One-component silicone-modified polyurethane microcapsule system water-based ceramic coating and preparation method

Abstract

This invention discloses a single-component organosilicon-modified polyurethane microcapsule system for waterborne ceramic coatings and its preparation method. The raw material composition and weight ratio are as follows: 45-70 parts of chelated modified nano-silica sol base; 15-35 parts of organosilicon-modified polyurethane microcapsules; 5-20 parts of organo-modified siloxane-assisted film-forming agent; 8-25 parts of inorganic pigments and fillers; 0.5-3 parts of waterborne additives; and 5-18 parts of deionized water. The organosilicon-modified polyurethane microcapsules are latent curing single-core microcapsules and / or functional sustained-release single-core microcapsules. The advantages are: significantly improved compatibility with waterborne silica sol systems, avoiding aggregation and sedimentation, while controlling the glass transition temperature of the capsule wall to achieve stability at room temperature and precise rupture at the curing temperature. The two types of microcapsules can be used alone or in combination, respectively solving the curing problem and the long-term functional problem of single-component systems, eliminating the need for complex dual-core structures, simplifying the process, and enhancing industrial applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of water-based ceramic coatings, in particular, a kind of single-component silicone-modified polyurethane microcapsule system water-based ceramic coatings and preparation method. BACKGROUND

[0002] Water-based ceramic coatings take Si-O-Si inorganic crosslinking network as the core skeleton, with the advantages of high hardness, high temperature resistance, weather resistance, corrosion resistance, environmental protection and non-toxicity, has been widely used in cookware non-stick, home appliance panel, building curtain wall, industrial corrosion prevention and other fields. The current industry is mainly divided into three categories:

[0003] The first type is a two-component water-based ceramic coating system, represented by the technology disclosed in CN115304940A and CN115322597A. This system uses nano-silica sol as the main film-forming material and alkyl silane as the auxiliary film-forming component. It is divided into primer and topcoat double coating or A / B two-component. Curing is achieved through silane hydrolysis and polycondensation. To improve the functionality of the coating, silicon oil microcapsules with a siloxane shell are introduced into the system to achieve slow release of non-stick and hydrophobic functions. The coating hardness can reach 9H, and the temperature resistance is excellent, but it has the core limitations of complex construction, short pot life and high temperature curing.

[0004] The second type is a single-component ceramic coating latent curing system. Existing technologies mainly use pH value control and alcohol-ether solvents to block the active groups of silane to achieve single-component storage. A few technologies use ordinary polyurethane and melamine resin as the shell material to encapsulate the curing agent inside the microcapsule to achieve latent curing. This type of system solves the problem of complex construction of two-component systems, but generally cannot balance storage stability and curing activity. The room temperature sealed storage period is generally not more than 6 months, and the curing temperature still needs to be above 180℃. Crosslinking is not complete at low temperatures, and the coating performance is significantly degraded.

[0005] The third type is the silicone-modified polyurethane microcapsule technology, represented by the invention patent application CN119453191A. This technology uses isocyanate, hydroxyl-terminated polydimethylsiloxane and degradable dihydric alcohol to prepare a silicone-modified polyurethane shell material, encapsulates the pesticide active ingredient to prepare a slow-release microcapsule, achieves controllable slow release of the core material, good spreading property with the substrate and degradability of the shell material, and has achieved good results in the field of pesticide slow release. However, this microcapsule technology has not been adapted for development and application in the field of ceramic coatings. The existing microcapsules for ceramic coatings still have the industry pain points of poor compatibility of the shell material with water-based silica sol system, easy breakage during high temperature curing, and uncontrollable slow release.

[0006] Through practical testing, the defects of the existing above-mentioned technologies are:

[0007] (1) Significant defects in the structure and performance of microcapsules for ceramic coatings: Most existing microcapsules for ceramic coatings use pure siloxane or ordinary polyurethane as shell material: pure siloxane shell material is prone to premature rupture during high-temperature curing at temperatures above 180°C, resulting in a core material volatilization loss of over 60% and extremely low effective retention of function; ordinary polyurethane shell material has a large polarity difference with the water-based silica sol system, poor compatibility, and is prone to agglomeration, stratification, and sedimentation, leading to failure of coating storage stability, and the shell material is non-degradable, which can easily cause high-molecular environmental pollution after disposal. At the same time, existing microcapsules cannot achieve the dual regulation of "precise rupture and release during the curing stage and long-term sustained release during the use stage". Either the core material is completely released during curing, and there is no functional supplementation during use; or it does not rupture during curing and cannot play a curing catalytic role, so the function and curing performance cannot be taken into account.

[0008] (2) Single-component ceramic coatings cannot solve the core contradiction between storage stability and low-temperature curing. Existing non-microcapsule single-component ceramic coatings achieve storage stability through pH control, but there is still a slow siloxane condensation reaction at room temperature. The storage period is no more than 6 months, and thickening and gelation are likely to occur. In contrast, the latent curing system with ordinary microcapsule encapsulation has an uncontrollable shell rupture temperature. Storage at room temperature is prone to capsule wall damage and premature release of curing agent, resulting in coating scrap. Moreover, the curing temperature still needs to be above 180℃, which cannot achieve low-temperature curing at 120℃ and below. It has high energy consumption and cannot be adapted to heat-sensitive substrates and on-site construction scenarios.

[0009] (3) The long-term effectiveness of coating function and basic mechanical properties cannot be balanced. Existing functional ceramic coatings directly add functional components such as silicone oil and fluorocarbon additives to improve non-stick, hydrophobic and weather-resistant properties. This is prone to surface migration and rapid loss during use, with functional degradation of more than 60% after 3 months. The addition of microcapsule functional system often leads to a decrease in coating density, a drop in pencil hardness from 6H to below 2H, and a significant reduction in adhesion, impact resistance and water resistance. It is impossible to achieve a balance between "functionality" and "basic mechanical properties".

[0010] (4) Insufficient compatibility and environmental friendliness of coatings: Existing ceramic coatings have high surface energy and poor wetting and spreading properties on substrates such as aluminum alloys, stainless steel, and cement, which easily lead to pinholes and missed coatings, requiring complex pretreatment of the substrates; at the same time, the material waste rate of two-component systems exceeds 20%, and the storage period of single-component systems is short, and waste coatings are prone to causing environmental pollution. Existing microcapsule shell materials are mostly non-degradable polymers, which further aggravates the environmental burden and cannot meet the current requirements of green and environmentally friendly industry development. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating and its preparation method, which can effectively solve the problems of poor compatibility between existing microcapsules and waterborne silica sols, easy breakage during high-temperature curing, and unstable storage.

[0012] To solve the above-mentioned technical problems, the single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating of the present invention has the following raw material composition and weight ratio: 45-70 parts of chelated modified nano-silica sol base material; 15-35 parts of organosilicon-modified polyurethane microcapsules; 5-20 parts of organo-modified siloxane auxiliary film-forming agent; 8-25 parts of inorganic pigments and fillers; 0.5-3 parts of waterborne additives; and 5-18 parts of deionized water. Among them, the organosilicon-modified polyurethane microcapsules are latent curing type single-core microcapsules and / or functional sustained-release type single-core microcapsules.

[0013] The latent curing single-core microcapsule comprises a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows:

[0014] The shell material prepolymer component includes 10-40 parts of isocyanate, 1-8 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000, 1-8 parts of biodegradable diol, and 0.05-1 part of catalyst.

[0015] The core material component is 10-80 parts of ketimine-modified siloxane latent curing agent;

[0016] The emulsion system consists of 0.5-4 parts of surfactant;

[0017] The chain extender is 1-20 parts of a diamine / triamine aqueous solution.

[0018] The solvent is deionized water.

[0019] The functional sustained-release single-core microcapsule also includes a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows:

[0020] The shell prepolymer component includes 10-40 parts of isocyanate, 1-10 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000, 1-10 parts of biodegradable diol, and 0.05-1 parts of catalyst.

[0021] The core material component consists of 10-90 parts of functional additives;

[0022] The emulsion system consists of 0.5-4 parts of surfactant;

[0023] The chain extender is 1-20 parts of a diamine / triamine aqueous solution.

[0024] The solvent is deionized water.

[0025] The organic modified siloxane-assisted film-forming agent is a compound of phenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and methyltrimethoxysilane.

[0026] The preparation method of the organosilicon-modified polyurethane microcapsules is as follows:

[0027] A. Preparation of prepolymer: Isocyanate, hydroxyl-terminated polydimethylsiloxane, biodegradable diol and catalyst are added to the reactor according to the formula. The reactor is heated to 60-70℃ under nitrogen protection and stirred for 3-4 hours to obtain -NCO-terminated organosilicon-modified polyurethane prepolymer. The prepolymer is then cooled to room temperature for later use.

[0028] B. Preparation of oil / water phase: The core material components and shell material prepolymer are mixed evenly in a certain proportion to form the oil phase; the surfactant is added to deionized water and stirred until completely dissolved to form the water phase.

[0029] C. Preparation of oil-in-water emulsion by emulsification: The oil phase is slowly added to the aqueous phase, and emulsified at 3000-5000 rpm for 10-20 min at room temperature using a high-speed disperser to obtain an oil-in-water emulsion with uniform particle size.

[0030] D. Interfacial polymerization and solidification into capsules: Add the aqueous solution of diamine / triamine dropwise to the emulsion. After the addition is complete, heat to 70-90℃, keep warm and stir for 2-3 hours to complete the interfacial polymerization and chain extension, and obtain the microcapsule suspension.

[0031] E. Post-processing: After demulsification and washing with deionized water 3-5 times, the microcapsule suspension is vacuum filtered and then vacuum dried at 40-45℃ for 11-12 hours to obtain powdered single-core organosilicon-modified polyurethane microcapsules with a particle size controlled at 2-10 μm and a capsule wall thickness of 0.5-1 μm.

[0032] The raw materials and proportions of the chelated modified nano-silica sol base are as follows: 100 parts of acidic nano-silica sol, 3-5 parts of γ-aminopropyltriethoxysilane, 0.3-0.5 parts of glacial acetic acid, and 10-15 parts of deionized water.

[0033] The preparation method of the chelated modified nano-silica sol is as follows: acidic nano-silica sol is added to an acid-resistant stainless steel reactor, the pH value of the system is adjusted to 3.5-4.5 with glacial acetic acid, the temperature is raised to 55-65℃, and γ-aminopropyltriethoxysilane is added dropwise at a low speed of 150r / min. After the addition is completed, the mixture is kept at the temperature and stirred for 4h to chelate and modify the surface of nano-silica. After the reaction is completed, the mixture is cooled to room temperature, filtered through a filter screen to obtain the chelated modified nano-silica sol, and then sealed and stored for later use.

[0034] A method for preparing a waterborne ceramic coating based on a single-component organosilicon-modified polyurethane microcapsule system as described above includes the following steps:

[0035] A. Preparation of inorganic color paste: In a reaction vessel, chelated modified nano silica sol base material, deionized water, water-based wetting and dispersing agent, and organosilicon defoamer are added in sequence. After stirring at a low speed of 300-400 r / min until uniform, inorganic pigments and functional fillers are added and dispersed at a high speed of 1200-1300 r / min for 30-40 min. The mixture is then introduced into a horizontal sand mill and ground until the fineness is ≤20μm to obtain inorganic color paste. The pH value is adjusted to 4.0-4.5.

[0036] B. Finished Product Preparation: Transfer the inorganic pigment paste to a low-speed stirring tank with a rotation speed ≤200 r / min. Add the organic modified siloxane auxiliary film-forming agent, leveling agent, and pH buffer in sequence. After stirring evenly, under nitrogen protection and relative humidity ≤40%, slowly add the single-core organosilicon modified polyurethane microcapsules and continue stirring for 30 minutes until the system is completely homogeneous. Filter with a filter screen, seal and package under nitrogen filling in an anhydrous drying environment to obtain the single-component microcapsule system waterborne ceramic coating product.

[0037] The advantages of this invention are:

[0038] (1) Through the structural design of single-core organosilicon-modified polyurethane microcapsules, combined with the film-forming characteristics of water-based ceramic coatings, three core technological breakthroughs have been achieved:

[0039] a. Microcapsule and system compatibility design: Organosilicon-modified polyurethane prepolymer was prepared by reacting hydroxyl-terminated polydimethylsiloxane, biodegradable diol and isocyanate, and microcapsule shell material was formed by interfacial polymerization; the introduction of organosilicon segments reduced the surface energy of microcapsules, which greatly improved their compatibility with aqueous silica sol system, avoided agglomeration and sedimentation, and controlled the glass transition temperature of the capsule wall to achieve stability at room temperature and precise rupture at curing temperature.

[0040] b. Dual-function adaptation of single-core microcapsules: Adopting a single-core structure design, latent curing microcapsules (core material is ketimine-modified siloxane latent curing agent) and functional sustained-release microcapsules (core material is fluorocarbon-modified silicone oil, weather-resistant additives and other functional components) can be prepared according to needs. The two types of microcapsules can be used alone or in combination to solve the curing problem and the long-term function problem of single-component systems respectively. There is no need for a complex dual-core structure, the process is simpler, and the industrialization adaptability is stronger.

[0041] c. Controlled Degradation and Slow-Release Design of Shell Material: Degradable diols such as polycaprolactone diol and polybutylene succinate diol are introduced into the shell material. On the one hand, by adjusting the amount of degradable diols added, the crosslinking density and porosity of the shell material can be precisely controlled, so as to achieve slow and long-term release of functional core material during the coating process. On the other hand, the shell material can be gradually degraded in the natural environment, avoiding high molecular residual pollution, while not affecting the structural stability of the coating during its service life.

[0042] (2) By chelating and modifying the nano-silica sol to seal the excess active hydroxyl groups in the system, and with the physical isolation of the latent curing agent by the microcapsule, there are no effective reaction sites in the system at room temperature and no cross-linking reaction occurs, thus achieving long-term storage stability; after curing and heating, the microcapsule wall ruptures and releases the curing agent, which rapidly catalyzes the hydrolysis and polycondensation of siloxane to form an interpenetrating structure of "inorganic Si-O-Si rigid network and organic polyurethane flexible network", thus achieving low-temperature rapid curing and comprehensive improvement of overall performance.

[0043] (3) Its formula and preparation process are reasonable and the technical route is novel. It has overcome the core contradiction between "long-term stable storage at room temperature" and "rapid curing at low temperature" of single-component ceramic coatings. By encapsulating the latent curing agent in single-core microcapsules, the curing agent and the film-forming system are completely isolated at room temperature. The capsule wall is precisely broken at a curing temperature of 100-120℃ to release the curing agent. The catalytic system is rapidly cross-linked and cured. The cross-linking degree of the coating film is ≥95%. It has completely solved the compatibility problem of storage and curing of single-component systems. It has effectively solved the problems of poor compatibility between existing microcapsules and water-based silica sol, easy breakage at high temperature, and unstable storage. It has achieved uniform dispersion of microcapsules in the coating system. There is no aggregation, no sedimentation, and no capsule wall damage after 12 months of sealed storage at room temperature. Detailed Implementation

[0044] The following detailed description, in conjunction with specific embodiments, further illustrates the single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating and its preparation method of the present invention.

[0045] Example 1:

[0046] This embodiment provides a single-component waterborne ceramic coating based on a silicone-modified polyurethane microcapsule system. The raw material composition and weight ratio (based on a total weight of 100 parts) are as follows: 45-70 parts of chelated modified nano-silica sol base material (silane chelated modified acidic nano-silica sol with a particle size of 10-50 nm and a solid content of 30%); 15-35 parts of silicone-modified polyurethane microcapsules; 5-20 parts of silicone-modified siloxane auxiliary film-forming agent; 8-25 parts of inorganic pigments and fillers; 0.5-3 parts of waterborne additives; and 5-18 parts of deionized water. The silicone-modified polyurethane microcapsules are latent curing single-core microcapsules and / or functional sustained-release single-core microcapsules (i.e., they can be used alone or in combination). The chelated modified nano-silica sol base material is the core film-forming substance. The coating provides an inorganic rigid skeleton, determining the base hardness, temperature resistance, and weather resistance. Latent-curing polyurethane microcapsules modified with silicone address the curing issues of single-component coatings, while functional slow-release types provide long-lasting non-stick properties and weather resistance. Inorganic pigments and fillers, including weather-resistant inorganic pigments and functional fillers (mica powder, silica powder, precipitated barium sulfate, and fumed silica), primarily provide hiding power and color, improving the mechanical properties, anti-settling properties, and high-temperature resistance of the coating. Water-based additives mainly consist of nonionic wetting and dispersing agents, silicone defoamers, polyurethane leveling agents, and phosphate pH buffers, used to improve the dispersibility of pigments and fillers, the storage stability of the coating, its workability, and the appearance of the coating film. Deionized water is used as the dispersion medium to adjust the application viscosity and achieve zero VOC environmental characteristics.

[0047] It is important to note that the two types of single-core microcapsules mentioned in this invention can be used alone or in combination. Both use silicone-modified polyurethane as the shell material and feature a single-core structure design. Specifically, the latent curing type single-core microcapsule includes a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows (parts by mass): The shell prepolymer component includes 10-40 parts of isocyanate (the main body of the shell material, forming a polyurethane cross-linked structure) and 1-8 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000 (to improve the compatibility of the shell material with the aqueous system and regulate the...). The microcapsule composition consists of: capsule wall rupture temperature, 1-8 parts of biodegradable diol (to regulate shell porosity and impart biodegradability), and 0.05-1 parts of catalyst (to catalyze the prepolymer reaction and improve crosslinking efficiency); core material component: 10-80 parts of ketimine-modified siloxane latent curing agent (isolated at room temperature, released during curing, catalyzing crosslinking and curing of the system); emulsion system component: 0.5-4 parts of surfactant (to stabilize the emulsion and ensure uniform microcapsule particle size); chain extender: 1-20 parts of diamine / triamine aqueous solution (interfacial polymerization chain extension to form a dense capsule wall); solvent: deionized water; the remainder is deionized water used as the emulsion dispersion medium.

[0048] The aforementioned functional sustained-release single-core microcapsules also include a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows: the shell prepolymer component includes 10-40 parts of isocyanate (the main body of the shell, forming a polyurethane cross-linked structure), 1-10 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000 (to improve the compatibility of the shell with the aqueous system and regulate the porosity of the capsule wall), and 1-10 parts of biodegradable diol (because the limited compatibility of PDMS affects the cross-linking density of the shell material, a specific number of parts of biodegradable diol are added to regulate the degradation rate of the shell material, achieving...). The core material consists of a long-lasting, sustained-release functional core and 0.05-1 parts of a catalyst (catalyzing the prepolymer reaction and improving crosslinking efficiency); the core material component consists of 10-90 parts of functional additives (fluorocarbon-modified hydroxyl silicone oil, phenyl silicone oil, benzotriazole UV absorbers, etc., to impart long-lasting functionality to the coating). The functional additives are used for room temperature isolation and are released during curing to catalyze the crosslinking and curing of the system; the emulsion system component consists of 0.5-4 parts of a surfactant (stabilizing the emulsion and ensuring uniform microcapsule particle size); the chain extender consists of 1-20 parts of a diamine / triamine aqueous solution (interfacial polymerization chain extension to form a dense capsule wall), the solvent is deionized water, and the remainder is deionized water used as the emulsion dispersion medium.

[0049] The preparation method (interfacial polymerization method) of its organosilicon-modified polyurethane microcapsules (latent-curing single-core microcapsules and functional sustained-release single-core microcapsules) mainly draws on the prepolymer-interfacial polymerization technology published in CN119453191A. Parameters are optimized for the ceramic coating system, and hydroxyl-terminated polydimethylsiloxane (PDMS) is introduced to reduce the surface energy of the microcapsules, significantly improving their compatibility with the aqueous silica sol system and preventing aggregation and sedimentation. The specific steps are as follows:

[0050] A. Preparation of prepolymer: Isocyanate, hydroxyl-terminated polydimethylsiloxane, biodegradable diol and catalyst are added to the reactor according to the formula. The reactor is heated to 60-70℃ under nitrogen protection and stirred for 3-4 hours to obtain -NCO-terminated organosilicon-modified polyurethane prepolymer. The prepolymer is then cooled to room temperature for later use.

[0051] B. Preparation of oil / water phase: The core material components and shell material prepolymer are mixed evenly in a certain proportion to form the oil phase; the surfactant is added to deionized water and stirred until completely dissolved to form the water phase.

[0052] C. Preparation of oil-in-water emulsion by emulsification: The oil phase is slowly added to the aqueous phase, and emulsified at 3000-5000 rpm for 10-20 min at room temperature using a high-speed disperser to obtain an oil-in-water emulsion with uniform particle size.

[0053] D. Interfacial polymerization and solidification into capsules: Add the aqueous solution of diamine / triamine dropwise to the emulsion. After the addition is complete, heat to 70-90℃, keep warm and stir for 2-3 hours to complete the interfacial polymerization and chain extension, and obtain the microcapsule suspension.

[0054] E. Post-processing: After demulsification and washing with deionized water 3-5 times, the microcapsule suspension is vacuum filtered and then vacuum dried at 40-45℃ for 11-12 hours to obtain powdered single-core organosilicon-modified polyurethane microcapsules with a particle size controlled at 2-10 μm and a capsule wall thickness of 0.5-1 μm.

[0055] Furthermore, the raw materials and proportions of the chelated modified nano-silica sol base material are as follows: 100 parts of acidic nano-silica sol (particle size 20nm, solid content 30%), 3-5 parts of γ-aminopropyltriethoxysilane, 0.3-0.5 parts of glacial acetic acid, and 10-15 parts of deionized water. The preparation method is as follows: the acidic nano-silica sol is added to an acid-resistant stainless steel reactor, the pH value of the system is adjusted to 3.5-4.5 with glacial acetic acid, the temperature is raised to 55-65℃, and γ-aminopropyltriethoxysilane is added dropwise at a low speed of 150r / min. After the addition is completed, the mixture is kept at the temperature and stirred for 4h to chelate and modify the surface of nano-silica, blocking excess active hydroxyl groups. After the reaction is completed, the mixture is cooled to room temperature, filtered through a filter screen to obtain the chelated modified nano-silica sol base material, and stored in a sealed container for later use.

[0056] In addition, the organic modified siloxane film-forming agent mentioned is a compound of phenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and methyltrimethoxysilane, which is mainly used to assist in film formation and improve the crosslinking density, adhesion and flexibility of the coating film.

[0057] Example 2:

[0058] This embodiment describes a method for preparing the above-mentioned single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating, including the following steps:

[0059] A. Preparation of inorganic color paste: In a stainless steel reactor, chelated modified nano-silica sol base material, deionized water, water-based wetting and dispersing agent, and organosilicon defoamer are added in sequence. After stirring at a low speed of 300-400 r / min until uniform, inorganic pigments and functional fillers are added and dispersed at a high speed of 1200-1300 r / min for 30-40 min. The mixture is then fed into a horizontal sand mill and ground until the fineness is ≤20μm to obtain inorganic color paste. The pH value is adjusted to 4.0-4.5.

[0060] B. Finished Product Preparation: Transfer the inorganic pigment paste to a low-speed stirring tank with a rotation speed ≤200 r / min. Add the organic modified siloxane film-forming agent, leveling agent, and pH buffer in sequence. After stirring evenly, under nitrogen protection and relative humidity ≤40%, slowly add the single-core organosilicon modified polyurethane microcapsules and continue stirring for 30 minutes until the system is completely homogeneous. Filter through a 200-mesh filter, seal and package under nitrogen filling in an anhydrous drying environment to obtain the single-component microcapsule system waterborne ceramic coating product.

[0061] Example 3:

[0062] Construction and curing process

[0063] Substrate pretreatment: Compatible with various substrates such as aluminum alloy, stainless steel, galvanized steel sheet, ceramic, glass, and cement; metal substrates are sandblasted with 80-120 mesh corundum to achieve a roughness of Ra2.5-4μm, and then dried after degreasing with anhydrous ethanol; non-metallic substrates are polished to remove dust and oil stains, ensuring that the substrate surface is dry and clean.

[0064] Application method: Simply open the can and stir until homogeneous before application. No on-site metering or mixing is required, and there is no curing step. Various application methods can be used, such as air spraying, electrostatic spraying, brushing, and roller coating. Adjust the viscosity of the Forte 4 cup to 15-20s with deionized water, and control the dry film thickness to 20-30μm.

[0065] Curing process:

[0066] Standard low-temperature curing process: 120℃ / 20min for complete curing, suitable for large-scale production of prefabricated parts in factories;

[0067] Rapid curing process: Complete curing at 150℃ for 10 minutes, suitable for high-speed production lines;

[0068] Accelerated curing process: Curing at 80℃ for 60 minutes, suitable for processing heat-sensitive substrates.

[0069] The following examples demonstrate its effectiveness:

[0070] This invention verifies the feasibility of the technical solution through three sets of examples with differentiated formulations, and simultaneously sets up a comparative example (using the existing technical formulation disclosed in CN115304940A) for performance comparison analysis. All microcapsules are single-core structures, with no dual-core designs, strictly adhering to the requirements of the invention.

[0071] Application Example 1: Low-Temperature Curing Single-Component Ceramic Coating

[0072] Preparation of core microcapsules (latent solidification type single-core microcapsules)

[0073] Formula: 20 parts isophorone diisocyanate, 2 parts hydroxyl-terminated polydimethylsiloxane (molecular weight 2000), 2 parts polycaprolactone diol (molecular weight 1000), 0.2 parts organotin catalyst, 30 parts ketimine-modified γ-aminopropyltriethoxysilane core material, 1 part sodium dodecylbenzenesulfonate, 2 parts ethylenediamine, 8 parts diethylenetriamine, and the balance of deionized water;

[0074] Preparation process: The steps described in Example 2 were followed. The prepolymer was reacted at 65°C for 4 hours, emulsified at 4000 rpm for 15 minutes, and subjected to interfacial polymerization at 80°C for 2.5 hours to obtain latent solidification microcapsules with a particle size of 3-8 μm and a capsule wall rupture temperature of 110°C.

[0075] Overall paint formulation (total weight 100 parts)

[0076]

[0077] Preparation and curing process: The coating was prepared according to the process described in Example 2. The relative humidity of the environment was ≤40% throughout the process. The finished product was sealed and nitrogen-filled. The aluminum alloy substrate was sandblasted and then sprayed. The dry film thickness was 25μm and the coating was cured at 120℃ for 20min.

[0078] Application Example 2: Long-lasting non-stick single-component ceramic coating

[0079] Preparation of core microcapsules (functional sustained-release single-core microcapsules)

[0080] Formula: 25 parts hexamethylene diisocyanate, 5 parts hydroxyl-terminated polydimethylsiloxane (molecular weight 3000), 4 parts polybutylene succinate diol (molecular weight 2000), 0.3 parts organic zinc catalyst, 40 parts fluorocarbon modified hydroxyl silicone oil core material, 1.5 parts sodium dodecyl sulfate, 3 parts butanediamine, 10 parts diethylenetriamine, and the balance of deionized water;

[0081] Preparation process: The steps described in Example 2 were followed. The prepolymer was reacted at 60°C for 4 hours, emulsified at 4500 rpm for 10 minutes, and subjected to interfacial polymerization at 85°C for 2 hours to prepare functional sustained-release microcapsules with a particle size of 2-8 μm and a capsule wall rupture temperature of 120°C.

[0082] Overall paint formulation (total weight 100 parts)

[0083]

[0084] Preparation and curing process: The coating was prepared according to the process described in Example 2. The relative humidity of the environment was ≤40% throughout the process. The finished product was sealed and nitrogen-filled. The aluminum alloy substrate was sandblasted and then sprayed. The dry film thickness was 25μm and the coating was cured at 150℃ for 10min.

[0085] Application Example 3: Weather-resistant self-cleaning single-component ceramic coating

[0086] Core microcapsule preparation

[0087] Latent solidification type single-core microcapsule: Same as application example 1, capsule wall rupture temperature 110℃;

[0088] Weather-resistant sustained-release single-core microcapsules: The formulation consists of 18 parts dicyclohexylmethane diisocyanate, 3 parts hydroxyl-terminated polydimethylsiloxane (molecular weight 2000), 3 parts polycaprolactone diol (molecular weight 2000), 0.2 parts organic bismuth catalyst, 35 parts benzotriazole UV absorber + hydroxyl silicone oil core material, 1 part sodium dodecylbenzenesulfonate, 2 parts hexamethylenediamine, 6 parts diethylenetriamine, and the balance deionized water; prepared according to the process of Example 2, with a particle size of 2-10 μm and a capsule wall rupture temperature of 115℃.

[0089] Overall paint formulation (total weight 100 parts)

[0090]

[0091] Preparation and curing process: The coating was prepared according to the process described in Example 2. The relative humidity of the environment was ≤40% throughout the process. The finished product was sealed and nitrogen-filled. The aluminum alloy substrate was sandblasted and then sprayed. The dry film thickness was 25μm and the coating was cured at 120℃ for 20min.

[0092] Comparative Example 1: Existing Ceramic Coatings

[0093] The two-component formulation of Example 1 disclosed in CN115304940A was adopted. The primer consisted of 26% silica sol, 4% 1% NaOH solution, 10% titanium dioxide, 4% kaolin, 4% mica powder, 1% BYK190, 30% methyltrimethoxysilane, 3% isopropanol, 6% siloxane shell silicone oil microcapsules, 1% 25% formic acid, and the balance being deionized water. The topcoat consisted of 1% heptadecafluorodecyltrimethoxysilane, 3% acetic acid, and the balance being a 1:1 mixture of deionized water and isopropanol. Preparation and application were performed according to the patent disclosure. The primer was applied to a thickness of 25 μm, the topcoat to 8 μm, and the curing time was 240℃ / 12 min.

[0094] Performance testing and effect analysis

[0095] Test Standards and Methods

[0096]

[0097] Performance test results

[0098]

[0099] Effect Theory Analysis

[0100] Breakthrough in storage stability and curing performance: Application Examples 1-3 utilize silicone-modified polyurethane microcapsules to physically isolate latent curing agents, combined with chelated modified silica sol to block active hydroxyl groups. This achieves a single-component system that remains unthickened, gelled, or agglomerated for 12 months at room temperature under sealed conditions, completely resolving the pain points of short shelf life in existing single-component systems and short pot life in two-component systems. Application Example 1 achieves complete curing at 120℃ / 20min, a 120℃ reduction in curing temperature compared to Comparative Example 1, resulting in a curing energy consumption reduction of over 70%. Simultaneously, the coating crosslinking degree is ≥95%, and the pencil hardness reaches 7H. The fundamental mechanical properties are comprehensively superior to existing technologies, solving the industry problem of incomplete low-temperature curing in single-component systems.

[0101] The microcapsule structure design solves the problems of high-temperature curing failure and long-term functional retention. The organosilicon-modified polyurethane shell material of this invention achieves precise rupture at the curing temperature through formulation control. In application examples 1-3, the core material retention rate after curing is ≥94%, while in comparative example 1, the siloxane shell microcapsule ruptured prematurely during high-temperature curing at 240℃, resulting in a core material volatilization loss of over 60% and a core material retention rate of only 38% after curing. Simultaneously, by introducing biodegradable diols into the shell material, the porosity of the shell wall is precisely controlled, achieving slow and long-term release of the functional core material during coating application. Theoretical analysis shows that application examples 2 and 3 retain ≥88% of their function after 3 years of use, while comparative example 1 shows significant functional degradation after 3 months of use, with a 3-year retention rate of only 35%. This fully verifies the significant advantages of the microcapsule structure of this invention in terms of long-term functional retention.

[0102] This invention comprehensively optimizes the overall performance and environmental friendliness of the coating. Through the excellent compatibility between the silicone-modified polyurethane shell and the inorganic silica sol system, the addition of microcapsules does not compromise the coating's density; instead, it forms an inorganic-organic interpenetrating cross-linked network, achieving a balance between high hardness and high toughness. Application examples 1-3 show that the coating withstood over 50 cycles of thermal cycling from -40℃ to 200℃ without cracking or peeling, while the pure inorganic system in Comparative Example 1 showed microcracks after only 20 cycles. Simultaneously, the all-water-based system has a VOC content ≤10g / L, far below national standards and existing technologies. The biodegradable shell design further enhances the coating's environmental friendliness, avoiding high-molecular-weight environmental pollution from waste coatings.

[0103] In terms of construction compatibility and environmental friendliness, the silicone segments in the shell material reduce the surface energy of the coating, improving its wetting and spreading properties on various substrates and simplifying the substrate pretreatment process, thus significantly improving construction compatibility. The silicone segments in the shell material effectively reduce the surface energy of the coating, greatly improving its wetting and spreading properties on various substrates. It is a single-component product that can be applied immediately after opening the can, without the need for on-site metering and mixing. It is compatible with various construction methods such as spraying, brushing, and roller coating, with a material utilization rate of 100%. The construction efficiency is more than 60% higher than that of a two-component system. At the same time, it simplifies the substrate pretreatment process, making it more suitable for industrialization. The shell material introduces biodegradable diols, achieving biodegradability in natural environments. The VOC content of the all-water-based system is ≤10g / L, meeting the most stringent environmental standards.

[0104] Through the above verification, the present invention achieves a balance between the long-term functionality of the coating and its basic mechanical properties. By controlling the crosslinking density, porosity, and biodegradability of the silicone-modified polyurethane shell material, the functional core material is slowly and effectively released during the coating application process. The non-stick, hydrophobic, and weather-resistant functions are maintained at ≥85% for 3 years. At the same time, the addition of microcapsules does not damage the density of the coating film, achieving a pencil hardness of ≥6H, adhesion grade 0, and superior resistance to high and low temperatures, acids and alkalis, and water compared to existing technologies.

[0105] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A single-component waterborne ceramic coating based on organosilicon-modified polyurethane microcapsule system, wherein the raw material composition and weight ratio are as follows: 45-70 parts of chelated modified nano-silica sol base; 15-35 parts of organosilicon-modified polyurethane microcapsules; 5-20 parts of organomodified siloxane film-forming agent; 8-25 parts of inorganic pigments and fillers; 0.5-3 parts of waterborne additives; and 5-18 parts of deionized water, wherein... The organosilicon-modified polyurethane microcapsules are latent curing single-core microcapsules and / or functional sustained-release single-core microcapsules.

2. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 1, characterized in that: The latent curing single-core microcapsule comprises a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows: The shell material prepolymer component includes 10-40 parts of isocyanate, 1-8 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000, 1-8 parts of biodegradable diol, and 0.05-1 part of catalyst. The core material component is 10-80 parts of ketimine-modified siloxane latent curing agent; The emulsion system consists of 0.5-4 parts of surfactant; The chain extender is 1-20 parts of a diamine / triamine aqueous solution. The solvent is deionized water.

3. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 1 or 2, characterized in that: The functional sustained-release single-core microcapsule also includes a shell prepolymer component, a core component, an emulsion system component, a chain extender, and a solvent. The raw material composition and weight ratio of each component are as follows: The shell prepolymer component includes 10-40 parts of isocyanate, 1-10 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000, 1-10 parts of biodegradable diol, and 0.05-1 parts of catalyst. The core material component consists of 10-90 parts of functional additives; The emulsion system consists of 0.5-4 parts of surfactant; The chain extender is 1-20 parts of a diamine / triamine aqueous solution. The solvent is deionized water.

4. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 3, characterized in that: The organic modified siloxane-assisted film-forming agent is a compound of phenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and methyltrimethoxysilane.

5. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 4, characterized in that: The preparation method of the organosilicon-modified polyurethane microcapsules is as follows: A. Preparation of prepolymer: Isocyanate, hydroxyl-terminated polydimethylsiloxane, biodegradable diol and catalyst are added to the reactor according to the formula. The reactor is heated to 60-70℃ under nitrogen protection and stirred for 3-4 hours to obtain -NCO-terminated organosilicon-modified polyurethane prepolymer. The prepolymer is then cooled to room temperature for later use. B. Preparation of oil / water phase: The core material components and shell material prepolymer are mixed evenly in a certain proportion to form the oil phase; the surfactant is added to deionized water and stirred until completely dissolved to form the water phase. C. Preparation of oil-in-water emulsion by emulsification: The oil phase is slowly added to the aqueous phase, and emulsified at 3000-5000 rpm for 10-20 min at room temperature using a high-speed disperser to obtain an oil-in-water emulsion with uniform particle size. D. Interfacial polymerization and solidification into capsules: Add the aqueous solution of diamine / triamine dropwise to the emulsion. After the addition is complete, heat to 70-90℃, keep warm and stir for 2-3 hours to complete the interfacial polymerization and chain extension, and obtain the microcapsule suspension. E. Post-processing: After demulsification and washing with deionized water 3-5 times, the microcapsule suspension is vacuum filtered and then vacuum dried at 40-45℃ for 11-12 hours to obtain powdered single-core organosilicon-modified polyurethane microcapsules with a particle size controlled at 2-10 μm and a capsule wall thickness of 0.5-1 μm.

6. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 1, characterized in that: The raw materials and proportions of the chelated modified nano-silica sol base are as follows: 100 parts of acidic nano-silica sol, 3-5 parts of γ-aminopropyltriethoxysilane, 0.3-0.5 parts of glacial acetic acid, and 10-15 parts of deionized water.

7. The single-component organosilicon-modified polyurethane microcapsule system waterborne ceramic coating according to claim 6, characterized in that: The preparation method of the chelated modified nano-silica sol is as follows: acidic nano-silica sol is added to an acid-resistant stainless steel reactor, the pH value of the system is adjusted to 3.5-4.5 with glacial acetic acid, the temperature is raised to 55-65℃, and γ-aminopropyltriethoxysilane is added dropwise at a low speed of 150r / min. After the addition is completed, the mixture is kept at the temperature and stirred for 4h to chelate and modify the surface of nano-silica. After the reaction is completed, the mixture is cooled to room temperature, filtered through a filter screen to obtain the chelated modified nano-silica sol, and then sealed and stored for later use.

8. A method for preparing a waterborne ceramic coating based on a single-component organosilicon-modified polyurethane microcapsule system as described in any one of claims 1-7, characterized in that, Includes the following steps: A. Preparation of inorganic color paste: In a reaction vessel, chelated modified nano silica sol base material, deionized water, water-based wetting and dispersing agent, and organosilicon defoamer are added in sequence. After stirring at a low speed of 300-400 r / min until uniform, inorganic pigments and functional fillers are added and dispersed at a high speed of 1200-1300 r / min for 30-40 min. The mixture is then introduced into a horizontal sand mill and ground until the fineness is ≤20μm to obtain inorganic color paste. The pH value is adjusted to 4.0-4.

5. B. Finished Product Preparation: Transfer the inorganic pigment paste to a low-speed stirring tank with a rotation speed ≤200 r / min. Add the organic modified siloxane film-forming agent, leveling agent, and pH buffer in sequence. After stirring evenly, under nitrogen protection and relative humidity ≤40%, slowly add the single-core organosilicon modified polyurethane microcapsules and continue stirring for 30 minutes until the system is completely homogeneous. Filter with a filter screen, seal and package under nitrogen filling in an anhydrous drying environment to obtain the single-component microcapsule system waterborne ceramic coating product.

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