JP7752174B2 - Curable composition and cured product - Google Patents

Description

The present invention relates to a curable composition and a cured product.

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 a polyoxyalkylene polymer or (meth)acrylic polymer having a reactive silicon group of a specific structure, it is possible to obtain a curable composition that has fast curing properties and excellent adhesive properties and storage stability (see, for example, Patent Documents 1 to 3).

JP 2012-136685 A JP 2014-101499 A JP 2010-202863 A

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 composition described in Patent Document 1 above contains a tin compound as a condensation catalyst. On the other hand, the curable compositions described in Patent Documents 2 and 3 are characterized by their ability to cure well without the use of a tin-based compound. However, the curable composition disclosed in Patent Document 2 has a highly reactive polymer containing a silyl group represented by a specific formula, and the reaction proceeds even in the presence of moisture in the air. This requires storage in an airtight container that blocks air. Furthermore, after removal from the storage container, the curable composition must be used up or discarded, resulting in poor storage stability.

The object of the present invention is to provide a curable composition that cures quickly without the use of a tin-based curing catalyst and can form a cured product with excellent storage stability and mechanical properties, or a curable composition with excellent adhesive properties.

The present invention relates to, for example, the following [1] to [7].

[1] A (meth)acrylic polymer (A) having a group represented by formula (1), having a number average molecular weight (Mn) of 1,000 or more, and containing 500 ppm or more of silicon element;
A curable composition containing a silane coupling agent (B) represented by formula (2) and having a molecular weight of less than 1,000.

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.]
Formula (2): Y-CH ₂ -SiR ¹ ₃
[In formula (2), ^R1 has the same meaning as in formula (1); and Y represents a (meth)acryloyl group, an alkoxy group having 1 to 20 carbon atoms, a mercapto group, or an isocyanate group.]
[2] The curable composition according to [1], comprising 0.1 to 20 parts by mass of (B) relative to 100 parts by mass of the (meth)acrylic polymer (A).

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

[4] The curable composition described in any one of [1] to [3], wherein the glass transition temperature (Tg) of the (meth)acrylic polymer (A) is −20°C or lower.

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

[6] The curable composition according to any one of [1] to [5], containing 0.05 to 10 parts by mass of an aminosilane compound (C) represented by the following formula (3) per 100 parts by mass of the (meth)acrylic polymer (A):

Formula (3): R ⁴ ₂ -N-(CH ₂ ) _n -SiR ¹ ₃
[In formula (3), n is an integer of 1 to 6; ^R1 has the same meaning as in formula (1); and ^R4s each independently represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a group in which at least one hydrogen atom of the hydrocarbon group has been substituted with a group selected from the group consisting of an unsubstituted amino group, a substituted amino group, and an alkoxysilyl group.]
[7] A cured product obtained from the curable composition according to any one of [1] to [6].

The present invention provides a curable composition that can be cured without the use of a tin-based curing catalyst to form a cured product with excellent storage stability and mechanical properties, or a curable composition that has excellent adhesion even after long-term storage.

The present invention will now be described in detail.

The curable composition of the present invention (hereinafter also referred to as the "composition of the present invention") contains a (meth)acrylic polymer (A) and a silane coupling agent (B), as described below.

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), having a number average molecular weight (Mn) of 1,000 or more, and containing 500 ppm or more of silicon element.

Formula (1): -X-CH ₂ -SiR ¹ ₃
In formula (1), ^R1 's 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 ^R1 's is the alkoxy group or hydroxyl group; X is a divalent group represented by -O-, -COO-, -S-, -N( ^R2 )-, -CH(OH) _-CH2 -O-, -O-CO-NH-, or -N( ^R2 )-CO-N( ^R3 )-, and ^R2 and ^R3 are hydrogen atoms, hydrocarbon groups, or halogenated hydrocarbon groups, and ^R2 and ^R3 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 standpoint of curability and mechanical properties, polymer (A) has a group represented by formula (1) and contains 500 ppm or more, preferably 1,000 to 20,000 ppm, and more preferably 1,500 to 10,000 ppm of silicon element. Note that "ppm" means wt ppm. 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-chain or branched.

Examples of 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.

Monomer (a1) can be used alone or in combination.

The proportion of monomer (a1) in the polymerizable monomer components constituting polymer (A) is preferably 20% by mass or more, more preferably 20 to 85% by mass, even more preferably 20 to 75% by mass, and particularly preferably 22 to 55% by mass. Polymer (A) may contain structural units derived from monomer (a1) in a similar range among all structural units. Using a (meth)acrylic acid alkyl ester (a1) in which the alkyl group has 8 to 12 carbon atoms in the above range can produce a (meth)acrylic polymer with excellent mechanical properties.

<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 monomer (a2), for example, a compound represented by formula (a2-1) is preferred.

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.

Monomer (a2) can be used alone or in combination.

The proportion of monomer (a2) in the polymerizable monomer components constituting polymer (A) is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass. Polymer (A) may contain structural units derived from monomer (a2) in a similar range among all structural units. Using monomer (a2) in the above range allows the introduction of a group represented by formula (1) into polymer (A). Therefore, the resulting polymer (A) has adequate crosslinkability and is suitable for applications involving the formation of crosslinked products.

<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.

Other monomers (a3) can be used alone or in combination.

The proportion of the other monomer (a3) in the polymerizable monomer components constituting polymer (A) is preferably 1 to 65% by mass, and more preferably 5 to 60% by mass. Polymer (A) may contain structural units derived from the other monomer (a3) in a similar range among all structural units.

<Mercapto Group-Containing Compound (d)>
In producing the polymer (A), a mercapto group-containing compound (d) may be used as a chain transfer agent.

Mercapto group-containing compound (d) functions as a chain transfer agent due to its functional group (-SH) with high chain transfer properties in radical polymerization. When polymerizable monomer components are polymerized in the presence of mercapto group-containing compound (d), a structural unit derived from 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 mercapto group-containing compound (d) represented by formula (1) into a polymer having a polymerizable unsaturated group via an ene-thiol reaction, the group represented by formula (1) can also be introduced into the polymer. Curable compositions using polymer (A) having a group represented by formula (1) at the molecular chain terminal exhibit excellent mechanical properties.

When monomer (a2) is used, the group represented by formula (1) in monomer (a2) and the group represented by formula (1) in mercapto group-containing compound (d) may be the same or different.

As the mercapto group-containing compound (d), a compound represented by formula (d-1) is preferred.

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, 2-mercaptoethanol, 3-mercapto-1,2-propanediol, 2,2-mercaptopropyl dimethyl methoxysilane, mercaptopropyl dimethyl ethoxysilane, mercaptopropyl methyl dimethoxysilane, mercaptopropyl methyl diethoxysilane, mercaptopropyl trimethoxysilane, and mercaptopropyl triethoxysilane.

Compound (d) can be used in one or more types.

The mercapto group-containing compound (d) is preferably used in the range of 0.1 to 5 parts by mass, and more preferably 0.2 to 3 parts by mass, per 100 parts by mass of the total polymerizable monomer components. In this embodiment, the number average molecular weight of 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 a monomer (a1) having the above-mentioned (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 (e.g., a hydroxy group, an isocyanate group, or an amino group) and a monomer component including 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 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
R ¹ has the same meaning as the same symbol in formula (1), and R ⁴ is 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 compound (e-2) include aminomethyltrimethoxysilane, aminomethyltriethoxysilane, (aminoethylamino)methyltrimethoxysilane, (N,N-dimethylamino)ethylaminomethyltrimethoxysilane, and glycidyloxymethyltrimethoxysilane.

Compound (e) can be used alone or in combination.

Compound (e) 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 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 hydroxide, 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)propanol. 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.

A single photoradical polymerization initiator may be used, or two or more types may be used.

The photoradical polymerization initiator may be combined with a sensitizer. Preferred sensitizers include anthracene-based compounds such as 9,10-dibutoxyanthracene and 9,10-bis(acyloxy)anthracene.

One or more polymerization initiators can be used.

The polymerization initiator may be added in multiple increments.

The amount of polymerization initiator used is typically 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 this range, the number average molecular weight of polymer (A) can be adjusted to an appropriate range.

Organic solvents are preferred as polymerization solvents. Examples of organic solvents 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.

One or more polymerization solvents can be used.

<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 40,000 or less, from the viewpoint of the viscosity of the polymer.

Number average molecular weight (Mn) is measured by gel permeation chromatography (GPC).

The glass transition temperature (Tg) of polymer (A) is preferably -20°C or lower, more preferably -90 to -25°C, and even more preferably -80 to -30°C. This embodiment is preferred from the viewpoint of low viscosity and excellent handleability. Tg is determined by differential scanning calorimetry (DSC).

Details of the GPC and DSC measurement conditions are 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 a total of 5% by mass or more of polymer (A), more preferably 8 to 95% by mass, and even more preferably 10 to 90% by mass.

[Silane coupling agent (B)]
The composition of the present invention contains a silane coupling agent (B) in addition to the polymer (A).

The silane coupling agent (B) acts as a dehydrating agent in the composition of the present invention.

Because polymer (A) contains a group represented by formula (1), the composition of the present invention cures without the use of a tin-based curing catalyst. However, polymer (A) containing a group represented by formula (1) is highly reactive on its own, and the reaction proceeds even in the presence of moisture in the air. Therefore, by including silane coupling agent (B) represented by formula (2) in the curable composition, the reaction of polymer (A) is suppressed, resulting in a curable composition that has excellent storage stability and excellent adhesion even after long-term storage.

The dehydrating effect of the silane coupling agent (B) is exerted by combining a polymer (A) having a group represented by formula (1) with a polymer (B) having a group represented by formula (2).

The silane coupling agent (B) is represented by formula (2).

Formula (2): Y-CH ₂ -SiR ¹ ₃
In formula (2), R ¹ has the same meaning as in formula (1); Y is a (meth)acryloyl group, an alkoxy group having 1 to 20 carbon atoms, a mercapto group, or an isocyanate group.

Examples of the alkoxy group having 1 to ₂₀ carbon atoms and the group represented by ^--SiR.sup.13 include the same groups as those described in the section on polymer (A).

In the silane coupling agent (B), examples of silane coupling agents in which Y is a (meth)acryloyl group include (meth)acryloxymethyldimethylmethoxysilane, (meth)acryloxymethyldimethylethoxysilane, ((meth)acryloxymethyl)methyldimethoxysilane, ((meth)acryloxymethyl)methyldiethoxysilane, (meth)acryloxymethyltrimethoxysilane, and (meth)acryloxymethyltriethoxysilane.

In the silane coupling agent (B), examples of silane coupling agents in which Y is an alkoxy group having 1 to 20 carbon atoms include methoxymethyltrimethoxysilane, ethoxymethyltrimethoxysilane, n-propyloxymethyltrimethoxysilane, isopropyloxymethyltrimethoxysilane, n-butyloxymethyltrimethoxysilane, isobutyloxymethyltrimethoxysilane, n-pentyloxymethyltrimethoxysilane, isopentyloxymethyltrimethoxysilane, neopentyloxymethyltrimethoxysilane, n-hexyloxymethyltrimethoxysilane, 1- Methylpentyloxymethyltrimethoxysilane, 4-methyl-2-pentyloxymethyltrimethoxysilane, 3,3-dimethylbutyloxymethyltrimethoxysilane, 2-ethylbutyloxymethyltrimethoxysilane, n-heptyloxymethyltrimethoxysilane, 1-methylhexyloxymethyltrimethoxysilane, n-octyloxymethyltrimethoxysilane, isooctyloxymethyltrimethoxysilane, 1-methylheptyloxymethyltrimethoxysilane, 2-ethylhexyloxymethyltrimethoxysilane, 2-propylpentyloxymethyltrimethoxysilane, n-Nonyloxymethyltrimethoxysilane, 2,2-dimethylheptyloxymethyltrimethoxysilane, 2,6-dimethyl-4-heptyloxymethyltrimethoxysilane, 3,5,5-trimethylhexyloxymethyltrimethoxysilane, n-Decyloxymethyltrimethoxysilane, n-Undecyloxymethyltrimethoxysilane, 1-Methyldecyloxymethyltrimethoxysilane, n-Dodecyloxymethyltrimethoxysilane, n-Tridecyloxymethyltrimethoxysilane, 1-Hexylheptyloxymethyltrimethoxysilane, n-Tetradecyloxymethyltrimethoxysilane Examples thereof include methoxysilane, n-pentadecyloxymethyltrimethoxysilane, n-hexadecyloxymethyltrimethoxysilane, n-heptadecyloxymethyltrimethoxysilane, n-octadecyloxymethyltrimethoxysilane, n-eicosyloxymethyltrimethoxysilane, and compounds in which the trimethoxysilyl group in these silyl groups is substituted with a dimethylmethoxysilyl group, a dimethylethoxysilyl group, a methyldimethoxysilyl group, a methyldiethoxysilyl group, a triethoxysilyl group, a dimethylisopropoxysilyl group, a methyldiisopropoxysilyl group, a triisopropoxysilyl group, etc. Among these, methoxymethyltrimethoxysilane, ethoxymethyltrimethoxysilane, n-propyloxymethyltrimethoxysilane, isopropyloxymethyltrimethoxysilane, n-butyloxymethyltrimethoxysilane, and isobutyloxymethyltrimethoxysilane are preferred.

In the silane coupling agent (B), examples of silane coupling agents in which Y is a mercapto group include mercaptomethyldimethylmethoxysilane, mercaptomethyldimethylethoxysilane, mercaptomethyldimethylisopropoxysilane, mercaptomethylmethyldimethoxysilane, mercaptomethylmethyldiethoxysilane, mercaptomethylmethyldiisopropoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, and mercaptomethyltriisopropoxysilane. Among these, mercaptomethyldimethylmethoxysilane, mercaptomethylmethyldimethoxysilane, mercaptomethyltrimethoxysilane, and mercaptomethyltriethoxysilane are preferred.

In the silane coupling agent (B), examples of silane coupling agents in which Y is an isocyanate group 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.

When monomer (a2) and/or mercapto compound (d) are used in producing polymer (A), silane coupling agent (B) may be the same as or different from monomer (a2) and/or mercapto compound (d).

<Physical Properties of Silane Coupling Agent (B)>
The molecular weight of the silane coupling agent (B) has a lower limit of preferably 80 or more, more preferably 100 or more, and even more preferably 120 or more, and an upper limit of less than 1,000, preferably 750 or less, and more preferably 500 or less.

<Content of Silane Coupling Agent (B)>
The composition of the present invention may contain one or more silane coupling agents (B).

The composition of the present invention preferably contains 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass of the silane coupling agent (B) in total per 100 parts by mass of the polymer (A). When the content of the silane coupling agent (B) is within the above range, a curable composition having excellent storage stability and excellent adhesion even after long-term storage can be obtained.

[Aminosilane Compound (C)]
The composition of the present invention preferably contains an aminosilane compound (C) in addition to the polymer (A) and the silane coupling agent (B).

The aminosilane compound (C) acts as a curing catalyst and a dehydrating agent in the composition of the present invention.

The aminosilane compound (C) has a group represented by the following formula (3):

Formula (3): R ⁴ ₂ -N-(CH ₂ ) _n -SiR ¹ ₃
[In formula (3), n is an integer of 1 to 6; ^R1 has the same meaning as in formula (1); and each ^R4 is independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a group in which at least one hydrogen atom of the hydrocarbon group has been substituted with a group selected from the group consisting of an unsubstituted amino group, a substituted amino group, and an alkoxysilyl group.]
Examples of the aminosilane compound (C) represented by formula (3) include N-(2-aminoethyl)aminomethyltrimethoxysilane, N-(2-aminoethyl)-2-aminoethyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, aminomethyltrimethoxysilane, 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, aminomethyltriethoxysilane, 2-aminoethyltriethoxysilane, 3-aminopropyltriethoxysilane, N-[2-( N,N-dimethylamino)ethyl]aminomethyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-cyclohexyl-3-aminopropylmethyldimethoxysilane, N-[2-(N-vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane, and N-[3-(trimethoxysilyl)propyl]-1-butanamine.

Among the aminosilane compounds (C), it is preferable to use an aminosilane compound represented by the following formula (3-1) from the viewpoint of improving the tack-free time of the composition of the present invention.

Formula (3-1): R ^4' -NH-(CH ₂ ) _n' -SiR ^1' ₃
In formula (3-1), n' is an integer of 1 to 3; R ^1' is an alkoxy group having 1 to 6 carbon atoms; and R ⁴ is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a group in which at least one hydrogen atom of the hydrocarbon group is substituted with at least one group selected from the group consisting of an unsubstituted amino group, a substituted amino group, and an alkoxysilyl group.

One or more aminosilane compounds (C) can be used.

The composition of the present invention preferably contains 0.05 to 10 parts by mass, more preferably 0.1 to 8 parts by mass, and even more preferably 0.5 to 5 parts by mass of aminosilane compound (C) in total per 100 parts by mass of polymer (A). When the content of aminosilane compound (C) is within the above range, a curable composition having excellent storage stability and excellent adhesion even after long-term storage can be obtained.

[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 polymer (D) having a polyether skeleton, a plasticizer, a filler, silica, a pigment, 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 imparting agent.

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

Polymer (D) 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 (D) may have a urethane skeleton between the polyether skeletons.

The number average molecular weight (Mn) of polymer (D) 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), the handleability of the curable composition, and excellent mechanical properties. The number average molecular weight (Mn) is measured by GPC.

Details of the GPC measurement conditions are described in the Examples section below.

By using polymer (D) together with polymer (A), a curable composition with excellent mechanical properties is obtained.

When polymer (D) is used, the group represented by formula (1) in polymer (A) and the group represented by formula (1) in polymer (D) may be the same or different.

In one embodiment, polymer (D) 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 the polyether polymer.

Polymer (D) 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 (D) 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 terminal isocyanate groups 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 (D) 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 (D).

The content of polymer (D) in the composition of the present invention is preferably 10 to 900 parts by mass, and more preferably 20 to 800 parts by mass, per 100 parts by mass of polymer (A). This embodiment is preferred from the viewpoint of obtaining a cured product with excellent mechanical properties.

<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, dioctyl 4,5-epoxyhexahydrophthalate, and epoxy Examples of polymer plasticizers include epoxy plasticizers such as benzyl cystearate; hydrocarbons such as chlorinated paraffin, normal paraffin, and isoparaffin; alkylsulfonic acid phenyl esters such as alkane (C=10 to 21)sulfonic acid phenyl ester; 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.

Fillers include, for example, calcium carbonate such as heavy calcium carbonate, light calcium carbonate, colloidal calcium carbonate, semi-colloidal calcium carbonate, light calcium carbonate, and calcium carbonates whose surfaces have been treated with fatty acids or resin acid organic substances; 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 Examples of suitable fillers include organic resin hollow bodies (plastic balloons) such as silicon dioxide 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 shirasu balloons, glass balloons, polystyrene balloons, and acrylic resin balloons are preferred from the viewpoint of reducing specific gravity and providing heat insulation.

One or more fillers can be used.

The content of the filler in the composition of the present invention is preferably 0.1 to 1,000 parts by mass, and more preferably 0.2 to 500 parts by mass, per 100 parts by mass of polymer (A). The present invention makes it possible to obtain a curable composition with excellent filler dispersibility.

<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. Examples of silica include hydrophobic silica and hydrophilic silica, with hydrophobic silica being preferred.

Silica can be used in combination of one or more types.

In one embodiment, the content of silica in the composition of the present invention is preferably 1 to 100 parts by mass, more preferably 3 to 50 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 standpoint 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, per 100 parts by mass of 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 UV absorbers include benzotriazole-based UV absorbers and benzophenone-based UV absorbers, with benzotriazole-based UV absorbers being preferred. Examples of benzotriazole-based UV absorbers 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, the 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.

One or more types of antioxidants can be used.

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, per 100 parts by mass of polymer (A).

<Dehydrating agent>
In order to further improve the storage stability, the composition of the present invention may contain a dehydrating agent in an amount that does not adversely affect the curing property 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, and 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 contain polymer (D) in addition to polymer (A).

<Tackifying Resin>
The composition of the present invention may further contain a tackifying resin.

Cured products containing tackifying resins have moderate tackiness and can produce adhesive layers with excellent shear adhesive strength.

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.

Terpene phenolic 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 (10-16), Pencel D-135 (10-16), and Pencel D-160 (10-16). The above products are manufactured by Arakawa Chemical Industries, Ltd., and the numbers in parentheses are 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.

Tackifying resins can be used alone or in combination of two or more.

Among these, from the perspective of storage stability of the curable composition, tackifier resins with an acid value of 1 mgKOH/g or less are preferred, and those with an acid value of 0.1 mgKOH/g or less are particularly preferred. Using a tackifier resin with an acid value of 0.1 mgKOH/g or less can produce a curable composition with particularly excellent storage stability. The acid value refers to the number of milligrams of potassium hydroxide required to neutralize 1 g of tackifier resin, and can be measured in accordance with JIS K0070.

The composition of the present invention preferably contains 1 to 500 parts by mass, more preferably 5 to 300 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.

[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.

In addition, because the composition of the present invention has good crosslinking properties, it can be used in applications where it is cured by crosslinking, or in applications where the elasticity of the cured product is utilized. It is believed that in the composition, moisture present in the atmosphere or in the adherend to which the curable composition is applied causes hydrolysis of, for example, the group represented by formula (1) in polymer (A), and, when polymer (D) is used, the group represented by formula (1) in polymer (D), to form silanol groups, which then undergo dehydration condensation with each other to form siloxane bonds, thereby curing the composition 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 composition of the present invention or a two-part curable composition. There are no particular limitations on the curing conditions, but curing can be smoothly promoted by applying the composition of the present invention to a substrate and leaving it for a predetermined period of time in an environment of, for example, -20 to 120°C and 10 to 95% RH, or preferably in an environment of 20 to 90°C and 30 to 85% RH.

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.

[Method for evaluating polymers, etc.]
The methods for evaluating the various physical properties of the polymers and the like 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 a polymer or the like 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 74 parts of n-butyl acrylate, 25 parts of 2-ethylhexyl acrylate, and 1 part of acryloxymethyltrimethoxysilane. After nitrogen substitution, the temperature was raised to 70°C. Next, while maintaining the contents of the flask at 75°C, 0.9 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 1,820 ppm, Mn was 21,000, Mw was 54,000, and Tg was -64°C.

[Example 1]
100 parts of the (meth)acrylic polymer (A-1), 170 parts of 1,2-cyclohexanedicarboxylic acid diisononyl ester "Hexamoll DINCH" (manufactured by BASF) as a plasticizer, 3 parts of polyhydroxycarboxylic acid ester "BYK R606" (manufactured by BYK) as a thixotropic agent, 10 parts of fumed silica "HDK H18" (manufactured by Wacker Asahi Kasei Co., Ltd.), and 350 parts of heavy calcium carbonate "Whiten 305" (manufactured by Toyo Fine Chemical Co., Ltd.) were mixed in a planetary centrifugal mixer (ARE-310, manufactured by Thinky Co., Ltd.) at a rotation speed of 2,000 rpm for 3 minutes. Next, 4 parts of acryloxymethyltrimethoxysilane "X-12-1169MS" (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 206) as the silane coupling agent (B) and 1 part of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane "KBM-603" (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 222) were mixed in an ARE-310 at a rotation speed of 2,000 rpm for 1 minute to obtain a curable composition.

Various evaluations were performed on the obtained curable composition.

[Examples 2 to 10, Comparative Examples 1 to 6]
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 Tables 1-1 and 1-2. The evaluation methods will be described later.

The meaning of the notation for each component in Tables 1-1 and 1-2 is as follows:

X-12-1169MS: acryloxymethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 206)
X-12-1303MS: methacryloxymethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 220)
X-12-1312MS: methoxymethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 166)
X-12-1307: Mercaptomethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 168)
KBM-1003: vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 148)
KBM-5013: Acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 234)
KBM-6103: N-2-(aminoethyl)-3-aminomethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 194)
Isocyanate methyltrimethoxysilane (molecular weight: 177)
KBM-603: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 222)
[Method for evaluating curable compositions]
The methods for evaluating the various physical properties of the curable composition are described below.

<Tuck-free time>
The curable compositions obtained in the Examples and Comparative Examples were coated onto a Teflon (registered trademark) sheet using a doctor blade so that the thickness of the cured product layer was 2 mm. After starting curing under conditions of 23°C/50% RH, the time until adhesion of an SUS spatula to the composition (cured product) was no longer observed when the composition was brought into contact with the spatula was measured.

<Stress at break, elongation>
The curable compositions obtained in the Examples and Comparative Examples were coated onto a Teflon (registered trademark) sheet using a doctor blade to form a cured layer of 2 mm thick, and then aged for 7 days at 23°C/50% RH. The resulting cured products were then punched out into JIS No. 3 dumbbell-shaped samples. Tensile tests were performed on the resulting samples in accordance with JIS K6251:2010 (Vulcanized rubber and thermoplastic rubber - Determination of tensile properties) at a pulling rate of 200 mm/min at 23°C, and the stress at break and elongation were measured.

<Shear adhesive strength>
The curable compositions obtained in the examples and comparative examples were applied to two aluminum (A1050, thickness 1 mm) test pieces in accordance with JIS-K6850:1999 (Testing method for tensile shear bond strength between adhesives and rigid adherends), allowed to stand for 2 minutes, and then laminated together so that the thickness of the curable composition layer was 0.2 mm. After aging for 7 days under conditions of 23°C/50% RH, the shear adhesive strength was measured using a universal tensile tester AG-X (manufactured by Shimadzu Corporation) in accordance with JIS K6850:1999 at a tensile speed of 50 mm/min and 23°C.

<Gel fraction>
The curable compositions obtained in the Examples and Comparative Examples were coated onto a Teflon (registered trademark) sheet using a doctor blade to give a cured layer thickness of 2 mm, and then aged for 7 days under conditions of 23°C/50% RH. Then, 0.2 g of the resulting cured product (dry mass) was weighed into a sample bottle, 40 g of ethyl acetate was added to the sample bottle, and the bottle was allowed to stand for 1 day under an environment of 23°C. After filtering through a 200-mesh stainless steel wire mesh made of SUS, the residue on the wire mesh was dried at 90°C for 2 hours, and the mass of the resulting residue was weighed, and the gel fraction was calculated using the following equation.

Gel fraction (%) = (weighing value of residue after drying) ÷ (weighing value of hardened product after curing) × 100
<Shear adhesive strength after storage stability test>
The curable compositions obtained in the Examples and Comparative Examples were filled into paper cartridges (capacity: 330 mL) and left to stand for one month in a 60°C environment as a storage stability test. Thereafter, the shear adhesive strength was measured using the same method as above. The shear adhesive strength of the cured product after the storage stability test (left to stand for one month in a 60°C environment) was divided by the shear adhesive strength of the cured product before the storage stability test (aged for 7 days under conditions of 23°C/50% RH) to calculate the change in shear adhesive strength [%].

Claims (7)

a (meth)acrylic polymer (A) having a group represented by formula (1), having a number average molecular weight (Mn) of 1,000 or more, and containing 500 ppm or more of silicon element;
A curable composition containing a silane coupling agent (B) represented by formula (2) and having a molecular weight of less than 1,000,
A curable composition, wherein the (meth)acrylic polymer (A) has a structural unit derived from a monomer (a2) represented by formula (a2-1) :
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.]
Formula (2): Y-CH ₂ -SiR ¹ ₃
[In formula (2), ^R1 has the same meaning as in formula (1); and Y represents a (meth)acryloyl group, an alkoxy group having 1 to 20 carbon atoms, a mercapto group, or an isocyanate group.]
[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 0.1 to 20 parts by mass of (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 at least one terminal. The curable composition according to claim 1, wherein the glass transition temperature (Tg) of the (meth)acrylic polymer (A) is -20°C or lower. The curable composition according to claim 1, wherein the number average molecular weight of the (meth)acrylic polymer (A) is 1,000 to 100,000. The curable composition according to claim 1, comprising 0.05 to 10 parts by mass of an aminosilane compound (C) represented by the following formula (3) relative to 100 parts by mass of the (meth)acrylic polymer (A):
Formula (3): R ⁴ ₂ -N-(CH ₂ ) _n -SiR ¹ ₃
[In formula (3), n is an integer of 1 to 6; ^R1 has the same meaning as in formula (1); and ^R4s each independently represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a group in which at least one hydrogen atom of the hydrocarbon group has been substituted with a group selected from the group consisting of an unsubstituted amino group, a substituted amino group, and an alkoxysilyl group.] A cured product obtained from the curable composition according to any one of claims 1 to 6.