Self-repairing temperature-adjusting antibacterial paper-based fiber reinforced calcium silicate board and preparation method thereof

Abstract

The invention discloses a self-repairing temperature-adjusting antibacterial paper-based fiber reinforced calcium silicate board and a preparation method thereof.The self-repairing temperature-adjusting antibacterial paper-based fiber reinforced calcium silicate board comprises a biomass-based composite core material layer and a self-repairing intelligent coating, and a three-dimensional communicated network-shaped micro-channel structure is arranged in the biomass-based composite core material layer; wherein the biomass-based composite core material layer comprises the following materials in percentage by mass: 50-70% of a gelling matrix raw material, 10-20% of reinforced fibers, 5-12% of a phase change energy storage unit, 1-4% of an embedded antibacterial agent and 0.5-2% of a process additive; the intelligent coating on the surface layer is combined with a dynamic covalent bond network and a photo-thermal antibacterial unit, so that the surface of the plate can be self-repaired when being slightly damaged, the powerful antibacterial performance is activated under illumination, and the problem that a traditional functional coating is prone to failure is solved.

Description

Technical Field

[0001] This invention belongs to the field of building decoration and functional materials technology, specifically referring to a self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board and its preparation method. Background Technology

[0002] Calcium silicate board, as a non-combustible and durable green building material, is widely used in interior walls, ceilings, and exterior envelope systems. With increasing demands for building health, energy conservation, and sustainability, the market is placing higher demands on the functionality of building materials, expecting them not only to provide structural support but also to proactively improve the indoor environment. However, existing calcium silicate board technologies and their preparation methods still suffer from the following significant drawbacks: Single-function problem and performance degradation: Traditional calcium silicate boards mainly focus on mechanical and fire resistance properties, lacking the ability to actively regulate indoor thermal comfort, microbial control, and long-term durability. Although applying a single-function coating (such as antibacterial or hydrophobic) to the surface of the board can partially improve performance, such coatings are prone to failure due to wear, scratches, or aging during long-term use, and it is difficult to combine functions.

[0003] Resource utilization and environmental protection issues: Conventional production uses quartz sand and lime as silicon and calcium sources, which is energy-intensive and dependent on natural mineral resources. Some studies have tried using industrial solid wastes such as fly ash and slag, but the product performance (such as strength and whiteness) is not stable. Although there are reports of using waste paper fibers as reinforcement, they are usually directly incorporated, which fails to systematically solve the problems of fiber dispersion, interfacial bonding, and negative impact on the water resistance of the board, thus limiting the dosage and performance improvement.

[0004] Lack of temperature regulation capability: As a wall material, traditional calcium silicate board itself lacks the ability to regulate indoor temperature fluctuations. Although phase change materials (PCMs) can be directly impregnated or mixed into the substrate, there are technical bottlenecks such as easy leakage of PCMs, poor compatibility with the substrate, and severe degradation of thermal performance after multiple cycles. Using microencapsulation technology to encapsulate PCMs is an effective approach, but how to maintain the integrity of microcapsules in the highly alkaline and high-pressure environment of hydrothermal synthesis in calcium silicate boards, and achieve their uniform dispersion in the substrate, remains a technical challenge that has not yet been well solved.

[0005] Insufficient functional synergy: Existing technologies mostly adopt a "physical superposition" approach, such as simply mixing antibacterial agents, phase change energy storage capsules, and substrates. In this method, each functional unit operates independently and may even cause performance interference (e.g., some antibacterial agents affect the hydration of cementitious materials), failing to achieve a synergistic effect of "1+1>2". The dense internal structure of the board limits the effective action of any functional additives to within the material, making it difficult to actively and efficiently interact with the environment.

[0006] Therefore, developing a novel calcium silicate board that can overcome the above-mentioned defects, namely having long-term self-maintenance capability, intelligent temperature buffering, efficient broad-spectrum antibacterial properties, and synergistic enhancement of various functions based on the high-value utilization of solid waste, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the needs and problems mentioned in the background above, the present invention provides a self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board and its preparation method, so as to at least partially solve the above problems.

[0008] According to the technical solution of the present invention, a self-healing temperature-regulating antibacterial paper-based fiber reinforced calcium silicate board is provided, comprising: a biomass-based composite core material layer and a self-healing intelligent coating, wherein the biomass-based composite core material layer is provided with a three-dimensional interconnected network-like microchannel structure. The biomass-based composite core layer comprises the following materials by mass percentage: The composition includes 50-70% cementitious matrix raw materials, 10-20% reinforcing fibers, 5-12% phase change energy storage units, 1-4% embedded antibacterial agents, and 0.5-2% process aids. The cementitious matrix raw materials include calcareous raw materials, siliceous raw materials, and silicate cement. The molar ratio of the calcium-based raw material to the silicon-based raw material is 0.7-0.9; The reinforcing fiber is waste paper pulp fiber that has undergone deinking and descaling treatment; The self-healing smart coating is formed by cross-linking and curing a film-forming matrix and a functional filler. The film-forming matrix is ​​a hybrid polymer network of phosphate ester and protonated siloxane based on dynamic imine bonds and phosphate ester bonds.

[0009] Preferably, the thickness of the self-healing smart coating is 50-200 μm; the functional filler is a composite antibacterial agent formed by loading nano-copper selenide onto modified oyster shell powder, and the functional filler accounts for 5-15% of the total mass of the self-healing smart coating.

[0010] Preferably, the calcium raw material is calcined and ground waste oyster shell powder with a particle size D50 ≤ 45 μm; The siliceous raw material is rice husk ash with a particle size D50≤20μm, and the content of highly active amorphous silica in the siliceous raw material is ≥90%.

[0011] Preferably, the phase change energy storage unit is a phase change energy storage capsule with paraffin as the core and silica as the wall material, with a phase change temperature range of 22-28℃, a capsule particle size of 5-30μm, and an encapsulation rate of ≥85%.

[0012] Preferably, the network-like microchannel structure is a network-like porous channel formed in the core material layer by a biodegradable template method, with a channel diameter of 0.5-2 mm and a porosity accounting for 3-8% of the total volume of the core material layer; the inner wall of the network-like porous channel is loaded with tourmaline powder or nano-titanium dioxide air purification material.

[0013] Preferably, the embedded antibacterial agent is a composite antibacterial agent formed by loading nano-copper selenide onto modified oyster shell powder; the beating degree of the waste paper pulp fiber is controlled at 35-45°SR.

[0014] On the other hand, the present invention also provides a method for preparing a self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board, comprising the following steps: Raw material pretreatment: Prepare siliceous raw materials, calcium-based raw materials, reinforcing fibers, phase change energy storage capsules, and embedded antibacterial agents respectively; Core material slurry preparation and molding: Calcium raw materials, siliceous raw materials, silicate cement, water, reinforcing fibers, phase change energy storage capsules, embedded antibacterial agents and process aids are added and stirred to make slurry, which is then injected into a mold and biodegradable channel templates are arranged during the spreading process. After pressure molding, a wet slab is obtained. Core material curing and channel formation: The wet slab is steam-cured, and the curing process includes a constant temperature curing stage of 180±5℃. After curing, the substrate is dried and sanded. Surface functionalization treatment: Prepare a self-healing antibacterial coating, apply the coating to the substrate surface after plasma treatment and cure it to form the self-healing smart coating.

[0015] Furthermore, the pressure applied during the pressure molding process is 2.5-3.5 MPa, and the holding time is 10-15 min. The autoclaving process includes the following steps: The temperature is raised to 180±5℃ at a constant rate within 1.5-2 hours, and then kept at a constant temperature for 8-12 hours. After that, the pressure and temperature are lowered to below 60℃ at a constant rate within 2-3 hours.

[0016] Furthermore, the preparation method of the self-healing antibacterial coating includes the following steps: Phosphate ester-siloxane prepolymers were prepared by reacting (3-aminopropyl)triethoxysilane with phosphite compounds in an alcohol-water solvent at a molar ratio of 1:1 to 1:1.2. The composite antibacterial agent is added and ultrasonically dispersed evenly. After pH adjustment to 5-6 and aging, it is prepared. The curing conditions are 80-110℃ for 30-60 min.

[0017] Furthermore, the preparation method of the composite antibacterial agent includes the following steps: Sodium selenite solution and copper salt solution were slowly added dropwise to a buffer solution containing nano-sized oyster shell powder under a protective atmosphere. After reacting at 60-80℃ for 2-4 hours, the product was centrifuged, washed, and freeze-dried sequentially.

[0018] Beneficial effects: The intelligent coating on the surface of this invention combines a dynamic covalent network with a photothermal antibacterial unit, enabling the surface of the board to self-repair when slightly damaged, and to activate strong antibacterial properties under light, thus solving the problem of easy failure of traditional functional coatings. The phase change energy storage capsules uniformly dispersed within the core material of this invention effectively mitigate indoor temperature fluctuations, enhance building thermal inertia, and reduce air conditioning energy consumption through latent heat absorption and release within the phase change temperature range. The intact silica wall material of the microcapsules effectively prevents PCM leakage in alkaline environments. This invention utilizes rice husk ash, oyster shells, and waste paper to replace traditional raw materials, achieving the resource utilization of biomass solid waste. The refined treatment of waste paper fibers and the optimization of their interface with the biomass cementitious matrix improve the toughness of the board while avoiding a decrease in water resistance. This invention not only reduces the weight of the board material through its internal network-like microchannel structure, but also constitutes a breathing system. It increases the contact area between the functional core material and the environment, promotes the diffusion and release of antibacterial and negative ions, and enhances the temperature regulation effect through air convection, transforming the board material from a passive material into a living material that can actively regulate the microenvironment. Detailed Implementation

[0019] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0020] This invention provides a self-healing, temperature-regulating, and antibacterial paper-based fiber-reinforced calcium silicate board, a multi-layered composite functional material comprising: Biomass-based composite core layer: This layer is the main load-bearing and temperature-regulating component of the board, and includes the following materials by weight percentage: Cementitious matrix raw materials: 50-70%, composed of calcareous raw materials, siliceous raw materials and silicate cement, wherein the molar ratio of calcareous raw materials to siliceous raw materials is controlled between 0.7 and 0.9; Preferably, the calcareous raw material is calcined and ground waste oyster shell powder with a particle size D50≤45μm, and the siliceous raw material is rice husk ash with a particle size D50≤20μm.

[0021] Reinforcing fiber: 10-20%, which is waste paper pulp fiber after deinking and descaling treatment, and its freeness is controlled at 35-45°SR.

[0022] Phase change energy storage unit: 5-12%, which is a phase change energy storage capsule with paraffin as the core and silica as the wall material. Its phase change temperature range is 22-28℃, the capsule particle size is 5-30μm, and the encapsulation rate is ≥85%.

[0023] Embedded antibacterial agent: 1-4%, which is a CuSe / CaCO3 composite photothermal antibacterial agent formed by nano-copper selenide loaded on modified oyster shell powder.

[0024] Processing aids: 0.5-2%, including hydroxypropyl methylcellulose for improving slurry rheology and polycarboxylate superplasticizers for promoting hydration.

[0025] Network-like microchannel structure: This refers to three-dimensional interconnected network-like pore channels pre-placed within the biomass-based composite core material layer. The channel diameter is 0.5-2 mm, and the porosity accounts for 3-8% of the total volume of the core material. The inner wall of this channel can be further loaded with air purification materials such as tourmaline powder and nano-titanium dioxide.

[0026] Self-healing smart coating: Compositely applied to at least one major surface of the core material layer, with a thickness of 50-200μm, and formed by cross-linking and curing of the following components: Film-forming matrix: 85-95%, which is a phosphate ester-protonated siloxane hybrid polymer network based on dynamic imine bonds and phosphate ester bonds.

[0027] Functional filler: 5-15%, which is the above-mentioned CuSe / CaCO3 composite photothermal antibacterial agent.

[0028] Furthermore, this embodiment of the invention also provides a method for preparing the calcium silicate board, comprising the following steps: Step 1: Raw material pretreatment Washed rice husks are calcined at 600-700℃ in an oxygen-deficient environment for 2-3 hours, then ground and sieved to obtain rice husk ash powder with high activity and amorphous SiO2 content ≥90%.

[0029] The washed oyster shells are calcined at 900-950℃ for 3-4 hours, digested, dried, and ground to obtain oyster shell powder with high purity Ca(OH)2 or CaO content ≥95%.

[0030] Waste paper is pulped by hydraulic pulping and deinked by flotation. The pH is adjusted to neutral and then the pulp is broken down to a specified degree of beating in a disc mill to obtain a pulp fiber suspension with a solid content controlled at 3-5%.

[0031] Phase change energy storage capsules were prepared by the sol-gel method: emulsified paraffin core material was mixed with an alcoholic solution of tetraethyl orthosilicate, and reacted at 50-60°C for 4-6 hours in the presence of ammonia as a catalyst. After washing and drying, a white powder product was obtained.

[0032] A composite antibacterial agent was prepared by chemical deposition: sodium selenite solution and copper salt solution were slowly added dropwise to a buffer solution containing nano-sized oyster shell powder under a protective atmosphere, and reacted at 60-80℃ for 2-4 hours. The product was centrifuged, washed, and freeze-dried to obtain CuSe / CaCO3 composite powder.

[0033] Step 2: Core Material Slurry Preparation and Molding Mix oyster shell powder, rice husk ash, and silicate cement in the designed proportions for 1-2 minutes until homogeneous.

[0034] Add the calculated amounts of water, pulp fiber suspension, phase change energy storage capsules, composite antibacterial agent and process aids to the dry mixture, and stir in a high-speed mixer at a speed of 800-1200 r / min for 5-8 minutes to form a uniform fiber slurry.

[0035] The slurry is injected into the mold of the board-making machine, which is lined with a filter screen and a base cloth. During the slurry spreading process, water-soluble or thermally degradable polymer fiber bundles (such as polyvinyl alcohol fibers) are simultaneously arranged according to a preset pattern as channel templates.

[0036] After initial dehydration by the slurry method, the slab is pressurized at 2.5-3.5 MPa and held for 10-15 minutes to form a wet slab.

[0037] Step 3: Core Material Curing and Channel Formation The wet slab, along with the mold, is fed into an autoclave, employing a stepped heating and constant-temperature curing regime: the temperature is uniformly increased to 180±5℃ over 1.5-2 hours, and then maintained at a constant temperature for 8-12 hours. Subsequently, the pressure and temperature are uniformly reduced to below 60℃ over 2-3 hours before removal from the autoclave. This high-temperature, high-pressure environment allows the cementitious material to undergo a complete hydrothermal synthesis reaction of the tobermorite phase, while simultaneously causing the polymer fiber bundles, which serve as channel templates, to completely degrade or dissolve, thereby forming a network of microchannels within the slab. After removal from the autoclave, the slab is dried and sanded to a fixed thickness to obtain the substrate.

[0038] Step 4: Surface functionalization treatment Preparation of self-healing antibacterial coating: (3-aminopropyl)triethoxysilane and a phosphite compound with a specific structure were reacted in an alcohol-water solvent at a molar ratio of 1:1-1:1.2 to prepare a phosphate ester-siloxane prepolymer. The prepolymer was then ultrasonically dispersed with 5-15% (by mass) of a CuSe / CaCO3 composite antibacterial agent, and the pH was adjusted to 5-6 with dilute acid and allowed to mature for 24 hours.

[0039] The substrate surface is subjected to plasma treatment with a power of 300-500W for 30-60 seconds to increase the surface energy.

[0040] The above coating is uniformly applied to the surface of the treated substrate using a precision roller coater, with the wet film thickness controlled between 100-250 μm.

[0041] The coated board is placed in an oven at 80-110℃ and cured for 30-60 minutes to form a cross-linked smart coating.

[0042] The following are the pretreatment methods for the common raw materials used in the various embodiments and comparative examples: 1. Preparation of rice husk ash powder Raw material: Washed and dried rice husks.

[0043] Equipment: Programmable muffle furnace, planetary ball mill, 500 mesh standard sieve.

[0044] Process: Place the rice husks in a crucible and put it into a muffle furnace.

[0045] The temperature was increased to 650℃ at a rate of 5℃ / min.

[0046] Calcination was carried out at 650℃ for 2.5 hours under oxygen-limited conditions (with the damper closed).

[0047] The rice husk ash was removed after being cooled to below 100°C in the furnace, yielding black carbonized rice husk ash.

[0048] The coarse ash was placed in a ball mill jar, and zirconia balls were used as the grinding medium at a ball-to-material ratio of 10:1. The mill was then wet-milled at a speed of 350 r / min for 4 hours.

[0049] After the slurry is dried, it is passed through a 500-mesh sieve to obtain rice husk ash powder with a particle size D50≈18μm and an active SiO2 content ≥92%, which is then sealed and stored.

[0050] 2. Preparation of oyster shell powder Ingredients: Oyster shells that have been washed and dried after consumption.

[0051] Equipment: Jaw crusher, box-type high-temperature furnace, digester, centrifugal spray dryer, air jet mill.

[0052] Process: Use a crusher to initially crush the oyster shells into particles smaller than 5mm.

[0053] Placed in a high-temperature furnace, the temperature is increased to 920℃ at 8℃ / min and held for 3.5h to completely decompose into calcium oxide (CaO).

[0054] The calcined material was put into a digestion tank, and hot water at 60°C was added at a water-to-ash mass ratio of 3:1. The mixture was vigorously stirred and digested for 45 minutes to produce calcium hydroxide (Ca(OH)2) slurry.

[0055] After impurities are removed by a 200-mesh vibrating screen, the slurry is sent to a centrifugal spray drying tower (inlet temperature 220℃, outlet temperature 90℃) to produce coarse powder.

[0056] The coarse powder was classified by an air jet mill to obtain oyster shell powder with a particle size of D50≈40μm and Ca(OH)2 purity ≥96%, and then sealed to prevent moisture.

[0057] 3. Pretreatment of waste paper pulp fibers Raw material: Mixed waste office paper (excluding plastic coating).

[0058] Equipment: Hydraulic pulper, flotation deinking machine, horizontal spiral dewatering machine, PFI refiner, concentration meter.

[0059] Process: Pulping: Pulping at a concentration of 4% in warm water at 45℃ for 20 minutes.

[0060] Deinking: Add 1.5% (for oven-dry pulp) of a composite deinking agent (containing NaOH, Na2SiO3, H2O2 and surfactant), and deink in a flotation machine for 25 minutes until the pulp whiteness no longer increases significantly.

[0061] Washing: Wash with water until pH is neutral, then concentrate to a concentration of 10%.

[0062] Disintegration and beating: The pulp is processed in a PFI refiner, and the beating degree is precisely adjusted to 36°SR by controlling the blade distance and rotation speed.

[0063] Storage: Dilute to a suspension with a solid content of 4.0% and keep ready for use (use within 24 hours).

[0064] 4. Preparation of paraffin@silica phase change energy storage capsules Raw materials: n-octadecane (phase transition point ~28℃), tetraethyl orthosilicate (TEOS), anhydrous ethanol, ammonia (28%), sodium dodecyl sulfate (SDS).

[0065] Equipment: High-shear emulsifier, four-necked flask, constant temperature water bath magnetic stirrer, vacuum filtration device, freeze dryer.

[0066] Process: Emulsion preparation: Dissolve 10g of n-octadecane and 1g of SDS in 200g of deionized water, and emulsify at 10000rpm for 10min using a high-shear emulsifier to form a stable emulsion.

[0067] Sol hydrolysis: In another container, dissolve 20g of TEOS in 100g of anhydrous ethanol, and slowly add 10g of an aqueous solution containing 2% ammonia while stirring. Pre-hydrolyze for 30min.

[0068] Coating reaction: The pre-hydrolyzed TEOS sol was slowly added dropwise to the vigorously stirred emulsion. The mixture was placed in a 55°C water bath and stirred at 400 rpm for 5 hours.

[0069] Post-processing: After the reaction was complete, the product was filtered and washed three times alternately with ethanol and water. The product was then freeze-dried at -50°C for 24 hours.

[0070] Product obtained: White, free-flowing powdery phase change energy storage capsules. The average particle size was measured to be 15±10μm by laser particle size analyzer, the encapsulation efficiency was ≥88% by DSC test, and the phase change enthalpy was ≥180J / g.

[0071] 5. Preparation of CuSe / CaCO3 composite photothermal antibacterial agent Raw materials: nano-sized oyster shell powder (CaCO3) prepared above, copper sulfate pentahydrate (CuSO4·5H2O), sodium selenite (Na2SeO3), ascorbic acid (VC), and polyvinylpyrrolidone (PVPK30).

[0072] Equipment: Three-necked flask, constant pressure dropping funnel, circulating water vacuum pump, vacuum drying oven.

[0073] Process: Dispersion: Disperse 5g of nano-sized oyster shell powder in 200ml of deionized water, add 0.5g of PVP, and sonicate for 30min.

[0074] Preparation of solutions: Solution A: Dissolve 2.5g of CuSO4·5H2O in 50ml of water; Solution B: Dissolve 1.73g of Na2SeO3 and 3.52g of VC in 50ml of water (prepare fresh before use).

[0075] Reaction: The oyster shell dispersion was placed in a 70°C water bath under nitrogen protection. Simultaneously, solutions A and B were added dropwise through two dropping funnels at a rate of approximately 1 drop / second for 3 hours. The solution gradually changed from blue to brownish-black.

[0076] Post-treatment: After the addition is complete, continue to keep warm and mature for 1 hour. After natural cooling, centrifuge and wash three times each with ethanol and deionized water.

[0077] Drying: The filter cake was placed in a vacuum drying oven at 60℃ and dried for 12 hours. After grinding, a gray-black composite antibacterial powder was obtained.

[0078] Example 1 Core material preparation and mixing: Weigh the following by dry basis: 32g oyster shell powder, 32g rice husk ash powder, 16g 42.5 grade ordinary silicate cement (total cementitious matrix 80g), 12g waste paper pulp fiber (octane dry), 6g phase change energy storage capsule, 1.5g composite antibacterial agent, 0.4g hydroxypropyl methylcellulose, and 0.1g polycarboxylate superplasticizer.

[0079] First, dry mix the three gel matrix raw materials in a mixer for 2 minutes.

[0080] In a planetary mixing vessel, first add 160g of water (water-to-solid ratio ≈ 1.6), then add pulp fiber suspension (containing 12g of oven-dry fiber, totaling 300g of suspension), and mix at a low speed of 200rpm.

[0081] Add the dry-mixed gelling agent, phase change energy storage capsule, composite antibacterial agent, and process aids in sequence. Increase the rotation speed to 1000 rpm and stir for 7 minutes to obtain a uniform fiber slurry.

[0082] Shaping and Channel Construction: The bottom of the mold (200mm×200mm) is covered with an 80-mesh filter screen and a polyester base cloth.

[0083] The slurry is injected evenly. At the same time, using a special layup tool, water-soluble polyvinyl alcohol (PVA) fiber bundles with a diameter of 1 mm are laid in a grid pattern with a spacing of 15 mm in the middle of the slurry.

[0084] The material is initially dehydrated using vacuum filtration, then transferred to a press and held at 3.0 MPa for 12 minutes to form a wet slab. The thickness of the wet slab is 10 mm.

[0085] Steam pressure curing: The wet slab, along with the mold, is fed into the autoclave.

[0086] Curing schedule: 1.5h uniformly heat up to 180℃ (saturated vapor pressure 1.0MPa) → constant temperature curing at 180℃ for 10h → 2.5h uniformly depressurize and cool down to <60℃ → remove from the reactor.

[0087] During the maintenance process, the PVA fiber bundles completely dissolve, forming a mesh-like biomimetic microchannel.

[0088] Post-treatment and coating: The slabs are dried in an oven at 105℃ to constant weight, and then sanded on both sides to a thickness of 8.0±0.1mm to obtain the substrate.

[0089] Coating preparation: 10g of (3-aminopropyl)triethoxysilane and 12.4g of a cyclic phosphite with a specific structure (molar ratio 1:1.1) were dissolved in 50g of a mixed solvent of ethanol / water (volume ratio 4:1) and reacted at 60℃ for 6h to obtain a phosphate ester-siloxane prepolymer (solid content 30%).

[0090] Take 100g of the prepolymer, add 8g of CuSe / CaCO3 composite antibacterial agent, ultrasonically disperse for 30min, adjust the pH to 5.5 with 0.1M HCl, and mature for 24h to obtain the coating.

[0091] The substrate surface was treated with 400W air plasma for 45 seconds.

[0092] The coating was applied to one side of the substrate using a wire bar coater, with a wet film thickness of 150 μm.

[0093] The coating is cured in a 95℃ forced-air oven for 45 minutes to form a self-healing intelligent coating. The final thickness of the finished board is 8.15mm.

[0094] Example 2 The difference from Example 1 is as follows: During the preparation process, the beating degree of waste paper pulp fiber was adjusted to 40°SR, the amount of waste paper pulp fiber was increased to 18g, and the amount of phase change energy storage capsule was reduced to 4g.

[0095] During mixing, the water-to-solid ratio is increased to 1.7 to ensure the fluidity of the slurry with high fiber content.

[0096] The pressure during molding was finely adjusted to 3.2 MPa to compensate for the springiness caused by the high fiber content.

[0097] Example 3 The difference from Example 1 is as follows: The phase change energy storage capsule has a phase change temperature of 24℃, and the amount of phase change energy storage capsule used has been increased to 11g.

[0098] During mixing, the stirring speed was reduced to 800 rpm and the time was shortened to 5 minutes to reduce mechanical shear damage to the microcapsule wall material.

[0099] The constant temperature time for autoclaving was shortened to 8 hours. This reduced the damage to high-content microcapsules caused by high temperatures, thus further protecting the microcapsule structure.

[0100] Example 4 The difference from Example 1 is as follows: The amount of composite antibacterial agent in the core material has been increased to 3.5g.

[0101] In coatings, the amount of composite antibacterial agent added is increased to 12g (accounting for 12% of the prepolymer mass).

[0102] To ensure the leveling properties of high-solids content coatings, the curing process is divided into two steps: pre-curing at 80℃ for 15 minutes, followed by full curing at 100℃ for 30 minutes.

[0103] Example 5 The difference from Example 1 is as follows: Optimized autoclaving process: 1 hour to 120℃ (air venting) → 1 hour to 180℃ → 12 hours of constant temperature curing at 180℃ → 3 hours of uniform cooling and depressurization.

[0104] Channel functionalization: A layer of hydroxypropyl cellulose aqueous solution containing 1 wt% nano TiO2 (P25) is pre-coated onto the surface of PVA fiber bundles and used after drying. After curing and dissolution, TiO2 adheres to the inner wall of the channel.

[0105] The coating is cured at 105°C to promote a stronger bond between the coating and the substrate.

[0106] Example 6 The difference from Example 1 is as follows: The amount of oyster shell powder was reduced to 30g, and the amount of rice husk ash powder was increased to 34g (keeping the total amount of the gel matrix at 80g), so that the Ca / Si molar ratio was precisely 0.75.

[0107] Example 7 The difference from Example 1 is as follows: The amount of oyster shell powder was increased to 34g, and the amount of rice husk ash powder was reduced to 30g (total cementitious matrix 80g), so that the Ca / Si molar ratio was precisely 0.90.

[0108] Example 8 The difference from Example 1 is as follows: When preparing phase change energy storage capsules, increasing the amount of TEOS by 40% while keeping other processes unchanged resulted in microcapsules with thicker walls and higher mechanical strength, with an average particle size of 22 μm.

[0109] During mixing, the stirring speed was reduced to 600 rpm and the time was shortened to 5 minutes to reduce mechanical shear damage to the microcapsule wall material.

[0110] Example 9 The difference from Example 1 is as follows: The conditions for coating curing are: place it in a 110℃ forced-air oven for 30 minutes to cure, forming a self-healing intelligent coating.

[0111] Example 10 The difference from Example 1 is as follows: The conditions for coating curing are: place it in an 80℃ forced-air oven for 60 minutes to cure, forming a self-healing intelligent coating.

[0112] Comparative Example 1 The difference from Example 1 is as follows: The surface coating was replaced with a regular acrylic emulsion coating.

[0113] Coating: Take 20g of styrene-acrylic emulsion with a solid content of 50%, add an equal amount of CuSe / CaCO3 composite antibacterial agent as in Example 1, and 0.5g of wetting agent, and stir evenly.

[0114] Coating and curing: Apply using the same method and cure at 80℃ for 30 minutes to form a film.

[0115] Comparative Example 2 The difference from Example 1 is as follows: Siliceous raw materials: Use 200-mesh quartz sand of equal mass instead of rice husk ash.

[0116] Calcium raw material: Use an equal mass of analytical grade calcium hydroxide instead of oyster shell powder.

[0117] Reinforcing fibers: Alkali-free chopped glass fibers of equal mass with a length of 6 mm and a diameter of 13 μm are used to replace waste paper pulp fibers.

[0118] Phase change-free energy storage capsule.

[0119] It does not have a pre-set PVA template and does not feature a network-like biomimetic microchannel design.

[0120] Process adjustments: When mixing the slurry, since glass fibers are prone to agglomeration, first dry mix them with dry binder for 1 minute, then add water for wet mixing.

[0121] It is formed by sheet forming rather than by flow pressing, in order to simulate the traditional process.

[0122] The autoclaving process is the same as the industry standard (185℃, 12h).

[0123] Comparative Example 3 The only difference from Example 1 is: No biodegradable template fibers are used in the molding process. After all the slurry is poured into the mold, the surface is leveled only by vibration, and then directly subjected to vacuum filtration and 3.0 MPa pressure molding. The resulting board has a uniform and dense internal structure, without an ordered network of biomimetic microchannels.

[0124] All preparation processes were conducted under standard experimental conditions of 23±2℃ and 50±5% relative humidity to ensure the repeatability and comparability of the results. At least three samples were prepared in parallel for each example and comparative example for performance testing, and the average value was taken.

[0125] The above Examples 1-10 and Comparative Examples 1-3 were tested respectively, and the testing standards and methods are as follows: Self-healing efficiency testing: Refer to ASTM D7027.

[0126] Instrument: Laser confocal microscope (CLSM).

[0127] Method: A 20 μm wide and 30 μm deep scratch was created using a diamond scratch instrument. The sample was placed in a 60℃ oven for 2 hours. After repair, the cross-sectional area of ​​the scratch at the same location was measured using a CLSM, and the repair rate was calculated.

[0128] Phase transition enthalpy (∆H): ISO 11357-3.

[0129] Instrument: Differential scanning calorimeter (DSC).

[0130] Method: Take 5-10 mg of core material powder and perform heating / cooling scans (10-50°C) at a rate of 5°C / min under a nitrogen atmosphere. Record the integrated enthalpy of the melting peak.

[0131] Phase transition cycle stability: Instruments: Hot and cold cycle chamber, DSC.

[0132] Method: The sample was alternately immersed in water baths at 22°C and 28°C for 100 rapid thermal cycles. After each cycle, ΔH was measured again using DSC, and the retention rate was calculated.

[0133] Antibacterial properties: GB / T21866-2008.

[0134] Instruments: sterile operating table, constant temperature incubator.

[0135] Bacterial strains: Staphylococcus aureus (ATCC6538), Escherichia coli (ATCC25922).

[0136] Method: Film application method. Bacterial culture was inoculated onto the sample surface, covered with a thin film, and incubated for 24 hours. The culture was then washed, counted, and the antibacterial rate was calculated.

[0137] Flexural strength: JC / T564.1-2018.

[0138] Instrument: Universal testing machine.

[0139] Method: Cut the board into standard size of 250mm×250mm, use the three-point bending method with a span of 200mm, apply uniform load until fracture, and record the maximum load.

[0140] Water absorption rate: JC / T564.1-2018.

[0141] Instruments: Electronic balance, constant temperature water bath.

[0142] Method: The sample was dried and weighed (M0), then immersed in water at 23±2°C for 24 hours. After removing the sample and wiping off the surface water droplets, it was weighed immediately (M1). Water absorption rate = [(M1-M0) / M0]×100%.

[0143] Moisture expansion rate: JC / T564.1-2018.

[0144] Instruments: length comparator, constant temperature water bath.

[0145] Method: Measure the change in length of the sample before and after immersion in water for 24 hours, and calculate the percentage.

[0146] Apparent density: JC / T564.1-2018.

[0147] Instruments: Electronic balance, calipers.

[0148] Method: Measure the dried mass and volume of the sample, and calculate the density.

[0149] The test results are shown in Table 1 below: Table 1

[0150] In Table 1 above, 1-10 correspond to Examples 1-10, C1-C3 correspond to Comparative Examples 1-3, E1 is the self-healing efficiency (%); E2 is the phase change enthalpy ΔH (J / g); E3 is the phase change enthalpy retention rate (after 100 cycles, %); E4 is the antibacterial rate - Staphylococcus aureus (%); E5 is the antibacterial rate - Escherichia coli (%); E6 is the flexural strength (MPa); E7 is the water absorption rate (%); E8 is the swelling rate (%); E9 is the apparent density (g / cm³). 3 In Table 1, C1 corresponds to E4 and E5, where "initial" indicates before wear and "wear" indicates after wear.

[0151] In summary, as shown in Table 1: The self-healing efficiency of all embodiments was above 88%, with Example 9 reaching 95%, indicating that the higher curing temperature promoted the formation of a dynamic covalent network. The antibacterial performance was superior to 99% (Example 4 reached >99.9%), demonstrating the effectiveness of the combination of the CuSe / CaCO3 composite antibacterial agent and the self-healing coating.

[0152] Comparative Example 1 used a standard coating, with a self-healing efficiency of 0. Its antibacterial rate plummeted to around 70% after wear, a stark contrast to the examples. This strongly demonstrates that self-healing is indispensable for maintaining long-term surface antibacterial properties. Its water absorption rate (45%) was significantly higher than all examples, further indicating that the self-healing coating provides excellent sealing and protection to the substrate.

[0153] Comparative Example 3 used the same raw materials, proportions, and coating as Example 1, except for the lack of the network-like biomimetic microchannels. Its antibacterial rate plummeted to approximately 85%. This demonstrates that in a dense matrix, antibacterial ions struggle to effectively migrate to the surface. The microchannel structure of this invention provides a high-speed pathway for functional components, representing a core structural innovation for achieving efficient and active antibacterial action.

[0154] Example 3, by increasing the content of phase change energy storage capsules, achieved a ΔH of 28.3 J / g, demonstrating excellent thermal storage potential. Example 8, by thickening the wall material, achieved a phase change enthalpy retention rate of up to 99% after 100 cycles, proving that process optimization can greatly improve the durability of temperature regulation functions.

[0155] The ΔH of Comparative Example 2 is 0, which means it has no temperature regulation function at all, highlighting the creative progress of this invention in improving the thermal comfort of buildings.

[0156] Example 2 increased the flexural strength to 13.5 MPa by increasing the fiber content, but the water absorption rate increased slightly (30%), demonstrating a balance between performance. Example 7 (high calcium-to-silicon ratio) had a strength (11.8 MPa) that was better than Example 6 (10.0 MPa), but a higher rate of moisture expansion (0.15%), indicating that a Ca / Si ratio of around 0.8 (as in Example 1) is the optimal range for overall performance.

[0157] Comparative Example 2 showed the best flexural strength (14.0 MPa) and water absorption (18%), but its density was as high as 1.25 g / cm³ because glass fiber has a higher density than waste paper pulp fiber. 3 Furthermore, the raw materials are non-renewable. While maintaining acceptable mechanical properties (all >9.8 MPa, far exceeding standards), the embodiments of this invention significantly reduce density (0.90-0.97 g / cm³). 3 This makes construction and transportation easier and enables the high-value utilization of solid waste.

[0158] All embodiments with microchannels exhibited significantly lower swelling rates than Comparative Example 3 (0.20%) without microchannels. This is because the ordered microchannels can uniformly distribute stress during water absorption, preventing localized deformation and improving dimensional stability.

[0159] The data from Examples 1-10 fully demonstrate that, within the parameter range of the claims of this invention, multifunctional boards with high self-healing efficiency (>88%), significant phase change enthalpy (>14J / g), strong antibacterial effect (>99%), qualified mechanical strength (>9.8MPa), and good physical properties can be stably prepared.

[0160] The three comparative examples, from the perspectives of functional longevity, functional integration, and functional effectiveness, highlight the necessity and remarkable effects of the three core innovations of this invention: the self-healing coating, the biomass / phase change material composite, and the network-like microchannel structure. These innovations are not simply superimposed, but rather produce a synergistic enhancement.

[0161] Data shows that by adjusting the formula and process (such as in Examples 2, 3, and 4), the product performance can be customized for different application scenarios such as high toughness, high heat storage, and strong antibacterial properties, and it has good industrial adaptability and market application value.

[0162] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board, characterized in that, include: The biomass-based composite core material layer and the self-healing intelligent coating, wherein the biomass-based composite core material layer has a three-dimensional interconnected network-like microchannel structure inside; The biomass-based composite core layer comprises the following materials by mass percentage: The composition includes 50-70% cementitious matrix raw materials, 10-20% reinforcing fibers, 5-12% phase change energy storage units, 1-4% embedded antibacterial agents, and 0.5-2% process aids. The cementitious matrix raw materials include calcareous raw materials, siliceous raw materials, and silicate cement. The molar ratio of the calcium-based raw material to the silicon-based raw material is 0.7-0.9; The reinforcing fiber is waste paper pulp fiber that has undergone deinking and descaling treatment; The self-healing smart coating is formed by cross-linking and curing a film-forming matrix and a functional filler. The film-forming matrix is ​​a hybrid polymer network of phosphate ester and protonated siloxane based on dynamic imine bonds and phosphate ester bonds.

2. The self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board according to claim 1, characterized in that, The thickness of the self-healing smart coating is 50-200μm; the functional filler is a composite antibacterial agent formed by loading nano-copper selenide onto modified oyster shell powder, and the functional filler accounts for 5-15% of the total mass of the self-healing smart coating.

3. The self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board according to claim 1, characterized in that, The calcium-based raw material is calcined and ground waste oyster shell powder with a particle size D50≤45μm; The siliceous raw material is rice husk ash with a particle size D50≤20μm, and the content of highly active amorphous silica in the siliceous raw material is ≥90%.

4. The self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board according to claim 1, characterized in that, The phase change energy storage unit is a phase change energy storage capsule with paraffin as the core and silica as the wall material. Its phase change temperature range is 22-28℃, the capsule particle size is 5-30μm, and the encapsulation rate is ≥85%.

5. The self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board according to claim 1, characterized in that, The network-like microchannel structure is a network of porous channels formed in the core material layer by a biodegradable template method. The channel diameter is 0.5-2 mm, and the porosity accounts for 3-8% of the total volume of the core material layer. The inner wall of the network-like porous channels is loaded with tourmaline powder or nano-titanium dioxide air purification material.

6. The self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board according to claim 1, characterized in that, The embedded antibacterial agent is a composite antibacterial agent formed by loading nano-copper selenide onto modified oyster shell powder; the beating degree of the waste paper pulp fiber is controlled at 35-45°SR.

7. A method for preparing a self-healing, temperature-regulating, antibacterial paper-based fiber-reinforced calcium silicate board as described in any one of claims 1-6, characterized in that, Includes the following steps: Raw material pretreatment: Prepare siliceous raw materials, calcium-based raw materials, reinforcing fibers, phase change energy storage capsules, and embedded antibacterial agents respectively; Core material slurry preparation and molding: Calcium raw materials, siliceous raw materials, silicate cement, water, reinforcing fibers, phase change energy storage capsules, embedded antibacterial agents and process aids are added and stirred to make slurry, which is then injected into a mold and biodegradable channel templates are arranged during the spreading process. After pressure molding, a wet slab is obtained. Core material curing and channel formation: The wet slab is steam-cured, and the curing process includes a constant temperature curing stage of 180±5℃. After curing, the substrate is dried and sanded. Surface functionalization treatment: Prepare a self-healing antibacterial coating, apply the coating to the substrate surface after plasma treatment and cure it to form the self-healing smart coating.

8. The preparation method according to claim 7, characterized in that, The pressure applied during the pressure molding process is 2.5-3.5 MPa, and the holding time is 10-15 min. The autoclaving process includes the following steps: The temperature is raised to 180±5℃ at a constant rate within 1.5-2 hours, and then kept at a constant temperature for 8-12 hours. After that, the pressure and temperature are lowered to below 60℃ at a constant rate within 2-3 hours.

9. The preparation method according to claim 7, characterized in that, The preparation method of the self-healing antibacterial coating includes the following steps: Phosphate ester-siloxane prepolymers were prepared by reacting (3-aminopropyl)triethoxysilane with phosphite compounds in an alcohol-water solvent at a molar ratio of 1:1 to 1:1.

2. The composite antibacterial agent is added and ultrasonically dispersed evenly. After pH adjustment to 5-6 and aging, it is prepared. The curing conditions are 80-110℃ for 30-60 min.

10. The preparation method according to claim 7, characterized in that, The preparation method of the composite antibacterial agent includes the following steps: Sodium selenite solution and copper salt solution were slowly added dropwise to a buffer solution containing nano-sized oyster shell powder under a protective atmosphere. After reacting at 60-80℃ for 2-4 hours, the product was centrifuged, washed, and freeze-dried sequentially.

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