Anticorrosive paint for ships and method for producing the same

Abstract

This invention belongs to the field of anti-corrosion coating technology, specifically relating to a marine anti-corrosion coating and its preparation method. The marine anti-corrosion coating comprises a first component and a second component. The first component consists of the following raw materials in parts by weight: 50 parts modified epoxy resin; 12-17 parts nano titanium dioxide; 0.2-1.5 parts wetting and dispersing agent; 1.0-3.0 parts adhesion promoter; 0.5-1.0 parts defoamer; 0.5-1.0 parts leveling agent; and 70-80 parts zinc powder. The second component consists of the following raw materials in parts by weight: 30-40 parts curing agent; and 3-6 parts curing accelerator. The anti-corrosion coating prepared by this invention can simultaneously achieve salt spray resistance, high adhesion, and impact resistance.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion coating technology, specifically relating to an anti-corrosion coating for ships and its preparation method. Background Technology

[0002] As core equipment in maritime transportation, ships operate for extended periods in extreme marine environments characterized by high salinity, high humidity, and strong waves. Their hulls and decks are susceptible to seawater corrosion, which not only shortens their lifespan but also increases maintenance costs and impacts navigational safety. Currently, significant progress has been made in the research and development of marine anti-corrosion coatings, with various modified anti-corrosion coatings emerging. Among these, epoxy resin, due to its excellent adhesion, chemical resistance, and mechanical strength, has become one of the mainstream base resins for marine anti-corrosion coatings.

[0003] With the rapid development of the shipbuilding industry, the navigation range of ships is constantly expanding, from near-shore navigation to open sea and deep sea, which places higher demands on the salt spray resistance of anti-corrosion coatings. However, existing anti-corrosion coatings for ships still have many shortcomings and cannot meet the current high-performance requirements of ships. Specifically: First, the inorganic fillers in the formulations of coatings currently on the market are prone to uneven dispersion in the epoxy resin matrix, resulting in the formation of micropores inside the coating. Seawater and chloride ions can easily penetrate to the substrate surface through the pores, accelerating substrate corrosion and failing to achieve long-term corrosion protection, thus limiting the improvement of salt spray resistance. Second, epoxy resin itself is relatively brittle, and the impact resistance of the coating is not ideal. Under the mechanical action of wave impact and ship navigation vibration, the coating is prone to cracking and peeling. On the other hand, the interfacial bonding force between the filler and the epoxy resin matrix is ​​weak, resulting in insufficient adhesion between the coating and the ship substrate (such as steel). Under the combined effect of salt spray corrosion and mechanical impact, the coating is easily peeled off from the substrate surface, losing its anti-corrosion function.

[0004] Currently, existing marine anti-corrosion coatings generally suffer from performance imbalances: most coatings excessively increase the amount of fillers or anti-corrosion components to improve salt spray resistance, resulting in increased coating brittleness, decreased adhesion, and significantly reduced impact resistance, making the coating prone to cracking and peeling, thus shortening the anti-corrosion life; a few coatings focus on improving adhesion and impact resistance but neglect the optimization of salt spray resistance, making them unable to resist long-term marine salt spray erosion and failing to meet the usage requirements of offshore vessels and deep-sea equipment.

[0005] Therefore, in order to address the problems of insufficient salt spray resistance and difficulty in achieving a balance between adhesion and impact resistance in existing marine anti-corrosion coatings, it is of great practical significance and industrial application value to develop a marine anti-corrosion coating that can improve salt spray resistance while also ensuring high adhesion and excellent impact resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a marine anti-corrosion coating and its preparation method, which can simultaneously achieve salt spray resistance, adhesion and impact resistance.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A marine anti-corrosion coating comprises a first component and a second component. The first component consists of the following raw materials in parts by weight: 50 parts modified epoxy resin; 12-17 parts nano titanium dioxide; 0.2-1.5 parts wetting and dispersing agent; 1.0-3.0 parts adhesion promoter; 0.5-1.0 parts defoamer; 0.5-1.0 parts leveling agent; and 70-80 parts zinc powder. The second component consists of the following raw materials in parts by weight: 30-40 parts curing agent; and 3-6 parts curing accelerator.

[0009] Preferably, the preparation method of the modified epoxy resin includes the following steps: by mass parts, epoxy resin and aliphatic / amino functional polyurea resin are mixed, stirred evenly, heated to 70-75°C, titanate n-butyl ester is added, the reaction is continued at the temperature for 7-8 hours, and cooled to room temperature to obtain modified epoxy resin.

[0010] Preferably, the aliphatic / amino-functionalized polyurea resin has an amine equivalent of 290-295 g / mol and a density of 1.05-1.08 g / cm³. 3 The viscosity at 25℃ is 900-2000 mPa·s.

[0011] Preferably, the epoxy equivalent of the epoxy resin is 184-195 g / mol.

[0012] Preferably, the molar ratio of epoxy groups to amino groups in epoxy resin and aliphatic / amino functional polyurea resin is controlled at 1:(4-6).

[0013] This invention utilizes aliphatic / amino functional polyurea resin to chemically modify epoxy resin E51. By controlling the molar ratio of epoxy groups to amino groups, the amino groups undergo ring-opening addition to the epoxy backbone, forming an epoxy-polyurea block copolymer. The modified epoxy resin combines the high adhesion and chemical resistance of epoxy with the flexibility and impact resistance of polyurea, thus improving the overall performance of coatings.

[0014] Preferably, the wetting and dispersing agent is a polyphosphate solution; the acid value of the wetting and dispersing agent is 52-55 mg KOH / g, and the density at 20°C is 1.02-1.05 g / mL. Preferably, the wetting and dispersing agent is DISPERBYK-110, manufactured by BYK Chemicals, with an acid value of 53 mg KOH / g and a density at 20°C of 1.03 g / mL.

[0015] Preferably, the amount of the wetting and dispersing agent is 2.3-3.2 wt% of the mass of the nano-titanium dioxide.

[0016] Preferably, the particle size of nano-titanium dioxide is 10-30 nm.

[0017] Nano-titanium dioxide has a large specific surface area and is prone to agglomeration. This invention uses the wetting and dispersing agent DISPERBYK-110, whose acidic groups can form a strong anchoring effect with the hydroxyl groups on the surface of nano-TiO2, providing steric hindrance and electrostatic repulsion. Furthermore, optimal dispersion can be achieved by controlling the amount of dispersant used. Insufficient dosage leads to TiO2 agglomeration, resulting in micropores in the coating and reduced salt spray resistance; excessive dosage, while providing good dispersion, weakens the coating's density due to residual dispersant and affects gloss.

[0018] Preferably, the anti-corrosion coating for ships is composed of a first component and a second component in a mass ratio of (5-7):1.

[0019] The preparation method of the anti-corrosion coating for ships includes the following steps: first, mixing modified epoxy resin, nano titanium dioxide, wetting and dispersing agent, adhesion promoter, defoamer, leveling agent and active zinc powder to obtain a first component; mixing curing agent and curing promoter to obtain a second component; and then mixing the first component and the second component to obtain the anti-corrosion coating for ships.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0021] 1. This invention uses a specific type of aliphatic / amino functional polyurea resin to chemically modify epoxy resin E51, while precisely controlling the molar ratio of epoxy groups and amino groups in the epoxy resin and the polyurea resin to prepare a modified epoxy resin. This effectively solves the problems of high brittleness and insufficient adhesion of unmodified epoxy resin, while taking into account the high chemical resistance of epoxy and the flexibility of polyurea, thus improving the overall performance of the coating.

[0022] 2. This invention constructs a synergistic anti-corrosion system of modified epoxy resin, nano titanium dioxide, and special additives, achieving simultaneous improvement in salt spray resistance, adhesion, and impact resistance. The three components, along with zinc powder and adhesion promoters, work synergistically to effectively block the penetration of seawater and chloride ions, enhance the adhesion between the coating and the steel substrate, and improve impact resistance. Ultimately, the coating achieves a high-performance level with adhesion grade 1, impact resistance ≥150cm, and salt spray resistance ≥3000h, solving the problem of performance imbalance in existing technologies. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] All raw materials used in the following embodiments of the present invention are commercially available products:

[0025] Defoamer, brand name THIX-219, manufactured by Yantai Hengxin Chemical Technology Co., Ltd.

[0026] The leveling agent is a fluorocarbon leveling agent, BASF Efka EFKA-3034 from Germany, manufactured by Guangzhou Haoliangda International Trade Co., Ltd.

[0027] Curing agent: Polyetheramine modified curing agent, brand name R-3327, purchased from Ruichi Chemical Co., Ltd.

[0028] Epoxy Resin: Epoxy Resin E51, from Wanqing (Jiangyin) Chemical Technology Co., Ltd., brand: Phoenix E51.

[0029] DISPERBYK-110, Brand: BYK Chemicals.

[0030] Adhesion promoter, model BYK-4511, BYK Chemical.

[0031] Zinc powder, particle size 400-800 mesh.

[0032] Curing accelerator, model DMP-30, Rongsheng New Material Technology (Nantong, Jiangsu) Co., Ltd.

[0033] Example 1

[0034] This embodiment provides a marine anti-corrosion coating, comprising the following components in parts by weight: a first component and a second component in a mass ratio of 6:1. The first component is composed of the following raw materials in parts by weight: 50 parts modified epoxy resin; 15 parts nano titanium dioxide; 0.45 parts wetting and dispersing agent; 2.2 parts adhesion promoter; 0.7 parts defoamer; 0.6 parts leveling agent; and 75 parts zinc powder. The second component is composed of the following raw materials in parts by weight: 33 parts curing agent; and 4 parts curing accelerator.

[0035] The preparation method of the modified epoxy resin includes the following steps: epoxy resin and aliphatic / amino-functionalized polyurea resin are mixed by mass parts, stirred evenly, heated to 75°C, and tetrabutyl titanate is added. The mixture is kept at this temperature for 7 hours, then cooled to room temperature to obtain the modified epoxy resin. The molar ratio of epoxy groups to amino groups in the epoxy resin and aliphatic / amino-functionalized polyurea resin is controlled at 1:4.5. The amount of tetrabutyl titanate used is 1% of the mass of the modified epoxy resin. The aliphatic / amino-functionalized polyurea resin is designated as Gordon® GD-1520, with an amine equivalent of 293 g / mol and a density of 1.07 g / cm³. 3 The viscosity at 25℃ is 900-2000 mPa·s. Shenzhen Gaodun New Materials Co., Ltd. The epoxy resin is epoxy resin E51.

[0036] The wetting and dispersing agent is a polyphosphate solution with an acid value of 53 mg KOH / g and a density of 1.03 g / mL at 20°C. The wetting and dispersing agent is designated as DISPERBYK-110, manufactured by BYK Chemicals, with an acid value of 53 mg KOH / g and a density of 1.03 g / mL at 20°C.

[0037] A method for preparing a marine anti-corrosion coating includes the following steps: first, adding modified epoxy resin to a stirring device and stirring at a low speed of 500 r / min; then adding a wetting and dispersing agent and stirring evenly; subsequently adding nano-titanium dioxide and zinc powder in sequence and dispersing at a high speed of 1500 r / min for 30 min to ensure uniform powder dispersion; finally adding an adhesion promoter, defoamer, and leveling agent and stirring at a low speed of 500 r / min for 15 min to obtain the first component; mixing the curing agent and curing accelerator to obtain the second component; and then mixing the first component and the second component to obtain the marine anti-corrosion coating.

[0038] Example 2

[0039] This embodiment provides a marine anti-corrosion coating, comprising the following components in parts by weight: a first component and a second component in a mass ratio of 6:1. The first component is composed of the following raw materials in parts by weight: 50 parts modified epoxy resin; 17 parts nano titanium dioxide; 0.40 parts wetting and dispersing agent; 1.0 part adhesion promoter; 1.0 part defoamer; 1.0 part leveling agent; and 70 parts zinc powder. The second component is composed of the following raw materials in parts by weight: 30 parts curing agent; and 3 parts curing accelerator.

[0040] The preparation method of the modified epoxy resin includes the following steps: epoxy resin and aliphatic / amino-functionalized polyurea resin are mixed by mass, stirred evenly, heated to 75°C, and tetrabutyl titanate is added. The mixture is kept at this temperature for 7 hours, then cooled to room temperature to obtain the modified epoxy resin. The molar ratio of epoxy groups to amino groups in the epoxy resin and aliphatic / amino-functionalized polyurea resin is controlled at 1:5.0. The amount of tetrabutyl titanate used is 1.2% of the mass of the modified epoxy resin. The aliphatic / amino-functionalized polyurea resin is Gordon® GD-1520, with an amine equivalent of 293 g / mol and a density of 1.07 g / cm³. 3 The viscosity at 25℃ is 900-2000 mPa·s. Shenzhen Gaodun New Materials Co., Ltd. The epoxy resin is epoxy resin E51.

[0041] The wetting and dispersing agent is a polyphosphate solution with an acid value of 53 mg KOH / g and a density of 1.03 g / mL at 20°C. The wetting and dispersing agent is designated as DISPERBYK-110, manufactured by BYK Chemicals, with an acid value of 53 mg KOH / g and a density of 1.03 g / mL at 20°C.

[0042] A method for preparing a marine anti-corrosion coating includes the following steps: first, adding modified epoxy resin to a stirring device and stirring at a low speed of 500 r / min; then adding a wetting and dispersing agent and stirring evenly; subsequently adding nano-titanium dioxide and zinc powder in sequence and dispersing at a high speed of 1500 r / min for 30 min to ensure uniform powder dispersion; finally adding an adhesion promoter, defoamer, and leveling agent and stirring at a low speed of 500 r / min for 15 min to obtain the first component; mixing the curing agent and curing accelerator to obtain the second component; and then mixing the first component and the second component to obtain the marine anti-corrosion coating.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that the aliphatic / amino functionalized polyurea resin is of the Gaodun type. ® GD-1422 has an amine equivalent of 280 g / mol and a density of 1.08 g / cm³. 3 The viscosity at 25℃ is 1000-2000 mPa·s. Shenzhen Gaodun New Materials Co., Ltd. The molar ratio of epoxy groups to amino groups in epoxy resins and aliphatic / amino functional polyurea resins is controlled at 1:4.5.

[0045] Comparative Example 2

[0046] The difference between this comparative example and Example 1 is that 0.45 parts of wetting and dispersing agent were replaced with 0.3 parts of wetting and dispersing agent.

[0047] Comparative Example 3

[0048] The difference between this comparative example and Example 1 is that 0.45 parts of wetting and dispersing agent were replaced with 1.0 part of wetting and dispersing agent.

[0049] Comparative Example 4

[0050] The difference between this comparative example and Example 1 is that the wetting and dispersing agent used is BYK-354, manufactured by BYK Chemical.

[0051] Comparative Example 5

[0052] The difference between this comparative example and Example 1 is that the wetting and dispersing agent used is BYK-192, manufactured by BYK Chemical.

[0053] Comparative Example 6

[0054] The difference between this comparative example and Example 1 is that the modified epoxy resin is replaced with epoxy resin E51.

[0055] Performance testing

[0056] The adhesion of the coating was tested according to GB / T1720-2020 "Cross-cut Test of Paint Film"; the impact resistance of the coating was tested according to GB / T1732-2020 "Determination of Impact Resistance of Paint Film"; and the anti-corrosion performance of the coating was tested according to GB / T1771-2007 "Determination of Resistance to Neutral Salt Spray of Paints and Varnishes". The performance test results are shown in Table 1.

[0057] Table 1 Performance Test Results

[0058] sample Adhesion / Grade Impact resistance / cm Salt spray resistance (5wt% NaCl) Example 1 1 157 The 4000h coating does not bubble or peel off. Example 2 1 152 The 4000h coating does not bubble or peel off. Comparative Example 1 2 141 3300h coating bubbling Comparative Example 2 2 135 3140h coating bubbling Comparative Example 3 1 148 3610h coating bubbling Comparative Example 4 2 130 2920h coating bubbling Comparative Example 5 2 129 2740h coating bubbling Comparative Example 6 2 136 2500h coating bubbling

[0059] As shown in Table 1, this invention, through epoxy-polyurea modification with a specific molar ratio, precise dosage of wetting and dispersing agent, and an optimized synergistic system of zinc powder and additives, has prepared a marine anti-corrosion coating with adhesion grade 1, impact resistance ≥150cm, and salt spray resistance ≥3000h. This overcomes the problem of difficulty in achieving both corrosion resistance and flexibility in the prior art and has significant industrial application value.

[0060] The core difference between Comparative Example 1 and Example 1 is only the type of aliphatic / amino functional polyurea resin. The two differ in physicochemical parameters such as amine equivalent, density, and viscosity, and their reactivity with epoxy resin E51 also differs. This results in a significant decrease in coating performance compared to Example 1. Although the molar ratio of epoxy groups to amino groups remained unchanged, the reactivity and physicochemical parameters of GD-1422 with epoxy resin E51 differed from those of GD-1520. This altered the degree of crosslinking and surface characteristics of the modified epoxy resin produced by the reaction, thereby reducing the compatibility of the modified epoxy resin with other components in the coating system, such as nano-titanium dioxide, active zinc powder, and wetting and dispersing agents. Decreased compatibility leads to poorer dispersion uniformity of powder components, making it easier for micropores and stress concentration points to form inside the coating, resulting in decreased adhesion and reduced impact resistance. Simultaneously, the reduced coating density allows water molecules in a salt spray environment to more easily penetrate to the interface between the coating and the metal substrate, compromising the coating's shielding and protective function, ultimately leading to a decrease in salt spray resistance.

[0061] In Comparative Example 2, the amount of wetting and dispersing agent was insufficient, resulting in a decrease in coating performance. When the amount of dispersing agent was insufficient, it could not provide enough steric hindrance and electrostatic repulsion. TiO2 particles re-aggregated to form micron-sized agglomerates. These agglomerates acted as stress concentration points and pore sources in the coating, reducing the coating density. Poorly dispersed fillers may migrate to the coating-metal interface during the curing process, interfering with the chemical bonding between the adhesion promoter and the substrate. As defects, agglomerates are prone to crack propagation under impact loads, leading to poor impact resistance.

[0062] In Comparative Example 3, the excessive amount of wetting and dispersing agent resulted in an adhesion rating of 1, slightly lower impact resistance, and decreased salt spray resistance. After reaching saturation adsorption, the excess molecules of the dispersant remain free in the coating system. These low-molecular-weight polyphosphate substances do not participate in the cross-linking reaction and remain inside the coating after curing, acting as a plasticizer and slightly reducing the coating's modulus and hardness, leading to a slight decrease in impact resistance. The residual polar dispersant is hydrophilic and may absorb trace amounts of moisture in long-term salt spray environments, reducing the coating's shielding performance and shortening the salt spray resistance time.

[0063] In Comparative Example 4, the wetting and dispersing agent was changed from DISPERBYK-110 to BYK-354. BYK-354 is a polyacrylate wetting agent. It does not contain strong anchoring groups, and its adsorption capacity on the surface of inorganic nano-TiO2 is weak. It cannot effectively reduce interfacial tension, resulting in poor dispersion of TiO2 and the formation of agglomeration and sedimentation.

[0064] In Comparative Example 5, the dispersant was changed to BYK-192. BYK-192 is a modified polyether, which mainly deflocculates the pigment through steric hindrance stabilization. The polyether solvation chain cannot fully extend in the epoxy resin, which reduces its steric hindrance stabilization effect on the pigment particles. BYK-192 is completely unsuitable for the system of this invention.

[0065] Comparative Example 6 replaced the modified epoxy resin with an equal mass of unmodified epoxy resin E51. Unmodified E51, after curing, exhibited high crosslinking density and rigidity, but poor toughness. It was prone to microcracks under wave impact, leading to coating cracking and decreased adhesion. The adhesion of unmodified E51 to steel relied entirely on the chemical bonding and mechanical anchoring of the epoxy groups, and was easily weakened in salt spray environments due to competition from water molecules.

[0066] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A marine anti-corrosion coating, characterized in that, It consists of a first component and a second component. The first component is composed of the following raw materials in parts by weight: 50 parts modified epoxy resin; 12-17 parts nano titanium dioxide; 0.2-1.5 parts wetting and dispersing agent; 1.0-3.0 parts adhesion promoter; 0.5-1.0 parts defoamer; 0.5-1.0 parts leveling agent; and 70-80 parts zinc powder. The second component is composed of the following raw materials in parts by weight: 30-40 parts curing agent; and 3-6 parts curing accelerator.

2. The anti-corrosion coating for ships according to claim 1, characterized in that, The preparation method of the modified epoxy resin includes the following steps: by mass parts, epoxy resin and aliphatic / amino functional polyurea resin are mixed, stirred evenly, heated to 70-75℃, titanate n-butyl ester is added, the reaction is continued at the temperature for 7-8 hours, and cooled to room temperature to obtain modified epoxy resin.

3. The anti-corrosion coating for ships according to claim 2, characterized in that, The amine equivalent of aliphatic / amino-functionalized polyurea resins is 290-295 g / mol, and the density is 1.05-1.08 g / cm³. 3 The viscosity at 25℃ is 900-2000 mPa·s.

4. The anti-corrosion coating for ships according to claim 2, characterized in that, The epoxy equivalent of the epoxy resin is 184-195 g / mol.

5. The anti-corrosion coating for ships according to claim 2, characterized in that, The molar ratio of epoxy groups to amino groups in epoxy resins and aliphatic / amino functional polyurea resins is controlled at 1:(4-6).

6. The anti-corrosion coating for ships according to claim 1, characterized in that, The wetting and dispersing agent is a polyphosphate solution; the acid value of the wetting and dispersing agent is 52-55 mg KOH / g, and the density at 20℃ is 1.02-1.05 g / mL.

7. The anti-corrosion coating for ships according to claim 1, characterized in that, The amount of the wetting and dispersing agent is 2.3-3.2 wt% of the mass of the nano-titanium dioxide.

8. The anti-corrosion coating for ships according to claim 1, characterized in that, The particle size of nano-titanium dioxide is 10-30 nm.

9. The anti-corrosion coating for ships according to claim 1, characterized in that, Marine anti-corrosion coatings are composed of a first component and a second component in a mass ratio of (5-7):

1.

10. A method for preparing a marine anti-corrosion coating according to any one of claims 1-9, characterized in that, Includes the following steps: First, the modified epoxy resin, nano titanium dioxide, wetting and dispersing agent, adhesion promoter, defoamer, leveling agent, and active zinc powder are mixed to obtain the first component; then the curing agent and curing promoter are mixed to obtain the second component. Finally, the first and second components are mixed to obtain the anti-corrosion coating for ships.