Interpenetrating Double Network High-Strength Coating for High-Speed Trains and Its Preparation Method

Abstract

The present invention relates to a functional coating composite material, and particularly to an interpenetrating double-network high-strength coating for high-speed trains and a preparation method thereof. The interpenetrating double-network coating is made of polyurea and polyacrylate; wherein, the mass ratio of the polyurea to the polyacrylate is (1-2):(4-6); the preparation method of the interpenetrating double-network coating includes impregnating the polyurea in the raw material mixture for preparing the polyacrylate to achieve the interpenetration of the polyurea and the polyacrylate. The interpenetrating double-network coating of the present invention modifies the polyurea with polyacrylate, and interpenetrates the chain segments and network structures of the thermoplastic polyacrylate and the polyurea to play a role in strengthening and toughening. The interpenetrating double-network coating has high strength, toughness and shape memory effect, and can be used at the position of the train head that bears the frontal impact.

Description

Technical Field

[0001] The present invention relates to a functional coating composite material, and particularly to an interpenetrating double-network high-strength coating for high-speed trains and a preparation method thereof. Background Art

[0002] Aluminum alloy has become a research hotspot of light materials today due to its characteristics such as light weight, high strength, easy processing and beauty, and is also the first choice material for the lightweight of high-speed train car bodies. 7003 aluminum alloy belongs to the Al-Zn-Mg alloy system, has medium strength, good extrusion property, formability and weldability, and has been widely used in vehicles, bridges and equipment. With the general speed increase of modern trains, the speed of EMUs generally reaches 300 km / h. Coupled with the complex operating environment, it is inevitably affected by extreme weather such as sand blowing, floating dust and even hail during operation. Erosive wear has become the main form of damage to the coatings of EMUs.

[0003] The coatings of EMUs are required to have basic properties such as waterproof, anti-seepage and anti-cracking, and also be able to withstand the effects of heavy loads and alternating impacts brought by high-speed driving. The existing train heads generally adopt the method of unified spraying, and a composite coating of polyurea topcoat / polyester filler / intermediate paint / epoxy resin primer is sprayed on the train heads. Relevant literature has proposed that the tip of the train head is mainly affected by frontal impact during operation and is scratched by particles such as floating dust and sand. The main wear mechanisms are impact deformation and friction corrosion. The commonly used coating systems of current EMU coatings are severely worn during operation and need to be replaced frequently, so the operation and maintenance costs are relatively high. Summary of the Invention

[0004] The present invention provides an interpenetrating double-network coating, which modifies polyurea with polyacrylate, and interpenetrates the chain segments and network structures of thermoplastic polyacrylate and polyurea to play a role in enhancing and toughening. The interpenetrating double-network coating has high strength, toughness and shape memory effect, and can be used at the position of the train head that bears frontal impact.

[0005] An interpenetrating double-network coating is made of polyurea and polyacrylate; wherein, the mass ratio of the polyurea to the polyacrylate is (1-2):(4-6); the preparation method of the interpenetrating double-network coating includes impregnating the polyurea in the raw material mixture for preparing the polyacrylate to achieve the interpenetration of the polyurea and the polyacrylate.

[0006] According to an embodiment of the present invention, the mass ratio of the polyurea to the polyacrylate is (1-1.5):(4-5).

[0007] Further research found that the mass ratio of the polyurea to the polyacrylate has a significant impact on the performance of the interpenetrating double network coating. If the ratio of the two is too low, for example, less than 1:6, since the polyurea with long chains dominates in the system, the mobility of the molecular chain segments is greatly increased, resulting in the macroscopic manifestation of the coating material as a viscous flow state and a significant decrease in mechanical properties, which is not conducive to being used as a coating; if the ratio of the two is too high, for example, higher than 1:2, it will make the acrylate molecular chains with ester groups dominate in the copolymerization system, and the van der Waals forces generated by the high-density distribution of ester groups will cause phase separation in the system. The part represented by the ester group macroscopically shows a hard and brittle phase, which is also not conducive to the use of the coating.

[0008] According to an embodiment of the present invention, the polyurea is copolymerized from an end amino compound and a curing agent; the end amino compound can be selected from one or more of polyetheramine and hexamethylenediamine; the curing agent can be selected from one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate.

[0009] According to an embodiment of the present invention, the polyetheramine can be selected from one or more of D230, D400, D2000, T403, and T5000, and all of them can be commercially available.

[0010] In some specific examples, a solvent and a dispersant are also added when preparing the polyurea.

[0011] The solvent can be selected from one of butyl acetate and ethanol. Ethanol can volatilize rapidly after the coating film is formed.

[0012] The dispersant can be selected from one or more of dodecyldimethylbenzylammonium bromide, sodium dodecylbenzenesulfonate, polyvinyl alcohol, and hydroxypropyl methylcellulose.

[0013] In some specific examples, the polyurea is polymerized from an end amino compound (such as polyetheramine), a curing agent (such as diisocyanate), a solvent (such as butyl acetate), and a dispersant in a mass ratio of (10 - 30):(15 - 20):(5 - 10):(0.1 - 1).

[0014] Preferably, the polyurea is polymerized from an end amino compound (such as polyetheramine), a curing agent (such as diisocyanate), a solvent (such as butyl acetate), and a dispersant in a mass ratio of (10 - 20):(15 - 17):(5 - 7):(0.1 - 0.5).

[0015] According to an embodiment of the present invention, the polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent.

[0016] The structural formula of the monomer is shown as follows:

[0017] CH2=CH-CO(R)→(CH2-CH2(CO(R))) n

[0018] Wherein, R is a hydroxyl group or an alkoxy group, and n is 70,000 - 150,000.

[0019] Specifically, the alkoxy group may be selected from methoxy (CH3O - ), ethoxy (C2H5O - ).

[0020] According to an embodiment of the present invention, the monomer may be selected from one or more of methyl acrylate, ethyl acrylate, acrylic acid, etc.

[0021] According to an embodiment of the present invention, the initiator may be selected from one or more of 1-hydroxycyclohexyl phenyl ketone (184), 2-hydroxy-2-methyl-1-phenylpropanone (1173), methyl benzoylformate (MBF).

[0022] According to an embodiment of the present invention, the crosslinking agent may be selected from one or more of divinylbenzene, diisocyanate, N,N-methylenebisacrylamide, and 1,4-bis(acryloyloxy)butane.

[0023] According to an embodiment of the present invention, the polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent in a mass ratio of 1:(0.005 - 0.05):(0.001 - 0.01).

[0024] Preferably, the polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent in a mass ratio of 1:(0.005 - 0.01):(0.001 - 0.005).

[0025] According to a specific example of the present invention, the polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent in a mass ratio of 1:0.005:0.001.

[0026] The present invention also provides a method for preparing the above-mentioned interpenetrating double network coating, including: providing polyurea; immersing the polyurea in a raw material mixture for preparing the polyacrylate to achieve interpenetration of the polyurea and the polyacrylate.

[0027] Generally, polyurea can be prepared by a conventional method in the art.

[0028] In some embodiments, the method for preparing polyurea includes: mixing its raw materials and initiating polymerization in a hydrothermal environment. In some specific examples, the temperature of the polymerization is 60 - 70°C.

[0029] In some embodiments, the impregnation time of the polyurea in the raw material mixture for preparing the polyacrylate is 10 - 30 min. An overly long impregnation time will cause sufficient penetration of the acrylate (hard phase) that acts as the strength of the reinforcing material. After photocuring, it will greatly increase the hardness and strength of the coating and even break through the first polyurea network, making the coating tend to be hard and brittle; vice versa.

[0030] In some embodiments, the raw materials for preparing the polyacrylate further include a solvent, such as ethanol.

[0031] In some embodiments, the raw materials for preparing the polyacrylate (monomers, initiators, crosslinkers, and ethanol) are mixed according to the formula to form a mixture. In some examples, it further includes adjusting the pH of the mixture to 6.8 - 7.3, such as 7. It can be adjusted with glacial acetic acid.

[0032] In some embodiments, the method for preparing the above interpenetrating double - network coating further includes the steps of coating a mixture containing polyurea and then curing. Generally, it can be cured (for about 2 h) under the irradiation of an ultraviolet lamp (for example, with a power of 60 - 80 W and a wavelength of 365 nm). The swollen polyurea initiates the polymerization of methyl acrylate monomers between polyurea chain segments, and the monomers are fully cured, completing the interpenetration of the polyurea intermediate paint and the polyacrylate topcoat, that is, a polyacrylate / polyurea interpenetrating double - network coating is obtained.

[0033] In the interpenetrating double - network coating of the present invention, the polyacrylate and the polyurea achieve interpenetration between the networks. The polyurea and the polyacrylate serve as the first network and the second network respectively, thereby obtaining higher strength and toughness.

[0034] In some embodiments, the mixture containing polyurea can be coated on a substrate, such as aluminum alloy, including Al - Zn - Mg series alloys (such as 7003 aluminum alloy).

[0035] When the mixture containing polyurea is coated on the body of a high - speed train (bullet train) (such as the tip of the train head), it greatly improves the anti - frontal erosion ability of the coating and enhances the anti - wear ability of the coating, and can be used as an anti - erosion bullet train protective coating. This protective coating has a long service life. Compared with the existing coatings, this coating system has good water and chemical resistance, is convenient for construction and easy to construct, recoat, and rework, reduces waste caused by severe wear, and has a long service life.

[0036] In some specific examples, when the mixture containing polyurea is coated on the body of a high - speed train (bullet train) (such as the tip of the train head), the substrate needs to be cleaned (such as plasma treatment) to further enhance the composite with the interpenetrating double - network coating.

[0037] For example, a method for surface cleaning treatment of a substrate metal: Set the program of the plasma cleaner, select appropriate parameters to perform plasma bombardment on the metal substrate, then soak it with a pre-prepared trimethoxysiloxane solution, and then clean it with ethanol.

[0038] Trimethoxysiloxane solution: Using water as a solvent, prepare a trimethoxysiloxane solution and adjust the pH with acetic acid. The pH is approximately between 6 and 7.

[0039] The present invention also provides the application of the interpenetrating double network coating, especially its application on high-speed trains.

[0040] The present invention provides an impact-resistant coating for bullet trains that is simple and fast to synthesize, has stable properties, and is durable. The present invention enhances the adhesion between the coating and the vehicle body by specially treating the metal substrate and compounding it with a polymer coating. Through the penetration and interpenetration of polyacrylate into polyurea, the coating is strengthened and toughened, and a bullet train coating system with good adhesion, high strength and toughness, and corrosion and wear resistance is prepared. Compared with the original coating system, the erosion wear rate of the coating combination is reduced to 1 / 3 of the original. The overall service life of the coating is increased by about 3 times, has a long service life and is convenient for unified replacement, solving the problems of serious wear, frequent replacement, and difficult maintenance during the service of the current bullet train coating system. Description of the Drawings

[0041] Figure 1 Fourier transform infrared spectrum of acrylic monomers in Example 1.

[0042] Figure 2 Fourier transform infrared spectrum of polyacrylic acid in Example 1.

[0043] Figure 3 Impact wear test results of the existing polyurea composite coating system for bullet trains in Comparative Example 1.

[0044] Figure 4 Impact wear test results of the polyacrylate / polyurea interpenetrating high-strength coating in Example 1.

[0045] Figure 5 Impact wear test results of the polyacrylate / polyurea interpenetrating high-strength coating in Examples 2-5.

[0046] Figure 6 Impact wear test results of the polyacrylate / polyurea interpenetrating high-strength coating in Comparative Example 5.

[0047] Figure 7 Cyclic tensile test results of the polyacrylate / polyurea interpenetrating high-strength coating in Example 1.

[0048] Figure 8Test results of coating adhesion of the non-interpenetrating network prepared in Comparative Example 4 and the interpenetrating network coating of Example 1.

[0049] Figure 9 Test results of stress and strain of the coatings of Example 1 and Comparative Examples 1-3. Detailed implementation manners

[0050] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0051] Example 1

[0052] This example provides an interpenetrating double-network coating, which can be used as an interpenetrating double-network high-strength coating for bullet trains. It modifies polyurea with polyacrylate, interpenetrates thermoplastic poly(methyl acrylate) and polyurea to play a role in enhancing strength and toughness. The specific preparation method is as follows:

[0053] 1) Select polyurea as the first network. Select hexamethylenediamine and isophorone diisocyanate as reaction monomers, ethanol as the solvent, and sodium dodecylbenzenesulfonate as the dispersant. Mix hexamethylenediamine, ethanol, and sodium dodecylbenzenesulfonate in a mass ratio of 10:10:0.1 and stir evenly; mix isophorone diisocyanate, ethanol, and sodium dodecylbenzenesulfonate in a mass ratio of 15:5:0.1 and stir evenly.

[0054] 2) Drop the isophorone diisocyanate emulsion into the hexamethylenediamine emulsion through a peristaltic pump, keep it in a water bath at 60 °C for 2 h, then let it stand, centrifuge, and freeze-dry to obtain polyurea.

[0055] 3) Select high-purity oxygen as the gas source, generate oxygen plasma under low-pressure environment and an excitation frequency of 13.56 MHz, perform plasma bombardment on 7003 aluminum alloy for 10 min, soak it in a 2 wt% aqueous solution of trimethoxysilane by mass fraction, wash it with ethanol and dry it after 2 h.

[0056] 4) Synthesis of the polyacrylate elastomer coating: Mix the monomers, initiator, and cross-linking agent in a ratio of m1:m2:m3 = 1:0.005:0.001, stir evenly, and immerse the prepared polyurea and acrylate mixed solution in it according to a mass ratio of 1:4 until the polyurea swells. Then coat the polyurea on the washed aluminum alloy sheet and place it under an ultraviolet lamp with a wavelength of 365 nm and a power of 60 W for continuous irradiation for 2 h to initiate the polymerization of the second polyacrylate network.

[0057] The thickness of the interpenetrating double-network coating in this example is about 100 μm.

[0058] Example 2

[0059] This example provides an interpenetrating double-network coating, and the preparation method is as follows:

[0060] 1) Select polyurea as the first network. Select hexamethylenediamine and diphenylmethane diisocyanate as reaction monomers, ethanol as the solvent, and dodecyl dimethyl benzyl ammonium bromide as the dispersant. Mix hexamethylenediamine, ethanol, and sodium dodecylbenzenesulfonate in a mass ratio of 10:10:0.1 and stir evenly; mix diphenylmethane diisocyanate, ethanol, and sodium dodecylbenzenesulfonate in a mass ratio of 15:5:0.1 and stir evenly.

[0061] 2) Drop the diphenylmethane diisocyanate emulsion into the hexamethylenediamine emulsion through a peristaltic pump, keep it in a water bath at 60 °C for 2 h, then let it stand, centrifuge, and freeze-dry to obtain polyurea.

[0062] 3) Select high-purity oxygen as the gas source, generate oxygen plasma under low-pressure environment and excitation frequency of 13.56 MHz, bombard 7003 aluminum alloy for 10 min, soak it in a 2 wt% aqueous solution of trimethoxysiloxane, wash it with ethanol and dry it after 2 h.

[0063] 4) Synthesis of poly(methyl acrylate) elastomer coating: Mix monomers, initiator, and crosslinker in a ratio of m1:m2:m3 = 1:0.005:0.001, stir evenly, then immerse the prepared polyurea and acrylate mixed solution in it according to a mass ratio of 1:4 until the polyurea swells. Subsequently, coat the polyurea on the washed aluminum alloy sheet and place it under a UV lamp with a wavelength of 365 nm and a power of 60 W for continuous irradiation for 2 h to initiate the polymerization of the poly(methyl acrylate) second network.

[0064] The thickness of the interpenetrating double-network coating in this example is about 100 μm.

[0065] Example 3

[0066] This example provides an interpenetrating double-network coating, and the preparation method is as follows:

[0067] 1) Select polyurea as the first network. Select polyetheramine D230 and toluene diisocyanate as reaction monomers, ethanol as the solvent, and polyvinyl alcohol as the dispersant. Mix polyetheramine D230, ethanol, and polyvinyl alcohol in a mass ratio of 10:10:0.1 and stir evenly; mix toluene diisocyanate, ethanol, and polyvinyl alcohol in a mass ratio of 15:5:0.1 and stir evenly.

[0068] 2) Drop the toluene diisocyanate emulsion into the polyetheramine D230 emulsion through a peristaltic pump, keep it in a water bath at 60 °C for 2 h, then let it stand, centrifuge, and freeze-dry to obtain polyurea.

[0069] 3) Select high-purity oxygen as the gas source, generate oxygen plasma under low-pressure environment and the excitation frequency of 13.56 MHz, conduct plasma bombardment on 7003 aluminum alloy for 10 min, soak it with 2 wt% trimethoxysiloxane aqueous solution, and after 2 h, wash it with ethanol and dry it.

[0070] 4) Synthesis of poly(methyl acrylate) elastomer coating: Mix the monomer, initiator, and crosslinker in the ratio of m1:m2:m3 = 1:0.005:0.001, stir evenly, and immerse the prepared polyurea and acrylate mixed solution in it according to the mass ratio of 1:4 until the polyurea swells. Subsequently, coat the polyurea on the washed aluminum alloy sheet and place it under an ultraviolet lamp with a wavelength of 365 nm and a power of 60 W for continuous irradiation for 2 h to initiate the polymerization of the poly(methyl acrylate) second network.

[0071] The thickness of the interpenetrating double-network coating in this example is about 100 μm.

[0072] Example 4

[0073] This example provides an interpenetrating double-network coating, and the preparation method is as follows: 1) Select polyurea as the first network. Select polyetheramine D2000 and dicyclohexylmethane diisocyanate as reaction monomers, butyl acetate as the solvent, and hydroxypropyl methylcellulose as the dispersant. Mix hexamethylenediamine, butyl acetate, and hydroxypropyl methylcellulose in a mass ratio of 10:10:0.1 and stir evenly; mix dicyclohexylmethane diisocyanate, butyl acetate, and hydroxypropyl methylcellulose in a mass ratio of 15:5:0.1 and stir evenly.

[0074] 2) Drop the dicyclohexylmethane diisocyanate emulsion into the polyetheramine D2000 emulsion through a peristaltic pump, keep it in a water bath at 70 °C for 2 h, then let it stand, centrifuge, and freeze-dry to obtain polyurea.

[0075] 3) Select high-purity oxygen as the gas source, generate oxygen plasma under low-pressure environment and the excitation frequency of 13.56 MHz, conduct plasma bombardment on 7003 aluminum alloy for 10 min, soak it with 2 wt% trimethoxysiloxane aqueous solution, and after 2 h, wash it with ethanol and dry it.

[0076] 4) Synthesis of poly(ethyl acrylate) elastomer coating: Mix the monomer, initiator, and crosslinker in the ratio of m1:m2:m3 = 1:0.005:0.001, stir evenly, and immerse the prepared polyurea and acrylate mixed solution in it according to the mass ratio of 1:4 until the polyurea swells. Subsequently, coat the polyurea on the washed aluminum alloy sheet and place it under an ultraviolet lamp with a wavelength of 365 nm and a power of 60 W for continuous irradiation for 2 h to initiate the polymerization of the poly(ethyl acrylate) second network.

[0077] The thickness of the interpenetrating double-network coating in this example is approximately 100 μm.

[0078] Example 5

[0079] This example provides an interpenetrating double-network coating, and the preparation method is as follows: 1) Select polyurea as the first network. Select polyetheramine T403 and lysine diisocyanate as reaction monomers, butyl acetate as the solvent, and sodium dodecylbenzenesulfonate as the dispersant. Mix hexamethylenediamine, butyl acetate, and sodium dodecylbenzenesulfonate in a mass ratio of 10:10:0.1 and stir evenly; mix lysine diisocyanate, butyl acetate, and sodium dodecylbenzenesulfonate in a mass ratio of 15:5:0.1 and stir evenly.

[0080] 2) Drop the lysine diisocyanate emulsion into the polyetheramine T403 emulsion through a peristaltic pump, keep it in a water bath at 70 °C for 2 h, then let it stand, centrifuge, and freeze-dry to obtain polyurea.

[0081] 3) Select high-purity oxygen as the gas source, generate oxygen plasma under low-pressure environment and the excitation frequency of 13.56 MHz, conduct plasma bombardment on 7003 aluminum alloy for 10 min, soak it in a 2 wt% aqueous solution of trimethoxysiloxane, wash it with ethanol and dry it after 2 h.

[0082] 4) Synthesis of the polyethyl acrylate elastomer coating: Mix the monomers, initiator, and cross-linking agent in a ratio of m1:m2:m3 = 1:0.005:0.001, stir evenly, then immerse the prepared polyurea and acrylate mixed solution in it according to a mass ratio of 1:4 until the polyurea swells. Subsequently, coat the polyurea on the washed aluminum alloy sheet, and place it under an ultraviolet lamp with a wavelength of 365 nm and a power of 60 W for continuous irradiation for 2 h to initiate the polymerization of the second network of polyethyl acrylate.

[0083] The thickness of the interpenetrating double-network coating in this example is approximately 100 μm.

[0084] Comparative Example 1

[0085] The difference between this comparative example and Example 1 is only that: only polyurea is used as the coating, and an existing polyurea composite coating for bullet trains is selected.

[0086] Comparative Example 2

[0087] This example provides an interpenetrating double-network high-strength coating for bullet trains, which is composed of two polymer monomers. First, the first network is synthesized, and then the elastomer of the first network is immersed in another monomer solution. After it swells, ultraviolet initiation is carried out to further synthesize the interpenetrating double-network coating. The specific preparation method is as follows:

[0088] 1) First, select appropriate initiators and crosslinkers according to the experimental environment and reaction monomers. Methyl acrylate is selected as the reaction monomer for the first-layer network. The wavelength of the ultraviolet lamp in the laboratory is 365 nm and the power is 60 - 80 W. Therefore, 2-hydroxy-2-methyl-1-phenyl-1-propanone is selected as the photoinitiator, and 1,4-bis(acryloyloxy)butane is selected as the crosslinker.

[0089] 2) Surface modification of the metal substrate to be protected: Select appropriate parameters to perform plasma bombardment on 7003 aluminum alloy, and then soak it with the pre-prepared trimethoxysiloxane solution. After 2 h, clean it with ethanol and dry it.

[0090] 3) Synthesis of poly(methyl acrylate) elastomer coating: The monomer, initiator, crosslinker, and corrosion inhibitor are mixed in the ratio of m1:m2:m3:m4 = 1:5×10 -3 -1×10 -2 :1×10 -3 -1×10 -2 :1×10 -3 -5×10 -3 After stirring evenly, coat it on the cleaned aluminum alloy sheet, and irradiate it continuously with an ultraviolet lamp with a wavelength of 365 nm and a power of 60 W for 2 h to initiate the polymerization of methyl acrylate.

[0091] 4) Immerse the metal substrate to be protected coated with the elastomer coating in an ethyl acrylate solution. After the coating swells, irradiate it with an ultraviolet lamp to initiate the polymerization of the second-layer network, thereby obtaining a double-network anti-corrosion coating.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 1 is only that: only polyacrylic acid is used as the coating.

[0094] Comparative Example 4

[0095] The difference between this comparative example and Example 1 is only that: first coat polyurea on the cleaned aluminum alloy sheet to form a polyurea coating; after curing, coat polyacrylic acid, and finally form a polyurea-polyacrylic acid composite layer, but no interpenetrating double-network structure is formed. The two coatings remain independent of each other and do not entangle with each other, resulting in structural delamination and a significant decrease in mechanical properties compared with Example 1.

[0096] Comparative Example 5

[0097] The difference between this comparative example and Example 1 is only that: the impregnation time of the first-layer polyurea network in the second-layer acrylate network is 40 min.

[0098] Experiment 1

[0099] The Fourier transform infrared spectroscopy test was carried out on the acrylic monomer in Example 1, and the test results are as follows Figure 1 shown. The strong peak at 1730 cm -1 and the peaks at 1250 cm -1 , 1170 cm -1 are the characteristic peaks of the antisymmetric and symmetric stretching vibrations of C-O respectively, and the peak intensity at 1170 cm-1 is stronger than that at 1250 cm -1 . The peak at 1170 cm -1 is split into two peaks at 1160 cm -1 and 1180 cm -1 due to the influence of adjacent carbon atoms. The peak at 2950 cm -1 is the characteristic peak of the -COOH association.

[0100] The Fourier transform infrared spectroscopy test was carried out on the polyacrylic acid in Example 1, and the test results are as follows Figure 2 shown. The disappearance of the carbon-carbon double bond after copolymerization and the remaining -COOH groups in the side chain can be observed. The disappearance of the C=C double bond peak at the wavelength of 1635 cm -1 before and after polymerization can prove the successful synthesis of polyacrylic acid (PAA). The stretching vibration peak at 2950 cm- 1 before polymerization shifts to 2951 cm -1 after polymerization, and the same phenomenon also occurs during the polymerization of other acrylates.

[0101] Experiment 2

[0102] The impact wear experiment was carried out on the existing polyurea composite coating system for bullet trains in Comparative Example 1, and the results are as follows Figure 3 shown. The parameters are set as follows: the particle velocity is 100 m / s, the feeding rate is 3.00 g / min, and the particle size is about 100 μm. The experimental results show that whether it is small-angle erosion or frontal erosion, the erosion volume wear rate of this coating is above 0.30 mm 3 / g.

[0103] The specimens of the polyacrylate / polyurea interpenetrating high-strength coating in Example 1 were prepared and subjected to the impact wear experiment. The curve of the erosion wear rate of the composite coating varying with the incident angle is shown in Figure 4 . The experimental parameters are set as: the particle velocity is 100 m / s, the feeding rate is 3.00 g / min, and the particle size is about 100 μm.

[0104] The specimens of the polyacrylate / polyurea interpenetrating high-strength coatings in Example 2, Example 3, Example 4, and Example 5 were prepared and subjected to the impact wear experiment. The curve of the erosion wear rate of the composite coating varying with the incident angle is shown in Figure 5 . From Figure 5It can be seen that the samples of the above 5 embodiments all have good erosion wear resistance. The experimental parameters are set as follows: particle velocity 100 m / s, feeding rate 3.00 g / min, and particle size about 100 μm.

[0105] An impact wear experiment was carried out on the polyacrylate / polyurea interpenetrating high-strength coating with too long impregnation time in Comparative Example 5, as shown in Figure 6 , compared with Example 1, it can be seen that the coating of Comparative Example 5 is brittle. At a smaller angle, due to the higher strength than the polyurea coating of Comparative Example 1, the wear rate is lower; during the process of increasing the angle, due to the too high proportion of the acrylic part acting as the hard phase, the brittle coating is difficult to withstand the frontal impact, and the erosion volume wear rate increases to 0.42 mm 3 / g. The experimental parameters are set as follows: particle velocity 100 m / s, feeding rate 3.00 g / min, and particle size about 100 μm.

[0106] Experiment 3

[0107] A cyclic tensile experiment was carried out on the composite coating prepared in Example 1 to test its strength and toughness. The test results are as shown in Figure 7 . The hysteresis loops are not much different from the initial state after 100 and 200 cycles, indicating that the double-network structure of the coating can be well reorganized and dissipate internal stress, so that the coating has good mechanical maintenance ability, providing guarantee for the weather resistance of the coating.

[0108] Experiment 4

[0109] The coating adhesion of the non-interpenetrating network prepared in Comparative Example 4 and the interpenetrating network coating of Example 1 was tested. The results are shown in Figure 8 . 7003 aluminum alloy was selected as the metal matrix. Under the same conditions, the adhesion of the interpenetrating network was measured to be 8.19 ± 1.73 MPa, while the adhesion of the non-interpenetrating network was only 3.59 ± 0.36 MPa. It can be seen that due to the insufficient entanglement of molecular chains in the non-interpenetrating network, the coating peeling phenomenon is likely to occur, seriously affecting the coating life. In fact, due to the inevitable mutual penetration phenomenon during the curing process of the simple laminated structure, but the impregnation effect is far from enough compared with the double-network.

[0110] Experiment 5

[0111] The stress-strain tests of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown in Figure 9Compared with Example 1, the polyurea coating and the polymethacrylic acid coating in Comparative Example 1 and Comparative Example 3 are both single-network structures. Among them, the former has soft molecular chain segments, and macroscopically shows large strain but small stress, which is not suitable as an erosion-resistant coating. On the contrary, the latter is hard and brittle, and the toughness of the coating is insufficient. In addition, both Comparative Example 2 and Example 1 are double-network structure coatings. However, due to the relatively large toughness and long molecular chain segments of the polyurea material, compared with the double-network structure coatings with the same hard segments, the double-network structure of the former has stronger strength and toughness.

[0112] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An interpenetrating double network coating, characterized in that, Made of polyurea and polyacrylate; wherein, the mass ratio of the polyurea to the polyacrylate is (1 - 2):(4 - 6); The preparation method of the interpenetrating double network coating includes impregnating the polyurea in the raw material mixture for preparing the polyacrylate to achieve the interpenetration of the polyurea and the polyacrylate; The impregnation time of the polyurea in the raw material mixture for preparing the polyacrylate is 10 - 30 min; The preparation method of the interpenetrating double network coating further includes: coating the mixture containing the polyurea and then curing; The curing is carried out under ultraviolet lamp irradiation.

2. The interpenetrating double network coating according to claim 1, wherein The mass ratio of the polyurea to the polyacrylate is (1 - 1.5):(4 - 5).

3. The interpenetrating double network coating according to claim 1 or 2, characterized in that, The polyurea is copolymerized from an amino-terminated compound and a curing agent; The amino-terminated compound is selected from one or more of polyetheramine and hexamethylenediamine; The curing agent is selected from one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate.

4. The interpenetrating double network coating according to claim 1 or 2, characterized in that, The polyurea is polymerized from an amino-terminated compound, a curing agent, a solvent, and a dispersant according to the mass ratio of (10 - 30):(15 - 20):(5 - 10):(0.1 - 1).

5. The interpenetrating double network coating according to claim 4, wherein The polyurea is polymerized from an amino-terminated compound, a curing agent, a solvent, and a dispersant according to the mass ratio of (10 - 20):(15 - 17):(5 - 7):(0.1 - 0.5).

6. The interpenetrating double network coating according to claim 4, wherein, The solvent is selected from one of butyl acetate or ethanol; The dispersant is selected from one or more of dodecyldimethylbenzylammonium bromide, sodium dodecylbenzenesulfonate, polyvinyl alcohol, and hydroxypropyl methylcellulose.

7. The interpenetrating double network coating according to claim 1, wherein, The polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent; The structural formula of the monomer is as follows: CH2=CH-CO(R)→(CH2-CH2(CO(R))) n Wherein, R is a hydroxyl group or an alkoxy group, and n is 70000 - 150000; Optionally, the monomer is selected from one or more of methyl acrylate, ethyl acrylate, and acrylic acid.

8. The interpenetrating double network coating according to claim 1, wherein, The polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent according to the mass ratio of 1:(0.005 - 0.05):(0.001 - 0.01).

9. The interpenetrating double network coating according to claim 8, characterized in that, The polyacrylate is in-situ polymerized from a monomer, an initiator, and a crosslinking agent according to the mass ratio of 1:(0.005 - 0.01):(0.001 - 0.005).

10. The interpenetrating double network coating according to any one of claims 7-9, characterized in that, The initiator is selected from one or more of 1-hydroxycyclohexyl phenyl ketone (184), 2-hydroxy-2-methyl-1-phenyl propanone (1173), and methyl benzoylformate (MBF); The crosslinking agent is selected from one or more of divinylbenzene and diisocyanate, N,N-methylenebisacrylamide, and 1,4-bis(acryloyloxy)butane.

11. The preparation method of the interpenetrating double network coating according to any one of claims 1-10, characterized in that, Including: Providing polyurea; impregnating the polyurea in the raw material mixture for preparing the polyacrylate to achieve the interpenetration of the polyurea and the polyacrylate; The impregnation time of the polyurea in the raw material mixture for preparing the polyacrylate is 10 - 30 min; The preparation method of the interpenetrating double network coating further includes: coating the mixture containing the polyurea and then curing; The curing is carried out under ultraviolet lamp irradiation.

12. Use of the interpenetrating double network coating according to any one of claims 1-10, characterized in that, The application of the interpenetrating double network coating on high-speed trains.

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