JP7798282B2 - Method for producing curable composition - Google Patents

Description

The present invention relates to a method for producing a curable composition containing a polymer having reactive silyl groups capable of forming a crosslinked structure.

Polyoxyalkylene polymers having reactive silyl groups are widely used in curable compositions for applications such as sealants, adhesives, and paints because they produce cured products with excellent flexibility, tensile properties, and paintability. It is known that the weather resistance of cured products containing polyoxyalkylene polymers having reactive silyl groups can be improved by adding a (meth)acrylic acid alkyl ester polymer having reactive silyl groups.

(Meth)acrylic acid alkyl ester polymers having reactive silyl groups have traditionally been produced using methods that use radical polymerization initiators or chain transfer agents that have reactive silyl groups. In these production methods, reactive silyl groups tend to be randomly introduced into the side chains of the main chain skeleton of the carbon-carbon bond chain of the (meth)acrylic acid alkyl ester polymer, and the resulting polymers have inferior tensile properties compared to polyoxyalkylene polymers having reactive silyl groups.

In recent years, in order to improve these physical properties, studies have been conducted to control the introduction of reactive silyl groups into (meth)acrylic acid alkyl ester polymers using living radical polymerization methods.

For example, Patent Document 1 describes a reversible chain transfer catalyzed polymerization (RTCP) living radical polymerization method that uses a compound containing nitrogen as a central element, such as N-succinimide, as a catalyst and a halogen atom bonded to the central element. It describes that this RTCP living radical polymerization method produces a polymer with terminal halogens, and that by modifying the terminal halogens, a vinyl polymer ((meth)acrylic acid alkyl ester polymer) with hydrolyzable silyl groups (reactive silyl groups) at the molecular ends can be obtained.

Patent Document 2 also describes living radical polymerization using an atom transfer radical polymerization (ATRP) method, which uses an organic halide or sulfonyl halide compound as an initiator and a transition metal complex such as a copper bromide-pentamethyldiethylenetriamine complex as a catalyst. It also describes that this ATRP living radical polymerization produces a polymer with terminal halogens, and that a conversion reaction of the terminal halogens produces a vinyl polymer ((meth)acrylic acid alkyl ester polymer) with crosslinkable silyl groups (reactive silyl groups) at the molecular ends.

JP 2011-74325 A International Publication No. 2005/095492

The curable composition is also required to have excellent workability when used in the above applications. From the viewpoint of such workability, a uniform mixed state is desirable. Furthermore, the cured product obtained from the curable composition is desirably homogeneous in order to exhibit excellent tensile properties.
Therefore, it is required that the polyoxyalkylene polymer having a reactive silyl group and the (meth)acrylic acid alkyl ester polymer having a reactive silyl group in the curable composition have good compatibility.

The RTCP-based living radical polymerization described in Patent Document 1 does not necessarily provide sufficient control over the position at which the reactive silyl group is introduced relative to the main chain of the (meth)acrylic acid alkyl ester polymer. The (meth)acrylic acid alkyl ester polymer having a reactive silyl group obtained by RTCP-based living radical polymerization has poor compatibility with polyoxyalkylene polymers having a reactive silyl group.

On the other hand, ATRP-based living radical polymerization, as described in Patent Document 2, offers superior control over the RTCP method in terms of the position of introduction, by introducing a reactive silyl group into the terminal of the main chain skeleton of the carbon-carbon bond chain of a (meth)acrylic acid alkyl ester polymer. However, even the (meth)acrylic acid alkyl ester polymer having a reactive silyl group obtained by ATRP-based living radical polymerization had poor compatibility with polyoxyalkylene polymers having a reactive silyl group, for reasons that are unclear.

The present invention was made to solve the above-mentioned problems, and aims to provide a method for producing a curable composition that has good compatibility between a polyoxyalkylene polymer having a reactive silyl group and a (meth)acrylic acid alkyl ester polymer having a reactive silyl group, and that contains these polymers and produces a cured product with excellent tensile properties.

The present invention is based on the discovery that (meth)acrylic acid alkyl ester polymers having specific reactive silyl groups, obtained by living radical polymerization using reversible coordination-mediated polymerization (RCMP), have good compatibility with polyoxyalkylene polymers having reactive silyl groups.

The present invention provides the following means.
[1] A method for producing a curable composition by blending a polymer (A) and a polymer (B), wherein the polymer (A) is a polyoxyalkylene polymer having an average of 1.0 or more reactive silyl groups per molecule and a number average molecular weight of 4,000 to 35,000, and the polymer (B) has an average of 0.5 or more reactive silyl groups per molecule, the method comprising: subjecting a monomer composition containing a monomer (b1) and a monomer (b2) to living radical polymerization in the presence of a quaternary ammonium halide salt; and wherein the monomer (b1) is a (meth)acrylic acid alkyl ester having an alkyl group of 4 to 8 carbon atoms, and the monomer (b2) is a (meth)acrylic acid alkyl ester having an alkyl group of 9 to 20 carbon atoms, and the content of the monomer (b1) in the monomer composition is 10 to 90 parts by mass per 100 parts by mass of the total of the monomer (b1) and the monomer (b2).

[2] The method for producing a curable composition according to [1], wherein the polymer (B) contains at least two or more types of the monomer (b2).
[3] The method for producing a curable composition according to [1] or [2], wherein the silylating agent is added in an amount of 0.5 to 10.0 parts by mass per 100 parts by mass of the total of the monomer (b1) and the monomer (b2).
[4] The method for producing a curable composition according to any one of [1] to [3], wherein the living radical polymerization is reversible coordination-mediated polymerization.
[5] The method for producing a curable composition according to any one of [1] to [4], wherein the quaternary ammonium halide salt is a quaternary ammonium iodide salt.
[6] The method for producing a curable composition according to [5], wherein the quaternary ammonium iodide salt is a compound represented by the following formula (1):
R ₄ N ⁺ I ^- (1)
(In formula (1), each R is independently an alkyl group having 1 to 8 carbon atoms.)
[7] The method for producing a curable composition according to [5] or [6], wherein the quaternary ammonium iodide salt is at least one selected from the group consisting of tetramethylammonium iodide, tetrabutylammonium iodide, and tetraoctylammonium iodide.
[8] The method for producing a curable composition according to any one of [1] to [7], wherein an organic iodine compound is used as an initiator in the living radical polymerization.
[9] The method for producing a curable composition according to [8], wherein the organic iodine compound is at least one selected from the group consisting of 1,4-diiodooctafluorobutane, ethylene glycol bis(2-iodoisobutyrate), diethyl 2,5-diiodoadipate, 1,4-bis(1'-iodoethyl)benzene, and ethylene glycol bis(2-iodo-2-phenylacetate).

[10] The method for producing a curable composition according to any one of [1] to [9], wherein the polymer (B) has an average of 1.0 to 6.0 reactive silyl groups per molecule.
[11] The method for producing a curable composition according to any one of [1] to [10], wherein the polymer (B) has a number average molecular weight of 6,000 to 300,000.

[12] The method for producing a curable composition according to any one of [1] to [11], wherein the mass blending ratio of the polymer (A) to the polymer (B) is 10/90 to 90/10.
[13] The method for producing a curable composition according to any one of [1] to [12], wherein the curable composition is a sealant composition.

According to the method for producing a curable composition of the present invention, the polyoxyalkylene polymer having a reactive silyl group and the (meth)acrylic acid alkyl ester polymer having a reactive silyl group have good compatibility, and a curable composition containing them can be obtained.
The curable composition has good workability and can give a cured product with excellent tensile properties.

The definitions and meanings of terms and notations used in this specification are shown below.
The term "polyoxyalkylene polymer" refers to a polymer having a polyoxyalkylene chain in the main chain skeleton, which is produced by ring-opening addition polymerization of alkylene oxide monomers.
The term "(meth)acrylic acid alkyl ester polymer" refers to a polymer having a carbon-carbon bond chain in the main chain skeleton formed by vinyl polymerization of a (meth)acrylic acid alkyl ester monomer. The term "(meth)acrylic acid" refers to either or both of acrylic acid and methacrylic acid.
The expression "x to y" indicating a range of values means that the range is from x to y.

The term "reactive silyl group" refers to a group in which a hydroxyl group or a hydrolyzable group is bonded to a silicon atom and which can form a crosslinked structure through a siloxane bond. The reaction to form the siloxane bond is accelerated by a curing catalyst.
The "reactive silyl group" referred to in the present invention is preferably a group represented by the following formula (2).
-SiX _a R ¹ _3-a (2)

In formula (2), X represents a hydrogen atom, a halogen atom, 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 mercapto group, and an alkenyloxy group. Among these, an alkoxy group is preferred because it is mildly hydrolyzable and easy to handle. Examples of the alkoxy group include a methoxy group, an ethoxy group, and an isopropoxy group. A methoxy group or an ethoxy group is preferred because the curable composition cures by rapidly forming a crosslinked structure through siloxane bonds, making it easier to obtain a cured product with good physical properties.

^R1 is a monovalent organic group having 1 to 20 carbon atoms and does not contain a hydrolyzable group. The organic group is preferably at least one selected from an alkyl group, a cycloalkyl group, an aryl group, a benzyl group, an α-chloroalkyl group, and a triorganosiloxy group. Specific examples include linear or branched alkyl groups having 1 to 4 carbon atoms, cyclohexyl groups, phenyl groups, benzyl groups, α-chloromethyl groups, trimethylsiloxy groups, triethylsiloxy groups, and triphenylsiloxy groups. Of these, methyl groups or ethyl groups are preferred from the viewpoint of the balance between the curability and stability of the polymer having a reactive silyl group. Furthermore, an α-chloromethyl group is preferred from the viewpoint of a high curing rate. A methyl group is preferred from the viewpoint of availability.
a is an integer of 1 to 3. When a is 1, two R ^1s may be the same or different. When a is 2 or 3, multiple Xs may be the same or different. a is preferably 1 or 2, and more preferably 2.

Specific examples of reactive silyl groups include trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, tris(2-propenyloxy)silyl, triacetoxysilyl, dimethoxymethylsilyl, diethoxymethylsilyl, dimethoxyethylsilyl, diisopropoxymethylsilyl, (α-chloromethyl)dimethoxysilyl, and (α-chloromethyl)diethoxysilyl. Of these, trimethoxysilyl, triethoxysilyl, dimethoxymethylsilyl, and diethoxymethylsilyl groups are preferred due to their high reactivity and favorable curing properties, with dimethoxymethylsilyl and trimethoxysilyl being more preferred.

The "average number of reactive silyl groups per molecule" is a value calculated by multiplying the concentration [mol/g] of reactive silyl groups in the polymer determined by proton nuclear magnetic resonance ( ¹ H-NMR) spectroscopy by the number average molecular weight.
The "number average molecular weight" (hereinafter referred to as "Mn") and the "weight average molecular weight" (hereinafter referred to as "Mw") are polystyrene-equivalent molecular weights determined by gel permeation chromatography (GPC). The molecular weight distribution is the ratio of Mw to Mn (Mw/Mn). Specifically, it is measured by the method described in the examples below.
The term "active hydrogen-containing group" refers to one or more groups selected from the group consisting of a hydroxyl group, a carboxyl group, a primary amino group, a secondary amino group, a hydrazide group, and a mercapto group. The hydrogen atoms contained in these groups are "active hydrogens."
"Silylation agent" means a compound used to introduce reactive silyl groups into a polymer.

The method for producing a curable composition of the present invention is a method for producing a curable composition by blending a predetermined polymer (A) and a predetermined polymer (B).
The curable composition may contain a component other than the polymer (A) and the polymer (B). For example, a polyoxyalkylene polymer having an average of less than 1.0 reactive silyl group per molecule may be contained as a polymer other than the polymer (A) and the polymer (B). Furthermore, the curable composition may contain a component other than these polymers, as described below.

[Polymer (A)]
The polymer (A) is a polyoxyalkylene polymer having an average of 1.0 or more reactive silyl groups per molecule and an Mn of 4,000 to 35,000.
The polymer (A) to be blended in the curable composition may be one type alone or two or more types, and may be linear or branched.
The polymer (A) has a polyoxyalkylene chain in its main chain skeleton formed by polymerization of one or more alkylene oxide monomers. When the main chain skeleton of the polymer (A) is formed by copolymerization of two or more alkylene oxide monomers, the arrangement of the monomers in the copolymerization is not particularly limited, and the copolymerization may be random copolymerization, alternating copolymerization, or block copolymerization.

Examples of the main chain skeleton of polymer (A) include those formed by the polymerization of ethylene oxide monomer, propylene oxide monomer, butylene oxide monomer, tetramethylene oxide monomer, copolymerization of ethylene oxide monomer and propylene oxide monomer, and copolymerization of propylene oxide monomer and butylene oxide monomer. Of these, those formed by the polymerization of propylene oxide monomer are preferred, taking into account the physical properties such as tensile characteristics of the cured product of the curable composition.

The main chain skeleton of polymer (A) preferably has 2 to 8 terminal ends, more preferably 2 to 6, even more preferably 2 to 4, and particularly preferably 2 or 3. From the viewpoints of compatibility with polymer (B) and the tensile properties of the cured product of the curable composition, 2 terminal ends is particularly preferred. Polymer (A) is linear when it has 2 terminal ends, and branched when it has 3 or more terminal ends.

Polymer (A) has an average of 1.0 or more reactive silyl groups per molecule. From the viewpoints of compatibility with polymer (B) and the tensile properties of the cured product of the curable composition, the average number of reactive silyl groups per molecule is preferably more than 1.0 and not more than 8.0, more preferably 1.1 to 6.0, and even more preferably 1.2 to 4.0.

The polymer (A) preferably has an average of more than 0.5 reactive silyl groups per terminal. From the viewpoint of the tensile properties of the cured product of the curable composition, the average number of reactive silyl groups per terminal is preferably more than 0.5 and not more than 4.0, more preferably 0.6 to 3.0, and even more preferably 0.7 to 2.0.

The Mn of the polymer (A) is 4,000 to 35,000, preferably 5,000 to 30,000, and more preferably 10,000 to 25,000.
If Mn is less than 4000, the amount of reactive silyl groups introduced per mass of polymer (A) becomes too large, making it difficult to obtain good tensile properties of the cured product of the curable composition.On the other hand, if Mn is more than 35000, the viscosity of polymer (A) tends to be high, making it difficult to obtain good compatibility with polymer (B).
The molecular weight distribution (Mw/Mn) of the polymer (A) is preferably 1.8 or less, more preferably 1.5 or less, and even more preferably 1.2 or less, from the viewpoint of keeping the viscosity low.

<Method for producing polymer (A)>
The polymer (A) is preferably produced by introducing a reactive silyl group into the terminal of the main chain of a polyoxyalkylene polymer, which is a precursor polymer. For example, an unsaturated bond can be introduced into the terminal of the main chain of the polyoxyalkylene polymer, which is a precursor polymer, and then the unsaturated bond can be reacted with a silylating agent to introduce the reactive silyl group into the terminal.

The precursor polymer is an oxyalkylene polymer obtained by ring-opening addition polymerization of an alkylene oxide monomer with the active hydrogen of an initiator having an active hydrogen-containing group in the presence of a catalyst. Preferably, the active hydrogen-containing group is a hydroxyl group, and the precursor polymer has a hydroxyl group at the end of the main chain. The initiator may be used alone or in combination of two or more.
When the initiator has two or more active hydrogen atoms, the number of active hydrogen atoms is usually the same as the number of terminals of the main chain of the precursor polymer.

The initiator is preferably a compound having 2 to 8 hydroxyl groups, and the number of hydroxyl groups is more preferably 2 to 6, still more preferably 2 to 4, and particularly preferably 2 or 3. When obtaining a linear polymer (A), it is preferable to use an initiator having two active hydrogen-containing groups, and it is more preferable that the two active hydrogen-containing groups are hydroxyl groups.
Examples of initiators having two hydroxyl groups include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, and low-molecular-weight polyoxypropylene glycol.
Examples of initiators having three or more hydroxyl groups include glycerin, trimethylolpropane, trimethylolethane, sorbitol, pentaerythritol, and low-molecular-weight polyoxypropylenetriol.

The catalyst may be a known catalyst, and examples thereof include alkali catalysts such as potassium hydroxide, transition metal compound-porphyrin complex catalysts such as complexes obtained by reacting an organoaluminum compound with porphyrin, composite metal cyanide complex catalysts, catalysts made of phosphazene compounds, etc. Among these, composite metal cyanide complex catalysts are preferred because they narrow the molecular weight distribution of the precursor polymer and can keep the viscosity of the curable composition low.
Known compounds can be used as the composite metal cyanide complex, such as a zinc hexacyanocobaltate complex with tert-butanol as a ligand. A known method can also be used to produce a polyoxyalkylene polymer using a composite metal cyanide complex catalyst. For example, production methods using catalysts 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, International Publication No. 2013/065802, Japanese Patent Application Laid-Open No. 2015-010162, etc. can be used.

The method for producing polymer (A) from the precursor polymer can be a known method, such as those described in JP-B No. 45-36319, JP-A No. 50-156599, JP-A No. 61-197631, JP-A No. 3-72527, JP-A No. 8-231707, JP-A No. 2015-105322, JP-A No. 2015-105323, JP-A No. 2015-105324, JP-A No. 2015-105293, and JP-A No. 2015-105326. Methods disclosed in, for example, Patent Publication No. 16-216633, JP 2017-39782 A, U.S. Patent No. 3,632,557, U.S. Patent No. 4,960,844, WO 2013/180203, WO 2014/192842, WO 2015/080067, WO 2015/105122, WO 2015/111577, and WO 2016/002907 can be used.

A preferred method for introducing an unsaturated bond into the terminal of the main chain skeleton of a polyoxyalkylene polymer, which is a precursor polymer, is, for example, a method in which a precursor polymer having a hydroxyl group at its terminal is reacted with an alkali metal alkoxide in an amount that is in excess of the equivalent of the terminal hydroxyl group, and then a halogenated unsaturated hydrocarbon compound having an unsaturated bond, such as allyl chloride, in an amount that is in excess of the equivalent of the terminal hydroxyl group.
Another preferred method is to react a precursor polymer having a hydroxyl group at its terminal with an alkali metal alkoxide in an amount that is in excess of the terminal hydroxyl group, then react with an epoxy compound having an unsaturated bond, and then react with a halogenated unsaturated hydrocarbon compound having an unsaturated bond, such as allyl chloride, in an amount that is in excess of the terminal hydroxyl group after the reaction. In this case, the number of unsaturated bonds introduced into the terminals of the main chain skeleton of the precursor polymer can be increased compared to the number of hydroxyl groups, which are active hydrogen-containing groups in the initiator used to obtain the precursor polymer, and the number of terminals into which reactive silyl groups are introduced can be increased.

Next, a silylating agent is reacted by hydrosilylation with the unsaturated bond introduced at the end of the main chain skeleton of the precursor polymer, thereby introducing a reactive silyl group at the end.
Examples of the silylating agent include hydrosilane compounds (e.g., compounds in which a group represented by formula (2) is bonded to a hydrogen atom), reactive silyl groups, and compounds having a group capable of reacting with an unsaturated bond to form a bond (e.g., a mercapto group). Specific examples include trimethoxysilane, triethoxysilane, triisopropoxysilane, tris(2-propenyloxy)silane, triacetoxysilane, dimethoxymethylsilane, diethoxymethylsilane, dimethoxyethylsilane, diisopropoxymethylsilane, (α-chloromethyl)dimethoxysilane, (α-chloromethyl)diethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. The silylating agents may be used alone or in combination of two or more. Among these, trimethoxysilane, triethoxysilane, dimethoxymethylsilane, and diethoxymethylsilane are preferred, and dimethoxymethylsilane or trimethoxysilane is more preferred, as they have high reactivity and good curability.

As described above, the average number of reactive silyl groups per molecule of the polymer (A) is adjusted to be 1 or more.
The silylation rate of the polymer (A) is preferably more than 50 mol% and not more than 100 mol%, more preferably 60 to 97 mol%, and even more preferably 65 to 95 mol%. When the polymer (A) is made up of two or more types of polymers, the silylation rate is the average value of the silylation rates of the respective polymers.
For example, when the polymer (A) is linear and has two ends of the main chain skeleton, if the silylation rate is 50 mol % or more, the average number of reactive silyl groups per molecule of the polymer (A) will be 1 or more.
The silylation rate can be controlled by adjusting the amount of silylating agent reacted with the unsaturated bond introduced at the end of the main chain of the precursor polymer. The silylation rate may also be expressed as the equivalent amount of silylating agent charged relative to the number of ends of the main chain of the precursor polymer.

From the viewpoint of achieving good tensile properties in the cured product of the curable composition, the content of polymer (A) in the curable composition is preferably 1 to 80 mass%, more preferably 3 to 75 mass%, and even more preferably 5 to 70 mass%, relative to 100 mass% of the curable composition.

[Polymer (B)]
The polymer (B) is a (meth)acrylic acid alkyl ester polymer having an average of 0.5 or more reactive silyl groups per molecule, and obtained by subjecting a monomer composition containing a monomer (b1) and a monomer (b2) to living radical polymerization in the presence of a quaternary ammonium halide salt, and then reacting the monomer composition with a silylating agent.
The polymer (B) to be blended in the curable composition may be one type alone or two or more types, and may be linear or branched.
The polymer (B) has, in its main chain skeleton, a carbon-carbon bond chain formed by vinyl polymerization of one or more (meth)acrylic acid alkyl ester monomers. The main chain skeleton of the polymer (B) is formed by copolymerization of two or more monomers, and the arrangement of the monomers in the copolymerization is not particularly limited, and the copolymerization may be random copolymerization, alternating copolymerization, or block copolymerization.

The total amount of the monomer (b1) and the monomer (b2) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and may be 100 parts by mass, relative to 100 parts by mass of the total amount of all the monomers in the monomer composition.
When the monomer composition contains a monomer other than the monomers (b1) and (b2), the monomer is preferably a vinyl polymer, such as acrylonitrile, styrene, a fluorine-containing vinyl monomer, a silicon-containing vinyl monomer, etc. Note that the silicon-containing vinyl monomer referred to here does not include a reactive silyl group-containing vinyl monomer.

Monomer (b1) is a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms. The alkyl group may be linear or branched. Specific examples of monomer (b1) include butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and octyl (meth)acrylate. Monomer (b1) may be used alone or in combination of two or more types.

Monomer (b2) is a (meth)acrylic acid alkyl ester having an alkyl group containing 9 to 20 carbon atoms. The alkyl group may be linear or branched, and linear alkyl groups are preferred from the standpoints of ease of copolymerization with monomer (b1) and availability. Examples of monomer (b2) include nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate. Monomer (b2) may be used alone or in combination of two or more types. From the standpoint of good tensile properties of the cured product, it is more preferable to use at least two types. When two or more types of monomer (b2) are used in combination, from the viewpoints of good tensile properties of the cured product of the curable composition and easy availability, it is preferable that they include a (meth)acrylic acid alkyl ester having an alkyl group with 9 to 14 carbon atoms and a (meth)acrylic acid alkyl ester having an alkyl group with 16 to 20 carbon atoms, more preferably lauryl (meth)acrylate and stearyl (meth)acrylate, and even more preferably that monomer (b2) is lauryl (meth)acrylate and stearyl (meth)acrylate.

In the monomer composition, the difference in the number of carbon atoms between the alkyl group of the (meth)acrylic acid alkyl ester of monomer (b1) and the alkyl group of the (meth)acrylic acid alkyl ester of monomer (b2) is preferably 2 to 16, more preferably 4 to 15, and even more preferably 6 to 14, from the viewpoints of good compatibility of polymer (B) with polymer (A) and good tensile properties of the cured product of the curable composition.

The content of the monomer (b1) in the monomer composition is 10 to 90 parts by mass, preferably 30 to 85 parts by mass, and more preferably 50 to 80 parts by mass, relative to 100 parts by mass of the total of the monomer (b1) and the monomer (b2).
If the amount of the monomer (b1) is less than 10 parts by mass, the polymer (B) cannot have good compatibility with the polymer (A). If the amount of the monomer (b1) is more than 90 parts by mass, the viscosity of the polymer (B) becomes too high, and in this case too, the polymer (B) cannot have good compatibility with the polymer (A), and it is difficult to obtain good tensile properties of the cured product of the curable composition.

Polymer (B) has an average of 0.5 or more reactive silyl groups per molecule. From the viewpoints of compatibility with polymer (A) and the tensile properties of the cured product of the curable composition, the average number of reactive silyl groups per molecule is preferably 1.0 to 6.0, and more preferably 1.1 to 5.0.

The Mn of the polymer (B) is preferably 6,000 to 300,000, more preferably 8,000 to 100,000, and even more preferably 10,000 to 50,000.
When Mn is 6000 or more, the cured product of the curable composition is likely to have good tensile properties. When Mn is 300000 or less, the viscosity of the polymer (B) can be kept low, and good compatibility with the polymer (A) is likely to be obtained.
The molecular weight distribution (Mw/Mn) of the polymer (B) is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less, from the viewpoint of keeping the viscosity low and obtaining good compatibility with the polymer (A).

<Method for producing polymer (B)>
The polymer (B) can be obtained by subjecting a monomer composition containing the monomer (b1) and the monomer (b2) to living radical polymerization in the presence of a quaternary ammonium halide salt and reacting the monomer composition with a silylating agent. That is, the main chain of the polymer (B) is formed by living radical polymerization using a quaternary ammonium halide salt as a catalyst. Such living radical polymerization is preferably a reversible coordination-mediated polymerization (RCMP) method.
According to the RCMP living radical polymerization, it is easy to control the molecular weight of the polymer, and it is easy to arbitrarily control the introduction of reactive silyl groups during the progress of the polymerization reaction, and further, it is possible to obtain a (meth)acrylic acid alkyl ester polymer having reactive silyl groups, which has good compatibility with the polymer (A).
The (meth)acrylic acid alkyl ester polymer having a reactive silyl group produced by the above-mentioned living radical polymerization has excellent compatibility with the polymer (A), unlike those produced by the ATRP method, the RTCP method, etc. The reason for this is not clear, but it is thought that the compatibility between the polymer (B) and the polymer (A) is improved because the quaternary ammonium halide salt used as a catalyst for the living radical polymerization to obtain the polymer (B) has amphiphilicity.

The quaternary ammonium halide salt used as the catalyst for the living radical polymerization may be used alone or in combination of two or more kinds.
As the quaternary ammonium halide salt, from the viewpoints of ease of handling, catalytic activity, etc., a quaternary ammonium iodide salt or a quaternary ammonium bromide salt is preferred, and a quaternary ammonium iodide salt is more preferred.

The quaternary ammonium iodide salt is preferably a compound represented by the following formula (1):
R ₄ N ⁺ I ^- (1)
In formula (1), each R is independently an alkyl group having 1 to 8 carbon atoms. The alkyl group may be linear or branched. From the viewpoint of availability, it is preferable that the four R are the same alkyl group.
Specific examples of the quaternary ammonium iodide salt include tetramethylammonium iodide, tetrabutylammonium iodide, tetraoctylammonium iodide, etc. Among these, tetrabutylammonium iodide is preferred from the viewpoints of availability and compatibility with monomers.

From the viewpoint of controlling the progress of the polymerization reaction, the amount of the quaternary ammonium halide salt, which serves as the catalyst in the living radical polymerization, added is preferably 0.1 to 15.0 parts by mass, more preferably 0.2 to 10.0 parts by mass, and even more preferably 0.5 to 8.0 parts by mass, per 100 parts by mass of all monomers in the monomer composition.

In the living radical polymerization, it is preferable to use an organic iodine compound as an initiator. The initiator may be used alone or in combination of two or more.
When the number of iodine atoms in the initiator is 2 or more, the number of iodine atoms is usually the same as the number of terminals of the main chain skeleton of the polymer (B).

The initiator is preferably a compound having 1 to 8 iodine atoms, and the number of iodine atoms is more preferably 1 to 6, and further preferably 1 to 3. When a linear polymer (B) is to be obtained, it is preferable to use a compound having 1 or 2 iodine atoms as the initiator, and a diiodo compound having 2 iodine atoms is more preferable.
Specific examples of the organic iodine compound include 2-iodo-2-methylpropionitrile, 2-iodo-2-methylbutylnitrile, ethyl 2-iodoisobutyrate, 1,4-diiodooctafluorobutane, ethylene glycol bis(2-iodoisobutyrate), diethyl 2,5-diiodoadipate, 1,4-bis(1'-iodoethyl)benzene, and ethylene glycol bis(2-iodo-2-phenylacetate). Of these, 1,4-diiodooctafluorobutane is preferred from the viewpoints of availability and ease of control of the polymerization reaction.

From the viewpoint of controlling the progress of the polymerization reaction, the amount of initiator added in the living radical polymerization is preferably 0.1 to 15.0 parts by mass, more preferably 0.2 to 10.0 parts by mass, and even more preferably 0.5 to 8.0 parts by mass, per 100 parts by mass of all monomers in the monomer composition.

Living radical polymerization may be carried out in a solvent or without a solvent. When a solvent is used, examples of the solvent include cyclic ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbon compounds such as benzene, toluene, and xylene; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and alcohols such as methanol, ethanol, and isopropanol. Of these, cyclic ethers, aromatic hydrocarbon compounds, esters, and ketones are preferred. These may be used alone or in combination of two or more.

From the viewpoint of polymerization reaction efficiency, the polymerization temperature in living radical polymerization is preferably 50 to 180°C, more preferably 60 to 160°C, and even more preferably 70 to 140°C.

Examples of a method for obtaining a (meth)acrylic acid alkyl ester polymer having a reactive silyl group by living radical polymerization of a monomer composition and reacting it with a silylating agent include the following methods <1> and <2>.
<1> A method in which a monomer composition containing a monomer (b1) and a monomer (b2) is subjected to living radical polymerization, and the iodine atom at the end of the main chain skeleton of the obtained (meth)acrylic acid alkyl ester polymer is converted to a reactive silyl group using a silylating agent such as a compound having a reactive silyl group, an amino group, or a mercapto group.
<2> A method in which living radical polymerization of a monomer composition containing a monomer (b1) and a monomer (b2) is initiated, and a compound having a reactive silyl group and a vinyl group is added as a silylating agent during the polymerization, thereby copolymerizing the monomer (b1), the monomer (b2), and the silylating agent.

The compound used as the silylating agent differs between methods <1> and <2> above, but in both cases, an amount sufficient to produce a (meth)acrylic acid alkyl ester polymer having an average of 0.5 or more reactive silyl groups per molecule is used. From the viewpoint of favorable elongation of the cured product of the curable composition described below, the amount of silylating agent added is preferably 0.5 to 10.0 parts by mass, more preferably 1.0 to 8.0 parts by mass, even more preferably 1.5 to 7.0 parts by mass, and particularly preferably 2.0 to 6.0 parts by mass, per 100 parts by mass of the total of monomer (b1) and monomer (b2).

According to the method <1>, a reactive silyl group can be efficiently introduced into the terminal of the main chain of the (meth)acrylic acid alkyl ester polymer by a substitution reaction.
Examples of the silylating agent in the method <1> include 3-aminopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These may be used alone or in combination of two or more. Of these, 3-aminopropyldimethoxymethylsilane or 3-mercaptopropylmethyldimethoxysilane is preferred.

In the method <1>, the substitution reaction with the silylating agent is preferably carried out in a solvent. The solvent to be used is not particularly limited and can be selected from the same solvents as those used in the above-mentioned living radical polymerization.
The reaction temperature for the substitution reaction is not particularly limited, but is generally preferably 0 to 85°C, more preferably 15 to 80°C, and even more preferably 25 to 75°C.

According to the method <2>, it is possible to control the introduction of the reactive silyl group into any position without being limited to the terminal of the main chain skeleton of the (meth)acrylic acid alkyl ester polymer.
Examples of the silylating agent in method <2> include 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and vinyltrimethoxysilane. These may be used alone or in combination of two or more. Of these, 3-methacryloxypropylmethyldimethoxysilane or 3-acryloxypropylmethyldimethoxysilane is preferred.

In method <2>, in the living radical polymerization of a monomer composition containing monomer (b1) and monomer (b2), the silylating agent can be added at any time between the start and end of the reaction, and the reaction temperature after the addition does not need to be changed.

After the silylating agent has been reacted as described above, any unreacted silylating agent remaining in the reaction system is removed, and the resulting mixture is dried to obtain the polymer (B).
The removal of unreacted silylating agent can be carried out by a known method such as solvent extraction, etc. Drying can also be carried out by a known method under conditions such as heating or reduced pressure, as necessary.

[Curable composition]
The curable composition can be obtained by blending the polymer (A) and the polymer (B).
The polymer (A) and the polymer (B) have good compatibility, and even after one week has passed since they were mixed and stirred, the polymer (A) and the polymer (B) do not undergo phase separation or become cloudy, and a uniform liquid state is maintained.
Therefore, the curable composition has good workability when used, and a cured product that is homogeneous and has excellent tensile properties can be obtained.

The mass blending ratio of polymer (A) to polymer (B) in the curable composition is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and even more preferably 30/70 to 70/30, from the viewpoint of effectively exhibiting the desired tensile properties in the cured product of the curable composition.

Suitable applications of the curable composition include sealants (e.g., elastic sealants for construction, sealants for double glazing, anti-rust and waterproof sealants for glass edges, sealants for the rear surfaces of solar cells, sealants for buildings, sealants for ships, sealants for automobiles, and sealants for roads), electrical insulating materials (insulating coating materials for electric wires and cables), adhesives, paints, etc. The curable composition is particularly suitable for applications requiring good tensile properties of the cured product.
Therefore, the curable composition of the present invention is preferably used for sealants, adhesives, paints, etc., and is particularly suitable as a sealant composition.

The curable composition of the present invention may contain other components in addition to the polymer (A) and the polymer (B). For example, when the curable composition is a sealant composition, the other components may include a filler, a plasticizer, a stabilizer, a thixotropic agent, a dehydrating agent, an adhesion promoter, an oxygen-curable compound, a photocurable compound, a curing catalyst, etc.
Specifically, other components are appropriately selected from known components described in WO 2013/180203, WO 2014/192842, WO 2016/002907, JP 2014-88481 A, JP 2015-10162 A, JP 2015-105293 A, JP 2017-214541 A, etc., and can be used in any combination.

The present invention will be explained in detail below based on examples, but the present invention is not limited to the following examples.

First, a polyoxyalkylene polymer and a (meth)acrylic acid alkyl ester polymer were produced according to the following synthesis examples.
The methods for measuring various physical properties in the following synthesis examples are shown below.

[Measurement method]
[Number average molecular weight (Mn) and weight average molecular weight (Mw)]
The Mn and Mw of various polymers were measured by gel permeation chromatography (GPC) under the following conditions (in terms of polystyrene), and the molecular weight distribution (Mw/Mn) was calculated from these values.
<Measurement conditions>
・Equipment used: "HLC-8220GPC", manufactured by Tosoh Corporation ・Data processing device: "SC-8020", manufactured by Tosoh Corporation ・Columns used: The following two types of columns were connected in series: "TSKgel (registered trademark) Super HZ4000", manufactured by Tosoh Corporation, two columns; "TSKgel (registered trademark) Super HZ2500", manufactured by Tosoh Corporation, two columns ・Column temperature: 40°C
Detector: Refractive index (RI)
Eluent: tetrahydrofuran Flow rate: 0.35 mL/min Sample concentration: 0.5% by mass
Sample injection volume: 20 μL
Standard sample for creating a calibration curve: polystyrene; "EasiCal (registered trademark) PS-2", manufactured by Agilent Technologies, Inc.

[Polymerization reaction rate]
The reaction solution was sampled during the reaction in the synthesis of various polymers, and proton nuclear magnetic resonance ( ¹ H-NMR) spectra were measured under the following conditions. The polymerization reaction rate was calculated from the integral value I _M of the signal derived from the unreacted monomer and the integral value I _P of the signal derived from the target polymer in the obtained NMR chart using the following formula.
Polymerization reaction rate [%]=I _P /(I _M +I _P )×100
<Measurement conditions>
Equipment used: "JNM-ECZ400S FT-NMR", manufactured by JEOL Ltd. Solvent: deuterated chloroform Polymer concentration in measurement sample: 1 to 10% by mass
・Number of times accumulated: 8 times

[Average number of reactive silyl groups per molecule]
The concentration of reactive silyl groups in the polymer (mol/g) determined from ^{the 1} H-NMR spectrum measured for each polymer was multiplied by Mn to calculate the value.
The ¹ H-NMR spectrum was accumulated 512 times, and the other measurement conditions were the same as those in the above section on [Polymerization reaction rate].

[Synthesis of polyoxyalkylene polymer (polymer (A))]
[Raw material compound]
Details of the raw material compounds used in Synthesis Examples 1 and 2 below are as follows.
<Initiator>
PPG: Polypropylene glycol obtained by ring-opening addition polymerization of propylene oxide to propylene glycol; hydroxyl group equivalent (molecular weight per hydroxyl group) 1,000
<Monomer>
PO: Propylene oxide <catalyst>
TBA-DMC catalyst: zinc hexacyanocobaltate complex with tert-butanol as a ligand (silylating agent)
DMMS: dimethoxymethylsilane

(Synthesis Example 1)
Using 64.1 g of PPG as an initiator, a reaction was carried out in the presence of 705.0 g of PO and 0.03 g of TBA-DMC catalyst at 120°C until the pressure of the reaction system no longer decreased, thereby obtaining a precursor polymer (2) having two hydroxyl groups per molecule at the terminals of the polyoxypropylene chains (Mw: 25,900, Mn: 24,000, Mw/Mn: 1.08).
A methanol solution containing sodium methoxide in an amount 1.05 times the molar equivalent of the hydroxyl groups of the precursor polymer (2) was added to the precursor polymer (2) to convert it into an alkoxide, and the methanol was distilled off under heating and reduced pressure. Then, allyl chloride in an excess molar equivalent of the hydroxyl groups of the precursor polymer (2) was added and reacted to obtain a precursor polymer (2) having allyl groups at all ends of the polyoxypropylene chains.
Next, in the presence of chloroplatinic acid hexahydrate, DMMS was added in an amount of 0.75 times the molar equivalent (silylation rate 75 mol%) relative to the allyl groups of precursor polymer (2), and the mixture was reacted at 70°C for 5 hours to obtain polymer A1 having a reactive silyl group at the end of the polyoxypropylene chain.

(Synthesis Example 2)
A precursor polymer (2) (Mw 17,100, Mn 16,000, Mw/Mn 1.07) was obtained in the same manner as in Synthesis Example 1, except that the amount of PO in Synthesis Example 1 was changed to 449.0 g, and then a polymer A2 having a reactive silyl group at the end of the polyoxypropylene chain (silylation rate 75 mol%) was obtained.

Table 1 shows the Mw, Mn, Mw/Mn, and average number of reactive silyl groups per molecule of each of the polymers A1 and A2 obtained in Synthesis Examples 1 and 2 above.

[Synthesis of (meth)acrylic acid alkyl ester polymer (polymer (B))]
[Raw material compound]
Details of the raw material compounds used in the following Synthesis Examples 3 to 16 are as follows:
<Monomer (b1)>
BA: n-butyl acrylate HA: n-hexyl acrylate <monomer (b2)>
LA: Lauryl acrylate LMA: Lauryl methacrylate StA: Stearyl acrylate (silylating agent)
KBM-502: 3-methacryloxypropylmethyldimethoxysilane; "KBM-502", manufactured by Shin-Etsu Chemical Co., Ltd. KBM-5102: 3-acryloxypropylmethyldimethoxysilane; "KBM-5102", manufactured by Shin-Etsu Chemical Co., Ltd. KBM-902: 3-aminopropyldimethoxymethylsilane; "KBM-902", manufactured by Shin-Etsu Chemical Co., Ltd. DMMS: dimethoxymethylsilane KBM-903: 3-aminopropyltriethoxysilane; "KBM-903", manufactured by Shin-Etsu Chemical Co., Ltd. <Catalyst>
BNI: Tetrabutylammonium iodide CuBr-PMDT: Copper bromide-pentamethyldiethylenetriamine complex NIS: N-iodosuccinimide <initiator>
DIFB: 1,4-diiodooctafluorobutane DBrADE: 2,5-dibromoadipate diethyl DIX: 1,4-bis(iodomethyl)benzene BPO: benzoyl peroxide

(Synthesis Example 3)
A 300 mL flask equipped with a stirrer and a thermometer was charged with 65.37 g (70.0 parts by mass) of BA, 28.01 g (30.0 parts by mass) of LA, 1.90 g (2.0 parts by mass) of DIFB, and 5.27 g (5.6 parts by mass) of BNI. The flask was thoroughly degassed by bubbling with nitrogen gas, and the liquid temperature was maintained at 125° C. with stirring to initiate the polymerization reaction, which was allowed to proceed for 13 hours (polymerization reaction rate 90%).
The reaction system was cooled to 70°C, and 3.16 g (3.4 parts by mass) of KBM-902 as a silylating agent and 100 g of toluene as a solvent were added, and the liquid temperature was maintained at 70°C to carry out the reaction for 5 hours.
The reaction system was cooled to 25° C., methanol was added, and the unreacted silylating agent was removed by a separation operation, followed by drying under reduced pressure of 0.3 kPa at 80° C. for 5 hours to obtain polymer B1.

(Synthesis Example 4)
The polymerization reaction was initiated in the same manner as in Synthesis Example 3 and continued for 8 hours (polymerization reaction rate: 65%).
Further, 3.17 g (3.4 parts by mass) of KBM-5102 was added as a silylating agent, and the mixture was reacted for 5 hours (polymerization reaction rate excluding the silylating agent: 90%).
Next, in the same manner as in Synthesis Example 3, unreacted silylating agent was removed, and the residue was dried under reduced pressure to obtain Polymer B2.

(Synthesis Example 5)
The polymerization reaction was initiated in the same manner as in Synthesis Example 3 and continued for 8 hours (polymerization reaction rate: 65%).
Further, 3.17 g (3.4 parts by mass) of KBM-502 was added as a silylating agent, and the mixture was reacted for 5 hours (polymerization reaction rate excluding the silylating agent: 90%).
Next, in the same manner as in Synthesis Example 3, unreacted silylating agent was removed, and the residue was dried under reduced pressure to obtain Polymer B3.

(Synthesis Example 6)
The polymerization reaction was initiated in the same manner as in Synthesis Example 3, except that the amount of DIFB was changed to 3.17 g (3.4 parts by mass), and the reaction was carried out for 8 hours (polymerization reaction rate: 65%).
Further, 5.28 g (5.7 parts by mass) of KBM-5102 was added as a silylating agent, and the mixture was reacted for 5 hours (polymerization reaction rate excluding the silylating agent: 90%).
Next, in the same manner as in Synthesis Example 3, unreacted silylating agent was removed, and the residue was dried under reduced pressure to obtain Polymer B4.

(Synthesis Examples 7 and 8)
In Synthesis Example 4, the types of monomers were changed as shown in Table 2, and the polymerization reaction was otherwise initiated in the same manner as in Synthesis Example 4, and the reaction was carried out for 8 hours (polymerization reaction rate was 65% in all cases).
Further, in the same manner as in Synthesis Example 4, a silylating agent was added and reacted for 5 hours (the polymerization reaction rates other than the silylating agent were all 90%), and after removing the unreacted silylating agent, the mixture was dried under reduced pressure to obtain polymers B5 and B6, respectively.

(Synthesis Examples 9 and 10)
In Synthesis Example 6, the types of monomers were changed as shown in Table 2, and the polymerization reaction was otherwise initiated in the same manner as in Synthesis Example 6, and the reaction was carried out for 8 hours (polymerization reaction rate was 65% in all cases).
Further, 5.28 g (5.7 parts by mass) of KBM-5102 was added as a silylating agent, and the mixture was reacted for 5 hours (the polymerization reaction rates other than the silylating agent were all 90%). After removing the unreacted silylating agent, the mixture was dried under reduced pressure to obtain polymers B7 and B8, respectively.

(Synthesis Examples 11 and 12)
The polymerization reaction was initiated in the same manner as in Synthesis Example 5 and continued for 8 hours (polymerization reaction rate: 65%).
Furthermore, the amount of KBM-502 used as a silylating agent was changed as shown in Table 2, and other conditions were the same as in Synthesis Example 5 to carry out the reaction (the polymerization reaction rates other than that of the silylating agent were all 90%). After removing the unreacted silylating agent, the mixture was dried under reduced pressure to obtain polymers B9 and B10, respectively.

(Synthesis Example 13)
In Synthesis Example 3, the polymerization reaction was initiated in the same manner as in Synthesis Example 3, except that 93.38 g (100 parts by mass) of BA was used as the only monomer, and the reaction was carried out for 13 hours (polymerization reaction rate: 90%).
Next, in the same manner as in Synthesis Example 3, the reaction system was cooled, and a silylating agent and a solvent were added to react. After removing the unreacted silylating agent, the mixture was dried under reduced pressure to obtain a polymer B11.

(Synthesis Example 14)
An alkyl (meth)acrylate polymer was produced by ATRP living radical polymerization, and a reactive silyl group was introduced into the terminal of the main chain of the polymer.
First, a 1 L reactor equipped with a stirrer and a thermometer was charged with 269.1 g (70.0 parts by mass) of BA, 115.32 g (30.0 parts by mass) of LA, 2.80 g (0.78 parts by mass) of CuBr, 34.5 g of acetonitrile, and 5.85 g (1.5 parts by mass) of DBrADE under a nitrogen gas atmosphere. The reactor was thoroughly degassed by bubbling with nitrogen gas, and the liquid temperature was maintained at 70-80 ° C. while stirring, and the mixture was stirred for 30 minutes. Then, PMDT was added as a ligand for CuBr, and the polymerization reaction was initiated. The liquid temperature was maintained at 70-90 ° C. while stirring, and during this time, PMDT was added so that the total amount became 0.564 g, and the mixture was allowed to react for approximately 3 hours.
The reaction system was heated and stirred at 0.3 kPa and 80° C. to remove volatile components, and then 139 g of acrylonitrile, 35.8 g of 1,7-octadiene, and 1.13 g of PMDT were added and reacted for 8 hours with stirring.
The reaction system was heated and stirred at 0.3 kPa and 80°C to remove volatile components, and then toluene was added to dissolve the polymer. Diatomaceous earth was added as a filter aid, and aluminum silicate and hydrotalcite were added as adsorbents. The mixture was heated and stirred at a liquid temperature of 100°C in an oxygen-nitrogen mixed gas atmosphere (oxygen concentration 6% by volume).
The stirred liquid was filtered, and the filtrate was heated and stirred at 0.3 kPa and 100 ° C. to remove volatiles. Then, aluminum silicate and hydrotalcite were added as adsorbents again, and a heat deterioration inhibitor ("Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) was further added, and the mixture was heated and stirred at 1.3 kPa or less and 175 ° C. Further, aluminum silicate and hydrotalcite were added, and an antioxidant ("Irganox (registered trademark) 245", manufactured by BASF Japan Ltd.) was added, and the mixture was heated and stirred at a liquid temperature of 150 ° C. under an oxygen-nitrogen mixed gas atmosphere (oxygen concentration 6% by volume).
Toluene was added to the stirred solution to dissolve the polymer, followed by filtration. The filtrate was heated and stirred at 0.3 kPa and 100° C. to remove volatile components, yielding a precursor polymer having octenyl groups.

300 g of this precursor polymer, 4.39 g (1.1 parts by mass, 2.0 molar equivalents relative to the octenyl groups) of DMMS, 2.20 g (1.0 molar equivalent relative to the octenyl groups) of methyl orthoformate, and 0.028 g (3.34 mg as platinum) of a xylene solution (concentration 20% by mass) of bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)platinum complex as a catalyst were mixed, heated and stirred at 100°C under a nitrogen gas atmosphere, and reacted until the octenyl groups disappeared.
The reaction system was dried under reduced pressure of 0.3 kPa at 100° C. to obtain polymer B12.

(Synthesis Example 15)
Polymer B13 was obtained by ATRP living radical polymerization in the same manner as in Synthesis Example 14, except that in Synthesis Example 14, BA was changed to 300 g (78.0 parts by mass) and LA was changed to StA: 84.4 g (22.0 parts by mass).

(Synthesis Example 16)
An alkyl (meth)acrylate polymer was produced by RTCP living radical polymerization, and a reactive silyl group was introduced into the terminal of the main chain of the polymer.
First, a 1 L reactor equipped with a stirrer and a thermometer was charged with 46.0 g (12.8 parts by mass) of BA, 314.0 g (87.2 parts by mass) of LMA, 3.7 g (1.0 part by mass) of DIX, 0.03 g (0.008 parts by mass) of NIS, 1.2 g (0.3 parts by mass) of BPO, and 154.0 g of methyl orthoacetate. The reactor was thoroughly degassed by bubbling with nitrogen gas, and the liquid temperature was maintained at 70 ° C. with stirring to initiate the polymerization reaction, which was then allowed to react for 3 hours (polymerization reaction rate 70%).
Further, 5.5 g (1.5 parts by mass) of KBM-903 was added as a silylating agent, and the mixture was reacted for 1 hour (polymerization reaction rate: 75%).
Next, in the same manner as in Synthesis Example 3, unreacted silylating agent was removed, and the residue was dried under reduced pressure to obtain Polymer B14.

Table 2 shows the Mw, Mn, Mw/Mn, and average number of reactive silyl groups per molecule for each of Polymers B1 to B14 obtained in Synthesis Examples 3 to 16 above.

[Preparation of curable composition (2)]
The polymers A1, A2 and B1 to B14 obtained in Synthesis Examples 1 to 16 above were mixed in the formulations shown in Examples 1 to 26 in Table 3 to prepare curable compositions.
The compatibility of each curable composition was evaluated as follows.

[Compatibility evaluation]
10 g of the stirred and mixed curable composition was placed in a 20 mL vial and allowed to stand at room temperature (25±5° C.). After one week, the state of the contents was visually observed and evaluated. The evaluation results based on the following evaluation criteria are shown in Table 3.
<Evaluation criteria>
○: Good compatibility (contents are transparent and uniform liquid)
×: Poor compatibility (contents are cloudy or phase separated)

[Preparation of curable composition (2)]
Each curable composition was produced by blending 100 parts by mass of the polyoxyalkylene polymer (A1 or A2) and (meth)acrylic acid alkyl ester polymer (any of B1 to B14) obtained in Synthesis Examples 1 to 16 above with additives in one of the compositions of Blends 1 to 9 in Table 4, and mixing the blends uniformly with a planetary mixer.

[Additives]
Details of the various additives shown in Table 4 are as follows:
<Filler>
Viscolite EL-20: Colloidal calcium carbonate; "Viscolite (registered trademark) EL-20", manufactured by Shiraishi Kogyo Co., Ltd. Whiten SB: Heavy calcium carbonate; "Whiten (registered trademark) SB", manufactured by Shiraishi Calcium Co., Ltd. R-820: Titanium oxide; "R-820", manufactured by Ishihara Sangyo Kaisha, Ltd. Balloon 80GCA: Organic balloon; "Matsumoto Microsphere (registered trademark) MFL-80GCA", manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. <Plasticizer>
EXCENOL 3020: Polypropylene glycol; "EXCENOL (registered trademark) 3020" manufactured by AGC Inc. ALPHON UP-1110: Acrylic polymer; "ALPHON (registered trademark) UP-1110" manufactured by Toagosei Co., Ltd. Polymer Q: Synthesized in Synthesis Example 15 below DINP: Diisononyl phthalate; "VINYCIZER (registered trademark) 90" manufactured by Kao Corporation N-12D: n-Dodecane, purity 98.0% by mass; "Cactus normal paraffin N-12D" manufactured by JXTG Nippon Oil & Energy Corporation Sanso Cizer E-PS: 4,5-epoxycyclohexane-1,2-dicarboxylate-di-2-ethylhexyl; "SANSO CIZER (registered trademark) E-PS" manufactured by New Japan Chemical Co., Ltd. <Stabilizers>
Irganox 1135: antioxidant; "Irganox (registered trademark) 1135" manufactured by BASF Japan Ltd. Tinuvin 326: ultraviolet absorber; "Tinuvin (registered trademark) 326" manufactured by BASF Japan Ltd. Tinuvin 765: light stabilizer; "Tinuvin (registered trademark) 765" manufactured by BASF Japan Ltd. Adeka STAB LA-63P: light stabilizer; "Adeka STAB LA-63P" manufactured by ADEKA Corporation <thixotropic agent>
Disparlon 6500: "Disparlon (registered trademark) 6500", manufactured by Kusumoto Chemicals Co., Ltd. <dehydrating agent>
KBM-1003: Vinyltrimethoxysilane; "KBM-1003", manufactured by Shin-Etsu Chemical Co., Ltd. <adhesion promoter>
KBM-403: 3-glycidoxypropyltrimethoxysilane; "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd. KBM-603: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; "KBM-603", manufactured by Shin-Etsu Chemical Co., Ltd. <amine compounds>
Laurylamine: Reagent, manufactured by Junsei Chemical Co., Ltd. Farmin CS: Coconut amine; "Farmin (registered trademark) CS", manufactured by Kao Corporation Adeka Hardener EH-235R-2: Ketimine compound; "Adeka Hardener (registered trademark) EH-235R-2", manufactured by ADEKA Corporation <Oxygen-curable compound>
・Tung oil: manufactured by Kimura Shoji Co., Ltd. <light curing compound>
Aronix M-309: Trimethylolpropane triacrylate; "Aronix (registered trademark) M-309", manufactured by Toagosei Co., Ltd. (curing catalyst)
・SCAT-32A: "SCAT-32A", manufactured by Nitto Kasei Co., Ltd.

A synthesis example of polymer Q used as a plasticizer is shown below. Note that PO, TBA-DMC catalyst, and DMMS in the description of Synthesis Example 15 are the same as those used in Synthesis Example 1 above.
(Synthesis Example 17)
Polyoxypropylene monool (hydroxyl group equivalent (molecular weight per hydroxyl group): 2000) obtained by ring-opening addition polymerization of PO to n-butanol was used as an initiator.
384 g of initiator and 594 g of PO were reacted in the presence of 0.05 g of TBA-DMC catalyst at 120°C until the pressure of the reaction system stopped decreasing, to obtain a precursor polymer (1') having one hydroxyl group per molecule at the end of the polyoxypropylene chain (Mw 8100, Mn 6900, Mw/Mn 1.10).
A methanol solution containing 1.05 times the molar amount of sodium methoxide relative to the hydroxyl groups of the precursor polymer (1') was added to the precursor polymer (1') to convert it into an alkoxide, and the mixture was heated under reduced pressure to remove the methanol. Then, allyl chloride was added in an excess molar equivalent relative to the hydroxyl groups of the precursor polymer (1') to react with the polymer, thereby obtaining a precursor polymer (2') having one allyl group per molecule at the end of the polyoxypropylene chain.
Next, in the presence of chloroplatinic acid hexahydrate, DMMS was added in an amount of 0.85 times the molar equivalent (silylation rate 85 mol%) of the allyl groups in the precursor polymer (2'), and the mixture was allowed to react at 70°C for 5 hours to obtain a polymer Q having a reactive silyl group at one end of the polyoxypropylene chain (average number of reactive silyl groups per molecule: 0.85).

[Evaluation of tensile properties of cured product]
Each curable composition was used as a filled sample to prepare a sealant test piece in accordance with "5.3 Tensile property test" of JIS A 1439:2016.
The adherends used in the tensile property test were aluminum adherends with an anodized film that had been treated with a primer ("MP-2000", manufactured by Cemedine Co., Ltd.).
The test specimens were cured at a temperature of 23±2°C and a humidity of 50±5% RH for 7 days, then at a temperature of 50±2°C and a humidity of 65±5% RH for 7 days, and then at a temperature of 90±2°C and a humidity of 65±5% RH for a further 7 days.

A tensile test was performed on each specimen using a Tensilon testing machine at a temperature of 23±2°C and a tensile speed of 50 mm/min to measure the maximum tensile stress Tmax [N/mm ² ], elongation at maximum load Emax [%], and 50% tensile stress M50 [N/mm ² ].
A larger Tmax value indicates a higher tensile strength, and if Tmax is 0.40 N/mm ² or more, it can be said that the tensile strength is sufficiently high.
The larger the Emax value, the better the elongation. An Emax of 370% or more can be said to have sufficient elongation, 400% or more can be said to have good elongation, and 500% or more can be said to have very good elongation.
If the M50 value is 0.20 N/ ^mm2 or less, it can be said that the flexibility is sufficient. On the other hand, if the M50 value is too small, it indicates that tack (stickiness) occurs due to insufficient curing, so M50 is preferably 0.070 N/ ^mm2 or more, more preferably 0.080 N/ ^mm2 or more, and even more preferably 0.090 N/ ^mm2 or more.
After the tensile test, it was confirmed that all the specimens underwent cohesive failure.
Table 5 shows representative examples of the evaluation results of the tensile property tests for each curable composition.

When curable compositions were produced using the polyoxyalkylene polymer and (meth)acrylic acid alkyl ester polymer blends of Examples 27 to 33 in Table 5 but with additives changed to blends 2 to 9 in Table 4, they all exhibited good elongation and tensile strength and were found to have sufficient flexibility compared to the curable compositions corresponding to Example 34 using additive blends 2 to 9 (in which the (meth)acrylic acid alkyl ester polymer was B11).

Claims (12)

A method for producing a curable composition comprising blending a polymer (A) and a polymer (B),
the polymer (A) is a polyoxyalkylene polymer having an average of 1.0 or more reactive silyl groups per molecule and a number average molecular weight of 4,000 to 35,000;
The polymer (A) has a polyoxyalkylene chain formed by polymerization of a propylene oxide monomer in its main chain skeleton,
the polymer (B) is a (meth)acrylic acid alkyl ester polymer having an average of 0.5 or more reactive silyl groups per molecule,
The production method includes subjecting a monomer composition containing a monomer (b1) and a monomer (b2) to living radical polymerization in the presence of a quaternary ammonium halide salt, and reacting the monomer composition with a silylating agent, thereby obtaining the polymer (B);
the monomer (b1) is a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms,
the monomer (b2) is a (meth)acrylic acid alkyl ester having an alkyl group having 9 to 20 carbon atoms,
the content of the monomer (b1) in the monomer composition is 10 to 90 parts by mass per 100 parts by mass of the total of the monomer (b1) and the monomer (b2),
The method for producing a curable composition, wherein the living radical polymerization is a reversible coordination-mediated polymerization. The method for producing a curable composition according to claim 1 , wherein the monomer composition contains at least two or more types of the monomer (b2). The method for producing a curable composition according to claim 1 or 2, wherein the silylating agent is added in an amount of 0.5 to 10.0 parts by mass per 100 parts by mass of the total of the monomer (b1) and the monomer (b2). The method for producing a curable composition according to any one of claims 1 to 3, wherein the quaternary ammonium halide salt is a quaternary ammonium iodide salt. The method for producing a curable composition according to claim 4 , wherein the quaternary ammonium iodide salt is a compound represented by the following formula (1):
R ₄ N ⁺ I ^- (1)
(In formula (1), each R is independently an alkyl group having 1 to 8 carbon atoms.) The method for producing a curable composition according to claim 4 or 5, wherein the quaternary ammonium iodide salt is one or more selected from tetramethylammonium iodide, tetrabutylammonium iodide, and tetraoctylammonium iodide. The method for producing a curable composition according to any one of claims 1 to 6, wherein an organic iodine compound is used as an initiator in the living radical polymerization. The method for producing a curable composition according to claim 7, wherein the organic iodine compound is one or more selected from 1,4-diiodooctafluorobutane, ethylene glycol bis(2-iodoisobutyrate), diethyl 2,5-diiodoadipate, 1,4-bis(1'-iodoethyl)benzene, and ethylene glycol bis(2-iodo-2-phenylacetate). The method for producing a curable composition according to any one of claims 1 to 8, wherein the polymer (B) has an average of 1.0 to 6.0 reactive silyl groups per molecule. The method for producing a curable composition according to any one of claims 1 to 9, wherein the number average molecular weight of the polymer (B) is 6,000 to 300,000. The method for producing a curable composition according to any one of claims 1 to 10, wherein the mass blending ratio of the polymer (A) to the polymer (B) is 10/90 to 90/10. The method for producing a curable composition according to any one of claims 1 to 11, wherein the curable composition is a sealant composition.