Highly durable yellow car paint and method for preparing the same

Abstract

The application relates to the field of coatings, and discloses a high-durability yellow car paint and a preparation method thereof. The yellow car paint comprises 60-70 parts by weight of a base resin, 25-30 parts by weight of functionalized bismuth vanadate, 0.5-1.5 parts by weight of a dispersing agent, 0.3-0.6 parts by weight of a leveling agent, 1.5-2.5 parts by weight of a silicone modifier and 2.5-3.5 parts by weight of an anti-wear agent. The base resin comprises a hydroxyl acrylate resin and an HDI trimer curing agent, and the functionalized bismuth vanadate has a titanium dioxide-silicon dioxide coating layer and is subjected to plasma treatment. The car paint of the application adopts bismuth vanadate subjected to sol-gel coating and plasma treatment, and an inorganic-organic hybrid coating layer is formed on the surface of the bismuth vanadate. The inorganic-organic hybrid coating layer can shield the active sites on the surface of the particles, inhibit the reaction between the bismuth vanadate and the resin base, the resin base has high chemical bond energy and is not easy to be damaged by ultraviolet light, and the resin base has excellent hydrolysis resistance and chemical corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of coatings, specifically to a high-durability yellow automotive paint and its preparation method. Background Technology

[0002] Traditional automotive yellow pigments primarily rely on inorganic pigment systems containing heavy metals such as chromium and cadmium, including lead chromate (PbCrO4) and cadmium sulfide (CdS). While these pigments offer excellent hiding power, color saturation, and weather resistance, meeting the stringent requirements for color durability in automotive coatings, their inherent environmental toxicity and health hazards are becoming increasingly prominent. With increasingly stringent environmental regulations, the use of these heavy metal-containing pigments in automotive paints is gradually being restricted or banned. Against this backdrop, bismuth vanadate (BiVO4), as a novel environmentally friendly inorganic yellow pigment, exhibits a vibrant yellow hue due to its unique monoclinic crystal structure and contains no toxic heavy metal elements, making it an important alternative to traditional yellow pigments.

[0003] Automotive coatings have high requirements for appearance, with stringent standards for color uniformity, gloss, surface smoothness, and purity. However, bismuth vanadate pigments still face many technical challenges in automotive coating applications. First, the surface of bismuth vanadate particles has a large number of active sites, which easily react with the resin matrix in the coating system, leading to problems such as increased viscosity and sedimentation during storage, seriously affecting the paint's application performance and batch stability. Second, pure-phase bismuth vanadate has a Mohs hardness of only 4-5, far below the 6 or higher hardness standard required for automotive paint, making the coating prone to scratches in actual use and failing to meet the durable appearance requirements of high-end automobiles. Furthermore, bismuth vanadate is susceptible to surface corrosion and lattice damage in acidic environments (such as acid rain) or organic solvents (such as gasoline and car wash liquid), resulting in defects such as fading and loss of gloss in the coating. Furthermore, prolonged exposure to ultraviolet radiation can cause bismuth vanadate to degrade the coating resin due to its intrinsic photocatalytic activity. This results in a ΔE color difference exceeding 3.0 and a gloss retention rate of less than 80% after 3000 hours of QUV aging testing, making it difficult to meet the stringent requirements of automotive exterior coatings for color durability and tolerance to extreme environments.

[0004] These technical bottlenecks severely limit the promotion and application of bismuth vanadate pigments in the field of high-end automotive coatings, and have become technical problems that urgently need to be solved. Summary of the Invention

[0005] In view of the above-mentioned problems in the existing technology, the main objective of the present invention is to provide a high-durability yellow car paint and its preparation method.

[0006] According to one aspect of the present invention, a high-durability yellow automotive paint is provided, comprising the following components by weight: 60-70 parts by weight of a base resin, 25-30 parts by weight of functionalized bismuth vanadate, 0.5-1.5 parts by weight of a dispersant, 0.3-0.6 parts by weight of a leveling agent, 1.5-2.5 parts by weight of an organosilicon modifier, and 2.5-3.5 parts by weight of an abrasion resistant agent, wherein the base resin is selected from a composite system comprising hydroxyl acrylic resin and HDI trimer curing agent, and the functionalized bismuth vanadate has a titanium dioxide-silica composite coating layer and is plasma treated.

[0007] According to one embodiment of the present invention, the mass ratio of hydroxyl acrylic resin and HDI trimer curing agent in the base resin is 5~6:4~5.

[0008] According to one embodiment of the present invention, the dispersant is selected from one or two of the following: polyurethane dispersants, acrylate dispersants, anionic surfactants, copolymers containing siloxane groups, and graphene-modified dispersants.

[0009] According to one embodiment of the present invention, the leveling agent is selected from one or two of the following: silicone leveling agents, fluorocarbon leveling agents, and acrylate leveling agents.

[0010] According to one embodiment of the present invention, the organosilicon modifier is selected from one or two of the following: reactive silanes, polysiloxane resins, organosilicon-acrylic hybrid resins, long-chain alkyl-modified silicone oils, and amino-modified silicone oils.

[0011] According to another aspect of the present invention, a method for preparing a high-durability yellow automotive paint is provided, the method being used to prepare the yellow automotive paint as described in any of the above embodiments and comprising the following steps:

[0012] Functionalized bismuth vanadate was prepared, wherein the functionalized bismuth vanadate has a titanium dioxide-silicon dioxide composite coating layer and is subjected to plasma treatment;

[0013] Hydroxy acrylic resin and HDI trimer curing agent are premixed in a set ratio to obtain the base resin;

[0014] The functionalized bismuth vanadate, dispersant, and leveling agent are added to the base resin in a set ratio and then mixed and ground.

[0015] The organosilicon modifier and wear-resistant agent are added to the base resin and ground and dispersed. After adjusting the viscosity, the mixture is filtered to obtain the yellow car paint.

[0016] According to one embodiment of the present invention, the preparation of functionalized bismuth vanadate includes the following steps:

[0017] Bismuth vanadate powder is dispersed in a solvent to form a first solution;

[0018] Add a mixed solution of tetrabutyl titanate and tetraethyl orthosilicate to the first solution and stir to react;

[0019] Adjust the pH of the reacted solution to 8-9 and continue the reaction;

[0020] The solution was subjected to solid-liquid separation, the solid was collected and then subjected to plasma treatment under nitrogen protection;

[0021] The plasma-treated solid was calcined to obtain functionalized bismuth vanadate.

[0022] According to one embodiment of the present invention, the tetrabutyl titanate and tetraethyl orthosilicate are added to the mixed solution in a molar ratio of 1:1 to 5 based on titanium and silicon, and the mixture is stirred at 55 to 75°C for 1.5 to 3 hours. After the pH of the solution is adjusted to 8 to 9, the reaction continues for 3.5 to 5.5 hours.

[0023] According to one embodiment of the present invention, the power used for plasma treatment is 300~400W, the time is 20~40min; the calcination temperature is 380~480℃, and the calcination time is 1~2.5h.

[0024] According to one embodiment of the present invention, the components for preparing the high-durability yellow car paint are mixed and ground until the particle size is ≤10μm and then the viscosity is adjusted.

[0025] Compared with the prior art, the high-durability yellow automotive paint and its preparation method of the present invention have at least one of the following beneficial effects:

[0026] (1) The high-durability yellow car paint of the present invention uses functionalized bismuth vanadate which is coated with sol-gel and then plasma treated to form an inert and dense inorganic-organic hybrid coating layer on the surface of bismuth vanadate particles. This coating layer can shield the active sites on the particle surface and inhibit the reaction between bismuth vanadate and the resin base in the coating system. Moreover, the functional groups introduced by the plasma treatment in the coating layer are conducive to forming strong hydrogen bonds or chemical bonds with the selected dispersant, optimizing the pigment dispersion performance and avoiding the sedimentation and stratification of bismuth vanadate. In addition, the inert and dense coating layer can prevent acidic substances, organic solvents and oxygen from corroding bismuth vanadate particles and improve the durability of pigments and coatings.

[0027] (2) The high-durability yellow car paint of the present invention uses a composite system including hydroxyl acrylic resin and HDI trimer curing agent as the base resin. Its chemical bond energy is high and it is not easily damaged by ultraviolet light. It has excellent hydrolysis resistance and chemical corrosion resistance. At the same time, HDI trimer has a regular six-membered ring structure. After cross-linking, it forms a dense and rigid polyurethane network. After film formation, it has high hardness, providing a high-hardness matrix for the coating. The wear-resistant agent is dispersed in the coating, which can better resist external friction and scratching force.

[0028] (3) The coating system of the present invention achieves the application of bismuth vanadate pigment in high-performance automotive coating system by synergistically optimizing the components and dosage of functionalized modified bismuth vanadate, dispersant, high crosslinking density resin, hard filler and organosilicon modifier, thereby improving the mechanical properties, chemical stability and long-term weather resistance of the coating. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A flowchart illustrating a method for preparing a high-durability yellow automotive paint according to an embodiment of the present invention is shown;

[0031] Figure 2 A flowchart illustrating a method for preparing functionalized bismuth vanadate according to an embodiment of the present invention is shown. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0035] According to one aspect of the present invention, a high-durability yellow automotive paint is provided. The high-durability yellow automotive paint comprises the following components by weight: 60-70 parts by weight of a base resin, 25-30 parts by weight of functionalized bismuth vanadate, 0.5-1.5 parts by weight of a dispersant, 0.3-0.6 parts by weight of a leveling agent, 1.5-2.5 parts by weight of an organosilicon modifier, and 2.5-3.5 parts by weight of an abrasion resistant agent, wherein the base resin is selected from a composite system including hydroxyl acrylic resin and HDI trimer curing agent, and the functionalized bismuth vanadate has a titanium dioxide-silica composite coating layer and has been plasma treated.

[0036] The core design of the coating system of this invention lies in the formation of a stable, tough, and durable composite coating system centered on functionalized bismuth vanadate pigments, through the synergistic effect of a specific dispersion stabilization system, a reinforced resin matrix, and multi-level wear-resistant and protective additives.

[0037] The base resin is selected from a composite system including hydroxyl acrylic resin and HDI trimer curing agent. HDI trimer has a regular six-membered ring structure, which, after crosslinking, forms a dense and rigid polyurethane network, providing a high-hardness basic framework for the coating. Furthermore, the aliphatic polyurethane coating formed by hydroxyl acrylic resin and HDI trimer has high chemical bond energy, is not easily damaged by ultraviolet light, and exhibits excellent hydrolysis resistance and chemical corrosion resistance, providing effective protection for the coating after application. In some embodiments of the present invention, the mass ratio of hydroxyl acrylic resin to HDI trimer curing agent in the base resin is 5~6:4~5.

[0038] Functionalized bismuth vanadate features a titanium dioxide-silica composite coating and undergoes plasma treatment. Through sol-gel coating combined with plasma treatment, an inert and dense inorganic-organic hybrid coating layer is formed on the surface of bismuth vanadate particles. This layer shields the active sites on the particle surface, inhibiting the reaction between bismuth vanadate and the resin matrix in the coating system. Furthermore, the functional groups introduced into the coating layer by plasma treatment facilitate the formation of strong hydrogen bonds or chemical bonds with the selected dispersant, optimizing pigment dispersion performance and preventing bismuth vanadate sedimentation and stratification. In addition, the inert and dense coating layer prevents acidic substances, organic solvents, and oxygen from corroding the bismuth vanadate particles, improving the durability of pigments and coatings.

[0039] Dispersants are used to improve the suspension properties of bismuth vanadate in coating systems. In some embodiments of the present invention, the dispersant is selected from one or two of the following: polyurethane dispersants, acrylate dispersants, anionic surfactants, copolymers containing siloxane groups, and graphene-modified dispersants. Further, the dispersant is selected from one or two of the following: polyurethanes, such as BYK-161 and BYK-2155; acrylates, such as EFKA-4585 and Disperbyk-190; modified polyesteramines, such as Solsperse 32000 (a superdispersant, especially suitable for nanoscale pigments); anionic surfactants, such as sodium polycarboxylate salts, specifically Tego Dispers 750W; phosphate salts, specifically BYK-110; special functional dispersants, such as copolymers containing siloxane groups, specifically BYK-2015; and graphene-modified dispersants that can improve conductivity and abrasion resistance. Preferably, two of these are used in a mass ratio of 1:1 to 3. Further preferred options include two of the following: polyurethane (BYK-161), modified polyesteramine (Solsperse 32000), anionic surfactant, and copolymers containing siloxane groups. The polyurethane / modified polyesteramine dispersant can form strong hydrogen bonds with functionalized bismuth vanadate, preventing bismuth vanadate from settling and separating. The copolymers containing siloxane groups can act as lubricants at the pigment-resin interface. The introduction of anionic surfactants can increase the zeta potential of the pigment surface and stabilize the dispersion system through electrostatic repulsion.

[0040] In some embodiments of the present invention, the leveling agent is selected from one or two of the following: silicone leveling agents, fluorocarbon leveling agents, and acrylate leveling agents. Further, the leveling agent is selected from one or two of the following: silicone, such as polyether-modified polydimethylsiloxanes, such as BYK-333 and Tego Glide 410; polyester-modified siloxanes, such as BYK-371, which can achieve both leveling and defoaming; fluorocarbons, such as perfluoropolyethers, such as Capstone FS-63; fluorinated acrylates, such as EFKA-3777; acrylates, such as low molecular weight acrylic copolymers, such as BYK-354; and self-crosslinking leveling agents, such as Perenol F40. Preferably, two of these are used in a mass ratio of 1:1 to 3.

[0041] In some embodiments of the present invention, the organosilicon modifier is selected from one or two of the following: reactive silanes, polysiloxane resins, organosilicon-acrylic hybrid resins, long-chain alkyl-modified silicone oils, and amino-modified silicone oils. Further, the organosilicon modifier is selected from one or two of the following: reactive silanes, such as epoxy silane KH-560, amino silane KH-550, and methacryloxy silane KH-570; polysiloxane resins, such as methylphenyl silicone resin Dow Corning 804 and organosilicon-acrylic hybrid resin Tego Rad 2100; and functional silicone oils, such as long-chain alkyl-modified silicone oils that enhance hydrophobicity and amino-modified silicone oils that improve adhesion. Preferably, two of these modifiers are used in a mass ratio of 1:1 to 3.

[0042] In some embodiments of the present invention, the wear-resistant agent is nano-alumina or nano-zirconia. The fine-sized alumina and zirconia particles possess extremely high hardness and, when uniformly dispersed in the coating, can effectively withstand external friction and scratching forces.

[0043] In the coating system of this invention, reactive silanes and other organosilicon modifiers can react with the resin and pigment surfaces during curing to form strong Si-OC or Si-OM bonds, enhancing interfacial resistance to media. Furthermore, organosilicon leveling agents (such as BYK-333) and functional silicone oils migrating to the coating surface significantly reduce the coating surface energy, making it difficult for acids and solvents to wet and adhere, resulting in excellent corrosion resistance. Through optimization of the coating components, after 3000 hours of QUV aging, the color difference can be stably controlled within ΔE≤1.5, gloss retention >85%, pencil hardness ≥3H, scratch resistance (gloss retention ≥90% after 100 car washes), gasoline resistance (no change after 72 hours of immersion), and alcohol resistance (no change after 100 wipes), far exceeding the performance of traditional bismuth vanadate coatings. The paint of this invention not only has vibrant and long-lasting colors but also excellent comprehensive performance, fully meeting the requirements of high-end automotive coatings.

[0044] The present invention also provides a method for preparing the high-durability yellow automotive paint described in the above embodiments. For example... Figure 1 As shown, the method for preparing high-durability yellow automotive paint according to an embodiment of the present invention generally includes the following steps:

[0045] Step S100: Prepare functionalized bismuth vanadate, which has a titanium dioxide-silica composite coating layer and is subjected to plasma treatment;

[0046] Step S200: Premix hydroxyl acrylic resin and HDI trimer curing agent in a set ratio to obtain base resin;

[0047] Step S300: Add functionalized bismuth vanadate, dispersant, and leveling agent to the base resin in a set ratio, and mix and grind.

[0048] Step S400: Add the organosilicon modifier and wear-resistant agent to the base resin for grinding and dispersion, adjust the viscosity and filter to obtain yellow car paint.

[0049] The following provides a detailed example of each step.

[0050] In step S100, functionalized bismuth vanadate is prepared, which has a titanium dioxide-silica composite coating layer and is subjected to plasma treatment.

[0051] Untreated bismuth vanadate particles have high surface energy and numerous active sites, making them prone to uncontrolled adsorption and reaction with polar groups in resins, forming an unstable three-dimensional network structure that leads to a sharp increase in system viscosity. Simultaneously, bismuth vanadate particles are prone to sedimentation and stratification due to density differences and interparticle forces.

[0052] To address the aforementioned issues, surface modification of bismuth vanadate is necessary. Preferably, a titanium dioxide-silica composite coating layer is formed on the bismuth vanadate surface using a sol-gel method. This method produces a dense coating layer, which is then further processed by plasma treatment to form a dense, inert inorganic-organic hybrid coating layer on the bismuth vanadate surface. This coating layer not only physically shields the active sites on the particle surface, but its surface-modified specific functional groups also provide an ideal interface for the selective binding of subsequent dispersants.

[0053] like Figure 2 As shown, the preparation of functionalized bismuth vanadate generally includes the following steps:

[0054] Step S110: Disperse bismuth vanadate powder in a solvent to form a first solution;

[0055] Step S120: Add a mixed solution of tetrabutyl titanate and tetraethyl orthosilicate to the first solution and stir to react;

[0056] Step S130: Adjust the pH of the reacted solution to 8-9 and continue the reaction;

[0057] Step S140: The solution is subjected to solid-liquid separation, the solid is collected and subjected to plasma treatment under nitrogen protection;

[0058] Step S150: Calcining the plasma-treated solid to obtain functionalized bismuth vanadate.

[0059] In step S110, bismuth vanadate powder is dispersed in a solvent to form a first solution. Preferably, the bismuth vanadate powder has an average particle size of 0.5–1 μm, and anhydrous ethanol can be used as the solvent. The mass fraction of bismuth vanadate in the prepared first solution is 5%–20%. After the bismuth vanadate powder is placed in the solvent, it is ultrasonically treated for 30–60 min to ensure thorough dispersion.

[0060] In step S120, a mixed solution of tetrabutyl titanate and tetraethyl orthosilicate is added to the first solution, and the mixture is stirred to react under a nitrogen protective atmosphere. The molar ratio of tetrabutyl titanate to tetraethyl orthosilicate, based on titanium to silicon, is 1:1~5, and the reaction is carried out at 55~75°C for 1.5~3 hours. The molar ratio of bismuth vanadate to titanium ions is 100:3~5. In this step, the temperature and stirring time are controlled to ensure complete hydrolysis of tetrabutyl titanate and tetraethyl orthosilicate.

[0061] In step S130, an alkaline solution (e.g., ammonia) is slowly added dropwise to the first solution to adjust the pH to 8-9, and the reaction continues for 3.5-5.5 hours to form a TiO2-SiO2 composite sol coating layer. Adjusting the pH to 8-9 makes the solution alkaline, providing sufficient hydroxide ions to recombine with titanium and silicon ions to form a composite sol.

[0062] In step S140, the solution undergoes solid-liquid separation, the solid is collected, and plasma treatment is performed under nitrogen protection. In some embodiments, the power used for plasma treatment is 300-400W, and the time is 20-40 minutes. Plasma treatment can enhance the density of the coating layer.

[0063] In step S150, the plasma-treated solid is calcined to obtain functionalized bismuth vanadate. In some embodiments, the calcination temperature is 380~480℃ and the calcination time is 1~2.5h.

[0064] The remaining steps of the preparation method for high-durability yellow automotive paint will now be described.

[0065] In step S200, hydroxyl acrylic resin and HDI trimer curing agent are premixed in a set ratio to obtain a base resin. In some embodiments, the mass ratio of hydroxyl acrylic resin to HDI trimer curing agent is 5~6:4~5.

[0066] In step S300, functionalized bismuth vanadate, dispersant, and leveling agent are added to the base resin in a set ratio and then mixed and ground.

[0067] In step S400, the organosilicon modifier and wear-resistant agent are added to the base resin and ground and dispersed until the particle size is ≤10μm. After adjusting the viscosity, the mixture is filtered to obtain yellow car paint.

[0068] The high-durability yellow automotive paint can be applied and cured using the following process: After conventional pretreatment of the substrate, a primer is applied; the paint prepared according to the above method is then applied, with the wet film thickness controlled at 40-55 μm; gradient temperature curing is used: 70-80℃ for 20-30 min, 100-120℃ for 30-45 min, and 150-160℃ for 20-30 min. The initial 70-80℃ stage allows for gradual solvent evaporation and sufficient migration of the leveling agent, ensuring a mirror-like finish free of orange peel and pinholes. The 100-120℃ stage allows for bulk cross-linking of the resin while it is in a rubbery state, fully relaxing the internal stress caused by solvent evaporation, thermal shrinkage, and the difference in pigment / resin expansion coefficients. This avoids microcracks and decreased adhesion due to stress concentration, and is the core guarantee for achieving a cross-cut adhesion rating of 0. The 150-160℃ high-temperature stage not only ensures the complete consumption of residual reactive groups, maximizing the density of the cross-linked network to achieve optimal hardness and chemical resistance, but also promotes the formation of stronger Si-OC / M covalent bonds between the silicone modifier and the resin / pigment, reinforcing the interface. Simultaneously, this temperature is slightly higher than the baking temperature commonly used in automotive coatings, providing the coating with additional thermal stability reserves.

[0069] The method of the present invention will be further described and illustrated below with reference to embodiments. The coating and curing operations in the following embodiments are as described above.

[0070] Example 1

[0071] Preparation of functionalized bismuth vanadate: 1 kg of bismuth vanadate powder (D50 = 0.8 μm) was added to 6 L of anhydrous ethanol to prepare a suspension with a mass fraction of 17%. The suspension was ultrasonically treated for 50 min to ensure full dispersion. Under nitrogen protection, a mixed solution of tetrabutyl titanate (0.15 mol) and tetraethyl orthosilicate (0.45 mol) (molar ratio 1:3) was added, and the mixture was heated to 65 °C and stirred for 2.5 h. Ammonia water with a mass fraction of 10% was added dropwise at a rate of 2 mL / min using a peristaltic pump to adjust the pH to 8.8 ± 0.2, and the reaction was continued for 4.5 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and then placed in a plasma reactor and treated at 350 W power under a nitrogen atmosphere for 35 min. The treated powder was placed in a muffle furnace and heated to 450 °C at a rate of 5 °C / min and held for 2 h to obtain functionalized bismuth vanadate with a dense TiO2-SiO2 composite layer on the surface.

[0072] Preparation of high-durability yellow automotive paint: Hydroxyacrylate resin (OH value 120 mg KOH / g) and HDI trimer (NCO content 21.6%) were premixed at a mass ratio of 55:45 to obtain the base resin. 65 parts by weight of the base resin were taken, and 28 parts by weight of functionalized bismuth vanadate, 1.2 parts by weight of a composite dispersant (BYK-2155: Solsperse 32000 = 2:1), and 0.5 parts by weight of a leveling agent (BYK-333: Tego Glide 410 = 1:1) were added and mixed and ground. Add 2.2 parts by weight of organosilicon modifier (KH-560: Dow Corning 804 = 3:1) and 3.2 parts by weight of nano-alumina (γ-Al2O3, particle size 50nm), grind to fineness ≤8μm using a sand mill, add an appropriate amount of propylene glycol methyl ether acetate to adjust the viscosity to 85±5s (Ford-4 cup), filter with a 200-mesh filter to obtain a high-durability yellow car paint.

[0073] The prepared high-durability yellow automotive paint was electrostatically sprayed onto Q235 steel sheet, and its performance was tested. The test results are as follows:

[0074] Initial optical properties: 60° gloss 98, chromaticity L=92.3 / a=-1.5 / b=93.8;

[0075] Mechanical properties: Pencil hardness 4H, cross-cut adhesion grade 0;

[0076] Weather resistance: After 3000 hours of QUV aging, ΔE=1.1, and gloss retention rate is 95%;

[0077] Chemical resistance: No change after soaking in 5% H2SO4 for 72 hours or 5% NaOH for 72 hours;

[0078] Salt spray resistance: rust width at scratches ≤ 0.5 mm after 1000 hours.

[0079] Example 2

[0080] Preparation of functionalized bismuth vanadate: 1.2 kg of bismuth vanadate powder (D50 = 0.7 μm) was added to 6 L of anhydrous ethanol to prepare a 20% (w / w) suspension. The suspension was sonicated for 60 min to ensure complete dispersion. Under nitrogen protection, a mixed solution of tetrabutyl titanate (0.12 mol) and tetraethyl orthosilicate (0.60 mol) (molar ratio 1:5) was slowly added, and the mixture was heated to 75 °C and stirred for 3 h. A 15% (w / w) ammonia solution was added dropwise at a rate of 1.5 mL / min using a precise pH control system to adjust the pH. The pH was adjusted to 8.9±0.1, and the reaction continued for 5.5 h. After the reaction was completed, the powder was cleaned by a combination of centrifugation and ultrasonication. After centrifugation at 8000 rpm and washing with ethanol / deionized water four times alternately, the powder was placed in a plasma reactor and treated at 400 W power under a nitrogen atmosphere for 40 min. The treated powder was then placed in a muffle furnace and heated to 300 °C at 3 °C / min and held for 1 h. The temperature was then increased to 480 °C at 5 °C / min and held for 1.5 h to obtain functionalized bismuth vanadate with a dense TiO2-SiO2 composite layer on the surface.

[0081] Preparation of high-durability yellow automotive paint: Hydroxyacrylate resin (OH value 135 mg KOH / g) and HDI trimer (NCO content 23.5%) were premixed at a mass ratio of 50:50 to obtain a base resin. 70 parts by weight of the base resin were mixed with 30 parts by weight of functionalized bismuth vanadate, 1.5 parts by weight of BYK-2015 dispersant, and 0.6 parts by weight of EFKA-3777 fluorocarbon leveling agent, and ground. Then, 2.5 parts by weight of organosilicon modifier (Tego Rad 2100) and 3.5 parts by weight of nano-zirconia (ZrO2, particle size 20 nm) were added, and the mixture was ground using a sand mill until the fineness was ≤6 μm. An appropriate amount of propylene glycol methyl ether acetate was added to adjust the viscosity to 95 ± 3 s (Ford Cup 4). The mixture was filtered through a 200-mesh filter to obtain the high-durability yellow automotive paint.

[0082] The prepared high-durability yellow automotive paint was electrostatically sprayed onto Q235 steel sheet, and its performance was tested. The test results are as follows:

[0083] Initial optical properties: initial 60° gloss 99.5, chromaticity L=93.1 / a=-1.2 / b=94.6 (CIE Lab);

[0084] Mechanical properties: Pencil hardness 5H, cross-cut adhesion grade 0 (ISO 2409), Taber abrasion (CS-10 wheel, 1000g / 1000 rpm) weight loss 8mg;

[0085] Weather resistance: After 4000 hours of QUV testing, ΔE = 0.7, gloss retention rate 97.5%;

[0086] Chemical resistance: No change after soaking in 10% H2SO4 for 96 hours or 10% NaOH for 96 hours; withstands 200 MEK wiping cycles.

[0087] Environmental testing: 100 cycles of cyclic corrosion test (CCT) with no defects, and a crushing stone impact resistance rating of 9 (SAE J400).

[0088] Example 3

[0089] Preparation of functionalized bismuth vanadate: 200g of bismuth vanadate powder (D50=1.0μm) was added to 4L of anhydrous ethanol to prepare a 5% (w / w) suspension. The suspension was ultrasonically treated for 40min to ensure full dispersion. Under nitrogen protection, a mixed solution of tetrabutyl titanate (0.08mol) and tetraethyl orthosilicate (0.08mol) (molar ratio 1:1) was added, and the mixture was heated to 55℃ and stirred for 1.5h. Ammonia water with a mass fraction of 10% was added dropwise to adjust the pH to 8, and the reaction was continued for 3.5h. After the reaction was completed, the solid product was collected by centrifugation, washed twice with ethanol, and then placed in a plasma reactor and treated at 300W power under a nitrogen atmosphere for 20min. The treated powder was placed in a muffle furnace, heated to 380℃, and held for 1h to obtain functionalized bismuth vanadate with a dense TiO2-SiO2 composite layer on the surface.

[0090] Preparation of high-durability yellow automotive paint: Hydroxyacrylate resin (OH value 110 mg KOH / g) and ordinary HDI trimer were premixed at a mass ratio of 60:40 to obtain a base resin. 60 parts by weight of the base resin were taken, and 25 parts by weight of functionalized bismuth vanadate, 0.5 parts by weight of BYK-110 dispersant, and 0.3 parts by weight of BYK-354 leveling agent were added and mixed and ground. Then, 1.5 parts by weight of KH-570 silane coupling agent and 2.5 parts by weight of nano-alumina (particle size 100 nm) were added, and the mixture was ground using a sand mill until the fineness was ≤10 μm. An appropriate amount of propylene glycol methyl ether acetate was added to adjust the viscosity to 100 ± 10 s (Ford cup 4). The mixture was filtered through a 100-mesh filter to obtain the high-durability yellow automotive paint.

[0091] The prepared high-durability yellow automotive paint was electrostatically sprayed onto Q235 steel sheet, and its performance was tested. The test results are as follows:

[0092] Initial optical properties: 60° gloss 95, chromaticity L=90.5 / a=-0.8 / b=92.3;

[0093] Mechanical properties: Pencil hardness 2H, cross-cut adhesion grade 1;

[0094] Weather resistance: After 2000 hours of QUV aging, ΔE=1.3, and gloss retention rate is 88%;

[0095] Chemical resistance: No significant changes were observed after immersion in 5% H2SO4 for 48 hours or 5% NaOH for 48 hours.

[0096] Solvent resistance: No change after 80 alcohol wipes; slight swelling after 48 hours of gasoline immersion.

[0097] Salt spray resistance: rust width at scratches ≤ 1 mm after 720 hours.

[0098] Comparative Example 1

[0099] 1 kg of commercially available bismuth vanadate powder (D50=0.8μm, same batch as in Example 1) was directly used. Only routine physical dispersion treatment was performed: the powder was added to 6 L of anhydrous ethanol and mechanically stirred for 30 min (500 rpm); after centrifugation (4000 rpm × 10 min), it was dried in a 60°C oven for 12 hours; no surface modification treatment was performed, and it was directly used for coating preparation.

[0100] Traditional coating preparation: A resin system was prepared by compounding the same hydroxyl acrylic resin (OH value 120 mg KOH / g) and HDI trimer (NCO content 21.6%) as in Example 1; 65 parts by weight of the base resin were taken, and 30 parts by weight of unmodified bismuth vanadate, 1.0 part by weight of BYK-110 dispersant, and 0.5 parts by weight of BYK-333 leveling agent were added; no organosilicon modifiers or nano-wear-resistant materials were added; the mixture was ground to a fineness ≤10 μm using the same sand mill, the viscosity was adjusted to 85±5s (Ford Cup 4), and filtered through a 200-mesh filter.

[0101] The prepared automotive paint was electrostatically sprayed onto Q235 steel sheet, and its performance was tested. The test results are as follows:

[0102] Initial optical properties: 60° gloss 90, chromaticity L=89.2 / a=-0.5 / b=90.1 (CIE Lab);

[0103] Mechanical properties: Pencil hardness 1H, cross-cut adhesion grade 2 (ISO 2409).

[0104] Weather resistance: After 1000 hours of QUV testing, ΔE = 4.5, and gloss retention is only 65%.

[0105] Chemical resistance: After immersion in 5% H2SO4 for 24 hours, obvious discoloration occurred, and the coating began to blister after 48 hours; after immersion in 5% NaOH for 36 hours, edge peeling occurred.

[0106] Solvent resistance: The coating swells after being soaked in gasoline for 24 hours and softens after 72 hours; the surface shows signs of wear after being wiped with alcohol 50 times.

[0107] Salt spray resistance: After 480 hours of testing, the rust width at the scratched area reached 2.5 mm, and obvious blistering appeared in the unscratched area;

[0108] Abrasion resistance: Taber wear (CS-10 wheel, 500g / 1000 rpm) resulted in a weight loss of up to 35mg.

[0109] The paint performance test data for the examples and comparative examples are shown in Table 1 below:

[0110] Table 1. Test results of vehicle paint performance in the examples and comparative examples.

[0111]

[0112] The comparison shows that the paint using the composition ratio of the present invention has significantly improved optical properties, hardness, chemical corrosion resistance and durability compared with Comparative Example 1. The prepared paint not only has bright and long-lasting color, but also has excellent comprehensive performance, which fully meets the requirements of high-end automotive coating.

[0113] Example 4

[0114] Preparation of functionalized bismuth vanadate: 1.3 kg of bismuth vanadate powder (D50 = 0.6 μm) was added to 7 L of anhydrous ethanol to prepare a suspension with a mass fraction of 19.1%. The suspension was sonicated for 55 min to ensure thorough dispersion. Under nitrogen protection, a mixed solution of tetrabutyl titanate (0.18 mol) and tetraethyl orthosilicate (0.54 mol) (molar ratio 1:3) was slowly added, and the mixture was heated to 70 °C and stirred for 2.8 h. A peristaltic pump was used to add a mass fraction of bismuth vanadate dropwise at a rate of 1.8 mL / min. The pH was adjusted to 9.0±0.2 using 12% ammonia water, and the reaction continued for 5 hours. After the reaction was completed, the powder was centrifuged at 8500 rpm and washed 5 times with alternating ethanol / deionized water. Then, it was placed in a plasma reactor and treated for 380W at a nitrogen atmosphere for 38 minutes. The treated powder was then placed in a muffle furnace and heated to 420℃ at a rate of 4℃ / min and held for 1.8 hours to obtain functionalized bismuth vanadate with a dense TiO2-SiO2 composite layer on the surface.

[0115] Preparation of high-durability yellow automotive paint: Hydroxyacrylate resin (OH value 125 mg KOH / g) and HDI trimer (NCO content 22.5%) were premixed at a mass ratio of 52:48 to obtain the base resin. 68 parts by weight of the base resin were taken, and 30 parts by weight of functionalized bismuth vanadate, 1.4 parts by weight of a composite dispersant (BYK-2150: Solsperse 39000 = 1.5:1), and 0.55 parts by weight of a leveling agent (BYK-378: Tego Flow 425 = 2:1) were added and mixed and ground. Add 2.4 parts by weight of organosilicon modifier (KH-560:Tego Rad 2200=2:1) ​​and 3.3 parts by weight of nano-alumina (γ-Al2O3, particle size 30nm), grind to fineness ≤7μm using a sand mill, add an appropriate amount of propylene glycol methyl ether acetate to adjust the viscosity to 90±5s (Ford-4 cup), filter with a 250 mesh filter to obtain a high-durability yellow car paint.

[0116] The prepared high-durability yellow automotive paint was electrostatically sprayed onto a Q235 steel plate. After standing for 30 minutes, the paint was subjected to storage stability testing: a portion of the paint was placed in a sealed container and accelerated aging in a 50℃ constant temperature chamber for 28 days, and the viscosity change and sedimentation / stratification before and after were tested; another portion of the paint was left to stand at room temperature for 6 months to observe whether sedimentation or stratification occurred. Simultaneously, routine performance tests were performed on the sprayed samples, and the results are as follows:

[0117] Storage stability: After 28 days of accelerated aging at 50℃, the viscosity change rate is ≤5%, with no sedimentation or stratification; after standing at room temperature for 6 months, there is no sedimentation or stratification.

[0118] Initial optical properties: 60° gloss 99, chromaticity L=93.5 / a=-1.3 / b=94.2 (CIE Lab);

[0119] Mechanical properties: Pencil hardness 4H, cross-cut adhesion grade 0 (ISO 2409), Taber abrasion (CS-10 wheel, 1000g / 1000 rpm) weight loss 7mg;

[0120] Weather resistance: After 3500 hours of QUV aging, ΔE=0.9, gloss retention rate is 96%;

[0121] Chemical resistance: No change after soaking in 8% H2SO4 for 84 hours or 8% NaOH for 84 hours; withstands 150 MEK wiping cycles.

[0122] Environmental testing: 120 cycles of cyclic corrosion test (CCT) with no defects, and a crushing stone impact resistance rating of 10 (SAE J400).

[0123] Comparative Example 2

[0124] 1.3 kg of commercially available bismuth vanadate powder (D50 = 0.6 μm, same batch as in Example 4) was directly used. Only routine physical dispersion treatment was performed: the powder was added to 7 L of anhydrous ethanol and mechanically stirred for 40 min (600 rpm); after centrifugation (4500 rpm × 12 min), it was dried in a 65°C oven for 15 hours; no surface modification treatment was performed, and it was directly used for coating preparation.

[0125] Traditional coating preparation: The same hydroxyl acrylic resin (OH value 125 mg KOH / g) and HDI trimer (NCO content 22.5%) as in Example 4 were used to form a resin system; 68 parts by weight of the base resin were taken, and 30 parts by weight of unmodified bismuth vanadate, 1.2 parts by weight of BYK-110 dispersant, and 0.5 parts by weight of BYK-333 leveling agent were added; no organosilicon modifiers or nano-wear-resistant materials were added; the coating was ground to a fineness ≤10 μm using the same sand mill, the viscosity was adjusted to 90±5s (Ford Cup 4), and filtered through a 250-mesh filter.

[0126] The prepared automotive paint was electrostatically sprayed onto Q235 steel plates, and storage stability tests were conducted simultaneously: a portion of the paint was subjected to accelerated aging in a 50℃ constant temperature chamber for 28 days, and the viscosity changes and sedimentation / stratification before and after were tested; another portion of the paint was left to stand at room temperature for 6 months to observe whether sedimentation or stratification occurred. Routine performance tests were performed on the sprayed samples, and the results are as follows:

[0127] Storage stability: After 7 days of accelerated aging at 50℃, significant sedimentation occurred, and after 28 days, a hard precipitate formed at the bottom with a viscosity change rate of ≥25%; after standing at room temperature for 3 months, stratification occurred, with a clear liquid in the upper layer.

[0128] Initial optical properties: 60° gloss 88, chromaticity L=88.6 / a=-0.4 / b=89.3 (CIE Lab);

[0129] Mechanical properties: Pencil hardness B, cross-cut adhesion grade 3 (ISO 2409), Taber abrasion (CS-10 wheel, 1000g / 1000 rpm) weight loss 42mg;

[0130] Weather resistance: After 800 hours of QUV aging, ΔE=5.2, and gloss retention rate is only 58%;

[0131] Chemical resistance: After immersion in 3% H2SO4 for 12 hours, obvious discoloration occurred, and the coating began to bubble and peel off after 36 hours; after immersion in 3% NaOH for 24 hours, edge peeling occurred; the coating only withstood 30 MEK wiping cycles.

[0132] Environmental testing: Obvious blistering and rust expansion were observed after 40 cycles of cyclic corrosion test (CCT), and the crush stone impact resistance (SAEJ400) level was 5.

[0133] Test Result Analysis

[0134] Example 4, through surface coating with a dense TiO2-SiO2 composite layer and the addition of organosilicon modifiers and nano-alumina, significantly improved the dispersion stability and interfacial bonding of bismuth vanadate in the resin. Therefore, the automotive paint exhibited excellent storage stability (no stratification or sedimentation) and overall performance. Comparative Example 2, due to the use of unmodified bismuth vanadate and the lack of corresponding modifying components, showed poor compatibility between the pigment and resin, leading to rapid sedimentation and stratification during storage, and significant deterioration in all coating properties. This confirms that the present invention effectively solves the key problems of easy stratification and poor stability in traditional bismuth vanadate coatings by modifying the surface of bismuth vanadate and optimizing the coating system.

[0135] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of the present invention is limited to these examples; within the framework of the embodiments of the present invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention.

Claims

1. A highly durable yellow car paint, characterized in that, The product comprises, by weight, the following components: 60-70 parts by weight of base resin, 25-30 parts by weight of functionalized bismuth vanadate, 0.5-1.5 parts by weight of dispersant, 0.3-0.6 parts by weight of leveling agent, 1.5-2.5 parts by weight of organosilicon modifier, and 2.5-3.5 parts by weight of wear-resistant agent. The base resin is selected from a composite system including hydroxyl acrylic resin and HDI trimer curing agent. The functionalized bismuth vanadate has a titanium dioxide-silica composite coating layer and has undergone plasma treatment. The functionalized bismuth vanadate is prepared by a method comprising the following steps: dispersing bismuth vanadate powder in a solvent to form a first solution; adding a mixed solution of tetrabutyl titanate and tetraethyl orthosilicate to the first solution and stirring to react; adjusting the pH of the reacted solution to 8-9 and continuing the reaction. The solution was subjected to solid-liquid separation, the solid was collected and subjected to plasma treatment under nitrogen protection; the plasma-treated solid was calcined to obtain the functionalized bismuth vanadate.

2. The high-durability yellow car paint according to claim 1, characterized in that, The mass ratio of hydroxyl acrylic resin to HDI trimer curing agent in the base resin is 5~6:4~5.

3. The high-durability yellow car paint according to claim 1, characterized in that, The dispersant is selected from one or two of the following: polyurethane dispersants, acrylate dispersants, anionic surfactants, copolymers containing siloxane groups, and graphene-modified dispersants.

4. The high-durability yellow car paint according to claim 1, characterized in that, The leveling agent is selected from one or two of the following: silicone leveling agents, fluorocarbon leveling agents, and acrylate leveling agents.

5. The high-durability yellow car paint according to claim 1, characterized in that, The organosilicon modifier is selected from one or two of the following: reactive silanes, polysiloxane resins, organosilicon-acrylic hybrid resins, long-chain alkyl-modified silicone oils, and amino-modified silicone oils.

6. A method for preparing a high-durability yellow automotive paint, characterized in that, The method is used to prepare yellow vehicle paint as described in any one of claims 1-5 and includes the following steps: The preparation of functionalized bismuth vanadate, wherein the functionalized bismuth vanadate has a titanium dioxide-silica composite coating layer and is subjected to plasma treatment, comprises the following steps: dispersing bismuth vanadate powder in a solvent to form a first solution; adding a mixed solution of tetrabutyl titanate and tetraethyl orthosilicate to the first solution and stirring to react; adjusting the pH of the reacted solution to 8-9 and continuing the reaction; The solution was subjected to solid-liquid separation, the solid was collected and subjected to plasma treatment under nitrogen protection; the plasma-treated solid was calcined to obtain the functionalized bismuth vanadate. Hydroxy acrylic resin and HDI trimer curing agent are premixed in a set ratio to obtain the base resin; The functionalized bismuth vanadate, dispersant, and leveling agent are added to the base resin in a set ratio and then mixed and ground. The organosilicon modifier and wear-resistant agent are added to the base resin and ground and dispersed. After adjusting the viscosity, the mixture is filtered to obtain the yellow car paint.

7. The method for preparing high-durability yellow automotive paint according to claim 6, characterized in that, The tetrabutyl titanate and tetraethyl orthosilicate are added to the mixed solution at a molar ratio of 1:1 to 5 (based on titanium and silicon). The mixture is stirred at 55 to 75°C for 1.5 to 3 hours. After adjusting the pH of the solution to 8 to 9, the reaction continues for another 3.5 to 5.5 hours.

8. The method for preparing high-durability yellow automotive paint according to claim 6, characterized in that, The power used for plasma treatment is 300~400W, the time is 20~40min; the calcination temperature is 380~480℃, and the calcination time is 1~2.5h.

9. The method for preparing high-durability yellow automotive paint according to claim 6, characterized in that, The components for preparing the high-durability yellow car paint are mixed and ground until the particle size is ≤10μm, and then the viscosity is adjusted.

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