JPH10292025A - Two-part curable urethane composition and coating material, sealing material, adhesive - Google Patents

Abstract

(57) [Problem] An object of the present invention is to provide a two-part composition in which the time required for curing is short despite the long working time after mixing the main agent and the curing agent, and the coating film is unlikely to foam even during high-temperature application. The present invention relates to a curable urethane composition and a coating material, a sealing material, and an adhesive using the composition. SOLUTION: The present invention provides (A) a primary or secondary amino group by a main agent mainly composed of a urethane prepolymer having two or more isocyanate groups at the terminal and (B) water. A two-part curable urethane composition characterized by comprising a curing agent mainly composed of an active hydrogen compound such as a block amine compound and a (C) polyol, an amine to be generated, and a coating material using the composition, a sealing material,
An adhesive is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-part curable urethane which requires a short time for curing in spite of a long working time after mixing a main agent and a curing agent, and hardly foams a coating film even at a high temperature. The present invention relates to a composition and a coating material, a sealing material, and an adhesive using the composition.

[0002]

2. Description of the Related Art Polyurethane compositions are prepared by mixing a main component mainly composed of an isocyanate-terminated urethane prepolymer with a curing agent mainly composed of an active hydrogen compound such as a polyol or an amine, and curing the mixture. Prepolymers can be broadly classified into one-component reactive urethanes, which react and cure with amine compounds generated and dissociated by moisture in the air or moisture.

[0003] Among them, the two-part curable urethane is inexpensive as compared with the one-part type in which it takes time to measure and mix the main agent and the curing agent, and the difference in curing time due to the thickness of the coating film is small. It is still widely used in the fields of coating materials, sealing materials, adhesives and the like. One problem that has been pointed out as a problem of the two-component curing type urethane is that it is difficult to balance the working time and the curing time. In other words, when trying to secure a sufficiently long working time, the curing time of the coating film becomes longer and it takes time to move to the next process operation, and if the curing time is shortened by adjusting the catalyst etc., the working time becomes shorter. It is. Further, since the curing time depends on the temperature, it is not preferable to add a catalyst amount suitable for the use temperature because the burden on the manufacturer or the operator is large.

In view of such a point, Japanese Patent Application Laid-Open No. 8-34829
JP, JP-A-8-41156, JP-A-8-14
No. 3826 proposes a method using diethyltoluenediamine, diethyltoluenediamine and 4,4′-methylene-bis (2-chloroaniline) (hereinafter abbreviated as MBOCA), and diethyltoluenediamine and methylbis (methylthio) benzenediamine as curing agents. Although it is possible to shorten the curing time as compared with the case of using a conventional curing agent containing MBOCA as a main component, it is still not possible to secure a sufficient working time, and it is necessary to finish the work in a particularly short time especially in summer. Be forced. In addition, a system has been introduced in which the isocyanate-terminated urethane prepolymer and the amine are impact-mixed by a machine and spray-coated, but the coating film contains foam and reduces the strength of the material. In reality, it can be used only for limited uses such as large-scale properties because of the labor of masking work.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to shorten the time required for curing (curability) and excellent adhesive strength in spite of the long working time after mixing the main agent and the curing agent, and to achieve excellent adhesion at high temperature. The present invention also relates to a two-part curable urethane composition in which a coating film is hardly foamed, and a coating material, a sealing material, and an adhesive using the same.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems of the two-part curable urethane. As a result, (A) a urethane prepolymer having two or more isocyanate groups at its terminal It has been found that these problems can be solved by using a main agent containing as a main component, and a curing agent mainly containing (B) a latent crosslinking agent and (C) an active hydrogen compound, to complete the present invention. Reached.

That is, the present invention provides (A) a main component mainly composed of a urethane prepolymer having two or more isocyanate groups at the terminal and (B) a latent or secondary crosslinking agent, preferably primary or secondary, with water. Two-part curable urethane composition, comprising a curing agent having a block amine compound and a (C) active hydrogen compound that form a secondary amino group as a main component,
Preferably, the block amine compound is reacted with N-2-hydroxyalkyl oxazolidine (b2) or / and a urethane prepolymer (b1) having two or more terminal isocyanate groups with N-2-hydroxyalkyl oxazolidine (b2). Urethane oxazolidine prepolymer having a terminal oxazolidine group (b)
3), and the urethane prepolymer (b1) preferably contains an oxyethylene chain. The present invention also relates to a coating material, a sealing material, and an adhesive comprising the composition.

Hereinafter, the present invention will be further described.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The urethane prepolymers (A) and (b1) having two or more terminal isocyanate groups used in the present invention are both urethane prepolymers having two or more isocyanate groups. There is a urethane prepolymer prepared by a conventional method using an organic polyisocyanate and a polyol in excess of a polyisocyanate.

As organic polyisocyanates, 2,4
-Tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, partially carbodiimidated diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, tolylene diisocyanate, naphthalene diisocyanate, phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, One or a mixture of two or more aromatic diisocyanates, such as xylylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and cyclohexane diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate.

The polyols include polyether polyols, polyester polyols, other polyols, and mixed polyols thereof. For example, a polyol produced using a double metal cyanide complex as a catalyst is also included.

As the polyether polyol, one or more polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, glucose, sorbitol, and sucrose are used. Polyols and polyoxytetramethylene polyols obtained by adding one or more of oxide, butylene oxide, styrene oxide and the like are included.

Examples of the polyester polyol include one or two of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, glycerin, trimethylolpropane and other low molecular polyols.
Or more and one or more of glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, dimer acid, hydrogenated dimer acid or other low molecular dicarboxylic acid or oligomeric acid Examples include condensation polymers and ring-opening polymers such as propiolactone, caprolactone, and valerolactone.

Other polyols include, for example, polycarbonate polyol, polybutadiene polyol,
Examples include hydrogenated polybutadiene polyol and acrylic polyol. Also, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol,
Low molecular polyols such as hexanediol, cyclohexanedimethanol glycerin, trimethylolpropane, glucose, sorbitol, and sucrose are also included.

The polyol of the component (A) is preferably a polyether polyol having a number average molecular weight of 300 to 16000 and preferably containing no oxyethylene chain. More preferred are polyether diols and / or polyether triols. Urethane prepolymer (b
In 1), a polyol containing an oxyethylene chain is preferable.

The number of terminal isocyanate groups of the urethane prepolymer (A) is preferably 2 or more, more preferably 2 or more.
~ 3. NC of isocyanate and polyol
The O / OH ratio is preferably 1.3 or more, and more preferably 1.3 to 5.0. The residual NCO% is preferably 1
-20% by weight.

The latent crosslinking agent (B) of the present invention is a polyol type in which active hydrogen of an active hydrogen compound is masked by various methods, and active hydrogen is generated by hydrolysis upon absorption of moisture.
Ketimine, enamine, aldimine and oxazolidine type compounds are used alone or in a mixed system. Preferably, it is a block amine compound that generates a primary or secondary amino group by water, and examples thereof include compounds such as aldimine, ketimine, enamine, and oxazolidine.
More preferably, at least one primary or secondary
Having a primary amino group and a primary or secondary amino group,
A condensate of a compound having an active hydrogen such as a hydroxyl group with an aldehyde or a ketone, a ketimine group or an oxazolidine group at a terminal obtained by reacting the condensate with the above-mentioned organic polyisocyanate or a urethane prepolymer having a terminal isocyanate group. A compound having the following formula:

At least one of the above-mentioned first or second grades
Having a primary amino group and a primary or secondary amino group,
Examples of the compound having an active hydrogen such as a hydroxyl group include a compound having a primary amino group and a hydroxyl group, a compound having a secondary amino group and a hydroxyl group, and a compound having a primary amino group and a secondary amino group. A compound having a primary amino group / secondary amino group and a hydroxyl group, a compound having two primary amino groups, a compound having two secondary amino groups, a secondary amino group Examples of the compound include a compound having a group and two hydroxyl groups. Specific examples include ethanolamine, diethanolamine, dipropanolamine, hexanolamine, diethylenetriamine, 2- (2-aminoethoxy) ethanol, and N- (2 -Aminoethyl) piperazine, ω-hydroxyhexylamine, N-methyl-1,
6-hexanediamine, N- (2-hydroxyethyl)
Ethylenediamine, 3-aminoethylpiperidine, N-
(2-hydroxyethyl) piperazine, 1-amino-3
-Aminomethyl-3,5,6-trimethylcyclohexane, N- (methylaminoethyl) piperazine, aniline, toluidine, xylidine, isophoronediamine, diaminocyclohexane, diaminodiphenylmethane, xylylenediamine, diaminobenzene, diaminomethylnorbonane, diamino Methyl bicycloheptane and the like can be mentioned.

The ketones and aldehydes include
Examples include acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, diisobutyl ketone, methyl heptenone, cyclohexanone, isophorone, acetophenone, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, trimethylacetaldehyde, valeroaldehyde, acrolein, crotonaldehyde, furfural, benzaldehyde, and the like. be able to. The synthesis of the blocked amine compound (B) such as aldimine, ketimine, enamine, oxazolidine and the like can be carried out by a known reaction method.

Of these, the block amine compound (B) is preferably an N-2-hydroxyalkyloxazolidine (b2) or / and a urethane prepolymer (b1) having two or more terminal isocyanate groups.
And N-2-hydroxyalkyloxazolidine (b
2) is a urethane oxazolidine prepolymer (b3) having an oxazolidine group at the terminal obtained by reacting with (2).

This N-2-hydroxyalkyloxazolidine (b2) is a known condensation product of aldehydes such as formaldehyde, acetaldehyde, propylaldehyde, butyraldehyde and benzaldehyde with dihydroxyalkylamines such as diethanolamine and dipropanolamine. It is a compound obtained by the reaction.

Urethane prepolymer (b1) and N-2-
The reaction ratio with hydroxyalkyl oxazolidine (b2) is preferably NCO / OH = 1.2 or less.
/0H=1.1 or less is preferred. NCO / 0H = 1.2
If the ratio exceeds the above range, the increase in viscosity becomes large due to the reaction between the remaining isocyanate groups and the active hydrogen compound (C) in the curing agent component.

The urethane oxazolidine prepolymer (b)
The number of terminal oxazolidine groups in 3) is preferably 1 to 3. If it exceeds 3, the elongation after curing is lowered, which is not preferable. The urethane oxazolidine prepolymer (b
It goes without saying that if at least one oxazolidine group is present at the terminal of 3), the other terminal may be an isocyanate group.

As the active hydrogen compound (C), a polyol and / or an amine compound can be used. As the polyol, the above-mentioned polyether polyol,
Polyester polyols, other polyols and mixed polyols thereof can be used, and methylene bisorthochloroaniline (hereinafter referred to as MB) is used as the amine compound.
OCA), diethyltoluenediamine, methylbis (methylthio) benzenediamine, 4,
Known primary or secondary aromatic amine compounds such as 4'-bis (secondary-butylamino) diphenylmethane and 4,4'-bis- (methylamino) diphenylmethane can be used.

The content ratio of the block amine compound (B), which forms a primary or secondary amino group by the moisture in the curing agent component, to the active hydrogen compound (C) is 8 as the ratio of the active hydrogen equivalent.
The range of 0:20 to 5:95 is preferable, and 60:40 to 1
A range of 5:85 is more preferred. If the ratio exceeds 80:20, the curing speed is strongly affected by the amount of moisture in the air, and the curing speed inside the coating film tends to decrease particularly at the time of thick coating. I can't show it enough.

The mixing ratio of the main agent and the curing agent is preferably such that the ratio of the isocyanate group to the active hydrogen group is in the range of 0.5: 1.0 to 1.5: 1.0. When the ratio of the isocyanate group to the active hydrogen group is less than 0.5: 1.0, the mechanical properties and durability are reduced. Some foaming is not preferred.

The composition of the present invention can be used for coating materials, sealing materials, adhesives and the like. Specifically, as a coating material, it can be used for paint, roof waterproofing material of buildings, wall waterproofing material, surface paving material of stadiums, etc.
It can be used as a sealing material for concrete, sizing board, metal, etc. for civil engineering construction, and as an adhesive, it can be used as an adhesive for building interior materials such as plastic flooring, an adhesive for roof tarpaulin, and for bonding tiles and sheets. It can be used as an agent.

When used in these applications, the composition of the present invention may contain, as necessary, an acid, a solvent, an inorganic filler, a small amount of process oil, a plasticizer, a thixotropic agent in a base material and / or a curing agent. And various additives such as an extender, an ultraviolet inhibitor for maintaining and improving weather resistance, and a stabilizer, and a catalyst.

For the purpose of promoting the curability of the present invention, an acid and a known urethane catalyst can be added. Acid is the main ingredient,
It is possible to blend either or both of the curing agents, preferably inorganic acids, organic acids and their anhydrides,
One or more selected from the group consisting of esters and acid salts are used. For example, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, silicic acid, aluminate, octylic acid, perchloric acid, formic acid, acetic acid,
Chloroacetic acid, propionic acid, caproic acid, oxalic acid, succinic acid, adipic acid, maleic acid, phthalic acid, benzoic acid, salicylic acid acid phosphate, and the like, or anhydrides, esters, acid salts thereof, and the like can be given. Known urethane catalysts such as tertiary amines and organometallic compounds are desirably blended with the curing agent.

Usable solvents include ordinary urethane solvents such as toluene, xylene, terpene, and ethyl acetate.

Examples of the thixotropic agent include surface-treated calcium carbonate, polyvinyl chloride powder, finely divided silica, bentonite and the like. In addition, the composition of the present invention may be mixed with a petroleum-based high-boiling aromatic fraction, a petroleum resin and the like.

Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, diundecyl phthalate,
Ester plasticizers such as dilauryl phthalate, butylbenzyl phthalate, diisodecyl phthalate, dibutyl adipate, dioctyl adipate, diisodecyl adipate, dioctyl azelate, dioctyl sebacate, and phosphate ester plasticizers such as trioctyl phosphate and triphenyl phosphate. For example, a known plasticizer for urethane can be used.

Examples of the stabilizer include an antioxidant and an ultraviolet absorber. As the inorganic filler, for example, calcium carbonate, calcium oxide, clay, talc,
Examples include powders of inorganic compounds such as titanium oxide, calcium hydroxide, aluminum sulfate, kaolin, zeolite, diatomaceous earth, and glass balloons.

[0034]

Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, all parts and percentages are by weight unless otherwise specified.

<Synthesis of Component (A)> (Preparation Example 1 of Urethane Prepolymer) Number average molecular weight 20
1000 g of polypropylene ether diol of 00
(0.5 mol) to 2,4-tolylene diisocyanate 1
94.9 g (1.12 mol), that is, an NCO / OH equivalent ratio of 2.24 was reacted in a flask with stirring under a nitrogen stream at 80 ° C. for 25 hours to give an NCO% of 4.35%.
The urethane prepolymer (A-1) was obtained.

(Production Example 2 of Urethane Prepolymer) Polypropylene ether diol 6 having a number average molecular weight of 3000
63.5 g (0.365 mol) of 2,4-tolylene diisocyanate per 00 g (0.2 mol), that is, NCO /
OH equivalent ratio 1.825 at 80 ° C. under nitrogen flow
The mixture was reacted with stirring in a flask for 5 hours to obtain a urethane prepolymer (A-2) having an NCO% of 2.09%.

<Synthesis of Component B> (Preparation Example 1 of Block Amine Compound) Number average molecular weight 48
A mixture of 500 g (0.104 mol) of polyethylene propylene ether triol having a oxyethylene chain content of 15% and 500 g (0.25 mol) of polypropylene ether diol having a number average molecular weight of 2,000 was prepared. 0.5%, average number of functional groups 2.2
9. A polyol having a number average molecular weight of 2820 was obtained. Further, 143.3 g of hexamethylene diisocyanate (0.8
53 mol), that is, an NCO / OH equivalent ratio of 2.1 was reacted in a flask with stirring at 80 ° C. for 48 hours under a nitrogen stream to give an NCO% of 3.29% and a terminal N per molecule.
Urethane prepolymer having 2.29 CO groups (b1-1)
I got

Urethane prepolymer (b1-1) 14
0.8 g and 2-isopropyl 3 (2-hydroxyethyl)
1,3 oxazolidine (hereinafter abbreviated as H-OXZ) 15.9
g, that is, an NCO / OH equivalent ratio of 1.1 was reacted in a flask under a nitrogen stream at 60 ° C. for 48 hours while stirring, and a urethane oxazolidine prepolymer (OXZ-
1) was obtained. As a result of measuring the GPC of this composition, it was confirmed that the content of the remaining H-OXZ was 1% or less.

(Preparation Example 2 of Block Amine Compound) In Preparation Example 1 of urethane oxazolidine prepolymer,
Number average molecular weight 4800, oxyethylene chain content 15
% Polyethylene propylene ether triol 500%
g (0.104 mol) instead of number average molecular weight 4800
500 g of polypropylene ether triol (0.1 g
(04 mol) was used, to obtain a urethane oxazolidine prepolymer (OXZ-2) in the same manner. As a result of measuring the GPC of this composition, the remaining H-OXZ
Was confirmed to be 1% or less.

(Preparation Example 3 of Block Amine Compound) 100 g of tetramethylene diamine and 35 g of p-tolualdehyde
0 g was reacted at 95 ° C. for 10 hours in the presence of formic acid and toluene while distilling off water, and the remaining water, unreacted p-tolualdehyde and toluene were removed by heating under reduced pressure to give an amine value of 380.
mg KOH / g of dialdimine (AR-1) was obtained.

<Compounding of the curing agent> The compounds shown in the following table were added in a closed planetary mixer and mixed uniformly.
Defoaming was performed to obtain a curing agent. In addition, calcium carbonate is 120 ° C.
And dried under reduced pressure for 5 hours to adjust the water content to 0.05% or less. For MBOCA, dioctyl phthalate (hereinafter abbreviated as DOP) was previously mixed and then dissolved at 80 ° C. In addition, Examples 1 to 3 and 5 and Comparative Examples 1 to 3 and 5 were manufactured as waterproof materials, and Example 4 and Comparative Example 4 were used.
Was manufactured as a sealant / adhesive application.

[Test Method] (Mixed Viscosity) Immediately after mixing the main agent and the curing agent at a predetermined ratio, 100 g was collected in a plastic container, and the viscosity was measured 5 minutes after mixing in a 25 ° C. atmosphere. Examples 1 to 3 and 5 and Comparative Examples 1 to 3 and 5 were measured with a BM-type rotational viscometer, and Examples 4 and Comparative Example 4 were measured with a BH-type rotational viscometer.

(Working time) In Examples 1 to 3 and 5, and Comparative Examples 1 to 3 and 5, the main agent and the curing agent were mixed at a predetermined ratio, and 100 g was immediately collected in a plastic container.
The viscosity was measured using a BM-type rotational viscometer in an atmosphere of × 50% RH, and the time required to reach 100,000 cps was defined as the pot life. On the other hand, for Example 4 and Comparative Example 4,
After mixing the curing agent at a predetermined ratio, the extrudability was evaluated according to JISA-5758 in an atmosphere of 20 ° C. × 55% RH,
The time required for the extrusion time to reach 20 seconds was defined as the pot life.

(Curability Test) In Examples 1 to 3 and 5 and Comparative Examples 1 to 3, the thickness was 6 mm on a glass plate (10 × 10 cm) with a frame surrounded on all sides and release paper attached. The sample is flowed through at 25 ° C x 35% RH and 25 ° C x 80%
It was left under RH conditions, and the hardness was measured at regular intervals by a JISA hardness tester. The hardness after curing for 14 days under the conditions of 25 ° C. × 80% RH was defined as the final hardness, and the time required to reach a hardness of 50% of the final hardness was defined as the curing time.

(Adhesion Development Test) Example 4 and Comparative Example 4
About concrete pavement board (30cm × 30cm × 7c
0.5 kg / cm ² of the sample on the surface of
25% × 35% and 25 ° C. × 80
After 10 minutes of standing under the condition of% RH, a waterproof sheet made of PVC (2.5 × 30 cm, DP roof sheet: manufactured by Dainippon Ink and Chemicals, Inc.) was stuck on and left under the same conditions with a load of ² g / cm ² applied. And a pulling speed of 200 mm /
The peel strength was measured under the conditions of min. Under the same conditions, 14
The final strength is defined as the peel strength after standing for 50 days.
% Of the time until the strength reached was defined as the adhesion development time.

(Tensile physical property test) The tensile physical properties were measured by flowing a sample at a rate of 1.0 mm on a glass plate (30 cm x 30 cm) having a frame on all sides and pasting a release paper, at 25 ° C x 50%. And cured for 14 days in JIS A-6021
Tensile strength in normal condition (kg / cm ² ), elongation at break between marked lines (%) using a tensile tester at a tensile speed of 500 mm / min according to
Was measured.

(Non-foaming test) For non-foaming, a sample was flowed at a rate of 2 mm on a slate plate (30 cm × 30 cm) surrounded by a frame on all sides, and the surface temperature of the coating film was 80 ° C. with an infrared irradiator.
After curing by irradiating infrared rays, the coating film surface was observed for the presence of blisters and pinholes. ○: No swelling or pinholes were observed, Δ: Minor swelling or pinholes observed, ×: Crater-like bulge of 1 cm or more.

Tables 1 to 3 show the mixing conditions and test results. [Blending conditions and test results]

[0049]

[Table 1] DETDA: Diethyltoluenediamine Charcoal NS-200: Nitto Powder Chemical Heavy Calcium Carbonate Charcoal CCR: Shiraishi Calcium Fatty Acid Surface Treated Calcium Carbonate PPG3000: Polypropylene ether diol with average molecular weight of 3000

[0050]

[Table 2]

[0051]

[Table 3] TG600: polypropylene ether triol with average molecular weight of 600

[0052]

[Table 4] Note 1) After 80 minutes, a cured film was formed on the sample surface, and the measurement was interrupted because it was wound around the rotor.

In Comparative Examples 1 and 3, in which the latent crosslinking agent (block amine compound) was not contained in the curing agent, the curability was at the same level as the examples, but the pot life was short and was inferior to the examples. there were. Comparative Example 2 not containing a latent crosslinking agent (block amine compound) in the curing agent
In Comparative Example 4, the pot life was at the same level as the examples, but the curing time was long and inferior to the examples. Comparative Examples 1 to 4 were also inferior to the Examples in the non-foaming test. On the other hand, Comparative Example 5, which does not contain an active hydrogen compound such as an amine or a polyol in the curing agent and contains a latent crosslinking agent (block amine compound), is greatly affected by the curability due to humidity and is inferior to the examples. there were.

[0054]

According to the present invention, a primary or secondary amino group is formed by a main ingredient mainly composed of a urethane prepolymer (A) having two or more isocyanate groups at terminals and water as a latent crosslinking agent. By using a block amine compound and a curing agent mainly composed of an active hydrogen compound such as a polyol or an amine, the time required for curing is short despite the long pot life after mixing the main agent and the curing agent. The present invention provides a two-part curable urethane composition which is excellent in foamability even when applied at high temperatures, and a coating material, a sealing material and an adhesive using the same.

Claims (5)

[Claims] 1. A main agent comprising a urethane prepolymer (A) having two or more isocyanate groups at its terminals as a main component,
A two-part curable urethane composition comprising a curing agent mainly comprising a latent crosslinking agent (B) and an active hydrogen compound (C). 2. The latent cross-linking agent (B) is converted into a first
The urethane composition according to claim 1, wherein the urethane composition is a block amine compound that generates a secondary or secondary amino group. 3. A method according to claim 1, wherein the block amine compound is N-2-hydroxyalkyloxazolidine (b2) or / and a urethane prepolymer having at least two terminal isocyanate groups (b1), and N-2-hydroxyalkyloxazolidine (b2). 3. The composition according to claim 2, which is a urethane oxazolidine prepolymer (b3) having an oxazolidine group at a terminal obtained by reacting 4. The composition according to claim 3, wherein the urethane prepolymer (b1) having two or more isocyanate groups at the terminal contains an oxyethylene chain. 5. A coating material, a sealing material, and an adhesive comprising the composition according to claim 1.