Curable composition and cured product

Abstract

The present invention pertains to a curable composition which contains a polymer A and a polymer B, wherein: polymer A is an oxyalkylene polymer which has an average of 2.00 or more terminal groups per molecule and has a reactive silicon group that is represented by formula (1); the terminal groups of polymer A include a reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group; polymer B is an oxyalkylene polymer which has an average of 1.00 to 1.30 terminal groups per molecule and has a reactive silicon group that is represented by formula (2) and is formed via one or more organic groups that are represented by formula (i); the terminal groups of polymer B include a reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group; and the number average molecular weight of polymer B is 5,000 or less.　Formula (1): -SiR1 aX1 3-a; Formula (i): -C(=O)NH-; Formula (2): -SiR2 bX2 3-b

Description

Curable composition and cured product

[0001] This application claims priority from Japanese Patent Application No. 2023-220986, filed on December 27, 2023, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a curable composition containing a polymer having a silicon group (hereinafter referred to as "reactive silicon group") that has a hydroxyl group or a hydrolyzable group bonded to a silicon atom and that can be crosslinked by forming a siloxane bond.

[0003] It is known that polymers having at least one reactive silicon group per molecule have the property of crosslinking through the formation of siloxane bonds accompanied by hydrolysis of the reactive silicon group due to moisture or the like, even at room temperature, to give rubber-like cured products.

[0004] Among these polymers having reactive silicon groups, those whose main chain skeletons are oxyalkylene polymers, saturated hydrocarbon polymers, alkyl acrylate polymers, and alkyl methacrylate polymers have already been industrially produced and are widely used in applications such as sealants, adhesives, and paints. When a curable composition containing such a polymer having a reactive silicon group is used as an adhesive, the curability of the curable composition, as well as the elongation and adhesion to the substrate of the cured product, are important. A high modulus is required as a physical property of the cured product.

[0005] On the other hand, in consideration of ease of handling of the curable composition, a plasticizer is used to reduce the viscosity of the curable composition. Patent Document 1 discloses a curable composition comprising an organic polymer (A) having a reactive silicon group and an organic polymer (B) containing an average of 0.5 to 1.5 reactive silicon groups per molecule. It is described that the organic polymer (B) functions as a reactive plasticizer or diluent, thereby reducing viscosity. It is disclosed that this curable composition can be used as an elastic sealant or adhesive.

[0006] International Publication No. 2005 / 073322

[0007] For example, in the synthesis method of Synthesis Example 7 in the examples of Patent Document 1, hydroxyl groups of a precursor polymer are converted into alkenyloxy groups having carbon-carbon double bonds at the molecular terminals. A silylating agent capable of introducing a reactive silicon group into the carbon-carbon double bond at the molecular terminal of the alkenyloxy group is then reacted to convert the alkenyloxy group into a group having a reactive silicon group. In this synthesis method, when the silylating agent is reacted, the carbon-carbon double bonds at the molecular terminals of some of the alkenyloxy groups are transferred to the interior. Because these transferred carbon-carbon double bonds do not react with the silylating agent, an organic polymer without a reactive silicon group is also produced. Therefore, when a polymer B1 containing an organic polymer without a reactive silicon group produced in this manner is used as a plasticizer, the amount of reactive silicon group may be insufficient, resulting in bleed-out in the cured product. Furthermore, to reduce viscosity, it is common to use a polymer B1 with a low molecular weight. However, as the number of moles of polymer B1 corresponding to the number of parts increases, the number of siloxane bonds that do not contribute to crosslinking increases, and the modulus of the cured product decreases, which poses a problem that the modulus of the cured product relative to the viscosity does not increase.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a curable composition that gives a cured product that has a high modulus relative to viscosity and is less likely to bleed out.

[0009] The present invention relates to the following items [1] to [8]. [1] A curable composition comprising a polymer A and a polymer B, wherein the polymer A is an oxyalkylene polymer having an average of 2.00 or more terminal groups per molecule and having a reactive silicon group represented by the following formula (1), the terminal groups of the polymer A including the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group, the polymer B is an oxyalkylene polymer having an average of 1.00 to 1.30 terminal groups per molecule and having a reactive silicon group represented by the following formula (2) formed via one or more organic groups represented by the following formula (i), the terminal groups of the polymer B including the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group, and the number average molecular weight of the polymer B is 5,000 or less. -SiR１ ａ X １ ３－ａ Formula (1) [In formula (1), R １ represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X １ represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R １ may be the same or different, and when a is 0 or 1, X １ may be the same or different.] -C(=O)NH- Formula (i) -SiR ２ ｂ X ２ ３－ｂ Formula (2) [In formula (2), R ２ represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X ２ represents a hydroxyl group or a hydrolyzable group. b is an integer of 0 to 2. When b is 2, R ２ may be the same or different, and when b is 0 or 1, X ２ may be the same or different.] [2] The curable composition according to [1], wherein the number of organic groups represented by formula (i) contained in polymer B is one. [3] The curable composition according to [1] or [2], wherein the content of polymer B is 20 to 80 parts by mass relative to 100 parts by mass of the total content of polymer A and polymer B. [4] The curable composition according to any of [1] to [3], wherein polymer A is an oxyalkylene polymer formed via one or more organic groups represented by formula (i). [5] The curable composition according to any of [1] to [4], wherein the number average molecular weight of polymer B is 500 to 5,000. [6] The curable composition according to any of [1] to [5], wherein the number average molecular weight of polymer A is 2,400 to 20,000. [7] The curable composition according to any of [1] to [6], wherein the total content of polymer A and polymer B relative to the total mass of the curable composition is 2 to 70% by mass. [8] A cured product of the curable composition according to any one of [1] to [7].

[0010] The curable composition of the present invention can give a cured product that has a high modulus relative to viscosity and is less susceptible to bleed-out.

[0011] FIG. 1 is a schematic diagram showing a test piece used in a tensile shear test.

[0012] The meanings and definitions of terms used in this specification are as follows. A numerical range expressed as "to" means a numerical range with the numbers before and after "to" as the lower and upper limits. A "unit" constituting a polymer means an atomic group formed directly by polymerization of a monomer. A "main chain" means a polymer chain formed by polymerization of two or more monomers. The "main chain" in the oxyalkylene polymer described below means a portion containing a residue of an initiator and a repeating unit based on an alkylene oxide monomer (a polyoxyalkylene chain). An oxyalkylene polymer is a polymer consisting of a main chain and an end group. An "end group" of an oxyalkylene polymer means an atomic group containing the oxygen atom closest to the molecular end among the oxygen atoms in the polyoxyalkylene chain. However, if the atomic group contains a residue of an initiator, it is not considered to be an end group. The term "active hydrogen-containing group" refers to at least one group selected from the group consisting of a hydroxyl group bonded to a carbon atom, a carboxyl group, an amino group, a monovalent functional group obtained by removing one hydrogen atom from a primary amine, a hydrazide group, and a sulfanyl group. The term "active hydrogen" refers to a hydrogen atom derived from the active hydrogen-containing group and a hydrogen atom derived from a hydroxyl group of water. The term "unsaturated group" refers to a group containing a carbon-carbon double bond or a group containing a carbon-carbon triple bond. The carbon-carbon double bond and the carbon-carbon triple bond may be located at or other than the molecular terminal. The term "precursor polymer" refers to a polymer before the introduction of a reactive silicon group, that is, an oxyalkylene polymer having a hydroxyl terminal group obtained by polymerizing an alkylene oxide monomer with the active hydrogen of an initiator.

[0013] The "silylation rate" refers to the ratio of the number of reactive silicon groups to the total number of reactive silicon groups, active hydrogen-containing groups, unsaturated groups, isocyanate groups, and amino groups in the terminal groups of an oxyalkylene polymer. Specifically, the silylation rate is calculated using the following formula: Silylation rate (%) = 100 × number of reactive silicon groups / [number of reactive silicon groups + number of active hydrogen-containing groups + number of isocyanate groups + number of amino groups + (number of carbon-carbon double bonds) + (number of carbon-carbon triple bonds) × 2]. The value of the silylation rate can be measured by NMR analysis. Alternatively, it may refer to the ratio (mol %) of the number of silyl groups of the silylating agent added to the number of terminal groups when the reactive silicon groups are introduced into the terminal groups of an oxyalkylene polymer using a silylating agent described below. However, in this case, a diisocyanate compound is used as the polyisocyanate compound in the method (c) described below. The term "silylating agent" refers to a compound having a functional group reactive with an active hydrogen-containing group, an unsaturated group, an isocyanate group, or an amino group, and a reactive silicon group. The number of organic groups represented by formula (i) can be determined by NMR analysis.

[0014] The "number of terminal groups" is a value calculated by, for example, introducing unsaturated groups into a precursor polymer of an oxyalkylene polymer and then directly measuring the unsaturated group concentration by titration analysis based on the principle of the iodine value measurement method specified in JIS K 0070 (1992). The "number of terminal groups" can also be calculated from the number of active hydrogen-containing groups and molecular weight of the initiator. The "number of terminal groups" in an oxyalkylene polymer is the same as the number of active hydrogens in the initiator and the number of terminal groups in the precursor polymer, as described below.

[0015] In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) are polystyrene-equivalent molecular weights measured using GPC with tetrahydrofuran as an eluent and a calibration curve prepared using polystyrene polymers of known molecular weights. The molecular weight distribution (Mw / Mn) is the ratio of Mw to Mn.

[0016] The curable composition of this embodiment contains an oxyalkylene polymer (hereinafter referred to as "polymer A") having an average of 2.00 or more terminal groups per molecule and having a reactive silicon group represented by the following formula (1), and an oxyalkylene polymer (hereinafter referred to as "polymer B") having an average of 1.00 to 1.30 terminal groups per molecule and having a reactive silicon group represented by the following formula (2), which is formed via one or more organic groups represented by the following formula (i). The terminal groups of polymer A contain the reactive silicon group, unsaturated group, isocyanate group, amino group, or active hydrogen-containing group. The terminal groups of polymer B contain the reactive silicon group, unsaturated group, isocyanate group, amino group, or hydroxyl group. The number average molecular weight of polymer B is 5,000 or less. -SiR １ ａ X １ ３－ａ Formula (1) [In formula (1), R １ represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X １ represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R １ may be the same or different, and when a is 0 or 1, X １ may be the same or different.] -C(=O)NH- Formula (i) -SiR ２ ｂ X ２ ３－ｂ Formula (2) [In formula (2), R ２ represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X ２ represents a hydroxyl group or a hydrolyzable group. b is an integer of 0 to 2. When b is 2, R ２ may be the same or different, and when b is 0 or 1, X ２ may be the same or different from each other.

[0017] <Reactive Silicon Group> The reactive silicon group has a hydroxyl group or a hydrolyzable group bonded to a silicon atom, and can form a siloxane bond to crosslink. The reaction to form the siloxane bond is accelerated by a curing catalyst. The reactive silicon group in polymer A is represented by the following formula (1): -SiR １ａ X １ ３－ａ Formula (1)

[0018] In the formula (1), R １ represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group. １ is preferably at least one selected from the group consisting of hydrocarbon groups having 1 to 20 carbon atoms and triorganosiloxy groups.

[0019] R １ is preferably at least one selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. It is more preferably at least one selected from the group consisting of a linear or branched alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, a phenyl group, a benzyl group, an α-chloromethyl group, a trimethylsiloxy group, a triethylsiloxy group, and a triphenylsiloxy group. A methyl group or an ethyl group is preferred from the viewpoint of good curability of the polymer having a reactive silicon group and stability of the curable composition. An α-chloromethyl group is preferred from the viewpoint of a fast curing rate of the cured product. A methyl group is particularly preferred from the viewpoint of easy availability.

[0020] In the formula (1), X １ represents a hydroxyl group or a hydrolyzable group. Examples of the hydrolyzable group include an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a sulfanyl group, and an alkenyloxy group. An alkoxy group is preferred because it is mildly hydrolyzable and easy to handle. The alkoxy group is preferably a methoxy group, an ethoxy group, or an isopropoxy group, and more preferably a methoxy group or an ethoxy group. When the alkoxy group is a methoxy group or an ethoxy group, a siloxane bond is quickly formed, making it easy to form a crosslinked structure in the cured product, and the physical properties of the cured product tend to be good.

[0021] In the formula (1), a is an integer of 0 to 2. When a is 2, R １ may be the same or different. When a is 1 or less, X １may be the same or different. If the crosslinking density by siloxane bonds is low, the modulus of the cured product will decrease, so a is preferably 2 or less, and more preferably 1 or less.

[0022] Examples of the reactive silicon group represented by formula (1) include a trimethoxysilyl group, a triethoxysilyl group, a triisopropoxysilyl group, a tris(2-propenyloxy)silyl group, a triacetoxysilyl group, a dimethoxymethylsilyl group, a diethoxymethylsilyl group, a dimethoxyethylsilyl group, a methyldiisopropoxysilyl group, an (α-chloromethyl)dimethoxysilyl group, and an (α-chloromethyl)diethoxysilyl group. From the viewpoint of high activity and good curability, a trimethoxysilyl group, a triethoxysilyl group, a dimethoxymethylsilyl group, and a diethoxymethylsilyl group are preferred, and a dimethoxymethylsilyl group is more preferred.

[0023] <Polymer A> Polymer A is an oxyalkylene polymer having an average of 2.00 or more terminal groups per molecule and having a reactive silicon group represented by formula (1), wherein the terminal group contains the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group. The curable composition of this embodiment may contain two or more types of polymer A.

[0024] The main chain of polymer A is a polymer chain composed of an oxyalkylene chain containing a residue of an initiator and a repeating unit based on one or more types of alkylene oxide monomer (hereinafter, a repeating unit based on a monomer will be simply referred to as a "monomer unit", for example, a repeating unit based on an alkylene oxide monomer will be referred to as an "alkylene oxide unit"). When the polymer chain contains two or more types of alkylene oxide units, the alkylene oxide units may form a block polymer or a random polymer. Examples of the oxyalkylene chain include a polymer chain containing an ethylene oxide unit, a polymer chain containing a propylene oxide unit, a polymer chain containing an ethylene oxide unit and a propylene oxide unit, a polymer chain containing an ethylene oxide unit, a polymer chain containing a propylene oxide unit, a polymer chain containing a butylene oxide unit, a polymer chain containing a tetramethylene oxide unit, a polymer chain containing an ethylene oxide unit and a propylene oxide unit, and a polymer chain containing a propylene oxide unit and a butylene oxide unit. Preferred are polymer chains having ethylene oxide units, polymer chains having propylene oxide units, polymer chains having ethylene oxide units and propylene oxide units, polymer chains consisting of propylene oxide units, and polymer chains consisting of ethylene oxide units and propylene oxide units, with polymer chains consisting of propylene oxide units being particularly preferred. Furthermore, when polymer A has a polymer chain containing ethylene oxide units, the content of ethylene oxide units relative to the total mass of polymer A is preferably 0.1 to 30 mass%, more preferably 10 to 20 mass%. A content of ethylene oxide units in polymer A equal to or greater than the lower limit is preferred in terms of faster curing, while a content of ethylene oxide units equal to or less than the upper limit is preferred in terms of easy reduction of viscosity. When polymer A has a polymer chain having ethylene oxide units and propylene oxide units, or a polymer chain consisting of ethylene oxide units and propylene oxide units, the content of ethylene oxide units relative to the total mass of polymer A is preferably 0.1 to 30 mass%, more preferably 10 to 20 mass%. When the content of ethylene oxide units in polymer A is equal to or greater than the lower limit, it is preferred in that the curing rate is faster, and when it is equal to or less than the upper limit, it is preferred in that the viscosity can be easily reduced.When polymer A has a polymer chain having an ethylene oxide unit and a propylene oxide unit, the content of the propylene oxide unit relative to the total mass of polymer A is preferably from 50 to 99.9% by mass, more preferably from 70 to 90% by mass.

[0025] Polymer A has an average of 2.00 or more terminal groups per molecule (also referred to as the "average number of terminal groups"). Polymers having an average of 2.00 to 6.00 terminal groups per molecule are more preferred, as this results in a cured product with higher tensile strength and better modulus and elongation. The terminal groups of polymer A include any of the reactive silicon group represented by formula (1), an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group. The respective terminal groups may be the same or different.

[0026] Polymer A preferably has an average of 0.50 to 2.00, and more preferably 0.60 to 1.94 reactive silicon groups represented by formula (1) per terminal group. If the number is equal to or greater than the lower limit of the above range, the crosslinking density due to siloxane bonds will be high, and a good cured product with a high modulus will be obtained.

[0027] The molecular weight distribution of polymer A is preferably 1.80 or less. A smaller molecular weight distribution is preferable, more preferably 1.00 to 1.60, even more preferably 1.02 to 1.50, and particularly preferably 1.04 to 1.40, because good elongation properties are easily obtained and the viscosity is reduced, resulting in good workability.

[0028] The Mn of polymer A is preferably 2,400 to 20,000, more preferably 3,000 to 19,000, even more preferably 3,000 to 18,000, and particularly preferably 3,500 to 10,000. When the Mn is equal to or greater than the lower limit of the above range, the elongation properties of the cured product are improved. When the Mn is equal to or less than the upper limit of the above range, the viscosity is low and workability is improved.

[0029] The polymer A can be produced by the following methods (a) to (c): Method (a): A hydroxyl group of a precursor polymer is converted into an alkenyloxy group having a carbon-carbon double bond at the molecular terminal, and then a reactive silicon group -SiR represented by the above formula (1) is attached to the carbon-carbon double bond at the molecular terminal of the alkenyloxy group. １ ａ X １ ３－ａ (b): A method of reacting a hydroxyl group of a precursor polymer with a silylating agent having a functional group reactive with the hydroxyl group and the reactive silicon group represented by formula (1) to convert the hydroxyl group into a group having a reactive silicon group represented by formula (1). (c): A method of converting a hydroxyl group of a precursor polymer into a group having an isocyanate group, and then reacting the hydroxyl group with a silylating agent having a functional group reactive with an isocyanate group and the reactive silicon group represented by formula (1) to convert the hydroxyl group into a group having a reactive silicon group represented by formula (1).

[0030] In method (a), a precursor polymer is first produced. The precursor polymer can be produced by polymerizing an initiator and an alkylene oxide in the presence of a ring-opening polymerization catalyst. The number of active hydrogens in the initiator is preferably 2 to 6. It is preferably selected depending on the number of reactive silicon groups per molecule of the polymer A to be obtained. One type of initiator may be used alone, or two or more types may be used in combination.

[0031] The initiator preferably has a hydroxyl group as the active hydrogen-containing group. Examples of initiators having two hydroxyl groups include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, and low-molecular-weight polyoxypropylene glycol. Examples of initiators having three hydroxyl groups include glycerin, trimethylolpropane, trimethylolethane, and low-molecular-weight polyoxypropylenetriol. Examples of initiators having four or more hydroxyl groups include pentaerythritol, sucrose, sorbitol, dipentaerythritol, trehalose, and diglycerin.

[0032] The alkylene oxide is selected depending on the structural units of the polyoxyalkylene chains of the precursor polymer and polymer A to be obtained. Examples of alkylene oxide include ethylene oxide, propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide. Among these, ethylene oxide and propylene oxide are preferred, and propylene oxide is more preferred.

[0033] Examples of ring-opening polymerization catalysts include composite metal cyanide complexes and alkali metal hydroxides (potassium hydroxide, etc.). The use of composite metal cyanide complexes is preferred because the precursor polymer tends to have a narrow molecular weight distribution and a low total degree of unsaturation. Conventionally known compounds can be used as the composite metal cyanide complex. For example, compounds and production methods disclosed in International Publication No. 2003 / 062301, International Publication No. 2004 / 067633, Japanese Patent Application Laid-Open No. 2004-269776, Japanese Patent Application Laid-Open No. 2005-15786, Japanese Patent Application Laid-Open No. 2013 / 065802, and Japanese Patent Application Laid-Open No. 2015-010162 can be used. The composite metal cyanide complex is preferably a composite metal cyanide complex in which glyme or t-butyl alcohol is coordinated as an organic ligand to the catalyst skeleton. The catalyst skeleton is preferably a Zn ３ [Co(CN) ６ ] ２(i.e., zinc hexacyanocobaltate complex) is more preferred. In particular, a double metal cyanide complex using t-butyl alcohol as an organic ligand is preferred.

[0034] When the polyoxyalkylene chains of the precursor polymer and polymer A to be obtained are random copolymer chains, a method of producing the precursor polymer by polymerizing an alkylene oxide including propylene oxide with an initiator in the presence of a double metal cyanide complex is preferred. For example, a method of producing the precursor polymer by reacting a mixture of ethylene oxide and propylene oxide with an initiator in the presence of a double metal cyanide complex is preferred.

[0035] When the polyoxyalkylene chains of the precursor polymer and polymer A to be obtained have a block chain or random copolymer chain consisting of oxyalkylene groups and a block chain consisting of oxyethylene groups, a method of producing the precursor polymer is preferred, in which an alkylene oxide is polymerized with an initiator in the presence of a composite metal cyanide complex, and then ethylene oxide is polymerized in the presence of an alkali metal hydroxide. For example, a method is preferred in which propylene oxide is polymerized with an initiator in the presence of a composite metal cyanide complex, and then ethylene oxide is polymerized in the presence of an alkali metal hydroxide to obtain the precursor polymer. Alternatively, a method is preferred in which a mixture of ethylene oxide and propylene oxide is reacted with an initiator in the presence of a composite metal cyanide complex, and then ethylene oxide is polymerized in the presence of an alkali metal hydroxide to obtain the precursor polymer. In the precursor polymer, the presence of an oxyethylene group at least at the end of the polyoxyalkylene chain on the reactive silicon group side is preferred, as this improves deep curability.

[0036] The Mn of the precursor polymer is preferably 2,400 to 20,000, more preferably 3,000 to 19,000, even more preferably 3,000 to 18,000, and particularly preferably 3,500 to 10,000. It is preferably set according to the Mn of the polymer A to be obtained. The Mw / Mn of the precursor polymer is preferably set so that the Mw / Mn of polymer A is 2.00 or less. For example, the Mw / Mn of the precursor polymer is preferably 1.50 or less, more preferably 1.45 or less, and even more preferably 1.40 or less. The lower limit is not particularly limited. For example, the lower limit is preferably 1.00 or more, and more preferably 1.01 or more. The above lower limit and upper limit can be combined arbitrarily. For example, the Mw / Mn of the precursor polymer is preferably 1.00 to 2.00, more preferably 1.00 to 1.50, even more preferably 1.01 to 1.45, and particularly preferably 1.01 to 1.40. The total unsaturation degree of the precursor polymer is preferably 0.10 meq / g or less, more preferably 0.05 meq / g or less, even more preferably 0.03 meq / g or less, and most preferably 0.01 meq / g or less. When it is below the upper limit, excellent deep curing properties are achieved. The lower limit is not particularly limited. For example, the lower limit is preferably 0.0001 meq / g or more. The total degree of unsaturation of the precursor polymer is preferably from 0.0001 to 0.10 meq / g, more preferably from 0.0001 to 0.05 meq / g, even more preferably from 0.0001 to 0.03 meq / g, and most preferably from 0.0001 to 0.01 meq / g.

[0037] Next, an alkali metal salt is reacted with the precursor polymer, and then a halogenated hydrocarbon compound having a carbon-carbon double bond at the molecular end is reacted to convert the hydroxyl groups of the precursor polymer into alkenyloxy groups having a carbon-carbon double bond at the molecular end.

[0038] Examples of alkali metal salts include sodium hydroxide, sodium alkoxide, potassium hydroxide, potassium alkoxide, lithium hydroxide, lithium alkoxide, cesium hydroxide, and cesium alkoxide. From the viewpoints of ease of handling and solubility, sodium hydroxide, sodium methoxide, sodium ethoxide, potassium hydroxide, potassium methoxide, and potassium ethoxide are preferred, with sodium methoxide and potassium ethoxide being more preferred. From the viewpoint of availability, sodium methoxide is particularly preferred. The alkali metal salt may be used in a state dissolved in a solvent.

[0039] As the halogenated hydrocarbon compound having a carbon-carbon double bond at the molecular terminal, one or both of a halogenated hydrocarbon compound containing a carbon-carbon double bond at the molecular terminal and a halogenated hydrocarbon compound containing a carbon-carbon triple bond can be used. Examples of the halogenated hydrocarbon compound containing a carbon-carbon double bond at the molecular terminal include vinyl chloride, allyl chloride, methallyl chloride, vinyl bromide, allyl bromide, methallyl bromide, vinyl iodide, allyl iodide, and methallyl iodide. Allyl chloride and methallyl chloride are preferred. Examples of the halogenated hydrocarbon compound containing a carbon-carbon triple bond include propargyl chloride, 1-chloro-2-butyne, 4-chloro-1-butyne, 1-chloro-2-octyne, 1-chloro-2-pentyne, 1,4-dichloro-2-butyne, 5-chloro-1-pentyne, 6-chloro-1-hexyne, propargyl bromide, 1-bromo-2-butyne, 4-bromo-1-butyne, 1-bromo- Examples include 2-octyne, 1-bromo-2-pentyne, 1,4-dibromo-2-butyne, 5-bromo-1-pentyne, 6-bromo-1-hexyne, propargyl iodide, 1-iodo-2-butyne, 4-iodo-1-butyne, 1-iodo-2-octyne, 1-iodo-2-pentyne, 1,4-diiodo-2-butyne, 5-iodo-1-pentyne, and 6-iodo-1-hexyne. Propargyl chloride, propargyl bromide, and propargyl iodide are preferred. Two or more halogenated hydrocarbon compounds having a carbon-carbon double bond or triple bond at the molecular terminal may be used in combination.

[0040] Next, a reactive silicon group, —SiR, represented by the above formula (1), is attached to the double bond at the molecular terminal of the alkenyloxy group. １ ａ X １ ３－ａ The alkenyloxy group is converted into a group having a reactive silicon group represented by the above formula (1) by reacting with a silylating agent capable of introducing the following: １ ａ X １ ３－ａ , X １ , R １ , a is the same as in formula (1) above). Specific examples include dimethoxymethylsilane, diethoxymethylsilane, dimethoxyethylsilane, methyldiisopropoxysilane, (α-chloromethyl)dimethoxysilane, (α-chloromethyl)diethoxysilane, trimethoxysilane, triethoxysilane, triisopropoxysilane, tris(2-propenyloxy)silane, triacetoxysilane, and 3-mercaptopropyltrimethoxysilane. From the viewpoints of high activity and good curability, trimethoxysilane, dimethoxymethylsilane, and diethoxymethylsilane are preferred, and dimethoxymethylsilane is more preferred.

[0041] In the method (b), the precursor polymer described in the method (a) is reacted with a silylating agent. As the silylating agent, it is preferable to use an isocyanate silane compound represented by the following formula (3): OCN—(CH ２ ) ｎ -SiR １ ａ X １ ３－ａ ...Formula (3) -SiR in the above formula (3) １ ａ X １ ３－ａ is the same as the above formula (1). n is an integer of 1 to 8, preferably 1 to 3. The reaction between the hydroxyl groups of the precursor polymer and the isocyanate silane compound converts the hydroxyl groups of the precursor polymer to —O—C(═O)NH—(CH２ ) ｎ -SiR ａ X ３－ａ A urethane bond (—O—C(═O)NH—) and —SiR ａ X ３－ａ

[0033] Examples of the isocyanate silane compound include 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, isocyanate methyl trimethoxysilane, isocyanate methyl triethoxysilane, 3-isocyanate propyl methyl dimethoxysilane, 3-isocyanate propyl methyl diethoxysilane, isocyanate methyl methyl dimethoxysilane, and isocyanate methyl methyl diethoxysilane.

[0034] In view of reactivity with the precursor polymer and ease of handling, 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, 3-isocyanate propyl methyl dimethoxysilane, and isocyanate methyl trimethoxysilane are preferred.

[0042] The active hydrogen of the precursor polymer reacts with the isocyanate group of the isocyanate silane compound represented by formula (3), thereby introducing a reactive silicon group into the precursor polymer. When the active hydrogen-containing group of the precursor polymer is a hydroxyl group, the polyoxyalkylene chain (-(R ５ O) ｍ -, R ５ represents an alkylene group, and m represents the number of moles of oxyalkylene groups.) to which a reactive silicon group is bonded via a urethane bond and an organic group. ５ O) ｍ -C(=O)NH-(CH ２ ) ｎ -SiR １ ａ X １ ３－ａ A linking structure represented by the following formula is formed.

[0043] This reaction may be carried out in the presence of a urethanization catalyst. The urethanization catalyst is not particularly limited, and known urethanization catalysts can be used as appropriate. Examples include organotin compounds such as dibutyltin dilaurate and dioctyltin dilaurate, metal catalysts such as bismuth compounds, and base catalysts such as organic amines. The reaction temperature is preferably 20 to 200°C, more preferably 50 to 150°C. The urethanization reaction is preferably carried out in an inert gas atmosphere. Nitrogen is preferred as the inert gas.

[0044] The molar ratio of the total number of isocyanate groups in the isocyanate silane compound represented by formula (3) to the total number of active hydrogens in the precursor polymer is preferably set according to the number of reactive silicon groups per molecule of the polymer A to be obtained. The isocyanate silane compound represented by formula (3) is reacted so that the resulting polymer A has at least 1.8 reactive silicon groups per molecule. For example, when the active hydrogen-containing groups in the precursor polymer are hydroxyl groups, NCO / OH, which represents the molar ratio of the total number of isocyanate groups (NCO) in the isocyanate silane compound represented by formula (3) to the total number of active hydrogens in the precursor polymer, is preferably 0.7 to 1.0, more preferably 0.8 to 1.0, and even more preferably 0.9 to 1.0. When the ratio is equal to or greater than the lower limit of the above range, the strength of the cured product is excellent, and when the ratio is equal to or less than the upper limit, the elongation of the cured product is excellent.

[0045] In method (c), a polyisocyanate compound is reacted with hydroxyl groups of a precursor polymer to convert the hydroxyl groups into monovalent organic groups containing an isocyanate group (hereinafter also referred to as "isocyanate-containing groups") that have a urethane bond (-O-C(=O)NH-) at the bond terminal with the precursor polymer. The isocyanate-containing groups are then reacted with a silylating agent having a functional group reactive with an isocyanate group and a reactive silicon group represented by formula (1) above, to form terminal groups that are monovalent organic groups having one or more urethane bonds (-O-C(=O)NH-) and a silylating agent residue that has reacted with an isocyanate group (hereinafter also referred to as "urethane bond- and reactive silicon-group-containing groups"). Hereinafter, method (c) will be described assuming that the polyisocyanate compound is a diisocyanate compound represented by the following formula (4) and that the silylating agent having a functional group reactive with an isocyanate group and a reactive silicon group represented by the above formula (1) is a compound represented by the following formula (5), but the present invention is not limited thereto.

[0046] OCN-R ３ -NCO Formula (4) R in the above formula (4) ３ represents a divalent organic group.

[0047] W-R ４ -SiR １ ａ X １ ３－ａ Formula (5) In the above formula (5), W represents a functional group (a group having one or more active hydrogens) capable of reacting with a monovalent isocyanate group, R ４ is a divalent organic group, -SiR １ ａ X １ ３－ａ is the same as the above formula (1).

[0048] The precursor polymer may be the precursor polymer described in the method (a). When the polyisocyanate compound represented by the formula (4) is reacted with the hydroxyl group of the precursor polymer, the isocyanate-containing group is —O—C(═O)NH—R ３When the isocyanate-containing group is reacted with the silylating agent represented by formula (5), the urethane bond and the reactive silicon-containing group are converted to a group represented by the formula -O-C(=O)NH-R ３ -NHC(=O)-W'-R ４ -SiR １ ａ X １ ３－ａ (wherein W' is a divalent group obtained by removing one active hydrogen from W.) For example, when W is a hydroxyl group, the urethane bond and the reactive silicon group-containing group are represented by the formula: -O-C(=O)NH-R ３ -NHC(=O)-OR ４ -SiR １ ａ X １ ３－ａ In this case, the urethane bond and reactive silicon group-containing group have two urethane bonds. ２ ), the urethane bond and the reactive silicon group-containing group are —O—C(═O)NH—R ３ -NHC(=O)-NH-R ４ -SiR １ ａ X １ ３－ａ It is a group represented by the formula:

[0049] R ３ is preferably a divalent organic group having 2 to 20 carbon atoms, and examples thereof include an alkylene group, a cycloalkylene group, a bicycloalkylene group, a monocyclic or polycyclic divalent aromatic hydrocarbon group, a divalent group obtained by removing two hydrogen atoms from a cycloalkane having an alkyl group as a substituent, a divalent group obtained by removing two hydrogen atoms from an aromatic hydrocarbon having an alkyl group as a substituent, a divalent group obtained by removing two hydrogen atoms from two or more cycloalkanes which are bonded via an alkylene group and which may have an alkyl group as a substituent, and a divalent group obtained by removing two hydrogen atoms from two or more aromatic hydrocarbons which are bonded via an alkylene group and which may have an alkyl group as a substituent.

[0050] Examples of the diisocyanate compound represented by the above formula (4) and other polyisocyanate compounds include aromatic polyisocyanates, non-yellowing aromatic polyisocyanates (which refer to compounds that do not have an isocyanate group directly bonded to a carbon atom constituting an aromatic ring), aliphatic polyisocyanates, and alicyclic polyisocyanates, as well as urethane-modified products, biuret-modified products, allophanate-modified products, carbodiimide-modified products, and isocyanurate-modified products obtained from the above polyisocyanates.

[0051] Examples of aromatic polyisocyanates include naphthalene-1,5-diisocyanate, polyphenylene polymethylene polyisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate. Examples of non-yellowing aromatic polyisocyanates include xylylene diisocyanate and tetramethylxylylene diisocyanate. Examples of aliphatic polyisocyanates include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, and 2,4,4-trimethyl-hexamethylene diisocyanate. Examples of alicyclic polyisocyanates include isophorone diisocyanate and 4,4'-methylenebis(cyclohexyl isocyanate). The polyisocyanate compound is preferably one having two isocyanate groups, and hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, or 2,6-tolylene diisocyanate is preferred, with tolylene diisocyanate being more preferred because it is easier to obtain tensile strength in the cured product. One type of polyisocyanate compound may be used, or two or more types may be used in combination.

[0052] A functional group capable of reacting with an isocyanate group represented by formula (5) and —SiR １ ａ X １ ３－ａ R in the silylating agent having ４As the alkyl group, a divalent organic group having 1 to 20 carbon atoms is preferred, a group obtained by removing two hydrogen atoms from an aromatic hydrocarbon having 6 to 10 carbon atoms, a group obtained by removing two hydrogen atoms from an aromatic hydrocarbon having 6 to 10 carbon atoms and substituted with an alkyl group having 1 to 4 carbon atoms, a group obtained by removing two hydrogen atoms from a cyclic hydrocarbon having 3 to 10 carbon atoms, or a group obtained by removing two hydrogen atoms from a linear hydrocarbon having 1 to 12 carbon atoms is more preferred, a group obtained by removing two hydrogen atoms from a linear hydrocarbon having 1 to 8 carbon atoms is even more preferred, and a group obtained by removing two hydrogen atoms from a linear hydrocarbon having 1 to 6 carbon atoms is particularly preferred. W is preferably a group having one or two active hydrogen atoms selected from a hydroxyl group, a carboxyl group, a sulfanyl group, an amino group, and an amino group in which one hydrogen atom is substituted with an alkyl group having 1 to 6 carbon atoms, more preferably a hydroxyl group, a sulfanyl group, an amino group, a methylamino group, an ethylamino group, or a butylamino group, and more preferably a hydroxyl group, an amino group, a methylamino group, an ethylamino group, or a butylamino group.

[0053] The number of reactive silicon-containing groups introduced into polymer A is preferably 0.50 to 2.00 on average per terminal group, as described above, and more preferably 0.60 to 1.94, since this makes it easier to achieve both a high modulus and good elongation properties in the cured product.

[0054] The silylation rate of polymer A is preferably 50 to 100 mol%, more preferably 60 to 98 mol%. When the silylation rate is equal to or greater than the lower limit of the above range, the cured product has excellent tensile strength and a high modulus. When the curable composition contains two or more types of polymer A, it is sufficient that the average silylation rate of all polymers A is within the above range.

[0055] When producing polymer A, in addition to a precursor polymer (main product) in which polyoxyalkylene is added to the initiator, a diol precursor polymer (by-product) in which polyoxyalkylene is added to water in the reaction system may be produced. Therefore, an oxyalkylene polymer having two terminal groups per molecule is produced from the by-product. As a result, the average number of terminal groups per molecule of polymer A (average number of terminal groups) is calculated as follows: Average number of terminal groups of polymer A = (number of active hydrogen-containing groups of initiator x mass% of main product derived from initiator + 2 x mass% of by-product derived from water) / 100

[0056] Polymer A may be an oxyalkylene polymer formed via one or more organic groups represented by formula (i). That is, polymer A may be an oxyalkylene polymer produced by method (b) or method (c). When polymer A is an oxyalkylene polymer formed via one or more organic groups represented by formula (i), the organic groups gather together through interactions derived from hydrogen bonds to form hard segments, which is more preferable because the modulus upon curing is higher than that of a polymer having no organic groups.

[0057] <Polymer B> Polymer B is an oxyalkylene polymer having an average of 1.00 to 1.30 terminal groups per molecule, and having a reactive silicon group represented by formula (2) below, which is formed via one or more organic groups represented by formula (i) below, and has a number average molecular weight of 5,000 or less. The terminal group of polymer B contains a reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group. -C(=O)NH- Formula (i) -SiR ２ ｂ X ２ ３－ｂ Formula (2)

[0058] One molecular end of polymer B has a structure derived from a residue of an initiator, and the other molecular end has a structure derived from the terminal group. The curable composition of this embodiment may contain two or more types of polymer B. Polymer B acts as a reactive plasticizer, reducing the viscosity of the curable composition and achieving a cured product with excellent bleed-out suppression ability and high modulus. Examples of the main chain of polymer B are the same as the examples of the main chain of polymer A. In addition, R in formula (2) ２and X ２ Regarding R of polymer A, １ and X １ The range of b in formula (2) is the same as that of a in formula (1).

[0059] An oxyalkylene polymer formed via one or more organic groups represented by formula (i) can also be said to contain one or more organic groups represented by formula (i).

[0060] In polymer B, the organic group (i) present between the polyoxyalkylene chain and the reactive silicon group is an organic group derived from the silylating agent having a functional group reactive with a hydroxyl group and a reactive silicon group represented by formula (1) in method (b), or the silylating agent having a functional group reactive with an isocyanate group and a reactive silicon group represented by formula (2) used in method (c). Polymer B contains one or two organic groups (i). The organic group (i) is a divalent group derived from a urethane bond or a urea bond. When an isocyanate silane compound represented by formula (3) is used as the silylating agent, the number of organic groups (i) is one.

[0061] The organic group (i) preferably forms a urethane bond (-O-C(=O)NH-, where -O- represents the oxygen atom at the terminal of the polyoxyalkylene chain) with the polyoxyalkylene chain. That is, it is preferable that one organic group (i) is present between the polyoxyalkylene chain and the reactive silicon group in polymer B. When polymer B is produced by the above-mentioned method (b), the number of organic groups represented by formula (i) contained in polymer B will be one. When polymer B is produced by method (b), polymer B having a high silylation rate can be obtained. A curable composition containing such polymer B as a reactive plasticizer has high reactivity during curing, and therefore bleed-out of the cured product is unlikely to occur. Furthermore, when produced by method (b), polymer B having a narrow molecular weight distribution can be obtained. The viscosity of the polymer is suppressed, resulting in good workability. When the isocyanate silane compound represented by formula (3) contains one isocyanate group and one reactive silicon group, the number of reactive silicon groups per molecule of polymer B is the same as the number of groups (i) per molecule.

[0062] As a method for producing polymer B, method (b), i.e., a method of reacting a precursor polymer with an isocyanate silane compound represented by formula (3), is preferred because it does not produce impurities having unsaturated groups as by-products. It is also preferred because it reduces the number of production steps. The total unsaturation degree of polymer B obtained by this method is equal to or less than the total unsaturation degree of the precursor polymer. Specifically, the total unsaturation degree of polymer B is preferably 0.10 meq / g or less, more preferably 0.05 meq / g or less, even more preferably 0.03 meq / g or less, and most preferably 0.01 meq / g or less. When the total unsaturation degree is equal to or less than the upper limit, the strength of the cured product is superior. The lower limit is not particularly limited. For example, the lower limit is preferably 0.0001 meq / g or more. The total degree of unsaturation of polymer B is preferably from 0.0001 to 0.10 meq / g, more preferably from 0.0001 to 0.05 meq / g, even more preferably from 0.0001 to 0.03 meq / g, and most preferably from 0.0001 to 0.01 meq / g.

[0063] Polymer B preferably has an average of more than 0.40 but not more than 1.00 reactive silicon groups represented by formula (2) per terminal group, more preferably more than 0.50 but not more than 1.00, even more preferably 0.51 to 0.97, and particularly preferably 0.52 to 0.95. When the polymer B is at or above the lower limit of the above range, the cured product has superior tensile strength, a higher modulus, and excellent bleed-out suppression. When the polymer B is at or below the upper limit of the above range, the cured product has superior elongation.

[0064] The Mn of polymer B is preferably 500 to 5,000, more preferably 600 to 4,000, and even more preferably 700 to 3,500. When the Mn is equal to or greater than the lower limit of the above range, the cured product will have superior tensile strength and a higher modulus. When the Mn is equal to or less than the upper limit of the above range, the viscosity is suppressed, resulting in better workability. Generally, the smaller the molecular weight of the plasticizer, the lower the viscosity of the curable composition, and accordingly the lower the modulus. On the other hand, polymer B of this embodiment has a reactive silicon group at the terminal group, and therefore can maintain a high modulus relative to the viscosity of the curable composition compared to other plasticizers. The molecular weight distribution of polymer B is preferably 1.80 or less. From the viewpoint of reducing viscosity, a smaller molecular weight distribution is preferable, more preferably 1.00 to 1.60, even more preferably 1.02 to 1.50, and particularly preferably 1.04 to 1.40.

[0065] Polymer B can be obtained by introducing more than 0 and 1.0 or less reactive silicon groups per terminal group into a precursor polymer having one terminal group which is a hydroxyl group. The initiator residue at one molecular terminal of polymer B is R １０ -O-(R １０ is preferably a monovalent hydrocarbon group. １０ As the alkyl group, a branched or linear alkyl group having 1 to 20 carbon atoms is preferable, a branched or linear alkyl group having 1 to 10 carbon atoms is more preferable, a branched or linear alkyl group having 1 to 4 carbon atoms is even more preferable, and a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an n-butyl group, or a t-butyl group is particularly preferable.

[0066] The precursor polymer of polymer B is preferably produced in the same manner as polymer A, except that an initiator having one active hydrogen is used. Two or more types of initiators may be used in combination. The active hydrogen-containing group of the initiator is preferably a hydroxyl group. The precursor polymer is preferably a polymer having one hydroxyl group as a terminal group. As the initiator having one hydroxyl group, a monohydric alcohol having a linear or branched hydrocarbon group is preferred. Specific examples include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-butyl alcohol, t-butyl alcohol, 2-ethylhexanol, decyl alcohol, lauryl alcohol, tridecanol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and low-molecular-weight polyoxyalkylene monools.

[0067] The silylation rate of polymer B is preferably more than 50 mol% and not more than 100 mol%, more preferably 70 to 100 mol%, and even more preferably 90 to 100 mol%. When the silylation rate of polymer B is equal to or greater than the lower limit of the above range, the cured product has superior tensile strength, a higher modulus, and is less susceptible to bleed-out. When the curable composition contains two or more types of polymer B, it is sufficient that the average silylation rate of all polymers B is within the above range.

[0068] When producing polymer B, in addition to a precursor polymer (main product) in which polyoxyalkylene is added to a mono-ol initiator, a diol precursor polymer (by-product) in which polyoxyalkylene is added to water in the reaction system may be produced. Therefore, an oxyalkylene polymer having two terminal groups per molecule and a reactive silicon group represented by formula (2) formed via one or more organic groups represented by formula (i) is produced from the by-product. As a result, the average number of terminal groups per molecule of polymer B may exceed 1.00. The average number of terminal groups per molecule (average number of terminal groups) is calculated as follows: Average number of terminal groups of polymer B = (1 x mass% of main product derived from mono-ol initiator + 2 x mass% of by-product derived from water) / 100

[0069] When the amount of water in the reaction system increases, Mw / Mn increases, and viscosity increases, resulting in poor workability. Therefore, the average number of terminal groups of polymer B is 1.00 to 1.30, preferably 1.00 to 1.20, and more preferably 1.00 to 1.10.

[0070] <Polymer C> The curable composition of this embodiment may contain a vinyl polymer (hereinafter referred to as "polymer C") having, on average, one or more reactive silicon groups represented by formula (1) per molecule. The curable composition of this embodiment may contain two or more types of polymer C. Polymer C contributes to weather resistance, water resistance, and the like. The reactive silicon group in polymer C may be introduced at the end of the main chain, at the side chain, or at both the end of the main chain and the side chain. The average number of reactive silicon groups per molecule of polymer C is preferably 0.8 or more. From the viewpoint of tensile strength after curing, 1.0 or more is preferred, and 1.2 or more is more preferred. From the viewpoint of good elongation of the cured product, 4.0 or less is preferred, and 3.0 or less is more preferred. 0.8 to 4.0 is preferred, 1.0 to 4.0 is more preferred, and 1.2 to 3.0 is even more preferred. The average number of reactive silicon groups per molecule of polymer C is calculated by "the concentration of reactive silicon groups in polymer C [mol / g] x the number average molecular weight of polymer C." The concentration of reactive silicon groups in polymer C [mol / g] can be measured by NMR. As the monomer constituting the main chain of polymer C, for example, conventionally known monomers described in JP-B No. 3-14068, JP-A No. 6-211922, and JP-A No. 11-130931 can be used. Examples of monomers containing a reactive silicon group and an unsaturated group to be copolymerized with the above monomers include vinyldimethoxymethylsilane, vinyldiethoxymethylsilane, vinylmethyldichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, tris(2-methoxyethoxy)vinylsilane, 3-(dimethoxymethylsilyl)propyl (meth)acrylate, 3-(trimethoxysilyl)propyl (meth)acrylate, and 3-(triethoxysilyl)propyl (meth)acrylate. Two or more of these may be used. The content of the (meth)acrylic acid ester monomer relative to all monomers constituting Polymer C is preferably 50% by mass or more, more preferably 70% by mass or more, and may be 100% by mass.

[0071] Polymer C can be polymerized by a conventionally known polymerization method described in, for example, JP-A Nos. 2006-257405, 2006-37076, and 2008-45059. Conventionally known secondary materials such as initiators required for polymerization can also be used, and reaction conditions such as reaction temperature and reaction pressure can also be selected appropriately. Examples of the polymerization method include solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization using a radical polymerization initiator, and living radical polymerization. Examples of living radical polymerization methods include those using a cobalt porphyrin complex as disclosed in Journal of the American Chemical Society (J. Am. Chem. Soc.), 1994, Vol. 116, p. 7943, those using a nitroxide radical as disclosed in JP-A-2003-500378, and atom transfer radical polymerization (ATRP) using an organic halide or a sulfonyl halide compound as an initiator and a transition metal complex as a catalyst as disclosed in JP-A-11-130931. Polymers obtained by living radical polymerization tend to have narrow molecular weight distributions and low viscosity. Commercially available polymer C can also be used. Examples of commercially available products that can be used include the XMAP series (trade name of Kaneka Corporation), the ARUFON US-6000 series (e.g., US-6110, US-6120, US-6170, etc., all of which are product names of Toagosei Co., Ltd.), and the Actflow NE series (e.g., NE-1000, NE-3000, all of which are product names of Soken Chemical & Engineering Co., Ltd.).

[0072] The Mn of polymer C is preferably 500 to 100,000, more preferably 800 to 80,000, and even more preferably 1,000 to 60,000. When the Mn is equal to or greater than the lower limit of the above range, the cured product tends to have excellent elongation properties and weather resistance, and when the Mn is equal to or less than the upper limit, the workability is superior. The molecular weight distribution of polymer C is preferably 4.0 or less, and more preferably 3.0 or less. When the Mn is equal to or less than the upper limit, the workability is superior.

[0073] <Curable Composition> The curable composition is obtained by mixing polymer A, polymer B, and other necessary components. The content of polymer A relative to the total mass of the curable composition is preferably 1 to 90 mass%, more preferably 10 to 80 mass%, and even more preferably 20 to 70 mass%. Within the above range, the cured product has better tensile strength and better elongation properties. The content of polymer B relative to the total mass of the curable composition is preferably 1 to 70 mass%, more preferably 1 to 60 mass%, and even more preferably 1 to 50 mass%. When the content is equal to or greater than the lower limit of the above range, the viscosity of the curable composition decreases and the elongation properties improve. When the content is equal to or less than the upper limit of the above range, the cured product has better tensile strength and a higher modulus. The combined content of polymer A and polymer B relative to the total mass of the curable composition is preferably 2 to 70 mass%, more preferably 3 to 60 mass%, and even more preferably 4 to 50 mass%. When the content is equal to or less than the upper limit of the above range, the viscosity of the curable composition tends to decrease. When the content is equal to or greater than the lower limit of the above range, the curability is good, and the cured product has excellent tensile strength and a high modulus. The content of polymer B is preferably 20 to 80 parts by mass, more preferably 25 to 75 parts by mass, and even more preferably 30 to 70 parts by mass, relative to 100 parts by mass of the total content of polymer A and polymer B. When the content is equal to or greater than the lower limit of the above range, the viscosity of the curable composition decreases, and the cured product has excellent tensile strength. When the content is equal to or less than the upper limit of the above range, the tensile strength and modulus are excellent. When the curable composition contains polymer C, the content of polymer C is preferably 1 to 600 parts by mass, more preferably 5 to 500 parts by mass, and even more preferably 10 to 300 parts by mass, relative to 100 parts by mass of the total content of polymer A. When the content is within the above range, the weather resistance of the cured product of the curable composition is improved.

[0074] [Other Components] Examples of the other components include curable compounds other than polymers A to C, such as epoxy resins, epoxy resin curing agents, curing catalysts (silanol condensation catalysts), fillers, plasticizers, thixotropy-imparting agents, stabilizers, adhesion-imparting agents, physical property adjusters, dehydrating agents, adhesion-imparting resins, reinforcing materials such as fillers, surface modifiers, flame retardants, foaming agents, solvents, and silicates. Other components include those described in WO 2013 / 180203, WO 2014 / 192842, WO 2016 / 002907, JP 2014-88481, JP 2015-10162, JP 2015-105293, JP 2017-039728, and JP 2017-214541, and can be used in combination without limitation. Two or more of each component may be used in combination.

[0075] The curable composition may be a one-component type in which the polymer and other components are all blended in advance, sealed, and stored, and then cured by moisture in the air after application. Alternatively, it may be a two-component type in which a base composition containing at least a polymer having a reactive silicon group and a curing agent composition containing at least a curing catalyst are stored separately, and the curing agent composition and the base composition are mixed before use. It is preferable that the one-component curable composition does not contain water. It is preferable that the blended components containing water are dehydrated and dried in advance, or that the pressure is reduced during blending and kneading. In two-component curable compositions, the curing agent composition may contain water. The base composition is unlikely to gel even if it contains a small amount of water, but from the perspective of storage stability, it is preferable that the blended components be dehydrated and dried in advance. To improve storage stability, a dehydrating agent may be added to the one-component curable composition or the two-component base composition.

[0076] [Mechanism of Action] The curable composition of this embodiment contains polymer A and polymer B, where polymer B contained in the composition is an oxyalkylene polymer having one terminal group per molecule and a reactive silicon group represented by formula (2) formed via one or more organic groups represented by formula (i), and the terminal group contains the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group, and has a number average molecular weight of 5,000 or less. Such a curable composition has low viscosity, and the organic group (i) contained in polymer B forms hard segments through interactions derived from hydrogen bonds. As a result, the resulting cured product has a high modulus and is less prone to bleed-out. Therefore, it is particularly useful as a material for adhesives that require high tensile strength and reduced bleed-out.

[0077] [Uses] Suitable uses of the curable composition of this embodiment include adhesives, sealants (for example, elastic sealants for construction, sealants for double glazing, rust-proofing and waterproofing sealants for glass edges, sealants for the rear surface of solar cells, sealants for buildings, sealants for ships, sealants for automobiles, and sealants for roads), and electrical insulating materials (insulating coating materials for electric wires and cables). In particular, the cured product is suitable for uses requiring good tensile strength and reduced bleed-out, such as floor adhesives.

[0078] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following descriptions.

[0079] [Average Number of Terminal Groups] The average number of terminal groups of polymer A was calculated by: average number of terminal groups of polymer A = (number of hydroxyl groups of initiator × mass% of main product derived from initiator + 2 × mass% of by-product derived from water) / 100. The average number of terminal groups of polymer B was calculated by: average number of terminal groups of polymer B = (1 × mass% of main product derived from mono-ol initiator + 2 × mass% of by-product derived from water) / 100.

[0080] [Number of reactive silicon groups] The average number of reactive silicon groups was calculated by "concentration of reactive silicon groups in the polymer [mol / g] × number average molecular weight of the polymer". The concentration of reactive silicon groups in the polymer [mol / g] was measured by NMR.

[0081] [Silylation rate] The number of reactive silicon groups per terminal group was calculated by dividing the number of reactive silicon groups by the average number of terminal groups. The silylation rate was calculated by multiplying the number of reactive silicon groups per terminal group by 100.

[0082] [Number-average molecular weight Mn and weight-average molecular weight Mw of polyoxyalkylene polymer] The measuring device used was an HLC-8420GPC (product name of Tosoh Corporation). The column used was a TSKgel Supermultipore HZ-M (product name of Tosoh Corporation), and the solvent used was tetrahydrofuran. The sample pump was set to a flow rate of 0.350 mL / min, the reference pump was set to a flow rate of 0.350 mL / min, the detector temperature was set to 40°C, and the collection time was 6 to 15 minutes. The number-average molecular weight Mn and weight-average molecular weight Mw were determined by analyzing the peaks that appeared between 6 and 11 minutes of collection time. A calibration curve was prepared using polystyrene as a standard material.

[0083] [Tensile shear test] The tensile shear test was performed in accordance with ISO 37:2017 (corresponding to JIS K 6251:2023). The curable composition to be measured was filled into a 2 mm thick mold and cured at a temperature of 23 ° C. and a humidity of 50% for 3 days, and then further cured at a temperature of 50 ° C. and a humidity of 65% for 4 days. The obtained cured product was punched using a test piece preparation machine (a sample punching machine (lever type), manufactured by Toyo Seiki Seisakusho) equipped with a test piece punching blade (dumbbell-shaped No. 3) in accordance with JIS K 6250:2019, 8.3, to obtain a dumbbell-shaped No. 3 test piece shown in FIG. 1. The test piece was subjected to a tensile test at a tensile speed of 500 mm / min using a Tensilon tester (TENSILON RTG-1310, manufactured by A&D Co., Ltd.), and the modulus (M20 / M50, unit: N / mm) was calculated as the stress at 20% and 50% elongation. ２ ), the tensile strength (Tmax, unit: N / mm ２The elongation at maximum point (elongation property, unit: %) and the elongation at maximum point (elongation property, unit: %) were measured. The details of the above test specimen shown in Figure 1 are as follows. The total length L1 of the test specimen is 100 mm, the length L2 of the narrow parallel portion is 20 mm, the length L3 from the narrow parallel portion to the end is 40 mm, and the length L4 from the narrow parallel portion to the wide parallel portion is 25 mm. The width W1 of the narrow parallel portion is 5 mm, and the width W2 of the wide parallel portion is 25 mm. The radius R1 of the shoulder portion is 11 mm, and the major radius R2 is 25 mm. The thickness of the dumbbell specimen is 2.0 mm.

[0084] [Bleed-out test] The surface of the cured product obtained under the above curing conditions was traced with a metal spatula. If a large amount of surface components was observed on the spatula, it was marked "X", if a small amount was observed, it was marked "△", and if no surface components were observed, it was marked "O". If surface components are migrated, it will lead to a loss of functionality, such as a deterioration in adhesion of the cured product to the substrate, so a score of "O" is desirable in this test.

[0085] [Compound Viscosity Measurement] Samples formulated under the conditions shown in Tables 3 to 6 below were placed in a deep-bottomed container capable of measuring viscosity, and before curing began, the viscosity (unit: Pa s) was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: RE80) at a measurement temperature of 25°C, rotor No. 7, and a rotation speed of 10 rpm. JS14000 (manufactured by Nippon Grease Co., Ltd., product name) was used as the calibration standard solution. From the viewpoint of workability, the compound viscosity is preferably 200 Pa s or less, more preferably 180 Pa s or less, and particularly preferably 160 Pa s or less.

[0086] [Measurement of Blend Viscosity of Polymer A and Polymer B] Only the components corresponding to "Polymer A" and "Polymer B" in Tables 3 to 7 described below were blended and placed in a deep-bottomed container capable of measuring viscosity. The viscosity (unit: Pa s) was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: RE80 type) at a measurement temperature of 25°C, rotor No. 7, and a rotation speed of 10 rpm. JS14000 (manufactured by Nippon Grease Co., Ltd., product name) was used as the calibration standard solution. In Tables 3 to 6, the blend viscosity measurements of Polymer A and Polymer B are referred to as "blended viscosity."

[0087] [Synthesis of Polymers] The polymers shown in Tables 1 and 2 were synthesized by the following method. Note that the number of formulas (i) in Tables 1 and 2 means the number of formulas (i) per reactive silicon group.

[0088]

[0089]

[0090] Synthesis Example 1: Polymer A-1 Using propylene glycol as an initiator and a zinc hexacyanocobaltate complex (hereinafter referred to as "TBA-DMC catalyst") having a t-butyl alcohol ligand as a catalyst, propylene oxide was polymerized to obtain an oxypropylene polymer (precursor polymer). The number average molecular weight of the precursor polymer was 10,000. Next, 0.97 molar equivalents of 3-isocyanatepropyltrimethoxysilane relative to the hydroxyl groups of the precursor polymer were added, and dioctyltin bisisooctylthioglycol (Neostan U-860: product name of Nitto Kasei Co., Ltd.) was added as a catalyst. The temperature was raised to 80°C and stirring was continued while maintaining the temperature at 80°C. Analysis was performed using a Fourier transform infrared spectrophotometer, and the reaction was continued until completion of the reaction between the hydroxyl groups and the isocyanate groups could be confirmed, yielding a polyoxyalkylene polymer (polymer A-1) having trimethoxysilyl groups introduced into the terminal groups.

[0091] (Synthesis Example 2: Polymer A-2) The precursor polymer having a molecular weight of 10,000 prepared in Synthesis Example 1 was used, and 0.97 molar equivalents of 3-isocyanatepropylmethyldimethoxysilane relative to the hydroxyl groups of the precursor polymer were added, along with dioctyltin bisisooctylthioglycol (Neostan U-860: product name of Nitto Kasei Co., Ltd.) as a catalyst. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer A-2 having a methyldimethoxysilyl group introduced into the terminal group.

[0092] (Synthesis Example 3: Polymer A-3) Propylene oxide was polymerized using propylene glycol as an initiator and a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 5,000. The subsequent steps were the same as in Synthesis Example 1, and Polymer A-3 was obtained.

[0093] (Synthesis Example 4: Polymer A-4) Propylene oxide was polymerized using propylene glycol as an initiator and a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 20,000. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer A-4.

[0094] (Synthesis Example 5: Polymer A-5) Propylene oxide was polymerized using glycerin as an initiator and a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 10,000. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer A-5.

[0095] Synthesis Example 6: Polymer A-6 Propylene oxide was polymerized using sorbitol as an initiator and a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 10,000. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer A-6.

[0096] Synthesis Example 7: Polymer B-1 Propylene oxide was polymerized using n-butyl alcohol as an initiator and TBA-DMC as a catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 3,000. The subsequent steps were the same as in Synthesis Example 1 to obtain Polymer B-1.

[0097] Synthesis Example 8: Polymer B-2 Propylene oxide was polymerized using n-butyl alcohol as an initiator and TBA-DMC as a catalyst to obtain an oxypropylene polymer (precursor polymer B'-2) having a number average molecular weight of 1,500. The subsequent steps were the same as in Synthesis Example 1, and polymer B-2 was obtained.

[0098] Synthesis Example 9: Polymer B-3 Propylene oxide was polymerized using n-butyl alcohol as an initiator and TBA-DMC as a catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 700. The subsequent steps were the same as in Synthesis Example 1, and Polymer B-3 was obtained.

[0099] Synthesis Example 10: Polymer B-4 Propylene oxide was polymerized using n-butyl alcohol as an initiator and TBA-DMC as a catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 5,000. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer B-4.

[0100] Synthesis Example 11: Polymer B-5 Using n-butyl alcohol as an initiator, propylene oxide was polymerized using a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 3,000. Next, 2 molar equivalents of isophorone diisocyanate relative to the hydroxyl groups of the precursor polymer were added, and dioctyltin bisisooctylthioglycol (Neostan U-860: product name of Nitto Kasei Co., Ltd.) was added as a catalyst. The temperature was raised to 80°C and stirred while maintaining the temperature at 80°C. The isocyanate group equivalent in the system was measured according to the method of JIS K 6860:1974, and the reaction was continued until completion of the reaction between the hydroxyl groups and the isocyanate groups could be confirmed. A prepolymer precursor having terminal groups modified with isocyanate groups was obtained, and then excess isophorone diisocyanate was removed by thermal decompression. Next, 1.03 molar equivalents of 3-trimethoxysilylpropylbutylamine relative to the isocyanate group equivalent of the prepolymer precursor was added. The temperature was raised to 80°C and stirred while maintaining the temperature at 80°C. Analysis was performed with a Fourier transform infrared spectrophotometer to allow the reaction to proceed until completion of the reaction between the hydroxy group and the isocyanate group could be confirmed, yielding Polymer B-5 in which a trimethoxysilyl group had been introduced into the terminal group via a urea group.

[0101] Synthesis Example 12: Polymer B-6 Using the precursor polymer having a molecular weight of 3,000 prepared in Synthesis Example 7, the subsequent steps were the same as in Synthesis Example 2, to obtain Polymer B-6 having a methyldimethoxysilyl group introduced at the terminal group.

[0102] Synthesis Example 13: Polymer B-7 The precursor polymer with a molecular weight of 3,000 prepared in Synthesis Example 7 was used, and a methanol solution of sodium methoxide in an amount of 1.05 molar equivalents relative to the hydroxyl groups of the precursor polymer was added to alcoholate the precursor polymer. Next, the methanol was distilled off by heating under reduced pressure, and an excess amount of allyl chloride relative to the amount of hydroxyl groups in the precursor polymer was added to convert the terminal groups to allyl groups, and then the excess allyl chloride was removed by heating under reduced pressure. Next, in the presence of chloroplatinic acid hexahydrate, 0.85 molar equivalents of methyldimethoxysilane relative to the converted allyl groups of the precursor polymer was added, and the mixture was allowed to react at 70°C for 5 hours to obtain Polymer B-7 in which methyldimethoxysilyl groups had been introduced into the terminal groups and which did not contain a -C(=O)NH- structure.

[0103] Synthesis Example 14: Polymer B-8 Propylene oxide was polymerized using n-butyl alcohol as an initiator and TBA-DMC as a catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 7,500. The subsequent steps were the same as in Synthesis Example 1, to obtain Polymer B-8.

[0104] Synthesis Example 15: Polymer B-9 Using n-butyl alcohol as an initiator, propylene oxide was polymerized using a TBA-DMC catalyst to obtain an oxypropylene polymer (precursor polymer) having a number average molecular weight of 7,500. The subsequent steps were the same as in Synthesis Example 11, to obtain Polymer B-9, in which a trimethoxysilyl group was introduced into the terminal group via a urea group.

[0105] Synthesis Example 16: Polymer B-10 Using the precursor polymer having a number average molecular weight of 7,500 prepared in Synthesis Example 14, the subsequent steps were carried out in the same manner as in Synthesis Example 2, to obtain Polymer B-10 having a methyldimethoxysilyl group introduced at the terminal group.

[0106] Synthesis Example 17: Polymer D The precursor polymer having a number average molecular weight of 10,000 prepared in Synthesis Example 1 was used as Polymer D.

[0107] [Other Components] The additives listed in Table 2 are as follows: Hakuenka CCR: Colloidal calcium carbonate, product name of Shiraishi Calcium Co., Ltd. Whiten SB: Heavy calcium carbonate, product name of Shiraishi Calcium Co., Ltd. IRGANOX 1010 (referred to as Ir1010 in the table): Hindered phenol-based antioxidant, product name of BASF Corporation TINUVIN 326 (referred to as Ti326 in the table): Benzotriazole-based light stabilizer, product name of BASF Corporation KBM-1003: Vinyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. KBM-403: 3-Glycidyloxypropyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. KBM-603: 3-(2-Aminoethylamino)propyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. U-860: Dioctyl tin catalyst, product name of Nitto Kasei Co., Ltd. S-1: Dioctyl tin catalyst, product name of Nitto Kasei Co., Ltd.

[0108] [Preparation of Curable Compositions] (Examples 1 to 25) Curable compositions were prepared using the polymers and additives in the blending amounts (parts by mass) shown in Tables 3 to 6. The blending amount of each component shown in Tables 3 to 6 is the value (unit: parts by mass) relative to 100 parts by mass of the total of Polymer A, Polymer B, and Polymer D. The above-mentioned viscosity measurements, tensile shear tests, and bleed-out tests were carried out using the obtained curable compositions. Examples 1 to 8, 18, 20, 22, and 23 are working examples, and Examples 9 to 17, 19, 21, 24, and 25 are comparative examples. The results are shown in Tables 3 to 6.

[0109]

[0110]

[0111]

[0112]

[0113] As shown in Table 3, in Examples 1 to 8 containing polymers B-1 to B-6, bleed-out was unlikely to occur in the cured product. On the other hand, in Example 9 containing polymer B-7, bleed-out occurred in the cured product. Because polymer B-7 does not contain organic group (i), it is thought that it is difficult to form hard segments caused by interactions derived from hydrogen bonds due to organic group (i), making bleed-out more likely to occur. In addition, because polymer B-7 was synthesized by method (a), impurities having unsaturated groups were by-produced, and unreacted materials having terminal allyl groups were present in the polymer, so it is thought that more polymers that do not contribute to crosslinking were present than in polymers B-1 to B-6, which is also thought to be a factor in the occurrence of bleed-out.

[0114] Furthermore, it was found that bleeding out was less likely to occur in Examples 1 to 6 and 8 compared to Example 7. This is thought to be because in Examples 1 to 6 and 8, impurities not having a reactive silyl group at the terminal group were less likely to be produced as by-products in the synthesis of Polymer B.

[0115] Furthermore, the ratio of modulus to blending viscosity of polymer A-1 and polymer B-1 (Mn: 3,000) was 0.0043 in Example 1, whereas the ratio of modulus to blending viscosity of polymer A-1 and polymer B-7 (Mn: 3,000) was 0.0014 in Example 9. That is, Example 1 demonstrated that the use of polymer B-1 having organic group (i) as a plasticizer can achieve a viscosity-reducing effect equivalent to that of B-7 while maintaining a high modulus of the cured product.

[0116] Furthermore, the ratio of the modulus to the blended viscosity of Polymer A-1 and Polymer B-1 (Mn: 3,000) was 0.0043 in Example 1, whereas the ratio of the modulus to the blended viscosity of Polymer A-1 and Polymer B-8 (Mn: 7,500) was 0.0038 in Example 12. In other words, Example 1 demonstrated that the use of Polymer B-1, which has a small Mn, as a plasticizer can reduce the viscosity of the mixture while maintaining a high modulus of the cured product.

[0117] As shown in Table 4, a comparison between Example 18 and Example 19 (polymer A-3, Mn: 5,000), in which the molecular weight of polymer A was low, showed that in Example 18, which contained polymer B-1, the ratio of modulus to the blending viscosity of polymer A-3 and polymer B-1 was 0.0103, whereas in Example 19, the ratio of modulus to the blending viscosity of polymer A-3 and polymer B-8 was 0.0086. In other words, in Example 18, it was demonstrated that the viscosity of the mixture was reduced by using polymer B-1 with a small Mn as a plasticizer, while the modulus of the cured product was maintained high. As shown in Table 5, a comparison between Example 20 and Example 21 (polymer A-4, Mn: 20,000), in which the molecular weight of polymer A was high, also showed that in Example 20, the modulus of the cured product was maintained high while the blending viscosity was reduced by using polymer B-1 with a small Mn as a plasticizer.

[0118] As shown in Table 6, even when the average number of terminal groups of polymer A was 2.90 (polymer A-5) and 5.60 (polymer A-6), in Examples 22 and 23 in which polymer B-1 was used, it was shown that the modulus of the cured product could be maintained high while reducing the compounding viscosity by using polymer B-1 with a small Mn as a plasticizer, as compared with Examples 24 and 25 in which polymer B-8 was used.

[0119] L1: total length of dumbbell test piece, L2: length of narrow parallel part, L3: length from narrow parallel part to end, L4: length from narrow parallel part to wide parallel part, W1: width of narrow parallel part, W2: width of wide parallel part, R1: radius of shoulder, R2: large radius

Claims

1. A curable composition containing polymer A and polymer B, wherein the polymer A has an average of 2.00 or more end groups per molecule and is an oxyalkylene polymer having a reactive silicon group represented by the following formula (1), the end groups of the polymer A include the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group, the polymer B has an average of 1.00 to 1.30 end groups per molecule and is an oxyalkylene polymer having a reactive silicon group represented by the following formula (2) formed through one or more organic groups represented by the following formula (i), the end groups of the polymer B include the reactive silicon group, an unsaturated group, an isocyanate group, an amino group, or a hydroxyl group, and the number average molecular weight of the polymer B is 5,000 or less. -SiR １ ａ X １ ３－ａ Formula (1) [In formula (1), R １ is a monovalent organic group having 1 to 20 carbon atoms and represents an organic group other than a hydrolyzable group, and X １ represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R １ may be the same or different from each other, and when a is 0 or 1, X １ may be the same or different from each other. ] -C(=O)NH- Formula (i) -SiR ２ ｂ X ２ ３－ｂ Formula (2) [In formula (2), R ２ is a monovalent organic group having 1 to 20 carbon atoms and represents an organic group other than a hydrolyzable group, and X ２ represents a hydroxyl group or a hydrolyzable group. b is an integer of 0 to 2. When b is 2, R ２ may be the same or different from each other, and when b is 0 or 1, X ２ may be the same or different from each other. ] 2. The curable composition according to claim 1, wherein the number of the organic groups represented by the formula (i) contained in the polymer B is 1.

3. The curable composition according to claim 1, wherein the content of the polymer B is 20 to 80 parts by mass with respect to 100 parts by mass of the total content of the polymer A and the polymer B.

4. The curable composition according to claim 1, wherein the polymer A is an oxyalkylene polymer formed through one or more of the organic groups represented by the formula (i).

5. The curable composition according to claim 1, wherein the number average molecular weight of the polymer B is 500 to 5,000.

6. The curable composition according to claim 1, wherein the number average molecular weight of the polymer A is 2,400 to 20,000.

7. The curable composition according to claim 1, wherein the total content ratio of the polymer A and the polymer B to the total mass of the curable composition is 2 to 70% by mass.

8. A cured product of the curable composition according to any one of claims 1 to 7.

Images