Non-overflow type antibacterial medical polyurethane and preparation method and application thereof

Abstract

This invention provides a non-overflow antibacterial medical polyurethane, its preparation method, and its application, relating to the technical field of medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B; stock solution A includes a hydrophilic chain extender, a surfactant, an antibacterial agent, a stabilizer, a structural reinforcing agent, a lubricant, and water; stock solution B includes an isocyanate prepolymer; wherein the antibacterial agent is a guanidine salt antibacterial agent, and the antibacterial agent is chemically bonded to the three-dimensional network structure of the non-overflow antibacterial medical polyurethane. The antibacterial agent of this invention can remain stably present within the foam for a long period, and is not easily migrated, leached, or rapidly released during use, thereby providing continuous and safe contact antibacterial action, while avoiding the decrease in efficacy or potential environmental toxicity caused by the loss of antibacterial components.

Description

Technical Field

[0001] This invention relates to the field of medical polyurethane foam technology, and in particular to a non-overflowing antibacterial medical polyurethane, its preparation method, and its application. Background Technology

[0002] Medical polyurethane foam, due to its excellent biocompatibility, high porosity, good air permeability, and liquid absorption properties, has become an important material in modern wound care, widely used in clinical scenarios such as acute and chronic wound management, postoperative wound protection, and pressure ulcer prevention. However, traditional medical polyurethane foam itself lacks antibacterial properties, making it susceptible to bacterial colonization and infection in the moist, nutrient-rich wound environment, leading to delayed wound healing, odor, and even systemic infection. To address this issue, antibacterial medical polyurethane foam has emerged. By introducing antibacterial active ingredients, it endows the material with the ability to kill or inhibit pathogenic microorganisms, thereby effectively controlling bacterial load while absorbing exudate and providing a protective microenvironment for wound healing.

[0003] Currently, antibacterial medical polyurethane foams are mainly of the overflow type. The main disadvantage of overflow-type antibacterial foams is that their antibacterial components are loaded into the polyurethane matrix through physical blending, relying on free migration and release to exert their effects. This results in a significant burst-release effect, with excessively high initial release followed by rapid attenuation, leading to poor antibacterial durability. More seriously, a large amount of free antibacterial components continuously seep into the wound and surrounding tissues, causing significant cytotoxicity. Experimental data shows low cell survival rates, far below biosafety standards. Furthermore, leaching experiments indicate that overflow-type foams can release large amounts of antibacterial components in a short time, not only causing rapid loss of efficacy but also potentially leading to environmental pollution and increased risk of bacterial resistance, severely limiting their clinical application.

[0004] For example, CN108355162A discloses an antibacterial hydrophilic polyurethane foam medical dressing, which is prepared by mixing and foaming component A and component B in a mass ratio of 0.5:1 to 3:1. Component A is an isocyanate-terminated hydrophilic prepolymer, and component B is a functional foam mixture composed of 1% to 10% surfactant, 0.9% to 10% foam stabilizer, and 0.1% to 10% cationic polymer antibacterial agent with 70% to 98% water. This dressing uses a physical blending method to disperse the cationic polymer antibacterial agent (such as polyhexamethylene biguanide hydrochloride) in the polyurethane prepolymer, which is a typical spill-type antibacterial technology route. This is because the antibacterial agent does not form a chemical bond with the matrix, making it easy to migrate and leach out, resulting in poor antibacterial durability and burst release effect; continuous leakage of free antibacterial components may cause cytotoxicity risks, as well as drug efficacy loss and potential environmental pollution, and its biosafety is not as good as that of chemical grafting non-spill-out technology.

[0005] In contrast, non-overflow antibacterial foams utilize chemical grafting technology to firmly bond antibacterial agents to the three-dimensional network structure of polyurethane via covalent bonds. This ensures that the antibacterial active ingredients remain stably within the material and are not easily migrated, leached, or rapidly released. However, the grafting process for non-overflow antibacterial foams mainly suffers from problems such as unstable grafting efficiency, low grafting rate, and stringent control of reaction conditions. For example, due to the difference in reactivity between the antibacterial agent and isocyanate, incomplete grafting or excessive cross-linking can easily occur, leading to uneven foam pore size and decreased mechanical properties. Furthermore, high-temperature reaction conditions increase side reactions, easily causing gelation or phase separation, affecting batch consistency and long-term antibacterial efficacy.

[0006] For example, CN119656361A discloses a hydrophilic antibacterial dressing and its preparation method. This hydrophilic antibacterial dressing is prepared by mixing and foaming an isocyanate-terminated antibacterial hydrophilic prepolymer and a functional foaming mixture. The isocyanate-terminated antibacterial hydrophilic prepolymer is made from the following raw materials in parts by weight: 10-100 parts of polyol I, 1-20 parts of cationic polymer, 10-40 parts of isocyanate, 0.1-5 parts of chain extender, and 0.3-7 parts of antioxidant. The functional foaming mixture is made from the following raw materials in parts by weight: 1-50 parts of polyol II, 1-20 parts of hydrophilic surfactant, 1-20 parts of foam stabilizer, and 1-100 parts of purified water. This hydrophilic antibacterial dressing is prepared by grafting antibacterial groups of a cationic polymer onto polyurethane segments to form a polyurethane prepolymer, and finally producing a polyurethane foam dressing. This dressing may have competitive reactions between polyol I and the cationic polymer, limiting the grafting efficiency and resulting in a high risk of unreacted antibacterial agent residue. The prepolymer has poor storage stability and is prone to gelation. During the foaming process, it is difficult to match the viscosity of the prepolymer with the foaming rate, resulting in low pore size control precision and large batch-to-batch fluctuations in the mechanical properties and antibacterial durability of the product.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a non-overflow antibacterial medical polyurethane, its preparation method, and its application. This invention aims to solve key technical problems in the existing preparation process of non-overflow antibacterial medical polyurethane foam, addressing issues such as excessively high reactivity, high system viscosity, poor storage stability, limited grafting efficiency, and low grafting rate associated with the prepolymer grafting method, as well as defects that easily occur during foaming, such as gelation, phase separation, uneven pore size, and decreased mechanical properties.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a non-overflow antibacterial medical polyurethane, wherein the raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B; The stock solution A comprises a hydrophilic chain extender, a surfactant, an antibacterial agent, a stabilizer, a structure enhancer, a lubricant, and water; wherein the antibacterial agent is a guanidine salt antibacterial agent. The original solution B includes an isocyanate prepolymer.

[0010] Further, the hydrophilic chain extender includes any one or a combination of at least two of the following: polypropylene oxide glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated poly(dibutylene), hydroxyl-terminated hydrogenated poly(dibutylene), hydroxyl-terminated poly(dibutylene-acrylonitrile), polyethylene oxide triol, propylene oxide-ethylene oxide co-ether triol, polycaprolactone triol, pentaerythritol polyether polyol, diaminopolyether tetraol, polyether pentaol, polyether hexaol, polystyrene polyol, castor oil and its castor oil derivatives polyol, soybean oil polyol, palm oil polyol, and rosin ester polyol.

[0011] Furthermore, the hydrophilic chain extender is any one or a combination of at least two of the following: polypropylene glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated polybutene-acrylonitrile, polyethylene oxide triol, propylene oxide-ethylene oxide copolyether triol, and polycaprolactone triol.

[0012] Furthermore, the number average molecular weight of the hydrophilic chain extender is 200 to 20,000.

[0013] Furthermore, the surfactant comprises any one or a combination of at least two of the following: polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol ether, propylene glycol block polyether, oleyl alcohol polyoxyethylene ether, polyethylene glycol, fatty acid polyoxyethylene ester, stearyl sorbitan, Tween, and triglyceride.

[0014] Furthermore, the guanidine salt antibacterial agent includes any one or a combination of at least two of polyhexamethylene biguanide hydrochloride, polyhexamethylene monoguanide hydrochloride, guanidine hydrochloride, chlorhexidine gluconate, chlorhexidine acetate, and chlorhexidine hydrochloride.

[0015] Furthermore, the stabilizer is a reaction system regulator.

[0016] Furthermore, the stabilizer is a reaction system regulator used to limit the reaction system to a process window; wherein the process window is characterized by the following parameters: the conductivity of the solution system is 5~30 mS / cm; the exothermic peak temperature of the reaction is 30~50℃.

[0017] Furthermore, the reaction system regulator includes electrolyte compounds and / or molecular compounds.

[0018] Furthermore, the electrolyte compound includes any one or a combination of at least two of sodium citrate, sodium lactate, sodium bicarbonate, sodium hydroxide, and sodium acetate.

[0019] Further, the molecular compound includes any one or a combination of at least two of 2-amino-2-methyl-1-propanol, triethanolamine, arginine, 1,3-propanediamine ethylenediamine, triethylamine, trimethylamine, choline, tromethamine, ethanolamine, dimethylaminoethanol, and triisopropanolamine.

[0020] Furthermore, the structural reinforcing agent includes any one or a combination of at least two of the following: light calcium carbonate, heavy calcium carbonate, silica powder, sodium silicate, borax, and kaolin.

[0021] Further, the lubricant comprises any one or a combination of at least two of the following: methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, calcium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, casein, calcium alginate, sodium alginate, gelatin, pectin, xanthan gum, carrageenan, xanthan gum, guar gum, gum arabic, hyaluronic acid, sodium hyaluronate, ceramide, nicotinamide, chitosan, and starch.

[0022] Furthermore, the isocyanate prepolymer is generated by reacting an alcohol monomer with a diisocyanate monomer; The alcohol monomer comprises polyether polyols and / or polyester polyols; the diisocyanate monomer comprises any one or a combination of at least two of the following: toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, dimethylbiphenyl diisocyanate, polymethylene polyphenyl isocyanate, 1,6-hexamethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenylenediamine diisocyanate, tetramethyl-isophthalimethylene diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, cyclohexanedimethylene diisocyanate, and norbornene diisocyanate.

[0023] Furthermore, the alcohol monomer is a polyether polyol.

[0024] Furthermore, the polyether polyol includes any one or a combination of at least two of polyoxypropylene polyol, sorbitol-based polyether polyol, sucrose-based polyether polyol, trimethylolpropane polyether polyol, and glycerol-based polyether polyol.

[0025] Furthermore, the content of -NCO in the isocyanate prepolymer is 6-8%.

[0026] Furthermore, the mass ratio of the alcohol monomer to the diisocyanate monomer is (5~6):(4~5).

[0027] Further, the stock solution A comprises, by weight, 1-20 parts of hydrophilic chain extender, 1-10 parts of surfactant, 0.1-2 parts of antibacterial agent, 0.1-2 parts of stabilizer, 0.1-1 parts of structural reinforcing agent, 1-10 parts of lubricant, and 50-99 parts of water.

[0028] Furthermore, the stock solution B comprises, by weight, 50 to 200 parts of isocyanate prepolymer.

[0029] In a second aspect, the present invention provides a method for preparing a non-overflowing antibacterial medical polyurethane as described in the first aspect, the method comprising: Hydrophilic chain extender, surfactant, antibacterial agent, stabilizer, structure enhancer, lubricant and water are mixed to prepare stock solution A; isocyanate prepolymer is used as stock solution B; Mix stock solution A and stock solution B, and then stir to obtain a mixture; The mixture is poured onto release paper and then coated by rollers to obtain a mixture wrapped in release paper. The mixture wrapped in the release paper is dried to obtain the non-overflowing antibacterial medical polyurethane.

[0030] Furthermore, the stirring temperature is 20~30℃, the stirring speed is 4000~5000rpm, and the stirring time is 2~4s.

[0031] Furthermore, during the roller coating process, the moving speed of the coating roller is 1~10 m / min; the coating thickness is 1~10 mm.

[0032] Furthermore, the drying temperature is 120~200℃.

[0033] Thirdly, the present invention provides the use of the non-overflowing antimicrobial medical polyurethane as described in the first aspect in the preparation of products for acute and chronic wound management and / or pressure ulcer prevention and treatment.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) Durable and stable antibacterial performance: This invention achieves efficient chemical bonding between the antibacterial agent and the polyurethane matrix through the synergistic effect of stabilizers and structural reinforcing agents, forming a truly non-overflow antibacterial structure. Compared with the problems of unstable grafting efficiency and uneven distribution of antibacterial agents in the prepolymer grafting method of the prior art, this invention adopts an in-situ grafting strategy, which, under mild and controllable reaction conditions, allows guanidine salt antibacterial agents to be firmly anchored in the three-dimensional polyurethane network through covalent bonds. The results of contact antibacterial test show that the foam dressing prepared by this invention has an antibacterial rate of more than 99.99% against Escherichia coli, Staphylococcus aureus and Candida albicans, and no obvious inhibition zone was observed in the inhibition zone test, confirming its non-overflow characteristics. More importantly, after soaking in purified water at 37°C for 72 h and 108 h, no PHMB release was detected in the extract, and the antibacterial active ingredients are completely retained in the material body and will not be lost due to body fluid rinsing, thus providing continuous and stable contact antibacterial protection, significantly extending the service life and antibacterial effectiveness of the material.

[0035] (2) Excellent biocompatibility and reduced risk of drug resistance: The non-overflow antibacterial mechanism of this invention fundamentally solves the biocompatibility risks associated with overflow antibacterial foam. Because the antibacterial agent is firmly fixed in the polyurethane matrix through chemical bonding rather than existing in a free state, the risk of antibacterial components migrating and penetrating into the wound and surrounding skin is greatly reduced. The MTT cytotoxicity test, conducted according to ISO 10993-5, showed that the cell survival rate of the foam of this invention was greater than 70%, indicating that the cytotoxicity was acceptable and at the same safety level as the blank foam. In contrast, the cell survival rate of the overflow antibacterial foam was less than 30%, indicating that the cytotoxicity was unacceptable. This significant difference fully demonstrates the advantages of this invention in terms of biocompatibility. Furthermore, the non-overflow characteristic avoids the pressure of long-term bacterial exposure to sublethal concentrations of antibacterial agents, significantly reducing the risk of screening and inducing drug-resistant strains. Simultaneously, the zero-release characteristic completely eliminates the pathway for antibacterial components to enter environmental water or soil with wound exudate, avoiding potential toxicity to the ecosystem. This reduces drug waste and the risk of secondary environmental pollution, meeting the dual requirements of safety and sustainability in modern wound care.

[0036] (3) Uniform product structure and excellent physical and mechanical properties: This invention effectively solves the common structural defects in the preparation of non-overflow antibacterial foam by optimizing the formula design and process parameters; the stabilizer precisely controls the dynamic ion balance of the reaction system, effectively suppresses the side reaction of isocyanate and water and premature gelation, so that the foaming process is stable and controllable, the bubble nucleation and growth stages proceed in an orderly manner, and avoids pore wall defects caused by local stress concentration; the structural reinforcement agent is uniformly dispersed in the liquid phase, and acts as a nucleation site and physical support skeleton in the foaming process, enhancing the rigidity and compressive strength of the bubble wall, and preventing bubble merging, collapse or shrinkage. Thus, through the synergy of these two factors, the foam produced by this invention has a uniform open-cell structure with a consistent pore size distribution, maintaining the same microstructure as the blank foam. This uniform porous structure endows the material with excellent physical and mechanical properties, including high porosity, high air permeability, and good softness. The foam can absorb up to 8 times its own weight in wound exudate while maintaining a moist healing environment and preventing maceration of the surrounding skin. The material can conform to the contours of irregular wounds, providing cushioning protection and dispersing pressure. Even after absorbing a large amount of exudate, it maintains structural integrity, facilitating complete removal and reducing patient pain and secondary injury. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of roller coating provided in an embodiment of the present invention; Among them, 1 is the coating roller; 2 is the foaming liquid; 3 is the release paper; and 4 is the water platform.

[0039] Figure 2 A comparison chart of the inhibition zone test results provided for Test Example 1.

[0040] Figure 3 Infrared spectra of different samples provided for test example 3.

[0041] Figure 4 This is the PHMB standard curve.

[0042] Figure 5 The image shows the SEM test results of the non-overflow antibacterial foam provided in Example 1.

[0043] Figure 6 The image shows the SEM test results of the foam provided for Comparative Example 1. Detailed Implementation

[0044] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0046] In a first aspect, the present invention provides a non-overflow antibacterial medical polyurethane, wherein the raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B; The stock solution A includes a hydrophilic chain extender, a surfactant, an antibacterial agent, a stabilizer, a structure enhancer, a lubricant, and water; wherein the antibacterial agent is a guanidine salt antibacterial agent; the stock solution B includes an isocyanate prepolymer.

[0047] The antibacterial agent is a guanidine salt antibacterial agent, and the antibacterial agent is chemically bonded to the three-dimensional network structure of the non-overflow antibacterial medical polyurethane.

[0048] It should be noted that the non-overflow antibacterial medical polyurethane foam of this invention is a functionalized material formed by chemically grafting guanidine salt antibacterial agents into the three-dimensional network structure of medical polyurethane foam. The antibacterial groups of the guanidine salt antibacterial agents form stable covalent bonds with the polyurethane molecular chains. Therefore, the antibacterial active ingredients can remain stably present in the foam matrix for a long time, and are not prone to migration, leaching, or rapid release during use, exhibiting a "non-overflow" characteristic. This characteristic allows the material to continuously exert its antibacterial effect through a contact killing mechanism, avoiding efficacy attenuation due to the loss of antibacterial components, while significantly reducing potential irritation to wounds and the risk of secondary environmental pollution. It combines long-lasting antibacterial efficacy with excellent biocompatibility, making it suitable for medical scenarios such as acute and chronic wound management, postoperative wound protection, and pressure ulcer prevention.

[0049] It should be noted that the guanidine salt antibacterial agent contains at least one guanidine functional group in its molecule. The reaction formula for the guanidine salt antibacterial agent being chemically bonded to the three-dimensional network structure of the non-overflow antibacterial medical polyurethane is shown below: .

[0050] As an optional implementation, taking polyhexamethylene biguanide hydrochloride (PHMB) as an example, the reaction formula in which PHMB is chemically bonded to the three-dimensional network structure of the non-overflowing antibacterial medical polyurethane is as follows: .

[0051] It should be noted that the non-overflow antibacterial medical polyurethane component system of this invention constructs a three-in-one non-overflow antibacterial system through multi-component synergy: chemical bonding, network locking, and structural reinforcement. Specifically, the hydrophilic chain extender reacts with the isocyanate prepolymer to form a three-dimensional polyurethane network framework, providing a stable anchoring carrier for the antibacterial agent. Under stabilizer-controlled process conditions, the antibacterial agent undergoes chemical grafting with isocyanate groups, allowing the antibacterial component to be firmly embedded in the network structure via covalent bonds rather than simple physical doping. The structural reinforcement agent acts as a crosslinking node to enhance network density, further restricting antibacterial agent migration. The surfactant regulates the uniformity of the foam structure, and the lubricant improves processing fluidity and synergistically enhances the foam's hydrophilic and liquid-retaining properties with the hydrophilic chain extender. Based on this, the synergistic system enables the antibacterial agent to achieve zero leaching while maintaining high activity, preserving both the safety and long-lasting effect of contact antibacterial action. Furthermore, the combination of structural reinforcement agents and stabilizers ensures excellent mechanical strength and biocompatibility of the foam, achieving a high degree of unity between antibacterial performance, material safety, and physical properties. In particular, the synergistic effect of stabilizers and structural reinforcing agents in this invention is one of the core mechanisms for achieving "non-overflow" antibacterial properties. The two form a synergistic effect through a dual path of reaction environment optimization and physical network enhancement.

[0052] Firstly, the core objective of this invention is to chemically bond guanidine antibacterial agents within a three-dimensional polyurethane network. The stabilizer, as a core process control component, confines the reaction system within specific process conditions, providing suitable kinetics for the chain extension / grafting reactions of isocyanates with hydroxyl and amino groups. This avoids runaway reaction rates and prepolymer deactivation, providing the prerequisite for the formation of stable chemical bonds between the stabilizer and the polyurethane network, thus achieving non-overflow fixation of the antibacterial agent from the root. Simultaneously, specific components in the structural reinforcing agent possess process-aiding capabilities, effectively supplementing the stabilizer. After the main stabilizer completes the basic macroscopic system control, the powder particles of the structural reinforcing agent can form a micro-region process-stabilized system within the reaction system. This effectively solves the problems of localized process condition fluctuations and byproduct accumulation caused by exothermic foaming reactions, avoiding the decrease in grafting rate and free antibacterial agent residues caused by uneven local reactions. The synergistic effect of both components achieves stable and controllable process conditions throughout the system, significantly improving the grafting rate between the guanidine antibacterial agent and the polyurethane matrix, laying the molecular foundation for non-overflow characteristics.

[0053] Secondly, the liquid absorption, liquid retention, and mechanical properties of polyurethane foam are directly related to the uniformity and integrity of its cell structure. These two factors create a synergistic effect through bidirectional complementarity during cell formation and structural reinforcement. Stabilizers, in addition to process control, effectively suppress side reactions during foaming, preventing cell collapse, merging, and breakage. This ensures a stable and controllable nucleation and growth process, providing a stable reaction environment for the structural reinforcement agent and preventing powder agglomeration and nucleation site failure caused by excessively rapid reaction rates. The structural reinforcement agent, as an inorganic powder, functions primarily as a heterogeneous nucleating agent during the foaming process. It provides numerous uniform nucleation sites for the CO2 bubbles generated by the reaction of water and isocyanate, significantly improving cell density and uniformity and preventing the formation of large pores and interconnected pores. Simultaneously, the inorganic powder can fill the cross-linking nodes of the polyurethane network, greatly enhancing the foam's compressive strength, resilience, and structural stability, effectively solving the problem of easy collapse and strength reduction after liquid absorption in highly hydrophilic systems. Furthermore, the powder surface of the structural reinforcing agent can adsorb surfactant and stabilizer molecules in the system, causing them to accumulate directionally at the cell walls, further enhancing the strength and toughness of the cell walls, reducing overflow and breakage problems during foaming, and conversely strengthening the system's reaction stability. These two components synergistically construct a uniform, dense, and high-strength three-dimensional polyurethane network structure, ensuring a liquid absorption and retention capacity eight times its own weight, maintaining a moist wound healing environment, and further limiting the migration of trace amounts of ungrafted antibacterial agents through the dense network structure, enhancing non-overflow properties, and preventing dressing failure due to structural collapse after liquid absorption.

[0054] Thirdly, medical polyurethane foam dressings need to maintain performance stability during storage and clinical use. The two components work together to provide long-term protective synergy, ensuring the material's biocompatibility and long-lasting antibacterial effect. The stabilizer itself possesses excellent process condition maintenance capabilities, neutralizing / buffering environmental fluctuations during storage and contact with wound exudate, inhibiting the hydrolytic aging of the polyurethane matrix, and maintaining physiologically appropriate conditions when the material contacts the wound, reducing irritation to the wound and surrounding skin. Meanwhile, the inorganic powder in the structural reinforcing agent forms a physical barrier, delaying the penetration of water, body fluids, and other media into the polyurethane matrix, significantly reducing the matrix's hydrolysis rate and extending the material's lifespan. Simultaneously, the active components in the structural reinforcing agent form a long-lasting, sustained-release buffer system with the stabilizer, continuously maintaining system stability under long-term body fluid flushing, preventing the breakage of grafted chemical bonds and the shedding of antibacterial agents due to environmental fluctuations. At the production process level, the two also work synergistically: the stabilizer inhibits the thermal degradation and side reactions of polyurethane during high-temperature drying at 120~200℃, while the structural reinforcing agent improves the foam's temperature resistance and shrinkage resistance, reduces structural deformation and performance degradation during high-temperature drying, and ensures the stability of production batches. Ultimately, the synergy between the two achieves long-term material stability, resulting in a 0% leaching rate of antibacterial agent in 72h and 108h extraction tests, cytotoxicity meeting medical standards, and maintaining long-term stable contact antibacterial properties. This reduces the risk of bacterial resistance and secondary contamination, while meeting the long-term use needs of clinical scenarios such as acute and chronic wounds and pressure ulcers.

[0055] As an optional implementation, the hydrophilic chain extender includes any one or a combination of at least two of the following: polypropylene glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated poly(dibutylene), hydroxyl-terminated hydrogenated poly(dibutylene), hydroxyl-terminated poly(dibutylene-acrylonitrile), polyethylene oxide triol, propylene oxide-ethylene oxide co-ether triol, polycaprolactone triol, pentaerythritol polyether polyol, diaminopolyether tetraol, polyether pentaol, polyether hexaol, polystyrene polyol, castor oil and its castor oil derivatives polyol, soybean oil polyol, palm oil polyol, and rosin ester polyol.

[0056] As an optional implementation, the number average molecular weight of the hydrophilic chain extender is 200 to 20,000, for example, it can be 200, 400, 600, 800, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, etc.

[0057] As an optional embodiment, the number average molecular weight of the polypropylene oxide glycol is 400-5000.

[0058] As an optional implementation, the alcohol in the adipic acid-based polyester glycol is any one or a combination of at least two of ethylene glycol, propylene glycol, 1,4-butanediol, and diethylene glycol.

[0059] As an optional implementation, the alcohol in the aromatic polyester diol is diethylene glycol; the acid is any one or a combination of at least two of phthalic anhydride, terephthalic acid, isophthalic acid, etc.

[0060] As an optional embodiment, the number average molecular weight of the polycaprolactone diol is 300-4000.

[0061] As an optional implementation, the number average molecular weight of the polyethylene glycol is 200 to 20,000.

[0062] As an optional implementation, the number-average molecular weight of the polypropylene glycol is 400 to 2000.

[0063] As an optional implementation, the number average molecular weight of the polyethylene oxide triol is 300-7000.

[0064] As an optional embodiment, the number average molecular weight of the propylene oxide-ethylene oxide copolyether triol is 300-7000.

[0065] As an optional embodiment, the number average molecular weight of the polycaprolactone triol is 300-3000.

[0066] As an optional implementation, the diamine in the diamine-based polyether tetraol may be any one or a combination of at least two of ethylenediamine, toluenediamine, diaminodiphenylmethane, and m-xylenediamine.

[0067] As an optional implementation, the polyether pentol is prepared from diethylenetriamine or xylitol.

[0068] As an optional implementation, the polyether hexaol is prepared from sorbitol or mannitol.

[0069] In a preferred embodiment, the hydrophilic chain extender is any one or a combination of at least two of the following: polypropylene glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated polybutene-acrylonitrile, polyethylene oxide triol, propylene oxide-ethylene oxide copolyether triol, and polycaprolactone triol.

[0070] In a preferred embodiment, the hydrophilic chain extender includes at least a strongly hydrophilic chain extender; wherein the strongly hydrophilic chain extender includes any one of polyethylene glycol, polyvinylpyrrolidone, polyethylene oxide triol, and propylene oxide-ethylene oxide copolyether triol.

[0071] It should be noted that the strong hydrophilic chain extender has excellent water solubility and can significantly improve the liquid absorption and retention capacity of foam. It is the core functional component of the hydrophilic system of this invention and can achieve the goal of absorbing liquid up to 8 times its own weight.

[0072] In a more preferred embodiment, the hydrophilic chain extender includes, in addition to a strongly hydrophilic chain extender, a moderately hydrophilic chain extender and / or a functional chain extender; wherein, the moderately hydrophilic chain extender includes any one of polypropylene oxide glycol, polypropylene glycol, polytrimethylene ether glycol, adipic acid-based polyester glycol, and polycaprolactone glycol; and the functional chain extender includes any one of aromatic polyester diol, polycarbonate diol, polytetrahydrofuran glycol, hydroxyl-terminated poly(dibutylene-acrylonitrile), and polycaprolactone triol.

[0073] It should be noted that moderately hydrophilic chain extenders balance hydrophilicity, water resistance, and mechanical properties, balancing the foam's liquid absorption capacity and structural stability, thus preventing softening and collapse of the foam after liquid absorption in highly hydrophilic systems. Meanwhile, functional chain extenders, although less hydrophilic, play a crucial role in regulating the foam's mechanical properties, hydrolysis resistance, heat resistance, and tear resistance. Without compromising the system's hydrophilic foundation, they address the foam's overall performance shortcomings, meeting the long-term needs of medical applications. This invention can synergistically construct a dense cross-linked network using strongly hydrophilic chain extenders, moderately hydrophilic chain extenders, and / or functional chain extenders, further enhancing the antibacterial agent's non-overflow properties and achieving a comprehensive balance of hydrophilicity, structural stability, and functional compatibility.

[0074] As an optional implementation, the surfactant includes any one or a combination of at least two of the following: polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol ether, propylene glycol block polyether, oleyl alcohol polyoxyethylene ether, polyethylene glycol, fatty acid polyoxyethylene ester, stearyl sorbitan, Tween, and triglyceride.

[0075] As an optional implementation, the guanidine salt antibacterial agent includes any one or a combination of at least two of polyhexamethylene biguanide hydrochloride, polyhexamethylene monoguanide hydrochloride, guanidine hydrochloride, chlorhexidine gluconate, chlorhexidine acetate, and chlorhexidine hydrochloride.

[0076] As an optional implementation, the stabilizer is a reaction system regulator.

[0077] As an optional implementation, the stabilizer is a reaction system regulator used to limit the reaction system within a process window; wherein, the process window is characterized by the following parameters: the conductivity of the solution system is 5~30 mS / cm, for example, it can be 5 mS / cm, 6 mS / cm, 8 mS / cm, 10 mS / cm, 12 mS / cm, 14 mS / cm, 16 mS / cm, 18 mS / cm, 20 mS / cm, 22 mS / cm, 24 mS / cm, 26 mS / cm, 28 mS / cm, 30 mS / cm, etc.; the exothermic peak temperature of the reaction is 30~50℃, for example, it can be 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, etc.

[0078] As an optional implementation, the reaction system regulator includes electrolyte compounds and / or molecular compounds.

[0079] As an optional implementation, the electrolyte type includes carboxylates and inorganic salts; the carboxylates include sodium citrate, sodium lactate, and sodium acetate; the inorganic salts include sodium bicarbonate and sodium hydroxide.

[0080] As an optional embodiment, the molecular type includes nitrogen-containing organic compounds; the nitrogen-containing organic compounds include 2-amino-2-methyl-1-propanol, sodium bicarbonate, triethanolamine, arginine, 1,3-propanediamine, ethylenediamine, triethylamine, trimethylamine, choline, tromethamine, ethanolamine, dimethylaminoethanol, and triisopropanolamine. As a preferred embodiment, the reaction system regulator includes at least carboxylates.

[0081] It should be noted that carboxylates (the core electrolyte component, preferably sodium citrate) are the preferred core stabilizers in the original formulation of this invention. With a conductivity range of 5-30 mS / cm, they can effectively regulate the ionic strength and rheological properties of the system, maintain reaction kinetic stability, ensure the smooth progress of the grafting reaction of the antibacterial agent, and exhibit excellent biocompatibility. They can form a micro-buffer synergy with the structure-strengthening agent, which is the basis for achieving non-overflow bonding of the antibacterial agent. In a preferred embodiment, the reaction system regulator, in addition to carboxylates, also includes molecularly nitrogen-containing organic compounds.

[0082] It should be noted that the molecular nitrogen-containing organic compounds are specially adapted components for polyurethane systems. They have excellent water solubility and system compatibility. They can dynamically fine-tune the molecular distribution and viscosity changes during the reaction process through the ion transfer effect and hydrogen bonding, smoothly catalyze chain extension / grafting reactions, avoid burst polymerization, bubble breakage and cell collapse, and simultaneously achieve bubble stabilization and precise control of reaction rate. They form a gradient synergy with electrolytes in terms of static ionic stability and dynamic molecular regulation.

[0083] As an optional implementation, the structural reinforcing agent includes any one or a combination of at least two of the following: light calcium carbonate, heavy calcium carbonate, silica powder, sodium silicate, borax, and kaolin.

[0084] As an optional implementation, the structural reinforcing agent includes any one or a combination of at least two of the following: carbonate inorganic fillers (such as light calcium carbonate, heavy calcium carbonate), silicate inorganic fillers (such as silica powder, sodium silicate, kaolin), and borate inorganic additives (such as borax).

[0085] In a preferred embodiment, the structural reinforcing agent comprises a combination of light calcium carbonate, sodium silicate and borax, or a combination of light calcium carbonate and sodium silicate, or a combination of light calcium carbonate and borax.

[0086] It should be noted that: Firstly, the core inorganic powder combination in the structural reinforcing agent includes high specific surface area carbonates, highly active silicates, and high-temperature stable borates. Light calcium carbonate plays a crucial role in core mechanical reinforcement and heterogeneous nucleation, sodium silicate enhances network density and cell stability, and borax strengthens the structural stability during high-temperature drying. These three components work synergistically with the stabilizer to construct a process buffer system, enhancing non-overflow characteristics and overall foam performance. Secondly, the carbonate-silicate dual-core combination is the preferred solution. Light calcium carbonate primarily provides mechanical reinforcement and cell refinement, while sodium silicate assists in cross-linking and foam stabilization, improving structural density. Their strong synergy meets the performance and cost balance requirements of large-scale production. Thirdly, the carbonate-borate combination is the preferred high-temperature process. Light calcium carbonate plays a major role in structural reinforcement, while borax specifically optimizes the foam's anti-shrinkage and anti-bubble-breaking capabilities under 120~200℃ drying conditions, ensuring batch stability.

[0087] As an optional implementation, the lubricant includes any one or a combination of at least two of the following: methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, calcium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, casein, calcium alginate, sodium alginate, gelatin, pectin, xanthan gum, carrageenan, xanthan gum, guar gum, gum arabic, hyaluronic acid, sodium hyaluronate, ceramide, nicotinamide, chitosan, and starch.

[0088] As an optional implementation, the isocyanate prepolymer is generated by reacting an alcohol monomer with a diisocyanate monomer. The alcohol monomer comprises polyether polyols and / or polyester polyols; the diisocyanate monomer comprises any one or a combination of at least two of the following: toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, dimethylbiphenyl diisocyanate, polymethylene polyphenyl isocyanate, 1,6-hexamethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenylenediamine diisocyanate, tetramethyl-isophthalimethylene diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, cyclohexanedimethylene diisocyanate, and norbornene diisocyanate.

[0089] As an optional implementation, the raw materials for preparing the isocyanate prepolymer include alcohol monomers, diisocyanate monomers, catalysts, stabilizers, small molecule chain extenders, and crosslinking agents.

[0090] As an optional implementation, the alcohol monomer is a polyether polyol.

[0091] As an optional implementation, the polyether polyol includes any one or a combination of at least two of polyoxypropylene polyol, sorbitol-based polyether polyol, sucrose-based polyether polyol, trimethylolpropane polyether polyol, and glycerol-based polyether polyol.

[0092] As an optional implementation, the -NCO content in the isocyanate prepolymer is 6~8%, for example, it can be 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, etc.

[0093] As an optional embodiment, the catalyst includes any one or a combination of at least two of the following: dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, triethylenediamine, bis(dimethylaminoethyl) ether, N-methylmorpholine, and tetramethylethylenediamine.

[0094] As an optional embodiment, the stabilizer includes any one or a combination of at least two of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-hydroxy-4-methoxybenzophenone, and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol.

[0095] As an optional implementation, the small molecule chain extender includes any one or a combination of at least two of 1,4-butanediol, ethylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, ethylenediamine, diethylenediamine, or isophoronediamine.

[0096] In a preferred embodiment, the small molecule chain extender is a combination of at least two of 1,4-butanediol, ethylene glycol, 1,6-hexanediol, or neopentyl glycol.

[0097] As an optional implementation, the crosslinking agent includes any one or a combination of at least two of glycerol, trimethylolpropane, pentaerythritol, triethanolamine, triethylenetetramine, or tetraethylenepentamine.

[0098] As an optional implementation, the crosslinking agent is a combination of at least two of trimethylolpropane, triethanolamine, triethylenetetramine, and tetraethylenepentamine.

[0099] As an optional implementation, the mass ratio of the alcohol monomer to the diisocyanate monomer is (5~6):(4~5); Among them, "5~6" can be, for example, 5, 5.2, 5.4, 5.6, 5.8, 6, etc.; Among them, "4~5" can be, for example, 4, 4.2, 4.4, 4.6, 4.8, 5, etc.

[0100] As an optional implementation, the mass ratio of the polyether polyol, diisocyanate monomer, catalyst, stabilizer, small molecule chain extender, and crosslinking agent is (50~60):(40~50):(0.1~1):(0.1~1):(0~5):(0~5).

[0101] As an optional implementation, the stock solution A comprises, by weight, 1-20 parts of a hydrophilic chain extender (e.g., 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, etc.), 1-10 parts of a surfactant (e.g., 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.), 0.1-2 parts of an antibacterial agent (e.g., 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, etc.), and 0.1-2 parts of a stabilizer. (For example, it can be 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, etc.), structural reinforcing agent 0.1~1 parts (for example, it can be 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, etc.), lubricant 1~10 parts (for example, it can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.), water 50~99 parts (for example, it can be 50 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 99 parts, etc.).

[0102] In a preferred embodiment, the hydrophilic chain extender in the stock solution A is 5 to 15 parts by weight, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc.

[0103] In a preferred embodiment, the surfactant in the stock solution A is 3 to 5 parts by weight, for example, 3 parts, 3.2 parts, 3.4 parts, 3.5 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.5 parts, 4.6 parts, 4.8 parts, 5 parts, etc.

[0104] In a preferred embodiment, the antibacterial agent in the stock solution A is 0.5 to 1.5 parts by weight, for example, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.5 parts, etc.

[0105] In a preferred embodiment, the stabilizer in the stock solution A is 0.5 to 1.5 parts by weight, for example, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.5 parts, etc.

[0106] In a preferred embodiment, the weight percentage of the structural reinforcing agent in the stock solution A is 0.3 to 0.7 parts, for example, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts, etc.

[0107] In a preferred embodiment, the lubricant in the stock solution A is 2 to 8 parts by weight, for example, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, etc.

[0108] In a preferred embodiment, the water content in the stock solution A is 65 to 85 parts by weight, for example, 65, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 85, etc.

[0109] As an optional implementation, the stock solution B includes, by weight, 50 to 200 parts of isocyanate prepolymer (e.g., 50, 60, 80, 100, 120, 140, 160, 180, 200, etc.).

[0110] In a preferred embodiment, the weight fraction of the isocyanate prepolymer in the stock solution B is 100-150 parts, for example, 100 parts, 105 parts, 110 parts, 115 parts, 120 parts, 125 parts, 130 parts, 135 parts, 140 parts, 145 parts, 150 parts, etc.

[0111] In a second aspect, the present invention provides a method for preparing a non-overflowing antibacterial medical polyurethane as described in the first aspect, the method comprising: Hydrophilic chain extender, surfactant, antibacterial agent, stabilizer, structure enhancer, lubricant and water are mixed to prepare stock solution A; isocyanate prepolymer is used as stock solution B; Mix stock solution A and stock solution B, and then stir to obtain a mixture; The mixture is poured onto release paper and then coated on a roller to obtain a mixture encapsulated in release paper (such as...). Figure 1 (as shown) The mixture wrapped in the release paper is dried to obtain the non-overflowing antibacterial medical polyurethane.

[0112] As an optional implementation, the temperature for preparing the stock solution A is 16~20℃, for example, 16℃, 17℃, 18℃, 19℃, 20℃, etc.; the stirring time for preparing the stock solution A is 1~3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.

[0113] As an optional implementation, the reaction temperature for preparing the stock solution B (i.e., the isocyanate prepolymer) is 60~80℃, for example, 60℃, 62℃, 64℃, 65℃, 66℃, 68℃, 70℃, 72℃, 74℃, 75℃, 76℃, 78℃, 80℃, etc.; the reaction time is 3~6 h, for example, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, etc. As an optional implementation, the temperature of the stirring process is 20~30℃, for example, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 28℃, 30℃, etc.; the stirring speed is 4000~5000 rpm, for example, 4000 rpm, 4200 rpm, 4400 rpm, 4500 rpm, 4600 rpm, 4800 rpm, 5000 rpm, etc.; and the stirring time is 2~4 s, for example, 2 s, 2.2 s, 2.4 s, 2.6 s, 2.8 s, 3 s, 3.2 s, 3.4 s, 3.6 s, 3.8 s, 4 s, etc.

[0114] As an optional implementation, during the roller coating process, the moving speed of the coating roller is 1~10 mm / s, for example, it can be 1 mm / s, 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, 10 mm / s, etc.

[0115] As an optional implementation, the coating thickness during the roller coating process is 1 to 10 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.

[0116] As an optional implementation, the drying temperature is 120~200℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, etc.

[0117] Thirdly, the present invention provides the use of the non-overflowing antimicrobial medical polyurethane as described in the first aspect in the preparation of products for acute and chronic wound management and / or pressure ulcer prevention and treatment.

[0118] The present invention will be further illustrated below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0119] Example 1 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0120] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, polyethylene glycol 400, polypropylene glycol 600, polyoxyethylene ether 400, sodium citrate, dimethylaminoethanol, light calcium carbonate, sodium silicate, borax and hydroxymethyl cellulose were added sequentially to pure water and stirred thoroughly at 18°C ​​for 2 h to obtain stock solution A. Preparation of stock solution B: Polypropylene oxide polyol 600, toluene diisocyanate, 1,4-cyclohexane diisocyanate, triethylenediamine, 2,6-di-tert-butyl-p-cresol, 1,4-butanediol, 1,6-hexanediol and glycerol were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5 and reacted at 70°C for 4.5 h. The reaction was stopped when the -NCO content dropped to 7%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0121] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 25℃, the stirring speed is 4500rpm, and the stirring time is 3s to obtain the mixture.

[0122] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 8 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0123] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 160°C to obtain the non-overflowing antibacterial medical polyurethane.

[0124] Example 2 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0125] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene monoguanidine hydrochloride, polyvinylpyrrolidone, aromatic polyester diol, fatty alcohol polyoxyethylene ether 600, sodium lactate, tromethamine, light calcium carbonate, sodium silicate and hydroxymethyl cellulose were added sequentially to pure water and stirred thoroughly at 18°C ​​for 2 h to obtain stock solution A. Preparation of stock solution B: Sorbitol polyether polyol 600, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, bis(dimethylaminoethyl) ether, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,4-butanediol, neopentyl glycol and trimethylolpropane were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5 and reacted at 80°C for 3 h. The reaction was stopped when the -NCO content dropped to 6%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0126] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 80 parts of stock solution B and mix them. The stirring temperature is controlled at 30℃, the stirring speed is 4500rpm, and the stirring time is 3s to obtain the mixture.

[0127] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 8 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0128] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 160°C to obtain the non-overflowing antibacterial medical polyurethane.

[0129] Example 3 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0130] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Chlorhexidine gluconate, polyethylene glycol 600, tetrahydrofurandiol 650, oleyl alcohol polyoxyethylene ether OV-3, sodium acetate, arginine, light calcium carbonate, borax and carboxymethyl cellulose were added sequentially to pure water and stirred thoroughly at 16°C for 2 h to obtain stock solution A. Preparation of stock solution B: Sucrose-based polyether polyol 600, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, bis(dimethylaminoethyl) ether, 2-hydroxy-4-methoxybenzophenone, 1,6-hexanediol, neopentyl glycol and triethanolamine were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5 and reacted at 60°C for 6 h. The reaction was stopped when the -NCO content dropped to 6%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0131] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 120 parts of stock solution B and mix them. The stirring temperature is controlled at 20℃, the stirring speed is 5000rpm, and the stirring time is 4s to obtain the mixture.

[0132] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 8 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0133] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 120°C to obtain the non-overflowing antibacterial medical polyurethane.

[0134] Example 4 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0135] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, propylene oxide-ethylene oxide copolyether triol 600, polycaprolactone triol 600, fatty acid polyoxyethylene ester, sodium citrate, arginine, light calcium carbonate, sodium silicate and hydroxyethyl cellulose were added sequentially to pure water and stirred thoroughly at 20°C for 2 h to obtain stock solution A. Preparation of stock solution B: Trimethylolpropane polyether polyol 600, naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, bis(dimethylaminoethyl) ether, 2-hydroxy-4-methoxybenzophenone, 1,6-hexanediol, neopentyl glycol, triethylenetetramine and tetraethylenepentamine were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5:0.3:0.2 and reacted at 70°C for 5 hours. The reaction was stopped when the -NCO content dropped to 8%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0136] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 28℃, the stirring speed is 4000rpm, and the stirring time is 2s to obtain the mixture.

[0137] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 10 mm / s; the coating thickness is 4 mm, resulting in a mixture wrapped in release paper.

[0138] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 180°C to obtain the non-overflowing antibacterial medical polyurethane.

[0139] Example 5 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0140] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, polyethylene glycol 600, hydroxyl-terminated poly(dibutylene-acrylonitrile), fatty acid polyoxyethylene ester, sodium citrate, arginine, light calcium carbonate, sodium silicate and ceramide were added sequentially to pure water and stirred thoroughly at 20°C for 2 h to obtain stock solution A. Preparation of stock solution B: Trimethylolpropane polyether polyol 600, naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, bis(dimethylaminoethyl) ether, 2-hydroxy-4-methoxybenzophenone, 1,6-hexanediol, neopentyl glycol, triethylenetetramine and tetraethylenepentamine were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5:0.3:0.2 and reacted at 72°C for 4 hours. The reaction was stopped when the -NCO content dropped to 8%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0141] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 30℃, the stirring speed is 4000rpm, and the stirring time is 2s to obtain the mixture.

[0142] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 6 mm / s; the coating thickness is 6 mm, resulting in a mixture wrapped in release paper.

[0143] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 180°C to obtain the non-overflowing antibacterial medical polyurethane.

[0144] Example 6 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0145] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, polyethylene glycol 800, polycaprolactone triol 600, triglyceride tripropionate, sodium citrate, arginine, light calcium carbonate, sodium silicate and chitosan were added sequentially to pure water and stirred thoroughly at 20°C for 2 h to obtain stock solution A. Preparation of stock solution B: Trimethylolpropane polyether polyol 600, naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, bis(dimethylaminoethyl) ether, 2-hydroxy-4-methoxybenzophenone, 1,6-hexanediol, neopentyl glycol, triethylenetetramine and tetraethylenepentamine were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5:0.3:0.2 and reacted at 70°C for 4 hours. The reaction was stopped when the -NCO content dropped to 8%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0146] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 25℃, the stirring speed is 4000rpm, and the stirring time is 2s to obtain the mixture.

[0147] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 10 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0148] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 200°C to obtain the non-overflowing antibacterial medical polyurethane.

[0149] Example 7 This embodiment provides a non-overflowing antibacterial medical polyurethane, which differs from Embodiment 1 only in that polyethylene glycol 400 is replaced with an equal mass of pentaerythritol polyether polyol 400, and propylene glycol 600 is replaced with an equal mass of polyether pentol 600. The other steps are the same as in Embodiment 1.

[0150] Example 8 This embodiment provides a non-overflow antibacterial medical polyurethane, which differs from Embodiment 1 only in that polyethylene glycol 400 is replaced with an equal mass of ethylenediamine polyether tetraol 400, and propylene glycol 600 is replaced with an equal mass of polyether hexaol 600. The other steps are the same as in Embodiment 1.

[0151] Example 9 This embodiment provides a non-overflow antibacterial medical polyurethane, which differs from Embodiment 1 only in that sodium citrate is replaced with an equal mass of sodium hydroxide and dimethylaminoethanol is replaced with an equal mass of ethylenediamine. The other steps are the same as in Embodiment 1.

[0152] Example 10 This embodiment provides a non-overflow antibacterial medical polyurethane, which differs from Embodiment 1 only in that sodium citrate is replaced with an equal mass of sodium bicarbonate and dimethylaminoethanol is replaced with an equal mass of triethylamine. The other steps are the same as in Embodiment 1.

[0153] Example 11 This embodiment provides a non-overflowing antibacterial medical polyurethane, which differs from Embodiment 1 only in that light calcium carbonate is replaced with an equal mass of heavy calcium carbonate, sodium silicate is replaced with an equal mass of silica powder, and borax is replaced with an equal mass of kaolin. The other steps are the same as in Embodiment 1.

[0154] Example 12 This embodiment provides a non-overflowing antibacterial medical polyurethane, which differs from Embodiment 1 only in that the structural reinforcing agent, a combination of light calcium carbonate, sodium silicate, and borax, is replaced with a single 0.5 parts of kaolin. The other steps are the same as in Embodiment 1.

[0155] Example 13 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0156] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, polyethylene glycol 400, polyoxyethylene ether 400, sodium citrate, light calcium carbonate and methylcellulose were added sequentially to pure water and stirred thoroughly at 18°C ​​for 2 h to obtain stock solution A; Preparation of stock solution B: Polypropylene oxide polyol 600, toluene diisocyanate, 1,4-cyclohexane diisocyanate, triethylenediamine, 2,6-di-tert-butyl-p-cresol, 1,4-butanediol, 1,6-hexanediol and glycerol were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5 and reacted at 70°C for 4.5 h. The reaction was stopped when the -NCO content dropped to 7%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0157] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 24℃, the stirring speed is 4500rpm, and the stirring time is 3s to obtain the mixture.

[0158] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 8 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0159] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 160°C to obtain the non-overflowing antibacterial medical polyurethane.

[0160] Example 14 This embodiment provides a non-overflow antibacterial medical polyurethane. The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B, and the specific formulation is as follows:

[0161] The non-overflow antibacterial medical polyurethane is prepared by the following steps: S1. Preparation of stock solution A and stock solution B: Preparation of stock solution A: Polyhexamethylene biguanide hydrochloride, polyethylene glycol 400, polyoxyethylene ether 400, sodium citrate, light calcium carbonate and methylcellulose were added sequentially to pure water and stirred thoroughly at 18°C ​​for 2 h to obtain stock solution A; Preparation of stock solution B: Polypropylene oxide polyol 600, toluene diisocyanate, 1,4-cyclohexane diisocyanate, triethylenediamine, 2,6-di-tert-butyl-p-cresol, 1,4-butanediol, 1,6-hexanediol and glycerol were mixed in a mass ratio of 55:40:5:0.5:0.5:0.5:0.5 and reacted at 70°C for 4.5 h. The reaction was stopped when the -NCO content dropped to 7%, and the isocyanate prepolymer was obtained, which is stock solution B.

[0162] S2. Mix stock solution A and stock solution B together: Weigh 100 parts of stock solution A and 100 parts of stock solution B and mix them. The stirring temperature is controlled at 25℃, the stirring speed is 4500rpm, and the stirring time is 3s to obtain the mixture.

[0163] S3, Roller coating: The mixed liquid is poured onto release paper and coated by rollers; during the roller coating process, the moving speed of the coating roller is 8 mm / s; the coating thickness is 5 mm, resulting in a mixture wrapped in release paper.

[0164] S4. Drying: After passing through the rollers, the mixture wrapped in release paper is dried in an oven at 160°C to obtain the non-overflowing antibacterial medical polyurethane.

[0165] Comparative Example 1 This comparative example provides a polyurethane that differs from Example 14 only in that sodium citrate and light calcium carbonate are not added, nor is polyhexamethylene biguanide hydrochloride (PHMB). The other steps are the same as in Example 14.

[0166] Comparative Example 2 This comparative example provides an overflow-type antibacterial polyurethane, which differs from Example 14 only in that sodium citrate and light calcium carbonate are not added, while the other steps are the same as in Example 14.

[0167] Comparative Example 3 This comparative example provides an antibacterial polyurethane, which differs from Example 14 only in that polyhexamethylene biguanide hydrochloride is replaced with benzalkonium chloride, while the other steps are the same as in Example 14.

[0168] Comparative Example 4 This comparative example provides an antibacterial polyurethane, which differs from Example 14 only in that polyhexamethylene biguanide hydrochloride is replaced with chitosan, while the other steps are the same as in Example 14.

[0169] Comparative Example 5 This comparative example provides an antibacterial polyurethane, which differs from Example 14 only in that sodium citrate is no longer added, and the content of light calcium carbonate is increased by 1.1 parts. The other steps are the same as in Example 14.

[0170] Comparative Example 6 This comparative example provides an antibacterial polyurethane, which differs from Example 14 only in that light calcium carbonate is no longer added, the sodium citrate content is increased by 1.1 parts, and the other steps are the same as in Example 14.

[0171] Test Example 1 Antibacterial zone test: Test samples: Non-overflow antibacterial medical polyurethane provided in Examples 1-14, and polyurethane provided in Comparative Examples 1-6.

[0172] Definition of inhibition zone (refer to ISO 20645:2004): A qualitative or semi-quantitative antimicrobial test method for assessing the ability of a material to inhibit bacterial growth.

[0173] The principle of inhibition zone: The sample is placed in close contact with the surface of an agar plate inoculated with a specific test bacterium. After incubation, the size of the sterile area (i.e., the inhibition zone) formed around the sample is observed to determine whether the antibacterial agent has the effect of inhibiting the spread and growth of bacteria.

[0174] Inhibition zone test method: Cut the test sample and control sample into circular pieces of the specified size (usually about 25 mm in diameter) and sterilize them. Apply the specified concentration (10... 6Test bacterial suspensions (Staphylococcus aureus, Escherichia coli, and Candida albicans) at CFU / mL were evenly spread on a solid agar plate. The sterilized, moistened sample was then firmly adhered to the agar surface inoculated with the bacterial suspension, ensuring no air bubbles were present. The plate was incubated at 35°C for 24 hours. The width of the inhibition zone around the sample was measured, and bacterial growth in the contact area below the sample was observed.

[0175] Specific test results are shown in Table 1 and... Figure 2 As shown: Table 1

[0176] From Table 1 and Figure 2 The test results show that, compared with the blank control group, the polyurethane foam of this invention exhibits a broad-spectrum and highly efficient antibacterial effect; within the optimal addition range, the antibacterial activity gradually increases with the increase of the addition amount and tends to saturate. Only the non-overflow type and the blank control polyurethane foam did not produce an inhibition zone in the test, proving that the antibacterial agent achieves non-overflow fixation through covalent bonding, and has excellent antibacterial stability; the components of the formulation have no antagonistic effect, synergistically ensuring the antibacterial effect, and the overall performance is superior to similar products on the market.

[0177] Test Example 2 Contact antimicrobial test Test samples: Non-overflow antibacterial medical polyurethane provided in Examples 1-14, and polyurethane provided in Comparative Examples 1-6.

[0178] Contact antimicrobial property definition (refer to AATCC 100-2019): A quantitative antimicrobial test method for evaluating the effectiveness of a material in reducing the number of viable bacteria over a specific contact time.

[0179] Contact antibacterial principle: The antibacterial performance is quantitatively evaluated by calculating the logarithmic decrease in the number of viable bacteria or the antibacterial rate of the sample before and after a certain period of contact.

[0180] Contact antibacterial activity test method: Cut a circular test sample with a diameter of 4.8±0.1 cm and place it in a sterile container. Add a specified concentration (10 μg) of the solution directly to the sample. 5 Test bacterial suspensions (Staphylococcus aureus, Escherichia coli, and Candida albicans) at CFU / mL, ensuring uniform coverage of the sample. Incubate the inoculated sample for 24 hours at suitable temperature and humidity. After contact, add a known volume of neutralization buffer and elute the sample by vigorous shaking. Serially dilute the eluent and perform viable counts on pour plates or spread plates. Calculate the bacterial reduction value or antimicrobial rate by comparing the number of viable bacteria on the "0 contact time" control sample and the test sample after the specified "contact time". The formula is as follows: Antibacterial rate (%) = [(Count of colonies in control sample at time 0 - Count of colonies in test sample after contact) / Count of colonies in control sample at time 0] × 100%.

[0181] The specific test results are shown in Table 2: Table 2

[0182] As shown in Table 2, the non-overflow antibacterial polyurethane foam of the present invention exhibits excellent contact antibacterial properties, with high contact antibacterial rates against both bacteria and fungi, significantly superior to the blank group without antibacterial agent. Compared to the comparative example with physically doped antibacterial agents, the antibacterial effect of the foam of the present invention remains consistent and is not affected by the covalent bonds of the antibacterial agent, verifying the feasibility and stability of the non-overflow characteristics. The synergistic effect of each formulation component does not antagonize the contact antibacterial effect, ensuring the reliability and practicality of the antibacterial performance.

[0183] Test Example 3 Infrared spectroscopy test Test samples: Non-overflow antibacterial medical polyurethane provided in Example 1, and polyurethane provided in Comparative Examples 1 and 2.

[0184] Infrared spectroscopy (ATR-FTIR, no reference standard): a physical method for structural analysis and identification based on the characteristic absorption of infrared radiation by molecules of a substance.

[0185] Infrared detection principle: Based on molecular vibrational and rotational energy level transitions. Different chemical bonds produce characteristic absorption peaks at specific wavenumbers due to differences in force constants and atomic masses, forming a unique fingerprint spectrum.

[0186] like Figure 3 As shown, the left image shows the infrared spectra of ordinary foam (Comparative Example 1), overflow foam (Comparative Example 2), and non-overflow foam (Example 1) – a comparison image; the middle image shows the core group peaks are labeled; the right image shows the infrared spectra of ordinary foam (Comparative Example 1), overflow foam (Comparative Example 2), and non-overflow foam (Example 1) – original image. Among them, the non-overflow foam (Example 1 and Comparative Example 2) raw materials were treated with an antibacterial agent (PHMB) and chemically grafted, resulting in antibacterial polyurethane foam with a peak density of 1640 cm⁻¹. -1 A C=N stretching vibration peak will appear, which belongs to the core group of PHMB - the guanidinium group (aside from this peak, the other characteristic peaks are identical, as most group peaks of PHMB are very similar to those of polyurethane). Furthermore, the amount of antibacterial agent PHMB added is very limited, which results in a low grafting content in the reaction mechanism, and the corresponding group absorption peak intensity will be weaker compared to other groups.

[0187] Test Example 4 MTT cytotoxicity assay Test samples: Non-overflow antibacterial medical polyurethane provided in Examples 1-14, and polyurethane provided in Comparative Examples 1-6.

[0188] MTT assay (ISO 10993-5): A method for detecting cell viability and growth.

[0189] Detection principle: Succinate dehydrogenase in the mitochondria of living cells can reduce exogenous MTT to water-insoluble blue-purple crystalline formazan, which is then deposited in the cells, while dead cells do not have this function.

[0190] The specific test results are shown in Table 3: Table 3

[0191] As shown in Table 3, the polyurethane foam of this invention, after MTT cytotoxicity testing, showed a high relative cell proliferation rate, far exceeding the acceptable threshold for cytotoxicity in medical materials, indicating no potential cytotoxicity and meeting the requirements for medical biocompatibility. Compared with commercially available antibacterial foams, the foam of this invention exhibits superior cell compatibility and does not suffer from enhanced toxicity due to antibacterial agent leaching. This verifies the effectiveness of the non-overflow design of covalently bonded antibacterial agents in improving biosafety and meets the clinical application needs of medical wound dressings.

[0192] Test Example 5 Guanidine salt leaching experiment Test samples: Non-overflow antibacterial medical polyurethane provided in Examples 1-14, and polyurethane provided in Comparative Examples 1-6.

[0193] Guanidine salt leaching test (visible spectrophotometry): a method for quantitatively analyzing the absorbance or transmittance of a substance in the visible light wavelength range.

[0194] Detection principle: Guanidine salt molecules generally have characteristic absorption in the ultraviolet region (e.g., the maximum absorption wavelength of polyhexamethylene biguanide (PHMB) molecules, which contain guanidine groups and benzene ring structures, is usually around 234 nm). By measuring the absorbance value at this wavelength and establishing a standard working curve (i.e., standard curve) of guanidine salt concentration versus absorbance value in the corresponding example, quantitative analysis of the guanidine salt in the corresponding example in the unknown sample can be performed.

[0195] Test method: ① Prepare solutions of different concentrations using guanidine salt standards; ② Test solutions of different concentrations at the maximum absorption wavelength (e.g., PHMB, at 234 nm) to obtain standard curves for the guanidine salts of the corresponding examples or comparative examples; ③ Soak the samples (three small pieces of each type) in purified water at 37℃ for 72 h (3 days) and 108 h (7 days), and shake at 60 rpm. ④ Take the extract and measure the absorbance using a visible light spectrophotometer to obtain the absorbance value; ⑤ Calculate and judge based on the guanidine salt standard curve.

[0196] The specific test results are shown in Table 4: Table 4

[0197] As shown in Table 4, the polyurethane foam of the present invention was tested by leaching experiments. The leachate showed no antibacterial effect on the target pathogens and no inhibition zone formation, with no significant difference from the blank group. This proves that the antibacterial agent in the foam did not undergo dissolution migration and has significant non-overflow characteristics. After aging treatment, the leaching test results remained consistent, with no antibacterial components released, verifying the fixation stability of the covalently bonded antibacterial agent. Compared with the antibacterial effect of the leachate of the physical doped antibacterial agent control group, the superiority of the non-overflow design of the present invention is further highlighted, meeting the safety application requirements of medical dressings.

[0198] Test Example 6 Physical and mechanical performance testing Test samples: Non-overflow antibacterial medical polyurethane provided in Examples 1-14, and polyurethane provided in Comparative Examples 1-6.

[0199] Test method: (1) Average pore size: Polyurethane foam was cut to a suitable size and fixed on the sample stage. After gold sputtering, a suitable area was selected in the electron imaging mode of a scanning electron microscope (model: HITACHI SU8010), and the surface morphology of the material was photographed at a fixed magnification. The pore edges were identified based on grayscale differences, and the pore size was tested using the instrument's built-in image analysis software. Multiple pore sizes were tested and the average value was calculated. (2) Surface porosity: The polyurethane foam is cut into regular shapes (e.g., cuboid shape), placed into the sample cell of the helium hydrometer (model: 3H-2000TD), vacuumed to remove residual gas, and helium is filled into the sample cell. The initial and equilibrium pressure of the sample cell are recorded respectively. The sample volume is calculated according to the gas state equation. The apparent density is calculated using the sample mass and volume. The surface porosity of the material is calculated using the apparent density and the true density. (3) Liquid absorption (YY / T 0471.1-2004): Place a 5 cm × 5 cm sample of known mass in a petri dish, add test solution A preheated to (37±1)℃, the mass of which is 40 times ±0.5 g of the sample material. Transfer the petri dish to a drying oven and keep it at (37±1)℃ for 30 min. Hold a corner or section of the sample with tweezers, suspend it for 30 s, and weigh it. Repeat 5 times for each type of sample.

[0200] Test solution A: Composed of sodium chloride and calcium chloride solution. This solution contains 142 mmol of sodium ions and 2.5 mmol of calcium ions. The ion content of this solution is equivalent to that of human serum or wound exudate. Dissolve 8.298 g of sodium chloride and 0.368 g of calcium chloride in deionized water in a volumetric flask and dilute to 1 L.

[0201] (4) Liquid retention: Take the sample that has been saturated with liquid in the liquid absorption experiment, apply a pressure of 5 kPa (simulating local pressure in the human body) and hold for 1 min, remove the pressure and weigh; repeat 5 times for each type of sample.

[0202] (5) Tensile strength and elongation (ASTM D3574): Cut at least five specimens using a dumbbell-shaped die. After standing for 24 hours at a temperature of 23±2℃ and a relative humidity of 50±5%, measure the width and thickness of the middle section of the specimen and calculate the original cross-sectional area. Place both ends of the specimen into the fixture of a universal testing machine and stretch the specimen at a constant speed until it breaks. Record the maximum load and elongation at break.

[0203] The specific test results are shown in Table 5: Table 5

[0204] As shown in Table 5, the present invention is a medical polyurethane foam that retains the high pore size, high air permeability, high liquid absorption and high liquid retention capacity of the foam itself. The foam can absorb a large amount of wound exudate (8 times its own weight) while maintaining a moist healing environment and avoiding maceration of the surrounding skin.

[0205] As can be seen from the comparison between Examples 1 and Examples 7-8, compared with the polyol combinations introduced in Examples 7-8, the molecular structure of Example 1 endows the polyurethane network with more suitable degrees of freedom of movement. While maintaining high tensile strength, it exhibits superior elongation at break, giving the material both good structural support and flexible conformability, enabling it to adapt to irregular wound contours without easily causing stress concentration. Simultaneously, the synergistic effect of the linear chain extender system, combined with the stabilizer and structural reinforcing agent, achieves a balance between uniform and regular cell structure and optimized surface porosity, ensuring high air permeability and liquid absorption efficiency. Furthermore, the bonding reaction between the antibacterial agent and isocyanate in Example 1 is more mild and controllable, ensuring that the guanidine salt antibacterial component is firmly anchored in the network structure through covalent bonds, achieving true non-overflow properties and long-lasting contact antibacterial efficacy.

[0206] A comparison of Examples 1 and 9-10 shows that, compared to the control schemes in Example 9 (replacing sodium citrate with sodium hydroxide and ethylenediamine) and Example 10 (replacing sodium bicarbonate and triethylamine), the synergistic system of carboxylate and molecular nitrogen-containing organic compounds in Example 1 can more precisely confine the reaction within the process window, achieving an optimized balance between the conductivity of the solution system and the exothermic peak temperature of the reaction. This compounding scheme effectively suppresses the side reactions of isocyanate and water and premature gelation, making the foaming process stable and controllable, with orderly cell nucleation and growth stages, avoiding pore wall defects and structural reinforcement agent aggregation failure caused by uneven local reactions. Simultaneously, sodium citrate, as the core electrolyte stabilizer, forms a gradient synergy with dimethylaminoethanol through proton transfer and hydrogen bonding, ensuring efficient chemical grafting of the antibacterial agent and isocyanate groups while maintaining a good match between prepolymer viscosity and foaming rate. This significantly improves batch consistency and the reliability of non-overflow characteristics, and also demonstrates superior cytotoxicity.

[0207] A comparison of Examples 1 and 11-12 shows that the carbonate-silicate-borate synergistic system of Example 1 achieves multiple functional couplings of heterogeneous nucleation, network densification, and high-temperature stability. Light calcium carbonate, as the core mechanical reinforcing component and heterogeneous nucleation site, works in conjunction with sodium silicate to increase the crosslinking density of the cell walls and borax to enhance the anti-shrinkage ability during high-temperature drying. These three components, along with the stabilizer, form a micro-region buffer synergy, effectively solving the problem of localized process fluctuations caused by the exothermic foaming reaction, and ensuring the uniformity of cell size and the integrity of the open-cell structure. This compound formulation, while maintaining high surface porosity, significantly improves the compressive strength and resilience of the foam, preventing structural collapse after liquid absorption. Furthermore, it delays hydrolytic aging caused by body fluid penetration through physical barriers, ensuring the long-term protection of the antibacterial agent's non-overflow characteristics and biosafety.

[0208] A comparison of Examples 1 and 13-14 shows that the formulation ratio of Example 1 is more balanced and reasonable. Example 13 suffers from unsatisfactory cytotoxicity due to excessive antibacterial agent content, while Example 14 exhibits deterioration in mechanical properties and cell structure due to an imbalance in the ratio of hydrophilic chain extender to surfactant and an excessively high lubricant dosage. Example 1, through optimized synergistic proportions of its components, achieves zero leaching, satisfactory cytotoxicity, and excellent physical and mechanical properties while ensuring high-efficiency contact antibacterial activity, demonstrating the precise control advantage of the formulation window of this invention.

[0209] As can be seen from the comparison between Example 14 and Comparative Example 1, the synergistic introduction of antibacterial agents, stabilizers, and structural reinforcing agents is key to endowing the material with functional properties and structural stability. Comparative Example 1, by completely omitting polyhexamethylene biguanide hydrochloride, sodium citrate, and light calcium carbonate, maintained basic foam molding ability but lost all antibacterial activity, and its mechanical properties and cell structure deteriorated significantly.

[0210] As can be seen from the comparison between Example 14 and Comparative Example 2, although Comparative Example 2 retains the antibacterial agent of physical blending, the lack of sodium citrate and light calcium carbonate results in the loss of precise process control and heterogeneous nucleation support in the reaction system. Consequently, the antibacterial agent cannot be firmly anchored to the network structure through covalent bonds, exhibiting obvious overflow characteristics, significant inhibition zone and unqualified cytotoxicity.

[0211] As can be seen from the comparison between Example 14 and Comparative Example 3, the chemical structure type of the antibacterial agent directly determines its bonding efficiency with the polyurethane matrix and the degree of non-leaking characteristics. Comparative Example 3 used benzalkonium chloride instead of guanidine salt antibacterial agents. Although it possessed surface-active antibacterial capabilities, its molecular structure lacked active sites for efficient chemical grafting with isocyanate groups. This resulted in the antibacterial components being mainly dispersed in the network through physical adsorption or ionic bonding, with significantly insufficient bonding strength, extremely high leaching rate, and unacceptable cytotoxicity. The polyhexamethylene biguanide hydrochloride selected in Example 14 contains multiple guanidine functional groups, which can form stable covalent bonds with the isocyanate prepolymer. Under mild reaction conditions controlled by a stabilizer, efficient in-situ grafting is achieved, allowing the antibacterial active components to be firmly embedded in the three-dimensional network structure, exhibiting zero leaching and non-leaking characteristics. Simultaneously, it maintained excellent contact antibacterial rate and biosafety, fully verifying the irreplaceable role of guanidine salt antibacterial agents in constructing chemically bonded long-lasting antibacterial systems.

[0212] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-overflowing antibacterial medical polyurethane, characterized in that, The raw materials for preparing the non-overflow antibacterial medical polyurethane include: stock solution A and stock solution B; The stock solution A comprises a hydrophilic chain extender, a surfactant, an antibacterial agent, a stabilizer, a structure reinforcing agent, a lubricant, and water; the stock solution B comprises an isocyanate prepolymer. The antibacterial agent is a guanidine salt antibacterial agent, and the antibacterial agent is chemically bonded to the three-dimensional network structure of the non-overflow antibacterial medical polyurethane.

2. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The non-overflow antibacterial medical polyurethane is characterized in that the hydrophilic chain extender comprises any one or a combination of at least two of the following: polypropylene oxide glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated polybutene, hydroxyl-terminated hydrogenated polybutene, hydroxyl-terminated polybutene-acrylonitrile, polyethylene oxide triol, propylene oxide-ethylene oxide co-ether triol, polycaprolactone triol, pentaerythritol polyether polyol, diamino polyether tetraol, polyether pentaol, polyether hexaol, polystyrene polyol, castor oil and its castor oil derivatives polyol, soybean oil polyol, palm oil polyol, and rosin ester polyol. Preferably, the hydrophilic chain extender is any one or a combination of at least two of the following: polypropylene glycol, polyvinylpyrrolidone, adipic acid-based polyester glycol, aromatic polyester glycol, polycaprolactone glycol, polycarbonate glycol, polytetrahydrofuran glycol, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, hydroxyl-terminated polybutene-acrylonitrile, polyethylene oxide triol, propylene oxide-ethylene oxide copolyether triol, and polycaprolactone triol; Preferably, the number average molecular weight of the hydrophilic chain extender is 200 to 20,000.

3. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The non-overflow antibacterial medical polyurethane is characterized in that the surfactant comprises any one or a combination of at least two of the following: polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isomeric alcohol ether, propylene glycol block polyether, oleyl alcohol polyoxyethylene ether, polyethylene glycol, fatty acid polyoxyethylene ester, stearyl sorbitan, Tween, and triglyceride.

4. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The non-overflow antibacterial medical polyurethane is characterized in that the guanidine salt antibacterial agent includes any one or a combination of at least two of polyhexamethylene biguanide hydrochloride, polyhexamethylene monoguanide hydrochloride, guanidine hydrochloride, chlorhexidine gluconate, chlorhexidine acetate, and chlorhexidine hydrochloride.

5. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The stabilizer is a reaction system regulator used to limit the reaction system within a process window; wherein, the process window is characterized by the following parameters: the conductivity of the solution system is 5~30 mS / cm; the exothermic peak temperature of the reaction is 30~50℃; Preferably, the reaction system regulator includes electrolyte compounds and / or molecular compounds; Preferably, the electrolyte compound includes any one or a combination of at least two of sodium citrate, sodium lactate, sodium bicarbonate, sodium hydroxide, and sodium acetate; Preferably, the molecular compound includes any one or a combination of at least two of 2-amino-2-methyl-1-propanol, triethanolamine, arginine, 1,3-propanediamine ethylenediamine, triethylamine, trimethylamine, choline, tromethamine, ethanolamine, dimethylaminoethanol, and triisopropanolamine. Preferably, the structural reinforcing agent comprises any one or a combination of at least two of the following: light calcium carbonate, heavy calcium carbonate, silica powder, sodium silicate, borax, and kaolin. Preferably, the lubricant comprises any one or a combination of at least two of the following: methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, calcium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, casein, calcium alginate, sodium alginate, gelatin, pectin, xanthan gum, carrageenan, xanthan gum, guar gum, gum arabic, hyaluronic acid, sodium hyaluronate, ceramide, nicotinamide, chitosan, and starch.

6. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The isocyanate prepolymer is generated by reacting an alcohol monomer with a diisocyanate monomer. Wherein, the alcohol monomer includes polyether polyols and / or polyester polyols; the diisocyanate monomer includes any one or a combination of at least two of the following: toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, dimethylbiphenyl diisocyanate, polymethylene polyphenyl isocyanate, 1,6-hexamethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenylenediamine diisocyanate, tetramethyl isophthalimethylene diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, cyclohexane dimethylene diisocyanate, and norbornene diisocyanate. Preferably, the alcohol monomer is a polyether polyol; Preferably, the polyether polyol comprises any one or a combination of at least two of polyoxypropylene polyol, sorbitol-based polyether polyol, sucrose-based polyether polyol, trimethylolpropane polyether polyol, and glycerol-based polyether polyol. Preferably, the -NCO content in the isocyanate prepolymer is 6-8%; Preferably, the mass ratio of the alcohol monomer to the diisocyanate monomer is (5~6):(4~5).

7. The non-overflowing antibacterial medical polyurethane according to claim 1, characterized in that, The stock solution A comprises, by weight, 1-20 parts of hydrophilic chain extender, 1-10 parts of surfactant, 0.1-2 parts of antibacterial agent, 0.1-2 parts of stabilizer, 0.1-1 parts of structure reinforcing agent, 1-10 parts of lubricant, and 50-99 parts of water; The stock solution B comprises, by weight, 50-200 parts of isocyanate prepolymer.

8. A method for preparing a non-overflowing antibacterial medical polyurethane according to any one of claims 1 to 7, characterized in that, The preparation method includes: Hydrophilic chain extender, surfactant, antibacterial agent, stabilizer, structure enhancer, lubricant and water are mixed to prepare stock solution A; isocyanate prepolymer is used as stock solution B; Mix stock solution A and stock solution B, and then stir to obtain a mixture. The mixture is poured onto release paper and then coated by rollers to obtain a mixture wrapped in release paper. The mixture wrapped in the release paper is dried to obtain the non-overflowing antibacterial medical polyurethane.

9. The method for preparing the non-overflow antibacterial medical polyurethane according to claim 8, characterized in that, The stirring temperature is 20~30℃, the stirring speed is 4000~5000 rpm, and the stirring time is 2~4 s; Preferably, during the roller coating process, the moving speed of the coating roller is 1~10 m / min; the coating thickness is 1~10 mm. Preferably, the drying temperature is 120~200℃.

10. The use of a non-overflowing antimicrobial medical polyurethane according to any one of claims 1 to 7 in the preparation of products for acute and chronic wound management and / or pressure ulcer prevention and treatment.

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