JPH0240106B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel one-component thermosetting sealant composition, more specifically, a composition comprising a specific blocked isocyanate prepolymer and one or more isocyanate-reactive compounds, which is an isocyanate composition that is regenerated by heating. The present invention relates to a one-component thermosetting sealant composition that utilizes the reaction curing between a group and the isocyanate-reactive compound. Thermosetting sealants are mainly used for structures that are continuously assembled and produced on a line, such as automobiles,
It is used to seal joints and gaps to maintain airtightness and watertightness when assembling press-formed steel plates such as refrigerators by spot welding or other partial welding. Structures assembled by spot welding or other partial welding are subjected to surface treatment and electrodeposition coating for rust prevention purposes, and then a thermosetting sealant is applied and applied, and an intermediate coating is applied for aesthetic purposes. It is extremely convenient to use a one-component thermosetting sealant that can cure the sealant simultaneously with the baking of the top coat, does not require measuring or mixing, and does not have a limited pot life. Conventionally, thermosetting sealants used for such purposes include polyvinyl chloride paste compositions in which polyvinyl chloride powder is dispersed in a plasticizer and blended with adhesives, stabilizers, fillers, etc.; That is, so-called PVC plastisol sealants have been widely used. Although PVC plastisol sealants do not chemically undergo a thermosetting reaction, the polyvinyl chloride powder absorbs plasticizers due to heat, fuses with each other, solidifies and gels, and appears to harden. However, the PVC plastisol sealant has various drawbacks as described below. (1) Since the main component is polyvinyl chloride, it is easily decomposed by heat, light, etc. When decomposed, it generates hydrogen chloride, which easily causes rust and corrosion to the underlying steel plate. (2) Since the main component is polyvinyl chloride, it tends to become hard and brittle at low temperatures, and cracks and peeling may occur due to external forces such as vibration and impact, and strain. (3) It has poor adhesion to the electrodeposited surface, which is a normal adhesive base, and a special adhesive agent must be added, and the adhesive agent may cause aging of the sealant.
Furthermore, it may contaminate the paint applied over the sealant. The present inventors have conducted various studies to obtain a one-component thermosetting sealant that does not have these drawbacks, and have investigated thermosetting sealants using blocked isocyanate. It was found that the material used caused significant foaming during heat curing and was completely unusable as a sealant. The cause of this foaming is thought to be that the water contained in the filler and other compounded ingredients reacts with the isocyanate regenerated from the blocked isocyanate prepolymer during heat curing, generating carbon dioxide gas. Foaming can be prevented by drying the water or adding a dehydrating agent (molecular sieves, calcium oxide, etc.), but this requires long dehydration and drying processes and is difficult to store. It is economically disadvantageous because it must be completely sealed, and if a large amount of dehydrating agent is used, the water resistance of the sealant itself decreases, and even if it is exposed to the air for a short time during application, it will absorb moisture again. There is a problem that foaming occurs during heat curing, making it impractical. Foaming of heat-cured sealing materials using this blocked isocyanate prepolymer is likely to occur in a significant state because the reaction between isocyanate and water is rapid under heating, and the carbon dioxide gas generated is in a state of thermal expansion.
Countermeasures against this problem are extremely difficult. Therefore, as a result of further painstaking research, the present inventors used a compound having a specific chemical structure as a compound that reacts with the isocyanate group to cure it, and furthermore, the chemical equivalent ratio with the blocked isocyanate group was adjusted within a specific range. By adjusting the temperature, the filler and other compounds do not need to be particularly dried, and even if the sealant is left in the air after being applied, it will not foam during heat curing, or it can be easily cured by adding a small amount of dehydrating agent. They discovered that foaming can be suppressed and completed the present invention. That is, the present invention provides (A) one or more polyoxypropylene polyols having 2 to 3 hydroxyl groups in one molecule and a hydroxyl equivalent of 500 to 2,500 and one or more polyisocyanate compounds to 1 mole of hydroxyl groups. A blocked isocyanate prepolymer obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting the isocyanate group at a ratio of 1.5 to 2.5 moles with one or more thermally dissociable compounds to block free isocyanate groups, and (B) the following compounds (i) amine compounds having 2 to 4 primary or secondary amino groups in one molecule, (ii) 3 to 6 N-β-hydroxyethyl in 1 molecule or N-β-hydroxypropyl group, (iii) 1 to 3 primary to secondary amino groups and 1 to 4 N-β-hydroxyethyl groups or N-β- in one molecule. It consists of one or more isocyanate-reactive compounds selected from compounds having hydroxypropyl groups, and is characterized in that component (B) is blended in a ratio of 1.0 to 3.0 equivalents to the blocked isocyanate group of component (A). The present invention provides a one-component thermosetting sealant composition, which has such a specific configuration that does not foam during heat curing;
It is possible to obtain a thermosetting sealant composition that overcomes the drawbacks of PVC plastisol sealants, has excellent adhesion to the underlying electrodeposited surface, and has excellent physical properties. Hydroxyl group equivalent having 2 to 3 hydroxyl groups in one molecule used as component (A) in the composition of the present invention
500~2500 polyoxypropylene polyol is
It is a polymer having a hydroxyl group at the molecular end obtained by ring-opening polymerization of propylene oxide in the presence of one or more types of low-molecular active hydrogen compounds, usually bifunctional or trifunctional. This includes block or random copolymerization of ethylene oxide. Examples of the low-molecular active hydrogen compound used include ethylene glycol, propylene glycol, 1,4-butadiol, 1,6-
Glycols such as hexanediol, monoamines such as n-butylamine, laurylamine, benzylamine, cyclohexylamine, aniline, glycerin, trimethylpropane, 1,2,
Examples include triols such as 6-hexanetriol, alkanolamines such as monoethanolamine, triethanolamine, and triisopropanolamine, and ammonia. If the content of hydroxyl groups in one molecule of polyoxypropylene polyol is less than 2, curing will be insufficient;
When the number is more than 1, the physical properties become fragile, and 2 to 3 is preferable. In addition, if the hydroxyl equivalent, that is, the molecular weight per hydroxyl group, is less than 500, the viscosity of the blocked isocyanate prepolymer obtained will be high, and the viscosity of the sealant will increase, which tends to impede workability. This tends to cause curing, which is thought to be caused by molecular chain scission, and there are problems with heat resistance. Therefore, the hydroxyl equivalent is 500
~2500 is preferred. Examples of polyisocyanate compounds include:
2,4/2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, polyphenylmethane polyisocyanate called crude MDI, xylylene diisocyanate,
Isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,
Aliphatic, cycloaliphatic or aromatic di- or triisocyanate compounds such as 4'-diisocyanate, triphenylmethane triisocyanate, or these isocyanate compounds with low molecular weight glycols or triols (e.g. dipropylene glycol, 1,6 -hexanediol, 1,
An isocyanate-terminated low molecular weight adduct obtained by reacting with 2,6-hexanetriol, trimethylolpropane, etc. can be used. An isocyanate group-terminated prepolymer is produced by reacting the polyoxypropylene polyol with a polyisocyanate compound at a ratio of 1.5 to 2.5 moles of isocyanate groups per mole of hydroxyl groups in a conventional manner. At this time, a small amount of a catalyst such as stannous octylate, dibutyltin dilaurate, or lead naphthenate may be used to promote the reaction. This reaction may also be carried out in a solvent that is non-reactive with isocyanate groups, such as toluene, xylene, ethyl acetate, cellosolve acetate, and isocyanate groups such as dibutyl phthalate, di(2-ethylhexyl) phthalate, butylbenzyl phthalate. It may be carried out in the presence of a plasticizer that is non-reactive with the group. It is preferable to use these solvents and plasticizers that have been previously dried under reduced pressure or dehydrated using molecular sieves or the like. Examples of thermally dissociable compounds for blocking isocyanate group-terminated prepolymers include alcohols such as ethanol, propanol, butanol, and isobutanol, phenol, cresol,
Phenols such as xylenol and P-nitrophenol, ethyl malonate, ethyl acetoacetate,
Active methylene compounds such as acetylacetone, acid amides such as acetamide, acrylamide and acetanilide, acid imides such as succinimide and maleic acid imide, imidazoles such as 2-ethylimidazole and 2-ethyl-4-methylimidazole, 2 - Lactams such as pyrrolidone and ε-caprolactam, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime,
Various oximes of ketones or aldehydes such as acetaldoxime, ethyleneimine, and bisulfites can be mentioned, but lactams and oximes are preferable from the viewpoint of storage stability and curability, and in particular ε-caprolactam, Methyl ethyl ketoxime and cyclohexanone oxime are preferred. These thermally dissociable compounds are reacted with the above-mentioned isocyanate group-terminated prepolymer to produce a blocked isocyanate prepolymer. At this time, per mole of isocyanate group, the thermally dissociable compound is
It is used in an amount of about 0.90 to 1.5 equivalents, preferably about 1.0 to 1.3 equivalents. If the thermally dissociable compound is less than 0.9 equivalents,
Free isocyanate groups remain in the blocked isocyanate prepolymer, which has a negative effect on storage stability.On the other hand, if the amount exceeds 1.3 equivalents, unreacted thermally dissociable compounds may migrate or volatilize, causing problems. , which is also unfavorable from an economic point of view. (B) One type used as a component, 2 in 1 molecule
The compound (i) having ~4 primary to secondary amino groups can be obtained by condensing an excess amount of aliphatic polyamines such as ethylene diamine, diethylene triamine, hexamethylene diamine, etc. with a polybasic acid such as dimer acid or adipic acid. The resulting primary or secondary amino group-terminated polyamide resin, ethylenediamine, diethylenetriamine, hexamethylenediamine, m
-Excess amount of aliphatic polyamines such as xylylene diamine, polyhydric alcohols and polyhydric phenols such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, polyoxyalkylene glycol diglycidyl ether, and dimer acid diglycidyl ester. , or a primary or secondary amino group-terminated epoxy adduct obtained by condensing glycidyl ethers or glycidyl esters of polyhydric carboxylic acids, and 3.
9-bis(3-aminopropyl)-2,4,8,
Examples include 10-tetraoxaspiro[5.5]undecane compounds. Although low molecular weight amine compounds may also be used, they are less preferred in terms of toxicity, volatility, and pollution. Compound (ii) having 3 to 6 N-β-hydroxyethyl groups and/or N-β-hydroxypropyl groups in 1 molecule and 1 to 3 primary or secondary amino groups in 1 molecule and 1 to 4 N-β
- Compound (iii) having a hydroxyethyl group and/or N-β-hydroxypropyl group is a compound obtained by partially or completely adding ethylene oxide or propion oxide to the amino group or ammonia of an aliphatic or alicyclic polyamine compound. It is a compound. For example, aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine,
Aromatic polyamines or alicyclic polyamines having aliphatic amino groups such as m-xylylene diamine and isophorone diamine, or primary or secondary amino obtained by reacting these polyamines with polybasic acids or epoxy resins. Group-terminated polyamide or epoxy resin, further 3,9-bis(3
-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]It is a compound obtained by partially to completely adding ethylene oxide or propylene oxide to undecane, ammonia, etc.
In this case, the adduct with the epoxy resin may be prepared by partially adding ethylene oxide or propylene oxide to the polyamine in advance, and then reacting the remaining primary or secondary amino groups with the epoxy resin. Specific examples of polyamine adducts include triethanolamine, isopropanolamine, diethanolamine, diisopropanolamine, N,N,N',N'-tetra(β-hydroxyethyl)ethyleneamine, N,N,N' ,N′―
Tetra(β-hydroxypropyl)ethylenediamine, N,N,N′-tri(β-hydroxyethyl)ethylenediamine, N,N,N′-tri(β-hydroxyethyl)ethylenediamine
-Hydroxypropyl)ethylenediamine, N,
N'-di(β-hydroxyethyl)ethylenediamine, N,N'-di(β-hydroxypropyl)
Ethylenediamine, N-(β-hydroxyethyl)ethylenediamine, N-(β-hydroxypropyl)ethylenediamine, N, N, N′, N′,
N″-penta(β-hydroxypropyl)diethylenetriamine, N,N,N′,N′-tetra(β-hydroxypropyl)
-hydroxypropyl) diethylenetriamine,
N,N,N'-tri(β-hydroxypropyl)
Diethylenetriamine, N,N'-di(β-hydroxypropyl)diethylenetriamine, N-
(β-hydroxypropyl) diethylene ditriamine, N, N, N′, N′, N″, N-hex (β
-Hydroxypropyl)triethylenetetramine, N,N,N',N'-tetra(β-hydroxypropyl)hexamethylenediamine, N,N'-
Di(β-hydroxypropyl)hexamethylenediamine, N,N,N′,N′-tetra(β-hydroxypropyl)-m-xylylenediamine, N,
N'-di(β-hydroxypropyl)-m-xylylenediamine, N,N,N',N'-tetra(β-
-Hydroxypropyl)isophoronediamine,
N,N,N'-tri(β-hydroxypropyl)
Examples include isophorone diamine. The isocyanate-reactive compound (B) selected from these (i), (ii) and (iii) can be used alone or in combination of two or more, but particularly preferred is the amine compound (i). Among them, primary or secondary amino group-terminated polyamide resin obtained by condensation of aliphatic polyamine and polybasic acid, primary or secondary amino group-terminated epoxy amine adduct obtained by reaction of aliphatic polyamine and epoxy resin, and Amino group terminal 3,9-bis(3-aminoprobyl)-2,
4,8,10-tetraoxaspiro[5.5]undecane-based compounds, and these isocyanate-reactive compounds (B) react with the blocked isocyanate groups of the blocked isocyanate prepolymer (A),
Mix and use in the range of 1.0 to 3.0 equivalents. (i), (ii), (iii)
Functional number of component (number of primary or secondary in one molecule +
Since it is polyfunctional, the number of N-β-hydroxyethyl groups or N-β-hydroxypropyl groups is 2 to 6, it exhibits sufficient curability when heated even if the amount is less than the equivalent, but if the number of functionalities is low, shows a tendency for hardenability to worsen, and when the amount is large, water resistance and physical properties decrease. Therefore, component (i) has 2 to 4 primary or secondary amino groups, component (ii) has 3 to 6
N-β-hydroxyethyl (or propyl) groups, in the case of component (iii), 1 to 3 primary or secondary
It is preferable that one molecule contains a class amino group and 1 to 4 N-β-hydroxyethyl groups or N-β-hydroxypropyl groups. In addition to these specific compounds, the usual isocyanate-reactive polyhydroxy compounds such as ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, 1,4-butanediol, 1,6-hexane Diols, 1,2,6-hexanetriol, pentaerythritol, diglycerin, etc. within the range that does not show harmful effects, for example,
They can also be used together in an amount of about 50% by weight or less based on components (i), (ii), and (iii). The one-component thermosetting sealant composition of the present invention may contain conventional plasticizers, fillers, reinforcing agents, thixotropic fillers, stabilizers, curing accelerators, solvents, and the like, as required. Examples of plasticizers include phthalic acid esters such as di(2-ethylhexyl) phthalate, butylbenzyl phthalate, dinonyl phthalate, diheptyl phthalate, butylphthalyl butyl glycolate; dioctyl adipate, didecyl adipate, dioctyl sebacate, etc. Aliphatic dibasic acid esters; polyglycol benzoate esters such as polyoxyethylene glycol dibenzoate and polyoxypropylene glycol dibenzoate; phosphoric acid esters such as tributyl phosphate and tricresyl phosphate; alkyl-substituted diphenyl, Non-reactive isocyanates selected from alkyl-substituted terphenyl, partially hydrogenated alkyl terphenyl, aromatic process oil, hydrocarbons such as pine oil, etc. can be used, and blocked isocyanate prepolymer 100
It is used in an amount of about 0 to 200 parts by weight. Filling materials and reinforcing materials can be selected and used in combination as appropriate, taking into consideration physical properties, properties, economic efficiency, etc.
For example, kaolin clay, heavy calcium carbonate, precipitated calcium carbonate, fatty acids, resin acids, calcium carbonate surface-treated with other cationic or anionic surfactants, magnesium carbonate, titanium oxide, calcined stone sulfur, barium sulfate, zinc oxide. , silicic anhydride, mica powder, asbestos, talc, bentonite, silica, glass powder, red iron, carbon black, graphite powder, alumina, shirasu balloon, and metal powders such as aluminum, copper, iron, and zinc. It is used in an amount of about 10 to 700 parts by weight per 100 parts by weight of the doisocyanate prepolymer. A thixotropic additive is used to adjust the fluidity of a sealant and is added to improve workability, sagging after construction, leveling properties, etc., and includes organic bentonite, fumed silica, aluminum stearate, etc. , metal soaps such as calcium or zinc, and castor oil derivatives. This thixotropic filler is often not necessarily required depending on the formulation of the filler. As a stabilizer, 2,6-di-t-butyl-4
-Known stabilizers such as methylphenol (BHT), 2,2-methylene-bis(4-methyl-6-t-butylphenol), and nickel dibutyldithiocarbamate (NBC) are used, and per 100 parts by weight of prepolymer. Approximately 0.1 to 2 parts by weight can be used, but in the composition of the present invention, the curing temperature is 140
It is not necessary at temperatures between ℃ and 160℃. Examples of the curing accelerator include known ones such as dibutyltin dilaurate, lead octylate, and bismuth octylate, which are not necessarily required and can similarly be used in an amount of about 0 to 0.5 parts by weight. Although a solvent is not necessarily required, it is also possible to use a solvent such as toluene, xylene, cellosolve acetate, ethyl acetate, butyl acetate, amyl acetate, etc. if necessary to lower the viscosity. Furthermore, the composition of the present invention is characterized in that it does not foam during heat curing, but if it foams slightly during high temperature curing due to the moisture contained in the filler, etc., a small amount of dehydrating agent, such as calcium oxide or molecule, may be added. It can be completely prevented by adding Rhashibus etc. The foaming is considered not to be caused by the reaction of water and isocyanate to generate carbon dioxide gas, but to be caused by the direct vaporization of water to become water vapor. The present invention will be explained in more detail below with reference to Examples. In the examples, % and parts mean weight % and parts by weight unless otherwise specified. Example 1 462.7 g of polyoxypropylene diol (hydroxyl equivalent: 500) with an average molecular weight of 1000 and 80/20 tolylene diisocyanate (2,4-tolylene diisocyanate 80%, 2,6-tolylene diisocyanate 20%)
% mixture) 177.3% and di-(2-ethylhexyl) phthalate (160 g) were placed in a separable flask, and stirred while flowing dry nitrogen gas for 80 g.
The reaction was carried out at .degree. C. for 5 hours, and then allowed to stand overnight at 80.degree. C. to obtain an isocyanate group-terminated prepolymer as a colorless and transparent viscous liquid. The content of isocyanate groups was measured by the di-n-butylamine method.
5.69%, and the viscosity was 5250 centihoise (20°C). Furthermore, 115 g of ε-caprolactam, which had been dehydrated using molecular sieves in advance, was added to 600 g of this prepolymer, and the reaction was simultaneously carried out at 80°C for 3 hours while stirring under dry nitrogen gas flow, and further at 80°C.
The viscosity was 86,000 centipoise (20°C) when left overnight.
A colorless, transparent and viscous plasticizer solution of blocked isocyanate prepolymer is obtained. It was confirmed that this solution was almost completely blocked when the isocyanate group content was 0.1% or less. Next, 2.76 parts of N,N,N',N'-tetra(β-hydroxypropyl)ethylenediamine and di(2-ethylhexyl) phthalate were added to 18 parts of the plasticizer solution of this blocked isocyanate prepolymer.
19 parts, calcium carbonate surface-treated with fatty acids (Shiraishi Calcium Shiraika CC) 10 parts, heavy calcium carbonate (Shiraishi Calcium Whiten SB) 45.24
1 part, 2 parts of titanium white (rutile type), and 3 parts of calcium oxide, and mixed with a vertical mixer that can reduce the pressure to 5 mm.
A white paste composition is obtained by kneading for 30 minutes under reduced pressure of Hg. Example 2-22 An isocyanate group-terminated prepolymer was prepared in the same manner as in Example 1 with the formulation shown in Table 1, and a blocked isocyanate prepolymer was further prepared in the same manner as in Example 1 with the formulation shown in Table 2. do. A sealant composition was obtained in the same manner as in Example 1 using these blocked isocyanate prepolymers in the formulations shown in Table 3.

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[Table] Comparative Examples 1 to 8 As shown in Table 1, a sealant composition was prepared in the same manner as in Example 1 using the blocked isocyanate prepolymer used in the Example.

[Table] Isocyanate-reactive compounds and calcium carbonate A and B in Tables 3 and 4 above
means the following: H-1: N, N, N', N'-tetra(N-β-hydroxypropyl)ethylenediamine 2: Diethanolamine 3: Triethanolamine 4: DER-#732 (epoxy resin manufactured by Asahi Dow Co., Ltd.)/diethanolamine = 1 mol/2 mol adduct 5: DER-#732 (epoxy resin manufactured by Asahi Dow Co., Ltd.)/ethylenediamine = 1 mol/2 mol adduct 6: Polyamide resin Versamide #115 (manufactured by Henkel Japan Co., Ltd.) 7 :3,9-bis(3-aminopropyl)-
2,4,8,10-tetraoxaspiro[5.5]undecane compound (Epomate B
-002, manufactured by Yuka Ciel Co., Ltd.) 8: Triisopropanolamine 9: Diisopropanolamine 10: N-(β-hydroxyethyl)ethylenediamine 11: N-(β-hydroxypropyl)ethylenediamine 12: N, N'- Di(β-hydroxypropyl)
Ethylenediamine Z-1: Ethylene glycol 2: Polyoxypropylene triol (molecular weight 250) 3: 1,2,6-hexanetriol 4: 1,4-butanediol 5: Glycerin calcium carbonate A: Fatty acid-treated calcium carbonate (Shiraika CC, (manufactured by Shiraishi Calcium Co., Ltd.) Calcium carbonate B: Heavy calcium carbonate (Whiten SB, manufactured by Shiroishi Calcium Co., Ltd.) Using the paste compositions obtained in Examples 1 to 15 above, the following various evaluations were carried out. was carried out. (1) Hardened state: Apply to a width of 25 mm and a thickness of 5 mm on a 0.8 mm thick steel plate.
Place it in a hot air circulation thermostat at 150℃ for 30 minutes.
After cooling, the state of foaming was visually inspected and the hardness was determined using a JISK-6301 rubber hardness meter. (2) Adhesion to 0.8mm thick automotive cationic electrodeposition coating surface
As in (1), it was coated to a width of 25 mm and a thickness of 5 mm, placed in a hot air circulation thermostat at 150°C for 30 minutes, and after cooling, adhesion was visually inspected while cutting with a knife. (3) Flexibility Apply the same method as in (1) to a 0.8 mm thick cationic electrodeposition coating surface for automobiles to a width of 25 mm and a thickness of 5 mm, place it in a hot air circulation thermostat at 150°C for 30 minutes, and leave it to cool. Using a mandrel-type bending tester with a diameter of 50 mm, the sealant was bent 180 degrees with the coated side facing outward to check for cracks or chips in the sealant. In addition, this test was also conducted on test pieces cooled to -40°C, and cracks and cracks at low temperatures were also detected. These results are shown in Table 6. As is clear from these results, the thermosetting sealant composition of the present invention exhibits a good cured state without foaming, and has excellent adhesiveness and flexibility.

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Claims (1)

[Scope of Claims] 1 (A) One or more polyoxypropylene polyols having 2 to 3 hydroxyl groups in one molecule and having a hydroxyl equivalent of 500 to 2,500 and one or more polyisocyanate compounds with 1 hydroxyl group A blocked isocyanate prepolymer obtained by reacting an isocyanate group-terminated prepolymer obtained by reacting at a ratio of 1.5 to 2.5 moles of isocyanate groups per mole with one or more thermally dissociable compounds to block free isocyanate groups. , and (B) the following compounds (i) amine compounds having 2 to 4 primary or secondary amino groups in one molecule, (ii) 3 to 6 N-β-hydroxy groups in one molecule Compounds having an ethyl group or N-β-hydroxypropyl group, (iii) 1 to 3 primary to secondary amino groups and 1 to 4 N-β-hydroxyethyl groups or N-β in one molecule - Compounds having a hydroxypropyl group, consisting of one or more isocyanate-reactive compounds selected from the following, and the component (B) is blended in a ratio of 1.0 to 3.0 equivalents to the blocked isocyanate group of the component (A). A one-component thermosetting sealant composition characterized by: 2. The composition of item 1 above, wherein the thermally dissociable compound is selected from lactams and ketone oximes. 3. The isocyanate-reactive compound (B)-(i) is a primary to secondary amino group-terminated polyamide resin obtained by condensation of an aliphatic polyamine and a polybasic acid, or 1 obtained by a reaction of an aliphatic polyamine and an epoxy resin. Grade ~2
grade amino group-terminated epoxy amine adduct, and amino group-terminated 3,9-bis(3-aminopropyl)
-2,4,8,10-tetraoxaspiro [5.5]
The composition according to item 1 above, which is one or more selected from undecane compounds.