JP7752175B2 - Curable composition, cured product, and two-component curable composition - Google Patents

Description

The present invention relates to a curable composition, a cured product, and a two-component curable composition.

Polymers containing reactive silicon groups in their molecules are known as compositions that crosslink and cure through the formation of siloxane bonds, which are accompanied by hydrolysis of silyl groups due to moisture in the atmosphere or on the substrate. Among these, polymers containing reactive silicon groups such as alkoxysilyl groups are widely used as adhesives, sealants, and paints in construction and building materials, automotive applications, and other applications.

In particular, it is known that by using polyoxyalkylene polymers and (meth)acrylate polymers or polysiloxane compounds having reactive silicon groups of a specific structure, it is possible to obtain curable compositions that are fast-curing and have excellent adhesive properties and storage stability (see, for example, Patent Documents 1 to 4).

JP 2014-101499 A WO 2009/104700 International Publication No. 2010/110107 Japanese Patent Application Laid-Open No. 2018-016796

Curable compositions containing polymers with reactive silicon groups in their molecules are often cured using catalysts such as tin-based compounds to accelerate the curing reaction. However, the use of tin-based compounds is undesirable due to their environmental impact and toxicity to the human body.

The curable compositions described in Patent Documents 1 to 3 above are characterized by their ability to cure well without the use of tin-based compounds. However, the curable composition disclosed in Patent Document 1 has a polymer having a silyl group represented by a specific formula that is highly reactive, and the reaction proceeds even in the presence of moisture in the air. This necessitates storage in an airtight container that blocks air, and the curable composition must be used up or discarded after removal from the storage container.

In light of the above circumstances, there is a need for the development of a curable composition that does not cure at room temperature but cures upon a certain level of heat treatment. The curable compositions disclosed in Patent Documents 2 to 4 are characterized by rapid curing at room temperature, but there is no mention of them curing under the desired thermal environment.

The objective of the present invention is to provide a curable composition that cures quickly without the use of a tin-based curing catalyst, has excellent storage stability and mechanical properties, and can form a cured product that cures under a desired thermal environment, a curable composition with excellent adhesiveness, and a two-component curable composition.

The present invention relates to, for example, the following [1] to [8].
[1] A curable composition comprising: a (meth)acrylic polymer (A) having a group represented by formula (1) and containing 1,500 ppm or more of silicon element; and a salt compound (B) composed of an acid having an acid dissociation constant (pKa) of less than 3.5 and a base having a pKa of 10 or more.
Formula (1): -X-CH ₂ -SiR ¹ ₃
[In formula (1), R ^1s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and at least one of the R ^1s is the alkoxy group or hydroxyl group; X is a divalent group represented by -O-, -COO-, -S-, -N(R ² )-, -CH(OH)-CH ₂ -O-, -O-CO-NH-, or -N(R ² )-CO-N(R ³ )-, and R ² and R ³ are a hydrogen atom, a hydrocarbon group, or a halogenated hydrocarbon group, and R ² and R ³ may be the same or different.]

[2] The curable composition described in [1] above, containing 0.01 to 50 parts by mass of the salt compound (B) per 100 parts by mass of the (meth)acrylic polymer (A).

[3] The curable composition described in [1] or [2] above, wherein the (meth)acrylic polymer (A) has a group represented by formula (1) at least at the molecular chain terminal.

[4] The curable composition described in any one of [1] to [3] above, wherein the number average molecular weight (Mn) of the (meth)acrylic polymer (A) is 1,000 to 100,000.

[5] The curable composition according to any one of [1] to [4], wherein the salt compound (B) is a salt compound composed of an organic acid having a pKa of 1 or more and less than 3.5 and an organic base having a pKa of 10 or more and less than 15.
[6] The curable composition according to any one of [1] to [5], containing 1 to 1,000 parts by mass of the epoxy resin (C) per 100 parts by mass of the (meth)acrylic polymer (A).
[7] A cured product obtained from the curable composition according to any one of [1] to [6] above.
[8] A two-component curable composition comprising a first part containing the curable composition according to any one of [1] to [6] above and a polymerization initiator, and a second part containing a reducing agent.

The present invention provides a curable composition that cures quickly without the use of a tin-based curing catalyst, has excellent storage stability and mechanical properties, and can form a cured product that cures under a desired thermal environment; a curable composition with excellent adhesive properties; and a two-component curable composition.

The present invention will be specifically described below.
[Curable composition]
A curable composition according to one embodiment of the present invention (hereinafter also referred to as "the composition of the present invention") contains a (meth)acrylic polymer (A) and a salt compound (B), which are described below. The composition of the present invention can be used as a one-component curable composition.

In this specification, (meth)acrylic is used as a general term for acrylic and methacrylic, and may be either acrylic or methacrylic. (Meth)acrylate is used as a general term for acrylate and methacrylate, and may be either acrylate or methacrylate. (Meth)acryloyl is used as a general term for acryloyl and methacryloyl, and may be either acryloyl or methacryloyl.

<(Meth)acrylic polymer (A)>
The (meth)acrylic polymer (A) (hereinafter also referred to as "polymer (A)") is a polymer having a group represented by formula (1) and containing 1,500 ppm or more of silicon element.

Formula (1): -X-CH ₂ -SiR ¹ ₃
[In formula (1), R ^1s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and at least one of the R ^1s is the alkoxy group or hydroxyl group; X is a divalent group represented by -O-, -COO-, -S-, -N(R ² )-, -CH(OH)-CH ₂ -O-, -O-CO-NH-, or -N(R ² )-CO-N(R ³ )-, and R ² and R ³ are a hydrogen atom, a hydrocarbon group, or a halogenated hydrocarbon group, and R ² and R ³ may be the same or different.]

Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, n-octyl, isooctyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, Examples of such alkyl groups include linear and branched alkyl groups such as 2,2-dimethylheptyl, 2,6-dimethyl-4-heptyl, 3,5,5-trimethylhexyl, n-decyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, 1-hexylheptyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl, and are preferably alkyl groups having 1 to 10 carbon atoms, more preferably alkyl groups having 1 to 3 carbon atoms. The alkyl groups may be linear or branched.

Examples of alkoxy groups having 1 to 20 carbon atoms include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, n-pentyloxy, isopentyloxy, neopentyloxy, n-hexyloxy, 1-methylpentyloxy, 4-methyl-2-pentyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-heptyloxy, 1-methylhexyloxy, n-octyloxy, isooctyloxy, 1-methylheptyloxy, 2-ethylhexyloxy, and 2-propylpentyloxy. Examples of alkoxy groups include linear and branched alkoxy groups such as n-nonyloxy, 2,2-dimethylheptyloxy, 2,6-dimethyl-4-heptyloxy, 3,5,5-trimethylhexyloxy, n-decyloxy, n-undecyloxy, 1-methyldecyloxy, n-dodecyloxy, n-tridecyloxy, 1-hexylheptyloxy, n-tetradecyloxy, n-pentadecyloxy, n-hexadecyloxy, n-heptadecyloxy, n-octadecyloxy, and n-eicosyloxy, and are preferably alkoxy groups having 1 to 10 carbon atoms, more preferably 1 to 3 carbon atoms. The alkoxy group may be linear or branched.

Examples of the hydrocarbon group for ^R2 and ^R3 include alkyl groups having 1 to 18 carbon atoms, preferably 1 to 3 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, 2-ethylhexyl, n-octyl, and isooctyl; cycloalkyl groups having 3 to 18 carbon atoms, preferably 5 to 8 carbon atoms, such as cyclopentyl and cyclohexyl; alkenyl groups having 2 to 18 carbon atoms, preferably 2 to 5 carbon atoms, such as vinyl, allyl, 3-butenyl, and 5-hexenyl; and aryl groups having 6 to 18 carbon atoms, preferably 6 to 10 carbon atoms, such as phenyl, naphthyl, and anthryl.

The halogenated hydrocarbon group in ^R2 and ^R3 is a group in which at least some of the hydrogen atoms constituting the aforementioned hydrocarbon group have been substituted with halogen atoms, such as fluorine, chlorine, bromine, and iodine atoms.
^R2 and ^R3 are preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrocarbon group.

Examples of the group represented _by ^--SiR.sub.13 include a dimethylmethoxysilyl group, a dimethylethoxysilyl group, a methyldimethoxysilyl group, a methyldiethoxysilyl group, a trimethoxysilyl group, a triethoxysilyl group, a dimethylisopropoxysilyl group, a methyldiisopropoxysilyl group, and a triisopropoxysilyl group.

From the viewpoint of curability and mechanical properties, polymer (A) has a group represented by formula (1) and contains 1,500 ppm or more, preferably 1,600 to 20,000 ppm, and more preferably 1,700 to 10,000 ppm of silicon element. Note that "ppm" means wt ppm. In one embodiment, polymer (A) preferably has a group represented by formula (1) at the molecular chain terminal of the polymer. Note that the silicon element content derived from the group represented by formula (1) in polymer (A) can be calculated from the charge ratio, but can also be measured by ICP atomic emission spectroscopy. Details are provided in the Examples section.

<(Meth)acrylic acid alkyl ester (a1)>
The polymer (A) is preferably a polymer of a polymerizable monomer component containing a (meth)acrylic acid alkyl ester (a1) (hereinafter also referred to as "monomer (a1)") having an alkyl group with a carbon number of 1 to 12. That is, the polymer (A) preferably has a structural unit derived from the monomer (a1).

The alkyl group may be straight or branched.
Examples of the monomer (a1) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, and lauryl (meth)acrylate.

The monomer (a1) may be used alone or in combination of two or more.
The proportion of monomer (a1) in the polymerizable monomer components constituting polymer (A) is preferably 20% by mass or more, more preferably 20 to 99% by mass, even more preferably 20 to 97% by mass, and particularly preferably 22 to 96% by mass. Polymer (A) can have structural units derived from monomer (a1) in the same range among all structural units. When a (meth)acrylic acid alkyl ester (a1) having an alkyl group with 8 to 12 carbon atoms is used in the above range, a (meth)acrylic polymer with excellent mechanical properties can be obtained.

<Hydrolyzable Silyl Group-Containing (Meth)acryloyl Monomer (a2)>
It is preferable that the polymer (A) further contains a structural unit derived from a hydrolyzable silyl group-containing (meth)acryloyl monomer (a2) (hereinafter also referred to as "monomer (a2)") that is copolymerizable with the monomer (a1) and has a group represented by formula (1).
As the monomer (a2), for example, a compound represented by formula (a2-1) is preferable.

In formula (a2-1), R ^a represents a hydrogen atom or a methyl group, and R ¹ has the same meaning as R ¹ in formula (1).

Examples of compounds represented by formula (a2-1) include (meth)acryloxy group-containing silanes such as (meth)acryloxymethyldimethylmethoxysilane, (meth)acryloxymethyldimethylethoxysilane, ((meth)acryloxymethyl)methyldimethoxysilane, ((meth)acryloxymethyl)methyldiethoxysilane, (meth)acryloxymethyltrimethoxysilane, and (meth)acryloxymethyltriethoxysilane.

Examples of monomer (a2) include compounds in which an isocyanate group of a compound represented by OCN-CH 2 -SiR ¹ ₃ (R ¹ has the same meaning as the same symbol explained in formula (1)) is added to a hydroxy group of a hydroxyalkyl (meth)acrylate such as 2-hydroxyethyl (meth)acrylate or _4- hydroxybutyl (meth)acrylate, or to an amino group of an aminoalkyl (meth)acrylate such as 2-aminoethyl (meth)acrylate. Specific examples of compounds represented by OCN-CH ₂ -SiR ¹ ₃ will be described later.

The monomer (a2) may be used alone or in combination of two or more.
The proportion of monomer (a2) in the polymerizable monomer components constituting polymer (A) is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. Polymer (A) can have structural units derived from monomer (a2) in the same range among all structural units. When monomer (a2) is used in the above range, a group represented by formula (1) can be introduced into polymer (A). Therefore, the resulting polymer (A) has appropriate crosslinkability and is suitable for applications in which a crosslinked product is formed.

<<Other Monomers (a3)>>
The polymer (A) may further contain a structural unit derived from a monomer (a3) other than the monomers (a1) and (a2) within the scope of the present invention.

Examples of the other monomer (a3) include:
(meth)acrylic acid alkyl esters having an alkyl group carbon number of 13 or more, preferably an alkyl group carbon number of 22, such as n-tridecyl (meth)acrylate, isodecyl (meth)acrylate, n-myristyl (meth)acrylate, isomyristyl (meth)acrylate, n-pentadecyl (meth)acrylate, isopentadecyl (meth)acrylate, n-cetyl (meth)acrylate, isocetyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate, n-nonadecyl (meth)acrylate, isononadecyl (meth)acrylate, n-eicosyl (meth)acrylate, and isoeicosyl (meth)acrylate;
(meth)acrylates containing an alicyclic hydrocarbon group or an aromatic hydrocarbon group, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, and phenyl (meth)acrylate;
alkoxyalkyl (meth)acrylates such as methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate;
polyalkylene glycol (meth)acrylates such as methoxypolyethylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate, octoxypolyethylene glycol mono(meth)acrylate, lauroxypolyethylene glycol mono(meth)acrylate, stearoxypolyethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate;
hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate;
(meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid; carboxy group-containing monomers such as carboxy group-containing (meth)acrylates such as β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, succinic acid mono(meth)acryloyloxyethyl ester, and ω-carboxypolycaprolactone mono(meth)acrylate;
Acid anhydride group-containing monomers such as phthalic anhydride and maleic anhydride;
Dialkylaminoalkyl (meth)acrylates such as 2-dimethylaminoethyl (meth)acrylate and 2-diethylaminoethyl (meth)acrylate;
(Meth)acrylamides; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, and N-hexyl(meth)acrylamide; amide group-containing monomers such as N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide;
Cyano group-containing monomers such as (meth)acrylonitrile;
Nitrogen-based heterocycle-containing monomers such as N-vinylpyrrolidone, N-vinylmorpholine, N-vinylcaprolactam, (meth)acryloylmorpholine, N-cyclohexylmaleimide, N-phenylmaleimide, N-laurylmaleimide, and N-benzylmaleimide;
Styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, divinylbenzene, and indene;
vinyl ester compounds such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl benzoate, and vinyl cinnamate;

Among other monomers (a3), (meth)acrylic acid alkyl esters other than monomer (a1) and polyalkylene glycol (meth)acrylates are preferred, and (meth)acrylic acid alkyl esters other than monomer (a1) are more preferred.

The other monomers (a3) may be used alone or in combination of two or more.
The proportion of the other monomer (a3) in the polymerizable monomer components constituting the polymer (A) is preferably 1 to 65 mass %, more preferably 5 to 60 mass %. The polymer (A) may have structural units derived from the other monomer (a3) in the total structural units in a similar range.

<Mercapto group-containing compound (d)>
In producing the polymer (A), a mercapto group-containing compound (d) may be used as a chain transfer agent.
The mercapto group-containing compound (d) acts as a chain transfer agent due to its functional group (—SH) with high chain transfer properties in radical polymerization. When polymerizing a polymerizable monomer component in the presence of the mercapto group-containing compound (d), a structural unit derived from the mercapto group-containing compound (d), particularly a mercapto group-containing compound having a group represented by formula (1), is used. The group represented by formula (1) can be introduced to the molecular chain terminal of the polymer. Furthermore, by introducing the mercapto group-containing compound (d) represented by formula (1) into a polymer having a polymerizable unsaturated group by an ene-thiol reaction, the group represented by formula (1) can also be introduced into the polymer. Curable compositions using a polymer (A) having a group represented by formula (1) at the molecular chain terminal have excellent curing speed and mechanical properties.

When the monomer (a2) is used, the group represented by formula (1) in the monomer (a2) and the group represented by formula (1) in the mercapto group-containing compound (d) may be the same or different.
The mercapto group-containing compound (d) is preferably a compound represented by formula (d-1).
Formula (d-1): HS-CH ₂ -SiR ¹ ₃
In formula (d-1), R ¹ has the same meaning as R ¹ in formula (1).

Among the mercapto group-containing compounds (d), examples of compounds represented by formula (d-1) include mercaptomethyldimethylmethoxysilane, mercaptomethyldimethylethoxysilane, mercaptomethyldimethylisopropoxysilane, mercaptomethylmethyldimethoxysilane, mercaptomethylmethyldiethoxysilane, mercaptomethylmethyldiisopropoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, and mercaptomethyltriisopropoxysilane. Among these, mercaptomethyldimethylmethoxysilane, mercaptomethylmethyldimethoxysilane, mercaptomethyltrimethoxysilane, and mercaptomethyltriethoxysilane are preferred. By using a compound represented by formula (d-1), a group represented by formula (1) can be introduced into the molecular chain terminal of polymer (A).

Other mercapto group-containing compounds (d) include, for example, n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, lauryl mercaptan, mercaptopropylmethyldimethoxysilane, mercaptopropyltrimethoxysilane, and other mercapto group-containing compounds.

The compound (d) can be used alone or in combination of two or more.
The mercapto group-containing compound (d) is preferably used in an amount of 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, per 100 parts by mass of the total of the polymerizable monomer components. In such an embodiment, the number average molecular weight of the polymer (A) can be adjusted to an appropriate range.

<Production of Polymer (A)>
The polymer (A) can be obtained by various polymerization methods, and the method is not particularly limited, but it is preferable to obtain it by, for example, the following method. Note that the methods (i) to (iv) may be used in any combination.

(i) A method of copolymerizing a monomer (a2) having a polymerizable unsaturated group and a group represented by formula (1) with the above-mentioned monomer (a1) having a (meth)acrylic structure.
(ii) A method of polymerizing a monomer (a1) having a (meth)acrylic structure in the presence of a mercapto group-containing compound (d) having a group represented by formula (1) as a chain transfer agent.
(iii) A method of reacting a polymer having a reactive functional group obtained by copolymerizing a compound having a polymerizable unsaturated group and a reactive functional group (for example, a hydroxy group, an isocyanate group, or an amino group) and a monomer component containing monomer (a1) with a compound (e) having a group that undergoes an addition reaction with the reactive functional group and that can introduce a group represented by formula (1) into the polymer by the addition reaction.

Examples of the compound (e) include compounds represented by formula (e-1) and formula (e-2) (hereinafter also referred to as "compound (e-1)" and "compound (e-2)", respectively).
Formula (e-1): OCN-CH ₂ -SiR ¹ ₃
[R ¹ has the same meaning as the same symbol in formula (1)]

Examples of compound (e-1) include 1-isocyanatemethyldimethylmethoxysilane, 1-isocyanatemethyldimethylethoxysilane, 1-isocyanatemethyldimethylisopropoxysilane, (1-isocyanatemethyl)methyldimethoxysilane, (1-isocyanatemethyl)methyldiethoxysilane, (1-isocyanatemethyl)methyldiisopropoxysilane, 1-isocyanatemethyltrimethoxysilane, 1-isocyanatemethyltriethoxysilane, and 1-isocyanatemethyltriisopropoxysilane. Among these, 1-isocyanatemethyldimethylmethoxysilane, (1-isocyanatemethyl)methyldimethoxysilane, 1-isocyanatemethyltrimethoxysilane, and 1-isocyanatemethyltriethoxysilane are preferred.

Formula (e-2): R ⁴ -CH ₂ -SiR ¹ ₃
[ ^R1 has the same meaning as the same symbol in formula (1), and ^R4 represents a glycidyloxy group, an amino group, an alkylamino group, an (aminoalkyl)amino group, an (N,N-dialkylaminoalkyl)amino group, or a halogenated hydrocarbon group.]

Examples of the compound (e-2) include aminomethyltrimethoxysilane, aminomethyltriethoxysilane, (aminoethylamino)methyltrimethoxysilane, (N,N-dimethylamino)ethylaminomethyltrimethoxysilane, and glycidyloxymethyltrimethoxysilane.
The compound (e) can be used alone or in combination of two or more.
The compound (e) is used in an amount of preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, per 100 parts by mass of the total of the polymerizable monomer components.

(iv) A method in which monomer (a1) is polymerized by living polymerization, functional groups such as alkenyl groups or hydroxyl groups are introduced to the ends of the molecular chain, and the resulting polymer is then reacted with compound (d) or compound (e), etc.

Polymer (A) can be produced using known polymerization methods such as cationic polymerization, anionic polymerization, and radical polymerization, as in methods (i) to (iv) above. While the method is not particularly limited, radical polymerization is preferred in terms of the versatility of monomers and industrial productivity. Radical polymerization methods include living radical polymerization, which allows for the introduction of specific functional groups (e.g., groups represented by formula (1)) at controlled positions such as terminals, and free radical polymerization, which copolymerizes specific monomer units using a polymerization initiator.

Living polymerization methods include living cationic polymerization, living anionic polymerization, and living radical polymerization, but living radical polymerization is preferred from the perspective of industrial productivity. Examples of living radical polymerization methods include atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, nitroxide-mediated polymerization (NMP), organotellurium compound-mediated polymerization (TERP), and iodine compound-mediated polymerization (IRP). By selecting the reaction conditions, polymers with terminal functional groups can be obtained.

In the free radical polymerization method, for example, polymerizable monomer components and, if necessary, a mercapto group-containing compound (d) are charged into a reaction vessel, a polymerization initiator is added, and the reaction is carried out at a reaction temperature of approximately 40 to 90°C for 2 to 20 hours. A polymerization solvent may be added to the reaction if necessary. For example, the polymerization is carried out under an inert gas atmosphere such as nitrogen gas. Furthermore, the polymerizable monomer components, polymerization initiator, chain transfer agent, and polymerization solvent may be added as appropriate during the polymerization reaction.

Examples of polymerization initiators include azo compound-based polymerization initiators, peroxide-based polymerization initiators, and photoradical polymerization initiators. It is preferable not to use a metal catalyst. Polymer (A) produced using such a polymerization initiator does not contain any metal components derived from the catalyst, which can improve crosslinking reaction inhibition and coloration. Furthermore, because depolymerization reactions caused by metal components can be suppressed, cured products with excellent durability can be provided for use in a variety of applications.

Examples of azo compound polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, ... 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

Examples of peroxide polymerization initiators include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, and 2,2-bis(4,4-di-t-butylperoxycyclohexyl). Examples thereof include propane, 2,2-bis(4,4-di-t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane.

As the photoradical polymerization initiator, compounds conventionally used as photoradical polymerization initiators are preferred, such as benzoin-based initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and 1-hydroxy-2-methyl-1-phenyl-propan-1-one. Acetophenone-based initiators such as cyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, and N,N-dimethylaminoacetophenone; anthraquinone-based initiators such as 2-methylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, and 2-isopropylthioxanthone; thioxanthone-based initiators such as acetophenone dimethyl ketal and benzyl methyl ketal; benzophenone-based initiators such as benzophenone, methylbenzophenone, 4-phenylbenzophenone, 2,4,6-trimethylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone and 4-benzoyl-4'-methyldiphenyl sulfide; 2,4 ,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4'-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and other acylphosphine oxide initiators; oxime ester initiators such as 1-[4-(phenylthio)phenyl]octane-1,2-dione=2-(O-benzoyloxime); camphorquinone, and α-hydroxyketones.

The photoradical polymerization initiator may be used alone or in combination of two or more kinds.
The photoradical polymerization initiator may be combined with a sensitizer, and examples of the sensitizer include anthracene compounds such as 9,10-dibutoxyanthracene and 9,10-bis(acyloxy)anthracene.

The polymerization initiators can be used alone or in combination.
The polymerization initiator may be added successively multiple times.
The amount of the polymerization initiator used is usually 0.001 to 2 parts by mass, and preferably 0.002 to 1 part by mass, per 100 parts by mass of the polymerizable monomer component. By using the polymerization initiator within the above range, the number average molecular weight of the polymer (A) can be adjusted within an appropriate range.

The polymerization solvent is preferably an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate, and methyl propionate; ketones such as acetone, acetylacetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; and sulfoxides such as dimethyl sulfoxide and sulfolane.
The polymerization solvent may be used alone or in combination of two or more kinds.

<Physical properties of polymer (A)>
The number average molecular weight (Mn) of the polymer (A) is preferably 1,000 or more, more preferably 3,000 or more, and even more preferably 5,000 or more, from the viewpoint of the viscosity of the polymer and the mechanical properties of the resulting cured product, and is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less, from the viewpoint of the viscosity of the polymer.

The number average molecular weight (Mn) is measured by gel permeation chromatography (GPC).
The glass transition temperature (Tg) of the polymer (A) is preferably −80° C. to 100° C. Tg is determined by differential scanning calorimetry (DSC).
Details of the measurement conditions for GPC and DSC will be described in the Examples section below.

<Content of polymer (A)>
The composition of the present invention may contain one or more polymers (A).
The composition of the present invention preferably contains 5% by mass or more of the polymer (A) in total, more preferably 8 to 95% by mass, and even more preferably 10 to 90% by mass.

<Salt Compound (B)>
The composition of the present invention contains a salt compound (B) composed of an acid having an acid dissociation constant (pKa) of less than 3.5 and a base having a pKa of 10 or more.
The salt compound (B) is a compound that melts, dissolves, or is activated by applying a temperature equal to or higher than a certain level, and functions as a curing agent for at least the polymer (A), i.e., a so-called latent curing agent. When the composition of the present invention contains the salt compound (B) composed of an acid and a base having a predetermined pKa value, the pot life of the composition of the present invention is extended, a cured product that can be cured under a desired thermal environment is formed, and a curable composition with excellent storage stability is obtained.
Examples of acids having a pKa of less than 3.5 include:
Carboxylic acids such as o-phthalic acid (2.9), acetoacetic acid (3.58), and maleic acid (1.93); halogenated carboxylic acids such as chloroethanoic acid (2.87), dichloroethanoic acid (1.35), trichloroethanoic acid (0.66), fluoroethanoic acid (2.59), bromoethanoic acid (2.90), and iodoethanoic acid (3.18);
Phenols such as 2,4,6-trinitrophenol (0.42);
Sulfinic acids such as paratoluenesulfonic acid (2.4) and trifluoromethanesulfonic acid (-14):
Examples of inorganic acids include hydrochloric acid (-8.0), nitric acid (-1.3), sulfuric acid (-3.0), phosphoric acid (2.12), hydrogen fluoride (3.17), and fluoroantimonic acid (-25).

Among these, from the viewpoints of the pot life and curability of the curable composition, acids having a pKa of −25.0 to 3.5 are preferred, acids having a pKa of −5.0 to 3.5 are more preferred, and acids having a pKa of 1 or more but less than 3.5 are even more preferred. Furthermore, organic acids are preferred from the viewpoint of good compatibility with the curable composition.
The organic acid means carboxylic acids other than the inorganic acids, halogenated carboxylic acids, phenolic acids, and sulfinic acids.

Examples of bases having a pKa of 10 or more include:
Nitrogen-containing heterocyclic compounds such as 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) (12.0) and 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) (12.7);
Alcohols such as choline hydroxide (13.9), 2,2,2-trifluoroethanol (11.4);
Oximes such as benzophenone oxime (11.3), acetophenone oxime (11.48);
Amines such as ethylamine (10.63), n-butylamine (10.59), cyclohexylamine (10.64);
Sulfoniums such as trimethylsulfonium (27.0), dimethylbenzylsulfonium (22.6), dimethylphenylsulfonium (25.2), etc.;
Ammonium such as tetramethylammonium (35.1), trimethylphenylammonium (33.9), benzyltrimethylammonium (31.8), etc.;
Imidazolium such as 3-benzyl-2-(2,6-dimethylphenyl)-1,4,5-trimethyl-1H-imidazol-3-ium (28.8), 1,3-dibutyl-2-(2,6-dimethylphenyl)-4,5-dimethyl-1H-imidazol-3-ium (37.8), 3-benzyl-2-(2,6-dimethylphenyl)-1-methyl-4,5-diphenyl-1H-imidazol-3-ium (29.1);
Thiazolium compounds such as 1,2-dimethylthiazolium (16.4);
Azoliums such as 1,2,3-triazonium (24.9);
Guanidinium such as 1,1,2,2,3,3-hexamethylguanidinium (38.4);
Phosphoniums such as tetramethylphosphonium (28.9), trimethylphenylphosphonium (27.7), and benzyltrimethylphosphonium (23.9);
Pyridiniums such as N-methylpyridinium (27.7) and N-benzylpyridinium (24.1);
Examples include inorganic bases such as sodium hydroxide (13).

Among these, bases having a pKa of 10 or more and less than 15 are preferred from the viewpoint of the pot life and curability of the curable composition, and bases having a pKa of 11 to 14 are more preferred. Furthermore, organic bases are preferred from the viewpoint of good compatibility with the curable composition.
The organic base means a nitrogen-containing heterocyclic compound other than the inorganic bases, alcohol oxime, amine, sulfonium, ammonium, imidazolium, thiazolium, azolium, guanidium, phosphonium and pyridinium.
The numbers in parentheses for the acids and bases mentioned above are pKa(H ₂ O).

The salt compound (B) is commercially available, for example, U-CAT SA810 (o-phthalic acid salt of DBU), U-CAT SA506 (paratoluenesulfonic acid salt of DBU) (all manufactured by San-Apro), SI-60L, SI-80L, SI-100L, SI-110L (fluoroantimony salt of sulfonium, all manufactured by Sanshin Chemical Industry Co., Ltd.), Optomer
Examples of such a resin include CXC-66, Optomer CP-77 (all manufactured by ADEKA), CXC-1614, CXC-2700, CXC-1612, CXC-1821, and CXC-1738 (all manufactured by King Industries).

<Content of salt compound (B)>
The composition of the present invention may contain one or more salt compounds (B).
The content of the salt compound (B) in the composition of the present invention is preferably 0.01 to 100 parts by mass, more preferably 1 to 50 parts by mass, based on 100 parts by mass of the polymer (A). Such an embodiment is preferred from the viewpoint of obtaining a curable composition excellent in pot life and curability.

<Epoxy resin (C)>
The composition of the present invention may contain, in addition to the polymer (A) and the salt compound (B), an epoxy resin (C) as required.
The epoxy resin (C) may be, for example, an epoxy compound having two or more epoxy groups in one molecule.

Examples of the epoxy resin (C) include:
bisphenol type epoxy resins such as bisphenol A type epoxy resins, bisphenol E type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol O type epoxy resins, and bisphenol AD type epoxy resins, hydrogenated bisphenol type epoxy resins, alkyl-substituted bisphenol type epoxy resins, alkylene oxide-modified bisphenol type epoxy resins, biphenyl type epoxy resins, resorcinol type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, dicyclopentadiene novolac type epoxy resins, biphenyl novolac type epoxy resins, naphthalene phenol novolac type epoxy resins, and glycidyl amine type epoxy resins;

Diglycidyl ethers of bisphenols such as bisphenol A, bisphenol E, bisphenol F, bisphenol S, bisphenol O, and bisphenol AD, and 4,4-dihydroxybiphenyl (wherein the bisphenols and biphenyls may be hydrogenated (e.g., hydrogenated bisphenols), may have alkyl substituents (e.g., alkyl-substituted bisphenols), or may be modified with alkylene oxides such as ethylene oxide or propylene oxide (e.g., alkylene oxide-modified bisphenols)), ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diglycidyl ether compounds such as alkanediol diglycidyl ethers such as 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, and 2,2-dimethyl-1,3-propanediol diglycidyl ether; alkanetriol diglycidyl ethers such as glycerin diglycidyl ether; polyalkylene glycol diglycidyl ethers such as diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, and hexaethylene glycol diglycidyl ether; and diglycidyl ethers of alicyclic ring-containing dimethanols such as 1,4-cyclohexanedimethanol diglycidyl ether;

Glycerin triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N,N'-tetraglycidyl-m-xylylenediamine, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidyl isocyanurate, m-N,N-diglycidylaminophenyl glycidyl ether, N,N-diglycidyl toluidine, N,N-diglycidylaniline, 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate;

The epoxy resin (C) may be used alone or in combination of two or more.
The content of the epoxy resin (C) in the composition of the present invention is preferably 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass, per 100 parts by mass of the polymer (A). Such an embodiment is preferred from the viewpoint of obtaining a cured product having excellent strength.
The epoxy equivalent of the epoxy resin (C) is not particularly limited, but is preferably 100 to 3000 g/eq., more preferably 100 to 1000 g/eq.

<Polymer (F)>
The composition of the present invention may contain, in addition to the polymer (A), a polymer (F) having a polyether skeleton, if necessary. The polymer (F) preferably has a reactive silicon group, and particularly preferably has a group represented by the formula (1).

Polymer (F) has a polyether skeleton as its main chain skeleton. The polyether skeleton is preferably a polyoxyalkylene skeleton, such as a polyoxyethylene skeleton, a polyoxypropylene skeleton, a polyoxybutylene skeleton, a polyoxytetramethylene skeleton, a polyoxyethylene-polyoxypropylene skeleton, or a polyoxypropylene-polyoxybutylene skeleton, with a polyoxypropylene skeleton being preferred. The polyoxyalkylene skeleton may consist of only one type of repeating unit, or may consist of two or more types of repeating units. The repeating unit here is an oxyalkylene unit. Polymer (F) may have a urethane skeleton between the polyether skeletons.

The number average molecular weight (Mn) of polymer (F) is preferably 10,000 to 50,000. A number average molecular weight (Mn) that satisfies this condition is preferable in terms of compatibility with polymer (A), handling properties of the curable composition, and mechanical properties. The number average molecular weight (Mn) is measured by GPC.

Details of the GPC measurement conditions will be described in the Examples section below.
By using the polymer (F) together with the polymer (A), a curable composition having excellent mechanical properties can be obtained.

When polymer (F) is used, the group represented by formula (1) in polymer (A) and the group represented by formula (1) in polymer (F) may be the same or different.
In one embodiment, the polymer (F) preferably has a group represented by formula (1) at the molecular chain terminal of the polymer, and more preferably has a group represented by formula (1) at the molecular chain terminal of a polyether polymer.

Polymer (F) can be obtained, for example, by reacting the terminal hydroxyl group of a polyether polymer with the isocyanate group of the compound (e-1) represented by OCN-CH ₂ -SiR ¹ ₃ (R ¹ has the same meaning as the same symbol in formula (1)).

Polymer (F) can also be obtained by obtaining a polyether polymer having isocyanate groups at its terminals from a polyether polymer, and then reacting the terminal isocyanate groups of the polymer with an amino group, ^alkylamino _group , ( ^aminoalkyl ₎ amino ^group , or (N,N-dialkylaminoalkyl)amino group as ^R4 in compound (e-2) represented by R4-CH2-SiR13 (R1 has the same meaning as the same symbol described in formula (1)). A polyether polymer having isocyanate groups at its terminals can be obtained, for example, by a urethane reaction between a polyether polymer having terminal hydroxyl groups and a diisocyanate compound. Such a polyether polymer has a urethane skeleton between polyether skeletons.

Polymer (F) can also be obtained by obtaining a polyether polymer having an amino group at its terminal from a polyether polymer and reacting the terminal amino group of the polymer with the isocyanate group of compound (e-1).

Examples of the diisocyanate compound include:
Aliphatic diisocyanates having 4 to 30 carbon atoms, such as ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate;
Alicyclic diisocyanates having 7 to 30 carbon atoms, such as isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylylene diisocyanate;
aromatic diisocyanates having 8 to 30 carbon atoms, such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate;

The composition of the present invention may contain one or more polymers (F).
The content of polymer (F) in the composition of the present invention is preferably 10 to 900 parts by mass, more preferably 20 to 800 parts by mass, per 100 parts by mass of polymer (A). Such an embodiment is preferred from the viewpoint of obtaining a cured product having excellent mechanical properties.

<Other ingredients>
In addition to the polymer (A), the composition of the present invention may contain, as necessary, one or more other components such as a plasticizer, a filler, silica, a pigment, a fiber, an antioxidant, a dehydrating agent, a silane coupling agent having an amino group, a curing catalyst, a tackifying resin, a dispersant, a rheology control agent, an antifoaming agent, and an adhesion promoter.

<Plasticizer>
The composition of the present invention may further contain a plasticizer. The use of a plasticizer can improve the flexibility and extensibility of the cured product formed from the curable composition.

Examples of plasticizers include phthalate esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, and diisononyl phthalate; non-phthalate esters such as 1,2-cyclohexanedicarboxylic acid diisononyl ester and trioctyl trimellitate; aliphatic carboxylic acid esters such as dioctyl adipate, diisodecyl succinate, dibutyl sebacate, and butyl oleate; alcohol esters such as diethylene glycol dibenzoate, triethylene glycol dibenzoate, and pentaerythritol ester; phosphate esters such as trioctyl phosphate and tricresyl phosphate; epoxidized soybean oil, 4,5- Examples of polymer plasticizers include epoxy plasticizers such as dioctyl epoxyhexahydrophthalate and benzyl epoxystearate; hydrocarbons such as chlorinated paraffin; normal paraffin and isoparaffin; polyethylene glycol and derivatives thereof, polypropylene glycol and derivatives thereof, for example, polyethers in which the hydroxyl groups of polyethylene glycol or polypropylene glycol are blocked with alkyl ethers, poly-α-methylstyrene, polystyrene oligomers such as polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene, polyisoprene, polybutene, hydrogenated polybutene, and epoxidized polybutadiene, and (meth)acrylic polymers other than polymer (A).

One or more plasticizers can be used.
In one embodiment, the content of the plasticizer in the composition of the present invention is preferably 10 to 400 parts by mass, more preferably 50 to 300 parts by mass, per 100 parts by mass of the polymer component, from the viewpoints of the coatability of the curable composition and the weather resistance of the cured product.

<Filler>
The compositions of the present invention may further contain a filler.
Examples of fillers include calcium carbonate such as heavy calcium carbonate, light calcium carbonate, colloidal calcium carbonate, semi-colloidal calcium carbonate, light calcium carbonate, and calcium carbonate obtained by surface-treating the surface of these calcium carbonates with a fatty acid or a resin acid-based organic substance; carbon black; magnesium carbonate; diatomaceous earth; calcined clay; clay; talc; titanium oxide; bentonite; ferric oxide; zinc oxide; activated zinc oxide; aluminum hydroxide; inorganic hollow bodies such as shirasu balloons, perlite, glass balloons, fly ash balloons, alumina balloons, zirconia balloons, and carbon balloons; phenolic resin balloons, epoxy resin balloons, etc. Examples of suitable fillers include organic resin hollow bodies (plastic balloons) such as silicon resin balloons, urea resin balloons, polyvinylidene chloride resin balloons, polyvinylidene chloride-(meth)acrylic resin balloons, polystyrene balloons, polymethacrylate balloons, polyvinyl alcohol balloons, styrene-(meth)acrylic resin balloons, and polyacrylonitrile balloons; powdery fillers such as resin beads, wood flour, pulp, cotton chips, mica, walnut flour, rice flour, graphite, fine aluminum powder, and flint powder; and fibrous fillers such as glass fiber, glass filament, carbon fiber, Kevlar fiber, and polyethylene fiber. Among these, calcium carbonate surface-treated with a fatty acid or the like is preferred from the viewpoint of dispersibility, and plastic balloons such as polystyrene balloons are preferred from the viewpoint of reducing specific gravity and providing heat insulation.
The filler may be used alone or in combination of two or more kinds.

The content of the filler in the composition of the present invention is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, per 100 parts by mass of polymer (A).

<Silica>
The composition of the present invention may further contain silica. By using silica, the coatability of the curable composition is improved, and a cured product having excellent weather resistance and elongation can be obtained.

Examples of silica include fumed silica, and examples of silica include hydrophobic silica and hydrophilic silica, with hydrophobic silica being preferred.
Silica may be used alone or in combination of two or more kinds.

In one embodiment, the content of silica in the composition of the present invention is preferably 1 to 1,000 parts by mass, more preferably 5 to 500 parts by mass, per 100 parts by mass of polymer (A).

Pigments
The composition of the present invention may further contain a pigment.
Examples of pigments include inorganic pigments such as iron oxide, chromium oxide, titanium oxide, and cobalt aluminate, and organic pigments such as phthalocyanine blue and phthalocyanine green. The use of pigments is preferred from the viewpoint of improving color matching and weather resistance.
One or more pigments can be used.
In one embodiment, the content of the pigment in the composition of the present invention is preferably 1 to 200 parts by mass, more preferably 3 to 100 parts by mass, based on 100 parts by mass of the polymer (A).

<Fiber>
The composition of the present invention may further contain fibers.
Examples of fibers include inorganic fibers such as glass fibers and boron fibers, and organic fibers such as carbon fibers, aramid fibers, polyethylene fibers, and Zylon fibers. The use of fibers is preferred from the viewpoint of improving the strength of the cured product.
One or more types of fibers can be used.
In one embodiment, the content of the pigment in the composition of the present invention is preferably 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass, based on 100 parts by mass of the polymer (A).

<Anti-aging agent>
The composition of the present invention may further contain an anti-aging agent such as an ultraviolet absorber, a light stabilizer, or an antioxidant.
Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers, with benzotriazole-based ultraviolet absorbers being preferred. Examples of the benzotriazole-based ultraviolet absorber include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, a reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate with polyethylene glycol, and 2-(2H-benzotriazol-2-yl)-p-cresol.

Examples of light stabilizers include hindered amine light stabilizers. Examples of hindered amine light stabilizers include bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, and 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine).

Examples of antioxidants include hindered phenol antioxidants, monophenol antioxidants, bisphenol antioxidants, polyphenol antioxidants, and phosphorus-based antioxidants.

The antioxidants may be used alone or in combination.
In one embodiment, the content of the antioxidant in the composition of the present invention is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the polymer (A).

Dehydrating agent
To further improve the storage stability, the composition of the present invention may contain a small amount of a dehydrating agent within a range that does not adversely affect the curing properties or flexibility.
Examples of dehydrating agents include hydrolyzable organosilicon compounds such as methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, and vinyltrimethoxysilane; alkyl orthoformates such as methyl orthoformate and ethyl orthoformate; alkyl orthoacetates such as methyl orthoacetate and ethyl orthoacetate; and isocyanate compounds such as p-toluenesulfonyl isocyanate.

In one embodiment, the content of the dehydrating agent in the composition of the present invention is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the polymer component, from the viewpoint of the storage stability and curability of the curable composition. The polymer component may also include polymer (F) in addition to polymer (A).

<Tackifying resin>
The composition of the present invention may further contain a tackifying resin.
A cured product containing a tackifier resin has appropriate tackiness, and a pressure-sensitive adhesive layer with excellent shear adhesive strength can be obtained.

Examples of tackifying resins include rosin-based tackifying resins such as rosin ester-based resins, terpene-based tackifying resins such as terpene-phenol-based resins, styrene-based tackifying resins, and alicyclic saturated hydrocarbon resins.

Rosin ester resins are resins obtained by esterifying rosin resins with alcohols. Examples of rosin resins include rosin resins, disproportionated rosin resins, and hydrogenated rosin resins, which are primarily composed of resin acids such as abietic acid, as well as dimers of resin acids such as abietic acid (polymerized rosin resins). Examples of alcohols include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol.

A resin obtained by esterifying rosin resin is a rosin ester resin, a resin obtained by esterifying disproportionated rosin resin is a disproportionated rosin ester resin, a resin obtained by esterifying hydrogenated rosin resin is a hydrogenated rosin ester resin, and a resin obtained by esterifying polymerized rosin resin is a polymerized rosin ester resin.

The terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol.
Examples of disproportionated rosin ester resins include Superester A75 (10 or less), Superester A100 (10 or less), Superester A115 (20 or less), and Superester A125 (20 or less). Examples of polymerized rosin ester resins include Pencel D-125 (10 to 16), Pencel D-135 (10 to 16), and Pencel D-160 (10 to 16). The above products are manufactured by Arakawa Chemical Industries, Ltd., and the numbers in parentheses indicate acid values (mgKOH/g).

Examples of terpene-based tackifying resins include YS Polystar T30 (1 or less), YS Polystar T80 (1 or less), YS Polystar T130 (1 or less), Clearon 100 (1 or less), and Clearon 110 (1 or less). The above products are manufactured by Yasuhara Chemical, and the numbers in parentheses are acid values (mgKOH/g).

Examples of styrene-based tackifying resins include FMR-0150 (0.1 or less), FTR-6100 (0.1 or less), FTR-6110 (0.1 or less), FTR-6125 (0.1 or less), FTR-7100 (0.1 or less), FTR-8120 (0.1 or less), FTR-0100 (0.1 or less), FTR-2120 (0.1 or less), and FTR-2140 (0.1 or less). The above products are manufactured by Mitsui Chemicals, and the numbers in parentheses are acid values (mgKOH/g). Another example is SX-100 (1 or less), manufactured by Yasuhara Chemical.

Examples of alicyclic saturated hydrocarbon resins include Alcon P-90, Alcon P-100, Alcon P-115, Alcon P-125, Alcon M-90, Alcon M-100, Alcon M-115, and Alcon M-135. These products are manufactured by Arakawa Chemical Industries, Ltd.

The tackifying resins may be used alone or in combination of two or more.
Among these, from the viewpoint of the storage stability of the curable composition, a tackifier resin having an acid value of 1 mgKOH/g or less is preferred, and an acid value of 0.1 mgKOH/g or less is particularly preferred. By using a tackifier resin having an acid value of 0.1 mgKOH/g or less, a curable composition having particularly excellent storage stability can be obtained. The acid value refers to the number of mg of potassium hydroxide required to neutralize 1 g of tackifier resin, and can be measured according to JIS K0070.

The composition of the present invention preferably contains 1 to 900 parts by mass, more preferably 5 to 500 parts by mass, of a tackifier resin per 100 parts by mass of polymer (A). In this embodiment, the pressure-sensitive adhesive layer has appropriate tackiness and excellent adhesive strength to various substrates.

<Rheology control agent>
The composition of the present invention may further contain a rheology control agent. The rheology control agent can improve the smoothness of the film surface. As the rheology control agent, acrylic, urea, urethane, amide, polyester, layered inorganic compound rheology control agents, etc. can be used. Among these, polyester-based rheology control agents, such as "BYK R606 (polyhydroxycarboxylic acid ester)" manufactured by BYK Japan, are preferred.

The composition of the present invention preferably contains 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, of the rheology control agent per 100 parts by mass of polymer (A). In this embodiment, a curable composition with excellent thixotropy and pseudoplasticity can be obtained.

[Two-component curable composition]
[0023] A two-component curable composition according to another embodiment of the present invention comprises a first part containing a (meth)acrylic polymer (A), a salt compound (B), and a polymerization initiator, and a second part containing a reducing agent. In the present invention, the two-component curable composition refers to a combination of the first part and the second part, i.e., the composition before the first part and the second part are mixed.

<First agent>
The two-component curable composition of the present invention may contain one or more polymers (A) in the first part. By containing the polymer (A) in the first part, a two-component curable composition having excellent adhesiveness can be obtained.
The two-part curable composition of the present invention may contain one or more salt compounds (B) in the first part. By containing the salt compound (B) in the first part, a two-part curable composition having excellent storage stability can be obtained.
In one embodiment, the content of the salt compound (B) in the two-component curable composition of the present invention is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, based on 100 parts by mass of the polymer (A).

<Polymerization initiator>
The two-component curable composition of the present invention may contain one or more polymerization initiators in the first part.
The polymerization initiator is preferably a peroxide initiator, such as those described in the section on the production of polymer (A).
In one embodiment, the content of the polymerization initiator in the two-component curable composition of the present invention is preferably 0.01 to 2,000 parts by mass, more preferably 0.1 to 1,000 parts by mass, based on 100 parts by mass of the polymer (A).

<Second agent>
The two-part curable composition of the present invention may contain one or more reducing agents in the second part.

<Reducing agent>
Any known reducing agent that reacts with the polymerization initiator to generate radicals can be used as the reducing agent, and examples thereof include tertiary amines, thiourea derivatives, and transition metal salts.

Examples of tertiary amines include triethylamine, tripropylamine, tributylamine, and N,N-dimethyl-paratoluidine.

Examples of thiourea derivatives include 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, tetramethylthiourea, and ethylenethiourea.

Examples of transition metal salts include cobalt naphthenate, copper naphthenate, cobalt octenate, copper acetylacetonate, vanadyl acetylacetonate, vanadium acetylacetonate, etc. Among these, transition metal salts are preferred in terms of reactivity, and vanadyl acetylacetonate is more preferred.
In one embodiment, the content of the reducing agent in the two-component curable composition of the present invention is preferably 0.001 to 500 parts by mass, more preferably 0.01 to 100 parts by mass, based on 100 parts by mass of the polymer (A).

The two-part curable composition of the present invention may further contain an epoxy resin (C) and/or a (meth)acrylic monomer. The epoxy resin (C) and/or the (meth)acrylic monomer may be contained in both the first and second parts, or each may be independently contained in one of them. The epoxy resin (C) and the (meth)acrylic monomer may be used alone, or two or more types may be used.

(Meth)acrylic monomer
Examples of the (meth)acrylic monomer include:
oxygen-containing (meth)acrylic monomers such as tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, methoxyethyl (meth)acrylate, and (3-ethyloxetan-3-yl)methyl (meth)acrylate;
nitrogen-containing (meth)acrylic monomers such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethyl (meth)acrylamide, and (meth)acryloylmorpholine;
Sulfur-containing (meth)acrylic monomers such as 2-methylthioethyl (meth)acrylate;
Monofunctional (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and isobornyl (meth)acrylate; pentaerythritol di(meth)acrylate; and (meth)acrylic acid esters such as polyfunctional (meth)acrylates, such as acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate.

In one embodiment, the content of the (meth)acrylic monomer in the two-component curable composition of the present invention is preferably 1 to 100,000 parts by mass, more preferably 10 to 10,000 parts by mass, per 100 parts by mass of polymer (A).

When storing a two-part curable composition, the first and second parts are separated, with the first part containing at least a polymerization initiator and the second part containing at least a reducing agent. In this case, the two parts can be applied simultaneously or separately, brought into contact, and cured to be used as a two-part curable composition.

[Uses of curable composition and cured product]
The composition of the present invention contains a polymer (A) and a salt compound (B) composed of an acid and a base that satisfy a predetermined pKa, and therefore can be cured under a desired thermal environment, and has excellent storage stability and mechanical properties.
Furthermore, since the composition of the present invention has good crosslinkability, it can be used in applications where it is cured by crosslinking, or in applications where the elasticity of the cured product is utilized, etc. It is thought that in the composition, due to moisture present in the atmosphere or in the adherend to which the curable composition is applied, for example, the group represented by formula (1) in polymer (A), and, when polymer (F) is used, the group represented by formula (1) in polymer (F), are hydrolyzed to form silanol groups, and then the silanol groups undergo dehydration condensation with each other to form siloxane bonds, thereby curing and forming a cured product.

The composition of the present invention or the two-component curable composition obtained by mixing and stirring is suitable for use as a sealant, adhesive, hot melt adhesive, or paint, for example, in construction and building material applications, automotive applications, etc. Other examples include coating agents for covering the surfaces of inorganic materials (e.g., cement, mortar, metal, and glass), sheet-forming compositions (examples of sheets: breathable sheets, protective sheets, water-shielding sheets, vibration-damping sheets, transfer sheets, light-modulating sheets, antistatic sheets, conductive sheets, protective sheets, sound-insulating sheets, light-blocking sheets, decorative sheets, marking sheets, and flame-retardant sheets), film-forming compositions (examples of films: marking films, protective films, ink-fixing films, and laminate films), foam-forming compositions (examples of foams: rigid foams, flexible foams, semi-rigid foams, and flame-retardant foams), compositions for forming vibration-damping materials, sound-insulating materials, sound-proofing materials, sound-absorbing materials, artificial leather, artificial skin, synthetic leather, various industrial parts, daily necessities, and molded toiletry products, paint vehicles, primer resins, and various binders (e.g., ink binders, binders for magnetic recording media, binders for casting, binders for fired bodies, and binders for glass fiber sizing materials).

The cured product of the present invention can be obtained from the curable composition or two-component curable composition of the present invention. The curing conditions are not particularly limited, but in the case of a curable composition (e.g., a one-component curable composition), curing can be favorably promoted by applying the composition of the present invention to a support and leaving it in an environment of 100 to 200°C, preferably 120 to 180°C, for a predetermined period of time. In the case of a two-component curable composition, a cured product can be obtained by applying the composition of the present invention to a support in any desired ratio.

The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples. In the following descriptions of the examples and comparative examples, "parts" refers to "parts by mass" unless otherwise specified.

[Polymer evaluation method]
The methods for evaluating the various physical properties of the polymer are described below.
<Number average molecular weight (Mn) and weight average molecular weight (Mw)>
The number average molecular weight (Mn) and weight average molecular weight (Mw) of each polymer were analyzed by gel permeation chromatography (GPC) and calculated in terms of polystyrene under the following conditions.
Apparatus: GPC-8220 (manufactured by Tosoh)
・Column: G7000HXL/7.8mm ID x 1 +
GMHXL/7.8mm ID x 2 +
G2500HXL/7.8 mm ID x 1 Medium: tetrahydrofuran Flow rate: 1.0 mL/min
・Concentration: 1.5mg/ml
・Injection volume: 300μL
Column temperature: 40°C

<Glass transition temperature (Tg)>
The glass transition temperature (Tg) of each polymer was measured by differential scanning calorimetry (DSC).
・Device: DSC7000X (Hitachi High-Tech Science)
Temperature conditions: -100°C to 30°C at a rate of 10°C/min. Sample container: Aluminum open cell. Sample amount: 5 mg.

<Silicon element content>
The silicon content of each polymer was measured by adding 7 mL of mixed acid containing hydrogen fluoride to 0.2 g of the polymer, wet ashing using a microwave decomposition apparatus (manufactured by Anthol Japan), adding ultrapure water to the ashed sample to make a constant volume of 50 mL, and then using an inductively coupled plasma atomic emission spectrometer (ICP-AES).
・Device: ICPE-9000 (Shimadzu Corporation)
High frequency power: 1.20 kW
Plasma gas: 10.00 L/min
Auxiliary gas: 0.60 L/min
Carrier gas: 0.70 L/min
Observation direction: Axial direction

[Production Example 1]
A stainless steel flask equipped with a stirrer, nitrogen gas inlet tube, thermometer, and reflux condenser was charged with 70 parts of n-butyl acrylate, 25 parts of 2-ethylhexyl acrylate, and 5 parts of acryloxymethyltrimethoxysilane. After nitrogen substitution, the temperature was raised to 70°C. Next, while maintaining the contents of the flask at 75°C, 4.5 parts of 3-mercaptopropyltrimethoxysilane was added, followed by the addition of 0.05 parts of 2,2'-azobisisobutyronitrile (AIBN) to initiate the reaction. Three hours after the start of the reaction, 0.05 parts of AIBN was added. Six hours after the start of the reaction, volatile components were distilled off under reduced pressure at 110°C for 3 hours to obtain (meth)acrylic polymer (A-1). The silicon content of polymer (A-1) was 8,850 ppm, Mn was 8,000, Mw was 13,000, and Tg was -67°C.

[Production Examples 2 to 4]
The same procedures as in Production Example 1 were carried out except that the raw material components used were changed as shown in Table 1, thereby obtaining (meth)acrylic polymers (A-2), (A-3), and (cA-1).

[Example 1: Preparation of one-component curable composition]
100 parts of (meth)acrylic polymer (A-1), 10 parts of DBU-o-phthalate salt [pKa(H ₂ O): DBU = 12, o-phthalic acid = 2.9] "U-CAT SA 810" (manufactured by San-Apro) as salt compound (B), 200 parts of bisphenol A epoxy resin "jER828" and 200 parts of "jER1001" (both manufactured by Mitsubishi Chemical Corporation) as epoxy resin (C), and 0.5 parts of phenolic antioxidant "ADK STAB AO-80" (manufactured by ADEKA) were charged into a stainless steel flask and stirred for 10 minutes under a 90°C environment. After cooling to room temperature, 10 parts of vinyltrimethoxysilane "KBM-1003" (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a dehydrating agent and mixed for 10 minutes to obtain a curable composition.
The resulting curable composition was subjected to various evaluations.

[Examples 2 to 5, Comparative Examples 1 to 5]
Curable compositions were obtained and various evaluations were carried out in the same manner as in Example 1, except that the blending compositions were changed as shown in Table 2. The evaluation methods will be described later.
[Example 6: Preparation of two-component curable composition]
100 parts of (meth)acrylic polymer (A-1), 20 parts of "U-CAT SA 506", 400 parts of tetrahydrofurfuryl acrylate, and 20 parts of thermal polymerization initiator "Percumyl H-80" (manufactured by NOF Corp.) were placed in a stainless steel flask and stirred for 10 minutes to prepare agent I. Next, 500 parts of tetrahydrofurfuryl acrylate and 2.5 parts of reducing agent "vanadyl acetylacetate 50D" (manufactured by Shinko Chemical Industry Co., Ltd.) were placed in another stainless steel flask and stirred for 10 minutes to prepare agent II. Various evaluations were performed on the obtained agent I, as well as on a mixture obtained by mixing agent I and agent II.

[Examples 7 and 8, Comparative Examples 6 to 9]
Agents I and II were prepared in the same manner as in Example 6, except that the blending compositions were changed as shown in Table 3. Various evaluations were performed on the obtained agent I and on a mixture of agent I and agent II.

In Tables 2 and 3, "-" indicates that the curable composition cured or did not cure during preparation and therefore could not be evaluated.

The meanings of the symbols for each component in Tables 2 and 3 are as follows:
U-CAT SA 810: DBU-o-phthalic acid salt [pKa (H ₂ O): DBU=12 (same below), o-phthalic acid=2.9] (manufactured by San-Apro)
U-CAT SA 506: DBU-paratoluenesulfonate [pKa(H ₂ O)=paratoluenesulfonic acid=2.4] (manufactured by San-Apro)
U-CAT SA 603: DBU-formate [pKa (H ₂ O): formic acid=3.8] (manufactured by San-Apro)
U-CAT SA 102: DBU-octylate [pKa (H ₂ O): octylate = 4.8] (manufactured by San-Apro)
jER828: Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical, epoxy equivalent: 184-194)
jER1001: Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical, epoxy equivalent: 450-500)
KBM-1003: Vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
・ADK STAB AO-80: Phenolic antioxidant (manufactured by ADEKA)
THFA: Tetrahydrofurfuryl acrylate Percumyl H-80: Cumene hydroperoxide (manufactured by NOF Corp.)
Vanadyl acetyl acetate 50D: Vanadyl acetyl acetate (manufactured by Shinko Chemical Industry Co., Ltd.)

[Method for evaluating curable compositions]
The methods for evaluating the various physical properties of the curable composition are described below.
<Pot life of one-component curable composition>
The curable compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were left in an environment at 23° C., and the number of days until a film was formed was measured.
<Pot life of component I in two-component curable composition>
The I agents prepared in Examples 6 to 8 and Comparative Examples 6 to 9 were left in an environment at 23° C., and the time until a film was formed was measured.

<Curing time>
Five grams of each of the curable compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 5 was transferred to a metal container (33 mm diameter, 13 mm height). The metal container containing the curable composition was then left in an environment at 140°C, and the time until a coating was formed was measured.

<Shear adhesive strength, cohesive failure rate, shear adhesive strength change rate>
The curable compositions obtained in the Examples and Comparative Examples were applied to two test pieces made of stainless steel 304 (1 mm thick) in accordance with JIS-K6850:1999 (Testing method for tensile shear bond strength between adhesives and rigid adherends), and the pieces were laminated together so that the thickness of the curable composition layer was 0.2 mm. The one-component compositions shown in Table 2 were heated at 140°C for 1 hour, while the two-component curable compositions shown in Table 3 were not heated. The shear adhesive strength was measured in accordance with JIS K6850:1999 using a universal tensile tester AG-X (manufactured by Shimadzu Corporation) at a tensile speed of 50 mm/min and 23°C.
The cohesive failure rate (the ratio of the cohesive failure area to the total adhesion area) was also measured.
The rate of change in shear adhesive strength was calculated by the following formula using the shear adhesive strength of a test piece obtained without heating (shear adhesive strength before heating) and the shear adhesive strength after heating at 120°C for 1 hour (shear adhesive strength after heating) for the two-component curable composition shown in Table 3.
[(Shear adhesive strength after heating) - (Shear adhesive strength before heating)] ÷ (Shear adhesive strength before heating) × 100
The rate of change in shear adhesive strength is an index showing the extent to which curing of the alkoxysilyl group is completed due to the heat of polymerization generated when component I and component II are brought into contact with each other, and a smaller rate of change means that there is less uncured component.

Claims (7)

a (meth)acrylic polymer (A) having a group represented by formula (1) and containing 1,500 ppm or more of silicon element;
A curable composition comprising a salt compound (B) composed of an acid having an acid dissociation constant (pKa) of less than 3.5 and a base having a pKa of 10 or more ,
the (meth)acrylic polymer (A) has a structural unit derived from a monomer (a2) represented by formula (a2-1),
the salt compound (B) is a salt compound composed of an organic acid having a pKa of 1 or more and less than 3.5 and an organic base having a pKa of 10 or more and less than 15,
The curable composition, wherein the organic base is 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) .
Formula (1): -X-CH ₂ -SiR ¹ ₃
[In formula (1), R ^1s are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and at least one of the R ^1s is the alkoxy group or hydroxyl group; X is a divalent group represented by -O-, -COO-, -S-, -N(R ² )-, -CH(OH)-CH ₂ -O-, -O-CO-NH-, or -N(R ² )-CO-N(R ³ )-, and R ² and R ³ are a hydrogen atom, a hydrocarbon group, or a halogenated hydrocarbon group, and R ² and R ³ may be the same or different.]
[In formula (a2-1), R ^a represents a hydrogen atom or a methyl group, and R ¹ has the same meaning as R ¹ in formula (1) ] The curable composition according to claim 1, comprising 0.01 to 50 parts by mass of the salt compound (B) per 100 parts by mass of the (meth)acrylic polymer (A). The curable composition according to claim 1, wherein the (meth)acrylic polymer (A) has a group represented by formula (1) at least at the molecular chain terminal. The curable composition according to claim 1, wherein the number average molecular weight (Mn) of the (meth)acrylic polymer (A) is 1,000 to 100,000. The curable composition according to claim 1, containing 1 to 1,000 parts by mass of epoxy resin (C) per 100 parts by mass of the (meth)acrylic polymer (A). A cured product obtained from the curable composition according to any one of claims 1 to 5 . A two-component curable composition comprising a first part containing the curable composition according to any one of claims 1 to 5 and a polymerization initiator, and a second part containing a reducing agent.