Hardening components

Abstract

To provide a curable composition capable of forming a curable article excellent in chemical resistance that suppresses degradation caused by alkaline agents.SOLUTION: A curable composition of the invention contains a polyoxyalkylene-based polymer (A) having a hydrolyzable silyl group and an acrylic polymer (B) having a hydrolyzable silyl group. The backbone chain of the polyoxyalkylene-based polymer (A) having a hydrolyzable silyl group has a branched chain. The acrylic polymer (B) having a hydrolyzable silyl group has a number average molecular weight of 10,000-50,000. The hydrolyzable silyl group of the acrylic polymer (B) having a hydrolyzable silyl group is a trialkoxysilyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a curable composition. [Background technology]

[0002] Modified silicone curable compositions containing polyoxyalkylene polymers having hydrolyzable silyl groups are widely used as sealants and adhesives because they are safe as they do not generate toxic substances during curing, and the resulting cured products have excellent flexibility (elasticity).

[0003] Common areas where sealants are used include kitchens, bathrooms, toilets, and washrooms—areas prone to mold and slime buildup. Therefore, alkaline detergents are often used to clean these areas.

[0004] Patent Document 1 proposes a sealing material composition comprising an acrylic polymer mainly composed of an acrylic acid ester having 1 to 20 carbon atoms in the ester portion, having a glass transition temperature of 10°C or less, and a weight-average molecular weight of 500 to 20,000, in an amount of 1 to 100 parts by weight per 100 parts by weight of a sealing substrate. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-207157 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the sealing material composition disclosed in Patent Document 1 has the problem of having low chemical resistance to alkaline detergents and degrading when chemicals such as detergents are used.

[0007] The present invention provides a curable composition that can produce a cured product with excellent chemical resistance in which degradation by alkaline chemicals is suppressed. [Means for solving the problem]

[0008] The curable composition of the present invention, A polyoxyalkylene polymer (A) having hydrolyzable silyl groups, It comprises an acrylic polymer (B) having a hydrolyzable silyl group, The main chain of the polyoxyalkylene polymer (A) having the above hydrolyzable silyl group has a branched chain, The above acrylic polymer (B) having hydrolyzable silyl groups has a number-average molecular weight of 10,000 to 50,000, In the above-mentioned acrylic polymer (B) having a hydrolyzable silyl group, the hydrolyzable silyl group is a trialkoxysilyl group.

[0009] [Polyoxyalkylene polymer having hydrolyzable silyl groups (A)] The curable composition contains a polyoxyalkylene polymer (A) having hydrolyzable silyl groups (hereinafter sometimes simply referred to as "polyoxyalkylene polymer (A)"). The polyoxyalkylene polymer (A) having hydrolyzable silyl groups makes it possible to provide a curable composition that can be cured by moisture present in the atmosphere or in joints.

[0010] The polyoxyalkylene polymer (A) preferably has hydrolyzable silyl groups in its molecule, and more preferably has hydrolyzable silyl groups at its molecular ends. More preferably, the hydrolyzable silyl groups are attached to only one of the two ends of the main chain, or to both ends. When hydrolyzable silyl groups are attached to the ends of the main chain, it is possible to maintain the excellent flexibility of the cured product of the curable composition, impart excellent normal adhesion, and impart excellent chemical resistance. In the case of polyoxyalkylene polymer (A) having multiple hydrolyzable silyl groups in its molecule, the hydrolyzable silyl groups may be the same or different from each other.

[0011] Examples of the hydrolyzable silyl group include a silicon-containing group having a hydrolyzable group bonded to a silicon atom or a silanol group, which causes a condensation reaction by using a catalyst or the like as necessary in the presence of moisture or a crosslinking agent. The silanol group means a functional group [≡Si-OH, formula (1)] in which a hydroxy group is directly bonded to a silicon atom. In formula (1), *1 to *3 are bonds and represent single bonds.

[0012] [Chemical formula]

[0013] The hydrolyzable group of the hydrolyzable silyl group is not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, an alkenyloxy group, and the like.

[0014] Among them, as the hydrolyzable silyl group, an alkoxysilyl group is preferable because it can impart excellent chemical resistance while maintaining the flexibility of the cured product of the curable composition.

[0015] The alkoxysilyl group preferably has a structure represented by -SiR 7 j (OR 8 ) 3-j In the formula, R 7 represents an alkyl group having 1 to 20 carbon atoms which may have a substituent or a hydrogen atom. R 8 represents an alkyl group having 1 to 6 carbon atoms. j represents an integer of 0 to 2.

[0016] Examples of the alkoxysilyl group include trialkoxysilyl groups such as trimethoxysilyl group, triethoxysilyl group, triisopropoxysilyl group, and triphenoxysilyl group; dialkoxysilyl groups such as propyldimethoxysilyl group, methyldimethoxysilyl group, and methyldiethoxysilyl group; and monoalkoxysilyl groups such as dimethylmethoxysilyl group and dimethylethoxysilyl group. Among them, dialkoxysilyl groups and trialkoxysilyl groups are preferred because they can impart excellent water-resistant adhesiveness to the cured product of the curable composition. Dimethoxysilyl group and trimethoxysilyl group are preferred, and dimethoxysilyl group is more preferred.

[0017] The polyoxyalkylene polymer (A) preferably has an average of 1.0 to 4.0, more preferably 1.0 to 3.0 hydrolyzable silyl groups per molecule. When the number of hydrolyzable silyl groups in the polyoxyalkylene polymer (A) is 1.0 or more, the curability and chemical resistance of the curable composition are improved. When the number of hydrolyzable silyl groups in the polyoxyalkylene polymer (A) is 4.0 or less, the elongation of the cured product of the curable composition is improved.

[0018] In the present invention, the average number of hydrolyzable silyl groups per molecule in the polyoxyalkylene polymer is 1 calculated based on the concentration of hydrolyzable silyl groups in the polyoxyalkylene polymer determined by H-NMR and the number average molecular weight of the polyoxyalkylene polymer determined by the GPC method.

[0019] The polyoxyalkylene polymer (A) having a hydrolyzable silyl group can be produced, for example, by reacting a polyoxyalkylene polymer having a functional group such as a hydroxyl group at the terminal with an organic compound having an active group and an unsaturated group reactive with this functional group, and then subjecting the obtained reaction product to hydrosilylation by the action of a hydrosilane having a hydrolyzable group.

[0020] The main chain of the polyoxyalkylene polymer (A) having a hydrolyzable silyl group has a branched chain. Here, the "main chain" of the polyoxyalkylene polymer refers to the longest molecular chain in the molecule. The length of the molecular chain can be determined by the number of atoms constituting the molecular chain, and it is judged that the molecular chain is longer as the number of atoms is larger.

[0021] When the main chain of the polyoxyalkylene polymer (A) has a branched chain, in the cured product of the curable composition, the branched chains are intertwined to reduce the intermolecular gaps, thereby reducing the absorbability of chemicals in the cured product. Thus, by reducing the absorbability of chemicals in the cured product, the chemical resistance of the cured product is improved.

[0022] The main chain of the polyoxyalkylene polymer (A) is preferably a polymer containing a repeating unit represented by the general formula (1). -(O-R 1 ) n - (1) (In the formula, R 1 represents an alkylene group having 1 to 14 carbon atoms, and n is the number of repeating units and is a positive integer.)

[0023] In the present invention, the alkylene group is a divalent atomic group generated by removing (extracting) two hydrogen atoms bonded to two different carbon atoms in an aliphatic saturated hydrocarbon, and includes both linear and branched atomic groups.

[0024] Examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], a hexylene group, and the like.

[0025] The main chain of the polyoxyalkylene polymer (A) may consist of only one kind of repeating unit or may consist of two or more kinds of repeating units.

[0026] Examples of the main chain skeleton of the polyoxyalkylene polymer (A) include polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and polyoxypropylene-polyoxybutylene copolymer. Polyoxypropylene is preferred because it improves the rubber elasticity of the cured product of the curable composition.

[0027] In polyoxyalkylene polymers (A), a "branched chain" in the main chain refers to a molecular chain containing two or more carbon atoms. Therefore, for example, methyl groups are not included in branched chains.

[0028] As described above, the branched chains in the main chain of the polyoxyalkylene polymer (A) can reduce the gaps between molecules due to entanglement between molecular chains in the cured product of the curable composition, so it is preferable that they have a certain molecular chain length. Therefore, the branched chains have two or more carbon atoms. The number of carbon atoms in the branched chains can reduce the viscosity of the curable composition and improve its handling properties, so it is preferable that they be 14 or less, more preferably 13 or less, and even more preferably 12 or less.

[0029] The branched chains in the main chain of the polyoxyalkylene polymer (A) are not particularly limited as long as they have two or more carbon atoms, but polyoxyalkylene chains are preferred because they improve the chemical resistance of the cured product of the curable composition.

[0030] The branched chains in the main chain of the polyoxyalkylene polymer (A) preferably have a repeating structure containing repeating units represented by general formula (2). -(OR 2 ) m - (2) (In the formula, R 2 (where m represents an alkylene group with 1 to 14 carbon atoms, and m is an integer greater than or equal to 2, representing the number of repeating units.)

[0031] The branched chains in the main chain of a polyoxyalkylene polymer may consist of only one type of repeating unit, or they may consist of two or more types of repeating units.

[0032] Examples of branched chain skeletons in the main chain of polyoxyalkylene polymer (A) include polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and polyoxypropylene-polyoxybutylene copolymer. Polyoxypropylene is preferred because the cured product of the curable composition maintains excellent flexibility while exhibiting excellent water-resistant adhesion.

[0033] In the polyoxyalkylene polymer (A), it is preferable that the main chain skeleton structure having branched chains includes the structure represented by general formula (3).

[0034] [ka] (In the formula, R 3 and R 5 Each of these represents an alkylene group with 1 to 14 carbon atoms. 4 R represents a trivalent group of atoms formed by removing (extracting) any hydrogen atom from an alkylene group. 6 R is an alkylene group with 1 to 6 carbon atoms. 3 , R 5 and R 6 x and y are positive integers representing the number of repeating units. z is an integer greater than or equal to 2, representing the number of repeating units.

[0035] Polyoxyalkylene polymers (A) having hydrolyzable silyl groups are preferred because the cured product of the curable composition maintains excellent flexibility and has excellent chemical resistance.

[0036] The number average molecular weight of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups is preferably 5,000 or more, more preferably 10,000 or more, more preferably 12,000 or more, and more preferably 13,000 or more. The number average molecular weight of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups is preferably 40,000 or less, more preferably 35,000 or less, more preferably 30,000 or less, and more preferably 20,000 or less. If the number average molecular weight of the polyoxyalkylene polymer (B) is 5,000 or more, the cured product of the curable composition can be given excellent elongation. If the number average molecular weight of the polyoxyalkylene polymer (A) is 40,000 or less, the viscosity of the curable composition can be kept low, the handling of the curable composition can be improved, and the curable composition can be given excellent coating properties.

[0037] The molecular weight distribution (Mw / Mn) of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.5 or less. A molecular weight distribution (Mw / Mn) of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups is preferably 2.0 or less because the cured product of the curable composition has good elongation.

[0038] In this invention, the number-average molecular weight and weight-average molecular weight of the polyoxyalkylene polymer are polystyrene-converted values ​​measured by GPC (gel permeation chromatography). Specifically, 6 to 7 mg of the polyoxyalkylene polymer is taken, the taken polyoxyalkylene polymer is supplied to a test tube, and then an o-DCB (orthodichlorobenzene) solution containing 0.05% by mass of BHT (dibutylhydroxytoluene) is added to the test tube to dilute the polyoxyalkylene polymer to a concentration of 1 mg / mL to prepare a diluted solution.

[0039] Using a dissolution filtration apparatus, the above diluted solution is shaken at 145°C at a rotation speed of 25 rpm for 1 hour to dissolve the polyoxyalkylene polymer in an o-DCB solution containing BHT, which is then used as the measurement sample. The number-average molecular weight and weight-average molecular weight of the polyoxyalkylene polymer can be measured using this measurement sample by the GPC method.

[0040] In this invention, the number-average molecular weight and weight-average molecular weight of the polyoxyalkylene polymer can be measured, for example, using the following measuring device and conditions. Measuring device: TOSOH Corporation, product name "HLC-8121GPC / HT" Measurement conditions: Column: TSKgelGMHHR-H(20)HT x 3 TSKguardcolumn-HHR(30)HT x 1 bottle Mobile phase: o-DCB 1.0mL / min Sample concentration: 1 mg / mL Detector: Blythe refractometer Standard material: Polystyrene (manufactured by TOSOH Corporation, molecular weight: 500-8,420,000) Elution conditions: 145℃ SEC temperature: 145℃

[0041] [Acrylic polymer having hydrolyzable silyl groups (B)] The curable composition contains an acrylic polymer (B) having hydrolyzable silyl groups. The use of acrylic polymer (B) can improve the chemical resistance of the cured product of the curable composition. Note that acrylic polymer (B) having hydrolyzable silyl groups is sometimes simply referred to as "acrylic polymer (B)".

[0042] Since the acrylic polymer (B) has hydrolyzable silyl groups, the acrylic polymer (B) can be incorporated into the cured product of the curable composition, thereby improving the chemical resistance of the cured product.

[0043] The hydrolyzable silyl group of the acrylic polymer (B) is a trialkoxysilyl group, which allows the cured product of the curable composition to maintain excellent durability over a long period of time. Examples of trialkoxysilyl groups include trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, and triphenoxysilyl groups, with trimethoxysilyl being preferred.

[0044] The acrylic polymer (B) has, on average, 1.0 to 4.0, more preferably 1.3 to 3.0, and more preferably 1.5 to 2.0 hydrolyzable silyl groups per molecule. When the average number of hydrolyzable silyl groups per molecule of the acrylic polymer (B) is 1.0 or more, the chemical resistance of the cured product of the curable composition is improved. When the average number of hydrolyzable silyl groups per molecule of the acrylic polymer (B) is 4.0 or less, the rubber elasticity of the cured product of the curable composition is improved.

[0045] Furthermore, the average number of hydrolyzable silyl groups per molecule in the acrylic polymer (B) is: 1 It can be calculated based on the concentration of hydrolyzable silyl groups in the acrylic polymer (B) determined by 1H-NMR, and the number-average molecular weight of the acrylic polymer (B) determined by GPC.

[0046] The main chain skeleton of acrylic polymer (B) is an acrylic polymer (B) obtained by radical polymerization of (meth)acrylate monomers. (Meth)acrylate refers to either methacrylate or acrylate.

[0047] Specifically, the (meth)acrylate monomers that constitute the main chain of the acrylic polymer (B) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, and isomiristyl (meth)acrylate. acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trim Examples include tyrolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy(meth)acrylate, polyester(meth)acrylate, urethane(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 5-hydroxypentyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 3-hydroxy-3-methylbutyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 2-[acryloyloxy]ethyl-2-hydroxyethylphthalic acid, and 2-[acryloyloxy]ethyl-2-hydroxypropylphthalic acid.As (meth)acrylate monomers, alkyl (meth)acrylates having 1 to 6 carbon atoms in the alkyl group are preferred, alkyl (meth)acrylates having 1 to 5 carbon atoms in the alkyl group are more preferred, and alkyl acrylates having 1 to 5 carbon atoms in the alkyl group are even more preferred. As (meth)acrylate monomers, methyl (meth)acrylate and butyl (meth)acrylate are preferred, butyl (meth)acrylate is more preferred, and butyl acrylate is even more preferred. These (meth)acrylate monomers may be used alone or in combination of two or more.

[0048] In acrylic polymer (B), it is also possible to copolymerize with other monomers. Examples of such monomers include styrene, indene, styrene derivatives such as α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, and divinylbenzene; compounds having vinyl ester groups such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl benzoate, and vinyl cinnamate; maleic anhydride, N-vinylpyrrolidone, N-vinylmorpholin, (meth)acrylonitrile, (meth)acrylamide, N-cyclohexylmaleimide, N-phenylmaleimide, N-laurylmaleimide, N-benzylmaleimide, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, 2-chloroethyl vinyl ether, ethylene glycol butyl vinyl ether, and triethylene Examples of compounds containing a vinyloxy group include glycol methyl vinyl ether, (4-vinyloxy)butyl benzoate, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, butane-1,4-diol-divinyl ether, hexane-1,6-diol-divinyl ether, cyclohexane-1,4-dimethanol-divinyl ether, di(4-vinyloxy)butyl isophthalate, di(4-vinyloxy)butyl glutarate, di(4-vinyloxy)butyl succinate trimethylolpropane trivinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane-1,4-dimethanol monovinyl ether, diethylene glycol monovinyl ether, 3-aminopropyl vinyl ether, 2-(N,N-diethylamino)ethyl vinyl ether, urethane vinyl ether, and polyester vinyl ether. These monomers may be used individually or in combination of two or more.

[0049] In particular, a copolymer of butyl (meth)acrylate and methyl (meth)acrylate is preferred as the main chain skeleton of the acrylic polymer (B), a copolymer of butyl acrylate and methyl methacrylate is more preferred, and a homopolymer of butyl acrylate is even more preferred. An acrylic polymer (B) whose main chain skeleton consists of the above copolymer can be used to obtain a curable composition that can form a cured product with excellent rubber elasticity after curing.

[0050] The polymerization method for the acrylic polymer (B) is not particularly limited, and known methods can be used. Examples include free radical polymerization, anionic polymerization, cationic polymerization, UV radical polymerization, living anionic polymerization, living cationic polymerization, and living radical polymerization.

[0051] The method for introducing hydrolyzable silyl groups into the acrylic polymer (B) is not particularly limited, and known methods can be used, such as hydrosilylation by reacting an acrylic polymer (B) having an unsaturated group in its molecule with a hydrosilane having a hydrolyzable silyl group.

[0052] The number-average molecular weight of the acrylic polymer (B) is 10,000 or more, preferably 15,000 or more, and more preferably 20,000 or more. When the number-average molecular weight of the acrylic polymer (B) is 10,000 or more, the rubber elasticity of the cured product of the curable composition is improved.

[0053] The number-average molecular weight of the acrylic polymer (B) is 50,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less. When the number-average molecular weight of the acrylic polymer (B) is 50,000 or less, the rubber elasticity of the cured product of the curable composition is improved.

[0054] In this invention, the number-average molecular weight and weight-average molecular weight of the acrylic polymer (B) refer to the polystyrene-converted values ​​measured by GPC (gel permeation chromatography). For GPC measurements, for example, a Tosoh Shodex KF800D can be used as the GPC column, and chloroform or the like can be used as the solvent.

[0055] In this invention, the number-average molecular weight and weight-average molecular weight of the acrylic polymer can be measured, for example, using the following measuring device and measurement conditions. Measuring device: TOSOH Corporation, product name "HLC-8121GPC / HT" Measurement conditions: Column: TSKgelGMHHR-H(20)HT x 3 TSKguardcolumn-HHR(30)HT x 1 bottle Mobile phase: o-DCB 1.0mL / min Sample concentration: 1 mg / mL Detector: Blythe refractometer Standard material: Polystyrene (manufactured by TOSOH Corporation, molecular weight: 500-8,420,000) Elution conditions: 145℃ SEC temperature: 145℃

[0056] In the curable composition, the mass ratio of the content of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups to the content of the acrylic polymer (B) having hydrolyzable silyl groups [content of polyoxyalkylene polymer (A) having hydrolyzable silyl groups / content of acrylic polymer (B) having hydrolyzable silyl groups] is preferably 0.01 or higher, more preferably 0.05 or higher, more preferably 0.07 or higher, more preferably 0.09 or higher, more preferably 0.12 or higher, more preferably 0.3 or higher, more preferably 0.5 or higher, and more preferably 0.8 or higher. When the above mass ratio is 0.01 or higher, the coating properties of the curable composition are improved, and the cured product has excellent elongation.

[0057] In the curable composition, the mass ratio of the content of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups to the content of the acrylic polymer (B) having hydrolyzable silyl groups [mass of polyoxyalkylene polymer (A) having hydrolyzable silyl groups / mass of acrylic polymer (B) having hydrolyzable silyl groups] is preferably 5.0 or less, more preferably 3.0 or less, more preferably 2.0 or less, and more preferably 1.5 or less. When the above mass ratio is 5.0 or less, the chemical resistance of the cured product of the curable composition is improved.

[0058] In a curable composition, preferably, the mass ratio of the content of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups to the content of the acrylic polymer (B) having hydrolyzable silyl groups [content of polyoxyalkylene polymer (A) having hydrolyzable silyl groups / content of acrylic polymer (B) having hydrolyzable silyl groups] is set to 0.01 to 2, and the number average molecular weight of the acrylic polymer (B) having hydrolyzable silyl groups is set to 10,000 to 50,000. This makes it possible to improve both the chemical resistance and rubber elasticity of the cured product of the curable composition.

[0059] [Filling material] The curable composition preferably contains a filler. The presence of a filler makes it possible to provide a curable composition that exhibits excellent rubber elasticity after curing.

[0060] The filler material is not particularly limited, and examples include inorganic fillers such as calcium carbonate, magnesium carbonate, calcium oxide, hydrated silicic acid, anhydrous silicic acid, finely powdered silica, calcium silicate, titanium dioxide, clay, talc, carbon black, and glass balloons. These fillers may be used alone or in combination of two or more. Among these, calcium carbonate is preferably used as the filler material.

[0061] Precipitating calcium carbonate and heavy calcium carbonate are preferred. Precipitating calcium carbonate includes light calcium carbonate and colloidal calcium carbonate.

[0062] As the calcium carbonate, either precipitated calcium carbonate or heavy calcium carbonate may be used, or both may be used. In particular, the use of precipitated calcium carbonate and heavy calcium carbonate is preferred. By using precipitated calcium carbonate and heavy calcium carbonate in combination, thixotropy can be imparted to the curable composition.

[0063] The content of the filler in the curable composition is preferably 10 to 500 parts by mass, more preferably 15 to 300 parts by mass, and even more preferably 20 to 200 parts by mass, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) and the acrylic polymer (B) having hydrolyzable silyl groups.

[0064] When using heavy calcium carbonate and precipitated calcium carbonate, the content of precipitated calcium carbonate in the curable composition is preferably 10 to 300 parts by mass, and more preferably 10 to 200 parts by mass, per 100 parts by mass of the total amount of polyoxyalkylene polymer (A) and acrylic polymer (B) having hydrolyzable silyl groups.

[0065] When using heavy calcium carbonate and precipitated calcium carbonate, the content of heavy calcium carbonate in the curable composition is preferably 30 to 500 parts by mass, more preferably 30 to 350 parts by mass, and particularly preferably 30 to 150 parts by mass, based on 100 parts by mass of the total of the polyoxyalkylene polymer (A) and the acrylic polymer (B).

[0066] The average particle size of calcium carbonate is preferably 0.01 to 5 μm, more preferably 0.05 to 2.5 μm, and even more preferably 0.1 to 2 μm. Calcium carbonate having such an average particle size can provide a curable composition capable of forming a cured product with excellent adhesive strength, mechanical strength, and elongation. The particle size of calcium carbonate is defined as the spherical volume equivalent diameter, and the average particle size of calcium carbonate is the particle size at which the cumulative distribution (cumulative curve), when the volume-based particle size distribution measured using the laser scattering method is represented with the total volume as 100%, reaches 50%.

[0067] Furthermore, it is preferable that the calcium carbonate is surface-treated with fatty acids or fatty acid esters. Surface-treated calcium carbonate can impart thixotropy to the curable composition and suppress the aggregation of calcium carbonate.

[0068] The content of the inorganic filler in the curable composition is preferably 1 part by mass or more, preferably 30 parts by mass or more, more preferably 50 parts by mass or more, more preferably 80 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. The content of the inorganic filler in the curable composition is preferably 800 parts by mass or less, preferably 600 parts by mass or less, more preferably 450 parts by mass or less, more preferably 300 parts by mass or less, and more preferably 200 parts by mass or less, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. When the content of the inorganic filler is 1 part by mass or more, the chemical resistance of the cured product of the curable composition to the acrylic properties can be improved. When the inorganic filler content is 800 parts by mass or less, the increase in viscosity of the curable composition can be suppressed, and the workability of the curable composition is improved.

[0069] [Dehydrating agent] The curable composition preferably further contains a dehydrating agent. The dehydrating agent helps to suppress the curable composition from hardening due to moisture contained in the air or other sources when it is stored.

[0070] Examples of dehydrating agents include silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane; and ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. These dehydrating agents may be used alone or in combination of two or more. Among these, vinyltrimethoxysilane is preferred.

[0071] The content of the dehydrating agent in the curable composition is preferably 0.5 to 20 parts by mass, and more preferably 1 to 15 parts by mass, based on 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. If the content of the dehydrating agent is 0.5 parts by mass or more, the effect of the dehydrating agent is sufficiently obtained. Furthermore, if the content of the dehydrating agent is 20 parts by mass or less, the curable composition has excellent curability.

[0072] [Silanol condensation catalyst] The curable composition preferably contains a silanol condensation catalyst. A silanol condensation catalyst is a catalyst that promotes the dehydration condensation reaction between silanol groups formed by the hydrolysis of hydrolyzable silyl groups contained in polyoxyalkylene polymers having hydrolyzable silyl groups.

[0073] Examples of silanol condensation catalysts include organotin compounds such as 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distanoxane, dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis(dibutyltin laurate) oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(monoester maleate), tin octoate, dibutyltin octoate, dioctyltin oxide, dibutyltin bis(triethoxysilicate), bis(dibutyltin bistriethoxysilicate) oxide, and dibutyltin oxybisethoxysilicate; and organotitanium compounds such as tetra-n-butoxytitanate and tetraisopropoxytitanate. These silanol condensation catalysts may be used individually or in combination of two or more.

[0074] As the silanol condensation catalyst, 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distanoxane is preferred. With such a silanol condensation catalyst, the curing rate of the curable composition can be easily adjusted.

[0075] The content of the silanol condensation catalyst in the curable composition is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. If the content of the silanol condensation catalyst is 1 part by mass or more, the curing rate of the curable composition can be increased, thereby shortening the time required for curing the curable composition. If the content of the silanol condensation catalyst is 10 parts by mass or less, the curable composition will have an appropriate curing rate, and the handling of the curable composition can be improved.

[0076] [Other additives] The curable composition may contain other additives such as thixotropic agents, antioxidants, UV absorbers, pigments, dyes, anti-settling agents, and solvents. Among these, thixotropic agents, UV absorbers, and antioxidants are particularly preferred.

[0077] [Tixotropic agents] The thixotropic agent can be any agent capable of inducing thixotropy in the curable composition. Preferred thixotropic agents include hydrogenated castor oil, fatty acid bisamides, and fumed silica.

[0078] The content of the thixotropic agent in the curable composition is preferably 0.1 to 200 parts by mass, and more preferably 1 to 150 parts by mass, based on 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. When the content of the thixotropic agent is 0.1 parts by mass or more, thixotropy can be effectively imparted to the curable composition. Furthermore, when the content of the thixotropic agent is 200 parts by mass or less, the curable composition has an appropriate viscosity, and the handling of the curable composition is improved.

[0079] [UV absorber] Examples of UV absorbers include benzotriazole-based UV absorbers and benzophenone-based UV absorbers, with benzotriazole-based UV absorbers being preferred. The amount of UV absorber in the curable composition is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups.

[0080] [Antioxidant] Examples of antioxidants include hindered phenol antioxidants, monophenol antioxidants, bisphenol antioxidants, and polyphenol antioxidants, with hindered phenol antioxidants being preferred. The content of the antioxidant in the curable composition is preferably 0.1 to 20 parts by mass, and more preferably 0.3 to 10 parts by mass, per 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups.

[0081] [Light stabilizer] The curable composition preferably contains a hindered amine-based light stabilizer. A hindered amine-based light stabilizer makes it possible to provide a curable composition that can maintain excellent rubber elasticity for a longer period after curing.

[0082] Examples of hindered amine-based light stabilizers include a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6 Examples include polycondensates with (-tetramethyl-4-piperidyl)butylamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], and polycondensates of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol.

[0083] As a hindered amine-based light stabilizer, NOR-type hindered amine-based light stabilizers are preferred. NOR-type hindered amine-based light stabilizers can provide a curable composition in which the decrease in rubber elasticity over time after curing is suppressed.

[0084] NOR-type hindered amine light stabilizers have a NOR structure in which an alkyl group (R) is bonded to a nitrogen atom (N) in the piperidine ring skeleton via an oxygen atom (O). The number of carbon atoms in the alkyl group in the NOR structure is preferably 1 to 20, more preferably 1 to 18, and particularly preferably 18. Examples of alkyl groups include linear alkyl groups, branched alkyl groups, and cyclic alkyl groups (saturated alicyclic hydrocarbon groups).

[0085] Examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl groups. Examples of branched alkyl groups include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups (saturated alicyclic hydrocarbon groups) include cyclopentyl, cyclohexyl, and cyclooctyl groups. Furthermore, the hydrogen atoms constituting the alkyl group may be substituted with halogen atoms (e.g., fluorine, chlorine, bromine, etc.) or hydroxyl groups.

[0086] Examples of NOR-type hindered amine light stabilizers include those represented by the following formula (4).

[0087] [ka]

[0088] When using a NOR-type hindered amine light stabilizer, it is preferable to use the NOR-type hindered amine light stabilizer in combination with a benzotriazole-based ultraviolet absorber or a triazine-based ultraviolet absorber. This makes it possible to provide a curable composition in which the decrease in rubber elasticity over time after curing is more suppressed.

[0089] The content of the hindered amine-based light stabilizer in the curable composition is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups.

[0090] [Aminosilane coupling agent] The curable composition preferably contains an aminosilane coupling agent. By using an aminosilane coupling agent, the rubber elasticity and adhesiveness of the cured product of the curable composition can be improved. An aminosilane coupling agent refers to a compound containing a silicon atom to which an alkoxy group is bonded in one molecule, and a functional group containing a nitrogen atom.

[0091] Examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N'-bis-[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(trimethoxysilyl)propyl]hexamethylenediamine, and N,N'-bis-[3-(triethoxysilyl)propyl]hexamethylenediamine. These aminosilane coupling agents may be used alone or in combination of two or more.

[0092] Among these, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane are preferred as aminosilane coupling agents, with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane being more preferred.

[0093] The content of the aminosilane coupling agent in the curable composition is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total amount of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups and the acrylic polymer (B) having hydrolyzable silyl groups. When the content of the aminosilane coupling agent is within the above range, the rubber elasticity and adhesiveness of the cured product of the curable composition can be improved.

[0094] The curable composition can be produced by uniformly mixing a polyoxyalkylene polymer (A) having hydrolyzable silyl groups and an acrylic polymer (B) having hydrolyzable silyl groups, along with additives as needed, using general-purpose means under a vacuum atmosphere.

[0095] Because the curable composition has excellent adhesive properties and can form a cured product that maintains excellent rubber elasticity over a long period of time, it can be used in various applications such as sealants, coatings, adhesives, and paints.

[0096] In particular, cured products obtained by curing the curable composition with moisture have excellent chemical resistance. On the other hand, areas with water, such as kitchens, bathrooms, toilets, and washrooms, are prone to mold and slime growth, and alkaline detergents and other chemicals are often used to remove them. The cured products of the above-mentioned curable composition have excellent resistance to alkaline chemicals, and even when in contact with chemicals, deterioration is suppressed, allowing them to maintain excellent rubber elasticity over a long period of time.

[0097] A method for obtaining a sealing structure by applying a curable composition to gaps involves filling the gap with the curable composition, allowing it to cure by moisture in the air or in the materials constituting the gap. The resulting sealing structure has structural members of the building structure and a cured product of the curable composition filled into the gaps formed between adjacent structural members. Examples of structural members of the building structure include walls such as exterior walls, interior walls, and ceilings, as well as washbasins, bathtubs, and system kitchen bodies, with structural members constituting water-related areas being preferred. [Effects of the Invention]

[0098] Since the curable composition of the present invention has the above-described structure, it has excellent chemical resistance to alkalis, and is particularly preferable for use in construction sites where chemicals may be used, such as areas with water. [Modes for carrying out the invention]

[0099] The present invention will be described more specifically below with reference to examples, but the present invention is not limited thereto. [Examples]

[0100] The following raw materials were used in the production of the curable compositions of the examples and comparative examples. [Polyoxyalkylene polymer having hydrolyzable silyl groups (A)] • Polyoxyalkylene polymer (A1) (a polyoxypropylene polymer whose main chain is polyoxypropylene and has branched chains; hydrolyzable silyl groups (bonded to the ends of the main chain): dimethoxysilyl groups; average number of dimethoxysilyl groups per molecular weight: 3.0; number of carbon atoms in branched chains: 2 or more and 12 or less; number average molecular weight: 30,000; molecular weight distribution (Mw / Mn): 1.1; manufactured by AGC Inc., product name "Excester S6735D")

[0101] • Polyoxyalkylene polymer (A2) (a polyoxypropylene polymer whose main chain is polyoxypropylene and has branched chains; hydrolyzable silyl groups (bonded to the ends of the main chain): dimethoxysilyl groups; average number of dimethoxysilyl groups per molecular weight: 3.0; number of carbon atoms in branched chains: 2 or more and 12 or less; number average molecular weight: 38,000; molecular weight distribution (Mw / Mn): 1.4; manufactured by Kaneka Corporation; product name "S303")

[0102] • Polyoxyalkylene polymer (A3) (a polyoxypropylene polymer whose main chain is polyoxypropylene and has branched chains; hydrolyzable silyl groups (bonded to the ends of the main chain): dimethoxysilyl groups; average number of dimethoxysilyl groups per molecular weight: 3.0; number of carbon atoms in branched chains: 2 or more and 12 or less; number average molecular weight: 8,000; molecular weight distribution (Mw / Mn): 1.1; manufactured by AGC Inc., product name "Excestar S6250")

[0103] • Polyoxyalkylene polymer (A4) (a polyoxypropylene polymer in which the main chain is a linear polyoxypropylene chain, the main chain has no branched chains, hydrolyzable silyl groups (bonded to both ends of the main chain): dimethoxysilyl groups, average number of dimethoxysilyl groups per molecular weight: 2.0, hydrolyzable silyl groups are bonded to the ends of the main chain via alkylene groups, number average molecular weight: 25,000, molecular weight distribution (Mw / Mn): 1.1, manufactured by AGC Inc., product name "Excestar S4530")

[0104] [Acrylic polymer having hydrolyzable silyl groups (B)] • Acrylic polymer (B1) (An acrylic polymer having trimethoxysilyl groups at the terminal or side chains of the main chain skeleton; main chain skeleton: butyl acrylate homopolymer; manufactured by Soken Chemical Co., Ltd., product name "NE-4003B"; number average molecular weight: 40,000; average number of trimethoxysilyl groups per molecular weight: 2.0)

[0105] • Acrylic polymer (B2) (An acrylic polymer having trimethoxysilyl groups at the terminal or side chains of the main chain skeleton; main chain skeleton: butyl acrylate homopolymer; manufactured by Toagosei Co., Ltd., product name "US6150"; number average molecular weight: 4,000; average number of trimethoxysilyl groups per molecular weight: 0.3)

[0106] • Acrylic polymer (B3) (An acrylic polymer having dimethoxysilyl groups at the terminal or side chains of the main chain skeleton; main chain skeleton: butyl acrylate homopolymer; manufactured by Kaneka Corporation, product name "SA310S"; number average molecular weight: 28,000; average number of trimethoxysilyl groups per molecular weight: 2.0)

[0107] [Filling material] • Precipitating calcium carbonate (manufactured by Maruo Calcium Co., Ltd., product name "Calfine 200M", average particle size: 0.5 μm)

[0108] [Dehydrating agent] • Vinyltrimethosilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-1003")

[0109] [Silanol condensation catalyst] • Silanol condensation catalyst (1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distanoxane, manufactured by Nitto Chemical Co., Ltd., product name "Neostan U-130")

[0110] [Aminosilane coupling agent] • Aminosilane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-603")

[0111] (Examples 1-7, Comparative Examples 1-6) A curable composition was obtained by mixing the above-mentioned polyoxyalkylene polymer (A) having hydrolyzable silyl groups, acrylic polymer (B) having hydrolyzable silyl groups, filler, vinyltrimethoxysilane, silanol condensation catalyst, and aminosilane coupling agent in the amounts shown in Table 1, under reduced pressure in a sealed stirrer until homogeneous.

[0112] The chemical resistance of the obtained curable compositions was measured according to the following procedure, and the results are shown in Table 1.

[0113] The obtained curable composition was measured for its basic sealant properties, namely its coatability and elongation, according to the following procedure, and the results are shown in Table 1.

[0114] (Chemical resistance) The resulting curable composition was cured for 7 days in an atmosphere of 23°C and 50% relative humidity to obtain a test specimen that was a flat square with sides of 2 cm and a thickness of 2 mm.

[0115] The obtained test specimens were immersed in a 2% by mass aqueous ammonia solution and a 2% by mass aqueous sodium hypochlorite solution for one week, respectively. After that, the test specimens were removed from the solutions and dried for 24 hours in an atmosphere of 23°C and 50% relative humidity.

[0116] The mass of the dried test specimens was measured. The specific gravity of the dried test specimens was measured according to the method for measuring density and specific gravity by liquid weighing, as specified in JIS Z8807.

[0117] Dried test specimens were immersed in 100 ml of primary reagent tetrahydrofuran (THF) and shaken at room temperature for 1 day. The test specimens were removed from the THF, and any excess THF adhering to the surface of the specimens was quickly wiped off with filter paper. The test specimens were placed in a weighing container whose mass had been measured beforehand, and their mass was measured. The degree of swelling was calculated based on the following formula and evaluated according to the following criteria. The more the test specimen was degraded by the chemical, the greater the degree of swelling of the test specimen.

[0118] Swelling degree (%) = [(Ws / W0)-1] × (dC / dT) × 100 W0: Mass of the test specimen before THF immersion Ws: Mass of the test specimen after THF immersion dC: Specific gravity of the test specimen film dT: Specific gravity of THF (23℃)

[0119] ◎...The degree of swelling was less than 400%. ○...The degree of swelling was 400% or more and less than 450%. △···The degree of swelling was 450% or more and less than 500%. ×...The degree of swelling was 500% or more.

[0120] (Coating properties) The viscosity (10 rpm) of the curable composition was measured using a BH-type viscometer with rotor No. 5 under conditions of 23°C and 10 rpm. The viscosity (1 rpm) of the curable composition was measured using a BH-type viscometer with rotor No. 5 under conditions of 23°C and 1 rpm. The Ti value of the curable composition was calculated based on the following formula. Ti value = viscosity (1 rpm) / viscosity (10 rpm)

[0121] ◎...The Ti value was 5.0 or higher. ○...The Ti value was less than 5.0 and greater than or equal to 4.0. △···The Ti value was less than 4.0 and greater than or equal to 3.0. ×...The Ti value was less than 3.0.

[0122] (Stretchability) The curable composition was cured for 14 days at a temperature of 23°C and a relative humidity of 50%, and the resulting cured product was left to stand for 14 days at a temperature of 30°C and a relative humidity of 40%. The elongation rate E1 (%) of the cured product under maximum load was then measured in the following manner.

[0123] An H-shaped test specimen was prepared using a curable composition in accordance with JIS A1439 5.17 (2010). Specifically, two aluminum plates (50 mm long x 50 mm wide x 3 mm thick) with an anodized coating were used, and a spacer was placed between them to form a rectangular parallelepiped space (12 mm long x 50 mm wide x 12 mm high) in the center of the space between the aluminum plates. The curable composition was then filled into this space, ensuring that no air was trapped inside. Subsequently, the curable composition was cured for 14 days in an atmosphere of 23°C and 50% relative humidity. After curing, the spacer was removed, and an H-shaped test specimen was obtained in which the two aluminum plates were bonded together by the cured product of the curable composition. The H-shaped test specimen was then left for 14 days in an atmosphere of 30°C and 40% relative humidity. Then, the H-type test specimens, after being left to stand, under conditions of 23°C and 50% relative humidity, were subjected to a tensile test at a tensile speed of 50 mm / min in accordance with JIS A1439 5.20.4 (2010), and the elongation rate [%] at maximum load was measured. The measured value obtained was defined as the elongation rate E1 at maximum load of the cured product of the curable composition. ◎...The elongation rate E1 under maximum load was 400% or more. ○...The elongation rate E1 under maximum load was 200% or more and less than 400%. △···The elongation rate E1 under maximum load was 100% or more and less than 200%. ×...The elongation rate E1 under maximum load was less than 100%.

[0124] [Table 1]

Claims

1. A polyoxyalkylene polymer (A) having hydrolyzable silyl groups, It comprises an acrylic polymer (B) having a hydrolyzable silyl group, The main chain of the polyoxyalkylene polymer (A) having the above hydrolyzable silyl group has a branched chain, The above acrylic polymer (B) having hydrolyzable silyl groups has a number-average molecular weight of 20,000 to 40,000, The hydrolyzable silyl group in the above-mentioned acrylic polymer (B) having a hydrolyzable silyl group is a trialkoxysilyl group. The polyoxyalkylene polymer (A) having the above hydrolyzable silyl group has a number-average molecular weight of 30,000 to 40,000. A curable composition characterized in that the mass ratio of the content of the above-mentioned polyoxyalkylene polymer (A) having hydrolyzable silyl groups to the content of the above-mentioned acrylic polymer (B) having hydrolyzable silyl groups [content of polyoxyalkylene polymer (A) having hydrolyzable silyl groups / content of acrylic polymer (B) having hydrolyzable silyl groups] is 0.01 to 1.

5.

2. The curable composition according to claim 1, characterized in that the molecular weight distribution (Mw / Mn) of the polyoxyalkylene polymer (A) having hydrolyzable silyl groups is 2.0 or less.

3. The curable composition according to claim 1, characterized in that it is used as a sealant for areas with water.

Images