KR100366564B1 - Processing method of the latent hardner and one-component polyurethane coating composite containing the latent hardner - Google Patents

Abstract

The present invention relates to a latent curing material, excellent in the curing properties and storage stability of the latent curing agent, the surface and the internal curing rate is uniformly controlled, bubbles and dissociated substances included in the coating is easily volatilized to the outside of the coating film It is an object of the present invention to provide a method for preparing an aldimine-oxazolidine latent curing agent which allows the inside and the outside to be uniformly cured without foaming, and a one-component coating composition comprising the curing agent. In the present invention, the aromatic aldehyde is added in an amount of 0.3 equivalents to 0.5 equivalents based on 1 equivalent of polyamine to a reactor containing a solvent and a polyamine, and then the monoglycidyl group-containing compound is added in an amount of 0.5 equivalents to 0.7 equivalents, equivalent to the remaining amine equivalents, and 30 ° C. After heating up to 100 ° C. for 3 to 4 hours, the reaction was completed, followed by addition of monoglycidyl group Aliphatic aldehyde or ketone is added in an equivalent ratio of about 1: 1.1 to 1: 2.0 over 1 hour to 2 hours, and after completion of addition of the aliphatic aldehyde or ketone, the temperature of the reactor is gradually raised to theoretical reaction. It can be achieved by providing a method for producing a latent curing agent by azeotropically extracting the condensed water and then distilling under reduced pressure to remove unreacted substances and solvents.

Description

Process of manufacturing latent hardner and one-component polyurethane coating composite containing the latent hardner

The present invention relates to a latent hardener, and more particularly, to excellent curability and storage stability of an aromatic aldimine-oxazolidine latent curing agent, and to uniformly control the surface and internal curing rate of the coating film after coating so that the coating film is not foamed. The present invention relates to a method of preparing a latent curing agent and a one-component coating composition including the curing agent, wherein the inside and the outside are uniformly cured to be widely used in various fields such as one-component paints, flooring materials, waterproofing materials, and sealing materials.

Conventionally, urethane compounds have excellent mechanical and chemical properties such as toughness, flexibility, chemical resistance, low temperature hardening, corrosion resistance, excellent adhesion to materials and blending, and have excellent mechanical and chemical properties. It is applied.

In particular, the isocyanate used as a polyurethane material has a high reactivity and is used as a two-component type that is mixed and cured when used. In particular, it is used in various materials such as paints, foams, flooring materials, waterproofing materials, and sealing materials.

However, some isocyanates are used as one-component products that are hardened by moisture in the air by using their rich reactivity. However, foaming due to carbon dioxide gas generated during curing is severely used for flooring, waterproofing and sealing materials that require post coating properties. In case of two-component type, there are problems such as short pot life, uneven mixing when used, and disposal of remaining paint.

As part of the method to solve the above problems, the development of a one-component technology for two-component materials is very active. In particular, it is necessary to solve problems such as two-component curing time and uneven mixing during use and discard the remaining paint after use. In order to reduce industrial waste and seek convenience of the user, much research is being conducted on the development of a one-component composition using a latent curing agent having the advantages of a two-part paint.

In particular, ketimines, enamines, aldimines and oxazolidines amine-blocked as latent curing agents for one-component urethanes have been actively studied.

Among them, ketamine and enamine are poor in hydrolysis stability, so they are very poor in storage stability and cannot be applied as urethane latent curing agents.Aldimine synthesized using aliphatic aldehyde also has poor hydrolysis stability and aromatic aldehyde. Aldimine synthesized by using has the disadvantage that the aromatic aldehyde dissociated in the curing process has a low volatility, so that cracking foaming occurs, it is difficult to use the waterproofing material, flooring material and the like which require a post-coating film.

In addition, oxazolidine has a good hydrolysis stability and is currently commercialized as a latent curing agent, but is mainly synthesized with aliphatic aldehyde, so that the surface drying is quick and the internal drying is late due to post-coating, so that aldehyde dissociated by hydrolysis cannot be volatilized. The cause of foaming and complete curing is very late, so there is a problem that can not be used, especially in winter.

In order to compensate for these disadvantages, Japanese Patent Application Laid-Open No. 09-278857 discloses a method of improving storage and drying properties by using an acid catalyst having an acid hazard index (pKa) of 1.0 to 4.0, but the drying property is greatly improved, but the storage stability is poor. have.

In addition, Japanese Patent Application Laid-Open No. 11-35819 discloses a technique for improving dryness and hardenability by using a specific silyl ester, but long-chain carboxylic acid generated by hydrolysis of the silyl ester has a low acidity, which does not significantly improve dryness and hardenability. .

Japanese Patent Laid-Open No. 11-269244 discloses dialkylmalonate and acetosan esters, which are hydrocarbon compounds having CH bonds with a pKa value of 16 or less for the purpose of improving the dryness and storage properties of monoisocyanate prepolymer and oxazolidine. The back light is disclosed, but the effect is weak and the storage stability is poor.

In addition, U.S. Patent 4,504,647 discloses a technique of partially opening a diamine or a polyamine with a monomer having an epoxy group to synthesize polyamino alcohol and dehydrating condensation of aliphatic aldehyde to include aldimine and oxazolidine in one chain. It contains a problem that the storage stability is poor.

In addition, U.S. Patent No. 5,591,819 discloses a synthesis method that includes aldimine and oxazolidine in one chain, but due to poor storage stability due to aliphatic aldimine, it is difficult to use as a urethane monolithic latent curing agent and is used only as a moisture removal agent. This was possible.

Meanwhile, in Korean Patent No. 0192201, a kedi monomer and an aldehyde are reacted with a dihydric or trivalent primary amine at a ratio of 30 to 70% to synthesize polyadimine-ketamine, and then use the synthesized polyaldimine-ketamine. The one-component polyurethane composition for moisture hardening is disclosed, but it contains ketimine with poor hydrolytic stability and very poor storage stability.

Accordingly, the present invention is to improve the above-mentioned conventional problems, excellent curing properties and storage stability of the latent curing agent, the surface and the internal curing rate is uniformly controlled, bubbles and dissociated materials included in the coating is easily It is an object of the present invention to provide a method for preparing an aldimine-oxazolidine latent curing agent which allows the inside and the outside to be uniformly cured without volatilizing the coating film, and a one-component coating composition comprising the curing agent.

In order to achieve the above object, the present invention adds an aromatic aldehyde in an amount of 0.3 equivalents to 0.5 equivalents based on 1 equivalent of polyamine to a reactor containing a solvent and a polyamine, and then adds a monoglycidyl group-containing compound to 0.5 equivalents to 0.7 equivalents of the remaining amine equivalents. After the reaction was completed, the reaction was carried out for 3 hours to 4 hours, and the ratio of aliphatic aldehyde or ketone to the amount of monoglycidyl group added was 1: 1.1 to 1: 2.0. After the addition of the aliphatic aldehyde or ketone, the temperature of the reactor is gradually raised to azeotropically extract the azeotropically until the theoretical reaction condensation water is extracted, followed by distillation under reduced pressure to remove unreacted substances and solvents. It can achieve by providing the manufacturing method of a latent hardening | curing agent.

In the present invention, first, the solvent and the polyamine are added to the reactor in which the aromatic aldehyde is added in an amount of 0.3 equivalents to 0.5 equivalents relative to 1 equivalent of the polyamine, and then the monoglycidyl group-containing compound is added in an amount of 0.5 equivalents to 0.7 equivalents, equivalent to the remaining amine equivalents.

As the solvent, in order to effectively remove the water generated after the reaction, aromatic solvents such as toluene and xylene are preferred, and as the aliphatic solvent, it is preferable to use normal hexane, cyclohexane, heptane and the like.

At this time, when the amount of aromatic aldehyde is added in less than 0.3 equivalent to 1 equivalent of polyamine, there is a problem that the coating film is rapidly dried due to the surface drying of the coating film, and when the amount of the aromatic aldehyde is added more than 0.5 equivalent, the aromatic aldehyde dissociated in the coating film. Since there is a problem that cracking foaming occurs under the coating film, the amount of aromatic aldehyde is preferably added in an amount of 0.3 equivalents to 0.5 equivalents based on 1 equivalent of polyamine.

When the aromatic aldehyde is added to the polyamine as described above, it reacts with each other by an equivalent ratio, as shown in Scheme 1 below, to produce aldimine-amine.

In this case, as the polyamine, propylenediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, isophoronediamine, polyoxypropylenediamine, polyoxypropylenetriamine, and the like may be used. If desired, polyoxypropylenepolyamines having a hydrophilic chain are more preferable in terms of reaction with isocyanate prepolymers.

As the aromatic aldehyde monomer, benzaldehyde, tolualdehyde, 4-ethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde, para-anizaldehyde and para-ethoxybenzaldehyde and the like are preferable.

As described above, when the reaction of the polyamine with the aromatic aldehyde is completed and the aldimine-amine is formed, 0.5 equivalent of the monoglycidyl group-containing compound is equivalent to that of the remaining amine in order to react the aldimine-amine with the monoglycidyl group-containing compound again. To 0.7 equivalent ratio.

At this time, when the monoglycidyl group-containing compound is added, the secondary amine and the hydroxyl group are formed by reacting with the aldimine-amine as shown in Scheme 2 below.

In this case, the monoglycidyl group-containing compound includes propylene oxide, butylglycidyl ether, phenylglycidyl ether, 2-ethylhexyl glycidyl ether, 2-methylglycidyl ether, Kadura E10 (trade name of Shell Chemical Company), and the like. This can be used, and propylene oxide and butylglycidyl ether are more preferable.

When the aldehyde generation is completed by adding the aromatic aldehyde and the monoglycidyl group-containing compound to the polyamine as described above, the ratio of the aliphatic aldehyde or the ketone to the added amount of the glycidyl group is 1: 1.1 to 1: 2.0 in an equivalent ratio. Mucus is added over 1 to 2 hours, and then the temperature of the reactor is gradually raised to azeotropically extracted until the theoretical reaction condensed water is extracted, followed by distillation under reduced pressure to remove unreacted substances and solvents.

At this time, if the azeotropic extraction by adding aliphatic aldehyde or ketone to the compound produced by the reaction formula 2, it is possible to produce a latent hardening material according to the present invention as shown in the following reaction formula 3.

If the amount of aliphatic aldehyde or ketone is added in an equivalent ratio of less than 1: 1.1 with respect to the amount of glycidyl group, a problem arises as long as the yield is lowered. Since the problem occurs, it is preferable that the amount of aliphatic aldehyde or ketone added is added in an equivalent ratio of 1: 1.1 to 1: 2.0 with respect to the amount of glycidyl group added.

In particular, when the aliphatic aldehyde is added, it is preferable to add 1.1 to 1.2 times the monoglycidyl group equivalent, and when adding the ketone compound, it is preferable to add 1.2 to 2 times the monoglycidyl group equivalent. Do.

As the aliphatic aldehydes, it is preferable to use acetaldehyde, butyl aldehyde, isobutyl aldehyde, normal hexyl aldehyde, and the like. As ketone monomers, methyl normal amyl ketone, methyl iso amyl ketone, ethyl butyl ketone, diisobutyl ketone, It is preferable to use isobutylheptyl ketone, isophorone, cyclohexanone and the like.

At this time, when the aliphatic aldehyde or ketone is added, the mucus is added over 1 hour to 2 hours. In this case, the addition time does not need to exceed 2 hours. Rather, the reaction time is long and the productivity is lowered. If less than 1 hour exothermic heat is difficult to control the reaction occurs because the aliphatic aldehyde or ketone is preferably added mucus over 1 to 2 hours.

In particular, in order to promote the reaction in the reaction process, a small amount may be added as a catalyst using acetate acid, dialkyl ester phosphoric acid, and the like.

When added during the production of one-component paints using the latent curing agent prepared according to the present invention as described above, the one-component paints prepared are not cured when not in use, so that they can be stored for a long time. The curing agent is hydrolyzed to produce a reactive hydrogen group-containing reactor, which is cured by reacting with isocyanate contained in the polyurethane in the one-component paint.

That is, when applying a one-component paint prepared by mixing a latent curing agent, aldimine-oxazolidine, a latent curing agent, is hydrolyzed by moisture in the air so that the aldimine group produces a primary amine group and the oxazolidine group is 2 By forming a secondary amine group and a hydroxyl group to form crosslinks by addition reaction of the isocyanate group of the polyurethane to cure it does not generate carbon dioxide gas generated during the curing of the conventional moisture-curable polyuretin does not cause foaming.

In particular, in order to provide a more effective one-part paint using the aldimine-oxazolidine latent curing agent prepared according to the present invention, the present invention is conventionally composed of an isocyanate prepolymer containing an isocyanate group, a curing agent, a solvent, and other additives. In the one-component coating composition according to claim 1, wherein the curing agent is mixed so that the NCO ratio of the isocyanate prepolymer is 1: 1.5 to 1: 3 with respect to the active hydrogen equivalent of the aromatic aldimine-oxazolidine. Provided is a one-component coating composition comprising a zolidine latent curing agent.

When the NCO ratio of the isocyanate prepolymer is less than 1: 1.5 with respect to the active hydrogen equivalent in the aromatic aldimine-oxazolidine prepared by the present invention, the storage stability is lowered and the elongation rate and tensile strength of the cured coating film are lowered. If the ratio exceeds 1: 3, the curability decreases and the coating film is foamed when the coating film is cured. Therefore, the NCO ratio of the isocyanate prepolymer is 1: 1.5 with respect to the active hydrogen equivalent contained in the aldimine group in aldimine-oxazolidine. It is preferable to mix and set so that it may become 1: 3.

In particular, the NCO ratio of the isocyanate prepolymer is more preferably 1: 1.6 to 1: 2.5 with respect to the active hydrogen equivalent of aldimine-oxazolidine.

At this time, the one-component coating composition having the above composition was introduced into a dissolva-type reactor capable of vacuum dehydration according to a conventional one-component coating method, and heated to about 110 ° C. while sufficiently mixed and stirred to dehydrate, and then cooled to room temperature. Then, a polyisocyanate prepolymer is added, the mixture is sufficiently stirred, and the mixture is stirred uniformly by adding aromatic aldimine-oxazolidine, a latent curing agent, and then sealed in a container filled with vacuum degassed dry nitrogen and completely sealed. It will be able to produce a coating composition.

The one-component polyurethane composition for curing at room temperature prepared by the above method has a storage stability of 5 months or more in an airtight container and a fast curing property when applied, and the cured coating film has excellent mechanical and chemical properties because it is not foamed even after 2 mm or more. It can be monolithic for waterproofing, flooring, sealants, paints or adhesives.

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

<Examples 1 to 7>

In a four-necked flask equipped with a stirrer, a nitrogen inlet tube, a thermometer, a water separator, and a dropping funnel, 200 g of polyoxypropylene diamine having a weight average molecular weight of 230 and 100 g of toluene were added with a solvent and stirred under a stream of nitrogen, and the temperature of the reaction section was adjusted to benzaldehyde at room temperature. The amount shown in the following Table 1 was added to the mucus for 1.5 hours while maintaining the temperature of the reaction portion at 40 ℃ and maintained at that temperature for 1 hour and then the amount shown in Table 1 to the butyl glycidyl ether over 1 hour After the addition, the temperature of the reaction part was gradually raised, the reaction part was kept at 80 ° C. for 4 hours, cooled to room temperature, and isobutyl aldehyde was added mucus for 1.5 hours while paying attention to the exotherm in the amount shown in Table 1 below. The mixture was gradually heated and azeotropically extracted until the reaction condensed water was azeotropically extracted. It was prepared oxazolidine latent curing agent.

division Addition amount of polyoxypropylene diamine (g) Benzaldehyde addition amount (g) Butyl glycidyl ether addition amount (g) Polyoxypropylene diamine equivalent: benzaldehyde equivalent ratio Isobutylaldehyde addition amount (g) Butyl glycidyl ether equivalent: butyl aldehyde equivalent ratio Example 1 230 21.2 234.4 1: 0.1 155.5 1: 1.2 Example 2 230 63.7 182.3 1: 0.3 121 1: 1.2 Example 3 230 84.9 156.2 1: 0.4 103.7 1: 1.2 Example 4 230 106.1 130.2 1: 0.5 86.4 1: 1.2 Example 5 230 148.6 78.1 1: 0.7 51.8 1: 1.2 Example 6 230 84.9 156.2 1: 0.4 216 1: 0.9 Example 7 230 84.9 156.2 1: 0.4 77.8 1: 2.5

Comparative Example 1

Under the same conditions as in Example, 230 g of polyoxypropylene diamine having a weight average molecular weight of 230 and 100 g of toluene were added to the reaction portion, and the mixture solution of 73 g of isobutylaldehyde and 107 g of benzaldehyde was added to the reaction mixture under a nitrogen stream for 2 hours while being cautious of exotherm at room temperature. Thereafter, the temperature of the reaction unit was gradually raised to react until the reaction condensed water was azeotropically dehydrated, and then subjected to azeotropic extraction. At this temperature, unreacted material and toluene were removed by distillation under reduced pressure to prepare an aldimine latent curing agent.

Experimental Examples 1 to 7

By using the latent curing agent prepared in Examples 1 to 7 according to the conventional one-component paint production method, the additive amount of each additive was mixed in the ratio of Table 2 below to prepare a one-component paint and then touched by the following method. Drying, curing drying, coating foaming and storage stability were measured and shown in Table 2. At this time, the isocyanate prepolymer included in the usual one-component paint was used by self-synthesis by the following method.

Preparation of Isocyanate Prepolymers

105 g of toluene diisocyanate (TDI-80) was added to a four-necked flask equipped with a stirrer, a nitrogen injection tube, a thermometer, and a dropping funnel, and the reaction mixture was dehydrated at 45 ° C. to 50 ° C. under nitrogen flow, and then dehydrated. 570 g of phosphorus polyoxypropylene glycol and 281 g of polyoxypropylene triol having a weight average molecular weight of 4000 were added dropwise and stirred for 2 hours while suppressing the heat generation of the reaction portion, and after the dropping was completed, the temperature was raised to 80 ° C. over about 1 hour to about 5 The reaction was carried out for a time to synthesize a polyurethane prepolymer having an isocyanate at the end. At this time, the degree of progress of the reaction was calculated by the method of titration using normal dibutylamine, which is generally used, and the content of preisocyanate of the synthesized polyisocyanate prepolymer was 2.75%.

-Touch drying and hardening drying-

Tack drying time was measured according to the test method of building sealing material of KS F 4910, and hardening drying was measured as the time that top coating is possible.

-Whether the film is foamed-

One-component paints were prepared to measure the coating film foaming, so that the dry coating thickness was 2mm, and after complete drying, the coating film was cut and visually confirmed whether bubbles were formed on the cut surface of the coating film.

-Storage stability-

After storage for 5 days in a thermostatic chamber at 50 ℃ was measured by the Brookfield viscometer at the beginning of the formulation and the viscosity after storage. At this time, the smaller the change in viscosity was determined to be excellent storage stability.

<Comparative Experimental Examples 1 and 2>

The ratio of addition of each additive to the aldimine latent curing agent prepared in Comparative Example 1 and the oxazolidine latent curing agent named Incozol LV (Industrial Co., Ltd.) according to a conventional one-component coating method is shown in Table 2 below. After preparing a one-component coating by mixing in the same manner as in Experimental Examples 1 to 7 it was shown in Table 2 by measuring the drying, curing drying, coating film foaming and storage stability.

division Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Experimental Example 6 Experimental Example 7 Comparative Example 1 Comparative Experiment 2 Isocyanate prepolymer addition amount (g) 400 400 400 400 400 400 400 400 400 Filler (calcium carbonate) addition amount (g) 400 400 400 400 400 400 400 400 400 Coloring agent (chrome green) addition amount (g) 15 15 15 15 15 15 15 15 15 Amount of plasticizer (DOP) added (g) 50 50 50 50 50 50 50 - - Diluent (xylene) addition amount (g) 80 80 80 80 80 80 80 80 80 Latent Hardener Addition (g) Example 1 25 g Example 2 25 g Example 3 25 g Example 4 25 g Example 5 25 g Example 6 25 g Example 7 25 g 25g of aldimine Oxazolidine 25g Other additives (g) 30 30 30 30 30 30 30 30 30 Dry touch 20 8 6.5 6 6 6 6 6 36 Curing drying 48 20 16 16 16 16 16 16 72 Coating foam none none none none has exist none has exist has exist none Storage stability 1.4 1.5 1.5 1.5 2.5 1.5 Gel Gel 3

In Examples 1 to 7 using the aromatic aldimine-oxazolidine latent curing agent as shown in Table 2, the equivalent ratio of the aromatic aldehyde and the polyamine is 0.3 to 0.5 in the range of the present invention prepared in Examples 2 to 4 The one-component paints of Experimental Examples 2 to 4 using the latent hardener can be confirmed that the drying, curing drying and storage stability are excellent and foaming does not occur in the coating film, but is prepared by Example 1 below the scope of the present invention. Experimental Example 1 using the latent hardener is excellent in storage stability and the coating film was not foamed, but it can be seen that the touch drying and curing drying properties are reduced, and also the latent produced by Example 5 carried out beyond the scope of the present invention. In the case of Experiment 5 using the biphasic agent, it was found that the touch drying and curing drying properties were excellent, but there was foaming in the coating film and the storage stability was lowered. Can.

In addition, in the case of Example 6 in which the addition ratio of the aromatic aldehyde to the glycidyl group-containing content is within the scope of the present invention, compared to Example 7 carried out below the scope of the present invention, the drying, curing drying and storage stability were excellent and foaming was applied to the coating film. It can be seen that the phenomenon does not occur.

In particular, Comparative Experimental Example 1, which was conducted using the aldimine latent curing agent prepared in Comparative Example 1, compared to the examples added within the preferred range of the present invention, while the drying and curing drying shows a similar tendency It can be confirmed that the storage stability is poor and foaming phenomenon occurs in the coating film, Comparative Experimental Example 2 experimented with oxazolidine latent curing agent is stored compared to the examples added within the preferred range of the present invention Excellent stability and foaming does not occur in the coating film, but it can be confirmed through Table 2 that the touch drying and curing drying properties are lowered.

As described above, the present invention has excellent curability and storage stability of the latent curing agent, and the surface and internal curing rate are uniformly controlled, so that bubbles and dissociated substances included in the coating are easily volatilized to the outside of the coating film so that the coating film is not foamed. It is a useful invention to provide a process for preparing an aldimine-oxazolidine latent curing agent and a one-component coating composition comprising the curing agent so that the inside and the outside can be uniformly cured.

Claims (10)

Benzaldehyde, tolu with respect to 1 equivalent of polyamine in a reactor containing a solvent and a polyamine selected from propylenediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, isophoronediamine, polyoxypropylenediamine or polyoxypropylenetriamine An aromatic aldehyde selected from aldehyde, 4-ethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde, para-anizaldehyde or para-ethoxybenzaldehyde is added in an amount of 0.3 to 0.5 equivalents, and then propylene oxide and butyl glycidyl ether , A monoglycidyl group-containing compound selected from phenylglycidyl ether, 2-ethylhexyl glycidyl ether, and 2-methylglycidyl ether is added in an amount of 0.5 equivalents to 0.7 equivalents, equivalent to the remaining amine equivalents, and is 30 ° C to 100 After the reaction was completed, the reaction was carried out for 3 to 4 hours, and then the amount of monoglycidyl group added after the reaction was completed. The aliphatic aldehyde or ketone was added in a ratio of 1: 1.1 to 1: 2.0 in an equivalent ratio over 1 hour to 2 hours, and after the addition of the aliphatic aldehyde or ketone was completed, the temperature of the reactor was gradually raised to increase the theoretical reaction condensation ratio. A method for producing a latent curing agent by azeotropically extracting and distilling under reduced pressure until extraction to remove unreacted substances and solvents. delete delete delete delete The method of producing a latent curing agent according to claim 1, wherein when the aliphatic aldehyde is added, it is prepared using acetaldehyde, butyl aldehyde, isobutyl aldehyde or normal hexyl aldehyde. delete The method of claim 1, wherein only methyl normal amyl ketone, methyl isoamyl ketone, ethyl butyl ketone, diisobutyl ketone, isobutyl heptyl ketone, isophorone or cyclohexanone is added to the ketone. Method of producing a latent curing agent. delete In a conventional one-component coating composition composed of an isocyanate prepolymer containing an isocyanate group, a curing agent, a solvent, and other additives, The curing agent is mixed so that the NCO ratio of the isocyanate prepolymer is 1: 1.5 to 1: 3 with respect to the equivalent of active hydrogen contained in the aldimine group of the aldimine-oxazolidine latent curing agent prepared by the method of claim 1. A one-component coating composition comprising an aldimine-oxazolidine latent curing agent, characterized in that.