Water-based paint for multi-material adhesion of engine and preparation method of water-based paint

Abstract

The invention relates to the technical field of water-based anticorrosive paint, and provides water-based paint for multi-material adhesion of an engine and a preparation method of the water-based paint. The water-based paint comprises a water-based acrylic emulsion, sanding slurry containing zinc phosphate and nano magnesium silicate, pre-coated calcium ion resin and an auxiliary agent; the pre-coated calcium ion resin is prepared by loading Ca < 2 + > on sulfonic acid type cation exchange resin and then coating with a polyvinylpyrrolidone layer, and then coating with acrylic acid to form an acrylic acid coating layer. When a corrosion medium permeates into the substrate, the acrylic acid coating layer swells under the action of H < + > to form pores, Ca < 2 + > is released, and the Ca < 2 + > and PO4 < 3-> of zinc phosphate generate a hydroxyapatite repairing layer, so that active self-repairing is realized. According to the scheme, the calcium ion resin coated with acrylic acid is used for achieving self-repairing, a compact barrier is constructed through zinc phosphate and nano magnesium silicate, the problem that corrosion diffusion is caused due to the fact that a traditional coating cannot be self-repaired in time after a coating is damaged is solved, and the coating can be effectively attached to multi-material parts of an engine and has long-acting corrosion resistance.

Description

Technical Field

[0001] The present application relates to the technical field of waterborne paints, and particularly relates to a waterborne paint for multi-material adhesion on engines and a preparation method thereof. Background Art

[0002] With the increasingly strict environmental protection regulations, waterborne anti-corrosion coatings, as an important direction to replace traditional solvent-based coatings, initially used chromates as the anti-corrosion main body, which have been banned due to their high toxicity; subsequently, zinc phosphate was used as the main corrosion inhibitor, and the corrosion inhibitor was introduced by physical doping, resulting in coexistence of initial burst release and later failure, and the high zinc content led to a decrease in the toughness of the coating, easy generation of hydrogen-induced blisters, and the hydrolysis of zinc powder oxidation products in a humid environment aggravated the coating peeling; the recent research focus is on self-healing coatings, introducing technologies such as microcapsules, and realizing single repair by encapsulating corrosion inhibitors, but too high a proportion of capsules will damage the coating denseness. Although the light / heat-responsive intelligent coating can achieve multiple repairs, it requires continuous external energy input, which is not suitable for the application scenarios of temperature fluctuations during engine start-stop conditions and lack of light in the closed structure, and generally has problems such as lagging repair response and passive triggering mechanism. The traditional filler system mostly adopts a single particle size design, making it difficult to construct a dense physical barrier. Micron-sized zinc phosphate can provide cathodic protection, but it is easy to form micropore defects; although nano-fillers can fill voids, they are prone to agglomeration and inactivation.

[0003] Chinese Patent with the authorization announcement number CN110452600B discloses a self-healing heavy anti-corrosion coating and a preparation method thereof. By arranging glass flakes in parallel and overlapping orientation, a series of barriers are formed against corrosive media, effectively increasing the penetration paths of corrosive media such as water, oxygen, and ions, and improving the anti-corrosion performance. The self-healing microcapsules therein are porous particles loaded with repair reagents, and the repair reagents in the coating around minor damages will be released from the porous particles to prevent further occurrence and spread of corrosion. However, the repair reagents used are organic reagents, physically loaded through porous particles, and need to be released passively after the coating is damaged, with a lagging repair response, and the photo-thermal triggering mechanism is not applicable in the closed engine environment, and the organic repair reagents may be affected by high temperatures and become ineffective, not suitable for engine conditions. Summary of the Invention

[0004] To solve the problem that traditional anti-corrosion coatings cannot be self-healed in time after coating damage, resulting in corrosion diffusion, the present application provides a waterborne paint for multi-material adhesion on engines and a preparation method thereof. The waterborne paint includes a waterborne acrylic emulsion, a sanding slurry containing zinc phosphate and nano-magnesium silicate, a pre-coated calcium ion resin, and an additive; the pre-coated calcium ion resin is prepared by loading Ca 2+ onto a sulfonic acid-type cation exchange resin and then coating it with a layer of polyvinylpyrrolidone, and then coating it with acrylic acid to form an acrylic acid coating layer. When corrosive media penetrate to the metal interface, the acrylic acid coating layer is in H +Swelling forms pores under the action, releasing Ca 2+ , and reacts with the PO4 of zinc phosphate 3- to generate a hydroxyapatite repair layer, achieving active self-repair. This solution uses an acrylic-coated calcium ion resin to achieve self-repair, and constructs a dense barrier through zinc phosphate and nano-magnesium silicate, solving the problem that traditional anti-corrosion coatings cannot be self-repaired in time after the coating is damaged, resulting in the spread of corrosion. It can effectively adhere to multi-material parts of the engine and has long-term anti-corrosion performance.

[0005] To achieve the above object, the present application adopts the following technical solutions: In the first aspect, the present application provides an aqueous paint for multi-material attachment of an engine, comprising: aqueous acrylic emulsion, sanding slurry, pre-coated calcium ion resin and additives; The sanding slurry contains zinc phosphate and nano-magnesium silicate; the pre-coated calcium ion resin is obtained by loading calcium ions on a sulfonic acid type cation exchange resin and then treating with polyvinylpyrrolidone.

[0006] In a feasible implementation case, the sulfonic acid type cation exchange resin is of H + type, and the exchange capacity ≥ 4.8 mmol / g; the particle size of the nano-magnesium silicate is 20 - 50 nm.

[0007] In a feasible implementation case, the mass ratio of the aqueous acrylic emulsion, sanding slurry, pre-coated calcium ion resin and additives is (50 - 55):(30 - 44):(5 - 8):(2 - 5).

[0008] In a feasible implementation case, the additives include nano-ceria, leveling agent BYK-346, adipic dihydrazide and hydroxyethyl cellulose aqueous solution with a mass ratio of (0.5 - 1):(0.2 - 0.5):(0.5 - 1.0):(2 - 3); the particle size of the nano-ceria is 20 - 50 nm.

[0009] In the second aspect, the present application provides a preparation method of an aqueous paint for multi-material attachment of an engine, comprising the following steps: S1. Pretreat the cation exchange resin, then carry out calcium ion loading, and then add polyvinylpyrrolidone for mixing and granulation, and obtain the pre-coated calcium ion resin after drying; S2. Mix zinc phosphate and nano-magnesium silicate and then grind them to obtain the sanding slurry; S3. Add the sanding slurry to the aqueous acrylic emulsion, then add additives and the pre-coated calcium ion resin, stir evenly, add deionized water to make the solid content 40% - 45% to obtain the aqueous paint; after filtering through a vibrating screen and storing under nitrogen, obtain the aqueous paint for multi-material attachment of the engine.

[0010] In a feasible implementation case, the preparation method of the pre-coated calcium ion resin described in S1 is specifically as follows: After soaking the cation exchange resin in deionized water until it swells, it is loaded into a glass column, hydrochloric acid solution is added, and it is rinsed until the pH of the effluent is within the range of 5-6, and then vacuum filtered until the moisture content is 40% - 50% to obtain the pretreated resin; The pretreated resin is reacted with a calcium chloride solution at a mass ratio of 1:(6-8), and washed until there is no residual chloride ion to obtain the calcium ion-loaded resin; The calcium ion-loaded resin is mixed with a polyvinylpyrrolidone solution at a mass ratio of (8-10):1, granulated, screened for 40-60 mesh particles, and vacuum dried until the moisture content < 3% to obtain the pre-coated calcium ion resin.

[0011] In a feasible implementation case, the preparation of the sanding slurry described in S2 further includes: mixing deionized water, sodium polyacrylate, polydimethylsiloxane, adjusting the pH to 8.5-9.0, and then adding zinc phosphate and nano-magnesium silicate; after stirring, it is sieved through a 300-mesh sieve, and the grinding treatment is carried out, and after the grinding treatment, it is sieved through an 800-mesh sieve to obtain the sanding slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate and nano-magnesium silicate is 50:(0.5-1.0):(0.1-0.3):(5-8):(3-5).

[0012] In a feasible implementation case, the molecular weight of the sodium polyacrylate is 7000-8000 g / mol; the viscosity of the polydimethylsiloxane is 280-300 cSt.

[0013] In a feasible implementation case, the preparation method of the aqueous acrylic emulsion described in S3 is: mixing butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate and water, and pre-emulsifying by high-speed shearing to form a monomer emulsion; dropping the monomer emulsion into an ammonium persulfate solution, and filtering through a sieve to obtain the aqueous acrylic emulsion.

[0014] In a feasible implementation case, after adding deionized water in S3, filtration and nitrogen filling preservation need to be completed within 30 minutes, and the preservation temperature ≤ 30 °C.

[0015] Beneficial technical effects: In this solution, Ca is pre-loaded through an ion exchange resin, 2+ pre-coated with a polyvinylpyrrolidone layer, and then coated with acrylic acid to form an acrylic acid coating layer. When the coating is damaged and the corrosive medium penetrates to the metal interface, the acrylic acid coating layer is protonated in an acidic environment, the molecular chain segments swell, pores are formed on the resin surface, and H + enters the resin interior through the pores and reacts with Ca on the sulfonic acid group 2+Competitive ion exchange occurs, and the released Ca 2+ diffuses through the pores to the interface, and the directionally released Ca 2+ reacts with the PO4 generated by the dissolution of zinc phosphate 3- to form a hydroxyapatite repair layer, achieving a self-repair response and preventing the spread of corrosion. At the same time, through the complex filling of the core-shell structure coated with resin and acrylic acid and micron-scale zinc phosphate and nano-scale magnesium silicate, a dense protective paint layer is formed to achieve corrosion resistance and improve durability. The water-based paint prepared by the present invention can effectively adhere to multi-material parts of the engine. At a low zinc content, it converts the corrosion chemical energy into a repair driving force, improves the repair efficiency, extends the corrosion life, and solves the problem that traditional anti-corrosion coatings cannot be self-repaired in time after corrosion occurs due to coating damage, resulting in the spread of corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the preparation method of the water-based paint for multi-material attachment of the engine of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the embodiments. However, it should not be understood that the scope of the present application is limited to the following examples. Without departing from the above method concept of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0018] In the present application, the terms used are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0019] In the present application, the singular forms of "is", "or", "a", "any one" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0020] In addition, if the terms "first" and "second" appear, they are only for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0021] In a first aspect, the present application provides a water-based paint for multi-material attachment of an engine, including: a water-based acrylic emulsion, a sanding slurry, a pre-coated calcium ion resin, and an additive; the sanding slurry contains zinc phosphate and nano-scale magnesium silicate; the pre-coated calcium ion resin is obtained by treating a sulfonic acid type cation exchange resin loaded with calcium ions with polyvinylpyrrolidone.

[0022] In a feasible implementation scenario, the sulfonic acid type cation exchange resin is H +Type, exchange capacity ≥ 4.8 mmol / g; the particle size of the nano magnesium silicate is 20 - 50 nm.

[0023] In a feasible implementation case, the mass ratio of the aqueous acrylic emulsion, the sanding slurry, the pre-coated calcium ion resin, and the additive is (50 - 55):(30 - 44):(5 - 8):(2 - 5).

[0024] In a feasible implementation case, the additive includes nano cerium oxide, leveling agent BYK - 346, adipic dihydrazide, and hydroxyethyl cellulose aqueous solution with a mass ratio of (0.5 - 1):(0.2 - 0.5):(0.5 - 1.0):(2 - 3); the particle size of the nano cerium oxide is 20 - 50 nm.

[0025] The aqueous acrylic emulsion serves as a film-forming substance and is compounded with the sanding slurry. The acrylic resin provides flexibility and adhesion, and the sanding slurry enhances mechanical strength and anti-corrosion performance. A solid content of 45% optimizes the coating leveling property and avoids cracking or shrinking holes; adding nano cerium oxide consumes O2 and H in the corrosive medium + , delaying the corrosion rate of the metal substrate; the leveling agent BYK - 346 can reduce the surface energy of the coating, enhance hydrophobicity, reduce water molecule penetration, and inhibit Cl - diffusion; adipic dihydrazide serves as a cross-linking agent and reacts with the carboxyl groups of the acrylic emulsion to form a cross-linked network structure, improving the hardness and impact resistance of the coating; the hydroxyethyl cellulose aqueous solution serves as a thickening agent, which can adjust the rheology of the coating, prevent filler sedimentation, and ensure construction uniformity. The prepared water-based paint is passed through a 200-mesh vibrating sieve to remove impurities, and stored under nitrogen to extend the storage stability of the paint and avoid premature activation of the resin.

[0026] In the second aspect, the present application provides a preparation method of a water-based paint for multi-material adhesion of an engine, including the following steps: S1. Pretreat the cation exchange resin, then carry out calcium ion loading, and then add polyvinylpyrrolidone for mixing and granulation, and obtain the pre-coated calcium ion resin after drying; S2. Mix zinc phosphate and nano magnesium silicate and then grind them to obtain the sanding slurry; S3. After adding the sanding slurry to the aqueous acrylic emulsion, add the additive and the pre-coated calcium ion resin, stir evenly, and add deionized water to make the solid content 40% - 45% to obtain the water-based paint; after filtering through a vibrating sieve and storing under nitrogen, obtain the water-based paint for multi-material adhesion of the engine.

[0027] Ion exchange resin pre-loaded with Ca 2+ , covering a polyvinylpyrrolidone layer on the resin surface, and then coating with acrylic acid to form an acrylic acid coating layer. Under normal conditions, a physical barrier is formed to prevent the resin from directly contacting the aqueous medium in the coating, avoiding Ca2+ Premature release; when a corrosive medium (such as Cl - , H2O, O2) penetrates to the metal interface, an anodic reaction starts to occur on the metal substrate (Fe → Fe 2+ +2e - ), and a cathodic reaction generates H + (2H + +2e - →H2↑). The concentration of H + in the local microenvironment increases significantly. The acrylic coating layer undergoes protonation in an acidic environment, the molecular chain segments swell, and nano-scale pores are formed on the resin surface. H + enters the resin interior through the pores, undergoes competitive ion exchange with Ca 2+ on the sulfonic acid groups, and the released Ca 2+ diffuses to the interface through the pores. The directionally released Ca 2+ reacts with PO4 3- dissolved from zinc phosphate to form a hydroxyapatite repair layer, achieving a self-repair response. At the same time, through the core-shell structure of the resin and acrylic coating and the compound filler of micron-scale zinc phosphate and nano-scale magnesium silicate, a dense protective paint layer is formed to achieve a corrosion-resistant effect and improve durability. The chemical energy released by the corrosion reaction provides a driving force for ion exchange, and there is no need for external energy input. The release position of Ca 2+ is accurately limited to the corrosion site, avoiding waste of resources.

[0028] In a feasible implementation case, the preparation method of the pre-coated calcium ion resin described in S1 is specifically as follows: Soak the cation exchange resin in deionized water until it swells, then load it into a glass column, add hydrochloric acid solution, and rinse until the pH of the effluent is in the range of 5-6. Then vacuum filter until the moisture content is 40% - 50% to obtain a pretreated resin; React the pretreated resin with calcium chloride solution at a mass ratio of 1:(6-8), and wash until there is no residual chloride ion to obtain a calcium ion-loaded resin; Mix the calcium ion-loaded resin with polyvinylpyrrolidone solution at a mass ratio of (8-10):1, granulate, screen 40-60 mesh particles, and vacuum dry until the moisture content < 3% to obtain the pre-coated calcium ion resin.

[0029] First, pretreat the sulfonic acid type cation exchange resin. The resin is converted to the H + type by hydrochloric acid treatment to activate the sulfonic acid groups (-SO3H), enhance the ion exchange ability, improve the calcium ion loading efficiency, and promote the full progress of subsequent ion exchange reactions; then react the resin with calcium chloride solution, and H + is replaced by Ca 2+Replacement is carried out to form calcium ion-loaded resin, providing an ion source for subsequent corrosion-triggered self-repair. Polyvinylpyrrolidone solution is used as an adhesive to promote the uniform granulation of resin particles. Its long-chain structure prevents resin agglomeration through steric hindrance effects. Moreover, the polyvinylpyrrolidone molecular chain contains a large number of polar amide groups (-N-C=O), which can form hydrogen bonds with the carboxylic acid groups in the acrylic emulsion, enhancing the interfacial bonding force between the two and promoting the uniform mixing of polyvinylpyrrolidone and acrylic acid. The polyvinylpyrrolidone layer serves as an intermediate transition layer and further combines with the aqueous acrylic emulsion to form a core-shell structure with resin as the core and an acrylic composite layer as the shell.

[0030] In a feasible implementation scenario, the preparation of the sanding slurry in S2 further includes: mixing deionized water, sodium polyacrylate, and polydimethylsiloxane, adjusting the pH to 8.5 - 9.0, and then adding zinc phosphate and nano-magnesium silicate; after stirring, passing through a 300-mesh sieve, performing the grinding treatment, and passing through an 800-mesh sieve after the grinding treatment to obtain the sanding slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate, and nano-magnesium silicate is 50:(0.5 - 1.0):(0.1 - 0.3):(5 - 8):(3 - 5).

[0031] Zinc phosphate and nano-magnesium silicate are compounded, and a sodium polyacrylate dispersant and a polydimethylsiloxane wetting agent are added to form a stable suspension system. Among them, zinc phosphate provides anodic protection to passivate the surface of the metal substrate. Nano-magnesium silicate fills the micropores of the coating, hydrolyzes to generate colloidal silica, and blocks the diffusion path of the corrosive medium. Sodium polyacrylate acts as a dispersant to prevent the agglomeration of zinc phosphate and magnesium silicate and improve the uniformity of the slurry; polydimethylsiloxane acts as a wetting agent to reduce the surface tension and enhance the bonding between the filler and the matrix; 2-amino-2-methyl-1-propanol adjusts the pH to 8.5 - 9.0 to stabilize the premix system. Then, the premix is subjected to a grinding treatment to improve the dispersibility of the filler, reduce the microdefects of the coating, and uniformly embed nano-magnesium silicate into the gaps of zinc phosphate to form a dense physical barrier.

[0032] In a feasible implementation scenario, the molecular weight of the sodium polyacrylate is 7000 - 8000 g / mol; the viscosity of the polydimethylsiloxane is 280 - 300 cSt.

[0033] In a feasible implementation scenario, the preparation method of the aqueous acrylic emulsion in S3 is: mixing butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, and water, and performing high-speed shear pre-emulsification to form a monomer emulsion; dropping the monomer emulsion into an ammonium persulfate solution and filtering through a sieve to obtain the aqueous acrylic emulsion.

[0034] In a feasible implementation scenario, after adding deionized water in S3, filtration and nitrogen filling preservation need to be completed within 30 minutes, and the preservation temperature ≤ 30 °C.

[0035] The following will specifically describe an aqueous paint for multi-material adhesion of an engine and its preparation method provided by the present application in combination with different embodiments.

[0036] The sulfonic acid type cation exchange resin used in the embodiment is of type H + , with an exchange capacity ≥ 4.8 mmol / g; the particle size of nano magnesium silicate is 20 - 50 nm; the viscosity of the hydroxyethyl cellulose aqueous solution is 6500 mPa·s; the particle size of nano cerium oxide is 20 - 50 nm.

[0037] Example 1 As Figure 1 shown, a preparation method of an aqueous paint for multi-material adhesion of an engine includes the following steps: 1. Immerse the sulfonic acid type cation exchange resin in deionized water for 24 h until fully swollen; load it into a glass column with a diameter-height ratio of 1:5, and pass through a 5% hydrochloric acid solution at a flow rate of 2 BV / h for 3 h; rinse with deionized water until the pH of the effluent is 5; perform vacuum filtration until the water content is 45% to obtain a pretreated resin; add the pretreated resin and a 1.5 mol / L calcium chloride solution to the reaction kettle at a mass ratio of 1:8, heat up to 40 °C, stir at 200 rpm for 6 h, wash with deionized water until no precipitation is detected by 0.1 mol / L silver nitrate to obtain a calcium ion-loaded resin; mix the calcium ion-loaded resin and a 1 wt% polyvinylpyrrolidone solution at a mass ratio of 10:1; granulate through an extrusion spheronizer at a rotational speed of 800 rpm, with a pore diameter of 0.8 mm; sequentially pass through a 40-mesh sieve and a 60-mesh sieve, screen the particles between 40 - 60 meshes, and vacuum dry until the water content < 3% to obtain a pre-coated calcium ion resin; 2. Mix butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, and water, and perform high-speed shearing pre-emulsification at 2000 rpm for 30 min to form a monomer emulsion; heat the 10 g / L ammonium persulfate solution to 75 °C, and slowly drop the monomer emulsion. The mass ratio of butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, water, and ammonium persulfate solution is 50:35:4:1.5:30:80, control the temperature below 80 °C, and finish dropping in 3 h. After keeping warm for 1 h, cool down to 40 °C and filter through a 200-mesh sieve to obtain an aqueous acrylic emulsion; 3. Under stirring at 300 rpm, mix deionized water, sodium polyacrylate (molecular weight 8000 g / mol), and polydimethylsiloxane (viscosity 300 cSt), adjust the pH to 8.5 with 2-amino-2-methyl-1-propanol, stir until completely dissolved, then add zinc phosphate and nano magnesium silicate; after stirring, pass through a 300-mesh sieve, and then carry out the grinding treatment. During the grinding process, control the temperature with a water-cooled jacket to maintain the temperature < 40°C. After grinding, pass through an 800-mesh sieve to obtain a sanded slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate, and nano magnesium silicate is 50:0.5:0.1:5:3; 4. Under stirring at 600 rpm, sequentially mix nano cerium oxide, leveling agent BYK-346, adipic dihydrazide, and 2 wt% aqueous hydroxyethyl cellulose solution in a mass ratio of 0.5:0.2:0.5:2 to obtain an additive; add the sanded slurry to the waterborne acrylic emulsion over 30 min, then add the additive and the pre-coated calcium ion resin. The mass ratio of the waterborne acrylic emulsion, sanded slurry, pre-coated calcium ion resin, and the additive is 50:30:5:2. Add deionized water to make the solid content 40%, stir evenly to obtain a waterborne paint; filter through a 200-mesh vibrating sieve; fill nitrogen in a sealed polyethylene barrel and store at below 30°C to obtain the waterborne paint for multi-material adhesion on the engine.

[0038] Example 2 As Figure 1 shown, a preparation method of a waterborne paint for multi-material adhesion on an engine includes the following steps: 1. Soak the sulfonic acid type cation exchange resin in deionized water for 24 h until fully swollen; load it into a glass column with a diameter-height ratio of 1:5, and pass through a 5% hydrochloric acid solution at a flow rate of 2 BV / h for 3 h; rinse with deionized water until the pH of the effluent is 5.5; vacuum filter to a moisture content of 50% to obtain a pretreated resin; add the pretreated resin and a 1.5 mol / L calcium chloride solution to a reaction kettle in a mass ratio of 1:6, heat up to 40°C, stir at 200 rpm for 6 h, and wash with deionized water until no precipitation is detected by 0.1 mol / L silver nitrate to obtain a calcium ion-loaded resin; mix the calcium ion-loaded resin and a 1 wt% polyvinylpyrrolidone solution in a mass ratio of 8:1; granulate through an extrusion spheronizer at a rotation speed of 800 rpm with a pore diameter of 0.8 mm; sequentially pass through a 40-mesh sieve and a 60-mesh sieve, screen the particles between 40 and 60 meshes, and vacuum dry to a moisture content < 3% to obtain a pre-coated calcium ion resin; 2. Mix butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate and water, and pre-emulsify them at a high speed of 2000 rpm for 30 min to form a monomer emulsion; heat the 10 g / L ammonium persulfate solution to 75 °C, and slowly dropwise add the monomer emulsion. The mass ratio of butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, water and ammonium persulfate solution is 50:35:4:1.5:30:80. Control the temperature below 80 °C and finish dropping in 3 h. After holding the temperature for 1 h, cool it down to 40 °C and filter it through a 200-mesh sieve to obtain an aqueous acrylic emulsion; 3. Under stirring at 300 rpm, mix deionized water, sodium polyacrylate (molecular weight 7000 g / mol), polydimethylsiloxane (viscosity 280 cSt), adjust the pH to 9.0 with 2-amino-2-methyl-1-propanol, and stir until completely dissolved. Then add zinc phosphate and nano-magnesium silicate; after stirring, pass through a 300-mesh sieve and carry out the grinding treatment. During the grinding process, control the temperature with a water-cooled jacket to maintain the temperature < 40 °C. After grinding, pass through an 800-mesh sieve to obtain a sanding slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate and nano-magnesium silicate is 50:1.0:0.3:8:5; 4. Under stirring at 600 rpm, mix nano-cerium oxide, leveling agent BYK-346, adipic dihydrazide and 2 wt% aqueous solution of hydroxyethyl cellulose in a mass ratio of 1:0.5:1.0:3 in sequence to obtain an additive; add the sanding slurry to the aqueous acrylic emulsion, which takes 45 min. Add the additive and pre-coated calcium ion resin. The mass ratio of the aqueous acrylic emulsion, sanding slurry, pre-coated calcium ion resin and the additive is 55:44:8:5. Add deionized water to make the solid content 45%, stir evenly to obtain an aqueous paint; filter it through a 200-mesh vibrating sieve; fill nitrogen in a closed polyethylene barrel and store it below 30 °C to obtain the aqueous paint for multi-material adhesion on the engine.

[0039] Example 3 As Figure 1 shown, a preparation method of an aqueous paint for multi-material adhesion on the engine includes the following steps: 1. Immerse the sulfonic acid type cation exchange resin in deionized water for 24 h until it is fully swollen; pack it into a glass column with a diameter-height ratio of 1:5, and pass through a 5% hydrochloric acid solution at a flow rate of 2 BV / h for 3 h; rinse with deionized water until the pH of the effluent is 6; perform vacuum filtration until the water content is 40% to obtain the pretreated resin; add the pretreated resin and a 1.5 mol / L calcium chloride solution to the reaction kettle in a mass ratio of 1:7, heat up to 40 °C, stir at 200 rpm for 6 h, and wash with deionized water until no precipitate is detected by 0.1 mol / L silver nitrate to obtain the calcium ion-loaded resin; mix the calcium ion-loaded resin and a 1 wt% polyvinylpyrrolidone solution in a mass ratio of 9:1; granulate through an extrusion spheronizer at a rotation speed of 800 rpm, with a pore diameter of 0.8 mm; pass through a 40-mesh sieve and a 60-mesh sieve in sequence, collect the particles between 40 and 60 meshes, and vacuum dry until the water content is <3% to obtain the pre-coated calcium ion resin; 2. Mix butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate and water, and perform high-speed shearing pre-emulsification at 2000 rpm for 30 min to form a monomer emulsion; heat the 10 g / L ammonium persulfate solution to 75 °C, and slowly drop the monomer emulsion. The mass ratio of butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, water and ammonium persulfate solution is 50:35:4:1.5:30:80. Control the temperature below 80 °C and finish dropping in 3 h. After keeping warm for 1 h, cool down to 40 °C and filter through a 200-mesh sieve to obtain the waterborne acrylic emulsion; 3. Under stirring at 300 rpm, mix deionized water, sodium polyacrylate (molecular weight 7500 g / mol), polydimethylsiloxane (viscosity 290 cSt), adjust the pH to 9.0 with 2-amino-2-methyl-1-propanol, stir until completely dissolved, and then add zinc phosphate and nano magnesium silicate; after stirring, pass through a 300-mesh sieve and perform the grinding treatment. During the grinding process, control the temperature with a water-cooled jacket to maintain the temperature <40 °C. After grinding, pass through an 800-mesh sieve to obtain the sanding slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate and nano magnesium silicate is 50:0.8:0.2:7:4; 4. Under stirring at 600 rpm, mix nano cerium oxide, leveling agent BYK-346, adipic dihydrazide and a 2 wt% aqueous solution of hydroxyethyl cellulose in a mass ratio of 0.8:0.3:0.8:2.5 in sequence to obtain an additive; add the sanding slurry to the waterborne acrylic emulsion in 40 min, add the additive and the pre-coated calcium ion resin, stir evenly, and add deionized water to make up to a solid content of 45% to obtain the waterborne paint; the mass ratio of the waterborne acrylic emulsion, the sanding slurry, the pre-coated calcium ion resin and the additive is 53:40:7:4; filter through a 200-mesh vibrating sieve; fill nitrogen in a sealed polyethylene bucket and store it below 30 °C to obtain the waterborne paint for multi-material adhesion on the engine.

[0040] Example 4 As Figure 1 shown, a preparation method of an aqueous paint for multi-material adhesion of an engine includes the following steps: 1. Immerse the sulfonic acid type cation exchange resin in deionized water for 24 h until fully swollen; load it into a glass column with a diameter-height ratio of 1:5, and pass through a 5% hydrochloric acid solution at a flow rate of 2 BV / h for 3 h; rinse with deionized water until the pH of the effluent is 6; perform vacuum filtration until the water content is 40% to obtain the pretreated resin; add the pretreated resin and a 1.5 mol / L calcium chloride solution to the reaction kettle at a mass ratio of 1:7, heat up to 40°C, stir at 200 rpm for 6 h, wash with deionized water until no precipitate is detected by 0.1 mol / L silver nitrate to obtain the calcium ion-loaded resin; mix the calcium ion-loaded resin and a 1 wt% polyvinylpyrrolidone solution at a mass ratio of 9:1; granulate through an extrusion spheronizer at a rotation speed of 800 rpm, with a pore diameter of 0.8 mm; pass through a 40-mesh sieve, and perform vacuum drying until the water content is <3% to obtain the pre-coated calcium ion resin; 2. Mix butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate and water, and perform high-speed shearing pre-emulsification at 2000 rpm for 30 min to form a monomer emulsion; heat the 10 g / L ammonium persulfate solution to 75°C, and slowly dropwise add the monomer emulsion. The mass ratio of butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, water and ammonium persulfate solution is 50:35:4:1.5:30:80, control the temperature below 80°C, and finish dropping in 3 h. After holding the temperature for 1 h, cool down to 40°C and filter through a 200-mesh sieve to obtain the aqueous acrylic emulsion; 3. Mix deionized water, sodium polyacrylate (molecular weight 7500 g / mol), polydimethylsiloxane (viscosity 290 cSt) under stirring at 300 rpm, adjust the pH to 9.0 with 2-amino-2-methyl-1-propanol, stir until completely dissolved, and then add zinc phosphate and nano magnesium silicate; after stirring, pass through a 300-mesh sieve, and then perform the grinding treatment. Control the temperature with a water-cooled jacket during the grinding process to maintain the temperature <40°C. After grinding, pass through an 800-mesh sieve to obtain the sanding slurry; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate and nano magnesium silicate is 50:0.7:0.2:6:4; Mix nanoceria, leveling agent BYK-346, adipic dihydrazide, and 2 wt% aqueous solution of hydroxyethyl cellulose in sequence at a mass ratio of 0.7:0.4:0.7:2.5 under stirring at 4,600 rpm to obtain an additive; add the sanding slurry to the aqueous acrylic emulsion over 35 min, then add the additive and pre-coated calcium ion resin, stir evenly, and add deionized water to make the solid content 45% to obtain an aqueous paint; the mass ratio of the aqueous acrylic emulsion, sanding slurry, pre-coated calcium ion resin, and the additive is 53:38:6:4; filter through a 200-mesh vibrating sieve; store in a sealed polyethylene barrel filled with nitrogen at a temperature below 30 °C to obtain the aqueous paint for multi-material adhesion on engines.

[0041] Comparative Example 1 A preparation method of an aqueous paint for multi-material adhesion on engines, with the implementation steps and parameters being the same as those in Example 3, except that the pre-coated calcium ion resin is not added.

[0042] Comparative Example 2 A preparation method of an aqueous paint for multi-material adhesion on engines, with the implementation steps and parameters being the same as those in Example 3, except that polyvinylpyrrolidone granulation is not added during the preparation of the pre-coated calcium ion resin, and it is used directly after drying.

[0043] Comparative Example 3 A preparation method of an aqueous paint for multi-material adhesion on engines, with the implementation steps and parameters being the same as those in Example 3, except that nanosilicate magnesium is not added.

[0044] Performance test: Use low-carbon steel as the substrate, coat the aqueous paints for multi-material adhesion on engines prepared in Examples 1 - 4 and Comparative Examples 1 - 3 on the surface of the metal substrate, and cure at 80 °C for 2 h to obtain a coating for testing.

[0045] Salt spray resistance test: According to GB / T1771, conduct a salt spray test on the coatings of Examples 1 - 4 and Comparative Examples 1 - 3 in a 50 g / L NaCl salt spray chamber at 35 °C. The test results are shown in Table 1.

[0046] Electrochemical impedance test: In a 3.5% NaCl solution, test the impedance value |Z| of the coatings before and after the salt spray test. The results are shown in Table 1.

[0047] Adhesion test: According to ASTM D3359, test the coatings of Examples 1 - 4 and Comparative Examples 1 - 3 using the cross-cut method. Draw 1 mm × 1 mm grids on the coating surface, stick the tape, and quickly peel it off. Observe the proportion of the coating peeling area and score from 0 - 5 levels. Level 0 means no peeling, and the higher the level, the worse the adhesion. The results are shown in Table 1.

[0048] Scratch self-healing effect test: Scratches with a width of 100 μm were made on the surface of the coating. The coatings of Examples 1-4 and Comparative Examples 1-3 were immersed in 3.5% NaCl solution, and the rusting conditions in the scratched areas were observed regularly. The results are shown in Table 1.

[0049] Table 1 Test results of the properties of the waterborne paint coatings

[0050] As can be seen from Table 1, the salt spray resistance time of Examples 1-4 was 343-353 h, which was significantly better than that of the Comparative Examples (78-123 h); the initial impedance value of the Examples reached 10 8 Ω·cm 2 , and it still remained 10 7 -10 8 Ω·cm 2 after salt spray; the impedance value of the Comparative Examples was low and decayed severely, dropping to 10 5 -10 6 Ω·cm 2 after salt spray; the adhesion of the Examples was grade 0-1 (no peeling), while the adhesion of the Comparative Examples was poor (grade 2-4) due to incomplete formulations; the scratch repair rate of the Examples was ≥92%, and the repair rate of the Comparative Examples was 27% - 58%.

[0051] The formulation of Comparative Example 1 did not contain pre-coated calcium ion resin and only relied on the leveling agent BYK-346 and hydroxyethyl cellulose. Its salt spray resistance was 78 h, which was significantly lower than that of the Examples. The impedance value decayed to 8.5×10 5 Ω·cm 2 after salt spray, far lower than that of the Examples. The scratch self-healing effect was only 35% (≥92% for the Examples). The pre-coated calcium ion resin is the core component for self-healing. It triggers the release of Ca + through H 2+ , and reacts with zinc phosphate to form a hydroxyapatite repair layer. When this component is missing, the coating cannot respond to the corrosive environment for repair, resulting in rapid rusting at the scratched areas. Although hydroxyethyl cellulose can thicken, excessive use destroys the compactness of the coating, and there is no resin filler to fill the defects, making it easier for corrosive media to penetrate to the substrate. Without the Ca 2+ release mechanism, a dynamic barrier layer cannot be formed, and the impedance value drops significantly.

[0052] In Comparative Example 2, polyvinylpyrrolidone was not added during the preparation of the pre-coated calcium ion resin for granulation, and it was used directly after drying. Its salt spray resistance was 123 h, which was better than that of Comparative Example 1 but far lower than that of the Examples. The self-healing effect was 55% (≥92% for the Examples), and the impedance value was only 1.2×10 6 Ω·cm 2. Polyvinylpyrrolidone acts as a binder during the granulation process, ensuring uniform resin particle size and complete surface coating. Ungranulated resin may cause uneven dispersion due to agglomeration or rough surface, resulting in partial Ca 2+ premature release or being blocked by the coating layer, reducing the repair efficiency; the irregular resin structure affects the H + penetration rate, leading to delayed or insufficient Ca 2+ release, and the inability to form a repair layer in a timely manner; the weak binding force between the ungranulated resin and the substrate results in poor coating adhesion (grade 2), which is inferior to that of the example (grade 0).

[0053] Comparative Example 3: Without adding nano-magnesium silicate, the salt spray resistance is poor, and the salt spray resistance time is only 102 h. The impedance value after salt spray is only 5.0×10 5 Ω·cm². The self-healing effect of the scratch is only 20%, and the adhesion is grade 4 (severe peeling). Nano-magnesium silicate can fill the micropores of the coating, and the colloidal silica generated by its hydrolysis can block the diffusion path of the corrosive medium. Without adding it, the density of the coating decreases, and the corrosive medium quickly penetrates to the substrate; zinc phosphate provides anodic protection, but it is prone to form micropore defects when used alone; the absence of nano-magnesium silicate leads to the inability to form a hydroxyapatite / silica composite repair layer, and the dynamic barrier effect is lost; nano-magnesium silicate can enhance the toughness of the coating, and its absence results in poor adhesion (grade 4), and the coating is easy to peel off.

[0054] Adhesion test on different material parts of the engine: Low-carbon steel SAE1010, 6061 aluminum alloy, gray cast iron HT250, copper C11000, nylon 6, ABS+PC, and two-component epoxy resin primer were used as substrates respectively. The waterborne paint for multi-material adhesion on the engine prepared in Examples 1-4 was coated on the surface of the above substrates. After curing at 80 °C for 2 h, the coating was obtained. The coating was tested according to ASTM D3359. Using the cross-cut method, a 1 mm×1 mm grid was drawn on the surface of the coating, and the tape was pasted and quickly peeled off. The proportion of the coating peeling area was observed, and it was scored from 0 to 5 levels. Level 0 means no peeling, and the higher the level, the worse the adhesion. The results are shown in Table 2.

[0055] Table 2 Adhesion test results of different material parts on the engine

[0056] As can be seen from Table 2, after the waterborne paints prepared in Examples 1-4 of the present invention are coated on substrates of different materials at different parts of the engine, the adhesion of the formed coatings is 0-1 level and there is basically no peeling. This is because when metal materials such as low-carbon steel SAE1010, 6061 aluminum alloy, gray cast iron HT250, and copper C11000 are used as substrates, the carboxyl groups of the waterborne acrylic emulsion form hydrogen bonds or chemical bonds on the metal surface, and the zinc phosphate in the sanding slurry enhances the binding force by passivating the metal surface; nano-magnesium silicate fills the micropores, reduces interface defects, and the pre-coated calcium ion resin generates a hydroxyapatite repair layer after corrosion is triggered, strengthening the interface bonding between the coating and the metal. On the nylon 6 and ABS+PC substrates, the additive BYK-346 reduces the surface tension of the coating, improves the wettability to low surface energy plastics, and hydroxyethyl cellulose adjusts the rheology to ensure that the coating evenly covers the substrate microstructure; the flexible chain segments of the acrylic emulsion adapt to the thermal expansion coefficient of the plastic, avoiding peeling caused by stress differences. The high surface activity of the two-component epoxy resin primer enables it to form chemical cross-links with the acrylic groups of the waterborne paint, enhancing the interlayer adhesion; and the nano-magnesium silicate in the sanding slurry fills the microscopic pores of the epoxy coating, forming a dense transition layer and enhancing the adhesion.

[0057] The above test data show that the waterborne paint prepared by the present invention has high adhesion ability to different materials on the engine and is not easy to peel off, and can be used as the overall anti-corrosion paint for the engine.

[0058] The above results show and describe the basic principles, main features and advantages of the present application.

[0059] Those skilled in the art of this industry should understand that the present application is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present application. Without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements all fall within the scope of the present application claimed. The scope of protection claimed by the present application is defined by the equivalents of the appended claims.

Claims

1. An aqueous paint for multi-material adhesion of an engine, characterized in that, Comprising: An aqueous acrylic emulsion, a sanding slurry, a pre-coated calcium ion resin, and an auxiliary agent; The sanding slurry contains zinc phosphate and nano magnesium silicate; The pre-coated calcium ion resin is obtained by loading calcium ions on a sulfonic acid type cation exchange resin and then treating it with polyvinylpyrrolidone.

2. The waterborne paint for multi-material adhesion of an engine according to claim 1, wherein, The sulfonic acid type cation exchange resin is of the H + type, and the exchange capacity is ≥4.8 mmol / g; the particle size of the nano magnesium silicate is 20 - 50 nm.

3. The waterborne paint for multi-material adhesion of an engine according to claim 1, wherein The mass ratio of the aqueous acrylic emulsion, the sanding slurry, the pre-coated calcium ion resin, and the auxiliary agent is (50 - 55):(30 - 44):(5 - 8):(2 - 5).

4. The waterborne paint for multi-material adhesion of an engine according to claim 1, wherein The auxiliary agent includes nano cerium oxide, leveling agent BYK-346, adipic dihydrazide, and hydroxyethyl cellulose aqueous solution with a mass ratio of (0.5 - 1):(0.2 - 0.5):(0.5 - 1.0):(2 - 3); the particle size of the nano cerium oxide is 20 - 50 nm.

5. The preparation method of an aqueous paint for multi-material adhesion on an engine according to any one of claims 1 to 4, characterized in that, Including the following steps: S1. Pretreat the cation exchange resin, then carry out calcium ion loading, and then add polyvinylpyrrolidone for mixing and granulation, and obtain the pre-coated calcium ion resin after drying; S2. Mix zinc phosphate and nano magnesium silicate and then carry out grinding treatment to obtain the sanding slurry; S3. After adding the sanding slurry to the aqueous acrylic emulsion, add the auxiliary agent and the pre-coated calcium ion resin, stir evenly, and add deionized water to make the solid content 40% - 45% to obtain the aqueous paint; after filtering through a vibrating screen and storing under nitrogen, obtain the aqueous paint for multi-material adhesion of the engine.

6. The preparation method of an aqueous paint for multi-material adhesion of an engine according to claim 5, wherein, The preparation method of the pre-coated calcium ion resin in S1 is specifically: Soak the cation exchange resin in deionized water until it swells, load it into a glass column, add hydrochloric acid solution, and rinse until the pH of the effluent is within the range of 5 - 6, and then vacuum filter until the moisture content is 40% - 50% to obtain the pretreated resin; React the pretreated resin with calcium chloride solution at a mass ratio of 1:(6 - 8), and wash until there is no residual chloride ion to obtain the calcium ion loaded resin; Mix the calcium ion loaded resin and polyvinylpyrrolidone solution at a mass ratio of (8 - 10):1, granulate, screen 40 - 60 mesh particles, and vacuum dry until the moisture content < 3% to obtain the pre-coated calcium ion resin.

7. The preparation method of an aqueous paint for multi-material adhesion of an engine according to claim 5, characterized in that The preparation of the sanding slurry in S2 further includes: mixing deionized water, sodium polyacrylate, polydimethylsiloxane, adjusting the pH to 8.5 - 9.0, and then adding zinc phosphate and nano magnesium silicate; stir and then pass through a 300-mesh sieve, carry out the grinding treatment, and obtain the sanding slurry after passing through an 800-mesh sieve; the mass ratio of deionized water, sodium polyacrylate, polydimethylsiloxane, zinc phosphate, and nano magnesium silicate is 50:(0.5 - 1.0):(0.1 - 0.3):(5 - 8):(3 - 5).

8. The preparation method of an aqueous paint for multi-material adhesion on an engine according to claim 7, characterized in that, The molecular weight of the sodium polyacrylate is 7000 - 8000 g / mol; the viscosity of the polydimethylsiloxane is 280 - 300 cSt.

9. The preparation method of an aqueous paint for multi-material adhesion on an engine according to claim 5, characterized in that, The preparation method of the aqueous acrylic emulsion in S3 is: mix butyl acrylate, methyl methacrylate, acrylic acid, sodium dodecyl sulfate, and water, and shear and pre-emulsify to form a monomer emulsion; dropwise add the monomer emulsion to an ammonium persulfate solution, and filter through a sieve to obtain the aqueous acrylic emulsion.

10. The preparation method of an aqueous paint for multi-material adhesion of an engine according to claim 5, characterized in that, After adding deionized water in S3, complete filtration and nitrogen storage within 30 minutes, and the storage temperature ≤ 30°C.

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