JP2019199581A - Curable composition and production method of the same, and cured product and sealing material - Google Patents

Abstract

To provide a curable composition that gives a cured product having good workability, a high recovery rate, a good elongation property and a good appearance while suppressing blistering.SOLUTION: The curable composition comprises: a polyoxyalkylene polymer A having a branched structure, which has at least three main-chain terminal groups in one molecule and more than 0.5 in average of a reactive silicon group per one main-chain terminal group; a polymer B having a linear structure, which has two main-chain terminal groups in one molecule and more than 0.5 in average of a reactive silicon group per one main-chain terminal group; and a vinyl polymer C having at least one reactive silicon group in one molecule. In the composition, the proportion of the mass of the polymer A with respect to the total mass of the polymer A and the polymer B is 0.5 to 1.0, and the proportion of the mass of the polymer C with respect to the total mass of the polymer A, the polymer B and the polymer C is 0.1 to 0.6.SELECTED DRAWING: None

Description

  The present invention relates to a moisture-curable curable composition containing a polymer having a reactive silicon group, a method for producing the same, a cured product, and a sealing material.

  The present invention includes a polymer having a hydroxyl group or a hydrolyzable group bonded to a silicon atom, and a polymer having a silicon group that can be crosslinked by forming a siloxane bond (hereinafter referred to as “reactive silicon group”). The present invention relates to a sex composition.

  A polymer having at least one reactive silicon group in the molecule is crosslinked at room temperature by forming a siloxane bond accompanied by a hydrolysis reaction of the reactive silicon group due to moisture or the like, and a rubber-like cured product is formed. It is known to have the property of being obtained.

  Among these polymers having reactive silicon groups, the main chain skeleton is a polyoxyalkylene polymer, a saturated hydrocarbon polymer, a polyacrylic acid alkyl ester polymer, and a polymethacrylic acid alkyl ester polymer. And is widely used for applications such as sealing materials, adhesives, and paints (for example, Patent Document 1). These curable compositions containing a polymer having a reactive silicon group are required to have low viscosity and good workability at the time of construction. Even if it is exposed for a period of time, it is required that the cured product has good physical properties and adhesiveness, the composition does not easily migrate (bleed out) on the surface of the cured product, and the periphery of the cured product is hardly contaminated.

  As a method for solving such a problem, for example, in Patent Document 2, a vinyl polymer having at least one crosslinkable silyl group (reactive silicon group) in one molecule of polymer and an average in one molecule of polymer. And a curable composition based on a polyether polymer having 1.2 or less crosslinkable silyl groups as a main component, and 3.3 molecules of crosslinkable silyl groups in one molecule of the polymer. A vinyl polymer having a number average molecular weight of 6,100, and polypropylene glycol having an average of 1.6 crosslinkable silyl groups in one molecule of the polymer and a number average molecular weight of 16,000 A curable composition prepared by mixing 50 parts to 50 parts of a polyether polymer having a number of molecular weight of 21 and a number average molecular weight of 21. , 500 vinyl polymer and polymer 1 minute A polyether polymer having a polypropylene glycol having an average of 1.6 crosslinkable silyl groups and having a number average molecular weight of 16,000 as an initiator is 70 parts by 30 parts and 60 parts by pair. A curable composition mixed at 40 parts is disclosed, and the cured product is disclosed to be flexible and difficult to bleed out.

JP 05-287187 A JP 2003-313302 A

By the way, it has been found that a sealing material for an outer wall used outdoors has a problem that blisters and wrinkles occur when exposed to an outdoor environment for a long time. This phenomenon is considered to be caused by the fact that the moisture confined inside gradually evaporates and the volume expands when the curable composition for the sealing material forms a cured product. If the swelling from the inside of the cured product does not return to the original state, the surface of the sealing material has irregularities, resulting in a problem that the appearance is deteriorated.
As a result of studies to solve the above problems, the present inventors have found that this problem can be solved by combining the polymers contained in the curable composition into a specific combination. The curable composition of the present invention has good workability, and according to the curable composition of the present invention, a cured product having a high restoration rate, good elongation properties, and good appearance can be provided.

The present invention includes the following [1] to [5].
[1] Branch having 3 or more main chain terminal groups in one molecule and having an average of more than 0.5 reactive silicon groups represented by the following formula 1 per main chain terminal group A polyoxyalkylene polymer A having a structure;
It has a linear structure having two main chain end groups in one molecule and having an average of more than 0.5 reactive silicon groups represented by the following formula 1 per main chain end group Polymer B;
Having at least one vinyl polymer C having a reactive silicon group represented by the following formula 1 in one molecule;
The ratio of the mass of the polymer A to the total mass of the polymer A and the polymer B is 0.5 to 1.0,
And the ratio of the mass of the polymer C with respect to the total mass of the said polymer A, the said polymer B, and the said polymer C is 0.1-0.6.
-SiX _a R _3-a Formula 1
[Wherein, R represents a monovalent organic group having 1 to 20 carbon atoms, and represents an organic group other than a hydrolyzable group, X represents a hydroxyl group or a hydrolyzable group, and a represents an integer of 1 to 3] And when a is 1, R may be the same or different from each other, and when a is 2 or 3, X may be the same or different from each other. ]
[2] The curable composition according to [1], wherein the polymer C is a polymer containing a repeating unit of a (meth) acrylic acid ester monomer.
[3] One main chain terminal group is an inactive monovalent organic group having two main chain end groups in one molecule, and one reactive silicon group represented by the formula 1 The curable composition according to [1] or [2], further comprising a linear oxyalkylene polymer having an average of 0.5 or less per main chain terminal group.
[4] The curable composition of [1] to [3], which is for a sealing material.
[5] A cured product obtained by curing the curable composition of [1] to [4].

  The curable composition of the present invention has good workability, and according to the curable composition of the present invention, a cured product having a high restoration rate, good elongation properties, and good appearance can be provided. The cured product of the present invention has a high restoration rate, good elongation properties, and good appearance.

In the present specification and claims, terms are defined and described as follows.
“Main chain” refers to a polymer chain formed by linking two or more monomers. The “main chain” in the polyoxyalkylene polymer described later refers to a moiety containing a repeating unit based on an initiator residue and an alkylene oxide monomer.
The “main chain end group” is an atomic group bonded to the end of the main chain.
The “active hydrogen-containing group” is at least one group selected from the group consisting of a hydroxyl group, a carboxy group, an amino group, a secondary amino group, a hydrazide group, and a sulfanyl group.
“Active hydrogen” is a hydrogen atom based on the active hydrogen-containing group.
The “unsaturated group” is a monovalent group containing an unsaturated double bond, and is at least one group selected from the group consisting of a vinyl group, an allyl group, and an isopropenyl group.

The “polyoxyalkylene polymer” is a polymer whose main chain skeleton contains repeating units based on an alkylene oxide monomer.
The “precursor polymer” is a polymer before introduction of a reactive silicon group, and is a polyoxyalkylene polymer in which the main chain end group obtained by polymerizing an alkylene oxide monomer with active hydrogen of an initiator is a hydroxyl group. That is.
The “saturated hydrocarbon polymer” is a polymer whose main chain skeleton includes a repeating unit based on a saturated hydrocarbon monomer.
“Poly (meth) acrylic acid alkyl ester polymer” means a polymer containing repeating units based on a (meth) acrylic acid alkyl ester monomer. The (meth) acrylic acid alkyl ester monomer means an acrylic acid alkyl ester, a methacrylic acid alkyl ester, or a mixture of both.
The “silylation rate” is the number of terminal groups that are either a reactive silicon group, an active hydrogen-containing group, an unsaturated group, or an inert monovalent organic group described later, which is a main chain terminal group of the polymer. The ratio of the number of reactive silicon groups to the total of The value of the silylation rate can be measured by NMR analysis. Moreover, it can also represent with the preparation equivalent of this silylating agent with respect to the number of main chain terminal groups at the time of introduce | transducing the said reactive silicon group into the main chain terminal group of a polymer with the silylating agent mentioned later.
The “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 numerical value range represented by “˜” is a numerical value range in which the number on the left side of “−” is the lower limit value and the number on the right side of “˜” is the upper limit value.

The number of main chain end groups is determined by, for example, titration analysis based on the principle of the iodine value measurement method defined in JIS K 0070 after introducing an unsaturated group into the polymer A or polymer B precursor polymer. May be calculated by a method of directly measuring the unsaturated group concentration.
The number average molecular weight (hereinafter referred to as “Mn”) and the weight average molecular weight (hereinafter referred to as “Mw”) in the present specification are gel permeation chromatography using tetrahydrofuran (hereinafter referred to as “THF”) as an eluent. It is a molecular weight in terms of polystyrene as measured by a graphic (hereinafter referred to as “GPC”). The molecular weight distribution is a value calculated by Mw / Mn.
The hydroxyl equivalent molecular weight is a polymer containing a repeating unit based on an alkylene oxide monomer, and the hydroxyl value of an initiator or a precursor polymer is calculated based on JIS K 1557, and “56100 / (hydroxyl value) X (number of active hydrogens of initiator or number of main chain end groups of precursor polymer) ".

The curable composition of the present invention has three or more main chain end groups in one molecule, and the average number of reactive silicon groups represented by the following formula 1 per main chain end group is 0. A polyoxyalkylene polymer having a branched structure (hereinafter referred to as “polymer A”) having more than five, having two main chain end groups in one molecule, and a reactivity represented by the following formula 1. A polymer having a linear structure (hereinafter referred to as “polymer B”) having an average of more than 0.5 silicon groups per main chain end group, and one or more of the following formulas per molecule 1, a vinyl polymer having a reactive silicon group represented by 1 (hereinafter referred to as “polymer C”).
Furthermore, one main chain terminal group is an inactive monovalent organic group having two main chain end groups in one molecule, and one reactive silicon group represented by the above formula 1 is converted into one main group. An oxyalkylene polymer having a linear structure having an average of 0.5 or less per chain end group (hereinafter referred to as “polymer D”) may be included.
The reactive silicon groups of the polymer A, the polymer B, the polymer C, and the polymer D that coexist in the curable composition may be the same as or different from each other.

<Reactive silicon group>
The reactive silicon group is represented by the following formula 1. The reactive silicon group has a hydroxyl group or hydrolyzable group bonded to a silicon atom and can be crosslinked by forming a siloxane bond. The reaction to form siloxane bonds is facilitated by a curing catalyst.
-SiX _a R _3-a Formula 1

In Formula 1, R shows a C1-C20 monovalent organic group. 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 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 From the viewpoint of good balance between curability and stability of the polymer having a reactive silicon group, a methyl group or an ethyl group is preferable. The α-chloromethyl group is preferred because the cured product has a high curing rate. A methyl group is particularly preferable because it is easily available.

In Formula 1, X represents a hydroxyl group or a hydrolyzable group.
Examples of hydrolyzable groups include hydrogen atoms, halogen atoms, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amide groups, acid amide groups, aminooxy groups, sulfanyl groups, and alkenyloxy groups.
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, it is easy to form a siloxane bond quickly and form a crosslinked structure in the cured product, and the physical properties of the cured product are likely to be good.

In Formula 1, a is an integer of 1-3. When a is 1, R may be mutually the same or different. When a is 2 or more, Xs may be the same or different.
a is preferably 1 or 2, and a is more preferably 2.

  Examples of the reactive silicon group represented by Formula 1 include trimethoxysilyl group, triethoxysilyl group, triisopropoxysilyl group, tris (2-propenyloxy) silyl group, triacetoxysilyl group, dimethoxymethylsilyl group, dimethoxy Examples thereof include ethoxymethylsilyl group, dimethoxyethylsilyl group, diisopropoxymethylsilyl group, (α-chloromethyl) dimethoxysilyl group, and (α-chloromethyl) diethoxysilyl group. From the viewpoint of high activity and good curability, a trimethoxysilyl group, a triethoxysilyl group, a dimethoxymethylsilyl group, and a diethoxymethylsilyl group are preferable, and a dimethoxymethylsilyl group or a trimethoxysilyl group is more preferable.

<Polymer A>
The curable composition of the present invention contains a polymer A.
Polymer A has 3 or more main chain end groups in one molecule, and has an average of more than 0.5 reactive silicon groups represented by the above formula 1 per main chain end group. A polyoxyalkylene polymer having a branched structure.
The polymer A may be one type or two or more types.
The main chain in the polymer A is a polymer chain composed of an oxyalkylene polymer formed by polymerization of one or more alkylene oxide monomers. In the case of a copolymer chain formed by polymerization of two or more kinds of alkylene oxide monomers, these alkylene oxide monomers may form a block polymer or a random polymer. Good.
As a polymer chain composed of an oxyalkylene polymer, a polymer chain composed of an ethylene oxide monomer, a polymer chain composed of a propylene oxide monomer, a polymer chain composed of a butylene oxide monomer, a polymer chain composed of a tetramethylene oxide monomer, Examples thereof include a copolymer chain of an ethylene oxide monomer and a propylene oxide monomer, and a copolymer chain of a propylene oxide monomer and a butylene oxide monomer. A polymer chain composed of a propylene oxide monomer is particularly preferable.
From the viewpoint of the restorability of the cured product, the polymer A preferably has 3 to 8 main chain end groups, more preferably 3 to 6, and even more preferably 3 or 4.
The main chain terminal group of the polymer A is any one of the reactive silicon group, the active hydrogen-containing group or the unsaturated group represented by the above formula 1, and each of the terminal groups is the same as or different from each other. May be.
The polymer A preferably has an average of more than 0.5 and no more than 1.0 reactive silicon groups per one main chain end group, from the viewpoint of good tensile strength. What has 0.98 piece is more preferable.

The Mn of the polymer A is preferably 2,000 to 100,000, more preferably 3,000 to 50,000, and still more preferably 8,000 to 40,000. When it is at least the lower limit of the above range, the stretched physical properties of the cured product are easily excellent, and when it is at most the upper limit, the viscosity tends to be sufficiently low and the workability is easily excellent.
The molecular weight distribution of the polymer A is preferably 1.8 or less. From the viewpoint of viscosity reduction, the molecular weight distribution is preferably small, more preferably 1.5 or less, further preferably 1.4 or less, and particularly preferably 1.2 or less.

The polymer A is obtained by introducing more than 0.5 of the reactive silicon groups into one main chain terminal group on the main chain terminal group of the precursor polymer described later. Those obtained by introducing more than 0.5 and 1.0 or less are preferred, and those obtained by introducing 0.55 to 0.98 are more preferred from the viewpoint of good tensile strength.
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 precursor polymer is preferably a polymer in which an alkylene oxide monomer is subjected to ring-opening addition polymerization with an initiator having a hydroxyl group and the main chain terminal group is a hydroxyl group.
The production method of the polymer A is preferably 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.
Since the main chain of the polymer A is branched, the restorability of the cured product is excellent.
The initiator for obtaining the branched polymer A is preferably a compound having 3 or more active hydrogen-containing groups, more preferably a compound having 3 to 8 hydroxyl groups, and still more preferably a compound having 3 to 6 hydroxyl groups. Compounds having 3 or 4 are particularly preferred. The active hydrogen-containing group in the initiator is preferably a hydroxyl group.
One type of initiator may be used, or two or more types of compounds having three or more active hydrogen-containing groups may be used in combination. When two or more kinds of initiators are used in combination, the molar average of the number of active hydrogen-containing groups in those initiators may be three or more.
Examples of the initiator having 3 or more hydroxyl groups include glycerin, trimethylolpropane, pentaerythritol, sucrose, and sorbitol, and glycerin or trimethylolpropane is preferable from the viewpoint of improving the elongation property of the cured product.
The number of active hydrogens in the initiator, the number of main chain end groups in the precursor polymer, and the number of main chain end groups in polymer A are the same.

As the ring-opening polymerization catalyst for ring-opening addition polymerization of an alkylene oxide monomer as an initiator, a conventionally known catalyst can be used. For example, an alkali catalyst such as KOH, an organoaluminum compound and porphyrin are used. Examples include transition metal compound-porphyrin complex catalysts such as complexes obtained by reaction, double metal cyanide complex catalysts, and catalysts comprising phosphazene compounds.
A double metal cyanide complex catalyst is preferable because the molecular weight distribution of the polymer A can be narrowed and a curable composition having a low viscosity is easily obtained. As the composite metal cyanide complex catalyst, a conventionally known compound can be used, and a known method can be adopted as a method for producing a polymer using the composite metal cyanide complex. For example, International Publication No. 2003/066301, International Publication No. 2004/066763, Japanese Unexamined Patent Application Publication No. 2004-267976, Japanese Unexamined Patent Application Publication No. 2005-15786, International Publication No. 2013/0665802, Japanese Unexamined Patent Application Publication No. 2015-010162. The compounds and the production methods disclosed in Japanese Patent Publication No. Gazette can be used.
The precursor polymer of the polymer A is preferably a polymer in which all main chain terminal groups are hydroxyl groups.

The method for producing the polymer A is preferably 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.
Examples of the silylating agent include compounds having both a group capable of reacting with an unsaturated group to form a bond (for example, a sulfanyl group) and the reactive silicon group, a hydrosilane compound (for example, HSiX _a R _3-a , where X And R are the same as those in the above formula 1.). Specifically, for example, trimethoxysilane, triethoxysilane, triisopropoxysilane, tris (2-propenyloxy) silane, triacetoxysilane, dimethoxymethylsilane, diethoxymethylsilane, methoxyethylsilane, diisopropoxymethyl Examples include silane, (α-chloromethyl) dimethoxysilane, and (α-chloromethyl) diethoxysilane. From the viewpoint of high activity and good curability, trimethoxysilane, triethoxysilane, dimethoxymethylsilane, and diethoxymethylsilane are preferable, and dimethoxymethylsilane or trimethoxysilane is more preferable.
As a method for producing the polymer A, conventionally known methods can be used. For example, JP-B No. 45-36319, JP-A No. 50-156599, JP-A No. 61-197631, JP-A No. 3-72527, Examples thereof include methods proposed in JP-A-8-231707, US Pat. No. 3,632,557, and US Pat. No. 4,960,844.

The silylation rate of the polymer A is preferably more than 50 mol% and 100 mol% or less, more preferably 50 to 97 mol%, further preferably 52 to 95 mol%.
When a curable composition contains 2 or more types of polymers A, the average silylation rate in the whole polymer A should just be in said range.

<Polymer B>
The curable composition of the present invention contains a polymer B.
The polymer B has two main chain end groups in one molecule, and has an average of more than 0.5 reactive silicon groups represented by the following formula 1 per main chain end group. It is a polyoxyalkylene polymer having a linear structure.
The polymer B may be one type or two or more types.
The main chain in the polymer B is the same as the main chain in the polymer A, and the preferred embodiment is also the same.
The two main chain end groups in one molecule of the polymer B may be the same or different. Examples of the main chain terminal group in the polymer B include one or more groups selected from the group consisting of a reactive silicon group represented by the above formula 1, an active hydrogen-containing group, and an unsaturated group. As the active hydrogen-containing group, a hydroxyl group is preferable. As the unsaturated group, an allyl group is preferable.
The polymer B preferably has an average of more than 0.5 and no more than 1.0 reactive silicon groups per one main chain end group, from the viewpoint of good tensile strength. What has 0.98 piece is more preferable.
The Mn of the polymer B is preferably 2,000 to 100,000, more preferably 3,000 to 50,000, and still more preferably 4,000 to 30,000. When it is at least the lower limit of the above range, the stretched physical properties of the cured product are easily excellent, and when it is at most the upper limit, the viscosity tends to be sufficiently low and the workability is easily excellent.
The molecular weight distribution of the polymer B is preferably 1.8 or less. From the viewpoint of viscosity reduction, the molecular weight distribution is preferably small, more preferably 1.5 or less, further preferably 1.4 or less, and particularly preferably 1.2 or less.

Polymer B is obtained by introducing, on average, more than 0.5 reactive silicon groups into the main chain end groups of the precursor polymer into one main chain end group. Those obtained by introducing more than 0.5 and 1.0 or less are preferred, and those obtained by introducing 0.55 to 0.98 are more preferred from the viewpoint of good tensile strength.
Since the main chain of the polymer B is linear, it is excellent in the elongation property of the cured product. Therefore, a compound having two active hydrogen-containing groups is used as the initiator. As the compound having two active hydrogen-containing groups, a compound having two hydroxyl groups is preferable. One type of initiator may be used, or two or more types may be used in combination.
Examples of the compound 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, low molecular weight An example is polyoxypropylene glycol.
The precursor polymer of the polymer B can be produced in the same manner as the precursor polymer of the polymer A, except that a compound having two active hydrogen-containing groups is used as an initiator.
The polymer B can be produced in the same manner as the production method of the polymer A, except that the precursor polymer of the polymer B is used.
The silylation rate of the polymer B is preferably more than 50 mol% and 100 mol% or less, more preferably 51 to 97 mol%, and still more preferably 52 to 95 mol%.
When a curable composition contains 2 or more types of polymers B, the average silylation rate in the whole polymer B should just be in said range.

<Polymer C>
The curable composition of the present invention contains polymer C.
The polymer C is a vinyl polymer having one or more reactive silicon groups represented by the above formula 1 in one molecule.
The polymer C contained in the curable composition of the present invention may be one type or two or more types.
The reactive silicon group in the polymer C may be introduced into the main chain end group, may be introduced into the side chain, or may be introduced into both the main chain end group and the side chain.
The average number of reactive silicon groups per molecule of the polymer C is preferably 1.0 or more. From the point of strength after curing, 1.2 or more is preferable, and 1.6 or more is more preferable. 4.0 or less are preferable and 3.0 or less are more preferable from the point from which the elongation of hardened | cured material becomes favorable.
The average number of reactive silicon groups per molecule of the polymer C is calculated by “the concentration of the reactive silicon group in the polymer C [mol / g] × Mn of the polymer C”. The concentration [mol / g] of the reactive silicon group in the polymer C can be measured by NMR.
As the monomer constituting the main chain of the polymer C, for example, conventionally known single monomers described in JP-B-3-14068, JP-A-6-211922, and JP-A-11-130931 are disclosed. The body can be used.
As monomers containing reactive silicon groups and unsaturated groups to be copolymerized with the above monomers, 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 An example is-(triethoxysilyl) propyl. These may be used alone or in combination of two or more.
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 with respect to all monomers constituting the polymer C.

The polymer C can be polymerized by a conventionally known polymerization method described in JP-A-2006-257405, JP-A-2006-37076, JP-A-2008-45059, and the like. A conventionally well-known thing can be used also about auxiliary materials, such as an initiator required for superposition | polymerization, and reaction conditions, such as reaction temperature and reaction pressure, can also be selected suitably.
Examples of the polymerization method include a polymerization method using a radical polymerization initiator by solution polymerization, emulsion polymerization, suspension polymerization or bulk polymerization, and living radical polymerization. As the living radical polymerization method, a method using a cobalt porphyrin complex as shown in Journal of American Chemical Society (J. Am. Chem. Soc.), 1994, 116, 7943, Initiators are those using nitrooxide radicals as shown in Table 2003-500378, organic halides or sulfonyl halides as shown in JP-A-11-130931, and transition metals. Examples thereof include 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 C can also be used. Commercially available products include, for example, XMAP series (Kaneka product name), ARUFON US-6000 series (for example, US-6110, US-6120, etc., both of which are product names of Toa Gosei Co., Ltd.), Actflow NE series (for example, NE- 1000 and NE-3000, both of which are product names of Soken Chemical Co., Ltd.).

The Mn of the polymer C is preferably 10,000 to 100,000, more preferably 12,000 to 80,000, and further preferably 13,000 to 60,000. When it is at least the lower limit of the above range, the elongation properties and weather resistance of the cured product are likely to be excellent, and when it is at most the upper limit, workability is likely to be excellent.
The molecular weight distribution of the polymer C is preferably 4.0 or less, and more preferably 3.0 or less. It is easy to be excellent in workability | operativity as it is below the upper limit of the said range.

<Polymer D>
The curable composition of the present invention may contain a polymer D. The polymer D may be one type or two or more types. The polymer D acts as a reactive plasticizer and contributes to lowering the viscosity of the curable composition and improving the stain resistance of the paint.
Examples of the main chain of the polymer D are the same as those of the main chain of the polymer A.

The Mn of the polymer D is preferably 2,000 to 12,000, more preferably 2,200 to 10,000, and further preferably 2,500 to 9,000. If it is within the above range, the stretched product properties of the cured product are likely to be excellent, and the paint contamination property and bleeding out of the cured product are likely to be good.
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 1.6 or less, still more preferably 1.5 or less, and particularly preferably 1.4 or less.

The polymer D is a precursor polymer in which one main chain end group is an inactive monovalent organic group, and the average of the reactive silicon group is more than 0 per one main chain end group. It is obtained by introducing less than one piece.
The inactive 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 chain having 1 to 4 carbon atoms. Alternatively, a linear alkyl group is more preferable, and a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an n-butyl group, or a t-butyl group is particularly preferable.

The precursor polymer of the polymer D can be produced in the same manner as the precursor polymer of the polymer A or B except that an initiator having one active hydrogen-containing group is used. One type of initiator may be used, or two or more types 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 in which the main chain terminal group has one hydroxyl group.
The initiator having one hydroxyl group is preferably a monovalent 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 the polymer D, a conventionally known method can be used, and a method similar to that for the polymer A or B can be used.

The polymer D has two main chain end groups per molecule, and one main chain end group is one of the reactive silicon group, the active hydrogen-containing group, or the unsaturated group, and the other The main chain terminal group is preferably a residue obtained by removing one active hydrogen from an initiator (inactive monovalent organic group).
The silylation rate of the polymer D is preferably 45 mol% or more, more preferably 50 mol% or more, and further preferably 55 mol% or more.
When a curable composition contains 2 or more types of polymers D, the average silylation rate in the whole polymer D should just be in said range.

  When the curable composition contains the polymer D, the content of the polymer D is preferably 1 to 600 parts by mass with respect to 100 parts by mass in total of the polymer A, the polymer B, and the polymer C. 500 mass parts is more preferable, and 10-300 mass parts is further more preferable. When the content of the polymer D is within the above range, the viscosity tends to be low, the workability is easily excellent, and bleeding out hardly occurs in the cured product.

<Polymer E>
The curable composition of the present invention may contain one or more polymers having no reactive silicon group and having a Mn of 1,000 or more (hereinafter referred to as “polymer E”).
The polymer E contributes to reducing the contamination on the surface of the cured product, improving the drying property of the coating on the surface of the cured product, and reducing the contamination on the surface of the coating.
The polymer E is preferably at least one 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 a saturated hydrocarbon monomer, and examples thereof include polyethylene and polypropylene.
(Meth) acrylic acid ester polymers include methyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, lauryl (meth) acrylate, and stearyl (meth) acrylate. A monomeric polymer or copolymer can be exemplified. Examples of commercially available (meth) acrylic acid ester polymers include ARUFON UP-1000, ARUFON UP-1110, and ARUFON UP-1171 (all manufactured by Toa Gosei Co., Ltd.).
Examples of the oxyalkylene polymer include polyether polyols (for example, polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol), and derivatives obtained by sealing the hydroxyl groups of the polyether polyols to esters or ethers. Examples of commercially available oxyalkylene polymers include Preminol S3011, Preminol S4012, and Preminol S4013F (all Asahi Glass Co., Ltd. product names).

The Mn of the polymer E is preferably 1,000 to 40,000, more preferably 1,500 to 35,000, and still more preferably 2,000 to 30,000. When it is at least the lower limit of the above range, it is easy to prevent outflow due to heat and rain, and when it is at most the upper limit, the viscosity is low and workability is easy.
In the case of the (meth) acrylic acid ester polymer, the molecular weight distribution of the polymer E is preferably less than 6.0, more preferably 5.5 or less, and even more preferably 5.0 or less. In the case of an oxyalkylene polymer, less than 2.0 is preferable, 1.8 or less is more preferable, and 1.6 or less is more preferable.
When the curable composition contains the polymer E, the content of the polymer E is preferably 1 to 600 parts by mass with respect to 100 parts by mass in total of the polymer A, the polymer B, and the polymer C. 500 mass parts is more preferable, and 10-300 mass parts is further more preferable. When it is at least the lower limit of the above range, the surface contamination is liable to be lowered, and when it is at most the upper limit, the viscosity tends to be low, and the workability is easy.

<Curable composition>
A curable composition is obtained by mixing the polymer mix | blended with a curable composition, and other components mentioned later other than these polymers.
The ratio of the mass of the polymer A to the total mass of the polymer A and the polymer B in the curable composition is 0.5 to 1.0, preferably 0.55 to 0.9, 0 .6 to 0.8 is more preferable. If it is in the said range, the elongation physical property and restoration rate of hardened | cured material will become favorable.
The ratio of the mass of the polymer C to the total mass of the polymer A, the polymer B, and the polymer C in the curable composition is 0.1-0.6, 0.15-0. 55 is preferable, and 0.2 to 0.5 is more preferable. If it is in the said range, the elongation physical property and restoration rate of hardened | cured material will become favorable.
3-80 mass% is preferable, as for the total content rate of the said polymer A, B, and C in a curable composition, 5-60 mass% is more preferable, and 10-50 mass% is further more preferable. When it is at least the lower limit of the above range, it is easy to be excellent in elongation physical properties, and when it is at most the upper limit, the viscosity tends to be low, and the elongation physical properties and restoration rate of the cured product are likely to be excellent.
The specific gravity of the curable composition of the present invention is preferably 0.8 or more and 2.0 or less. More preferably, it is 0.8 or more and 1.6 or less, More preferably, it is 0.8 or more and 1.3 or less. If it is within the above range, a large amount of filler such as calcium carbonate can be filled, the strength of the cured product tends to be high, and the mass per volume is light, so that the sealing material does not easily drip when applied to a vertical joint.

  The curable composition may be a one-component type in which all the ingredients are pre-blended, hermetically stored, and cured by moisture in the air after construction, and at least a main ingredient composition containing a component having a reactive silicon group, and at least A two-component type in which a curing agent composition containing a curing catalyst is stored separately and the curing agent composition and the main agent composition are mixed before use may be used.

The one-component curable composition preferably does not contain moisture. It is preferable to dehydrate and dry the ingredients containing water in advance, or dehydrate them under reduced pressure during compounding.
In the two-component curable composition, the curing agent composition may contain water, and the main component composition hardly gels even if it contains a small amount of water, but from the viewpoint of storage stability, the blended components are dehydrated and dried in advance. It is preferable.
In order to improve the storage stability, a dehydrating agent may be added to the one-component curable composition or the two-component main agent composition.

[Other ingredients]
The curable composition may contain other components other than the polymers A to E. Examples of other components include a curable compound, a curing catalyst (silanol condensation catalyst), a filler, a plasticizer, a thixotropic agent, a stabilizer, an adhesion promoter, a physical property modifier, a tackifier resin, and a filler. Examples of reinforcing materials, surface modifiers, flame retardants, foaming agents, solvents, and silicates.
Other components include International Publication No. 2013/180203, International Publication No. 2014/192842, International Publication No. 2016/002907, Japanese Unexamined Patent Application Publication No. 2014-88481, Japanese Unexamined Patent Application Publication No. 2015-10162, Japanese Unexamined Patent Application Publication No. 2015, respectively. Conventionally known materials described in JP-A-105293, JP-A-2017-039728, JP-A-2017-214541 and the like can be used in combination without limitation.

[Mechanism of action]
The curable composition of the present invention can be obtained by combining polymers A, B and C at a specific ratio to obtain a cured product excellent in elastic resilience and elongation properties as shown in the examples described later. Therefore, the outer appearance of the sealing material for the outer wall that is exposed outdoors for a long period of time can be maintained well. This is because the polymer A, the polymer B, and the polymer C are combined at a specific ratio, in particular, the elastic recovery rate of the cured product is increased, and further, the stretched physical properties are improved. It is considered that the swelling and wrinkles on the surface of the sealing material generated in (5) are easy to return to the original, and the expansion of the generated swelling and wrinkles is suppressed.

[Industrial applicability]
Applications of the curable composition include sealing materials (for example, elastic sealing materials for construction, sealing materials for double-glazed glass, sealing materials for rust prevention and waterproofing of glass edges, solar cell back surface sealing materials, and sealing for buildings) Materials, sealing materials for ships, sealing materials for automobiles, sealing materials for roads), electrical insulating materials (insulating coating materials for electric wires and cables), and adhesives are suitable.
In particular, it is suitable for applications that require the elastic restoring properties and stretched physical properties of the cured product. For example, a sealing material applied outdoors can be exemplified.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to the following examples.

<Synthesis of Polymer A, Polymer B, Polymer C, and Polymer D>
[Molecular weight of precursor polymer]
The molecular weight of the polyoxyalkylene polymer (hereinafter referred to as “precursor polymer”) in which the main chain end group obtained by polymerizing alkylene oxide with the initiator is a hydroxyl group is determined from the hydroxyl value calculated based on JIS K1557. It was calculated based on the formula of “56100 / (hydroxyl value of precursor polymer) × number of active hydrogens of initiator” (hereinafter referred to as “hydroxyl equivalent molecular weight”).

[Mn and molecular weight distribution]
Mw and Mn were calculated | required using HLC-8220GPC (Tosoh Corporation product name), and Mw / Mn was calculated.

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

[Evaluation of tensile properties]
As an adherend, a surface anodized aluminum plate coated with primer MP-2000 (product name of Cemedine Co., Ltd.) is used as the adherend, and a durability test body in conformity with the test method for architectural sealing material of JIS A 1439 Form 1 was prepared and tested for tensile properties.
Specifically, the curable composition is poured into a space formed by sandwiching a spacer between the two aluminum plates, and cured for 7 days at a temperature of 23 ° C. and a humidity of 50%. It was cured at 50 ° C. and a humidity of 65% for 7 days to obtain a durability test specimen 1 type. The obtained durability test specimen 1 was subjected to a tensile property test with a Tensilon tester, and stress (hereinafter referred to as “M50”, unit: N / mm ² ) when stretched 50%, maximum point cohesive force ( Unit: N / mm ² ) and maximum point elongation (unit:%) were measured.
The smaller the M50 value is, the softer the cured product is. The larger the maximum point cohesion value is, the higher the tensile strength of the cured product is, and the larger the maximum point elongation value is, the better the cured product is.

[Evaluation of elastic resilience]
As an adherend, a surface anodized aluminum plate coated with primer MP-2000 (product name of Cemedine Co., Ltd.) is used as the adherend, and aluminum is used in accordance with the test method for architectural sealant of JIS A 1439 5.2. An adherend was prepared and evaluated for elastic resilience.
Specifically, as in the evaluation of the tensile properties, the curable composition is poured between the two aluminum plates, cured at a temperature of 23 ° C. and a humidity of 50% for 7 days, and further at a temperature of 50 ° C. and a humidity of 65%. After curing for 7 days, an aluminum adherend was obtained. The distance of the obtained aluminum adherend two aluminum plates was L _0. Using a predetermined jig, the distance between the two aluminum plates was extended by 100% with respect to L ₀ in an environment of a temperature of 23 ° C. and a humidity of 50%. The distance of two aluminum plates at this time is set as L _1. After the distance of two aluminum plates were kept for 24 hours while the L _1, the jig removed, allowed to stand 1 hour, the distance of two aluminum plates was measured as L _2. From the values of the above L ₀ , L ₁ and L ₂ , the elastic recovery rate (unit:%) was determined by the following formula 2. The higher the elastic recovery rate, the better the elastic recovery.
Elastic recovery rate = (L ₁ −L ₂ / L ₁ −L ₀ ) × 100 Equation 2

[Paint contamination]
On the aluminum plate, the curable composition was applied in a shape of 50 mm in length, 50 mm in width, and 10 mm in thickness, and cured at 23 ° C. and 50% humidity for 48 hours to obtain a cured product. A silicone resin paint (Ares Aqua Silicon AC II, product name of Kansai Paint Co., Ltd.) was applied on the cured product. After curing at 50 ° C. for 1 week, it was allowed to stand for 1 day under the conditions of 23 ° C. and humidity 50%. Next, a well-dried contaminated powder (Kanto Loam, manufactured by Japan Powder Industrial Technology Association) was sprinkled on the entire surface coated with the paint, allowed to stand for 10 minutes, and then the contaminated powder was screened off. The presence or absence of contaminated powder was visually confirmed. When there is no adhesion of contaminated powder, the paint contamination is good.

(Synthesis Example 1: Polymer A1)
Propylene oxide was polymerized using glycerin as an initiator and a zinc hexacyanocobaltate complex (hereinafter referred to as “TBA-DMC catalyst”) having a ligand of t-butyl alcohol as a catalyst to obtain polyoxypropylene. . Polyoxypropylene obtained a precursor polymer a1 having a hydroxyl group at the terminal and having a hydroxyl equivalent molecular weight of 22,000. Subsequently, 1.05 molar equivalent of a methyl alcohol solution of sodium methoxide with respect to the hydroxyl group of the precursor polymer a1 was added to alcoholate the precursor polymer a1. Next, methyl alcohol was distilled off by heating under reduced pressure, and an excessive amount of allyl chloride was added to the amount of hydroxyl groups in the precursor polymer a1 to convert the end groups of the main chain into allyl groups. Next, in the presence of chloroplatinic acid hexahydrate, 0.55 molar equivalent of dimethoxymethylsilane is added as a silylating agent to the converted allyl group of the precursor polymer a1, and the mixture is added at 70 ° C. for 5 hours. An oxypropylene polymer (polymer A1) in which a dimethoxymethylsilyl group was introduced as a reactive silicon group into the main chain end group was obtained.
Table 1 shows Mn, Mw / Mn, and silylation rate of the obtained polymer A1. The same applies to the polymers obtained in Synthesis Examples 2, 3 and 6 below.

(Synthesis Example 2: Polymer B1)
Propylene glycol was used as an initiator and propylene oxide was polymerized in the presence of a TBA-DMC catalyst in the same manner as in Synthesis Example 1 to obtain a precursor polymer b1 having a hydroxyl equivalent molecular weight of 10,000. Next, 0.55 molar equivalent of dimethoxymethylsilane was added as a silylating agent to the allyl group of the precursor polymer b1 obtained in the same manner as in Synthesis Example 1 and having a terminal group converted to an allyl group. An oxypropylene polymer (polymer B1) in which a dimethoxymethylsilyl group was introduced into the main chain terminal group as a functional silicon group was obtained.

(Synthesis Example 3: Polymer B2)
In the same procedure as in Synthesis Example 2, the amount of propylene oxide to be polymerized was adjusted to obtain a precursor polymer b2 having a hydroxyl equivalent molecular weight of 18,000. The same procedure as in Synthesis Example 1 was repeated except that 0.73 moles of dimethoxymethylsilane was reacted with the allyl group of the precursor polymer b2 in which the hydroxyl group was converted to an allyl group. An oxypropylene polymer (polymer B2) having a group introduced into the main chain end group was obtained.

(Synthesis Example 4: Polymer C1)
100 g of methyl methacrylate, 750 g of butyl acrylate, 150 g of stearyl methacrylate, 26.7 g of γ-methacryloxypropylmethyldimethoxysilane, 7.5 g of dodecyl mercaptan and 2,2′-azobis-2-methylbutyronitrile (V65) , Wako Pure Chemical Industries, Ltd. product name) was added dropwise to 300 g of ethyl acetate heated to 70 ° C. over 2 hours and polymerized for 2 hours to obtain a (meth) acrylic acid ester polymer (heavy Combined C1) was obtained. Table 1 shows the average number of reactive silicon groups per molecule (hereinafter referred to as “the number of silyl groups”) obtained by Mn, Mw / Mn, and ¹ H-NMR analysis of the obtained polymer C1. The same applies to the polymer obtained in Synthesis Example 5 below.

(Synthesis Example 5: Polymer C2)
A (meth) acrylic acid ester polymer (polymer C2) having a conversion rate of about 98% was prepared in the same manner as in Synthesis Example 4 except that 4.0 g of dodecyl mercaptan was added. Obtained.

(Synthesis Example 6: Polymer D1)
A precursor polymer d1 having a hydroxyl equivalent molecular weight of 5,000 was obtained in the same procedure as in Synthesis Example 1 except that n-butyl alcohol was used as an initiator. The same procedure as in Synthesis Example 1 was repeated except that 0.78 moles of dimethoxymethylsilane was reacted with the allyl group of the precursor polymer d1 in which the hydroxyl group was converted to an allyl group. An oxypropylene polymer (polymer D1) in which a group was introduced into one main chain end group was obtained. Table 1 shows Mn, Mw / Mn and silylation rate of the obtained polymer D1.

<Other ingredients>
The polymers F and additives listed in Table 2 are as follows.
Whiteon SB: Heavy calcium carbonate, product name of Shiroishi Kogyo Co., Ltd.
CCR: Colloidal calcium carbonate, white glazed CCR, product name of Shiroishi Kogyo Co., Ltd. R-820: titanium oxide, product name of Ishihara Sangyo Co., Ltd. Balloon 80GCA: Organic balloon, product name of Matsumoto Yushi Co., Ltd.
UP-1110: ARUFON UP-1110, acrylic polymer with Mn = 1,500, product name of Toa Gosei Co., Ltd.
EL3020: Exenol 3020, a polyoxyalkylene polymer having two hydroxyl groups per molecule and a molecular weight in terms of hydroxyl group of 2000, product name of Asahi Glass Co., Ltd.
N-12D: Cactus normal paraffin N-12D, n-dodecane, purity 98.0%, manufactured by JXTG Energy.
Sunsizer EPS: 4,5-epoxycyclohexane-1,2-dicarboxylic acid-di-2-ethylhexyl, a product name of Shin Nippon Rika Co., Ltd.
IRGANOX 1135: hindered phenol antioxidant, product name of BASF.
TINUVIN326: Benzotriazole ultraviolet absorber, product name of BASF Corporation.
TINUVIN765: tertiary amine-containing hindered amine light stabilizer, product name of BASF Corporation.
LA-63P: ADK STAB LA-63P, a product name of ADEKA.
KBM-1003: Vinyltrimethoxysilane, product name of Shin-Etsu Chemical Co., Ltd.
KBM-403: 3-glycidyloxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. product name.
KBM-603: 3- (2-aminoethylamino) propyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. product name.
Laurylamine: Reagent, manufactured by Pure Chemicals.
Farmin CS: Coconutamine, Kao Corporation product name.
Tung Oil: Air oxidation curable compound, manufactured by Kimura Corporation.
M-309: Aronix M-309, product name of Toa Gosei Co., Ltd.
U-220H: Tin catalyst, product name of Nitto Kasei Co., Ltd.

<Adjustment of curable composition>
Examples 1 to 8 and Examples 14 to 18 are examples, and examples 9 to 13 are comparative examples.

(Example 1 to Example 13)
Polymers having reactive silicon having the formulations shown in Tables 3 to 4 and additives having the compounding amounts shown in Table 2 were added to prepare curable compositions.
The obtained curable composition was subjected to a tensile property test and an elastic resilience test. The results are shown in Tables 3-4.
The cured product obtained in Example 1 was evaluated for paint contamination. The contaminated powder did not adhere to the surface of the cured product, and the paint contamination was good.

(Example 14)
In the formulation shown in Example 1 of Table 3, the polymer D is not used, the additive formulation is changed from Additive 1 shown in Table 2 to Additive 2, and a curable composition is prepared and cured in the same manner as above. I got a thing. The curable composition of Example 14 cured well. The elastic recovery rate was as good as in Example 1. On the other hand, the paint contamination on the surface of the obtained cured product was different from the surface of the cured product obtained in Example 1, and contaminated powder adhered to the surface of the cured product.

(Examples 15 to 18)
In the formulation shown in Example 1 of Table 3, the additive formulation was changed from Additive 1 shown in Table 2 to Additives 3 to 6 to prepare curable compositions, and cured products were obtained in the same manner as described above. . The curable compositions of Examples 15 to 18 were cured well and the elastic recovery rate was good.

  As shown in Tables 3 to 4, Examples 1 to 8 are considered to be less likely to cause poor appearance due to swelling or wrinkles of the cured product because the elastic recovery rate is high and the elongation property is good. In Example 9 or Example 10, in which the polymer A was not contained or the ratio of the mass of the polymer A to the total mass of the polymer A and the polymer B was small, the elastic recovery rate was low. From this, it is considered that these cured products are likely to have poor appearance due to swelling or the like. Further, in Examples 11 to 13 in which the ratio of the polymer C is large with respect to the total mass of the polymer A, the polymer B, and the polymer C, the recovery rate is poor because the test body was broken during the test. It was clear and the elongation physical properties were also poor.

Claims (5)

It has a branched structure having 3 or more main chain end groups in one molecule and having an average of more than 0.5 reactive silicon groups represented by the following formula 1 per main chain end group A polyoxyalkylene polymer A;
It has a linear structure having two main chain end groups in one molecule and having an average of more than 0.5 reactive silicon groups represented by the following formula 1 per main chain end group Polymer B;
Having at least one vinyl polymer C having a reactive silicon group represented by the following formula 1 in one molecule;
The ratio of the mass of the polymer A to the total mass of the polymer A and the polymer B is 0.5 to 1.0,
And the ratio of the mass of the polymer C with respect to the total mass of the said polymer A, the said polymer B, and the said polymer C is 0.1-0.6.
-SiX _a R _3-a Formula 1
[Wherein, R represents a monovalent organic group having 1 to 20 carbon atoms, and represents an organic group other than a hydrolyzable group, X represents a hydroxyl group or a hydrolyzable group, and a represents an integer of 1 to 3] And when a is 1, R may be the same or different from each other, and when a is 2 or 3, X may be the same or different from each other. ]   The curable composition of Claim 1 whose said polymer C is a polymer containing the repeating unit of a (meth) acrylic acid ester monomer.   One molecule has two main chain end groups, one main chain end group is an inactive monovalent organic group, and the reactive silicon group represented by the above formula 1 has one main chain end group. The curable composition according to claim 1 or 2, further comprising a linear oxyalkylene polymer having an average of 0.5 or less per group.   The curable composition according to any one of claims 1 to 3, which is for a sealing material.   Hardened | cured material formed by hardening | curing the curable composition as described in any one of Claims 1-4.