Nano titanium-polyurethane modified epoxy resin anticorrosive coating as well as preparation method and application thereof

Abstract

The invention discloses a nano titanium-polyurethane modified epoxy resin anticorrosive coating and a preparation method and application thereof, and the preparation method comprises the following steps: preparation of a polyurethane prepolymer, preparation of polyurethane modified epoxy resin, preparation of a nano titanium functional filler, preparation of a nano titanium-polyurethane modified epoxy resin anticorrosive coating, and preparation of a nano titanium-polyurethane modified epoxy resin anticorrosive coating. Then adding the prepared polyurethane modified epoxy resin, a powder filler, a dispersing agent, a flatting agent and a defoaming agent into a mixed solvent, putting the mixture into a high-speed dispersion machine, and stirring at normal temperature at the rotating speed of 2000-3000rpm to obtain mixed slurry; adding the prepared nano titanium functional filler, and stirring in a high-speed dispersion machine at normal temperature at the rotating speed of 2000-3000rpm to obtain a nano titanium-polyurethane modified epoxy resin coating; adding an amine curing agent into the coating, mixing and stirring, finally coating the surface of a base material with the coating, and drying to obtain a cured coating. The anti-corrosion coating for the ship ballast tank is excellent in comprehensive performance and can provide corrosion-resistant and seawater alternating pressure-resistant protection for a metal base material for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion coatings, and particularly relates to a nano-titanium-polyurethane modified epoxy resin anti-corrosion coating, a preparation method thereof, and an application thereof. Background Art

[0002] As an important compartment of a marine ship, a ballast tank often faces a harsh and complex environment during use. High humidity, high pressure at deep water, and frequent alternating seawater pressure can all cause corrosion and structural loss of equipment, thereby causing property losses and safety hazards. Coating an anti-corrosion coating is an effective protective measure to extend the service life of a ship's ballast tank. Developing long-lasting anti-corrosion coatings for complex and harsh marine environments is an urgent problem to be solved.

[0003] Epoxy resin-based coatings are one of the most widely used coatings in the field of marine anti-corrosion. The epoxy resin molecular structure has polar functional groups such as hydroxyl groups and ether bonds, which have good adhesion to the substrate. At the same time, the benzene ring in the molecular chain provides good rigidity, hardness, and chemical stability for the coating. Coatings prepared by epoxy resin combined with various functional fillers and additives can be used for anti-corrosion protection in different occasions, and at the same time have the characteristics of expandable production and strong construction operability. Today's epoxy resin-based coatings have been widely used in the field of anti-corrosion protection of marine ships and other equipment.

[0004] Problem 1: The epoxy resin coating is brittle after curing

[0005] The epoxy resin coating has good mechanical strength after curing, but poor toughness. Long-term alternating seawater pressure will cause cracks and defects on the surface or inside of the epoxy coating, reducing the protective effect and service life of the coating.

[0006] Problem 2: Various defects will occur inside the epoxy resin coating during the curing process

[0007] Nowadays, in order to save the time cost of construction, anti-corrosion coatings for marine ship equipment with fast curing and surface drying are often favored by people. However, during the curing process of the coating, due to the relatively rapid cross-linking reaction between the resin and the curing agent, the coating has not had time to level and fill before a large amount of solvent volatilizes, resulting in pores. At the same time, the internal stress generated by the rapid cross-linking reaction cannot be effectively released, resulting in tiny cracks inside the coating. Therefore, traditional quick-drying coatings usually have defects such as pores and micro-cracks inside. When in use, seawater rich in various corrosive media can penetrate through the pores inside the coating to the substrate, and at the same time, alternating pressure can cause stress concentration at the micro-cracks, thereby damaging the coating and ultimately leading to the failure of the coating and being unable to provide long-term protection for the metal substrate.

[0008] Problem 3: The preparation cost of nano-functional fillers is relatively high and their dispersibility in the coating is poor

[0009] Nanomaterials have a large specific surface area and small size, and generally have more excellent physical and chemical properties than traditional materials. As functional fillers, they can not only improve the conventional properties of coatings, but also endow coatings with other special functions. However, there are still problems in the application of nano-fillers in anti-corrosion coatings. First, compared with traditional functional fillers, the preparation of nano-functional fillers is limited by factors such as technical processes, with a small production scale and high cost. Second, the surface energy of nanomaterials is high and there are interaction forces, and nanoparticles or lamellae are prone to agglomeration, with poor dispersibility in polyurethane-modified epoxy resins, resulting in various defects inside the coating during the curing process and reducing the service life of the anti-corrosion coating. Therefore, reducing the production cost of nano-functional fillers, expanding the production scale, and solving the dispersibility problem in coatings are also difficult problems that need to be overcome urgently in the current research field of anti-corrosion coatings. Summary of the Invention

[0010] In view of this, aiming at the problems existing in the prior art, the purpose of the present invention is to provide a nano-titanium-polyurethane modified epoxy resin anti-corrosion coating, its preparation method and application, effectively solving problems such as poor toughness and large brittleness after curing of traditional epoxy anti-corrosion coatings, various defects generated inside during rapid curing, and poor dispersibility of functional fillers in the coating.

[0011] The technical solution adopted is as follows:

[0012] A preparation method of a nano-titanium-polyurethane modified epoxy resin anti-corrosion coating of the present invention includes the following steps:

[0013] S1. Mix polyol and hydroxyl-terminated propyl silicone oil and dehydrate under vacuum, add diisocyanate, and react at 60 - 80 °C to obtain a polyurethane prepolymer;

[0014] S2. Take the polyurethane prepolymer prepared in S1 and blend and modify it with epoxy resin at a reaction temperature of 75 - 85 °C to obtain a polyurethane-modified epoxy resin;

[0015] S3. Put titanium powder, the polyurethane prepolymer prepared in S1, and a grinding aid into a high-energy ball mill, and grind them at high speed at room temperature with a rotation speed of 1500 - 2000 rpm to obtain a black paste-like substance, which is the nano-titanium functional filler;

[0016] S4. First, take the polyurethane-modified epoxy resin prepared in S2, powder filler, dispersant, leveling agent, defoaming agent and add them to a mixed solvent, place them in a high-speed disperser and stir at a speed of 2000 - 3000 rpm at room temperature to obtain a mixed slurry; then, add the nano-titanium functional filler prepared in S3, place it in a high-speed disperser and stir at a speed of 2000 - 3000 rpm at room temperature to obtain a nano-titanium-polyurethane modified epoxy resin coating;

[0017] S5. Add an amine curing agent to the coating and mix it thoroughly, and finally coat it on the surface of the substrate and dry it to obtain a cured coating.

[0018] Further, in S1, the polyol is one or more of polyethylene glycol, polypropylene glycol, and polybutylene glycol; and / or, the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and / or, the molecular weight range of the hydroxyl-terminated propyl silicone oil is 2000-2500.

[0019] Further, in S1, in the prepared polyurethane prepolymer, the content of the blocked isocyanate group is 5%-20% of the mass fraction of the polyurethane prepolymer.

[0020] Further, in S2, the epoxy resin model is one or more of E20, E44, E51, and F44.

[0021] Further, in S2, the blending mass ratio of the polyurethane prepolymer to the epoxy resin is 1:(2-10); the mass ratio of the titanium powder to the polyurethane prepolymer is 5:(3-6).

[0022] Further, in S3, the grinding aid is one or more of xylene, n-butanol, and acetone, and / or, the titanium powder is high-purity industrial titanium powder with a purity ≥99.95%.

[0023] Further, in S3, the rotation speed of the high-energy ball mill is 1500-2000 rpm, and the grinding time is 2-6 h.

[0024] Further, in S4, the powder filler is one or more of talc powder, fumed silica, titanium dioxide, and graphene; and / or, the mixed solvent is a mixed solvent of polar and non-polar solvents.

[0025] Further, in S5, coat it on the surface of the substrate, place it in a blast drying oven at 50-100°C and dry it for 4-10 h to obtain a cured coating.

[0026] Further, in S5, the substrate is Q235 carbon steel after surface pretreatment.

[0027] Further, in S5, the thickness of the cured coating is 100±10 μm.

[0028] A nano-titanium-polyurethane modified epoxy resin anticorrosive coating of the present invention is prepared by the preparation method described in any of the above schemes.

[0029] Application of the nano-titanium-polyurethane modified epoxy resin anticorrosive coating described in the above scheme of the present invention in the surface protection of the ballast tank of a marine ship.

[0030] In the above technical solution:

[0031] 1. Before synthesizing the polyurethane prepolymer, the polyol needs to be dehydrated under vacuum to ensure that the hydroxyl groups reacting with the isocyanate groups all come from the polyol.

[0032] 2. When synthesizing the nano-titanium functional filler, the self-rotation speed of the high-energy ball mill is 1500 - 2000 rpm, and the preferred grinding time is 2 - 6 h, ensuring that the grinding balls can fully contact and extrude the titanium powder, polyurethane prepolymer, and grinding aid. The mechanical energy generated breaks and crushes the titanium particles, making their particle size nano-sized, and enabling the polyurethane prepolymer to fully coat the surface of the nano-titanium particles.

[0033] 3. When formulating the coating, it is preferred to use a mixed solvent of polar and non-polar solvents to ensure the uniform mixing of the polyurethane-modified epoxy resin and the functional filler. The polar solvent is, for example, one or more of ethyl acetate, n-butanol, and cyclohexanone, and the non-polar solvent is, for example, one or more of toluene and xylene.

[0034] 4. The coating curing conditions are preferably drying in a forced-air drying oven at 50 - 100 °C for 4 - 10 h. The resin cross-linking curing reaction rate and the solvent evaporation rate inside the coating are moderate, allowing the coating to have sufficient time to level during curing, reducing internal defects after complete curing.

[0035] Features of the present invention:

[0036] Feature 1: Using the polyurethane-modified epoxy resin as the polyurethane-modified epoxy resin of the coating can solve the problem of relatively large brittleness of the traditional epoxy resin coating after curing. In the polyurethane molecular chain segment, there are both "soft segments", which are polyol chain segments with good flexibility, and "hard segments", which are isocyanate chain segments with a certain rigidity. The polyurethane resin polymerized from these two chain segments has good flexibility after curing. By modifying the epoxy resin with a polyurethane prepolymer capped with isocyanate groups, a resin system with excellent mechanical properties can be obtained. The reaction between the isocyanate groups in the polyurethane prepolymer and the hydroxyl groups in the epoxy resin molecular chain forms chemical cross-linking, resulting in a polyurethane-modified epoxy resin. By introducing the polyurethane chain segment, the disadvantage of relatively large brittleness of the epoxy coating after curing can be improved without affecting the barrier performance of the coating, enhancing the flexibility of the polyurethane-modified epoxy resin, and enabling the coating to remain stable under long-term exposure to the alternating pressure of seawater.

[0037] Feature 2: The nano-titanium functional filler prepared by high-energy ball milling method has excellent dispersibility in polyurethane-modified epoxy resin. The raw material titanium powder, polyurethane prepolymer and grinding aid are put into a high-energy ball mill. The balls collide with the raw materials by rolling. During this period, the titanium powder is broken by impact, the particle size is reduced to the nano-scale size, and the surface energy is greatly increased. At the same time, the balls collide with each other to generate a relatively high energy, realizing the coating of the polyurethane prepolymer molecules on the metal particles, and thus obtaining the nano-titanium functional filler. When the filler is fully mixed with the polyurethane-modified epoxy resin, the polyurethane prepolymer molecules coating the titanium particles can effectively reduce the surface energy and interaction of the nanoparticles, hinder the agglomeration between the nano-titanium particles, and improve the dispersibility in the polyurethane-modified epoxy resin. In this way, it not only solves the problem of poor dispersibility of nano-functional fillers in polyurethane-modified epoxy resin, but also slows down the sedimentation rate, ensuring the quality of the coating during long-term storage.

[0038] Feature 3: The addition of the nano-titanium functional filler can effectively reduce the defects generated inside the coating during curing, and improve the long-term corrosion resistance, fatigue resistance to alternating stress and service life of the coating. When the nano-titanium functional filler is uniformly dispersed in the coating, fewer micropores and cracks are generated during the rapid curing process of the coating, thus reducing the channels for the penetration and diffusion of corrosive media after they enter the coating. And because titanium has stable chemical properties and strong corrosion resistance, it can effectively block the corrosive media. At the same time, the nano-titanium function, as a reinforcing phase material of the coating, can be uniformly dispersed in the curing system to effectively enhance the mechanical strength of the coating and improve the tolerance to the alternating pressure of seawater.

[0039] Therefore, the beneficial effects of the present invention are as follows:

[0040] 1. The present invention synthesizes a polyurethane-modified epoxy resin with both excellent mechanical strength and flexibility as the polyurethane-modified epoxy resin of the coating, which can effectively cope with the ocean water pressure and deep-sea alternating pressure, and improve the service life of the coating.

[0041] 2. The present invention uses the high-energy ball milling method to prepare nano-titanium with excellent dispersion performance in the polyurethane-modified epoxy resin as a functional filler, which provides an effective barrier protection for the coating while reducing the internal defects of the coating.

[0042] 3. The present invention utilizes the good mechanical properties of the polyurethane-modified epoxy resin and the synergistic protection effect generated by the good dispersion barrier and mechanical enhancement of the nano-titanium filler to prepare an anti-corrosion coating for ship ballast tanks with excellent comprehensive performance and capable of providing long-term corrosion resistance and protection against seawater alternating pressure for metal substrates.

[0043] 4. The nano-titanium functional filler prepared by the high-energy ball milling method in the present invention has a low cost and great industrialization potential. This nano-titanium functional filler has good compatibility with the polyurethane-modified epoxy matrix resin. After curing, the coating prepared from the nano-composite modified epoxy coating has fewer internal defects and is denser than the traditional composite modified epoxy coating, with strong corrosion resistance. After being soaked in the corrosive liquid for a long time, it can still maintain a high adhesion to the metal substrate. Moreover, due to the uniform distribution of the nano-titanium functional filler in the coating, the coating has good toughness and impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is the infrared spectrogram of polyurethane prepolymer (PU), nano-titanium (PTiN) and raw titanium powder (Ti).

[0045] Figure 2 It is the transmission electron microscope image of the nano-titanium functional filler (PTiN).

[0046] Figure 3 It is the broken line graph of the water absorption rate of the coating for 240 h.

[0047] Figure 4 It is the electrochemical impedance spectroscopy diagram of the coating after being soaked for 360 h.

[0048] Figure 5 It is the coating resistance R fitted from the electrochemical impedance test data of the coating after being soaked for 360 h c Bar graph. DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention.

[0050] Example 1

[0051] A preparation method of a nano-titanium-polyurethane modified epoxy resin anti-corrosion coating in this example includes the following steps:

[0052] Step 1: Synthesis of polyurethane prepolymer PU: Mix 1200 g of polypropylene glycol 3000, 400 g of polybutylene glycol 1000, and 240 g of hydroxypropyl-terminated silicone oil 2000 and dehydrate under vacuum for 1 h. Add 1100 g of 4,4'-diphenylmethane diisocyanate and react at 80 °C for 3 h to obtain the polyurethane prepolymer, and the mass fraction of the blocked isocyanate group in this polyurethane prepolymer is 10%.

[0053] Step 2: Take 20 g of the synthesized polyurethane prepolymer PU in Step 1 and blend and modify it with 200 g of E44 type epoxy resin, and the reaction temperature is 80 °C.

[0054] Step 3: Synthesis of nano-titanium functional filler: Put 500 g of high-purity industrial titanium powder (purity ≥ 99.95%), 600 g of the polyurethane prepolymer prepared in the above experiment, and a grinding aid into a high-efficiency ball mill. The titanium powder, polyurethane prepolymer and grinding aid are ground at high speed for 4 h at room temperature with a rotation speed of 1600 rpm to obtain a black paste-like substance, which is the nano-titanium functional filler (PTiN).

[0055] Step 4: First, take 130 g of polyurethane-modified epoxy resin, 11 g of talc powder, 1.8 g of R972 powder, a dispersant, a leveling agent, and an antifoaming agent with a mass fraction of 0.1% of the polyurethane-modified epoxy resin, add them to a mixed solvent of 30 g of xylene and 10 g of n-butanol, and place them in a high-speed disperser and stir at 3000 rpm at room temperature for 1 h to obtain a mixed slurry, and prepare a polyurethane-modified epoxy composite coating.

[0056] Step 5: Add a curing agent of type T31 with a mass fraction of 20% to the coating and mix and stir evenly. Coat the curing system on the surface of Q235 carbon steel with a size of 60 mm × 30 mm × 3 mm after surface sandblasting treatment, and place it in a blast drying oven at 80 °C for 4 h to obtain a cured coating, and the coating thickness is 100 ± 10 μm.

[0057] Figure 1 Infrared spectra of polyurethane prepolymer (PU), nano-titanium (PTiN) and raw material titanium powder (Ti).

[0058] Among them, the characteristic peak at 1093 cm -1 in the infrared spectrum of PU corresponds to the stretching vibration absorption peak of organosilicon Si-O-Si. The characteristic peaks at 1602 cm -1 , 1527 cm -1 , 1457 cm -1 correspond to the aromatic ring skeleton absorption peak. The characteristic peak at 810 cm -1 corresponds to the stretching vibration peak of organosilicon Si-C. The peak at 2270 cm -1 corresponds to the antisymmetric stretching absorption peak of -N=C=O at the end of the molecular chain, proving the successful synthesis of PU. The above corresponding groups also appear in the infrared spectrum of PTiN, indicating that the high-energy ball milling technology enables PU (polyurethane prepolymer) to be successfully coated on the surface of titanium particles. The disappearance of the -N=C=O absorption peak is because this active group undergoes chemical cross-linking with the surface titanium atoms during the ball milling process.

[0059] Figure 2It is the TEM image of PTiN. It can be seen that the raw material Ti is ground into nanoscale particles by high-energy ball milling, and the morphology of the nano-titanium functional filler is relatively thin nanosheets.

[0060] Example 2

[0061] This example is basically the same as Example 1, except that in Step 2, the mass of the polyurethane prepolymer PU is 40 g.

[0062] Example 3

[0063] This example is basically the same as Example 2, except that in Step 4, nano-titanium functional filler with a percentage content of 10% of polyurethane-modified epoxy resin needs to be additionally added and placed in a high-speed disperser to stir at a speed of 2400 rpm at room temperature for 3 h to obtain nano-titanium-polyurethane-modified epoxy coating.

[0064] Example 4

[0065] This example is basically the same as Example 2, except that in Step 4, nano-titanium functional filler with a percentage content of 12% of polyurethane-modified epoxy resin needs to be additionally added and placed in a high-speed disperser to stir at a speed of 2500 rpm at room temperature for 3 h to obtain nano-titanium-polyurethane-modified epoxy coating.

[0066] Example 5

[0067] This example is basically the same as Example 2, except that in Step 4, nano-titanium functional filler with a percentage content of 15% of polyurethane-modified epoxy resin needs to be additionally added and placed in a high-speed disperser to stir at a speed of 2400 rpm at room temperature for 3 h to obtain nano-titanium-polyurethane-modified epoxy coating.

[0068] Comparative Example 1

[0069] E44 epoxy resin and T31 curing agent are mixed and stirred evenly, and the curing system is coated on the surface of Q235 carbon steel with a size of 60 mm × 30 mm × 3 mm after surface sandblasting treatment, and placed in a blast drying oven at 80 °C for 4 h to obtain a cured coating, and the coating thickness is 100 ± 10 μm.

[0070] Test Result Analysis

[0071] 1. Coating Impact Experiment and Bending Experiment

[0072] The test standards for the impact resistance performance of all example and comparative example coatings refer to GB / Tl 732—2020, and the test instrument is a QCJ type paint film impact instrument. The test standards for the toughness of the coating refer to GB / T1731-2020, and the test instrument is a QTX type paint film elasticity tester.

[0073] The test results of the coating toughness and impact resistance are shown in Table 1. It can be seen from a comparison between Example 1, Example 2 and Comparative Example 1 (epoxy resin cured coating) that the toughness and impact resistance of the polyurethane-modified epoxy resin coating are significantly improved.

[0074] It can be seen from the test results of Example 3 and Example 4 that adding an appropriate amount of nano-titanium polymer functional filler does not affect the toughness and impact resistance of the polyurethane-modified epoxy resin coating.

[0075] Table 1 Test results of coating impact experiment and bending experiment

[0076]

[0077]

[0078] 2. Pull-off adhesion experiment

[0079] The test standard for the adhesion of all example and comparative example coatings is GB / T 5210-2006, and the test instrument is the PosiTest ATA-B pull-off adhesion tester.

[0080] The test results of the coating pull-off adhesion are shown in Table 2. It can be seen from a comparison between Example 1, Example 2 and Comparative Example 1 that the polyurethane-modified epoxy resin coating maintains excellent substrate adhesion of the epoxy resin.

[0081] It can be seen from the test results of Example 3, Example 4 and Example 5 that adding an appropriate amount of nano-titanium polymer functional filler does not affect the adhesion of the polyurethane-modified epoxy resin coating.

[0082] Table 2 Test results of coating pull-off adhesion experiment

[0083]

[0084] 3. Coating water absorption

[0085] The test standard for the water absorption of all example and comparative example coatings is HG / T 3344-2012. After testing the dry weight of the cured sample coating, it is immersed in a 3.5wt% sodium chloride solution, and then taken out at specific intervals to wipe off the surface water and weighed to calculate the water absorption. The test duration is 240h.

[0086] The test results are as shown in the appendix Figure 3 After 24h, all coatings reach the water absorption saturation state. Comparative Example 1 (epoxy resin cured coating) has the highest saturation water absorption. It can be seen from the test results of Example 1 and Example 2 that the saturation water absorption of the polyurethane-modified epoxy resin coating decreases, which is due to the reduction of epoxy resin curing defects after introducing the polyurethane prepolymer molecular chain segments.

[0087] From the test results of Example 3, Example 4 and Example 5, it can be seen that introducing an appropriate amount of nano-titanium polymer functional filler can further reduce the water absorption rate of the coating. This is because the functional filler has good dispersion compatibility in the polyurethane-modified epoxy resin, improves the density of the cured coating, and plays a barrier role in the cured coating, reducing the water molecule diffusion rate.

[0088] 4. Electrochemical testing

[0089] The corrosion protection performance of the coatings of all examples and comparative examples was tested by electrochemical impedance spectroscopy. The test platform was a Metrohm PGSTAT302N electrochemical workstation. A three-electrode system was selected. The carbon steel sheet coated with the coating was used as the working electrode, the test area radius was 1 cm, the saturated calomel electrode was used as the reference electrode, the platinum sheet electrode was used as the counter electrode, and 3.5 wt% sodium chloride solution was used as the electrolyte. The test frequency range was 10 5 -10 -2 Hz, the amplitude of the sine signal was 10 mV. Electrochemical impedance tests were carried out on the coatings of all examples and comparative examples after soaking in 3.5 wt% sodium chloride solution for 360 h. The test results were fitted using ZView2 software.

[0090] The Bode diagram of the electrochemical impedance spectrum is as shown in the appendix Figure 4 In the Bode diagram, the magnitude of the low-frequency impedance modulus |Z| 0.01Hz intuitively reflects the corrosion protection performance of the coating. After soaking in 3.5 wt% sodium chloride solution for 360 h, the low-frequency impedance modulus |Z| of the coating of Comparative Example 1 0.01Hz was the lowest. From the test results of Example 1 and Example 2, it can be seen that the long-term corrosion resistance of the polyurethane-modified epoxy resin coating is significantly improved compared with the epoxy coating. This is because the introduction of polyurethane prepolymer molecular chain segments reduces the curing defects of the epoxy resin and enhances the barrier performance against corrosive media.

[0091] From the test results of Example 3, Example 4 and Example 5, it can be seen that introducing an appropriate amount of nano-titanium polymer functional filler can further enhance the corrosion protection performance of the coating. This is because the functional filler has good dispersion compatibility in the polyurethane-modified epoxy resin and improves the density of the cured coating. Titanium nanoparticles with good chemical stability can effectively block the diffusion of corrosive media to the coating-metal substrate interface and improve the long-term corrosion protection performance of the coating.

[0092] The resistance values R of the coatings of the examples and comparative examples obtained by fitting the electrochemical impedance data c are as shown in the appendix Figure 5 Among them, the resistance value R of the coating of Example 4 c is the highest and the corrosion protection performance is the best.

[0093] The above are only the preferred embodiments of the present invention and do not constitute any form of limitation to the present invention. Although the present invention has been described through the above embodiments, for those skilled in the art, any adjustments, equivalent modifications and simple improvements made without departing from the spirit, principles and technical solution requirements of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a nano-titanium-polyurethane modified epoxy resin anti-corrosion coating, characterized in that: The following steps are involved: S1. Mix the polyol and the terminal hydroxypropyl silicone oil, remove water under vacuum, add diisocyanate, and react at 60-80°C to obtain a polyurethane prepolymer; S2. The polyurethane prepolymer prepared in S1 is blended with an epoxy resin for modification at a reaction temperature of 75-85° C. to obtain a polyurethane-modified epoxy resin; S3. The titanium powder, the polyurethane prepolymer prepared in S1 and the grinding aid are put into a high-energy ball mill, the titanium powder, the polyurethane prepolymer and the grinding aid are ground at high speed at room temperature and a rotation speed of 1500-2000rpm to obtain a black paste, which is a nano-titanium functional filler; S4. First, the polyurethane-modified epoxy resin, powder filler, dispersant, leveling agent and defoamer prepared in S2 are added to a mixed solvent and placed in a high-speed disperser and stirred at a speed of 2000-3000 rpm at room temperature to obtain a mixed slurry; then, the nano-titanium functional filler prepared in S3 is added and placed in a high-speed disperser and stirred at a speed of 2000-3000 rpm at room temperature to obtain a nano-titanium-polyurethane modified epoxy resin coating; S5. Add an amine curing agent to the coating, mix and stir, and finally apply it on the surface of the substrate and dry to obtain a cured coating.

2. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S1, the polyol is one or more of polyethylene glycol, polypropylene glycol, and polybutylene glycol; and / or the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and / or the molecular weight range of the terminal hydroxypropyl silicone oil is 2000-2500.

3. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S1, in the prepared polyurethane prepolymer, the content of blocked isocyanate groups is 5%-20% of the mass fraction of the polyurethane prepolymer.

4. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S2, the epoxy resin type is one or more of E20, E44, E51, and F44.

5. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S2, the mass ratio of the polyurethane prepolymer to the epoxy resin is 1:(2-10); in S3, the mass ratio of the titanium powder to the polyurethane prepolymer is 5:(3-6).

6. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S3, the grinding aid is one or more of xylene, n-butanol and acetone; and / or the titanium powder is high-purity industrial titanium powder with a purity of ≥99.95%.

7. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S4, the powder filler is one or more of talc, fumed silica, titanium dioxide, and graphene; and / or the mixed solvent is a mixed solvent of polar and non-polar solvent.

8. The method for preparing the nano titanium-polyurethane modified epoxy resin anticorrosion coating according to claim 1, characterized in that: In S5, the coating is applied on the surface of the substrate and placed in a 50-100° C. forced air drying oven for 4-10 hours to obtain a cured coating.

9. A nano-titanium-polyurethane modified epoxy resin anti-corrosion coating, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the nano-titanium-polyurethane modified epoxy resin anti-corrosion coating according to claim 9 in the surface protection of ballast tanks of marine vessels.

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