Large offshore floating ball protective coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a large offshore floating ball protective coating and a preparation method thereof. The large offshore floating ball protective coating comprises a component A and a component B, wherein the component A comprises modified polyurea resin, an auxiliary agent, a moisture scavenger, a shielding material, a pigment, feldspar powder and a solvent; the component B comprises an isocyanate prepolymer curing agent; the isocyanate prepolymer curing agent is an IPDI (isophorone diisocyanate) prepolymer curing agent. The coating has excellent properties such as high weather resistance, excellent seawater soaking resistance, high elasticity, high strength and the like, a coating formed by the coating can be firmly combined with nonmetal and metal substrates in mechanical property, the mechanical property is matched with a floating ball, the coating still has good elasticity after being used for a long time, the coating can be effectively prevented from being stripped from the substrates, and the service life of the coating is prolonged. And the coating is high in solid content, easy to construct and applicable to protection of offshore facilities such as large offshore floating balls and the like.

Description

Technical Field

[0001] The present application relates to the field of coating technology, and in particular to a large offshore buoy protective coating and a preparation method thereof. Background Art

[0002] Large offshore buoys are widely used in marine scientific research, fishery production, waterway warnings and other fields. They are usually made of PE (polyethylene), EVA foam (ethylene-vinyl acetate copolymer) and other materials. They face serious corrosion problems in the marine environment, especially seawater, ultraviolet rays, wind and wave impacts, etc., which will cause the buoys to gradually degrade, age and break, which not only shortens the service life of the facilities, but also the plastic particles produced will pollute the marine environment.

[0003] At present, only a few offshore buoys are painted with ordinary polyurethane paint or ordinary acrylic paint due to color requirements, but more often they are used directly without protective paint, which causes a large amount of plastic particles produced by aging of the buoy material to cause harm to marine life. Therefore, there is an urgent need to develop a coating that can provide long-term anti-corrosion protection for offshore buoys in high-salinity and high-UV marine environments.

[0004] Compared with conventional coatings, this coating not only needs to have long-term weather resistance and seawater erosion resistance in terms of anti-corrosion properties, but also needs to be able to firmly bond with non-metallic and metal substrates in terms of mechanical properties, and the mechanical properties must be compatible with the float, so that the coating still has good elasticity after long-term use, to prevent the coating from peeling off the substrate. Summary of the invention

[0005] To solve the problems of the prior art mentioned in the above background technology: offshore buoys are often simply coated or used directly without protective coatings, which are prone to aging and damage in harsh marine environments, causing pollution to the environment. The present application provides a protective coating for large offshore buoys, which can be used for the protection of large offshore buoys and other sea surface facilities. Compared with ordinary anti-corrosion coatings, the present application first modifies the polyurea resin with functional materials, and then optimizes the composition of the curing agent and shielding material. After comprehensive adjustment of the formula, the coating formed by the coating can withstand the erosion of wind, sun and seawater immersion in the marine environment, maintain sufficient hardness and strength, and the mechanical properties of the coating are compatible with the elastic material of the buoy, which can effectively prevent the coating from peeling off from the substrate; and it has a high solid content and is easy to construct.

[0006] The large offshore buoy protective coating provided in the present application includes component A and component B, wherein component A includes modified polyurea resin, additives, dewatering agents, shielding materials, pigments, feldspar powder and solvents; component B includes isocyanate prepolymer curing agent; wherein the isocyanate prepolymer curing agent is IPDI prepolymer curing agent; the modified polyurea resin is obtained by modifying polyurea resin with a resin modifier, wherein the resin modifier is a silane containing a glycidyl ether group.

[0007] In some embodiments, the isocyanate prepolymer curing agent is Feiyang Junyan GB926-85 curing agent.

[0008] In some embodiments, the polyurea resin is a secondary amine polyurea resin with high weather resistance, high wear resistance and high strength, and has a solid content of ≥97%, a viscosity of 800-3000 cP (25°C), an amine equivalent of 250-350, and a gel time of ≥15 min with an isocyanate trimer curing agent. Preferably, the polyurea resin has a solid content of ≥98.5%, a viscosity of 900-2500 cP (25°C), an amine equivalent of 270-330, and a gel time of ≥20 min with an isocyanate trimer curing agent.

[0009] In some embodiments, the resin modifier is one of 3-glycidyloxypropyltrimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane, or a mixture of the two in any proportion.

[0010] In some embodiments, the preparation process of the modified polyurea resin is as follows: under a protective atmosphere, the polyurea resin is heated to 45-55°C; a resin modifier is added while stirring, and the resin modifier is added within 5-9 minutes, and then the reaction is continued for 20-30 minutes under a protective atmosphere, and stirring and heating are stopped to obtain the modified polyurea resin; wherein the weight ratio of the polyurea resin to the resin modifier is 100:(1.2-1.4).

[0011] In some embodiments, the preparation process of the modified polyurea resin is as follows: in a nitrogen atmosphere, the polyurea resin is heated to 45-55° C.; a resin modifier is added dropwise while stirring, and the addition of the resin modifier is completed within 5-9 minutes, and then the reaction is continued for 20-30 minutes in a nitrogen atmosphere, and stirring and heating are stopped. The viscosity change value of the obtained resin is detected to be ≤5%, and the gel time is ≥15 minutes, thereby obtaining the modified polyurea resin.

[0012] In some embodiments, the component A includes 50-80 parts of modified polyurea resin, 3-5.5 parts of additives, 3-13 parts of dewatering agents, 15-30 parts of shielding materials, 8-14 parts of pigments, 20-40 parts of feldspar powder and 10-20 parts of solvents, and the component B is 80-120 parts of isocyanate prepolymer curing agent.

[0013] In some embodiments, the dehydrating agent is one or a combination of an oxazolidine dehydrating agent and a molecular sieve dehydrating agent; preferably a 3A molecular sieve dehydrating agent.

[0014] In some embodiments, the shielding material is glass flakes with a mesh size of 200 to 500.

[0015] In some embodiments, the water content of the feldspar powder is <0.1%; the solvent is a polyurethane grade solvent, which is xylene or butyl acetate, and the water content thereof is <0.05%.

[0016] The present application also provides a method for preparing the protective coating for large offshore buoys as described above, wherein the preparation process of component A is as follows: according to the formula, the modified polyurea resin, the additive, the water removing agent, and the solvent are weighed and mixed evenly to obtain a mixed material M, and shielding materials, pigments, and feldspar powder are added to the mixed material M while stirring and dispersed evenly to obtain component A; the preparation process of component B is as follows: the IPDI prepolymer curing agent is filtered and packaged to obtain component B.

[0017] Compared with the existing technology, the large offshore floating ball protective coating provided by this application has the following beneficial effects: The coating provided in the present application has excellent properties such as high weather resistance, excellent resistance to seawater immersion, high elasticity, and high strength. The coating formed by it can not only firmly bond with non-metallic and metal substrates in terms of mechanical properties, but also has mechanical properties that are compatible with the buoy. It still has good elasticity after long-term use, and can effectively prevent the coating from peeling off from the substrate. The coating has a high solid content and is easy to construct, and can be used for the protection of offshore facilities such as large offshore buoys. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] The present application provides an example of the preparation process of a coating dispersant as follows: The preparation process includes the following steps: (1) The preparation process of component A is as follows: According to the formula, the modified polyurea resin, the additive, the water removing agent and the solvent are weighed and mixed evenly to obtain a mixed material M. The shielding material, the pigment and the feldspar powder are added to the mixed material M while stirring, and the mixed material is dispersed evenly at a high speed for 30 to 50 minutes to obtain component A. (2) The preparation process of component B is as follows: The IPDI prepolymer curing agent is filtered and packaged to obtain component B.

[0020] Among them, for the recipe ratio: In parts by weight, the component A includes 50 to 80 parts of modified polyurea resin, 3 to 5.5 parts of additives, 3 to 13 parts of dewatering agents, 15 to 30 parts of shielding materials, 8 to 14 parts of pigments, 20 to 40 parts of feldspar powder and 10 to 20 parts of solvents; the component B is 80 to 120 parts of isocyanate prepolymer curing agent.

[0021] For raw material selection: The preparation process of the modified polyurea resin is as follows: under a protective atmosphere, the polyurea resin is heated to 45-55°C; a resin modifier is added while stirring, and the resin modifier is added within 5-9 minutes, and then the reaction is continued for 20-30 minutes under a protective atmosphere, and stirring and heating are stopped to obtain the modified polyurea resin.

[0022] Wherein, the weight ratio of the polyurea resin to the resin modifier is 100:(1.2-1.4).

[0023] The polyurea resin used is a secondary amine polyurea resin, with a solid content of ≥97%, a viscosity of 800-3000 cP (25°C), an amine equivalent of 250-350, and a gel time of ≥15 min with an isocyanate trimer curing agent. Preferably, the polyurea resin used has a solid content of ≥98.5%, a viscosity of 900-2500 cP (25°C), an amine equivalent of 270-330, and a gel time of ≥20 min with an isocyanate trimer curing agent; the resin modifier used is one or two of 3-glycidyloxypropyltrimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane mixed in any proportion.

[0024] The isocyanate prepolymer curing agent used is IPDI prepolymer curing agent. Preferably, the isocyanate prepolymer curing agent used is Feiyang Junyan GB926-85 curing agent.

[0025] The dehydrating agent used is one of oxazolidine dehydrating agent and molecular sieve dehydrating agent or a combination of the two, preferably 3A molecular sieve dehydrating agent. The shielding material used is glass flakes with a mesh number of 200 to 500 meshes.

[0026] The additives used include but are not limited to defoamers, dispersants, leveling agents, and one or more combinations of anti-settling agents and other common commercial additives, which can be flexibly adjusted according to demand; the pigments used include but are not limited to titanium dioxide, iron red, carbon black, light chrome yellow, phthalocyanine blue B and other common commercial pigments, which can be flexibly adjusted according to customer color requirements. The feldspar powder used is a common commercial filler with a moisture content of <0.1%; the solvent used is a polyurethane grade solvent, which can be selected from xylene or butyl acetate, and its moisture content is <0.05%.

[0027] The present application also provides the following embodiments and comparative examples: The protective coating formulas for large offshore buoys provided in the examples and comparative examples are shown in Table 1-2: Table 1 Example formula (unit, weight parts) Component A raw materials Example 1 Example 2 Example 3 Example 4 Modified polyurea resin 77 66 53 73 Dispersant Euka 710S 0.2 0.4 0.9 0.4 Defoaming agent Euka 272S 1.7 1.2 1.4 1.6 Leveling agent Uka 493U 1 0.2 1.7 1.6 Organic bentonite 2 1.4 1 1.5 3A molecular sieve 11 8 4 5 Xylene 11 14 18 14 Titanium dioxide 0.1 0.2 0.1 0.1 Glass flakes 16 22 28 20 Iron oxide red 10 13 8 11 Feldspar powder 35 26 21 30 total 165 152.4 137.1 158.2 Component B raw materials Example 1 Example 2 Example 3 Example 4 GB926-85 curing agent 116 100 80 108 Conventional trimer curing agent: Covestro N3300 0 0 0 0 Weight ratio of component A to component B 165：116 152.4：100 137.1：80 158.2：108 Table 2 Comparative Example Formula (Unit, parts by weight) Component A raw materials Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Modified polyurea resin 0 66 53 73 73 Unmodified polyurea resin 77 0 0 0 0 Dispersant Euka 710S 0.2 0.4 0.9 0.4 0.4 Defoaming agent Euka 272S 1.7 1.2 1.4 1.6 1.6 Leveling agent Uka 493U 1 0.2 1.7 1.6 1.6 Organic bentonite 2 1.4 1 1.5 1.5 3A molecular sieve 11 8 4 5 5 Xylene 11 14 18 14 14 Titanium dioxide 0.1 0.2 0.1 0.1 0.1 Glass flakes 16 0 28 10 40 Iron oxide red 10 13 8 11 11 Feldspar powder 35 48 21 30 30 total 165 152.4 137.1 148.2 178.2 Component B raw materials Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 GB926-85 curing agent 116 100 0 108 108 Conventional trimer curing agent: Covestro N3300 0 0 18.7 0 0 Weight ratio of component A to component B 165:116 152.4:100 137.1：18.7 148.2：108 178.2：108 The preparation process of the protective coating for large offshore buoys in a specific embodiment includes the following steps: (1) The preparation process of component A is as follows: according to the formula, the modified polyurea resin, the additive, the water scavenger, and the solvent are weighed and mixed evenly to obtain a mixed material M; shielding materials, pigments, and feldspar powder are added to the mixed material M while stirring; and the mixed material is dispersed evenly at high speed for 40 minutes to obtain component A; (2) The preparation process of component B is as follows: the IPDI prepolymer curing agent is filtered and packaged to obtain component B.

[0028] The preparation process of the modified polyurea resin is as follows: in a nitrogen atmosphere, the polyurea resin is heated to 50°C; a resin modifier is added dropwise while stirring, and the addition of the resin modifier is completed within 7 minutes, and then the reaction is continued for 25 minutes in a nitrogen atmosphere, and stirring and heating are stopped. The viscosity change value of the obtained resin is detected to be ≤5% and the gel time is ≥15 minutes, thereby obtaining the modified polyurea resin.

[0029] The calculation method of the amount of the resin modifier (unit %) is: the mass of the resin modifier ÷ the mass of the polyurea resin × 100%. The specific amount of each embodiment is shown in Table 3 below: Table 3 Component A raw materials Example 1 Example 2 Example 3 Example 4 Modifier dosage 1.2% 1.3% 1.4% 1.3% The raw material components in specific embodiments 1-4 are selected as follows: In Example 1, the polyurea resin adopts Feiyang Junyan F420, and the resin modifier is 3-glycidyloxypropyltrimethoxysilane; in Example 2, the polyurea resin adopts Feiyang Junyan F420, and the resin modifier is 3-glycidyloxypropylmethyldiethoxysilane; in Example 3, the polyurea resin adopts Feiyang Junyan F420, and the resin modifier is 3-glycidyloxypropyltrimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane mixed in equal weight proportions; in Example 4, the polyurea resin adopts Feiyang Junyan F420, and the resin modifier is 3-glycidyloxypropyltrimethoxysilane.

[0030] Among them, the polyurea resin Feiyang Junyan F420 selected in Examples 1-4 is a highly weather-resistant, highly wear-resistant, and highly strong secondary amine polyurea resin with a solid content of 97%, a viscosity of 1100 cP, an amine equivalent of 277, and a gel time of 12 minutes with an isocyanate trimer curing agent.

[0031] The mesh number of the glass flakes used in Examples 1-4 is 300 meshes. The feldspar powder used in Examples 1-3 is a common commercial filler with a moisture content of <0.1%. The solvent used in Examples 1-4 is polyurethane-grade solvent xylene with a moisture content of <0.05%.

[0032] The specific differences between the comparative examples and the embodiments are as follows: The difference between Comparative Example 1 and Example 1 is that the unmodified polyurea resin is used to replace the modified polyurea resin in Example 1, that is, the polyurea resin Feiyang Junyan F420 is used to directly replace the modified polyurea resin. The other formulas and preparation processes are the same as those in Example 1.

[0033] The only difference between Comparative Example 2 and Example 2 is that no glass flakes are added when preparing Component A (feldspar powder of equal quality is used to replace the glass flakes in Example 1), and the other formulas and preparation processes are consistent with Example 2.

[0034] The only difference between Comparative Example 3 and Example 3 is that Comparative Example 3 uses a commercially available conventional trimer curing agent N3300 with a relatively small molecular weight, and the other raw material formulas and preparation process are consistent with those of Example 3.

[0035] It should be noted that: this comparative example uses 18.7 parts of Covestro N3300 to replace 80 parts of GB926-85 curing agent in Example 3, because: the amount of component B curing agent depends on the -NCO functional group content per unit mass of the curing agent, and its core principle is to replace the total amount of -NCO functional groups of the curing agent. The -NCO functional group content per unit mass of GB926-85 curing agent is 5.1%, and the -NCO functional group content per unit mass of Covestro N3300 is 21.8%. Therefore, when the -NCO functional group content is replaced, (80 x 5.1%) ≈ (19 x 21.8%).

[0036] The only difference between Comparative Example 4 and Example 4 is that the amount of glass flakes is reduced to 10 parts, and the other formulas and preparation processes are consistent with Example 4.

[0037] The only difference between Comparative Example 5 and Example 4 is that the amount of glass flakes is increased to 40 parts, and the other formulas and preparation processes are consistent with Example 4.

[0038] The large offshore buoy protective coatings prepared in the above examples and comparative examples were subjected to the following performance tests: Component A and component B of the coating were mixed evenly in proportion to form a coating. The protective coating was applied on the roughened surface of the offshore buoy shell and the carbon steel plate sandblasted to Sa2.5 grade. Test specimens such as tensile performance test and salt spray resistance test were prepared. The test results are shown in Table 4-5.

[0039] Table 4 Main performance test data of the embodiment

[0040] Table 5 Main performance test data of comparative examples

[0041] Analysis of the above comparative examples and embodiment data shows that: The coating provided in Examples 1-4 of the present application has excellent mechanical properties, salt spray resistance, and seawater resistance. Its UV aging resistance is ≥4000h without powdering, its adhesion to metal substrates is ≥10MPa, its adhesion to non-metallic substrates (floating ball shells) is ≥17MPa, and its tensile strength can reach 19-21MPa. At the same time, its elongation is 500-650%, its solid content is ≥86%, and its Shore A hardness is ≥90. After 4000h of UV aging, its tensile elongation is still maintained at 240-290%.

[0042] Compared with the examples, comparative example 1 uses unmodified polyurea resin, and its adhesion to metal substrates and seawater immersion resistance are significantly reduced, and its adhesion to non-metallic substrates (floating ball shells) and tensile strength are slightly reduced.

[0043] Compared with the embodiment, in comparative example 2, no glass flakes were added when preparing component A, and its salt spray resistance and seawater resistance were significantly reduced.

[0044] Compared with the embodiment, comparative example 3 uses a commercially available conventional trimer curing agent N3300 with a relatively small molecular weight, and its resistance to ultraviolet aging, salt spray and seawater is significantly reduced.

[0045] Compared with the embodiment, comparative example 4 greatly reduces the amount of glass flakes (its amount is lower than the range specified in the present application), and its salt spray resistance and seawater resistance are significantly reduced, and its shielding property is deteriorated.

[0046] Compared with the embodiment, the comparative example 5 adds excessive glass flakes (the amount exceeds the specified range of this application), and its salt spray resistance and seawater resistance are significantly reduced. The analysis may be that there are too many glass flakes in the paint film, the resin content is relatively reduced, and the glass flakes are difficult to stack and arrange before the coating is cured, which easily causes defects such as capillaries and micropores.

[0047] In summary, the present application first modifies the polyurea resin and matches it with a highly weather-resistant and highly elastic isocyanate prepolymer curing agent to obtain a resin system with good adhesion to both metal and non-metallic substrates, and then comprehensively optimizes the formula. The prepared coating has excellent mechanical properties, salt spray resistance, and seawater resistance, and is resistant to UV aging for ≥4000h without powdering. The paint film after the aging test still has high elasticity; the adhesion to the metal substrate is ≥10MPa, the adhesion to the non-metallic substrate is ≥17MPa, the Shore A hardness is ≥90, the tensile strength can reach 19-21MPa, and the elongation is 500-650%. The mechanical properties of the paint film are compatible with the elastic material of the buoy; the solid content of the coating is ≥86%, which is easy to construct and can provide long-term protection for large offshore buoys.

[0048] Among them, whether the mechanical properties of the coating formed by the coating provided in this application are compatible with the float can be seen mainly through the adhesion and elongation results. The adhesion results show that the coating will not fall off easily, and the elongation results show that it has sufficient elongation. When the float is deformed by external force, the coating can also deform with it. The coating will not fall off easily and the coating can deform with the deformation of the float, indicating that the coating and the float are compatible. If the elongation is not enough, the coating will break during the deformation process, and the two are not compatible.

[0049] In summary, the large offshore buoy protective coating provided by this application has at least the following design concepts and beneficial effects: (1) Improvement of resin system: Large offshore buoys have high elasticity and will deform when subjected to external forces. Therefore, the selected protective coating resin system must have high elasticity in addition to high weather resistance, so that the coating can change with the deformation of the buoy and avoid interlayer peeling due to mismatch of mechanical properties during long-term use. In addition, the buoy is often subjected to wave erosion, cable friction, etc. during use, and needs to have sufficient hardness, strength, and wear resistance. Therefore, polyurea resin is the preferred type of resin system.

[0050] Some floats have a part of metal support structure on their surface. If the polyurea resin system is directly applied to the metal surface, poor interlayer adhesion will occur. When the coating is damaged, the coating will be completely peeled off from the metal substrate surface, and even cause the paint film to be torn off in one piece. Therefore, the polyurea resin needs to be modified to meet the needs of the application site of this application. To solve this demand, this application finally selected silane containing glycidyl ether groups as the resin modifier, and through chemical reaction, the silicon hydroxyl groups are evenly grafted onto the polyurea resin molecular chain, thereby greatly improving the adhesion of the resin to the metal substrate. When the paint film is hit by external forces, it is only damaged in this local area, and other areas can still be firmly attached, rather than falling off in one piece.

[0051] In order to further improve the weather resistance, elasticity and tensile strength of the resin system, this application uses IPDI prepolymer with higher molecular weight as a curing agent. Compared with conventional isocyanate trimer curing agents, prepolymer curing agents have larger molecular weights and can more accurately design molecular chain structures. By introducing elastic groups and weather-resistant groups, the resin after the reaction has better mechanical strength, elasticity and weather resistance.

[0052] (2) Adding a dehydrating agent to the paint can remove the moisture adsorbed during the paint production process and the moisture carried by the powder when it leaves the factory through chemical reaction or physical adsorption lattice fixation, and prevent the paint from deteriorating due to moisture during storage.

[0053] (3) Adding an appropriate amount of glass flakes to the coating will cause the glass flakes to overlap and interlace in the coating, forming a maze effect, which can extend the penetration path of water and ions, thereby improving the coating's resistance to seawater penetration. In addition, the added feldspar powder can increase the hardness and wear resistance of the coating, extending the service life of the coating on the sea surface.

[0054] It should be noted that: "IPDI" is the abbreviation of isophorone diisocyanate.

[0055] The calculation method of the resin viscosity change value is: (the viscosity of the modified polyurea resin obtained by modification - the viscosity of the polyurea resin before modification) ÷ the viscosity of the polyurea resin before modification × 100%.

[0056] In this article, “~” is used to indicate a numerical range, and the range indicated by this expression includes two endpoint values.

[0057] In addition to the actual selections embodied in the above specific embodiments, the above formulation ranges may be used in the specific implementation of the present application, including but not limited to the above embodiment schemes.

[0058] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments of the present application, but are not intended to limit the present application. Those skilled in the art may make adaptive adjustments within the scope of the present application.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A large-scale marine floating ball protective coating, comprising component A and component B, characterized in that: The component A comprises modified polyurea resin, additives, water scavenger, shielding material, pigment, feldspar powder and solvent; The component B includes an isocyanate prepolymer curing agent; The isocyanate prepolymer curing agent is an IPDI prepolymer curing agent; the modified polyurea resin is obtained by modifying a polyurea resin with a resin modifier, wherein the resin modifier is a silane containing a glycidyl ether group.

2. The large offshore floating ball protective coating according to claim 1 is characterized by: The polyurea resin is a secondary amine polyurea resin, has a solid content of ≥97%, a viscosity of 800-3000 cP, an amine equivalent of 250-350, and a gel time of ≥15 min with an isocyanate trimer curing agent.

3. The large offshore floating ball protective coating according to claim 1 is characterized by: The resin modifier is one of 3-glycidyloxypropyltrimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane or a mixture of the two in any proportion.

4. The large offshore floating ball protective coating according to claim 1 is characterized in that: The preparation process of the modified polyurea resin is: In a protective atmosphere, the polyurea resin is heated to 45-55° C.; a resin modifier is added while stirring, and the resin modifier is added within 5-9 minutes, and then the reaction is continued for 20-30 minutes in a protective atmosphere, and stirring and heating are stopped to obtain the modified polyurea resin; Wherein, the weight ratio of the polyurea resin to the resin modifier is 100:(1.2-1.4).

5. The large offshore floating ball protective coating according to claim 4 is characterized in that: The preparation process of the modified polyurea resin is: In a nitrogen atmosphere, the polyurea resin is heated to 45-55° C.; a resin modifier is added dropwise while stirring, and the addition of the resin modifier is completed within 5-9 minutes, and then the reaction is continued for 20-30 minutes in a nitrogen atmosphere, and the stirring and heating are stopped. The viscosity change value of the obtained resin is detected to be ≤5% and the gel time is ≥15 minutes, thereby obtaining the modified polyurea resin.

6. The large offshore floating ball protective coating according to claim 1 is characterized in that: The polyurea resin is a secondary amine polyurea resin, having a solid content of ≥98.5%, a viscosity of 900-2500 cP, an amine equivalent of 270-330, and a gel time of ≥20 min with an isocyanate trimer curing agent; The isocyanate prepolymer curing agent is Feiyang Junyan GB926-85 curing agent.

7. The large offshore floating ball protective coating according to claim 1 is characterized by: In parts by weight, the component A comprises 50 to 80 parts of modified polyurea resin, 3 to 5.5 parts of auxiliary agent, 3 to 13 parts of dewatering agent, 15 to 30 parts of shielding material, 8 to 14 parts of pigment, 20 to 40 parts of feldspar powder and 10 to 20 parts of solvent; The component B is 80 to 120 parts of isocyanate prepolymer curing agent.

8. The large offshore floating ball protective coating according to claim 1 is characterized by: The dehydrating agent is one or a combination of an oxazolidine dehydrating agent and a molecular sieve dehydrating agent; The shielding material is glass flakes with a mesh size of 200 to 500 meshes.

9. The large offshore floating ball protective coating according to claim 1 is characterized by: The water content of the feldspar powder is less than 0.1%; The solvent is a polyurethane grade solvent, which is xylene or butyl acetate, and its water content is less than 0.05%.

10. A method for preparing a large offshore floating ball protective coating as claimed in any one of claims 1 to 9, characterized in that: The preparation process of component A is as follows: According to the formula, the modified polyurea resin, the additive, the water removing agent and the solvent are weighed and mixed evenly to obtain a mixed material M. The shielding material, the pigment and the feldspar powder are added to the mixed material M while stirring and dispersed evenly to obtain component A. The preparation process of component B is: The IPDI prepolymer curing agent is filtered and packaged to obtain component B.

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