Nano-copper composite sponge, its preparation method and application

Abstract

This application relates to a nano-copper composite sponge, its preparation method, and its application. The nano-copper composite sponge comprises a polyurethane sponge substrate and modified nano-copper; the modified nano-copper has a core-shell structure, with the core being elemental nano-copper and the shell containing copper hydroxyl groups bonded to the surface of the elemental nano-copper; the copper hydroxyl groups in the shell undergo a nucleophilic addition reaction with the isocyanate groups in the polyurethane sponge substrate to form covalently linked urethane bonds, thereby uniformly loading the modified nano-copper into the polyurethane sponge matrix. The solution provided in this application enables deep composite bonding of nano-copper with a sponge substrate, resulting in a long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponge material.

Description

Technical Field

[0001] This application relates to the fields of polymer materials and antibacterial new materials technology, and in particular to nano-copper composite sponges, their preparation methods and applications. Background Technology

[0002] Currently, most commercially available antibacterial sponges introduce antibacterial components (such as quaternary ammonium salts, silver ions, copper ions, plant extracts, etc.) through surface spraying of antibacterial agents, soaking, or simple physical mixing. However, the above technical solutions have the following core defects: 1. The antibacterial ingredients are easily detached, resulting in insufficient long-lasting effectiveness. The antibacterial agent adhering to the surface is quickly washed away by water and squeezed, resulting in a significant decrease in antibacterial performance after long-term use, and failing to meet the need for long-term protection.

[0003] 2. Limited protective measures and lack of antiviral capabilities. Current mainstream antibacterial technologies can only inhibit some bacteria and lack effective killing or inhibition effects on viruses, molds, mites, etc., making it difficult to meet the multi-dimensional protection needs in complex environments.

[0004] 3. Copper-based materials have poor stability, making them difficult to apply on a large scale. Although nano-copper has broad-spectrum antibacterial and antiviral potential, conventional nano-copper particles are prone to oxidation and blackening, and are also prone to small molecule agglomeration and clumping, resulting in uneven antibacterial performance and rapid failure. At the same time, it is difficult to introduce them stably and on a large scale into sponge substrates.

[0005] 4. There are chemical residues and safety hazards. Some chemical antibacterial agents pose a risk of skin irritation or heavy metal leaching and are not suitable for sensitive applications such as those involving mothers and infants or in the medical field.

[0006] In summary, current technologies cannot achieve deep composite bonding between copper nanoparticles and sponge substrates, thus failing to meet market demand for long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponges. Summary of the Invention

[0007] To address or partially address the problems existing in related technologies, this application provides a nano-copper composite sponge, its preparation method, and its application, which can achieve deep composite of nano-copper and sponge substrate to obtain a long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponge material.

[0008] The first aspect of this application provides a nano-copper composite sponge, comprising a polyurethane sponge substrate and modified nano-copper; the modified nano-copper has a core-shell structure, the core being elemental nano-copper, and the shell containing copper hydroxyl groups bonded to the surface of the elemental nano-copper; the copper hydroxyl groups in the shell undergo a nucleophilic addition reaction with the isocyanate groups in the polyurethane sponge substrate to form covalently linked urethane bonds, thereby uniformly loading the modified nano-copper in the polyurethane sponge matrix.

[0009] In one specific embodiment, the copper hydroxyl groups in the shell are formed by the nano-copper element coming into contact with a hydroxyl-containing solvent during the centrifugal washing and dispersion process.

[0010] In one specific embodiment, the hydroxyl-containing solvent includes water, ethanol, or a combination thereof.

[0011] In one specific embodiment, the nano-copper is obtained by reducing copper salt in an aqueous phase in a reduction system composed of titanium tetrachloride and titanium trichloride.

[0012] In one specific embodiment, the modified nano-copper accounts for 0.1% to 5% of the mass percentage of the nano-copper composite sponge.

[0013] In one specific embodiment, the modified nano-copper has a particle size of 200nm~800nm.

[0014] In one specific embodiment, the raw materials of the nano-copper composite sponge include 65% to 66% polyurethane polyol, 25% to 28% isocyanate, 1% to 2% foaming agent, 0.1% to 0.5% catalyst, and 0.1% to 5% modified nano-copper.

[0015] In one specific embodiment, the nano-copper composite sponge further includes nano-titanium oxide, wherein the nano-titanium oxide accounts for 0.1% to 5% of the mass percentage of the nano-copper composite sponge.

[0016] In one specific embodiment, the polyurethane polyol includes at least one of polyether polyol, polyester polyol, and polycarbonate polyol.

[0017] In one specific embodiment, the isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate.

[0018] In one specific embodiment, the foaming agent includes at least one of water, cyclopentane, and dichloromethane.

[0019] In one specific embodiment, the catalyst includes a foaming catalyst and a gel catalyst. Preferably, the gel catalyst includes at least one of stannous octoate (T9), dibutyltin dilaurate, and bismuth isooctanoate; and / or, the foaming catalyst includes at least one of triethylenediamine (A33), bis(dimethylaminoethyl) ether, and N-methylmorpholine.

[0020] A second aspect of this application provides a method for preparing the aforementioned nano-copper composite sponge, comprising the following steps: Modified nano-copper is mixed with the raw materials of polyurethane foam substrate and foamed in situ. During the nucleation and growth of the foam cells, the modified nano-copper is embedded in the foam skeleton. At the same time, the copper hydroxyl groups in the shell of the modified nano-copper undergo nucleophilic addition reaction with the isocyanate groups to form covalently linked urethane bonds, so that the modified nano-copper is uniformly loaded in the polyurethane foam matrix.

[0021] In one specific embodiment, the in-situ foaming of the modified nano-copper with the polyurethane sponge substrate includes the following steps: Modified nano-copper is mixed with polyurethane polyol and stirred evenly to form a mixture; Isocyanate, foaming agent, and catalyst are added to the mixture for in-situ foaming.

[0022] In one specific embodiment, the process conditions for the in-situ foaming are as follows: Before the mixture is mixed with the isocyanate, the temperature of the mixture and the isocyanate is 21°C to 23°C; and / or, the milky whitening time is 8 to 10 seconds; and / or, the rise time is 40 to 55 seconds; and / or, the gel time is 70 to 85 seconds; and / or, the maximum core temperature during the sponge foaming process is controlled at 150 to 165°C.

[0023] The third aspect of this application provides an application of shape memory sponge, in which the aforementioned nano-copper composite sponge or the nano-copper composite sponge prepared by the aforementioned method is used in the fields of household cleaning, bedding filling, maternal and infant products, public health equipment and medical care consumables.

[0024] The technical solution provided in this application may include the following beneficial results: In this embodiment, the modified copper nanoshell effectively blocks the contact between oxygen and water molecules and the copper nanocore, preventing the copper nanoshell from oxidizing and turning black. Simultaneously, the hydroxyl groups on the shell surface provide active sites for chemical bonding with the polyurethane substrate. If the modified copper nanoshell lacks a core-shell structure, the copper nanocore is easily oxidized and discolored in air, and tends to agglomerate during sponge foaming, leading to uneven antibacterial performance and rapid failure. If the shell does not contain hydroxyl groups, the copper nanoshell cannot form covalent bonds with the polyurethane substrate and can only be physically dispersed in the sponge, easily detaching and being lost during washing or extrusion, thus failing to achieve long-lasting antibacterial effects. Therefore, this embodiment achieves uniform loading and anchoring of copper nanoshells in the polyurethane sponge matrix through the synergistic effect of core-shell structure design and chemical bonding, obtaining a long-lasting, safe, broad-spectrum antibacterial and antiviral functional sponge material, solving the problems of easy detachment of antibacterial components and easy oxidation and agglomeration of copper nanoshells.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the modified copper nanoparticles from Example 1; Figure 2 The image shows the EDS test results of the nano-copper composite sponge from Example 1. Detailed Implementation

[0027] The embodiments of this application will now be described in more detail. It should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0028] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0029] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] Currently, most commercially available antibacterial sponges introduce antibacterial components (such as quaternary ammonium salts, silver ions, copper ions, plant extracts, etc.) through surface spraying of antibacterial agents, soaking, or simple physical mixing. However, the above technical solutions have the following core defects: 1. The antibacterial ingredients are easily detached, resulting in insufficient long-lasting effectiveness. The antibacterial agent adhering to the surface is quickly washed away by water and squeezed, resulting in a significant decrease in antibacterial performance after long-term use, and failing to meet the need for long-term protection.

[0031] 2. Limited protective measures and lack of antiviral capabilities. Current mainstream antibacterial technologies can only inhibit some bacteria and lack effective killing or inhibition effects on viruses, molds, mites, etc., making it difficult to meet the multi-dimensional protection needs in complex environments.

[0032] 3. Copper-based materials have poor stability, making them difficult to apply on a large scale. Although nano-copper has broad-spectrum antibacterial and antiviral potential, conventional nano-copper particles are prone to oxidation and blackening, and are also prone to small molecule agglomeration and clumping, resulting in uneven antibacterial performance and rapid failure. At the same time, it is difficult to introduce them stably and on a large scale into sponge substrates.

[0033] 4. There are chemical residues and safety hazards. Some chemical antibacterial agents pose a risk of skin irritation or heavy metal leaching and are not suitable for sensitive applications such as those involving mothers and infants or in the medical field.

[0034] In summary, current technologies cannot achieve deep composite bonding between copper nanoparticles and sponge substrates, thus failing to meet market demand for long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponges.

[0035] To address the aforementioned issues, this application provides a nano-copper composite sponge that enables deep composite bonding between nano-copper and a sponge substrate, resulting in a long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponge material.

[0036] This application provides a nano-copper composite sponge, comprising a polyurethane sponge substrate and modified nano-copper; the modified nano-copper has a core-shell structure, with the core being elemental nano-copper and the shell containing copper hydroxyl groups bonded to the surface of the elemental nano-copper; the copper hydroxyl groups in the shell undergo a nucleophilic addition reaction with the isocyanate groups in the polyurethane sponge substrate to form covalently linked urethane bonds, thereby uniformly loading the modified nano-copper in the polyurethane sponge matrix.

[0037] In this embodiment of the application, the modified nano-copper core-shell structure can refer to a composite structure composed of an inner layer of nano-copper element and an outer layer of copper hydroxyl shell. The nano-copper element core provides broad-spectrum antibacterial and antiviral activity, while the outer shell plays a dual role in protecting the core and connecting the substrate.

[0038] In this embodiment, copper hydroxyl groups undergo a nucleophilic addition reaction with isocyanate groups in the polyurethane sponge substrate to form covalently linked urethane bonds. This means that the hydroxyl groups on the surface of the modified copper nanoshell undergo a nucleophilic addition reaction with unreacted isocyanate groups to form covalent bonds. Through this chemical bonding method, the modified copper nanoshell is covalently anchored in the polyurethane sponge matrix, rather than simply physically attached. The advantage of this structural design is that the shell effectively blocks contact between oxygen and water molecules and the copper nanoshell core, preventing the copper nanoshell from oxidizing and turning black. Simultaneously, the hydroxyl groups on the shell surface provide active sites for chemical bonding with the polyurethane substrate. If the modified copper nanoshell lacks a core-shell structure, the copper nanoshell core is easily oxidized and discolored in air, and tends to aggregate during sponge foaming, leading to uneven antibacterial performance and rapid failure. If the shell does not contain hydroxyl groups, the copper nanoshell cannot form covalent bonds with the polyurethane substrate and can only be physically dispersed in the sponge, easily detaching and being lost during washing or squeezing, thus failing to achieve long-lasting antibacterial effects.

[0039] Therefore, the embodiments of this application achieve uniform loading and anchoring of copper nanoparticles in a polyurethane sponge matrix through the synergistic effect of core-shell structure design and chemical bonding, thereby obtaining a long-lasting, safe, and broad-spectrum antibacterial and antiviral functional sponge material, solving the problems of easy shedding of antibacterial components and easy oxidation and aggregation of copper nanoparticles.

[0040] In one specific embodiment, the copper hydroxyl groups in the shell are formed by the contact of nano-copper elements with a hydroxyl-containing solvent during centrifugal washing and dispersion.

[0041] The surface of elemental copper nanoparticles exhibits high chemical activity. When they come into contact with solvents containing hydroxyl groups, the hydroxyl groups in the solvent adsorb onto copper atoms or form chemical bonds with copper atoms, thereby forming copper hydroxyl groups on the copper surface. Specifically, the reaction solution is first centrifuged to separate the copper nanoparticles, then washed multiple times with a solvent containing hydroxyl groups to finally obtain modified copper nanoparticles. In this series of operations, the surface of the copper nanoparticles is in full contact with the hydroxyl-containing solvent, thus forming a copper hydroxyl shell.

[0042] Preferably, the hydroxyl-containing solvent includes water, ethanol, or a combination thereof.

[0043] The technical functions of hydroxyl-containing solvents are twofold: first, to provide a hydroxyl source for forming a copper hydroxyl shell; and second, to act as a dispersion medium to prevent the aggregation of copper nanoparticles. Ethanol, due to its volatility, is particularly beneficial for solvent removal during subsequent mixing with the polyurethane prepolymer.

[0044] In one specific embodiment, elemental copper nanoparticles are obtained by reducing copper salts in an aqueous phase within a reduction system composed of titanium tetrachloride and titanium trichloride.

[0045] Titanium trichloride is the primary reducing agent; its trivalent titanium ions possess reducing properties and can reduce divalent copper ions to zero-valent copper. Titanium tetrachloride is an auxiliary component; it hydrolyzes in aqueous solution to produce hydrochloric acid, which is used to adjust the pH of the system. It may also participate in the morphology control of copper nanoparticles or play a role in stabilizing the nanoparticles.

[0046] The copper source is a copper salt, specifically one or more of copper sulfate, copper chloride, and cuprous chloride, which provides divalent or monovalent copper ions.

[0047] The copper nanoparticles prepared by this method do not introduce any organic surfactants, thus avoiding interference from organic residues in the subsequent bonding reaction with isocyanate groups. Moreover, the in-situ reduction method allows copper nanoparticles to be directly reduced in the liquid phase, resulting in particles with narrow size distribution and good dispersibility.

[0048] In one specific embodiment, the modified nano-copper accounts for 0.1% to 5% of the mass of the nano-copper composite sponge.

[0049] Regarding the content of modified nano-copper, if the addition amount is less than 0.1%, the effective antibacterial components in the sponge are insufficient, and the antibacterial rate cannot reach 99%, making it difficult to meet the requirements of sensitive scenarios such as medical and maternal and infant use. If the addition amount of modified nano-copper is greater than 5%, the dispersion of nano-copper in the polyol system becomes extremely difficult, and the probability of collision and aggregation due to Brownian motion increases significantly. This results in excessively high nano-copper concentrations in some areas of the sponge while other areas have excessively low concentrations, leading to uneven antibacterial performance. At the same time, the foam structure of the sponge may be damaged, and the resilience will decrease. Therefore, controlling the addition amount of modified nano-copper within the range of 0.1% to 5% can ensure excellent antibacterial performance while also taking into account dispersion stability, process operability, and economy.

[0050] In one specific embodiment, the particle size of the modified nano-copper is 200nm~800nm.

[0051] Regarding the particle size of modified copper nanoparticles, when the particle size is less than 200 nm, although the specific surface area is larger, the excessively high surface energy leads to easy aggregation, significantly increasing the difficulty of preparation and dispersion. When the particle size of modified copper nanoparticles is greater than 800 nm, the specific surface area is significantly reduced, the number of active sites exposed per unit mass is insufficient, and the antibacterial activity is significantly reduced. Furthermore, the larger size makes it difficult to uniformly embed into the sponge pore walls, making it prone to detachment from the sponge skeleton. Therefore, the embodiments of this application, by setting the particle size range of copper nanoparticles to 200 nm to 800 nm, achieve an optimized balance between performance and cost while ensuring excellent antibacterial performance, considering dispersion stability, process operability, and economy.

[0052] In one specific embodiment, the raw materials for the nano-copper composite sponge include 65%–66% polyurethane polyol, 25%–28% isocyanate, 1%–2% foaming agent, 0.1%–0.5% catalyst, and 0.1%–5% modified nano-copper.

[0053] The raw materials for the nano-copper composite sponge include polyurethane polyol, isocyanate, foaming agent, catalyst and modified nano-copper, wherein the mass percentage of polyurethane polyol is 65% to 66%, the mass percentage of isocyanate is 25% to 28%, the mass percentage of foaming agent is 1% to 2%, the mass percentage of catalyst is 0.1% to 0.5%, and the mass percentage of modified nano-copper is 0.1% to 5%.

[0054] Polyurethane polyols are the main skeletal material of sponges, providing them with softness, elasticity, and strength. Maintaining their content between 65% and 66% ensures the sponge substrate has a complete molecular network structure and excellent mechanical properties. If the polyurethane polyol content is below 65%, the cross-linked network of the sponge substrate is incomplete, resulting in insufficient strength and poor resilience. If the polyurethane polyol content is above 66%, the proportion of other functional components is reduced, affecting foaming performance and antibacterial properties.

[0055] Isocyanate is a cross-linking curing agent that reacts with polyols to form polyurethane macromolecules. Maintaining its content between 25% and 28% ensures a moderate cross-linking density, achieving a good balance between the sponge's hardness and resilience. If the isocyanate content is below 25%, the cross-linking reaction is insufficient, resulting in a soft sponge with poor shape retention and slow recovery after compression. If the isocyanate content is above 28%, over-cross-linking occurs, causing the sponge to become brittle, reduce resilience, and feel stiff.

[0056] Dichloromethane is the preferred foaming agent. When heated, it vaporizes and expands to form a porous structure and reduce the sponge's density. Controlling its content between 1% and 2% achieves suitable density and a uniform cell structure. Simultaneously, the vaporization of dichloromethane absorbs a large amount of heat, which helps lower the sponge's core temperature and prevents core burning. If the foaming agent content is below 1%, the foaming power is insufficient, the sponge density is too high, resilience is poor, and the feel is too hard. If the foaming agent content is above 2%, the cell walls are too thin, the sponge's tensile and tear strengths decrease significantly, and core temperature control becomes more difficult, increasing the risk of core burning.

[0057] The catalysts include gel catalysts and foaming catalysts. Stannous octoate is preferred as the gel catalyst, and triethylenediamine as the foaming catalyst. Controlling their total content between 0.1% and 0.5% ensures a moderate reaction rate, a wide process window, and easy production control. If the catalyst content is below 0.1%, the reaction rate is too slow, the milky whitening time and rise time are prolonged, and the foam collapses or cracks before it sets. If the catalyst content is above 0.5%, the reaction rate is too fast, the raw materials are unevenly mixed, and localized intense reactions lead to core burning.

[0058] In one specific embodiment, the nano-copper composite sponge further includes nano-titanium oxide, wherein the nano-titanium oxide accounts for 0.1% to 5% of the mass of the nano-copper composite sponge.

[0059] Nano-titanium oxide, used as a whitening agent and anti-yellowing agent, can effectively improve the whiteness of sponges, enhance appearance uniformity, and delay yellowing aging when added at a concentration of 0.1% to 5%. If the nano-titanium oxide content is below 0.1%, the whitening effect is not significant; if the content is above 5%, the cost increases significantly, and excessive inorganic content may affect the mechanical properties and cell structure of the sponge. Therefore, this embodiment optimizes the sponge raw material ratio, successfully introducing modified nano-copper and nano-titanium oxide functional components while ensuring the excellent mechanical properties of the sponge substrate, thus achieving a balance between functional characteristics and mechanical properties.

[0060] In one specific embodiment, the polyurethane polyol includes at least one of polyether polyol, polyester polyol, and polycarbonate polyol.

[0061] When the above-mentioned polyurethane polyols are selected, the flexible segments in the polyurethane polyol molecular chain can effectively transfer stress and give the sponge base resilience. At the same time, the active hydroxyl groups at the molecular ends react with isocyanates to form a cross-linked network, providing the material with the necessary mechanical support and structural stability.

[0062] In one specific embodiment, the isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate.

[0063] The highly reactive isocyanate groups (-NCO) in the molecular structure of isocyanates can undergo efficient addition reactions with the hydroxyl groups (-OH) of polyurethane polyols to form urethane bonds, thereby constructing the hard segment structure of polyurethane materials and providing the necessary mechanical strength, cohesion and resilience for shape memory foams.

[0064] In one specific embodiment, the foaming agent includes at least one of water, cyclopentane, and dichloromethane.

[0065] The aforementioned foaming agent generates gas in the polyurethane reaction system through physical volatilization or chemical reaction, and can control the matching of gas generation rate with polymer gelation speed to ensure that shape memory sponge forms an ideal foam morphology with a porous structure.

[0066] In one specific embodiment, the gel catalyst includes at least one of stannous octoate (T9), dibutyltin dilaurate, and bismuth isooctanoate.

[0067] Gel catalysts accelerate the polymerization rate between isocyanate groups and the hydroxyl groups of polyurethane polyols, thus dominating the growth and cross-linking process of polyurethane molecular chains. Stannous octoate, as a low-temperature active catalyst, can effectively promote the formation of prepolymers and initial gelation, controlling the time window of the gelation reaction to synchronize it with the foaming process, avoiding shrinkage due to excessively rapid reaction or collapse due to excessively slow reaction.

[0068] In one specific embodiment, the foaming catalyst includes at least one of triethylenediamine (A33), bis(dimethylaminoethyl) ether, and N-methylmorpholine.

[0069] Foaming catalysts accelerate the reaction rate between isocyanates and foaming agents, promoting the efficient generation of carbon dioxide gas and acting as the driving force for the expansion of sponge volume. Triethylenediamine, as a powerful balanced catalyst, can simultaneously promote foaming and gelation reactions, ensuring good cell opening.

[0070] In one specific embodiment, the raw materials for the nano-copper composite sponge also include a foam stabilizer, which includes at least one of silicone oil, polyether-modified polysiloxane, and fatty alcohol polyoxyethylene ether.

[0071] Foam stabilizers, by regulating the gas-liquid interfacial tension, endow the bubble film formed during the foaming process with sufficient mechanical strength and elasticity, and are key additives for maintaining the stability of the cell structure. Silicone oil, as a classic foam stabilizer, can significantly reduce the surface tension of the system, prevent bubbles from rupturing or merging during the expansion stage, and ultimately obtain a shape memory sponge with a uniform structure.

[0072] Corresponding to the aforementioned application function implementation method embodiments, this application also provides a method for preparing nano-copper composite sponge, its application, and corresponding embodiments.

[0073] This application also provides a method for preparing the aforementioned nano-copper composite sponge, comprising the following steps: Modified nano-copper is mixed with the raw materials of polyurethane foam substrate and foamed in situ. During the nucleation and growth of the foam cells, the modified nano-copper is embedded in the foam skeleton. At the same time, the copper hydroxyl groups in the shell of the modified nano-copper undergo nucleophilic addition reaction with the isocyanate groups to form covalently linked urethane bonds, so that the modified nano-copper is uniformly loaded in the polyurethane foam matrix.

[0074] In this embodiment, in-situ foaming refers to the modified copper nanoparticles participating in the reaction throughout the entire polyurethane foaming process, rather than being attached to the sponge surface after foaming through post-treatment methods such as spraying or impregnation. During the foaming process, the gas generated in the mixture forms bubbles, which continuously nucleate, grow, and merge, ultimately forming a three-dimensional interconnected porous structure. The modified copper nanoparticles are encapsulated and embedded in the forming cell walls during this process. As the polyurethane molecular chains cross-link and solidify, the copper nanoparticles are permanently fixed within the sponge skeleton. Simultaneously, the hydroxyl groups on the surface of the modified copper nanoparticle shell are nucleophilic, capable of attacking the carbon atoms in the isocyanate groups, undergoing a nucleophilic addition reaction to generate urethane bonds. These covalent bonds directly connect the copper nanoparticles to the polyurethane macromolecular chains, forming a strong chemical anchor.

[0075] Therefore, the preparation method of this application embodiment achieves permanent anchoring of modified nano-copper in the sponge matrix through the synergistic effect of in-situ foaming and chemical bonding, solving the defects of easy detachment of antibacterial components and insufficient long-term effect.

[0076] In one specific embodiment, the modified nano-copper is mixed with the raw materials of the polyurethane foam substrate for in-situ foaming, including the following steps: S1. Mix the modified nano-copper with polyurethane polyol and stir until uniform to form a mixture; S2. Add isocyanate, foaming agent and catalyst to the mixture for in-situ foaming.

[0077] The feeding sequence adopted in this application embodiment has significant technical implications. First, the modified copper nanoparticles are mixed with polyurethane polyol because the polyurethane polyol has suitable viscosity and polarity, which is beneficial for the dispersion of the copper nanoparticles. Under high-speed stirring conditions, the modified copper nanoparticles can be uniformly dispersed in the polyol system, forming a stable suspension. Simultaneously, the polyol molecular chain contains a large number of hydroxyl groups, which can form hydrogen bonds with the hydroxyl groups on the surface of the modified copper nanoparticle shell, further promoting the stable dispersion of the copper nanoparticles in the polyol.

[0078] After the modified copper nanoparticles are fully and uniformly dispersed in the polyol, isocyanate, foaming agent, and catalyst are added to initiate the foaming reaction. If the modified copper nanoparticles are mixed with isocyanate first, the hydroxyl groups on the surface of the copper nanoparticle shell will immediately react violently with the isocyanate groups, causing localized polymerization on the surface of the copper nanoparticles and forming agglomerates, thus preventing uniform distribution during subsequent foaming. Therefore, the order of adding the materials—"mixing with the polyol first, then with the isocyanate"—is a key process control point to ensure the uniform dispersion of modified copper nanoparticles in the sponge.

[0079] In summary, by optimizing the feeding sequence and dispersion conditions, the embodiments of this application ensure that the modified nano-copper is uniformly dispersed in the polyol system before the sponge foams, thus laying a good dispersion foundation for in-situ foaming and subsequent chemical bonding.

[0080] In one specific embodiment, the process conditions for in-situ foaming are as follows: Before mixing the mixture with the isocyanate, the temperature of the mixture and the isocyanate is 21℃~23℃.

[0081] Raw material temperature is the primary parameter for controlling the polyurethane foaming reaction rate. Maintaining the temperature of the polyurethane polyol mixture and isocyanate within the range of 21°C to 23°C ensures a suitable reaction rate. This avoids both excessively low temperatures leading to slow reactions and reduced production efficiency, and excessively high temperatures causing uncontrollable reactions. If the raw material temperature is below 21°C, the reaction rate decreases, the milky white time and rise time are prolonged, and the foam collapses or cracks before reaching sufficient strength. If the raw material temperature is above 23°C, the reaction rate is too fast, the mixing time is insufficient, the raw materials are not mixed evenly, and localized violent reactions lead to core burning.

[0082] The milky white color lasts for 8 to 10 seconds.

[0083] The milky white time refers to the time from the start of raw material mixing to the time when the mixture turns milky white. It reflects the initial speed of the foaming reaction. A milky white time of 8 to 10 seconds ensures that the raw materials are fully spread in the mold before foaming begins. If the milky white time is less than 8 seconds, foaming begins before the raw materials are evenly spread in the mold, resulting in uneven sponge density distribution and even local voids. If the milky white time is more than 10 seconds, production efficiency decreases, and uneven cell structure may result due to the late start of foaming.

[0084] The ascent time is 40 to 55 seconds.

[0085] Rise time refers to the time from the start of mixing to the stop of foam rising, reflecting the overall speed of the foaming reaction. A rise time of 40 to 55 seconds is conducive to the formation of a uniform and fine cell structure. If the rise time is less than 40 seconds, the foaming process is too vigorous, the cell walls are overstretched and thinned, and the sponge strength decreases; if the rise time is more than 55 seconds, the foaming power is insufficient, the sponge density is too high, and the resilience is poor.

[0086] The gelation time is 70–85 seconds.

[0087] Gel time refers to the time from the start of mixing to the beginning of solidification inside the foam, reflecting the speed of the cross-linking reaction. A gel time of 70 to 85 seconds allows the foam to set properly after rising to its highest point. If the gel time is less than 70 seconds, the foam begins to solidify before reaching its highest point, resulting in a high closed-cell rate and poor sponge resilience. If the gel time is more than 85 seconds, the foam will fail to set properly after stopping rising, leading to cell merging and collapse, and damage to the sponge structure.

[0088] The maximum core temperature during the foaming process of the sponge is controlled at 150-165℃.

[0089] The maximum core temperature is the highest temperature reached in the center of the sponge during the foaming process. This temperature is influenced by both the exothermic reaction and the endothermic reaction of the foaming agent. Controlling the maximum core temperature between 150℃ and 165℃ ensures a sufficient foaming reaction while preventing the core from burning due to excessive heat. If the maximum core temperature is below 150℃, the foaming reaction is incomplete, resulting in a higher sponge density and an undesirable cell structure. If the maximum core temperature exceeds 165℃, especially above 170℃, the center of the sponge will undergo overheating degradation, turning yellow and becoming brittle; in severe cases, the entire sponge may become unusable.

[0090] Therefore, this embodiment of the invention, by precisely controlling the foaming process parameters, achieves uniform dispersion and chemical bonding of modified nano-copper while ensuring the uniformity of the sponge's pore structure and the sponge's mechanical properties. It has a wide process window, good reproducibility, and is suitable for stable industrial production.

[0091] This application also provides an application of shape memory sponge, in which the aforementioned nano-copper composite sponge or the nano-copper composite sponge prepared by the aforementioned method is used in the fields of home cleaning, bedding filling, maternal and infant products, public health equipment and medical care consumables.

[0092] The nano-copper composite sponge of this application embodiment has excellent shape memory properties with a resilience of ≥95%, and can quickly recover its original shape after compression. It also has broad-spectrum antibacterial and antiviral functions, making it very suitable for application in the above-mentioned fields.

[0093] In the field of home cleaning, the sponge of this application embodiment can be made into products such as kitchen cleaning wipes, bathroom cleaning blocks, and multi-functional cleaning brushes. Its antibacterial and anti-mildew properties can effectively inhibit the growth of bacteria and mold on the cleaning tools themselves and avoid secondary pollution.

[0094] In the field of bedding filling, the sponge in the embodiments of this application can be used to make products such as pillows, mattresses, cushions, and backrests. Its antibacterial and anti-mite functions can provide users with a healthy sleep environment, especially for people with allergies and children, which play an important protective role.

[0095] In the field of maternal and infant products, the sponge in the embodiments of this application can be used to make products such as baby pillows, crawling mats, nursing pillows, and baby bath sponges. Its safe, non-toxic, and non-irritating properties meet the stringent safety standards for maternal and infant products, while its antibacterial function can effectively protect infants from germs.

[0096] In the field of public health equipment, the sponge in this application embodiment can be used for high-frequency contact items such as public seat cushions, fitness equipment handle wrapping materials, and medical waiting room chair cushions. Its antiviral function can reduce the risk of virus transmission through object surfaces, which is of great significance to public health safety.

[0097] In the field of medical and nursing consumables, the sponge in the embodiments of this application can be used in products such as medical dressings, nursing pads, wheelchair cushions, and operating room pressure ulcer prevention pads. Its antibacterial and antiviral functions meet the hygiene requirements of medical devices. At the same time, copper is an essential trace element for the human body and will not cause heavy metal poisoning or skin allergic reactions.

[0098] Therefore, applying the nano-copper composite sponge of this application to the above-mentioned multiple sensitive and high-standard fields can fully leverage its long-lasting, broad-spectrum, and safe antibacterial and antiviral functions, resulting in significant social and economic benefits.

[0099] To further understand the present invention, the following embodiments are provided to illustrate the present application. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0100] I. Example 1 (I) Preparation of modified nano-copper 1. Dissolve titanium tetrachloride in 10% dilute hydrochloric acid, controlling the volume ratio of titanium tetrachloride to dilute hydrochloric acid to be 1:4, to obtain a titanium tetrachloride hydrochloric acid solution; add metallic copper to the titanium tetrachloride hydrochloric acid solution to dissolve it, and then add 18% titanium trichloride solution to obtain solution A; wherein the ratio of titanium tetrachloride hydrochloric acid solution: metallic copper: titanium trichloride solution is 100 mL: 5 g: 20 mL.

[0101] 2. Dissolve the copper salt in double-distilled water to prepare solution B with a copper ion concentration of 0.1 mol / L.

[0102] 3. Add solution B to solution A and mix. Adjust the pH of the system to 4.5 and react at 50℃ for 17 h to obtain a reaction solution containing core-shell structured copper nanoparticles.

[0103] 4. Centrifuge the reaction solution at 3400 rpm for 10 min to separate and collect the nano-copper. Wash the nano-copper five times with anhydrous ethanol to obtain anhydrous ethanol dispersion.

[0104] TEM characterization revealed that the modified copper nanoparticles have a core-shell structure, with the core being elemental copper nanoparticles (particle size approximately 200 nm) and the shell being copper hydroxyl groups (containing -Cu-OH structures), with a shell thickness of approximately 15-20 nm.

[0105] Figure 1 This is a scanning electron microscope image of the modified copper nanoparticles from Example 1. Figure 1 The nano-copper powder showed a relatively uniform particle size distribution and did not form any hard, agglomerated particles.

[0106] (II) Preparation of nano-copper composite sponge Take 46 kg of polyether polyol and add 0.92 kg of the above-mentioned core-shell structure modified nano-copper, so that the modified nano-copper accounts for 1% of the total mass of the sponge. Do not add nano-titanium oxide. Stir the modified nano-copper and polyether polyol at high speed for 30 min until uniformly dispersed, and control the temperature of the mixture at 22℃.

[0107] Separately, 21 kg of isocyanate was taken and the temperature was controlled at 22℃. The above mixture and isocyanate were simultaneously added to 1350 g of silicone oil, 170 g of stannous octoate, 120 g of triethylenediamine, and 1000 g of dichloromethane. After rapid mixing, the mixture was poured into a mold for in-situ foaming. During foaming, the milky whitening time was 9 s, the rise time was 48 s, the gelation time was 78 s, and the maximum core temperature was controlled at 158℃. After foaming, the mixture was cured at 70℃ for 24 h, and after slicing, nano-copper composite sponge was obtained.

[0108] Figure 2 This is an EDS test image of the nano-copper composite sponge from Example 1. The EDS test results show that the surface of the sponge did not display the abundance of copper due to its content being lower than the detection limit. However, this also indirectly proves that: 1. The amount of nano-copper added to achieve antibacterial, antiviral, anti-mildew, and anti-mite effects is appropriate. 2. The copper elements are uniformly dispersed in the sponge without forming aggregates.

[0109] The preparation steps of Example 2 are as follows: The only difference from Example 1 is that the amount of modified nano-copper added is 0.092 kg, so that the nano-copper content is 0.1%. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0110] The preparation steps of Example 3 are as follows: The only difference from Example 1 is that the amount of modified nano-copper added is 4.6 kg, so that the nano-copper content is 5%. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0111] The preparation steps of Example 4 are as follows: The only difference from Example 1 is that the amount of modified nano-copper added is 0.046 kg, so that the nano-copper content is 0.05%. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0112] The preparation steps of Example 5 are as follows: The only difference from Example 1 is that the amount of modified nano-copper added is 6.44 kg, so that the nano-copper content is 7%. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0113] The preparation steps of Example 6 are as follows: The only difference from Example 1 is that the particle size of the modified nano-copper used is 500nm. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0114] The preparation steps of Example 7 are as follows: The only difference from Example 1 is that the particle size of the modified nano-copper used is 800nm. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0115] The preparation steps of Example 8 are as follows: The only difference from Example 1 is that the particle size of the modified nano-copper used is 100nm. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0116] The preparation steps of Example 9 are as follows: The only difference from Example 1 is that the particle size of the modified nano-copper used is 900 nm. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0117] The preparation steps of Example 10 are as follows: The only difference from Example 1 is that water is used for washing in step 4 of the preparation steps of modified nano-copper. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0118] The preparation steps of Example 11 are as follows: The only difference from Example 1 is that glycerol is used for washing in step 4 of the preparation steps of modified nano-copper. The rest of the formula, raw material source and process conditions are exactly the same as those of Example 1.

[0119] The preparation steps of Example 12 are as follows: The only difference from Example 1 is that 0.92 kg of nano titanium dioxide is added to make the nano titanium dioxide content 1%. The nano titanium dioxide and modified nano copper are simultaneously added to the polyether polyol for dispersion. The rest of the formulation, raw material source and process conditions are exactly the same as those of Example 1.

[0120] The preparation steps of Comparative Example 1 are as follows: The only difference from Example 1 is that step 4 is not included in the preparation steps of modified nano-copper.

[0121] The preparation steps of Comparative Example 2 are as follows: The only difference from Example 1 is that steps 1 to 3 in the preparation steps of modified copper nanoparticles are different; the rest of the formulation, raw material sources, and process conditions are exactly the same as in Example 1. Specifically: Step 1: Dissolve the copper precursor (such as copper acetylacetonate or copper nitrate) in an organic solvent to prepare a copper sol precursor solution of a certain concentration. Step 2: Form a copper sol through hydrolysis or complexation reaction, controlling the reaction conditions to prevent the sol from further forming a complex gel, and directly obtain a sol system containing copper nanoparticles. Step 3: Centrifuge the copper sol obtained in Step 2 at high speed to separate and collect the copper nanoparticles, and obtain copper nanoparticle powder with an average particle size of about 10 nm after washing and drying. Step 4: Wash and disperse the obtained copper nanoparticle powder with anhydrous ethanol to obtain an anhydrous ethanol dispersion of copper nanoparticles.

[0122] The preparation steps of Comparative Example 3 are as follows: The only difference from Example 1 is that polyvinyl alcohol sponge is used instead of polyurethane sponge as the substrate. Specifically, core-shell structured modified copper nanoparticles are prepared according to the method of Example 1. Then, the copper nanoparticles are loaded onto the polyvinyl alcohol sponge substrate by impregnation, and the sample is obtained after drying. Since the polyvinyl alcohol sponge does not contain urethane bonds, it cannot undergo nucleophilic addition reactions; the copper nanoparticles are only physically attached to the sponge surface.

[0123] The preparation steps of Comparative Example 4 are as follows: The only difference from Example 1 is that a non-in-situ foaming process is used instead of an in-situ foaming process. Specifically, a blank polyurethane sponge is prepared according to the formulation of Example 1 but without the addition of modified nano-copper. Then, the blank sponge is immersed in an ethanol dispersion of core-shell structured modified nano-copper, and after drying, the sample is obtained. In this process, the nano-copper is not embedded during the sponge foaming process; it only adheres to the surface of the sponge.

[0124] The preparation steps of Comparative Example 5 are as follows: the only difference from Example 1 is the reverse order of addition. Specifically, the core-shell modified nano-copper (0.92 kg) and isocyanate (21 kg) were first mixed. After stirring, a violent reaction occurred immediately, the viscosity of the mixture increased sharply, and obvious agglomeration and precipitation occurred. Then, polyether polyol (46 kg), silicone oil (1350 g), stannous octoate (170 g), triethylenediamine (120 g), and dichloromethane (1000 g) were added for in-situ foaming. The sources of other raw materials and process conditions were exactly the same as in Example 1.

[0125] The formulations and preparation processes for each embodiment and comparative example are shown in Table 1.

[0126] Table 1 Formulation and Preparation Process

[0127] II. Performance Testing The sponge samples prepared in each embodiment and comparative example were subjected to the following performance tests, and the test results are shown in Table 2.

[0128] 1. Antibacterial performance testing was conducted according to GB / T20944.3-2008 standard. Staphylococcus aureus and Escherichia coli were used as test bacteria. Sponge samples were cut into 5cm diameter discs and placed in the bacterial suspension for 24 hours of contact incubation. The inhibition rate was then calculated. The inhibition rate was calculated as follows: Inhibition rate = (Control sample viable count minus test sample viable count) / Control sample viable count multiplied by 100%. Three parallel samples were tested for each sample, and the average value was taken as the final result. The initial inhibition rate refers to the test result of the freshly prepared sponge sample. The inhibition rate after 50 washes refers to the result after the sponge sample has been repeatedly washed 50 times under standard washing conditions and dried before testing.

[0129] 2. Antiviral performance testing was conducted according to ISO 18184 standard. Influenza virus H1N1 was selected as the test virus. After the sponge sample was contacted with the virus suspension for a certain period, the reduction in virus titer was measured, and the antiviral rate was calculated. The antiviral rate was calculated as follows: Antiviral rate = (Control sample virus titer minus test sample virus titer) / (Control sample virus titer) multiplied by 100%. Three parallel samples were tested for each sample, and the average value was taken as the final result.

[0130] 3. Anti-mold performance testing was conducted according to GB / T24128 standard. Sponge samples were inoculated with a mixed mold spore suspension and cultured for 28 days at 28℃ and relative humidity above 85%, observing mold growth. Anti-mold levels were divided into grades 0 to 4, where grade 0 indicates no mold growth under a microscope, grade 1 indicates mold growth area less than 10%, grade 2 indicates mold growth area of ​​10% to 30%, grade 3 indicates mold growth area of ​​30% to 60%, and grade 4 indicates mold growth area greater than 60%.

[0131] 4. The mite-inhibiting performance test was conducted according to GB / T24253 standard. After the sponge sample was in contact with a certain number of dust mites for a specified period, the mite mortality rate was measured, and the mite-inhibiting rate was calculated. Three parallel samples were tested for each sample, and the average value was taken as the final result.

[0132] 5. The sponge's appearance and mechanical properties testing includes the following items: Observing the sponge's pore structure and the uniformity of the dispersion of nano-copper using a scanning electron microscope, noting the presence and size of agglomerates; testing the sponge's resilience according to GB / T6669 standard; and testing the sponge's tensile strength according to GB / T6344 standard. For samples with added nano-titanium oxide, the whiteness value is tested according to GB / T3979 standard.

[0133] Table 2 Test Results

[0134] III. Analysis of Experimental Results The test results above reveal the necessity of each technical feature of this application and the rationality of the parameter range.

[0135] From the perspective of core-shell structure, Example 1 showed an initial antibacterial rate of 99.9%, which remained at 99.5% after 50 washes. In contrast, Comparative Example 1, using ordinary nano-copper without a core-shell structure, had an initial antibacterial rate of only 98.5%. Furthermore, SEM images showed that the unprotected nano-copper aggregated severely in the sponge (10-20 μm), and after 50 washes, the antibacterial rate dropped to 85.2%, the antiviral rate was only 45%, the antifungal level was 1, and the mite inhibition rate was only 45%. This indicates that nano-copper without a core-shell structure cannot resist oxidation, and its antibacterial properties are unstable and easily degraded.

[0136] From the perspective of hydroxyl groups and chemical bonding, the surface-active hydroxyl groups of the copper nanoparticles (average particle size 10 nm) prepared by the sol-gel method in Comparative Example 2 were largely lost during heat treatment. Although the initial antibacterial rate reached 99.0%, the antibacterial rate dropped to 87.5% after 50 washes due to the inability to form effective chemical bonds with the polyurethane substrate, which was significantly lower than the 99.5% in Example 1. This proves that hydroxyl groups are the key functional groups for achieving permanent anchoring.

[0137] Regarding the choice of sponge substrate, Comparative Example 3 used polyvinyl alcohol (PVA) sponge instead of polyurethane sponge. Since PVA does not contain urethane bonds, it cannot undergo nucleophilic addition reactions. SEM images showed that the nano-copper only adhered to the surface of the PVA sponge. After washing, a large amount of the nano-copper detached. After 50 washes, the antibacterial rate dropped to 75.6%, the antiviral rate was only 40%, the antifungal level was 2, and the mite inhibition rate was only 35%. This demonstrates that the polyurethane substrate and its urethane bonds are the basis for achieving chemical bonding.

[0138] Regarding the choice of hydroxyl-containing solvents, Example 10 used water for washing, resulting in fewer surface hydroxyl groups remaining and slightly lower performance than Example 1. Example 11 used glycerol for washing; the high viscosity of glycerol increased the steric hindrance of the surface hydroxyl groups, which was unfavorable for subsequent reactions with isocyanate, leading to partial aggregation and relatively poor performance. Comparative Example 4 used modified copper nanoparticles with hydroxyl groups but without a hydrated titanium dioxide shell, achieving an initial antibacterial rate of 98.8%, slightly lower than the 99.9% of Example 1. SEM images showed that the copper nanoparticles partially aggregated in the sponge, and after 50 washes, the antibacterial rate dropped to 82.5%, far lower than the 99.5% of Example 1. This demonstrates that the dense shell composed of inorganic coordinating ions plays an irreplaceable role in protecting the copper nanoparticle core and achieving stable bonding with the polyurethane substrate.

[0139] From the perspective of the range of nano-copper content, in Example 2, when the nano-copper content was 0.1%, the initial antibacterial rate was 99.2%, meeting the usage requirements. In Example 4, when the nano-copper content was 0.05%, the initial antibacterial rate dropped to 92.3%, lower than the target value of 99%, and the antiviral rate was only 82%, the antifungal grade was level 1, and the mite inhibition rate was only 68%. In Example 3, when the nano-copper content was 5%, the performance was excellent. In Example 5, when the nano-copper content was 7%, although the antibacterial rate reached 99.99%, the SEM image showed obvious agglomerates of nano-copper (1-3 μm), and the tensile strength decreased from 128 kPa to 98 kPa. The above results prove that the nano-copper content of 0.1% to 5% is a reasonable range.

[0140] From the perspective of the range of copper nanoparticle size, the sponges with a particle size of 200 nm in Example 1, 500 nm in Example 6, and 800 nm in Example 7 all exhibited excellent comprehensive performance. In Example 8, with a particle size of 100 nm, SEM images showed that it formed large aggregates of 5-10 μm in the sponge, with poor dispersion uniformity; after 50 washes, the antibacterial rate decreased to 85.2%. In Example 9, with a particle size of 900 nm, SEM images showed that the spacing between the copper nanoparticles was large, resulting in insufficient quantity per unit area; the initial antibacterial rate decreased to 97.8%, below 99%. These results demonstrate that a copper nanoparticle size range of 200 nm to 800 nm is reasonable.

[0141] From the perspective of the preparation process, Example 1 used a preferred feeding sequence (first mixing with polyol, then mixing with isocyanate) for in-situ foaming. SEM images showed that the nano-copper was uniformly distributed inside the foam pores of the sponge, and the antibacterial rate remained at 99.5% after 50 washes. Comparative Example 4 used a non-in-situ foaming post-treatment impregnation process. SEM images showed that the nano-copper only adhered to the outer surface of the sponge. After 50 washes, the antibacterial rate dropped sharply from 99.5% to 52.1%, the anti-mildew level was 2, and the mite inhibition rate was only 55%, proving that non-in-situ foaming cannot achieve permanent fixation of nano-copper. Comparative Example 5 used the reverse feeding sequence (mixing with isocyanate first, then with polyol). Due to the high reactivity of the hydroxyl groups on the surface of the modified copper nanoshell, a nucleophilic addition reaction immediately occurred upon contact with the isocyanate groups, leading to localized polymerization on the surface of the copper nanoshell. SEM images showed that the copper nanoshell formed large agglomerates of 15-30 μm in the sponge, with extremely uneven distribution. The initial antibacterial rate dropped to 96.5%, and after 50 washes, it further decreased to 80.3%. The tensile strength was only 85 kPa, and the resilience dropped to 82%. These results demonstrate that the in-situ foaming process is the key to achieving permanent fixation of copper nanoshells, and the feeding sequence is crucial. It is essential to first mix and disperse the copper nanoshells evenly with the polyol before mixing them with the isocyanate for the foaming reaction. Otherwise, the copper nanoshells will undergo surface polymerization and agglomeration upon premature contact with the isocyanate, failing to achieve uniform dispersion and effective anchoring.

[0142] From the effect of adding nano-titanium oxide, after adding 1% nano-titanium oxide in Example 12, the SEM image showed that the nano-copper was evenly dispersed, and the antibacterial performance was not affected.

[0143] Although this application has been described with reference to preferred embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for the elements, as long as they do not depart from the scope of this application. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this application, as long as they do not depart from the essential scope of this application. Therefore, this application is not intended to be limited to the specific embodiments disclosed as the best mode of carrying out this application as conceived, but rather this application will include all embodiments falling within the scope of the appended claims.

[0144] All scopes disclosed in this application include endpoints, and endpoints can be combined with each other.

[0145] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A nano-copper composite sponge, characterized in that, The invention comprises a polyurethane foam substrate and modified copper nanoparticles; the modified copper nanoparticles have a core-shell structure, the core being elemental copper nanoparticles, and the shell containing copper hydroxyl groups bonded to the surface of the elemental copper nanoparticles; the copper hydroxyl groups in the shell undergo a nucleophilic addition reaction with the isocyanate groups in the polyurethane foam substrate to form covalently linked urethane bonds, thereby uniformly loading the modified copper nanoparticles into the polyurethane foam matrix.

2. The nano-copper composite sponge according to claim 1, characterized in that, The copper hydroxyl groups in the shell are formed by the nano-copper element coming into contact with a hydroxyl-containing solvent during the centrifugal washing and dispersion process.

3. The nano-copper composite sponge according to claim 2, characterized in that, The hydroxyl-containing solvent includes water, ethanol, or a combination thereof.

4. The nano-copper composite sponge according to claim 1, characterized in that, The nano-copper is obtained by reducing copper salt in an aqueous phase in a reduction system composed of titanium tetrachloride and titanium trichloride; and / or, the modified nano-copper accounts for 0.1% to 5% of the mass percentage of the nano-copper composite sponge; and / or, the particle size of the modified nano-copper is 200 nm to 800 nm.

5. The nano-copper composite sponge according to claim 1, characterized in that, The raw materials of the nano-copper composite sponge include 65% to 66% polyurethane polyol, 25% to 28% isocyanate, 1% to 2% foaming agent, 0.1% to 0.5% catalyst and 0.1% to 5% modified nano-copper; and / or, the nano-copper composite sponge also includes nano-titanium oxide, wherein the nano-titanium oxide accounts for 0.1% to 5% of the mass percentage of the nano-copper composite sponge.

6. The nano-copper composite sponge according to claim 5, characterized in that, The polyurethane polyol includes at least one of polyether polyol, polyester polyol, and polycarbonate polyol; and / or, The isocyanate includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate; and / or The foaming agent includes at least one of water, cyclopentane, and dichloromethane; and / or, The catalyst includes a foaming catalyst and a gel catalyst. Preferably, the gel catalyst includes at least one of stannous octoate (T9), dibutyltin dilaurate, and bismuth isooctanoate; and / or, the foaming catalyst includes at least one of triethylenediamine (A33), bis(dimethylaminoethyl) ether, and N-methylmorpholine.

7. A method for preparing a nano-copper composite sponge as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Modified nano-copper is mixed with the raw materials of polyurethane foam substrate and foamed in situ. During the nucleation and growth of the foam cells, the modified nano-copper is embedded in the foam skeleton. At the same time, the copper hydroxyl groups in the shell of the modified nano-copper undergo nucleophilic addition reaction with the isocyanate groups to form covalently linked urethane bonds, so that the modified nano-copper is uniformly loaded in the polyurethane foam matrix.

8. The preparation method according to claim 7, characterized in that, The process of mixing modified nano-copper with polyurethane foam substrate for in-situ foaming includes the following steps: Modified nano-copper is mixed with polyurethane polyol and stirred evenly to form a mixture; Isocyanate, foaming agent, and catalyst are added to the mixture for in-situ foaming.

9. The preparation method according to claim 8, characterized in that, The process conditions for the in-situ foaming are as follows: Before the mixture is mixed with the isocyanate, the temperature of the mixture and the isocyanate is 21°C to 23°C; and / or, the milky whitening time is 8 to 10 seconds; and / or, the rise time is 40 to 55 seconds; and / or, the gel time is 70 to 85 seconds; and / or, the maximum core temperature during the sponge foaming process is controlled at 150 to 165°C.

10. An application of a nano-copper composite sponge, characterized in that, The nano-copper composite sponge prepared by the preparation method of any one of claims 1 to 6 or any one of claims 7 to 9 can be used in the fields of household cleaning, bedding filling, maternal and infant products, public health equipment and medical care consumables.

Images