Self-repairing composite floor for clean room and preparation method of self-repairing composite floor

Abstract

The invention discloses a self-repairing composite floor for a clean room and a preparation method of the self-repairing composite floor, and the preparation method comprises the following steps: carrying out amination treatment on nano silicon dioxide and carbon quantum dots by using a silane coupling agent, and sulfonating polyethersulfone ketone by using concentrated sulfuric acid; the preparation method comprises the following steps: carrying out curing treatment on epoxy resin, an amine curing agent, N-hydroxyethyl maleimide and tetrakis (3-mercaptopropionic acid) pentaerythritol ester to obtain epoxy-mercaptan resin; the preparation method comprises the following steps: carrying out prepolymerization reaction on vacuum dehydrated polyester polyol, tetrahydroxyethyl ethylenediamine, furanpropanol, diisocyanate, a catalyst, 2, 2 '-thiodiethanol and hydroxyl silicone oil to obtain a star-shaped polyurethane prepolymer, adding epoxy-thiol resin, glyceryl borate, sulfonated polyethersulfone ketone, aminated silicon dioxide, aminated carbon quantum dots and an auxiliary agent, carrying out ultrasonic treatment, and carrying out drying to obtain the star-shaped polyurethane resin. The self-repairing coating material is obtained; and coating the self-repairing coating material on the surface of a base plate, and performing hot-pressing curing molding to obtain the self-repairing composite floor for the clean room.

Description

Technical Field

[0001] This invention relates to the field of flooring technology, and in particular to a self-healing composite floor for cleanrooms and its preparation method. Background Technology

[0002] Cleanrooms are critical environments in fields such as electronics, pharmaceuticals, and bioengineering, where strict control over environmental cleanliness, temperature, humidity, and static charge is essential. Their flooring materials must possess high cleanliness, antistatic properties, chemical resistance, wear resistance, durability, and ease of cleaning and disinfection. Simultaneously, they must maintain dimensional stability and a certain level of comfort to ensure the safety of production processes and personnel. Traditional cleanroom floors (such as epoxy resin floors and PVC rolls) are prone to scratches, indentations, and micro-cracks during use due to equipment movement, material handling, and cleaning friction. This not only affects aesthetics and cleanliness but can also foster microbial growth and accumulate static charge, thereby interfering with the operation of precision equipment, increasing the risk of contamination, and raising maintenance costs.

[0003] Self-healing composite flooring is a new type of intelligent flooring material. Its core component is a layer or more of a functional, self-healing curing coating applied to the floor substrate. This curing coating utilizes intrinsic self-healing mechanisms (such as dynamic covalent bonds: Diels-Alder bonds, borate ester bonds, disulfide bonds; and non-covalent bonds: hydrogen bonds, ionic coordination bonds) or introduces exogenous repair units (such as microcapsules) within the material. When physical damage such as wear and scratches occurs on the floor surface, it can activate a repair reaction under stimuli such as heat, humidity, or pressure, automatically restoring the continuity and functionality of the coating. This significantly extends the floor's lifespan, reduces maintenance intervention, and continuously meets the stringent requirements of clean environments. Currently, cleanroom floor repair largely relies on manual repairs or complete replacement after shutdown, which is not only inefficient and costly but also may interrupt production and introduce contamination during maintenance.

[0004] However, most existing self-healing curing coating technologies still have significant limitations: their self-healing behavior is often only effective at room temperature or within a narrow temperature range, making it difficult to adapt to the complex working environment of cleanrooms. Moreover, many self-healing curing coatings, in pursuit of repair efficiency, have to sacrifice mechanical strength, hardness, abrasion resistance, and chemical resistance, making it difficult to meet the stringent requirements of clean environments for the comprehensive performance of floor materials. Therefore, developing a new curing coating system that enables the prepared self-healing composite flooring for cleanrooms to efficiently trigger its self-healing function in a wide temperature range and humidity variation environment, while also possessing excellent mechanical properties, abrasion resistance, chemical corrosion resistance, antistatic properties, and long-term environmental stability, effectively reducing maintenance costs, extending service life, and ensuring the continuous and safe operation of cleanrooms, has become a key technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0005] In view of this, the present invention provides a self-healing composite floor for cleanrooms and its preparation method. The composite floor constructs an intelligent self-healing coating on the substrate surface with a star-shaped polyurethane network as the main chain and an epoxy-thiol network as the auxiliary chain segment. It synergistically introduces functional components such as glycerol borate ester, aminated nano-silica, carbon quantum dots, sulfonated polyethersulfone ketone, and hydroxyl silicone oil to form a multi-layer dynamic bonding system in the coating. This endows the floor with the ability to trigger efficient self-healing under various environmental stimuli such as heat, humidity, or room temperature. It achieves rapid damage repair in the wide temperature range, humidity fluctuations, and daily chemical disinfection environment of cleanrooms, significantly improving the mechanical strength, wear resistance, impact resistance, and interfacial bonding of the floor. At the same time, it has excellent antistatic properties, chemical corrosion resistance, dimensional stability, and environmental durability. It can effectively resist common physical wear, chemical erosion, and moist heat sterilization operations in cleanrooms, significantly extending the service life of the composite floor.

[0006] To achieve the above objectives, this invention proposes a method for preparing a self-healing composite floor for cleanrooms, comprising the following steps: S1, silane coupling agent amination treatment of nano-silica and carbon quantum dots, concentrated sulfuric acid sulfonate treatment of polyethersulfone ketone; S2. After curing epoxy resin, amine curing agent, N-hydroxyethyl maleimide and pentaerythritol tetrakis(3-mercaptopropionic acid) ester, epoxy-thiol resin is obtained. S3. Vacuum-dehydrated polyester polyol is prepolymerized with tetrahydroxyethyl ethylenediamine, furanol and diisocyanate, catalyst, 2,2'-thiodiethanol, and hydroxyl silicone oil to obtain a star-shaped polyurethane prepolymer. Epoxy-thiol resin, glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, and additives are then added and ultrasonically treated to obtain a self-healing coating material. S4. Apply the self-healing coating material to the surface of the substrate and cure it by hot pressing to obtain a self-healing composite floor for cleanrooms.

[0007] In some embodiments of the present invention, step S1 includes: S1.1 Disperse nano-silica and carbon quantum dots separately in ethanol, add silane coupling agent, reflux at 70~80℃ for 6~7h, and then sonicate at 300~400 W for 25~30min to obtain aminated silica and aminated carbon quantum dots. S1.2. Place the polyethersulfone ketone powder in a vacuum dryer at 70-80℃ for 2-3 hours, slowly add it to 98% concentrated sulfuric acid in an ice bath, stir and react at 25-40℃ for 2-4 hours, and then adjust the pH to 7 with 5% NaHCO3 solution to obtain sulfonated polyethersulfone ketone.

[0008] In some embodiments of the present invention, in step S1, the particle size of the nano-silica is 10-30 nm, the particle size of the carbon quantum dots is 3-5 nm, the silane coupling agent is 3-aminopropyltriethoxysilane, the particle size of the polyethersulfone ketone is <50 μm, the mass ratio of the silica to the silane coupling agent is 10-15:1-2, the mass ratio of the carbon quantum dots to the silane coupling agent is 1-3:5-10, and the volume-to-mass ratio of the concentrated sulfuric acid to the polyethersulfone ketone is 10-12 mL:1 g.

[0009] In some embodiments of the present invention, step S2 includes: adding epoxy resin and N-hydroxyethyl maleimide to a reaction vessel respectively, pre-reacting at 55-60°C for 1-2 hours, adding an amine curing agent, pre-curing at 50-60°C for 20-30 minutes, adding pentaerythritol tetrakis(3-mercaptopropionic acid), and aging at 25-30°C for 20-24 hours to obtain epoxy-thiol resin.

[0010] In some embodiments of the present invention, in step S2, the epoxy resin is bisphenol A epoxy resin, the amine curing agent is one or more of diethylenetriamine, polyetheramine D230 and ketimide, the mass ratio of the epoxy resin to the N-hydroxyethyl maleimide is 5~8:1~3, the amount of the amine curing agent is 25~35% of the mass of the epoxy resin, and the amount of the pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 10~15% of the mass of the epoxy-thiol resin.

[0011] In some embodiments of the present invention, step S3 includes: S3.1. The polyester polyol is dehydrated at 100~110℃ and -0.1MPa vacuum for 1~2h, and then added to a reaction vessel along with tetrahydroxyethyl ethylenediamine and furanyl propanol. The temperature is lowered to 40~45℃, and diisocyanate and catalyst are slowly added dropwise. The reaction is carried out under nitrogen protection for 1~1.5h, and then the temperature is raised to 50~60℃. 2,2'-thiodiethanol and hydroxyl silicone oil are added, and the reaction is continued for 2~3h to obtain a star-shaped polyurethane prepolymer. S3.2 Add epoxy-thiol resin to star-shaped polyurethane prepolymer, react at 60~80℃ for 4~5h, then add glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, leveling agent, and defoamer, and sonicate at 300~400W for 30~40min to obtain self-healing coating material.

[0012] In some embodiments of the present invention, in step S3, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol, and polyethylene adipate; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, and 4,4'-diphenylmethane diisocyanate; the catalyst is dibutyltin dilaurate; the leveling agent is BYK-333 leveling agent; and the defoamer is BYK-055 defoamer.

[0013] In some embodiments of the present invention, in step S3, the mass ratio of the diisocyanate to the tetrahydroxyethyl ethylenediamine is 4-7:1-3, the mass ratio of the polyester polyol, the furanyl propanol, and the 2,2'-thiodiethanol is 1-4:1-4:1-3, the amount of the hydroxyl silicone oil is 5-8% of the mass of the star-shaped polyurethane prepolymer, the amount of the catalyst is 0.1-0.3% of the mass of the star-shaped polyurethane prepolymer, and the mass ratio of the epoxy-thiol resin to the star-shaped polyurethane prepolymer is 4-6. The amount of the glycerol borate ester is 5-7% of the mass of the self-healing coating material, the amount of the sulfonated polyethersulfone ketone is 1.5-3% of the mass of the self-healing coating material, the amount of the aminated silica is 2-3% of the mass of the self-healing coating material, the amount of the aminated carbon quantum dots is 0.5-1.5% of the mass of the self-healing coating material, the amount of the leveling agent is 0.3-0.5% of the mass of the self-healing coating material, and the amount of the defoamer is 0.1-0.3% of the mass of the self-healing coating material.

[0014] In some embodiments of the present invention, step S4 includes: uniformly coating the self-healing coating material onto the surface of a high-density fiberboard or metal composite board substrate, controlling the coating thickness to be 0.5~1.0 mm, pre-curing at 60~80℃ for 2~3 h, then pressing and curing at 100~120℃ and 5~10 MPa pressure for 1~2 h using a hot press, and obtaining a self-healing composite floor for cleanrooms after natural cooling.

[0015] This invention proposes a self-healing composite floor for cleanrooms, prepared by the method described above, comprising a substrate layer and a self-healing coating. The self-healing coating comprises nano-silica, carbon quantum dots, ethanol, silane coupling agent, polyethersulfone ketone, concentrated sulfuric acid, epoxy resin, N-hydroxyethyl maleimide, amine curing agent, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, polyester polyol, tetrahydroxyethyl ethylenediamine, furanylpropanol, diisocyanate, catalyst, 2,2'-thiodiethanol, hydroxyl silicone oil, glyceryl borate ester, leveling agent, and defoamer. The nano-silica, as a nano-reinforcing filler, forms covalent bonds with the isocyanate groups of polyurethane through surface amylation, thereby improving the interfacial adhesion of the floor coating, enhancing the mechanical strength and wear resistance of the self-healing coating, and simultaneously assisting in the uniform distribution of heat to promote self-healing. The carbon quantum dots accelerate electron transfer through the quantum confinement effect, catalyze the redox exchange of dynamic disulfide bonds, improve the room temperature self-healing efficiency of the self-healing coating, and enhance the antistatic properties of the floor to meet the antistatic requirements of cleanrooms. The polyethersulfone ketone forms hydrogen bonds with the hydroxyl groups of the epoxy-thiol resin through sulfonic acid groups, and simultaneously generates ionic bonds with the amine curing agent, thereby enhancing the hydrolysis resistance and chemical corrosion resistance of the self-healing coating, and improving the interface toughness to adapt to the cleanroom cleaning and disinfection environment. The epoxy resin serves as a rigid network skeleton, and its epoxy groups react with the amine curing agent to form a three-dimensional cross-linked structure, providing the self-healing coating with basic hardness and chemical resistance, and ensuring the dimensional stability of the floor. The N-hydroxyethyl maleimide is incorporated into the network through the reaction of hydroxyl groups and epoxy groups. The steric hindrance of its N-hydroxyethyl group protects the carbon-carbon double bond from amine / thiol attack and retains the carbon-carbon double bond for Diels-Alder crosslinking reaction, thereby realizing the high-temperature thermally triggered self-healing of the self-healing coating and maintaining the high-temperature stability of the coating to adapt to the high-temperature sterilization environment of cleanrooms. The pentaerythritol tetrakis(3-mercaptopropionic acid) ester, as a polythiol crosslinking agent, has its thiol group reacting with the epoxy group to generate dynamic disulfide bonds after oxidation, thus giving the self-healing coating room temperature oxidation-reduction self-healing ability to repair daily wear. The polyester polyol, as a flexible segment of polyurethane, reacts with diisocyanate to form a soft segment, which lowers the glass transition temperature and ensures the flexibility and repair function of the self-healing coating at low temperatures. The tetrahydroxyethyl ethylenediamine, as the core chain extender of the star-shaped polyurethane, provides four hydroxyl groups to form a four-arm structure, enhances the intermolecular chain interaction, inhibits the low-temperature brittleness of the self-healing coating, and improves the impact resistance of the floor. The furan propanol introduces furan rings into the polyurethane chain end through the reaction of hydroxyl groups with isocyanate groups, providing furan groups for the Diels-Alder crosslinking reaction and realizing the thermally reversible crosslinking network of the self-healing coating; The diisocyanate is used to provide rigid segments and a rigid structure for the polyurethane. Its isocyanate groups react with polyols / amines to enhance the chemical stability and impact resistance of the self-healing coating and extend the service life of the floor. The 2,2'-thiodiethanol acts as a chain extender, with its thio group oxidized into a dynamic disulfide bond, while providing flexible chain segments to balance the strength and toughness of the self-healing coating and adapt to the movement requirements of cleanroom equipment. The hydroxyl silicone oil is embedded into the polyurethane chain through the reaction of terminal hydroxyl groups with isocyanate groups, introducing siloxane segments, thereby improving the hydrophobicity and UV aging resistance of the self-healing coating and reducing cleaning residue. The glycerol borate ester is used to form dynamic borate ester bonds with epoxy ring-opening products, responding to moisture / temperature to achieve humidity-assisted self-healing of the self-healing coating, adapting to the humidity fluctuation environment of the clean room.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a star-shaped polyurethane prepolymer constructed by reacting polyester polyol, tetrahydroxyethyl ethylenediamine, furanyl propanol, 2,2'-thiodiethanol, hydroxyl silicone oil, and diisocyanate. This prepolymer forms dynamic urethane bonds and a rich supramolecular hydrogen bond network within the coating, endowing the flooring with excellent humidity and thermal self-healing capabilities. This significantly improves the flooring's repair efficiency and environmental adaptability under a wide range of temperature and humidity conditions in cleanrooms. Furthermore, by introducing furan rings and thioether bonds, and utilizing the active groups in the prepolymer to react with epoxy-thiol resin to form an interpenetrating network structure, and leveraging the Diels-Alder reversible reaction between maleimide double bonds and furan rings, a stable high-temperature self-healing network is successfully constructed. This enables the flooring to effectively resist thermal damage caused by high-temperature sterilization operations in cleanrooms and achieve highly efficient heat-triggered repair. The introduction of glycerol borate ester and aminated carbon quantum dots, utilizing the glycerol borate ester bonds to form dynamic covalent bonds with the hydroxyl groups of the epoxy-thiol resin, further expands the humidity-responsive repair network, significantly improving the flooring's performance in humid environments or during cleaning. The humidity-assisted self-healing efficiency after disinfection is enhanced by utilizing the reaction of amino groups on the surface of aminated carbon quantum dots with isocyanate groups in polyurethane prepolymer to form covalent urea bonds, which are firmly bound in the network. The quantum confinement effect of carbon quantum dots effectively accelerates electron transfer and catalyzes the redox exchange reaction of dynamic disulfide bonds in the system, thereby significantly improving the self-healing efficiency of the floor at room temperature and reducing dependence on additional energy input. With the synergistic effect of fillers and additives such as aminated silica, the mechanical strength, hardness, wear resistance and impact resistance of the floor coating are significantly enhanced. The coating's hydrolysis resistance, interfacial bonding strength and dimensional stability are effectively improved, enabling it to withstand frequent equipment movement, material transportation and cleaning operations in clean rooms, greatly extending the service life of the floor. At the same time, the prepared composite floor has excellent antistatic properties, chemical corrosion resistance and good surface hydrophobicity, making it easy to clean and maintain. It can maintain a high cleanliness surface for a long time, meeting the comprehensive and stringent requirements of high-level clean rooms for floor materials, and effectively reducing maintenance costs and production interruption risks. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] This invention proposes a method for preparing self-healing composite flooring for cleanrooms, comprising the following steps: S1, silane coupling agent amination treatment of nano-silica and carbon quantum dots, concentrated sulfuric acid sulfonate treatment of polyethersulfone ketone.

[0019] Step S1 includes: S1.1 Disperse nano-silica and carbon quantum dots separately in ethanol, add silane coupling agent, reflux at 70~80℃ for 6~7h, and then sonicate at 300~400 W for 25~30min to obtain aminated silica and aminated carbon quantum dots.

[0020] Ethanol is used as a solvent to effectively dissolve the silane coupling agent, promoting its hydrolysis to form silanols, while simultaneously dispersing the nanoparticles and preventing agglomeration. Controlling the reaction temperature at 70-80℃, close to the boiling point of ethanol, effectively accelerates the hydrolysis and condensation of the silane coupling agent, avoiding violent boiling. Reacting at this temperature for 6-7 hours ensures complete hydrolysis of the silane coupling agent and its reaction with the nanoparticle surface. Ultrasonic treatment effectively breaks down physical agglomerates such as hydrogen-bonded silica, promoting uniform coating of the nanoparticle surface by the silane coupling agent. Controlling the ultrasonic power at 300-400 W avoids incomplete dispersion or damage to chemical bonds. Ultrasonic treatment at this power for 25-30 minutes avoids incomplete dispersion due to too short a time or detachment of the grafted silane coupling agent due to too long a time.

[0021] S1.2. Place the polyethersulfone ketone powder in a vacuum dryer at 70-80℃ for 2-3 hours, slowly add it to 98% concentrated sulfuric acid in an ice bath, stir and react at 25-40℃ for 2-4 hours, and then adjust the pH to 7 with 5% NaHCO3 solution to obtain sulfonated polyethersulfone ketone.

[0022] Vacuum drying of polyethersulfone (PES) effectively removes adsorbed moisture from PES powder, preventing the exothermic reaction between moisture and concentrated sulfuric acid, which could lead to localized overheating and side reactions. It also improves the permeability of concentrated sulfuric acid to PES. Controlling the drying temperature at 70-80°C effectively prevents incomplete moisture removal or softening and sticking of PES. Oxidation treatment of PES with 98% concentrated sulfuric acid provides strong sulfonation capabilities due to the high concentration of H2SO4. Slowly adding PES to the 98% concentrated sulfuric acid under ice bath conditions effectively controls initial exothermic reactions, preventing PES degradation or carbonization. Controlling the reaction temperature at 25-40°C effectively balances the reaction rate and side reactions, preventing excessively slow reactions or excessively high temperatures that could cause main chain breakage. Reacting at this temperature for 2-4 hours effectively controls the degree of PES sulfonation, laying the foundation for subsequent reactions. Adjusting the pH of the system to 7 using a 5% NaHCO3 solution can effectively neutralize residual sulfuric acid, prevent acid-catalyzed hydrolysis of polyethersulfone ketone, and avoid the acidic environment from damaging subsequent coating materials.

[0023] In step S1, the particle size of nano-silica is 10~30nm, the particle size of carbon quantum dots is 3~5nm, the silane coupling agent is 3-aminopropyltriethoxysilane, the particle size of polyethersulfone ketone is <50μm, the mass ratio of silica to silane coupling agent is 10~15:1~2, the mass ratio of carbon quantum dots to silane coupling agent is 1~3:5~10, and the volume-mass ratio of concentrated sulfuric acid to polyethersulfone ketone is 10~12mL:1g.

[0024] S2. After curing epoxy resin, amine curing agent, N-hydroxyethyl maleimide and pentaerythritol tetrakis(3-mercaptopropionic acid) ester, epoxy-thiol resin is obtained.

[0025] Step S2 includes: Epoxy resin and N-hydroxyethyl maleimide were added to a reaction vessel and pre-reacted at 55-60°C for 1-2 hours. An amine curing agent was added and pre-cured at 50-60°C for 20-30 minutes. Then, pentaerythritol tetrakis(3-mercaptopropionic acid) ester was added and aged at 25-30°C for 20-24 hours to obtain epoxy-thiol resin.

[0026] The pre-reaction temperature is controlled at 55-60℃ to avoid both excessively low temperatures leading to a slow epoxy-hydroxyl reaction and excessively high temperatures causing premature participation of the maleimide double bond in side reactions. Pre-reaction at this temperature for 1-2 hours ensures sufficient reaction between the hydroxyl and epoxy groups of N-hydroxyethyl maleimide, guaranteeing its conversion rate. The pre-curing temperature is controlled at 50-60℃ to accelerate the ring-opening reaction between the amine and epoxy, preventing premature gelation due to excessively high temperatures. Pre-curing at this temperature for 20-30 minutes effectively controls the epoxy conversion rate, retaining some epoxy groups for subsequent thiol reactions. The aging temperature is controlled at 25-30℃. Low temperature inhibits the Michael addition of thiol and maleimide, ensuring that the thiol preferentially reacts with the remaining epoxy groups. Simultaneously, room temperature ensures a moderate amine-catalyzed thiol-epoxy reaction rate. Aging at this temperature for 20-24 hours guarantees the conversion rate of thiol and epoxy groups, while some thiol groups are oxidized to dynamic disulfide bonds.

[0027] In step S2, the epoxy resin is bisphenol A epoxy resin, the amine curing agent is one or more of diethylenetriamine, polyetheramine D230 and ketimide, the mass ratio of epoxy resin to N-hydroxyethyl maleimide is 5~8:1~3, the amount of amine curing agent is 25~35% of the mass of epoxy resin, and the amount of pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 10~15% of the mass of epoxy-thiol resin.

[0028] S3. Vacuum-dehydrated polyester polyol is reacted with tetrahydroxyethyl ethylenediamine, furanol and diisocyanate, catalyst, 2,2'-thiodiethanol, and hydroxyl silicone oil to obtain a star-shaped polyurethane prepolymer. Epoxy-thiol resin, glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, and additives are added and ultrasonically treated to obtain a self-healing coating material.

[0029] Step S3 includes: S3.1. The polyester polyol is dehydrated at 100~110℃ and -0.1MPa vacuum for 1~2h, and then added to a reaction vessel along with tetrahydroxyethyl ethylenediamine and furanyl propanol. The temperature is lowered to 40~45℃, and diisocyanate and catalyst are slowly added dropwise. The reaction is carried out under nitrogen protection for 1~1.5h, and then the temperature is raised to 50~60℃. 2,2'-thiodiethanol and hydroxyl silicone oil are added, and the reaction is continued for 2~3h to obtain a star-shaped polyurethane prepolymer.

[0030] High-temperature vacuum dehydration effectively removes trace amounts of moisture from polyester polyols, ensuring the reaction system remains strictly dry and preventing side reactions between isocyanate groups and water, which could lead to urea bonds and carbon dioxide, resulting in bubbles or uncontrolled crosslinking. Maintaining the system temperature at 100-110℃ ensures moisture evaporation while keeping it below the polyol's decomposition temperature, preventing decomposition losses. A vacuum of -0.1 MPa reduces system pressure, promoting the removal of moisture and low-boiling-point volatiles, ensuring that isocyanate does not react with water to generate carbon dioxide in subsequent reactions, thus avoiding bubbles or side reactions. Dehydration at this temperature and vacuum for 1-2 hours effectively removes most of the moisture from the polyol raw materials, reducing the system moisture content to below 0.05%, minimizing side reactions and raw material decomposition losses, and laying the foundation for efficient subsequent prepolymerization.

[0031] Controlling the reaction temperature at 40-45℃ effectively controls the exothermic rate of the reaction between isocyanate groups and hydroxyl groups, avoiding local overheating and side reactions, while also reducing the self-polymerization reaction of isocyanate groups. Nitrogen gas protection effectively prevents the reaction of moisture in the air with the isocyanate groups, avoiding carbon dioxide generation and uncontrolled crosslinking of the prepolymer. Reacting at this temperature for 1-1.5 hours ensures effective polymerization of isocyanate groups and hydroxyl groups. Controlling the reaction temperature at 50-60℃ accelerates the reaction rate, ensuring the full reaction of the remaining isocyanate groups. Reacting at this temperature for 2-3 hours ensures effective bonding of the remaining isocyanate groups with 2,2'-thiodiethanol and the hydroxyl groups on the surface of the hydroxyl silicone oil, fully introducing thioether bonds, enhancing chain segment flexibility and dynamic exchange capacity, forming an organic-inorganic hybrid structure, improving the hydrophobicity and surface lubricity of the coating, and reducing internal stress.

[0032] In the preparation of polyurethane prepolymers, the determination of isocyanate group (-NCO) content is a critical quality control step, directly affecting the molecular weight, crosslinking density, and performance of the final coating. Using di-n-butylamine titration to track the consumption of isocyanate groups allows researchers / producers to understand the concentration of remaining isocyanate in the system during the reaction, enabling precise control of the reaction endpoint.

[0033] Take a star-shaped polyurethane prepolymer sample from the middle of the reaction vessel, accurately weigh 1.000±0.005 g, add the sample to 20 mL of anhydrous toluene, then add 10 mL of di-n-butylamine solution, stir magnetically at 300-400 rpm for 15-20 min, dilute with 50 mL of isopropanol, add 3-5 drops of bromocresol green indicator, and titrate with 0.1 mol / L hydrochloric acid standard solution to the yellow endpoint. Record the volume of hydrochloric acid consumed as V1. Set up a blank control group and titrate the di-n-butylamine solution without the sample using the same method, recording the volume of hydrochloric acid consumed as V0. Calculate the concentration of isocyanate groups based on the volume of hydrochloric acid consumed to determine whether the reaction is complete. Stop the reaction when the concentration of isocyanate groups reaches the set value. The calculation formula is: in, V 0 represents the volume of hydrochloric acid consumed by the blank control group, in mL; V 1 represents the volume of hydrochloric acid consumed during sample titration, in mL; C HCl The concentration of hydrochloric acid is 0.1 mol / L; m The sample is the mass of a polyurethane prepolymer sample, 1.000 ± 0.005 g.

[0034] In the above detection process, the preset concentration of isocyanate groups is 3%~8%.

[0035] S3.2 Add epoxy-thiol resin to star-shaped polyurethane prepolymer, react at 60~80℃ for 4~5h, then add glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, leveling agent, and defoamer, and sonicate at 300~400W for 30~40min to obtain self-healing coating material.

[0036] Controlling the reaction temperature at 60-80℃ accelerates the ring-opening reaction of epoxy-thiol while avoiding side reactions such as epoxy group self-polymerization. This also helps maintain the stability of the polyurethane prepolymer and prevents its thermal degradation. Reacting at this temperature for 4-5 hours ensures sufficient reaction between the epoxy groups and the thiol to form a cross-linked network, while allowing some unreacted isocyanates to react with the hydroxyl or amino groups of the epoxy-thiol system. Controlling the ultrasonic power at 300-400W ensures sufficient energy to break up nanoparticle aggregation while avoiding excessive shearing that damages the polymer chains. Ultrasonication at this power for 30-40 minutes ensures uniform dispersion of the nanofiller, forming a stable composite system.

[0037] In step S3, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol, and polyethylene adipate; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, and 4,4'-diphenylmethane diisocyanate; the catalyst is dibutyltin dilaurate; the leveling agent is BYK-333 leveling agent; and the defoamer is BYK-055 defoamer.

[0038] In step S3, the mass ratio of diisocyanate to tetrahydroxyethyl ethylenediamine is 4-7:1-3, the mass ratio of polyester polyol, furanol, and 2,2'-thiodiethanol is 1-4:1-4:1-3, the amount of hydroxyl silicone oil is 5-8% of the mass of the star-shaped polyurethane prepolymer, the amount of catalyst is 0.1-0.3% of the mass of the star-shaped polyurethane prepolymer, the mass ratio of epoxy-thiol resin to star-shaped polyurethane prepolymer is 4-6:5-7, and glycerol boric acid... The amount of ester used is 5-7% of the mass of the self-healing coating material, the amount of sulfonated polyethersulfone ketone used is 1.5-3% of the mass of the self-healing coating material, the amount of aminated silica used is 2-3% of the mass of the self-healing coating material, the amount of aminated carbon quantum dots used is 0.5-1.5% of the mass of the self-healing coating material, the amount of leveling agent used is 0.3-0.5% of the mass of the self-healing coating material, and the amount of defoamer used is 0.1-0.3% of the mass of the self-healing coating material.

[0039] S4. Apply the self-healing coating material to the surface of the substrate and cure it by hot pressing to obtain a self-healing composite floor for cleanrooms.

[0040] Step S4 includes: The self-healing coating material is uniformly coated on the surface of high-density fiberboard or metal composite board substrate, and the coating thickness is controlled to be 0.5~1.0mm. It is pre-cured at 60~80℃ for 2~3h, and then pressed and cured by hot press at 100~120℃ and 5~10MPa pressure for 1~2h. After natural cooling, the self-healing composite floor for cleanrooms is obtained.

[0041] The coating thickness is controlled between 0.5 and 1.0 mm. This range represents the optimal balance between functionality, durability, and economy, providing sufficient repair for physical damage while effectively preventing coating defects. This ensures the coating possesses adequate mechanical strength, wear-resistant layer thickness, and repair agent reserves to meet the requirements of high-frequency passage and equipment movement in cleanrooms. The pre-curing temperature is controlled between 60 and 80°C, below the reverse reaction temperature of the Diels-Alder (DA) reaction. This prevents premature dissociation of the reversible network before final curing, protecting the integrity of the heat-triggered self-healing function. Pre-curing at this temperature for 2-3 hours allows any residual solvents, moisture, or small molecules of reaction byproducts to slowly and completely escape from the coating, preventing defects such as bubbles, pinholes, or delamination during subsequent high-temperature, high-pressure pressing. This lays a solid foundation for subsequent hot pressing. Controlling the hot-pressing temperature at 100~120℃ is the ideal temperature range for the Diels-Alder cycloaddition reaction of furan and maleimide to form reversible covalent bonds, effectively constructing a thermally reversible self-healing network. Pressing at this temperature helps the coating and substrate achieve a tighter physical bond and possible chemical bond, significantly enhancing interlayer adhesion. Controlling the hot-pressing pressure at 5~10MPa forces the pre-cured coating into close contact with the substrate surface, overcoming microscopic unevenness, expanding the effective contact area, promoting physical wetting and intermolecular forces at the interface, greatly improving the adhesion between the coating and the substrate, preventing future delamination, and effectively removing any trace air bubbles that may remain during the initial curing process, improving coating density and controlling thickness uniformity. Hot-pressing at this temperature and pressure for 1~2 hours ensures that the cross-linking reaction and DA reaction deep within the coating can proceed fully, avoiding a "burnt outside, raw inside" situation, thus guaranteeing the uniformity and stability of product performance.

[0042] This invention proposes a self-healing composite floor for cleanrooms, prepared by the method described above, comprising a substrate layer and a self-healing coating. The self-healing coating comprises nano-silica, carbon quantum dots, ethanol, silane coupling agent, polyethersulfone ketone, concentrated sulfuric acid, epoxy resin, N-hydroxyethyl maleimide, amine curing agent, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, polyester polyol, tetrahydroxyethyl ethylenediamine, furanylpropanol, diisocyanate, catalyst, 2,2'-thiodiethanol, hydroxyl silicone oil, glyceryl borate ester, leveling agent, and defoamer. Nano-silica, as a nano-reinforcing filler, forms covalent bonds with the isocyanate groups of polyurethane through surface amylation, thereby improving the interfacial adhesion of the floor coating, enhancing the mechanical strength and wear resistance of the self-healing coating, and simultaneously assisting in the uniform distribution of heat to promote self-healing. Carbon quantum dots accelerate electron transfer through quantum confinement effect, catalyze the redox exchange of dynamic disulfide bonds, improve the room temperature self-healing efficiency of self-healing coatings, and enhance the antistatic properties of floors to meet the antistatic requirements of cleanrooms. Polyethersulfone ketone forms hydrogen bonds with the hydroxyl groups of epoxy-thiol resin through sulfonic acid groups, and at the same time forms ionic bonds with amine curing agents, which enhances the hydrolysis resistance and chemical corrosion resistance of the self-healing coating, and improves the interface toughness, making it suitable for the cleanroom cleaning and disinfection environment. Epoxy resin, as a rigid network skeleton, reacts with amine curing agents to form a three-dimensional cross-linked structure, providing the basic hardness and chemical resistance of the self-healing coating and ensuring the dimensional stability of the floor. N-hydroxyethyl maleimide integrates into the network through the reaction of hydroxyl groups and epoxy groups. The steric hindrance of its N-hydroxyethyl group protects the carbon-carbon double bond from amine / thiol attack, and retains the carbon-carbon double bond for Diels-Alder crosslinking reaction, realizing high-temperature thermal triggering self-healing of the self-healing coating, while maintaining the high-temperature stability of the coating and adapting to the high-temperature sterilization environment of cleanrooms. Pentaerythritol tetrakis(3-mercaptopropionic acid) ester, as a polythiol crosslinking agent, has its thiol groups reacting with epoxy groups to generate dynamic disulfide bonds after oxidation, giving the self-healing coating room temperature oxidation-reduction self-healing ability to repair daily wear. Polyester polyols, as flexible segments of polyurethane, react with diisocyanates to form soft segments, which lowers the glass transition temperature and ensures the flexibility and repair function of the self-healing coating at low temperatures. Tetrahydroxyethyl ethylenediamine, as the core chain extender of star-shaped polyurethane, provides four hydroxyl groups to form a four-arm structure, enhances the intermolecular chain forces, inhibits the low-temperature brittleness of the self-healing coating, and improves the impact resistance of the floor. Furan propanol introduces furan rings into the polyurethane chain ends through the reaction of hydroxyl groups with isocyanate groups, providing furan groups for the Diels-Alder crosslinking reaction and realizing a thermally reversible crosslinking network for the self-healing coating; Diisocyanates are used to provide rigid segments and a rigid structure for polyurethane. Their isocyanate groups react with polyols / amines to enhance the chemical stability and impact resistance of self-healing coatings and extend the service life of flooring. 2,2'-Thiodiethanol, as a chain extender, oxidizes its thio group into a dynamic disulfide bond, while providing flexible chain segments to balance the strength and toughness of the self-healing coating and adapt to the movement requirements of cleanroom equipment. Hydroxyl silicone oil is embedded into the polyurethane chain through the reaction of terminal hydroxyl groups with isocyanate groups, introducing siloxane segments, which improves the hydrophobicity and UV aging resistance of the self-healing coating and reduces cleaning residue. Glyceryl borate esters are used to form dynamic borate ester bonds with epoxy ring-opening products, responding to moisture / temperature to achieve humidity-assisted self-healing of self-healing coatings, adapting to the humidity fluctuation environment of cleanrooms.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a self-healing composite floor for cleanrooms, characterized in that the steps include... include: S1, silane coupling agent amination treatment of nano-silica and carbon quantum dots, concentrated sulfuric acid sulfonate treatment of polyethersulfone ketone; S2. After curing epoxy resin, amine curing agent, N-hydroxyethyl maleimide and pentaerythritol tetrakis(3-mercaptopropionic acid) ester, epoxy-thiol resin is obtained. S3. Vacuum-dehydrated polyester polyol is prepolymerized with tetrahydroxyethyl ethylenediamine, furanol and diisocyanate, catalyst, 2,2'-thiodiethanol, and hydroxyl silicone oil to obtain a star-shaped polyurethane prepolymer. Epoxy-thiol resin, glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, and additives are then added and ultrasonically treated to obtain a self-healing coating material. S4. Apply the self-healing coating material to the surface of the substrate and cure it by hot pressing to obtain a self-healing composite floor for cleanrooms.

2. The method for preparing a self-healing composite floor for cleanrooms according to claim 1, characterized in that, Step S1 includes: S1.1 Disperse nano-silica and carbon quantum dots separately in ethanol, add silane coupling agent, reflux at 70~80℃ for 6~7h, and then sonicate at 300~400 W for 25~30min to obtain aminated silica and aminated carbon quantum dots. S1.

2. Place the polyethersulfone ketone powder in a vacuum dryer at 70-80℃ for 2-3 hours, slowly add it to 98% concentrated sulfuric acid in an ice bath, stir and react at 25-40℃ for 2-4 hours, and then adjust the pH to 7 with 5% NaHCO3 solution to obtain sulfonated polyethersulfone ketone.

3. The method for preparing a self-healing composite floor for cleanrooms according to claim 2, characterized in that, In step S1, the particle size of the nano-silica is 10-30 nm; the particle size of the carbon quantum dots is 3-5 nm; the silane coupling agent is 3-aminopropyltriethoxysilane; the particle size of the polyethersulfone ketone is <50 μm; the mass ratio of the silica to the silane coupling agent is 10-15:1-2; the mass ratio of the carbon quantum dots to the silane coupling agent is 1-3:5-10; and the volume-to-mass ratio of the concentrated sulfuric acid to the polyethersulfone ketone is 10-12 mL:1 g.

4. The method for preparing a self-healing composite floor for cleanrooms according to claim 1, characterized in that, Step S2 includes: adding epoxy resin and N-hydroxyethyl maleimide into a reaction vessel, pre-reacting at 55~60℃ for 1~2h, adding an amine curing agent, pre-curing at 50~60℃ for 20~30min, adding pentaerythritol tetrakis(3-mercaptopropionic acid), and aging at 25~30℃ for 20~24h to obtain epoxy-thiol resin.

5. The method for preparing a self-healing composite floor for cleanrooms according to claim 4, characterized in that, In step S2, the epoxy resin is bisphenol A epoxy resin; the amine curing agent is one or more of diethylenetriamine, polyetheramine D230, and ketimide; the mass ratio of the epoxy resin to the N-hydroxyethyl maleimide is 5~8:1~3; the amount of the amine curing agent is 25~35% of the mass of the epoxy resin; and the amount of pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 10~15% of the mass of the epoxy-thiol resin.

6. The method for preparing a self-healing composite floor for cleanrooms according to claim 1, characterized in that, Step S3 includes: S3.

1. The polyester polyol is dehydrated at 100~110℃ and -0.1MPa vacuum for 1~2h, and then added to a reaction vessel along with tetrahydroxyethyl ethylenediamine and furanyl propanol. The temperature is lowered to 40~45℃, and diisocyanate and catalyst are slowly added dropwise. The reaction is carried out under nitrogen protection for 1~1.5h, and then the temperature is raised to 50~60℃. 2,2'-thiodiethanol and hydroxyl silicone oil are added, and the reaction is continued for 2~3h to obtain a star-shaped polyurethane prepolymer. S3.2 Add epoxy-thiol resin to star-shaped polyurethane prepolymer, react at 60~80℃ for 4~5h, then add glyceryl borate, sulfonated polyethersulfone ketone, aminated silica, aminated carbon quantum dots, leveling agent, and defoamer, and sonicate at 300~400W for 30~40min to obtain self-healing coating material.

7. The method for preparing a self-healing composite floor for cleanrooms according to claim 6, characterized in that, In step S3, the polyester polyol is one or more of polycaprolactone diol, polycarbonate diol, and polyethylene adipate; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, and 4,4'-diphenylmethane diisocyanate; the catalyst is dibutyltin dilaurate; the leveling agent is BYK-333 leveling agent; the defoamer is BYK-055 defoamer; the mass ratio of the diisocyanate to the tetrahydroxyethyl ethylenediamine is 4~7:1~3; the mass ratio of the polyester polyol, the furanyl propanol, and the 2,2'-thiodiethanol is 1~4:1~4:1~3; and the amount of hydroxyl silicone oil used is equal to the mass of the star-shaped polyurethane prepolymer. The amount of the catalyst is 0.1-0.3% of the mass of the star-shaped polyurethane prepolymer; the mass ratio of the epoxy-thiol resin to the star-shaped polyurethane prepolymer is 4-6:5-7; the amount of the glycerol borate ester is 5-7% of the mass of the self-healing coating material; the amount of the sulfonated polyethersulfone ketone is 1.5-3% of the mass of the self-healing coating material; the amount of the aminated silica is 2-3% of the mass of the self-healing coating material; the amount of the aminated carbon quantum dots is 0.5-1.5% of the mass of the self-healing coating material; the amount of the leveling agent is 0.3-0.5% of the mass of the self-healing coating material; and the amount of the defoamer is 0.1-0.3% of the mass of the self-healing coating material.

8. The method for preparing a self-healing composite floor for cleanrooms according to claim 1, characterized in that, Step S4 includes: uniformly coating the self-healing coating material onto the surface of a high-density fiberboard or metal composite board substrate, controlling the coating thickness to be 0.5~1.0mm, pre-curing at 60~80℃ for 2~3h, then pressing and curing at 100~120℃ and 5~10MPa pressure for 1~2h using a hot press, and obtaining the self-healing composite floor for cleanrooms after natural cooling.

9. A self-healing composite floor for cleanrooms, characterized in that, The self-healing composite flooring for cleanrooms is prepared by the method described in any one of claims 1-8, comprising a substrate layer and a self-healing coating; the self-healing coating comprises nano-silica, carbon quantum dots, ethanol, silane coupling agent, polyethersulfone ketone, concentrated sulfuric acid, epoxy resin, N-hydroxyethyl maleimide, amine curing agent, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, polyester polyol, tetrahydroxyethyl ethylenediamine, furanol, diisocyanate, catalyst, 2,2'-thiodiethanol, hydroxyl silicone oil, glyceryl borate ester, leveling agent, and defoamer; wherein... The nano-silica, as a nano-reinforcing filler, forms covalent bonds with the isocyanate groups of polyurethane through surface amylation, thereby improving the interfacial adhesion of the floor coating, enhancing the mechanical strength and wear resistance of the self-healing coating, and simultaneously assisting in the uniform distribution of heat to promote self-healing. The carbon quantum dots accelerate electron transfer through the quantum confinement effect, catalyze the redox exchange of dynamic disulfide bonds, improve the room temperature self-healing efficiency of the self-healing coating, and enhance the antistatic properties of the floor to meet the antistatic requirements of cleanrooms. The polyethersulfone ketone forms hydrogen bonds with the hydroxyl groups of the epoxy-thiol resin through sulfonic acid groups, and simultaneously generates ionic bonds with the amine curing agent, thereby enhancing the hydrolysis resistance and chemical corrosion resistance of the self-healing coating, and improving the interface toughness to adapt to the cleanroom cleaning and disinfection environment. The epoxy resin serves as a rigid network skeleton, and its epoxy groups react with the amine curing agent to form a three-dimensional cross-linked structure, providing the self-healing coating with basic hardness and chemical resistance, and ensuring the dimensional stability of the floor. The N-hydroxyethyl maleimide is incorporated into the network through the reaction of hydroxyl groups and epoxy groups. The steric hindrance of its N-hydroxyethyl group protects the carbon-carbon double bond from amine / thiol attack and retains the carbon-carbon double bond for Diels-Alder crosslinking reaction, thereby realizing the high-temperature thermally triggered self-healing of the self-healing coating and maintaining the high-temperature stability of the coating to adapt to the high-temperature sterilization environment of cleanrooms. The pentaerythritol tetrakis(3-mercaptopropionic acid) ester, as a polythiol crosslinking agent, has its thiol group reacting with the epoxy group to generate dynamic disulfide bonds after oxidation, thus giving the self-healing coating room temperature oxidation-reduction self-healing ability to repair daily wear. The polyester polyol, as a flexible segment of polyurethane, reacts with diisocyanate to form a soft segment, which lowers the glass transition temperature and ensures the flexibility and repair function of the self-healing coating at low temperatures. The tetrahydroxyethyl ethylenediamine, as the core chain extender of the star-shaped polyurethane, provides four hydroxyl groups to form a four-arm structure, enhances the intermolecular chain interaction, inhibits the low-temperature brittleness of the self-healing coating, and improves the impact resistance of the floor. The furan propanol introduces furan rings into the polyurethane chain end through the reaction of hydroxyl groups with isocyanate groups, providing furan groups for the Diels-Alder crosslinking reaction and realizing the thermally reversible crosslinking network of the self-healing coating; The diisocyanate is used to provide rigid segments and a rigid structure for the polyurethane. Its isocyanate groups react with polyols / amines to enhance the chemical stability and impact resistance of the self-healing coating and extend the service life of the floor. The 2,2'-thiodiethanol acts as a chain extender, with its thio group oxidized into a dynamic disulfide bond, while providing flexible chain segments to balance the strength and toughness of the self-healing coating and adapt to the movement requirements of cleanroom equipment. The hydroxyl silicone oil is embedded into the polyurethane chain through the reaction of terminal hydroxyl groups with isocyanate groups, introducing siloxane segments, thereby improving the hydrophobicity and UV aging resistance of the self-healing coating and reducing cleaning residue. The glycerol borate ester is used to form dynamic borate ester bonds with epoxy ring-opening products, responding to moisture / temperature to achieve humidity-assisted self-healing of the self-healing coating, adapting to the humidity fluctuation environment of the clean room.

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