An antibacterial wear-resistant light composite coating material and a preparation method and application thereof

Abstract

The application discloses an antibacterial wear-resistant light composite coating material and a preparation method and application thereof, and relates to the field of composite materials.The preparation method comprises the following steps: mixing a nano antibacterial component and an amphoteric ionic silane coating agent to form a dynamic surface energy regulation coating layer; after centrifugal washing, freeze-drying is carried out to obtain loose freeze-dried powder; after mild ultrasonic depolymerization and normal-pressure defoaming, the freeze-dried powder is mixed with main slurry; after coating, solidification is carried out in a coagulation bath, a polarity gradient drives the coating layer to self-adaptively overturn and intertwine with polymer chain segments; step-by-step water washing is carried out, low-pressure dynamic water flow pore forming is carried out after low-temperature water pre-coagulation locking; and heat setting is carried out.The material solves the problems of nano particle agglomeration, precipitation and conflicts between film forming and pore forming through a dynamic overturning and intertwining process and a step-by-step pore forming process, and has the characteristics of long-acting antibacterial property, high wear resistance and light weight and moisture permeability.

Description

Technical Field

[0001] This application relates to the field of composite materials, specifically to an antibacterial, wear-resistant, lightweight composite coating material, its preparation method, and its application. Background Technology

[0002] Functional products such as lightweight bags (e.g., school bags) place high demands on the lightweight, wear-resistant, and long-lasting antibacterial properties of coating materials. Currently, polyurethane (PU) / microcrystalline cellulose (MCC) composite porous coatings are widely used due to their excellent physical properties and controllable pore structure. To further enhance antibacterial performance, the industry often introduces nano-antibacterial components such as silver or copper into this system.

[0003] However, introducing high surface energy nano-antibacterial components into the PU-MCC system faces numerous technical challenges. On the one hand, nano-antibacterial components are prone to agglomeration at the three-phase interface, causing mechanical embrittlement and pore structure collapse. Conventional short-chain silane surface treatment can only provide a static, single polar interface, which is difficult to simultaneously adapt to the polar solvent environment in the slurry preparation stage and the non-polar / weakly polar matrix environment in the curing and film formation stage, making them prone to desorption or secondary agglomeration during phase transition. Adding polymeric dispersants reduces film strength and wash fastness. On the other hand, weak interfacial bonding forces cause antibacterial components to easily migrate and precipitate during washing, resulting in a short actual antibacterial lifespan and safety risks.

[0004] Furthermore, in wet curing processes, there is an inherent conflict between film strength and pore-forming efficiency. While heating or ultrasonic-assisted water washing can improve pore-forming and salt-washing efficiency, high temperatures accelerate PU precipitation, forming a dense skin that hinders salt removal. Ultrasonic cavitation, on the other hand, can destroy the unheat-set microporous structure and dislodge initially physically entangled antibacterial particles, resulting in a trade-off between abrasion resistance and lightweight. Adding water-soluble anti-collapse agents can leave microscopic voids during subsequent water washing and leaching, degrading coating performance. Summary of the Invention

[0005] In order to solve at least one of the technical problems in the prior art, this invention application provides an antibacterial, wear-resistant, lightweight composite coating material, its preparation method, and its application.

[0006] The first aspect of this application provides a method for preparing an antibacterial, wear-resistant, and lightweight composite coating material, comprising the following steps: The nano-antibacterial component is mixed with an amphoteric silane coating agent in a solvent, and the amphoteric silane coating agent is hydrolyzed and chemically bonded to the hydroxyl groups on the surface of the nano-antibacterial component to form a dynamically regulated surface energy coating layer. The obtained product was centrifuged and washed, then freeze-dried to sublimate and dehydrate the ice crystals, resulting in a loose freeze-dried coated powder. The freeze-dried coated powder is dispersed in a solvent, and the soft agglomerates are broken up by gentle ultrasound. Then, it is allowed to stand under normal pressure to degas, allowing the entrained microbubbles to escape. Subsequently, it is mixed with a main slurry containing a polymer matrix and a pore-forming agent and degassed under vacuum. The degassed slurry is coated onto the substrate surface and placed in a coagulation bath for curing. During the curing process, water molecules replace the solvent to generate a local polar gradient, which drives the dynamic surface energy to regulate the adaptive flipping of the coating layer, with the hydrophobic groups facing outward and physically entangled with the precipitated polymer chain segments. The cured coating is subjected to two stages of water washing: the first stage uses room temperature pure water for pre-coagulation water washing to complete the deep entanglement and locking of the coated antibacterial particles and polymer chain segments; the second stage uses low-pressure dynamic circulating water to rinse the coating surface and leach out the pore-forming agent. The coating is then heat-set after washing.

[0007] This application introduces dynamic surface energy to regulate the coating layer, enabling it to exhibit compatible interfacial properties under different polarity environments, fundamentally eliminating the agglomeration dynamics caused by abrupt changes in three-phase polarity. During the solidification stage in the coagulation bath, water molecules replace the solvent, generating localized solvent-poor microregions and polarity gradients, driving the zwitterionic coating layer to adaptively flip. The hydrophobic groups then physically entangle with the precipitating PU segments, achieving spontaneous deep anchoring of nanoparticles to the matrix and effectively solving the problem of easy migration and precipitation of antibacterial components. Simultaneously, the loose powder obtained through freeze-drying and sublimation dehydration completely avoids the hard agglomeration caused by capillary contraction forces in traditional vacuum drying, and eliminates the need for water-soluble anti-collapse agents; gentle ultrasonic degassing under normal pressure eliminates microbubble defects caused by air entrapment in the powder.

[0008] Preferably, the zwitterionic silane coating agent is N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride, and its amount is 5-8 times the mass of the nano-antibacterial component. Before forming the dynamically controlled surface energy coating layer, the nano-antibacterial component is pre-coated with a carboxyl PEG-PLA composite dispersant, and then a secondary coating is performed with the zwitterionic silane coating agent to form a three-dimensional hierarchical interface.

[0009] Preferably, when forming the dynamic surface energy controlled coating layer, the pH is adjusted to 5.0-6.5 to hydrolyze the zwitterionic silane coating agent; the freeze-drying conditions are -40℃ to -60℃, vacuum degree <10Pa, and time is 20-28h; the frequency of the mild ultrasound is 40-45kHz, the power is 150-250W, and it is carried out in an ice bath at 0-5℃ for 5-15 minutes; the time for static degassing under normal pressure is 20-40 minutes.

[0010] Preferably, the coagulation bath is a DMF aqueous solution with a mass fraction of 10%-15%, and the solidification time is 5-10 min; the temperature of the first stage room temperature pure water pre-coagulation water washing is 20-25℃, and the time is 2-5 min; the pressure of the second stage low-pressure dynamic circulating water flow is 0.1-0.3 MPa, and the rinsing time is 10-20 min.

[0011] The second aspect of this application provides an antibacterial, wear-resistant, lightweight composite coating material, prepared by the above-described method. This material, due to the use of dynamic surface energy-controlled coating and adaptive flipping precipitation processes, achieves deep anchoring of nanoparticles, eliminating agglomeration and microporous defects, thus exhibiting long-lasting antibacterial properties and high wear resistance.

[0012] Preferably, the nano-antibacterial component is silver nanoparticles or copper nanoparticles with a particle size of 10-50 nm.

[0013] Preferably, the main slurry comprises polyether polyurethane resin, modified microcrystalline cellulose, micro / nano salt particles and additives, wherein the amount of micro / nano salt particles is 15%-20% of the solid content of the polyether polyurethane resin.

[0014] Preferably, the composite coating material is free of micropores and cracks, and the dynamic surface energy regulates the deep entanglement and anchoring of the hydrophobic groups of the coating layer with the polyether-type polyurethane resin chain segments.

[0015] Preferably, the composite coating material has a Taber abrasion loss of 5-6 mg / 500 rpm, an antibacterial rate of >99.5% after 20 washes, a nano-antibacterial component concentration of <5 ppm, and a moisture permeability of >4100 g / m³. 2 / 24h.

[0016] The third aspect of this application provides the application of the aforementioned antibacterial, wear-resistant, and lightweight composite coating material in student backpacks and other applications.

[0017] The present invention has the following beneficial effects: (1) This invention introduces a dynamic surface energy-controlled coating layer on the surface of nano antibacterial components and uses the micro-region polar gradient during the phase transition process to drive the coating layer to adaptively flip, so that the hydrophobic groups and the precipitated polymer chain segments are deeply physically entangled, fundamentally eliminating the aggregation dynamics caused by polarity mismatch, and realizing the spontaneous anchoring of nanoparticles in the matrix. This solves the problems of coating micro-skeleton fracture and easy migration and precipitation of antibacterial components, ensuring long-lasting antibacterial effect and high safety. (2) The present invention uses freeze-drying sublimation dehydration to obtain loose powder, which completely avoids the hard agglomeration caused by traditional vacuum drying. It does not use water-soluble anti-collapse additives, which avoids the micro-voids left by leaching and the resulting particle falling channels. Combined with gentle ice bath ultrasonic and normal pressure pre-degassing process, it completely eliminates the micro-pore defects of the coating caused by powder entrapment, ensuring the compactness and microstructure integrity of the film. (3) The present invention adopts a step-by-step locking and low-pressure dynamic water flow pore-forming process. The pre-solidification of room temperature water provides a stable environment for physical entanglement. The low-pressure dynamic water flow, while efficiently washing salt and forming pores, avoids the shearing damage to the foam micropore wall caused by high temperature PU precipitation densification and ultrasonic cavitation, as well as the shaking off of the entanglement interface, thus achieving a three-effect synergy of high moisture permeability, high wear resistance and lightweight. Detailed Implementation

[0018] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0020] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0021] In this application, the dynamic surface energy-regulated coating layer refers to an interfacial coating layer formed by the hydrolysis and condensation of a zwitterionic silane coating agent on the surface of the nano-antibacterial component, capable of conformational rearrangement in response to changes in the polarity of the external solvent environment. In the polar solvent environment (such as DMF) during the slurry preparation stage, the hydrophilic / polar groups of this coating layer extend outwards, exhibiting interfacial properties compatible with the polar solvent and preventing nanoparticle aggregation due to polarity mismatch. When entering the coagulation bath solidification stage, as water molecules replace the solvent, creating localized solvent-poor microregions and polar gradients, the coating layer undergoes adaptive flipping driven by the polar gradient. The hydrophobic groups then extend outwards, physically entangled with the polymer matrix (such as PU segments) undergoing film precipitation, thereby achieving spontaneous deep anchoring of nanoparticles in a non-polar / weakly polar matrix. This dynamic response characteristic overcomes the limitation of conventional short-chain silanes, which can only provide a static, single polar interface. Its specific sub-forms include a single-layer coating formed by N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propyl-ammonium chloride, and a three-dimensional hierarchical coating structure formed by compounding carboxyl PEG-PLA on this basis.

[0022] Adaptive flipping refers to the process by which the coating layer undergoes spontaneous conformational rearrangement during coagulation bath precipitation, driven by the polarity gradient of the micro-regions caused by the rapid displacement of solvent by water molecules. In this process, the originally outward-facing hydrophilic / polar ends repel and contract inward, while the hydrophobic ends are attracted and flip outward, forming deep physical entanglement with the polymer chains being precipitated. This process requires no additional crosslinking or curing agents and is entirely driven by the thermodynamics of the phase transition.

[0023] Mild ultrasound and high-intensity ultrasound are two different ultrasonic treatment processes of varying intensities used in this field for powder dispersion. Mild ultrasound refers to short-duration (5-15 min) ultrasonic treatment performed under ice bath temperature control (0-5℃) conditions, using medium to low power (150-250W) and conventional frequency (40-45kHz). Its energy is only sufficient to break up soft agglomerates formed by freeze-drying of powder, but not enough to damage the surface coating structure, and avoids solvent evaporation and air entrainment caused by prolonged ultrasonic heating. High-intensity ultrasound, on the other hand, refers to long-duration ultrasound with high power (e.g., 500W). Although it can forcibly open hard agglomerates caused by vacuum drying, its cavitation effect can damage the integrity of the coating layer and cause a large amount of air to be entrained into the slurry, forming microbubbles that are difficult to remove.

[0024] Micro / nano salt pore-forming refers to the pre-mixing of micro / nano-sized salt particles (such as NaCl with a particle size of 1-10 μm) into the coating slurry as a pore-forming agent. After the coating has cured, the salt particles are dissolved by water washing, leaving a continuous or semi-continuous microporous structure inside the coating. This process is a key means to achieve lightweight coatings and high moisture permeability. The particle size and distribution of the salt particles directly determine the pore size and porosity of the micropores. In this application, low-pressure dynamic circulating water rinsing is used instead of traditional ultrasonic or high-temperature immersion to thoroughly leach out the salt without damaging the mechanical integrity of the polymer micropore walls.

[0025] Modified MCC refers to microcrystalline cellulose that has undergone surface modification. Microcrystalline cellulose itself has high rigidity and a high aspect ratio, making it an effective reinforcing filler for improving the wear resistance of coatings. However, its surface is rich in hydroxyl groups and has strong polarity, making it prone to agglomeration in non-polar PU matrices. After treatment with modifiers (such as KH-550 silane coupling agent), its surface is grafted with organic segments compatible with the non-polar matrix, thus enabling it to disperse uniformly in PU slurries and exert excellent skeletal reinforcement.

[0026] The first aspect of this invention provides a method for preparing an antibacterial, wear-resistant, lightweight composite coating material, comprising the following steps: The nano-antibacterial component is mixed with an amphoteric silane coating agent in a solvent, and the amphoteric silane coating agent is hydrolyzed and chemically bonded to the hydroxyl groups on the surface of the nano-antibacterial component to form a dynamically regulated surface energy coating layer; wherein, the nano-antibacterial component can be silver or copper nanoparticles, and the amphoteric silane can adapt to the transformation between polar solvent and non-polar matrix environments. The obtained product was centrifuged and washed before being freeze-dried to sublimate and dehydrate the ice crystals, resulting in a loose, freeze-dried coated powder. The pressure and temperature during freeze-drying must be controlled to ensure that the ice crystals sublimate directly. The freeze-dried coated powder is dispersed in a solvent, and the soft agglomerates are broken up by gentle ultrasound. Then, it is allowed to stand under normal pressure to degas, allowing the entrained microbubbles to escape. Subsequently, it is mixed with a main slurry containing a polymer matrix and a pore-forming agent and degassed under vacuum. The degassed slurry is coated onto the substrate surface and placed in a coagulation bath for curing. During the curing process, water molecules replace the solvent to generate a local polar gradient, which drives the dynamic surface energy to regulate the adaptive flipping of the coating layer, with the hydrophobic groups facing outward and physically entangled with the precipitated polymer chain segments. The cured coating is subjected to two stages of water washing: the first stage uses room temperature pure water for pre-coagulation water washing to complete the deep entanglement and locking of the coated antibacterial particles and polymer chain segments; the second stage uses low-pressure dynamic circulating water to rinse the coating surface and leach out the pore-forming agent. The coating is then heat-set after washing.

[0027] This invention introduces a dynamic surface energy-controlled coating layer, enabling it to exhibit compatible interfacial properties under different polarity environments, fundamentally eliminating the agglomeration dynamics caused by abrupt changes in three-phase polarity. During the solidification stage in the coagulation bath, water molecules replace the solvent, creating localized solvent-poor microregions and polarity gradients. This drives the zwitterionic coating layer to adaptively flip, with the hydrophobic groups facing outwards and physically entangled with the precipitating PU segments. This achieves spontaneous deep anchoring of nanoparticles to the matrix, effectively solving the problem of easy migration and precipitation of antibacterial components. Simultaneously, the loose powder obtained through freeze-drying and sublimation dehydration completely avoids the hard agglomeration caused by capillary contraction in traditional vacuum drying, and eliminates the need for water-soluble anti-collapse agents. Gentle ultrasonic degassing under normal pressure eliminates microbubble defects caused by air entrapment in the powder. In terms of the pore-forming process, a step-by-step water washing strategy is adopted. Room temperature water pre-coagulation and locking provides sufficient time and a stable environment for entanglement. Subsequently, low-pressure dynamic water flow flushes the pores, which not only ensures the efficient washing out of salt driven by the concentration gradient difference, but also avoids the damage to the foamed micropore walls and the initial entanglement interface caused by high temperature densification and ultrasonic cavitation, thus achieving a synergistic effect of wear resistance, lightweight and high moisture permeability.

[0028] In a preferred embodiment, the zwitterionic silane coating agent is N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propyl-ammonium chloride, and its amount is 5-8 times the mass of the nano-antibacterial component. Before forming the dynamically modulated surface energy coating layer, the nano-antibacterial component is pre-coated with a carboxyl PEG-PLA composite dispersant, and then a secondary coating is performed with the zwitterionic silane coating agent to form a three-dimensional hierarchical interface. Using a specific zwitterionic silane can achieve excellent flip-response behavior; the three-dimensional hierarchical interface further optimizes the compatibility between the particles and the matrix, enhancing the anchoring strength. Specifically, the purity of N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propyl-ammonium chloride can be 97%.

[0029] In a preferred embodiment, during the formation of the dynamically controlled surface energy coating layer, the pH is adjusted to 5.0-6.5 to hydrolyze the zwitterionic silane coating agent; the freeze-drying conditions are -40℃ to -60℃, vacuum degree <10Pa, and time is 20-28h; the gentle ultrasound frequency is 40-45kHz, power is 150-250W, and it is performed in an ice bath at 0-5℃ for 5-15 minutes; the atmospheric pressure static degassing time is 20-40 minutes. Suitable pH conditions ensure the hydrolysis and bonding efficiency of the silane; the ice bath gentle ultrasound breaks up soft agglomerates without damaging the coating layer; atmospheric pressure degassing utilizes the porous structure of the freeze-dried powder to allow entrained microbubbles to naturally escape, avoiding micropores within the coating. Specifically, the freeze-drying temperature can be selected from any value among -40℃, -50℃, and -60℃; the gentle ultrasound time can be selected from any value among 5 minutes, 10 minutes, and 15 minutes.

[0030] In a preferred embodiment, the coagulation bath is a 10%-15% (w / w) DMF aqueous solution, and the solidification time is 5-10 min; the temperature of the first stage pre-coagulation water wash is 20-25°C, and the time is 2-5 min; the pressure of the second stage low-pressure dynamic circulating water flow is 0.1-0.3 MPa, and the rinsing time is 10-20 min. These parameter ranges ensure sufficient precipitation and turbulence, as well as deep physical entanglement, while the low-pressure water flow avoids shear damage.

[0031] Specifically, the time for the first stage of water washing can be selected from any value among 2 min, 3 min, and 5 min; the pressure of the second stage water flow can be selected from any value among 0.1 MPa, 0.2 MPa, and 0.3 MPa.

[0032] A second aspect of this invention provides an antibacterial, wear-resistant, lightweight composite coating material, prepared by the method described above. This material, due to its dynamic surface energy-controlled coating and adaptive flipping precipitation process, achieves deep anchoring of nanoparticles, eliminating agglomeration and microporous defects, thus exhibiting long-lasting antibacterial properties and high wear resistance.

[0033] In a preferred embodiment, the nano-antibacterial component is silver nanoparticles or copper nanoparticles with a particle size of 10-50 nm. Specifically, the particle size can be selected from any value among 10 nm, 20 nm, 30 nm, and 50 nm.

[0034] In a preferred embodiment, the main slurry comprises polyether polyurethane resin, modified microcrystalline cellulose, micro / nano salt particles, and additives, wherein the amount of micro / nano salt particles is 15%-20% of the solid content of the polyether polyurethane resin. Specifically, the micro / nano salt can be selected from NaCl, and the particle size can be 1-10 μm; the additives include foaming agents, foam leveling agents, color pastes, surfactants, etc.

[0035] In a preferred embodiment, the composite coating material is free of micropores and cracks, and the dynamic surface energy regulates the deep entanglement and anchoring of the hydrophobic groups of the coating layer with the polyether-type polyurethane resin segments. This microstructure endows the coating with excellent mechanical continuity.

[0036] In a preferred embodiment, the composite coating material exhibits a Taber abrasion loss of 5-6 mg / 500 rpm, an antibacterial rate >99.5% after 20 washes, a nano-antibacterial component concentration of <5 ppm, and a moisture permeability >4100 g / m³. 2 / 24h.

[0037] The third aspect of the present invention provides an application of the aforementioned antibacterial, wear-resistant, and lightweight composite coating material in student school bags, which is further described in Example 1.

[0038] To better illustrate the advantages of the present invention, the present invention will be further described below through detailed specific embodiments and comparative embodiments: Example 1

[0039] This embodiment 1 provides an antibacterial, wear-resistant, lightweight composite coating material and a method for preparing the coating material. The raw materials for preparing the antibacterial, wear-resistant, lightweight composite coating material include: polyether polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g, of which 70g is used for the main slurry and 20g for dispersion), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveling agent (industrial grade, 2g), silver nanoparticles (20nm dispersion, 0.1g dry basis, medical / textile grade), and N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride (97% pure, amphoteric silane, 0.6g).

[0040] The preparation method includes the following steps: Step 1: Dynamic surface energy regulation of coating.

[0041] Dissolve 0.6 g of amphoteric silane in a mixed solvent of 28 mL ethanol and 2 mL deionized water at a ratio of 1:6, adjust the pH to 5.5-6.0, and hydrolyze at room temperature for 30 min. Add silver nanoparticle dispersion dropwise while stirring at 1000 rpm, continue stirring for 60 min, and sonicate (45 kHz) for 15 min to allow the amphoteric silane to chemically bond with the hydroxyl groups on the surface of the silver nanoparticles, forming a dynamically regulated surface energy coating layer.

[0042] Step 2: Freeze-dry to obtain loose powder.

[0043] Centrifuge the above solution (8000 rpm, 15 min), discard the supernatant, and wash twice with a mixture of ethanol and water. Place the resulting wet filter cake in a freeze dryer and freeze-dry for 24 h at -50 °C and a vacuum degree <10 Pa. The ice crystals directly sublimate and dehydrate to obtain loose, non-agglomerated freeze-dried silver powder, which is then sealed and protected from light for later use.

[0044] Step 3: Mild depolymerization and preparation of pre-deaerated slurry under normal pressure.

[0045] Weigh out lyophilized silver-coated powder (based on a dry basis of 0.1g silver) and disperse it in 20g DMF. Perform gentle ice-bath ultrasonication (40kHz, 200W, ice bath 0-5℃) for 10min to break up soft agglomerates. Then, allow the dispersion to stand under normal pressure for 30min to degas, allowing entrained microbubbles to escape naturally. Separately, stir polyether-type polyurethane resin, 70g DMF, foaming agent, foam leveling agent, color paste, and surfactant for 10min. Add modified MCC and micro / nano salt particles and disperse for 20min to form the main slurry. Incorporate the pre-degassed silver dispersion into the main slurry and stir for 30min. Perform vacuum degassing for 30min on the entire mixture.

[0046] Step 4: Coating and adaptive flip precipitation.

[0047] Apply by scraping at 20g / m 2 The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% (w / w) DMF aqueous solution coagulation bath for 7 minutes. Water molecules replaced DMF, generating a local polar gradient, which drove the dynamic surface energy to regulate the adaptive flipping of the coating layer, causing the hydrophobic groups to physically entangle with the polyether polyurethane segments that were precipitating.

[0048] Step 5: Step-by-step locking and dynamic water flow hole creation.

[0049] The cured coating is first placed in a 25°C room temperature pure water bath for 3 minutes to pre-coagulate and wash, completing the deep entanglement and adhesion of the coated silver particles and polyether polyurethane segments; then it is transferred to a 25°C flowing water washing tank and sprayed with 0.2MPa low-pressure dynamic circulating water at an angle of 45 degrees for 15 minutes to thoroughly leach out the micro-nano salt particles.

[0050] Step 6: Heat setting. The coating after water washing and pore creation is hot-air baked (120℃, 5 min), cooled, and rolled up to obtain an antibacterial, wear-resistant, lightweight composite coating material. Testing showed that this coating material achieves high moisture permeability (4250 g / m²). 2 While maintaining a waterproof hydrostatic pressure of 52 cm H2O (24h), it also demonstrates that the microporous structure formed by micro-nano salt pore creation is interconnected but the pore size is controllable, and does not cause significant deterioration of waterproof performance.

[0051] The antibacterial, wear-resistant, and lightweight composite coating material prepared in Example 1 was applied to the fabric manufacturing of school bags. The fabric substrate was 210D nylon Oxford cloth, and the coating process was carried out according to steps 1-6 of Example 1, with the coating amount controlled at 20 g / m². 2 The processed fabric is cut and sewn into finished student backpacks.

[0052] Actual use tests and performance evaluations were conducted on the finished student backpack: the overall weight of the backpack is about 12% lighter than backpacks using traditional PU coated fabric; in daily use, after frequent friction from keys, book edges, etc., the coating showed no obvious wear or pilling; after 20 standard simulated hand washes, the backpack surface still maintained high antibacterial properties, and no excessive silver ion precipitation was detected in the washing liquid, fully meeting the safety standards for children's products; at the same time, due to the excellent microporous structure of the coating, the backpack's breathability and moisture permeability are significantly improved when carried in hot weather, effectively reducing stuffiness.

[0053] Example 2

[0054] This embodiment 2 provides an antibacterial, wear-resistant, lightweight composite coating material and a method for preparing the coating material.

[0055] The raw materials for preparing the antibacterial, wear-resistant, and lightweight composite coating material include: Polyether-type polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g, of which 70g is used for the main slurry and 20g for dispersion), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether-modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveler (industrial grade, 2g), copper nanoparticles (20nm dispersion, 0.12g dry basis, medical / textile grade), N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride (97% pure, amphoteric silane, 0.84g).

[0056] The preparation method includes the following steps: Step 1: Dynamic surface energy regulation of coating.

[0057] Dissolve 0.84 g of amphoteric silane in a mixed solvent of 28 mL ethanol and 2 mL deionized water at a ratio of 1:7, adjust the pH to 5.5-6.0, and hydrolyze at room temperature for 30 min. Add copper nanoparticle dispersion dropwise while stirring at 1000 rpm, continue stirring for 60 min, and sonicate (45 kHz) for 15 min to allow the amphoteric silane to chemically bond with the hydroxyl groups on the surface of the copper nanoparticles, forming a dynamically regulated surface energy coating layer.

[0058] Step 2: Freeze-dry to obtain loose powder.

[0059] Centrifuge the above solution (8000 rpm, 15 min), discard the supernatant, and wash twice with a mixed solvent of ethanol and water. Place the resulting wet filter cake in a freeze dryer and freeze-dry for 24 h at -50 °C and a vacuum degree <10 Pa. The ice crystals directly sublimate and dehydrate, yielding loose, non-agglomerated freeze-dried copper powder, which is then sealed and protected from light for later use.

[0060] Step 3: Mild depolymerization and preparation of pre-deaerated slurry under normal pressure.

[0061] Weigh out lyophilized copper-coated powder (based on 0.12g of copper on a dry basis) and disperse it in 20g of DMF. Perform gentle ice-bath ultrasonication (40kHz, 200W, ice bath 0-5℃) for 10min to break up soft agglomerates. Then, allow the dispersion to stand under normal pressure for 30min to degas, allowing entrained microbubbles to escape naturally. Separately, stir polyether-type polyurethane resin, 70g of DMF, foaming agent, foam leveling agent, color paste, and surfactant for 10min. Add modified MCC and micro / nano salt particles and disperse for 20min to form the main slurry. Incorporate the pre-degassed copper dispersion into the main slurry and stir for 30min. Perform vacuum degassing on the entire mixture for 30min.

[0062] Step 4: Coating and adaptive flip precipitation.

[0063] Apply by scraping at 20g / m 2 The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% (w / w) DMF aqueous solution coagulation bath for 7 minutes. Water molecules replaced DMF, generating a local polar gradient, which drove the dynamic surface energy to regulate the adaptive flipping of the coating layer, causing the hydrophobic groups to physically entangle with the polyether polyurethane segments that were precipitating.

[0064] Step 5: Step-by-step locking and dynamic water flow hole creation.

[0065] The cured coating is first pre-coagulated and washed in a 25°C room temperature pure water bath for 3 minutes to achieve deep entanglement and adhesion between the coated copper particles and the polyether polyurethane segments. Then, it is transferred to a 25°C flowing water washing bath and rinsed for 15 minutes using a 0.2MPa low-pressure dynamic circulating water jet at a 45-degree angle to thoroughly leach out the micro-nano salt particles. Step 6: Heat setting. The water-washed and pore-forming coating is then hot-air baked (120°C, 5 minutes), cooled, and rolled up to obtain an antibacterial, wear-resistant, lightweight composite coating material.

[0066] Example 3

[0067] This embodiment 3 provides an antibacterial, wear-resistant, lightweight composite coating material and a method for preparing the coating material.

[0068] The raw materials for preparing the antibacterial, wear-resistant, and lightweight composite coating material include: polyether polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g, of which 70g is used for the main slurry and 20g for dispersion), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveling agent (industrial grade, 2g), silver nanoparticles (20nm dispersion, 0.1g dry basis, medical / textile grade), carboxyl PEG-PLA composite dispersant (0.2g), and N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride (97% pure, amphoteric silane, 0.6g).

[0069] The preparation method includes the following steps: Step 1: Dynamic Surface Energy Controlled Coating. First, a dispersion of 0.1 g (dry weight) of silver nanoparticles was pre-coated with a carboxyl-PEG-PLA composite dispersant and stirred for 20 minutes. Then, 0.6 g of amphoteric silane was dissolved in a mixed solvent of 28 mL ethanol and 2 mL deionized water at a ratio of 1:6, and the pH was adjusted to 5.5-6.0. The mixture was then hydrolyzed at room temperature for 30 minutes. The pre-coated silver nanoparticles were added to the amphoteric silane solution and stirred continuously at 1000 rpm for 60 minutes, followed by sonication (45 kHz) for 15 minutes. This allowed the amphoteric silane to chemically bond with the hydroxyl groups on the surface of the silver nanoparticles, forming a three-dimensional hierarchical dynamic surface energy controlled coating layer.

[0070] Step 2: Freeze-dry to obtain loose powder.

[0071] Centrifuge the above solution (8000 rpm, 15 min), discard the supernatant, and wash twice with a mixture of ethanol and water. Place the resulting wet filter cake in a freeze dryer and freeze-dry for 24 h at -50 °C and a vacuum degree <10 Pa. The ice crystals directly sublimate and dehydrate to obtain loose, non-agglomerated freeze-dried silver powder, which is then sealed and protected from light for later use.

[0072] Step 3: Gentle depolymerization and preparation of pre-deaerated slurry under normal pressure. Weigh lyophilized coated silver powder (based on 0.1g of silver on a dry basis) and disperse it in 20g of DMF. Perform gentle ice bath ultrasonication (40kHz, 200W, ice bath 0-5℃) for 10min to break up soft agglomerates. Then, allow the dispersion to stand under normal pressure for 30min to deaerate, allowing entrained microbubbles to escape naturally. Separately, stir polyether-type polyurethane resin, 70g of DMF, foaming agent, foam leveling agent, color paste, and surfactant for 10min. Add modified MCC and micro / nano salt particles and disperse for 20min to form the main slurry. Incorporate the pre-deaerated silver dispersion into the main slurry and stir for 30min. Perform vacuum deaeration on the entire mixture for 30min.

[0073] Step 4: Coating and Adaptive Flip Sedimentation. A doctor blade coating method was used at 20 g / m³. 2 The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% (w / w) DMF aqueous solution coagulation bath for 7 minutes. Water molecules replaced DMF, generating a local polar gradient, which drove the dynamic surface energy to regulate the adaptive flipping of the coating layer, causing the hydrophobic groups to physically entangle with the polyether polyurethane segments that were precipitating.

[0074] Step 5: Step-by-step adhesion and dynamic water flow pore creation. The cured coating is first immersed in a 25°C room temperature pure water bath for 3 minutes to pre-coagulate and wash, completing the deep entanglement and adhesion of the coated silver particles and polyether polyurethane segments; then it is transferred to a 25°C flowing water washing tank and sprayed with 0.2MPa low-pressure dynamic circulating water at a 45-degree angle for 15 minutes to thoroughly leach out the micro-nano salt particles.

[0075] Step 6: Heat setting. The coating after water washing and pore making is hot-air baked (120℃, 5min), cooled and rolled up to obtain an antibacterial, wear-resistant, lightweight composite coating material.

[0076] Comparative Example 1 Comparative Example 1 provides a composite coating material and a method for preparing the coating material. The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not perform zwitterionic silane coating and freeze-drying treatment on the silver nanoparticles, and the water washing adopts a conventional immersion method.

[0077] The raw materials for preparing the composite coating material include: polyether polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveling agent (industrial grade, 2g), and silver nanoparticles (20nm dispersion, 0.1g dry basis, medical / textile grade).

[0078] The preparation method of Comparative Example 1 includes the following steps: Step 1: Slurry preparation.

[0079] Polyether-type polyurethane resin, 90g DMF, foaming agent, foam leveling agent, color paste, and surfactant were stirred for 10 minutes. Modified MCC and micro / nano salt particles were added and dispersed for 20 minutes. Then, 0.1g of silver nanoparticle dispersion (dry basis) was directly added, stirred for 30 minutes, and then the whole mixture was vacuum degassed for 30 minutes.

[0080] Step 2: Coating and precipitation.

[0081] Apply by scraping at 20g / m 2The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% DMF aqueous solution coagulation bath for 7 minutes.

[0082] Step 3: Rinse with water as usual. Immerse the cured coating directly in a 25°C water bath for 20 minutes to leach out the micro-nano salt particles.

[0083] Step 4: Heat setting. The water-washed coating is hot-air baked (120℃, 5 min), cooled and rolled up to obtain the composite coating material.

[0084] Comparative Example 2 Comparative Example 2 provides a composite coating material and a method for preparing the coating material.

[0085] The difference from Example 1 is that: Comparative Example 2 uses traditional short-chain silane KH-550 instead of zwitterionic silane, and uses traditional vacuum drying instead of freeze drying. In addition, due to the hard agglomeration of powder, strong ultrasonic dispersion is used, and water washing is done by conventional soaking.

[0086] The raw materials for preparing the composite coating material in Comparative Example 2 include: polyether polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g, of which 70g is used for the main paste and 20g for dispersion), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveling agent (industrial grade, 2g), silver nanoparticles (20nm dispersion, 0.1g dry basis, medical / textile grade), and KH-550 silane (0.6g).

[0087] The preparation method of Comparative Example 2 includes the following steps: Step 1: Short-chain silane coating.

[0088] Dissolve 0.6 g of KH-550 silane in a 1:6 ratio in a mixed solvent of 28 mL ethanol and 2 mL deionized water, adjust the pH to 5.5-6.0, and hydrolyze at room temperature for 30 min. Add the silver nanoparticle dispersion dropwise while stirring at 1000 rpm, continue stirring for 60 min, and sonicate (45 kHz) for 15 min to allow KH-550 to bond with the hydroxyl groups on the surface of the silver nanoparticles.

[0089] Step 2: Vacuum drying.

[0090] The above solution was centrifuged (8000 rpm, 15 min), the supernatant was discarded, and the solution was washed twice with a mixture of ethanol and water. The resulting wet filter cake was placed in a vacuum drying oven and dried under vacuum at 60 °C for 12 h to obtain coated silver powder.

[0091] Step 3: Preparation of high-intensity ultrasonic slurry.

[0092] Vacuum-dried coated silver powder (based on a dry basis of 0.1g silver) was weighed and dispersed in 20g DMF. Due to the presence of hard agglomerates in the powder, it was dispersed by high-intensity ultrasonic treatment (45kHz, 500W) for 30min. Separately, polyether-type polyurethane resin, 70g DMF, foaming agent, foam leveling agent, color paste, and surfactant were stirred for 10min. Modified MCC and micro / nano salt particles were added and dispersed for 20min to form the main slurry. The ultrasonically dispersed silver dispersion was then added to the main slurry and stirred for 30min. The entire mixture was then subjected to vacuum degassing for 30min.

[0093] Step 4: Coating and Precipitation. A scraping method is used with a coating density of 20 g / m³. 2 The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% DMF aqueous solution coagulation bath for 7 minutes.

[0094] Step 5: Rinse with water as usual. Immerse the cured coating directly in a 25°C water bath for 20 minutes to leach out the micro-nano salt particles.

[0095] Step 6: Heat setting. The water-washed coating is hot-air baked (120℃, 5min), cooled and rolled up to obtain the composite coating material.

[0096] Comparative Example 3 Comparative Example 3 provides a composite coating material and a method for preparing the coating material.

[0097] The difference from Example 1 is that although Comparative Example 3 uses zwitterionic silane, water-soluble anti-collapse agent PEG-400 is added after centrifugation, and vacuum drying is used. Subsequently, strong ultrasonic dispersion and room temperature ultrasonic water washing are used.

[0098] The raw materials for preparing the composite coating material in Comparative Example 3 include: polyether polyurethane resin (industrial grade, 100g), DMF (analytical grade, 90g, of which 70g is used for the main paste and 20g for dispersion), modified MCC (KH-550 modified, 8g), micro / nano salt particles (NaCl, 4μm, 18g), colored paste (textile grade, 3g), surfactant (polyether modified silicone oil, 2g), foaming agent (industrial grade, 2g), foam leveling agent (industrial grade, 2g), silver nanoparticles (20nm dispersion, 0.1g dry basis, medical / textile grade), N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride (97% pure, amphoteric silane, 0.6g), and PEG-400 anti-collapse agent (0.5g).

[0099] The preparation method of Comparative Example 3 includes the following steps: Step 1: Dynamic surface energy regulation of coating.

[0100] Dissolve 0.6 g of amphoteric silane in a mixed solvent of 28 mL ethanol and 2 mL deionized water at a ratio of 1:6, adjust the pH to 5.5-6.0, and hydrolyze at room temperature for 30 min. Add silver nanoparticle dispersion dropwise while stirring at 1000 rpm, continue stirring for 60 min, and sonicate (45 kHz) for 15 min to allow the amphoteric silane to chemically bond with the hydroxyl groups on the surface of the silver nanoparticles, forming a dynamically regulated surface energy coating layer.

[0101] Step 2: Vacuum drying.

[0102] Centrifuge the above solution (8000 rpm, 15 min), discard the supernatant, and wash twice with a mixture of ethanol and water. Add 0.5 g of PEG-400 as an anti-collapse agent to the wet filter cake obtained by centrifugation, stir evenly, and place in a vacuum drying oven. Dry under vacuum at 60 °C for 12 h to obtain coated silver powder.

[0103] Step 3: Preparation of high-intensity ultrasonic slurry.

[0104] Vacuum-dried coated silver powder (based on 0.1g of silver on a dry basis) was weighed and dispersed in 20g of DMF. Due to the presence of some hard agglomerates, it was dispersed by high-intensity ultrasonic treatment (45kHz, 500W) for 30 minutes. Separately, polyether-type polyurethane resin, 70g of DMF, foaming agent, foam leveling agent, color paste, and surfactant were stirred for 10 minutes. Modified MCC and micro / nano salt particles were added and dispersed for 20 minutes to form the main slurry. The ultrasonically dispersed silver dispersion was then added to the main slurry and stirred for 30 minutes. The entire mixture was then subjected to vacuum degassing for 30 minutes.

[0105] Step 4: Coating and Precipitation. A scraping method is used with a coating density of 20 g / m³. 2 The degassed slurry was coated onto the surface of Oxford cloth and then cured in a 12% DMF aqueous solution coagulation bath for 7 minutes.

[0106] Step 5: Ultrasonic water washing. Place the cured coating in a 25°C room temperature water bath and perform ultrasonic water washing (45kHz, 15min) to leach out the micro-nano salt particles.

[0107] Step 6: Heat setting. The water-washed coating is hot-air baked (120℃, 5min), cooled and rolled up to obtain the composite coating material.

[0108] The following performance tests and analyses were conducted on Examples 1-3 and Comparative Examples 1-3, and the specific performance test methods are as follows: Antibacterial rate test: Refer to GB / T 20944.3-2008 to test the initial antibacterial rate against Escherichia coli after 24 hours; the wash resistance was tested again after 20 cycles of static washing.

[0109] Taber abrasion loss test: Refer to GB / T 21196.2, load 500g, test the mass loss after 500 revolutions.

[0110] Breathability and moisture permeability test: Refer to GB / T 32610-2016 to test the moisture permeability.

[0111] Metal precipitation test: After 10 washes, the precipitation concentration of Ag or Cu in the washing solution was detected by ICP-MS.

[0112] SEM microscopic observation: The microstructure of the coating cross section was observed using a scanning electron microscope.

[0113] Weather resistance yellowing grade test: Yellowing grade is assessed in accordance with GB / T 30669-2014.

[0114] The test results are shown in Table 1 below:

[0115] Table 1 As shown in Table 1, Examples 1-3 of the present invention are significantly superior to Comparative Examples 1-3 in terms of antibacterial longevity, abrasion resistance, anti-precipitation safety, and moisture permeability. Example 1 maintained an antibacterial rate of over 99.5% after 20 washes, with a silver precipitation of only 4.2 ppm, far lower than the 18.5 ppm of Comparative Example 1. Taber abrasion was reduced to 5.8 mg / 500 rpm, while also exhibiting a moisture permeability of 4250 g / m³. 2 The high moisture permeability of 24h and the waterproof hydrostatic pressure of 52cm H2O (see the main text of Example 1) demonstrate that the dynamic surface energy regulation coating and the step-by-step water washing and locking process achieve deep anchoring of nanoparticles and complete protection of the microstructure, achieving breathability and lightweight without sacrificing the basic waterproof performance of the coating.

[0116] In Comparative Example 1, bare silver nanoparticles were directly added to the slurry. Due to interfacial polarity mismatch, the particles severely agglomerated at the three-phase interface, leading to mechanical embrittlement and a surge in wear resistance loss to 14.5 mg / 500 rpm. Simultaneously, the lack of physical entanglement resulted in significant detachment after washing, causing the antibacterial rate to plummet to 80.5% and silver precipitation to reach as high as 18.5 ppm, posing a serious safety risk. The obvious black spots appearing on the surface during weathering tests are macroscopic evidence of this. The increased number of discontinuous micropores observed in the three phases via SEM directly explains the reason for the low moisture permeability but deteriorated mechanical properties.

[0117] Comparative Example 2 used a traditional short-chain silane, KH-550. Because it only provides a static, single-polar interface and lacks the ability to adapt to polar phase transitions, desorption during precipitation led to partial agglomeration and interface breakpoints. Simultaneously, traditional vacuum drying caused hard powder agglomeration, necessitating strong ultrasonic dispersion. This not only damaged the coating layer but also prevented air from being expelled through atmospheric pressure pre-degassing. Ultimately, the coating's wear resistance and antibacterial longevity were inferior to the examples, and its moisture permeability decreased due to the damaged microporous structure.

[0118] Although Comparative Example 3 used amphoteric silane, it employed PEG-400 anti-collapse agent combined with vacuum drying. Vacuum drying still resulted in hard agglomeration, and strong ultrasonic dispersion damaged the system. More critically, water-soluble PEG leached out during subsequent water washing, leaving microscopic cavities around the particles, providing channels for the detachment of antibacterial particles, leading to a silver precipitation of 8.8 ppm. Simultaneously, the cavitation effect generated by the ultrasonic water washing directly damaged the foam micropore walls, and SEM clearly showed micropore rupture and collapse, resulting in accelerated weathering and yellowing, and disrupting the balance between moisture permeability and abrasion resistance.

[0119] Example 3, by introducing a carboxyl-based PEG-PLA composite dispersant for pre-coating, constructed a three-dimensional hierarchical interface. SEM showed that it had minimal interfacial cracks, optimized particle size distribution (<60nm), and further reduced wear loss to 5.2mg / 500 rpm. After 20 washes, the antibacterial rate reached 99.8%, and the silver precipitation decreased to 3.0ppm, demonstrating that the three-dimensional hierarchical interface further enhanced compatibility and anchoring strength. Example 2 replaced the coating with copper nanoparticles. Its SEM results showed that the coating also exhibited a three-phase, crack-free, microporous, and uniformly dispersed copper particle microstructure. Combined with its excellent wear resistance and low precipitation data, it verified the universality of the dynamic flipping entanglement process of this invention for different nano-antibacterial components.

[0120] In summary, the core improvement principle and beneficial technical effects of this invention are reflected in the following three aspects: (1) Elimination of agglomeration and embrittlement, and integrity of microstructure: This invention utilizes the "adaptive flipping" characteristic of the zwitterionic coating layer to ensure that it exhibits compatible interfacial properties under different polarity environments, fundamentally eliminating the agglomeration dynamics caused by abrupt changes in three-phase polarity; freeze-drying and sublimation dehydration avoids hard agglomeration caused by capillary contraction; and gentle ultrasonic degassing under normal pressure eliminates microbubbles generated by powder entrapment. This ensures the high dispersibility of the nano-antibacterial components in the slurry and coating, and the coating is free of cracks, broken skeletons, and micropores, resulting in a significant improvement in wear resistance.

[0121] (2) Long-lasting antibacterial effect and high safety: The local polar gradient-driven flipping entanglement mechanism allows hydrophobic groups to be deeply embedded in the PU matrix; the room temperature pre-coagulation locking process provides sufficient time and a stable environment for entanglement, avoiding damage to the initial anchoring points by ultrasound or high-temperature water flow; and no water-soluble anti-collapse agent is used, avoiding particle detachment channels caused by leaching voids. This ensures deep physical anchoring of nanoparticles in the PU matrix, long-lasting antibacterial effect after washing, and extremely low Ag / Cu precipitation, far below the safety threshold for children's products, ensuring long-lasting safety.

[0122] (3) Synergistic effect of wear resistance and lightweight breathability: The dynamic water flow at room temperature and low pressure assists in pore formation, which not only ensures the efficient washing out of salt driven by concentration gradient difference, but also avoids the excessive densification of PU caused by high temperature (which hinders salt release), and avoids the shearing damage of the foam micropore wall and the shaking off of the entangled interface caused by ultrasonic cavitation. Thus, the three-effect synergy of high moisture permeability, high wear resistance and lightweight is achieved without sacrificing any core indicators.

Claims

1. A method for preparing an antibacterial, wear-resistant, lightweight composite coating material, characterized in that, Includes the following steps: The nano-antibacterial component is mixed with an amphoteric silane coating agent in a solvent, and the amphoteric silane coating agent is hydrolyzed and chemically bonded to the hydroxyl groups on the surface of the nano-antibacterial component to form a dynamically regulated surface energy coating layer. The obtained product was centrifuged and washed, then freeze-dried to sublimate and dehydrate the ice crystals, resulting in a loose freeze-dried coated powder. The freeze-dried coated powder is dispersed in a solvent, and the soft agglomerates are broken up by gentle ultrasound. Then, it is allowed to stand under normal pressure to degas, allowing the entrained microbubbles to escape. Subsequently, it is mixed with a main slurry containing a polymer matrix and a pore-forming agent and degassed under vacuum. The degassed slurry is coated onto the substrate surface and placed in a coagulation bath for curing. During the curing process, water molecules replace the solvent to generate a local polar gradient, which drives the dynamic surface energy to regulate the adaptive flipping of the coating layer, with the hydrophobic groups facing outward and physically entangled with the precipitated polymer chain segments. The cured coating is then subjected to two stages of water washing: the first stage uses room temperature pure water for pre-coagulation water washing to complete the deep entanglement and adhesion of the coated antibacterial particles and polymer chain segments. The second stage uses low-pressure dynamic circulating water to rinse the coating surface and leach out the pore-forming agent. The coating is then heat-set after washing.

2. The preparation method according to claim 1, characterized in that, The zwitterionic silane coating agent is N-(3-trimethoxysilylpropyl)-N,N-dimethyl-N-propylammonium chloride, and its amount is 5-8 times the mass of the nano antibacterial component. Before forming a dynamically controlled surface energy coating layer, a carboxyl PEG-PLA composite dispersant is used to pre-coat the nano antibacterial component, and then a zwitterionic silane coating agent is used for secondary coating to form a three-dimensional hierarchical interface.

3. The preparation method according to claim 1, characterized in that, When forming a dynamically controlled surface energy coating layer, the pH is adjusted to 5.0-6.5 to hydrolyze the zwitterionic silane coating agent; the freeze-drying conditions are -40℃ to -60℃, vacuum degree <10Pa, and time is 20-28h; the frequency of the mild ultrasound is 40-45kHz, the power is 150-250W, and it is carried out in an ice bath at 0-5℃ for 5-15 minutes; the time for static degassing under normal pressure is 20-40 minutes.

4. The preparation method according to claim 1, characterized in that, The coagulation bath is a DMF aqueous solution with a mass fraction of 10%-15%, and the solidification time is 5-10 min; the temperature of the first stage room temperature pure water pre-coagulation water washing is 20-25℃, and the time is 2-5 min; the pressure of the second stage low pressure dynamic circulating water flow is 0.1-0.3 MPa, and the rinsing time is 10-20 min.

5. An antibacterial, wear-resistant, lightweight composite coating material, characterized in that, It is prepared by the preparation method according to any one of claims 1-4.

6. The antibacterial, wear-resistant, lightweight composite coating material according to claim 5, characterized in that, The nano-antibacterial component is silver nanoparticles or copper nanoparticles with a particle size of 10-50 nm.

7. The antibacterial, wear-resistant, lightweight composite coating material according to claim 5, characterized in that, The main slurry includes polyether polyurethane resin, modified microcrystalline cellulose, micro / nano salt particles and additives, wherein the amount of micro / nano salt particles is 15%-20% of the solid content of the polyether polyurethane resin.

8. The antibacterial, wear-resistant, lightweight composite coating material according to claim 5, characterized in that, The composite coating material has no micropores or cracks inside, and the dynamic surface energy can regulate the deep entanglement and anchoring of the hydrophobic groups of the coating layer with the polyether-type polyurethane resin chain segments.

9. The antibacterial, wear-resistant, lightweight composite coating material according to claim 5, characterized in that, The composite coating material exhibits a Taber abrasion loss of 5-6 mg / 500 rpm, an antibacterial rate of >99.5% after 20 washes, a nano-antibacterial component concentration of <5 ppm, and a moisture permeability of >4100 g / m³. 2 / 24h.

10. The application of the antibacterial, wear-resistant, lightweight composite coating material as described in any one of claims 5-9 in student school bags.

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