JP7367332B2 - Curable composition, cured product, and sealant - Google Patents

Description

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

The present invention relates to a cured polymer containing a 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 (hereinafter referred to as a "reactive silicon group"). The present invention relates to sexual compositions.

Polymers having at least one reactive silicon group in the molecule are crosslinked even at room temperature through the formation of siloxane bonds accompanied by a hydrolysis reaction of the reactive silicon group due to moisture, etc., resulting in a rubber-like cured product. It is known that it has the property of being obtained.

Among these polymers having reactive silicon groups, oxyalkylene polymers, saturated hydrocarbon polymers, polyacrylic acid alkyl ester polymers, and polymethacrylic acid alkyl ester polymers have already been used industrially. It is widely used in sealants, adhesives, paints, etc. When a curable composition containing a polymer having these reactive silicon groups is used as a sealant, in addition to curability, adhesion to adherends, and elongation properties of the cured product, it is difficult to expose it to an outdoor environment for a long time. It is required to have resilience that can follow the structural expansion and contraction of the joints that occur due to the joints, and to be resistant to cracking.

In order to improve the restorability of the cured product, it is conceivable to increase the number of reactive silicon groups in one molecule of the polymer to increase the crosslinking density.
Patent Document 1 discloses a branched oxyalkylene polymer having four main chain terminal groups in one molecule and having a methyldimethoxysilyl group as a reactive silicon group. Specifically, in the examples, propylene oxide was polymerized using pentaerythol as an initiator and a zinc hexacyanocobaltate catalyst to obtain a polyoxypropylene tetraol with an average molecular weight of 20,000, and the polyol It is described that after converting the terminal hydroxyl group of propylenetetraol to an allyl group, the allyl group was converted to a methyldimethoxysilyl group to obtain a polymer in which 60% of the terminals were silylated. It is described that the above polymer has low viscosity and excellent workability as a curable composition for an elastic adhesive, and has excellent adhesion to a substrate and water resistance.
Patent Document 2 describes a branched oxyalkylene polymer having four main chain terminal groups in one molecule, a polystyrene equivalent number average molecular weight of 32,000, and a trimethoxysilyl group as a reactive silicon group. The combination is disclosed. Specifically, in the examples, a tetraol obtained by polymerizing propylene oxide to pentaerythritol was used as an initiator, and a multimetal cyanide complex catalyst having t-butyl alcohol as a ligand was used. By polymerizing propylene oxide to obtain polyoxypropylene tetraate, and reacting the polyoxypropylene tetraate with 3-isocyanatepropyltrimethoxysilane, a polymer having a trimethoxysilyl group at the end of the molecule was obtained. Are listed. It is described that when a curable composition containing the above polymer is used, a cured product with excellent adhesiveness and high shear strength can be obtained.

Japanese Patent Application Publication No. 7-62205 Japanese Patent Application Publication No. 2009-46539

However, when a curable composition containing the polymer in Patent Document 1 or the polymer in Patent Document 2 is used as a sealant, the elongation properties of the cured product may be insufficient.
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 from which a cured product with excellent restorability and elongation can be obtained.

The present invention includes the following [1] to [8].
[1] One molecule has four or more main chain terminal groups, the number average molecular weight per main chain terminal group is 6,000 or more, and the main chain terminal group has a reaction represented by the following formula 1. A curable composition containing an oxyalkylene polymer A having a branched structure and having a silicon group.
-SiX ₂ R Formula 1
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. X may be the same or different.
[2] The curable composition according to [1], wherein the polymer A has a molecular weight distribution of 1.8 or less.
[3] The curable composition according to [1] or [2], wherein the polymer A has four main chain terminal groups in one molecule.
[4] Furthermore, it has two main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 2,000 or more, and the main chain terminal group is represented by the following formula 2. The curable composition according to any one of [1] to [3], which contains a linear oxyalkylene polymer B having a reactive silicon group.
-SiX _a R _3-a formula 2
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. a is an integer from 1 to 3. When a is 1, R may be the same or different, and when a is 2 or more, X may be the same or different.
[5] The curable composition according to [4], wherein the content ratio of the polymer A to the total of the polymer A and the polymer B is 50 to 99% by mass.
[6] Furthermore, one molecule has two main chain terminal groups, one main chain terminal group is an inert monovalent organic group, and the other main chain terminal group is represented by the following formula 3. The curable composition according to any one of [1] to [5], which contains an oxyalkylene polymer C having a linear structure and having a reactive silicon group and a number average molecular weight of 2,000 or more. Composition.
-SiX _a R _3-a formula 3
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. a is an integer from 1 to 3. When a is 1, R may be the same or different, and when a is 2 or more, X may be the same or different.
[7] A cured product obtained by curing the curable composition according to any one of [1] to [6].
[8] A sealing material comprising the cured product according to [7].

The curable composition of the present invention can provide a cured product with excellent restorability and elongation. The cured product of the present invention has excellent restorability and elongation.

The meanings and definitions of terms used in this specification are as follows.
The numerical range represented by "~" means a numerical range whose lower and upper limits are the numbers before and after ~.
A "unit" constituting a polymer means an atomic group directly formed by polymerization of monomers.
"Main chain" means a polymer chain formed by linking two or more monomers. The "main chain" in the oxyalkylene polymer described below means a portion containing a repeating unit based on a residue of an initiator and an alkylene oxide monomer.
The term "main chain terminal group" means an atom or atomic group bonded to a terminal atom constituting the main chain.
"Active hydrogen" means a hydrogen atom possessed by a reactive group to which an alkylene oxide can undergo ring-opening addition, and means a hydrogen atom bonded to an oxygen atom, nitrogen atom, sulfur atom, etc. Furthermore, water also has active hydrogen.
"Active hydrogen-containing group" means a group having the above-mentioned active hydrogen. Note that the active hydrogen-containing group is also a reactive group that can react with an isocyanate group.
"Unsaturated group" means a monovalent group containing an unsaturated double bond. Unless otherwise specified, it is at least one group selected from the group consisting of a vinyl group, an allyl group, and an isopropenyl group.

"Oxyalkylene polymer" means a polymer having a polymer chain formed from units based on alkylene oxide monomers.
"Precursor polymer" means a polymer before the introduction of reactive silicon groups, which is an oxyalkylene polymer in which the main chain terminal group is a hydroxyl group, which is obtained by polymerizing an alkylene oxide monomer with the active hydrogen of an initiator. do.
"Silylation rate" refers to the number of reactive silicon groups relative to the total number of terminal groups that are any of reactive silicon groups, active hydrogen-containing groups, and unsaturated groups, which are the main chain terminal groups of the oxyalkylene polymer. It is a proportion of numbers. The value of the silylation rate can be determined by NMR analysis. In addition, when introducing the reactive silicon group into the terminal group of the main chain of the oxyalkylene polymer using the silylating agent described below, the number of silyl groups of the added silylating agent relative to the number of terminal groups is also determined. It may be a ratio (mol%).
"Silylating agent" means a compound having a functional group that reacts with an active hydrogen-containing group or an unsaturated group and a reactive silicon group.

The "number of main chain terminal groups" is, for example, based on the principle of the iodine number measurement method specified in JIS K 0070 (1992) after introducing an unsaturated group into a precursor polymer of an oxyalkylene polymer. This is a value calculated by directly measuring the unsaturated group concentration by titration analysis. The "number of main chain terminal groups" in the oxyalkylene polymer described below is the same number as the number of active hydrogens of the initiator or the number of main chain terminal groups of the precursor polymer, which will be described later.

"Molecular weight in terms of hydroxyl group" means, in the case of a polymer containing a repeating unit based on an alkylene oxide monomer, the hydroxyl value of the initiator or precursor polymer is calculated based on JIS K 1557 (2007), and "56 ,100/(hydroxyl value)×(number of active hydrogens in the initiator or number of main chain terminal groups of the precursor polymer)". The hydroxyl-based molecular weight of the oxyalkylene polymer tends to be equal to or slightly smaller than the oxyalkylene polymer-based molecular weight described below.

In this specification, "number average molecular weight" (hereinafter referred to as "Mn") and "weight average molecular weight" (hereinafter referred to as "Mw") refer to tetrahydrofuran (hereinafter referred to as "THF") as an eluent. This is the molecular weight in terms of oxyalkylene polymer measured using gel permeation chromatography (hereinafter referred to as "GPC") and creating a calibration curve using an oxyalkylene polymer with a known molecular weight in terms of hydroxyl group. The molecular weight distribution is a value calculated from Mw and Mn, and is the ratio of Mw to Mn (Mw/Mn).

The molecular weight per main chain terminal group is calculated by applying the value of the hydroxyl value in the precursor polymer to the formula "56,100/(hydroxyl value of the precursor polymer)" or by GPC measurement. A calibration curve of the obtained Mn and the molecular weight per main chain end group obtained from the hydroxyl value is prepared in advance for each number of active hydrogens in the initiator, and the measurement result of the desired Mn is calculated based on this relationship. It may be calculated by a method of converting it into the molecular weight per main chain terminal group by applying to the formula.

In this specification, "number average molecular weight in terms of polystyrene" (hereinafter referred to as "PS-Mn") and "weight average molecular weight in terms of polystyrene" (hereinafter referred to as "PS-Mw") mean that THF is used as an eluent. This is the molecular weight in terms of polystyrene, which was measured using GPC by creating a calibration curve using a polystyrene polymer with a known molecular weight. In oxyalkylene polymers, PS-Mn and PS-Mw tend to be measured larger than the above-mentioned Mn and Mw. The value calculated by PS-Mw/PS-Mn is approximately the same as the above-mentioned Mw/Mn.

The curable composition of the present invention has four or more main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 6,000 or more, and the main chain terminal group has the following It includes a branched oxyalkylene polymer (hereinafter referred to as "polymer A") having a reactive silicon group represented by Formula 1.
Furthermore, it has two main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 2,000 or more, and the main chain terminal group has a reactivity expressed by formula 2 below. An oxyalkylene polymer with a linear structure having a silicon group (hereinafter referred to as "polymer B"), and a polymer having two main chain terminal groups in one molecule, one of which is inert. An oxyalkylene polymer ( (hereinafter referred to as "polymer C").

<Polymer A>
Polymer A has four or more main chain terminal groups in one molecule, has a number average molecular weight per main chain terminal group of 6,000 or more, and has a main chain terminal group represented by the formula 1 below. It is an oxyalkylene polymer with a branched structure and having reactive silicon groups. Two or more types of polymer A may be used in the curable composition of the present invention.

The reactive silicon group has a hydroxyl group or a hydrolyzable group bonded to a silicon atom, and can be crosslinked by forming a siloxane bond. The reaction that forms siloxane bonds is facilitated by a curing catalyst. The reactive silicon group in polymer A is represented by the following formula 1.
-SiX ₂ R Formula 1

In the above formula 1, R represents a monovalent organic group having 1 to 20 carbon atoms. R does not contain a hydrolyzable group.
R is preferably at least one selected from the group consisting of a hydrocarbon group having 1 to 20 carbon atoms and a triorganosiloxy group.

R 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. At least one member 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. It is more preferable that A methyl group or an ethyl group is preferred from the viewpoint of good curability of a polymer having a reactive silicon group and good stability of a curable composition. α-chloromethyl group is preferred because the cured product has a fast curing speed. Methyl group is particularly preferred because it is easily available.

In the formula 1, X represents a hydroxyl group or a hydrolyzable group. X may be the same or different.
Examples of the hydrolyzable group include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a sulfanyl group, and an alkenyloxy group.
Alkoxy groups are preferred because they are 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, siloxane bonds are quickly formed, a crosslinked structure is easily formed in the cured product, and the physical properties of the cured product are likely to be good.

Examples of the reactive silicon group represented by formula 1 include methyldimethoxysilyl group, methyldiethoxysilyl group, ethyldimethoxysilyl group, methyldiisopropoxysilyl group, (α-chloromethyl)dimethoxysilyl group, and (α-chloromethyl)dimethoxysilyl group. An example is chloromethyl)diethoxysilyl group. From the viewpoint of high activity and good curability, methyldimethoxysilyl group and methyldiethoxysilyl group are preferred, and methyldimethoxysilyl group is more preferred.

The main chain of the polymer A is a polymer chain consisting of an oxyalkylene polymer formed by polymerization of one or more types of alkylene oxide monomers. In the case of a copolymer chain formed by polymerization of two or more types of alkylene oxide monomers, those alkylene oxide monomers may form a block polymer or a random polymer. good.
As a polymer chain made of an oxyalkylene polymer, a polymer chain made of an ethylene oxide monomer, a polymer chain made of a propylene oxide monomer, a polymer chain made of a butylene oxide monomer, a polymer chain made of a tetramethylene oxide monomer, Examples include a copolymer chain of ethylene oxide monomer and propylene oxide monomer, and a copolymer chain of propylene oxide monomer and butylene oxide monomer. In particular, a polymer chain consisting of a propylene oxide monomer is preferred.

Polymer A has four or more main chain terminal groups. From the viewpoint of restorability of the cured product, those having 4 to 8 main chain terminal groups are preferred, those having 4 to 6 are more preferred, and those having 4 are even more preferred.
The main chain terminal group of the polymer A is either a reactive silicon group, an active hydrogen-containing group, or an unsaturated group represented by the above formula 1; One or more groups selected from the group consisting of allyl groups are preferred. The respective main chain terminal groups may be the same or different.
Examples of the active hydrogen-containing group include a hydroxyl group, a carboxy group, an amino group, a monovalent functional group obtained by removing a hydrogen atom from a primary amine, a hydrazide group, and a sulfanyl group. The active hydrogen-containing group is preferably a hydroxyl group, an amino group, or a monovalent functional group obtained by removing a hydrogen atom from a primary amine, and more preferably a hydroxyl group.

Polymer A preferably has on average more than 0.5 but not more than 1.0 reactive silicon groups represented by the above formula 1 per main chain terminal group, and the cured product has good tensile strength. Therefore, those having 0.52 to 0.95 are more preferable.
Polymer A preferably has more than 1.5 but not more than 7.6 reactive silicon groups per molecule on average, and the tensile strength of the cured product is likely to be good, so the number is 1.5 to 4. It is more preferable to have 0 pieces.

Mn per main chain terminal group of polymer A is 6,000 or more, preferably 6,500 to 15,000, more preferably 7,000 to 12,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
The Mn of polymer A is preferably 24,000 to 60,000, more preferably 26,000 to 50,000, even more preferably 28,000 to 48,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
The PS-Mn of Polymer A is preferably 29,000 to 80,000, more preferably 31,000 to 70,000, even more preferably 33,000 to 63,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
The molecular weight distribution of polymer A is preferably 1.8 or less. Since good elongation properties are easily obtained, the molecular weight distribution is preferably small, more preferably 1.0 to 1.5, even more preferably 1.02 to 1.4, particularly preferably 1.04 to 1.3.

Polymer A is obtained by introducing more than 0.5 but not more than 1.0 reactive silicon groups into the main chain terminal groups of the precursor polymer described below on average per main chain terminal group. Preferably, from the viewpoint of good tensile strength, those obtained by introducing 0.52 to 0.95 are more preferable.
The precursor polymer is an oxyalkylene polymer obtained by subjecting an alkylene oxide monomer to ring-opening addition polymerization to active hydrogen of an initiator having an active hydrogen-containing group in the presence of a ring-opening polymerization catalyst. As the precursor polymer, a precursor polymer whose main chain terminal group is a hydroxyl group, which is obtained by ring-opening addition polymerization of an alkylene oxide monomer to an initiator having a hydroxyl group, is preferable.

The method for producing polymer A includes a method in which one unsaturated group is introduced into one main chain end group of the precursor polymer, and then the unsaturated group is reacted with a silylating agent, or a method in which the precursor polymer Preferred is a method in which the active hydrogen-containing group of the terminal group of the main chain and the isocyanate silane compound are subjected to a urethanation reaction.
Since the main chain of the polymer A is branched, a curable composition containing the polymer A tends to yield a cured product with excellent restorability.

The precursor polymer is an oxyalkylene polymer obtained by ring-opening addition polymerization of an alkylene oxide monomer to active hydrogen of an initiator having an active hydrogen-containing group in the presence of a ring-opening polymerization catalyst. The number of active hydrogens of the initiator, the number of main chain end groups of the precursor polymer, and the number of main chain end groups of polymer A are the same.
The precursor polymer is preferably a polymer in which an alkylene oxide monomer is subjected to ring-opening addition polymerization to an initiator having a hydroxyl group, and the terminal group in the main chain end group is a hydroxyl group.
The initiator is preferably an initiator having 4 or more active hydrogen-containing groups, more preferably an initiator having 4 to 8 active hydrogen-containing groups, even more preferably an initiator having 4 to 6 active hydrogen-containing groups, and particularly preferably an initiator having 4 active hydrogen-containing groups. . The active hydrogen-containing group in the initiator is preferably a hydroxyl group.
Two or more types of initiators may be used in combination. When two or more types of initiators are used in combination, it is sufficient that the molar average number of active hydrogen-containing groups of those initiators is 4 or more.
Examples of the initiator having four or more active hydrogen-containing groups include pentaerythritol, sucrose, sorbitol, and dipentaerythritol, with pentaerythritol and sorbitol being preferred from the viewpoint of elongation of the cured product.

Conventionally known catalysts can be used as the ring-opening polymerization catalyst when the alkylene oxide monomer is subjected to ring-opening addition polymerization to the initiator. Examples include transition metal compound-porphyrin complex catalysts such as complexes obtained by reaction, multimetal cyanide complex catalysts, and catalysts consisting of phosphazene compounds.
A multi-metal cyanide complex catalyst is preferred because it can narrow the molecular weight distribution of the polymer A and it is easy to obtain a curable composition with low viscosity. A conventionally known compound can be used as the composite metal cyanide complex catalyst, and a known method can also be adopted as a method for producing a polymer using the composite metal cyanide complex. For example, WO 2003/062301, WO 2004/067633, JP 2004-269776, JP 2005-15786, WO 2013/065802, JP 2015-010162 The compounds and production methods disclosed in the above publication can be used.
As the precursor polymer for the polymer A, a precursor polymer in which all main chain terminal groups are hydroxyl groups is preferable.

The method for producing polymer A includes a method in which one unsaturated group is introduced into one main chain end group of the precursor polymer and then the unsaturated group is reacted with a silylating agent, or a method in which the unsaturated group is reacted with a silylating agent, or Preferred is a method in which an active hydrogen-containing group at the end of the main chain and an isocyanate silane compound undergo a urethanization reaction.
As the silylating agent, compounds having both a group capable of reacting with an unsaturated group to form a bond (for example, a sulfanyl group) and the above-mentioned reactive silicon group, a hydrosilane compound (for example, HSiX ₂ R, where X and R are ) can be exemplified. Specific examples include methyldimethoxysilane, methyldiethoxysilane, ethyldimethoxysilane, methyldiisopropoxysilane, (α-chloromethyl)dimethoxysilane, and (α-chloromethyl)diethoxysilane. From the viewpoint of high activity and good curability, methyldimethoxysilane and methyldiethoxysilane are preferred, and methyldimethoxysilane is more preferred.
As the isocyanate silane compound, for example, a conventionally known isocyanate silane compound described in JP-A No. 2011-178955 can be used.
A method in which one unsaturated group is introduced into one main chain terminal group of the precursor polymer and then the unsaturated group is reacted with a silylating agent, or an active hydrogen-containing method in which the main chain terminal group of the precursor polymer is reacted with a silylating agent. Conventionally known methods can be used for the urethanization reaction between the group and the isocyanate silane compound. Examples include methods proposed in Japanese Patent Application Publication No. 3-72527, Japanese Patent Application Publication No. 8-231707, Japanese Patent Application Publication No. 2011-178955, US Pat. No. 3,632,557, and US Pat. No. 4,960,844.

The silylation rate of polymer A is preferably more than 50 mol% and 100 mol% or less, more preferably 52 to 95 mol%.
When the curable composition contains two or more types of polymer A, the average silylation rate of the entire polymer A may be within the above range.

<Polymer B>
Polymer B has two main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 2,000 or more, and the main chain terminal group is represented by the following formula 2. It is a linear oxyalkylene polymer with reactive silicon groups. Two or more types of polymer B may be used in the curable composition of the present invention.
Examples of the main chain of polymer B are the same as those of the main chain of polymer A.
-SiX _a R _3-a formula 2

In the formula 2, R represents a monovalent organic group having 1 to 20 carbon atoms. R does not contain a hydrolyzable group. Preferred embodiments of R are the same as in Formula 1 above.

In the formula 2, X represents a hydroxyl group or a hydrolyzable group. Preferred embodiments of X are the same as in Formula 1 above.

In the above formula 2, a is an integer from 1 to 3. When a is 1, R may be the same or different from each other. When a is 2 or more, X may be the same or different. Since curability becomes good, a is preferably 2.

The reactive silicon group represented by the formula 2 includes a trimethoxysilyl group, a triethoxysilyl group, a triisopropoxysilyl group, a tris(2-propenyloxy)silyl group, a triacetoxysilyl group, a methyldimethoxysilyl group, Examples include methyldiethoxysilyl group, ethyldimethoxysilyl group, methyldiisopropoxysilyl group, (α-chloromethyl)dimethoxysilyl group, and (α-chloromethyl)diethoxysilyl group. From the viewpoint of high activity and good curability, trimethoxysilyl group, triethoxysilyl group, methyldimethoxysilyl group, and methyldiethoxysilyl group are preferred, and methyldimethoxysilyl group or trimethoxysilyl group is more preferred.

Since Polymer B has a reactive silicon group represented by the above formula 2, a cured product made from a curable composition containing Polymer B has good restorability and excellent conformability to adherends.
Moreover, since Polymer B has two main chain terminal groups and has a linear structure, a cured product prepared from a curable composition containing Polymer B has excellent elongation properties.
The main chain terminal group of the polymer B is either a reactive silicon group, an active hydrogen-containing group, or an unsaturated group represented by the above formula 2; One or more groups selected from the group consisting of allyl groups are preferred. The respective main chain terminal groups may be the same or different.

Polymer B preferably has more than 0.5 but not more than 1.0 reactive silicon groups represented by formula 2 on average per main chain terminal group, and the cured product has good tensile strength. Therefore, those having 0.52 to 0.95 are more preferable.
Polymer B preferably has more than 1.0 and less than 2.0 reactive silicon groups per molecule on average, and has a range of 1.04 to 1.0, since the cured product tends to have good tensile strength. It is more preferable to have 90 pieces.

Mn per main chain terminal group of polymer B is preferably 2,000 or more, more preferably 2,000 to 12,000, and even more preferably 2,200 to 10,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
The Mn of polymer B is preferably 4,000 to 24,000, more preferably 4,400 to 22,000, even more preferably 4,500 to 20,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
PS-Mn of Polymer B is preferably 5,000 to 30,000, more preferably 5,500 to 28,000, even more preferably 6,000 to 25,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
The molecular weight distribution of polymer B is preferably 1.8 or less. Since good elongation properties are easily obtained, the molecular weight distribution is preferably small, more preferably 1.0 to 1.5, even more preferably 1.02 to 1.4, particularly preferably 1.04 to 1.3.

Polymer B has a reactive silicon group represented by the formula 2 introduced into the main chain terminal group of the polymer, on average more than 0.5 but not more than 1.0 per main chain terminal group. The one obtained is preferred. The one obtained by introducing 0.52 to 0.95 is more preferable because it is easy to obtain good restorability and good tensile strength.
Polymer B having two main chain terminal groups in one molecule can be produced using an initiator having two active hydrogen-containing groups.
As the compound having two active hydrogen-containing groups, a compound having two hydroxyl groups is preferable. Two or more types of initiators may be used in combination.
Compounds with 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 An example is polyoxypropylene glycol.

The precursor polymer for Polymer B can be produced in the same manner as the precursor polymer for Polymer A, except that a compound having two active hydrogen-containing groups is used as an initiator, and alkylene is used as an initiator having a hydroxyl group. A precursor polymer obtained by ring-opening addition polymerization of an oxide monomer and whose main chain terminal group is a hydroxyl group is preferable.
Polymer B can be produced in the same manner as the method for producing Polymer A, except that the precursor polymer of Polymer B is used.

As the silylating agent, compounds having both a group capable of reacting with an unsaturated group to form a bond (for example, a sulfanyl group) and the above-mentioned reactive silicon group, and a hydrosilane compound (for example, HSiX _a R _3-a , where X , R and a are the same as in Formula 2 above.) can be exemplified. Specifically, for example, trimethoxysilane, triethoxysilane, triisopropoxysilane, tris(2-propenyloxy)silane, triacetoxysilane, methyldimethoxysilane, methyldiethoxysilane, ethyldimethoxysilane, methyldiisopropoxy Examples include silane, (α-chloromethyl)dimethoxysilane, and (α-chloromethyl)diethoxysilane. From the viewpoint of high activity and good curability, trimethoxysilane, triethoxysilane, methyldimethoxysilane, and methyldiethoxysilane are preferred, and methyldimethoxysilane or trimethoxysilane is more preferred.
As the isocyanate silane compound, for example, a conventionally known isocyanate silane compound described in JP-A No. 2011-178955 can be used.

The silylation rate of polymer B is preferably more than 50 mol% and 100 mol% or less, more preferably 52 to 95 mol%.
When the curable composition contains two or more types of polymer B, the average silylation rate of the entire polymer B may be within the above range.

<Polymer C>
Polymer C has two main chain terminal groups in one molecule, one main chain terminal group is an inert monovalent organic group, and the other main chain terminal group is represented by the above formula 2. It is an oxyalkylene polymer with a linear structure, which has reactive silicon groups and a number average molecular weight of 2,000 or more. Two or more types of polymer C may be used in the curable composition of the present invention. Polymer C acts as a reactive plasticizer and contributes to lowering the viscosity of the curable composition and improving paint staining properties.
Examples of the main chain of polymer C are the same as those of the main chain of polymer A.

The Mn of the polymer C is preferably 2,000 to 15,000, more preferably 2,200 to 12,000, even more preferably 2,500 to 10,000. Within the above range, the cured product tends to have excellent elongation properties, and the cured product tends to have good paint staining and bleed-out properties.
PS-Mn of Polymer C is preferably 2,400 to 20,000, more preferably 2,600 to 16,000, even more preferably 2,800 to 13,000. Within the above range, the cured product tends to have excellent elongation properties, and the cured product tends to have good paint staining and bleed-out properties.
The molecular weight distribution of the polymer C is preferably 1.8 or less. From the viewpoint of viscosity reduction, the molecular weight distribution is preferably small, more preferably 1.0 to 1.6, even more preferably 1.02 to 1.5, and particularly preferably 1.04 to 1.4.

Polymer C is a precursor polymer having a linear structure in which one main chain terminal group is an inert monovalent organic group, and an average of 0 reactive silicon groups per main chain terminal group. It can be obtained by introducing more than 0.5 or less.
The inert monovalent organic group is preferably R ¹⁰ —O— (R ¹⁰ is a monovalent hydrocarbon group). R ¹⁰ is preferably a branched or straight-chain alkyl group having 1 to 20 carbon atoms, more preferably a branched or straight-chain alkyl group having 1 to 10 carbon atoms, and a branched or straight-chain alkyl group having 1 to 4 carbon atoms. A group is more preferred, and a methyl group, ethyl group, isopropyl group, n-propyl group, n-butyl group or t-butyl group is particularly preferred.

The precursor polymer for Polymer C can be produced in the same manner as the precursor polymer for Polymer A or B, except that an initiator having one active hydrogen-containing group 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 whose main chain terminal group has one hydroxyl group.
The initiator having one hydroxyl group is preferably a monohydric alcohol having a linear or branched hydrocarbon group. Specifically, 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, Examples include tridecanol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and low molecular weight polyoxyalkylene monool.
As a method for producing polymer C, a conventionally known method can be used, and the same method as for polymer B can be used.

Polymer C has two main chain terminal groups in one molecule, one of which is either the reactive silicon group, active hydrogen-containing group, or unsaturated group, and the other main chain terminal group is the reactive silicon group, active hydrogen-containing group, or unsaturated group. It is preferable that the chain end group is a residue obtained by removing one active hydrogen from the initiator (an inert monovalent organic group).
The silylation rate of the polymer C is preferably more than 50 mol% and 100 mol% or less, more preferably 51 to 97 mol%, and even more preferably 52 to 95 mol%.
When the curable composition contains two or more types of polymers C, the average silylation rate of the entire polymer C may be within the above range.

<Polymer D>
The curable composition of the present invention is an oxyalkylene polymer ( (hereinafter referred to as "polymer D"). Two or more types of polymers D may be used in the curable composition of the present invention.
Examples of the main chain of polymer D are the same as those of the main chain of polymer A.

Mn per main chain terminal group of polymer D is preferably 4,000 to 15,000, more preferably 5,000 to 13,000. Within the above range, the cured product tends to have excellent elongation properties and has a sufficiently low viscosity.
Mn of Polymer D is preferably 12,000 to 45,000, more preferably 15,000 to 42,000, even more preferably 18,000 to 39,000. When it is within the above range, the cured product tends to have excellent elongation properties, and the hardness of the cured product can be easily adjusted.
PS-Mn of Polymer D is preferably 15,000 to 60,000, more preferably 20,000 to 55,000, even more preferably 23,000 to 51,000. Within the above range, the elongation properties of the cured product tend to be good and the hardness of the cured product can be easily adjusted.
The molecular weight distribution of the polymer D is preferably 1.8 or less. From the viewpoint of viscosity reduction, the molecular weight distribution is preferably small, more preferably 1.0 to 1.6, even more preferably 1.02 to 1.5, and particularly preferably 1.04 to 1.4.

Polymer D having three main chain terminal groups in one molecule can be produced using an initiator having three active hydrogen-containing groups.
The compound having three active hydrogen-containing groups is preferably a compound having three hydroxyl groups. Two or more types of initiators may be used in combination.
Examples of the compound having three hydroxyl groups include glycerin, trimethylolpropane, and butanetriol, and glycerin or trimethylolpropane is preferred from the viewpoint of improving the elongation properties of the cured product.

The precursor polymer for Polymer D can be produced in the same manner as the precursor polymer for Polymer A, except that a compound having three active hydrogen-containing groups is used as an initiator, and alkylene is used as an initiator having hydroxyl groups. A precursor polymer obtained by ring-opening addition polymerization of an oxide monomer and whose main chain terminal group is a hydroxyl group is preferable.
Polymer D can be produced in the same manner as the method for producing Polymer A, except that the precursor polymer of Polymer D is used.

As the silylating agent, the same compounds as those for the polymer B can be used, and the preferred embodiments are also the same.
The silylation rate of polymer D is preferably more than 50 mol% and 100 mol% or less, more preferably 52 to 95 mol%.
When the curable composition contains two or more types of polymers D, the average silylation rate of the entire polymer D may be within the above range.

<Polymer E>
The curable composition of the present invention may contain a vinyl polymer having one or more reactive silicon groups represented by the formula 2 in one molecule (hereinafter referred to as "polymer E"). Two or more types of polymers E in the curable composition of the present invention may be used.
It may contain one or more types.
The reactive silicon group in polymer E may be introduced into the main chain terminal group, the side chain, or both the main chain terminal group and the side chain.
The average number of reactive silicon groups per molecule of polymer E is preferably 1.0 or more. From the viewpoint of strength after curing, the number is preferably 1.2 or more, and more preferably 1.6 or more. From the viewpoint of good elongation of the cured product, the number is preferably 4.0 or less, and more preferably 3.0 or less.
The average number of reactive silicon groups per molecule of polymer E is calculated by "concentration of reactive silicon groups in polymer E [mol/g] x PS-Mn of polymer E". The concentration of reactive silicon groups [mol/g] in polymer E can be measured by NMR.
Examples of monomers constituting the main chain of polymer E include conventionally known monomers described in Japanese Patent Publication No. 3-14068, Japanese Patent Application Publication No. 6-211922, and Japanese Patent Application Publication No. 11-130931. You can use your body.
Monomers containing reactive silicon groups and unsaturated groups to be copolymerized with the above monomers include vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, Vinyltrichlorosilane, tris(2-methoxyethoxy)vinylsilane, (meth)acrylic acid-3-(methyldimethoxylyl)propyl, (meth)acrylic acid-3-(trimethoxysilyl)propyl, (meth)acrylic acid-3 -(triethoxysilyl)propyl is an example. Two or more types of these may be used.
With respect to all the monomers constituting the polymer E, the content of the (meth)acrylic acid ester monomer is preferably 50% by mass or more, more preferably 70% by mass or more, and may be 100% by mass.

Polymer E can be polymerized by conventionally known polymerization methods described in JP-A Nos. 2006-257405, 2006-37076, and 2008-45059. Conventionally known auxiliary materials such as initiators required for polymerization can be used, and reaction conditions such as reaction temperature and reaction pressure can also be selected as appropriate.
Examples of the polymerization method include solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization using a radical polymerization initiator, and living radical polymerization. Living radical polymerization methods include methods using cobalt porphyrin complexes as shown in Journal of American Chemical Society (J. Am. Chem. Soc.), 1994, Vol. 116, p. 7943; Those using nitroxide radicals as shown in Table 2003-500378, transition metal An example is atom transfer radical polymerization (ATRP method) using a complex as a catalyst. Polymers obtained by living radical polymerization tend to have a narrow molecular weight distribution and low viscosity.
Commercially available polymer E can also be used. Commercially available products include, for example, the XMAP series (Kaneka product name), the ARUFON US-6000 series (for example, US-6110, US-6120, US-6170, etc., all Toagosei product names), and the Actflow NE series ( For example, NE-1000, NE-3000 (both product names of Soken Chemical Co., Ltd.), etc. can be used.

PS-Mn of Polymer E is preferably 10,000 to 100,000, more preferably 12,000 to 80,000, even more preferably 13,000 to 60,000. When it is at least the lower limit of the above range, the cured product tends to have excellent elongation properties and weather resistance, and when it is at most the upper limit, it has better workability.
The molecular weight distribution of polymer E is preferably 4.0 or less, more preferably 3.0 or less. When it is below the above upper limit, workability is better.

<Polymer F>
The curable composition of the present invention may contain a polymer having no reactive silicon groups and having a PS-Mn of 1,000 or more (hereinafter referred to as "polymer F"). Two or more types of polymers E in the curable composition of the present invention may be used.
Polymer F contributes to reducing contamination on the surface of the cured product, improving drying properties of the paint on the surface of the cured product, and reducing contamination on the surface of the paint.
The polymer F is preferably one or more selected from the group consisting of saturated hydrocarbon polymers, (meth)acrylic acid ester polymers, and oxyalkylene polymers.

The saturated hydrocarbon polymer is a polymer whose main chain includes units based on saturated hydrocarbon monomers, and examples thereof include polyethylene and polypropylene.
(Meth)acrylic acid ester polymers include methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. Examples include polymers or copolymers of monomers. Examples of commercially available (meth)acrylic acid ester polymers include ARUFON UP-1000, ARUFON UP-1110, and ARUFON UP-1171 (all product names of Toagosei Co., Ltd.).
Examples of the oxyalkylene polymer include polyether polyols (eg, polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol), and derivatives obtained by capping the hydroxyl groups of the polyether polyols to form esters or ethers. Examples of commercially available oxyalkylene polymers include Preminol S3011, Preminol S4012, and Preminol S4013F (all product names of AGC Corporation).

PS-Mn of Polymer F is preferably 1,000 to 40,000, more preferably 1,500 to 35,000, even more preferably 2,000 to 30,000. When it is above the lower limit of the above range, it is easy to be excellent in preventing runoff due to heat or rain, and when it is below the upper limit, the viscosity is low and the workability is excellent.
In the case of a (meth)acrylic acid ester polymer, the molecular weight distribution of the polymer F is preferably less than 6.0, more preferably 5.5 or less, and even more preferably 5.0 or less. In the case of oxyalkylene polymers, it is preferably less than 2.0, more preferably 1.8 or less, and even more preferably 1.6 or less.

<Curable composition>
The curable composition is obtained by mixing Polymer A and other necessary components.
The content of polymer A in the curable composition is preferably 1 to 50% by mass, more preferably 2 to 45% by mass, and even more preferably 4 to 40% by mass. Within the above range, the cured product of the curable composition has excellent followability and elongation to adherends.
When the curable composition contains polymer B, the content of polymer B in the curable composition is preferably 1 to 25% by mass, more preferably 1 to 22% by mass, and 2 to 20% by mass. More preferred. Within the above range, the cured product of the curable composition has excellent followability and elongation to adherends.
When the curable composition contains polymer B, the total content of polymer A and polymer B in the curable composition is preferably 2 to 60% by mass, more preferably 3 to 50% by mass, and 4% by mass. More preferably 45% by mass. Within the above range, the cured product of the curable composition has excellent followability and elongation to adherends.
When the curable composition contains polymer B, the content ratio of polymer A to the total of polymer A and polymer B is preferably 50 to 99% by mass, more preferably 50 to 95% by mass, More preferably 60 to 95% by mass. Within the above range, the cured product of the curable composition has excellent followability and elongation to adherends.
When the curable composition contains polymer C, the content ratio of polymer C is preferably 1 to 600 parts by mass, more preferably 5 to 500 parts by mass, and 10 to 100 parts by mass. More preferably 300 parts by mass. When it is within the above range, the viscosity tends to be low, the workability tends to be excellent, and bleed-out is unlikely to occur in the cured product.
When the curable composition contains the polymer D, the content of the polymer D is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, and more preferably 1 to 100 parts by mass, based on a total of 100 parts by mass of the polymer A. 60 parts by mass is more preferred. When it is at least the lower limit of the above range, the elongation properties of the cured product tend to be good, and the hardness of the cured product is easily adjusted.
When the curable composition contains polymer E, the content of polymer E is preferably 1 to 600 parts by mass, more preferably 5 to 500 parts by mass, and 10 to 500 parts by mass, based on a total of 100 parts by mass of polymer A. More preferably 300 parts by mass. If it is above the lower limit of the above range, the staining property of the surface of the cured product obtained tends to decrease, and if it is below the upper limit, the viscosity tends to be low and the workability is better.
When the curable composition contains polymer F, the content of polymer F is preferably 1 to 600 parts by mass, more preferably 5 to 500 parts by mass, and 10 to 500 parts by mass, based on a total of 100 parts by mass of polymer A. More preferably 300 parts by mass. When it is above the lower limit of the above range, surface contamination tends to decrease, and when it is below the upper limit, the viscosity tends to be low and the workability is better.

As shown in the Examples below, the cured product obtained from the curable composition of the present invention has an elastic recovery rate of 70% or more according to the test method for architectural sealants of JIS A 1439 5.2 (2016). It is easy, and even more likely to be 72% or more. If it is 70% or more, good restorability is obtained, it is easy to follow the structural change of the adherend over time, and it is easy to obtain the followability of the cured product.
In addition, as shown in the examples below, the cured product obtained from the curable composition of the present invention was subjected to tensile testing using a durability test specimen type 1 in accordance with JIS A 1439 (2016) testing method for architectural sealants. The maximum elongation value in the property test is likely to be 300% or more, and even more likely to be 330% or more. If it is 300% or more, good elongation can be obtained and it is suitable as a sealing material for construction.
As shown in the Examples below, the viscosity at 25°C of a mixture of Polymer A, Polymer B, and Polymer C is preferably 1 to 50 Pa·s, more preferably 3 to 40 Pa·s, and 5 to 30 Pa·s. -s is more preferred. When the viscosity of the mixture of polymer A, polymer B, and polymer C is at least the lower limit of the above range, dripping during work is less likely to occur, and when it is at most the upper limit, workability tends to be good.

The curable composition may be a one-component type in which the polymer and all other components are blended in advance, sealed and stored, and cured by moisture in the air after application. A two-part type may be used, in which the composition and the 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. A one-component curable composition is preferred because it is easy to apply.

It is preferable that the one-component curable composition does not contain water. It is preferable to dehydrate the components containing water in advance or by applying reduced pressure during compounding and kneading.
In a two-component curable composition, the curing agent composition may contain water, and the base composition is difficult to gel even if it contains a small amount of water, but from the viewpoint of storage stability, the ingredients should be dehydrated and dried in advance. It is preferable.
In order to improve storage stability, a dehydrating agent may be added to the one-component curable composition or the two-component base composition.

[Other ingredients]
Other components mentioned above include polymers other than polymers A to F, curable compounds, curing catalysts (silanol condensation catalysts), fillers, plasticizers, thixotropic agents, stabilizers, adhesion agents, and physical property adjustment agents. Examples include reinforcing agents such as additives, tackifying resins, fillers, surface modifiers, flame retardants, foaming agents, solvents, and silicates.
Other components are International Publication No. 2013/180203, International Publication No. 2014/192842, International Publication No. 2016/002907, JP 2014-88481, JP 2015-10162, JP 2015-105293. Conventionally known materials described in JP-A No. 2017-039728, JP-A No. 2017-214541, etc. can be used in combination without any restriction. Two or more types of each component may be used in combination.

[Mechanism of action]
The curable composition of the present invention has four or more main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 6,000 or more, and the main chain terminal group has the following formula: It contains an oxyalkylene polymer A having a branched structure and having a reactive silicon group represented by 1. Furthermore, it has two main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 2,000 or more, and the main chain terminal group contains reactive silicon represented by the above formula 2. oxyalkylene polymer B having a linear structure, and one molecule having two main chain terminal groups, one main chain terminal group being an inert monovalent organic group, and the other main chain terminal group being an inert monovalent organic group. It may contain one or both of the linear oxyalkylene polymers C having a reactive silicon group represented by the formula 2 at the chain terminal group and having a number average molecular weight of 2,000 or more. The curable composition is particularly suitable as a sealing material for exterior walls that are exposed outdoors for a long period of time, since the resulting cured product has good restorability and elongation, as shown in the Examples below. When the curable composition of the present invention is used as a sealant for exterior walls, it has excellent recovery properties, follows structural changes in the adhered material over time, and is less prone to cracking, resulting in a good appearance. Cheap.

[Application]
The curable composition is used as a sealant (e.g., elastic sealant for construction, sealant for double-glazed glass, anti-rust/waterproof sealant for glass edges, back sealant for solar cells, sealant for buildings). Suitable examples include electrical insulation materials (insulating coating materials for electric wires and cables), and adhesives.
It is particularly suitable for applications that require resilience, such as sealing materials applied outdoors.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited by the following description.

[Molecular weight of precursor polymer]
The molecular weight of an oxyalkylene polymer (hereinafter referred to as "precursor polymer") whose main chain end has a hydroxyl group, which is obtained by polymerizing alkylene oxide with an initiator having a hydroxyl group, was calculated based on JIS K 1557 (2007). It was calculated from the hydroxyl value based on the formula "56,100/(hydroxyl value of precursor polymer) x number of active hydrogens of initiator" (hereinafter referred to as "hydroxyl group equivalent molecular weight").

[Mn, PS-Mn, and molecular weight distribution]
The test was carried out by the method described above using HLC-8220GPC (product name of Tosoh Corporation).

[Silylation rate, number of silyl groups]
An unsaturated group introduced to the main chain terminal group in a method of introducing an unsaturated group to the main chain terminal group using allyl chloride and reacting a silylating agent with the unsaturated group to introduce a reactive silicon group. The charged equivalent (molar ratio) of the reactive silicon group of the silylation agent to that of the silylation agent was defined as the silylation rate.
In the reaction between the unsaturated group introduced using allyl chloride and the silylating agent, approximately 10 mol% of the unsaturated group does not react with the silylating agent due to side reactions. Therefore, when less than 90 mol% of the unsaturated groups are reacted with the silylating agent, the charged equivalent amount becomes the silylation rate.

[Evaluation of tensile properties]
As the adherend, a surface anodized aluminum plate coated with primer MP-2000 (product name of Cemedine Co., Ltd.) was used, and the durability was determined in accordance with the test method for architectural sealants of JIS A 1439 (2016). A type 1 test specimen was prepared and subjected to a tensile property test.
Specifically, the curable composition was poured into a space formed by sandwiching a spacer between two of the above aluminum plates, cured for 7 days at a temperature of 23°C and a humidity of 50%, and then After curing for 7 days at 50° C. and 65% humidity, a durability test specimen type 1 was obtained. The obtained durability test specimen type 1 was subjected to a tensile property test using a Tensilon tester, and the stress at 50% elongation (hereinafter referred to as "M50", unit: N/mm ² ), maximum point cohesive force ( Unit: N/mm ² ) and maximum point elongation (unit: %) were measured.
The smaller the value of M50, the softer the cured product, the larger the value of maximum point cohesive force, the higher the tensile strength of the cured product, and the larger the value of maximum point elongation, the better the elongation of the cured product. A maximum point elongation of 300% or more indicates good elongation.

[Evaluation of elastic recovery]
A surface-anodized aluminum plate coated with primer MP-2000 (product name of Cemedine Co., Ltd.) is used as the adherend, and is compliant with the test method for architectural sealants of JIS A 1439 5.2 (2016). An aluminum adherend was prepared and an elastic recovery test was conducted.
Specifically, in the same way as in the evaluation of the tensile properties, a curable composition was poured between the two aluminum plates, cured for 7 days at a temperature of 23°C and a humidity of 50%, and then cured at a temperature of 50°C and a humidity of 65%. After curing for 7 days, an aluminum adherend was obtained. The distance between the two aluminum plates of the obtained aluminum adherend was defined as L0. Using a predetermined jig, the distance between the two aluminum plates was extended by 100% with respect to L0 in an environment of a temperature of 23° C. and a humidity of 50%.
The distance between the two aluminum plates at this time was defined as L1. After holding the distance between the two aluminum plates as L1 for 24 hours, the jig was removed, and the distance between the two aluminum plates was measured as L2. From the above values of L0, L1, and L2, the elastic recovery rate (unit: %) was determined using the following formula 4. The higher the value of the elastic recovery rate, the better the recovery property.
If the elastic recovery rate is 70% or more, the recovery property will be good.
Elastic recovery rate = ((L1-L2)/(L1-L0)) x 100 Equation 4

[Measurement of viscosity]
The viscosity of the mixture of Polymer A, Polymer B, and Polymer C was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: RE80 type) at a measurement temperature of 25° C. and a rotor No. The measurement was carried out under the following conditions.

[Synthesis of polymer A, polymer B and polymer C]
(Synthesis Example 1: Polymer A1)
Propylene oxide is polymerized using pentaerythritol as an initiator and a zinc hexacyanocobaltate complex (hereinafter referred to as "TBA-DMC catalyst") in which the ligand is t-butyl alcohol as a catalyst to form an oxypropylene polymer ( (precursor polymer) was obtained. The molecular weight of the precursor polymer in terms of hydroxyl group was 32,000. Next, a methanol solution of sodium methoxide in an amount of 1.05 molar equivalent based on the hydroxyl group of the precursor polymer was added to alcoholate the precursor polymer. Next, 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 main chain terminal groups to allyl groups. Next, in the presence of chloroplatinic acid hexahydrate, 0.67 molar equivalent of methyldimethoxysilane was added to the converted allyl group of the precursor polymer, reacted at 70°C for 5 hours, and dimethoxymethyl An oxypropylene polymer (polymer A1) in which a silyl group was introduced into the terminal group of the main chain was obtained.
Table 1 shows Mn, Mn per main chain terminal group, Mw/Mn, PS-Mn, and average number of reactive silicon groups per main chain terminal group of the obtained polymer A1. The polymers obtained in Synthesis Examples 2 to 11 below are also shown in Table 1.

(Synthesis Example 2: Polymer A2)
The hydroxyl group of the precursor polymer obtained in Synthesis Example 1 was converted into an allyl group in the same manner as in Synthesis Example 1. Next, in the presence of chloroplatinic acid hexahydrate, 0.73 molar equivalent of methyldimethoxysilane was added to the converted allyl group of the precursor polymer, reacted at 70°C for 5 hours, and dimethoxymethyl An oxypropylene polymer (polymer A2) in which a silyl group was introduced into the terminal group of the main chain was obtained.

(Synthesis Example 3: Polymer A3)
Using pentaerythritol as an initiator, propylene oxide was polymerized in the same manner as in Synthesis Example 1 in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight in terms of hydroxyl group of 30,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.62 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. An introduced oxypropylene polymer (polymer A3) was obtained.

(Synthesis Example 4: Polymer A4)
Using pentaerythritol as an initiator, propylene oxide was polymerized in the same manner as in Synthesis Example 1 in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight in terms of hydroxyl group of 40,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.70 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. The introduced oxypropylene polymer (polymer A4) was obtained.

(Synthesis example 5: polymer a1)
Using pentaerythritol as an initiator, propylene oxide was polymerized in the same manner as in Synthesis Example 1 in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight calculated as a hydroxyl group of 22,000. Next, the hydroxyl group of the precursor polymer was converted to an allyl group in the same manner as in Synthesis Example 1, and 0.60 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. The introduced oxypropylene polymer (polymer a1) was obtained.

(Synthesis Example 6: Polymer a2)
The hydroxyl group of the precursor polymer obtained in Synthesis Example 1 was converted into an allyl group in the same manner as in Synthesis Example 1. Next, in the presence of chloroplatinic acid hexahydrate, 0.63 molar equivalent of triethoxysilane was added to the converted allyl group of the precursor polymer, and the mixture was reacted at 70°C for 5 hours. An oxypropylene polymer (polymer a2) in which an ethoxysilyl group was introduced into the terminal group of the main chain was obtained.

(Synthesis Example 7: Polymer B1)
Using propylene glycol as an initiator, propylene oxide was polymerized in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight in terms of hydroxyl group of 8,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.70 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. An introduced oxypropylene polymer (polymer B1) was obtained.

(Synthesis Example 8: Polymer B2)
Using propylene glycol as an initiator, propylene oxide was polymerized in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight in terms of hydroxyl group of 18,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.70 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. An introduced oxypropylene polymer (polymer B2) was obtained.

(Synthesis Example 9: Polymer C1)
Propylene oxide was polymerized using n-butyl alcohol as an initiator in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a molecular weight in terms of hydroxyl group of 5,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.80 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. An introduced oxypropylene polymer (polymer C1) was obtained.
(Synthesis Example 10: Polymer D1)
Using glycerin as an initiator, propylene oxide was polymerized in the presence of a TBA-DMC catalyst to obtain a precursor polymer having a hydroxyl-based molecular weight of 24,000. Next, in the same manner as in Synthesis Example 1, the hydroxyl group of the precursor polymer was converted to an allyl group, and 0.65 molar equivalent of methyldimethoxysilane was added to the allyl group, so that the dimethoxymethylsilyl group became the main chain terminal group. An introduced oxypropylene polymer (polymer D1) was obtained.

(Synthesis Example 11: Polymer D2)
The hydroxyl group of the precursor polymer obtained in Synthesis Example 10 was converted into an allyl group in the same manner as in Synthesis Example 10. Next, in the presence of chloroplatinic acid hexahydrate, 0.70 molar equivalent of methyldimethoxysilane was added to the converted allyl group of the precursor polymer, reacted at 70°C for 5 hours, and dimethoxymethyl An oxypropylene polymer (polymer D2) in which a silyl group was introduced into the terminal group of the main chain was obtained.

[Other ingredients]
The additives listed in Table 2 are as follows.
Whiten SB: Heavy calcium carbonate, product name of Shiraishi Kogyo Co., Ltd.
CCR: colloidal calcium carbonate, white gloss CCR, product name of Shiraishi Kogyo Co., Ltd.
R-820: Titanium oxide, Ishihara Sangyo Co., Ltd. product name.
UP-1110: ARUFON UP-1110, acrylic polymer with Mn of 1,500, product name of Toagosei Co., Ltd.
US-6170: ARUFON US-6170, acrylic polymer having 0.5 reactive silicon groups per molecule and Mn of 1,300, product name of Toagosei Co., Ltd.
EL3020: Excenol 3020, an oxyalkylene polymer having two hydroxyl groups per molecule and a hydroxyl-equivalent molecular weight of 3000, product name of AGC Company.
DINP: Vinicizer 90, diisononyl phthalate, Kao product.
N-12D: Cactus normal paraffin N-12D, n-dodecane, purity 98.0%, product of JXTG Energy.
Sansocizer EPS: 4,5-epoxycyclohexane-1,2-dicarboxylic acid-di-2-ethylhexyl, product name of Shin Nippon Chemical Co., Ltd.
Glycerin monostearate: Reagent, manufactured by Tokyo Kasei Kogyo Co., Ltd.
KBM-202: Diphenyldimethoxysilane, Shin-Etsu Chemical product name.
IRGANOX1135: Hindered phenol antioxidant, BASF product name.
TINUVIN327: Benzotriazole ultraviolet absorber, BASF product name.
TINUVIN770: Hindered amine light stabilizer, BASF product name.
LA-63P: ADEKA STAB LA-63P, ADEKA product name.
KBM-1003: Vinyltrimethoxysilane, Shin-Etsu Chemical product name.
KBM-403: 3-glycidyloxypropyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd.
KBM-603: 3-(2-aminoethylamino)propyltrimethoxysilane, Shin-Etsu Chemical product name.
Laurylamine: Reagent, manufactured by Junsei Kagaku Co., Ltd.
Firmin CS: Coconut amine, Kao company product name.
U-220H: Dibutyltin bis(acetylacetonate), tin catalyst, Nitto Kasei Co., Ltd. product name.

[Preparation of curable composition]
Examples 1 to 7 and Examples 14 to 73 are examples, and Examples 8 to 13 are comparative examples.

(Example 1 to Example 13)
A curable composition was prepared by adding a polymer having a reactive silicon group in the formulation shown in Table 3 and an additive in the amount shown in Table 2. The blending amount of each component shown in Table 2 is the value (unit: parts by mass) for a total of 100 parts by mass of polymer A or comparative polymer a, polymer B, polymer C, and polymer D. .
Using the obtained curable composition, a tensile property test and an elastic recovery test were conducted. The results are shown in Table 3.

(Example 14 to Example 73)
In Examples 1 to 6 in Table 3, curable compositions were prepared by changing the additives to Additives 3 to 12 in Table 2, and evaluated in the same manner as above. Examples 14 to 19 are examples in which additive 3 is added, Examples 20 to 25 are examples in which additive 4 is added, Examples 26 to 31 are examples in which additive 5 is added, and Examples 32 to 37 are examples in which additive 5 is added. Examples 38 to 43 are examples in which Additive 6 is added, Examples 44 to 49 are examples in which Additive 8 is added, and Examples 50 to 55 are examples in which Additive 9 is added. Examples 56 to 61 are examples in which additive 10 is added, Examples 62 to 67 are examples in which additive 11 is added, and Examples 68 to 73 are examples in which additive 12 is added. All of the obtained cured products had good elongation and restorability in the above-mentioned tensile test and elastic restorability test.

As shown in Table 3, Examples 1 to 7 had good elongation properties, high elastic recovery rates, and sufficient recovery properties. In Example 8, which contained a polymer a1 having four main chain terminal groups in one molecule and a number average molecular weight per main chain terminal group of less than 6,000, the elongation properties were poor. In addition, in Examples 9 to 11 and 13 containing polymer D1, polymer D2, polymer B1, and polymer B2, which have only three or less main chain terminal groups in one molecule, the elastic recovery rate was low and sufficient. No good resiliency was obtained. Example 12 containing a polymer a2 having 4 main chain terminal groups in one molecule, a number average molecular weight per main chain terminal group of 8,000, and having a triethoxysilyl group as a reactive silicon group However, the elongation properties were poor.

Claims (8)

Having 4 or more main chain terminal groups in one molecule, a number average molecular weight per main chain terminal group of 6,000 or more, and a reactive silicon group represented by the following formula 1 in the main chain terminal group. A curable composition containing an oxyalkylene polymer A having a branched structure.
-SiX ₂ R Formula 1
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. X may be the same or different. The curable composition according to claim 1, wherein the polymer A has a molecular weight distribution of 1.8 or less. The curable composition according to claim 1 or 2, wherein the polymer A has four main chain terminal groups in one molecule. Furthermore, it has two main chain terminal groups in one molecule, the number average molecular weight per main chain terminal group is 2,000 or more, and the main chain terminal group contains reactive silicon represented by the following formula 2. The curable composition according to any one of claims 1 to 3, comprising an oxyalkylene polymer B having a linear structure having a group.
-SiX _a R _3-a formula 2
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. a is an integer from 1 to 3. When a is 1, R may be the same or different, and when a is 2 or more, X may be the same or different. The curable composition according to claim 4, wherein the content ratio of the polymer A to the total of the polymer A and the polymer B is 50 to 99% by mass. Furthermore, one molecule has two main chain terminal groups, one main chain terminal group is an inert monovalent organic group, and the other main chain terminal group has a reactivity represented by the following formula 3. The curable composition according to any one of claims 1 to 5, which contains an oxyalkylene polymer C having a linear structure and having a silicon group and a number average molecular weight of 2,000 or more.
-SiX _a R _3-a formula 3
In the formula, R is a monovalent organic group having 1 to 20 carbon atoms, which is a hydrolyzable group selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group, an α-chloroalkyl group, and a triorganosiloxy group. X represents a hydroxyl group or a hydrolyzable group. a is an integer from 1 to 3. When a is 1, R may be the same or different, and when a is 2 or more, X may be the same or different. A cured product obtained by curing the curable composition according to any one of claims 1 to 6. A sealing material comprising the cured product according to claim 7.