Curable composition, cured product, adhesive, and sealing material

Abstract

The present invention pertains to a curable composition containing a first polymer and a second polymer, wherein the first polymer is an oxyalkylene polymer having a reactive silicon group formed via one or more organic groups represented by -C(=O)NH- and having, on average, 2.00 or more terminal groups per molecule, the terminal groups of the first polymer including the reactive silicon groups, isocyanate groups, amino groups, or hydroxyl groups; and the second polymer is an oxyalkylene polymer having, on average, 1.00-1.20 terminal groups per molecule, the terminal group of the second polymer including one hydroxy group, and the number average molecular weight of the second polymer is 15,000 or less.

Description

Curable composition, cured product, adhesive, and sealant

[0001] This application claims priority to Japanese Patent Application No. 2024-027355, filed February 27, 2024, 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 are already being produced industrially and are widely used in applications such as sealants, adhesives, and paints.

[0005] Considering the ease of handling of curable compositions, plasticizers are used to reduce the viscosity of the curable compositions. Low-molecular-weight compounds such as 1,2-cyclohexanedicarboxylic acid diisononyl ester and diisononyl phthalate are widely used as plasticizers. However, when a low-molecular-weight compound is used as a plasticizer, bleeding may occur in the resulting cured product. Furthermore, the cured product tends to have poor deep curability.

[0006] Plasticizers have been investigated for the purposes of improving the deep curing properties of the cured product and suppressing bleed-out. Patent Document 1 discloses the use of a polymeric plasticizer having a number average molecular weight of 1,000 to 15,000 as a plasticizer in a curable composition containing an organic polymer having a silicon-containing group that can be crosslinked by forming a siloxane bond. Polyalkylene glycol is disclosed as an example of the polymeric plasticizer.

[0007] WO 2005 / 108491

[0008] The inventors of the present application investigated the use of polyalkylene glycol as a plasticizer. As a result, they found that although the deep curing property of the resulting cured product was improved and bleed-out was suppressed, the viscosity of the curable composition increased over time and storage stability was reduced. The present invention was made in consideration of the above circumstances, and aims to provide a curable composition that gives a cured product with high deep curing property and low bleed-out property, and has high storage stability, a cured product obtained by curing the curable composition, and an adhesive and sealant comprising the cured product.

[0009] The present invention relates to the following items [1] to [8]. [1] A curable composition comprising a first polymer and a second polymer, wherein the first polymer 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 formed via one or more organic groups represented by the following formula i, the terminal group of the first polymer containing the reactive silicon group, an isocyanate group, an amino group, or a hydroxyl group, the second polymer is an oxyalkylene polymer having an average of 1.00 to 1.20 terminal groups per molecule, the terminal group of the second polymer having one hydroxyl group, and the number average molecular weight of the second polymer is 15,000 or less. -SiR ａ X ３－ａFormula 1 In the above formula 1, R represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R may be the same or different from each other, and when a is 0 or 1, X may be the same or different from each other. -C(=O)NH- Formula i [2] The curable composition according to [1], wherein the number average molecular weight of the first polymer is 3,000 to 80,000 or 3,500 to 60,000. [3] The curable composition according to [1] or [2], wherein the number average molecular weight of the second polymer is 1,500 to 10,000 or 1,500 to 8,000. [4] The curable composition according to any one of [1] to [3], wherein the content of the second polymer is 80 parts by mass or less, 10 to 80 parts by mass, or 20 to 80 parts by mass, per 100 parts by mass of the total content of the first polymer and the second polymer. [5] The curable composition according to any one of [1] to [4], wherein the number of organic groups represented by formula i contained in the first polymer is one per terminal group. [6] A cured product obtained by curing the curable composition according to any one of [1] to [5]. [7] An adhesive comprising the cured product according to [6]. [8] A sealant comprising the cured product according to [6].

[0010] According to the present invention, it is possible to provide a curable composition that has high deep curing properties, can produce a cured product that is less likely to bleed out, and has high storage stability, a cured product obtained by curing the curable composition, and an adhesive and sealant made of the cured product.

[0011] 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 refers to an atomic group formed directly by the polymerization of a monomer. A "main chain" refers to a polymer chain formed by the polymerization of two or more monomers. The "main chain" in the oxyalkylene polymer described below refers to a portion (polyoxyalkylene chain) containing a residue obtained by removing active hydrogen from an initiator and a repeating unit based on alkylene oxide. An oxyalkylene polymer is a polymer consisting of a main chain and terminal groups. The "end group" of an oxyalkylene polymer refers to 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 an end group but is considered part of the main chain. The "number of terminal groups" in an oxyalkylene polymer is the same as the number of active hydrogen atoms in the initiator and the number of terminal groups in the precursor polymer, as described below. The average number of terminal groups will be described later. 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 "precursor polymer" refers to a polymer before the introduction of a reactive silicon group, an oxyalkylene polymer having a hydroxyl terminal group obtained by polymerizing an alkylene oxide with the active hydrogen of an initiator.

[0012] The "silylation rate" is the ratio of the number of reactive silicon groups to the total number of reactive silicon groups, hydroxyl groups, isocyanate groups, and amino groups in the terminal groups of an oxyalkylene polymer. Specifically, the silylation rate is calculated by the following formula: Silylation rate (%) = 100 × number of reactive silicon groups / [number of reactive silicon groups + number of hydroxyl groups + number of isocyanate groups + number of amino groups]. The value of the silylation rate can be measured by NMR analysis. Alternatively, it may be 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. The "silylating agent" refers to a compound having a reactive silicon group and a functional group that reacts with an active hydrogen-containing group or an isocyanate group.

[0013] 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.

[0014] <Curable Composition> The curable composition of this embodiment comprises a first oxyalkylene polymer (hereinafter also 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 formed via one or more organic groups represented by the following formula i; and a second oxyalkylene polymer (hereinafter also referred to as "polymer B") having an average of 1.00 to 1.20 terminal groups per molecule, each terminal group having one hydroxyl group. The terminal group of polymer A comprises the reactive silicon group, an isocyanate group, an amino group, or a hydroxyl group. The Mn of polymer B is 15,000 or less. -SiR ａ X ３－ａ Formula 1 In the above formula 1, R represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R may be the same or different from each other, and when a is 0 or 1, X may be the same or different from each other. -C(=O)NH- Formula i

[0015] <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 ａ X ３－ａ Formula 1

[0016] In the above formula 1, R represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group. R is preferably at least one group selected from the group consisting of hydrocarbon groups having 1 to 20 carbon atoms and triorganosiloxy groups.

[0017] R is preferably at least one group 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 group 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 in view of the good curability of the polymer having a reactive silicon group and the stability of the curable composition. An α-chloromethyl group is preferred in view of the fast curing rate of the cured product. A methyl group is particularly preferred in view of its ready availability.

[0018] In the above formula 1, X 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.

[0019] In the above formula 1, a is an integer of 0 to 2. When a is 2, R may be the same or different from each other. When a is 1 or less, X may be the same or different from each other. If the crosslinking density due to 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.

[0020] Examples of the reactive silicon group represented by the above 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 trimethoxysilyl group and a dimethoxymethylsilyl group are more preferred.

[0021] <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 the above formula 1 formed via one or more organic groups represented by the following formula i, wherein the terminal group is the reactive silicon group, an isocyanate group, an amino group, or a hydroxyl group. The curable composition may contain two or more types of polymer A. -C(=O)NH- Formula i

[0022] Polymer A is a polymer consisting of a main chain and terminal groups. The main chain of polymer A is a polymer chain including a residue obtained by removing active hydrogen from an initiator and an oxyalkylene chain consisting of one or more repeating units based on alkylene oxide (hereinafter, a repeating unit based on a monomer will be simply referred to as a "monomer unit", for example, a repeating unit based on alkylene oxide will be referred to as an "alkylene oxide unit"). The main chain of polymer A is preferably a polymer chain consisting of a residue obtained by removing active hydrogen from an initiator and an oxyalkylene chain consisting of one or more alkylene oxide units.

[0023] In the case of a polymer chain having two or more types of alkylene oxide units, the alkylene oxide units may form a block polymer or a random polymer.

[0024] Examples of the oxyalkylene chain include a polymer chain having an ethylene oxide unit, a polymer chain having a propylene oxide unit, a polymer chain having an ethylene oxide unit and a propylene oxide unit, a polymer chain consisting of an ethylene oxide unit, a polymer chain consisting of a propylene oxide unit, a polymer chain consisting of a butylene oxide unit, a polymer chain consisting of a tetramethylene oxide unit, a polymer chain consisting of an ethylene oxide unit and a propylene oxide unit, and a polymer chain consisting of a propylene oxide unit and a butylene oxide unit. A polymer chain having an ethylene oxide unit, a polymer chain having a propylene oxide unit, a polymer chain having an ethylene oxide unit and a propylene oxide unit, a polymer chain consisting of a propylene oxide unit, and a polymer chain consisting of an ethylene oxide unit and a propylene oxide unit are preferred, with a polymer chain consisting of a propylene oxide unit being particularly preferred. Furthermore, when polymer A has a polymer chain containing an ethylene oxide unit, the content of the ethylene oxide unit relative to the total mass of polymer A is preferably 0.1 to 30% by mass, more preferably 10 to 20% by mass. When the content of ethylene oxide units in polymer A is equal to or greater than the above-mentioned lower limit, it is preferred in that the curing rate is faster, and when it is equal to or less than the above-mentioned upper limit, it is preferred in that the viscosity can be easily reduced. 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%, and 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 ethylene oxide units and propylene oxide units, the content of propylene oxide units relative to the total mass of polymer A is preferably 50 to 99.9 mass%, and more preferably 70 to 90 mass%.

[0025] Polymer A has an average of 2.00 or more terminal groups per molecule. The average number of terminal groups is preferably 2.00 to 10.00, more preferably 2.00 to 8.00, and even more preferably 2.00 to 6.00, because this results in a cured product with higher tensile strength and better modulus and elongation. The terminal groups of polymer A are any of the reactive silicon groups, isocyanate groups, amino groups, and hydroxyl groups represented by the above formula 1. The respective terminal groups may be the same or different.

[0026] In the production of polymer A described below, in addition to a precursor polymer (main precursor polymer A) in which alkylene oxide is polymerized with a specific initiator, a diol precursor polymer (minor precursor polymer A) in which alkylene oxide is polymerized with water in the reaction system may be produced. In this case, in addition to the oxyalkylene polymer (main polymer A) having two or more terminal groups per molecule and formed via one or more organic groups, which is produced from the main precursor polymer A by silylation described below, polymer A may also contain an oxyalkylene polymer (minor polymer A) having two or more terminal groups per molecule and formed via one or more organic groups, which is produced from the minor precursor polymer A by silylation described below. In this case, the number of terminal groups of polymer A may not match the number of active hydrogen atoms of the specific initiator (especially when the number of active hydrogen atoms of the specific initiator is three or more). The average number of terminal groups per molecule of polymer A is calculated using the following formula 1A: Average number of terminal groups of polymer A = [number of active hydrogen atoms in a given initiator (units) × content of main polymer A (% by mass) + 2 × content of sub polymer A (% by mass)] / 100 Formula 1A In the above Formula 1A, the total of the content of main polymer A and the content of sub polymer A is 100% by mass. The content of sub polymer A relative to the total mass of polymer A is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 0% by mass.

[0027] The average number of reactive silicon atoms per terminal group of polymer A is preferably 0.50 to 2.00, more preferably 0.60 to 1.94. When the average number is equal to or greater than the lower limit of the above range, the crosslinking density due to siloxane bonds increases, and a good cured product with a high modulus can be obtained.

[0028] The average number of reactive silicon atoms per molecule of polymer A is preferably 1.80 to 10.00, more preferably 1.80 to 8.00, and even more preferably 1.80 to 6.00. If the average 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 can be obtained.

[0029] The number of organic groups represented by the above formula i per terminal group of polymer A is preferably 1 or 2, and more preferably 1. When the number of organic groups represented by the above formula i per terminal group of the polymer is 1, the initial viscosity of polymer A is more likely to be reduced than when the number is 2. In addition, deep section curability is also more likely to be improved.

[0030] The Mn of polymer A is preferably 2,400 to 100,000, more preferably 3,000 to 80,000, even more preferably 3,500 to 60,000, and particularly preferably 10,000 to 60,000. 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.

[0031] The Mw / Mn of polymer A is preferably 1.80 or less. A smaller Mw / Mn is preferable, more preferably 1.00 to 1.60, even more preferably 1.00 to 1.50, still more preferably 1.00 to 1.40, and particularly preferably 1.00 to 1.20, because good elongation properties are likely to be obtained and the viscosity is reduced, resulting in good workability.

[0032] (Method for Producing Polymer A) Examples of methods for producing polymer A include the following methods (a) and (b). Method (a): A method in which a silylating agent having a functional group reactive with the active hydrogen and a reactive silicon group represented by formula 1 above reacts with the active hydrogen of a precursor polymer to convert the active hydrogen-containing group into a group having a reactive silicon group represented by formula 1 above. Method (b): A method in which the active hydrogen-containing group of a precursor polymer is converted into a group having an isocyanate group, and then a silylating agent having a functional group reactive with the isocyanate group and a reactive silicon group represented by formula 1 above reacts with the precursor polymer to convert the hydroxyl group into a group having a reactive silicon group represented by formula 1 above.

[0033] [Method for Producing Precursor Polymer] 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 or more, more preferably 2 to 10, even more preferably 2 to 8, and particularly preferably 2 to 6. The number of active hydrogens in the initiator is preferably selected depending on the number of reactive silicon groups per molecule of the polymer A to be obtained. The number of active hydrogens in the initiator and the number of terminal groups in the polymer A are the same. One type of initiator may be used alone, or two or more types may be used in combination.

[0034] 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 polyoxypropylene glycol. Water is also an example of an initiator having two hydroxyl groups. Examples of initiators having three hydroxyl groups include glycerin, trimethylolpropane, trimethylolethane, and polyoxypropylenetriol. Examples of initiators having four or more hydroxyl groups include pentaerythritol, sucrose, sorbitol, dipentaerythritol, trehalose, and diglycerin.

[0035] 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.

[0036] 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 small Mw / Mn ratio and a small 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.

[0037] The polyoxyalkylene chains of the precursor polymer and polymer A are preferably produced by a method in which alkylene oxides including propylene oxide are polymerized with an initiator in the presence of a double metal cyanide complex. When the polyoxyalkylene chains of the precursor polymer and polymer A are random copolymer chains, for example, the precursor polymer is preferably produced by a method in which a mixture of ethylene oxide and propylene oxide is reacted with an initiator in the presence of a double metal cyanide complex.

[0038] When the polyoxyalkylene chains of the precursor polymer and polymer A 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 by polymerizing an alkylene oxide with an initiator in the presence of a composite metal cyanide complex, and then polymerizing ethylene oxide in the presence of an alkali metal hydroxide is preferred. For example, a method of polymerizing propylene oxide with an initiator in the presence of a composite metal cyanide complex, and then polymerizing ethylene oxide in the presence of an alkali metal hydroxide to obtain the precursor polymer is preferred. Alternatively, a method of reacting a mixture of ethylene oxide and propylene oxide with an initiator in the presence of a composite metal cyanide complex, and then polymerizing ethylene oxide in the presence of an alkali metal hydroxide to obtain the precursor polymer is preferred. 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.

[0039] The Mn of the precursor polymer is preferably from 2,400 to 100,000, more preferably from 3,000 to 80,000, and particularly preferably from 3,500 to 60,000. It is preferable to set it depending on the Mn of the polymer A to be obtained.

[0040] 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 1.60 or less, more preferably 1.50 or less, even more preferably 1.40 or less, and particularly preferably 1.20 or less. The lower limit is not particularly limited. For example, 1.00 or more is preferable. 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 1.60, more preferably 1.00 to 1.50, even more preferably 1.00 to 1.40, and particularly preferably 1.00 to 1.20.

[0041] The total unsaturation degree of the precursor polymer is preferably 0.1 meq / g or less, more preferably 0.05 meq / g or less, even more preferably 0.03 meq / g or less, and particularly preferably 0.01 meq / g or less. When it is below the above upper limit, excellent deep section curing properties are achieved. The lower limit is not particularly limited. For example, 0.0001 meq / g or more is preferred. The total unsaturation degree of the precursor polymer is preferably 0.0001 to 0.1 meq / g, more preferably 0.0001 to 0.05 meq / g, even more preferably 0.0001 to 0.03 meq / g, and particularly preferably 0.0001 to 0.01 meq / g. The total unsaturation degree can be measured in accordance with JIS K 1557-3:2007.

[0042] [Method (a)] In method (a), a silylating agent having a functional group reactive with the active hydrogen and a reactive silicon group represented by the above formula 1 is reacted with the active hydrogen of the precursor polymer. The functional group is preferably an isocyanate group. It is preferable to use an isocyanate silane compound represented by the following formula 2 as the silylating agent: OCN-(CH ２ ) ｎ -SiR ａ X ３－ａ ...Formula 2 -SiR in the above formula 2 ａ X ３－ａ is the same as in formula 1 above. n is an integer of 1 to 8, preferably 1 to 3. When the active hydrogen-containing group of the precursor polymer is a hydroxyl group, the hydroxyl group of the precursor polymer is converted to —O—C(═O)NH—(CH ２ ) ｎ -SiR ａ X ３－ａ A urethane bond (—O—C(═O)NH—) and —SiR ａ X ３－ａ is converted to an end group having the formula:

[0043] Examples of the isocyanate silane compound include 3-isocyanate propyl trimethoxy silane, 3-isocyanate propyl triethoxy silane, isocyanate methyl trimethoxy silane, isocyanate methyl triethoxy silane, 3-isocyanate propyl methyl dimethoxy silane, 3-isocyanate propyl methyl diethoxy silane, isocyanate methyl methyl dimethoxy silane, and isocyanate methyl methyl diethoxy silane.

[0044] As the isocyanate silane compound, 3-isocyanate propyl trimethoxy silane, 3-isocyanate propyl triethoxy silane, 3-isocyanate propyl methyl dimethoxy silane, isocyanate methyl methyl dimethoxy silane and isocyanate methyl trimethoxy silane are preferred in view of reactivity with the precursor polymer and ease of handling.

[0045] The active hydrogen of the precursor polymer reacts with the isocyanate group of the isocyanate silane compound represented by the above formula 2, 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 ａ X ３－ａ That is, in the case of method a, a polymer A having one organic group represented by the above formula i per terminal group of the polymer A is obtained.

[0046] 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.

[0047] The molar ratio of the total number of isocyanate groups in the isocyanate silane compound represented by Formula 2 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 2 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, the NCO / OH ratio, which represents the molar ratio of the total number of isocyanate groups (NCO) in the isocyanate silane compound represented by Formula 2 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.

[0048] [Method (b)] In method (b), first, the active hydrogen-containing groups of the precursor polymer are converted into groups having an isocyanate group. A preferred method for converting the active hydrogen-containing groups of the precursor polymer into groups having an isocyanate group is to react the active hydrogen-containing groups of the precursor polymer with a compound having an isocyanate group and a functional group reactive with the active hydrogen-containing groups. The functional group is preferably an isocyanate group. That is, the compound is preferably a polyisocyanate compound having two or more isocyanate groups. In this case, the active hydrogen of the precursor polymer is reacted with the isocyanate groups of the polyisocyanate compound to convert the active hydrogen-containing groups into monovalent organic groups containing a urethane bond (—O—C(═O)NH—) and an isocyanate group (hereinafter also referred to as “isocyanate-containing groups”). Thereafter, the isocyanate-containing group is reacted with a silylating agent having a functional group reactive with an isocyanate group and a reactive silicon group represented by the above formula 1 to form a terminal group that is a monovalent organic group having one or more urethane bonds (—O—C(═O)NH—) and a silylating agent residue reacted with an isocyanate group (hereinafter also referred to as a “urethane bond-and-reactive silicon group-containing group”). Hereinafter, method (b) will be explained assuming that the polyisocyanate compound is a diisocyanate compound represented by the following formula 3, 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 4, but the present invention is not limited to these.

[0049] OCN-R １ -NCO Formula 3 R in the above formula 3 １ represents a divalent organic group.

[0050] W-R ２ -SiR ａ X ３－ａ In the above formula 4, W represents a functional group (a group having one or more active hydrogens) capable of reacting with a monovalent isocyanate group, R ２ is a divalent organic group, -SiR ａ X ３－ａ is the same as Equation 1 above.

[0051] When the active hydrogen-containing group of the precursor polymer is a hydroxyl group, when the hydroxyl group is reacted with the polyisocyanate compound represented by the above formula 3, the isocyanate-containing group becomes -O-C(=O)NH-R １ When the isocyanate-containing group is reacted with the silylating agent represented by the formula 4, the urethane bond and the reactive silicon-containing group are converted to a group represented by the formula -O-C(=O)NH-R １ -NHC(=O)-W'-R ２ -SiR ａ X 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 １ -NHC(=O)-OR ２ -SiR ａ X 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 １ -NHC(=O)-NH-R ２ -SiR ａ X ３－ａ That is, in the case of method b, a polymer A having two organic groups represented by the above formula i per terminal group of the polymer A is obtained.

[0052] R １is 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.

[0053] Examples of the diisocyanate compound represented by the above formula 3 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.

[0054] 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.

[0055] The functional group capable of reacting with an isocyanate group represented by the above formula 4 and —SiR ａ X ３－ａ R in the silylating agent having ２As 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.

[0056] The molar ratio of the total number of silylating agents represented by Formula 4 to the total number of isocyanate groups derived from the isocyanate-containing group is preferably set according to the number of reactive silicon groups per molecule of the polymer A to be obtained. The silylating agent represented by Formula 4 is reacted so that the resulting polymer A has at least 1.8 reactive silicon groups per molecule. For example, the NCO / silylating agent ratio, which represents the molar ratio of the total number of isocyanate groups in the isocyanate-containing group to the total number of functional groups reactive with monovalent isocyanate groups in the silylating agent represented by Formula 4, 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 it is equal to or less than the upper limit, the elongation of the cured product is excellent.

[0057] (Silylation rate, etc.) 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 will have 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. The silylation rate can be controlled by adjusting the NCO / OH ratio in method a, or by adjusting the NCO / silylating agent ratio in method b.

[0058] It is more preferable that polymer A is an oxyalkylene polymer having a reactive silicon group formed via one organic group represented by the above formula i, because the hydrogen bonds generated from the organic group increase the moisture permeability into the inside of the cured product, thereby improving deep curing properties.

[0059] <Polymer B> Polymer B has an average of 1.00 to 1.20 terminal groups per molecule, and the terminal group has one hydroxyl group. Polymer B has an Mn of 15,000 or less. The curable composition may contain two or more types of polymer A. Polymer B preferably does not have the reactive silicon group, double bond at the molecular terminal, amino group, or isocyanate group.

[0060] Polymer B is a polymer consisting of a main chain and terminal groups. The main chain of polymer B is a polymer chain containing a residue obtained by removing active hydrogen from an initiator and an oxyalkylene chain consisting of one or more types of alkylene oxide units. The main chain of polymer B is preferably a polymer chain containing a residue obtained by removing active hydrogen from an initiator and an oxyalkylene chain consisting of one or more types of alkylene oxide units. Preferred embodiments of the oxyalkylene chain are the same as those of polymer A.

[0061] Polymer B has an average of 1.00 to 1.20 terminal groups. The average number of terminal groups is preferably 1.00 to 1.20, more preferably 1.00 to 1.15, and even more preferably 1.00 to 1.10. The terminal group of polymer B has one hydroxyl group. The terminal group of polymer B is preferably a hydroxyl group. When the average number of terminal groups is equal to or greater than the lower limit, the curable composition containing polymer A and polymer B has excellent deep curing properties. When the average number of terminal groups is equal to or less than the upper limit, the curable composition containing polymer A and polymer B has excellent storage stability.

[0062] In the production of polymer B described below, in addition to a polymer (main polymer B) having one terminal hydroxyl group per molecule formed by polymerization of alkylene oxide with an initiator having one active hydrogen, polymer B may also contain a polymer (sub-polymer B) having two terminal hydroxyl groups per molecule formed by polymerization of alkylene oxide with water in the reaction system. In this case, polymer B may not have one terminal group. The average number of terminal groups per molecule of polymer B is calculated using the following formula 1B: Average number of terminal groups of polymer B = [1 × content of main polymer B (% by mass) + 2 × content of sub-polymer B (% by mass)] / 100 Formula 1B In the above formula 1B, the sum of the content of main polymer B and the content of sub-polymer B is 100% by mass. The content of sub-polymer B relative to the total mass of polymer B is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 0% by mass.

[0063] The average number of hydroxyl groups per molecule of polymer B is preferably 1.00 to 1.20, more preferably 1.00 to 1.15, and even more preferably 1.00 to 1.10. The average number of hydroxyl groups per molecule of polymer B is the same as the average number of terminal groups per molecule of polymer B. When the average number of hydroxyl groups is equal to or greater than the lower limit, the curable composition containing polymer A and polymer B has excellent deep curing properties. When the average number of hydroxyl groups is equal to or less than the upper limit, the curable composition containing polymer A and polymer B has excellent storage stability.

[0064] The Mn of polymer B is 15,000 or less, preferably 1,500 to 15,000, more preferably 1,500 to 10,000, and even more preferably 1,500 to 8,000. When the Mn is equal to or greater than the lower limit of the above range, the cured product has superior tensile strength and a higher modulus. In particular, when the Mn of polymer B is 1,500 or greater, bleed-out is easily suppressed. When the Mn is equal to or less than the upper limit of the above range, viscosity is suppressed and workability is improved. In addition, the number of hydroxyl groups per unit mass of polymer B is likely to be sufficient. As a result, the curable composition is more likely to absorb an appropriate amount of water, curing progresses to the interior, and the cured product has excellent deep curing properties.

[0065] The Mw / Mn of polymer B is preferably 1.80 or less. A smaller Mw / Mn is preferable, more preferably 1.00 to 1.60, still more preferably 1.02 to 1.50, still more preferably 1.04 to 1.40, and particularly preferably 1.04 to 1.20, since good elongation properties are likely to be obtained and the viscosity is reduced, resulting in good workability.

[0066] (Method for producing polymer B) Examples of methods for producing polymer B include the same methods as those for producing the precursor polymer of polymer A, except that an initiator having one active hydrogen is used. That is, the precursor polymer described for polymer A is polymer B. However, an initiator having one active hydrogen is used as the initiator. The number of active hydrogens in the initiator and the number of terminal groups in oxyalkylene polymer B are the same. One type of initiator may be used alone, or two or more types may be used in combination.

[0067] The initiator having one active hydrogen is preferably a monohydric alcohol having a linear or branched hydrocarbon group, specific examples of which 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 polyoxyalkylene monool.

[0068] The total unsaturation degree of polymer B is preferably 0.1 meq / g or less, more preferably 0.05 meq / g or less, even more preferably 0.03 meq / g or less, and particularly preferably 0.01 meq / g or less. When it is equal to or less than the above upper limit, excellent deep section curing properties are achieved. The lower limit is not particularly limited. For example, 0.0001 meq / g or more is preferred. The total unsaturation degree of the precursor polymer is preferably 0.0001 to 0.1 meq / g, more preferably 0.0001 to 0.05 meq / g, even more preferably 0.0001 to 0.03 meq / g, and particularly preferably 0.0001 to 0.01 meq / g.

[0069] <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 the above 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, it is preferably 1.0 or more, and more preferably 1.2 or more. From the viewpoint of good elongation of the cured product, it is preferably 4.0 or less, and more preferably 3.0 or less. The average number of reactive silicon groups per molecule of polymer C is calculated by "concentration of reactive silicon groups in polymer C [mol / g] x Mn of polymer C". The concentration [mol / g] of reactive silicon groups in polymer C can be measured by NMR. As the monomer constituting the main chain of polymer C, for example, conventionally known monomers described in JP-B-3-14068, JP-A-6-211922, and JP-A-11-130931 can be used. Examples of monomers containing a reactive silicon group and an unsaturated group to be copolymerized with the above-mentioned 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 the monomers constituting the polymer C is preferably 50% by mass or more, more preferably 70% by mass or more, and may be 100% by mass.

[0070] 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 a narrow Mw / Mn ratio 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.).

[0071] 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 Mw / Mn is equal to or less than the upper limit, the workability is superior. The Mw / Mn of polymer C is preferably 4.0 or less, and more preferably 3.0 or less. When the Mw / Mn is equal to or less than the upper limit, the workability is superior.

[0072] <Composition of 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%. When the content is equal to or less than the upper limit of the above range, the cured product will have 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 will decrease and the elongation properties will be better. When the content is equal to or less than the upper limit of the above range, the cured product will have better tensile strength and a higher modulus.

[0073] The combined content of polymer A and polymer B relative to the total mass of the curable composition is preferably 2 to 95 mass%, more preferably 2 to 80 mass%, even more preferably 2 to 70 mass%, particularly preferably 3 to 60 mass%, and most preferably 4 to 50 mass%. When the combined content is at least the lower limit of the above range, the curability is good, and the cured product has excellent tensile strength and a high modulus.

[0074] The content of the polymer B is preferably 80 parts by mass or less, more preferably 10 to 80 parts by mass, and particularly preferably 20 to 80 parts by mass, relative to 100 parts by mass of the total content of the polymer A and the 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 tensile strength of the cured product becomes superior. When the content is equal to or less than the upper limit of the above range, the tensile strength and modulus become superior.

[0075] When the curable composition contains polymer C, the content of polymer C relative to 100 parts by mass of the total of polymer A 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. When the content is equal to or less than the upper limit of the above range, the weather resistance of the cured product of the curable composition becomes better. Note that the curable composition does not necessarily contain polymer C.

[0076] The content of components other than the polymers A to C relative to the total mass of the curable composition is preferably from 20 to 90 mass %, more preferably from 25 to 80 mass %, and even more preferably from 30 to 70 mass %.

[0077] [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.

[0078] 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.

[0079] [Mechanism of Action] Polymer B of the present invention has a higher molecular weight than conventionally used low-molecular-weight compounds such as 1,2-cyclohexanedicarboxylic acid diisononyl ester and diisononyl phthalate, and is therefore less susceptible to bleed-out. Furthermore, Polymer B has an average of 1.00 to 1.20 terminal groups per molecule, each of which has one hydroxyl group. As a result, the hydroxyl groups are thought to facilitate the absorption of an appropriate amount of water into the interior of the curable composition, allowing curing to proceed to the interior and resulting in excellent deep curing of the cured product. Furthermore, conventionally used polymers having two terminal groups per molecule, each of which has one hydroxyl group, have two hydroxyl groups per molecule, which facilitate the absorption of excessive amounts of water into the curable composition and reduce storage stability. On the other hand, since polymer B of the present invention has an average of 1.00 to 1.20 hydroxyl groups per molecule, it is thought that excessive water is less likely to be absorbed into the curable composition, and that the storage stability is also excellent.

[0080] [Uses] Suitable uses of the curable composition of the present embodiment include adhesives, sealants (for example, elastic sealants for construction, sealants for double glazing, anti-rust and waterproof 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 curable composition is suitable for uses requiring good deep curing properties and reduced bleed-out, such as elastic sealants for construction, elastic adhesives for vehicles, and adhesives for electronic components.

[0081] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following descriptions.

[0082] [Mn and Mw / Mn of Oxyalkylene Polymer] The measurement 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 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. Mn and Mw were determined by analyzing the peaks that appeared between 6 and 11 minutes into the collection time. A calibration curve was prepared using polystyrene as a standard material.

[0083] [Measurement of Initial Compound Viscosity] A sample (curable composition) formulated under the conditions shown in Table 3 below was placed in a deep-bottomed container capable of measuring viscosity, and before curing began, the viscosity (initial compound viscosity) was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: RE80 Model) 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 liquid.

[0084] [Measurement of Compound Viscosity During Storage] A sample (curable composition) formulated under the conditions shown in Table 3 below was filled into a container, purged with nitrogen, and then the container was closed and placed in a 50°C oven. After two weeks, the container was removed from the oven and the contents were placed in a deep-bottomed container suitable for viscosity measurement. Before curing began, the viscosity (compound viscosity during storage) 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. The storage viscosity increase rate was calculated using the following formula: Storage viscosity increase rate = Compound viscosity during storage / Initial viscosity of compound. For example, a storage viscosity increase rate of 1.20 or less can be determined to have excellent storage stability.

[0085] [Bleed-out Test] A sample (curable composition) formulated under the conditions shown in Table 3 below was filled into a 2-mm-thick mold and aged for 3 days at 23°C and 50% humidity, followed by 4 days at 50°C and 65% humidity. The surface of the resulting cured product was traced with a metal spatula. If a large amount of the surface component was transferred to the spatula, the test was marked with "X." If a small amount of the surface component was transferred to the spatula, the test was marked with "△." If no surface component was transferred to the spatula but a tacky feeling caused by the bleed-out component was observed, the test was marked with "○." If no surface component was transferred to the spatula and no tacky feeling was observed, the test was marked with "◎." If a large amount of the surface component was transferred, the cured product would lose its functionality, such as by poor adhesion to the substrate. Therefore, this test is preferably rated as "△," "◯," or "◎."

[0086] [Deep Curability Measurement] A cylindrical polyethylene tube with an inner diameter of 24 mm and a height of 55 mm was placed so that one opening was in contact with an aluminum plate. The tube was filled with the curable composition obtained in Table 3 through the other opening in an atmosphere of 23°C and 50% relative humidity, taking care to prevent bubbles from entering. The curable composition that protruded from the other opening of the filled tube was scraped off with a spatula to flatten the surface of the curable composition at the end of the tube, thereby obtaining a test specimen. The obtained test specimen was placed in the atmosphere, and after 7 days, the extent of curing progress from the surface to the interior of the curable composition was examined. Specifically, the cured surface layer (cured portion) of the cured curable composition was removed with a spatula, and uncured curable composition adhering to the removed cured portion was removed. The thickness (unit: mm) of the resulting cured portion (in the height direction of the tube) was measured using a vernier caliper. The removed cured portion was often cylindrical, and the thickest part of the cured portion was measured. The greater the thickness of the cured portion, the better the deep curing. For example, if the thickness is 2.9 mm or more, it can be determined that the deep curing is excellent.

[0087] Synthesis Example 1: Synthesis of 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 Precursor Polymer 1, an oxypropylene polymer having an Mn of 20,000. Next, 0.97 molar equivalents of 3-isocyanatepropyltrimethoxysilane relative to the hydroxyl groups of Precursor Polymer 1 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 oxypropylene Polymer A-1 having trimethoxysilyl groups introduced into the terminal groups. Table 1 shows the average number of terminal groups, the type of reactive silicon group, the number of reactive silicon groups per molecule, the number of organic groups represented by formula i per terminal group, Mn, and Mw / Mn of polymer A-1 (hereinafter, the same applies to polymers A-2 to A-7 and polymer a-1).

[0088] Synthesis Example 2: Synthesis of Polymer A-2 Using propylene glycol as an initiator and TBA-DMC catalyst, propylene oxide was polymerized using a different amount of propylene oxide from that used in Synthesis Example 1, to obtain Precursor Polymer 2, an oxypropylene polymer having an Mn of 40,000. Except for using Precursor Polymer 2 instead of Precursor Polymer 1, the same procedure as in Synthesis Example 1 was repeated to obtain an oxypropylene polymer A-2 having a trimethoxysilyl group introduced into the terminal group.

[0089] Synthesis Example 3 Synthesis of Polymer A-3 Propylene oxide was polymerized using propylene glycol as an initiator and a TBA-DMC catalyst, but the amount of propylene oxide was changed from that in Synthesis Example 1, to obtain Precursor Polymer 3, an oxypropylene polymer having an Mn of 60,000. Except for using Precursor Polymer 3 instead of Precursor Polymer 1, the same procedure as in Synthesis Example 1 was repeated to obtain an oxypropylene polymer A-3 having a trimethoxysilyl group introduced into the terminal group.

[0090] Synthesis Example 4: Synthesis of Polymer A-4 The precursor polymer 1 synthesized in Synthesis Example 1 was used. Two molar equivalents of isophorone diisocyanate were added relative to the hydroxyl groups of precursor polymer 1, 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. The isocyanate group equivalent in the system was measured in accordance with Method B of JIS K 1603:2007, and the reaction was continued until completion of the reaction between the hydroxyl groups and the isocyanate groups could be confirmed, thereby obtaining prepolymer precursor 1 in which an isocyanate group had been introduced into the terminal group. Next, 1.03 molar equivalents of 3-trimethoxysilylpropylbutylamine relative to the isocyanate groups of prepolymer precursor 1 was added. The temperature was raised to 80°C and stirring was continued while maintaining the temperature at 80°C. Analysis was performed with a Fourier transform infrared spectrophotometer, and the reaction was continued until completion of the reaction between the hydroxyl group and the isocyanate group could be confirmed, thereby obtaining an oxypropylene polymer A-4 in which a trimethoxysilyl group was introduced into the terminal group via the urea group.

[0091] Synthesis Example 5 Synthesis of Polymer A-5 Using glycerin as an initiator and TBA-DMC catalyst, propylene oxide was polymerized to obtain Precursor Polymer 5, an oxypropylene polymer having an Mn of 20,000. Except for using Precursor Polymer 5 instead of Precursor Polymer 1, the same procedure as in Synthesis Example 1 was carried out to obtain Oxypropylene Polymer A-5 having a trimethoxysilyl group introduced into the terminal group.

[0092] Synthesis Example 6 Synthesis of Polymer A-6 Using sorbitol as an initiator, propylene oxide was polymerized using a TBA-DMC catalyst to obtain Precursor Polymer 6, an oxypropylene polymer having an Mn of 20,000. Except for using Precursor Polymer 6 instead of Precursor Polymer 1, the same procedure as in Synthesis Example 1 was carried out to obtain an oxypropylene polymer A-6 having a trimethoxysilyl group introduced into the terminal group.

[0093] Synthesis Example 7 Synthesis of Polymer A-7 Precursor Polymer 1 synthesized in Synthesis Example 1 was used. 0.97 molar equivalents of 3-isocyanatepropylmethyldimethoxysilane was added relative to the hydroxyl groups of Precursor Polymer 1, 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 with 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 oxypropylene polymer A-7 having methyldimethoxysilyl groups introduced into the terminal groups.

[0094] Synthesis Example 8 Synthesis of Polymer a-1 Precursor polymer 1 synthesized in Synthesis Example 1 was used. Precursor polymer 1 was alcoholated by adding 1.05 molar equivalents of a methanol solution of sodium methoxide relative to the hydroxyl groups of precursor polymer 1. Next, the methanol was distilled off by heating under reduced pressure, and an excess amount of allyl chloride relative to the hydroxyl groups of precursor polymer 1 was added to obtain precursor polymer 1-1 in which the terminal groups had been converted to allyloxy groups. Next, in the presence of chloroplatinic acid hexahydrate, 0.85 molar equivalents of methyldimethoxysilane relative to the allyloxy groups of precursor polymer 1-1 was added, and the mixture was allowed to react at 70°C for 5 hours to obtain oxypropylene polymer a-1 in which methyldimethoxysilyl groups had been introduced into the terminal groups and which did not contain a -C(=O)NH- structure.

[0095] Synthesis Example 9 Synthesis of 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 B-1 having an Mn of 3,000. Table 2 shows the average number of terminal groups, the type of terminal group, Mn, and Mw / Mn of polymer B-1 (hereinafter, the same applies to polymers B-2 to B-6 and polymers b-1 to b-3).

[0096] (Synthesis Examples 10 to 15: Synthesis of Polymers B-2 to B-6, b-1) Oxypropylene polymers B-2 to B-6, b-1 were obtained in the same manner as in Synthesis Example 9, except that the amount of propylene oxide was changed so as to obtain the Mn shown in Table 2.

[0097] Synthesis Example 16 Synthesis of Polymer b-2 Propylene oxide was polymerized using propylene glycol as an initiator and a TBA-DMC catalyst as a catalyst to obtain an oxypropylene polymer b-2 having an Mn of 3,000. The oxypropylene polymer b-2 has two hydroxyl terminal groups per molecule.

[0098] Synthesis Example 17 Synthesis of Polymer b-3 Oxypropylene polymer B-1 synthesized in Synthesis Example 9 was alcoholated by adding 1.05 molar equivalents of a methanol solution of sodium methoxide relative to the hydroxyl groups of the 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 polymer B-1 was added to obtain oxypropylene polymer b-3 converted to allyloxy groups. Oxypropylene polymer b-3 has one terminal allyloxy group per molecule.

[0099]

[0100]

[0101] [Preparation of Curable Compositions] (Examples 1 to 22) Curable compositions were prepared using the polymers and additives in the amounts (parts by mass) shown in Table 3. The amount of each component shown in Table 3 is in parts by mass. The above-mentioned viscosity measurements, bleed-out tests, and deep section curing measurements were carried out using the obtained curable compositions. Examples 1 to 14 are working examples, and Examples 15 to 22 are comparative examples. The results are shown in Table 3.

[0102] [Other Components] The additives listed in Table 3 are as follows: DINP: 1,2-cyclohexanedicarboxylic acid diisononyl ester, product name of BASF. DINCH: diisononyl phthalate, product name of Kao Corporation. Hakuenka CCR: colloidal calcium carbonate, product name of Shiraishi Calcium Co., Ltd. Whiten SB: heavy calcium carbonate, product name of Shiraishi Calcium Co., Ltd. TINUVIN 326 (referred to as Ti326 in the table): benzotriazole-based light stabilizer, product name of BASF. IRGANOX 1010 (referred to as Ir1010 in the table): hindered phenol-based antioxidant, product name of BASF. KBM-1003: vinyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. KBM-603: 3-(2-aminoethylamino)propyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. KBM-403: 3-glycidyloxypropyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd. U-860: Dioctyl tin catalyst, product name of Nitto Kasei Co., Ltd. S1: Dioctyl tin catalyst, product name of Nitto Kasei Co., Ltd.

[0103]

[0104] As shown in Table 3, the curable compositions of Examples 1 to 14 had high storage stability. Furthermore, the cured products obtained had high deep section curability and were less susceptible to bleed-out. The curable composition of Example 15, which contained polymer a-1 having a reactive silicon group formed without the organic group represented by formula i below, had low deep section curability. This is thought to be because polymer a-1 does not contain the organic group represented by formula i, thereby reducing moisture penetration into the interior of the cured product. The curable composition of Example 16, which contained polymer b-3, an oxyalkylene polymer having an average of 1.03 terminal groups per molecule, where the terminal group was an allyl group, had low deep section curability. This is thought to be because polymer b-3 does not contain hydroxyl groups, making it difficult for an appropriate amount of water to be drawn into the interior of the curable composition, preventing curing from progressing to the interior. The curable composition of Example 17, which did not contain a plasticizer, had low storage stability. It also had low deep section curability. The curable composition of Example 18, which did not contain polymer A, could not be molded and therefore could not be evaluated. The curable compositions of Examples 19 and 20, which contained the low-molecular-weight plasticizers DINP and DINCH, respectively, exhibited poor deep section curing properties, and significant bleed-out was observed in the resulting cured products. The curable composition of Example 21, which contained polymer b-2, an oxyalkylene polymer having an average of 2.00 terminal groups per molecule, in which the terminal groups were hydroxyl groups, exhibited poor storage stability. This was thought to be due to the fact that polymer b-2 had an average of 2.00 hydroxyl groups per molecule, resulting in excessive water being absorbed into the curable composition. The curable composition of Example 22, which contained polymer b-1 with an Mn of 20,000, exhibited poor deep section curing properties. This was thought to be due to the fact that polymer b-1 had a lower number of hydroxyl groups per unit mass than polymers B-1 to B-6, making it difficult for an appropriate amount of water to be absorbed into the interior of the curable composition, preventing curing from progressing to the interior.

Claims

1. A curable composition comprising a first polymer and a second polymer, wherein the first polymer 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 formed via one or more organic groups represented by the following formula i, the terminal group of the first polymer includes the reactive silicon group, an isocyanate group, an amino group, or a hydroxyl group, the second polymer is an oxyalkylene polymer having an average of 1.00 to 1.20 terminal groups per molecule, the terminal group of the second polymer has one hydroxyl group, and the number average molecular weight of the second polymer is 15,000 or less. -SiR ａ X ３－ａ Formula 1 In the formula 1, R represents a monovalent organic group having 1 to 20 carbon atoms other than a hydrolyzable group, and X represents a hydroxyl group or a hydrolyzable group. a is an integer of 0 to 2. When a is 2, R may be the same or different from each other, and when a is 0 or 1, X may be the same or different from each other. -C(=O)NH- Formula i 2. The curable composition according to claim 1, wherein the number average molecular weight of the first polymer is 3,000 to 80,000.

3. The curable composition according to claim 1, wherein the number average molecular weight of the second polymer is 1,500 to 10,000.

4. The curable composition according to claim 1, wherein the content of the second polymer is 80 parts by mass or less per 100 parts by mass of the total content of the first polymer and the second polymer.

5. The curable composition according to claim 1, wherein the number of organic groups represented by formula i contained in the first polymer is one per terminal group.

6. A cured product obtained by curing the curable composition according to any one of claims 1 to 5.

7. An adhesive comprising the cured product according to claim 6.

8. A sealant comprising the cured product according to claim 6.

Images