Aminopyrimidine-modified polyaspartate polyurea coating, its preparation method and application

Abstract

The present invention discloses an amino-pyrimidine modified polyaspartate polyurea coating, its preparation method and application. The coating comprises a polyether polyol prepolymer with an R(NCO / NH) value of 1.05, a polyaspartate ester and a modified amino-pyrimidine solution. The preparation method includes dissolving 2,4,6-triaminopyrimidine in a solvent and dropping a silane coupling agent to obtain the modified amino-pyrimidine; mixing polytetrahydrofuran diol and polypropylene glycol in a mass ratio of 2:3 and adding isophorone diisocyanate to obtain the polyether polyol prepolymer; reacting the polyether polyol prepolymer with an R(NCO / NH) value of 1.05 with the polyaspartate ester and the modified amino-pyrimidine to obtain the finished product. The coating of the present invention has the characteristics of high mechanical properties and strong anti-fouling properties, and the preparation method has the characteristics of controllable reaction rate and stable reaction.

Description

Technical Field

[0001] The present invention relates to a modified polyaspartate polyurea coating, in particular to an aminopyrimidine-modified polyaspartate polyurea coating, a preparation method thereof and an application thereof. Background Art

[0002] Marine biofouling is a difficult problem to be faced in the process of developing resources. At present, applying marine antifouling coatings is the most economical and effective means to prevent marine biofouling. Among antifouling coatings, self-polishing coatings and fouling-release coatings have been studied more. However, the antifouling effect of self-polishing coatings comes from antifouling agents. By hydrolyzing and releasing antifouling agents into the environment to avoid the attachment of marine fouling organisms, and most of the mainstream antifouling agents are heavy metal ions. The release of these heavy metal ions will cause their accumulation in organisms, resulting in an impact on the ecosystem and a greater impact on the environment; fouling-release coatings avoid the attachment of fouling organisms through hydrodynamic shear force and low surface energy. Although they will not cause an impact on the environment, their antifouling ability under static conditions is limited, their mechanical properties are generally poor, their adhesion to substrates is weak, and they are easily damaged, so they cannot better adapt to the marine environment. Therefore, developing coatings that take into account both antifouling performance and resistance to damage has become a new trend at present.

[0003] Modified coatings with polyurethane as the main body are a research hotspot in the field of marine antifouling coatings. Generally speaking, polyurethane coatings themselves do not have antifouling ability. Therefore, substances with antifouling activity are selected to modify polyurethane, which can not only retain the excellent mechanical properties of the original polyurethane, but also endow it with antifouling ability.

[0004] When selecting antifouling substances, multiple aspects need to be noted, such as reactivity, stability, etc. Heterocyclic compounds, as an important type of compound, are widely used in fields such as pharmaceuticals and biological tests. Currently, most antifouling agents mostly have heterocyclic structures. Many heterocyclic compounds and their derivatives are considered to have potential activities. Pyrimidine is a heterocyclic compound formed by replacing two carbon atoms in the meta position of benzene with two nitrogen atoms. It has certain antifouling ability and the potential to graft into the resin matrix. However, the primary amino group it contains has too fast a reaction rate, the reaction process is not easy to control, it is difficult to ensure the progress of the next reaction, resulting in poor reaction stability and the inability to guarantee the product quality. Therefore, it is difficult to use pyrimidine as an antifouling substance to prepare antifouling coatings. Summary of the Invention

[0005] The purpose of the present invention is to provide an aminopyrimidine-modified polyaspartate polyurea coating, a preparation method thereof and an application thereof. The coating of the present invention has the characteristics of high mechanical properties and strong antifouling performance, and the preparation method has the characteristics of controllable reaction rate and stable reaction.

[0006] Technical solution of the present invention: An amino-pyrimidine modified polyaspartate polyurea coating, which comprises a polyether polyol prepolymer with an R(NCO / NH) value of 1.05, a polyaspartate, and a modified amino-pyrimidine solution.

[0007] In the aforementioned amino-pyrimidine modified polyaspartate polyurea coating, by weight, it comprises 10 parts of polyether polyol prepolymer, 5.08 parts of polyaspartate, and 0.16 part of modified amino-pyrimidine solution.

[0008] In the aforementioned amino-pyrimidine modified polyaspartate polyurea coating, the modified amino-pyrimidine solution comprises a silane coupling agent, 2,4,6-triaminopyrimidine, and a solvent, where the mass ratio of the silane coupling agent, 2,4,6-triaminopyrimidine, and the solvent is (5 - 6):1:(3.6 - 7).

[0009] In the aforementioned amino-pyrimidine modified polyaspartate polyurea coating, the solvent uses a strongly polar solvent, including any one of dimethyl sulfoxide and N,N-dimethylformamide; the silane coupling agent uses γ-glycidoxypropyltrimethoxysilane.

[0010] In the aforementioned amino-pyrimidine modified polyaspartate polyurea coating, the polyether polyol prepolymer comprises polytetrahydrofuran diol, polypropylene glycol, isophorone diisocyanate, and a catalyst, where the mass ratio of polytetrahydrofuran diol to polypropylene glycol is 2:3, the mass of the catalyst is 0.05 - 0.15% of the total mass of polytetrahydrofuran diol and polypropylene glycol, and the mass of isophorone diisocyanate is 45 - 50% of the total mass of polytetrahydrofuran diol and polypropylene glycol.

[0011] In the aforementioned amino-pyrimidine modified polyaspartate polyurea coating, the catalyst uses one or at least two of dibutyltin dilaurate, triethylamine, cobalt naphthenate, and N-ethylmorpholine, and the mass of the catalyst is 0.05 - 0.15% of the total mass of polytetrahydrofuran diol and polypropylene glycol.

[0012] The preparation method of the above-mentioned amino-pyrimidine modified polyaspartate polyurea coating comprises the following steps:

[0013] S1. Prepare modified pyrimidine: Dissolve 2,4,6-triaminopyrimidine in a solvent, add a silane coupling agent, the reaction temperature is 35 - 45°C, the reaction time is 7.5 - 8.5 h, to obtain a modified amino-pyrimidine solution;

[0014] S2. Prepare polyether polyol prepolymer:

[0015] a. Mix polytetrahydrofuran diol and polypropylene glycol, add a catalyst, heat up to 100 - 110°C, then vacuum dehydrate for 0.8 - 1.2 h, after dehydration is completed, cool down to room temperature to obtain Product A;

[0016] b. Add isophorone diisocyanate to Product A and keep the temperature not exceeding 50 °C to obtain Product B;

[0017] c. Heat Product B to 75 - 85 °C and react for 2 - 3 h to obtain a polyether polyol prepolymer;

[0018] S3. Prepare a polyaspartate polyurea modified coating:

[0019] After taking the polyether polyol prepolymer, polyaspartate and the modified aminopyrimidine solution for curing reaction, a finished product is obtained.

[0020] In the foregoing preparation method, the solvent in step S1 uses a strongly polar solvent, including any one of dimethyl sulfoxide and N,N - dimethylformamide; the silane coupling agent uses γ - glycidoxypropyltrimethoxysilane, and the mass ratio of γ - glycidoxypropyltrimethoxysilane, 2,4,6 - triaminopyrimidine and dimethyl sulfoxide is (5 - 6):1:(3.6 - 7).

[0021] In the foregoing preparation method, in step S3, before curing, first stir at a stirring speed of 1800 - 2200 r / min for 1 - 3 min; then defoam at a speed of 1800 - 2200 r / min for 1 - 2 min. After mixing evenly, defoam at a temperature of 35 - 45 °C and cure at a temperature of 75 - 85 °C.

[0022] This solution also includes the application of the aminopyrimidine - modified polyaspartate polyurea coating on a marine antifouling coating.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention uses polyaspartate polyurea as the matrix resin, uses 2,4,6 - triaminopyrimidine as the antifouling active substance, and uses an amino - epoxy ring - opening reaction with a silane coupling agent to prepare a coupling agent - modified pyrimidine, and grafts the modified pyrimidine onto the polyurea resin matrix to obtain a pyrimidine - modified polyaspartate polyurea coating.

[0025] The polyaspartate polyurea among them overcomes the disadvantages of the traditional polyurea with too fast reaction speed and difficult to control, and also overcomes the defects of the traditional polyurethane system such as inability to cure at low temperature, requiring baking equipment assistance, and being sensitive to humidity. It has a controllable gel time and curing, the film thickness of the coating can be adjusted, has good mechanical properties, has high impact resistance, wear resistance, good flexibility, and ultraviolet resistance.

[0026] Among them, the coupling agent-modified pyrimidine has anti-fouling potential, and contains three primary amino groups in its structure, making it easy to be incorporated into the polyurea resin system and obtaining secondary amine-based substances through modification. This can not only ensure the progress of the next reaction, but also slow down the reaction rate, facilitate the control of the reaction process, improve the reaction stability and product quality. The trifunctional substance among them can also provide high crosslinking for the finished coating, enhance its mechanical properties, and ensure wear resistance.

[0027] Finally, for the pyrimidine-modified polyaspartate polyurea coating prepared, through the research on surface morphology, heat resistance, mechanical properties, wear resistance, and anti-fouling properties, it is found that its surface roughness and hardness increase, the structure is more stable, it is not easily degraded, has strong adhesion to the substrate, has good strength, toughness and impact resistance, is anti-fouling, wear-resistant and easy to clean, is not easily damaged, can better adapt to the marine environment, and will not cause impact on the environment. Brief Description of the Drawings

[0028] Figure 1 is the synthesis schematic diagram of the amino-pyrimidine modified polyaspartate polyurea coating in the present invention;

[0029] Figure 2 is the SEM image of the coating;

[0030] Figure 3 is the Shore hardness test result diagram of the coating;

[0031] Figure 4 is the adhesion result diagram of the coating to the substrate;

[0032] Figure 5 is the wear amount diagram of the coating;

[0033] Figure 6 is the surface silicon attachment situation diagram of the coating after being soaked in Navicula sp. liquid;

[0034] Figure 7 is the attachment situation diagram of the coating soaked in the liquid of Chlorococcum minutum for different days;

[0035] Figure 8 is the inhibition attachment rate diagram of the coating to diatoms;

[0036] Figure 9 is the surface diatom attachment situation diagram of the coating after being washed by high-pressure water flow; Detailed Embodiments

[0037] The following further illustrates the present invention in conjunction with embodiments, but it is not used as the basis for limiting the present invention.

[0038] Example 1:

[0039] The aminopyrimidine modified polyaspartic acid ester polyurea coating comprises, by weight, 10 parts of polyether polyol prepolymer, 5.08 parts of polyaspartic acid ester and 0.16 parts of modified aminopyrimidine solution, which is recorded as AMPU2.5.

[0040] The molar number of excess NCO in the polyether polyol prepolymer: (the molar number of the secondary amino group of the polyaspartic acid ester + the secondary amino group of the modified aminopyrimidine) is 1.05.

[0041] The modified aminopyrimidine solution comprises γ-glycidyloxypropyltrimethoxysilane, 2,4,6-triaminopyrimidine and dimethyl sulfoxide, wherein the mass ratio of γ-glycidyloxypropyltrimethoxysilane, 2,4,6-triaminopyrimidine and dimethyl sulfoxide is 5.67:1:4.

[0042] The polyether polyol prepolymer comprises polytetrahydrofuran diol, polypropylene glycol, isophorone diisocyanate and dibutyltin dilaurate, wherein the mass ratio of polytetrahydrofuran diol to polypropylene glycol is 2:3, the mass of dibutyltin dilaurate is 0.1% of the total mass of polytetrahydrofuran diol and polypropylene glycol, and the mass of isophorone diisocyanate is 48% of the total mass of polytetrahydrofuran diol and polypropylene glycol.

[0043] The preparation method of aminopyrimidine modified polyaspartic acid ester polyurea coating is as follows (unless otherwise specified, "parts" in the following embodiments are all parts by weight):

[0044] S1. Preparation of modified pyrimidine: Figure 1 As shown in (a), 2.5 parts of 2,4,6-triaminopyrimidine are dissolved in dimethyl sulfoxide (DMSO), the solution is placed in a magnetic stirrer with a thermometer and a condensation device, 14.18 parts of γ-glycidyloxypropyltrimethoxysilane (KH560) are slowly added dropwise to the solution, the reaction temperature is 40°C, the reaction time is 8h, and a dimethyl sulfoxide solution of modified aminopyrimidine PD-560 is obtained;

[0045] S2. Preparation of polyether polyol prepolymer:

[0046] like Figure 1 (b) As shown in a, 40 parts of polytetrahydrofuran diol (PTMG2000) and 60 parts of polypropylene glycol (PPG3000) and 0.1 parts of dibutyltin dilaurate as a catalyst were stirred and mixed, the temperature was raised to 105° C., and then vacuum dehydrated for 1 h using a vacuum pump. After the dehydration was completed, the heating was stopped and the temperature was cooled to room temperature to obtain product A;

[0047] b. Slowly add 48 parts of isophorone diisocyanate (IPDI) to product A, while keeping the temperature not exceeding 50°C, to obtain product B;

[0048] c. Heat B product to 80 °C and react for 2.5 h to obtain a polyether polyol prepolymer. The mass percentage of NCO in the final system shall be based on the titration test results;

[0049] S3. Prepare a polyaspartate polyurea modified coating:

[0050] As Figure 1 (c) shows, take 10 parts of the polyether polyol prepolymer, and mix it with 5.08 parts of polyaspartate (NH1220) and 0.16 part of a dimethyl sulfoxide (DMSO) solution of modified aminopyrimidine pd-560 according to the R(NCO / NH) value = 1.05. Put it into a rotating and revolving stirrer, stir at a stirring speed of 2000 r / min for 2 min, and then defoam at a speed of 2000 r / min for 1.5 min. After mixing, coat the mixture on the required substrate or pour it into a polytetrafluoroethylene mold, and place it in a vacuum oven for defoaming. The oven temperature for defoaming is set at 40 °C. After defoaming, raise the temperature to 80 °C to remove the volatile components in the coating and cure it to obtain the finished product.

[0051] Example 2:

[0052] Refer to the preparation method of Example 1 to prepare Example 2. The difference between Example 2 and Example 1 is that the addition amount of the polyether polyol prepolymer is 10 parts, the addition amount of polyaspartate is 4.95 parts, and the addition amount of the dimethyl sulfoxide solution of modified aminopyrimidine pd-560 is 0.32 part. The obtained coating is denoted as AMPU5.

[0053] Example 3:

[0054] Refer to the preparation method of Example 1 to prepare Example 3. The difference between Example 3 and Example 1 is that the addition amount of the polyether polyol prepolymer is 10 parts, the addition amount of polyaspartate is 4.69 parts, and the addition amount of the dimethyl sulfoxide solution of modified aminopyrimidine pd-560 is 0.64 part. The obtained coating is denoted as AMPU10.

[0055] Example 4:

[0056] Refer to the preparation method of Example 1 to prepare Example 4. The difference between Example 4 and Example 1 is that the addition amount of the polyether polyol prepolymer is 10 parts, the addition amount of polyaspartate is 4.43 parts, and the addition amount of the dimethyl sulfoxide solution of modified aminopyrimidine pd-560 is 0.96 part. The obtained coating is denoted as AMPU15.

[0057] Comparative example:

[0058] Referring to the preparation method of Example 1, a comparative example was prepared. The difference between the comparative example and Example 1 was as follows: the addition amount of the polyether polyol prepolymer was 10 parts, the addition amount of the polyaspartate was 5.21 parts, and the dimethyl sulfoxide solution of the modified aminopyrimidine pd-560 was not added. The obtained coating was denoted as AMPU0.

[0059] Performance tests were carried out on the finished products of the comparative example and Examples 1-4:

[0060] (1) Surface morphology observation:

[0061] The surface morphology of the coatings of the comparative example and Examples 1-4 was observed by a scanning electron microscope. The results are as Figure 2 shown. It can be seen from the SEM pictures that the surface of the unmodified coating is smooth and flat, while the coatings of the examples of the present invention have increased roughness, indicating an increase in the adhesion to the substrate.

[0062] (2) Thermal stability test: The TG test of the coating was carried out using a thermogravimetric analyzer. During the test, the sample was first made into small granular form, 5-10 mg was weighed and placed in a ceramic crucible, and the heating test was carried out under the protection of high-purity nitrogen. During the test, the nitrogen flow rate was 50 mL / min, the temperature range was 30-700 °C, and the heating rate was 10 °C / min. The thermal weight loss data results of the coating are shown in Table 1.

[0063] Table 1 Thermal gravimetric analysis data table of the coating

[0064] Sample Name <![CDATA[T d5 ( ℃ )]]> <![CDATA[T max ( ℃ )]]> Residual Carbon Content (%) Comparative Example 286.53 431.60 1.483 Example 1 266.23 432.25 2.570 Example 2 284.69 432.25 4.680 Example 3 320.29 436.52 4.385 Example 4 265.14 434.73 5.123

[0065] It can be seen from Table 1 that the decomposition temperature of the examples is higher than that of the comparative example, and the decomposition temperature of Example 3 is the highest, indicating that the coating structure of the present invention is relatively stable and not easily degraded.

[0066] (3) Shore hardness test: The hardness of the coating was measured using a Shore hardness tester. The specific results are as Figure 3 shown. The hardness of Examples 1-4 is greater than that of the comparative example. As the addition amount of pd-560 increases, the number of crosslinking points in the coating increases, the crosslinking density increases, the rigid structure increases, and the hardness of the coating increases.

[0067] (6) Adhesion test: The adhesion of the coating to Q235 steel was measured by the pull-out method. The results are as Figure 4As shown. The adhesion of the comparative example is 9.42MPa, and the adhesion of Example 4 is 15.15MPa. The adhesion of Examples 1-4 is greater than that of the comparative example, and as the amount of PD-560 added increases, the adhesion of the coating gradually increases. This is precisely the use of the siloxane structure of the silane coupling agent, which has a small contact angle with the metal surface, is easier to unfold on the metal surface, and reacts with the moisture on the metal surface to generate silicon hydroxyl groups, increasing the adhesion to the substrate; at the same time, the coating generates a large number of hydroxyl groups, and the increase in the hydroxyl content increases the number of sites in the coating that can form hydrogen bonds with the substrate. When affected by external forces, the formation of hydrogen bonds in the coating will absorb part of the energy, which requires greater stress to separate the coating from the substrate, so that the adhesion of the coating is improved to a certain extent. Under normal circumstances, the adhesion of the coating to the substrate is greater than 3.0MPa, which can meet practical applications. Therefore, the test results show that the adhesion of the coating of the present invention to the substrate is sufficient to be suitable for marine environments and meet practical application requirements.

[0068] (7) Strength and toughness test: The coating was subjected to a tensile test using a universal tensile testing machine to test the ultimate tensile strength and elongation at break of the coating. The tensile performance data of the coating were obtained. The results are shown in Table 2.

[0069] Table 2 Tensile properties of coatings

[0070] Sample Name Tensile Strength (MPa) Elongation at Break (%) Comparative Example 6.31±0.43 2410 Example 1 9.19±0.37 1745 Example 2 5.14±0.50 1874 Example 3 3.98±0.62 2003 Example 4 1.60±0.27 931

[0071] It can be seen from Table 2 that the polyurea coating prepared in the present invention has good strength and toughness. Among them, the tensile strength of Example 1 is the highest, reaching 9.19 MPa.

[0072] (8) Impact resistance test: The impact resistance of the coating was tested according to the standard GB / T1732-2020. The coatings of Examples 1-4 were evenly coated on the treated tinplate sheets. After the coatings were cured, the coatings were impacted by a paint film impactor. After completion, the samples were taken out and the surface conditions of the samples were observed. The experimental results are shown in Table 3. As shown in Table 3, after the impact test, it was shown that Examples 1-4 all had good impact resistance, and the impact strength reached 50 cm. The internal structure of the coating had the ability to resist stress, and when subjected to rapid deformation, it could resist the influence of external stress through elastic deformation, so that the coating surface would not be damaged or fall off.

[0073] Table 3 Impact resistance test results of coating

[0074] Sample Name Thickness (μm) Impact Distance (cm) Surface Condition Example 1 180 50 Without Any Cracks or Damage Example 2 206 50 Without Any Cracks or Damage Example 3 172 50 Without Any Cracks or Damage Example 4 196 50 Without Any Cracks or Damage

[0075] (9) Wear resistance test: The wear resistance of the coating was tested in accordance with the standard GB / T 1768, and the instrument used was a Taber Type Tester abrasion tester. During the test, the rotation speed was set at 60 r / min, the number of rotations was 500 r, and the load was 500 g. Before and after the test, the mass of the sample was weighed using an analytical balance, and the wear amount was expressed as the mass difference of the sample before and after wear (accurate to 0.1 mg). Each sample was tested 3 times, and the final result was based on the average value. The test results are as Figure 7 shown.

[0076] As Figure 5 can be seen, the wear amount of the comparative example at 500 r was 0.0815 g. The wear amounts of Example 1 and Example 2 were lower. Among them, the wear amount of Example 2 was 0.0481 g, showing excellent wear resistance.

[0077] (10) Anti-fouling performance test:

[0078] Diatoms were used as a fouling organism model for the attachment experiment, and a blank glass slide was used as a blank sample to characterize the anti-fouling performance of the coating. Among them, the diatoms selected were Navicula and Closterium. The coating was immersed in the algal solution, and the diatom attachment on the surface of the coating was observed. By comparing the attachment area on the surface of the coating, the diatom inhibition rate of the coating was calculated to study the anti-fouling ability of the coating.

[0079] Static adhesion test of seaweed: The coating to be tested was cleaned, dried and sterilized under an ultraviolet lamp for 30 min. All the instruments used in the experiment were sterilized using a pressure cooker before use. The coating and 50 mL of algal solution were placed in a conical flask, sealed with a sealing film and placed in a light incubator. The light and temperature were the same as the conditions for culturing diatoms. After the experiment, the coating was taken out, washed with deionized water to remove the diatoms floating on the surface, and then the diatom attachment on the surface of the coating was observed using a fluorescence microscope. Different three positions of each coating were randomly selected for photographing and recording, and the attachment area of the diatoms was calculated. The result was the average value of three experiments.

[0080] The static attachment situation of Navicula solution is as Figure 6 shown. It can be seen that a large number of diatoms adhered to the blank glass slide after being immersed in the Navicula solution, and a large number of Navicula also appeared on the surface of the coating of the comparative example, and the number was not much different from that on the glass slide. This indicates that the unmodified polyaspartate ester urea coating does not have the ability to resist diatom attachment. However, the number of diatoms on the surface of the coatings of Example 1 - Example 4 decreased significantly, which indicates that the coating of the present invention has certain anti-fouling activity and inhibits the attachment of diatoms. Among them, the anti-diatom attachment performance of Example 1 was the best, and the number of diatoms decreased by 93.6% compared with the glass slide. As the content of pd-560 increased, although the number of diatoms on the surface of the coating showed an increasing trend, the number was still less than that of the comparative example. Therefore, the product of the present invention has the ability to resist the attachment of Navicula solution.

[0081] Furthermore, the blank group and the coating group in the Closterium lunula solution with different soaking days were observed. The attachment of Closterium lunula on the surfaces of the blank group and the coating group at different days is as Figure 7 shown.

[0082] With the increase of soaking time, the number of diatoms on the blank group and the comparative example gradually increased, and the surfaces of the blank group and the comparative example were basically covered by diatoms after 7 days of co-culture; while the number of diatoms on Examples 1-4 was significantly reduced, having good anti-diatom adhesion ability and improving the anti-fouling performance of the coating. Among them, the number of diatoms on the surface of Example 1 was the least, and it was reduced by 90.25% compared with the surface of the blank group at 7 days. The inhibition adhesion rate of the coating to diatoms is as Figure 8 shown, indicating that the coating of the present invention has a high inhibition adhesion rate to Amphora and Closterium lunula.

[0083] Anti-fouling performance retention test after dynamic cleaning: The coatings of Examples 1-4 were placed under a water flow of 50 L / min for 30 min, and the diatom adhesion test was carried out on the coatings after flushing, and the attachment of diatoms on the coating surface was observed. The observation results are as Figure 9 shown. From Figure 9 it can be seen that the coating of the present invention still has anti-fouling performance after being impacted by water flow. Among them, the number of diatoms attached to the surface of Example 1 is the least, indicating that the coating of the present invention still maintains the ability to inhibit diatom attachment after cleaning, and its mechanical properties ensure that the coating will not be damaged after flushing.

Claims

1. An amino-pyrimidine modified polyaspartate polyurea coating, characterized in that: It includes a polyether polyol prepolymer, a polyaspartate ester, and a modified aminopyrimidine solution. The molar ratio of the excess NCO in the polyether polyol prepolymer to the sum of the secondary amino groups of the polyaspartate ester and the modified aminopyrimidine is 1.

05. The modified aminopyrimidine solution is prepared by dissolving 2,4,6-triaminopyrimidine in a solvent and adding a silane coupling agent. The silane coupling agent is γ-glycidoxypropyltrimethoxysilane. The reaction temperature is 35 - 45 °C, and the reaction time is 7.5 - 8.5 h. The polyether polyol prepolymer includes polytetrahydrofuran diol, polypropylene glycol, isophorone diisocyanate, and a catalyst. The mass ratio of polytetrahydrofuran diol to polypropylene glycol is 2:3, and the mass of isophorone diisocyanate is 45 - 50% of the total mass of polytetrahydrofuran diol and polypropylene glycol.

2. The amino-pyrimidine modified polyaspartate polyurea coating according to claim 1, characterized in that: By weight, it includes 10 parts of polyether polyol prepolymer, 5.08 parts of polyaspartate ester, and 0.16 part of modified aminopyrimidine solution.

3. The amino-pyrimidine modified polyaspartic ester polyurea coating according to claim 1, wherein: The modified aminopyrimidine solution includes a silane coupling agent, 2,4,6-triaminopyrimidine, and a solvent. The mass ratio of the silane coupling agent, 2,4,6-triaminopyrimidine, and the solvent is (5 - 6):1:(3.6 - 7).

4. The amino-pyrimidine modified polyaspartate polyurea coating according to claim 3, wherein: The solvent is a strongly polar solvent, including any one of dimethyl sulfoxide and N,N-dimethylformamide. The silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

5. The amino-pyrimidine modified polyaspartate polyurea coating according to claim 1, characterized in that: The catalyst is one or at least two of dibutyltin dilaurate, triethylamine, cobalt naphthenate, and N-ethylmorpholine. The mass of the catalyst is 0.05 - 0.15% of the total mass of polytetrahydrofuran diol and polypropylene glycol.

6. The preparation method of the amino-pyrimidine modified polyaspartic ester polyurea coating according to any one of claims 1-5, characterized in that: It includes the following steps: S1. Prepare the modified pyrimidine: Dissolve 2,4,6-triaminopyrimidine in a solvent and add a silane coupling agent. The reaction temperature is 35 - 45 °C, and the reaction time is 7.5 - 8.5 h to obtain the modified aminopyrimidine solution. S2. Prepare the polyether polyol prepolymer: a. Mix polytetrahydrofuran diol and polypropylene glycol, add a catalyst, heat up to 100 - 110 °C, then vacuum dehydrate for 0.8 - 1.2 h. After dehydration is completed, cool down to room temperature to obtain Product A. b. Add isophorone diisocyanate to Product A and keep the temperature not exceeding 50 °C to obtain Product B. c. Heat Product B to 75 - 85 °C and react for 2 - 3 h to obtain the polyether polyol prepolymer. S3. Prepare the polyaspartate ester polyurea modified coating: Take the polyether polyol prepolymer, polyaspartate ester, and modified aminopyrimidine solution and carry out a curing reaction to obtain the finished product.

7. The preparation method according to claim 6, characterized in that: The solvent in step S1 is a strongly polar solvent, including any one of dimethyl sulfoxide and N,N-dimethylformamide. The silane coupling agent is γ-glycidoxypropyltrimethoxysilane. The mass ratio of γ-glycidoxypropyltrimethoxysilane, 2,4,6-triaminopyrimidine, and dimethyl sulfoxide is (5 - 6):1:(3.6 - 7).

8. The preparation method according to claim 6, characterized in that: In step S3, prior to curing, stirring is carried out first, with a stirring speed of 1800 - 2200 r / min and a stirring time of 1 - 3 min; then degassing is carried out at a speed of 1800 - 2200 r / min for 1 - 2 min. After being uniformly mixed, degassing is carried out at a temperature of 35 - 45 °C, and curing is carried out at a temperature of 75 - 85 °C.

9. Application of the aminopyrimidine-modified polyaspartate polyurea coating according to any one of claims 1 - 5 in a marine antifouling coating.

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