Antibacterial thermoplastic polyurethane composite material and preparation method thereof

Abstract

The invention belongs to the technical field of polymer composite materials, and particularly relates to an antibacterial thermoplastic polyurethane composite material and a preparation method thereof. The problems that in the prior art, a thermoplastic polyurethane matrix has a weak diffusion retardation effect on an inorganic silver antibacterial agent, and a phosphorus-containing flame retardant and silver ions coexist to easily generate silver phosphate precipitates, so that the flame-retardant and antibacterial effects are reduced are solved. The composite material disclosed by the invention takes TPU (Thermoplastic Polyurethane) as a matrix, and comprises Ag (at) ZIF-8 (at) PDA-peptide / PtPd and an antibacterial flame-retardant difunctional monomer, through structural gradient optimization design, mechanical properties are considered while slow-release and long-acting sterilization is realized; the flame-retardant and antibacterial polymer material has excellent antibacterial performance and efficient flame-retardant performance, and is suitable for the field of flame-retardant and antibacterial polymer products.

Description

Technical Field

[0001] This invention belongs to the field of polymer functional composite materials technology, specifically relating to antibacterial thermoplastic polyurethane composite materials and their preparation methods. This material is mainly used in thermoplastic polyurethane composite materials for products with high requirements for flame retardancy and antibacterial properties, such as electronic device housings, medical device components, and public transportation vehicle interiors. Background Technology

[0002] Thermoplastic polyurethane (TPU) is widely used in electronics, automotive, and medical fields due to its excellent mechanical and processing properties. However, TPU materials are flammable and release toxic gases at high temperatures, necessitating the addition of flame retardants to improve safety. Furthermore, TPU products used in medical and public settings often require antibacterial properties to prevent bacterial growth and cross-infection. Traditional methods achieve antibacterial and flame-retardant functions by adding inorganic antibacterial agents and phosphorus-containing flame retardants to the polymer; however, this approach has the following drawbacks:

[0003] (1) The TPU matrix has a weak diffusion-blocking effect on inorganic silver antibacterial agents (such as nano-silver or silver ions), meaning that silver particles or silver ions are easily migrated and exuded in the TPU matrix, resulting in the rapid release of antibacterial agents. Although they can provide a strong bactericidal effect in the early stages, the duration is short. Filler-type antibacterial agents are largely precipitated and consumed in the early stages of use, which not only shortens the effective antibacterial time of the material but may also cause discoloration of the material surface or changes in mechanical properties. In addition, a high amount of silver agent is required to maintain sufficient antibacterial performance, which may weaken the mechanical and processing properties of the TPU material.

[0004] (2) When commonly used phosphorus-containing flame retardants (such as inorganic polyphosphates) coexist with silver-based antibacterial agents, the two may have an antagonistic effect. For example, when phosphorus-containing flame retardants and silver ion antibacterial agents coexist, silver phosphate precipitates may be formed, which weakens the antibacterial and flame retardant effects of the material. At the same time, the silver phosphate precipitates may be unevenly dispersed, which can act as a defect and further affect the mechanical properties and thermal stability of the material.

[0005] To address these issues, researchers have proposed several improvements, such as preloading silver nanoparticles onto a support or coating their surface to slow down the release of silver ions. However, conventional supports have limited control over the slow release of silver ions and significantly impact other material properties. Therefore, a new material design and preparation method is urgently needed to synergistically solve the problems of rapid loss of silver antibacterial agents and mutual interference between silver ions and phosphorus flame retardants. Summary of the Invention

[0006] The purpose of this invention is to provide an antibacterial thermoplastic polyurethane composite material and its preparation method, thereby solving the technical problems in the prior art where the sustained-release performance of silver antibacterial agents in the TPU matrix is ​​weak, and where the coexistence of silver ions and phosphorus-containing flame retardants results in the formation of silver phosphate precipitation, which weakens the flame retardant and antibacterial effects. The material of this invention, through innovative material structure design and component selection, endows the composite material with excellent long-lasting antibacterial and flame retardant properties, while also taking into account mechanical properties and balanced processability.

[0007] The specific technical solution is as follows:

[0008] Antibacterial thermoplastic polyurethane composite materials and their preparation methods are as follows:

[0009] S1: Enzyme-pH dual-responsive PDA-metal-organic framework structure.

[0010] S11: Disperse ZIF-8 in AgNO3 solution, vacuum disperse for 30 min, then add ascorbic acid, and reduce at 40℃ in the dark for 3 h to obtain Ag@ZIF-8.

[0011] S12: Disperse Ag@ZIF-8 in Tris-HCl buffer, add DA-HCl, and stir under N2 protection for 24 h in the dark. Centrifuge to obtain Ag@ZIF-8@PDA.

[0012] S13: The peptide chain, NHS, and EDC were shaken at room temperature for 30 min, and then Ag@ZIF-8@PDA was added, with the molar ratio of peptide chain to carrier being 1:8 to 1:12. The mixture was reacted at 4℃ for 12 h to obtain Ag@ZIF-8@PDA-peptide (peptide: peptide).

[0013] S14: Disperse Ag@ZIF-8@PDA-peptide in deionized water, then add chloroplatinic acid and palladium chloride, and react with pulsed sonication; then add NaBH4 dropwise, react at 35℃ for 1 h, and centrifuge to obtain Ag@ZIF-8@PDA-peptide / PtPd; add sodium citrate, stir at room temperature for 2 h, and obtain surface passivated Ag@ZIF-8@PDA-peptide / PtPd.

[0014] S2: Preparation of bifunctional monomers.

[0015] S21: Under nitrogen protection, DOPO and terephthalaldehyde were added to the reaction vessel, then heated to 120°C and mechanically stirred at 300 rpm for 10 h. The mixture was then cooled to room temperature, recrystallized from ethanol, and dried under vacuum at 80°C for 12 h to obtain DOPO-aldehyde.

[0016] S22: Dissolve DOPO-aldehyde and 6-aminohexanol in methanol and stir at 25°C for 2 hours to generate a yellow Schiff base; then cool to 0°C in an ice bath and add NaBH4 in batches while controlling the temperature to be less than 10°C and the pH to be 7; after the addition is complete, heat to 25°C and continue stirring for 2 hours, then remove methanol by rotary evaporation, wash three times with water, and dry under vacuum to obtain secondary amino alcohol.

[0017] S23: Dissolve secondary amino alcohol in DMF, add bromododecane, and stir at 80°C for 24 h; then add dimethylamine aqueous solution dropwise and continue the reaction for 6 h; then cool to 60°C, add diethyl ether to precipitate the product, filter, and finally wash three times with diethyl ether and vacuum dry at 60°C for 48 h to obtain a bifunctional monomer with antibacterial and flame-retardant properties.

[0018] S3: Bifunctional monomer-grafted TPU was prepared by drying TPU particles under vacuum at 80°C for 12 hours, then adding dried TPU and DMF solvent to a nitrogen-protected reactor, heating to 90°C and stirring to dissolve for 2 hours, followed by dropwise addition of a DMF solution of bifunctional monomers, wherein the TPU:monomer ratio was 1:0.05 to 1:0.15; DBTDL catalyst was then added, and the reaction was carried out at 90-100°C for 6-8 hours; finally, the reaction solution was poured into ice-cold methanol to precipitate, filtered, washed three times with methanol, and dried under vacuum at 60°C for 24 hours to obtain bifunctional monomer-grafted TPU.

[0019] S4: Two-layer gradient structure design.

[0020] S41: Preparation of inner and outer layer materials. Inner layer material preparation: Based on 100 parts of TPU base material, 0.5-3 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-mixed with 1 part of bifunctional monomer-grafted TPU. Outer layer material preparation: Based on 100 parts of TPU base material, 3-6 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-mixed with 1 part of bifunctional monomer-grafted TPU. Then, 100 parts of TPU base material, prepared in S3... Five to five parts of bifunctional monomer-grafted TPU were melt-blended using a twin-screw extruder. The twin-screw extruder had four zones: zone one, zone two, zone three, and zone four. The TPU was fed into the extruder through the main feed port and melt-plasticized in zones one and two. The dry-blended products of the surface layer and the inner layer were injected into the feed port of zone three. Volatile substances were removed by applying a vacuum of -0.08 MPa in zone four. The melt was cooled in a water bath, stretched, and pelletized. Finally, it was vacuum-dried at 40°C for 12 hours to obtain inner-layer modified TPU masterbatch and surface-layer modified TPU masterbatch.

[0021] S42: A dual-channel flat extrusion die is used, with independent channels for the inner and outer layers to transport the surface material and the inner material respectively. A confluence zone is set in front of the die exit so that the two layers of melt overlap in a viscous flow state to obtain a double-layer sheet with a total thickness of 0.5 mm, of which the surface layer accounts for about 50 μm. Then, a three-stage cooling system is used for cooling and shaping. The sheet is then wound up by a traction machine and cut for sampling.

[0022] Furthermore, the ZIF-8 described in S11 is dispersed in an AgNO3 solution at a mass ratio of 1:0.15 to 1:0.25.

[0023] The ascorbic acid described in S11 has a molar ratio of silver ions to ascorbic acid of 1:1.8 to 1:2.2.

[0024] Furthermore, the centrifugation described in S12 has the following parameter settings: rotation speed 8000~10000rpm, duration 10~15min, and temperature 4~10℃.

[0025] Furthermore, the molar ratio of peptide chain, NHS, and EDC described in S13 is 1:2.5:5 to 1:5:10.

[0026] Furthermore, the molar ratio of chloroplatinic acid and palladium chloride described in S14 is 2.5:1 to 3.5:1;

[0027] The pulsed ultrasound described in S14 has the following parameter settings: power: 100-150W, duration: 8-12min, on for 2s / off for 1s.

[0028] The addition of NaBH4 described in S14 involves a molar ratio of Pt to Pd:NaBH4 of 1:4 to 1:6.

[0029] Furthermore, the molar ratio of DOPO to terephthalaldehyde in S21 is in the range of 1:1.05 to 1:1.10.

[0030] Furthermore, the DOPO-aldehyde and 6-aminohexanol described in S22 are soluble in methanol, wherein the molar ratio of DOPO-aldehyde to 6-aminohexanol is 1:1.1 to 1:1.2, and the solid-liquid ratio of the two to methanol is 1:10.

[0031] The addition of NaBH4 as described in S22 has a molar ratio of 1.8:1 to that of the Schiff base.

[0032] Furthermore, in the case of the bromododecane described in S23, the molar ratio of secondary amino alcohol to bromododecane is 1:1.2 to 1:1.5.

[0033] The dimethylamine aqueous solution described in S23 has a molar ratio of secondary amino alcohol to dimethylamine aqueous solution of 1:1.5 to 1:2.0.

[0034] Furthermore, the dry TPU and DMF solvent described in S3 have a mass-to-volume ratio of 1:5.

[0035] The DMF solution of the bifunctional monomer described in S3 has a TPU:bifunctional monomer ratio of 1:0.05 to 1:0.15.

[0036] The DBTDL catalyst described in S3 has a TPU to DBTDL ratio of 1:0.01 to 1:0.05.

[0037] Furthermore, the parameters of the twin-screw extruder described in S41 are set as follows: zone 1 temperature 160-170℃, zone 2 temperature 175-180℃, zone 3 temperature 180-185℃, zone 4 temperature 185-190℃, die head temperature 175-180℃, rotation speed of zone 1, zone 2, and zone 3 is 50-80 rpm, and rotation speed of zone 4 is 100-120 rpm.

[0038] Furthermore, the parameters of the dual-channel flat extrusion die described in S42 are set as follows: the extrusion temperature of the surface material and the inner material is 175-180℃, the extrusion speed ratio is 1:10, the melt pressure of the surface material is 8-10MPa, the melt pressure of the inner material is 6-8MPa, the temperature gradient of the surface material die is 178℃ for the upper channel, and the temperature gradient of the inner material die is 176℃ for the lower channel.

[0039] The cooling and shaping described in S42 has the following parameter settings: First-stage cold air knife: wind speed 15-30m / s, temperature 5-10℃; Second-stage water bath: water flow rate 0.3-0.8m / s, temperature 10-15℃; Third-stage calendering roller: temperature 35-45℃, pressure 0.3-0.8MPa.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. By using ZIF-8 channel confinement physical retardation, PDA-peptide chain intelligent chemical silver locking, and Pt and Pd reduction to decrease silver demand, the problem of weak silver ion retardation ability of TPU matrix is ​​solved.

[0042] 2. By replacing silver ions with asymmetric long-chain quaternary ammonium salts, the problem of silver phosphate precipitation was solved. At the same time, by constructing bifunctional monomers, the antibacterial and flame-retardant properties of polyurethane were improved.

[0043] 3. By constructing an enzyme-pH dual-responsive PDA-metal-organic framework, the antibacterial efficacy of polyurethane is extended while ensuring the mechanical and processing properties of TPU materials. Attached Figure Description

[0044] Figure 1This is a flowchart of the preparation method for antibacterial thermoplastic polyurethane composite materials.

[0045] Figure 2 This is a comparison chart of the antibacterial rate, limiting oxygen index, and response release rate of the polyurethanes prepared in Examples 1-4 and Comparative Examples 1-3.

[0046] Figure 3 This is a comparison chart of the tensile strength and elongation at break data of the polyurethanes prepared in Examples 1-4 and Comparative Examples 1-3. Detailed Implementation

[0047] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0048] This invention proposes an antibacterial thermoplastic polyurethane composite material and its preparation method. The raw materials comprise the following components: a thermoplastic polyurethane (TPU) matrix of commercially available polyester-type TPU particles (Shore hardness 95A, melting temperature 180℃), MOF material (ZIF-8, particle size 180–220 nm, pore size 1.5 nm), a silver source (AgNO3, 0.2 mol / L), a reducing agent (ascorbic acid, 0.05 mmol / L), a dispersion medium (methanol and water in a volume ratio of 4:1), a PDA precursor (dopamine hydrochloride, DA-HCl, 1.5 mg / mL), an enzyme-responsive peptide chain (peptide sequence: Gly-Gly-Arg, enzyme: β-lactamase), and a coupling agent (1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC, 5 mmol / L)). N-hydroxysuccinimide (NHS, 2 mmol / L), buffer system (Tris-HCl, pH 8.5, 10 mmol / L), metal precursor (chloroplatinic acid (H2PtCl6, 1 mmol / L, purity ≥99.9%), palladium chloride (PdCl2, 1 mmol / L, purity ≥99.5%)), reducing agent (sodium borohydride (NaBH4, 0.1 mmol / L, purity ≥96%)), stabilizer (2 wt% sodium citrate), 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO, industrial grade, melting point ≥118℃, phosphorus content ≥8.5%), terephthalaldehyde (purity ≥99%, anhydrous), 6-aminohexanol (purity ≥98%, moisture ≤0.1%), bromododecane (C 12 H 25Br (purity ≥95%), dimethylamine aqueous solution (33% aqueous solution), catalyst (DMF (anhydrous, 99.8%)), dibutyltin dilaurate (DBTDL), diethyl ether. See attached. Figure 1 The diagram shows a method for preparing antibacterial thermoplastic polyurethane composite materials. The detailed preparation steps are as follows:

[0049] 1. Enzyme-pH dual-responsive PDA-metal-organic framework structure

[0050] 1.1 ZIF-8 Loading AgNPs

[0051] ZIF-8 was dispersed in AgNO3 solution at a mass ratio of 1:0.15 to 1:0.25 and dispersed under vacuum for 30 min. Then, ascorbic acid was added, with a molar ratio of silver ions to ascorbic acid of 1:1.8 to 1:2.2. The mixture was reduced at 40 °C in the dark for 3 h to obtain Ag@ZIF-8.

[0052] 1.2 PDA Blocking

[0053] Disperse Ag@ZIF-8 in Tris-HCl buffer, add DA-HCl (1-2 mg / mL), and stir under N2 protection in the dark for 24 h. Centrifuge to obtain Ag@ZIF-8@PDA. Centrifugation parameters: speed 8000-10000 rpm, duration 10-15 min, temperature 4-10℃.

[0054] 1.3 Peptide chain modification

[0055] The peptide chain, NHS, and EDC were shaken at room temperature for 30 min, with the molar ratio of peptide chain:NHS:EDC ranging from 1:2.5:5 to 1:5:10. Then Ag@ZIF-8@PDA was added, with the molar ratio of peptide chain:Ag@ZIF-8@PDA ranging from 1:8 to 1:12. The mixture was reacted at 4 °C for 12 h to obtain Ag@ZIF-8@PDA-peptide.

[0056] 1.4 Bimetallic Nanozyme Modification

[0057] Ag@ZIF-8@PDA-peptide was dispersed in deionized water, and then chloroplatinic acid and palladium chloride were added, with a Pt:Pd molar ratio of 2.5:1 to 3.5:1. Pulsed sonication was performed with the following parameters: power 100–150 W, duration 8–12 min, on 2 s / off 1 s. Then, NaBH4 (Pt:Pd:reducing agent molar ratio of 1:4 to 1:6) was added dropwise, and the reaction was carried out at 35°C for 1 h. The mixture was then centrifuged to obtain Ag@ZIF-8@PDA-peptide / PtPd. Sodium citrate was then added, and the mixture was stirred at room temperature for 2 h to obtain the surface-passivated Ag@ZIF-8@PDA-peptide / PtPd.

[0058] 2. Preparation of bifunctional monomers

[0059] 2.1 Synthesis of DOPO-aldehydes

[0060] Under nitrogen protection, DOPO and terephthalaldehyde were added to a reaction vessel, then heated to 120°C and mechanically stirred at 300 rpm for 10 h. The mixture was then cooled to room temperature, recrystallized from ethanol, and dried under vacuum at 80°C for 12 h to obtain a white solid. The molar ratio of DOPO to terephthalaldehyde was in the range of 1:1.05 to 1:1.1.

[0061] 2.2 Preparation of secondary amino alcohol intermediates

[0062] DOPO-aldehyde and 6-aminohexanol were dissolved in methanol and stirred at 25°C for 2 hours. The molar ratio of DOPO-aldehyde to 6-aminohexanol was 1:1.1 to 1:1.2, and the solid-liquid ratio of the two to methanol was 1:10, forming a yellow Schiff base. The mixture was then cooled to 0°C in an ice bath, and NaBH4 was added in batches, maintaining a temperature below 10°C and a pH of 7. The molar ratio of the Schiff base to NaBH4 was 1:1.8. After the batch addition was complete, the temperature was raised to 25°C and stirring was continued for 2 hours. Methanol was then removed by rotary evaporation, and the mixture was washed three times with water and dried under vacuum to obtain a secondary amino alcohol.

[0063] 2.3 Quaternization reaction

[0064] Secondary amino alcohol was dissolved in DMF, and bromododecane was added. The mixture was stirred at 80°C for 24 h, with a molar ratio of secondary amino alcohol to bromododecane of 1:1.2 to 1:1.5. Then, dimethylamine aqueous solution was added dropwise, and the reaction was continued for 6 h, with a molar ratio of secondary amino alcohol to dimethylamine aqueous solution of 1:1.5 to 1:2.0. The mixture was then cooled to 60°C, and diethyl ether was added to precipitate the product. The precipitate was filtered, washed three times with diethyl ether, and dried under vacuum at 60°C for 48 h to obtain a bifunctional monomer with antibacterial and flame-retardant properties.

[0065] 3. Dual-function monomer grafted TPU

[0066] 3.1 Grafting

[0067] TPU particles were vacuum dried at 80℃ for 12 h. Then, in a nitrogen-protected reactor, dried TPU and DMF solvent were added, with a TPU:DMF mass-to-volume ratio of 1:5. The mixture was heated to 90℃ and stirred for 2 h to dissolve. Then, a DMF solution of bifunctional monomers (concentration of 20 wt%) was added dropwise, with a TPU:monomer ratio of 1:0.05 to 1:0.15. DBTDL catalyst (TPU to DBTDL ratio of 1:0.01 to 1:0.05) was added, and the reaction was carried out at 90–100℃ for 6–8 h. Finally, the reaction solution was poured into ice-cold methanol to precipitate the product. After filtration, the product was washed three times with methanol and vacuum dried at 60℃ for 24 h to obtain bifunctional monomer-grafted TPU.

[0068] 4. Double-layer gradient structure design

[0069] 4.1 Inner Layer Material Preparation

[0070] Based on 100 parts of TPU base material, 5-15 parts of bifunctional monomer-grafted TPU were melt-blended using a twin-screw extruder. The twin-screw extruder parameters were set as follows: Zone 1 temperature 160-170℃, Zone 2 temperature 175-180℃, Zone 3 temperature 180-185℃, Zone 4 temperature 185-190℃, and die head temperature 175-180℃. The rotation speeds of Zones 1, 2, and 3 were 50-80 rpm, and the rotation speed of Zone 4 was 100-120 rpm. Bifunctional monomer-grafted TPU is fed into the main feed port and melt-plasticized in zones one and two. Ag@ZIF-8@PDA-peptide / PtPd is dry-mixed with one part of bifunctional monomer-grafted TPU at a ratio of 0.5:1 to 3:1 and injected into the side feed port of zone three. Volatile substances are removed by applying a vacuum of -0.08MPa in zone four. The melt is cooled in a water bath, stretched into strips, granulated, and then vacuum-dried at 40℃ for 12 hours to obtain inner-layer modified TPU masterbatch.

[0071] 4.2 Preparation of Surface Material

[0072] Surface material formulation: 100 parts TPU base material, 5-15 parts bifunctional monomer-grafted TPU, 3-6 parts Ag@ZIF-8@PDA-peptide / PtPd and one part bifunctional monomer-grafted TPU are dry-mixed in a ratio of 3:1 to 6:1. Other processes are the same as those for the inner layer material, and the surface modified TPU masterbatch is finally obtained.

[0073] 4.3 Double-layer co-extrusion molding

[0074] A dual-channel flat extrusion die is used, with independent inner and outer channels to transport the surface layer and inner layer materials respectively. The extrusion temperature of the surface layer material and the inner layer material is 175–180℃, the extrusion speed ratio is 1:10, the melt pressure of the surface layer material is 8–10 MPa, and the melt pressure of the inner layer material is 6–8 MPa. The temperature gradient of the surface layer material at the die is 178℃ for the upper channel and 176℃ for the inner layer material at the die. A confluence zone is set before the die exit to allow the two melt layers to overlap in a viscous flow state, resulting in a double-layer sheet with a total thickness of 0.5 mm, of which the surface layer occupies approximately 50 μm. Then, a three-stage cooling system is used for cooling and shaping, with the following parameters: First stage: air knife; air velocity 15–30 m / s; temperature 5–10℃; Second stage: water bath; water flow rate 0.3–0.8 m / s; temperature 10–15℃; Third stage: calendering roller; temperature 35–45℃; pressure 0.3–0.8 MPa. After cooling, the sheet is wound up by a traction machine and cut for sampling.

[0075] Example 1

[0076] Antibacterial thermoplastic polyurethane composite materials and their preparation methods are as follows:

[0077] Table 1 Raw Material Data Table

[0078]

[0079]

[0080]

[0081]

[0082] S1: Enzyme-pH dual-responsive PDA-metal-organic framework structure.

[0083] S11: Disperse ZIF-8 in AgNO3 solution at a mass ratio of 1:0.2, vacuum disperse for 30 min, then add ascorbic acid, with a molar ratio of silver ions to ascorbic acid of 1:2, and reduce at 40℃ in the dark for 3 h to obtain Ag@ZIF-8.

[0084] S12: Disperse Ag@ZIF-8 in Tris-HCl buffer, add DA-HCl, and stir under N2 protection in the dark for 24 h. Centrifuge to obtain Ag@ZIF-8@PDA. The parameters are set as follows: rotation speed 9000 rpm, duration 12 min, and temperature 4℃.

[0085] S13: The peptide chain, NHS, and EDC were shaken at room temperature for 30 min, with a molar ratio of peptide chain:NHS:EDC of 1:4:8. Then Ag@ZIF-8@PDA was added, with a molar ratio of peptide chain:Ag@ZIF-8@PDA of 1:10. The mixture was reacted at 4℃ for 12 h to obtain Ag@ZIF-8@PDA-peptide.

[0086] S14: Ag@ZIF-8@PDA-peptide was dispersed in deionized water, then chloroplatinic acid and palladium chloride were added, with a Pt:Pd molar ratio of 3:1. The reaction was carried out by pulsed sonication with the following parameters: power 120W, duration 10min, on 2s / off 1s. Then NaBH4 was added dropwise, with a Pt:Pd:reducing agent molar ratio of 1:5. The reaction was carried out at 35℃ for 1h, and centrifuged to obtain Ag@ZIF-8@PDA-peptide / PtPd. Sodium citrate was added, and the mixture was stirred at room temperature for 2h to obtain surface passivated Ag@ZIF-8@PDA-peptide / PtPd.

[0087] S2: Preparation of bifunctional monomers.

[0088] S21: Under nitrogen protection, DOPO and terephthalaldehyde were added to the reactor, then heated to 120°C and mechanically stirred at 300 rpm for 10 h. The mixture was then cooled to room temperature, recrystallized from ethanol, and dried under vacuum at 80°C for 12 h to obtain a white solid. The molar ratio of DOPO to terephthalaldehyde was 1:1.07.

[0089] S22: DOPO-aldehyde and 6-aminohexanol were dissolved in methanol and stirred at 25°C for 2 hours, with a molar ratio of DOPO-aldehyde to 6-aminohexanol of 1:1.1 and a solid-liquid ratio of the two to methanol of 1:10, forming a yellow Schiff base. The mixture was then cooled to 0°C in an ice bath, and NaBH4 was added in batches, maintaining a temperature below 10°C and a pH of 7, with a molar ratio of Schiff base to NaBH4 of 1:1.8. The mixture was then heated to 25°C and stirred for another 2 hours. Methanol was removed by rotary evaporation, and the mixture was washed three times with water and dried under vacuum to obtain a secondary amino alcohol.

[0090] S23: Dissolve secondary amino alcohol in DMF, add bromododecane, and stir at 80°C for 24 h, wherein the molar ratio of secondary amino alcohol to bromododecane is 1:1.3; then add dimethylamine aqueous solution dropwise, and continue the reaction for 6 h, wherein the molar ratio of secondary amino alcohol to dimethylamine aqueous solution is 1:1.7; then cool to 60°C, add diethyl ether to precipitate, obtain the precipitate product, filter, and finally wash three times with diethyl ether, and dry under vacuum at 60°C for 48 h to obtain a bifunctional monomer with antibacterial and flame-retardant properties.

[0091] S3: TPU grafted with bifunctional monomers was prepared by drying TPU particles under vacuum at 80°C for 12 hours. Then, in a nitrogen-protected reactor, dried TPU and DMF solvent were added, with a TPU:DMF mass-to-volume ratio of 1:5. The mixture was heated to 90°C and stirred for 2 hours to dissolve. Next, a 20wt% DMF solution of the bifunctional monomer was added dropwise, with a TPU:monomer mass ratio of 1:0.10. DBTDL catalyst was then added, with a TPU:DBTDL mass ratio of 1:0.03. The reaction was carried out at 95°C for 7 hours. Finally, the reaction solution was poured into ice-cold methanol to precipitate the precipitate. After filtration, the precipitate was washed three times with methanol and dried under vacuum at 60°C for 24 hours to obtain the bifunctional monomer-grafted TPU.

[0092] S4: Two-layer gradient structure design.

[0093] S41: Preparation of inner and outer layer materials. Inner layer material preparation: Based on 100 parts of TPU base material, 0.5-3 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-dry-blended with 1 part of bifunctional monomer-grafted TPU. Outer layer material preparation: Based on 100 parts of TPU base material, 3-6 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-dry-blended with 1 part of bifunctional monomer-grafted TPU. Then, 5-15 parts of the 100 parts of TPU base material and the bifunctional monomer-grafted TPU prepared in S3 are melt-blended separately using a twin-screw extruder. The material is fed into four zones through the main feed port. Melting and plasticizing take place in zones one and two. The parameters of the twin-screw extruder are set as follows: zone one temperature 165℃, zone two temperature 177℃, zone three temperature 182℃, zone four temperature 188℃, die head temperature 178℃, rotation speed of zones one, two, and three 65 rpm, and rotation speed of zone four 110 rpm. The dry-mixed products of the surface layer and inner layer are injected into the feed port of zone three respectively. A vacuum of -0.08MPa is applied in zone four to remove volatile substances. The melt is cooled in a water bath, stretched, and pelletized. Finally, it is vacuum dried at 40℃ for 12 hours to obtain inner layer modified TPU masterbatch and surface modified TPU masterbatch.

[0094] S42: Employs a dual-channel flat extrusion die with independent inner and outer channels for conveying the surface and inner layers respectively. Parameter settings are as follows: extrusion temperature of the surface and inner layers is 177℃; extrusion speed ratio is 1:10; melt pressure of the surface layer is 9MPa; melt pressure of the inner layer is 7MPa; surface layer die temperature gradient is 178℃ for the upper channel; inner layer die temperature gradient is 176℃ for the lower channel. A confluence zone is set before the die exit to allow the two melt layers to overlap in a viscous flow state, resulting in a double-layer sheet with a total thickness of 0.5mm, of which the surface layer occupies approximately 50μm. A three-stage cooling system is then used for cooling and shaping, with the following parameters: first-stage cold air knife: air velocity 20m / s, temperature 7℃; second-stage water bath: water velocity 0.5m / s, temperature 12℃; third-stage calendering roller: temperature 40℃, pressure 0.5MPa. The sheet is then wound up by a traction machine and cut for sampling.

[0095] Example 2

[0096] The composition and preparation process are the same as in Example 1, except that:

[0097] In the preparation process S11, the mass ratio of ZIF-8 to AgNO3 is 1:0.15, the molar ratio of silver ions to ascorbic acid is 1:1.8, and other components are the same.

[0098] In the preparation process S13, the molar ratio of peptide chain: NHS: EDC is 1:2.5:5, the molar ratio of peptide chain: Ag@ZIF-8@PDA is 1:8, and other components are the same.

[0099] In the preparation process S14, the molar ratio of Pt:Pd is 2.5:1, the pulse ultrasound parameters are set as follows: power 100W, duration 8min, and the molar ratio of Pt to Pd:reducing agent is 1:4. Other steps are the same.

[0100] In step S21 of the preparation process, the molar ratio of DOPO to terephthalaldehyde is 1:1.05, and the other steps are the same.

[0101] In the preparation process S23, the molar ratio of secondary amino alcohol to bromododecane is 1:1.2; however, the molar ratio of secondary amino alcohol to dimethylamine aqueous solution is 1:1.5, and the other steps are the same.

[0102] In the preparation process S3, the ratio of TPU to monomer is 1:0.05; the reaction is carried out at 90℃ for 6 hours, and other steps are the same.

[0103] In the S41 preparation process, the temperature in zone 1 is 160℃, zone 2 is 175℃, zone 3 is 180℃, zone 4 is 185℃, and the die head temperature is 175℃. The rotation speed in zones 1, 2, and 3 is 50 rpm, and the rotation speed in zone 4 is 100 rpm. The amount of bifunctional monomer-grafted TPU is 5g. The inner layer material (Ag@ZIF-8@PDA-peptide / PtPd) is 0.5g, and the surface layer material is...

[0104] The Ag@ZIF-8@PDA-peptide / PtPd is 4.5g, and the other steps are the same.

[0105] In the S42 process of preparation, the extrusion temperature of the surface material and the inner material is 175℃; the first-stage cold air knife has an air velocity of 15m / s and a temperature of 10℃; the second-stage water bath has a water flow rate of 0.3m / s and a temperature of 15℃; the third-stage calendering roller has a temperature of 35℃ and a pressure of 0.3MPa, and the other steps are the same.

[0106] Example 3

[0107] The composition and preparation process are the same as in Example 1, except that:

[0108] In the preparation process S11, the mass ratio of ZIF-8 to AgNO3 is 1:0.25, the molar ratio of silver ions to ascorbic acid is 1:2.2, and other components are the same.

[0109] In the preparation process S13, the molar ratio of peptide chain: NHS: EDC is 1:5:10, the molar ratio of peptide chain: Ag@ZIF-8@PDA is 1:12, and other components are the same.

[0110] In the preparation process S14, the molar ratio of Pt:Pd is 3.5:1, the pulse ultrasound parameters are set as follows: power 150W, duration 12min, and the molar ratio of Pt to Pd:reducing agent is 1:6. Other steps are the same.

[0111] In step S21 of the preparation process, the molar ratio of DOPO to terephthalaldehyde is 1:1.10, and the other steps are the same.

[0112] In step S23 of the preparation process, the molar ratio of secondary amino alcohol to bromododecane is 1:1.5; however, the molar ratio of secondary amino alcohol to dimethylamine aqueous solution is 1:2.0, and the other steps are the same.

[0113] In the preparation process S3, the ratio of TPU to monomer is 1:0.15; the reaction is carried out at 100℃ for 8 hours, and other steps are the same.

[0114] In the S41 preparation process, the temperature in zone 1 is 170℃, zone 2 is 180℃, zone 3 is 185℃, zone 4 is 190℃, and the head temperature is 180℃. The rotation speed in zones 1, 2, and 3 is 80 rpm, and the rotation speed in zone 4 is 120 rpm. The amount of bifunctional monomer-grafted TPU is 15g, the inner layer material (Ag@ZIF-8@PDA-peptide / PtPd) is 3g, and the surface layer material (Ag@ZIF-8@PDA-peptide / PtPd) is 6g. Other steps are the same.

[0115] In the S42 process of preparation, the extrusion temperature of the surface material and the inner material is 180℃; the first-stage cold air knife has an air velocity of 30m / s and a temperature of 5℃; the second-stage water bath has a water flow rate of 0.8m / s and a temperature of 10℃; the third-stage calendering roller has a temperature of 45℃ and a pressure of 0.8MPa, and the other steps are the same.

[0116] Example 4

[0117] The composition and preparation process are the same as in Example 1, except that:

[0118] Centrifugation parameters in step S12 of the preparation process are set as follows: rotation speed 10000 rpm, duration 15 min, temperature 10℃, and other steps are the same.

[0119] In the preparation process S14, the pulse ultrasound parameters were set as follows: power 120W, duration 12min, and other components were the same.

[0120] In the preparation process, the molar ratio of secondary amino alcohol to bromododecane in S23 is 1:1.4, and the other steps are the same.

[0121] In the S41 preparation process, the temperature in zone 1 is 168℃, zone 2 is 179℃, zone 3 is 183℃, zone 4 is 186℃, and the head temperature is 176℃. The rotation speed in zones 1, 2, and 3 is 60 rpm, and the rotation speed in zone 4 is 105 rpm. The inner layer material is 1g of Ag@ZIF-8@PDA-peptide / PtPd, and the surface layer material is 6g of Ag@ZIF-8@PDA-peptide / PtPd. The other steps are the same.

[0122] In the S42 process of preparation, the extrusion temperature of the surface material and the inner material is 180℃; the first-stage cold air knife has an air velocity of 25m / s and a temperature of 5℃; the second-stage water bath has a water flow rate of 0.6m / s and a temperature of 12℃; the third-stage calendering roller has a temperature of 42℃ and a pressure of 0.7MPa, and the other steps are the same.

[0123] Comparative Example 1

[0124] The composition and preparation process are the same as in Example 1, except that:

[0125] The preparation of the S2 bifunctional monomer in the preparation process is omitted, while the other steps remain the same.

[0126] The S3 bifunctional monomer grafted TPU step in the preparation process is removed, and pure TPU base material is used directly, while the other steps are the same.

[0127] In the S41 preparation process, the inner layer material and the outer layer material do not contain bifunctional monomer-grafted TPU, but only Ag@ZIF-8@PDA-peptide / PtPd, and the other steps are the same.

[0128] Comparative Example 2

[0129] The composition and preparation process are the same as in Example 1, except that:

[0130] In step S41 of the preparation process, gradient design was eliminated, 10g of bifunctional monomer was grafted onto TPU, and 3g of Ag@ZIF-8@PDA-peptide / PtPd was used. Other steps were the same.

[0131] In the S42 process, a single-channel die extrusion is used, without a double-layer structure, and the other steps are the same.

[0132] Comparative Example 3

[0133] The composition and preparation process are the same as in Example 1, except that:

[0134] In the preparation process, S12 and S13 are removed from S1, and only Ag@ZIF-8 is retained. There is no PDA-peptide chain modification. The other steps are the same.

[0135] In the preparation process, Pt and Pd are directly loaded in S14, which has no enzyme-pH response capability, and the other steps are the same.

[0136] Based on Examples 1-4 and Comparative Examples 1-3, samples of the antibacterial thermoplastic polyurethane composite material prepared by S42 were taken for antibacterial performance testing: the thin-film sample was placed in Escherichia coli culture medium and cultured for 24 hours using the shaking inoculation method, and the supernatant was taken to determine the colony forming units;

[0137] Based on Examples 1-4 and Comparative Examples 1-3, samples of the antibacterial thermoplastic polyurethane composite material prepared by S42 were taken and the response release rate was tested: the stimulation conditions were pH 5.5, temperature 37°C, enzyme type lipase, enzyme concentration 2U / mL, test duration 48h, and buffer system SBF simulated body fluid.

[0138] Based on Examples 1-4 and Comparative Examples 1-3, multiple samples of the antibacterial thermoplastic polyurethane composite material prepared by S42 were taken and subjected to LOI, tensile strength, and elongation at break tests. The LOI reference standard GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method", and the reference standards for tensile strength and elongation at break are GB / T 1040.1-2018 "Determination of Tensile Properties of Plastics". The specific test results are shown in Table 1.

[0139] Table 2 Comparison of results between Examples 1-4 and Comparative Examples 1-3

[0140]

[0141]

[0142] Note: LOI stands for Limiting Oxygen Index, which refers to the minimum oxygen concentration required for a material to sustain combustion in a nitrogen-oxygen mixture.

[0143] Note: The response release rate is the release rate under stimulation conditions, which is the effective amount of antibacterial agent / the total amount of material loaded.

[0144] The comparison results above show that Example 1 has the best overall performance, with tensile strength close to that of pure TPU in Comparative Example 1, indicating that Example 1 achieves high functionality while maintaining basic mechanical properties. Examples 2 to 4 have slightly lower overall performance than Example 1, indicating that excellent extraction results were still achieved under a wide range of parameter variations. The deletion of the bifunctional monomer preparation in Comparative Example 1 resulted in the failure of both antibacterial and flame-retardant properties. Comparative Example 2 eliminated the gradient design and adopted single-channel die extrusion, which led to the destruction of the uniform dispersion strength of the bifunctional monomer grafted TPU and Ag@ZIF-8@PDA-peptide / PtPd, resulting in the lack of surface enrichment effect. Comparative Example 3 has no PDA-peptide chain modification and no enzyme-pH response capability, resulting in the lowest response release rate.

[0145] In summary, the above embodiments and comparisons clearly demonstrate that the antibacterial thermoplastic polyurethane composite material provided by this invention significantly outperforms traditional solutions in terms of long-lasting antibacterial effect and high flame retardancy. This is attributed to the innovative construction of an enzyme-pH dual-responsive PDA-metal-organic framework, which solves the problem of weak silver ion retention in the TPU matrix through ZIF-8 channel confinement, PDA-peptide chain intelligent silver locking, and Pt and Pd reduction and enhancement. Furthermore, the antibacterial and flame retardant properties of the material are enhanced by bifunctional monomers, and the distribution of functional components within the material is optimized through gradient structure design, effectively solving the silver-phosphorus antagonism problem in existing technologies. The technical solution of this invention is reasonable, the preparation method is feasible, and the obtained product exhibits excellent performance.

Claims

1. An antibacterial thermoplastic polyurethane composite material, characterized in that: It comprises the following components: antibacterial carrier Ag@ZIF-8@PDA-peptide / PtPd, and bifunctional monomer grafted TPU matrix; it also comprises the following structure: a bilayer gradient structure.

2. The antibacterial thermoplastic polyurethane composite material according to claim 1, characterized in that: The antibacterial carrier Ag@ZIF-8@PDA-peptide / PtPd consists of ZIF-8 loaded with AgNPs as the core sustained-release unit, PDA superimposed with enzyme-responsive peptide chains as the intermediate layer, and Pt and Pd bimetallic nanozymes as the surface catalytic enhancement layer. The bifunctional monomer is grafted onto the TPU matrix, and the bifunctional monomer is prepared by covalent bonding of DOPO-quaternary ammonium salt.

3. The antibacterial thermoplastic polyurethane composite material according to claim 1, characterized in that: The antibacterial carrier Ag@ZIF-8@PDA-peptide / PtPd enhances the TPU matrix's ability to block silver ions by surface modification with bimetallic nanoenzymes Pt and Pd and dual-response control of release efficiency by ZIF-8 and PDA-peptide chains. The bifunctional monomer grafted onto the TPU matrix imparts flame-retardant properties to the material through DOPO aldehyde modification; increases antibacterial anchor points and grafting sites through Schiff base formation and reduction; and avoids silver phosphate precipitation by isolating DOPO from silver ions.

4. The antibacterial thermoplastic polyurethane composite material according to claim 1, characterized in that: The dual-layer gradient structure consists of a surface layer and an inner layer. The surface layer contains 3 to 6 antibacterial carriers per 100 parts of TPU base material, while the inner layer contains 0.5 to 3 antibacterial carriers per 100 parts of TPU base material. The thickness ratio of the surface layer to the inner layer is 1:

9.

5. The method for preparing the antibacterial thermoplastic polyurethane composite material according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Enzyme-pH dual-responsive PDA-metal-organic framework structure; S11: Disperse ZIF-8 in AgNO3 solution, vacuum disperse for 30 min, then add ascorbic acid, and reduce at 40℃ in the dark for 3 h to obtain Ag@ZIF-8; S12: Disperse Ag@ZIF-8 in Tris-HCl buffer, add DA-HCl, and stir under N2 protection in the dark for 24 h. Centrifuge to obtain Ag@ZIF-8@PDA. S13: The peptide chain, NHS, and EDC were shaken at room temperature for 30 min, and then Ag@ZIF-8@PDA was added, wherein the molar ratio of peptide chain to Ag@ZIF-8@PDA was 1:8 to 1:

12. The mixture was reacted at 4℃ for 12 h to obtain Ag@ZIF-8@PDA-peptide. S14: Disperse Ag@ZIF-8@PDA-peptide in deionized water, then add chloroplatinic acid and palladium chloride, and react with pulsed sonication; then add NaBH4 dropwise, react at 35℃ for 1 h, and centrifuge to obtain Ag@ZIF-8@PDA-peptide / PtPd; add sodium citrate, stir at room temperature for 2 h, and obtain surface passivated Ag@ZIF-8@PDA-peptide / PtPd; S2: Preparation of bifunctional monomers; S21: Under nitrogen protection, DOPO and terephthalaldehyde were added to the reactor, then heated to 120°C and mechanically stirred at 300 rpm for 10 h. The mixture was then cooled to room temperature, recrystallized from ethanol, and dried under vacuum at 80°C for 12 h to obtain DOPO-aldehyde. S22: Dissolve DOPO-aldehyde and 6-aminohexanol in methanol and stir at 25°C for 2 hours to generate a yellow Schiff base; then cool to 0°C in an ice bath and add NaBH4 in batches while controlling the temperature to be less than 10°C and the pH to be 7; after the addition is complete, heat to 25°C and continue stirring for 2 hours, then remove methanol by rotary evaporation, wash with water three times, and dry under vacuum to obtain secondary amino alcohol. S23: Dissolve secondary amino alcohol in DMF, add bromododecane, and stir at 80°C for 24 h; then add dimethylamine aqueous solution dropwise and continue the reaction for 6 h; then cool to 60°C, add diethyl ether to precipitate the product, filter, and finally wash with diethyl ether three times, and vacuum dry at 60°C for 48 h to obtain a bifunctional monomer with antibacterial and flame-retardant properties. S3: Bifunctional monomer-grafted TPU was prepared by drying TPU particles under vacuum at 80°C for 12 hours using 100 parts of TPU base material as a reference. Then, in a nitrogen-protected reactor, the dried TPU and DMF solvent were added, and the mixture was heated to 90°C and stirred for 2 hours to dissolve. Next, a DMF solution of bifunctional monomers was added dropwise, with a TPU:monomer ratio of 1:0.05 to 1:0.

15. DBTDL catalyst was then added, and the reaction was carried out at 90-100°C for 6-8 hours. Finally, the reaction solution was poured into ice-cold methanol to precipitate the product. After filtration, the product was washed three times with methanol and dried under vacuum at 60°C for 24 hours to obtain bifunctional monomer-grafted TPU. S4: Two-layer gradient structure design; S41: Preparation of inner and outer layer materials. Inner layer material preparation: Based on 100 parts of TPU base material, 0.5-3 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-mixed with 1 part of bifunctional monomer-grafted TPU. Outer layer material preparation: Based on 100 parts of TPU base material, 3-6 parts of Ag@ZIF-8@PDA-peptide / PtPd prepared in S1 are pre-mixed with 1 part of bifunctional monomer-grafted TPU. Then, 100 parts of TPU base material, prepared in S3... Five to five parts of bifunctional monomer-grafted TPU were melt-blended using a twin-screw extruder. The twin-screw extruder had four zones: zone one, zone two, zone three, and zone four. The TPU was fed into the main feed port and melt-plasticized in zones one and two. The dry-blended products of the surface layer and the inner layer were injected into the feed port of zone three. Volatile substances were removed by applying a vacuum of -0.08 MPa in zone four. The melt was cooled in a water bath, stretched into strips, granulated, and finally vacuum-dried at 40°C for 12 hours to obtain inner-layer modified TPU masterbatch and surface-layer modified TPU masterbatch. S42: A dual-channel flat extrusion die is used, with independent channels for the inner and outer layers to transport the surface material and the inner material respectively. A confluence zone is set in front of the die exit so that the two layers of melt overlap in a viscous flow state to obtain a double-layer sheet with a total thickness of 0.5 mm, of which the surface layer accounts for about 50 μm. Then, a three-stage cooling system is used for cooling and shaping. The sheet is then wound up by a traction machine and cut for sampling.

6. The method for preparing an antibacterial thermoplastic polyurethane composite material according to claim 5, characterized in that: The ZIF-8 described in S11 is dispersed in an AgNO3 solution, wherein the mass ratio of ZIF-8 to AgNO3 is 1:0.15 to 1:0.25; The ascorbic acid described in S11 has a molar ratio of silver ions to ascorbic acid of 1:1.8 to 1:2.

2. The centrifugation described in S12 has the following parameters: rotation speed 8000~10000rpm, duration 10~15min, and temperature 4~10℃. The peptide chain, NHS, and EDC mentioned in S13 have a molar ratio of peptide chain:NHS:EDC of 1:2.5:5 to 1:5:

10. The molar ratio of chloroplatinic acid and palladium chloride described in S14 is 2.5:1 to 3.5:1; The pulsed ultrasound described in S14 has the following parameter settings: power: 100-150W, duration: 8-12min, on for 2s / off for 1s. The addition of NaBH4 described in S14 involves a molar ratio of Pt to Pd:NaBH4 of 1:4 to 1:

6.

7. The method for preparing an antibacterial thermoplastic polyurethane composite material according to claim 5, characterized in that: The molar ratio of DOPO to terephthalaldehyde described in S21 is in the range of 1:1.05 to 1:1.

10. The DOPO-aldehyde and 6-aminohexanol described in S22 are soluble in methanol, wherein the molar ratio of DOPO-aldehyde to 6-aminohexanol is 1:1.1 to 1:1.2, and the solid-liquid ratio of the two to methanol is 1:

10. The addition of NaBH4 as described in S22 has a molar ratio of 1.8:1 to the Schiff base. The bromododecane described in S23 has a molar ratio of secondary amino alcohol to bromododecane of 1:1.2 to 1:1.

5. The dimethylamine aqueous solution described in S23 has a molar ratio of secondary amino alcohol to dimethylamine aqueous solution of 1:1.5 to 1:2.

0.

8. A method for preparing an antibacterial thermoplastic polyurethane composite material according to claim 5, characterized in that: The dry TPU and DMF solvent described in S3 have a mass-to-volume ratio of 1:5; The DMF solution of the bifunctional monomer described in S3 has a TPU:bifunctional monomer ratio of 1:0.05 to 1:0.

15. The DBTDL catalyst described in S3 has a TPU to DBTDL ratio of 1:0.01 to 1:0.

05.

9. A method for preparing an antibacterial thermoplastic polyurethane composite material according to claim 5, characterized in that: The twin-screw extruder described in S41 has the following parameter settings: Zone 1 temperature 160-170℃, Zone 2 temperature 175-180℃, Zone 3 temperature 180-185℃, Zone 4 temperature 185-190℃, Die head temperature 175-180℃, Zone 1, Zone 2, and Zone 3 speeds 50-80 rpm, and Zone 4 speed 100-120 rpm.

10. A method for preparing an antibacterial thermoplastic polyurethane composite material according to claim 5, characterized in that: The dual-channel flat extrusion die described in S42 has the following parameter settings: extrusion temperature of 175-180℃, extrusion speed ratio of 1:10, surface material melt pressure of 8-10MPa, inner material melt pressure of 6-8MPa, surface material die temperature gradient of 178℃ for the upper channel, and inner material die temperature gradient of 176℃ for the lower channel. The cooling and shaping described in S42 has the following parameter settings: First-stage cold air knife: wind speed 15-30m / s, temperature 5-10℃; Second-stage water bath: water flow rate 0.3-0.8m / s, temperature 10-15℃; Third-stage calendering roller: temperature 35-45℃, pressure 0.3-0.8MPa.

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