Protective coating film with high tolerance and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a high-tolerance protective coating film and a preparation method thereof, and the high-tolerance protective coating film comprises a heat-conducting electrophoresis binding layer, an anti-impact buffer layer and a self-repairing wear-resistant layer from bottom to top. According to the preparation method, in the preparation of the bonding layer, common silicon carbide whiskers are modified and grooved, so that the specific surface area of the silicon carbide whiskers is remarkably increased, a three-dimensional mechanical interlocking structure is formed, and the groove structure not only enhances the adhesive force through a physical anchoring effect, but also improves the bonding strength of the silicon carbide whiskers. A stable silicon-oxygen-carbon covalent bond network is formed through surface active sites and a silane coupling agent, in addition, a zigzag path of a groove effectively blocks diffusion of water molecules, the interface stability of a protective coating film is remarkably improved, and when the protective coating film is applied to the surface of an automobile, the problem of coating layering caused by water vapor permeation can be effectively solved through excellent damp-heat adhesive force of the protective coating film, and the service life of the protective coating film is prolonged. And the whole vehicle protection life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a protective coating with high tolerance and a preparation method thereof. Background Art

[0002] Car coating is a protective film that improves the protective performance and aesthetics of a vehicle. It forms a tough and transparent film on the surface of the car body, effectively resisting the impact of stones and scratches from branches during daily driving, reducing the risk of damage to the paint. This film is like putting an invisible protective suit on the car. It not only does not affect the original design of the car body, but also makes daily cleaning of the vehicle easier.

[0003] In the existing technology, the protective coating on the surface of the car mainly relies on simple physical adsorption and a small amount of unstable chemical bonding to adhere to the metal substrate on the surface of the car. It is difficult to resist the interfacial hydrolysis reaction caused by the penetration of water molecules in a hot and humid environment. When water vapor invades the metal substrate interface through the pores of the coating, it will preferentially destroy the weak bonding area between the metal oxide layer and the polymer, causing local stress concentration and forming a debonding starting point, resulting in delamination of the coating, resulting in a reduction in the protective life of the entire vehicle.

[0004] Based on this, the present invention provides a protective coating with high tolerance and a preparation method. Summary of the Invention

[0005] The purpose of the present invention is to provide a protective coating with high tolerance and a preparation method. The protective coating with high tolerance prepared by the present invention not only has good adhesion, but also has good impact resistance, wear resistance and self-repairing properties.

[0006] To achieve the above objectives, the present invention provides the following technical solutions: a protective coating with high tolerance and a preparation method, comprising, from bottom to top: a thermal conductive electrophoretic bonding layer, an impact-resistant buffer layer, and a self-repairing wear-resistant layer;

[0007] The thermal conductive electrophoretic bonding layer is composed of the following raw materials in parts by weight: 45-50 parts of modified polythioamide, 6-8 parts of grooved silicon carbide whiskers and 1-3 parts of epoxy silane coupling agent;

[0008] The impact-resistant buffer layer is composed of the following raw materials in parts by weight: 22 to 25 parts of block fluorosilicone prepolymer, 8 to 10 parts of polydopamine-coated boron nitride nanosheets and 4 to 6 parts of microencapsulated dicyclopentadiene;

[0009] The self-repairing wear-resistant layer is composed of the following raw materials in parts by weight: 16 to 18 parts of graphene oxide grafted polycaprolactone, 6 to 10 parts of surface-modified nanodiamonds and 10 to 15 parts of nickel-loaded halloysite nanotubes.

[0010] Preferably, the method for preparing the raw material of the thermal conductive electrophoretic bonding layer comprises the following steps:

[0011] Step 1: preparing a modified polythioamide by adding 2-mercaptobenzothiazole and 4,4'-diaminodiphenyl sulfone in a molar ratio of 1:(1-1.5) to a deep eutectic solvent made of choline chloride and urea, reacting at 130-140° C. for 5-6 hours, and then precipitating with ethanol to obtain a yellow solid, which is the modified polythioamide;

[0012] Step 2: preparing grooved silicon carbide whiskers by immersing the silicon carbide whiskers in 68% nitric acid, ultrasonically treating them at 70-90° C. for 4-5 hours, washing and drying them to obtain whiskers with grooves on their surfaces, namely, grooved silicon carbide whiskers;

[0013] Step 3: Weigh modified polythioamide, grooved silicon carbide whiskers and epoxy silane coupling agent as needed and add them to a ball mill with a ball-to-material ratio of 10:1. Continue grinding for 2 to 3 hours to obtain the raw material for the thermal conductive electrophoretic bonding layer.

[0014] Preferably, the method for preparing the raw material of the impact-resistant buffer layer comprises the following steps:

[0015] Step 1: Prepare a block fluorosilicone prepolymer by reacting hydroxyl-terminated polydimethylsiloxane and carboxyl-terminated perfluoropolyether in a molar ratio of 1:1 at 170-185° C. under nitrogen protection for 4-5 hours to obtain a transparent viscous liquid, which is the block fluorosilicone prepolymer;

[0016] Step 2: preparing microencapsulated dicyclopentadiene by mixing dicyclopentadiene and urea formaldehyde resin prepolymer in a mass ratio of 1:3, adding sodium lauryl sulfate emulsifier, stirring and reacting at pH 4.5 and 60-70° C. for 5-6 hours to obtain microencapsulated dicyclopentadiene with a wall thickness of 0.2-0.4 μm and a particle size of 10-15 μm;

[0017] Step 3: preparing polydopamine-coated boron nitride nanosheets, dispersing the boron nitride nanosheets in tris-hydroxymethylaminomethane hydrochloride buffer containing dopamine hydrochloride, stirring the reaction at 40-50° C. and 200-300 r / min for 10-12 hours, and collecting the precipitate after centrifugation to obtain the polydopamine-coated boron nitride nanosheets;

[0018] Step 4: Weigh the block fluorosilicone prepolymer, polydopamine-coated boron nitride nanosheets and microencapsulated dicyclopentadiene as needed, and use a reactor to continuously stir for 2 to 3 hours at 60 to 80° C. and a speed of 200 to 300 r / min to prepare the impact-resistant buffer layer raw material.

[0019] Preferably, the method for preparing the raw material of the self-repairing wear-resistant layer comprises the following steps:

[0020] Step a: preparing graphene oxide grafted polycaprolactone, mixing graphene oxide with an oxygen content of 30% and caprolactone monomer in a mass ratio of 1:(15-20), then adding stannous octoate catalyst, and performing a ring-opening polymerization reaction at 110-120° C. for 6-8 hours to obtain graphene oxide grafted polycaprolactone;

[0021] Step b: preparing surface-modified nanodiamonds by dispersing the nanodiamonds in methyl methacrylate, adding 0.1 wt% potassium persulfate as an initiator, reacting at 70-80° C. for 2-3 hours, and collecting the precipitate after centrifugation to obtain the surface-modified nanodiamonds;

[0022] Step c: preparing nickel-loaded halloysite nanotubes, selecting halloysite nanotubes and immersing them in a 15% hydrochloric acid solution, stirring at 70-90° C. for 2-3 hours, and then centrifuging and washing until neutral. The precipitate is obtained, which is acidified halloysite. The acidified halloysite is then added to an ethanol solution containing 5wt% γ-aminopropyltriethoxysilane, reacted at 50-70° C. for 4 hours, and centrifuged and dried to obtain a precipitate, which is silanized halloysite. The silanized halloysite is then dispersed in a 0.1mol / L nickel nitrate solution, chemically deposited at 40-50° C. and pH 5.8-6.2 for 30 minutes, and centrifuged to obtain a precipitate, which is nickel-loaded halloysite nanotubes;

[0023] Step d: Weigh graphene oxide grafted polycaprolactone, surface modified nanodiamond and nickel-loaded halloysite nanotubes as needed, use a reactor, and stir continuously for 3 to 4 hours at 90 to 110° C. and a rotation speed of 200 to 300 r / min to prepare a self-repairing wear-resistant layer raw material.

[0024] Preferably, in step 2, the sodium lauryl sulfate emulsifier accounts for 2-3% of the total mass of the dicyclopentadiene and urea formaldehyde resin prepolymer.

[0025] Preferably, in step 3, the mass concentration of dopamine hydrochloride in tris hydrochloride buffer is 2 mg / mL.

[0026] Preferably, in step a, the stannous octoate catalyst accounts for 0.5 to 1% of the total mass of the graphene oxide and the caprolactone monomer.

[0027] Preferably, the epoxy silane coupling agent can be replaced with tridecafluorooctyl triethoxysilane, and the added amount is 1.8 to 2.2 parts.

[0028] Preferably, a method for preparing a protective coating with high tolerance comprises the following steps:

[0029] S1: Substrate pretreatment: sandblasting the metal substrate to a surface roughness of Ra3.2μm;

[0030] S2: Preparation of thermal conductive electrophoretic bonding layer: Use electrostatic spraying equipment to spray the thermal conductive electrophoretic bonding layer raw materials onto the substrate at a voltage of 50kV, with a spray gun moving speed of 0.5m / s and pre-curing at 80℃ for 20 minutes to form a thermal conductive electrophoretic bonding layer;

[0031] S3: Preparation of the impact-resistant buffer layer: spray the raw material of the impact-resistant buffer layer onto the surface of the thermal conductive electrophoretic bonding layer at a pressure of 26 MPa and a spraying distance of 20 cm using a high-pressure airless spraying device, and cure at room temperature for 1 hour to form the impact-resistant buffer layer;

[0032] S4: Preparation of self-repairing wear-resistant layer. The raw material of the self-repairing wear-resistant layer is sprayed onto the surface of the impact-resistant buffer layer at a flame velocity of 800 m / s and a spraying distance of 15 cm using supersonic flame spraying equipment. At the same time, a 0.6T axial magnetic field is applied to make the nickel-loaded halloysite nanotubes oriented at 45°, forming a self-repairing wear-resistant layer and obtaining a highly tolerant protective coating.

[0033] Preferably, the thickness of the protective coating with high tolerance is 125-150 μm, wherein the thickness of the thermal conductive electrophoretic bonding layer is 25-30 μm, the thickness of the impact-resistant buffer layer is 65-75 μm, and the thickness of the self-repairing wear-resistant layer is 35-45 μm.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. In this preparation method, during the preparation of the bonding layer, ordinary silicon carbide whiskers are modified and grooved, so that the specific surface area of the silicon carbide whiskers is significantly increased, forming a three-dimensional mechanical interlocking structure. This groove structure not only enhances adhesion through a physical anchoring effect, but also forms a stable silicon-oxygen-carbon covalent bond network with the silane coupling agent through surface active sites. In addition, the tortuous path of the groove effectively blocks the diffusion of water molecules, significantly improving the interfacial stability of the protective coating. When applied to the surface of an automobile, its excellent wet and hot adhesion can effectively prevent coating delamination caused by water vapor penetration, thereby extending the protective life of the entire vehicle.

[0036] 2. In the preparation method, in the preparation of the impact-resistant buffer layer, encapsulated dicyclopentadiene is dually controlled by a specific wall material. The response characteristics of the wall material ensure that the repair agent is only released in a specific environment. The rupture of the microcapsule requires a certain mechanical stress, so that it is only activated in the real damaged area. This directional release mechanism greatly improves the utilization rate of the repair agent. At the same time, the volume expansion generated by the polymerization reaction effectively fills the cracks. Therefore, the introduction of microencapsulated dicyclopentadiene enables the automotive protective coating to quickly trigger the self-repair function when encountering flying stone impact or daily scratches, reducing maintenance costs and maintaining the integrity of the vehicle body appearance.

[0037] 3. In the present preparation method, during the preparation of the wear-resistant layer, the nickel-loaded halloysite is oriented by induction of a magnetic field to form a bionic layered structure, which can significantly extend the wear path. In addition, the nickel particles are preferentially distributed in the inner cavity of the halloysite, and the catalytic efficiency is significantly improved, ensuring that the repair agent is rapidly polymerized at the damaged site. At the same time, the surface-modified nanodiamonds and the oriented halloysite work synergistically to disperse stress through the load transfer effect, thereby significantly improving the wear resistance of the protective coating, extending the service life of the protective coating applied to automobiles, and solving the problem of corrosion caused by exposure of the metal substrate due to wear of the vehicle protective layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of a highly tolerant protective coating according to the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Example 1:

[0041] This embodiment provides a high-tolerance protective coating and a preparation method, which comprises, from bottom to top: a thermal conductive electrophoretic bonding layer, an impact-resistant buffer layer, and a self-repairing wear-resistant layer;

[0042] The thermal conductive electrophoretic bonding layer is composed of the following raw materials in parts by weight: 45 parts of modified polythioamide, 6 parts of grooved silicon carbide whiskers and 1 part of epoxy silane coupling agent;

[0043] The impact-resistant buffer layer is composed of the following raw materials in parts by weight: 22 parts of block fluorosilicone prepolymer, 8 parts of polydopamine-coated boron nitride nanosheets and 4 parts of microencapsulated dicyclopentadiene;

[0044] The self-repairing wear-resistant layer is composed of the following raw materials in parts by weight: 16 parts of graphene oxide grafted polycaprolactone, 6 parts of surface-modified nanodiamonds and 10 parts of nickel-loaded halloysite nanotubes.

[0045] The method for preparing the raw material of the thermal conductive electrophoresis bonding layer includes the following steps:

[0046] Step 1: preparing a modified polythioamide by adding 2-mercaptobenzothiazole and 4,4'-diaminodiphenyl sulfone in a 1:1 molar ratio to a deep eutectic solvent made of choline chloride and urea, reacting at 130°C for 5 hours, and then precipitating the reacted product with ethanol to obtain a yellow solid, which is the modified polythioamide.

[0047] Step 2: preparing grooved silicon carbide whiskers by immersing the silicon carbide whiskers in 68% nitric acid, ultrasonically treating them at 70° C. for 4 hours, washing and drying them to obtain whiskers with grooves on their surfaces, namely, grooved silicon carbide whiskers;

[0048] Step 3: Weigh modified polythioamide, grooved silicon carbide whiskers and epoxy silane coupling agent as needed and add them to a ball mill with a ball-to-material ratio of 10:1. Continue grinding for 2 hours to obtain the raw material for the thermal conductive electrophoretic bonding layer.

[0049] The method for preparing the raw material of the impact-resistant buffer layer comprises the following steps:

[0050] Step 1: Prepare a block fluorosilicone prepolymer by reacting hydroxyl-terminated polydimethylsiloxane and carboxyl-terminated perfluoropolyether in a molar ratio of 1:1 at 170°C under nitrogen protection for 4 hours to obtain a transparent viscous liquid, which is the block fluorosilicone prepolymer;

[0051] Step 2: preparing microencapsulated dicyclopentadiene by mixing dicyclopentadiene with urea formaldehyde resin prepolymer in a mass ratio of 1:3, adding sodium lauryl sulfate emulsifier, and stirring the mixture at pH 4.5 and 60° C. for 5 hours to obtain microencapsulated dicyclopentadiene with a wall thickness of 0.2 μm and a particle size of 10 μm;

[0052] Step 3: Prepare polydopamine-coated boron nitride nanosheets, disperse the boron nitride nanosheets in tris-hydrochloride buffer containing dopamine hydrochloride, stir and react at 40°C and 200 rpm for 10 hours, and collect the precipitate after centrifugation, which is the polydopamine-coated boron nitride nanosheets;

[0053] Step 4: Weigh block fluorosilicone prepolymer, polydopamine-coated boron nitride nanosheets and microencapsulated dicyclopentadiene as needed, and use a reactor to continuously stir at 60° C. and 200 r / min for 2 hours to prepare the impact-resistant buffer layer raw material.

[0054] The method for preparing the raw material of the self-repairing wear-resistant layer comprises the following steps:

[0055] Step a: preparing graphene oxide grafted polycaprolactone, mixing graphene oxide with an oxygen content of 30% and caprolactone monomer in a mass ratio of 1:15, then adding stannous octoate catalyst, and performing a ring-opening polymerization reaction at 110°C for 6 hours to obtain graphene oxide grafted polycaprolactone;

[0056] Step b: preparing surface-modified nanodiamonds by dispersing the nanodiamonds in methyl methacrylate, adding 0.1 wt% potassium persulfate as an initiator, reacting at 70° C. for 2 h, and collecting the precipitate after centrifugation to obtain the surface-modified nanodiamonds;

[0057] Step c: preparing nickel-loaded halloysite nanotubes, selecting halloysite nanotubes and immersing them in a 15% hydrochloric acid solution, stirring at 70°C for 2 hours, and then centrifuging and washing until neutral. The precipitate is acidified halloysite, and then the acidified halloysite is added to an ethanol solution containing 5wt% γ-aminopropyltriethoxysilane, reacting at 50°C for 4 hours. After centrifugal drying, the precipitate is obtained, which is silanized halloysite. The silanized halloysite is then dispersed in a 0.1mol / L nickel nitrate solution, chemically deposited at 40°C and pH 5.8 for 30 minutes, and centrifuged to obtain the precipitate, which is nickel-loaded halloysite nanotubes;

[0058] Step d: Graphene oxide grafted polycaprolactone, surface modified nanodiamond and nickel-loaded halloysite nanotubes were weighed as needed and continuously stirred in a reactor at 90° C. and a rotation speed of 200 r / min for 3 h to prepare a self-repairing wear-resistant layer raw material.

[0059] Wherein, in step 2, the sodium lauryl sulfate emulsifier accounts for 2% of the total mass of the dicyclopentadiene and urea formaldehyde resin prepolymer.

[0060] Wherein, in step 3, the mass concentration of dopamine hydrochloride in tris hydrochloride buffer is 2 mg / mL.

[0061] Wherein, in step a, the stannous octoate catalyst accounts for 0.5% of the total mass of graphene oxide and caprolactone monomer.

[0062] Among them, the epoxy silane coupling agent can be replaced with tridecafluorooctyl triethoxysilane, and the added amount is 1.8 parts.

[0063] Among them, a method for preparing a protective coating with high tolerance includes the following steps:

[0064] S1: Substrate pretreatment: sandblasting the metal substrate to a surface roughness of Ra3.2μm;

[0065] S2: Preparation of thermal conductive electrophoretic bonding layer: Use electrostatic spraying equipment to spray the thermal conductive electrophoretic bonding layer raw materials onto the substrate at a voltage of 50kV, with a spray gun moving speed of 0.5m / s and pre-curing at 80℃ for 20 minutes to form a thermal conductive electrophoretic bonding layer;

[0066] S3: Preparation of the impact-resistant buffer layer: spray the raw material of the impact-resistant buffer layer onto the surface of the thermal conductive electrophoretic bonding layer at a pressure of 26 MPa and a spraying distance of 20 cm using a high-pressure airless spraying device, and cure at room temperature for 1 hour to form the impact-resistant buffer layer;

[0067] S4: Preparation of self-repairing wear-resistant layer. The raw material of the self-repairing wear-resistant layer is sprayed onto the surface of the impact-resistant buffer layer at a flame velocity of 800 m / s and a spraying distance of 15 cm using supersonic flame spraying equipment. At the same time, a 0.6T axial magnetic field is applied to make the nickel-loaded halloysite nanotubes oriented at 45°, forming a self-repairing wear-resistant layer and obtaining a highly tolerant protective coating.

[0068] Among them, the thickness of the high-tolerance protective coating is 125μm, of which the thickness of the thermal conductive electrophoretic bonding layer is 25μm, the thickness of the impact-resistant buffer layer is 65μm, and the thickness of the self-repairing wear-resistant layer is 35μm.

[0069] Example 2:

[0070] A high-tolerance protective coating and preparation method, comprising, from bottom to top, a thermal conductive electrophoretic bonding layer, an impact-resistant buffer layer, and a self-repairing wear-resistant layer;

[0071] The thermal conductive electrophoretic bonding layer is composed of the following raw materials in parts by weight: 50 parts of modified polythioamide, 8 parts of grooved silicon carbide whiskers and 3 parts of epoxy silane coupling agent;

[0072] The impact-resistant buffer layer is composed of the following raw materials in parts by weight: 25 parts of block fluorosilicone prepolymer, 10 parts of polydopamine-coated boron nitride nanosheets and 6 parts of microencapsulated dicyclopentadiene;

[0073] The self-repairing wear-resistant layer is composed of the following raw materials in parts by weight: 18 parts of graphene oxide grafted polycaprolactone, 10 parts of surface-modified nanodiamonds and 15 parts of nickel-loaded halloysite nanotubes.

[0074] The method for preparing the raw material of the thermal conductive electrophoresis bonding layer includes the following steps:

[0075] Step 1: preparing a modified polythioamide by adding 2-mercaptobenzothiazole and 4,4'-diaminodiphenyl sulfone in a molar ratio of 1:1.5 to a deep eutectic solvent made of choline chloride and urea, reacting at 140°C for 6 hours, and then precipitating the resultant product by ethanol to obtain a yellow solid, which is the modified polythioamide.

[0076] Step 2: preparing grooved silicon carbide whiskers by immersing the silicon carbide whiskers in 68% nitric acid, ultrasonically treating them at 90° C. for 5 hours, washing and drying them to obtain whiskers with grooves on their surfaces, namely, grooved silicon carbide whiskers;

[0077] Step 3: Weigh modified polythioamide, grooved silicon carbide whiskers and epoxy silane coupling agent as needed and add them to a ball mill with a ball-to-material ratio of 10:1. Continue grinding for 3 hours to obtain the raw material for the thermal conductive electrophoretic bonding layer.

[0078] The method for preparing the raw material of the impact-resistant buffer layer comprises the following steps:

[0079] Step 1: Prepare a block fluorosilicone prepolymer by reacting hydroxyl-terminated polydimethylsiloxane and carboxyl-terminated perfluoropolyether in a molar ratio of 1:1 at 185°C under nitrogen protection for 5 hours to obtain a transparent viscous liquid, which is the block fluorosilicone prepolymer;

[0080] Step 2: preparing microencapsulated dicyclopentadiene by mixing dicyclopentadiene with urea formaldehyde resin prepolymer in a mass ratio of 1:3, adding sodium lauryl sulfate emulsifier, and stirring the mixture at pH 4.5 and 70° C. for 6 hours to obtain microencapsulated dicyclopentadiene with a wall thickness of 0.4 μm and a particle size of 15 μm;

[0081] Step 3: Prepare polydopamine-coated boron nitride nanosheets, disperse the boron nitride nanosheets in tris-hydrochloride buffer containing dopamine hydrochloride, stir and react at 50°C and 300 rpm for 12 hours, and collect the precipitate after centrifugation, which is the polydopamine-coated boron nitride nanosheets;

[0082] Step 4: Weigh block fluorosilicone prepolymer, polydopamine-coated boron nitride nanosheets and microencapsulated dicyclopentadiene as needed, and use a reactor to continuously stir at 80° C. and a speed of 300 r / min for 3 hours to prepare the impact-resistant buffer layer raw material.

[0083] The method for preparing the raw material of the self-repairing wear-resistant layer comprises the following steps:

[0084] Step a: preparing graphene oxide grafted polycaprolactone, mixing graphene oxide with an oxygen content of 30% and caprolactone monomer in a mass ratio of 1:20, then adding stannous octoate catalyst, and performing a ring-opening polymerization reaction at 120° C. for 8 hours to obtain graphene oxide grafted polycaprolactone;

[0085] Step b: preparing surface-modified nanodiamonds by dispersing the nanodiamonds in methyl methacrylate, adding 0.1 wt% potassium persulfate as an initiator, reacting at 80° C. for 3 h, and collecting the precipitate after centrifugation to obtain the surface-modified nanodiamonds;

[0086] Step c: preparing nickel-loaded halloysite nanotubes, selecting halloysite nanotubes and immersing them in a 15% hydrochloric acid solution, stirring at 90°C for 3 hours, and then centrifuging and washing until neutral. The precipitate is acidified halloysite, and then the acidified halloysite is added to an ethanol solution containing 5wt% γ-aminopropyltriethoxysilane, reacting at 70°C for 4 hours. After centrifugal drying, the precipitate is obtained, which is silanized halloysite. The silanized halloysite is then dispersed in a 0.1mol / L nickel nitrate solution, chemically deposited at 50°C and pH 6.2 for 30 minutes, and centrifuged to obtain the precipitate, which is nickel-loaded halloysite nanotubes;

[0087] Step d: Graphene oxide grafted polycaprolactone, surface modified nanodiamond and nickel-loaded halloysite nanotubes were weighed as needed and continuously stirred in a reactor at 110° C. and a rotation speed of 300 r / min for 4 h to prepare a self-repairing wear-resistant layer raw material.

[0088] Wherein, in step 2, the sodium lauryl sulfate emulsifier accounts for 3% of the total mass of the dicyclopentadiene and urea formaldehyde resin prepolymer.

[0089] Wherein, in step 3, the mass concentration of dopamine hydrochloride in tris hydrochloride buffer is 2 mg / mL.

[0090] Wherein, in step a, the stannous octoate catalyst accounts for 1% of the total mass of graphene oxide and caprolactone monomer.

[0091] Among them, the epoxy silane coupling agent can be replaced with tridecafluorooctyl triethoxysilane, and the added amount is 2.2 parts.

[0092] Among them, a method for preparing a protective coating with high tolerance includes the following steps:

[0093] S1: Substrate pretreatment: sandblasting the metal substrate to a surface roughness of Ra3.2μm;

[0094] S2: Preparation of thermal conductive electrophoretic bonding layer: Use electrostatic spraying equipment to spray the thermal conductive electrophoretic bonding layer raw materials onto the substrate at a voltage of 50kV, with a spray gun moving speed of 0.5m / s and pre-curing at 80℃ for 20 minutes to form a thermal conductive electrophoretic bonding layer;

[0095] S3: Preparation of the impact-resistant buffer layer: spray the raw material of the impact-resistant buffer layer onto the surface of the thermal conductive electrophoretic bonding layer at a pressure of 26 MPa and a spraying distance of 20 cm using a high-pressure airless spraying device, and cure at room temperature for 1 hour to form the impact-resistant buffer layer;

[0096] S4: Preparation of self-repairing wear-resistant layer. The raw material of the self-repairing wear-resistant layer is sprayed onto the surface of the impact-resistant buffer layer at a flame velocity of 800 m / s and a spraying distance of 15 cm using supersonic flame spraying equipment. At the same time, a 0.6T axial magnetic field is applied to make the nickel-loaded halloysite nanotubes oriented at 45°, forming a self-repairing wear-resistant layer and obtaining a highly tolerant protective coating.

[0097] Among them, the thickness of the high-tolerance protective coating is 150μm, of which the thickness of the thermal conductive electrophoretic bonding layer is 30μm, the thickness of the impact-resistant buffer layer is 75μm, and the thickness of the self-repairing wear-resistant layer is 45μm.

[0098] Example 3:

[0099] A high-tolerance protective coating and preparation method, comprising, from bottom to top, a thermal conductive electrophoretic bonding layer, an impact-resistant buffer layer, and a self-repairing wear-resistant layer;

[0100] The thermal conductive electrophoretic bonding layer is composed of the following raw materials in parts by weight: 48 parts of modified polythioamide, 7 parts of grooved silicon carbide whiskers and 2 parts of epoxy silane coupling agent;

[0101] The impact-resistant buffer layer is composed of the following raw materials in parts by weight: 24 parts of block fluorosilicone prepolymer, 9 parts of polydopamine-coated boron nitride nanosheets and 5 parts of microencapsulated dicyclopentadiene;

[0102] The self-repairing wear-resistant layer is composed of the following raw materials in parts by weight: 17 parts of graphene oxide grafted polycaprolactone, 8 parts of surface-modified nanodiamonds and 12 parts of nickel-loaded halloysite nanotubes.

[0103] The method for preparing the raw material of the thermal conductive electrophoresis bonding layer includes the following steps:

[0104] Step 1: preparing a modified polythioamide by adding 2-mercaptobenzothiazole and 4,4'-diaminodiphenyl sulfone in a molar ratio of 1:1.3 to a deep eutectic solvent made of choline chloride and urea, reacting at 135°C for 5.5 hours, and then precipitating with ethanol to obtain a yellow solid, which is the modified polythioamide;

[0105] Step 2: preparing grooved silicon carbide whiskers by immersing the silicon carbide whiskers in 68% nitric acid, ultrasonically treating them at 80° C. for 4.5 hours, washing and drying them to obtain whiskers with grooves on their surfaces, namely, grooved silicon carbide whiskers;

[0106] Step 3: Weigh modified polythioamide, grooved silicon carbide whiskers and epoxy silane coupling agent as needed and add them to a ball mill with a ball-to-material ratio of 10:1. Continue grinding for 2.5 hours to obtain the raw material for the thermal conductive electrophoretic bonding layer.

[0107] The method for preparing the raw material of the impact-resistant buffer layer comprises the following steps:

[0108] Step 1: Prepare a block fluorosilicone prepolymer by reacting hydroxyl-terminated polydimethylsiloxane and carboxyl-terminated perfluoropolyether in a molar ratio of 1:1 at 180°C under nitrogen protection for 4.5 hours to obtain a transparent viscous liquid, which is the block fluorosilicone prepolymer;

[0109] Step 2: preparing microencapsulated dicyclopentadiene by mixing dicyclopentadiene with urea formaldehyde resin prepolymer in a mass ratio of 1:3, adding sodium lauryl sulfate emulsifier, and stirring the mixture at pH 4.5 and 65° C. for 5.5 hours to obtain microencapsulated dicyclopentadiene with a wall thickness of 0.3 μm and a particle size of 13 μm;

[0110] Step 3: Prepare polydopamine-coated boron nitride nanosheets, disperse the boron nitride nanosheets in tris-hydrochloride buffer containing dopamine hydrochloride, stir and react at 45°C and 250 rpm for 11 hours, and collect the precipitate after centrifugation to obtain the polydopamine-coated boron nitride nanosheets;

[0111] Step 4: Weigh block fluorosilicone prepolymer, polydopamine-coated boron nitride nanosheets and microencapsulated dicyclopentadiene as needed, and use a reactor to continuously stir at 70° C. and a speed of 250 r / min for 2.5 hours to prepare the impact-resistant buffer layer raw material.

[0112] The method for preparing the raw material of the self-repairing wear-resistant layer comprises the following steps:

[0113] Step a: preparing graphene oxide grafted polycaprolactone, mixing graphene oxide with an oxygen content of 30% and caprolactone monomer in a mass ratio of 1:18, then adding stannous octoate catalyst, and performing a ring-opening polymerization reaction at 115°C for 7 hours to obtain graphene oxide grafted polycaprolactone;

[0114] Step b: preparing surface-modified nanodiamonds by dispersing the nanodiamonds in methyl methacrylate, adding 0.1 wt% potassium persulfate as an initiator, reacting at 75° C. for 2.5 h, and collecting the precipitate after centrifugation to obtain the surface-modified nanodiamonds;

[0115] Step c: preparing nickel-loaded halloysite nanotubes, selecting halloysite nanotubes and immersing them in a 15% hydrochloric acid solution, stirring at 80°C for 2.5 hours, and then centrifuging and washing until neutral. The precipitate is acidified halloysite, and the acidified halloysite is added to an ethanol solution containing 5wt% γ-aminopropyltriethoxysilane, reacted at 60°C for 4 hours, and centrifuged and dried to obtain a precipitate, which is silanized halloysite. The silanized halloysite is then dispersed in a 0.1mol / L nickel nitrate solution, chemically deposited at 45°C and pH 6 for 30 minutes, and centrifuged to obtain a precipitate, which is nickel-loaded halloysite nanotubes;

[0116] Step d: Graphene oxide grafted polycaprolactone, surface modified nanodiamond and nickel-loaded halloysite nanotubes were weighed as needed and continuously stirred in a reactor at 100° C. and a rotation speed of 250 r / min for 3.5 h to prepare a self-repairing wear-resistant layer raw material.

[0117] Wherein, in step 2, the sodium lauryl sulfate emulsifier accounts for 2.5% of the total mass of the dicyclopentadiene and urea formaldehyde resin prepolymer.

[0118] Wherein, in step 3, the mass concentration of dopamine hydrochloride in tris hydrochloride buffer is 2 mg / mL.

[0119] Wherein, in step a, the stannous octoate catalyst accounts for 0.8% of the total mass of graphene oxide and caprolactone monomer.

[0120] Among them, the epoxy silane coupling agent can be replaced with tridecafluorooctyl triethoxysilane, and the added amount is 2 parts.

[0121] Among them, a method for preparing a protective coating with high tolerance includes the following steps:

[0122] S1: Substrate pretreatment: sandblasting the metal substrate to a surface roughness of Ra3.2μm;

[0123] S2: Preparation of thermal conductive electrophoretic bonding layer: Use electrostatic spraying equipment to spray the thermal conductive electrophoretic bonding layer raw materials onto the substrate at a voltage of 50kV, with a spray gun moving speed of 0.5m / s and pre-curing at 80℃ for 20 minutes to form a thermal conductive electrophoretic bonding layer;

[0124] S3: Preparation of the impact-resistant buffer layer: spray the raw material of the impact-resistant buffer layer onto the surface of the thermal conductive electrophoretic bonding layer at a pressure of 26 MPa and a spraying distance of 20 cm using a high-pressure airless spraying device, and cure at room temperature for 1 hour to form the impact-resistant buffer layer;

[0125] S4: Preparation of self-repairing wear-resistant layer. The raw material of the self-repairing wear-resistant layer is sprayed onto the surface of the impact-resistant buffer layer at a flame velocity of 800 m / s and a spraying distance of 15 cm using supersonic flame spraying equipment. At the same time, a 0.6T axial magnetic field is applied to make the nickel-loaded halloysite nanotubes oriented at 45°, forming a self-repairing wear-resistant layer and obtaining a highly tolerant protective coating.

[0126] Among them, the thickness of the high-tolerance protective coating is 140μm, of which the thickness of the thermal conductive electrophoretic bonding layer is 28μm, the thickness of the impact-resistant buffer layer is 70μm, and the thickness of the self-repairing wear-resistant layer is 42μm.

[0127] Comparative Example 1: The difference between this comparative example and Examples 1 to 3 is that the grooved silicon carbide whiskers in the thermal conductive electrophoretic bonding layer are replaced by ordinary silicon carbide whiskers.

[0128] Comparative Example 2: The difference between this comparative example and Examples 1 to 3 is that the microencapsulated dicyclopentadiene in the impact-resistant buffer layer in this comparative example is replaced by liquid dicyclopentadiene as the repair agent.

[0129] Comparative Example 3: The difference between this comparative example and Examples 1 to 3 is that the nickel-loaded halloysite nanotubes in the self-repairing wear-resistant layer in this comparative example are replaced by conventional halloysite nanotubes.

[0130] Adhesion test: Test according to GB / T 1740-2007 standard and record the test results in the table below;

[0131] Self-repair performance test: Use 4mm steel shot to impact the coating surface at an impact speed of 150km / h and an impact angle of 45°. Each sample is tested 10 times, with 10 impact points each time. After 1 hour, observe and record the number of concave points on the coating surface, and record the test results in the table below;

[0132] Wear resistance test: Test according to GB / T 1768-2006 standard and record the test results in the table below.

[0133]

[0134] Comparing the data in the table, it can be seen that the high-tolerance protective coating prepared by the preparation method of Comparative Example 1 has a wet-heat adhesion retention rate of only 52.3%, while the high-tolerance protective coatings prepared by Examples 1-3 have wet-heat adhesion retention rates of more than 95%. This performance degradation is due to the smooth surface of untreated ordinary silicon carbide whiskers, which cannot form an effective bond with the polymer matrix. Ordinary whiskers are highly hydrophobic, resulting in extremely weak chemical bonding ability with epoxy silane coupling agents. In a wet-heat environment, water molecules easily penetrate to the interface to form a continuous water film, destroying the physical adsorption effect. In comparison, In Examples 1-3, the grooved silicon carbide whiskers significantly increase their specific surface area through surface grooves, forming a three-dimensional mechanical interlocking structure. This groove structure not only enhances adhesion through a physical anchoring effect but also forms a stable silicon-oxygen-carbon covalent bond network with the silane coupling agent via surface active sites. Furthermore, the tortuous paths of the grooves effectively block the diffusion of water molecules, significantly improving the interfacial stability of the protective coating. This demonstrates that the protective coating prepared by this method, when applied to automotive surfaces, exhibits excellent wet-hot adhesion, effectively preventing coating delamination caused by water vapor penetration and extending the protective life of the vehicle.

[0135] By comparing the data in the table, it can be seen that the high-tolerance protective coating prepared by the preparation method of Comparative Example 2 still has 80 pits in the 100 points of the impact test, while the number of pits after the impact test of the high-tolerance protective coating prepared by Examples 1-3 is ≤5, and the self-repair performance of the two is significantly different. This is because the liquid dicyclopentadiene causes a large amount of volatilization of the repair agent during the processing process, and large-sized droplets are formed due to phase separation during high-pressure spraying, which cannot accurately cover the damaged area. The unencapsulated repair agent undergoes partial polymerization in advance at the processing temperature, seriously reducing the utilization rate of the active ingredient. The microencapsulation design achieves dual control through specific wall materials. The response characteristics of the wall material ensure that the repair agent is only released in a specific environment. The rupture of the microcapsule requires a certain amount of mechanical stress, so that it is activated only in the actual damaged area. This directional release mechanism greatly improves the utilization rate of the repair agent. At the same time, the volume expansion generated by the polymerization reaction effectively fills the cracks. This shows that the introduction of microencapsulated dicyclopentadiene enables the automotive protective coating to quickly trigger the self-repair function when it encounters flying stone impact or daily scratches, reducing maintenance costs and maintaining the integrity of the vehicle body appearance.

[0136] It can be seen from the data in the comparison table that the wear amount of the high-tolerance protective coating prepared by the preparation method of Comparative Example 3 is significantly higher than that of the high-tolerance protective coating prepared by Examples 1-3. The fundamental reason is that the unmodified halloysite nanotubes are randomly distributed, resulting in stress concentration and brittle fracture. The halloysite without nickel catalyst cannot trigger the polymerization of dicyclopentadiene, making the microcracks caused by wear impossible to repair. This shows that the nickel-loaded halloysite is oriented by magnetic field induction to form a bionic layered structure, which can significantly extend the wear path. In addition, the nickel particles are preferentially distributed in the inner cavity of the halloysite, and the catalytic efficiency is significantly improved, ensuring that the repair agent is quickly polymerized at the damaged site. At the same time, the surface-modified nanodiamonds work synergistically with the oriented halloysite to disperse the stress through the load transfer effect, thereby significantly improving the wear resistance of the protective coating, extending the service life of the protective coating applied to automobiles, and solving the problem of corrosion caused by exposure of the metal substrate due to wear of the vehicle protective layer.

[0137] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0138] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A protective coating with high tolerance and a preparation method thereof, characterized in that From bottom to top, it includes: thermal conductive electrophoretic bonding layer, impact-resistant buffer layer and self-repairing wear-resistant layer; The thermal conductive electrophoretic bonding layer is composed of the following raw materials in parts by weight: 45-50 parts of modified polythioamide, 6-8 parts of grooved silicon carbide whiskers and 1-3 parts of epoxy silane coupling agent; The impact-resistant buffer layer is composed of the following raw materials in parts by weight: 22 to 25 parts of block fluorosilicone prepolymer, 8 to 10 parts of polydopamine-coated boron nitride nanosheets and 4 to 6 parts of microencapsulated dicyclopentadiene; The self-repairing wear-resistant layer is composed of the following raw materials in parts by weight: 16 to 18 parts of graphene oxide grafted polycaprolactone, 6 to 10 parts of surface-modified nanodiamonds and 10 to 15 parts of nickel-loaded halloysite nanotubes.

2. The high-tolerance protective coating according to claim 1, characterized in that: The method for preparing the raw material of the thermal conductive electrophoresis bonding layer comprises the following steps: Step 1: preparing a modified polythioamide by adding 2-mercaptobenzothiazole and 4,4'-diaminodiphenyl sulfone in a molar ratio of 1:(1-1.5) to a deep eutectic solvent made of choline chloride and urea, reacting at 130-140° C. for 5-6 hours, and then precipitating with ethanol to obtain a yellow solid, which is the modified polythioamide; Step 2: preparing grooved silicon carbide whiskers by immersing the silicon carbide whiskers in 68% nitric acid, ultrasonically treating them at 70-90° C. for 4-5 hours, washing and drying them to obtain whiskers with grooves on their surfaces, namely, grooved silicon carbide whiskers; Step 3: Weigh modified polythioamide, grooved silicon carbide whiskers and epoxy silane coupling agent as needed and add them to a ball mill with a ball-to-material ratio of 10:

1. Continue grinding for 2 to 3 hours to obtain the raw material for the thermal conductive electrophoretic bonding layer.

3. The high-tolerance protective coating according to claim 1, characterized in that: The method for preparing the raw material of the impact-resistant buffer layer comprises the following steps: Step 1: Prepare a block fluorosilicone prepolymer by reacting hydroxyl-terminated polydimethylsiloxane and carboxyl-terminated perfluoropolyether in a molar ratio of 1:1 at 170-185° C. under nitrogen protection for 4-5 hours to obtain a transparent viscous liquid, which is the block fluorosilicone prepolymer; Step 2: preparing microencapsulated dicyclopentadiene by mixing dicyclopentadiene and urea formaldehyde resin prepolymer in a mass ratio of 1:3, adding sodium lauryl sulfate emulsifier, stirring and reacting at pH 4.5 and 60-70° C. for 5-6 hours to obtain microencapsulated dicyclopentadiene with a wall thickness of 0.2-0.4 μm and a particle size of 10-15 μm; Step 3: preparing polydopamine-coated boron nitride nanosheets, dispersing the boron nitride nanosheets in tris-hydroxymethylaminomethane hydrochloride buffer containing dopamine hydrochloride, stirring the reaction at 40-50° C. and 200-300 r / min for 10-12 hours, and collecting the precipitate after centrifugation to obtain the polydopamine-coated boron nitride nanosheets; Step 4: Weigh the block fluorosilicone prepolymer, polydopamine-coated boron nitride nanosheets and microencapsulated dicyclopentadiene as needed, and use a reactor to continuously stir for 2 to 3 hours at 60 to 80° C. and a speed of 200 to 300 r / min to prepare the impact-resistant buffer layer raw material.

4. The high-tolerance protective coating according to claim 1, characterized in that: The method for preparing the raw material of the self-repairing wear-resistant layer comprises the following steps: Step a: preparing graphene oxide grafted polycaprolactone, mixing graphene oxide with an oxygen content of 30% and caprolactone monomer in a mass ratio of 1:(15-20), then adding stannous octoate catalyst, and performing a ring-opening polymerization reaction at 110-120° C. for 6-8 hours to obtain graphene oxide grafted polycaprolactone; Step b: preparing surface-modified nanodiamonds by dispersing the nanodiamonds in methyl methacrylate, adding 0.1 wt% potassium persulfate as an initiator, reacting at 70-80° C. for 2-3 hours, and collecting the precipitate after centrifugation to obtain the surface-modified nanodiamonds; Step c: preparing nickel-loaded halloysite nanotubes, selecting halloysite nanotubes and immersing them in a 15% hydrochloric acid solution, stirring at 70-90° C. for 2-3 hours, and then centrifuging and washing until neutral. The precipitate is obtained, which is acidified halloysite. The acidified halloysite is then added to an ethanol solution containing 5wt% γ-aminopropyltriethoxysilane, reacted at 50-70° C. for 4 hours, and centrifuged and dried to obtain a precipitate, which is silanized halloysite. The silanized halloysite is then dispersed in a 0.1mol / L nickel nitrate solution, chemically deposited at 40-50° C. and pH 5.8-6.2 for 30 minutes, and centrifuged to obtain a precipitate, which is nickel-loaded halloysite nanotubes; Step d: Weigh graphene oxide grafted polycaprolactone, surface modified nanodiamond and nickel-loaded halloysite nanotubes as needed, use a reactor, and stir continuously for 3 to 4 hours at 90 to 110° C. and a rotation speed of 200 to 300 r / min to prepare a self-repairing wear-resistant layer raw material.

5. The protective coating with high tolerance according to claim 3, characterized in that: In the step 2, the sodium lauryl sulfate emulsifier accounts for 2-3% of the total mass of the dicyclopentadiene and urea formaldehyde resin prepolymer.

6. The high-tolerance protective coating according to claim 3, characterized in that: In the step 3, the mass concentration of dopamine hydrochloride in the tris hydrochloride buffer solution is 2 mg / mL.

7. The high-tolerance protective coating according to claim 4, characterized in that: In the step a, the stannous octoate catalyst accounts for 0.5-1% of the total mass of the graphene oxide and the caprolactone monomer.

8. The protective coating with high tolerance according to claim 1, characterized in that: The epoxy silane coupling agent can be replaced with tridecafluorooctyl triethoxysilane, and the added amount is 1.8 to 2.2 parts.

9. A method for preparing a protective coating with high tolerance according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Substrate pretreatment: sandblasting the metal substrate to a surface roughness of Ra3.2μm; S2: Preparation of thermal conductive electrophoretic bonding layer: Use electrostatic spraying equipment to spray the thermal conductive electrophoretic bonding layer raw materials onto the substrate at a voltage of 50kV, with a spray gun moving speed of 0.5m / s and pre-curing at 80℃ for 20 minutes to form a thermal conductive electrophoretic bonding layer; S3: Preparation of the impact-resistant buffer layer: spray the raw material of the impact-resistant buffer layer onto the surface of the thermal conductive electrophoretic bonding layer at a pressure of 26 MPa and a spraying distance of 20 cm using a high-pressure airless spraying device, and cure at room temperature for 1 hour to form the impact-resistant buffer layer; S4: Preparation of self-repairing wear-resistant layer. The raw material of the self-repairing wear-resistant layer is sprayed onto the surface of the impact-resistant buffer layer at a flame velocity of 800 m / s and a spraying distance of 15 cm using supersonic flame spraying equipment. At the same time, a 0.6T axial magnetic field is applied to make the nickel-loaded halloysite nanotubes oriented at 45°, forming a self-repairing wear-resistant layer and obtaining a highly tolerant protective coating.

10. The high-tolerance protective coating according to claim 9, characterized in that: The thickness of the high-tolerance protective coating is 125 to 150 μm, wherein the thickness of the thermal conductive electrophoretic bonding layer is 25 to 30 μm, the thickness of the impact-resistant buffer layer is 65 to 75 μm, and the thickness of the self-repairing wear-resistant layer is 35 to 45 μm.

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