Preparation method of water-based environment-friendly bio-based automotive finishing paint

Abstract

The invention provides a preparation method of water-based environment-friendly bio-based automobile finish paint, and belongs to the technical field of automobile paints.The preparation method comprises the following steps that S1, a water-based bio-based acrylate modified polyester dispersion is synthesized; s2, preparing a thixotropic agent; s3, mixing and homogenizing finish paint components; the water-based bio-based acrylate modified polyester dispersion, amino resin, color paste, a thixotropic agent, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, a wetting agent, a flatting agent and pure water are adopted as raw materials to prepare the finishing paint; the finish paint produced by the method not only has strong adhesive force, but also has good hardness, strong flexibility and impact resistance. Meanwhile, due to the adoption of the water-based environment-friendly bio-based resin, emission of harmful volatile matters can be effectively avoided, and dual improvement of environmental protection and commodity performance is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile coatings, and in particular to a method for preparing a water-based environmentally friendly bio-based automobile topcoat. Background Art

[0002] Automotive coatings are an integral part of the automotive manufacturing process, used to protect the car body from corrosion and environmental factors while providing an aesthetically pleasing appearance. Conventional automotive topcoats are mostly based on solvent-based coatings, which contain a large amount of volatile organic compounds (VOCs). These VOCs are released into the atmosphere during the drying and curing process of the coating, causing serious environmental pollution, including damage to the ozone layer and potential threats to human health.

[0003] In response to environmental challenges, waterborne topcoats based on bio-based raw materials have been developed, that is, raw materials extracted from renewable resources are used to replace traditional petrochemical raw materials. However, existing bio-based topcoats often face the problem of insufficient comprehensive performance. Although these topcoats perform well in reducing environmental impact, they often cannot match traditional chemical synthetic topcoats in key performance indicators such as adhesion, hardness, impact resistance and flexibility. These performance deficiencies limit the widespread adoption of bio-based topcoats in commercial and industrial applications.

[0004] For example, insufficient adhesion may cause the coating to peel off easily during vehicle use, affecting the vehicle's protective function and appearance quality. Insufficient hardness reduces the coating's resistance to physical wear, while lower impact resistance and flexibility may cause coating damage when the vehicle suffers a minor collision. These problems highlight the need to develop a new type of water-based environmentally friendly bio-based automotive topcoat that can meet high-performance industrial application requirements while maintaining environmental protection characteristics.

[0005] Therefore, there is an urgent need for a new water-based automotive original equipment topcoat preparation technology that can reduce environmental pollution while providing excellent physical and chemical properties that match those of traditional automotive topcoats. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems in the prior art and to provide a method for preparing a water-based environmentally friendly bio-based automobile topcoat.

[0007] The purpose of the present invention can be achieved by the following technical scheme: A method for preparing a water-based environmentally friendly bio-based automotive topcoat, comprising the following steps:

[0008] S1 Synthesis of water-based bio-based acrylate modified polyester dispersion: S1.1 Esterification reaction: by weight, 245-275 parts of bio-based diol, 210-240 parts of bio-based dibasic acid and 1-5 parts of ester catalyst are added into a reactor to form a mixed material; the temperature in the reactor is heated to 120-130°C, and after the mixed material is completely melted, nitrogen is introduced and stirred; then the temperature in the reactor is gradually raised to 230-240°C, and the temperature is kept warm; after the esterification reaction is completed, the bio-based polyester diol is obtained;

[0009] The bio-based diol has a 100% 14C bio-based content, specifically at least one of 1,2-propylene glycol, 1,4-butylene glycol, 1,9-nonanediol, and 1,10-decanediol;

[0010] The bio-based dibasic acid has a 100% 14C bio-based content, specifically at least one of azelaic acid, sebacic acid, and dodecanedioic acid;

[0011] The ester catalyst is TYZOR BTP polybutyl titanate;

[0012] Reasons for choosing bio-based diols: Structural diversity and application flexibility: 1,2-propylene glycol and 1,4-butylene glycol: These shorter-chain diols generally have better solubility and lower viscosity, which helps improve the processing performance of polymers. Their good fluidity at low temperatures can improve the flexibility and impact resistance of the final product;

[0013] 1,9-Nonanediol and 1,10-Decanediol: Longer-chain diols provide greater intermolecular forces, enhancing the polymer’s mechanical stability and heat resistance; these properties are important for automotive coatings, which need to maintain stable performance under varying environmental conditions.

[0014] Sustainability of bio-based sources: All of these diols can be synthesized from biomass (such as corn, sugar cane or other bio-oils) through fermentation or other biochemical pathways, which meets the needs of environmental protection and sustainable development.

[0015] Reasons for choosing bio-based dibasic acids: Improve polymer performance: Azelaic acid and sebacic acid: These longer-chain dibasic acids can form longer molecular chains in polymers, enhancing the flexibility and wear resistance of the coating, while also providing better chemical stability and weather resistance.

[0016] Dodecanedioic acid: It has strong polarity and can improve the overall performance of polymers by increasing intermolecular forces, especially in high temperature and high humidity environments.

[0017] Environmental advantages: These acids can also be produced through bio-based methods, reducing dependence on traditional petroleum resources and complying with the trend of environmentally friendly production.

[0018] Specific performance requirements: In high-performance automotive coatings, materials are required to have excellent physical, chemical and thermal stability. The selection of these specific bio-based dibasic acids can optimize these requirements and ensure that the coating does not degrade in performance over time or under extreme conditions.

[0019] Overall, by selecting these specific bio-based diols and dibasic acids, we can not only meet the sustainability needs of producing environmentally friendly bio-based automotive topcoats, but also ensure that the coating products meet the high standards of the automotive industry in terms of performance.

[0020] S1.1 describes in detail the specific operation of the esterification reaction, including the amount of bio-based diol and bio-based dibasic acid, temperature setting, and ester catalyst used. The selection of these parameters is based on the following important chemical considerations:

[0021] 1. Ratio of bio-based diols and bio-based dibasic acids (245-275 parts and 210-240 parts): Theoretical basis and stoichiometry: These ratios are designed based on the stoichiometric ratio of the reactants to ensure that the diols and dibasic acids can react effectively to form the desired polyester structure. Selecting a slightly wider range provides flexibility to adjust the ratio during production according to changes in raw material characteristics and purity.

[0022] Control of final product properties: By adjusting the ratio of diols and dibasic acids, the molecular weight and crosslink density of the final polyester can be fine-tuned, affecting the mechanical properties and durability of the coating.

[0023] 2. Temperature setting (heat to 120-130℃, then increase to 230-240℃)

[0024] Importance of temperature control: The initial temperature is set to 120-130°C to ensure that all solid raw materials can be fully melted to form a uniform reaction mixture, which is crucial for the uniformity of subsequent chemical reactions.

[0025] High temperature esterification: The temperature is then gradually raised to 230-240°C and kept warm because high temperature is conducive to the esterification reaction and accelerates the reaction rate between molecules. At the same time, high temperature also helps to expel the moisture generated during the reaction, push the reaction equilibrium toward the product direction, and increase the molecular weight and yield of polyester.

[0026] 3. Use ester catalyst (1-5 parts TYZOR BTP polybutyl titanate)

[0027] Catalyst selection and dosage: TYZOR BTP polybutyl titanate was selected as the catalyst because it has high activity and can effectively catalyze the esterification reaction at a lower dosage to reduce side reactions. The dosage of the catalyst is controlled at a low level to avoid affecting the color and physical properties of the coating.

[0028] Catalytic efficiency and environmental protection characteristics: Polybutyl titanate as a catalyst shows low volatile organic compound (VOC) release and lower toxicity in the reaction, which is particularly important for the preparation of environmentally friendly coatings.

[0029] The precise setting of these parameters ensures the effectiveness and efficiency of the chemical reaction, while taking into account the optimization of environmental protection and production costs, so that the final product can maintain high performance while also meeting environmental and sustainable requirements.

[0030] S1.2 Introducing unsaturated monomers: lowering the temperature in the reactor to 180-190°C; adding 80-100 parts of bio-based 2-octyl acrylate and 1-3 parts of a catalyst to the reactor to react until the acid value is ≤5 mgKOH / g; lowering the temperature in the reactor to 160-165°C, adding 20-30 parts of trimellitic anhydride, and carrying out a heat-insulating reaction until the acid value is 25-30 mgKOH / g; finally removing the small molecule prepolymer by vacuum decompression to obtain a water-based bio-based acrylate modified polyester resin;

[0031] The catalyst is di-tert-butyl peroxide;

[0032] This step involves the introduction of an unsaturated monomer (bio-based 2-octyl acrylate) and a crosslinker (trimellitic anhydride) into the bio-based polyester system and the use of a catalyst (di-tert-butyl peroxide) to promote these reactions. The reasons for these choices are detailed below:

[0033] Bio-based 2-octyl acrylate: Functionality: Bio-based 2-octyl acrylate is an unsaturated monomer, which is introduced to introduce unsaturated double bonds at the ends of the polyester chains. These double bonds can form cross-linked structures through free radical polymerization in the subsequent curing stage, thereby enhancing the mechanical strength and chemical stability of the coating.

[0034] Environmentally friendly attributes: Selecting acrylates with a certain proportion of bio-based content (73% 14C bio-based content) meets the product requirements of environmental protection and sustainable development and reduces dependence on traditional petrochemicals.

[0035] Di-tert-butyl peroxide (DTBP): Catalytic effect: DTBP is a commonly used free radical initiator, which can generate free radicals at a lower decomposition temperature to promote the polymerization reaction of acrylate monomers. In this process, DTBP not only acts as a catalyst, but also improves the safety of the reaction and the quality of the product by controlling the reaction rate and heat release.

[0036] Reaction Control: The use of DTBP allows polymerization reactions to be carried out efficiently at lower temperatures, helping to reduce side reactions due to high temperatures, such as thermal degradation of polyesters.

[0037] Trimellitic anhydride: Crosslinking agent: As a trifunctional compound, trimellitic anhydride can react with the hydroxyl groups on the polyester chain to form anhydride rings, which can then react with the hydroxyl groups or amino groups on other chains to form a crosslinked network structure. This structure gives the final product better chemical resistance and physical properties.

[0038] Improved performance: By introducing trimellitic anhydride, not only the mechanical properties and durability of the coating are enhanced, but also its high temperature resistance and chemical resistance are improved, making it very suitable for automotive topcoat, which needs to maintain stable performance in various environments.

[0039] In summary, these specific materials were chosen to ensure that bio-based polyesters meet the high requirements of automotive topcoats in terms of mechanical strength, wear resistance and chemical stability while maintaining their environmentally friendly properties.

[0040] The synthesis of bio-based acrylate-modified polyester resins is critical to strict requirements on temperature control, material ratio and reaction conditions, as they directly affect the quality and performance of the final product. The following is a detailed explanation of the logic behind these choices:

[0041] Temperature control: 180-190°C: Adding bio-based 2-octyl acrylate and catalyst within this temperature range is mainly to ensure that the acrylate can effectively react with the polyester chain, while avoiding thermal degradation caused by too high a temperature or too fast a reaction rate, which may lead to difficult to control the reaction and unstable product quality.

[0042] 160-165℃: The temperature for adding trimellitic anhydride is slightly lower. This is to reduce the side reactions that may be caused by too high temperature, such as excessive polymerization or incomplete reaction of trimellitic anhydride, and also to ensure the effective reaction between the anhydride ring and the polyester chain.

[0043] Requirements for the number of shares and acid value: Ratios of bio-based 2-octyl acrylate and trimellitic anhydride: These ratios ensure the introduction of sufficient unsaturated double bonds and cross-linking points, thereby forming an ideal network structure during the curing stage and enhancing the mechanical properties and durability of the coating.

[0044] Acid value control (acid value ≤ 5 mg KOH / g and acid value 25-30 mg KOH / g): Acid value control is a key indicator for evaluating the reaction process and product quality. The initial low acid value is required to ensure that the reaction of the acrylate is sufficiently complete, while the subsequent higher acid value is to ensure that the trimellitic anhydride can react fully while avoiding excessive crosslinking density caused by overreaction.

[0045] The step of removing small molecule prepolymers by vacuum decompression is crucial because: Purification: Remove unreacted monomers and low molecular weight by-products, which, if left in the product, will affect the performance of the coating, such as causing unstable viscosity of the coating, reducing the gloss and weather resistance of the coating.

[0046] Enhanced performance: Ensuring that only high molecular weight polymers are present in the final product enhances the mechanical strength and chemical resistance of the coating, while also contributing to the overall quality and aesthetics of the coating.

[0047] In summary, strict temperature control, proportion and acid value requirements in this step, as well as the removal of small molecule prepolymers, are all aimed at optimizing reaction conditions, ensuring the integrity and efficiency of the reaction, and ultimately obtaining high-quality environmentally friendly bio-based automotive topcoat. These control points are key factors in ensuring that the product exhibits excellent performance in application.

[0048] S1.3 Emulsification: lowering the temperature in the reactor to 100-110°C; then stirring, adding 50-70 parts of ethylene glycol butyl ether and 270-300 parts of pure water to the reactor during stirring, stirring for 20-30 minutes, lowering the temperature in the reactor to 78-82°C, then adding 20-30 parts of silane, 3-5 parts of stabilizer and 15-25 parts of dimethylethanolamine, and keeping warm for 2-3 hours, cooling the temperature in the reactor to room temperature and filtering to obtain an aqueous bio-based acrylate modified polyester dispersion;

[0049] The silane is 3-isocyanatepropyltrimethoxysilane;

[0050] The stabilizer is a mixture of polyoxyethylene sorbitan fatty acid ester and sorbitan tristearate, wherein the weight ratio of polyoxyethylene sorbitan fatty acid ester to sorbitan tristearate is 7:3;

[0051] The key to the emulsification stage in the preparation of environmentally friendly bio-based automotive topcoats is to form a stable aqueous dispersion to ensure that the final product has good application performance and environmental characteristics. In this step, the selection of ethylene glycol butyl ether, silane, stabilizer and dimethylethanolamine each has its own unique purpose and role:

[0052] Ethylene glycol butyl ether: As a solvent and co-solvent: Ethylene glycol butyl ether, as a solvent with good dissolving ability, can effectively help the compatibility between the dispersion medium and the polymer and promote the formation of a uniform emulsion.

[0053] Reduce surface tension: By reducing the surface tension between water and other non-hydrophilic components, ethylene glycol butyl ether helps the formation and stability of emulsions and improves dispersion efficiency.

[0054] Silane (3-isocyanatepropyltrimethoxysilane): coupling agent and surface modifier: Silane, as a coupling agent, can form a stable chemical bond between the polyester molecular chain and the aqueous medium, thereby improving the mechanical strength and water resistance of the emulsion.

[0055] Improving adhesion and weather resistance: Silane can improve the adhesion of the coating while enhancing the weather resistance of the coating. It is a very important additive in the manufacture of automotive topcoat.

[0056] Stabilizers (polyoxyethylene sorbitan fatty acid esters and sorbitan tristearate): Emulsification and stabilization: Stabilizers prevent polymer particles from aggregating and settling in the emulsification system, thereby maintaining the long-term stability of the emulsion.

[0057] Improve film-forming properties: These stabilizers can also help the coating form a uniform film during the coating process, reduce coating defects and improve coating effects.

[0058] Polyoxyethylene sorbitan fatty acid ester: Emulsification performance: This stabilizer is a non-ionic surfactant with excellent emulsification ability, which can help aqueous components form stable emulsions with hydrophobic substances such as polyester resins.

[0059] Enhanced Wettability: It can improve the wetting of the coating to the substrate, helping the coating to form a more uniform and smooth surface.

[0060] Dispersing power: It helps maintain uniform dispersion of pigments and fillers, prevents particle settling, and improves the quality and appearance of the final product.

[0061] Sorbitan Tristearate: Enhanced Stability: This stabilizer enhances the thermal and mechanical stability of the coating, making it more durable.

[0062] Control viscosity: Help control the viscosity of the emulsion to ensure fluidity and construction performance during coating.

[0063] Provides durability: Positively affects the long-term performance of the coating, especially in water- and moisture-resistant environments.

[0064] Combination ratio (7:3): Optimize synergistic effect: Polyoxyethylene sorbitan fatty acid esters are mainly responsible for providing good emulsification and dispersibility, while sorbitan tristearate increases the stability and durability of the overall formula. By adjusting the ratio of the two, the emulsification effect and stability can be balanced to achieve better coating performance.

[0065] Achieving comprehensive performance: This ratio is obtained through experimental optimization, aiming to make the coating have good applicability and long-term stability while meeting environmental protection and bio-based requirements.

[0066] Dimethylethanolamine: pH adjuster: As an alkaline substance, dimethylethanolamine is used to adjust the pH value of the emulsion to optimize the emulsification process and improve the stability of the polymer.

[0067] Enhanced dispersion effect: Dimethylethanolamine also helps improve the dispersion properties of polymers, especially in water-based systems.

[0068] In summary, these ingredients are selected to ensure a smooth emulsification process while providing the required chemical and physical properties so that the final product meets high quality standards.

[0069] The selection of the proportions of various additives is crucial to ensure the quality and performance of environmentally friendly bio-based automotive topcoats. The following is a detailed analysis of the reasons for selecting the proportions of each ingredient:

[0070] Ethylene glycol butyl ether (50-70 parts): The range of 50-70 parts is selected to ensure sufficient solvent action to promote mixing of the resin and water while maintaining the fluidity and handling of the mixture. Too little may result in poor emulsification, while too much may lead to cost uneconomical and possible environmental burden.

[0071] Pure water (270-300 parts): Water is the main medium in the emulsification process, and the selection of 270-300 parts ensures a sufficient amount to form a stable emulsion. The amount of water has an important impact on the stability of the emulsion and the properties of the final coating, including viscosity and drying time. Too little water may result in incomplete emulsification, while too much may dilute the coating and affect its covering ability and adhesion.

[0072] Silane (20-30 parts): 20-30 parts of silane can ensure sufficient crosslinking and functionalization to enhance the durability and performance of the coating. Excessive amounts of silane may lead to increased costs and possible surface issues such as high viscosity or extended drying time.

[0073] Stabilizer (3-5 parts): The selection and dosage of stabilizer are critical to maintaining the long-term stability of the emulsion. 3-5 parts of stabilizer (mixed by weight) are sufficient to prevent emulsion delamination or polymer precipitation without affecting other properties of the coating. This ratio provides a balance between efficiency and cost.

[0074] Dimethylethanolamine (15-25 parts): Dimethylethanolamine is used as a pH regulator and emulsification aid. Its dosage of 15-25 parts can effectively control the pH value of the emulsion and improve the emulsification process. The appropriate pH value helps stabilize the emulsion and improve the quality of the final product. Too little may lead to poor pH control, affecting the emulsification effect and coating performance.

[0075] These shares are set based on experimental optimization and cost-benefit analysis to ensure the quality, performance and environmental standards of the final product. Each choice is made to minimize the impact on the environment while ensuring product performance, in line with the goal of using environmentally friendly bio-based materials.

[0076] Reasons for temperature and time selection: Temperature selection: Initial temperature adjustment at 100-110℃:

[0077] Within this temperature range, the reactant mixing and emulsification process can be carried out effectively while avoiding thermal degradation of heat-sensitive materials. This helps ensure the stability of the reactants and the emulsification effect.

[0078] This temperature is also conducive to the fluidity and mixing of the reaction materials, thereby better performing subsequent additions and mixing.

[0079] Secondary adjustment to 78-82°C: This temperature is more suitable for the addition and reaction of silane. At this temperature, silane can react better with the polyester matrix to form a stable network structure, enhancing the water resistance and adhesion of the coating.

[0080] Low temperatures facilitate uniform distribution of stabilizers and other additives, avoiding any possible polymerization or decomposition due to high temperatures.

[0081] Time setting: Stir for 20-30 minutes: This period of time is enough for the ethylene glycol butyl ether and water to mix completely and start the emulsification process.

[0082] Keep warm for 2-3 hours: This period of time is to ensure that all ingredients are fully reacted, especially the silane and stabilizer are fully reacted and evenly distributed to form a stable emulsion system.

[0083] S2 Preparation of thixotropic agent: pure water and PPG1000 are added to the mixer to perform the first dispersion operation; after the first dispersion operation, Laponite RD rheological additive is added; the speed is increased to perform the second dispersion operation until the solution is clear and transparent. The mixer is equipped with a dispersion disk;

[0084] According to the weight ratio, pure water:PPG1000:Laponite RD rheological additive is 99.7:0.1:0.2;

[0085] In the process of preparing environmentally friendly bio-based automotive topcoat, PPG1000 and LaponiteRD were selected as key ingredients in the preparation of thixotropic agents. The selection of these two materials and their specific proportions were based on their respective properties and functional considerations in the thixotropic agent.

[0086] Selection of PPG1000 (polypropylene glycol): hydroxyl value and molecular weight: PPG1000 has a moderate hydroxyl value (102-125 mgKOH / g) and molecular weight (900-1100), which makes it have good reactivity and controllability in chemical reactions and is suitable as a base material for rheology regulators.

[0087] Chemical stability: The low acid value (≤0.5 mgKOH / g) and low moisture content (≤0.5%) of PPG1000 ensure stability during mixing and storage, reducing possible side reactions.

[0088] Laponite RD rheological additive selection: structure and performance: Laponite RD is a layered silicate with a high specific surface area (370m 2 / g) and a specific chemical composition that provides excellent suspension and thixotropic properties. This means it disperses well in the coating and provides excellent consistency control.

[0089] pH and Chemical Composition: Laponite RD's pH (9.8) and composition consisting primarily of silica and magnesium oxide facilitate chemical compatibility and stability in aqueous systems.

[0090] Ratio (pure water:PPG1000:Laponite RD is 99.7:0.1:0.2):

[0091] The proportion of pure water (99.7%): A high proportion of pure water is used for dilution and as a medium, so that PPG1000 and Laponite RD can be evenly dispersed in the liquid to form a stable thixotropic agent solution. Too much solid content will make the solution too viscous and difficult to handle and use.

[0092] Ratio of PPG1000 (0.1%): Although the ratio of PPG1000 seems low, it is enough to play a good thickening and rheology adjustment role in the system due to its molecular weight and structural characteristics.

[0093] Ratio of Laponite RD (0.2%): Despite being added in small proportions, the efficient thixotropic and suspension properties of Laponite RD ensure that the necessary viscosity and stability are provided in the coating. Smaller additions also help control costs while achieving the required performance.

[0094] This precise ratio is based on the results of experiments and performance tests to ensure the maximum effect of the thixotropic agent, while taking into account cost-effectiveness and ease of application. The amount of each component is carefully calculated to ensure the best performance and economic benefits in the entire topcoat preparation process.

[0095] S3 topcoat component mixing and homogenization: diethylene glycol butyl ether, ethylene glycol butyl ether and pure water are put into a mixer to perform the first stirring operation; after the first stirring operation, amino resin is added, the stirring speed is increased, and the second stirring operation is performed; after the second stirring operation, a wetting agent and a defoaming agent are added, the stirring speed is continued to be increased, and the third stirring operation is performed; after the third stirring operation is completed, a water-based bio-based acrylate modified polyester dispersion is added, the stirring speed is reduced, and the fourth stirring operation is performed; after the fourth stirring operation is completed, a color paste and a thixotropic agent are added, and the fifth stirring operation is performed. After the fifth stirring operation is completed, an environmentally friendly bio-based automotive topcoat is obtained;

[0096] By weight, the waterborne bio-based acrylate modified polyester dispersion: amino resin: color paste: thixotropic agent: diethylene glycol butyl ether: ethylene glycol butyl ether: wetting agent: leveling agent: pure water is 50-60: 8-12: 12-20: 2-5: 2-3: 2-3: 0.2-0.5: 0.2-0.5: 10-20;

[0097] The wetting agent is specifically TEGO Wet 270 wetting agent; the leveling agent is specifically TEGO Glide 450 leveling agent.

[0098] The mixing and homogenization of topcoat ingredients, the selection of each ingredient is critical to achieve excellent coating performance, environmental friendliness and ease of application. The following details the reasons for the selection of each ingredient and their role in the preparation process:

[0099] 1. Water-based bio-based acrylate modified polyester dispersion: As the main film-forming substance, the dispersion is not only derived from renewable resources, ensuring the environmental friendliness of the product, but also provides excellent mechanical properties and weather resistance.

[0100] 2. Amino resin: Amino resin is used as a cross-linking agent in coatings. It can react with acrylic resin to form a network structure, enhancing the hardness, chemical resistance and gloss of the coating.

[0101] 3. Color paste: purchased in the market, the color can be adjusted according to customer requirements; color paste is used to provide the required color and beauty. For automotive coatings, color and gloss are one of the appearance attributes that consumers value.

[0102] 4. Thixotropic agent: Thixotropic agent is used to adjust the viscosity of the paint, ensuring that the paint does not flow during construction, is flat and free of brush marks after drying, and maintains good stability during storage and transportation.

[0103] 5. Butyl diglycol and butyl glycol ether: These solvents help to adjust the viscosity and fluidity of the coating, making the coating easy to apply and evenly coated, while improving film-forming properties and drying speed.

[0104] 6. Wetting agent (TEGO Wet 270): Wetting agent helps to reduce the surface tension of the coating, improve the wettability of the coating to the substrate, ensure that the coating can evenly cover the substrate, and improve adhesion and appearance quality.

[0105] 7. Leveling agent (TEGO Glide 450): Leveling agent is used to optimize the fluidity and self-leveling ability of the coating, prevent defects such as bubbles and brush marks during the coating process, and improve the overall aesthetics of the coating.

[0106] 8. Pure water: medium and diluent: As the main medium of water-based paint, pure water is used to adjust the overall viscosity and fluidity of the paint. It also serves as an environmentally friendly solvent to reduce the impact on the environment.

[0107] In the preparation of environmentally friendly bio-based automotive topcoats, each of the above components is carefully selected to meet the multiple requirements of high performance, environmental protection and user-friendliness.

[0108] The proportions of the components are critical to ensure the optimal performance and suitability of the final product.

[0109] The following is a detailed description of the selection of the proportions of each component:

[0110] 1. Waterborne bio-based acrylate modified polyester dispersion (50-60%):

[0111] Main film-forming component: This component serves as the basis of the coating, providing good film-forming properties and environmental protection properties. A higher proportion ensures the continuity and mechanical strength of the coating, and is also the key to ensuring the durability and environmental friendliness of the coating.

[0112] 2. Amino resin (8-12%): Enhanced cross-linking: Amino resin is used as a cross-linking agent to react with acrylate to form a three-dimensional network structure, which improves the chemical resistance, hardness and wear resistance of the coating. This ratio is sufficient to ensure a good cross-linking effect without over-hardening, and maintain a certain elasticity of the coating.

[0113] 3. Color paste (12-20%): Provide color and covering power: Color paste provides the required color and good covering power in the paint. This range of proportions can ensure sufficient color saturation while avoiding excessive addition that affects the physical properties of the coating.

[0114] 4. Thixotropic agent (2-5%): Adjust viscosity and rheology: Thixotropic agent is added to adjust the rheological properties of the coating, making the coating easy to handle during construction, smooth surface after drying, and reducing sagging. This ratio can optimize the construction performance of the coating without affecting drying and film formation.

[0115] 5. Diethylene glycol butyl ether and ethylene glycol butyl ether (2-3% each): Adjust the solubility and drying rate of the coating: These solvent ratios help adjust the viscosity and drying speed of the coating, while improving the fluidity and wettability of the coating, making the coating more uniform.

[0116] 6. Wetting agent and leveling agent (0.2-0.5% each): Improve the surface properties of the coating: The use of wetting agent and leveling agent can significantly improve the wettability and fluidity of the coating on the substrate, thereby obtaining a smoother and flawless coating surface. These proportions are sufficient to work effectively without affecting the overall performance of the coating.

[0117] 7. Pure water (10-20%): as a diluent and medium: Pure water not only acts as a solvent to dilute the paint and reduce the overall viscosity of the paint, but also as a basic medium for water-based paint, which contributes to environmental protection and safe use.

[0118] The design of these proportions fully considers the paint's workability, environmental protection, film-forming properties and final application effect. Through careful blending, it can ensure that the paint is suitable for use as a car topcoat while maintaining excellent performance.

[0119] Preferably, in step S1.1, the heating time is 4-5 hours, and the holding time is 2-4 hours; 100% 14C biobased content means that all carbon atoms come from biobased sources, which are biodegradable or renewable raw materials;

[0120] The parameters of TYZOR BTP polybutyl titanate are as follows: viscosity (25° C.) is 2000-6000 mPas; active content is 100%; titanium dioxide content is 34-35%.

[0121] Heating time is 4-5 hours: Gradual heating: Gradually increasing the temperature of the reactor can ensure uniform heating of the reactants and uniform reaction. This gradual heating method helps to avoid local overheating, which may cause side reactions or thermal decomposition of materials.

[0122] Reaction Control: The slow temperature ramp allows for gradual ester bond formation between the bio-based diol and dibasic acid, rather than abrupt reactions, allowing for better control of molecular weight and molecular weight distribution, which are critical to the performance of the final product.

[0123] The holding time is 2-4 hours: Esterification is completed: The holding stage is a critical period to ensure that the esterification reaction is carried out thoroughly. During this period, the reaction mixture is maintained at a higher temperature (230-240°C) to complete the reaction and ensure that the generated polyester diol has the required molecular weight and structure.

[0124] Improve yield: Longer holding time helps to increase the conversion rate of the esterification reaction and reduce unreacted monomers, which is beneficial to improving product performance and reducing subsequent processing costs.

[0125] Parameters of TYZOR BTP polybutyl titanate: TYZOR BTP polybutyl titanate, as an ester catalyst, plays a key role in this process: High active content (100%): It can achieve efficient catalytic effect without a large amount, thereby reducing the amount of catalyst used in the production process, reducing costs and potential by-products.

[0126] Moderate viscosity (2000-6000mPa·s): This viscosity range ensures good dispersion and fluidity of the catalyst in the reaction system, which helps to evenly participate in each esterification reaction.

[0127] Titanium dioxide content (34-35%): The titanium dioxide content reflects the proportion of the active components of the catalyst in promoting the esterification reaction, ensuring its efficient catalytic performance.

[0128] The control of these parameters is to ensure that the esterification reaction can be carried out efficiently, uniformly and stably during the synthesis of water-based bio-based acrylate-modified polyester dispersions, and ultimately obtain products with excellent performance.

[0129] Preferably, in step S1.2, the bio-based 2-octyl acrylate has a 14C bio-based content of 73%.

[0130] Preferably, in step S1.3, the stirring speed is set to 2300-2500 r / min.

[0131] Stirring speed setting (2300-2500r / min):

[0132] High shear force: During the emulsification process, sufficiently high shear force is required to form a stable emulsion. Setting a higher stirring speed can produce smaller droplets, thereby increasing the contact area between the droplets, helping the stabilizer to cover the droplet surface more effectively and preventing the droplets from aggregating.

[0133] Rapid dispersion: High-speed stirring helps to quickly and evenly disperse additives such as silane, stabilizer and dimethylethanolamine in the polyester dispersion, ensuring that these additives can play an effective role and improve the uniformity and stability of emulsification.

[0134] Heat and mass transfer: High-speed stirring can promote the uniform distribution of heat and materials, which is beneficial to the control of reaction temperature and the reaction kinetics of materials, thereby obtaining products with consistent performance.

[0135] Preferably, in step S2, in the first dispersion operation, the mixer speed is 200-300r / min, and the dispersion time is 2-3 minutes; in the second dispersion operation, the mixer speed is 2000-2100r / min. First dispersion operation (200-300r / min, 2-3 minutes): low-speed stirring: In the initial dispersion stage, a lower speed is used to avoid introducing too much air and avoid splashing of materials. The purpose of this stage is to mix PPG1000 and Laponite RD rheological additives with water to achieve initial wetting and dispersion, laying the foundation for subsequent high-speed dispersion.

[0136] Short-time stirring: A short time is sufficient to complete the initial mixing. Too long stirring may cause structural damage to the material or unnecessary energy consumption.

[0137] Second dispersion operation (2000-2100r / min): High-speed stirring: At this stage, a higher speed is required to achieve complete dispersion and activation of Laponite RD rheological additive. This high-speed stirring can break up any particle agglomeration and ensure the uniform distribution of the thixotropic agent in the coating, thereby improving the consistency and stability of the coating.

[0138] Enhanced thixotropy: Good dispersion can ensure that the thixotropic agent fully develops its layered structure, maximizes its thixotropic effect in the coating, improves the rheological properties of the coating, and enables it to exhibit better wall-hanging and anti-drip properties during the application process.

[0139] Preferably, in step S2, the parameters of PPG1000 are as follows: color Pt-Co ≤ 20; hydroxyl value 102-125 mgKOH / g; molecular weight 900-1100; acid value ≤ 0.5 mgKOH / g; moisture ≤ 0.5%; pH value (1% aqueous solution) 5.0-7.0;

[0140] The parameters of Laponite RD rheological additive are as follows: bulk density is 1000kg / m 3 ; Specific surface area (BET) is 370m 2 / g; pH (2% aqueous dispersion) is 9.8; chemical composition (dry powder ratio) silicon dioxide is 59.5%; chemical composition (dry powder ratio) magnesium oxide is 27.5%; chemical composition (dry powder ratio) lithium oxide is 0.8%; chemical composition (dry powder ratio) sodium oxide is 2.8%; chemical composition (dry powder ratio) loss on ignition is 8.2%.

[0141] Preferably, in step S3, the parameters of TEGO Wet 270 wetting agent are as follows: chemical composition: polyether siloxane copolymer; viscosity at 25° C.: 50 mPa.s; active matter content ≥ 99%;

[0142] The parameters of TEGO Glide 450 leveling agent are as follows: Chemical composition: polyether siloxane; Active substance content: 100%.

[0143] The parameter requirements of the additives TEGO Wet 270 wetting agent and TEGO Glide 450 leveling agent are to ensure the performance and consistency of the final product. The following is an analysis of the reasons for the specific parameter requirements:

[0144] TEGO Wet 270 wetting agent: Chemical composition (polyether siloxane copolymer): Polyether siloxane copolymer is an excellent surfactant that can effectively reduce the surface tension in water-based coating systems. This chemical structure helps the coating to better wet and spread on various substrates, especially non-polar or low-energy surfaces such as plastics or metals.

[0145] Viscosity (50mPa.s at 25°C): The setting of viscosity affects the fluidity and workability of the coating. Moderate viscosity helps the wetting agent to be quickly and evenly distributed in the coating without causing excessive thickening or dilution of the coating, thereby maintaining the workability and final appearance of the coating.

[0146] Active content (≥99%): A high active content indicates that the wetting agent contains a high proportion of effective ingredients with little to no impurities or fillers. This ensures that the wetting agent is more effective and consistent, helping to reduce the amount required, thereby reducing costs and potential environmental impact.

[0147] TEGO Glide 450 leveling agent: Chemical composition (polyether siloxane): Polyether siloxane as a leveling agent can effectively reduce the formation of bubbles and surface defects such as brush marks and orange peel during coating application. This chemical structure optimizes the appearance of the coating and provides a smoother and more uniform surface.

[0148] Active substance content (100%): 100% active substance content means that the leveling agent is composed entirely of active ingredients without any solvents or inactive extenders. This high purity ensures that the leveling agent is maximized in the coating while reducing potential impacts on the environment and human health.

[0149] The strict requirements of these parameters ensure the performance of wetting agents and leveling agents during the preparation process, as well as their final effect in environmentally friendly bio-based automotive topcoats, in line with environmentally friendly and high-performance coating standards. By setting these specific chemical and physical parameters, product quality control can be more stringent, ensuring consistency between batches, thus meeting the high standards of industrial production and application.

[0150] Preferably, in step S3, in the first stirring operation, the stirring speed is 300-310 r / min, and the stirring time is 5-6 minutes;

[0151] In the second mixing operation, the mixing speed is 500-510r / min and the mixing time is 10-12 minutes;

[0152] In the third mixing operation, the mixing speed is 1000-1050r / min / min, and the mixing time is 30-32 minutes;

[0153] In the fourth mixing operation, the mixing speed is 400-410 r / min, and the mixing time is 10-12 minutes;

[0154] In the fifth mixing operation, the mixing speed is 400-410 / min, and the mixing time is 15-16 minutes.

[0155] In the process of preparing environmentally friendly bio-based automotive topcoat, the stirring speed and stirring time are precisely controlled in each step. The setting of these parameters is very critical because they directly affect the uniformity, dispersion and completeness of the chemical reaction of the final product. The following are the specific reasons for each stirring stage:

[0156] First stirring operation: This stage is mainly for the preliminary mixing of liquid ingredients such as diethylene glycol butyl ether, ethylene glycol butyl ether and pure water. A lower stirring speed is sufficient to mix these components evenly, while a shorter stirring time is to avoid excessive shear force, which may cause early changes in molecular structure or unnecessary temperature rise.

[0157] Second stirring operation: After the amino resin is added, a higher stirring speed is required to ensure that these solid ingredients are fully integrated with the liquid matrix. The increased stirring time helps the amino resin to be fully dispersed and begin to react with other chemicals to form the desired polymer network structure.

[0158] The third stirring operation: This step is the most critical in the entire preparation process and involves the addition of wetting agents and defoamers. High-speed stirring is necessary to ensure that these additives can be quickly and thoroughly dispersed throughout the coating system, eliminating any potential aggregates or bubbles, thereby optimizing the surface quality and performance of the coating.

[0159] Fourth stirring operation: At this stage, the water-based bio-based acrylate modified polyester dispersion is added, and a slower stirring speed is required to maintain the structural stability of the dispersion and avoid physical shear damage caused by high-speed stirring. Moderate stirring time is sufficient to achieve sufficient mixing.

[0160] Fifth stirring operation: This is the final stirring stage, mainly to add colorants and thixotropes and ensure that they are evenly distributed throughout the paint. Similar to the fourth stirring, use the same speed to avoid damaging sensitive colorant particles and thixotropes.

[0161] In summary, the speed and time settings of each mixing step are designed to optimize the efficiency of chemical reactions, improve physical properties such as dispersion and stability, and ensure that the performance of the final product meets the expected standards. These finely tuned parameters are critical to ensuring consistency and controllability of the production process.

[0162] Compared with the prior art, the preparation method of the water-based environmentally friendly bio-based automobile topcoat has the following beneficial effects:

[0163] 1. Environmental protection: The raw materials used in the present invention, such as bio-based diols and bio-based dibasic acids, have a 100% 14C bio-based content, and bio-based 2-octyl acrylate has a 73% bio-based content, indicating that these compounds are basically completely derived from renewable resources and meet the goal of sustainable development; a water-based acrylate-modified polyester resin dispersion is used, and compared with traditional solvent-based coatings, the VOC emissions of this topcoat during the application process are significantly reduced.

[0164] 2. High performance: The preparation method includes the steps of synthesizing a water-based acrylate-modified polyester resin dispersion to ensure that the coating has excellent weather resistance, abrasion resistance and chemical corrosion resistance. These characteristics enable the topcoat to maintain its performance in various harsh environments and extend the service life of the automotive surface.

[0165] 3. Excellent adhesion and stability: By using silane and specific stabilizers, the topcoat not only has strong adhesion, but also remains stable in humid or changeable weather conditions. This feature is particularly suitable for automotive paint, which can effectively protect the car body and reduce the need for repairs and repainting.

[0166] 4. Good operability and application effect: The unique emulsification technology and emulsifier are used to ensure the uniformity of the coating and the smoothness during coating. At the same time, the addition of rheological additives and leveling agents further optimizes the coating process, making the coating smoother and more beautiful, and improving the market competitiveness of the product.

[0167] 5. Efficient preparation process: Through precise temperature setting, as well as multi-stage stirring and dispersing process, the coating components are guaranteed to be uniform and stable, which is crucial to achieving high yield and high quality of the final product.

[0168] 6. Customizability and Adjustability: Multiple steps in the preparation method allow adjustments in the proportion of ingredients and processing to suit different performance requirements and application needs. For example, by changing the ratio of color paste and thixotropic agent, the color depth and viscosity of the coating can be adjusted to meet specific aesthetic and application requirements. DETAILED DESCRIPTION

[0169] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments. Specific embodiment one:

[0171] A method for preparing an environmentally friendly bio-based automobile topcoat comprises the following steps:

[0172] S1 Synthesis of water-based bio-based acrylate modified polyester dispersion: S1.1 Esterification reaction: By weight, 255 parts of bio-based diol, 233 parts of bio-based dibasic acid and 2 parts of ester catalyst are put into a reactor to form a mixture; the temperature in the reactor is heated to 130°C, and after the mixture is completely melted, nitrogen is introduced and stirred; then the temperature in the reactor is gradually raised to 235°C, and the heating time is 4 hours; the reaction is kept warm for 3 hours; the reaction generates bio-based polyester diol.

[0173] The bio-based diol has a 100% 14C bio-based content, specifically at least one of 1,2-propylene glycol, 1,4-butylene glycol, 1,9-nonanediol, and 1,10-decanediol;

[0174] The bio-based dibasic acid has a 100% 14C bio-based content, specifically at least one of azelaic acid, sebacic acid, and dodecanedioic acid;

[0175] The ester catalyst is TYZOR BTP polybutyl titanate;

[0176] S1.2 Introducing unsaturated monomers: lowering the temperature in the reactor to 180°C; adding 100 parts of bio-based 2-octyl acrylate and 1 part of a catalyst to the reactor to react until the acid value is ≤5 mgKOH / g; lowering the temperature in the reactor to 160°C, adding 22 parts of trimellitic anhydride, and carrying out a heat-insulating reaction until the acid value is 25-30 mgKOH / g; finally removing the small molecule prepolymer by vacuum decompression to obtain a water-based bio-based acrylate-modified polyester resin;

[0177] The catalyst is di-tert-butyl peroxide;

[0178] S1.3 Emulsification: Lower the temperature in the reactor to 110°C; gradually add 60 parts of ethylene glycol butyl ether and 295 parts of pure water while stirring at a speed of 2300r / min, and disperse at high speed for 30 minutes. Lower the temperature to 82°C, add 22 parts of silane, 3 parts of stabilizer and 17 parts of dimethylethanolamine, keep warm for 3 hours, cool to room temperature and filter. Cool the temperature in the reactor to room temperature and filter to obtain a water-based bio-based acrylate modified polyester dispersion;

[0179] The silane is 3-isocyanatepropyltrimethoxysilane;

[0180] The stabilizer is a mixture of polyoxyethylene sorbitan fatty acid ester and sorbitan tristearate, wherein the weight ratio of polyoxyethylene sorbitan fatty acid ester to sorbitan tristearate is 7:3;

[0181] S2 Preparation of thixotropic agent: Add 99.7 parts of pure water and 0.1 parts of PPG1000 into a blender, use a dispersion disk to disperse for 3 minutes at 200-300r / min, then slowly add 0.2 parts of Laponite RD rheological additive, increase the speed to 2000r / min, and disperse for 20 minutes until the solution is clear and transparent.

[0182] S3 topcoat ingredients mixing and homogenization: Add diethylene glycol butyl ether, ethylene glycol butyl ether and pure water into a mixer, start stirring, stir at 300r / min for 5 minutes, then add amino resin, stir at 500r / min for 10 minutes. Increase the speed to 1000r / min, add wetting agent and defoamer, and stir for 30 minutes. Reduce the speed to 400r / min, add water-based bio-based acrylate modified polyester dispersion, stir for 10 minutes, add color paste and thixotropic agent, stir for 15 minutes to obtain environmentally friendly bio-based automotive topcoat.

[0183] By weight, the waterborne bio-based acrylate modified polyester dispersion: amino resin: color paste: thixotropic agent: diethylene glycol butyl ether: ethylene glycol butyl ether: wetting agent: leveling agent: pure water is 55:11:13:4:3:3:0.3:0.3:10.4;

[0184] The wetting agent is specifically TEGO Wet 270 wetting agent; the leveling agent is specifically TEGO Glide 450 leveling agent.

[0185] In step S1.1, 100% 14C biobased content means that all carbon atoms come from biobased sources, which are biodegradable or renewable raw materials;

[0186] The parameters of TYZOR BTP polybutyl titanate are as follows: viscosity (25° C.) is 2000-6000 mPas; active content is 100%; titanium dioxide content is 34-35%.

[0187] In step S1.2, the bio-based 2-octyl acrylate has a 14C bio-based content of 73%.

[0188] In step S2, the parameters of PPG1000 are as follows: color Pt-Co ≤ 20; hydroxyl value 102-125 mgKOH / g; molecular weight 900-1100; acid value ≤ 0.5 mgKOH / g; moisture ≤ 0.5%; pH value (1% aqueous solution) 5.0-7.0;

[0189] The parameters of Laponite RD rheological additive are as follows: bulk density is 1000kg / m 3 ; Specific surface area (BET) is 370m 2 / g; pH (2% aqueous dispersion) is 9.8; chemical composition (dry powder ratio) silicon dioxide is 59.5%; chemical composition (dry powder ratio) magnesium oxide is 27.5%; chemical composition (dry powder ratio) lithium oxide is 0.8%; chemical composition (dry powder ratio) sodium oxide is 2.8%; chemical composition (dry powder ratio) loss on ignition is 8.2%.

[0190] In step S3, the parameters of TEGO Wet 270 wetting agent are as follows: chemical composition: polyether siloxane copolymer; viscosity at 25°C: 50 mPa.s; active matter content ≥ 99%;

[0191] The parameters of TEGO Glide 450 leveling agent are as follows: Chemical composition: polyether siloxane; Active substance content: 100%. Specific embodiment 2:

[0193] A method for preparing an environmentally friendly bio-based automobile topcoat comprises the following steps:

[0194] S1 Synthesis of water-based bio-based acrylate modified polyester dispersion: S1.1 Esterification reaction: By weight, 265 parts of bio-based diol, 235 parts of bio-based dibasic acid and 3 parts of ester catalyst are put into a reactor to form a mixture; the temperature in the reactor is heated to 130°C, and after the mixture is completely melted, nitrogen is introduced and stirred; then the temperature in the reactor is gradually raised to 235°C, and the heating time is 4 hours; the reaction is kept warm for 3 hours; the reaction generates bio-based polyester diol.

[0195] The bio-based diol has a 100% 14C bio-based content, specifically at least one of 1,2-propylene glycol, 1,4-butylene glycol, 1,9-nonanediol, and 1,10-decanediol;

[0196] The bio-based dibasic acid has a 100% 14C bio-based content, specifically at least one of azelaic acid, sebacic acid, and dodecanedioic acid;

[0197] The ester catalyst is TYZOR BTP polybutyl titanate;

[0198] S1.2 Introducing unsaturated monomers: lowering the temperature in the reactor to 180°C; adding 90 parts of bio-based 2-octyl acrylate and 1 part of a catalyst to the reactor to react until the acid value is ≤5 mgKOH / g; lowering the temperature in the reactor to 160°C, adding 25 parts of trimellitic anhydride, and carrying out a heat-insulating reaction until the acid value is 25-30 mgKOH / g; finally removing the small molecule prepolymer by vacuum decompression to obtain a water-based bio-based acrylate modified polyester resin;

[0199] The catalyst is di-tert-butyl peroxide;

[0200] S1.3 Emulsification: Lower the temperature in the reactor to 110°C; gradually add 65 parts of ethylene glycol butyl ether and 270 parts of pure water while stirring at a speed of 2300r / min, and disperse at high speed for 30 minutes. Lower the temperature to 82°C, add 25 parts of silane, 3 parts of stabilizer and 18 parts of dimethylethanolamine, keep warm for 3 hours, cool to room temperature and filter. Cool the temperature in the reactor to room temperature and filter to obtain a water-based bio-based acrylate modified polyester dispersion;

[0201] The silane is 3-isocyanatepropyltrimethoxysilane;

[0202] The stabilizer is a mixture of polyoxyethylene sorbitan fatty acid ester and sorbitan tristearate, wherein the weight ratio of polyoxyethylene sorbitan fatty acid ester to sorbitan tristearate is 7:3;

[0203] S2 Preparation of thixotropic agent: Add 99.7 parts of pure water and 0.1 parts of PPG1000 into a blender, use a dispersion disk to disperse for 3 minutes at 200-300r / min, then slowly add 0.2 parts of Laponite RD rheological additive, increase the speed to 2000r / min, and disperse for 20 minutes until the solution is clear and transparent.

[0204] S3 topcoat ingredients mixing and homogenization: Add diethylene glycol butyl ether, ethylene glycol butyl ether and pure water into a mixer, start stirring, stir at 300r / min for 5 minutes, then add amino resin, stir at 500r / min for 10 minutes. Increase the speed to 1000r / min, add wetting agent and defoamer, and stir for 30 minutes. Reduce the speed to 400r / min, add water-based bio-based acrylate modified polyester dispersion, stir for 10 minutes, add color paste and thixotropic agent, stir for 15 minutes to obtain environmentally friendly bio-based automotive topcoat.

[0205] By weight, the waterborne bio-based acrylate modified polyester dispersion: amino resin: color paste: thixotropic agent: diethylene glycol butyl ether: ethylene glycol butyl ether: wetting agent: leveling agent: pure water is 55:11:13:4:3:3:0.3:0.3:10.4;

[0206] The wetting agent is specifically TEGO Wet 270 wetting agent; the leveling agent is specifically TEGO Glide 450 leveling agent.

[0207] In step S1.1, 100% 14C biobased content means that all carbon atoms come from biobased sources, which are biodegradable or renewable raw materials;

[0208] The parameters of TYZOR BTP polybutyl titanate are as follows: viscosity (25° C.) is 2000-6000 mPas; active content is 100%; titanium dioxide content is 34-35%.

[0209] In step S1.2, the bio-based 2-octyl acrylate has a 14C bio-based content of 73%.

[0210] In step S2, the parameters of PPG1000 are as follows: color Pt-Co ≤ 20; hydroxyl value 102-125 mgKOH / g; molecular weight 900-1100; acid value ≤ 0.5 mgKOH / g; moisture ≤ 0.5%; pH value (1% aqueous solution) 5.0-7.0;

[0211] The parameters of Laponite RD rheological additive are as follows: bulk density is 1000kg / m 3 ; Specific surface area (BET) is 370m 2 / g; pH (2% aqueous dispersion) is 9.8; chemical composition (dry powder ratio) silicon dioxide is 59.5%; chemical composition (dry powder ratio) magnesium oxide is 27.5%; chemical composition (dry powder ratio) lithium oxide is 0.8%; chemical composition (dry powder ratio) sodium oxide is 2.8%; chemical composition (dry powder ratio) loss on ignition is 8.2%.

[0212] In step S3, the parameters of TEGO Wet 270 wetting agent are as follows: chemical composition: polyether siloxane copolymer; viscosity at 25°C: 50 mPa.s; active matter content ≥ 99%;

[0213] The parameters of TEGO Glide 450 leveling agent are as follows: Chemical composition: polyether siloxane; Active substance content: 100%. Specific embodiment three:

[0215] A method for preparing an environmentally friendly bio-based automobile topcoat comprises the following steps:

[0216] S1 Synthesis of water-based bio-based acrylate modified polyester dispersion: S1.1 Esterification reaction: By weight, 265 parts of bio-based diol, 225 parts of bio-based dibasic acid and 2 parts of ester catalyst are put into a reactor to form a mixture; the temperature in the reactor is heated to 130°C, and after the mixture is completely melted, nitrogen is introduced and stirred; then the temperature in the reactor is gradually raised to 235°C, and the heating time is 4 hours; the reaction is kept warm for 3 hours; the reaction generates bio-based polyester diol.

[0217] The bio-based diol has a 100% 14C bio-based content, specifically at least one of 1,2-propylene glycol, 1,4-butylene glycol, 1,9-nonanediol, and 1,10-decanediol;

[0218] The bio-based dibasic acid has a 100% 14C bio-based content, specifically at least one of azelaic acid, sebacic acid, and dodecanedioic acid;

[0219] The ester catalyst is TYZOR BTP polybutyl titanate;

[0220] S1.2 Introducing unsaturated monomers: lowering the temperature in the reactor to 180°C; adding 95 parts of bio-based 2-octyl acrylate and 2 parts of a catalyst into the reactor to react until the acid value is ≤5 mgKOH / g; lowering the temperature in the reactor to 160°C, adding 24 parts of trimellitic anhydride, and carrying out a heat-insulating reaction until the acid value is 25-30 mgKOH / g; finally removing the small molecule prepolymer by vacuum decompression to obtain a water-based bio-based acrylate-modified polyester resin;

[0221] The catalyst is di-tert-butyl peroxide;

[0222] S1.3 Emulsification: Lower the temperature in the reactor to 110°C; gradually add 57 parts of ethylene glycol butyl ether and 278 parts of pure water while stirring at a speed of 2300r / min, and disperse at high speed for 30 minutes. Lower the temperature to 82°C, add 27 parts of silane, 5 parts of stabilizer and 20 parts of dimethylethanolamine, keep warm for 3 hours, cool to room temperature and filter. Cool the temperature in the reactor to room temperature and filter to obtain a water-based bio-based acrylate modified polyester dispersion;

[0223] The silane is 3-isocyanatepropyltrimethoxysilane;

[0224] The stabilizer is a mixture of polyoxyethylene sorbitan fatty acid ester and sorbitan tristearate, wherein the weight ratio of polyoxyethylene sorbitan fatty acid ester to sorbitan tristearate is 7:3;

[0225] S2 Preparation of thixotropic agent: Add 99.7 parts of pure water and 0.1 parts of PPG1000 into a blender, use a dispersion disk to disperse for 3 minutes at 200-300r / min, then slowly add 0.2 parts of Laponite RD rheological additive, increase the speed to 2000r / min, and disperse for 20 minutes until the solution is clear and transparent.

[0226] S3 topcoat ingredients mixing and homogenization: Add diethylene glycol butyl ether, ethylene glycol butyl ether and pure water into a mixer, start stirring, stir at 300r / min for 5 minutes, then add amino resin, stir at 500r / min for 10 minutes. Increase the speed to 1000r / min, add wetting agent and defoamer, and stir for 30 minutes. Reduce the speed to 400r / min, add water-based bio-based acrylate modified polyester dispersion, stir for 10 minutes, add color paste and thixotropic agent, stir for 15 minutes to obtain environmentally friendly bio-based automotive topcoat.

[0227] By weight, the waterborne bio-based acrylate modified polyester dispersion: amino resin: color paste: thixotropic agent: diethylene glycol butyl ether: ethylene glycol butyl ether: wetting agent: leveling agent: pure water is 55:10:13:4:3:3:0.3:0.3:11.4;

[0228] The wetting agent is specifically TEGO Wet 270 wetting agent; the leveling agent is specifically TEGO Glide 450 leveling agent.

[0229] In step S1.1, 100% 14C biobased content means that all carbon atoms come from biobased sources, which are biodegradable or renewable raw materials;

[0230] The parameters of TYZOR BTP polybutyl titanate are as follows: viscosity (25° C.) is 2000-6000 mPas; active content is 100%; titanium dioxide content is 34-35%.

[0231] In step S1.2, the bio-based 2-octyl acrylate has a 14C bio-based content of 73%.

[0232] In step S2, the parameters of PPG1000 are as follows: color Pt-Co ≤ 20; hydroxyl value 102-125 mgKOH / g; molecular weight 900-1100; acid value ≤ 0.5 mgKOH / g; moisture ≤ 0.5%; pH value (1% aqueous solution) 5.0-7.0;

[0233] The parameters of Laponite RD rheological additive are as follows: bulk density is 1000kg / m 3 ; Specific surface area (BET) is 370m 2 / g; pH (2% aqueous dispersion) is 9.8; chemical composition (dry powder ratio) silicon dioxide is 59.5%; chemical composition (dry powder ratio) magnesium oxide is 27.5%; chemical composition (dry powder ratio) lithium oxide is 0.8%; chemical composition (dry powder ratio) sodium oxide is 2.8%; chemical composition (dry powder ratio) loss on ignition is 8.2%.

[0234] In step S3, the parameters of TEGO Wet 270 wetting agent are as follows: chemical composition: polyether siloxane copolymer; viscosity at 25°C: 50 mPa.s; active matter content ≥ 99%;

[0235] The parameters of TEGO Glide 450 leveling agent are as follows: Chemical composition: polyether siloxane; Active substance content: 100%.

[0236] The environmentally friendly bio-based automotive paint topcoat prepared in specific examples 1-3 was sprayed with an automatic spray gun, and the parameters of the automatic spray gun were set as follows: the air pressure was 3-3.5KG / CM2, and it was sprayed on the wet-on-wet mid-coat plate made by patent number 202410574956.6, and the spraying thickness was 20-30μm. The sprayed product was flash-dried at 70℃ for 15 minutes or 80℃ for 10 minutes before the next spraying operation. The forced drying condition was 140℃, baked for 45 minutes, and taken out and placed at room temperature after drying. Its performance test was as follows:

[0237]

[0238] Analyze the implementation examples of each project:

[0239] Adhesion: The standard requires the use of 2mm cross-cut method to test and reach level 0.

[0240] Examples 1, 2, and 3 all meet the standard requirements, indicating that the paint surface has good adhesion to the substrate and there is no peeling phenomenon.

[0241] hardness:

[0242] The standard requires the hardness to be no less than HB (Mitsubishi pencil), 750g.

[0243] Examples 1, 2, and 3 all achieved H-grade hardness, meeting standard requirements, indicating that the paint film had good hardness characteristics.

[0244] Flexibility: The standard requires no damage such as reticulation, cracks, and peeling.

[0245] There was no damage in Examples 1, 2, and 3, indicating that the paint film has good flexibility and can withstand a certain degree of deformation without damage.

[0246] Impact resistance: The standard requires that the impact resistance should be no less than 30cm, and there should be no cracks or wrinkles on the surface of the paint film.

[0247] Examples 1, 2, and 3 all meet the standard requirements, and the paint films withstand impact tests at room temperature without cracks or wrinkles.

[0248] Test conclusion:

[0249] The invention discloses a method for preparing an environmentally friendly bio-based automobile original paint topcoat. The topcoat produced by the method has not only strong adhesion, but also good hardness, strong flexibility and impact resistance. At the same time, due to the use of water-based environmentally friendly bio-based resin, the emission of harmful volatiles can be effectively avoided, thereby achieving a dual improvement in environmental protection and product performance.

[0250] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for preparing a water-based environmentally friendly bio-based automotive topcoat, It is characterized in that The preparation method of water-based environmentally friendly bio-based automobile topcoat comprises the following steps: S1 Synthesis of water-based bio-based acrylate modified polyester dispersion: S1.1 Esterification reaction: by weight, 245-275 parts of bio-based diol, 210-240 parts of bio-based dibasic acid and 1-5 parts of ester catalyst are added into a reactor to form a mixed material; the temperature in the reactor is heated to 120-130°C, and after the mixed material is completely melted, nitrogen is introduced and stirred; then the temperature in the reactor is heated to 230-240°C and kept warm; after the esterification reaction is completed, the bio-based polyester diol is obtained; The bio-based diol has a 100% 14C bio-based content, specifically at least one of 1,2-propylene glycol, 1,4-butylene glycol, 1,9-nonanediol, and 1,10-decanediol; The bio-based dibasic acid has a 100% 14C bio-based content, specifically at least one of azelaic acid, sebacic acid, and dodecanedioic acid; The ester catalyst model is TYZOR BTP polybutyl titanate; S1.2 Introducing unsaturated monomers: lowering the temperature in the reactor to 180-190°C; adding 80-100 parts of bio-based 2-octyl acrylate and 1-3 parts of a catalyst to the reactor to react until the acid value is ≤5 mgKOH / g; lowering the temperature in the reactor to 160-165°C, adding 20-30 parts of trimellitic anhydride, and carrying out a heat-insulating reaction until the acid value is 25-30 mgKOH / g; finally removing the small molecule prepolymer by vacuum decompression to obtain a water-based bio-based acrylate modified polyester resin; The catalyst is di-tert-butyl peroxide; S1.3 Emulsification: lowering the temperature in the reactor to 100-110°C; then stirring, adding 50-70 parts of ethylene glycol butyl ether and 270-300 parts of pure water to the reactor during stirring, stirring for 20-30 minutes, lowering the temperature in the reactor to 78-82°C, then adding 20-30 parts of silane, 3-5 parts of stabilizer and 15-25 parts of dimethylethanolamine, and keeping warm for 2-3 hours, cooling the temperature in the reactor to room temperature and filtering to obtain an aqueous bio-based acrylate modified polyester dispersion; The silane is 3-isocyanatepropyltrimethoxysilane; The stabilizer is a mixture of polyoxyethylene sorbitan fatty acid ester and sorbitan tristearate, wherein the weight ratio of polyoxyethylene sorbitan fatty acid ester to sorbitan tristearate is 7:3; S2 Preparation of thixotropic agent: pure water and PPG1000 are added to the mixer to perform the first dispersion operation; after the first dispersion operation, a rheological additive of model Laponite RD is added; the speed is increased and the second dispersion operation is performed until the solution is clear and transparent. The mixer is equipped with a dispersion disk; According to the weight ratio, pure water:PPG1000:Laponite RD rheological additive is 99.7:0.1:0.2; S3 topcoat component mixing and homogenization: diethylene glycol butyl ether, ethylene glycol butyl ether and pure water are put into a mixer to perform the first stirring operation; after the first stirring operation, amino resin is added, the stirring speed is increased, and the second stirring operation is performed; after the second stirring operation, a wetting agent and a defoaming agent are added, the stirring speed is continued to be increased, and the third stirring operation is performed; after the third stirring operation is completed, a water-based bio-based acrylate modified polyester dispersion is added, the stirring speed is reduced, and the fourth stirring operation is performed; after the fourth stirring operation is completed, a color paste and a thixotropic agent are added, and a fifth stirring operation is performed. After the fifth stirring operation is completed, a water-based environmentally friendly bio-based automotive topcoat is obtained; By weight, the waterborne bio-based acrylate modified polyester dispersion: amino resin: color paste: thixotropic agent: diethylene glycol butyl ether: ethylene glycol butyl ether: wetting agent: leveling agent: pure water is 50-60: 8-12: 12-20: 2-5: 2-3: 2-3: 0.2-0.5: 0.2-0.5: 10-20; The specific model of the wetting agent is TEGO Wet 270 wetting agent; the specific model of the leveling agent is TEGO Glide450 leveling agent.

2. The method for preparing the water-based environmentally friendly bio-based automotive topcoat according to claim 1, It is characterized in that In step S1.1, the heating time is 4-5 hours, and the holding time is 2-4 hours; 100% 14C biobased content means that all carbon atoms come from biobased sources, which are biodegradable or renewable raw materials; The parameters of TYZOR BTP polybutyl titanate are as follows: viscosity (25° C.) is 2000-6000 mPas; active content is 100%; titanium dioxide content is 34-35%.

3. The method for preparing the water-based environmentally friendly bio-based automotive topcoat according to claim 1, It is characterized in that In step S1.2, the bio-based 2-octyl acrylate has a 14C bio-based content of 73%.

4. The method for preparing the water-based environmentally friendly bio-based automotive topcoat according to claim 1, It is characterized in that In step S1.3, the stirring speed is set to 2300-2500 r / min.

5. The method for preparing the water-based environmentally friendly bio-based automotive topcoat according to claim 1, It is characterized in that In step S2, in the first dispersing operation, the speed of the mixer is 200-300 r / min, and the dispersing time is 2-3 minutes; in the second dispersing operation, the speed of the mixer is 2000-2100 r / min.

6. The method for preparing the water-based environmentally friendly bio-based automotive topcoat according to claim 1, It is characterized in that In step S2, the parameters of PPG1000 are as follows: color Pt-Co ≤ 20; hydroxyl value 102-125 mgKOH / g; molecular weight 900-1100; acid value ≤ 0.5 mgKOH / g; moisture ≤ 0.5%; pH value (1% aqueous solution) 5.0-7.0; The parameters of Laponite RD rheological additive are as follows: bulk density is 1000kg / m 3 ; Specific surface area (BET) is 370m 2 / g; pH (2% aqueous dispersion) is 9.8; chemical composition (dry powder ratio) silicon dioxide is 59.5%; chemical composition (dry powder ratio) magnesium oxide is 27.5%; chemical composition (dry powder ratio) lithium oxide is 0.8%; chemical composition (dry powder ratio) sodium oxide is 2.8%; chemical composition (dry powder ratio) loss on ignition is 8.2%.

7. The method for preparing the water-based environmentally friendly bio-based automobile topcoat according to claim 1, It is characterized in that In step S3, the parameters of TEGO Wet 270 wetting agent are as follows: chemical composition: polyether siloxane copolymer; viscosity at 25°C: 50 mPa.s; active matter content ≥ 99%; The parameters of TEGO Glide 450 leveling agent are as follows: Chemical composition: polyether siloxane; Active substance content: 100%.

8. The method for preparing the water-based environmentally friendly bio-based automobile topcoat according to claim 1, It is characterized in that In step S3, in the first stirring operation, the stirring speed is 300-310 r / min, and the stirring time is 5-6 minutes; In the second mixing operation, the mixing speed is 500-510r / min and the mixing time is 10-12 minutes; In the third mixing operation, the mixing speed is 1000-1050r / min / min, and the mixing time is 30-32 minutes; In the fourth mixing operation, the mixing speed is 400-410 r / min, and the mixing time is 10-12 minutes; In the fifth mixing operation, the mixing speed is 400-410 / min, and the mixing time is 15-16 minutes.

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