JP5286711B2 - Curable composition - Google Patents

Description

  The present invention relates to a curable composition that is cured by hydrolysis and crosslinking reaction of a hydrolyzable silicon group in the presence of moisture.

A polymer having a hydrolyzable silicon group at the terminal of a polyoxyalkylene chain has a moisture curable property, a cured product has rubber elasticity, and has characteristics such as less peripheral joint contamination. It is used for curable compositions such as.
However, when the curable composition containing the polymer is used outdoors in winter, the reactivity of the polymer at a low temperature is low, so that sufficient curing does not proceed in a predetermined time, and there is a problem in workability. Arise.
Moreover, when using this curable composition as a sealing material, an adhesive agent, etc. in a factory line, the curable composition is required to be cured in a short time for the purpose of improving productivity.

As the curable composition, the following curable compositions have been proposed.
(1) A curable composition containing a polymer having a methyldimethoxysilyl group at the end of a polyoxyalkylene chain (see Patent Document 1).
(2) A curable composition containing a polymer having a trimethoxysilyl group at the end of a polyoxyalkylene chain (see Patent Documents 2 and 3).
(3) A curable composition containing a polymer in which a terminal hydroxyl group of a polyoxypropylene polyol having a functionality of 4 or more is substituted with a methyldimethoxysilyl group (see Patent Document 4).

  The cured product obtained by curing the curable composition (1) has elongation and flexibility, but the curing rate of the curable composition is not sufficient. By increasing the amount of the curing catalyst or increasing the activity of the curing catalyst, the room temperature curing rate can be shortened from about 12 hours to several hours, but it is difficult to increase the curing rate further, and the pot There are problems such as shortening of life and deterioration of storage stability.

  The curable composition (2) cures quickly in the presence of moisture because the trimethoxysilyl group of the polymer is easily hydrolyzed and a crosslinking due to a siloxane bond is easily formed. However, when a polymer having a trimethoxysilyl group is used alone, the resulting cured product is brittle and therefore has insufficient adhesion (elongation and peel strength). Moreover, since the curing rate at room temperature (23 ° C.) is too high, there is a problem in workability.

The curable composition (3) has a low viscosity and excellent workability, and is excellent in the shear strength of the cured product. However, the cure rate is still insufficient.
Japanese Patent Publication No.58-10418 Japanese Patent Laid-Open No. 3-47825 Japanese Patent Laid-Open No. 10-245484 JP-A-7-62205

  The present invention provides a curable composition that is excellent in adhesiveness (elongation and peel strength), can obtain a cured product having high shear strength, and has a high curing rate.

The curable composition of the present invention includes the following curable material (a1), the following curable material (a2), and a curing catalyst (b).
(Curable material (a1))
By modifying a polyoxyalkylene polyol having 4 or more hydroxyl groups, a polymer (a1) (in which 85 mol% or more of the hydroxyl groups are converted into a group (X1) having a group represented by the following formula (Y1) ( However, the hydroxyl group which is not converted into the group (X1) may be modified with another group).
(Curable material (a2))
By modifying polyoxyalkylene diol, polymer (a21) in which 50 mol% or more of the hydroxyl group is converted to group (X) having a group represented by the following formula (Y) (however, in group (X) The hydroxyl group that is not converted may be modified with another group) and / or the polyoxyalkylene monool having an unsaturated group is modified to reduce 50 mol% or more of the total of unsaturated groups and hydroxyl groups. The polymer (a22) converted into the group (X) having a group represented by the formula (Y) (however, it may have an unsaturated group and / or a hydroxyl group that is not converted into the group (X)). 1 type or 2 types or more, Comprising: Of all group (X) (100 mol%) which exists in curable material (a2), said group (X1) is 50 mol% or more.
-Si (OR) ₃ (Y),
_{-Si (OCH 3) 3 ··· (} Y1).
However, R is a C1-C6 organic group, respectively.

Of all the groups (X) (100 mol%) present in the curable material (a2), the group (X1) is 50 mol% or more, and the remaining groups (X) are represented by the following formula (Y2) It is preferable that it is group (X2) which has group represented by these.
_{-Si (OCH 2 CH 3) 3} ··· (Y2).
Of all the groups (X) (100 mol%) present in the pre-curing material (a2), the group (X1) is more preferably 100 mol%.

The number of hydroxyl groups in the polyoxyalkylene polyol is preferably 4-6.
The ratio of the curable material (a1) to the curable material (a2) (curable material (a1) / curable material (a2)) is 90/10 to 10/90 (mass ratio). 80/20 to 10/90 (mass ratio) is more preferable.

The number average molecular weight (Mn) of the polymer (a1) is 8000 to 50000, the molecular weight distribution (Mw / Mn) of the polymer (a1) is 1.6 or less, and the polymer (a21) Or the number average molecular weight (Mn) of the said polymer (a22) is 8000-50000, and the molecular weight distribution (Mw / Mn) of the said polymer (a21) or the said polymer (a22) is 1.6 or less. Preferably there is.
The group (X1) of the polymer (a1) preferably has a urethane bond.

  According to the curable composition of the present invention, a cured product having excellent adhesiveness (elongation and peel strength) and high shear strength can be obtained. Further, the curable composition of the present invention has a high curing rate.

  In the present specification, a group represented by the formula (X) is referred to as a group (X). Groups represented by other formulas are also described in the same manner. Moreover, the compound represented by Formula (1-1) is described as a compound (1-1). Groups represented by other formulas are also described in the same manner.

<Curable composition>
The curable composition of the present invention includes a curable material (a1), a curable material (a2), and a curing catalyst (b), and other additives (adhesion imparting agent, plasticizer) as necessary. , Dehydrating agents, fillers, anti-aging agents, coloring agents, thixotropic agents, etc.).
The curable composition of the present invention gives a cured product by crosslinking the polymer by hydrolysis and crosslinking reaction of hydrolyzable silicon groups in the presence of moisture even at a temperature around room temperature.

The curing speed, pot life, mechanical properties of the cured product, etc. of the curable composition are the types of the curable material (a1) and the curable material (a2), the curable material (a1) and the curable material (a2). The ratio and the type and ratio of each polymer (a21) (or polymer (a22)) when the curable material (a2) is two or more of the polymer (a21) (or polymer (a22)) It can adjust by selecting suitably.
The properties of the cured product also vary depending on various parameters such as the number of hydrolyzable silicon groups per molecule of the polymer, the molecular weight of the polymer per molecular terminal, and the molecular weight distribution of the polymer.

  The ratio of the curable material (a1) to the curable material (a2) (curable material (a1) / curable material (a2)) is 90/10 to 10/90 (from the point of adjusting the curing rate). Mass ratio) is preferable, and 80/20 to 10/90 (mass ratio) is more preferable. When the curable material (a1) / curable material (a2) is 90/10 to 10/90 (mass ratio), the balance of the pot life and the curing rate of the curable composition is excellent. When the curable material (a1) / curable material (a2) is 80/20 to 10/90 (mass ratio), the curing speed is high, and the mechanical properties such as elongation and peel strength of the cured product are further improved. To do.

(Curable material (a1))
The curable material (a1) has a group (Y1) containing 50 mol% or more of hydroxyl groups by modifying a polyoxyalkylene polyol having 4 or more hydroxyl groups (hereinafter referred to as polyol (a1)). It is 1 type (s) or 2 or more types of the polymer (a1) converted into group (X1) (however, the hydroxyl group which is not converted into group (X1) may be modified | denatured to another group).
_{-Si (OCH 3) 3 ··· (} Y1).

The group (X1) is a group represented by the following formula.
_{-O-A-Si (OCH 3} ) 3 ··· (X1).
However, A is a bivalent coupling group.

Examples of the group (X1) include groups (X1-1) to (X1-3) according to a modification method described later.
^{-O-A 1 -R 11 -CH (} R 12) CH (R 13) -A 2 -R 01 -Si (OCH 3) 3 ··· (X1-1),
_{^{-O-C (O) NH-}} R 02 -Si (OCH 3) 3 ··· (X1-2),
—O—C (O) NH—R ³¹ —A ³ —R ⁰³ —Si (OCH ₃ ) ₃ ... (X1-3).

A ¹ is a single bond, —C (O) —, —C (O) O—, or —C (O) NH—.
R ¹¹ is a single bond or a divalent organic group (—CH ₂ —, —CH ₂ CH ₂ —OC (O) —, etc.).
R ¹² and R ¹³ are a hydrogen atom or a monovalent organic group (such as —CH ₃ ).
A ² is a single bond or —S—.
R ⁰¹ is a single bond or a divalent organic group. The divalent organic group is preferably a divalent organic group having 1 to 17 carbon _atoms, -CH 2 _CH 2 CH ₂ - is more preferable.
R ⁰² and R ⁰³ are divalent organic groups, preferably a divalent organic group having 1 to 17 carbon atoms, and more preferably —CH ₂ CH ₂ CH ₂ —.
R ³¹ is a divalent organic group (an alkylene group, a cycloalkylene group, an arylene group, etc.).
A ³ represents —NHC (O) O—, —NHC (O) NH—, —NHC (O) N (R ³² ) —, —NHC (O) OC (O) — or —NHC (O) S—. It is.
R ³² is a monovalent organic group (an alkyl group, a cycloalkyl group, an aryl group, etc.).

Polyol (a1):
The polyol (a1) is a polyol having a polyoxyalkylene chain in the main chain. The polyol (a1) may have a structure other than the polyoxyalkylene chain (for example, a structure derived from an initiator).
The number of hydroxyl groups in the polyol (a1) is 4 or more, preferably 4-8, and more preferably 4-6. When the number of hydroxyl groups of the polyol (a1) is 4 to 6, the adhesiveness of the resulting cured product is further improved when the polymer (a1) obtained from the polyol and the polymer (a2) described later are used in combination. And the curing rate of the resulting curable composition is sufficiently high.

The polyol (a1) is preferably a polyol obtained by subjecting a cyclic ether to a ring-opening polymerization reaction using a polymerization catalyst in the presence of an initiator.
Examples of the cyclic ether include ethylene oxide, propylene oxide, butylene oxide, hexylene oxide, tetrahydrofuran and the like, and propylene oxide is preferable. A cyclic ether may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the initiator include compounds having 4 or more active hydrogen atoms in one molecule, and hydroxy compounds and / or unsaturated alcohols having 4 or more hydroxyl groups in one molecule are preferable, and 4 to 8 in one molecule. The hydroxyl compound having a hydroxyl group and / or an unsaturated alcohol is more preferable, and the hydroxyl compound having 4 to 6 hydroxyl groups in one molecule is particularly preferable.

Examples of the initiator include the following compounds.
Polyhydric alcohols: tetravalent alcohols (pentaerythritol, etc.), hexavalent alcohols (sorbitol, dipentaerythritol, etc.), octavalent alcohols (sucrose, etc.), etc.
Polyamines: ethylenediamine, hexamethylenediamine, etc.
Alkylene oxide adducts of the polyhydric alcohols,
Alkylene oxide adducts of the polyamines.
As the initiator, pentaerythritol and sorbitol are preferable from the viewpoint of adhesiveness of the obtained cured product. An initiator may be used individually by 1 type and may be used in combination of 2 or more type.

Examples of the polymerization catalyst include alkali metal compounds, double metal cyanide complexes, metal porphyrin complexes, and compounds having a P = N bond. Examples of the alkali metal compound include potassium compounds (potassium hydroxide, potassium methoxide, etc.) and cesium compounds (cesium hydroxide, etc.).
As the polymerization catalyst, a double metal cyanide complex, a cesium compound, or a compound having a P═N bond is preferable from the viewpoint of obtaining a polyol having a large molecular weight.

As the double metal cyanide complex, a complex mainly composed of zinc hexacyanocobaltate is preferable from the viewpoint of high polymerization activity, and an ether and / or alcohol complex of zinc hexacyanocobaltate is more preferable from the viewpoint of high activity. .
As the ether, ethylene glycol dimethyl ether (hereinafter referred to as glyme) or diethylene glycol dimethyl ether (hereinafter referred to as diglyme) is preferable, and glyme is more preferable from the viewpoint of easy handling of the complex during production.
As the alcohol, tert-butyl alcohol is preferable because a highly active polymerization catalyst can be obtained.
The amount of the double metal cyanide complex used is preferably 0.0001 to 0.1% by mass with respect to the obtained polyol (100% by mass), and is excellent in storage stability of the product and economically advantageous. 0.001-0.03 mass% is more preferable.

Examples of the cesium compound include cesium metal, cesium hydroxide, cesium carbonate, cesium alkoxide (such as cesium methoxide), and cesium hydroxide is preferable from the viewpoint of availability.
0.05-1.5 mass% is preferable with respect to the polyol (100 mass%) obtained, and, as for the usage-amount of a cesium compound, 0.1-1.0 mass% is more preferable.

  Examples of the compound having a P = N bond include a phosphazenium compound, a phosphazene compound, or a phosphine oxide compound, and a phosphazenium compound or a phosphine oxide compound is preferable from the viewpoint of availability.

Modification of polyol (a1):
Examples of the method for modifying the polyol (a1) include the following methods.
(I) The hydroxyl group of polyol (a1), or -OM (where M is an alkali metal) converted to hydroxyl group by reacting the hydroxyl group with an alkali metal alkoxide (such as sodium methoxide). 1-1) is allowed to act to convert the hydroxyl group to the group (X0-1), then the compound (1-2) is allowed to act on the group (X0-1) to convert the group (X0-1) to (X1- How to convert to 1).
W ¹ −R ¹¹ −C (R ¹² ) = CH (R ¹³ ) (1-1),
^{-O-A 1 -R 11 -C (} R 12) = CH (R 13) ··· (X0-1),
_{^{W 2 -R 01 -Si (OCH 3}} ) 3 ··· (1-2).
W ¹ is a halogen atom, —COOH, —COX (where X is a halogen atom), a hydroxyl group such as —NCO or a group capable of reacting with —OM, and W ² is a group in which R ⁰¹ is a single atom. In the case of a bond, it is a hydrogen atom, and when R ⁰¹ is a divalent organic group, it is —SH. R ¹¹ , R ¹² , R ¹³ , A ¹ , R ⁰¹ are the same as those described for the group (X1).

(Ii) A method of converting a hydroxyl group into a group (X1-2) by allowing the compound (2-1) to act on the hydroxyl group of the polyol (a1).
^{_{OCN-R 02 -Si (OCH 3}} ) 3 ··· (2-1).
However, R ⁰² is the same as that described for the group (X1).

Method (i):
Examples of the compound (1-1) include allyl chloride, acrylic acid, methacrylic acid, acrylic acid chloride, methacrylic acid chloride, 2-acryloyloxyethyl isocyanate, and 2-methacryloyloxyethyl isocyanate.
Examples of the compound (1-2) include the following compounds.
H-Si (OCH ₃ ) ₃ (1-2-1),
^{_{HS-R 01 -Si (OCH 3}} ) 3 ··· (1-2-2).

The reaction (hydrosilylation reaction) between the group (X0-1) and the compound (1-2-1) is carried out in the presence of a catalyst.
Examples of the catalyst include platinum-based catalysts (chloroplatinic acid, platinum metal, platinum chloride, platinum olefin complexes, etc.), rhodium-based catalysts, cobalt-based catalysts, palladium-based catalysts, or nickel-based catalysts, with platinum-based catalysts being preferred. .
30-150 degreeC is preferable and the temperature of hydrosilylation reaction has more preferable 60-120 degreeC.
The time for the hydrosilylation reaction is usually several hours.

Examples of the compound (1-2-2) include 3-mercaptopropyltrimethoxysilane.
The reaction between the group (X0-1) and the compound (1-2-2) may be performed using a radical polymerization initiator, or may be performed by radiation or heat without using a radical polymerization initiator.
Examples of radical polymerization initiators include peroxide polymerization initiators, azo polymerization initiators, redox polymerization initiators, metal compound catalysts, and the like. Specifically, 2,2′-azobisisobutyronitrile, Examples include 2,2′-azobis-2-methylbutyronitrile (hereinafter referred to as AMBN), benzoyl peroxide, tert-alkyl peroxyester, acetyl peroxide, diisopropyl peroxycarbonate, and the like.
The reaction temperature in the case of using a radical polymerization initiator varies depending on the decomposition temperature (half-life temperature) of the radical polymerization initiator, and is usually 20 to 200 ° C, preferably 50 to 150 ° C. The reaction time is preferably about several hours to several tens of hours.

Method (ii):
Examples of the compound (2-1) include 1-isocyanate methyltrimethoxysilane, 2-isocyanatoethyltrimethoxysilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatobutyltrimethoxysilane, 3-isocyanatepentyltrimethoxysilane, 1 -Isocyanatopropyltrimethoxysilane is mentioned, 1-isocyanatomethyltrimethoxysilane or 3-isocyanatopropyltrimethoxysilane is preferable, from the point that the curing rate of the curable composition is fast, and the elongation of the cured product is good 3-isocyanatopropyltrimethoxysilane is particularly preferred. As the compound (2-1), one type may be used alone, or two or more types may be used in combination.

The ratio (NCO / OH) of the isocyanate group (NCO) of the compound (2-1) to the hydroxyl group (OH) of the polyol (a1) is preferably 0.80 to 1.10 (molar ratio), 0.85 to 1.05 (molar ratio) is more preferable, and 0.95 to 1.05 (molar ratio) is particularly preferable.
If NCO / OH is 0.80 (molar ratio) or more, the reaction between the unreacted hydroxyl group and the group (Y1) hardly occurs, and the resulting curable composition has good storage stability. It is preferable to reduce the unreacted hydroxyl group by reacting with the compound (2-1) or the monoisocyanate compound.
If NCO / OH is 1.20 (molar ratio) or less, the cured product is soft and foaming is unlikely to occur due to the reaction between unreacted isocyanate groups and water. Unreacted isocyanate groups are preferably reduced by reacting with alcohols.

The reaction between the hydroxyl group of the polyol (a1) and the compound (2-1) may be performed using a urethanization catalyst.
Examples of the urethanization catalyst include organotin compounds (dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, etc.), metal catalysts such as bismuth compounds, and base catalysts such as organic amines.
1-100 ppm is preferable and, as for the quantity of a urethanization catalyst, 10-50 ppm is more preferable. If the amount of the urethanization catalyst is 100 ppm or less, the storage stability of the curable composition will be good. If the amount of the urethanization catalyst is 1 ppm or more, the urethanization reaction proceeds in a short time.

The reaction temperature varies depending on the presence or absence of the urethanization catalyst and the amount thereof, and is usually 50 to 200 ° C, preferably 70 to 150 ° C.
The reaction time is preferably about several hours.
Since the method (ii) has a small number of steps, the manufacturing time can be greatly shortened. Moreover, since there are no impurities by-produced during the process, complicated operations such as purification are unnecessary, and the obtained curable composition is very excellent in storage stability.

Polymer (a1):
The polymer (a1) may be used alone or in combination of two or more different in molecular weight, molecular weight distribution, number of hydroxyl groups of the starting polyol (a1), introduction rate of the group (X1) and the like. Also good.

  The introduction rate of the group (X1) in the polymer (a1) is 50 to 100 mol%, preferably 85 to 100 mol%, based on the hydroxyl group (100 mol%) of the starting polyol (a1). When the introduction ratio of the group (X1) is 50 mol% or more, the curing rate of the curable composition is high, the uniformity of curing is good, and the strength and durability of the cured product are high. The hydroxyl group that has not been converted to the group (X1) may be converted to another organic group.

  The number average molecular weight (Mn) of the polymer (a1) is preferably from 8000 to 50000, more preferably from 8000 to 38000, and particularly preferably from 12000 to 35000, from the viewpoint that a cured product having flexibility and good elongation can be obtained. When the number average molecular weight (Mn) of the polymer (a1) is 8000 or more, the obtained cured product is hardly brittle. If the number average molecular weight (Mn) of a polymer (a1) is 50000 or less, the viscosity of a polymer (a1) will become low and the workability | operativity at the time of construction of a curable composition and handling property will become favorable.

The molecular weight distribution of the polymer (a1) is preferably 1.6 or less, more preferably 1.5 or less, and particularly preferably 1.4 or less.
When the molecular weight distribution of the polymer (a1) is 1.6 or less, the elongation at break of the cured product can be improved and the strength can be improved while maintaining the elastic modulus of the cured product.
The lower limit of the molecular weight distribution of the polymer (a1) is 1.0.

In addition, when comparing a curable composition containing a polymer having a narrow molecular weight distribution and a curable composition containing a polymer having the same number average molecular weight and a wide molecular weight distribution, the former is a ratio of a polymer having a small molecular weight. Therefore, the elongation at break and the maximum stress of the cured product are larger than those of the latter, and the viscosity of the curable composition is low, so that the handleability is excellent.
The polymer (a1) having a narrow molecular weight distribution can be stably produced by modifying the polyol (a1) obtained by using a double metal cyanide complex as a polymerization catalyst and converting the hydroxyl group to a group (X1). .
In addition, even if the molecular weight distribution of the polymer (a1) exceeds 1.6, the curable composition of the present invention containing the polymer (a1) and the curing containing the polymer having three groups (X1) When compared with the curable composition, the curable composition of the present invention is greatly improved in the maximum tensile stress and elongation at break of the cured product.

The molecular weight distribution of the polymer (a1) can be adjusted by the following method.
(I) A method for adjusting the type and amount of the polymerization catalyst used in the production of the polyol (a1).
(Ii) A method for optimizing the polymerization conditions of the cyclic ether.
(Iii) A method of combining two or more kinds of polymers (a1) having different molecular weights and molecular weight distributions.

The molecular weight distribution of the polymer (a1) is represented by the following formula.
Molecular weight distribution = mass average molecular weight (Mw) / number average molecular weight (Mn).
The mass average molecular weight (Mw) and the number average molecular weight of the polymer (a1) are molecular weights in terms of polystyrene measured by gel permeation chromatography (hereinafter referred to as GPC).

(Curable material (a2))
The curable material (a2) is a group having a group represented by the following formula (Y) by modifying at least 50 mol% of the hydroxyl group by modifying polyoxyalkylene diol (hereinafter referred to as diol (a21)). Polymer (a21) converted to (X) (however, a hydroxyl group that is not converted to group (X) may be modified with another group) and / or a polyoxyalkylene monool having an unsaturated group (hereinafter, The unsaturated monool (a22) is modified to convert 50 mol% or more of the total of unsaturated groups and hydroxyl groups into groups (X) having groups represented by the following formula (Y). 1 type or 2 types or more of the polymer (a22) (which may have an unsaturated group and / or a hydroxyl group that cannot be converted to the group (X)), and the curable material (a2) All groups present (X) Of 100 mol%), the group (X1) is not less than 50 mol%.
-Si (OR) ₃ ... (Y).

R is an organic group having 1 to 6 carbon atoms. Examples of the organic group include an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, and an aryl group, and an alkyl group is preferable.
Examples of the alkyl group include a methoxy group and an ethoxy group.
Examples of the alkenyl group include a vinyl group, a propenyl group, an allyl group, and an isopropenyl group.
Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group.
Examples of the aryl group include a phenyl group.
R is preferably a methyl group or an ethyl group, more preferably a methyl group, from the viewpoint of curing speed.

The group (X) is represented by the following formula.
-Q-A-Si (OR) ₃ ... (X).
However, Q is —O— when a hydroxyl group is converted, and —CH (R ⁴¹ ) CH (R ⁴² ) — when an unsaturated group is converted, and R ⁴¹ and R ⁴² are hydrogen. It is an atom or a monovalent organic group (—CH ₃ or the like). A is the same as the description of the group (X1), and R is the same as the description of the group (Y).

Examples of the group (X) include groups (X-1) to (X-4) according to a modification method described later.
^{-O-A 1 -R 11 -CH (} R 12) CH (R 13) -A 2 -R 01 -Si (OR) 3 ··· (X-1),
—O—C (O) NH—R ⁰² —Si (OR) ₃ (X-2),
^{-O-C (O) NH-} R 31 -A 3 -R 03 -Si (OR) 3 ··· (X-3),
^{-CH (R 41) CH (R} 42) -A 2 -R 01 -Si (OR) 3 ··· (X-4).
However, R is the same as the description of the group (Y), and A ¹ , R ¹¹ , R ¹² , R ¹³ , A ² , R ⁰¹ , R ⁰² , R ³¹ , A ³ , R ⁰³ are the group (X1 ), And R ⁴¹ and R ⁴² are the same as those described for the group (X).

Diol (a21):
The diol (a21) is a diol having a polyoxyalkylene chain in the main chain. The diol (a21) may have a structure other than the polyoxyalkylene chain (for example, a structure derived from an initiator).

The diol (a21) is preferably a polyol obtained by subjecting a cyclic ether to a ring-opening polymerization reaction using a polymerization catalyst in the presence of an initiator.
Examples of the cyclic ether include ethylene oxide, propylene oxide, butylene oxide, hexylene oxide, tetrahydrofuran and the like, and propylene oxide is preferable. A cyclic ether may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the initiator include a compound having two active hydrogen atoms in one molecule. A hydroxy compound and / or an unsaturated alcohol having two hydroxyl groups in one molecule are preferable, and two hydroxyl groups are contained in one molecule. Hydroxyl compounds are particularly preferred.
As initiators, ethylene glycol, propanediol (propylene glycol), dipropylene glycol, butanediol, hexamethylene glycol, hydrogenated bisphenol A, neopentyl glycol, polybutadiene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and these compounds And alkylene oxide adducts thereof. An initiator may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymerization catalyst include those used for the production of the polyol (a1). From the viewpoint of obtaining a diol having a large molecular weight, a double metal cyanide complex, a cesium compound, or a compound having a P = N bond is preferable.

Modification of diol (a21):
Examples of the method for modifying the diol (a21) include the same method as that for the polyol (a1) described above.
(I) Hydroxyl group of diol (a21), or -OM (where M is an alkali metal) converted to hydroxyl group by reacting the hydroxyl group with an alkali metal alkoxide (such as sodium methoxide). 1-1) is allowed to act to convert the hydroxyl group to the group (X0-1), then the compound (1-3) is allowed to act on the group (X0-1) to convert the group (X0-1) to (X— How to convert to 1).
W ¹ −R ¹¹ −C (R ¹² ) = CH (R ¹³ ) (1-1),
^{-O-A 1 -R 11 -C (} R 12) = CH (R 13) ··· (X0-1),
_{^{W 2 -R 01 -Si (OR)}} 3 ··· (1-3).
However, R is the same as the description of the group (Y), and W ¹ , W ² , R ¹¹ , R ¹² , R ¹³ , A ¹ and R ⁰¹ are the same as the description of the group (X1).

(Ii) A method of converting the hydroxyl group into the group (X-2) by allowing the compound (2-2) to act on the hydroxyl group of the diol (a21).
_{^{OCN-R 02 -Si (OR)}} 3 ··· (2-2).
However, R is the same as the description of the group (Y), and R ⁰² is the same as the description of the group (X1).

(Iii) The compound (3-1) is allowed to act on the hydroxyl group of the diol (a21) to convert the hydroxyl group to a group (X0-3), and then the compound (3-3) is allowed to act on the group (X0-3). The group (X0-3) to (X-3).
OCN-R ³¹ -NCO (3-1),
^{-O-C (O) NH-} R 31 -NCO ··· (X0-3),
_{^{W 3 -R 03 -Si (OR)}} 3 ··· (3-3).
^{However, W} 3 ^{_{are, -OH, -NH 2, -NHR 32}} , it is -COOH or -SH,. R is the same as the description of the group (Y), and R ³¹ and R ⁰³ are the same as the description of the group (X1).

Method (i):
Examples of the compound (1-3) include the following compounds.
H-Si (OR) ₃ (1-3-1),
HS-R ⁰¹ -Si (OR) ₃ (1-3-2).
Examples of the compound (1-3-2) include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.
The reaction conditions in the method (i) are the same as those in the modification method of the polyol (a1).

Method (ii):
Examples of the compound (2-2) include 1-isocyanate methyltrimethoxysilane, 2-isocyanateethyltrimethoxysilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatebutyltrimethoxysilane, 3-isocyanatepentyltrimethoxysilane, 1 -Isocyanatomethyltriethoxysilane, 2-isocyanatoethyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 1-isocyanatopropyltrimethoxysilane, 1-isocyanatopropyltriethoxysilane, 1-isocyanatemethyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane or 3-isocyanatopropyltriethoxysilane is preferred, Tokishishiran, 3-isocyanate propyl trimethoxysilane is more preferred, a point high curing speed of the curable composition, and from the point elongation of the cured product is good, 3-isocyanate propyl trimethoxysilane is particularly preferred. As the compound (2-2), one type may be used alone, or two or more types may be used in combination.
The reaction conditions in the method (ii) are the same as the reaction conditions in the method for modifying the polyol (a1).

Method (iii):
Examples of the compound (3-1) include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and the like.
The amount of the compound (3-1) is set so that the isocyanate group becomes excessive with respect to the hydroxyl group of the polyol (a1).

  Examples of the compound (3-3) include aminosilane compounds (N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.), mercaptosilane compounds (3 -Mercaptopropyltrimethoxysilane etc.).

The reaction between the isocyanate group of the group (X0-3) and the compound (3-3) may be performed using a urethanization catalyst.
The reaction temperature varies depending on the presence or absence of the urethanization catalyst and the amount thereof, and is usually 20 to 200 ° C., preferably 50 to 150 ° C.
The reaction time is preferably about several hours.

Polymer (a21):
As the polymer (a21), one type may be used alone, or two or more types having different molecular weight, molecular weight distribution, type of group (X), introduction rate, and the like may be used in combination.

  The introduction rate of the group (X) in the polymer (a21) is 50 to 100 mol%, preferably 70 to 100 mol%, based on the hydroxyl group (100 mol%) of the starting diol (a21). When the introduction ratio of the group (X) is 50 mol% or more, the curing rate of the curable composition is high, the uniformity of curing is good, and the strength and durability of the cured product are high. The hydroxyl group that has not been converted to the group (X) may be converted to another organic group.

  The number average molecular weight (Mn) of the polymer (a21) is preferably from 8000 to 50000, more preferably from 8000 to 38000, and particularly preferably from 12000 to 35000, from the viewpoint of obtaining a cured product having flexibility and good elongation. When the number average molecular weight (Mn) of the polymer (a21) is 8000 or more, the obtained cured product is hardly brittle. If the number average molecular weight (Mn) of a polymer (a21) is 50000 or less, the viscosity of a polymer (a21) will become low and the workability | operativity at the time of construction of a curable composition and handling property will become favorable.

The molecular weight distribution of the polymer (a21) is preferably 1.6 or less, more preferably 1.5 or less, and particularly preferably 1.4 or less.
If the molecular weight distribution of the polymer (a21) is 1.6 or less, the elongation at break of the cured product can be improved and the strength can be improved while maintaining the elastic modulus of the cured product.
The lower limit of the molecular weight distribution of the polymer (a21) is 1.0.

In addition, when comparing a curable composition containing a polymer having a narrow molecular weight distribution and a curable composition containing a polymer having the same number average molecular weight and a wide molecular weight distribution, the former is a ratio of a polymer having a small molecular weight. Therefore, the elongation at break and the maximum stress of the cured product are larger than those of the latter, and the viscosity of the curable composition is low, so that the handleability is excellent.
The polymer (a21) having a narrow molecular weight distribution can be stably produced by modifying the diol (a21) obtained by using a double metal cyanide complex as a polymerization catalyst and converting the hydroxyl group to a group (X). .
Even if the molecular weight distribution of the polymer (a21) exceeds 1.6, the curable composition of the present invention containing the polymer (a21) and the curing containing the polymer having three groups (X) When compared with the curable composition, the curable composition of the present invention is greatly improved in the maximum tensile stress and elongation at break of the cured product.

The molecular weight distribution of the polymer (a21) can be adjusted by the following method.
(I) A method for adjusting the type and amount of the polymerization catalyst used in the production of the diol (a21).
(Ii) A method for optimizing the polymerization conditions of the cyclic ether.
(Iii) A method of combining two or more kinds of polymers (a21) having different molecular weights and molecular weight distributions.

The molecular weight distribution of the polymer (a21) is represented by the following formula.
Molecular weight distribution = mass average molecular weight (Mw) / number average molecular weight (Mn).
The mass average molecular weight (Mw) and number average molecular weight of the polymer (a21) are molecular weights in terms of polystyrene measured by GPC.

Unsaturated monool (a22):
The unsaturated monool (a22) is a monool having a polyoxyalkylene chain in the main chain and an unsaturated group at the terminal. The unsaturated monool (a22) may have a structure other than the polyoxyalkylene chain (for example, a structure derived from an initiator).

The unsaturated monool (a22) is preferably a monool obtained by subjecting a cyclic ether to a ring-opening polymerization reaction using a polymerization catalyst in the presence of an initiator.
Examples of the cyclic ether include ethylene oxide, propylene oxide, butylene oxide, hexylene oxide, tetrahydrofuran and the like, and propylene oxide is preferable. A cyclic ether may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the initiator include unsaturated monoalcohol (allyl alcohol, methallyl alcohol, etc.). An initiator may be used individually by 1 type and may be used in combination of 2 or more type.
Examples of the polymerization catalyst include those used for the production of the polyol (a1). From the viewpoint of obtaining a monool having a large molecular weight, a double metal cyanide complex, a cesium compound, or a compound having a P = N bond is preferable.

Modification of unsaturated monool (a22):
Examples of the method for modifying the unsaturated monool (a22) include the same method as the method (i) in the above-described method for modifying the diol (a21).
(I) Hydroxyl group of unsaturated monool (a22) or -OM (where M is an alkali metal) in which the hydroxyl group is converted by the action of an alkali metal alkoxide (such as sodium methoxide) on the hydroxyl group. Then, the compound (1-1) is allowed to act to convert the hydroxyl group to the group (X0-1), and then the compound (1-3) is converted into the unsaturated group of the group (X0-1) and the unsaturated monool (a22). To convert the group (X0-1) and the unsaturated group into the group (X-1) and the group (X-4).
W ¹ −R ¹¹ −C (R ¹² ) = CH (R ¹³ ) (1-1),
^{-O-A 1 -R 11 -C (} R 12) = CH (R 13) ··· (X0-1),
_{^{W 2 -R 01 -Si (OR)}} 3 ··· (1-3).
However, R is the same as the description of the group (Y), and W ¹ , W ² , R ¹¹ , R ¹² , R ¹³ , A ¹ and R ⁰¹ are the same as the description of the group (X1).
The reaction conditions in the method (i) are the same as those in the method for modifying the diol (a21).

Polymer (a22):
As the polymer (a22), one type may be used alone, or two or more types having different molecular weight, molecular weight distribution, type of group (X), introduction rate, and the like may be used in combination.

  The introduction rate of the group (X) in the polymer (a22) is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, based on the hydroxyl group (100 mol%) of the unsaturated monool (a22) of the raw material. preferable. When the introduction ratio of the group (X) is 50 mol% or more, the curing rate of the curable composition is high, the uniformity of curing is good, and the strength and durability of the cured product are high. The hydroxyl group that has not been converted to the group (X) may be converted to another organic group.

  The number average molecular weight (Mn) of the polymer (a22) is preferably from 8000 to 50000, more preferably from 8000 to 38000, and particularly preferably from 12000 to 35000, from the viewpoint that a cured product having flexibility and good elongation can be obtained. When the number average molecular weight (Mn) of the polymer (a22) is 8000 or more, the obtained cured product is hardly brittle. If the number average molecular weight (Mn) of a polymer (a22) is 50000 or less, the viscosity of a polymer (a22) will become low and the workability | operativity at the time of construction of a curable composition and handling property will become favorable.

The molecular weight distribution of the polymer (a22) is preferably 1.6 or less, more preferably 1.5 or less, and particularly preferably 1.4 or less.
When the molecular weight distribution of the polymer (a22) is 1.6 or less, the elongation at break of the cured product can be improved and the strength can be improved while maintaining the elastic modulus of the cured product.
The lower limit of the molecular weight distribution of the polymer (a22) is 1.0.

In addition, when comparing a curable composition containing a polymer having a narrow molecular weight distribution and a curable composition containing a polymer having the same number average molecular weight and a wide molecular weight distribution, the former is a ratio of a polymer having a small molecular weight. Therefore, the elongation at break and the maximum stress of the cured product are larger than those of the latter, and the viscosity of the curable composition is low, so that the handleability is excellent.
The polymer (a22) having a narrow molecular weight distribution is stabilized by modifying the unsaturated monool (a22) obtained by using the double metal cyanide complex as a polymerization catalyst and converting the hydroxyl group to the group (X). Can be manufactured.
In addition, even if the molecular weight distribution of the polymer (a22) exceeds 1.6, the curable composition of the present invention containing the polymer (a22) and the curing containing the polymer having three groups (X) When compared with the curable composition, the curable composition of the present invention is greatly improved in the maximum tensile stress and elongation at break of the cured product.

The molecular weight distribution of the polymer (a22) can be adjusted by the following method.
(I) A method for adjusting the type and amount of the polymerization catalyst used in the production of the unsaturated monool (a22).
(Ii) A method for optimizing the polymerization conditions of the cyclic ether.
(Iii) A method of combining two or more polymers (a22) having different molecular weights and molecular weight distributions.

The molecular weight distribution of the polymer (a22) is represented by the following formula.
Molecular weight distribution = mass average molecular weight (Mw) / number average molecular weight (Mn).
The mass average molecular weight (Mw) and the number average molecular weight of the polymer (a22) are molecular weights in terms of polystyrene measured by GPC.

Ratio of group (X1):
Of all the groups (X) (100 mol%) present in the curable material (a2), the group (X1) needs to be 50 mol% or more. The proportion of the group (X1) is preferably 60 mol% or more, more preferably 70 mol% or more, and particularly preferably 100 mol%.
When the ratio of the group (X1) is less than 100 mol%, the remaining group (X) is preferably a group (X2) having a group (Y2) from the viewpoint of curing rate.
_{-Si (OCH 2 CH 3) 3} ··· (Y2).

Examples of the method for adjusting the ratio of the group (X1) include the following methods, and the method (i) is preferable from the viewpoint of easy adjustment.
(I) By modifying the diol (a21) to modify the polymer (a21-1) and / or the unsaturated monool (a22) in which the hydroxyl group is converted to the group (X1) only, the unsaturated group and By modifying one or more of the polymers (a22-1) in which the hydroxyl group is converted only to the group (X1) and the diol (a21), the hydroxyl group is converted into the group (X) (however, the group (X1) is excluded). By modifying the polymer (a21-2) and / or the unsaturated monool (a22) converted to, the unsaturated group and the hydroxyl group were converted to the group (X) (excluding the group (X1)). A method of combining one or more polymers (a22-2).
(Ii) By modifying the diol (a21) with a compound having the group (Y1) and a compound having the group (Y) (excluding the group (Y1)), the hydroxyl group is simultaneously converted into the group (X1) or the group The polymer (a21-3) and / or the unsaturated monool (a22) converted into (X) (excluding the group (X1)), the compound having the group (Y1) and the group (Y) (provided that , A polymer having an unsaturated group and a hydroxyl group simultaneously converted to a group (X1) or a group (X) (excluding the group (X1)) by modification with a compound having a group (excluding the group (Y1)). A method of using one or more of (a22-3).

(Other curable materials)
The curable composition of the present invention includes other curable materials having a hydrolyzable silicon group in addition to the curable material (a1) and the curable material (a2), as long as the effects of the present invention are not impaired. May be.

Other curable materials include the following.
(I) A polymer in which a hydroxyl group is converted to a group (X) by modifying a polyoxyalkylene polyol having 3 hydroxyl groups (however, it may have a hydroxyl group that is not converted to a group (X)). 1 type or 2 types or more.
(Ii) A polymer in which a hydroxyl group is converted to a group (X) (however, excluding the group (X1)) by modifying the polyol (a1) (however, it has a hydroxyl group that is not converted to the group (X)). 1 type or 2 types or more.
(Iii) A polymer (a21) in which a hydroxyl group is converted into a group (X) by modifying the diol (a21) (however, it may have a hydroxyl group that is not converted into the group (X)) and / or. Polymer (a22) in which unsaturated group and hydroxyl group are converted to group (X) by modifying unsaturated monool (a22) (however, it has unsaturated group and / or hydroxyl group that is not converted to group (X)) 1 or 2 or more types), and among all the groups (X) (100 mol%) present in the curable material, the group (X1) is less than 50 mol%. is there.

(Curing catalyst (b))
The curing catalyst (b) is a compound that promotes hydrolysis and / or crosslinking reaction of the group (X).
Examples of the curing catalyst (b) include the following compounds.
Organic stannous carboxylates: dibutyltin diacetate, dibutyltin dilaurate, dioctyltin _{dilaurate, (n-C 4 H 9} ) 2 Sn (OCOCH = CHCOOCH 3) 2, (n-C 4 H 9) 2 Sn (OCOCH = CHCOO (n _{-C 4 H 9)) 2,} (n-C 8 H 17) 2 Sn (OCOCH = CHCOOCH 3) 2, (n-C 8 H 17) 2 Sn (OCOCH = CHCOO (n-C 4 H 9)) _{2, (n-C 8 H} 17) 2 Sn (OCOCH = CHCOO (iso-C 8 H 17)) 2 or the like,
Sulfur-containing organic tin _{compounds: (n-C 4 H 9} ) 2 Sn (SCH 2 COO), (n-C 8 H 17) 2 Sn (SCH 2 COO), (n-C 8 H 17) 2 Sn (SCH _{2 CH 2 COO), (n} -C 8 H 17) 2 Sn (SCH 2 COOCH 2 CH 2 OCOCH 2 S), (n-C 4 H 9) 2 Sn (SCH 2 COO (iso-C 8 H 17) ) ₂ , (n-C ₈ H ₁₇ ) ₂ Sn (SCH ₂ COO (iso-C ₈ H ₁₇ )) ₂ , (n-C ₈ H ₁₇ ) ₂ Sn (SCH ₂ COO (n-C ₈ H ₁₇ ) ) ₂ , (n-C ₄ H ₉ ) ₂ SnS, etc.
Organic tin _{oxide: (n-C 4 H 9} ) 2 SnO, (n-C 8 H 17) 2 SnO or the like,
A reaction product of the organotin oxide with an ester compound (ethyl silicate, dimethyl maleate, diethyl maleate, dioctyl maleate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, etc.);
Kiretosuzu _{compounds: (n-C 4 H 9} ) 2 Sn (acac) 2, (n-C 8 H 17) 2 Sn (acac) 2, (n-C 4 H 9) 2 Sn (OC 8 H 17) ( _{acac), (n-C 4} H 9) 2 Sn (OC (CH 3) CHCO 2 C 2 H 5) 2, (n-C 8 H 17) 2 Sn (OC (CH 3) CHCO 2 C 2 H 5 ) ₂ , (n-C ₄ H ₉ ) ₂ Sn (OC ₈ H ₁₇ ) (OC (CH ₃ ) CHCO ₂ C ₂ H ₅ ) and the like (where acac is an acetylacetonato ligand and OC (CH ₃ ) CHCO ₂ C ₂ H ₅ is an ethyl acetoacetate ligand)),
A reaction product of the chelated tin compound and alkoxysilane (tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, etc.);
Tetravalent tin compounds: -SnOSn--containing organic tin compound _{{(n-C 4 H 9} ) 2 (CH 3 COO) SnOSn (OCOCH 3) (n-C 4 H 9) 2, (n-C 4 H _{9) 2 (CH 3 O)} SnOSn (OCH 3) (n-C 4 H 9) 2 and the like. }etc,

Divalent tin carboxylates: tin 2-ethylhexanoate, tin n-octylate, tin naphthenate, tin stearate, etc.
Acidic compounds: octylic acid, phosphoric acid, p-toluenesulfonic acid, phthalic acid, etc.
Aliphatic monoamines: butylamine, hexylamine, octylamine, decylamine, laurylamine, etc.
Aliphatic diamines, ethylenediamine, hexanediamine, etc.
Aliphatic polyamines: diethylenetriamine, triethylenetetramine, tetraethylenepentamine, etc.
Heterocyclic amines: piperidine, piperazine, etc.
Aromatic amines: metaphenylenediamine, etc.
Alkanolamines: monoethanolamine, diethanolamine, triethanolamine, etc.
Trialkylamines: triethylamine, etc.
Various modified amines: epoxy resin curing agents, etc.

  A curing catalyst (b) may be used individually by 1 type, and may be used in combination of 2 or more type. When combining two or more kinds, from the viewpoint of curability, a metal-containing compound (divalent tin carboxylate, organotin carboxylate, reaction product of organotin oxide and ester compound, etc.) and an amine compound (aliphatic monoamine) Etc.) is preferred.

  The amount of the curing catalyst (b) is preferably 0.001 to 10 parts by mass with respect to a total of 100 parts by mass of the curable material (a1) and the curable material (a2). When the amount of the curing catalyst (b) is 0.001 part by mass or more, the curing rate of the curable composition can be effectively accelerated. When the amount of the curing catalyst (b) is 10 parts by mass or less, problems such as foaming of the cured product and a decrease in durability can be suppressed.

In addition, when a curable composition contains another curable material, the quantity of a curing catalyst (b) is 100 mass parts in total of a curable material (a1), a curable material (a2), and another curable material. On the other hand, 0.001-10 mass parts is preferable.
The curable composition of the present invention may be a one-pack type in which the curing catalyst (b) is added in advance and stored under dehydration conditions, and reacted with moisture in the atmosphere at the time of curing. It is good also as a two-component type which mixes and hardens (b).

(Other additives)
The curable composition of the present invention may contain an adhesiveness imparting agent, a plasticizer, a dehydrating agent, a filler, an antiaging agent, a colorant, a thixotropic property imparting agent, and the like as necessary.

Adhesive agent:
The adhesiveness imparting agent is for improving the adhesiveness with the substrate.
Examples of the adhesion imparting agent include (meth) acryloyloxy group-containing silanes, amino group-containing silanes, mercapto group-containing silanes, epoxy group-containing silanes, carboxyl group-containing silanes, and so-called silane coupling agents. Amino group-containing silanes or epoxy group-containing silanes are preferred.

  Examples of amino group-containing silanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N -(2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, N- (N-vinylbenzyl-2) -Aminoethyl) -3-aminopropyltrimethoxysilane, 3-anilinopropyltrimethoxysilane and the like.

Examples of the epoxy group-containing silanes include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 3-glycidyloxypropyltriethoxysilane.
As the adhesiveness imparting agent, one kind may be used alone, or two or more kinds may be used in combination. The amount of the adhesion-imparting agent is preferably 30 parts by mass or less with respect to 100 parts by mass in total of the curable material (a1), the curable material (a2), and other curable materials. If the amount of the adhesion-imparting agent is 30 parts by mass or less, the cured product will not be too hard and the flexibility of the cured product will be good.

An epoxy resin may be used together with an adhesiveness imparting agent, and an epoxy resin curing agent may be further used as necessary.
Examples of the epoxy resin include bisphenol A-diglycidyl ether type epoxy resin, bisphenol F-diglycidyl ether type epoxy resin, flame retardant type epoxy resin (tetrabromobisphenol A-glycidyl ether type epoxy resin, etc.), novolac type epoxy resin, Hydrogenated bisphenol A type epoxy resin, glycidyl ether type epoxy resin of bisphenol A-propylene oxide adduct, diglycidyl ester type epoxy resin (glycidyl 4-glycidyloxybenzoate, diglycidyl phthalate, diglycidyl tetrahydrophthalate, hexahydrophthalic acid Diglycidyl, etc.), m-aminophenol epoxy resin, diaminodiphenylmethane epoxy resin, urethane-modified epoxy resin, various alicyclic epoxy resins, N, -Diglycidylaniline, N, N-diglycidyl-o-toluidine, triglycidyl isocyanurate, polyalkylene glycol diglycidyl ether, glycidyl ether of polyhydric alcohol (glycerin, etc.), hydantoin type epoxy resin, unsaturated polymer (petroleum resin) Etc.)).

  As for the quantity of an epoxy resin, 100 mass parts or less are preferable with respect to a total of 100 mass parts of curable material (a1), curable material (a2), and another curable material. If the quantity of an epoxy resin is 100 mass parts or less, a hardened | cured material will not become hard too much and the softness | flexibility of a hardened | cured material will become favorable.

Examples of the epoxy resin curing agent include the following compounds.
Amines: triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, m-xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, 2,4,6-tris (Dimethylaminomethyl) phenol, etc.
Salts of amines,
Blocked amines: Ketimine compounds of amines, etc.
Polyamide resin,
Imidazoles,
Dicyandiamides,
Boron trifluoride complex compounds,
Carboxylic anhydride: phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dodecenyl succinic anhydride, pyromellitic anhydride, etc.
Phenoxy resin,
Carboxylic acids,
Alcohols,
Polyalkylene oxide polymer having an average of at least one group capable of reacting with an epoxy group in the molecule: terminal aminated polyoxypropylene glycol, terminal carboxylated polyoxypropylene glycol, etc.
Liquid terminal functional group-containing polymer: polymer whose end is modified with a functional group (hydroxyl group, carboxyl group, amino group, etc.) (polybutadiene, hydrogenated polybutadiene, acrylonitrile-butadiene copolymer, acrylic polymer, etc.). etc.
As for the quantity of an epoxy resin hardening | curing agent, 300 mass parts or less are preferable with respect to 100 mass parts of epoxy resins.

Plasticizer:
Examples of the plasticizer include the following compounds.
Phthalate esters: Dioctyl phthalate, dibutyl phthalate, butyl benzyl phthalate, etc.
Aliphatic carboxylic acid esters: dioctyl adipate, bis (2-methylnonyl) succinate, dibutyl sebacate, butyl oleate, etc.
Alcohol esters: pentaerythritol ester, etc.
Phosphate esters: trioctyl phosphate, tricresyl phosphate, etc.
Epoxy plasticizers: epoxidized soybean oil, dioctyl 4,5-epoxyhexahydrophthalate, benzyl epoxy stearate, etc.
Chlorinated paraffin,
Polyester plasticizers: polyesters obtained by reacting dibasic acids and dihydric alcohols, etc.
Polyethers: polyoxypropylene glycol, its derivatives, etc.
Styrene oligomers: poly-α-methylstyrene, polystyrene, etc.
Oligomers: polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene, polyisoprene, polybutene, hydrogenated polybutene, epoxidized polybutadiene and the like.

A plasticizer may be used individually by 1 type and may be used in combination of 2 or more type.
As for the quantity of a plasticizer, 300 mass parts or less are preferable with respect to a total of 100 mass parts of curable material (a1), curable material (a2), and another curable material.
In addition, when using the curable composition of this invention for uses, such as an adhesive agent, the direction which does not use a plasticizer may make the adhesive force of hardened | cured material and a base material high.

Dehydrating agent:
A dehydrating agent is for improving the storage stability of a curable composition. When the curable composition is a one-component type, it is preferable to use a dehydrating agent.
Examples of the dehydrating agent include the following compounds.
Alkyl orthoformates: methyl orthoformate, ethyl orthoformate, etc.
Alkyl orthoacetates: methyl orthoacetate, ethyl orthoacetate, etc.
Hydrolyzable organosilicon compounds: methyltrimethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, etc.
Hydrolyzable organic titanium compounds.

A dehydrating agent may be used individually by 1 type, and may be used in combination of 2 or more type.
As the dehydrating agent, vinyltrimethoxysilane or tetraethoxysilane is preferable because it is easily available and has a high dehydrating effect.
The amount of the dehydrating agent is preferably 30 parts by mass or less with respect to 100 parts by mass in total of the curable material (a1), the curable material (a2), and other curable materials. If the quantity of a dehydrating agent is 30 mass parts or less, the fall of the hardening rate of a curable composition will be suppressed.

filler:
Examples of the filler include a powder filler and a fibrous filler.
Examples of the powder filler include calcium carbonate surface-treated with fatty acid or resin acid-based organic substance, calcium carbonate further refined into calcium carbonate having an average particle diameter of 1 μm or less, and an average particle diameter of 1 to 1 produced by a precipitation method. 3 μm light calcium carbonate, heavy calcium carbonate with an average particle diameter of 1 to 20 μm, other calcium carbonates, fumed silica, precipitated silica, anhydrous silicic acid, hydrous silicic acid, carbon black, magnesium carbonate, diatomaceous earth, calcined Clay, clay, talc, titanium oxide, bentonite, organic bentonite, ferric oxide, zinc oxide, activated zinc white, shirasu balloon, glass balloon, plastic balloon, wood flour, pulp, cotton chip, mica, walnut flour, rice flour Graphite, aluminum fine powder, flint powder and the like. By using a plastic balloon, the specific gravity of the curable composition can be reduced.
Examples of the fibrous filler include glass fiber, glass filament, carbon fiber, Kevlar fiber, and polyethylene fiber.

A filler may be used individually by 1 type and may be used in combination of 2 or more type.
The amount of the filler is preferably 600 parts by mass or less, and more preferably 50 to 250 parts by mass with respect to 100 parts by mass in total of the curable material (a1), the curable material (a2), and other curable materials.

Anti-aging agent:
The anti-aging agent is for increasing the weather resistance and light resistance of the curable composition.
Examples of the anti-aging agent include anti-aging agents (antioxidants, ultraviolet absorbers, light stabilizers, etc.) used for polyurethane resins. Examples of the antioxidant include hindered amine-based, benzotriazole-based, benzophenone-based, benzoate-based, cyanoacrylate-based, acrylate-based, hindered phenol-based, phosphorus-based, and sulfur-based various antioxidants.

Colorant:
Examples of the colorant include inorganic pigments (iron oxide, chromium oxide, titanium oxide, etc.), organic pigments (phthalocyanine blue, phthalocyanine green, etc.) and the like.

Thixotropic agent:
The thixotropic agent is used as an anti-sagging agent.
Examples of the thixotropic agent include hydrogenated castor oil and fatty acid amide.
The amount of the thixotropic agent is appropriately selected so as to obtain a desired sagging-preventing property.

Other additives:
Examples of other additives include fungicides and foaming agents.

In the curable composition of this invention demonstrated above, since it contains curable material (a1), curable material (a2), and a curing catalyst (b), it hardens | cures rather than the conventional curable composition. A cured product having a high speed and good strength and elongation can be obtained.
That is, a tetrafunctional or higher functional branched polymer having a trimethoxysilyl group as a hydrolyzable silicon group at the molecular end and a trialkoxysilyl group (provided that the trimethoxysilyl group is 50 mol% or more at the molecular end. The curable composition containing a linear polymer having) is compared with a curable composition containing a trifunctional branched polymer having a trimethoxysilyl group as a hydrolyzable silicon group at the molecular end. Thus, the curing rate of the curable composition is extremely high, and the obtained cured product has high strength and large elongation.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited only to these Examples.
Examples 7 to 17, 22 to 31 are examples, and examples 18 to 21 and 32 are comparative examples.

(Mass average molecular weight, number average molecular weight, molecular weight distribution)
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer were measured by GPC, and the molecular weight distribution (Mw / Mn) was determined. Specifically, two TSK Multipore HXL-M (manufactured by Tosoh Corporation) were connected in series as a GPC column, and tetrahydrofuran was used as a mobile phase, and measurement was performed at 40 ° C. Moreover, Mw and Mn were calculated | required as a polystyrene conversion molecular weight from the analytical curve created using the polystyrene standard sample (Polymer Laboratories company make, PS-2) with known molecular weight.

(Tensile shear strength)
In accordance with JIS K6850, a curable composition was applied to an aluminum test piece having a length of 100 mm and a width of 25 mm so that the sample application surface had a length of 25 mm, a width of 25 mm, and a thickness of 1 mm. Was made.
The specimen was placed in a curing device under conditions of a temperature of 23 ° C. and a relative humidity of 50% for 3 days to cure and cure the curable composition. After removing the spacer, the test specimen was further cured by being placed in a curing apparatus under conditions of a temperature of 50 ° C. and a relative humidity of 65% for 6 days. The specimen was taken out from the curing device and allowed to stand for 24 hours or more under conditions of a temperature of 23 ° C. and a relative humidity of 50%, and then the tensile shear strength (maximum tensile stress and elongation at the maximum stress) was measured using Tensilon. The measurement was performed according to JIS K6850 under the condition of a pulling speed of 50 mm / min.

(T-shaped peel strength)
A curable composition was applied to an aluminum test piece having a length of 100 mm, a width of 25 mm, and a thickness of 0.5 mm so that the sample application surface had a length of 75 mm, a width of 25 mm, and a thickness of 1 mm. Produced.
The specimen was placed in a curing device under conditions of a temperature of 23 ° C. and a relative humidity of 50% for 3 days to cure and cure the curable composition. After removing the spacer, the test specimen was further cured by being placed in a curing apparatus under conditions of a temperature of 50 ° C. and a relative humidity of 65% for 6 days. Remove the specimen from the curing device and leave it for 24 hours or more under conditions of a temperature of 23 ° C. and a relative humidity of 50%. Then, the specimen is bent into a T shape and peel strength (5-point average peel stress) using Tensilon. Was measured. The measurement was performed in accordance with JIS K6854-3 under a pulling speed of 100 mm / min.

(Curable)
After adding 2 parts by mass of ES-C10 (manufactured by Asahi Glass Co., Ltd.) as a curing catalyst to a total of 100 parts by mass of the polymer, these were mixed and stirred. The stirring start time was 0 minute, the time when the curable composition became gelled was defined as the gel time (minutes), and the time when the curable composition did not adhere to the spatula was defined as the skinning time (minutes).

[Example 1]
Polymerization of 6828 g of propylene oxide in the presence of 1.6 g of zinc hexacyanocobaltate-glyme complex catalyst using 1000 g of diol (Mn: 3200) obtained by ring-opening addition of propylene oxide to propanediol as an initiator To obtain polyoxypropylene diol.
A methanol solution of sodium methoxide in an amount of 1.05 equivalent to the hydroxyl group of polyoxypropylene diol was added, and methanol was distilled off under heating and reduced pressure to convert the hydroxyl group of polyoxypropylene diol to -ONa group. Next, after adding 1.20 equivalents of allyl chloride to the -ONa group and reacting them, unreacted allyl chloride is removed under reduced pressure, and by-product salts are removed by purification, and allyl group terminal oxyl is removed. A propylene polymer (hereinafter referred to as polymer 1) was obtained.

When the hydroxyl group remaining in the polymer 1 was analyzed by a hydroxyl value measuring method in accordance with JIS K1557, the hydroxyl group amount was 0.01 mmol / g.
3 g of 3-mercaptopropyltrimethoxysilane and 4 g of AMBN are added to 1000 g of polymer 1 and reacted by heating at 70 ° C. for 12 hours to have a trimethoxysilyl group at the molecular end. (A21) (hereinafter referred to as TMS-2) was obtained. The number average molecular weight (Mn) of TMS-2 was 17000, and the molecular weight distribution (Mw / Mn) was 1.29. The introduction ratio of the group (X1) was 70 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene diol.

[Example 2]
Using 295 g of triol (Mn: 1000) obtained by ring-opening polymerization of propylene oxide on glycerin as an initiator, 706 g of propylene oxide was polymerized in the presence of 0.059 g of zinc hexacyanocobaltate-glyme complex catalyst. A polyoxypropylene triol was obtained.
A methanol solution of sodium methoxide in an amount of 1.05 equivalent to the hydroxyl group of polyoxypropylene triol was added, and methanol was distilled off under heating and reduced pressure to convert the hydroxyl group of polyoxypropylene triol into -ONa group. Next, after adding 1.20 equivalents of allyl chloride to the -ONa group and reacting them, unreacted allyl chloride is removed under reduced pressure, and by-product salts are removed by purification, and allyl group terminal oxyl is removed. A propylene polymer (hereinafter referred to as polymer 2) was obtained.

When the hydroxyl group remaining in the polymer 2 was analyzed by a hydroxyl value measurement method in accordance with JIS K1557, the hydroxyl group amount was 0.01 mmol / g.
To 1000 g of polymer 2, 15 g of a methanol solution in which 35 g of 3-mercaptopropyltrimethoxysilane and 5 g of AMBN were dissolved was added, and the mixture was reacted by heating at 70 ° C. for 12 hours, followed by degassing under reduced pressure. Thus, a polymer having a trimethoxysilyl group at the molecular end (hereinafter referred to as TMS-3) was obtained. The number average molecular weight (Mn) of TMS-3 was 17000, and the molecular weight distribution (Mw / Mn) was 1.29. The introduction ratio of the group (X1) was 85 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene triol.

[Example 3]
Using 1,200 g of tetraol (Mn: 1200) obtained by ring-opening polymerization of propylene oxide on pentaerythritol as an initiator, 24064 g in the presence of 0.06 g of zinc hexacyanocobaltate-tert-butyl alcohol complex catalyst. Propylene oxide was polymerized to obtain polyoxypropylene tetraol.
A methanol solution of sodium methoxide in an amount of 1.05 equivalent to the hydroxyl group of polyoxypropylene tetraol was added, and methanol was distilled off under heating and reduced pressure to convert the hydroxyl group of polyoxypropylene tetraol into -ONa group. Next, after adding 1.20 equivalents of allyl chloride to the -ONa group and reacting them, unreacted allyl chloride is removed under reduced pressure, and by-product salts are removed by purification, and allyl group terminal oxyl is removed. A propylene polymer (hereinafter referred to as polymer 3) was obtained.

When the hydroxyl group remaining in the polymer 3 was analyzed by a hydroxyl value measurement method in accordance with JIS K1557, the hydroxyl group amount was 0.01 mmol / g.
To 1000 g of the polymer 3, 22.4 g of a methanol solution in which 39.17 g of 3-mercaptopropyltrimethoxysilane and 5.6 g of AMBN were dissolved was added, and the reaction was performed by heating at 70 ° C. for 12 hours. Further, degassing under reduced pressure yielded a polymer (a1) having a trimethoxysilyl group at the molecular end (hereinafter referred to as TMS-4). The number average molecular weight (Mn) of TMS-4 was 25000, and the molecular weight distribution (Mw / Mn) was 1.35. The introduction rate of the group (X1) was 85 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene tetraol.

[Example 4]
Using 880 g of hexaol (Mn: 880) obtained by ring-opening polymerization of propylene oxide to sorbitol as an initiator, 26970 g of propylene in the presence of 0.04 g of zinc hexacyanocobaltate-tert-butyl alcohol complex catalyst A polyoxypropylene hexaol obtained by polymerizing an oxide was obtained.
A methanol solution of sodium methoxide in an amount of 1.05 equivalent to the hydroxyl group of polyoxypropylene hexaol was added, and methanol was distilled off under heating and reduced pressure to convert the hydroxyl group of polyoxypropylene hexaol into -ONa group. Next, after adding 1.20 equivalents of allyl chloride to the -ONa group and reacting them, unreacted allyl chloride is removed under reduced pressure, and by-product salts are removed by purification, and allyl group terminal oxyl is removed. A propylene polymer (hereinafter referred to as polymer 4) was obtained.

When the hydroxyl group remaining in the polymer 4 was analyzed by a hydroxyl value measuring method in accordance with JIS K1557, the hydroxyl group amount was 0.01 mmol / g.
30.8 g of a methanol solution in which 54.1 g of 3-mercaptopropyltrimethoxysilane and 7.7 g of AMBN were dissolved was added to 1000 g of the polymer 4, and the reaction was performed by heating at 70 ° C. for 12 hours. Further, degassing under reduced pressure gave a polymer (a1) having a trimethoxysilyl group at the molecular end (hereinafter referred to as TMS-6). The number average molecular weight (Mn) of TMS-6 was 25000, and the molecular weight distribution (Mw / Mn) was 1.45. The introduction ratio of the group (X1) was 85 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene hexaol.

[Example 5]
To 1000 g of the polymer 1 obtained in Example 1, 31.7 g of 3-mercaptopropyltriethoxysilane and 14.9 g of a methanol solution in which 3.7 g of AMBN were dissolved were added and heated at 70 ° C. for 12 hours. To obtain a polymer (a21) having a triethoxysilyl group at the molecular terminal (hereinafter referred to as TES-2). The number average molecular weight (Mn) of TES-2 was 17000, and the molecular weight distribution (Mw / Mn) was 1.29. The introduction ratio of the group (X) was 70 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene diol.

[Example 6]
Using 1200 g of tetraol (Mn: 1200) obtained by ring-opening polymerization of propylene oxide on pentaerythritol as an initiator, 0.06 g of a double metal cyanide complex catalyst having tert-butyl alcohol as a ligand. In the presence, 30800 g of propylene oxide was polymerized to obtain polyoxypropylene tetraol.
The polyoxypropylene tetraol was heated at 110 ° C. for 4 hours, dehydrated and cooled, and then 50 ppm of dibutyltin dilaurate (hereinafter referred to as DBTDL) was added as a urethanization catalyst and stirred. A polymer having a trimethoxysilyl group at the molecular end by adding 95 mol% of 3-isocyanatopropyltrimethoxysilane with respect to the hydroxyl group of polyoxypropylenetetraol and heating it at 90 ° C. for 8 hours to cause a reaction (a1) ( uTMS-4) was obtained.
uTMS-4 was analyzed by IR and it was confirmed that there was no residual isocyanate. The number average molecular weight (Mn) of uTMS-4 was 32000, and the molecular weight distribution (Mw / Mn) was 1.35. The introduction rate of the group (X1) was 95 mol% with respect to the hydroxyl group (100 mol%) of the raw material polyoxypropylene tetraol.

[Examples 7 to 32]
Curable material (a1) (one selected from TMS-4, TMS-6, uTMS-4) and curable material (a2) (from TMS-2, TES-2) at the ratios shown in Table 1 or Table 2. 1 type or 2 types selected) and another curable material (TMS-3) are blended, and a total of 100 parts by mass of the curable material (a1), the curable material (a2), and the other curable material is added. 30 parts by mass of quality calcium carbonate (trade name: NS-400, manufactured by Nitto Flour Chemical Co., Ltd.) and 70 parts by mass of surface-treated calcium carbonate (trade name: white polished CCR, manufactured by Shiraishi Calcium Co., Ltd.) It stirred and mixed using the type | formula stirrer (made by Kurabo Industries). After the temperature of the obtained mixture was lowered to room temperature, 5 parts by mass of vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a dehydrating agent, and the mixture was stirred and mixed. As an imparting agent, 3 parts by mass of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (trade name: KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.), and 3-glycidyloxypropyltrimethoxysilane (KBM-) 403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred and mixed, and finally 1 part by weight of DBTDL was added as a curing catalyst and stirred and mixed to obtain a curable composition. In Examples 17 and 31, among all the groups (X) (100 mol%) present in the curable material (a2), the groups (X1) are respectively 75.5 mol% and 77.8, respectively. Mol%.
Using the curable composition, tensile shear strength (maximum tensile stress and elongation at the maximum stress), peel strength (5-point average peel stress), and curability were evaluated. The results are shown in Table 1 or Table 2 together with the measurement results of gelation time and skinning time.

  As shown in Tables 1 and 2, Example 7 containing a tetrafunctional or higher functional branched polymer having a trimethoxysilyl group at the molecular end and a linear polymer having a trimethoxysilyl group at the molecular end -17, 22-31 are the conventional curable compositions (the curable composition of Example 20 containing only a linear polymer having a trialkoxysilyl group at the molecular end, and the molecular end Compared with the curable composition of Example 21 containing only a trifunctional branched polymer having a trimethoxysilyl group), the initial curing gelation time and skinning time are fast, and the tensile shear strength and maximum stress are high. The elongation and peel strength at the time were similar or high.

  Further, the gelation time and skinning time of the curable compositions of Examples 18, 19 and 32 containing only a tetrafunctional or higher-functional branched polymer having a trimethoxysilyl group at the molecular end, and trimethoxysilyl at the molecular end Examples 7 to 17 in comparison with the calculated values of gelation time and skinning time predicted from the gelation time and skinning time of the curable composition of Example 20 containing only a linear polymer having a group The gelation time and skinning time of the curable compositions of 22 to 31 were short, and showed a remarkable effect on the curing rate. Thereby, the short adhesion time to a base material was securable. The curable composition of the present invention could shorten the curing time while maintaining the shear strength, and had good peel strength and elongation even after curing.

  The curable composition of the present invention is useful as a coating composition such as a sealant, a waterproofing material, an adhesive, and a coating agent, and a sealing composition.

Claims (8)

A curable composition comprising the following curable material (a1), the following curable material (a2), and a curing catalyst (b).
(Curable material (a1))
By modifying a polyoxyalkylene polyol having 4 or more hydroxyl groups, a polymer (a1) (in which 85 mol% or more of the hydroxyl groups are converted into a group (X1) having a group represented by the following formula (Y1) ( However, the hydroxyl group which is not converted into the group (X1) may be modified with another group).
(Curable material (a2))
By modifying polyoxyalkylene diol, polymer (a21) in which 50 mol% or more of the hydroxyl group is converted to group (X) having a group represented by the following formula (Y) (however, in group (X) The hydroxyl group that is not converted may be modified with another group) and / or the polyoxyalkylene monool having an unsaturated group is modified to reduce 50 mol% or more of the total of unsaturated groups and hydroxyl groups. The polymer (a22) converted into the group (X) having a group represented by the formula (Y) (however, it may have an unsaturated group and / or a hydroxyl group that is not converted into the group (X)). 1 type or 2 types or more, Comprising: Of all group (X) (100 mol%) which exists in curable material (a2), said group (X1) is 50 mol% or more.
-Si (OR) ₃ (Y),
_{-Si (OCH 3) 3 ··· (} Y1).
However, R is a C1-C6 organic group, respectively. Of all the groups (X) (100 mol%) present in the curable material (a2), the group (X1) is 50 mol% or more,
The curable composition according to claim 1, wherein the remaining group (X) is a group (X2) having a group represented by the following formula (Y2).
_{-Si (OCH 2 CH 3) 3} ··· (Y2).   The curable composition of Claim 1 whose said group (X1) is 100 mol% among all the groups (X) (100 mol%) which exists in the said curable material (a2).   The curable composition according to any one of claims 1 to 3, wherein the polyoxyalkylene polyol has 4 to 6 hydroxyl groups.   The ratio of the curable material (a1) and the curable material (a2) (curable material (a1) / curable material (a2)) is 90/10 to 10/90 (mass ratio). Item 5. The curable composition according to any one of Items 1 to 4.   The ratio (curable material (a1) / curable material (a2)) between the curable material (a1) and the curable material (a2) is 80/20 to 10/90 (mass ratio). Item 6. The curable composition according to Item 5. The number average molecular weight (Mn) of the polymer (a1) is 8000 to 50000,
The molecular weight distribution (Mw / Mn) of the polymer (a1) is 1.6 or less,
The number average molecular weight (Mn) of the polymer (a21) or the polymer (a22) is 8000 to 50000,
The curable composition in any one of Claims 1-6 whose molecular weight distribution (Mw / Mn) of the said polymer (a21) or the said polymer (a22) is 1.6 or less.   The curable composition according to any one of claims 1 to 7, wherein the group (X1) of the polymer (a1) has a urethane bond.