of a core polymer prepared in the form of an aqueous polymer latex, and polymerizing the resulting mixture. In polymer particles, it is preferable that the core polymer and shell polymer are substantially chemically bonded. Note that in polymer particles, the core layer and shell layer do not need to form a complete layer structure. The shell layer (shell polymer) need only cover at least a portion of the core layer (core polymer), and does not need to cover the entire core layer. Furthermore, part of the shell layer may penetrate into the core layer.

Each layer of the polymer particles is explained in detail below.

<Core layer>
The core layer is preferably an elastic core layer having rubber properties in order to enhance the toughness of the cured product of the composition.

The core layer preferably contains a diene-based rubber because it effectively improves the toughness of the resulting cured product, effectively improves the impact peel strength of the resulting cured product, and is less likely to experience an increase in viscosity over time due to swelling of the core layer due to its low affinity with component (A). The core layer preferably contains a (meth)acrylate-based rubber because a wide range of polymer compositions can be designed by combining a variety of monomers. Furthermore, to improve impact resistance at low temperatures without reducing the heat resistance of the cured product, the core layer preferably contains an organosiloxane-based rubber. In other words, the core layer of the polymer particles, which are component (b1), preferably contains one or more rubbers selected from the group consisting of diene-based rubbers, (meth)acrylate-based rubbers, and organosiloxane-based rubbers.

(Diene rubber)
The diene rubber is preferably a polymer containing 50% by mass to 100% by mass of conjugated diene units and 0% by mass to 50% by mass of structural units derived from vinyl monomers other than conjugated diene monomers copolymerizable with the conjugated diene monomers.

Examples of conjugated diene monomers from which the conjugated diene units are derived include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), and 2-chloro-1,3-butadiene.

These conjugated diene monomers may be used alone or in combination of two or more.

The content of conjugated diene units in the core layer (e.g., diene rubber) is preferably 50% to 100% by mass, more preferably 70% to 100% by mass, and even more preferably 90% to 100% by mass, out of 100% by mass of all structural units constituting the core layer. If the content of conjugated diene units in the core layer (e.g., diene rubber) is 50% by mass or more, the toughness of the resulting cured product can be improved.

Examples of vinyl monomers other than conjugated diene monomers that can be copolymerized with conjugated diene monomers include vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinyl carboxylic acids such as acrylic acid and methacrylic acid; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; vinyl acetate; alkenes such as ethylene, propylene, butylene, and isobutylene; and polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

These vinyl monomers may be used alone or in combination of two or more. Styrene is particularly preferred as a vinyl monomer other than a conjugated diene monomer that is copolymerizable with a conjugated diene monomer.

The core layer of the polymer particles, which is component (b1), preferably contains, among diene rubbers, butadiene rubber, a homopolymer of 1,3-butadiene, and/or butadiene-styrene rubber, a copolymer of 1,3-butadiene and styrene, because of the greater toughness-improving effect of the resulting cured product, the greater impact peel strength-improving effect of the resulting cured product, and the lower affinity with component (A) makes it less likely for the core layer to increase in viscosity over time due to swelling. It is more preferable for the core layer to be (composed exclusively of) butadiene rubber and/or butadiene-styrene rubber, even more preferable for it to contain butadiene rubber, and particularly preferable for it to be (composed exclusively of) butadiene rubber. Butadiene-styrene rubber is also preferred because it can enhance the transparency of the resulting cured product by adjusting the refractive index.

((Meth)acrylate rubber)
The (meth)acrylate rubber is preferably a polymer obtained by polymerizing a monomer mixture containing 50% by mass to 100% by mass of (meth)acrylate units and 0% by mass to 50% by mass of structural units derived from vinyl monomers other than (meth)acrylate monomers that are copolymerizable with the (meth)acrylate monomers. In this specification, "(meth)acrylate" means acrylate and/or methacrylate.

Examples of (meth)acrylate monomers from which the (meth)acrylate units are derived include: (i) alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (ii) aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; (iii) hydroxyalkanol (meth)acrylates; (iv) glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; (v) alkoxyalkyl (meth)acrylates; (vi) allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; (vii) multifunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate.

Hydroxyalkyl (meth)acrylates include linear hydroxy alkyl (meth)acrylates (particularly linear C1-6 hydroxy alkyl (meth)acrylates) such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; caprolactone-modified hydroxy (meth)acrylates; branched hydroxy alkyl (meth)acrylates such as methyl α-(hydroxymethyl)acrylate and ethyl α-(hydroxymethyl)acrylate; and hydroxyl group-containing (meth)acrylates such as mono(meth)acrylates of polyester diols (particularly saturated polyester diols) obtained from divalent carboxylic acids (such as phthalic acid) and dihydric alcohols (such as propylene glycol).

These (meth)acrylate monomers may be used alone or in combination of two or more. The (meth)acrylate unit is preferably one or more selected from the group consisting of ethyl (meth)acrylate units, butyl (meth)acrylate units, and 2-ethylhexyl (meth)acrylate units.

Examples of vinyl monomers other than (meth)acrylate monomers copolymerizable with (meth)acrylate monomers include: (i) vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; (ii) vinyl carboxylic acids such as acrylic acid and methacrylic acid; (iii) vinyl cyanides such as acrylonitrile and methacrylonitrile; (iv) vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; (v) vinyl acetate; (vi) alkenes such as ethylene, propylene, butylene, and isobutylene; and (vii) polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

The vinyl monomer other than (meth)acrylate monomers copolymerizable with (meth)acrylate monomers may be used alone or in combination of two or more. Styrene is particularly preferred as the vinyl monomer other than (meth)acrylate monomers copolymerizable with (meth)acrylate monomers, as it can easily increase the refractive index.

(organosiloxane rubber)
Examples of the organosiloxane rubber include: (i) polysiloxane polymers composed of alkyl or aryl di-substituted silyloxy units, such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy; and (ii) polysiloxane polymers composed of alkyl or aryl mono-substituted silyloxy units, such as organohydrogensilyloxy in which some of the alkyl groups in the side chains have been substituted with hydrogen atoms.

These polysiloxane-based polymers may be used alone or in combination of two or more. Of these, dimethylsilyloxy, methylphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy are preferred because they can impart heat resistance to the cured product, with dimethylsilyloxy being the most preferred because it is easily available.

The glass transition temperature (hereinafter sometimes simply referred to as "Tg") of the core layer is preferably 0°C or lower, more preferably -20°C or lower, even more preferably -40°C or lower, and particularly preferably -60°C or lower, in order to enhance the toughness of the resulting cured product.

The volume average particle diameter of the core layer is not particularly limited, but is preferably 0.03 μm to 2.00 μm, more preferably 0.05 μm to 1.00 μm, more preferably 0.12 μm to 0.50 μm, more preferably 0.12 μm to 0.28 μm, and even more preferably 0.14 to 0.25 μm. If the volume average particle diameter of the core layer is within this range, the core layer can be produced stably, and the cured product can have good heat resistance and toughness. The method for measuring the volume average particle diameter of the core layer will be explained in detail in the Examples below.

The core layer may have a single layer structure, or a multilayer structure consisting of multiple layers each having rubber elasticity. Furthermore, if the core layer has a multilayer structure, the polymer composition of each layer may be different within the range disclosed above.

The composition of the structural units of the core layer depends on the composition of the monomers used to form the core layer. When the polymerization conversion rate is 100%, the resulting core layer contains structural units derived from all of the monomers contained in the monomers used to form the core layer.

In one embodiment of the present invention, an intermediate layer, such as that described in paragraphs [0046] to [0049] of WO2016-163491, can be provided between the core layer and the shell layer.

<Shell layer>
The shell layer is a polymer obtained by polymerizing a monomer for forming the shell layer. The polymer constituting the shell layer (shell polymer) plays a role of improving the compatibility between the polymer particles and component (A) and enabling the polymer particles to be dispersed in the form of primary particles in the composition and/or a cured product of the composition.

There are no particular restrictions on the type and content ratio of the structural units contained in the shell layer. From the standpoint of compatibility and dispersibility of the polymer particles in the composition, the shell layer of the polymer particles (component (b1)) preferably contains one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units, more preferably (meth)acrylate units, and particularly preferably methyl methacrylate units.

The composition of the structural units of the shell layer depends on the composition of the monomers used to form the shell layer. When the polymerization conversion rate is 100%, the resulting shell layer contains structural units derived from all of the monomers contained in the monomers used to form the shell layer.

The total content of one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units in the shell layer is preferably 10.0% to 99.5% by mass, more preferably 50.0% to 99.0% by mass, even more preferably 65.0% to 98.0% by mass, particularly preferably 67.0% to 80.0% by mass, and most preferably 67.0 to 85.0% by mass, based on 100% by mass of the shell layer (shell polymer).

Specific examples of aromatic vinyl monomers from which the aromatic vinyl units are derived include vinylbenzenes such as styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

Specific examples of vinylcyanide monomers from which the vinylcyanide units are derived include acrylonitrile and methacrylonitrile.

Specific examples of the (meth)acrylate monomers from which the (meth)acrylate units are derived are the same as those described above in the section on "Core Layer," so that description is incorporated herein by reference and will not be repeated here.

In order to maintain a good dispersion state without the polymer particles agglomerating in the cured product and composition, it is preferable to chemically bond the polymer particles to component (A). In order to chemically bond the polymer particles to component (A), it is preferable that the shell layer contain structural units derived from a reactive group-containing monomer. In other words, it is preferable that the shell layer contain a reactive group.

The reactive group is preferably one or more selected from the group consisting of, for example, an epoxy group, an oxetane group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic acid anhydride group, a cyclic ester, a cyclic amide, a benzoxazine group, and a cyanate ester group.

The reactive group is preferably an epoxy group. In other words, the shell layer preferably has a structural unit derived from a monomer having an epoxy group, i.e., it preferably has an epoxy group. When the shell layer of the polymer particle has an epoxy group, the composition has excellent storage stability, and has the advantage of being able to provide a cured product with excellent toughness even when the composition is cured at low temperatures.

Specific examples of the monomer having an epoxy group include glycidyl group-containing vinyl monomers such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether.

If the shell layer of the polymer particle contains epoxy groups, the content (mmol) of epoxy groups in the shell layer relative to the total mass (g) of the shell layer of the polymer particle is preferably greater than 0 mmol/g and less than 2.0 mmol/g, more preferably 0.1 mmol/g to 2.0 mmol/g, and even more preferably 0.3 mmol/g to 1.5 mmol/g. This configuration suppresses aggregation of the polymer particles, allowing the polymer particles to be dispersed in the cured product as primary particles. As a result, it is believed that the toughness of the cured product can be improved even when cured at low temperatures.

Monomers having epoxy groups are preferably used to form the shell layer, and more preferably only to form the shell layer. In other words, it is preferable that the core layer and intermediate layer do not have epoxy groups.

From the viewpoint of storage stability of the composition, it is preferable that the shell layer of the polymer particles does not contain epoxy groups.

Specific examples of the reactive group-containing monomer having a hydroxyl group include the hydroxyalkyl (meth)acrylates mentioned above.

When the shell layer contains structural units derived from a polyfunctional monomer having two or more radically polymerizable double bonds, swelling of the polymer particles in the composition is prevented, and the composition tends to have a low viscosity and be easier to handle. For this reason, it is preferable that the shell layer contains structural units derived from the polyfunctional monomer. On the other hand, from the perspective of achieving an excellent effect of improving the toughness and impact peel strength of the resulting cured product, it is preferable that the shell layer does not contain structural units derived from the polyfunctional monomer.

Specific examples of the polyfunctional monomer do not include conjugated diene monomers such as butadiene, and include allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; allyloxyalkyl (meth)acrylates; polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as (poly)ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

Among these polyfunctional monomers, allyl methacrylate and triallyl isocyanurate are preferred.

The shell layer is preferably a polymer composed only of the following structural units: (a) aromatic vinyl units (particularly preferably styrene units) 0% to 50% by mass (preferably 0% to 35% by mass, more preferably 0% to 20% by mass), (b) vinylcyan units (particularly preferably acrylonitrile units) 0% to 50% by mass (preferably 0% to 30% by mass, more preferably 0% to 20% by mass), (c) (meth)acrylate units ((i) preferably one or more structural units selected from the group consisting of methyl acrylate units, butyl acrylate units, and methyl methacrylate units, (ii) particularly preferably methyl methacrylate units) 0% to 100% by mass (preferably 5% to 100% by mass, more preferably 70% to 95% by mass), and (d) structural units derived from a monomer having an epoxy group (particularly glycidyl methacrylate units) 0% to 50% by mass (preferably 1% to 35% by mass, more preferably 3% to 20% by mass). However, (i) the total of the structural units derived from aromatic vinyl units, vinylcyan units, (meth)acrylate units, and monomers having an epoxy group is 100% by mass, and (ii) 0% by mass means that these structural units may not be included.

The above-mentioned monomer components may be used alone or in combination of two or more. The shell layer may also contain structural units derived from monomers other than the above-mentioned monomers.

The shell layer may have a single-layer structure, but it may also have a multi-layer structure. Furthermore, if the shell layer has a multi-layer structure, the polymer composition of each layer may be different within the range disclosed above.

<Volume average particle diameter (Mv) of polymer particles>
The volume average particle diameter (Mv) of the polymer particles is not particularly limited, but from the viewpoint of industrial productivity and workability of the curable resin composition, it is preferably 0.01 μm to 2.00 μm, more preferably 0.02 μm to 1.00 μm, more preferably 0.03 μm to 0.60 μm, more preferably 0.05 μm to 0.40 μm, more preferably 0.10 μm to 0.30 μm, more preferably 0.15 μm to 0.30 μm, more preferably 0.16 μm to 0.28 μm, more preferably 0.17 μm to 0.27 μm, and even more preferably 0.18 μm to 0.25 μm. When the volume average particle diameter (Mv) of the polymer particles is (a) 0.01 μm or more, the viscosity of the composition is reduced, which is advantageous in that workability is improved, and when it is (b) 2.00 μm or less, the polymerization time of the polymer particles is shortened, which is advantageous in that industrial productivity is increased. The method for measuring the volume average particle diameter (Mv) of the polymer particles will be described in detail in the Examples below.

When the composition contains polymer particles as component (B), the polymer particles are preferably dispersed in the composition in the form of primary particles. As used herein, "polymer particles dispersed in the form of primary particles" (hereinafter also referred to as "primary dispersion") means that the polymer particles are dispersed substantially independently (without contact). The state of dispersion of the polymer particles in the composition can be confirmed, for example, by mixing a portion of the composition with a solvent such as methyl ethyl ketone, subjecting the resulting mixture to a particle size measurement device that uses laser light scattering, and measuring the particle size of the polymer particles in the mixture.

Furthermore, a "stable dispersion" of polymer particles means a state in which the polymer particles remain dispersed steadily under normal conditions for an extended period of time in the continuous layer without agglomerating, separating, or precipitating. It is also preferable that the distribution of the polymer particles in the continuous layer does not change substantially, and that the "stable dispersion" can be maintained even when these compositions are heated within a non-hazardous range to reduce the viscosity and then stirred.

One type of polymer particle may be used alone, or two or more types may be used in combination.

<Method for producing polymer particles>
(Method for manufacturing core layer)
The core layer constituting the polymer particles can be formed by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, etc. As the emulsion polymerization, suspension polymerization, microsuspension polymerization, etc., the methods described in WO 2005/028546 and WO 2006/070664 can be appropriately used.

(Method of forming shell layer and intermediate layer)
When the polymer particles contain an intermediate layer, the intermediate layer can be formed by polymerizing a monomer for forming the intermediate layer by known radical polymerization. When the rubber elastic material constituting the core layer is obtained as an emulsion, the polymerization of the monomer for forming the intermediate layer is preferably carried out by emulsion polymerization.

The shell layer can be formed by polymerizing the shell layer-forming monomer using known radical polymerization. When the core layer, or the polymer particle precursor comprising the core layer coated with the intermediate layer, is obtained as an emulsion, it is preferable to polymerize the shell layer-forming monomer using an emulsion polymerization method. For example, the method described in WO 2005/028546 can be used as the emulsion polymerization method.

In emulsion polymerization, an emulsifier (dispersant) is used.

Emulsifiers include (i) (i-1) various acids such as alkyl or aryl sulfonic acids typified by dioctylsulfosuccinic acid and dodecylbenzenesulfonic acid; alkyl or aryl ether sulfonic acids; alkyl or aryl sulfuric acids typified by dodecyl sulfate; alkyl or aryl ether sulfuric acids; alkyl or aryl substituted phosphoric acids; alkyl or aryl ether substituted phosphoric acids; N-alkyl or aryl sarcosinic acids typified by dodecyl sarcosinic acid; alkyl or aryl carboxylic acids typified by oleic acid and stearic acid; alkyl or aryl ether carboxylic acids; and (i-2) anionic emulsifiers (dispersants) such as alkali metal salts or ammonium salts of these acids; (ii) nonionic emulsifiers (dispersants) such as alkyl or aryl substituted polyethylene glycol; and (iii) dispersants such as polyvinyl alcohol, alkyl substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives.

These emulsifiers (dispersants) may be used alone or in combination of two or more.

It is preferable to use a small amount of emulsifier (dispersant) as long as it does not impair the dispersion stability of the aqueous latex of polymer particles. Furthermore, the more water-soluble the emulsifier (dispersant), the better. High water solubility makes it easier to wash off the emulsifier (dispersant) with water, and makes it easier to prevent adverse effects on the final cured product.

When emulsion polymerization is used, peroxides (e.g., organic peroxides), chain transfer agents, surfactants, etc. can be used as needed.

The polymerization conditions, such as polymerization temperature, pressure, and deoxygenation, can be within known ranges.

It is preferable that the composition contains at least polymer particles as component (B), as this provides an excellent balance between the storage stability of the resulting composition and the toughness-improving effect and impact peel strength of the resulting cured product.

When the composition contains polymer particles as component (B), the content of the polymer particles in the composition is preferably 1 to 100 parts by mass, more preferably 5 to 90 parts by mass, even more preferably 10 to 80 parts by mass, even more preferably 20 to 70 parts by mass, and particularly preferably 30 to 60 parts by mass, per 100 parts by mass of component (A). This configuration has the advantage of providing an excellent balance between the storage stability of the resulting composition and the toughness-improving effect and impact peel strength of the resulting cured product.

[Component (b2): Blocked urethane]
In this specification, the term "blocked urethane" refers to an "elastomeric compound containing urethane groups and/or urea groups and having terminal isocyanate groups," in which all or some of the terminal isocyanate groups have been capped with various blocking agents having active hydrogen groups. The compound capped with a blocking agent, i.e., the blocked urethane itself, may be an elastomer. As the blocked urethane, a compound in which all of the terminal isocyanate groups have been capped with a blocking agent is particularly preferred. Blocked urethanes can be obtained, for example, by the following methods: (A) (A-1) reacting an organic polymer having an active hydrogen-containing group at its terminal with an excess of a polyisocyanate compound to obtain a polymer (urethane prepolymer) having urethane groups and/or urea groups in the main chain and isocyanate groups at its terminal; (A-2) subsequently capping all or some of the isocyanate groups with a blocking agent having an active hydrogen group; or (B) reacting an organic polymer having an active hydrogen-containing group at its terminal with an excess of a polyisocyanate compound and simultaneously reacting it with a blocking agent, thereby capping all or some of the isocyanate groups of the urethane prepolymer with the blocking agent having an active hydrogen group.

Specific examples of blocked urethanes include the compounds described in WO 2016/163491.

The number average molecular weight of the blocked urethane, measured by GPC in terms of polystyrene equivalent, is preferably 2,000 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. The molecular weight distribution (weight average molecular weight/number average molecular weight) of the blocked urethane is preferably 1.0 to 4.0, more preferably 1.2 to 3.0, and particularly preferably 1.5 to 2.5.

A single type of blocked urethane may be used alone, or two or more types may be used in combination.

From the standpoint of improving the toughness, impact resistance, and adhesion (e.g., impact peel strength) of the resulting cured product, it is preferable that the composition contain at least a blocked urethane as component (B).

When the composition contains a blocked urethane as component (B), the content of the blocked urethane in the composition is, from the above-mentioned viewpoints, preferably 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, and particularly preferably 5 to 30 parts by mass, per 100 parts by mass of component (A). When the content of the blocked urethane in the composition is (a) 1 part by mass or more per 100 parts by mass of component (A), the toughness, impact resistance, and adhesion (e.g., impact peel strength) of the cured product obtained by curing the resulting composition are favorably improved; and when (b) 50 parts by mass or less, the resulting cured product has the advantage of excellent heat resistance and a high elastic modulus.

[Component (b3): Rubber-modified epoxy resin]
The rubber-modified epoxy resin is a reaction product obtained by reacting rubber with an epoxy group-containing compound (e.g., an epoxy resin). The rubber-modified epoxy resin preferably has an average of 1.1 or more epoxy groups per molecule, more preferably 2 or more epoxy groups.

Examples of rubber include rubber-based polymers such as acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), ethylene-propylene rubber (EPDM), acrylic rubber (ACM), butyl rubber (IIR), butadiene rubber, and polyoxyalkylenes (e.g., polypropylene oxide, polyethylene oxide, polytetramethylene oxide, etc.). The rubber-based polymer preferably has a terminal reactive group (a functional group capable of reacting with an epoxy group), such as an amino group, a hydroxy group, or a carboxyl group. The rubber-modified epoxy resin used in one embodiment of the present invention is a reaction product obtained by reacting these rubber-based polymers with an epoxy group-containing compound (e.g., an epoxy resin) in an appropriate blending ratio using a known method. Among these, acrylonitrile-butadiene rubber-modified epoxy resins and polyoxyalkylene-modified epoxy resins are preferred as rubber-modified epoxy resins, from the viewpoint of the adhesiveness and impact peel adhesion resistance of the resulting curable resin composition, with acrylonitrile-butadiene rubber-modified epoxy resins being more preferred. Acrylonitrile-butadiene rubber-modified epoxy resin can be obtained, for example, by reacting carboxyl-terminated NBR (CTBN) with bisphenol A-type epoxy resin.

The content of the acrylonitrile monomer component (acrylonitrile unit) in the acrylonitrile-butadiene rubber (100% by mass) is preferably 5% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 15% by mass to 30% by mass, from the viewpoint of the adhesiveness and impact peel adhesion resistance of the resulting curable resin composition. The content of the acrylonitrile monomer component (acrylonitrile unit) in the acrylonitrile-butadiene rubber (100% by mass) is particularly preferably 20% by mass to 30% by mass, from the viewpoint of the workability of the resulting curable resin composition.

Furthermore, rubber-modified epoxy resins also include, for example, addition reaction products (hereinafter also referred to as "adducts") between amino-terminated polyoxyalkylenes and epoxy resins. The adducts can be easily produced by known methods, as described, for example, in U.S. Pat. Nos. 5,084,532 and 6,015,865. Examples of the epoxy resins used in producing the adducts include the specific examples of component (A) listed above. As the epoxy resins used in producing the adducts, bisphenol A epoxy resins and bisphenol F epoxy resins are preferred, with bisphenol A epoxy resins being more preferred. Commercially available amino-terminated polyoxyalkylenes used in producing the adduct include, for example, Jeffamine (registered trademark) D-230, Jeffamine (registered trademark) D-400, Jeffamine (registered trademark) D-2000, Jeffamine (registered trademark) D-4000, and Jeffamine (registered trademark) T-5000, all manufactured by Huntsman.

The reactive groups contained at the molecular terminals of the rubber are sometimes referred to as "epoxide reactive end groups." The average number of epoxide reactive end groups contained per rubber molecule is preferably 1.5 to 2.5, and more preferably 1.8 to 2.2. The number average molecular weight of the rubber, measured by GPC in terms of polystyrene, is preferably 1,000 to 10,000, more preferably 2,000 to 8,000, and particularly preferably 3,000 to 6,000.

There are no particular limitations on the method for producing rubber-modified epoxy resins. For example, rubber-modified epoxy resins can be produced by reacting rubber with an epoxy group-containing compound in a large amount of epoxy group-containing compound. Specifically, it is preferable to produce rubber-modified epoxy resins by reacting two or more equivalents of epoxy group-containing compound per equivalent of epoxy reactive terminal groups in the rubber. It is more preferable to react a sufficient amount of epoxy group-containing compound with rubber so that the resulting product is a mixture of an adduct of rubber and epoxy group-containing compound and free epoxy group-containing compound. For example, rubber-modified epoxy resins can be produced by heating a mixture of rubber and epoxy group-containing compound to a temperature of 100°C to 250°C in the presence of a catalyst such as phenyldimethylurea and triphenylphosphine. There are no particular limitations on the epoxy group-containing compound used in producing rubber-modified epoxy resins, but bisphenol A epoxy resins and bisphenol F epoxy resins are preferred, with bisphenol A epoxy resins being more preferred.

In rubber-modified epoxy resins, the epoxy resin can be modified by pre-reacting a bisphenol component with rubber. The amount of bisphenol component used for modification is preferably 3 to 35 parts by mass, and more preferably 5 to 25 parts by mass, per 100 parts by mass of the rubber component in the rubber-modified epoxy resin. The cured product obtained by curing a curable resin composition containing the modified rubber-modified epoxy resin exhibits excellent adhesion durability after exposure to high temperatures and also excellent impact resistance at low temperatures.

There are no particular restrictions on the glass transition temperature (Tg) of the rubber-modified epoxy resin, but it is preferably -25°C or lower, more preferably -35°C or lower, even more preferably -40°C or lower, and particularly preferably -50°C or lower.

The number average molecular weight of the rubber-modified epoxy resin, measured by GPC in terms of polystyrene, is preferably 1,500 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight (weight average molecular weight/number average molecular weight)) of the rubber-modified epoxy resin is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

From the viewpoint of the balance of toughness, impact peel strength, heat resistance, and modulus of elasticity (rigidity) of the cured product, it is preferable that the composition contain at least a rubber-modified epoxy resin as component (B).

When the composition contains a rubber-modified epoxy resin as component (B), the content of the rubber-modified epoxy resin in the composition is preferably 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, even more preferably 5 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass, per 100 parts by mass of component (A). When the content of the rubber-modified epoxy resin in the composition is (a) 1 part by mass or more per 100 parts by mass of component (A), the resulting cured product has the advantage of excellent toughness and good Impact Peel strength, and when (b) 50 parts by mass or less, the resulting cured product has the advantage of good heat resistance and/or elastic modulus (rigidity).

The rubber-modified epoxy resin may be used alone or in combination of two or more types.

[Component (b3): Urethane-modified epoxy resin]
The urethane-modified epoxy resin is a reaction product obtained by reacting (i) a compound containing an epoxy group and a group reactive with an isocyanate group with (ii) a urethane prepolymer containing an isocyanate group. The urethane-modified epoxy resin preferably has an average of 1.1 or more epoxy groups per molecule, more preferably 2 or more. For example, a urethane-modified epoxy resin can be obtained by reacting a hydroxyl-containing epoxy compound with a urethane prepolymer.

The number average molecular weight of the urethane-modified epoxy resin, measured by GPC in terms of polystyrene, is preferably 1,500 to 40,000, more preferably 3,000 to 30,000, and particularly preferably 4,000 to 20,000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight (weight average molecular weight/number average molecular weight)) of the urethane-modified epoxy resin is preferably 1 to 4, more preferably 1.2 to 3, and particularly preferably 1.5 to 2.5.

From the viewpoint of balancing the toughness and heat resistance of the cured product, it is preferable that the composition contain at least a rubber-modified epoxy resin as component (B).

When the composition contains a urethane-modified epoxy resin as component (B), the content of the urethane-modified epoxy resin in the composition is preferably 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, even more preferably 5 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass, per 100 parts by mass of component (A). When the content of the urethane-modified epoxy resin in the composition is (a) 1 part by mass or more per 100 parts by mass of component (A), the resulting cured product has the advantage of excellent toughness, and when (b) 50 parts by mass or less, the resulting cured product has the advantage of good heat resistance.

The urethane-modified epoxy resin may be used alone or in combination of two or more types.

In this composition, the content of component (B) per 100 parts by mass of component (A) is preferably 1 to 200 parts by mass, more preferably 5 to 150 parts by mass, even more preferably 10 to 100 parts by mass, even more preferably 20 to 90 parts by mass, and particularly preferably 30 to 80 parts by mass. This configuration has the advantage that the resulting cured product has excellent toughness, impact resistance, and adhesion (e.g., impact peel strength). Note that the "content of component (B)" refers to the total content of components (b1), (b2), (b3), and (b4) contained in the composition.

2-3. Component (C): Epoxy curing agent
The present composition contains an epoxy curing agent as component (C). In this specification, the term "epoxy curing agent" refers to a compound (including an oligomer or polymer) containing an active hydrogen group that can react with the epoxy resin (A) to form a crosslink.

The present composition preferably contains, as component (C), an epoxy curing agent that is active at low temperatures. In this specification, "epoxy curing agent that is active at low temperatures" refers to "a compound (including oligomers or polymers) containing active hydrogen groups that can react with component (A) to form crosslinks even at low temperatures (e.g., from 0°C to less than 120°C)."

Epoxy curing agents that are active at low temperatures include amine-based curing agents. More specific examples of epoxy curing agents that are active at low temperatures include alicyclic amines (also known as "cyclic aliphatic polyamines"), aliphatic amines (also known as "chain aliphatic polyamines"), polyamidoamines, amine-terminated polyethers, amine-terminated butadiene nitrile rubber, modified alicyclic amines, modified aliphatic amines, modified polyamidoamines, modified amine-terminated polyethers, and modified amine-terminated butadiene nitrile rubber.

Examples of the alicyclic amines (alicyclic polyamines) include N-aminoethylpiperazine, piperazine, 1-(2-hydroxyethyl)piperazine, 2-methylpiperazine, 1-methylpiperazine, 2,5-dimethylpiperazine, menthenediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, which is a type of spiroacetal diamine, norbornanediamine, bis(aminomethyl)tricyclodecane, and 1,3-bis(aminomethyl)cyclohexane.

Examples of the aliphatic amine (chain aliphatic polyamine) include chain aliphatic polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, diethylaminopropylamine, hexamethylenediamine, 3-diethylaminopropylamine, 3-dimethylaminopropylamine, 2-diethylaminoethylamine, and 2-dimethylaminoethylamine, as well as aliphatic aromatic amines such as metaxylenediamine.

The polyamidoamine is a compound produced by condensing (i) (i-1) a dicarboxylic acid such as a dimer (dimer acid) of tall oil fatty acid, and/or (i-2) a monocarboxylic acid such as tall oil fatty acid, oleic acid, or neodecanoic acid, with (ii) a polyamine such as triethylenetetramine or tetraethylenepentamine. Commercially available polyamidoamines include Ancamide 910, Ancamide 350A, Versamid 140, and Versamid 115.

The amine-terminated polyether has a polyether main chain and preferably has an average of 1 to 4 (more preferably 1.5 to 3) amino and/or imino groups per molecule. Examples of the amine-terminated polyether include poly(oxypropylene) monoamine, poly(oxypropylene) diamine, poly(oxypropylene) triamine, and poly(oxypropylene) tetraamine. Commercially available amine-terminated polyethers include Huntsman's Jeffamine D-230 (poly(oxypropylene)diamine), Jeffamine D-400 (poly(oxypropylene)diamine), Jeffamine D-2000 (poly(oxypropylene)diamine), Jeffamine D-4000 (poly(oxypropylene)diamine), and Jeffamine T-5000 (poly(oxypropylene)triamine).

Examples of modified amine-based curing agents include (i) polyamine epoxy resin adducts, which are reaction products of various polyamines such as the above-mentioned aliphatic amines and alicyclic amines with less than an equivalent amount of epoxy resin, and (ii) ketimines, which are dehydration reaction products of polyamines with ketones such as methyl ethyl ketone and isobutyl methyl ketone.

Component (C) of this composition satisfies the following (1) and/or (2):

(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

Below, a curable resin composition that satisfies at least the above-mentioned (1) will be described. In this specification, the alicyclic amine is also referred to as component (c1). In this specification, a curable resin composition that satisfies at least the above-mentioned (1) may be referred to as "composition (1)." Composition (1) contains, as component (C), an alicyclic amine, which is component (c1). When this composition contains, as component (C), an alicyclic amine, which is component (c1), an advantage is that when the composition is cured at low temperatures, a cured product with an excellent balance of heat resistance and toughness can be obtained.

The alicyclic amine component (c1) includes (i) one or more selected from the group consisting of isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, piperazine, 1-(2-hydroxyethyl)piperazine, 2-methylpiperazine, 1-methylpiperazine, 2,5-dimethylpiperazine, and menthenediamine. (ii) isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,3-bis(aminomethyl)cyclohexane; and (iii) isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,3-bis(aminomethyl)cyclohexane; and (iv) isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,3-bis(aminomethyl)cyclohexane; and (v) isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,3-bis(aminomethyl)cyclohexane; and (vi ...cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, 1-(2-hydroxyethyl)piperazine, and 1,3-bis(aminomethyl)cyclohexane; and (vi) isophoronediamine, 4,4'-methylenebis(cyclohex (iii) more preferably contains one or more selected from the group consisting of isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, and 1,3-bis(aminomethyl)cyclohexane, and more preferably consists of only one or more selected from this group; (iv) more preferably contains one or more selected from the group consisting of isophoronediamine, 4,4'-methylenebis(cyclohexylamine), and 4,4'-methylenebis(2-methylcyclohexylamine), and more preferably consists of only one or more selected from this group; and (v) even more preferably contains one or more selected from the group consisting of 4,4'-methylenebis(cyclohexylamine) and 4,4'-methylenebis(2-methylcyclohexylamine), and particularly preferably consists of only one or more selected from this group. This configuration has the advantage that the resulting cured product has an excellent balance between toughness and heat resistance.

In composition (1), the content of component (c1) is 25% by mass to 100% by mass, preferably 30% by mass to 100% by mass, more preferably 40% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. This configuration has the advantage that the resulting cured product has an excellent balance between toughness and heat resistance. The content of component (c1) may be 100% by mass out of 100% by mass of component (C); in other words, component (C) may consist solely of component (c1).

In composition (1), the content of component (c1) in a total amount of 100% by mass of the composition is preferably 3.5% by mass to 30.0% by mass, more preferably 3.6% by mass to 27.0% by mass, even more preferably 3.7% by mass to 24.0% by mass, even more preferably 3.8% by mass to 22.0% by mass, even more preferably 3.9% by mass to 20.0% by mass, even more preferably 4.0% by mass to 18.0% by mass, and particularly preferably 8.0% by mass to 15.0% by mass. This configuration has the advantage that the resulting cured product has excellent toughness.

Below, a curable resin composition that satisfies at least the above-mentioned (2) will be described. In this specification, polyamidoamine is also referred to as component (c2). In this specification, a curable resin composition that satisfies at least the above-mentioned (2) may be referred to as "composition (2)." Composition (2) contains polyamidoamine, which is component (c2), as component (C). When this composition contains polyamidoamine, which is component (c2), as component (C), it has the advantage that a cured product with excellent toughness can be obtained when the composition is cured at low temperatures.

Furthermore, in composition (2), the active hydrogen equivalent of component (C) is 50 g/eq to 90 g/eq. Having the active hydrogen equivalent of component (C) in this range has the advantage that when the composition is cured at low temperatures, a cured product with an excellent balance of heat resistance and toughness can be obtained.

When component (C) contains multiple epoxy curing agents (1, 2, 3, ..., i), the active hydrogen equivalent (X) of component (C) can be calculated using the following formula, where _X1 , _X2 , _X3 , _... , Xi represents the active hydrogen equivalent of each epoxy curing agent and _W1 , _W2 , _W3 , ..., _Wi represents the mass ratio of each epoxy curing agent in component (C):
1/X=W ₁ /X ₁ +W ₂ /X ₂ +W ₃ /X ₃ +...W _i /X _i .

In composition (2), the active hydrogen equivalent of component (C) is 50 g/eq to 90 g/eq, preferably 53 g/eq to 88 g/eq, more preferably 55 g/eq to 87 g/eq, more preferably 58 g/eq to 85 g/eq, more preferably 60 g/eq to 82 g/eq, more preferably 62 g/eq to 81 g/eq, more preferably 62 g/eq to 80 g/eq, even more preferably 62 g/eq to 78 g/eq, and particularly preferably 65 g/eq to 75 g/eq. This configuration has the advantage that the resulting cured product has an excellent balance between heat resistance and toughness.

Commercially available polyamidoamines, which are the component (c2), include Sunmide DT-200, Sunmide X-2000, Sunmide 330, Sunmide 336, Ancamide 910, Ancamide 350A, Versamid 140, and Versamid 115. Of these, Sunmide DT-200, Sunmide X-2000, Sunmide 330, Sunmide 336, Ancamide 350A, and Versamid 140 are preferred, with Sunmide DT-200, Sunmide X-2000, Sunmide 330, and Sunmide 336 being more preferred, and Sunmide DT-200 being particularly preferred.

In composition (2), the content of component (c2) is 25% by mass to 100% by mass, preferably 30% by mass to 100% by mass, more preferably 40% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. This configuration has the advantage that the resulting cured product has an excellent balance between toughness and heat resistance. The content of component (c2) may be 100% by mass out of 100% by mass of component (C); in other words, component (C) may consist solely of component (c2).

In composition (2), the content of component (c2) in a total amount of 100% by mass of the composition is preferably 3.5% by mass to 30.0% by mass, more preferably 3.6% by mass to 27.0% by mass, even more preferably 3.7% by mass to 24.0% by mass, even more preferably 3.8% by mass to 22.0% by mass, even more preferably 3.9% by mass to 20.0% by mass, even more preferably 4.0% by mass to 18.0% by mass, and particularly preferably 8.0% by mass to 15.0% by mass. This configuration has the advantage that the resulting cured product has excellent toughness.

A curable resin composition according to one embodiment of the present invention may be both composition (1) and composition (2); in other words, it may satisfy both (1) and (2). That is, a curable resin composition according to one embodiment of the present invention may have a (C) component that includes the (c1) and (c2) components, an active hydrogen equivalent of the (C) component being 50 g/eq to 90 g/eq, and a content of the (c1) component being 25% to 75% by mass and a content of the (c2) component being 25% to 75% by mass, based on 100% by mass of the (C) component. The preferred embodiment of composition (1) described above is also a preferred embodiment of a curable resin composition that satisfies both (1) and (2). The preferred embodiment of composition (2) described above is also a preferred embodiment of a curable resin composition that satisfies both (1) and (2).

In composition (1) and/or composition (2), component (C) preferably further contains component (c3) below.

Component (c3): Amine-terminated butadiene nitrile rubber.

In this specification, amine-terminated butadiene nitrile rubber is also referred to as component (c3). When the present composition further contains, as component (C), amine-terminated butadiene nitrile rubber (component (c3)) in addition to the components (c1) and/or (c2), the composition has the advantage of being able to obtain a cured product with an especially excellent balance between heat resistance and toughness when cured at low temperatures.

In composition (1) of one embodiment of the present invention, component (C) includes components (c1) and (c3), and the content of component (c1) may be 25% by mass or more and less than 100% by mass relative to 100% by mass of component (C). In composition (2) of one embodiment of the present invention, component (C) includes components (c2) and (c3), and the content of component (c2) may be 25% by mass or more and less than 100% by mass relative to 100% by mass of component (C).

The amine-terminated butadiene nitrile rubber (component (c3)) preferably has an average of 1 to 4 (more preferably 1.5 to 3) amino and/or imino groups per molecule. The amine-terminated butadiene nitrile rubber (component (c3)) is a polybutadiene/acrylonitrile copolymer with an acrylonitrile monomer content in the main chain of preferably 5% to 40% by mass, more preferably 10% to 35% by mass, and even more preferably 15% to 30% by mass. Commercially available amine-terminated butadiene nitrile rubbers include Huntsman's Hypro 1300X16 ATBN.

With respect to 100% by mass of component (C), the content of component (c3) is preferably 1% by mass to 75% by mass, more preferably 5% by mass to 70% by mass, even more preferably 10% by mass to 70% by mass, even more preferably 15% by mass to 65% by mass, and particularly preferably 20% by mass to 60% by mass. This configuration has the advantage that the resulting cured product has an excellent balance between toughness and heat resistance.

With respect to a total amount (100% by mass) of the composition, the content of component (c3) is preferably 0.3% by mass to 30.0% by mass, more preferably 1.0% by mass to 27.0% by mass, even more preferably 2.0% by mass to 22.0% by mass, even more preferably 4.0% by mass to 18.0% by mass, and particularly preferably 8.0% by mass to 15.0% by mass. This configuration has the advantage that the resulting cured product has excellent toughness.

In a curable resin composition according to one embodiment of the present invention, the (C) component comprises the (c1), (c2), and (c3) components, the active hydrogen equivalent of the (C) component is 50 g/eq to 90 g/eq, and the content of the (c1) component is 25% by mass or more but less than 75% by mass, and the content of the (c2) component is 25% by mass or more but less than 75% by mass, based on 100% by mass of the (C) component.

Epoxy curing agents that are active at low temperatures also include aromatic amine and mercaptan curing agents. The present composition may contain an aromatic amine and/or mercaptan curing agent as component (C).

The composition may further contain, as component (C), an epoxy curing agent that exhibits activity at high temperatures (e.g., acid anhydride curing agents; boron trifluoride-amine complexes; dicyandiamide; organic acid hydrazides; etc.).

In this composition, the content of component (C) per 100 parts by mass of component (A) is preferably 5 to 100 parts by mass, more preferably 10 to 90 parts by mass, more preferably 15 to 80 parts by mass, even more preferably 18 to 70 parts by mass, and particularly preferably 20 to 60 parts by mass. This configuration has the advantage that the resulting cured product has an excellent balance between toughness and heat resistance.

2-4. Component (D): Epoxy-based reactive diluent
The composition further contains an epoxy-based reactive diluent as component (D). In this specification, the term "epoxy-based reactive diluent" refers to a compound having at least one epoxy group per molecule and having a viscosity of 500 mPa·s or less at 25°C. By including component (D), i.e., the epoxy-based reactive diluent, the composition has the advantage that the cured product obtained by curing the composition at low temperatures has superior toughness.

Examples of epoxy-based reactive diluents include polyalkylene glycol diglycidyl ethers, glycol diglycidyl ethers, diglycidyl esters of aliphatic polybasic acids, glycidyl ethers of dihydric or higher polyhydric aliphatic alcohols, and monoepoxides.

More specifically, examples of the polyalkylene glycol diglycidyl ether include polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and dipropylene glycol diglycidyl ether.

More specific examples of the glycol diglycidyl ether include neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, ethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether.

More specifically, examples of the diglycidyl esters of aliphatic polybasic acids include dimer acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, and maleic acid diglycidyl ester.

More specifically, examples of the glycidyl ethers of dihydric or higher polyhydric aliphatic alcohols include trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, castor oil-modified polyglycidyl ether, propoxylated glycerin triglycidyl ether, and sorbitol polyglycidyl ether.

Examples of monoepoxides include aliphatic glycidyl ethers such as butyl glycidyl ether; aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether (o-cresyl glycidyl ether); ethers containing a glycidyl group and an alkyl group having 8 to 10 carbon atoms, such as 2-ethylhexyl glycidyl ether; ethers containing a glycidyl group and a phenyl group having 6 to 12 carbon atoms, which may be substituted with an alkyl group having 2 to 8 carbon atoms, such as p-tert-butylphenyl glycidyl ether; ethers containing a glycidyl group and an alkyl group having 12 to 14 carbon atoms, such as dodecyl glycidyl ether (alkyl C12-C14 glycidyl ether); aliphatic glycidyl esters such as glycidyl (meth)acrylate and glycidyl maleate; glycidyl esters of aliphatic carboxylic acids having 8 to 12 carbon atoms, such as versatic acid glycidyl ester, neodecanoic acid glycidyl ester, and lauric acid glycidyl ester; p-t-butylbenzoic acid glycidyl ester, etc.

The present inventors have independently discovered the novel finding that, when a composition contains an epoxy-based reactive diluent having two epoxy groups per molecule as component (D), the composition can surprisingly provide a cured product having an excellent balance of heat resistance and toughness when cured at low temperatures. Component (D) in this composition preferably contains an epoxy-based reactive diluent having two epoxy groups per molecule. Examples of epoxy-based reactive diluents having two epoxy groups per molecule include the above-mentioned polyalkylene glycol diglycidyl ether, glycol diglycidyl ether, and diglycidyl ester of an aliphatic polybasic acid.

In this composition, component (D) preferably contains, out of 100 mass% of component (D), 70 mass% or more of an epoxy-based reactive diluent having two epoxy groups per molecule, more preferably 80 mass% or more, even more preferably 90 mass% or more, and particularly preferably 90 mass% to 100 mass%. Component (D) may contain, out of 100 mass% of component (D), 100 mass% of an epoxy-based reactive diluent having two epoxy groups per molecule; in other words, component (D) may be composed solely of an epoxy-based reactive diluent having two epoxy groups per molecule.

Furthermore, the present inventors have independently discovered the novel finding that when composition (1) contains an epoxy-based reactive diluent having one epoxy group per molecule as component (D), composition (1) can surprisingly provide a cured product with excellent oily surface adhesion when cured at low temperatures. The oily surface adhesion refers to adhesion to metal substrates whose surfaces are coated with oil, such as rust preventative oil or press oil. It is preferable that component (D) in this composition contains an epoxy-based reactive diluent having one epoxy group per molecule. Examples of epoxy-based reactive diluents containing one epoxy group per molecule include glycidyl esters such as versatic acid glycidyl ester and neodecanoic acid glycidyl ester; alkyl glycidyl ethers such as dodecyl glycidyl ether, which are ethers containing an alkyl group having 12 to 14 carbon atoms and a glycidyl group (alkyl C12-C14 glycidyl ether); and aromatic glycidyl ethers such as o-cresyl glycidyl ether. In view of their excellent adhesion to oily surfaces, alkyl glycidyl ethers and glycidyl esters are preferred, with glycidyl esters being particularly preferred.

Commercially available epoxy reactive diluents can also be used. Examples of commercially available epoxy reactive diluents include YED216M (manufactured by Mitsubishi Chemical, 1,6-hexanediol diglycidyl ether), Cardura® E10P (manufactured by Hexion, neodecanoic acid glycidyl ester), ERISYS® GE-10 (manufactured by Huntsman, o-cresyl glycidyl ether), 4-tert-butylphenyl glycidyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), ERISYS® GE-6 (manufactured by Huntsman, 2-ethylhexyl glycidyl ether), and ERISYS® G Examples of such diluents include E-8 (manufactured by Huntsman, alkyl C12-C14 glycidyl ether), ERISYS® GE-20 (manufactured by Huntsman, neopentyl glycol diglycidyl ether), ERISYS® GE-21 (manufactured by Huntsman, 1,4-butanediol diglycidyl ether), ERISYS® GE-24 (manufactured by Huntsman, polypropylene glycol diglycidyl ether), and PG-207 (manufactured by Nippon Steel Chemical & Material, polypropylene glycol diglycidyl ether). Note that Cardura® E10P, ERISYS® GE-10, 4-tert-butylphenyl glycidyl ether, ERISYS® GE-6, and ERISYS® GE-8 are each epoxy-based reactive diluents having one epoxy group per molecule. Additionally, YED216M, ERISYS (registered trademark) GE-20, ERISYS (registered trademark) GE-21, ERISYS (registered trademark) GE-24, and PG-207 are each epoxy-based reactive diluents containing two epoxy groups per molecule.

In this composition, the content of component (D) relative to 100 parts by mass of component (A) is preferably 1.0 to 100.0 parts by mass, more preferably 1.0 to 90.0 parts by mass, more preferably 1.0 to 80.0 parts by mass, more preferably 1.0 to 70.0 parts by mass, more preferably 1.0 to 60.0 parts by mass, more preferably 1.0 to 50.0 parts by mass, more preferably 1.0 to 40.0 parts by mass, more preferably 1.0 to 30.0 parts by mass, more preferably 1.0 to 20.0 parts by mass, more preferably 2.0 to 18.0 parts by mass, more preferably 4.0 to 16.0 parts by mass, even more preferably 6.0 to 14.0 parts by mass, and particularly preferably 8.0 to 12.0 parts by mass. In this composition, when the content of component (D) per 100 parts by mass of component (A) is within the above-mentioned range, the composition has the advantage of exhibiting excellent toughness in a cured product obtained by curing the composition at low temperatures.

<2-5. Other ingredients>
The composition may contain other components as needed. Examples of other components include, but are not limited to, curing accelerators (e.g., tertiary amines such as 2,4,6-tris(dimethylaminomethyl)phenol), reinforcing agents, inorganic fillers (e.g., silicic acid and/or silicates), calcium oxide, radical-curing resins, photopolymerization initiators, blowing agents (e.g., azo-type chemical blowing agents and/or thermally expandable microballoons), colorants (e.g., pigments and/or dyes), extender pigments, UV absorbers, antioxidants, stabilizers (antigelling agents), plasticizers, leveling agents, defoamers, silane coupling agents (e.g., 3-glycidoxypropyltrimethoxysilane), antistatic agents, flame retardants, lubricants, viscosity reducers, shrinkage reducing agents, organic fillers, thermoplastic resins, desiccants, and dispersants. Examples of inorganic fillers include untreated fumed silica and fumed silica surface-treated with polydimethylsiloxane or the like. These other components may be used alone or in combination of two or more, depending on the desired effect.

Silicate and/or silicate can be added as the inorganic filler. Specific examples include dry silica, wet silica, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, talc, etc.

The dry silica is also called fumed silica, and includes hydrophilic fumed silica with no surface treatment, and hydrophobic fumed silica produced by chemically treating the silanol groups of hydrophilic fumed silica with silane or siloxane. However, hydrophobic fumed silica is preferred in terms of dispersibility in component (A).

Other inorganic fillers include reinforcing fillers such as dolomite and carbon black; colloidal calcium carbonate, heavy calcium carbonate, magnesium carbonate, titanium oxide, ferric oxide, fine aluminum powder, zinc oxide, and activated zinc oxide. Calcium carbonate is particularly preferred from the standpoint of adhesive strength. The content of calcium carbonate is preferably 5 to 300 parts by mass, more preferably 10 to 250 parts by mass, even more preferably 20 to 200 parts by mass, and particularly preferably 30 to 150 parts by mass, per 100 parts by mass of component (A).

It is preferable that the inorganic filler be surface-treated with a surface treatment agent. Surface treatment improves the dispersibility of the inorganic filler in the composition, thereby improving various physical properties of the resulting cured product. Surface-treated heavy calcium carbonate is particularly preferable from the standpoint of adhesive strength.

The amount of inorganic filler used is preferably 1 to 300 parts by mass, more preferably 2 to 250 parts by mass, even more preferably 5 to 200 parts by mass, and particularly preferably 7 to 150 parts by mass, per 100 parts by mass of component (A).

Inorganic fillers may be used alone or in combination of two or more types.

<2-6. Other>
The composition may be of a one-component type, a two-component type, or a multi-component type having three or more components.

When the present composition is a two-component or multi-component curable resin composition, for example, the following embodiments are preferred:
A two-component or multi-component curable resin composition for low-temperature curing, comprising a first component and a second component,
The first component includes the following components (A) and (D):
Component (A): epoxy resin;
Component (D): an epoxy-based reactive diluent;
The second component includes the following component (C):
Component (C): epoxy curing agent;
The curable resin composition further contains the following component (B):
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
A two-component or multi-component curable resin composition for low-temperature curing that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

The above-mentioned two-component or multi-component curable resin compositions for low-temperature curing also have the advantage that, when cured at low temperatures, they can provide a cured product that has an excellent balance of heat resistance and toughness.

With regard to specific aspects (e.g., aspects of each component) of the above-mentioned two-component or multi-component curable resin composition for low-temperature curing, the above descriptions (e.g., descriptions of each component) are incorporated as appropriate. Preferred aspects in the above descriptions (e.g., descriptions of each component) are also preferred aspects of the above-mentioned two-component or multi-component curable resin composition for low-temperature curing.

<2-7. Method for producing curable resin composition>
[0043] The method for producing the curable resin composition is not particularly limited. When the composition is a one-component curable resin composition, the curable resin composition can be produced, for example, by mixing the above-mentioned components (A), (B), (C), and (D), and other components as necessary, using a known mixing device (e.g., a planetary mixer).

When polymer particles (b1) are used as component (B), the polymer particles (b1) are preferably dispersed in the composition as primary particles. From the viewpoint of efficiently obtaining a composition in which the polymer particles (b1) are dispersed as primary particles, it is preferable to prepare a polymer particle-containing composition in which the polymer particles (b1) are dispersed as primary particles in component (A) or component (D) before mixing with components (C) and (D). A composition in which the polymer particles (b1) are dispersed as primary particles can be produced by mixing the prepared polymer particle-containing composition with component (C), and, as necessary, with component (A), component (D), and other components, using a known mixing device.

Various methods can be used to obtain the polymer particle-containing composition. Examples of such methods include (i) a method in which polymer particles obtained in an aqueous latex state are contacted with component (A) or (D) and then unnecessary components such as water are removed, and (ii) a method in which the polymer particles are first extracted into an organic solvent, the extracted polymer particles are mixed with component (A) or (D), and then the organic solvent is removed. The method described in WO 2005/028546 is preferably used to obtain the polymer particle-containing composition. The polymer particle-containing composition is preferably prepared by, in order, (i) a first step of mixing an aqueous latex containing polymer particles (more specifically, a reaction mixture obtained after producing polymer particles by emulsion polymerization) with an organic solvent having a solubility in water of 5% by mass or more and 40% by mass or less at 20°C, and then mixing the resulting mixture with excess water to aggregate the polymer particles; (ii) a second step of separating and recovering the aggregated polymer particles from the liquid phase, and then mixing the resulting polymer particle aggregates again with an organic solvent to obtain an organic solvent dispersion of polymer particles; and (iii) a third step of mixing the organic solvent dispersion with component (A) or (D), and then distilling off the organic solvent from the resulting mixture.

Components (A) and (D) are preferably liquid at 23°C, as this facilitates the third step. "Liquid at 23°C" means that the softening point is 23°C or lower, and the component exhibits fluidity at 23°C.

The polymer particle-containing composition can also be obtained using powdered polymer particles. For example, powdered polymer particles can be obtained by using polymer particles obtained in an aqueous latex state, coagulating the polymer particles by a method such as salting out, and then drying the resulting aggregates. The resulting powdered polymer particles can be redispersed in component (A) or (D) using a disperser with high mechanical shear force, such as a triple paint roll, roll mill, or kneader. Applying mechanical shear force at a high temperature enables efficient redispersion of component (B). The temperature for redispersing component (B) in component (A) or (D) is preferably 50 to 200°C, more preferably 70 to 170°C, even more preferably 80 to 150°C, and particularly preferably 90 to 120°C.

When the composition is a two-component or multi-component curable resin composition containing a first component and a second component, the first component containing component (B) can be produced, for example, by mixing the above-mentioned components (A), (B), and (D), as well as other components as necessary, using a known mixing device (e.g., a planetary mixer, etc.). When polymer particles (b1) are used as component (B), the first component containing components (A), (B), and (D) corresponds to the above-mentioned polymer particle-containing composition. The second component can also be produced by mixing component (C), as well as, as necessary, component (B) and other components, using a known mixing device (e.g., a planetary mixer, etc.). The first and second components produced in this manner are preferably mixed and used immediately before use (e.g., immediately before bonding the adherends or immediately before curing the curable resin composition).

When the composition is a two-component or multi-component curable resin composition containing a first component and a second component, as another example, the first component not containing the component (B) can be produced by mixing the above-mentioned components (A) and (D), and other components as needed, using a known mixing device (e.g., a planetary mixer, etc.). Alternatively, the second component containing the component (B) can be produced by mixing the components (B), (C), and other components as needed, using a known mixing device (e.g., a planetary mixer, etc.). The first and second components produced in this manner are preferably mixed and used immediately before use (e.g., immediately before the bonding operation of the adherends or immediately before the curing of the curable resin composition).

[3. Cured product]
One embodiment of the present invention also provides a cured product obtained by curing the curable resin composition according to one embodiment of the present invention described in the above section [2. Curable Resin Composition]. In other words, the cured product obtained by curing the curable resin composition according to one embodiment of the present invention can also be said to be the cured product according to one embodiment of the present invention. When the composition is used as an adhesive (for example, a vehicle adhesive (structural adhesive) for vehicles and aircraft, an adhesive for secondary batteries such as EV battery cells, a structural adhesive for wind power generation, etc.), the cured product obtained by curing the composition (adhesive) can also be said to be an adhesive layer.

The cured product according to one embodiment of the present invention has the advantage of having an excellent balance between heat resistance and toughness.

When the composition is a one-component type, a cured product can be obtained by curing the curable resin composition at the curing temperature described below. When component (B) contains polymer particles (b1) and the polymer particles are dispersed in the curable resin composition in the form of primary particles, the polymer particles are also considered to be dispersed in the resulting cured product in the form of primary particles.

When the composition is a two-component or multi-component type containing a first component and a second component, the first and second components can be mixed uniformly using a static mixer or the like, and the resulting mixture (composition) can be cured at the curing temperature described below to obtain a cured product. When component (B) contains polymer particles (b1), and the polymer particles are dispersed in the first component and/or second component in the form of primary particles, the polymer particles are also considered to be dispersed in the resulting cured product in the form of primary particles.

A cured product according to another embodiment of the present invention is a cured product obtained by curing a curable resin composition including the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A degree of cure by differential scanning calorimetry (DSC) of 50% to 95%;
The curable resin composition satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
The active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq.

The cured product according to another embodiment of the present invention also has the advantage of having an excellent balance between heat resistance and toughness.

The degree of cure of a cured product according to another embodiment of the present invention, as measured by differential scanning calorimetry (DSC), is 50% to 95%. Generally, the degree of cure of a cured product obtained by curing a curable resin composition at high temperatures, as measured by DSC, is greater than 95%, and can be 96% to 100%. On the other hand, the degree of cure of a cured product obtained by curing a curable resin composition at low temperatures, as measured by DSC, can be 95% or less. In other words, the fact that the degree of cure of a cured product according to another embodiment of the present invention, as measured by DSC, is 95% or less, indicates that the cured product according to another embodiment of the present invention was obtained by low-temperature curing.

The higher the degree of cure of the cured product measured by DSC, the more advantageously the cured product will have superior heat resistance. Therefore, in another embodiment of the present invention, the degree of cure of the cured product measured by DSC is preferably 60% to 95%, more preferably 70% to 95%, even more preferably 75% to 95%, and particularly preferably 80% to 95%. The method for measuring the degree of cure of the cured product by DSC will be explained in detail in the Examples below.

The glass transition temperature (Tg) of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the glass transition temperature (Tg), the more excellent the heat resistance of the cured product. The glass transition temperature (Tg) is preferably 80°C or higher, more preferably 82°C or higher, even more preferably 85°C or higher, and particularly preferably 90°C or higher. The upper limit of the glass transition temperature (Tg) is not particularly limited, but is, for example, 150°C or lower. The method for measuring the glass transition temperature (Tg) of the cured product will be explained in detail in the Examples below.

The storage modulus at 70°C of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. It is intended that the higher the storage modulus value, the better the heat resistance of the cured product. The storage modulus is preferably 0.14 GPa or more, more preferably 0.17 GPa or more, even more preferably 0.20 GPa or more, and particularly preferably 0.50 GPa or more. The upper limit of the storage modulus is not particularly limited, but is, for example, 5.00 GPa or less. A method for measuring the storage modulus at 70°C of the cured product will be explained in detail in the Examples below.

The fracture toughness (K1c) of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the fracture toughness (K1c) value, the more excellent the toughness of the cured product. The fracture toughness (K1c) is preferably 1.10 MPa·m ^1/2 or more, more preferably 1.40 MPa·m ^1/2 or more, even more preferably 1.70 MPa·m ^1/2 or more, and particularly preferably 2.00 MPa·m ^1/2 or more. The upper limit of the storage modulus is not particularly limited, but is, for example, 5.00 MPa·m ^1/2 or less. The method for measuring the fracture toughness (K1c) of the cured product will be described in detail in the Examples below.

The fracture toughness (G1c) of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the fracture toughness (G1c) value, the more excellent the toughness of the cured product. The fracture toughness (G1c) is preferably 0.30 kJ/ ^m² or more, more preferably 0.50 kJ/ ^m² or more, even more preferably 0.80 kJ/ ^m² or more, and particularly preferably 1.50 kJ/ ^m² or more. The upper limit of the storage modulus is not particularly limited, but is, for example, 10.00 kJ/ ^m² or less. The method for measuring the fracture toughness (G1c) of the cured product will be described in detail in the Examples below.

The shear bond strength of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the shear bond strength value, the more excellent the toughness of the cured product. The shear bond strength is preferably 18 MPa or more, more preferably 19 MPa or more, even more preferably 20 MPa or more, and particularly preferably 21 MPa or more. The upper limit of the shear bond strength is not particularly limited, but is, for example, 40 MPa or less. The method for measuring the shear bond strength of the cured product will be explained in detail in the examples below.

The T-peel adhesive strength of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the T-peel adhesive strength, the more excellent the toughness of the cured product. The T-peel adhesive strength is preferably 100 N/25 mm or more, more preferably 105 N/25 mm or more, even more preferably 110 N/25 mm or more, and particularly preferably 115 N/25 mm or more. The upper limit of the T-peel adhesive strength is not particularly limited, but is, for example, 400 N/25 mm or less. The method for measuring the T-peel adhesive strength of the cured product will be explained in detail in the Examples below.

The impact peel strength of the cured product according to one embodiment of the present invention and the cured product according to another embodiment of the present invention is not particularly limited. The higher the impact peel strength value, the more excellent the toughness of the cured product. The impact peel strength is preferably 17 kN/m or more, more preferably 18 kN/m or more, even more preferably 19 kN/m or more, and particularly preferably 20 kN/m or more. The upper limit of the storage modulus is not particularly limited, but is, for example, 100 kN/m or less. The method for measuring the impact peel strength of the cured product will be explained in detail in the examples below.

(Application method)
The composition can be applied to a substrate by any method. The composition may be applied in the form of a low-temperature composition at about room temperature without heating, or may be applied in the form of a high-temperature composition after heating.

There are no particular limitations on the method for applying the composition; for example, it can be applied by extruding it onto a substrate in the form of a bead, monofilament, or swirl using a coating robot. The viscosity of the composition at the application temperature is not particularly limited. For example, the viscosity of the composition at the application temperature is preferably approximately 150 Pa·s to 600 Pa·s for the extrusion bead method, approximately 100 Pa·s for the swirl application method, and approximately 20 Pa·s to 400 Pa·s for the high-volume application method using a high-speed flow device.

This section explains the case where the composition is a two-component or multi-component curable resin composition containing a first component and a second component. In this case, the first and second components of the curable resin composition can be applied (applied) after being discharged from a constant-volume dispenser and then uniformly mixed in a static mixer connected to the tip of the device. It is also possible to fill each cartridge of a double-cartridge caulking gun, which has a static mixer connected to the tip, with the first and second components of the curable resin composition and manually extrude them for application.

The method for producing the cured product, in other words, the method for curing the composition, is not particularly limited. For example, the composition can be cured by heating it to a certain temperature (curing temperature) and maintaining it at that temperature for a certain period of time (curing time), thereby obtaining a cured product.

In one embodiment of the present invention, the curable resin composition is a composition for use in applications where it cures at low temperatures, and is a curable resin composition for low-temperature curing. As used herein, "low-temperature curing" or "curing at low temperatures" refers to curing the curable resin composition at temperatures above 0°C and below 120°C. In other words, when a curable resin composition is cured at a high temperature of 120°C or higher, this is not considered "low-temperature curing" in this specification, but rather "high-temperature curing."

A method for producing a cured product according to one embodiment of the present invention includes a step of curing the curable resin composition according to one embodiment of the present invention described in the above section [2. Curable Resin Composition] at a low temperature (e.g., at least 0°C and less than 120°C). One embodiment of the present invention provides use of a curable resin composition, including a step of curing the curable resin composition according to one embodiment of the present invention described in the above section [2. Curable Resin Composition] at a low temperature (e.g., at least 0°C and less than 120°C). Because the curable resin composition according to one embodiment of the present invention has the above-described configuration, it is possible to obtain a cured product that has an excellent balance between heat resistance and toughness, even when cured at a low temperature (e.g., at least 0°C and less than 120°C).

The curing temperature of the curable resin composition is preferably 10°C to 119°C, more preferably 10°C to 115°C, even more preferably 20°C to 100°C, and particularly preferably 20°C to 90°C.

The curing time is not particularly limited as long as the composition can be cured (for example, as long as the degree of cure of the resulting cured product measured by DSC is 50% or more). The curing time is preferably 0.1 to 100 hours, more preferably 0.2 to 90 hours, even more preferably 0.3 to 80 hours, and particularly preferably 0.5 to 70 hours.

[4. Use]
The curable resin composition is preferably used in applications such as adhesives (for example, vehicle adhesives (structural adhesives) for vehicles and aircraft, adhesives for secondary batteries such as EV battery cells, and structural adhesives for wind power generation), materials for impregnating glass fibers and/or carbon fibers to obtain fiber-reinforced composite materials (hereinafter, may be referred to as "impregnation materials"), materials for printed wiring boards, solder resists, interlayer insulating films, build-up materials, adhesives for FPCs, electrically insulating materials such as sealants for electronic components such as semiconductors and LEDs, die-bonding materials, underfills, mounting materials for semiconductors (for example, ACF, ACP, NCF, NCP), sealants for display devices (for example, liquid crystal panels and OLED displays), sealants for lighting devices (for example, OLED lighting), concrete repair materials, and coating materials (for example, concrete coating materials).

In other words, one embodiment of the present invention provides the use of the curable resin composition according to one embodiment of the present invention described in the above section [2. Curable Resin Composition] as one or more materials selected from the group consisting of adhesives, impregnation materials, materials for printed wiring boards, solder resists, interlayer insulating films, build-up materials, adhesives for FPCs, electrical insulating materials, die-bonding materials, underfills, semiconductor mounting materials, sealants for display devices, sealants for lighting devices, concrete repair materials, and coating materials.

When the curable resin composition is used as an impregnation material (a material impregnated into fibers to produce a composite material), it can be used in a wide range of molding methods without any particular restrictions. Specifically, it can be molded using known molding methods such as hand layup, spray-up, pultrusion, filament winding, matched die, prepreg, centrifugal molding, liquid molding, hot press, casting, injection molding, continuous lamination, resin transfer molding (RTM), vacuum bag molding, and cold press.

The curable resin composition is suitable as a raw material for composite materials with glass fiber or carbon fiber, BMC (bulk molding compound) and SMC (sheet molding compound). There are no particular limitations on the areas in which it can be used, but specific applications include artificial marble applications such as kitchen counters, washbasins, bathtubs, and wall materials; resin concrete, tanks, pressure vessels, industrial pipes, factory piping, joints, pipes, corrugated sheets, helmets, poles, wind power generation blades, piping for oil field pumping systems such as sucker rods and pumps; electrical parts, automotive parts, railway vehicle parts, ship parts, aircraft parts, industrial machinery parts, construction materials, structural components for furniture and musical instruments; and sheet materials such as decorative panels and decorative sheets.

One embodiment of the present invention may have the following configuration.

[X1] Contains the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A curable resin composition for low temperature curing that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

[X2] A two-component or multi-component curable resin composition for low-temperature curing, comprising a first component and a second component,
The first component includes the following components (A) and (D):
Component (A): epoxy resin;
Component (D): an epoxy-based reactive diluent;
The second component includes the following component (C):
Component (C): epoxy curing agent;
The curable resin composition further contains the following component (B):
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
A two-component or multi-component curable resin composition for low-temperature curing that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C).

[X3] The curable resin composition according to [X1] or [X2], wherein the component (C) further contains the following component (c3):
Component (c3): Amine-terminated butadiene nitrile rubber.

[X4] The curable resin composition according to any one of [X1] to [X3], wherein the component (A) includes the following component (a1) and/or component (a2):
Component (a1): bisphenol A epoxy resin;
Component (a2): bisphenol F type epoxy resin.

[X5] The curable resin composition described in [X4], wherein the total content of the (a1) component and the (a2) component is 5% by mass to 100% by mass, relative to 100% by mass of the (A) component.

[X6] A curable resin composition described in any one of [X1] to [X5], wherein the core layer of component (b1) contains one or more rubbers selected from the group consisting of diene rubbers, (meth)acrylate rubbers, and organosiloxane rubbers.

[X7] A curable resin composition described in any one of [X1] to [X6], wherein the core layer of component (b1) is butadiene rubber and/or butadiene-styrene rubber.

[X8] A curable resin composition described in any one of [X1] to [X7], wherein the shell layer of component (b1) contains one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units.

[X9] A curable resin composition according to any one of [X1] to [X8], wherein the content of the (B) component is 1 to 200 parts by mass per 100 parts by mass of the (A) component.

[X10] A curable resin composition according to any one of [X1] to [X9], wherein the component (c1) includes one or more selected from the group consisting of isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, piperazine, and menthenediamine.

[X11] A curable resin composition described in any one of [X1] to [X10], wherein the component (c1) includes one or more selected from the group consisting of isophoronediamine, 4,4'-methylenebis(cyclohexylamine), and 4,4'-methylenebis(2-methylcyclohexylamine).

[X12] A curable resin composition according to any one of [X1] to [X11], wherein the content of the (C) component is 5 to 100 parts by mass per 100 parts by mass of the (A) component.

[X13] A curable resin composition according to any one of [X1] to [X12], wherein the content of component (c1) is 3.5% by mass to 30.0% by mass, relative to 100% by mass of the total amount of the curable resin composition.

[X14] A curable resin composition according to any one of [X1] to [X13], wherein the component (D) includes an epoxy-based reactive diluent having two epoxy groups per molecule.

[X15] A curable resin composition according to any one of [X1] to [X14], wherein the content of the (D) component is 1.0 to 100.0 parts by mass per 100 parts by mass of the (A) component.

[X16] A curable resin composition according to any one of [X1] to [X15], further containing 5 to 300 parts by mass of calcium carbonate per 100 parts by mass of component (A).

[X17] Use of the curable resin composition described in any one of [X1] to [X16] as one or more materials selected from the group consisting of adhesives, impregnation materials, and coating materials.

[X18] Use of a curable resin composition, comprising a step of curing the curable resin composition described in any one of [X1] to [X16] at low temperature.

[X19] A method for producing a cured product, comprising a step of curing the curable resin composition described in any one of [X1] to [X16] at low temperature.

[X20] An adhesive comprising the curable resin composition described in any one of [X1] to [X16].

[X21] An impregnated material containing the curable resin composition described in any one of [X1] to [X16].

[X22] A coating material comprising the curable resin composition described in any one of [X1] to [X16].

[X23] A cured product obtained by curing the curable resin composition described in any one of [X1] to [X16].

[X24] A cured product obtained by curing a curable resin composition containing the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A degree of cure by differential scanning calorimetry (DSC) of 50% to 95%;
The curable resin composition has a cured product that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
The active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq.

[X25] A cured product obtained by curing a curable resin composition containing the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A cured product obtained by curing a curable resin composition that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
A degree of cure by differential scanning calorimetry (DSC) of 50% to 95%;
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The degree of cure is 50% to 95% by differential scanning calorimetry (DSC).

[X26] A cured product according to [X24] or [X25], in which the content of the (c1) component and/or the (c2) component is 25% by mass to 100% by mass relative to 100% by mass of the (C) component.

One embodiment of the present invention may have the following configuration.

[Y1] Contains the following components (A), (B), (C), and (D),
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
A curable resin composition for low-temperature curing, wherein the content of the component (c1) is 10% by mass to 100% by mass relative to 100% by mass of the component (C).

[Y2] A two-component or multi-component curable resin composition for low-temperature curing, comprising a first component and a second component,
The first component includes the following components (A) and (D):
Component (A): epoxy resin;
Component (D): an epoxy-based reactive diluent;
The second component includes the following component (C):
Component (C): epoxy curing agent;
The curable resin composition further contains the following component (B):
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
A two-component or multi-component curable resin composition for low-temperature curing, wherein the content of the component (c1) is 10 mass % to 100 mass % relative to 100 mass % of the component (C).

[Y3] The curable resin composition according to [Y1] or [Y2], wherein the component (A) includes the following component (a1) and/or component (a2):
Component (a1): bisphenol A epoxy resin;
Component (a2): bisphenol F type epoxy resin.

[Y4] The curable resin composition described in [Y3], in which the total content of the (a1) component and the (a2) component is 5% by mass to 100% by mass, relative to 100% by mass of the (A) component.

[Y5] A curable resin composition described in any one of [Y1] to [Y4], wherein the core layer of component (b1) contains one or more rubbers selected from the group consisting of diene rubbers, (meth)acrylate rubbers, and organosiloxane rubbers.

[Y6] A curable resin composition according to any one of [Y1] to [Y5], wherein the core layer of component (b1) is butadiene rubber and/or butadiene-styrene rubber.

[Y7] A curable resin composition described in any one of [Y1] to [Y6], wherein the shell layer of component (b1) contains one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units.

[Y8] A curable resin composition according to any one of [Y1] to [Y7], wherein the content of the (B) component is 1 to 200 parts by mass per 100 parts by mass of the (A) component.

[Y9] A curable resin composition according to any one of [Y1] to [Y8], wherein the component (c1) includes one or more selected from the group consisting of isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, piperazine, and menthenediamine.

[Y10] A curable resin composition according to any one of [Y1] to [Y9], wherein the content of the (C) component is 5 to 100 parts by mass per 100 parts by mass of the (A) component.

[Y11] A curable resin composition according to any one of [Y1] to [Y10], wherein the component (D) includes an epoxy-based reactive diluent having two epoxy groups per molecule.

[Y12] A curable resin composition according to any one of [Y1] to [Y11], wherein the content of the (D) component is 1.0 to 100.0 parts by mass per 100 parts by mass of the (A) component.

[Y13] Use of the curable resin composition described in any one of [Y1] to [Y12] as one or more materials selected from the group consisting of adhesives, impregnation materials, and coating materials.

[Y14] Use of a curable resin composition, comprising a step of curing the curable resin composition described in any one of [Y1] to [Y12] at low temperature.

[Y15] A method for producing a cured product, comprising a step of curing the curable resin composition described in any one of [Y1] to [Y12] at low temperature.

[Y16] A cured product obtained by curing a curable resin composition containing the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
A cured product having a degree of cure of 50% to 95% by differential scanning calorimetry (DSC).

[Y17] The cured product described in [Y16], in which the content of the (c1) component is 10% by mass to 100% by mass based on 100% by mass of the (C) component.

Below, one embodiment of the present invention will be explained in more detail using examples and comparative examples, but the present invention is not limited to these. One embodiment of the present invention can be implemented by appropriately modifying the examples below, as long as it conforms to the intent described above and below. All embodiments implemented by appropriately modifying the examples below are encompassed within the technical scope of the present invention. In the examples, comparative examples, and tables below, "parts" and "%" mean parts by mass and % by mass, respectively.

〔material〕
First, the substances used in the examples and comparative examples are shown below.

<Component (A)>
A-(1): Difunctional bisphenol A epoxy resin (difunctional bisphenol A epoxy resin that is liquid at room temperature) (manufactured by Mitsubishi Chemical Corporation, "jER828", epoxy equivalent: 189 g/eq)
<(B) component>
[Component (b1) (polymer particles)]
The component (b1) (polymer particles) prepared by the following method was used. As described below, dispersions (M-(1) to M-(3)) in which the prepared component (B) (component (b1) (polymer particles)) was dispersed in the component (A) (A-(1)) were prepared and used in the examples.

1. Formation of Core Layer Production Example 1-1: Preparation of Polybutadiene Rubber Latex (R-1) Into a 100 L pressure-resistant polymerization reactor, 200 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.25 parts by mass of potassium dihydrogen phosphate, 0.002 parts by mass of disodium ethylenediaminetetraacetate (EDTA), 0.001 parts by mass of ferrous sulfate heptahydrate (FE), and 1.5 parts by mass of sodium dodecylbenzenesulfonate (SDS) as an emulsifier were charged. Next, the gas inside the pressure-resistant polymerization reactor was replaced with nitrogen while stirring the charged raw materials, thereby thoroughly removing oxygen from inside the pressure-resistant polymerization reactor. Thereafter, 100 parts by mass of butadiene (BD) was charged into the pressure-resistant polymerization reactor, and the temperature inside the pressure-resistant polymerization reactor was raised to 45 ° C. Next, 0.015 parts by mass of paramenthane hydroperoxide (PHP) was charged into the pressure-resistant polymerization reactor, followed by 0.04 parts by mass of sodium formaldehyde sulfoxylate (SFS) to initiate polymerization. Ten hours after the start of polymerization, the polymerization was terminated by devolatilization under reduced pressure to remove remaining monomers that had not been used in the polymerization. During the polymerization, PHP, EDTA, and FE were each added to the pressure-resistant polymerization reactor in desired amounts and at desired times. This polymerization procedure yielded a latex (R-1) containing a core layer (polybutadiene rubber particles) primarily composed of polybutadiene rubber. The volume average particle diameter of the polybutadiene rubber particles contained in the resulting latex was 0.10 μm.

Production Example 1-2: Preparation of Polybutadiene Rubber Latex (R-2) 21 parts by mass of the polybutadiene rubber latex (R-1) obtained in Production Example 1-1 (containing 7 parts by mass of polybutadiene rubber particles), 200 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.002 parts by mass of EDTA, and 0.001 parts by mass of FE were charged into a 100 L pressure-resistant polymerization reactor. Next, the gas inside the pressure-resistant polymerization reactor was replaced with nitrogen while stirring the charged raw materials, thereby thoroughly removing oxygen from inside the pressure-resistant polymerization reactor. Thereafter, 93 parts by mass of BD were charged into the pressure-resistant polymerization reactor, and the temperature inside the pressure-resistant polymerization reactor was raised to 45°C. Next, 0.02 parts by mass of PHP was charged into the pressure-resistant polymerization reactor, followed by 0.10 parts by mass of SFS, to initiate polymerization. Thirty hours after the start of polymerization, volatilization was carried out under reduced pressure to remove remaining monomers that were not used in the polymerization, thereby terminating the polymerization. During the polymerization, PHP, EDTA, and FE were each added to the pressure-resistant polymerization reactor in desired amounts and at desired times. This polymerization procedure yielded a latex (R-2) containing a core layer (polybutadiene rubber particles) composed primarily of polybutadiene rubber. The volume average particle diameter of the polybutadiene rubber particles contained in the obtained latex was 0.20 μm.

2. Preparation of component (B) (component (b1) (polymer particles)) (formation of shell layer)
Production Example 2-1: Preparation of Aqueous Latex (L-1) Containing Polymer Particles 271 parts by mass of the polybutadiene rubber latex (R-2) prepared in Production Example 1-2 (containing 90 parts by mass of polybutadiene rubber particles) and 51 parts by mass of deionized water were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. The gas in the glass reactor was replaced with nitrogen, and the charged raw materials were stirred at 60°C while the nitrogen replacement was being carried out. Next, 0.004 parts by mass of EDTA, 0.001 parts by mass of FE, and 0.2 parts by mass of SFS were added to the glass reactor. Thereafter, a mixture of shell layer-forming monomers (9.25 parts by mass of methyl methacrylate (MMA) and 0.75 parts by mass of GMA) and 0.14 parts by mass of CHP was continuously added to the glass reactor over 120 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was further stirred for 2 hours to complete the polymerization. Through the above operations, an aqueous latex (L-1) containing component (B) (component (b1) (polymer particles)) was obtained. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex (L-1) was 0.21 μm. The content of epoxy groups relative to the total amount of the shell layer of the polymer particles was 0.5 mmol/g.

Production Example 2-2: Preparation of Aqueous Latex (L-2) Containing Polymer Particles 262 parts by mass of the polybutadiene rubber latex (R-2) prepared in Production Example 1-2 (containing 87 parts by mass of polybutadiene rubber particles) and 57 parts by mass of deionized water were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. The gas in the glass reactor was replaced with nitrogen, and the charged raw materials were stirred at 60°C while the nitrogen replacement was being carried out. Next, 0.004 parts by mass of EDTA, 0.001 parts by mass of FE, and 0.2 parts by mass of SFS were added to the glass reactor. Thereafter, a mixture of shell layer-forming monomers (8 parts by mass of MMA, 3.5 parts by mass of butyl acrylate (BA), and 1.5 parts by mass of glycidyl methacrylate (GMA)) and 0.04 parts by mass of cumene hydroperoxide (CHP) was continuously added to the glass reactor over a period of 120 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was continuously stirred for an additional 2 hours to complete the polymerization. Through the above operations, an aqueous latex (L-2) containing component (B) (component (b1) (polymer particles)) was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex (L-2) was 0.21 μm. The epoxy group content relative to the total amount of the shell layer of the polymer particles was 0.8 mmol/g.

Production Example 2-3: Preparation of aqueous latex (L-3) containing polymer particles [0077] An aqueous latex (L-3) containing component (B) (component (b1) (polymer particles)) was obtained in the same manner as in Production Example 2-2, except that 1 part by mass of MMA, 6 parts by mass of styrene (ST), 2 parts by mass of acrylonitrile (AN), and 4 parts by mass of GMA were used instead of 8 parts by mass of MMA, 3.5 parts by mass of BA, and 1.5 parts by mass of GMA as the shell layer-forming monomers in Production Example 2-2. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex (L-3) was 0.21 μm. The epoxy group content relative to the total mass of the shell layer of the polymer particles was 2.2 mmol/g.

3. Preparation of Dispersion (M) in Which Polymer Particles Are Dispersed in Component (A) Production Example 3-1: Preparation of Dispersion (M-(1)) 132 g of methyl ethyl ketone (MEK) was introduced into a 1 L mixing tank at 25°C. Next, while stirring the MEK, 132 g of the aqueous latex (L-1) containing polymer particles obtained in Production Example 2-1 (containing 40 g of polymer particles) was added to the mixing tank. After the raw materials in the mixing tank were uniformly mixed, 200 g of water was added to the mixing tank at a feed rate of 80 g/min while stirring the raw materials in the mixing tank. After the water supply was completed, stirring was promptly stopped to obtain a slurry liquid consisting of aggregates containing polymer particles and an aqueous phase containing a small amount of organic solvent. The aggregates were floatable. Next, 360 g of the aqueous phase was discharged from a discharge port at the bottom of the mixing tank, leaving a portion of the aggregates containing the aqueous phase in the mixing tank. 90 g of MEK was added to the obtained aggregates and mixed uniformly to obtain a dispersion in which polymer particles were uniformly dispersed in MEK. 60 g of A-(1) (a bifunctional bisphenol A epoxy resin that is liquid at room temperature), which is component (A), was added to the obtained dispersion and mixed uniformly. MEK was removed from the obtained mixture using a rotary evaporator. In this way, a dispersion (M-(1)) in which component (B) (component (b1) (polymer particles)) was dispersed in component (A) was obtained.

Production Example 3-2: Preparation of Dispersion (M-(2)) A dispersion (M-(2)) in which component (B) (component (b1) (polymer particles)) was dispersed in component (A) was obtained in the same manner as in Production Example 3-1, except that (L-2) obtained in Production Example 2-2 was used instead of (L-1) as the aqueous latex containing polymer particles, and 48.9 g of epoxy resin (A-(1)) was used instead of 60 g of epoxy resin (A-(1)).

Production Example 3-3: Preparation of Dispersion (M-(3)) A dispersion (M-(3)) in which component (B) (component (b1) (polymer particles)) was dispersed in component (A) was obtained in the same manner as in Production Example 3-1, except that 132 g of (L-3) (containing 40 g of polymer particles) obtained in Production Example 2-3 was used instead of (L-1) as the aqueous latex containing polymer particles in Production Example 3-1.

[Component (b2): Blocked urethane]
b2-(1): Flexibilizer DY 965 (Huntsman, blocked urethane containing a polytetramethylene glycol structure; GPC (apparatus: Tosoh HLC-8420, column: Tosoh TSKgel Super HZ column, mobile phase: THF, column temperature: 40°C, flow rate: 0.35 ml/min, injection volume: 10 μL, detector: differential refractometer) polystyrene equivalent number average molecular weight (Mn): 11,800, molecular weight distribution (Mw/Mn): 2.1)
[Component (b3): Rubber-modified epoxy resin]
b3-(1): Hypox RA 1340 (manufactured by Huntsman, rubber-modified epoxy resin, epoxy equivalent: 325 g/eq to 375 g/eq)
[Component (b4): Urethane-modified epoxy resin]
b4-(1): EPU-73B (manufactured by ADEKA, urethane-modified epoxy resin, epoxy equivalent: 245 g/eq).

<(C) component>
[Component (c1): Alicyclic amine]
c1-(1): 4,4'-methylenebis(cyclohexylamine) (mixture of isomers) (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent: 52.6 g/eq)
c1-(2): Isophoronediamine (manufactured by BASF, active hydrogen equivalent: 42.6 g/eq)
[Component (c2): Polyamidoamine]
c2-(1): Sunmide DT-200 (manufactured by Evonik, active hydrogen equivalent: 70 g/eq)
c2-(2): Ancamide 350A (manufactured by Evonik, active hydrogen equivalent: 100 g/eq)
[Component (c3): Amine-terminated butadiene nitrile rubber]
c3-(1): Hypro 1300X16 ATBN (manufactured by Huntsman, amine-terminated butadiene-acrylonitrile copolymer, molecular weight: approximately 3800, active hydrogen equivalent: 800 g/eq to 1000 g/eq)
[Epoxy curing agents other than components (c1), (c2), and (c3)]
c-(1): 3-diethylaminopropylamine (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent: 65.1 g/eq)
c-(2): Jeffamine D-230 (manufactured by Huntsman, poly(oxypropylene) diamine, active hydrogen equivalent: 60 g/eq)
c-(3): Triethylenetetramine (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent: 24 g/eq)
<(D) component>
[Epoxy-based reactive diluent having two epoxy groups per molecule]
D-(1): YED216M (manufactured by Mitsubishi Chemical, 1,6-hexanediol diglycidyl ether, epoxy equivalent: 140 g/eq to 160 g/eq)
D-(2): PG-207 (manufactured by Nippon Steel Chemical & Material Co., Ltd., polypropylene glycol diglycidyl ether, epoxy equivalent: 315 g/eq)
D-(3): Epoite 100E (manufactured by Kyoeisha Chemical, diethylene glycol diglycidyl ether, epoxy equivalent: 151 g/eq)
D-(4): Epoite 400P (Kyoeisha Chemical Co., Ltd., polypropylene glycol diglycidyl ether, epoxy equivalent: 306 g/eq)
[Epoxy-based reactive diluent having one epoxy group per molecule]
D-(5): ERISYS (registered trademark) GE-10 (manufactured by Huntsman, o-cresyl glycidyl ether, epoxy equivalent: 182 g/eq)
D-(6): Cardula (registered trademark) E10P (manufactured by Hexion, neodecanoic acid glycidyl ester, epoxy equivalent: 245 g/eq)
D-(7): Denacol (registered trademark) EX-121 (Nagase ChemteX, 2-ethylhexyl glycidyl ether, epoxy equivalent: 187 g/eq)
<Other ingredients>
[Curing accelerator]
Ancamine K54 (manufactured by Evonik, 2,4,6-tris(dimethylaminomethyl)phenol, tertiary amine)
[Silane coupling agent]
DOWSIL Z-6040 Silane (3-glycidoxypropyltrimethoxysilane, manufactured by Dow Corning Toray Co., Ltd.)
[Heavy calcium carbonate]
Whiten SB (Shiraishi Calcium, average particle size: 1.8 μm)
[Fume silica]
CAB-O-SIL TS-720 (manufactured by CABOT, fumed silica surface-treated with polydimethylsiloxane).

[Measurement and evaluation methods]
The methods for measuring and evaluating the various physical properties measured in the examples are shown below.

[Measurement of volume average particle diameter]
The volume average particle diameter (Mv) of the polymer particles (B) dispersed in the aqueous latex was measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). The aqueous latex was diluted with deionized water and used as the measurement sample. The measurement was performed by inputting the refractive index of water and the refractive index of each polymer particle, adjusting the sample concentration so that the measurement time was 600 seconds, and the signal level was within the range of 0.6 to 0.8.

[Measurement of fracture toughness (K1c, G1c)]
Each curable resin composition in Tables 1 and 2 was poured between two fluorine-coated aluminum plates (dimensions: 25 cm × 25 cm × 0.5 cm) sandwiching a 5 mm-thick spacer, and then cured under the curing conditions (curing temperature, curing time) described in Tables 1 and 2 to obtain a 5 mm-thick cured product in the form of a plate. The cured product was cut into a size of 2.5 inches long, 0.5 inches wide, and 5 mm thick to prepare a test specimen. A V-notch was made in each test specimen, and a crack was created from the tip of the V-notch to the center of the specimen using a razor blade. The test specimens thus obtained were subjected to a three-point bending test under conditions of a support distance of 50 mm, a test speed of 1 mm/min, and 23°C. From the bending test results, fracture toughness values (K1c and G1c) were evaluated in accordance with ASTM D-5045.

[Measurement of Impact Peel Strength]
Each component was weighed and thoroughly mixed according to the formulations shown in Tables 3 to 5 and 7 to obtain the first and second components of a two-component curable resin composition. The first and second components in Tables 3 to 5 and 7 were then thoroughly mixed to obtain a curable resin composition. The obtained curable resin composition was applied to two cold-rolled steel plates, which were then stacked so that the thickness of the curable resin composition was 0.25 mm. The curable resin composition was cured under the curing conditions (curing temperature, curing time) shown in Tables 3 to 5 and 7 to obtain a laminate. Using this laminate, the dynamic splitting resistance (Impact Peel strength) was measured at 23°C in accordance with ISO 11343, and the toughness of the cured product (adhesive layer) was evaluated.

[Measurement of T-peel adhesive strength]
Each component was weighed and thoroughly mixed according to the formulations shown in Tables 5 and 6 to obtain the first and second components of a two-component curable resin composition. The first and second components shown in Tables 5 and 6 were then thoroughly mixed to obtain a curable resin composition. The resulting curable resin composition was applied to two cold-rolled steel plates (SPCC steel plates) measuring 25 mm wide x 200 mm long x 0.5 mm thick, and the two cold-rolled steel plates were then overlapped so that the adhesive layer was 0.25 mm thick. The composition between the two cold-rolled steel plates was then cured under the curing conditions (curing temperature, curing time) listed in Tables 5 and 6 to obtain a laminate. Using the resulting laminate as a sample, the T-peel adhesive strength (N/25 mm) was measured in accordance with JIS K6854 to evaluate the toughness of the cured product (adhesive layer). The measurement conditions were a temperature of 23°C and a test speed of 254 mm/min.

[Measurement of shear bond strength]
Each component was weighed and thoroughly mixed according to the formulation shown in Table 6 to obtain the first and second components of a two-component curable resin composition. The first and second components in Table 6 were then thoroughly mixed to obtain a curable resin composition. The resulting curable resin composition was applied to two cold-rolled steel plates (SPCC steel plates) measuring 25 mm wide x 100 mm long x 1.6 mm thick, and the two cold-rolled steel plates were then overlapped so that the adhesive layer was 0.25 mm thick. The composition between the two cold-rolled steel plates was then cured under the curing conditions (curing temperature, curing time) listed in Table 6 to obtain a laminate. Using the resulting laminate as a sample, the shear bond strength (MPa) was measured according to JIS K6850 using an Autograph AG-2000E (manufactured by Shimadzu Corporation) to evaluate the toughness of the cured product (adhesive layer). The measurement conditions were a temperature of 23°C and a test speed of 1.3 mm/min.

[Measurement of Glass Transition Temperature (Tg) and Storage Modulus at 70°C]
For the compositions in Tables 1 and 2, each 5 mm thick plate-shaped cured product obtained in the above [Measurement of fracture toughness (K1c, G1c)] was cut into a length of 40 mm, a thickness of 5 mm, and a width of 3 mm to prepare a test specimen.

The first and second components in Tables 3 to 7 were thoroughly mixed to obtain curable resin compositions. The obtained curable resin compositions were poured between two fluorine-coated steel plates (dimensions: 10 cm x 2.5 cm x 0.5 cm) sandwiching a 0.3 mm thick spacer. The curable resin compositions were then cured under the curing conditions (curing temperature, curing time) listed in Tables 3 to 7 to obtain 0.3 mm thick plate-shaped cured products. Each cured product was then cut into a length of 30 mm, width of 5 mm, and thickness of 0.3 mm to prepare test specimens.

Dynamic viscoelasticity measurements were performed on the resulting test specimens using an ITK DVA-200 dynamic viscoelasticity measuring device (ITK Measurement & Control Co., Ltd.) in tension mode at a frequency of 1 Hz, with the temperature rising at a rate of 8°C/min. From the results obtained, the temperature (°C) at which the loss tangent (tan δ) was maximized was determined to be the glass transition temperature (Tg). Furthermore, from the results obtained, the storage modulus (GPa) at 70°C was measured to evaluate the heat resistance of the cured product.

[Measurement of degree of cure of cured product by DSC]
10 mg of each curable resin composition in Tables 1 and 2 was sampled. For the compositions in Tables 3, 4, and 6, 10 mg of each curable resin composition obtained by thoroughly mixing the first component and the second component was sampled. The curable resin compositions were measured using a DSC, with the temperature rising from 30°C to 250°C at a heating rate of 10°C/min, and a heat generation curve was obtained. The total heat generation amount QT of each curable resin composition was calculated by integrating the heat generation peak of the heat generation curve.

Next, for the compositions in Tables 1 and 2, the cured products were obtained in the form of 5 mm thick plates as obtained in the above [Measurement of fracture toughness (K1c, G1c)]. Each cured product was then cut into a length of 3.0 mm, thickness of 1.5 mm, and width of 2.5 mm to prepare test specimens.

Furthermore, for the compositions in Tables 3, 4, and 6, each 0.3 mm thick plate-shaped cured product obtained in the above [Measurement of glass transition temperature (Tg) and storage modulus at 70°C] was cut into a length of 3.0 mm x thickness of 0.3 mm x width of 2.5 mm. Five of these small plate-shaped cured products were stacked to form a test specimen.

The obtained test specimens were heated from 30°C to 250°C at a rate of 10°C/min using a DSC, and a heat generation curve was obtained. The heat generation peak of the heat generation curve was integrated to calculate the residual heat generation amount QR of each cured product.

The degree of cure (%) of the cured product obtained by DSC was calculated based on the following formula:
Curing degree (%) = {(QT-QR)/QT}×100.

(Examples 1 to 7, Comparative Examples 1 to 3, Reference Examples 1 and 2)
Curable resin compositions were obtained by weighing each component and thoroughly mixing them to obtain the formulations shown in Tables 1 and 2. The degree of cure, fracture toughness (K1c and G1c), glass transition temperature (Tg), and storage modulus at 70°C of the obtained curable resin compositions were measured and evaluated according to the methods described above. The results are shown in Tables 1 and 2.

(Examples 8 to 28, Comparative Examples 4 to 12)
Each component was weighed and thoroughly mixed according to the formulations shown in Tables 3 to 7 to obtain the first and second components of two-component curable resin compositions. The degree of cure, impact peel strength, T-peel adhesive strength, shear adhesive strength, glass transition temperature (Tg), and storage modulus at 70°C of the obtained curable resin compositions were measured and evaluated according to the methods described above. The results are shown in Tables 3 to 7.

According to one embodiment of the present invention, a curable resin composition can be provided that, when cured at low temperatures, provides a cured product that exhibits an excellent balance between heat resistance and toughness. Therefore, the curable resin composition according to one embodiment of the present invention can be suitably used in applications such as adhesives (e.g., vehicle adhesives (structural adhesives) for vehicles and aircraft, adhesives for secondary batteries such as EV battery cells, and structural adhesives for wind power generation), paints, materials for impregnating glass fibers and/or carbon fibers to obtain composite materials, materials for printed wiring boards, solder resists, interlayer insulating films, build-up materials, FPC adhesives, electrically insulating materials such as encapsulants for electronic components such as semiconductors and LEDs, die bond materials, underfills, mounting materials for semiconductors (e.g., ACF, ACP, NCF, NCP, etc.), encapsulants for display devices (e.g., liquid crystal panels and OLED displays), encapsulants for lighting devices (e.g., OLED lighting), composite materials for concrete repair, and coating materials (e.g., concrete coating materials).

Claims (15)

The composition comprises the following components (A), (B), (C), and (D),
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A curable resin composition for low temperature curing that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C). A two-component or multi-component curable resin composition for low-temperature curing, comprising a first component and a second component,
The first component includes the following components (A) and (D):
Component (A): epoxy resin;
Component (D): an epoxy-based reactive diluent;
The second component includes the following component (C):
Component (C): epoxy curing agent;
The curable resin composition further contains the following component (B):
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
A two-component or multi-component curable resin composition for low-temperature curing that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
The content of the component (c1) is 25% by mass to 100% by mass relative to 100% by mass of the component (C);
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
the active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq;
The content of the component (c2) is 25% by mass to 100% by mass relative to 100% by mass of the component (C). The curable resin composition according to claim 1 or 2, wherein the component (C) further contains the following component (c3):
Component (c3): Amine-terminated butadiene nitrile rubber. The curable resin composition according to claim 1 or 2, wherein the core layer of component (b1) contains one or more rubbers selected from the group consisting of diene rubbers, (meth)acrylate rubbers, and organosiloxane rubbers. The curable resin composition according to claim 1 or 2, wherein the content of component (B) is 1 to 200 parts by mass per 100 parts by mass of component (A). The curable resin composition according to claim 1 or 2, wherein the component (c1) includes one or more selected from the group consisting of isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), N-aminoethylpiperazine, piperazine, and menthenediamine. The curable resin composition according to claim 1 or 2, wherein the content of component (C) is 5 to 100 parts by mass per 100 parts by mass of component (A). The curable resin composition according to claim 1 or 2, wherein the content of component (c1) is 3.5% by mass to 30.0% by mass, relative to 100% by mass of the total amount of the curable resin composition. The curable resin composition according to claim 1 or 2, wherein the content of component (D) is 1.0 to 100.0 parts by mass per 100 parts by mass of component (A). The curable resin composition according to claim 1 or 2, further comprising 5 to 300 parts by mass of calcium carbonate per 100 parts by mass of component (A). Use of the curable resin composition according to claim 1 or 2 as one or more materials selected from the group consisting of adhesives, impregnation materials, and coating materials. Use of a curable resin composition, comprising a step of curing the curable resin composition according to claim 1 or 2 at low temperature. A method for producing a cured product, comprising the step of curing the curable resin composition described in claim 1 or 2 at low temperature. A cured product obtained by curing a curable resin composition containing the following components (A), (B), (C), and (D):
Component (A): epoxy resin;
Component (B): one or more selected from the group consisting of the following components (b1), (b2), (b3), and (b4);
Component (b1): polymer particles having a core-shell structure including a core layer and a shell layer;
Component (b2): Blocked urethane; Component (b3): Rubber-modified epoxy resin;
Component (b4): urethane-modified epoxy resin;
Component (C): epoxy curing agent;
Component (D): an epoxy-based reactive diluent;
A degree of cure by differential scanning calorimetry (DSC) of 50% to 95%;
The curable resin composition has a cured product that satisfies the following (1) and/or (2):
(1)
The component (C) includes the following component (c1):
Component (c1): alicyclic amine;
(2)
The component (C) includes the following component (c2):
Component (c2): polyamidoamine;
The active hydrogen equivalent of the component (C) is 50 g/eq to 90 g/eq. The cured product according to claim 14, wherein the content of the (c1) component and/or the (c2) component is 25% by mass to 100% by mass relative to 100% by mass of the (C) component.