JP7826082B2 - Curable composition and cured product thereof - Google Patents

Description

The present invention relates to a curable composition. The present invention also relates to a cured product obtained by curing the curable composition.

Acrylic urethane paints are commonly used in a wide range of industries, including construction, home appliances, and automobiles. They consist of two liquid components: a base agent (acrylic polyol) and a curing agent (polyisocyanate). However, these acrylic urethane paints lack sufficient scratch resistance, chemical resistance, and stain resistance, and improvements in these areas are needed.

A technique for incorporating polysiloxanes into acrylic urethane paints is known, with the aim of improving the physical properties of the cured coating film produced by curing the acrylic urethane paint. For example, Patent Document 1 discloses a coating composition in which polysilicate is incorporated into an acrylic urethane paint.

JP 2013-159622 A

In applications where assembly is performed after painting, such as home appliances and automotive components, there are cases where repainting is required to repair scratches that occur in the paint film during assembly, and paints that are excellent in recoatability in addition to scratch resistance and chemical resistance are required.

The inventors' investigations revealed that when a cured coating film was obtained by blending polysilicate into an acrylic urethane paint, as disclosed in Patent Document 1, the inclusion of polysilicate reduced the wettability of the coating surface, and the recoatability did not reach a sufficient level, indicating the need for improvement.

The present invention aims to solve the above problems and provide a curable composition that can produce a cured product with excellent recoatability, chemical resistance, and scratch resistance.

The inventors conducted extensive research to solve the above-mentioned problems, and as a result, completed the present invention.

That is, the present invention relates to the following [1] to [8].
[1] A curable composition comprising: (meth)acrylic polyol (A), polyisocyanate (B), and co-condensate (C) of an alkoxysilane compound having an epoxy group and a silicate compound,
the (meth)acrylic polyol (A) has a hydroxyl value of 100 to 200 mgKOH/g;
The curable composition, wherein the co-condensate (C) has an epoxy equivalent of 3,600 or more.
[2] The curable composition according to [1], wherein the co-condensation product (C) is 1 to 10 parts by weight relative to 100 parts by weight of the (meth)acrylic polyol (A).
[3] The curable composition according to either [1] or [2], wherein the co-condensation product (C) contains an epoxycyclohexyl group.
[4] The curable composition according to any one of [1] to [3], wherein the weight average molecular weight of the (meth)acrylic polyol (A) is 2,000 to 12,000.
[5] The curable composition according to any one of [1] to [4], wherein the polyisocyanate (B) is 40 to 70 parts by weight relative to 100 parts by weight of the (meth)acrylic polyol (A).
[6] The curable composition according to any one of [1] to [6], which is a multi-component curable composition.
[7] A first liquid containing the (meth)acrylic polyol (A) and the co-condensate (C),
and a second liquid containing the polyisocyanate (B).
[8] A cured product obtained by curing the curable composition according to any one of [1] to [7].

The present invention provides a curable composition that has excellent scratch resistance and chemical resistance without impairing recoatability.

One aspect of the present invention is described in detail below. Unless otherwise specified, "A to B" representing a numerical range means "A or greater and B or less." Furthermore, in this specification, "(meth)acrylic" means "acrylic" and/or "methacrylic."

[Curable composition]
The present curable composition comprises (meth)acrylic polyol (A), polyisocyanate (B), and co-condensate (C) of an alkoxysilane having an epoxy group and a silicate compound, wherein the hydroxyl value of the acrylic resin (A) is 100 to 200 mgKOH/g, and the epoxy equivalent of the co-condensate (C) is 3600 or more. Because the present curable composition has the above-mentioned configuration, it can provide a cured product that has excellent recoatability, chemical resistance, and scratch resistance.

((A) (meth)acrylic polyol)
The present curable composition contains a (meth)acrylic polyol (A). Hereinafter, the "(meth)acrylic polyol (A)" may be referred to as "component (A)."

In this specification, component (A) refers to a copolymer having two or more hydroxyl groups in the molecule, obtained by copolymerization (e.g., radical polymerization) of a (meth)acrylic monomer and a monomer having a hydroxyl group. Component (A) is preferably obtained by radical polymerization. Component (A) can also be said to be a copolymer containing a (meth)acrylic monomer and a monomer having a hydroxyl group. Component (A) may use one type of (meth)acrylic polyol alone, or two or more types may be used in combination.

The (meth)acrylic monomer is not particularly limited, but examples include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; cycloalkyl (meth)acrylates having 4 to 20 carbon atoms, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; and aralkyl (meth)acrylates having 3 to 20 carbon atoms, such as allyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and benzyl (meth)acrylate. Component (A) may contain only one type of these (meth)acrylic monomers, or two or more types. A (meth)acrylic monomer can also be considered a monomer having a (meth)acrylic group.

The monomer having a hydroxyl group is not particularly limited, but examples thereof include hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono(meth)acrylate, cyclohexanedimethanol (meth)acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth)acrylamide, and 4-hydroxystyrene vinyl toluene; Placcel FA-1, Plac Examples of suitable monomers include modified lactones or polyesters having a polymerizable carbon-carbon double bond at the end, such as Placel FA-4, Placel FM-1, and Placel FM-4 (all manufactured by Daicel Chemical Industries, Ltd.); and polyoxyalkylenes having a polymerizable carbon-carbon double bond at the end, such as the Blenmer PP series, Blenmer PE series, and Blenmer PEP series (all manufactured by NOF Corporation), MA-30, MA-50, MA-100, MA-150, RA-1120, RA-2614, RMA-564, RMA-568, RMA-1114, and MPG130-MA (all manufactured by Nippon Nyukazai Co., Ltd.). Component (A) may contain only one or more of these hydroxyl group-containing monomers.

Component (A) may also contain monomers (other monomers) other than the above-mentioned (meth)acrylic monomers and monomers having a hydroxyl group. Examples of other monomers include, but are not limited to, olefin-based monomers such as ethylene and propylene, styrene-based monomers, acid-based monomers such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid, acid anhydrides such as maleic anhydride, and monomers having a reactive silicon group. These other monomers may be used alone or in combination of two or more.

The number of hydroxyl groups contained in the molecule of component (A) is not particularly limited as long as it is two or more, but is, for example, three or more, preferably five or more, and more preferably seven or more. When the number of hydroxyl groups contained in the molecule of component (A) is three or more, a dense crosslinked structure is obtained, and a cured product with excellent scratch resistance can be obtained. Furthermore, the upper limit of the number of hydroxyl groups contained in the molecule of component (A) is not particularly limited, but is, for example, 50 or less, preferably 40 or less. When the number of hydroxyl groups contained in the molecule of component (A) is 50 or less, fewer hydroxyl groups remain in the cured product (coating film) after the curing reaction, and a cured product (coating film) with excellent water resistance can be obtained.

The hydroxyl value of component (A) is 100 to 200 mgKOH/g, more preferably 110 to 190 mgKOH/g, even more preferably 120 to 180 mgKOH/g, and particularly preferably 150 to 180 mgKOH/g. When component (A) has a hydroxyl value of 100 to 200 mgKOH/g, a curable composition with a high crosslink density and excellent scratch resistance and chemical resistance can be obtained. Note that, in this specification, the hydroxyl value is a value measured in accordance with JIS K 1557-1.

The number average molecular weight (Mn) of component (A) is preferably 1,000 to 6,000, more preferably 1,500 to 5,000, even more preferably 2,000 to 4,500, and particularly preferably 2,500 to 4,200. When the number average molecular weight (Mn) of component (A) is 1,000 to 6,000, a cured product with high crosslink density and excellent scratch resistance and chemical resistance can be obtained. The number average molecular weight (Mn) of component (A) is a value calculated using GPC in terms of polystyrene.

The weight-average molecular weight (Mw) of component (A) is not particularly limited, but is preferably 2,000 to 12,000, more preferably 3,000 to 10,000, and even more preferably 4,000 to 9,000. A weight-average molecular weight (Mw) of component (A) of 2,000 to 12,000 ensures excellent compatibility with the co-condensation product of an alkoxysilane compound having an epoxy group and a silicate compound, as described below, and allows for the production of a cured product with excellent transparency. The weight-average molecular weight (Mw) of component (A) is a value calculated using GPC in terms of polystyrene.

(Method for producing component (A))
Component (A) can be produced by polymerizing the above-mentioned (meth)acrylic monomer, a monomer having a hydroxyl group, and optionally other monomers by a known method (for example, by heating in the presence of a polymerization initiator).

The polymerization initiator is not particularly limited, but is preferably an initiator that can generate radicals upon heating (radical polymerization initiator). Examples of such polymerization initiators include organic peroxides such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butylperoxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, and diisopropyl peroxycarbonate. These polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator used when producing component (A) is not particularly limited, but is preferably 0.1 to 5.0 parts by weight, more preferably 0.3 to 4.0 parts by weight, and even more preferably 0.5 to 2.0 parts by weight, per 100 parts by weight of the total amount of the above-mentioned acrylic group-containing monomer, hydroxyl group-containing monomer, and other monomers. When the amount of polymerization initiator used is 0.1 part by weight or more, the polymerization reaction proceeds appropriately. Furthermore, when the amount of polymerization initiator used is 5.0 parts by weight or less, a copolymer with an appropriate molecular weight can be obtained.

Component (A) may be produced by polymerizing a (meth)acrylic monomer, a hydroxyl group-containing monomer, and optionally other monomers in the presence of a solvent. Examples of such solvents include, but are not limited to, hydrocarbon solvents such as toluene, xylene, heptane, hexane, and petroleum-based solvents; halogenated solvents such as trichloroethylene; ester solvents such as ethyl acetate, butyl acetate, and isobutyl acetate (IBAC); ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dibutyl ether, dipentynyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol methyl ether acetate; and silicone solvents such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

In one embodiment of the present invention, a chain transfer agent may be used in addition to the polymerization initiator when producing component (A). By using a chain transfer agent, the molecular weight (number average molecular weight) of component (A) can be controlled within a suitable range. The chain transfer agent is not particularly limited, but examples include n-dodecyl mercaptan, t-dodecyl mercaptan, 2-ethylhexyl thioglycolate, n-octyl mercaptan, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, mercaptoethanol, and α-methylstyrene dimer. These chain transfer agents may be used alone or in combination of two or more.

The amount of the chain transfer agent used when producing component (A) is not particularly limited, but is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, and even more preferably 0.5 to 6 parts by weight, per 100 parts by weight of the combined total of the acrylic group-containing monomer, hydroxyl group-containing monomer, and other monomers. When the amount of chain transfer agent used is 0.5 parts by weight or more, functional groups (nitrile groups, carboxyl groups, ester groups, etc.) derived from the polymerization initiator (radical generator) are not introduced to the polymer terminals of component (B), thereby preventing the inhibition of curing of component (A) by these functional groups. Furthermore, when the amount of chain transfer agent used is 10 parts by weight or less, the agent is efficiently introduced to the polymer terminals, eliminating the risk of it remaining in the curable composition as an unreacted product (plasticizer).

((B) Polyisocyanate)
The present curable composition contains a polyisocyanate (B). Hereinafter, the "polyisocyanate (B)" may be referred to as "component (B)."

The number of isocyanate groups contained in component (B) is not particularly limited as long as it is two or more per molecule, but is preferably 2.1 or more, more preferably 2.3 or more, and even more preferably 2.5 or more per molecule. The upper limit of the number of isocyanate groups contained in component (B) is not particularly limited, but is preferably, for example, 20 or less, more preferably 10 or less, and particularly preferably 5 or less. When the number of isocyanate groups contained in component (B) is 20 or less, (i) it is possible to obtain a curable composition that has excellent compatibility with component (A) and (ii) excellent reactivity due to the absence of risk of steric repulsion between the isocyanate groups.

Conventionally known polyisocyanates can be used as component (B). Examples of such polyisocyanates include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, araliphatic polyisocyanate compounds, and aromatic polyisocyanate compounds.

Examples of aliphatic polyisocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate. Examples include diisocyanate compounds such as methyl caproate; compounds with three or more isocyanate groups such as lysine ester triisocyanate, 1,4,8-triisocyanato octane, 1,6,11-triisocyanato undecane, 1,8-diisocyanato-4-isocyanato methyl octane, 1,3,6-triisocyanato hexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanato methyl octane; and the like.

Examples of alicyclic polyisocyanate compounds include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3 diisocyanate compounds such as 1,3,5-bis(isocyanatemethyl)cyclohexane, 1,4-bis(isocyanatemethyl)cyclohexane, and isophorone diisocyanate; 1,3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 3-isocyanatemethyl-3,3,5-trimethylcyclohexyl isocyanate, and 2-(3-isocyanatepropyl)-2,5-di(isocyanatemethyl)-bis(isocyanatemethyl)- Cyclo[2,2,1]heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo[2,2,1]heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo[2,2,1]heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo[2,2,1]heptane, 6-(2-isocyanatoethyl)-2-isocyanatoethyl Compounds having three or more isocyanate groups, such as isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo[2,2,1]heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo[2,2,1]heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo[2,2,1]heptane; and the like.

Examples of aromatic aliphatic polyisocyanate compounds include diisocyanate compounds such as 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or mixtures thereof; and compounds having three or more isocyanate groups, such as 1,3,5-triisocyanatomethylbenzene.

Examples of aromatic polyisocyanate compounds include diisocyanate compounds such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate; and compounds having three or more isocyanate groups such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate, and polymethylene polyphenyl polyisocyanate (polymeric MDI).

In one embodiment of the present invention, modified versions of the various isocyanate-containing compounds described above may be used as component (B). Examples of such modified versions include allophanate modified versions, biuret modified versions, and isocyanurate modified versions.

Component (B) is preferably a polyisocyanate having a cyclic structure or a linear or branched structure. Component (B) is more preferably one or more selected from the group consisting of aromatic polyisocyanates, alicyclic polyisocyanates, and araliphatic polyisocyanates. Polyisocyanates having a cyclic structure within the molecule, such as alicyclic polyisocyanate compounds, araliphatic polyisocyanate compounds, and aromatic polyisocyanate compounds, are more preferred because they significantly improve the physical properties (adhesion, toughness, impact resistance) of the resulting cured product. Among these, aromatic polyisocyanates are even more preferred, with 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, and polymethylene polyphenyl polyisocyanate (polymeric MDI) being particularly preferred because the resulting curable composition has excellent adhesion.

Aliphatic polyisocyanate compounds and alicyclic polyisocyanate compounds are preferred because the resulting cured product has excellent weather resistance. Hexamethylene diisocyanate, isophorone diisocyanate, and their isocyanurate-modified forms are particularly preferred.

If yellowing becomes a problem when using these polyisocyanate compounds, it is preferable to use aliphatic, alicyclic, or araliphatic polyisocyanates, with aliphatic polyisocyanates or alicyclic polyisocyanates being more preferred.

In one embodiment of the present invention, component (B) can be converted into a blocked isocyanate in which the isocyanate group is masked with a blocking agent and deactivated at room temperature. Examples of blocking agents include alcohols, phenols, oximes, triazoles, and caprolactams.

The content of component (B) in the curable composition can be adjusted depending on the hydroxyl value of component (A), but a preferred content is, for example, 40 to 70 parts by weight per 100 parts by weight of component (A). When the content of component (B) in the curable composition is 40 to 70 parts by weight, it reacts sufficiently with component (A) and the co-condensate (C) of an alkoxysilane compound having an epoxy group and a silicate compound to form a crosslinked structure, resulting in a cured product with excellent scratch resistance and chemical resistance.

((C) Co-condensation product of an alkoxysilane compound having an epoxy group and a silicate compound)
The curable composition contains a co-condensation product (C) of an alkoxysilane compound having an epoxy group and a silicate compound. Hereinafter, the "co-condensation product (C) of an alkoxysilane compound having an epoxy group and a silicate compound" may be referred to as "component (C)."

In this specification, component (C) refers to an organopolysiloxane formed by subjecting an alkoxysilane compound having an epoxy group (hereinafter referred to as alkoxysilane compound (c1)) and a silicate compound (hereinafter referred to as silicate compound (c2)) to a hydrolysis/dehydration condensation reaction in the presence of water, i.e., by forming a siloxane bond between the alkoxysilane compound (c1) and the silicate compound (c2).

(Alkoxysilane Compound (c1) (Alkoxysilane Compound Having an Epoxy Group))
The alkoxysilane compound (c1) is one or more silane compounds having an alkoxy group and an epoxy group as substituents on the silicon atom. The presence of the epoxy group can improve the recoatability of the cured product obtained by curing the curable composition containing component (C).

The alkoxysilane compound (c1) may be any of monoorganotrialkoxysilane, diorganodialkoxysilane, and triorganomonoalkoxysilane. It is preferable that the alkoxysilane compound (c1) contains at least one type of monoorganotrialkoxysilane. The alkoxysilane component may be composed solely of monoorganotrialkoxysilane, or may be composed solely of monoorganotrialkoxysilane and diorganodialkoxysilane, or may be composed of monoorganotrialkoxysilane, diorganodialkoxysilane, and/or triorganomonoalkoxysilane.

When the alkoxysilane compound (c1) contains a triorganomonoalkoxysilane, the content is not particularly limited as long as it does not impair the effects of the invention. For example, the content is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 1 mol% or less, relative to the total amount (100 mol%) of the alkoxysilane components.

Examples of the alkoxy group that the alkoxysilane compound (c1) has as a substituent on the silicon atom include alkoxy groups having 1 to 3 carbon atoms. Specific examples include methoxy, ethoxy, and propoxy groups, with methoxy and ethoxy groups being preferred, and methoxy groups being more preferred. The alkoxy group may be of one type, or two or more types may be mixed.

Examples of the epoxy group that the alkoxysilane compound (c1) has as a substituent on the silicon atom include a glycidyloxy group and an epoxycyclohexyl group. Examples include a 1-glycidyloxymethyl group, a 2-glycidyloxyethyl group, a 3-glycidyloxypropyl group, a 4-glycidyloxybutylmethyl group, a 6-glycidyloxyhexyl group, an 8-glycidyloxyoctyl group, and a 2-(3,4-epoxycyclohexyl) group. The epoxy group may be of one type, or two or more types may be mixed. Among these, an epoxycyclohexyl group is preferred because the resulting cured product has excellent scratch resistance, recoatability, and chemical resistance.

The alkoxysilane compound (c1) is required to contain at least one alkoxy group and at least one epoxy group as substituents on the silicon atom, and may also contain an organic group (an organic group other than an epoxy group) in addition to these.

Examples of such organic groups include alkyl groups having 1 to 8 carbon atoms, alkenyl groups having 2 to 8 carbon atoms, and aryl groups having 6 to 12 carbon atoms. The alkyl groups, alkenyl groups, and aryl groups may be unsubstituted or may have a substituent. The alkyl groups preferably have 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, even more preferably 1 to 3 carbon atoms, and even more preferably 1 to 2 carbon atoms. The alkenyl groups preferably have 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms. The organic groups may be of one type, or two or more types may be mixed.

In one embodiment of the present invention, examples of the alkoxysilane compound (c1) include a trialkoxysilane compound having a glycidyloxy group, a dialkoxysilane compound having a glycidyloxy group and an organic group, a trialkoxysilane compound having a glycidyloxy group, and a dialkoxysilane compound having a glycidyloxy group and an organic group. More specifically, the alkoxysilane compound (c1) may be 1-glycidyloxymethyltrimethoxysilane, 1-glycidyloxymethylmethyldimethoxysilane, 1-glycidyloxymethyltriethoxysilane, 1-glycidyloxymethylmethyldiethoxysilane, 2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethylmethyldimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 2-glycidyloxyethylmethyldiethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 4-glycidyl Examples of suitable alkoxysilanes include oxybutyltrimethoxysilane, 4-glycidyloxybutylmethyldimethoxysilane, 4-glycidyloxybutyltriethoxysilane, 4-glycidyloxybutylmethyldiethoxysilane, 6-glycidyloxyhexyltrimethoxysilane, 6-glycidyloxyhexylmethyldimethoxysilane, 6-glycidyloxyhexyltriethoxysilane, 6-glycidyloxyhexylmethyldiethoxysilane, 8-glycidyloxyoctyltrimethoxysilane, 8-glycidyloxyoctylmethyldimethoxysilane, 8-glycidyloxyoctyltriethoxysilane, 8-glycidyloxyoctylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Among these, trialkoxysilane compounds or dialkoxysilane compounds having a 3-glycidyloxypropyl group are preferred, with trialkoxysilane compounds having a 3-glycidyloxypropyl group being particularly preferred.

Examples of the alkoxysilane compound having an epoxycyclohexyl group include trialkoxysilanes having an epoxycyclohexyl alkyl group, and dialkoxysilanes having an epoxycyclohexyl alkyl group and the organic group. More specifically, 1-(3,4-epoxycyclohexyl)methyltrimethoxysilane, 1-(3,4-epoxycyclohexyl)methylmethyldimethoxysilane, 1-(3,4-epoxycyclohexyl)methyltriethoxysilane, 1-(3,4-epoxycyclohexyl)methylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, silane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldimethoxysilane, 3-(3,4-epoxycyclohexyl)propyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldiethoxysilane, 4 -(3,4-epoxycyclohexyl)butyltrimethoxysilane, 4-(3,4-epoxycyclohexyl)butylmethyldimethoxysilane, 4-(3,4-epoxycyclohexyl)butyltriethoxysilane, 4-(3,4-epoxycyclohexyl)butylmethyldiethoxysilane, 6-(3,4-epoxycyclohexyl)hexyltrimethoxysilane, 6-(3,4-epoxycyclohexyl)hexylmethyldimethoxysilane, 6-(3,4 Examples of suitable alkoxysilanes include 6-(3,4-epoxycyclohexyl)hexyltriethoxysilane, 6-(3,4-epoxycyclohexyl)hexylmethyldiethoxysilane, 8-(3,4-epoxycyclohexyl)octyltrimethoxysilane, 8-(3,4-epoxycyclohexyl)octylmethyldimethoxysilane, 8-(3,4-epoxycyclohexyl)octyltriethoxysilane, and 8-(3,4-epoxycyclohexyl)octylmethyldiethoxysilane. Among these, trialkoxysilane compounds or dialkoxysilane compounds having a 2-(3,4-epoxycyclohexyl) group are preferred, and trialkoxysilane compounds having a 2-(3,4-epoxycyclohexyl) group are particularly preferred.

(Silicate compound (c2))
In one embodiment of the present invention, examples of the silicate compound (c2) include tetraalkoxysilane and hydrolysis condensates of tetraalkoxysilane.

Examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, which can be used alone or in combination of two or more. Among these, from the viewpoints of the storage stability of the resulting hydrolysis condensation product and the scratch resistance of the cured product, tetramethoxysilane and/or tetraethoxysilane are preferred, and tetraethoxysilane is more preferred.

Commercially available tetraalkoxysilanes can be used. Specifically, for example, commercially available tetramethoxysilanes include "Methyl Orthosilicate" (trade name, manufactured by Tama Chemicals Co., Ltd.). Commercially available tetraethoxysilanes include "KBE-04" (manufactured by Shin-Etsu Chemical Co., Ltd.) and "Ethyl Silicate 28" (manufactured by Colcoat Co., Ltd.).

Commercially available hydrolytic condensates of the tetraalkoxysilanes include, for example, "Ethyl Silicate 40," "Ethyl Silicate 48," "Methyl Silicate 51," "Methyl Silicate 53A," and "EMS-485" (all manufactured by Colcoat Co., Ltd.).

The epoxy equivalent of component (C) is 3600 or more, preferably 7200 or more, and more preferably 10800 or more. If the epoxy equivalent of component (C) is 3600 or more, it will exhibit recoatability. Although the cause is not clear, it is believed that if the epoxy equivalent is 3600 or more, component (C) localizes on the surface of the cured product, and the epoxy groups in component (C) form bonds with the recoat coating, thereby exhibiting recoatability. There is no particular upper limit to the epoxy equivalent, but for example, it is preferably 1,750,000 or less, and more preferably 350,000 or less.

The epoxy equivalent is the mass of resin per epoxy group and can be determined by dividing the solids content of component (C) by the number of moles of epoxy groups contained in component (C). The epoxy equivalent can also be determined according to a method in accordance with JIS K7236:2001.

The content of component (C) in the curable composition is preferably 1 to 10 parts by weight, more preferably 1 to 8 parts by weight, and even more preferably 1 to 5 parts by weight, per 100 parts by weight of component (A). When the content of component (C) in the curable composition is 1 to 10 parts by weight, it is possible to obtain a cured product that has excellent scratch resistance and chemical resistance without impairing the transparency of the cured product.

(Method for producing component (C))
The component (C) can be produced by subjecting the above-mentioned alkoxysilane compound (c1) and silicate compound (c2) to hydrolysis and dehydration condensation reaction in the presence of water.

In one embodiment of the present invention, a dehydration condensation catalyst may be optionally added when the alkoxysilane compound (c1) and the silicate compound (c2) are subjected to a hydrolysis/dehydration condensation reaction. Such a dehydration condensation catalyst is not particularly limited as long as it is a substance capable of promoting the dehydration condensation reaction of a mixture containing the alkoxysilane compound (c1), the silicate compound (c2), and water. Examples of such a catalyst include acidic catalysts, basic catalysts, and neutral salt catalysts. Among these, neutral salt catalysts are preferred because they can suppress the deactivation of epoxy groups and produce a cured product with excellent adhesion and scratch resistance.

In this specification, the term "neutral salt catalyst" refers to a salt (neutral salt) formed from a strong acid and a strong base. Specifically, this refers to a salt formed by combining a cation selected from the group consisting of Group 1 element ions, Group 2 element ions, tetraalkylammonium ions, and guanidinium ions with an anion selected from the group consisting of Group 17 element ions (excluding fluoride ions), sulfate ions, nitrate ions, and perchlorate ions. Examples of neutral salts used as the neutral salt catalyst include lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, francium chloride, beryllium chloride, magnesium chloride, calcium chloride, strontium chloride, barium chloride, radium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetrapentylammonium chloride, tetrahexylammonium chloride, and guanidium chloride; lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, francium bromide, beryllium bromide, magnesium bromide, calcium bromide, strontium bromide, barium bromide, and radium bromide. Tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, guanidium bromide; lithium iodide, sodium iodide, potassium iodide, rubidium iodide, cesium iodide, francium iodide, beryllium iodide, magnesium iodide, calcium iodide, strontium iodide, barium iodide, radium iodide, tetramethylammonium iodide, tetraethylammonium iodide, tetrapropylammonium iodide, tetrabutylammonium iodide, tetrapentylammonium iodide, tetrahexylammonium iodide, guanidium iodide; Lithium sulfate, sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, francium sulfate, beryllium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, radium sulfate, tetramethylammonium sulfate, tetraethylammonium sulfate, tetrapropylammonium sulfate, tetrabutylammonium sulfate, tetrapentylammonium sulfate, tetrahexylammonium sulfate, guanidium sulfate; lithium nitrate, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, francium nitrate, beryllium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, radium nitrate, tetramethylammonium nitrate, tetraethylammonium nitrate Examples of neutral salts include ammonium nitrate, tetrapropylammonium nitrate, tetrabutylammonium nitrate, tetrapentylammonium nitrate, tetrahexylammonium nitrate, and guanidium nitrate; lithium perchlorate, sodium perchlorate, potassium perchlorate, rubidium perchlorate, cesium perchlorate, francium perchlorate, beryllium perchlorate, magnesium perchlorate, calcium perchlorate, strontium perchlorate, barium perchlorate, radium perchlorate, tetramethylammonium perchlorate, tetraethylammonium perchlorate, tetrapropylammonium perchlorate, tetrabutylammonium perchlorate, tetrapentylammonium perchlorate, tetrahexylammonium perchlorate, and guanidium perchlorate. These neutral salts may be used alone or in combination of two or more.

The amount of dehydration condensation catalyst added during the hydrolysis and dehydration condensation reaction can be determined appropriately depending on the desired degree of progress of the hydrolysis and dehydration condensation reaction, but is preferably 1 ppm to 100,000 ppm, more preferably 10 ppm to 10,000 ppm, even more preferably 20 ppm to 5,000 ppm, and even more preferably 50 ppm to 1,000 ppm, relative to the total amount of alkoxysilane compound (c1) and silicate compound (c2).

In the method for producing component (C), the amount of water used when subjecting the alkoxysilane compound (c1) and the silicate compound (c2) to a hydrolysis and dehydration condensation reaction is preferably 1 to 10 parts by weight, and more preferably 1 to 5 parts by weight, per 100 parts by weight of the alkoxysilane compound (c1) and the silicate compound (c2). When the amount of water used is 1 to 10 parts by weight, the hydrolysis and dehydration condensation reaction proceeds sufficiently, and the scratch resistance of the cured product can be improved.

During this reaction, some of the alkoxy groups contained in the alkoxysilane component remain unreacted, or after the alkoxy groups undergo hydrolysis, they do not undergo a dehydration condensation reaction and remain as silanol groups, allowing the produced polyorganosiloxane to contain reactive silicon groups (alkoxysilyl groups and/or silanol groups). The silanol groups remaining in component (C) can form bonds (Si-O-C) with the hydroxyl groups in component (A) when the composition is cured, potentially improving the transparency or scratch resistance of the cured product.

In one embodiment of the present invention, an organic solvent other than water may be used in addition to water when the alkoxysilane compound (c1) and the silicate compound (c2) are subjected to a hydrolysis/dehydration condensation reaction. Since such an organic solvent is used in combination with water, an organic solvent with high solubility in water is preferred. Furthermore, to ensure the solubility of the alkoxysilane component, an organic solvent with 4 or more carbon atoms is preferred. From the above perspective, preferred organic solvents include, for example, propylene glycol methyl ether acetate, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, methanol, ethanol, 1-propanol, and 2-propanol, but are not limited to these.

The reaction temperature when carrying out the hydrolysis and dehydration condensation reaction of the alkoxysilane compound (c1) and the silicate compound (c2) can be determined as appropriate by those skilled in the art, but it is preferable to heat the reaction solution to, for example, 50°C to 110°C. Carrying out the hydrolysis and dehydration condensation reaction at a temperature of 50°C to 110°C or lower facilitates the production of component (C). Furthermore, the reaction time when carrying out the hydrolysis and dehydration condensation reaction can be determined as appropriate by those skilled in the art, but may be, for example, approximately 10 minutes to 12 hours.

In the method for producing component (C), it is preferable to carry out a step (alcohol removal step) of removing the alcohol generated in the hydrolysis reaction from the reaction solution after the hydrolysis and dehydration condensation reaction. By removing the alcohol, the hydrolysis reaction of the alkoxysilyl group, which by-produces alcohol, can be further promoted. The alcohol removal step can be carried out, for example, by subjecting the reaction solution after the hydrolysis and dehydration condensation reaction to vacuum distillation to distill off the alcohol. The conditions for vacuum distillation can be appropriately set by those skilled in the art, but the temperature at this time is preferably 50°C to 110°C, as this facilitates the production of component (C). In the alcohol removal step, it is preferable to remove 80 mol% or more of the alcohol generated by the hydrolysis reaction, and more preferably 90 mol% or more of the alcohol.

After the hydrolysis and dehydration condensation reaction (preferably after the alcohol removal step), the reaction system can be cooled (e.g., to 30°C or below) to obtain component (C).

(Other ingredients)
(solvent)
The present curable composition may further contain a solvent in addition to the above components (A) to (C).

The solvent is not particularly limited, and various compounds can be used. More specifically, examples of solvents include hydrocarbon solvents such as toluene, xylene, heptane, hexane, and petroleum-based solvents; halogenated solvents such as trichloroethylene; ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate (IBAC), and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as propylene glycol methyl ether acetate (PMA), dibutyl ether, dipentynyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether; and silicone solvents such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. Among these, ester and ether solvents are preferred due to their high solubility in components (A) and (B) and their high volatility during spray application. Isobutyl acetate, methoxypropyl acetate, and propylene glycol methyl ether acetate are particularly preferred. These solvents may be used alone or in combination of two or more.

The solvent content in the curable composition is preferably 40 to 80 parts by weight, more preferably 45 to 75 parts by weight, and even more preferably 50 to 70 parts by weight, based on 100 parts by weight of the total amount of the curable composition. When the solvent content in the curable composition is 40 parts by weight or more, a curable composition with low viscosity, high thixotropy, and excellent workability can be obtained. Furthermore, when the solvent content in the curable composition is 80 parts by weight or less, a cured product with a sufficient film thickness can be obtained with a single coating.

(Metal catalyst)
The curable composition may further contain a metal catalyst in addition to the above components (A) to (C). Examples of the metal catalyst include organometallic acid catalysts such as organotin compounds, organoaluminum compounds, organozinc compounds, organotitanium compounds, and organoiron compounds.

(Additives)
The curable composition may contain additives commonly used in the art, as long as the effects of the present invention are achieved. Examples of such additives include dehydrating agents, stabilizers, fillers, flame retardants, dispersants, defoamers, plasticizers, tackifiers, leveling agents, thixotropy-imparting agents, epoxy resins, antioxidants, light stabilizers, UV absorbers, silane coupling agents, hydrolysis stabilizers, titanate coupling agents, aluminate coupling agents, mold release agents, antistatic agents, lubricants, low-shrinkage agents, silicone surfactants, and water. The additives may be contained alone or in combination of two or more. The amounts of these additives can be appropriately determined by those skilled in the art depending on the intended use. Furthermore, these additives can be added to the curable composition at any timing. For example, they may be added when components (A) to (C) are mixed, or they may be added immediately before use of the curable composition.

(others)
The curable resin composition may be a one-component type or a multi-component type. A one-component curable resin composition is one in which all of the components (components (A) to (C) and other components) are blended in advance and then sealed and stored. A one-component curable resin composition can provide a cured product by curing with moisture in the air after use. On the other hand, a multi-component curable resin composition can provide a cured product by separately producing and storing a first component containing the resin components and a second component containing the curing agent (curing catalyst), and then mixing the first component and the second component immediately before use.

In one embodiment of the present invention, the curable resin composition is preferably a multi-component curable resin composition.

In one embodiment of the present invention, the multi-component curable composition preferably contains component (A) of the curable composition as a first component and component (B) as a second component, and more preferably contains components (A) and (C) as a first component and component (B) as a second component. The first component can also be considered the base component of the multi-component curable composition, and the second component can also be considered the curing agent of the multi-component curable composition.

In one embodiment of the present invention, the first component of the multi-component curable resin composition may contain, in addition to components (A) and (C), other resin components. Examples of such resin components include, but are not limited to, polyether polyol, polyester polyol, polyolefin polyol, (meth)acrylic resin without hydroxyl groups, polystyrene, and AS resin.

In one embodiment of the present invention, the second component of the multi-component curable resin composition may contain other components in addition to component (B). Such components are not particularly limited, but include, for example, solvents, leveling agents, dehydrating agents, stabilizers, organic resins without hydroxyl groups, and metal catalysts (e.g., organometallic acid catalysts such as organotin compounds, organoaluminum compounds, organozinc compounds, organotitanium compounds, and organoiron compounds).

The blending ratio of the first and second liquids in the multi-component curable composition can be adjusted as appropriate depending on the application. The blending ratio of the first and second liquids in the multi-component curable composition is, for example, 20:1 to 1:1, preferably 15:1 to 2:1, and more preferably 10:1 to 3:1. A blending ratio of the first and second liquids of 10:1 to 2:1 can provide a multi-component curable composition that is easy to mix and less prone to uneven performance.

In one embodiment of the present invention, a colorant or the like can be further added to the multi-component curable composition, for example, when mixing the first and second components. This has the advantage of making it possible to provide sealants in a wide range of colors to match the color of siding boards, even with a limited number of curable composition types. Therefore, multi-component curable compositions can easily meet market demand for multiple colors and are suitable for applications such as low-rise buildings. A colorant that is made into a paste by mixing, for example, a pigment, a plasticizer, and, if necessary, a filler, is highly workable and is preferred.

In addition, a retarder can be added to multi-component curable compositions when mixing the components. This allows the curing speed to be fine-tuned at the work site.

(Method for producing curable composition)
The curable composition can be produced by mixing the above-described components (components (A) to (C)) and, if necessary, other components by a known method. The mixing method is not particularly limited, and examples thereof include methods using a mixer such as a mixing vessel equipped with propeller-type or paddle-type stirring blades, a planetary mixer, a kneader, a Hobart mixer, a high-speed mixer, a line mixer, a roll mill, a sand mill, an attritor, or a twin-screw mixer.

In the method for producing the curable composition, the above-mentioned components may be mixed simultaneously, or the components may be mixed by sequentially repeating the process of adding, mixing, and homogenizing each component. Mixing by sequentially repeating the process of adding, mixing, and homogenizing each component is preferred, as this results in a more uniformly mixed composition.

When a multi-component curable composition is to be prepared, the first and second components obtained by the above method are further mixed to obtain the present curable composition. In this case, examples of methods for mixing the first and second components include blending the components and mixing them with a hand mixer or static mixer, kneading them at room temperature or under heat using a planetary mixer, disperser, roll, kneader, or the like, and dissolving the components in a small amount of a suitable solvent and mixing them.

[Cured product]
In one embodiment of the present invention, a cured product (hereinafter referred to as the "cured product") obtained by curing the curable composition is provided.

The present cured product is formed by curing the present curable composition. Preferably, the present cured product is formed by mixing a first liquid (main component) containing components (A) and (C) with a second liquid (curing agent) containing component (B), and then heating and curing the resulting curable composition. Note that if the present curable composition contains volatile components such as solvents, these volatile components volatilize when heated during curing. Therefore, the present cured product is substantially free of the volatile components contained in the present curable composition.

The heating temperature when curing this curable composition is not particularly limited and is typically 50 to 200°C, but 60 to 140°C is preferred, 70 to 130°C is more preferred, and 80 to 120°C is even more preferred. This cured product can have excellent scratch resistance even when formed at a relatively low temperature such as 60 to 140°C.

The heating time for curing the curable composition is not particularly limited, but from the viewpoint of balancing cost and the progress of the curing reaction, 10 to 120 minutes is preferred, 15 to 100 minutes is more preferred, and 30 to 60 minutes is even more preferred.

The thickness of the cured product is not particularly limited, but is preferably 1 to 100 μm. If the thickness of the cured product is 1 μm or more, the cured coating film (cured product) will have good scratch resistance and water resistance. If the thickness of the cured product is 100 μm or less, cracks due to cure shrinkage are less likely to occur. A thickness of 5 to 50 μm is more preferable, and even more preferably 10 to 40 μm.

(Application)
The present curable composition and the present cured product can be used in various applications, for example, transparent materials, optical materials, optical lenses, optical films, optical sheets, adhesives for optical components, optical adhesives for coupling optical waveguides, adhesives for fixing peripheral components of optical waveguides, adhesives for bonding DVDs, pressure-sensitive adhesives, dicing tapes, electronic materials, insulating materials (including printed circuit boards, electric wire coatings, etc.), high-voltage insulating materials, interlayer insulating films, insulating packings, insulating coating materials, adhesives, highly heat-resistant adhesives, highly heat-dissipating adhesives, optical adhesives, adhesives for LED elements, adhesives for various substrates, adhesives for heat sinks, paints, inks, colored inks, coating materials (including hard coats, sheets, films, coatings for optical disks, coatings for optical fibers, etc.), molding materials (including sheets, films, FRP Applications include sealing materials, potting materials, encapsulating materials, encapsulating materials for light-emitting diodes, reflectors and reflective plates for light-emitting diodes, optical semiconductor encapsulating materials, liquid crystal sealants, sealants for display devices, encapsulating materials for electrical materials, encapsulating materials for solar cells, high-heat-resistant sealants, resist materials, liquid resist materials, colored resists, dry film resist materials, solder resist materials, color filter materials, photolithography, materials for electronic paper, hologram materials, solar cell materials, fuel cell materials, display materials, recording materials, vibration-proof materials, waterproof materials, moisture-proof materials, heat-shrinkable rubber tubing, O-rings, photosensitive drums for copiers, solid electrolytes for batteries, and gas separation membranes. Other applications include concrete protective materials, linings, soil injection agents, cold and heat storage materials, sealants for sterilization treatment equipment, contact lenses, oxygen-enriched membranes, and additives to other resins.

In addition, a laminate containing the cured product can be obtained by applying the curable composition to a substrate and curing the mixture using a heat source to form a cured coating film. The laminate can be suitably used for front panels of personal computers, smartphones, tablets, etc., window glass for automobiles, lamp protectors for automobiles, films, etc.

The substrate is not particularly limited and may be, for example, metal (e.g., aluminum, SUS, copper, iron, etc.), ceramics, glass, cement, ceramic substrates, stone, plastic (e.g., polycarbonate (PC), acrylic, ABS, PC-ABS alloy, polyethylene terephthalate (PET), etc.), wood, paper, fiber, etc. The substrate may also be a film or sheet. The curable composition is suitable for use in coating automobiles, buildings, home appliances, industrial equipment, etc. Because the curable composition cures upon heating, it is particularly suitable for forming coating films on the surfaces of substrates with complex shapes. Furthermore, as described above, the curable composition can achieve excellent scratch resistance even when cured at relatively low temperatures such as 60 to 120°C. Therefore, even if the substrate is organic, damage to the substrate due to heating during curing can be suppressed, making it advantageous for use on organic substrates as well.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[material]
The following materials were used in the examples and comparative examples.

<Component (A)>
((Meth)acrylic monomer)
Methyl methacrylate (abbreviated as "MMA"): manufactured by Mitsubishi Gas Chemical Company, Inc. Butyl acrylate (abbreviated as "BA"): manufactured by Nippon Shokubai Co., Ltd. (a monomer having a hydroxyl group)
Hydroxyethyl methacrylate (abbreviated as "HEMA"): manufactured by Nippon Shokubai Co., Ltd. (other monomers)
Acrylic acid (abbreviated as "AA"): (manufactured by Wako Pure Chemical Industries, Ltd.)
(Polymerization catalyst)
2,2'-Azobis(2-methylbutylnitrile) (abbreviated as "V59"): (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 192.3)

<Component (B)>
Average trimer of hexamethylene diisocyanate (isocyanate-modified product) (abbreviated as "N3300": "Sumidur N3300" manufactured by Covestro Japan Co., Ltd.)

<Component (C)>
(Alkoxysilane compound (c1))
3-Glycidyloxypropyltrimethoxysilane (abbreviated as "Ge"): ("OFS-6040" manufactured by Dow Toray Industries, Inc., molecular weight 236.3)
2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (abbreviated as "EC"): ("KBM-303" manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight 246.3)
(Silicate compound (c2))
Ethyl silicate 48 (abbreviated as "ESi48"): (manufactured by Colcoat Co., Ltd.)
Methyl silicate 56 (abbreviated as "MS56"): (manufactured by Mitsubishi Chemical Corporation)
KR-517: (manufactured by Shin-Etsu Chemical Co., Ltd., epoxy-modified ethyl/methyl silicate low condensate, epoxy equivalent 830)
(Condensation catalyst)
Lithium bromide (anhydrous) (abbreviated as "LiBr"): (Kishida Chemical Co., Ltd., molecular weight 86.84)

<Other ingredients>
(solvent)
Propylene glycol methyl ether acetate (abbreviated as "PMA"): (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 132.2)
Methanol (abbreviated as "MeOH"): (Nacalai Tesque, Inc.)
(Metal catalyst)
Dibutyltin compound (trade name "Neostan (registered trademark) U-220H" abbreviated as "U-220H") (manufactured by Nitto Kasei Co., Ltd.).

[Measurement and evaluation methods]
Measurements and evaluations in the examples and comparative examples were carried out by the following methods.

(Weight average molecular weight)
The obtained component (A) or component (C) was measured by gel permeation chromatography (GPC). Measurements were performed using a Tosoh Corporation HLC-8320GPC liquid delivery system, a Tosoh Corporation TSK-GEL H type column, and THF as a solvent, and calculations were made in terms of polystyrene.

(Recoatability)
The resulting cured product (coating film) coated on ABS was cut with a cutter to create 100 10 x 10 cross-cut squares spaced 1 mm apart, and Nichiban Cellophane Tape (registered trademark) was applied to the cuts. The film was then forcefully peeled upward at a 90° angle, and visual inspection was performed to determine whether the cured coating film had peeled from the substrate. Each square where the resin had not peeled was assigned a score of 1, and the adhesion of the cured product was measured (peeling evaluation). Complete adhesion (i.e., no squares where the resin had peeled) was assigned a score of 100, and complete peeling of all the resin was assigned a score of 0. A score of 90 or higher was considered to indicate that the cured product had adhered to the substrate, and a score of less than 90 was considered to indicate that the cured product had peeled from the substrate.

(Chemical resistance)
0.2 g of a 10% aqueous solution of lactic acid was spotted on the resulting cured product (coating film) applied to the ABS, and the coating film was left to stand for 10 minutes in a hot air dryer adjusted to 80° C. Thereafter, the color change and smoothness change of the coating film were visually confirmed, and the chemical resistance of the cured product was evaluated based on the following criteria:
◎ (Good): No change in color, no spot marks, and the surface of the coating film is smooth and free of crimping.
◯ (pass): No change in color, faint spot marks remain, and the surface of the coating is smooth and free of crimping.
Δ (fail): The spot marks were slightly whitened and the surface of the coating film was slightly wrinkled.
× (bad): The spot marks are clearly whitened and the surface of the coating film is clearly wrinkled.

(Scratch resistance)
Using an eraser abrasion tester (manufactured by Mitsumoto Seisakusho Co., Ltd.), a load of 500 g/cm2 was applied to steel wool #0000 on the cured product (coating film) applied to the ABS, and the surface of the cured coating film was moved back and forth 10 times with a stroke length of 10 cm, and the gloss retention of the coating film was measured. Here, the gloss retention of the coating film was a value measured using a BYK Micro Trigloss. The scratch resistance of the cured product was evaluated based on the following criteria:
◯ (Good): Gloss retention is 30% or more.
× (bad): Gloss retention rate is less than 30%.

(Production Example 1: Preparation of component (A-1))
A nitrogen inlet tube, a condenser, and a thermometer were installed in a four-neck flask, and the flask was assembled under slightly pressurized reflux conditions. An oil bath was set up to maintain an internal temperature of 110°C under nitrogen flow, and 114.8 g of PMA was charged and heated to 110°C.

Separately from the four-neck flask, 85.0 g of HEMA, 73.5 g of MMA, 68.9 g of BA, 2.3 g of AA, 10.33 g of V59, and 45.2 g of PMA were added to a brown bottle to prepare a monomer solution for pump addition. The prepared monomer solution was added dropwise to the four-neck flask over a period of four hours using a diaphragm pump.

After the dropwise addition was completed, the mixture was heated for an additional 2 hours to obtain component (A-1). The resulting component (A-1) had a SC (solids content) of 60.0%, a hydroxyl value of 160 mg KOH/g, and a weight-average molecular weight of 8,800. Note that SC indicates the weight percentage of components that did not volatilize when the entire amount of the resulting component (A) was heated to 105°C relative to the total amount of component (A).

(Production Example 2: Preparation of component (A-2))
A nitrogen inlet tube, a condenser, and a thermometer were installed in a four-neck flask, and the flask was assembled under slightly pressurized reflux conditions. An oil bath was set up to maintain an internal temperature of 110°C under nitrogen flow, and 114.8 g of PMA was charged and heated to 110°C.

Separately from the four-neck flask, a brown bottle was charged with 41.3 g of HEMA, 105.7 g of MMA, 80.4 g of BA, 2.3 g of AA, 10.33 g of V59, and 45.2 g of PMA to prepare a monomer solution for pump addition. The prepared monomer solution was added dropwise to the four-neck flask over a period of four hours using a diaphragm pump.

After the dropwise addition was completed, the mixture was heated for an additional 2 hours to obtain component (A-2). The SC of the resulting component (A-2) was 60.0%, the hydroxyl value was 78 mgKOH/g, and the weight-average molecular weight was 8,800.

(Production Example 3: Preparation of component (C-1))
In a 500 mL four-neck flask, 197.8 g of ESi48, 2.15 g of EC, 0.16 g of LiBr, 7.99 g of pure water, 82.8 g of MeOH, and 29.1 g of PMA were added, and the mixture was heated in an oil bath set to 90 ° C. and reacted for 1 hour. Then, 231.7 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 162.0 g of generated methanol, ethanol, and residual water was removed. Then, 10.3 g of PMA was added to adjust the SC, and the reaction system was heated to 130 ° C., and the reaction was allowed to proceed for a further 4 hours, allowing the condensation to proceed, to obtain approximately 400 g of component (C-1). The SC of the resulting component (C-1) was 38%, the weight average molecular weight was 46,000, and the epoxy equivalent was 17,200. SC indicates the weight percentage of components that did not volatilize relative to the total amount of component (C) when the entire amount of the obtained component (C) was heated to 105° C. The epoxy equivalent was calculated by dividing the solid content of the obtained component (C-1) by the number of epoxy groups in component (C-1) calculated from the charged amounts of the raw materials.

(Production Example 4: Preparation of component (C-2))
In a 500 mL four-neck flask, 99.0 g of ESi48, 1.09 g of Ge, 0.04 g of LiBr, 4.00 g of pure water, 41.4 g of MeOH, and 14.6 g of PMA were added, heated in an oil bath set to 90 ° C., and reacted for 1 hour. Thereafter, 115.9 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 81.0 g of generated methanol, ethanol, and residual water was removed. Thereafter, 5.1 g of PMA was added for SC adjustment, and the reaction system was heated to 130 ° C., and the reaction was allowed to proceed for a further 4 hours, allowing the condensation to proceed, to obtain approximately 200 g of component (C-2). The SC of the obtained component (C-2) was 38%, the weight average molecular weight was 133,000, and the epoxy equivalent was 19,610.

(Production Example 5: Preparation of component (C-3))
In a 500 mL four-neck flask, 98.8 g of MS56, 1.07 g of EC, 0.08 g of LiBr, 3.99 g of pure water, 41.4 g of MeOH, and 14.5 g of PMA were added, and the mixture was heated in an oil bath set to 90 ° C. and reacted for 1 hour. Then, 106.6 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 75.6 g of generated methanol, ethanol, and residual water was removed. Then, 5.1 g of PMA was added to adjust the SC, and the reaction system was heated to 130 ° C., and the reaction was continued for a further 4 hours, allowing the condensation to proceed, to obtain approximately 200 g of component (C-3). The SC of the resulting component (C-3) was 38%, the weight average molecular weight was 68,500, and the epoxy equivalent was 9,600.

(Production Example 6: Preparation of component (C-4))
In a 500 mL four-neck flask, 89.9 g of ESi48, 10.74 g of EC, 0.08 g of LiBr, 3.99 g of pure water, 40.7 g of MeOH, and 14.5 g of PMA were added, heated in an oil bath set to 90 ° C., and reacted for 1 hour. Then, 115.9 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 81.0 g of generated methanol, ethanol, and residual water was removed. Then, 5.1 g of PMA was added to adjust the SC, and the reaction system was heated to 130 ° C., and the reaction was allowed to proceed for a further 4 hours, allowing the condensation to proceed, to obtain approximately 200 g of component (C-4). The SC of the obtained component (C-4) was 38%, the weight average molecular weight was 213,000, and the epoxy equivalent was 1,840.

(Production Example 7: Preparation of component (C-5))
In a 500 mL four-neck flask, 50.0 g of ESi48, 53.69 g of EC, 0.08 g of LiBr, 3.99 g of pure water, 30.7 g of MeOH, and 14.6 g of PMA were added, heated in an oil bath set to 90 ° C., and reacted for 1 hour. Thereafter, 115.9 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 81.0 g of generated methanol, ethanol, and residual water was removed. Thereafter, 5.1 g of PMA was added to adjust the SC, and the reaction system was heated to 130 ° C., and the reaction was allowed to proceed for a further 4 hours, allowing the condensation to proceed, to obtain approximately 200 g of component (C-5). The SC of the obtained component (C-5) was 40%, the weight average molecular weight was 49,100, and the epoxy equivalent was 360.

(Production Example 8: Preparation of component (C-6))
In a 500 mL four-neck flask, 100.0 g of ESi48, 0.04 g of LiBr, 4.00 g of pure water, 41.5 g of MeOH, and 14.6 g of PMA were added, heated in an oil bath set to 90 ° C., and reacted for 1 hour. Thereafter, 115.9 g of PMA was added to the reaction system, and atmospheric distillation was performed using an evaporator and an oil bath set to 140 ° C., and a total of 81.0 g of generated methanol, ethanol, and residual water was removed. Thereafter, 5.1 g of PMA was added to adjust the SC, and the reaction system was heated to 130 ° C., and the reaction and condensation were allowed to proceed for a further 4 hours, yielding approximately 200 g of component (C-6). The SC of the resulting component (C-6) was 38%, and the weight-average molecular weight was 16,600. Component (C-6) was not produced using an alkoxysilane having an epoxy group.

[Example 1]
(Preparation of curable composition)
According to the formulation shown in Table 1, component (A) prepared in Production Example 1 and component (C) prepared in Production Example 3 were added to a mayonnaise bottle and mixed using a magnetic stirrer. Then, PMA as a solvent, N3300 as component (B), and U-220H as a catalyst were added and mixed to prepare a curable composition.

The amounts of component (A) and component (C) listed in Table 1 are SC (solids content) amounts. The amount of solvent listed in Table 1 is the total amount of the solvent in component (A) and component (C) prepared in each production example (the amount of component (A) and component (C) prepared in each production example excluding the solids content) and the amount of solvent added separately when combining the components (i.e., the total amount of solvent contained in the curable composition).

(Preparation of cured product (coating film))
The prepared curable composition was applied to a 70 x 150 x 2 mm ABS substrate using a No. 40 bar coater, and the substrate was placed in a hot air dryer set at 80°C for 30 minutes to remove the solvent and cure the applied curable composition, yielding a cured product (coating film) with a dry film thickness of approximately 30 µm. The prepared curable composition was then applied again onto the obtained cured product (coating film) using a No. 40 bar coater, and the substrate was placed in a hot air dryer set at 80°C for 60 minutes to remove the solvent and cure the applied curable composition, yielding a cured product (recoat coating film) with a dry film thickness of approximately 30 µm.

[Examples 2 to 4, Comparative Examples 1 to 9]
Curable compositions and cured products were prepared in the same manner as in Example 1, except that the amounts of each component were changed as shown in Table 1. The resulting cured products were evaluated for recoatability, chemical resistance, and scratch resistance. The results are shown in Table 1.

Table 1 shows that the curable compositions of Examples 1 to 4 have excellent recoatability, chemical resistance, and scratch resistance. In other words, one embodiment of the present invention has been shown to provide a curable composition that can provide a cured product with excellent recoatability, chemical resistance, and scratch resistance.

On the other hand, Table 1 shows that the curable compositions of Comparative Examples 1 to 9 resulted in cured products with insufficient recoatability, chemical resistance, or scratch resistance. In other words, this shows that if the curable composition does not satisfy the requirements of this curable composition, the recoatability, chemical resistance, or scratch resistance of the resulting cured product will be poor.

This curable composition can provide a cured product that has excellent recoatability, chemical resistance, and scratch resistance, making it suitable for use in paints and other applications.

Claims (7)

A curable composition comprising (meth)acrylic polyol (A), polyisocyanate (B), and co-condensate (C) of an alkoxysilane compound having an epoxy group and a silicate compound,
the (meth)acrylic polyol (A) has a hydroxyl value of 100 to 200 mgKOH/g;
the epoxy equivalent of the co-condensate (C) is 3600 or more,
The curable composition comprises 1 to 10 parts by weight of the co-condensate (C) relative to 100 parts by weight of the (meth)acrylic polyol (A) . The curable composition of claim 1 , wherein the co-condensate (C) comprises an epoxycyclohexyl group. The curable composition according to claim 1 or 2 , wherein the (meth)acrylic polyol (A) has a weight average molecular weight of 2,000 to 12,000. The curable composition according to any one of claims 1 to 3 , wherein the polyisocyanate (B) is 40 to 70 parts by weight based on 100 parts by weight of the (meth)acrylic polyol (A). The curable composition according to any one of claims 1 to 4 , which is a multi-component curable composition. a first liquid containing the (meth)acrylic polyol (A) and the co-condensate (C);
The curable composition according to claim 5 , further comprising: a second liquid containing the polyisocyanate (B). A cured product obtained by curing the curable composition according to any one of claims 1 to 6 .