A composite foam material containing biologically active crystals and a method for making the same

Abstract

This invention discloses a composite foam material containing bioactive crystals and its preparation method, relating to the field of polyurethane foam material technology. The method includes: using a porous mineral loaded with heat-sensitive, easily decomposable gas-producing substances as a core, and coating it with hydrophilic polymer nanomaterials to obtain a breathable filler; in-situ polymerization of a conductive polymer layer on the surface of a two-dimensional carbon substrate, followed by discontinuous coating with polar polymers to obtain antistatic particles with exposed conductive polymer on the surface; mixing polyol, bioactive crystal powder, the above-mentioned breathable filler, antistatic particles, and additives, and then foaming and curing with isocyanate. This invention enables the foam to possess high air and moisture permeability, antistatic properties, and bioactivity, with the filler firmly bonded to the matrix.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam materials technology, specifically to a composite foam material containing bioactive crystals and its preparation method. Background Technology

[0002] Polyurethane foam, with its lightweight, good elasticity, and excellent cushioning properties, is widely used in areas where it comes into close contact with the human body for extended periods, such as automotive seats, home bedding, and medical care. As consumers' demands for product comfort and functionality continue to rise, traditional single-mechanical cushioning materials are no longer sufficient to meet market needs. Consumers expect foam materials to provide good elastic support while also possessing excellent breathability and moisture-wicking properties to eliminate stuffiness, durable antistatic properties to prevent electric shock discomfort and dust adsorption, and environmental regulation functions such as far-infrared radiation and negative ion release through the incorporation of natural bioactive crystal powders. Traditional polyurethane foam has inherent limitations in achieving these multi-dimensional functions synergistically. On the one hand, its cell structure is mostly closed-cell or semi-open-cell, making effective convection of air and moisture difficult, leading to increased surface temperature and humidity. On the other hand, polyurethane is a typical polymeric insulating material, highly susceptible to static electricity buildup due to friction. The conventional approach is to directly and physically blend porous mineral fillers and conductive fillers into the foaming system. However, due to the differences in surface energy of various fillers and their poor interfacial compatibility in the matrix, not only is sedimentation and agglomeration very likely to occur, but high filler content will also seriously deteriorate the mechanical properties of the foam, making it difficult to achieve multiple functions in actual production. Summary of the Invention

[0003] The purpose of this invention is to provide a composite foam material containing bioactive crystals and its preparation method, so as to solve the technical problems mentioned in the background.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. A porous mineral material loaded with substances that are easily decomposed by heat and produce gas is used as the core and coated with a hydrophilic polymer nanomaterial to prepare a breathable filler with a core-shell structure. S2. A conductive polymer layer is polymerized in situ on the surface of a two-dimensional carbon substrate, and then a discontinuous coating of polar polymer is applied to its outermost layer to obtain antistatic particles with some conductive polymer exposed on the surface. S3. Polyurethane foam polyol, bioactive crystal powder, the air-permeable filler, the antistatic particles, foaming agent and catalyst are mixed evenly, and isocyanate is added for foaming and curing; during the exothermic foaming process, the gas-generating substances in the core of the air-permeable filler are decomposed by heat to form secondary microporous channels.

[0005] Preferably, the porous mineral material in step S1 is activated diatomaceous earth with surface passivation modification by a silane coupling agent, the gas-producing substance that is easily decomposed by heat is ammonium bicarbonate, and the hydrophilic polymer nanomaterial is nanocellulose grafted with epoxy silane.

[0006] Preferably, the method for preparing the permeable filler with the core-shell structure is as follows: Diatomaceous earth was acid-washed and activated, and then synergistically modified with methyltrimethoxysilane and n-octyltriethoxysilane to obtain surface-passivated diatomaceous earth. The surface passivated diatomaceous earth is impregnated in an ammonium bicarbonate solution, then vacuum impregnated and dried under the condition of containing a wetting agent, so that the ammonium bicarbonate is loaded into the pores of the diatomaceous earth to obtain ammonium-loaded diatomaceous earth. Modified nanocellulose was obtained by reacting nanocellulose with γ-glycidoxypropyltrimethoxysilane. The ammonium-loaded diatomaceous earth and the modified nanocellulose were mixed in a certain mass ratio, and then ultrasonically dispersed and dried under reduced pressure in a solvent to obtain the air-permeable filler.

[0007] Preferably, the acid washing activation involves adding diatomaceous earth to a hydrochloric acid solution with a mass concentration of 10-15% and stirring at 60-70°C for 2-3 hours; then, during surface modification, the activated diatomaceous earth is dispersed in an ethanol-water mixed solvent, methyltrimethoxysilane and n-octyltriethoxysilane are added, the pH is adjusted to 4-5 with acetic acid, and the reaction is stirred at 50-60°C for 2-3 hours. The mass ratio of the activated diatomaceous earth to methyltrimethoxysilane is 1:(0.1-0.2); The mass ratio of the activated diatomaceous earth to n-octyltriethoxysilane is 1:(0.03-0.08); The ammonium-loaded diatomaceous earth and modified nanocellulose were mixed in a mass ratio of 6:(0.5-0.8). The mixture was first ultrasonically dispersed in anhydrous ethanol at atmospheric pressure for 30-45 min, and then the solvent was removed by vacuum evaporation under a vacuum of -0.06 to -0.08 MPa and a temperature of 20°C.

[0008] Preferably, the two-dimensional carbon substrate in step S2 is graphene oxide, the conductive polymer layer is doped polypyrrole, and the polar polymer is polylactic acid.

[0009] As a preferred method, the preparation method of antistatic particles is as follows: Preparation of graphene oxide dispersion; Pyrrole monomers and dopants were added to the graphene oxide dispersion, and after mixing and adsorption, an initiator was added to carry out in-situ oxidative polymerization to obtain graphene oxide-polypyrrole composite conductive particles. The composite conductive particles are dispersed in a polylactic acid solution, and then antisolvent precipitation is carried out by adding a poor solvent, so that polylactic acid forms a discontinuous shell on the surface of the composite conductive particles. After drying, the antistatic particles are obtained.

[0010] Preferably, the concentration of the graphene oxide dispersion is 2-5 mg / mL, and the ultrasonic treatment time is 40-60 min. The dopant is p-toluenesulfonic acid, and the initiator is ammonium persulfate; The mass ratio of the composite conductive particles to polylactic acid is 1:(0.3-0.5).

[0011] Preferably, the polyol used for polyurethane foaming in step S3 is a mixture of polyether polyol and polymer polyol; the isocyanate is toluene diisocyanate; the foaming agent is water; the catalyst is a mixture of triethanolamine and dibutyltin dilaurate; and the foam stabilizer is open-cell polyether modified silicone oil. The bioactive crystal powder is composed of equal mass of tourmaline powder, obsidian powder and moonstone powder.

[0012] Preferably, the weight ratio of the raw material components used in the foaming process is as follows: 50-60 parts of polyether polyol, 20-30 parts of polymer polyol; 54-56 parts of toluene diisocyanate; 3-6 parts of water; 0.5-1 part of triethanolamine and 0.05-0.15 parts of dibutyltin dilaurate; 0.5-1.5 parts of open-cell polyether modified silicone oil; 5-7 parts of bioactive crystal powder; 6-8 parts of air-permeable filler; 3-8 parts of antistatic particles.

[0013] A composite foam material containing bioactive crystals is prepared by the method described above.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. By constructing a three-dimensional interpenetrating multi-layered air-permeable network consisting of micropores in the diatomaceous earth framework, secondary micropore channels formed by the decomposition of ammonium bicarbonate, and interconnected polyurethane foam pores, and utilizing the hydroxyl groups retained by the modified nanocellulose coated on the diatomaceous earth surface (with a small area coated and a large amount of the diatomaceous earth surface exposed) to achieve capillary moisture conduction, the air permeability and moisture permeability of the composite foam material are significantly improved compared to conventional polyurethane foam.

[0015] 2. Utilizing the high aspect ratio and discontinuous polylactic acid (PLA) ultrathin shell design of graphene oxide-polypyrrole composite conductive particles (the PLA coating on the particle surface is not a uniform and continuous complete film, but forms a discontinuous ultrathin shell with a large number of shell gaps and nanoscale thin-walled regions), a continuous and uniform conductive percolation network is constructed. Charge can be conducted directly through the shell gaps and also through electron tunneling in the nanoscale thin-walled regions, ensuring rapid dissipation of static charge. At the same time, it improves the interfacial compatibility between conductive particles and the substrate and prevents particle aggregation.

[0016] 3. The problem of hydrogen bonding adsorption between silanol groups on the surface of diatomaceous earth and polypyrrole-type NH, resulting in the capture of antistatic particles and their inability to disperse evenly, is solved by synergistic surface passivation treatment with methyltrimethoxysilane and n-octyltriethoxysilane. The former penetrates deep into the micropores for chemical passivation, while the latter constructs a long-chain physical shielding layer on the outer surface, completely blocking the harmful hydrogen bonding between the two. This allows the antistatic particles to disperse freely and form an effective conductive network, without affecting the unobstructed flow and air permeability modification effect of the diatomaceous earth channels. Ultimately, the composite material has both high air permeability and high antistatic properties. Attached Figure Description

[0017] Figure 1 This is a SEM image of the composite foam material prepared in Example 1 of the present invention.

[0018] Figure 2 The image shows the XRD pattern of the composite foam material prepared in Example 1 of this invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention 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 of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1

[0021] A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. Add 15g of diatomaceous earth powder (250 mesh) to 80mL of 14% hydrochloric acid solution, stir and acid wash at 65℃ for 2.5h, filter, wash until neutral, and dry at 105℃ for 5h to obtain activated diatomaceous earth. 10g of activated diatomaceous earth was dispersed in 100mL of ethanol-water mixed solvent with a volume ratio of 9:1. 1.8g of methyltrimethoxysilane and 0.7g of n-octyltriethoxysilane were added. The pH was adjusted to 4.5 with acetic acid. The mixture was stirred at 55℃ for 2.5h. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 60℃ for 4h to obtain surface passivated diatomaceous earth. Ammonium bicarbonate was dissolved in deionized water to prepare a 15% (w / w) ammonium bicarbonate solution, and 0.2% (w / w) of fatty alcohol polyoxyethylene ether nonionic wetting agent was added relative to the solution mass. Passivated diatomaceous earth was added to this solution (passivated diatomaceous earth to solution mass ratio of 1:4), and the solution was placed in a vacuum drying oven and immersed for 1.5 h under a vacuum of -0.085 MPa. Excess solution was removed by centrifugation, and the solution was freeze-dried under vacuum until constant weight to obtain ammonium-loaded diatomaceous earth with a passivated outer surface. 2g of nanocellulose was dispersed in 40mL of ethanol-water mixed solvent with a volume ratio of 4:1, 0.6g of γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 9.5 with sodium hydroxide solution, and the reaction was stirred at 65℃ for 3.5h. After filtration, washing twice with anhydrous ethanol, and drying at 60℃ for 4h, modified nanocellulose was obtained. Ammonium-loaded diatomaceous earth and modified nanocellulose were mixed at a mass ratio of 6:0.7, and anhydrous ethanol was added to form a slurry. The slurry was first dispersed under normal pressure with an ultrasonic power of 300W for 40 minutes. Then the slurry was transferred to a vacuum drying oven and dried under reduced pressure at a vacuum degree of -0.07MPa and a temperature of 20℃ to remove the ethanol and obtain an air-permeable filler.

[0022] S2. Graphene oxide was dispersed in deionized water and treated with ultrasonic power of 500W for 50 min to prepare a graphene oxide dispersion with a concentration of 4 mg / mL. 100 mL of the above graphene oxide dispersion was taken, 1.2 g of pyrrole monomer and 1.85 g of p-toluenesulfonic acid were added, and the mixture was stirred in an ice-water bath at 3℃ for 30 min. Then, 40.7 mL of 10% ammonium persulfate solution was slowly added dropwise at a rate of 1.5 mL / min. After the addition was completed, the mixture was stirred in an ice-water bath for 9 h. The mixture was filtered, washed three times each with deionized water and anhydrous ethanol, and dried under vacuum at 60℃ for 12 h to obtain graphene oxide-polypyrrole composite conductive particles. 0.53 g of polylactic acid (weight average molecular weight 10000) was dissolved in 9 mL of dichloromethane to prepare a polylactic acid solution of about 6%. The above-mentioned composite conductive particles were added to the polylactic acid solution (the mass ratio of composite conductive particles to polylactic acid was 1:0.45). The mixture was stirred at 28 °C for 2 h to achieve uniform dispersion. Then, the mixture was slowly added dropwise to 90 mL of anhydrous ethanol under high-speed stirring at 1000 rpm for anti-solvent precipitation. The mixture was stirred at high speed for 30 min, filtered, washed with anhydrous ethanol, and vacuum dried at 40 °C for 8 h to obtain antistatic particles.

[0023] S3. Weigh out 58 parts by weight of polyether polyol, 27 parts by weight of polymer polyol, 55 parts by weight of toluene diisocyanate, 6 parts by weight of bioactive crystal powder (composed of tourmaline powder, obsidian powder and moonstone powder mixed by weight), 7 parts by weight of air-permeable filler, 6 parts by weight of antistatic particles, 0.8 parts by weight of triethanolamine, 0.12 parts by weight of dibutyltin dilaurate, 5 parts by weight of water, and 1.2 parts by weight of open-cell polyether modified silicone oil. Mix all the above materials except toluene diisocyanate evenly, then add toluene diisocyanate, stir quickly for 8 seconds to mix evenly, and immediately pour into a mold preheated to 50°C. The gelation time is about 100 seconds. Continue to keep in the mold for 6 minutes until the foam has sufficient green strength, then demold and cure at room temperature for 24 hours to obtain a composite foam material containing bioactive crystals.

[0024] Example 2

[0025] A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. Add 15g of diatomaceous earth powder (250 mesh) to 80mL of 11% hydrochloric acid solution, stir and acid wash at 65℃ for 2.5h, filter, wash until neutral, and dry at 105℃ for 5h to obtain activated diatomaceous earth. 10g of activated diatomaceous earth was dispersed in 100mL of ethanol-water mixed solvent with a volume ratio of 9:1. 1.2g of methyltrimethoxysilane and 0.4g of n-octyltriethoxysilane were added. The pH was adjusted to 4.5 with acetic acid. The mixture was stirred at 55℃ for 2.5h. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 60℃ for 4h to obtain surface passivated diatomaceous earth. Ammonium bicarbonate was dissolved in deionized water to prepare a 15% (w / w) ammonium bicarbonate solution, and 0.2% (w / w) of fatty alcohol polyoxyethylene ether nonionic wetting agent was added relative to the solution mass. Passivated diatomaceous earth was added to this solution (passivated diatomaceous earth to solution mass ratio of 1:4), and the solution was placed in a vacuum drying oven and immersed for 1.5 h under a vacuum of -0.085 MPa. Excess solution was removed by centrifugation, and the solution was freeze-dried under vacuum until constant weight to obtain ammonium-loaded diatomaceous earth with a passivated outer surface. 2g of nanocellulose was dispersed in 40mL of ethanol-water mixed solvent with a volume ratio of 4:1, 0.6g of γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 9.5 with sodium hydroxide solution, and the reaction was stirred at 65℃ for 3.5h. After filtration, washing twice with anhydrous ethanol, and drying at 60℃ for 4h, modified nanocellulose was obtained. Ammonium-loaded diatomaceous earth and modified nanocellulose were mixed at a mass ratio of 6:0.6, and anhydrous ethanol was added to form a slurry. The slurry was first dispersed under normal pressure with an ultrasonic power of 300W for 40 minutes. Then the slurry was transferred to a vacuum drying oven and dried under reduced pressure at a vacuum degree of -0.07MPa and a temperature of 20℃ to remove the ethanol and obtain an air-permeable filler.

[0026] S2. Graphene oxide was dispersed in deionized water and treated with ultrasonic power of 500W for 50 min to prepare a graphene oxide dispersion with a concentration of 3 mg / mL. 100 mL of the above graphene oxide dispersion was taken, 1.2 g of pyrrole monomer and 1.85 g of p-toluenesulfonic acid were added, and the mixture was stirred in an ice-water bath at 3℃ for 30 min. Then, 40.7 mL of 10% ammonium persulfate solution was slowly added dropwise at a rate of 1.5 mL / min. After the addition was completed, the mixture was stirred in an ice-water bath for 9 h. The mixture was filtered, washed three times each with deionized water and anhydrous ethanol, and dried under vacuum at 60℃ for 12 h to obtain graphene oxide-polypyrrole composite conductive particles. 0.53 g of polylactic acid (weight average molecular weight 10000) was dissolved in 9 mL of dichloromethane to prepare a polylactic acid solution of about 6%. The above-mentioned composite conductive particles were added to the polylactic acid solution (the mass ratio of composite conductive particles to polylactic acid was 1:0.35). The mixture was stirred at 28 °C for 2 h to achieve uniform dispersion. Then, the mixture was slowly added dropwise to 90 mL of anhydrous ethanol under high-speed stirring at 1000 rpm for anti-solvent precipitation. The mixture was stirred at high speed for 30 min, filtered, washed with anhydrous ethanol, and vacuum dried at 40 °C for 8 h to obtain antistatic particles.

[0027] S3. Weigh out 53 parts by weight of polyether polyol, 22 parts by polymer polyol, 55 parts by weight of toluene diisocyanate, 6 parts by weight of bioactive crystal powder (composed of equal mass of tourmaline powder, obsidian powder and moonstone powder), 7 parts by weight of air-permeable filler, 4 parts by weight of antistatic particles, 0.6 parts by weight of triethanolamine, 0.08 parts by weight of dibutyltin dilaurate, 4 parts by weight of water, and 0.8 parts by weight of open-cell polyether modified silicone oil. Mix all the above materials except toluene diisocyanate evenly, then add toluene diisocyanate, stir quickly for 8 seconds to mix evenly, and immediately pour into a mold preheated to 50°C. The gelation time is about 100 seconds. Continue to keep in the mold for 6 minutes until the foam has sufficient green strength, then demold and cure at room temperature for 24 hours to obtain a composite foam material containing bioactive crystals.

[0028] Example 3

[0029] A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. Add 15g of diatomaceous earth powder (250 mesh) to 80mL of 12% hydrochloric acid solution, stir and acid wash at 65℃ for 2.5h, filter, wash until neutral, and dry at 105℃ for 5h to obtain activated diatomaceous earth. 10g of activated diatomaceous earth was dispersed in 100mL of ethanol-water mixed solvent with a volume ratio of 9:1. 1.5g of methyltrimethoxysilane and 0.5g of n-octyltriethoxysilane were added. The pH was adjusted to 4.5 with acetic acid. The mixture was stirred at 55℃ for 2.5h. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 60℃ for 4h to obtain surface passivated diatomaceous earth. Ammonium bicarbonate was dissolved in deionized water to prepare a 15% (w / w) ammonium bicarbonate solution, and 0.2% (w / w) of fatty alcohol polyoxyethylene ether nonionic wetting agent was added relative to the solution mass. Passivated diatomaceous earth was added to this solution (passivated diatomaceous earth to solution mass ratio of 1:4), and the solution was placed in a vacuum drying oven and immersed for 1.5 h under a vacuum of -0.085 MPa. Excess solution was removed by centrifugation, and the solution was freeze-dried under vacuum until constant weight to obtain ammonium-loaded diatomaceous earth with a passivated outer surface. 2g of nanocellulose was dispersed in 40mL of ethanol-water mixed solvent with a volume ratio of 4:1, 0.6g of γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 9.5 with sodium hydroxide solution, and the reaction was stirred at 65℃ for 3.5h. After filtration, washing twice with anhydrous ethanol, and drying at 60℃ for 4h, modified nanocellulose was obtained. Ammonium-loaded diatomaceous earth and modified nanocellulose were mixed at a mass ratio of 6:0.65, and anhydrous ethanol was added to form a slurry. The slurry was first dispersed under normal pressure with an ultrasonic power of 300W for 40 minutes. Then the slurry was transferred to a vacuum drying oven and dried under reduced pressure at a vacuum degree of -0.07MPa and a temperature of 20℃ to remove the ethanol and obtain an air-permeable filler.

[0030] S2. Graphene oxide was dispersed in deionized water and treated with ultrasonic power of 500W for 50 min to prepare a graphene oxide dispersion with a concentration of 3.5 mg / mL. 100 mL of the above graphene oxide dispersion was taken, 1.2 g of pyrrole monomer and 1.85 g of p-toluenesulfonic acid were added, and the mixture was stirred in an ice-water bath at 3℃ for 30 min. Then, 40.7 mL of 10% ammonium persulfate solution was slowly added dropwise at a rate of 1.5 mL / min. After the addition was completed, the mixture was stirred in an ice-water bath for 9 h. The mixture was filtered, washed three times each with deionized water and anhydrous ethanol, and dried under vacuum at 60℃ for 12 h to obtain graphene oxide-polypyrrole composite conductive particles. 0.53 g of polylactic acid (weight average molecular weight 10000) was dissolved in 9 mL of dichloromethane to prepare a polylactic acid solution of about 6%. The above-mentioned composite conductive particles were added to the polylactic acid solution (the mass ratio of composite conductive particles to polylactic acid was 1:0.4). The mixture was stirred at 28 °C for 2 h to achieve uniform dispersion. Then, the mixture was slowly added dropwise to 90 mL of anhydrous ethanol under high-speed stirring at 1000 rpm for anti-solvent precipitation. The mixture was stirred at high speed for 30 min, filtered, washed with anhydrous ethanol, and vacuum dried at 40 °C for 8 h to obtain antistatic particles.

[0031] S3. Weigh out 55 parts by weight of polyether polyol, 25 parts by weight of polymer polyol, 55 parts by weight of toluene diisocyanate, 6 parts by weight of bioactive crystal powder (composed of equal mass of tourmaline powder, obsidian powder and moonstone powder), 7 parts by weight of air-permeable filler, 5 parts by weight of antistatic particles, 0.8 parts by weight of triethanolamine, 0.1 parts by weight of dibutyltin dilaurate, 4.5 parts by weight of water, and 1 part by weight of open-cell polyether modified silicone oil. Mix all the above materials except toluene diisocyanate evenly, then add toluene diisocyanate, stir quickly for 8 seconds to mix evenly, and immediately pour into a mold preheated to 50°C. The gelation time is about 100 seconds. Continue to keep in the mold for 6 minutes until the foam has sufficient green strength, then demold and cure at room temperature for 24 hours to obtain a composite foam material containing bioactive crystals.

[0032] Example 4

[0033] A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. Add 15g of diatomaceous earth powder (250 mesh) to 80mL of 15% hydrochloric acid solution, stir and acid wash at 70℃ for 3h, filter, wash until neutral, and dry at 105℃ for 5h to obtain activated diatomaceous earth. 10g of activated diatomaceous earth was dispersed in 100mL of ethanol-water mixed solvent with a volume ratio of 9:1. 2g of methyltrimethoxysilane and 0.8g of n-octyltriethoxysilane were added. The pH was adjusted to 5 with acetic acid. The mixture was stirred at 60℃ for 3h. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 60℃ for 4h to obtain surface passivated diatomaceous earth. Ammonium bicarbonate was dissolved in deionized water to prepare a 15% (w / w) ammonium bicarbonate solution, and 0.2% (w / w) of fatty alcohol polyoxyethylene ether nonionic wetting agent was added relative to the solution mass. Passivated diatomaceous earth was added to this solution (passivated diatomaceous earth to solution mass ratio of 1:4), and the solution was placed in a vacuum drying oven and immersed for 1.5 h under a vacuum of -0.085 MPa. Excess solution was removed by centrifugation, and the solution was freeze-dried under vacuum until constant weight to obtain ammonium-loaded diatomaceous earth with a passivated outer surface. 2g of nanocellulose was dispersed in 40mL of ethanol-water mixed solvent with a volume ratio of 4:1, 0.6g of γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 9.5 with sodium hydroxide solution, and the reaction was stirred at 65℃ for 3.5h. After filtration, washing twice with anhydrous ethanol, and drying at 60℃ for 4h, modified nanocellulose was obtained. Ammonium-loaded diatomaceous earth and modified nanocellulose were mixed at a mass ratio of 6:0.8, and anhydrous ethanol was added to form a slurry. The slurry was first dispersed under normal pressure with an ultrasonic power of 300W for 45 minutes. Then the slurry was transferred to a vacuum drying oven and dried under reduced pressure at a vacuum degree of -0.08MPa and a temperature of 20℃ to remove the ethanol and obtain an air-permeable filler.

[0034] S2. Graphene oxide was dispersed in deionized water and treated with ultrasonic power of 500W for 60 min to prepare a graphene oxide dispersion with a concentration of 5 mg / mL. 100 mL of the above graphene oxide dispersion was taken, 1.2 g of pyrrole monomer and 1.85 g of p-toluenesulfonic acid were added, and the mixture was stirred in an ice-water bath at 3℃ for 30 min. Then, 40.7 mL of 10% ammonium persulfate solution was slowly added dropwise at a rate of 1.5 mL / min. After the addition was completed, the mixture was stirred in an ice-water bath for 9 h. The mixture was filtered, washed three times each with deionized water and anhydrous ethanol, and dried under vacuum at 60℃ for 12 h to obtain graphene oxide-polypyrrole composite conductive particles. 0.53 g of polylactic acid (weight average molecular weight 10000) was dissolved in 9 mL of dichloromethane to prepare a polylactic acid solution of about 6%. The above-mentioned composite conductive particles were added to the polylactic acid solution (the mass ratio of composite conductive particles to polylactic acid was 1:0.5). The mixture was stirred at 28 °C for 2 h to achieve uniform dispersion. Then, the mixture was slowly added dropwise to 90 mL of anhydrous ethanol under high-speed stirring at 1000 rpm for anti-solvent precipitation. The mixture was stirred at high speed for 30 min, filtered, washed with anhydrous ethanol, and vacuum dried at 40 °C for 8 h to obtain antistatic particles.

[0035] S3. Weigh out 60 parts by weight of polyether polyol, 30 parts by weight of polymer polyol, 56 parts by weight of toluene diisocyanate, 7 parts by weight of bioactive crystal powder (composed of tourmaline powder, obsidian powder and moonstone powder mixed by weight), 8 parts by weight of air-permeable filler, 8 parts by weight of antistatic particles, 1 part by weight of triethanolamine, 0.15 parts by weight of dibutyltin dilaurate, 6 parts by weight of water, and 1.5 parts by weight of open-cell polyether modified silicone oil. Mix all the above materials except toluene diisocyanate evenly, then add toluene diisocyanate, stir quickly for 8 seconds to mix evenly, and immediately pour into a mold preheated to 50°C. The gelation time is about 100 seconds. Continue to keep in the mold for 6 minutes until the foam has sufficient green strength, then demold and cure at room temperature for 24 hours to obtain a composite foam material containing bioactive crystals.

[0036] Example 5

[0037] A method for preparing a composite foam material containing bioactive crystals includes the following steps: S1. Add 15g of diatomaceous earth powder (250 mesh) to 80mL of 10% hydrochloric acid solution, stir and acid wash at 60℃ for 2h, filter, wash until neutral, and dry at 105℃ for 5h to obtain activated diatomaceous earth. 10g of activated diatomaceous earth was dispersed in 100mL of ethanol-water mixed solvent with a volume ratio of 9:1. 1g of methyltrimethoxysilane and 0.3g of n-octyltriethoxysilane were added. The pH was adjusted to 4 with acetic acid. The mixture was stirred at 50℃ for 2h. After filtration, the mixture was washed twice with anhydrous ethanol and dried at 60℃ for 4h to obtain surface passivated diatomaceous earth. Ammonium bicarbonate was dissolved in deionized water to prepare a 15% (w / w) ammonium bicarbonate solution, and 0.2% (w / w) of fatty alcohol polyoxyethylene ether nonionic wetting agent was added relative to the solution mass. Passivated diatomaceous earth was added to this solution (passivated diatomaceous earth to solution mass ratio of 1:4), and the solution was placed in a vacuum drying oven and immersed for 1.5 h under a vacuum of -0.085 MPa. Excess solution was removed by centrifugation, and the solution was freeze-dried under vacuum until constant weight to obtain ammonium-loaded diatomaceous earth with a passivated outer surface. 2g of nanocellulose was dispersed in 40mL of ethanol-water mixed solvent with a volume ratio of 4:1, 0.6g of γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 9.5 with sodium hydroxide solution, and the reaction was stirred at 65℃ for 3.5h. After filtration, washing twice with anhydrous ethanol, and drying at 60℃ for 4h, modified nanocellulose was obtained. Ammonium-loaded diatomaceous earth and modified nanocellulose were mixed at a mass ratio of 6:0.5, and anhydrous ethanol was added to form a slurry. The slurry was first dispersed under normal pressure with an ultrasonic power of 300W for 30 minutes. Then the slurry was transferred to a vacuum drying oven and dried under reduced pressure at a vacuum degree of -0.06MPa and a temperature of 20℃ to remove the ethanol and obtain an air-permeable filler.

[0038] S2. Graphene oxide was dispersed in deionized water and treated with ultrasonic power of 500W for 40 min to prepare a graphene oxide dispersion with a concentration of 2 mg / mL. 100 mL of the above graphene oxide dispersion was taken, 1.2 g of pyrrole monomer and 1.85 g of p-toluenesulfonic acid were added, and the mixture was stirred in an ice-water bath at 3℃ for 30 min. Then, 40.7 mL of 10% ammonium persulfate solution was slowly added dropwise at a rate of 1.5 mL / min. After the addition was completed, the mixture was stirred in an ice-water bath for 9 h. The mixture was filtered, washed three times each with deionized water and anhydrous ethanol, and dried under vacuum at 60℃ for 12 h to obtain graphene oxide-polypyrrole composite conductive particles. 0.53 g of polylactic acid (weight average molecular weight 10000) was dissolved in 9 mL of dichloromethane to prepare a polylactic acid solution of about 6%. The above-mentioned composite conductive particles were added to the polylactic acid solution (the mass ratio of composite conductive particles to polylactic acid was 1:0.3). The mixture was stirred at 28 °C for 2 h to disperse it evenly. Then, the mixture was slowly added dropwise to 90 mL of anhydrous ethanol under high-speed stirring at 1000 rpm for anti-solvent precipitation. The mixture was stirred at high speed for 30 min, filtered, washed with anhydrous ethanol, and vacuum dried at 40 °C for 8 h to obtain antistatic particles.

[0039] S3. Weigh out 50 parts by weight of polyether polyol, 20 parts by weight of polymer polyol, 54 parts by weight of toluene diisocyanate, 6 parts by weight of bioactive crystal powder (composed of tourmaline powder, obsidian powder and moonstone powder mixed by weight), 6 parts by weight of air-permeable filler, 3 parts by weight of antistatic particles, 0.5 parts by weight of triethanolamine, 0.05 parts by weight of dibutyltin dilaurate, 3 parts by weight of water, and 0.5 parts by weight of open-cell polyether modified silicone oil. Mix all the above materials except toluene diisocyanate evenly, then add toluene diisocyanate, stir quickly for 8 seconds to mix evenly, and immediately pour into a mold preheated to 50°C. The gelation time is about 100 seconds. Continue to keep in the mold for 6 minutes until the foam has sufficient green strength, then demold and cure at room temperature for 24 hours to obtain a composite foam material containing bioactive crystals.

[0040] Comparative Example 1: The only difference from Example 4 is that the synergistic surface passivation treatment step of methyltrimethoxysilane and n-octyltriethoxysilane is omitted in step S1, and the activated diatomaceous earth is directly used for subsequent ammonium bicarbonate loading. The remaining steps and parameters are exactly the same as in Example 4.

[0041] Comparative Example 2: The only difference from Example 4 is that only methyltrimethoxysilane is added in the surface passivation treatment of step S1, and n-octyltriethoxysilane is not added. All other steps and parameters are exactly the same as in Example 4.

[0042] Comparative Example 3: The only difference from Example 4 is that only n-octyltriethoxysilane is added in the surface passivation treatment of step S1, instead of methyltrimethoxysilane. All other steps and parameters are exactly the same as in Example 4.

[0043] Comparative Example 4: The only difference from Example 4 is that the ammonium bicarbonate vacuum impregnation loading step is omitted in step S1, and the surface passivated diatomaceous earth is directly mixed with modified nanocellulose to prepare the air-permeable filler. The remaining steps and parameters are exactly the same as in Example 4.

[0044] Comparative Example 5: The only difference from Example 4 is that the preparation and coating steps of modified nanocellulose are omitted in step S1, and ammonium-loaded diatomaceous earth is directly added to the foaming system as a breathable filler. The remaining steps and parameters are exactly the same as in Example 4.

[0045] Comparative Example 6: The only difference from Example 4 is that the polylactic acid discontinuous shell coating step is omitted in step S2, and graphene oxide-polypyrrole composite conductive particles are directly added to the foaming system as antistatic particles. The remaining steps and parameters are exactly the same as in Example 4.

[0046] Comparative Example 7: The only difference from Example 4 is that no breathable filler and antistatic particles are added in step S3. Only the bioactive crystal powder is mixed with the polyurethane foaming raw material for foaming. The remaining steps and parameters are exactly the same as in Example 4.

[0047] Performance testing (1) Air permeability test: According to the method of GB / T 10655-2003 "Determination of air permeability of porous polymer elastic materials", the foam sample is cut into a circular sample with a diameter of 70 mm and a thickness of 25 mm, placed in the test chamber of the air permeability tester, and the air flow rate through the sample is measured under a constant pressure difference of 125 Pa. The air permeability value (unit: L / min) is recorded. The average value of 3 samples in each group is taken.

[0048] (2) Surface resistivity test: According to GB / T 31838.3-2019 "Dielectric and resistive properties of solid insulating materials - Part 3: Resistive properties (DC method) - Surface resistance and surface resistivity", the foam sample was cut into sheet-like specimens of 100mm×100mm×10mm. After conditioning in a standard environment of 23±2℃ and 50±5% relative humidity for 24h, the surface resistivity of the specimen was measured using a high resistance meter (applied voltage 500V, charging time 60s). The average value of 3 specimens in each group was taken, and the result was expressed in Ω.

[0049] (3) Compression set test: According to the method of GB / T 6669-2008 "Determination of compression set of flexible foam polymer materials", the foam sample was cut into 50mm×50mm×25mm specimens, compressed to 50% of the original thickness at 23±2℃ and kept for 72h, then the pressure was released, and the specimen thickness was measured after 30min of recovery in the standard environment. The compression set rate was calculated according to C=(d0-d1) / d0×100%. The average value of 3 specimens in each group was taken.

[0050] Table 1:

[0051] Comparative Example 1 omitted the silane passivation treatment, and its surface resistivity increased sharply to 4.7 × 10⁻⁶. 10The Ω value indicates that the lack of silane passivation treatment affected the dispersion of antistatic particles, confirming that the hydrogen bond trapping effect of unpassivated activated diatomaceous earth severely disrupted the formation of the conductive percolation network. Comparative Example 2, using only MTMS without OTES, had a surface resistivity of 6.3 × 10⁻⁶. 9 The Ω indicates that short-chain chemical passivation alone is insufficient to completely prevent interfacial interference. Comparative Example 3, using only OTES without MTMS, has a surface resistivity of 8.1 × 10⁻⁶. 9 The results for Ω were even worse than those for Comparative Example 2, confirming the shortcomings of long-chain silanes, which suffer from low coverage density and inability to enter narrow orifice regions due to their steric hindrance. The results of Comparative Example 2 and Comparative Example 3 together demonstrate the necessity of using MTMS and OTES in synergy.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the essence and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite foam material containing bioactive crystals, characterized in that, Includes the following steps: S1. A porous mineral material loaded with substances that are easily decomposed by heat and produce gas is used as the core and coated with a hydrophilic polymer nanomaterial to prepare a breathable filler with a core-shell structure. S2. A conductive polymer layer is polymerized in situ on the surface of a two-dimensional carbon substrate, and then a discontinuous coating of polar polymer is applied to its outermost layer to obtain antistatic particles with some conductive polymer exposed on the surface. S3. Polyurethane foam polyol, bioactive crystal powder, the air-permeable filler, the antistatic particles, foaming agent and catalyst are mixed evenly, and isocyanate is added for foaming and curing; during the exothermic foaming process, the gas-generating substances in the core of the air-permeable filler are decomposed by heat to form secondary microporous channels.

2. The method for preparing a composite foam material containing bioactive crystals according to claim 1, characterized in that, The porous mineral material in step S1 is activated diatomaceous earth with surface passivation modification by silane coupling agent, the gas-producing substance that is easily decomposed by heat is ammonium bicarbonate, and the hydrophilic polymer nanomaterial is nanocellulose grafted with epoxy silane.

3. The method for preparing a composite foam material containing bioactive crystals according to claim 2, characterized in that, The method for preparing the permeable filler with the core-shell structure is as follows: Diatomaceous earth was acid-washed and activated, and then synergistically modified with methyltrimethoxysilane and n-octyltriethoxysilane to obtain surface-passivated diatomaceous earth. The surface passivated diatomaceous earth is impregnated in an ammonium bicarbonate solution, then vacuum impregnated and dried under the condition of containing a wetting agent, so that the ammonium bicarbonate is loaded into the pores of the diatomaceous earth to obtain ammonium-loaded diatomaceous earth. Modified nanocellulose was obtained by reacting nanocellulose with γ-glycidoxypropyltrimethoxysilane. The ammonium-loaded diatomaceous earth and the modified nanocellulose were mixed in a certain mass ratio, and then ultrasonically dispersed and dried under reduced pressure in a solvent to obtain the air-permeable filler.

4. The method for preparing a composite foam material containing bioactive crystals according to claim 3, characterized in that, The acid washing and activation process involves adding diatomaceous earth to a hydrochloric acid solution with a mass concentration of 10-15% and stirring at 60-70°C for 2-3 hours. Then, for surface modification, the activated diatomaceous earth is dispersed in an ethanol-water mixed solvent, methyltrimethoxysilane and n-octyltriethoxysilane are added, the pH is adjusted to 4-5 with acetic acid, and the reaction is stirred at 50-60°C for 2-3 hours. The mass ratio of the activated diatomaceous earth to methyltrimethoxysilane is 1:(0.1-0.2); The mass ratio of the activated diatomaceous earth to n-octyltriethoxysilane is 1:(0.03-0.08); The ammonium-loaded diatomaceous earth and modified nanocellulose were mixed in a mass ratio of 6:(0.5-0.8). The mixture was first ultrasonically dispersed in anhydrous ethanol at atmospheric pressure for 30-45 min, and then the solvent was removed by vacuum evaporation under a vacuum of -0.06 to -0.08 MPa and a temperature of 20°C.

5. The method for preparing a composite foam material containing bioactive crystals according to claim 1, characterized in that, In step S2, the two-dimensional carbon substrate is graphene oxide, the conductive polymer layer is doped polypyrrole, and the polar polymer is polylactic acid.

6. The method for preparing a composite foam material containing bioactive crystals according to claim 5, characterized in that, The preparation method of antistatic particles is as follows: Preparation of graphene oxide dispersion; Pyrrole monomers and dopants were added to the graphene oxide dispersion, and after mixing and adsorption, an initiator was added to carry out in-situ oxidative polymerization to obtain graphene oxide-polypyrrole composite conductive particles. The composite conductive particles are dispersed in a polylactic acid solution, and then antisolvent precipitation is carried out by adding a poor solvent, so that polylactic acid forms a discontinuous shell on the surface of the composite conductive particles. After drying, the antistatic particles are obtained.

7. The method for preparing a composite foam material containing bioactive crystals according to claim 6, characterized in that, The concentration of the graphene oxide dispersion is 2-5 mg / mL, and the ultrasonic treatment time is 40-60 min. The dopant is p-toluenesulfonic acid, and the initiator is ammonium persulfate; The mass ratio of the composite conductive particles to polylactic acid is 1:(0.3-0.5).

8. The method for preparing a composite foam material containing bioactive crystals according to claim 1, characterized in that, In step S3, the polyol used for polyurethane foaming is a mixture of polyether polyol and polymer polyol; the isocyanate is toluene diisocyanate; the foaming agent is water; the catalyst is a mixture of triethanolamine and dibutyltin dilaurate; and the foam stabilizer is open-cell polyether modified silicone oil. The bioactive crystal powder is composed of equal mass of tourmaline powder, obsidian powder and moonstone powder.

9. The method for preparing a composite foam material containing bioactive crystals according to claim 8, characterized in that, The weight ratio of the raw material components used in the foaming process is as follows: 50-60 parts of polyether polyol, 20-30 parts of polymer polyol; 54-56 parts of toluene diisocyanate; 3-6 parts of water; 0.5-1 part of triethanolamine and 0.05-0.15 parts of dibutyltin dilaurate; 0.5-1.5 parts of open-cell polyether modified silicone oil; 5-7 parts of bioactive crystal powder; 6-8 parts of air-permeable filler; 3-8 parts of antistatic particles.

10. A composite foam material containing bioactive crystals, characterized in that, It is prepared by the method described in any one of claims 1 to 9 above.

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