High-toughness high-wear-resistance epoxy composite coating and preparation method thereof

Abstract

The application provides a high-toughness high-wear-resistance epoxy composite coating and a preparation method thereof, and belongs to the technical field of polymer coatings and comprises the following steps: step 1, preparing hydroxylated nanoscale titanium dioxide; step 2, preparing silanized nanoscale titanium dioxide; step 3, preparing a core-shell structure graphene oxide-titanium dioxide; and step 4, preparing the high-toughness high-wear-resistance epoxy composite coating. The application has the advantages of mild preparation conditions, scientific rationality, precision and convenience, great achievement transformation potential, easy preparation of large-scale high-toughness high-wear-resistance nanocomposite coatings and wide application range.

Description

Technical Field

[0001] This invention relates to the field of polymer coating technology, specifically to a high-toughness, high-wear-resistant epoxy composite coating and its preparation method. Background Technology

[0002] The main forms of material failure include corrosion, fracture, and wear, with wear failure being the most common and often leading to catastrophic consequences and enormous economic losses. Since wear failure occurs constantly, effective protective measures are urgently needed. Therefore, high-toughness and high-wear-resistant composite coatings have become a research hotspot, offering a solution to these problems.

[0003] Epoxy resin is an important cross-linked thermosetting polymer with advantages such as high adhesion, good chemical stability, excellent mechanical properties, and resistance to chemical corrosion. However, the three-dimensional network structure formed by curing and cross-linking is often brittle and cannot effectively resist the initiation and propagation of cracks, resulting in poor friction reduction and wear resistance, which severely limits the application of epoxy-based coating systems. Therefore, the mechanical and tribological properties of epoxy resin are improved by adding various fillers with good mechanical and lubricating properties.

[0004] Currently, numerous studies have confirmed that filling with nano- or micro-particles can improve the mechanical and tribological properties of epoxy coating systems. For example, single materials such as carbon fiber, carbon nanotubes, graphene, titanium dioxide, aluminum oxide, organosilicon, molybdenum disulfide, polytetrafluoroethylene, and graphite can improve the toughness and wear resistance of epoxy coatings. In the prior art, CN111485418A discloses a method for preparing plant fiber cloth with surface grafted graphene oxide-silica, which improves the mechanical properties of plant fiber-reinforced epoxy resin composites, achieving a three-point bending strength of 126.0 MPa to 150 MPa. CN108385371B discloses a method for preparing plant fiber cloth / resin composites with surface grafted carbon nanotubes, which improves the interfacial adhesion between plant fibers and the resin matrix by uniformly grafting carbon nanotubes onto the surface of plant fibers. CN112143346A discloses a method for preparing a graphene oxide-grafted Fe2O3 / epoxy composite coating, utilizing ferric oxide nanospheres to improve the dispersibility of graphene oxide in the coating and to prepare a composite coating for corrosion protection. CN109338299B discloses a high-wear-resistant coating and its preparation method, using a pulverizer to screen uniformly sized molybdenum disulfide particles, and preparing a wear-resistant coating with a low coefficient of friction and low wear by deposition. However, under the existing technology, it is difficult for the prepared coating to simultaneously possess both flexibility and wear resistance. Furthermore, some coatings, due to the poor temperature resistance and durability of the resin matrix, cannot maintain their wear resistance for long periods in complex environments, thus affecting the quality and service life of the composite coating.

[0005] Therefore, this invention patent relates to a high-temperature resistant, wear-resistant, high-load resistant, and humid heat resistant nanocomposite coating. Its preparation method is simple, novel, scientific, reasonable, easy to operate, and has great potential for technology transfer. The resulting coating has a uniform and dense surface, high toughness, and is resistant to high and low temperatures, salt water corrosion, and friction and wear, making it suitable for a wide range of applications. Summary of the Invention

[0006] The purpose of this invention is to propose a high-toughness and high-wear-resistant epoxy composite coating and its preparation method. This composite coating has a small amount of added materials, controls the structure from the perspective of molecular self-assembly, and has excellent fatigue resistance and wear resistance. The preparation conditions are mild, scientific and reasonable, precise and convenient, with great potential for technology transfer, and it is easy to prepare large-scale high-toughness and high-wear-resistant nanocomposite coatings with a wide range of applications.

[0007] The technical solution of this invention is implemented as follows:

[0008] This invention provides a method for preparing a high-toughness, high-wear-resistant epoxy composite coating, comprising the following steps:

[0009] Step 1: Preparation of hydroxylated nano-sized titanium dioxide: Prepare an aqueous solution of isopropyl titanate, then add sodium hydroxide solution dropwise until the mixed solution turns white, sonicate and stir to obtain a uniform mixed solution, then centrifuge, wash, filter, and dry in an oven to obtain powder A;

[0010] Step 2: Preparation of silanized nano-sized titanium dioxide: Add the above powder A to a mixed solution of ethanol and water, ultrasonically disperse and stir until uniform, add dispersant polyvinylpyrrolidone and silane coupling agent in sequence, ultrasonically, heat and stir, then centrifuge, wash, filter, and dry in an oven to obtain powder B;

[0011] Step 3: Preparation of core-shell structured graphene oxide-titanium dioxide: Add the above powder B to the aqueous solution and stir evenly, then mix with the graphene oxide aqueous solution, heat and stir until uniform, then centrifuge, wash, filter, and dry in an oven to obtain powder C;

[0012] Step 4: Preparation of high-toughness and high-wear-resistant epoxy composite coating: Add the above powder C to the ethanol solution, add zinc sulfide and epoxy resin in sequence, heat to remove excess ethanol, stir and cool to room temperature to obtain a mixed solution, add defoamer and curing agent to the mixed solution and stir evenly, and scrape the mixed solution onto the substrate, cure and form to obtain a high-toughness and high-wear-resistant epoxy composite coating.

[0013] As a further improvement of the present invention, when adding isopropyl titanate in step 1, the aqueous solution should be continuously stirred and the container should be placed in an ice-water solution to prevent the mixed solution from overheating.

[0014] As a further improvement of the present invention, the heating temperature in step 2 is 70-90°C and the heating time is 20-30 hours.

[0015] As a further improvement of the present invention, the mass fractions of graphene oxide and titanium dioxide in powder C in step 3 are 1-7%, 3-7%, and 2-8%, respectively.

[0016] As a further improvement of the present invention, the heating in step 3 is to a temperature of 80-100°C for 3-5 hours.

[0017] As a further improvement of the present invention, the heating temperature in step 4 is 80-110℃, the heating time is 3-6 hours, and the mixed solution is stirred evenly until no bubbles overflow from the surface; the curing conditions are: initial curing at 40-60℃ for 8-16 hours, followed by curing at 100-140℃ for 3-5 hours.

[0018] As a further improvement of the present invention, the coating prepared in step 4 is uniform, dense and smooth, with a thickness of 50-200 μm.

[0019] As a further improvement of the present invention, the concentration of the sodium hydroxide solution is 0.01-0.05 mol / L.

[0020] As a further improvement of the present invention, the defoamer is BYK-066N from Dalian Liansheng Trading Co., Ltd.; the curing agent is E51 (bisphenol A type epoxy resin curing agent) from Dalian International Composite Materials Co., Ltd.

[0021] This invention further protects a high-toughness, high-wear-resistant epoxy composite coating prepared by the above-described preparation method.

[0022] This invention offers the following advantages: Graphene oxide sheets possess hydrophilic oxygen-containing functional groups, such as hydroxyl, carboxyl, and epoxy groups, both internally and on the surface. This makes them not only soluble in water and certain organic solvents but also suitable as covalent reaction sites, assembly sites for nanoparticles, or functional polymers. Therefore, based on the dispersibility and compatibility of graphene oxide in the coating matrix, it is chosen as a filler for anti-wear coatings. Simultaneously, graphene oxide, as a reinforcing phase, is beneficial for increasing the glass transition temperature of the epoxy resin matrix. This is due to its nanoscale size, which provides excellent dispersion and adhesion at the molecular level, while also altering the kinetic properties of the chain matrix. Furthermore, nanoscale titanium dioxide possesses numerous advantages, including high chemical stability, superhydrophobicity, thermal stability, and wear resistance, while also exhibiting certain strength and hardness, thus playing a load-bearing and wear-resistant role. It is widely used for the mechanical reinforcement and tribological modification of materials. By employing graphene oxide as the shell and nano-titanium dioxide as the core for molecular self-assembly, and through microscopic control, the advantages of both graphene oxide (shell) and nano-titanium dioxide (core) are integrated. Simultaneously, the chemical bonding at the core-shell interface ensures the stable existence and good dispersion of this core-shell structure within the coating matrix, enabling long-term enhancement of the mechanical and tribological properties of the epoxy resin. Furthermore, zinc sulfide, a metal composite solid lubricant with a closely packed hexagonal lattice structure, exhibits extremely low shear strength and weak stiffness. During friction, it can transform from a face-centered cubic structure to a hexagonal close-packed structure, facilitating the filling of scratches and grooves. It can also form a lubricant transfer film between friction pairs, improving the wear and fatigue resistance of the coating system. This invention proposes a microscopic control method from the perspective of molecular self-assembly to obtain a high-toughness, high-wear-resistant composite coating, achieving outstanding fatigue resistance and wear reduction properties in epoxy resin composite coatings with low additive content.

[0023] In summary, the preparation conditions of this invention are mild, scientifically sound, precise, convenient, and have great potential for commercialization. It is easy to prepare large-scale high-toughness and high-wear-resistant nanocomposite coatings and has a wide range of applications. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a field emission scanning electron microscope image of the graphene oxide powder in Example 1 of the present invention;

[0026] Figure 2 This is a field emission scanning electron microscope image of the silanized titanium dioxide powder in Example 1 of the present invention;

[0027] Figure 3 This is a field emission scanning electron microscope image of the core-shell TiO2-GO structure in Example 1 of the present invention;

[0028] Figure 4 This is a diagram illustrating the mechanism of the self-assembled TiO2-GO core-shell structure in Embodiment 1 of the present invention.

[0029] Figure 5 This is a surface scratch morphology image of the coating at 100°C in a dry state, as shown in Example 1 of the present invention.

[0030] Figure 6 This is a morphology image of the scratches on the coating surface in a wet state at 80°C in Example 1 of the present invention;

[0031] Figure 7 This is a morphology image of the scratches on the coating surface in Comparative Example 1 of the present invention at 80°C in a wet state;

[0032] Figure 8 This is a scratch morphology image of the coating surface at 100°C in a dry state, as shown in Example 2 of the present invention.

[0033] Figure 9 This is a scratch morphology image of the coating surface at 100°C in a dry state, as shown in Example 3 of the present invention.

[0034] Figure 10 This is a morphology diagram of the scratches on the coating surface in Comparative Example 1 of the present invention at 100°C in a dry state. Detailed Implementation

[0035] 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.

[0036] Example 1

[0037] First, 5 ml of isopropyl titanate was added to 120 ml of aqueous solution. Then, while sonicating, 0.01 mol / L sodium hydroxide solution was added dropwise until the solution turned white. The mixture was mechanically stirred for 45 minutes, then centrifuged, washed, filtered, and oven-dried to obtain hydroxylated titanium dioxide powder. This powder was placed in 40 g of water, and 360 g of ethanol solution, 8 g of KH550 silane coupling agent, and 2 g of polyvinylpyrrolidone were added sequentially. The mixture was stirred and refluxed at 80°C for 24 hours. After centrifugation, washing, filtration, and drying, the resulting silanized titanium dioxide powder was placed in an aqueous solution and stirred until homogeneous. Then, it was mixed with 1 g of graphene oxide solution and mechanically stirred for 1 hour. After centrifugation, filtration, washing, and drying, GO-TiO2 powder was obtained. This powder was then placed in 10 wt.% anhydrous ethanol, and 7 g of zinc sulfide and 100 g of epoxy resin were added. The mixture was stirred at 90°C. o After heating in a water bath for 4 hours and allowing it to cool naturally, the mixture was then rotated for 20 minutes in an emulsifier at 2000 rpm. Next, 0.5 g of defoamer and 34.5 g of curing agent were added, and the mixture was rotated for 5 minutes in a spin coater at 2000 rpm. Finally, the resulting solution was poured into a fixed mold and then evenly coated onto the substrate surface using a scraping method to obtain coating A. Initial curing was performed at 60°C for 12 hours, followed by further curing at 120°C. o After curing for 2 hours, it is used for tensile, friction and wear and corrosion resistance tests.

[0038] Figure 3 The image shows the field emission scanning electron microscope morphology of the molecular self-assembled system. As can be seen from the image, the core-shell TiO2-GO structure was successfully prepared and uniform titanium dioxide particles have grown on the surface of the graphene oxide without agglomeration. Figure 6 and Figure 7 They are respectively dry state high temperature 100 o C and humid high temperature 80 o The ultra-depth morphology image of the scratched surface under C shows that there is a dense wear-resistant transfer film on the scratched surface, which can significantly improve the fatigue resistance and wear resistance of the coating.

[0039] Example 2

[0040] First, 5 ml of isopropyl titanate was added to 120 ml of aqueous solution. Then, while sonicating, 0.01 mol / L sodium hydroxide solution was added dropwise until the solution turned white. The mixture was mechanically stirred for 45 minutes, then centrifuged, washed, filtered, and oven-dried to obtain hydroxylated titanium dioxide powder. 4 g of this powder was added to 360 g of anhydrous ethanol, along with 2 g of polyvinylpyrrolidone, and ultrasonically stirred until homogeneous. 100 g of epoxy resin was added, and the mixture was heated at 90°C for 4 hours while stirring. After natural cooling, it was rotated in an emulsifier at 2000 rpm for 20 minutes. Then, 0.5 g of defoamer and 34.5 g of curing agent were added, and the mixture was rotated in a spin coater at 2000 rpm for 5 minutes. Finally, the resulting solution was poured into a fixed mold and molded, and then uniformly coated onto the substrate surface using a scraping method to obtain coating B. Initial curing was performed at 60°C for 12 hours, followed by further curing at 120°C. o After curing (C), it will be ready for use after 2 hours.

[0041] Example 3

[0042] First, 5 ml of isopropyl titanate was added to 120 ml of aqueous solution. Then, while sonicating, 0.01 mol / L sodium hydroxide solution was added dropwise until the solution turned white. The mixture was mechanically stirred for 45 minutes, then centrifuged, washed, filtered, and dried in an oven to obtain hydroxylated titanium dioxide powder. This powder was placed in 40 g of water, and 360 g of ethanol solution, 8 g of KH550 silane coupling agent, and 2 g of polyvinylpyrrolidone were added sequentially. The mixture was stirred and refluxed at 80 °C for 24 hours. After centrifugation, washing, filtration, and drying, silanized titanium dioxide was obtained. Titanium powder was added to 360g of anhydrous ethanol, along with 2g of polyvinylpyrrolidone, and ultrasonically stirred until homogeneous. 100g of epoxy resin was then added, and the mixture was heated at 90℃ for 4 hours while stirring. After natural cooling, it was rotated for 20 minutes in an emulsifier at 2000 rpm. Then, 0.5g of defoamer and 34.5g of curing agent were added, and the mixture was rotated for 5 minutes in a spin coater at 2000 rpm. Finally, the resulting solution was poured into a fixed mold and molded, and then uniformly coated onto the substrate surface using a scraping method to obtain coating C. Initial curing was performed at 60℃ for 12 hours, followed by further curing at 120℃. o After curing (C), it will be ready for use after 2 hours.

[0043] Comparative Example 1

[0044] Mix 100g epoxy resin, 0.5g defoamer, and 45g curing agent together, and spin the mixture for 5 minutes at 2000 rpm using a spin coater. Apply the mixture evenly to the substrate surface using a scraper method to obtain coating D. Initially cure at 60℃ for 12 hours, then... o C then cures for 2 hours.

[0045] Comparative Example 2

[0046] First, mix 100g of epoxy resin and 7g of zinc sulfide and spin coat at 2000 rpm for 5 minutes. Then, add 0.5g of defoamer and 45g of hardener and mix together. Spin coat the mixture at 2000 rpm for 5 minutes. Apply the mixture evenly to the substrate surface using a scraper to obtain coating E. Initially cure at 60℃ for 12 hours. o C then cures for 2 hours.

[0047] Test Example 1

[0048] The coatings A and D prepared in Example 1 and Comparative Example 1 of this invention were subjected to performance tests, and the results are shown in Table 1.

[0049] Table 1 shows the friction coefficient and wear rate of the two lubricating coatings A and B prepared in Examples 1 and 2. It can be seen from the table that the friction coefficient and wear rate of the epoxy high wear-resistant composite coating with molecular self-assembled core-shell structure are much lower than those of the unmodified epoxy resin coating. That is, the epoxy resin coating can be endowed with excellent fatigue and wear resistance by nano-titanium dioxide / graphene oxide / zinc sulfide materials at low addition amounts.

[0050] Table 1

[0051]

[0052] Table 2

[0053]

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-toughness, high-wear-resistance epoxy composite coating, characterized in that, The method comprises the following steps: Step 1: Preparation of hydroxylated nanoscale titanium dioxide: prepare an isopropyl titanate aqueous solution, then drop a sodium hydroxide solution into the mixed solution until it becomes white, ultrasonically and stir to obtain a uniform mixed solution, then centrifuge, wash, suction filter and oven dry to obtain powder A; Step 2: Preparation of silanized nanoscale titanium dioxide: add powder A into a mixed solution of ethanol and water, ultrasonically and stir to obtain a uniform solution, then sequentially add a dispersant polyvinylpyrrolidone and a silane coupling agent, heat and stir after ultrasonic treatment, then centrifuge, wash, suction filter and oven dry to obtain powder B; Step 3: Preparation of a core-shell structure graphene oxide-titanium dioxide: add powder B into an aqueous solution, mix with a graphene oxide aqueous solution after stirring to obtain a uniform solution, then heat and stir, then centrifuge, wash, suction filter and oven dry to obtain powder C; Step 4: Preparation of a high-toughness and high-wear-resistance epoxy composite coating: add powder C into an ethanol solution, sequentially add zinc sulfide and an epoxy resin, remove excess ethanol by heating, stir to cool to room temperature to obtain a mixed solution, add a defoaming agent and a curing agent into the mixed solution and stir to obtain a uniform solution, then coat the mixed solution on a substrate by scraping, and solidify and form a high-toughness and high-wear-resistance epoxy composite coating.

2. The production method according to claim 1, characterized by, In step 1, the isopropyl titanate aqueous solution is continuously stirred and the container is placed in an ice water solution to prevent the mixed solution from overheating.

3. The preparation method according to claim 1, characterized in that, In step 2, the heating temperature is 70-90℃ and the heating time is 20-30 hours.

4. The method of claim 1, wherein, In step 3, the heating temperature is 80-100℃ and the heating time is 3-5 hours.

5. The preparation method according to claim 1, characterized in that, In step 4, the heating temperature is 80-110℃ and the heating time is 3-6 hours, the mixed solution is stirred until no bubbles overflow from the surface, the curing conditions are initial curing at 40-60℃ for 8-16 hours and post-curing at 100-140℃ for 3-5 hours.

6. The method of claim 1, wherein, The coating prepared in step 4 is uniform, dense and smooth in surface, and has a thickness of 50-200um.

7. The preparation method according to claim 1, characterized in that, The concentration of the sodium hydroxide solution is 0.01-0.05mol / L.

8. The method of claim 1, wherein, The defoaming agent is BYK-066N from Dalian Lian Sheng Trade Co., Ltd.

9. A high-toughness and high-wear-resistance epoxy composite coating prepared by the method of any one of claims 1-8.

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