Coating composition with long pot life and preparation method thereof

Abstract

The invention provides a coating composition with long pot life and a preparation method thereof, and relates to the technical field of coatings. The coating composition with the long pot life is prepared from the following raw material components: A-1) aspartic ester resin, and the aspartic ester resin comprises first aspartic ester resin with an asymmetric structure; and A-2) an isocyanate curing agent. The coating composition disclosed by the invention has the characteristics of long pot life and quick drying, and is good in adhesiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings and relates to a coating composition with a long applicability period and a preparation method thereof. Background Art

[0002] Aspartic polyurea coatings are generally obtained from raw materials including aspartic acid ester resin and isocyanate curing agent. They have the characteristics of good weather resistance, good corrosion resistance, high mechanical strength, etc., and the pot life can be adjusted. For aspartic polyurea coatings, pot life and drying time are two important performance indicators. They require both a long pot life and a short drying time, that is, quick drying. Taking Feiyang Junyan's F420 resin and F520 resin as examples, F420 resin has a short pot life and quick drying, while F520 resin has a long pot life and slow drying. Adding a small amount of F520 resin to F420 resin has no obvious effect on extending the pot life. Adding a larger amount of F520 resin can extend the pot life, but it also causes the drying time to become longer, which cannot meet the requirements of quick drying.

[0003] Chinese patent CN113930142A discloses a two-component coating composition, wherein component A comprises polyaspartic acid ester and component B comprises polyether-modified polyisocyanate. However, the viscosity of the two-component coating composition is relatively high, making it unsuitable for spraying, and the surface drying time is still relatively long.

[0004] Therefore, aspartame polyurea coatings with both long pot life and fast drying are still in need of improvement. Summary of the Invention

[0005] In addition, the applicant also found that the adhesion of the aspartame polyurea coating prepared by using F420 resin and F520 resin alone or in combination is not good enough, especially the adhesion on tinplate is poor.

[0006] In order to solve the above technical problems, on the one hand, the present invention provides a coating composition with a long working life, which has the characteristics of long working life and fast drying, and has good adhesion after film formation on tinplate.

[0007] On the other hand, the present invention also provides a method for preparing a coating composition with a long pot life.

[0008] The technical solutions of the present invention are as follows:

[0009] A coating composition with a long pot life comprises the following raw material components:

[0010] A-1) an aspartic acid ester resin, wherein the aspartic acid ester resin comprises a first aspartic acid ester resin, wherein the first aspartic acid ester resin has a structure represented by the following formula (1):

[0011]

[0012] wherein R1 and R2 are independently selected from C1-C3 alkyl, R3 and R4 are independently selected from C4-C8 alkyl, R5 and R6 are independently selected from H or C1-C4 alkyl, and R5 and R6 are not H at the same time;

[0013] and, A-2) an isocyanate curing agent.

[0014] Preferably, the first aspartic acid ester resin is obtained by Michael addition reaction of a cyclohexanediamine compound represented by the following formula (2) with a first unsaturated ester represented by the following formula (3) and a second unsaturated ester represented by the following formula (4),

[0015]

[0016] R3OOCCH=CHCOOR4 (3),

[0017] R1OOCCH=CHCOOR2 (4).

[0018] More preferably, the molar ratio of the cyclohexanediamine compound to the first unsaturated ester is 1:0.8-1.2.

[0019] More preferably, the molar ratio of the cyclohexanediamine compound to the second unsaturated ester is 1:0.8-1.2.

[0020] Preferably, the cyclohexanediamine compound first reacts with the first unsaturated ester and then reacts with the second unsaturated ester.

[0021] Preferably, R1 and R2 are the same, and R3 and R4 are the same.

[0022] Preferably, the R5 is H or methyl, and the R6 is methyl.

[0023] Preferably, the aspartic acid ester resin further comprises a second aspartic acid ester resin, and the weight ratio of the first aspartic acid ester resin to the second aspartic acid ester resin is 1:3-10:1;

[0024] The second aspartic acid ester resin is selected from one or a combination of two or more of Feiyang Junyan's F420 resin, F520 resin, F220 resin, F421 resin, F221 resin, F423 resin, F2872 resin, F2886 resin, F330 resin and F2850 resin.

[0025] Preferably, the molar ratio of the NH groups in the aspartic acid ester resin to the NCO groups in the isocyanate curing agent is 1:1-1.2.

[0026] Preferably, the raw material components further include one or a combination of two or more of fillers, pigments, dispersants, wetting agents, leveling agents, defoamers, anti-ultraviolet agents, anti-yellowing agents, antioxidants, water absorbents and anti-settling agents.

[0027] The beneficial effects of the present invention are:

[0028] (1) The present invention designs the structure of the first aspartic acid ester resin, wherein the two secondary amine groups have different activities, so that the coating composition of the present invention has both a long working life and fast drying.

[0029] (2) The first aspartic acid ester resin of the present invention has a relatively low viscosity (viscosity ≤ 350 mPa·s at 25° C.), which makes the coating composition of the present invention suitable for spraying process, and the cured coating has good adhesion to the substrate (such as tinplate). DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0031] In one aspect, the present invention provides a coating composition with a long pot life, comprising the following raw material components:

[0032] A-1) Aspartic acid ester resin, the aspartic acid ester resin includes a first aspartic acid ester resin, and the first aspartic acid ester resin has a structure represented by the following formula (1),

[0033]

[0034] wherein R1 and R2 are independently selected from C1-C3 alkyl, R3 and R4 are independently selected from C4-C8 alkyl, R5 and R6 are independently selected from H or C1-C4 alkyl, and R5 and R6 are not H at the same time;

[0035] and, A-2) an isocyanate curing agent.

[0036] The coating composition of the present invention comprises a first aspartic acid ester resin, the structure of the first aspartic acid ester resin is asymmetric, R1 and R2 are independently selected from C1-C3 alkyl groups, R3 and R4 are independently selected from C4-C8 alkyl groups, the two secondary amine groups are subjected to different steric hindrances by R1, R2, R3 and R4, the secondary amine group close to R1 and R2 (secondary amine group 1) is subjected to less steric hindrance by R1 and R2 than the secondary amine group close to R3 and R4 (secondary amine group 2) is subjected to steric hindrance by R3 and R4, the secondary amine group with low steric hindrance provides a quick-drying effect, and the secondary amine group with high steric hindrance provides a long pot life effect.

[0037] For the isocyanate curing agent, it can be an isocyanate trimer such as HT-600, HT-100, HI-100, TPA-100, or a combination of the above isocyanate trimer and a diisocyanate monomer, such as a combination of HT-600 and IPDI, a combination of HT-600 and HMDI, a combination of HT-100 and HMDI, etc.

[0038] The adhesion of the aspartame polyurea coating composed of existing F420 resin, F520 resin, etc. is not good enough. The present invention unexpectedly found that the above coating composition has the characteristics of long pot life and fast drying, and also has good adhesion to the substrate.

[0039] In some embodiments, the first aspartic acid ester resin is obtained by Michael addition reaction of a cyclohexanediamine compound represented by the following formula (2) with a first unsaturated ester represented by the following formula (3) and a second unsaturated ester represented by the following formula (4),

[0040]

[0041] R3OOCCH=CHCOOR4 (3),

[0042] R1OOCCH=CHCOOR2 (4).

[0043] Due to the asymmetric structure of the first aspartic acid ester resin, the first aspartic acid ester resin can be obtained via a two-step Michael addition reaction. The preparation of aspartic acid ester resins via the Michael addition reaction is a technique well known to those skilled in the art. For example, the cyclohexanediamine compound may be 2,4-dimethyl-1,3-cyclohexanediamine, 2-methyl-1,3-cyclohexanediamine, 4-methyl-1,3-cyclohexanediamine, etc.; the first unsaturated ester may be dibutyl maleate, dihexyl maleate, dioctyl maleate, diisoamyl maleate, etc.; and the second unsaturated ester may be dimethyl maleate, diethyl maleate, di-n-propyl maleate, etc.

[0044] In some embodiments, the molar ratio of the cyclohexanediamine compound to the first unsaturated ester is 1:0.8-1.2. For example, the molar ratio can be any value or any value in between 1:0.8, 1:0.85, 1:0.87, 1:0.88, 1:0.9, 1:0.92, 1:0.93, 1:0.95, 1:0.97, 1:0.98, 1:1, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.07, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.2, etc., without particular limitation. Further, the molar ratio of the cyclohexanediamine compound to the first unsaturated ester can be 1:0.9-1.1.

[0045] In some embodiments, the molar ratio of the cyclohexanediamine compound to the second unsaturated ester is 1:0.8-1.2. For example, the molar ratio can be any value or any value in between 1:0.8, 1:0.85, 1:0.87, 1:0.88, 1:0.9, 1:0.92, 1:0.93, 1:0.95, 1:0.97, 1:0.98, 1:1, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.07, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.2, etc., without particular limitation. Further, the molar ratio of the cyclohexanediamine compound to the second unsaturated ester can be 1:0.9-1.1.

[0046] In some embodiments, the cyclohexanediamine compound reacts first with the first unsaturated ester and then with the second unsaturated ester. Because the carbon chains of R3 and R4 in the first unsaturated ester are longer than the carbon chains of R1 and R2 in the second unsaturated ester, and the reactivity of the carbon-carbon double bond in the first unsaturated ester is lower than that in the second unsaturated ester, the cyclohexanediamine compound reacts first with the first unsaturated ester and then with the second unsaturated ester, thereby allowing both the first unsaturated ester and the second unsaturated ester to react relatively completely, thereby obtaining the first aspartic acid ester resin represented by formula (1).

[0047] In some embodiments, R1 and R2 are the same, R3 and R4 are the same, the first unsaturated ester and the second unsaturated ester are easier to obtain and have lower cost, for example, dimethyl maleate, diethyl maleate, di-n-butyl maleate, etc. can be directly obtained from the market in batch production.

[0048] In some embodiments, R5 is H or a methyl group, and R6 is a methyl group, further increasing the asymmetry of the first aspartic acid ester resin structure. Furthermore, due to the significant steric hindrance of R6 on the adjacent secondary amine group 1, the reactivity of the secondary amine group 1 is significantly reduced and is lower than that of the secondary amine group 2. If R5 is further a methyl group, R5 sterically hinders the secondary amine groups 1 and 2, reducing their reactivity. Due to the different overall steric hindrance experienced, the secondary amine groups 1 and 2 have different reactivities. However, the secondary amine groups with low steric hindrance still provide a quick-drying effect, and the secondary amine groups with high steric hindrance still provide a long pot life.

[0049] In some embodiments, the aspartic acid ester resin further comprises a second aspartic acid ester resin, and the weight ratio of the first aspartic acid ester resin to the second aspartic acid ester resin is 1:3-10:1;

[0050] In the present invention, there is no particular limitation on the second aspartic acid ester resin, which can be directly obtained from the market, such as one or a combination of two or more of F420 resin, F520 resin, F220 resin, F421 resin, F221 resin, F423 resin, F2872 resin, F2886 resin, F330 resin and F2850 resin from Feiyang Junyan Company.

[0051] The weight ratio of the first aspartic acid ester resin to the second aspartic acid ester resin can be, for example, any value among 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., or any value in between, without particular limitation.

[0052] In some embodiments, the molar ratio of the NH group in the aspartic acid ester resin to the NCO group in the isocyanate curing agent is 1:1-1.2, which can achieve a better curing effect. For example, the molar ratio can be any value among 1:1, 1:1.02, 1:1.05, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.17, 1:1.2, etc., or any value in between, without special restrictions.

[0053] In some embodiments, the raw material components further include one or a combination of two or more of fillers, pigments, dispersants, wetting agents, leveling agents, defoaming agents, anti-ultraviolet agents, anti-yellowing agents, antioxidants, water absorbents and anti-settling agents. For fillers, for example, they can be kaolin, carbon black, talc, wollastonite, alumina, polytetrafluoroethylene powder, glass beads, etc., without special restrictions, and can be directly obtained from the market; for pigments, they can be phthalocyanine blue, phthalocyanine green, chrome yellow, titanium dioxide, etc., without special restrictions, and can be directly obtained from the market; for dispersants, they can be small molecule dispersants or polymer dispersants, without special restrictions, and can be directly obtained from the market; for wetting agents, they can be polyether modified silicone wetting agents, without special restrictions, and can be directly obtained from the market; for leveling agents, they can be polyether modified silicone leveling agents, without special restrictions, and can be directly obtained from the market; for defoaming agents, they can be diisocyanate. Methyl silicone defoamers are available on the market without any particular restrictions. UV inhibitors include UVP, UV-327, and UV-328, among others, without any particular restrictions. Anti-yellowing agents include HK-60, among others, without any particular restrictions. Antioxidants include antioxidants 1010 and 168, among others, without any particular restrictions. Water absorbents include molecular sieves, among others, without any particular restrictions. Anti-settling agents include fumed silica, organic bentonite, and polyamide wax, among others, without any particular restrictions. Furthermore, to further adjust viscosity or facilitate mixing and construction, a certain amount of organic solvents, such as propylene glycol methyl ether acetate (PMA) and butyl acetate, may be added to the raw material components.

[0054] In the present invention, the preparation method of the asparagus polyurea composition is not particularly limited. The raw material components except the isocyanate curing agent can be mixed and then uniformly mixed by high-speed stirring or grinding dispersion, and then the isocyanate curing agent is added and stirred to mix uniformly.

[0055] The technical solution of the present invention is further described and illustrated below based on various preparation examples and embodiments. Unless otherwise specified, the parts described in the following embodiments are parts by weight.

[0056] Preparation Example 1

[0057] The molar ratio of 4-methyl-1,3-cyclohexanediamine, di-n-butyl maleate and diethyl maleate is 1:1.05:1.05.

[0058] At room temperature, 4-methyl-1,3-cyclohexanediamine was added to a reaction vessel, the temperature of the reaction system was controlled not to exceed 40°C, di-n-butyl maleate was added dropwise, and after the addition, the temperature was raised to 40-45°C and the reaction was carried out for 24 hours. Then, diethyl maleate was added dropwise, the temperature of the reaction system was controlled not to exceed 45°C, and after the addition, the temperature was raised to 50-55°C and the reaction was carried out for 96 hours, and the reaction was continued at 55-60°C for 48 hours to obtain the first aspartic acid ester resin. The viscosity at 25°C was measured by an NDJ-5S rotational viscometer to be 186 mPa.s.

[0059] Preparation Example 2

[0060] The molar ratio of 2,4-dimethyl-1,3-cyclohexanediamine, di-n-butyl maleate and diethyl maleate is 1:1.08:1.02.

[0061] At room temperature, 2,4-dimethyl-1,3-cyclohexanediamine was added to a reaction vessel, the temperature of the reaction system was controlled not to exceed 40°C, di-n-butyl maleate was added dropwise, and after the addition was complete, the temperature was raised to 40-45°C and reacted for 24 hours, and then the temperature was raised to 55-60°C and reacted for 24 hours; diethyl maleate was added dropwise, the temperature of the reaction system was controlled not to exceed 45°C, and after the addition was complete, the temperature was raised to 50-55°C and reacted for 96 hours, and the temperature was continued to react at 55-60°C for 48 hours to obtain the first aspartic acid ester resin, and the viscosity at 25°C was 260 mPa.s as measured by an NDJ-5S rotational viscometer.

[0062] Preparation Example 3

[0063] The molar ratio of 2-methyl-1,3-cyclohexanediamine, di-n-octyl maleate and diethyl maleate is 1:1.1:1.

[0064] At room temperature, 4-methyl-1,3-cyclohexanediamine was added to a reaction vessel, the temperature of the reaction system was controlled not to exceed 40°C, di-n-octyl maleate was added dropwise, and after the addition was complete, the temperature was raised to 40-45°C and reacted for 48 hours, and then the temperature was raised to 55-60°C and reacted for 24 hours; diethyl maleate was added dropwise, the temperature of the reaction system was controlled not to exceed 45°C, and after the addition was complete, the temperature was raised to 50-55°C and reacted for 96 hours, and the temperature was continued to react at 55-60°C for 48 hours to obtain the first aspartic acid ester resin, and the viscosity at 25°C was 205 mPa.s as measured by an NDJ-5S rotational viscometer.

[0065] Example 1

[0066] The aspartic polyurea coating composition is composed of an aspartic acid ester resin and an isocyanate curing agent in a molar ratio of NH groups to NCO groups of 1:1.05;

[0067] The aspartic acid ester resin is the first aspartic acid ester resin in the above-mentioned Preparation Example 1;

[0068] The isocyanate curing agent is HT-600.

[0069] Example 2

[0070] The difference between this example and Example 1 is that in Example 1, the first aspartic acid ester resin in Preparation Example 1 is replaced by the first aspartic acid ester resin in Preparation Example 2 in terms of NH groups in an equimolar ratio. The remaining steps remain unchanged.

[0071] Example 3

[0072] The difference between this example and Example 1 is that in Example 1, the first aspartic acid ester resin in Preparation Example 1 is replaced by the first aspartic acid ester resin in Preparation Example 3 in terms of NH groups in an equal molar ratio. The remaining steps remain unchanged.

[0073] Example 4

[0074] The difference between this example and Example 1 is that in Example 1, the first aspartic acid ester resin in Preparation Example 1 is replaced with an equimolar NH group combination of the first aspartic acid ester resin in Preparation Example 1 and F420 resin in a weight ratio of 2:1. The remaining steps remain unchanged.

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 1 is that in Example 1, the first aspartic acid ester resin in Preparation Example 1 is replaced by a combination of F420 resin and F520 resin in a weight ratio of 2:1 in terms of NH groups in an equimolar ratio. The remaining steps remain unchanged.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that in Example 1, the first aspartic acid ester resin in Preparation Example 1 is replaced by a combination of F420 resin and F520 resin in a weight ratio of 1:2 in terms of NH groups in an equimolar ratio. The remaining steps remain unchanged.

[0079] Pot life: the time it takes for the viscosity of the aspartame polyurea composition to rise to 10,000 mPa.s at 25°C.

[0080] Surface drying time and through drying time: tested according to the method of GB / T 1728-2020.

[0081] Coating Adhesion: The aspartame polyurea composition was applied to a clean tinplate surface and left at room temperature for 48 hours before testing adhesion using the cross-grid method (1 mm). Adhesion was graded from 1 to 5, with grade 1 being the best and grade 5 being the worst.

[0082] The results are shown in Table 1 below.

[0083] Table 1

[0084] Pot life / min Surface drying time / min Drying time / min Adhesion / Grade Example 1 45 107 430 Level 1 Example 2 48 115 460 Level 1 Example 3 46 109 442 Level 1 Example 4 37 61 389 Level 1 Comparative Example 1 20 22 90 Level 4 Comparative Example 2 29 51 117 Level 3

[0085] Therefore, it can be seen from the data results in Table 1 that the aspartame polyurea composition of the present invention has the characteristics of a long pot life and quick drying, and has good adhesion.

[0086] Example 5

[0087] The raw material components consist of 400 parts of the first aspartic acid ester resin obtained in Preparation Example 2, 450 parts of titanium dioxide, 40 parts of molecular sieves, 10 parts of fumed silica, 2 parts of polyether-modified silicone leveling agent, 3 parts of dimethyl silicone oil defoaming agent, 10 parts of ultraviolet absorber, 80 parts of a mixed solvent (consisting of 40 parts of PMA and 40 parts of butyl acetate) and HT-600 curing agent.

[0088] The molar ratio of the NH groups in the first aspartic acid ester resin to the NCO groups in HT-600 was 1:1.05.

[0089] The raw material components except the HT-600 curing agent are added to a stirring container, the stirring speed is adjusted to 500 rpm and stirred for 10 minutes, then the stirring speed is adjusted to 1500 rpm and stirred for 30 minutes, then the stirring speed is adjusted to 1000 rpm and stirred for 15 minutes, then the stirring speed is adjusted to 500 rpm and stirred for 10 minutes, the HT-600 curing agent is added, and stirring is continued for 10 minutes to obtain the aspartame polyurea composition.

[0090] Example 6

[0091] The difference between this example and Example 5 is that in Example 5, 400 parts of the first aspartic acid ester resin obtained in Preparation Example 2 were adjusted to a combination of 300 parts of the first aspartic acid ester resin obtained in Preparation Example 2 and 100 parts of the first aspartic acid ester resin obtained in Preparation Example 1. The remaining steps remained unchanged.

[0092] Example 7

[0093] The difference between this example and Example 5 is that in Example 5, 400 parts of the first aspartic acid ester resin obtained in Preparation Example 2 were adjusted to a combination of 300 parts of the first aspartic acid ester resin obtained in Preparation Example 2 and 100 parts of F420 resin. The remaining steps remained unchanged.

[0094] Example 8

[0095] The difference between this example and Example 5 is that in Example 5, 400 parts of the first aspartic acid ester resin obtained in Preparation Example 2 were adjusted to a combination of 300 parts of the first aspartic acid ester resin obtained in Preparation Example 2 and 100 parts of F520 resin. The remaining steps remained unchanged.

[0096] Comparative Example 3

[0097] The difference between this comparative example and Example 5 is that in Example 5, the first aspartic acid ester resin obtained in Preparation Example 2 was adjusted to an equal weight of F420 resin. The remaining steps remained unchanged.

[0098] Comparative Example 4

[0099] The difference between this comparative example and Example 5 is that in Example 5, the first aspartic acid ester resin obtained in Preparation Example 2 was adjusted to an equal weight of F520 resin. The remaining steps remained unchanged.

[0100] Comparative Example 5

[0101] The difference between this example and Example 5 is that in Example 5, 400 parts of the first aspartic acid ester resin obtained in Preparation Example 2 are adjusted to a combination of 200 parts of F420 resin and 200 parts of F520 resin. The remaining steps remain unchanged.

[0102] The results are shown in Table 2 below.

[0103] Table 2

[0104] Applicable period / h Surface drying time / min Drying time / h Adhesion / Grade Example 5 3 120 10 1 Example 6 2.5 97 8 1 Example 7 3 62 6 1 Example 8 3 174 14 1 Comparative Example 3 0.2 17 1.5 5 Comparative Example 4 4 248 20 2 Comparative Example 5 0.7 50 1.8 3

[0105] Therefore, it can be seen from the data results in Table 2 that the aspartame polyurea coating of the present invention has the characteristics of a long working life and quick drying, and has good adhesion.

[0106] As described above, the basic principles, main features, and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A coating composition having a long pot life, characterized in that Contains the following raw materials: A-1) an aspartic acid ester resin, wherein the aspartic acid ester resin comprises a first aspartic acid ester resin, wherein the first aspartic acid ester resin has a structure represented by the following formula (1): wherein R1 and R2 are independently selected from C1-C3 alkyl, R3 and R4 are independently selected from C4-C8 alkyl, R5 and R6 are independently selected from H or C1-C4 alkyl, and R5 and R6 are not H at the same time; and, A-2) an isocyanate curing agent.

2. The coating composition according to claim 1, wherein The first aspartic acid ester resin is obtained by Michael addition reaction of a cyclohexanediamine compound represented by the following formula (2) with a first unsaturated ester represented by the following formula (3) and a second unsaturated ester represented by the following formula (4), R3OOCCH=CHCOOR4 (3), R1OOCCH=CHCOOR2 (4).

3. The coating composition according to claim 2, characterized in that The molar ratio of the cyclohexanediamine compound to the first unsaturated ester is 1:0.8-1.

2.

4. The coating composition according to claim 2, characterized in that The molar ratio of the cyclohexanediamine compound to the second unsaturated ester is 1:0.8-1.

2.

5. The coating composition according to claim 1, wherein The cyclohexanediamine compound first reacts with the first unsaturated ester and then reacts with the second unsaturated ester.

6. The coating composition according to claim 1, characterized in that The R1 and R2 are the same, and the R3 and R4 are the same.

7. The coating composition according to claim 1, wherein The R5 is H or methyl, and the R6 is methyl.

8. The coating composition according to claim 1, wherein The aspartic acid ester resin further comprises a second aspartic acid ester resin, and the weight ratio of the first aspartic acid ester resin to the second aspartic acid ester resin is 1:3-10:1; The second aspartic acid ester resin is selected from one or a combination of two or more of Feiyang Junyan's F420 resin, F520 resin, F220 resin, F421 resin, F221 resin, F423 resin, F2872 resin, F2886 resin, F330 resin and F2850 resin.

9. The coating composition according to claim 1, wherein The molar ratio of the NH groups in the aspartic acid ester resin to the NCO groups in the isocyanate curing agent is 1:1-1.

2.

10. The coating composition according to claim 1, characterized in that The raw material components further include one or a combination of two or more of fillers, pigments, dispersants, wetting agents, leveling agents, defoamers, anti-ultraviolet agents, anti-yellowing agents, antioxidants, water absorbents and anti-settling agents.

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