DE112023002011T5 - CURRENT COMPOSITION AND CURED PRODUCT - Google Patents

Abstract

There are provided a curable composition comprising a polymer having a reactive silicon group, the curable composition giving a cured product having both excellent strength properties and excellent weather resistance, and a cured product thereof. The curable composition of the present invention comprises a polyether-polycarbonate polymer (A) comprising a carbon dioxide-based unit and an alkylene oxide-based unit, having an average of 1 or less predetermined reactive silicon group(s) per molecule, and having a number average molecular weight (Mn) of 2,000 to 50,000, and an oxyalkylene polymer (B) having two or more terminal groups and a predetermined reactive silicon group.

Description

technical field

The present invention relates to a curable composition comprising a polymer having a reactive silicon group and suitable for sealants, adhesives and the like, and a cured product thereof.

State of the art

Polymers having a reactive silicon group are widely used in applications such as sealants, adhesives and the like because they become a flexible, rubbery cured product through siloxane bonds formed by a hydrolysis reaction of reactive silicon groups and a condensation reaction.

For example, PTL1 describes that a cured product of a composition comprising a polymer having a reactive silicon group at both ends and a polymer having a reactive silicon group at one end has good flexibility, elongation and durability.

PTL2 describes that a cured product made of a polyether-polycarbonate polymer with a reactive silicon group has good strength and elongation.

document list

patent documents

• PTL1: JP 2011-178955 A
• PTL2: JP 2021-59722 A

Summary of the Invention

Technical problem

The polymer constituting the curable composition described in PTL1 is a polyoxyalkylene polymer without a carbonate group, and the polymer cannot be expected to have good strength and weather resistance.

The polyether-polycarbonate polymer having one reactive silicon group specifically described in PTL2 is merely a polymer having two reactive silicon groups, and therefore it can hardly be expected that such a polyether-polycarbonate polymer is highly viscous and has excellent handling.

The present invention has been made in view of this situation, and an object of the present invention is to provide a curable composition comprising a polymer having a reactive silicon group, the curable composition giving a cured product having both excellent strength properties and excellent weather resistance, and a cured product thereof.

solution to the problem

The present invention is based on the discovery that in a curable composition comprising a polymer having a reactive silicon group, the use of a given monofunctional polyether-polycarbonate polymer having an average of 1 or less reactive silicon group(s) per molecule in combination with a multifunctional polyoxyalkylene polymer having a reactive silicon group can yield a cured product having good strength properties and excellent weather resistance.

1. [1] Aushärtbare Zusammensetzung, umfassend:
   • ein Polyether-Polycarbonat-Polymer (A), das eine Einheit auf der Basis von Kohlendioxid und eine Einheit auf der Basis eines Alkylenoxids umfasst, durchschnittlich 1 oder weniger reaktive Siliziumgruppe(n), die durch die folgende Formel (1) dargestellt ist/sind, pro Molekül aufweist und ein Zahlenmittel des Molekulargewichts (Mn) von 2000 bis 50000 aufweist; und
   • ein Oxyalkylenpolymer (B) mit zwei oder mehr Endgruppen und einer reaktiven Siliziumgruppe, die durch die folgende Formel (1) dargestellt ist: -SiX_aR_3-a (1) wobei
     • X ein Halogenatom, eine Hydroxylgruppe oder eine hydrolysierbare Gruppe ist;
     • R eine einwertige organische Gruppe mit 1 bis 20 Kohlenstoffatomen ist und keine hydrolysierbare Gruppe umfasst; und
     • a eine ganze Zahl von 1 bis 3 ist, und wenn a 1 ist, zwei R identisch oder voneinander verschieden sein können, und wenn a 2 oder 3 ist, eine Mehrzahl von X identisch oder voneinander verschieden sein kann.
2. [2] Aushärtbare Zusammensetzung nach [1], wobei die Einheit auf der Basis eines Alkylenoxids des Polyether-Polycarbonat-Polymers (A) eine Einheit auf der Basis von Propylenoxid umfasst.
3. [3] Aushärtbare Zusammensetzung nach [1] oder [2], wobei ein Gehalt der Einheit auf der Basis von Kohlendioxid des Polyether-Polycarbonat-Polymers (A) 10 bis 30 Massen-% auf der Basis von 100 Massen-% einer Gesamtmenge der Einheit auf der Basis von Kohlendioxid und der Einheit auf der Basis eines Alkylenoxids beträgt.
4. [4] Aushärtbare Zusammensetzung nach einem von [1] bis [3], wobei das Polyether-Polycarbonat-Polymer (A) durchschnittlich mehr als 0,5 der reaktiven Siliziumgruppen pro Molekül aufweist.
5. [5] Aushärtbare Zusammensetzung nach einem von [1] bis [4], wobei ein Verhältnis (Mw/Mn) des Gewichtsmittels des Molekulargewichts (Mw) zu dem Zahlenmittel des Molekulargewichts (Mn) des Polyether-Polycarbonat-Polymers (A) von 1,0 bis 3,0 beträgt.
6. [6] Aushärtbare Zusammensetzung nach einem von [1] bis [5], wobei ein Zahlenmittel des Molekulargewichts (Mn) des Oxyalkylenpolymers (B) 10000 bis 50000 beträgt.
7. [7] Aushärtbare Zusammensetzung nach einem von [1] bis [6], wobei ein Gehalt des Polyether-Polycarbonat-Polymers (A) 5 bis 100 Massenteile bezogen auf 100 Massenteile des Oxyalkylenpolymers (B) beträgt.
8. [8] Aushärtbare Zusammensetzung nach einem von [1] bis [7], die ferner einen Aushärtungskatalysator umfasst.
9. [9] Ausgehärtetes Produkt der aushärtbaren Zusammensetzung nach einem von [1] bis [8].

The present invention provides the following objects:

1. [1] A curable composition comprising:
   • a polyether-polycarbonate polymer (A) comprising a carbon dioxide-based unit and an alkylene oxide-based unit, having an average of 1 or less reactive silicon group(s) represented by the following formula (1) per molecule and having a number average molecular weight (Mn) of 2,000 to 50,000; and
   • an oxyalkylene polymer (B) having two or more terminal groups and a reactive silicon group represented by the following formula (1): -SiX _a R _3-a (1) where
     • X is a halogen atom, a hydroxyl group or a hydrolyzable group;
     • R is a monovalent organic group having 1 to 20 carbon atoms and does not comprise a hydrolyzable group; and
     • a is an integer from 1 to 3, and when a is 1, two R's may be identical or different, and when a is 2 or 3, a plurality of X's may be identical or different.
2. [2] The curable composition according to [1], wherein the alkylene oxide-based unit of the polyether-polycarbonate polymer (A) comprises a propylene oxide-based unit.
3. [3] The curable composition according to [1] or [2], wherein a content of the carbon dioxide-based unit of the polyether-polycarbonate polymer (A) is 10 to 30 mass% based on 100 mass% of a total amount of the carbon dioxide-based unit and the alkylene oxide-based unit.
4. [4] The curable composition according to any one of [1] to [3], wherein the polyether-polycarbonate polymer (A) has on average more than 0.5 of the reactive silicon groups per molecule.
5. [5] The curable composition according to any one of [1] to [4], wherein a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyether-polycarbonate polymer (A) is from 1.0 to 3.0.
6. [6] The curable composition according to any one of [1] to [5], wherein a number average molecular weight (Mn) of the oxyalkylene polymer (B) is 10,000 to 50,000.
7. [7] The curable composition according to any one of [1] to [6], wherein a content of the polyether-polycarbonate polymer (A) is 5 to 100 parts by mass based on 100 parts by mass of the oxyalkylene polymer (B).
8. [8] The curable composition according to any one of [1] to [7], further comprising a curing catalyst.
9. [9] Cured product of the curable composition according to any one of [1] to [8].

Advantageous effects of the invention

According to the present invention, there can be provided a curable composition comprising a polymer having a reactive silicon group, the curable composition giving a cured product having both excellent strength properties and excellent weather resistance.

The curable composition of the present invention is useful in sealant and adhesive applications.

Description of embodiments

The definitions and meanings of the terms and expressions used herein are as follows.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) are polystyrene equivalent molecular weights obtained by measurement by gel permeation chromatography (GPC) using a calibration curve prepared using a polystyrene standard sample.

The terminal group in the polyether-polycarbonate polymer includes not only a functional group at the end of a main chain of the polymer but also a functional group at the end of a branched chain equivalent to the main chain.

The main chain in the oxyalkylene polymer comprises a residue of an initiator and a repeating unit based on an alkylene oxide monomer (polyoxyalkylene chain). The end group in the oxyalkylene polymer refers to a terminal functional group based on the oxygen atom closest to the molecular end of the oxygen atoms in the polyoxyalkylene chain. "(Meth)acrylic" is a generic term for acrylic and methacrylic.

• X ein Halogenatom, eine Hydroxylgruppe oder eine hydrolysierbare Gruppe ist;
• R eine einwertige organische Gruppe mit 1 bis 20 Kohlenstoffatomen ist und keine hydrolysierbare Gruppe umfasst; und
• a eine ganze Zahl von 1 bis 3 ist, und wenn a 1 ist, zwei R identisch oder voneinander verschieden sein können, und wenn a 2 oder 3 ist, eine Mehrzahl von X identisch oder voneinander verschieden sein kann.

The curable composition of the present invention comprises a polyether-polycarbonate polymer (A) comprising a carbon dioxide-based unit and an alkylene oxide-based unit, having an average of 1 or less reactive silicon group(s) represented by the following formula (1) per molecule, and having a number average molecular weight (Mn) of 2,000 to 50,000; and an oxyalkylene polymer (B) having two or more terminal groups and a reactive silicon group represented by the following formula (1): -SiX _a R _3-a (1) where

• X is a halogen atom, a hydroxyl group or a hydrolyzable group;
• R is a monovalent organic group having 1 to 20 carbon atoms and does not comprise a hydrolyzable group; and
• a is an integer from 1 to 3, and when a is 1, two R's may be identical or different, and when a is 2 or 3, a plurality of X's may be identical or different.

According to the curable composition comprising the polyether-polycarbonate polymer (A) in combination with the oxyalkylene polymer (B) as described above, a cured product in which both excellent strength properties and excellent weather resistance are combined can be obtained.

[Polyether-polycarbonate polymer (A)]

The polyether-polycarbonate polymer (A) comprises a carbon dioxide-based unit and an alkylene oxide-based unit, has an average of 1 or less reactive silicon group(s) represented by the formula (1) per molecule, and has an Mn of 2,000 to 50,000.

One polyether-polycarbonate polymer (A) may be used alone, or two or more polyether-polycarbonate polymers (A) may be used in combination.

Examples of the alkylene oxide of the alkylene oxide-based unit include ethylene oxide, propylene oxide, butylene oxide and tetramethylene oxide in view of easy availability and the like. An alkylene oxide may be used alone, or two or more alkylene oxides may be used in combination. The alkylene oxide-based unit preferably comprises a propylene oxide-based unit in view of compatibility between the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B), easy handling of the curable composition, good strength properties of a cured product of the curable composition and the like.

The carbon dioxide-based unit forms a carbonate group. The cured product of the curable composition has excellent weather resistance because the polyether-polycarbonate polymer (A) has a carbonate group comprising the carbon dioxide-based unit.

The content of the carbon dioxide-based unit in the polyether-polycarbonate polymer (A) is preferably 10 to 30 mass%, more preferably 10 to 25 mass%, and even more preferably 10 to 20 mass%, in view of good strength properties and weather resistance of a cured product of the curable composition, moderate flexibility and the like. based on 100% by mass of a total amount of the carbon dioxide-based unit and the alkylene oxide-based unit.

The content of the carbon dioxide-based unit in the polyether-polycarbonate polymer (A) can be determined from a nuclear magnetic resonance (NMR) analysis, particularly by the method described in Examples described later.

(Reactive silicon group)

The reactive silicon group represented by formula (1) is a crosslinking site of the polyether-polycarbonate polymer (A) and can form a crosslinked structure through a siloxane bond.

In the formula (1), X is a halogen atom, a hydroxyl group or a hydrolyzable group. The hydrolyzable group is a group capable of forming a silanol group (-Si-OH) by hydrolysis, and examples include an alkoxy group, an acyloxy group, a ketoxymate group, an amino group, an amide group, an acid amide group, an aminooxy group, a sulfanyl group and an alkenyloxy group. The number of carbon atoms of the alkyl group or alkenyl group capable of being included in the hydrolyzable group is preferably 1 to 6, and more preferably 1 to 3.

X is preferably an alkoxy group, more preferably an alkoxy group having 1 to 3 carbon atoms, and even more preferably a methoxy group, an ethoxy group or an isopropoxy group from the viewpoint of mild hydrolysis. A methoxy group or an ethoxy group is particularly preferred from the viewpoint of promoting curing by forming crosslinked structures through siloxane bonds.

R is a monovalent organic group having 1 to 20 carbon atoms and does not include a hydrolyzable group. Examples of the organic group include a hydrocarbon group, a halohydrocarbon group and a triorganosiloxy group, and the number of carbon atoms of the organic group is preferably 1 to 6, and more preferably 1 to 3.

R is preferably an alkyl group, a cycloalkyl group, an aryl group, a 1-chloroalkyl group or a triorganosiloxy group, more preferably a straight or branched alkyl group having 1 to 4 carbon atoms, a cyclohexyl group, a phenyl group, a benzyl group, a 1-chloroalkyl group, a trimethylsiloxy group, a triethylsiloxy group or a triphenylsiloxy group, and still more preferably an alkyl group having 1 to 3 carbon atoms or a 1-chloroalkyl group having 1 to 3 carbon atoms. Of these, a methyl group or an ethyl group is preferred in view of good curability of the polymer having a reactive silicon group and good stability of the curable composition, a 1-chloromethyl group is preferred in view of moderate curing speed of the curable composition, and a methyl group is preferred in view of easy availability.

a is an integer from 1 to 3. If a is 1, two R's may be identical or different. If a is 2 or 3, a plurality of X's may be identical or different.
a is preferably 2 or 3, more preferably 2.

Examples of the reactive silicon group represented by the formula (1) include a trimethoxysilyl group, a triethoxysilyl group, a triisopropoxysilyl group, a tris(2-propenyloxy)silyl group, a triacetoxysilyl group, a dimethoxymethylsilyl group, a diethoxymethylsilyl group, a dimethoxyethylsilyl group, a diisopropoxymethylsilyl group, a chloromethyldimethoxysilyl group, and a chloromethyldiethoxysilyl group. Of these, a trimethoxysilyl group, a triethoxysilyl group, a dimethoxymethylsilyl group, or a diethoxymethylsilyl group is preferred, a dimethoxymethylsilyl group or a trimethoxysilyl group is more preferred, and a dimethoxymethylsilyl group is even more preferred in view of good curability of the curable composition.

The number of reactive silicon groups represented by the formula (1) of the polyether-polycarbonate polymer (A) is on average 1 or less per molecule, preferably more than 0.5 and 1 or less, and more preferably 0.8 or more and 0.97 or less, in view of good elongation and good weather resistance of a cured product of the curable composition.

The average number of reactive silicon groups per molecule can be determined based on the average number per molecule of a functional group into which a reactive silicon group can be introduced from the terminal groups of the precursor into which the reactive silicon group is introduced. Specifically, the average number of reactive silicon groups per molecule can be determined by the method described in Examples.

The polyether-polycarbonate polymer (A) has, for example, an unsaturated group, an active hydrogen-containing group, an isocyanate group or an alkyl group as a terminal group other than the reactive silicon group represented by the formula (1).

Examples of the unsaturated group include a vinyl group (CH ₂ =CH-) and an ethynyl group (CH=C-). More specific examples include an allyl group (CH ₂ =CH-CH ₂ -), an acryloyl group (CH ₂ =CH-C(=O)-), a methacryloyl group (CH ₂ =C(CH ₃ )-C(=O)-), a methallyl group (CH ₂ =C(CH ₃ )-CH ₂ -), and a propargyl group (CH=C-CH ₂ -).

Examples of the active hydrogen-containing group include a hydroxyl group, a carboxyl group, an amino group, a monovalent functional group in which a hydrogen atom is removed from a primary amine, a hydrazide group, and a mercapto group.

Although the polyether-polycarbonate polymer (A) may have a reactive silicon group other than those represented by the formula (1), it is preferable that the reactive silicon groups of the polyether-polycarbonate polymer (A) are only those represented by the formula (1) in view of good crosslinking reactivity of the curable composition and good strength properties of a cured product of the curable composition.

(molecular weight)

The Mn of the polyether-polycarbonate polymer (A) is 2000 to 50000, preferably 5000 to 30000, and more preferably 6000 to 25000.

When the Mn is larger than or equal to the lower limit, the elongation and weather resistance of a cured product of the curable composition become good, and when it is smaller than or equal to the upper limit, the viscosity tends to be low and the handling properties during processing such as mixing of the curable composition become good.

The molecular weight distribution Mw/Mn of the polyether-polycarbonate polymer (A) is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, even more preferably 1.0 to 2.0, and even more preferably 1.4 to 2.0, from the viewpoint of making the viscosity of the curable composition low and the handling easy.

Mn and Mw/Mn of the polyether-polycarbonate polymer (A) can be adjusted by the kind of catalyst and polymerization conditions (temperature, stirring conditions, pressure and the like).

When two or more polyether-polycarbonate polymers (A) are used, Mn and Mw/Mn described above are preferably applied to each of the two or more polyether-polycarbonate polymers (A).

The same applies to the oxyalkylene polymer (B) described later.

(manufacturing process)

The polyether-polycarbonate polymer (A) can be produced, for example, by a method of reacting a silylating agent with a precursor polymer (A') comprising a carbon dioxide-based unit and an alkylene oxide-based unit and having a terminal group into which a reactive silicon group can be introduced.

The method for producing the precursor polymer (A') is not particularly limited, and examples include a method of obtaining the precursor polymer (A') by reacting alkylene oxide and carbon dioxide in the presence of a catalyst using a polyoxyalkylene monool and an ini itiators having an active hydrogen-containing group other than these for conducting a ring-opening addition polymerization. Examples of the initiator having an active hydrogen-containing group include methanol, ethanol, n-propanol and n-butanol.

Preferred examples of the process for producing the precursor polymer (A') include a process of obtaining the precursor polymer (A') by reacting an alkylene oxide and carbon dioxide in the presence of a catalyst with an initiator having an unsaturated group at the terminal and an active hydrogen-containing group to conduct ring-opening addition polymerization.

According to this method, a precursor polymer (A') having a polycarbonate chain consisting of an alkylene oxide-based unit and a carbon dioxide-based unit and a polyoxyalkylene chain consisting of an alkylene oxide-based unit and having an unsaturated group at the terminal is obtained. For example, when the active hydrogen-containing group is a hydroxyl group, a precursor polymer (A') having a hydroxyl group is obtained. Further, when the unsaturated group is an allyl group, a precursor polymer (A') having an allyl group is obtained.

According to this method, a main chain structure in which a carbon dioxide-based unit and an alkylene oxide-based unit are randomly arranged can be easily formed. It is believed that a polyether-polycarbonate polymer (A) obtained from a precursor polymer (A') having such a randomly arranged main chain structure can contribute to an improvement in strength properties and weather resistance of a cured product of the curable composition.

Examples of the active hydrogen-containing group and the unsaturated group at the terminal of the initiator include those identical to the active hydrogen-containing group and the unsaturated group described above.

The active hydrogen-containing group of the initiator is preferably a hydroxyl group, an amino group or a monovalent functional group in which a hydrogen atom bonded to a nitrogen atom of a primary amine is removed, and more preferably a hydroxyl group in view of easy introduction of a reactive silicon group into a polymer. The unsaturated group at the terminal is preferably an allyl group (CH ₂ =CH-CH ₂ -), an acryloyl group (CH ₂ =CH-C(=O)-), a methacryloyl group (CH ₂ =C(CH ₃ )-C(=O)-), a methacrylic group (CH ₂ =C(CH ₃ )-CH ₂ -) or a propargyl group (CH≡C-CH ₂ -), and more preferably an allyl group in view of easy introduction of a reactive silicon group into a polymer.

The initiator preferably has an allyl group at the terminal and a hydroxyl group. Examples of such an initiator include an allylated polyether such as allylated polyoxyalkylene, and a low molecular weight allylated polyoxypropylene having a hydroxyl group value of 50 mg KOH/g or more is preferred.

The catalyst for the ring-opening addition polymerization may be a known catalyst, and examples thereof include metal cyanide composite complex catalysts; alkali catalysts such as sodium hydroxide, potassium hydroxide and cesium hydroxide; Ziegler-Natta catalysts consisting of organic aluminum compounds and transition metal compounds; metal-porphyrin catalysts as complexes obtained by reacting porphyrin; phosphazene catalysts; imino group-containing phosphazenium salts; tris(pentafluorophenyl)borane; catalysts consisting of metal-salen complexes; and catalysts consisting of reduced Robson type macrocyclic ligands. One catalyst may be used alone, or two or more catalysts may be used in combination. Of these, metal cyanide composite complex catalysts are preferred because polymers having a relatively narrow molecular weight distribution can be easily obtained.

Examples of the metal cyanide composite complex catalyst include hexacyanocobaltate complexes of potassium or zinc having an alcohol such as tert-butanol or an ether such as ethylene glycol dimethyl ether (glyme) or diethylene glycol dimethyl ether (diglyme) as a ligand. The ring-opening addition polymerization using the metal cyanide composite complex catalyst can be carried out in a known manner. For example, the methods in which the metal cyanide composite complex catalyst described in WO 2003/062301 , WO 2004/067633 , JP 2004-269776 A , JP 2005-15786 A , WO 2013/065802 , JP 2015-10162 A disclosed catalyst is used, and the like.

Examples of the alkylene oxide subjected to ring-opening addition polymerization include ethylene oxide, propylene oxide, butylene oxide and tetramethylene oxide, and it is preferable that the alkylene oxide includes propylene oxide in view of ease of production, good strength properties of a cured product of the curable composition and the like.

The method of reacting a silylating agent with a precursor polymer (A') may be a known method. Examples thereof include a method (method 1) of reacting a precursor polymer (A') having an unsaturated group at the terminal with a silylating agent capable of undergoing an addition reaction with the unsaturated group, a method (method 2) of subjecting a precursor polymer (A') having an active hydrogen-containing group to a urethanization reaction using a silylating agent having an isocyanate group, and a method (method 3) of introducing an isocyanate group into an active hydrogen-containing group of a precursor polymer (A') having an active hydrogen-containing group, and then subjecting the precursor polymer (A') to a urethanization reaction with a silylating agent having a functional group capable of reacting with an isocyanate group and a reactive silicon group represented by the formula (1).

Examples of the silylating agent capable of undergoing an addition reaction with an unsaturated group in the method 1 include a hydrosilane compound (e.g., HSiX _a R _3-a , where X, R and a are the same as those in the formula (1)), and a compound having a reactive silicon group and 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. One silylating agent may be used alone, or two or more silylating agents may be used in combination. Of these, trimethoxysilane, triethoxysilane, dimethoxymethylsilane and diethoxymethylsilane are preferred, and dimethoxymethylsilane and trimethoxysilane are more preferred in view of high reactivity and obtaining good curability.

Examples of the silylating agent having an isocyanate group in the method 2 include isocyanate silane compounds as described in PTL1. Specific examples thereof include 1-isocyanatemethyldimethoxymethylsilane, 1-isocyanatemethyldiethoxyethylsilane, 3-isocyanatepropylmethyldimethoxysilane, 3-isocyanatepropylethyldiethoxysilane, 3-isocyanatepropylmethyldiethoxysilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, isocyanatemethyltrimethoxysilane, and isocyanatemethyltriethoxysilane. One silylating agent may be used alone, or two or more silylating agents may be used in combination. Of these, 1-isocyanatemethyldimethoxymethylsilane, 3-isocyanatepropylmethyldimethoxysilane, 3-isocyanatepropyltrimethoxysilane, and isocyanatemethyltrimethoxysilane are preferred.

It is also preferable that the active hydrogen-containing group of the precursor polymer (A') which reacts with a silylating agent having an isocyanate group is a hydroxyl group derived from ethylene oxide in view of good reactivity of the silylation reaction.

In the method 3, for example, an isocyanate group is introduced into a hydroxyl group of the precursor polymer (A') in which the active hydrogen-containing group is a hydroxyl group by a urethanization reaction using a polyisocyanate compound, and then this isocyanate group is reacted with a silylating agent having a functional group capable of reacting with an isocyanate group and a reactive silicon group represented by the formula (1). According to this method, two or more urethane bonds and a silylating agent residue reacted with the isocyanate group are introduced at the end of the precursor polymer (A').

Examples of the polyisocyanate compound in the method 3 include aromatic polyisocyanates such as naphthalene-1,5-diisocyanate, polyphenylene-polymethylene polyisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and 4,4'-methylenebis(cyclohexyl isocyanate); and urethane-modified compounds, biuret-modified compounds, allophanate-modified compounds, carbodiimide-modified compounds, and isocyanurate-modified compounds obtained from these polyisocyanates. One polyisocyanate compound may be used alone, or two or more polyisocyanate compounds may be used in combination. Of these, those having two isocyanate groups are preferred, and hexamethylene diisocyanate nat, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate are preferred, and tolylene diisocyanate is more preferred in view of good strength properties of a cured product of the curable composition.

Examples of the functional group that can react with an isocyanate group of a silylating agent having a functional group that can react with an isocyanate group and a reactive silicon group represented by the formula (1) in the process 3 include a hydroxyl group, a carboxyl group, a mercapto group, an amino group, and an amino group in which a hydrogen atom is substituted with an alkyl group having 1 to 6 carbon atoms. Of these, a group having one or two active hydrogen atoms is preferred, and a hydroxyl group, a mercapto group, an amino group, a methylamino group, an ethylamino group, and a butylamino group are preferred, and a hydroxyl group, an amino group, a methylamino group, an ethylamino group, and a butylamino group are more preferred.

The functional group capable of reacting with an isocyanate group is preferably bonded to the reactive silicon group represented by the formula (1) via a divalent organic group having 1 to 20 carbon atoms. The organic group is preferably a divalent hydrocarbon group having 1 to 20 carbon atoms, more preferably an aromatic hydrocarbon group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 1 to 10 carbon atoms substituted with an alkyl group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group having 1 to 10 carbon atoms, and a straight-chain hydrocarbon group having 1 to 12 carbon atoms, even more preferably a straight-chain hydrocarbon group having 1 to 8 carbon atoms, and particularly preferably a straight-chain hydrocarbon group having 1 to 6 carbon atoms.

The number of moles of reactive silicon groups introduced by the addition reaction per mole of the unsaturated group of the precursor polymer (A') in the process 1, the number of moles of reactive silicon groups introduced via a urethane bond of the active hydrogen-containing group of the precursor polymer (A') in the process 2; and the number of moles of reactive silicon groups introduced via a urethane bond per mole of the active hydrogen-containing group of the precursor polymer (A') in the process 3, that is, a silylation rate in the polyether-polycarbonate polymer (A), is preferably 50 to 100 mol%, more preferably 55 to 100 mol%, and even more preferably 60 to 100 mol%, from the viewpoint of obtaining good strength properties of the curable composition by moderate crosslinking.

The silylation rate can be adjusted in an appropriate manner depending on the amount of the silylating agent used and the reaction conditions of the silylation reaction.

The silylation rate can be measured by NMR analysis. When the reaction rate of the silylating agent can be assumed to be about 100 mol%, the calculated value (theoretical value) based on the amounts of the precursor polymer (A') and the silylating agent to be charged can also be used as the value of the silylation rate.

In the processes 1 to 3, the amount of the silylating agent that can be introduced per mole of the group into which a reactive silicon group can be introduced at the end of the precursor polymer (A') is 1 mole, and when the silylation rate is 100 mol%, the number of reactive silicon groups that the polyether-polycarbonate polymer (A) has is one.

[Oxyalkylene polymer (B)]

The oxyalkylene polymer (B) has two or more terminal groups and a reactive silicon group represented by the formula (1).

In the curable composition, the reactive silicon group of the oxyalkylene polymer (B) may be identical to or different from the reactive silicon group of the polyether-polycarbonate polymer (A).

One oxyalkylene polymer (B) may be used alone, or two or more oxyalkylene polymers (B) may be used in combination.

The oxyalkylene polymer (B) can be produced by a method of reacting a silylating agent with a precursor polymer (B') having a terminal group into which a reactive silicon group can be introduced.

It is preferred that the terminal groups of the precursor polymer (B') are each independently an unsaturated group or a hydroxyl group.

The precursor polymer (B') is preferably a polymer obtained by subjecting an alkylene oxide to addition polymerization with an initiator having two or more active hydrogen-containing groups. That is, the oxyalkylene polymer (B) and the precursor polymer (B') comprise alkylene oxide-based units.

The precursor polymer (B') is preferably a precursor polymer (B'1) comprising a polyoxyalkylene chain and having two or more hydroxyl groups as end groups, or a precursor polymer (B'2) comprising a polyoxyalkylene chain and having two or more unsaturated groups as end groups.

The precursor polymer (B'1) can be produced by subjecting an alkylene oxide to ring-opening addition polymerization with an initiator having two or more active hydrogen-containing groups in the presence of a catalyst.

The active hydrogen-containing group of the initiator is preferably a hydroxyl group. Examples of the initiator include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, low molecular weight polypropylene glycol (e.g., a hydroxyl value equivalent molecular weight of 50 to 8,000; the same applies hereinafter), glycerin, low molecular weight polyoxypropylenetriol, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, 1,2,6-hexanetriol, diglycerin and dipentaerythritol. One initiator may be used alone, or two or more initiators may be used in combination.

The alkylene oxide and catalyst used for the ring-opening addition polymerization may be the alkylene oxide and catalyst described above in the description of the preparation of the precursor polymer (A'). The alkylene oxide and catalyst used for the preparation of the precursor polymer (B'1) may be the same as or different from those used in the preparation of the precursor polymer (A').

The precursor polymer (B'2) can be produced by a known method in which the hydroxyl group of the precursor polymer (B'1) is subjected to metal oxidation to form an alkoxide and then the alkoxide is reacted with a halogenated hydrocarbon containing an unsaturated group such as allyl chloride, methallyl chloride or propargyl bromide. The precursor polymer (B'2) can also be produced by a known method in which the hydroxyl group of the precursor polymer (B'1) is subjected to metal oxidation to form an alkoxide and then the alkoxide is reacted with an epoxy compound containing an unsaturated group such as allyl glycidyl ether and further reacted with an unsaturated group-containing halogenated hydrocarbon. The precursor polymer (B'2) can also be obtained by a method of reacting a compound having a functional group capable of reacting with a hydroxyl group and an unsaturated group with the precursor polymer (B'1) and introducing an unsaturated group via an ester bond, a urethane bond or the like.

The method of obtaining the oxyalkylene polymer (B) by introducing a reactive silicon group into a hydroxyl group or an unsaturated group at the terminal of the precursor polymer (B') may be identical to the method of introducing a reactive silicon group into a hydroxyl group or an unsaturated group at the terminal of the precursor polymer (A').

When the curable composition is cured, the oxyalkylene polymers (B) are crosslinked with each other, and a part of the oxyalkylene polymer (B) reacts with the polyether-polycarbonate polymer (A). Since the polyether-polycarbonate polymer (A) has an average of 1 or less reactive silicon group(s) per molecule, the crosslinking reaction between the oxyalkylene polymers (B) is inhibited by the reaction of the oxyalkylene polymer (B) with the polyether-polycarbonate polymer (A). For this reason, an excessive amount of the polyether-polycarbonate polymer (A) mixed may cause poor curing.

On the other hand, the larger the amount of the polyether-polycarbonate polymer (A) in the curable composition, the better the weather resistance of the cured product of the curable composition.

Therefore, a larger blended amount of the polyether-polycarbonate polymer (A) and a higher silylation rate of the oxyalkylene polymer (B) are beneficial for improving the weather resistance of a cured product of the curable composition and do not cause poor curing. The higher the silylation rate of the oxyalkylene polymer (B), the less the crosslinking reaction is inhibited due to the ratio relationship and the less it becomes uncured even if a large amount of the polyether-polycarbonate polymer (A) is blended.

Accordingly, the higher the silylation rate of the oxyalkylene polymer (B), the more the polyether-polycarbonate polymer (A) can be blended, the more the curable composition has good curability, and the strength and weather resistance of a cured product of the curable composition are improved.

The proportion of reactive silicon groups introduced into an unsaturated group or a hydroxyl group which are terminal groups of the precursor polymer (B'), that is, the silylation rate in the oxyalkylene polymer (B), is preferably 50 to 100 mol%, more preferably 55 to 100 mol%, still more preferably 60 to 100 mol%, in view of good curability of the curable composition.

The Mn of the oxyalkylene polymer (B) is preferably 10,000 to 50,000, more preferably 12,000 to 40,000, and even more preferably 15,000 to 30,000, in view of good strength properties of a cured product of the curable composition and a viscosity which causes the curable composition to be easily handled.

Mw/Mn of the oxyalkylene polymer (B) is preferably 1.0 to 1.8, more preferably 1.0 to 1.7, and even more preferably 1.0 to 1.5, in view of a viscosity that causes the curable composition to be easily handled and good strength properties of a cured product of the curable composition.

The number of terminal groups per molecule of the oxyalkylene polymer (B) is 2 or more, preferably 2 to 6, and more preferably 2 to 4, in view of good strength properties of a cured product of the curable composition.

The oxyalkylene polymer (B) has, for example, an unsaturated group, an active hydrogen-containing group or an isocyanate group as a terminal group other than the reactive silicon group represented by the formula (1). The unsaturated group, the active hydrogen-containing group and the reactive silicon group other than those represented by the formula (1) are as described above for the polyether-polycarbonate polymer (A).

[Vinyl polymer (C)]

The curable composition may comprise a vinyl polymer (C) having an average of 0.8 or more reactive silicon groups represented by the formula (1) per molecule as a polymer other than the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B). One vinyl polymer (C) may be used alone, or two or more vinyl polymers may be used in combination.

The weather resistance, water resistance and the like of a cured product of the curable composition can be improved when the curable composition comprises the vinyl polymer (C).

The vinyl polymer (C) may have a reactive silicon group either at the end of a main chain or at the end of a side chain, and may have it at both the end of the main chain and the end of the side chain.

The average number of reactive silicon groups per molecule of the vinyl polymer (C) is, in view of good strength, elongation and the like of a cured product of the curable composition is preferably 0.8 or more, more preferably 1.0 to 4.0, and even more preferably 1.2 to 3.0.

The average number of reactive silicon groups per molecule of the vinyl polymer (C) can be calculated as the product of the concentration of reactive silicon groups [mol/g] measured by NMR analysis and Mn.

The vinyl polymer (C) can be produced by a known method, and the method may be a method of reacting a compound having a reactive silicon group with a vinyl monomer or a method of introducing a reactive silicon group into a polymer. For example, the production method described in JP 2006-257405 A , JP 2006-37076 A or JP 2008-45059 A described.

The vinyl monomer constituting a main chain of the vinyl polymer (C) may be a known vinyl monomer, and examples thereof include those described in JP H3-14068 B , JP H6-211922 A and JP H11-130931 A described.

The vinyl monomer preferably comprises a (meth)acrylic acid ester in view of good strength properties and good weather resistance of a cured product of the curable composition. In this case, the content of the (meth)acrylic acid ester is preferably 50 mass% or more, more preferably 70 mass% or more, and may be 100 mass% or more based on the total amount of the monomers constituting the vinyl polymer (C).

The Mn of the vinyl polymer (C) is preferably 500 to 100,000, more preferably 800 to 80,000, and even more preferably 1,000 to 60,000, in view of good weather resistance of a cured product of the curable composition and a viscosity which makes the curable composition easy to handle.

Mw/Mn of the vinyl polymer (C) is preferably 4.0 or less, and more preferably 3.0 or less, in view of a viscosity which makes the curable composition easy to handle and good strength properties of a cured product of the curable composition.

[mixed composition]

Regarding the contents of the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B) in the curable composition, the content of the polyether-polycarbonate polymer (A) is preferably 5 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass based on 100 parts by mass of the oxyalkylene polymer (B), in view of a viscosity which makes the curable composition easy to handle and good strength properties of a cured product of the curable composition.

When the curable composition contains a vinyl polymer (C), the content of the vinyl polymer (C) is preferably 1 to 600 parts by mass, more preferably 5 to 500 parts by mass, and still more preferably 10 to 300 parts by mass based on 100 parts by mass of a total amount of the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B), in view of good weather resistance of a cured product of the curable composition.

The curable composition may comprise other components other than the polyether-polycarbonate polymer (A), the oxyalkylene polymer (B) and the vinyl polymer (C). The other components may be known additives depending on the application of the curable composition, and examples thereof include curing catalysts, fillers, plasticizers, thixotropic agents, antioxidants, ultraviolet absorbers, light stabilizers, dehydrating agents, tackifiers, amine compounds, oxygen-curable compounds, light-curable compounds, epoxy compounds and acrylic compounds. Each of these components may be used in a combination of two or more. For example, the 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 2017-039728 A and JP 2017-214541 A described may be used in a suitable combination. Other ingredients are mixed to an extent that they do not impair the effect of the present invention.

The total content of the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B) in the curable composition is preferably 3 to 60 mass%, more preferably 5 to 55 mass%, more preferably 10 to 50 mass% based on 100 mass% of the curable composition, in view of good strength properties and good weather resistance of a cured product of the curable composition.

The curable composition preferably comprises a curing catalyst for facilitating crosslinking by the formation of siloxane bonds based on reactive silicon groups. When the curable composition comprises a curing catalyst, the content of the curing catalyst is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.5 to 2 parts by mass, based on 100 parts by mass of a total amount of the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B), from the viewpoint of obtaining a uniformly cured product by promoting moderate crosslinking.

The curable composition may be a one-component curable composition in which all the mixing ingredients are premixed, hermetically sealed and stored, and cured by moisture in the air after application, or it may be a two-component curable composition in which a main agent composition comprising the polyether-polycarbonate polymer (A) and the oxyalkylene polymer (B) and a curing agent composition comprising the curing catalyst are stored separately, and the main agent composition and the curing agent composition are mixed before use. In view of ease of application, a one-component curable composition is preferred.

In the case of a one-pack curable composition, it is preferable that the curable composition does not contain moisture. It is preferable that the compounding ingredients containing moisture are dehydrated and dried in advance, or that dehydration is carried out by decompression or the like during mixing and kneading.

In the case of a two-component curable composition, the main agent composition is difficult to gel even if it contains a small amount of water, but in view of good storage stability, it is preferable that the mixed components are dehydrated and dried in advance.

In order to ensure good storage stability, a dehydrating agent may be added to the one-component curable composition and the main agent composition of the two-component curable composition.

The curable composition of the present invention is cured at room temperature to obtain a cured product and can be used in various applications. In particular, the curable composition of the present invention is suitable for sealants (e.g., elastic sealants for construction, laminated glass sealants, anti-rust and waterproof sealants for glass ends, solar cell back surface sealants, building sealants, marine sealants, automobile sealants, road sealants), electrical insulating materials (insulating coating materials for electric wires and cables), adhesives, potting materials and the like. It is particularly suitable for applications requiring excellent strength properties and weather resistance, such as sealants and adhesives used outdoors.

examples

Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples, and various variations are possible without departing from the gist of the present invention.

[measurement method]

The methods for measuring various physical properties in the following synthesis examples and preparation examples are as follows.

(hydroxyl number)

The hydroxyl values were measured according to the B method (automatic potentiometric titration method) of JIS K1557-1: 2007.

<hydroxyl number equivalent molecular weight>

The hydroxyl value equivalent molecular weight was calculated from the hydroxyl value [mg KOH/g] measured as above using the following formula (molecular weight of potassium hydroxide 56.1). $$\begin{array}{l}\left(\text{Hydroxylzahl}-\ddot{\text{a}}\text{quivalentes Molekulargewicht}\right)=\mathrm{56,1}\times 1000\times (\text{Anzahl von}\\ \text{Hydroxylgruppen pro Molek}\ddot{\text{u}}\text{l})/\left(\text{Hydroxylzahl}\right)\end{array}$$

The number of hydroxyl groups per molecule was set as the number of hydroxyl groups per molecule of an initiator used in the synthesis of a polymer.

(degree of unsaturation)

The degree of unsaturation of an allylated polyether (Z1) was determined by measuring the iodine number using the Wijs method and converting the value into milligram equivalents [meq/g] of the vinyl group per gram of the allylated polyether (Z1).

(Content of the unit based on carbon dioxide (CO ₂ unit))

For a polymer sample, proton nuclear magnetic resonance ( ¹ H-NMR) spectra (the same applies below) were measured under the following conditions.

<measurement conditions>

• - Equipment used: “JNM-ECZ400S FT-NMR”, manufactured by JEOL Ltd.
• - Solvent: Deuterochloroform
• - Polymer concentration in the sample: 10 mass%

In the obtained NMR spectrum, the content of the CO ₂ unit was calculated on the basis of 100 mass % of a total amount of CO ₂ units (formula weight 44) and units based on an alkylene oxide in the polymer from the following equations based on the area S1 of the signal assigned to a methyl group (δ1.34 ppm, 3H) in the oxypropylene group (formula weight 58) in which both ends are bonded to a carbonate group, the area S2 of the signal assigned to a methyl group (δ1.29 ppm, 3H) in the oxypropylene group in which one end is bonded to a carbonate group and the other end is bonded to an oxypropylene group, and the area S3 of the signal assigned to a methyl group (δ1.14 ppm, 3H) in the oxypropylene group in which both ends are bonded to an oxypropylene group. $$\begin{array}{l}\left({\text{Gehalt von CO}}_2\left[\text{Massen}-\%\right]\right)=\left(\text{S1}+\text{S2}\right)/\left\{\left(\text{S1}+\text{S2}\right)\times \left(58+44\right)+\text{S3}\times \text{58}\right\}\times 44\times \\ 100\end{array}$$

(Viscosity)

The viscosity [Pa s] of the polymer was measured with an E-type viscometer (“RE80 type viscometer”, manufactured by Toki Sangyo Co., Ltd.; 25 °C). “JS14000” (manufactured by NIPPON GREASE Co., Ltd.) was used as a calibration standard solution.

(number average molecular weight (Mn) and weight average molecular weight (Mw))

Mn and Mw were measured by gel permeation chromatography (GPC) under the following measurement conditions (polystyrene equivalent) and the molecular weight distribution (Mw/Mn) was calculated from these values.

<measurement conditions>

• - Machine used: “HLC-8220GPC”, manufactured by Tosoh Corporation
• - Column used: “TSKgel(R) SuperMultipore HZ-M”, manufactured by Tosoh Corporation
• - Detector: Refractive index difference (RI) detector
• - Detection temperature: 40°C
• - Eluent: tetrahydrofuran
• - Flow rate: 0.350 mL/min
• - Sample concentration: 0.5 mass%
• - Sample injection volume: 10 µL
• - Standard sample: polystyrene

(silylation rate)

For polymers A1, B1, A'1 and A'3, the proportion of the number of moles of reactive silicon groups added per mole of an allyl group of a precursor polymer was determined by means of a ¹ H-NMR spectrum, and the determined value was used as the silylation rate.

The silylation rates of polymers A2, A3 and A'2 were determined as a proportion of the amount [mol] of 3-isocyanatopropylmethyldimethoxysilane introduced per mole of a hydroxyl group of a precursor polymer.

(Average number of reactive silicon groups per molecule)

The average number of reactive silicon groups per molecule of polymers A1, B1, A'1 and A'3 was determined by multiplying the number of allyl groups per molecule of the precursor polymer by the silylation rate.

The average number of reactive silicon groups per molecule of polymers A2, A3 and A'2 was determined by multiplying the number of hydroxyl groups per molecule of the precursor polymer by the silylation rate.

[Connections used]

• - Allylierter Polyether (Z1): Polyoxypropylen mit einer Allylgruppe an einem Ende und einer Hydroxylgruppe an dem anderen Ende der Hauptkette (Hydroxylzahl 86,3 mg KOH/g, Hydroxylzahl-äquivalentes Molekulargewicht 650, Ungesättigtheitsgrad 1,54 mmol/g)
• - TBA-DMC-Katalysator: Zinkhexacyanocobaltat-Komplex mit tert-Butanol als Ligand
• - Glyme-DMC-Katalysator: Zinkhexacyanocobaltat-Komplex mit Glyme als Ligand
• - U-860: Dioctylzinnbis(isooctylthioglykolat); „NEOSTANN(R) U-860“, hergestellt von Nitto Kasei Co., Ltd.
• - KBM-803: 3-Mercaptopropyltrimethoxysilan; „KBM-803“, hergestellt von Shin-Etsu Chemical Co., Ltd.

Details of the various compounds used in examples are shown below.

• - Allylated polyether (Z1): polyoxypropylene with an allyl group at one end and a hydroxyl group at the other end of the main chain (hydroxyl number 86.3 mg KOH/g, hydroxyl number equivalent molecular weight 650, degree of unsaturation 1.54 mmol/g)
• - TBA-DMC catalyst: zinc hexacyanocobaltate complex with tert-butanol as ligand
• - Glyme-DMC catalyst: zinc hexacyanocobaltate complex with glyme as ligand
• - U-860: dioctyltinbis(isooctylthioglycolate); “NEOSTANN(R) U-860” manufactured by Nitto Kasei Co., Ltd.
• - KBM-803: 3-mercaptopropyltrimethoxysilane; “KBM-803”, manufactured by Shin-Etsu Chemical Co., Ltd.

<Synthesis of the polymer>

(Synthesis Example 1)

The reactor was charged with 52 g of allylated polyether (Z1) as an initiator and 0.04 g of a TBA-DMC catalyst. A series of operations of introducing carbon dioxide, pressurizing (about 1.5 MPa) and then depressurizing (about 0.1 MPa) was repeated three times and then the reactor was heated to 130 °C and degassed under reduced pressure for 2 hours.

Then, the pressure was maintained at 1.5 MPa, 7 g of propylene oxide (hereinafter referred to as "PO") was added, and after confirming heat generation, the liquid temperature was lowered to 110 °C and 285 g of PO was added over 9 hours. After reacting at 110 °C for 2 hours, the liquid temperature was raised to 130 °C, the reactor was maintained under reduced pressure for 5 hours, and propylene carbonate, which is a by-product, was removed.

The reactant was then discharged from the reactor to obtain an allylated polyether-polycarbonate monool (precursor polymer a1; hydroxyl value 14.8 mg KOH/g, carbon dioxide-based unit content 13.2 mass%, viscosity 8.6 Pa s, 1 hydroxyl group per molecule).

Then, 1 mol of dimethoxymethylsilane was added per mol of the allyl group of the precursor polymer a1 in the presence of platinum chloride hexahydrate and reacted at 85 °C for 4 hours to obtain a polyether-polycarbonate polymer into which a dimethoxymethylsilyl group had been introduced (polymer A1).

(Synthesis Example 2)

A reactor was charged with the precursor polymer a1, and the air inside the reactor was replaced with nitrogen gas, and while the inside temperature was kept at 80 °C, 3-isocyanatopropylmethyldimethoxysilane was added at 0.97 mol of an isocyanate group per mol of a hydroxyl group (NCO/OH molar ratio) of the precursor polymer a1, and U-860 was added as a catalyst. The liquid temperature was raised to and kept at 80 °C, and the mixture was stirred. After confirming the completion of the reaction of the hydroxyl group and the isocyanate group with a Fourier transform infrared spectrophotometer, 0.06 parts by mass of KBM-803 was added as a storage stabilizer based on 100 parts by mass of the precursor polymer a1 to obtain a polyether-polycarbonate polymer in which a urethane bond and a dimethoxymethylsilyl group were introduced into the main chain (polymer A2).

(Synthesis Example 3)

The reactor was charged with 32 g of polypropylene glycol (hydroxyl value equivalent molecular weight 400) as an initiator obtained by subjecting PO to ring-opening addition polymerization of PO with n-butanol and 0.04 g of a TBA-DMC catalyst. A series of operations of introducing carbon dioxide, pressurizing (about 1.5 MPa) and then depressurizing (about 0.1 MPa) were repeated three times, and then the reactor was heated to 130 °C and degassed under reduced pressure for 2 hours.

Then, the pressure was maintained at 1.5 MPa, 8 g of PO was added, and after confirming heat generation, the liquid temperature was reduced to 110 °C and 312 g of PO was added over 9 hours. After reacting at 110 °C for 2 hours, the liquid temperature was raised to 130 °C, the reactor was maintained under reduced pressure for 5 hours, and propylene carbonate, which is a byproduct, was removed.

The reactant was taken out from the reactor to obtain a polyether-polycarbonate monool (precursor polymer a2; hydroxyl value 12.8 mg KOH/g, carbon dioxide-based unit content 11.0 mass%, viscosity 9.5 Pa s, 1 hydroxyl group per molecule).

The same procedure as in Synthesis Example 2 was carried out except that the precursor polymer a1 in Synthesis Example 2 was changed to the precursor polymer a2, so that a polyether-polycarbonate polymer in which a urethane bond and a dimethoxymethylsilyl group were introduced into the main chain was obtained (Polymer A3).

(Synthesis Example 4)

Polypropylene glycol (hydroxyl value equivalent molecular weight 3000) obtained by subjecting PO to ring-opening addition polymerization with propylene glycol was used as an initiator, and 1703 g of PO was added to 394 g of the initiator in the presence of 0.56 g of a glyme-DMC catalyst and reacted until no pressure drop was observed in the reaction system at 125 °C, whereby polypropylene glycol (precursor polymer b'1-1; hydroxyl value 7.0 mg KOH/g, 2 hydroxyl groups per molecule) was obtained.

Polyoxypropylenetriol (hydroxyl value equivalent molecular weight 5000) obtained by subjecting PO to ring-opening addition polymerization with glycerin was used as an initiator, and 1020 g of PO was added to 340 g of the initiator in the presence of 0.48 g of a glyme-DMC catalyst and reacted until no pressure drop was observed in the reaction system at 125 °C to obtain a polyoxypropylenetriol (precursor polymer b'1-2; hydroxyl value 8.4 mg KOH/g, 3 hydroxyl groups per molecule).

The precursor polymer b'1-1 and the precursor polymer b'1-2 were mixed in a mass ratio of 70/30 to obtain a mixture (precursor polymer b'1; 2.3 hydroxyl groups per molecule). A methanol solution containing 1.10 mol of sodium methoxide per molecule of the hydroxyl group of the precursor polymer b'1 was added to the alcoholate. The number of hydroxyl groups per molecule of the precursor polymer b'1 was a weighted average of the number of hydroxyl groups per molecule of the precursor polymer b'1-1 and the precursor polymer b'1-2. Methanol was distilled off under heating and reduced pressure, and allyl chloride was added in excess equivalent to the hydroxyl group of the precursor polymer b'1 to obtain an allylated polyether (precursor polymer b1).

Then, 0.67 mol of dimethoxymethylsilane per mol of the allyl group of the precursor polymer b1 was added in the presence of platinum chloride hexahydrate and reacted at 85 °C for 4 hours to obtain a polyoxypropylene polymer in which a dimethoxymethylsilyl group was introduced (polymer B1). The number of terminal groups of the polymer B1 corresponding to the number of hydroxyl groups per molecule of the precursor polymer b'1 is 2.3.

(Synthesis Example 5)

50 g of an allylated polyether (Z1) and 0.04 g of a TBA-DMC catalyst were introduced into the reactor. Then, 350 g of PO was added and a ring-opening addition polymerization was carried out at 130 °C to obtain an allylated polypropylene monool (precursor polymer a3; hydroxyl number 11.1 mg KOH/g, viscosity 1.2 Pa s, 1 hydroxyl group per molecule).

Then, 1 mole of dimethoxymethylsilane per mole of the allyl group of the precursor polymer a3 was added in the presence of platinum chloride hexahydrate and reacted at 85 °C for 4 hours to obtain a polyoxypropylene polymer into which a dimethoxymethylsilyl group had been introduced (polymer A'1).

(Synthesis Example 6)

A polyoxypropylene polymer in which a urethane bond and a dimethoxymethylsilyl group were introduced into the main chain (polymer A'2) was obtained in the same manner as in Synthesis Example 2 except that the precursor polymer a3 was introduced instead of the precursor polymer a1.

(Synthesis Example 7)

A polyoxypropylene monool (hydroxyl value equivalent molecular weight 2000) obtained by subjecting PO to ring-opening addition polymerization with n-butanol was used as an initiator, and 576 g of PO was added to 384 g of the initiator in the presence of 0.05 g of a TBA-DMC catalyst and reacted until no pressure drop was observed in the reaction system at 120 °C to obtain a polyoxypropylene monool (precursor polymer a4-1; hydroxyl value 11.2 mg KOH/g, 1 hydroxy group per molecule).

A methanol solution containing 1.10 moles of sodium methoxide per mole of the hydroxyl group of the precursor polymer a4-1 was added to the precursor polymer a4-1 to form an alcoholate. Methanol was distilled off under heating and reduced pressure, and allyl chloride was added in excess equivalent to the hydroxyl group of the mixture to obtain an allylated polyether (precursor polymer a4).

Then, 1 mole of dimethoxymethylsilane was added per mole of the allyl group of the precursor polymer a3 in the presence of platinum chloride hexahydrate and reacted at 85 °C for 4 hours to obtain a polyoxypropylene polymer in which a dimethoxymethylsilyl group had been introduced (polymer A'3).

The aspects of each of the polymers prepared in the above synthesis examples are given in Table 1 below.

Table 1 synthesis example 1 2 3 4 5 6 7 polymer A1 A2 A3 B1 A'1 A'2 A'3 precursor polymer a1 a1 a2 b1 a3 a3 a4 Content of CO ₂ unit [mass%] 13.2 13.2 11.0 0 0 0 0 presence or absence of a urethane bond Missing Is available Is available Missing Missing Is available Missing Mn 7200 6500 7520 20,000 8100 7700 8100 Mw/Mn 1.70 1.55 1.93 1.46 1.17 1.12 1.14 silylation rate [mol-%] 82 97 97 67 78 97 79 Average number of reactive silicon groups per molecule 0.82 0.97 0.97 1.54 0.78 0.97 0.79

[Preparation of a curable composition]

Each polymer and various additives prepared in the above synthesis examples were used to prepare a curable composition for a sealant.

The additives used and the amount added (based on 100 parts by mass of polymer B1) are shown below.

[Addition 1] (total quantity 162 parts by mass)

<Thixotropic agent>

• - “DISPARLON(R) 6500” (hydrogenated castor oil-based thixotropic agent; product name, manufactured by Kusumoto Chemicals, Ltd.) 3 parts by mass

<filler>

• - “HAKUENKA CCR” (colloidal calcium carbonate; product name, manufactured by Shiraishi Calcium Kaisha, Ltd.) 75 parts by mass
• - “WHITON(R) SB” (heavy calcium carbonate; manufactured by Shiraishi Calcium Kaisha, Ltd.) 75 parts by mass

<dehydrating agent>

• - “KBM-1003” (vinyltrimethoxysilane; product name, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts by mass

<sticky agent>

• - “KBM-403” (3-glycidyloxypropyltrimethoxysilane; product name, manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass
• - “KBM-603” (3-(2-Aminoethylamino)propyltrimethoxysilane; product name, manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass

<Stabilizer>

• - “lrganox(R) 1010” (antioxidant based on hindered phenol; product name, BASF SE) 1 part by mass
• - “HS ester 765” (hindered amine based ester; light stabilizer; manufactured by HOKOKU CORPORATION) 1 part by mass
• - “Tinuvin(R) 326” (ultraviolet absorber based on benzotriazole, product name, BASF SE) 1 part by mass

<curing catalyst>

• - “NEOSTANN(R) U-220H” (dibutyltin bis(acetylacetonate)) 1 part by mass

[Addendum 2]

<plasticizer>

• - DINP: Diisononyl phthalate; “VINYCIZER(R) 90”, manufactured by Kao Co., Ltd. 40 parts by mass

[Example 1]

To 100 parts by mass of the polymer B1, a mixture obtained by mixing 40 parts by mass of the polymer A1 and a thixotropic agent and heating to swell at 90 °C and a filler were added, and stirred and mixed in a planetary mixer (manufactured by Kurabo Industries Ltd.).

The resulting mixture was cooled to 25 °C and further stirred and mixed while adding a dehydrating agent, a tackifier and a stabilizer. Then, the curing catalyst was added and stirred and mixed to prepare a curable composition.

(Examples 2 to 7)

Curable compositions were prepared in the same manner as in Example 1 except that the mixing composition was changed as shown in Table 2.

[Evaluation of the cured product]

A tensile test and a weather resistance test were conducted on the cured products obtained by using the curable compositions obtained in each of the above examples. The evaluation results of each test are shown in Table 2. Examples 1 to 3 are working examples and Examples 4 to 7 are comparative examples.

(tensile test)

The curable composition was filled into a mold with a thickness of 2 mm and cured by curing for 3 days in an atmosphere with a temperature of 23 °C and a relative humidity of 50% and further curing for 4 days in an atmosphere with a temperature of 50 °C and a relative humidity of 65%. The resulting cured product was punched and prepared to obtain a No. 3 dumbbell test specimen in accordance with JIS K 6251: 2017.

For each specimen, a tensile test was performed using a Tensilon tester (temperature 23 °C, tensile speed 500 mm/min) to measure the stress at 50% strain (M50) [N/mm ² ], the maximum point cohesion (Tmax) [N/mm ² ] and the maximum point strain (Emax) [%].

In this test, if M50 is 0.3 N/mm ² or more, Tmax is 1.75 N/mm ² or more and Emax is 650% or more, it can be considered that the strength is good and the strength properties are suitable for a sealant.

(weather resistance test)

The curable composition was filled into a frame with a length of 40 mm, a width of 40 mm and a thickness of 5 mm and cured for 3 days in an atmosphere at a Temperature of 23 °C and relative humidity of 50% and further curing for 4 days in an atmosphere at a temperature of 50 °C and relative humidity of 65%. The obtained cured product was used as a test specimen and a stationary weather resistance test was carried out by a method according to the WX-A method of JIS A 1415: 2013 using a metal halide lamp type accelerated weatherability tester (“EYE Super UV Tester”, manufactured by IWASAKI ELECTRIC CO., LTD.; black plate temperature 63 °C, relative humidity 50%, rain for 120 seconds/118 minutes).

The presence or absence of cracks was visually inspected for the test specimens 72 and 144 hours after the start of the test. The rating was "A" if there were no cracks, the rating was "B" if cracks were slightly observed, and the rating was "C" if cracks were clearly observed. If the rating is A or B, the cured product can be considered to be weather resistant.

Table 2 Example 1 2 3 4 5 6 7 mixed composition [parts by mass] Polymer B1 100 100 100 100 100 100 100 Polymer A1 40 - - - - - - Polymer A2 - 40 - - - - - Polymer A3 - - 40 - - - - Polymer A'1 - - - 40 - - - Polymer A'2 - - - - 40 - - Polymer A'3 - - - - - 40 - Amendment 1 162 162 162 162 162 162 162 Amendment 2 - - - - - - 40 tensile properties M50 [N/mm ² ] 0.32 0.39 0.40 0.27 0.31 0.31 0.34 Tmax [N/mm ² ] 1.78 1.98 2.03 1.76 1.86 1.92 1.75 Emax [%] 750 680 670 760 760 760 640 weather resistance After 72 hours A A A B A B B After 144 hours B B B C C C C

As is apparent from the evaluation results shown in Table 2, it was confirmed that the curable composition of the present invention (Examples 1 to 3) gives a cured product having both excellent strength properties and excellent weather resistance.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• JP 2011-178955 A [0004]
• JP 2021-59722 A [0004]
• WO 2003/062301 [0052]
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Cited non-patent literature

• JIS A 1415: 2013 [0150]

Claims (9)

A curable composition comprising: a polyether-polycarbonate polymer (A) comprising a carbon dioxide-based unit and an alkylene oxide-based unit, having on average 1 or less reactive silicon group(s) represented by the following formula (1) per molecule, and having a number average molecular weight (Mn) of 2,000 to 50,000; and an oxyalkylene polymer (B) having two or more terminal groups and a reactive silicon group represented by the following formula (1): -SiX _a R _3-a (1) wherein X is a halogen atom, a hydroxyl group or a hydrolyzable group; R is a monovalent organic group having 1 to 20 carbon atoms and not including a hydrolyzable group; and a is an integer of 1 to 3, and when a is 1, two R's may be identical or different from each other, and when a is 2 or 3, a plurality of X's may be identical or different from each other. Curable composition according to claim 1 wherein the alkylene oxide-based unit of the polyether-polycarbonate polymer (A) comprises a propylene oxide-based unit. Curable composition according to claim 1 or 2 wherein a content of the carbon dioxide-based unit of the polyether-polycarbonate polymer (A) is 10 to 30 mass% based on 100 mass% of a total amount of the carbon dioxide-based unit and the alkylene oxide-based unit. Curable composition according to claim 1 or 2 , wherein the polyether-polycarbonate polymer (A) has on average more than 0.5 of the reactive silicon groups per molecule. Curable composition according to claim 1 or 2 wherein a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyether-polycarbonate polymer (A) is from 1.0 to 3.0. Curable composition according to claim 1 or 2 wherein a number average molecular weight (Mn) of the oxyalkylene polymer (B) is 10,000 to 50,000. Curable composition according to claim 1 or 2 wherein a content of the polyether-polycarbonate polymer (A) is 5 to 100 parts by mass based on 100 parts by mass of the oxyalkylene polymer (B). Curable composition according to claim 1 or 2 , which further comprises a curing catalyst. Cured product of the curable composition according to claim 1 or 2 .