A method for preparing a high gloss waterborne aluminum silver paste self-laminating coating

Abstract

The application discloses a preparation method of high-light water-based aluminum silver paste self-laminating paint, relates to the technical field of paint preparation, and comprises the following steps: adding water-based resin and modified silicon resin into a high-speed dispersion kettle, preliminarily mixing the water-based resin and the modified silicon resin after stirring to form a resin base, adding organic silicon additives, a thickening agent and a pH regulator into the resin base in sequence, stirring and adjusting the viscosity and the pH value of the system, immersing a substrate to be coated in an alkali solution of hydroxyl ions to remove surface grease and a loose layer, washing the substrate with water, immersing the substrate in an acid solution of hydrogen ions for treatment, finally washing the substrate with water and drying the substrate, removing residual solvents and moisture from the cooled reflection layer by soft drying, and obtaining the water-based aluminum silver paste paint with a self-laminating structure. According to the preparation method, the high-light water-based aluminum silver paste paint with the self-laminating structure is prepared by optimizing filler modification, resin proportioning, surface treatment and heating processes, and the paint can provide excellent reflection performance, and ensure the stability, uniformity and adhesion of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, specifically to a method for preparing a high-gloss water-based aluminum silver paste self-layering coating. Background Technology

[0002] Aluminum silver paint is widely used in many fields such as automotive paint, motorcycle paint, bicycle paint, plastic paint, architectural coatings, inks, mobile phone casings and buttons, electromechanical casings, and metallic paints. However, traditional aluminum silver paste coatings still have some problems in terms of performance and application effect that need to be solved.

[0003] From a coating structure perspective, existing water-based aluminum silver paste coatings often struggle to form a stable and ideal self-layering structure. During the coating process, aluminum silver paste particles have difficulty migrating and accumulating on the coating surface, resulting in poor uniformity and stability of the reflective layer, which affects the coating's gloss and decorative effect. For example, in some high-end decorative fields with extremely high gloss requirements, such as automotive interior parts and high-end furniture surface coatings, ordinary water-based aluminum silver paste coatings cannot meet their requirements for high reflectivity and durability of the reflective layer.

[0004] Traditional preparation methods have several limitations. Firstly, pretreatment of fillers may not adequately improve their compatibility with the resin matrix, leading to uneven dispersion of the filler in the resin and consequently affecting the overall performance of the coating, such as mechanical strength and wear resistance. Secondly, the control of parameters such as temperature and time during existing coating and curing processes is not precise enough, making it difficult to achieve the ideal melt flow state of the modified silicone resin and film-forming aids. This hinders effective self-stratification of the aluminum silver paste particles and sufficient intermolecular cross-linking, ultimately resulting in coating performance that falls short of expectations. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a high-gloss waterborne aluminum silver paste self-layering coating. By optimizing filler modification, resin ratio, surface treatment and heating process, a high-gloss waterborne aluminum silver paste coating with a self-layering structure is prepared, which can provide excellent reflective performance while ensuring the stability, uniformity and adhesion of the coating.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a high-gloss water-based aluminum silver paste self-layering coating, the preparation method comprising the following steps:

[0007] S100: The filler and PDA-silane coupling agent are dispersed in deionized water and ultrasonically treated to uniformly coat the surface of the filler with a modified layer, forming a modified filler dispersion.

[0008] S200: Add water-based resin and modified silicone resin to a high-speed dispersion kettle, stir, and then mix to form a resin base material;

[0009] S300: Add organosilicon additives, thickeners and pH adjusters to the resin base in sequence, stir and adjust the viscosity and pH of the system;

[0010] S400: Immerse the substrate to be coated in an alkaline solution of hydroxide ions to remove surface grease and loose layer, wash with water, then immerse in an acidic solution of hydrogen ions, and finally wash with water and dry.

[0011] S500: The substrate is heated to the first melting temperature T1, and a layer of mixed slurry is uniformly coated by reverse roller coating and dried to form the bottom coating.

[0012] S600: The remaining mixed slurry is coated again on the surface of the bottom coating. After coating, the temperature is increased based on the first melting temperature T1, so that the modified silicone resin and film-forming aid in the system melt and flow, promote the aluminum silver paste particles to migrate to the surface and self-decompose, maintain the molten state and promote intermolecular cross-linking.

[0013] S700: Natural cooling allows the molten coating to gradually solidify, and aluminum silver paste particles are fixed on the surface to form a reflective layer;

[0014] S800: After cooling, the reflective layer is gently dried to remove residual solvent and moisture, resulting in a water-based aluminum silver paste coating with a self-layering structure.

[0015] In one embodiment disclosed in this application, step S200, the method for preparing the modified silicone resin includes the following steps:

[0016] S201: Side-hydrogen silicone oil is prepared using hydrogen-containing silicone oil, octamethylcyclotetrasiloxane, and hexamethyldisiloxane at a set temperature with a Karstedt catalyst;

[0017] S202: An acrylate intermediate is obtained by reacting 3-hydroxypropionic acid with unsaturated isocyanate at a set temperature in the presence of a catalyst.

[0018] S203: Using the products from steps S201 and S202, a Karstedt catalyst is added at a set temperature to carry out a hydrosilylation reaction to form the product.

[0019] S204: After neutralizing the product with triethylamine to neutral, water is added for emulsification until homogeneous to obtain modified silicone resin.

[0020] In one embodiment disclosed in this application, the main chain structure of the modified silicone resin includes a substituent R1, which contains a plurality of methylene groups as well as carboxyl and amide functional groups.

[0021] In one embodiment disclosed in this application, in step S201, the hydrogen content of the hydrogen-containing silicone oil is >1%, the Karstedt catalyst is a platinum (0)-vinylsiloxane complex, 0.2-0.4 parts by weight, and the temperature used in the preparation process of the hydrogen-containing silicone oil is 50-70°C.

[0022] In one embodiment disclosed in this application, in step S202, the temperature is set to 40-60°C and the inverse time is 3 hours.

[0023] In one embodiment disclosed in this application, in step S203, the temperature used in the product synthesis is 60-80°C, and in step S204, after adding triethylamine to neutralize the product to neutrality, water is added, with water accounting for 30% to 60% of the total mass.

[0024] In one embodiment disclosed in this application, in step S300, the organosilicon additive is BYK-346 / TEGOGlide410, 0.1-1 parts by weight; the thickener is RM-2020 / ASE-60, 0.1-1 parts by weight; the pH adjuster is DMEA / AMP-95, 0.1-0.5 parts by weight; the stirring speed is 600-800 rpm; the stirring time is 20-30 min; the viscosity of the system is adjusted to 5000-8000 mPa·s (25℃); and the pH value is 7.5-8.5.

[0025] In one embodiment disclosed in this application, in step S100: the filler is zinc phosphate or calcium carbonate, 5-10 parts by weight, the amount of PDA-silane coupling agent is 0.5 wt% of the total filler, and the ultrasonic treatment time is 3-6 hours.

[0026] In one embodiment disclosed in this application, in step S600: the temperature after coating is increased by 40-50°C, that is, it is increased to T2=T1+40~50°C, where T2 is 120-150°C.

[0027] In one embodiment disclosed in this application, in step S200, the aqueous resin is HYR-2435B, 20-35 parts by weight, the modified silicone resin is 20-35 parts by weight, the stirring speed is 300-500 rpm, and the stirring time is 15-20 min.

[0028] In one exemplary embodiment of this disclosure, during the final drying process, the cooled reflective layer is gently dried at 40-50°C for 30-60 minutes (e.g., the drying temperature can be 40°C, 45°C, or 50°C, and the drying time can be 30 minutes, 45 minutes, or 60 minutes) to thoroughly remove residual solvents and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-layering structure (aluminum silver paste-rich surface layer + resin-adhered underlayer), and strong adhesion to the substrate. This coating is suitable for automotive interiors, appliance housings, and architectural decoration, combining both decorative and functional properties.

[0029] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0030] 1. This invention uses a PDA-silane coupling agent to uniformly coat the filler surface to form a modified layer, enhancing the compatibility between the filler and the resin matrix. Ultrasonic treatment ensures a uniform coating layer on the filler surface, improving filler dispersibility and ensuring the stability and uniformity of the coating. This modified layer helps improve filler dispersibility, reduces the aggregation of aluminum silver paste particles, and thus optimizes the optical effects and physical properties of the coating.

[0031] 2. This invention combines water-based resin and modified silicone resin to form a stable resin base. Based on this, organosilicon additives, thickeners, and pH adjusters are added to effectively regulate the viscosity and pH value of the system, giving the coating excellent workability. The addition of these additives optimizes the fluidity and uniformity of the coating, ensuring good processability and adaptability.

[0032] 3. This invention improves the cleanliness and surface adhesion of the substrate by treating it with hydroxide and hydrogen ion solutions before coating, thereby removing surface grease and loose layers. The washing and drying processes further remove unnecessary impurities, providing a better foundation for coating adhesion and enhancing the bond between the coating and the substrate.

[0033] 4. In this invention, during the heating process of the coating, modified silicone resin and film-forming aids melt at a specific temperature, driving aluminum silver paste particles to migrate to the coating surface. This process, through a self-stratification effect, causes the aluminum silver paste particles to aggregate on the surface, forming a high-reflectivity layer. The self-stratification effect not only enhances reflectivity but also ensures the uniformity of the coating surface, avoiding unstable reflection effects caused by uneven particle distribution.

[0034] 5. This invention promotes intermolecular cross-linking in the molten state of the coating, resulting in better durability and scratch resistance. After the self-layered coating cools naturally, the aluminum silver paste particles are fixed to the surface, forming a reflective layer, ensuring the coating's high gloss and stable reflective properties.

[0035] 6. This invention removes residual solvents and moisture through a gentle drying process, ensuring the final coating's dryness and stability. This process ensures that no solvent residue remains during use, avoiding the negative impact of solvent evaporation on coating performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0037] Figure 1 This is a flowchart of the preparation method of the present invention.

[0038] Figure 2 This is a schematic diagram of the main chain structure of the modified silicone resin in this invention.

[0039] Figure 3 This is a schematic diagram of the structure of the substituent R1 in this invention.

[0040] Figure 4 This is a schematic diagram of the structure of the hydrosilicone oil in this invention.

[0041] Figure 5 This is a schematic diagram of the structure of the unsaturated isocyanate in this invention.

[0042] Figure 6 This is a schematic diagram of the structure of the acrylate intermediate in this invention.

[0043] Figure 7 This is a schematic diagram of the structure of the product formed after the hydrosilylation reaction in this invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In this application, the materials and process parameters are explained as follows:

[0046] I. Material Name

[0047] PDA - Polydopamine-silane-coupling agent → used to improve the compatibility of fillers with aqueous systems;

[0048] HYR-2435B is a self-drying water-based resin model.

[0049] Modified silicone resin (functional modified organosilicon resin) → The main chain contains amide bonds (-CONH-), which combines hydrophilicity and reactivity;

[0050] BYK-346 / TEGOGlide410 silicone leveling agent → optimizes coating leveling properties;

[0051] RM-2020 / ASE-60 thickener model → controls coating viscosity;

[0052] DMEA / AMP-95 pH adjuster (dimethylethanolamine / DMAE, 2-amino-2-methyl-1-propanol) → Adjust the system pH to 7.5-8.5;

[0053] Aluminum silver paste (MD-2000 / STAPA) ® Hydrolan 2150 aluminum silver paste model → provides a high-gloss reflective effect;

[0054] Film-forming aids (Texanol / PM / DPM / DPNB) Film-forming aid combination (dodecyl alcohol ester / Texanol, propylene glycol methyl ether / PM, dipropylene glycol methyl ether / DPM, dipropylene glycol butyl ether / DPNB) → promote resin film formation;

[0055] NaOH aqueous solution (sodium hydroxide aqueous solution, alkaline degreasing agent);

[0056] Dilute HCl and dilute hydrochloric acid solutions (acidic activator).

[0057] II. Process Parameters and Operation

[0058] Ultrasonic treatment → Disperses the filler material using ultrasound to prevent agglomeration;

[0059] Reverse-roll coating → The coating is transferred from the roller to the substrate in the reverse direction, achieving uniform coating;

[0060] Wet-film-thickness (WFT) → The thickness of the coating before it dries (10-15 μm).

[0061] Surface roughness Ra (Ra) → represents the arithmetic mean deviation of the micro-unevenness of the coating surface (>1.45μm).

[0062] High-temperature molten state → Heating to T2 temperature (120-150℃) allows the modified silicone resin and film-forming aids to flow;

[0063] Self-stratification → Aluminum silver paste migrates to the surface, while the water-based resin matrix sinks to form a double-layer structure;

[0064] Intermolecular-crosslinking → enhances coating density through chemical bonding at high temperatures;

[0065] Forced-air-cooling → accelerates the cooling of the coating to room temperature or ≤40°C using a fan;

[0066] Low-temperature drying → Drying at 40-50℃ to remove residual solvent and moisture.

[0067] III. Structural and Performance Parameters

[0068] Glass transition temperature (Tg) → the specific softening temperature of modified silicone resin, affecting melt flowability;

[0069] pH value → pH level of the system (7.5-8.5), balancing coating stability and substrate adhesion;

[0070] Viscosity → 5000-8000 mPa·s (25℃), controlling the workability of the coating;

[0071] Glossiness →> 90GU@60° (60° gloss unit), high gloss reflection effect

[0072] Adhesion strength → Verified by cross-cut test or tensile test;

[0073] Water resistance → resistance to water penetration and foaming.

[0074] IV. Chemical Structure and Functional Groups

[0075] Main-chain structure → polymer backbone composed of repeating siloxane units (-Si-O-Si-);

[0076] Substituent R1 → Organic groups containing amide bonds (-CONH-) and carboxyl groups (-COOH) → Enhance hydrophilicity and reactivity;

[0077] Hydrogen bond (hydrogen-bond) → the interaction force between modified silicone resin and water molecules;

[0078] Crosslinking density → the number of crosslinking points per unit volume, which affects the hardness and wear resistance of the coating.

[0079] V. Equipment and Tools

[0080] High-speed disperser → used for initial mixing of resin base materials;

[0081] Karstedt catalyst (Karstedt-catalyst) → platinum(0)-vinylsiloxane complex (platinum catalyst);

[0082] Hexamethyldisiloxane (MM) → capping agent, used to adjust the molecular weight of silicone resin;

[0083] Octamethylcyclotetrasiloxane (D4) → cyclic siloxane monomer, participating in polymerization reactions;

[0084] Triethylamine (TEA) → Neutralizing agent, used in emulsion preparation.

[0085] This application provides a method for preparing a high-gloss waterborne aluminum silver paste self-layering coating. Please refer to [link / reference]. Figure 1 As shown, the preparation method includes the following steps:

[0086] S100: Preparation of modified filler dispersion

[0087] The filler (zinc phosphate, calcium carbonate, etc., 5-10 parts by weight) and PDA-silane coupling agent (0.5 wt% of the total filler) are dispersed in deionized water and ultrasonically treated for 3-6 hours to uniformly coat the filler surface with a modified layer, forming a modified filler dispersion. The PDA-silane coupling agent improves the compatibility and dispersion stability of the filler with the aqueous system, avoiding subsequent coating separation or sedimentation.

[0088] S200: Formulation of resin mixture base material

[0089] Add the self-drying waterborne resin (HYR-2435B, 20-35 parts by weight) and the modified silicone resin (20-35 parts by weight) to a high-speed dispersion vessel, and stir at 300-500 rpm for 15-20 minutes at room temperature to initially mix and form a resin base. This is the basic blending of waterborne resin and functional silicone resin, which provides a carrier for subsequent functional additives.

[0090] S300: Additives and pH Adjustment

[0091] Add organosilicon additives (BYK-346 / TEGOGlide410, etc., 0.1-1 parts by weight), thickeners (RM-2020 / ASE-60, etc., 0.1-1 parts by weight), and pH adjusters (DMEA / AMP-95, etc., 0.1-0.5 parts by weight) sequentially to the S200 resin base. Stir at 600-800 rpm for 20-30 minutes to adjust the viscosity of the system to 5000-8000 mPa·s (25℃) and stabilize the pH value at 7.5-8.5. The leveling, thickening, and storage stability of the coating are optimized by the additives.

[0092] S400: Surface pretreatment

[0093] Completely immerse the substrate to be coated in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 50-60 minutes to remove surface grease and loose layers; then rinse with water until neutral, and then immerse in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.1-0.12 mol / L for 8-10 minutes to activate the surface and improve the adhesion of subsequent coatings; finally rinse with water and dry; ensure strong adhesion between the coating and the substrate to avoid delamination and peeling.

[0094] S500: Single coating

[0095] Heat the substrate to the first melting temperature T1 (set according to the characteristics of the aluminum silver paste and resin system, usually 80-100℃), and uniformly coat a layer of mixed slurry (containing S100 modified filler dispersion, S200 resin base, S300 additive system, and 5-10 parts by weight of aluminum silver paste (MD-2000 / STAPA)) using a reverse roller coating method. ® The aluminum silver paste is mixed with 5-10 parts by weight of film-forming aids (such as Hydrolan2150, etc.) and controlled to a wet film thickness of 10-15 μm. It is then dried at 60-80℃ for 10-15 minutes to form a base coating with a surface roughness Ra > 1.45. By controlling the temperature and drying conditions, the aluminum silver paste is partially oriented and forms a micro-convex structure, providing anchoring sites for secondary coating.

[0096] S600: Secondary coating and high-temperature melting

[0097] Apply the remaining mixed paste (with the same composition as S500, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) again to the surface of the S500 base coating. After coating, quickly raise the temperature by 40-50℃ (i.e., raise it to T2=T1+40~50℃, such as 120-150℃) to make the modified silicone resin and film-forming aid in the system melt and flow, promote the migration of aluminum silver paste particles to the surface and self-separate (high-gloss aluminum silver paste is enriched on the top layer, and the water-based resin matrix sinks to form an adhesion layer). Maintain the high-temperature molten state for 5-8 minutes to promote intermolecular cross-linking. Use the temperature difference to drive the directional migration of functional components (aluminum silver paste) to achieve the natural separation of the high-gloss surface layer and the adhesion base layer.

[0098] S700: Cooling and Shaping

[0099] Stop heating and allow it to cool naturally to room temperature (or be forced to air cool to below 40°C) to allow the molten coating to gradually solidify. The aluminum silver paste particles are fixed on the surface to form a high-gloss reflective layer, and the underlying resin is tightly bonded to the substrate. This ensures the stability of the coating structure and avoids deformation or decreased adhesion caused by high-temperature residue.

[0100] S800: Final Drying

[0101] After cooling, the reflective layer is gently dried at 40-50℃ for 30-60 minutes to completely remove residual solvent and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-layered structure (aluminum silver paste enriched surface layer + resin-adhered bottom layer), and strong adhesion to the substrate.

[0102] Specifically, the preparation process of the modified silicone resin in this application is as follows:

[0103] The main chain structure of modified silicone resin is as follows: Figure 2 As shown in the diagram. Here, m represents an integer from 1 to 4, and n represents an integer from 20 to 50; the substituent R1 is an organic group containing functional groups such as amide bonds (-CONH-). Structurally, R1 contains multiple methylene groups (-CH2-), carboxyl groups (-COOH), and amide bonds. This structure endows the silicone resin with special properties, such as potential hydrophilicity and reactivity with other substances. The structure of substituent R1 is shown in the diagram. Figure 3 As shown.

[0104] a) Preparation of side-hydrogen silicone oil. Side-hydrogen silicone oil was prepared using high-hydrogen-content silicone oil (hydrogen content >1%), octamethylcyclotetrasiloxane (D4), and hexamethyldisiloxane (MM) at a specific temperature (50-70℃) in the presence of a Karstedt catalyst (platinum(0)-vinylsiloxane complex, 0.2-0.4 parts by weight). The structure of the side-hydrogen silicone oil is as follows... Figure 4As shown, the temperature used in the preparation of the side-hydrogen silicone oil is 50-70℃;

[0105] b) Preparation of acrylate intermediates. 3-hydroxypropionic acid and unsaturated isocyanate were reacted at 40-60°C in the presence of a catalyst for 3 hours to obtain the acrylate intermediates. The structure of the unsaturated isocyanate is as follows: Figure 5 As shown, the structure of the acrylate intermediate is as follows: Figure 6 As shown, the unsaturated isocyanate is AOI-VM from Showa Denko Corporation;

[0106] c) Preparation of silicone resin. Using the products from steps a) and b), a hydrosilylation reaction is carried out at a certain temperature (60-80℃) in the presence of a Karstedt catalyst (platinum(O)-vinylsiloxane complex, 0.2-0.4 parts by weight). The resulting product is as follows: Figure 7 As shown;

[0107] d) Product emulsification. The above product is neutralized to neutral by adding triethylamine, and then water (30% to 60% of the total mass) is added for high-speed emulsification until it is completely homogeneous to obtain the modified silicone resin.

[0108] The steps of this application are explained in detail below:

[0109] In one exemplary embodiment of this disclosure, side-hydrogen silicone oil serves as a key intermediate in the preparation of modified silicone resin, and its preparation quality directly affects the performance of the final product. Specifically, side-hydrogen silicone oil is prepared by reacting high-hydrogen silicone oil (with a hydrogen content >1%), octamethylcyclotetrasiloxane (D4), and hexamethyldisiloxane (MM) at 50-70°C with 0.2-0.4 parts by weight of a Karstedt catalyst (platinum(0)-vinylsiloxane complex). The hydrogen content of the high-hydrogen silicone oil must meet the reactivity requirements, while the controlled ratio of D4 to MM can optimize the molecular structure of the side-hydrogen silicone oil, providing suitable active sites for subsequent hydrosilylation reactions.

[0110] In one exemplary embodiment of this disclosure, the synthesis of the acrylate intermediate is a key step in imparting special functions to the silicone resin. This intermediate is prepared by reacting 3-hydroxypropionic acid with an unsaturated isocyanate (such as AOI-VM from Showa Denko Corporation) at 40-60°C for 3 hours in the presence of a catalyst. The structural characteristics of the unsaturated isocyanate (such as...) Figure 5 (As shown) enables it to undergo a highly efficient addition reaction with 3-hydroxypropionic acid, generating an acrylate intermediate (such as...) Figure 6 (As shown) It contains carbon-carbon double bonds that can react with silane groups, while retaining the reactivity of carboxylic acid derivatives, laying the foundation for the subsequent introduction of functional groups such as amide bonds.

[0111] In one exemplary embodiment of this disclosure, the main structure of the modified silicone resin is prepared by a hydrosilylation reaction of the side-hydrosilicone oil of step a) and the acrylate intermediate of step b) at 60-80°C and catalyzed by 0.2-0.4 parts by weight of Karstedt catalyst (the product structure is as follows). Figure 7 As shown). This reaction achieves the combination of a main-chain siloxane structure and side-chain functional organic groups (containing amide bonds, carboxyl groups, etc., such as...). Figure 3 The efficient connection (as shown) is achieved by controlling the number of repeating units n in the main chain within the range of 20-50 to ensure the chain length and flexibility of the polymer, and the number m of methylene (-CH2-) in the side chain substituent R1 is 1-4 to balance steric hindrance and reactivity. The resulting silicone resin combines the heat resistance of siloxanes with the reactive / hydrophilic properties of organic functional groups.

[0112] In one exemplary embodiment of this disclosure, the emulsification process of the modified silicone resin achieves compatibility with an aqueous system through neutralization and dispersion. Specifically, the silicone resin product is first neutralized to neutral with triethylamine, and then 30%–60% water by mass is added for high-speed emulsification until the system is uniformly dispersed. This emulsification process, by adjusting the amount of water and the emulsification intensity, can control the particle size distribution and stability of the final modified silicone resin, making it suitable for aqueous applications such as coatings and adhesives, while retaining the functional properties of the main chain and side chains (such as hydrophilicity and reactivity).

[0113] In one exemplary embodiment of this disclosure, zinc phosphate and calcium carbonate fillers, deionized water, PDA-silane coupling agent, and ultrasonic treatment parameters in a preset ratio can be uniformly combined to obtain a modified filler dispersion. To ensure the dispersion stability of the final coating system, the total proportion of zinc phosphate and calcium carbonate fillers in the preset ratio is 5-10 parts by mass (for example, the proportion of fillers can be 5, 7, 9, or 10 parts by mass; of course, the proportion of fillers can also be other values, which will not be listed here). This range of filler proportions not only ensures the uniform distribution of fillers in the coating system but also effectively avoids sedimentation and agglomeration caused by excessive fillers, thus ensuring that the final coating has better application performance and long-term stability. Meanwhile, the type of filler (such as zinc phosphate or calcium carbonate) can be adjusted according to the specific application scenario; through a reasonable ratio of the two, the wear resistance, weather resistance, and cost control of the coating can be balanced.

[0114] In one exemplary embodiment of this disclosure, the amount of PDA-silane coupling agent is 0.5 wt% of the total filler (for example, the coupling agent percentage can be 0.4 wt%, 0.5 wt%, or 0.6 wt%, and of course, other proportions are also possible, which will not be listed here). This proportion range not only ensures a uniform coating of the modified layer on the filler surface but also effectively avoids cost increases or system compatibility imbalances caused by excessive coupling agent. Simultaneously, the PDA-silane coupling agent enhances the compatibility of the filler with the aqueous system through chemical bonding, resulting in more uniform dispersion of the filler in the subsequent resin matrix, thereby optimizing the overall mechanical properties and appearance of the coating.

[0115] In one exemplary embodiment of this disclosure, the ultrasonic treatment time is 3 to 6 hours (for example, the ultrasonic duration can be 3, 4, 5, or 6 hours; of course, other ranges are also possible, which will not be listed here). This treatment duration range not only ensures that the filler surface is fully coated with the modified layer, but also effectively avoids filler structure damage or energy waste caused by excessive ultrasonic time. Simultaneously, the ultrasonic power needs to be adapted to the filler particle size (the conventional particle size range is 1-10 μm). By uniformly dispersing the filler, the subsequent coating system exhibits lower viscosity fluctuations and better storage stability.

[0116] In one exemplary embodiment of this disclosure, the ratio of self-drying waterborne resin (HYR-2435B) to modified silicone resin is 20-35 parts by weight (for example, the ratio can be 20, 25, 30, or 35 parts by weight; of course, the resin ratio can also be other values, which will not be listed here). This ratio range not only ensures that the resin base has good film-forming properties and flexibility, but also enhances the adhesion and weather resistance of the coating through the special functional groups (such as amide bonds and carboxyl groups) of the modified silicone resin. At the same time, the synergistic effect of the two provides a stable carrier for subsequent functional additives (such as aluminum silver paste and film-forming aids), ensuring the overall performance balance of the coating system.

[0117] In one exemplary embodiment of this disclosure, the amount of silicone-based additive (such as BYK-346 / TEGOGlide410) is 0.1-1 parts by weight (e.g., the additive ratio can be 0.1 parts by weight, 0.3 parts by weight, 0.5 parts by weight, or 1 part by weight; of course, the amount of additive can also be other proportions, which will not be listed here). This proportion range not only optimizes the leveling and surface tension of the coating, but also effectively avoids increased costs or decreased system stability caused by excessive additives. Meanwhile, the amount of thickener (such as RM-2020 / ASE-60) is 0.1-1 parts by weight (for example, the proportion of thickener can be 0.1 parts by weight, 0.2 parts by weight, 0.5 parts by weight or 1 part by weight) to precisely adjust the viscosity of the system to 5000-8000 mPa·s (25℃) (for example, the viscosity can be 5000 mPa·s, 6000 mPa·s, 7000 mPa·s or 8000 mPa·s) to ensure that the coating can maintain ideal fluidity and coating uniformity under different construction processes (such as roller coating, spray coating).

[0118] In one exemplary embodiment of this disclosure, the amount of pH adjuster (such as DMEA / AMP-95) is 0.1-0.5 parts by weight (e.g., the proportion of adjuster may be 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, or 0.5 parts by weight) to stabilize the pH value of the system at 7.5-8.5 (e.g., the pH value may be 7.5, 8.0, or 8.5). This pH range not only ensures the long-term storage stability of the coating but also avoids substrate corrosion caused by excessive alkalinity or resin hydrolysis caused by excessive acidity, thereby improving the durability and adhesion of the coating.

[0119] In one exemplary embodiment of this disclosure, during the substrate pretreatment process, the hydroxide ion concentration of the alkaline solution (such as an aqueous NaOH solution) is 0.2 mol / L (e.g., the concentration may be 0.15 mol / L, 0.2 mol / L, or 0.25 mol / L), and the treatment time is 50–60 minutes (e.g., the treatment duration may be 50 minutes, 55 minutes, or 60 minutes). This treatment condition not only effectively removes grease and loose layers from the substrate surface but also avoids a decrease in substrate strength due to excessive corrosion. Subsequently, the hydrogen ion concentration of the acid solution (such as dilute HCl) is 0.1–0.12 mol / L (e.g., the concentration may be 0.1 mol / L, 0.11 mol / L, or 0.12 mol / L), and the treatment time is 8–10 minutes (e.g., the treatment duration may be 8 minutes, 9 minutes, or 10 minutes), used to activate the substrate surface and improve the adhesion of subsequent coatings. Finally, washing and drying ensure that the substrate surface is clean and free of residual impurities.

[0120] In one exemplary embodiment of this disclosure, during a single coating process, the substrate is heated to a first melting temperature T1 (e.g., T1 can be 80°C, 90°C, or 100°C, typically set to 80-100°C depending on the characteristics of the aluminum silver paste and resin system). A mixed slurry (containing a modified filler dispersion, resin base, additive system, and 5-10 parts by weight of aluminum silver paste (e.g., MD-2000 / STAPA)) is uniformly coated using a reverse roller coating method. ® The aluminum silver paste is mixed with 5-10 parts by weight of a film-forming aid (such as Texanol / PM / DPM / DPNB) to control the wet film thickness at 10-15 μm (e.g., the wet film thickness can be 10 μm, 12 μm, or 15 μm). It is then dried at 60-80°C for 10-15 minutes (e.g., the drying temperature can be 60°C, 70°C, or 80°C, and the drying time can be 10 minutes, 12 minutes, or 15 minutes) to form an undercoat with a surface roughness Ra > 1.45 (e.g., Ra can be 1.5, 1.6, or 1.8). By controlling the temperature and drying conditions, the aluminum silver paste is partially oriented and forms a micro-convex structure, providing anchoring sites for secondary coating, thereby improving the adhesion strength and reflectivity of the coating.

[0121] In one exemplary embodiment of this disclosure, during the secondary coating process, the remaining mixed slurry (with the same components as the primary coating, ensuring that the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) is coated. After coating, the temperature is rapidly increased by 40-50°C (i.e., to T2 = T1 + 40~50°C, for example, T2 can be 120°C, 130°C, 140°C, or 150°C). This causes the modified silicone resin and film-forming aid in the system to melt and flow, promoting the migration of aluminum silver paste particles to the surface and self-stratification (high-gloss aluminum silver paste is enriched on the top layer, and the aqueous resin matrix sinks to form an adhesion layer). The high-temperature molten state is maintained for 5-8 minutes (e.g., the holding time can be 5 minutes, 6 minutes, or 8 minutes) to promote intermolecular cross-linking. The temperature difference drives the directional migration of functional components (aluminum silver paste), achieving natural separation between the high-gloss surface layer and the adhesion layer, ultimately forming a self-stratified structure with high gloss (>90GU@60°).

[0122] In one exemplary embodiment of this disclosure, during the cooling and setting process, the molten coating gradually solidifies by natural cooling to room temperature (or forced air cooling to below 40°C), fixing the aluminum silver paste particles to the surface to form a high-gloss reflective layer, while the underlying resin adheres tightly to the substrate. By controlling the cooling rate, deformation or decreased adhesion caused by high-temperature residue is avoided, ensuring the long-term stability of the coating structure.

[0123] In one exemplary embodiment of this disclosure, during the final drying process, the cooled reflective layer is gently dried at 40-50°C for 30-60 minutes (e.g., the drying temperature can be 40°C, 45°C, or 50°C, and the drying time can be 30 minutes, 45 minutes, or 60 minutes) to thoroughly remove residual solvents and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-layering structure (aluminum silver paste-rich surface layer + resin-adhered underlayer), and strong adhesion to the substrate. This coating is suitable for automotive interiors, appliance housings, and architectural decoration, combining both decorative and functional properties.

[0124] The performance of samples prepared under different conditions was investigated through multiple examples and comparative examples, as detailed below:

[0125] Example 1

[0126] Zinc phosphate filler (average particle size 5 μm, mass purity 99.9%) and PDA-silane coupling agent (0.5 wt% of total filler) were dispersed in deionized water and ultrasonically treated for 4 hours to uniformly coat the filler surface with a modified layer, forming a modified filler dispersion. Self-drying waterborne resin (HYR-2435B, 30 parts by mass) and modified silicone resin (30 parts by mass) were added to a high-speed dispersion vessel and stirred at 400 rpm for 18 minutes at room temperature to initially mix and form a resin base. Organosilicon additive (BYK-346, 0.5 parts by mass), thickener (RM-2020, 0.5 parts by mass), and pH adjuster (DMEA, 0.3 parts by mass) were added sequentially to the resin base, and stirred at 700 rpm for 25 minutes to adjust the system viscosity to 6500 mPa·s (25℃) and stabilize the pH at 8. The substrate to be coated is completely immersed in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 55 minutes to remove surface grease and loose layers; then rinsed with water until neutral, and then immersed in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.11 mol / L for 9 minutes to activate the surface and improve the adhesion of subsequent coatings; finally rinsed with water and dried. The substrate is heated to the first melting temperature T1 (90°C), and a layer of mixed slurry (containing modified filler dispersion, resin base, additive system, and 8 parts by mass of aluminum silver paste (MD-2000) and 8 parts by mass of film-forming aid (Texanol)) is uniformly coated using a reverse roller coating method, controlling the wet film thickness to 12 μm; then dried at 70°C for 12 minutes to form a base coating with a surface roughness Ra > 1.45. The remaining mixed slurry (with the same components as before, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) is applied again to the surface of the base coating. After application, the temperature is rapidly increased to 45°C (i.e., to T2=135°C) to allow the modified silicone resin and film-forming aid in the system to melt and flow, promoting the migration of aluminum silver paste particles to the surface and self-stratification. The high-temperature molten state is maintained for 6 minutes to promote intermolecular cross-linking. Heating is stopped, and the mixture is allowed to cool naturally to room temperature, allowing the molten coating to gradually solidify. The aluminum silver paste particles are fixed to the surface to form a high-gloss reflective layer, and the underlying resin is tightly bonded to the substrate. The cooled reflective layer is then gently dried at 45°C for 45 minutes to completely remove residual solvents and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-stratified structure (aluminum silver paste enriched on the surface + resin attached to the underlying layer), and strong adhesion to the substrate.

[0127] Example 2

[0128] Calcium carbonate filler (average particle size 8 μm, purity 99.8%) and PDA-silane coupling agent (0.5 wt% of total filler) were dispersed in deionized water and ultrasonically treated for 5 hours to uniformly coat the filler surface with a modified layer, forming a modified filler dispersion. Self-drying waterborne resin (HYR-2435B, 25 parts by weight) and modified silicone resin (25 parts by weight) were added to a high-speed dispersion vessel and stirred at 350 rpm for 16 minutes at room temperature to initially mix and form a resin base. Organosilicon additive (TEGOGlide410, 0.8 parts by weight), thickener (ASE-60, 0.8 parts by weight), and pH adjuster (AMP-95, 0.4 parts by weight) were added sequentially to the resin base, and the mixture was stirred at 650 rpm for 22 minutes to adjust the system viscosity to 5500 mPa·s (25℃) and stabilize the pH at 7.8. The substrate to be coated is completely immersed in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 52 minutes to remove surface grease and loose layers; then rinsed with water until neutral, and then immersed in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.1 mol / L for 8 minutes to activate the surface and improve the adhesion of subsequent coatings; finally rinsed with water and dried. The substrate is heated to the first melting temperature T1 (85°C), and a layer of mixed slurry (containing modified filler dispersion, resin base, additive system, and 6 parts by mass of aluminum silver paste and 6 parts by mass of film-forming aid (DPM)) is uniformly coated using a reverse roller coating method, controlling the wet film thickness to be 11 μm; then dried at 65°C for 11 minutes to form a base coating with a surface roughness Ra > 1.45. The remaining mixed slurry (with the same components as before, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) is applied again to the surface of the base coating. After application, the temperature is rapidly increased to 42°C (i.e., to T2=127°C) to allow the modified silicone resin and film-forming aid in the system to melt and flow, promoting the migration of aluminum silver paste particles to the surface and self-stratification. The high-temperature molten state is maintained for 7 minutes to promote intermolecular cross-linking. Heating is stopped, and the mixture is allowed to cool naturally to room temperature, allowing the molten coating to gradually solidify. The aluminum silver paste particles are fixed to the surface to form a high-gloss reflective layer, and the underlying resin is tightly bonded to the substrate. The cooled reflective layer is then gently dried at 42°C for 50 minutes to completely remove residual solvents and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-stratified structure (aluminum silver paste enriched on the surface + resin attached to the underlying layer), and strong adhesion to the substrate.

[0129] Example 3

[0130] A mixture of zinc phosphate and calcium carbonate filler (zinc phosphate: calcium carbonate = 1:1, average particle size of both 6 μm, mass purity of both 99.9%) was dispersed in deionized water with PDA-silane coupling agent (0.5 wt% of the total filler volume). The mixture was ultrasonically treated for 6 hours to uniformly coat the filler surface with a modified layer, forming a modified filler dispersion. Self-drying waterborne resin (HYR-2435B, 35 parts by weight) and modified silicone resin (35 parts by weight) were added to a high-speed dispersion vessel and stirred at 500 rpm for 20 minutes at room temperature to initially mix and form a resin matrix. Add the following to the resin base in sequence: silicone additive (BYK-346 and TEGOGlide410 mixed in a 1:1 ratio, 0.3 parts by mass), thickener (RM-2020 and ASE-60 mixed in a 1:1 ratio, 0.3 parts by mass), and pH adjuster (DMEA and AMP-95 mixed in a 1:1 ratio, 0.2 parts by mass). Stir at 800 rpm for 30 minutes to adjust the viscosity of the system to 8000 mPa·s (25℃) and stabilize the pH value at 8.5. Completely immerse the substrate to be coated in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 60 minutes to remove surface grease and loose layer; then wash with water until neutral, and then immerse in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.12 mol / L for 10 minutes to activate the surface and improve the adhesion of subsequent coatings; finally wash with water and dry. The substrate is heated to the first melting temperature T1 (100°C), and a layer of mixed slurry (containing modified filler dispersion, resin base, additive system, and 10 parts by weight of aluminum silver paste (MD-2000 and STAPA)) is uniformly coated using a reverse roller coating method. ® Hydrolan2150 (mixed at a 1:1 mass ratio) and 10 parts by mass of film-forming aid (Texanol, PM, DPM, and DPNB mixed at a 1:1:1:1 mass ratio) were used to control the wet film thickness at 15 μm. The mixture was then dried at 80°C for 15 minutes to form a base coat with a surface roughness Ra > 1.45. The remaining mixed slurry (with the same components as before, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) was then applied over the base coat. After application, the temperature was rapidly increased by 50°C (i.e., to T2 = 150°C) to allow the modified silicone resin and film-forming aid in the system to melt and flow, promoting the migration of aluminum silver paste particles to the surface and self-delamination. The high-temperature molten state was maintained for 8 minutes to promote intermolecular cross-linking. Heating was then stopped, and the mixture was allowed to cool naturally to room temperature, allowing the molten coating to gradually solidify. The aluminum silver paste particles were fixed to the surface to form a high-reflectivity layer, and the base resin was tightly bonded to the substrate. After cooling, the reflective layer is gently dried at 50°C for 60 minutes to completely remove residual solvent and moisture, resulting in a water-based aluminum silver paste coating with high gloss (>90GU@60°), a self-layered structure (aluminum silver paste enriched surface layer + resin-adhered bottom layer), and strong adhesion to the substrate.

[0131] Comparative Example 1 (without modified silicone resin)

[0132] Calcium carbonate filler (average particle size 8 μm, mass purity 99.8%) was dispersed in deionized water and ultrasonically treated for 5 hours to form a filler dispersion. Self-drying aqueous resin (HYR-2435B, 60 parts by weight) was added to a high-speed dispersion vessel and stirred at 400 rpm for 18 minutes at room temperature to initially mix and form a resin base. Organosilicon additive (TEGOGlide410, 0.8 parts by weight), thickener (ASE-60, 0.8 parts by weight), and pH adjuster (AMP-95, 0.4 parts by weight) were added sequentially to the resin base. The mixture was stirred at 650 rpm for 22 minutes to adjust the viscosity to 5500 mPa·s (25℃) and stabilize the pH at 7.8. The substrate to be coated is completely immersed in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 52 minutes to remove surface grease and loose layers; then rinsed with water until neutral, and then immersed in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.1 mol / L for 8 minutes to activate the surface and improve the adhesion of subsequent coatings; finally rinsed with water and dried. The substrate is heated to the first melting temperature T1 (85°C), and a layer of mixed slurry (containing filler dispersion, resin base, additive system, and 6 parts by mass of aluminum silver paste and 6 parts by mass of film-forming aid (DPM)) is uniformly coated using a reverse roller coating method, controlling the wet film thickness to 11 μm; then dried at 65°C for 11 minutes to form the undercoat. The remaining mixed slurry (with the same components as before, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) is applied again to the surface of the base coating. After application, the temperature is quickly raised to 42℃ (i.e., to T2=127℃) to melt and flow the resin and film-forming aid in the system, promoting the migration of aluminum silver paste particles to the surface. The high-temperature molten state is maintained for 7 minutes to promote intermolecular cross-linking. Heating is stopped, and the mixture is allowed to cool naturally to room temperature, allowing the molten coating to gradually solidify. The aluminum silver paste particles are fixed to the surface to form a reflective layer, and the base resin adheres to the substrate. The cooled reflective layer is then gently dried at 42℃ for 50 minutes to completely remove residual solvent and moisture, yielding a water-based aluminum silver paste coating. Performance comparison: The coating prepared in the comparative example, due to the lack of modified silicone resin, exhibits poor self-delamination, uneven distribution of aluminum silver paste particles, low gloss (approximately 70 GU@60°), weak adhesion to the substrate, and is prone to delamination and peeling.

[0133] Comparative Example 2 (Some parameters were inappropriate during the preparation of the modified silicone resin)

[0134] A mixture of zinc phosphate and calcium carbonate filler (zinc phosphate: calcium carbonate = 1:1, average particle size of both 6 μm, mass purity of both 99.9%) was dispersed in deionized water with PDA-silane coupling agent (0.5 wt% of the total filler volume). The mixture was ultrasonically treated for 6 hours to uniformly coat the filler surface with a modified layer, forming a modified filler dispersion. Self-drying waterborne resin (HYR-2435B, 35 parts by weight) and modified silicone resin (35 parts by weight) were added to a high-speed dispersion vessel and stirred at 500 rpm for 20 minutes at room temperature to initially mix and form a resin matrix. Add the following to the resin base in sequence: silicone additive (BYK-346 and TEGOGlide410 mixed in a 1:1 ratio, 0.3 parts by mass), thickener (RM-2020 and ASE-60 mixed in a 1:1 ratio, 0.3 parts by mass), and pH adjuster (DMEA and AMP-95 mixed in a 1:1 ratio, 0.2 parts by mass). Stir at 800 rpm for 30 minutes to adjust the viscosity of the system to 8000 mPa·s (25℃) and stabilize the pH value at 8.5. Completely immerse the substrate to be coated in an alkaline solution (such as NaOH aqueous solution) with a hydroxide ion concentration of 0.2 mol / L for 60 minutes to remove surface grease and loose layer; then wash with water until neutral, and then immerse in an acidic solution (such as dilute HCl) with a hydrogen ion concentration of 0.12 mol / L for 10 minutes to activate the surface and improve the adhesion of subsequent coatings; finally wash with water and dry. The substrate is heated to the first melting temperature T1 (100°C), and a layer of mixed slurry (containing modified filler dispersion, resin base, additive system, and 10 parts by weight of aluminum silver paste (MD-2000 and STAPA)) is uniformly coated using a reverse roller coating method. ® Hydrolan2150 (mixed at a 1:1 mass ratio) and 10 parts by mass of film-forming aid (Texanol, PM, DPM, and DPNB mixed at a 1:1:1:1 mass ratio) were used to control the wet film thickness at 15 μm. The mixture was then dried at 80°C for 15 minutes to form a base coat with a surface roughness Ra > 1.45. The remaining mixed slurry (with the same components as before, ensuring the total aluminum silver paste and film-forming aid ratio meets the formulation requirements) was then applied over the base coat. After application, the temperature was rapidly increased by 50°C (i.e., to T2 = 150°C) to allow the modified silicone resin and film-forming aid in the system to melt and flow, promoting the migration of aluminum silver paste particles to the surface and self-delamination. The high-temperature molten state was maintained for 8 minutes to promote intermolecular cross-linking. Heating was then stopped, and the mixture was allowed to cool naturally to room temperature, allowing the molten coating to gradually solidify. The aluminum silver paste particles were fixed to the surface to form a high-reflectivity layer, and the base resin was tightly bonded to the substrate. After cooling, the reflective layer is gently dried at 50°C for 60 minutes to completely remove residual solvent and moisture, resulting in a water-based aluminum silver paste coating with general gloss (82GU@60°), a self-layered structure (aluminum silver paste enriched surface layer + resin-adhered bottom layer), and strong adhesion to the substrate.

[0135] The high-gloss waterborne aluminum silver paste self-layering coatings prepared in Examples 1-3 and Comparative Examples 1-2 were tested for washability (GB / T9266-2009), alkali resistance (GB / T9265-2009), gloss, and self-layering effect. The test results are shown in Table 1.

[0136] Table 1: Performance Test Results

[0137]

[0138] In Table 1, regarding washability, Examples 1 and 2 both achieved 1200 cycles, while Example 3 reached the highest at 1300 cycles. Comparative Example 1 achieved 1000 cycles, and Comparative Example 2 achieved 1100 cycles, with Example 3 showing the best performance. Regarding alkali resistance, all examples and comparative examples showed no abnormalities after immersion in 10% NaOH solution for 24 hours. In terms of gloss, Example 1 achieved 92.50 GU, Example 2 91.80 GU, Example 3 93.00 GU, Comparative Example 1 70.00 GU, and Comparative Example 2 82.00 GU, with Example 3 showing the highest. Regarding self-stratification, Examples 1, 2, and 3 all performed well, Comparative Example 1 was poor, and Comparative Example 2 was average. Considering the key indicators such as washability, gloss, and self-stratification, Example 3 performed excellently in all aspects and is the optimal example.

[0139] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0140] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-gloss water-based aluminum silver paste self-layering coating, characterized in that: The preparation method includes the following steps: S100: The filler and PDA-silane coupling agent are dispersed in deionized water and ultrasonically treated to uniformly coat the surface of the filler with a modified layer, forming a modified filler dispersion. S200: Add water-based resin and modified silicone resin to a high-speed dispersion kettle, stir, and then mix to form a resin base material; S300: Add organosilicon additives, thickeners and pH adjusters to the resin base in sequence, stir and adjust the viscosity and pH of the system; S400: Immerse the substrate to be coated in an alkaline solution of hydroxide ions to remove surface grease and loose layer, wash with water, then immerse in an acidic solution of hydrogen ions, and finally wash with water and dry. S500: The substrate is heated to the first melting temperature T1, and a layer of mixed slurry is uniformly coated by reverse roller coating and dried to form the bottom coating. S600: The remaining mixed slurry is coated again on the surface of the bottom coating. After coating, the temperature is increased based on the first melting temperature T1, so that the modified silicone resin and film-forming aid in the system melt and flow, promote the aluminum silver paste particles to migrate to the surface and self-decompose, maintain the molten state and promote intermolecular cross-linking. S700: Natural cooling allows the molten coating to gradually solidify, and aluminum silver paste particles are fixed on the surface to form a reflective layer; S800: After cooling, the reflective layer is gently dried to remove residual solvent and moisture, resulting in a water-based aluminum silver paste coating with a self-layering structure.

2. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 1, characterized in that: In step S200, the method for preparing the modified silicone resin includes the following steps: S201: Side-hydrogen silicone oil is prepared using hydrogen-containing silicone oil, octamethylcyclotetrasiloxane, and hexamethyldisiloxane at a set temperature with a Karstedt catalyst; S202: An acrylate intermediate is obtained by reacting 3-hydroxypropionic acid with unsaturated isocyanate at a set temperature in the presence of a catalyst. S203: Using the products from steps S201 and S202, a Karstedt catalyst is added at a set temperature to carry out a hydrosilylation reaction to form the product. S204: After neutralizing the product with triethylamine to neutral, water is added for emulsification until homogeneous to obtain modified silicone resin.

3. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 2, characterized in that: The main chain structure of the modified silicone resin includes a substituent R1, which contains multiple methylene groups as well as carboxyl and amide functional groups.

4. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 2 or 3, characterized in that: In step S201, the hydrogen content of the hydrogen-containing silicone oil is >1%, the Karstedt catalyst is a platinum (0)-vinylsiloxane complex, 0.2-0.4 parts by weight, and the temperature used in the preparation process of the hydrogen-containing silicone oil is 50-70℃.

5. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 2, characterized in that: In step S202, the temperature is set to 40-60℃ and the inverse time is 3h.

6. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 2, characterized in that: In step S203, the temperature used in the product synthesis is 60-80℃. In step S204, after adding triethylamine to neutralize the product to neutrality, water is added, with water accounting for 30% to 60% of the total mass.

7. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 1, characterized in that: In step S300, the organosilicon additive is BYK-346 or TEGOGlide410, 0.1-1 parts by weight; the thickener is RM-2020 or ASE-60, 0.1-1 parts by weight; the pH adjuster is DMEA or AMP-95, 0.1-0.5 parts by weight; the stirring speed is 600-800 rpm; the stirring time is 20-30 min; the viscosity of the system is adjusted to 5000-8000 mPa·s at 25℃; and the pH value is 7.5-8.

5.

8. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 1, characterized in that: In step S100: the filler is zinc phosphate or calcium carbonate, 5-10 parts by weight, the amount of PDA-silane coupling agent is 0.5 wt% of the total filler, and the ultrasonic treatment time is 3-6 hours.

9. The method for preparing a high-gloss water-based aluminum silver paste self-layering coating according to claim 1, characterized in that: In step S600: the temperature is increased by 40-50℃ after coating, that is, T2=T1+40~50℃, where T2 is 120-150℃.

10. The method for preparing a high-gloss waterborne aluminum silver paste self-layering coating according to claim 2, characterized in that: In step S200, the aqueous resin is HYR-2435B, 20-35 parts by weight, the modified silicone resin is 20-35 parts by weight, the stirring speed is 300-500 rpm, and the stirring time is 15-20 min.

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