Antibacterial self-cleaning PBS-based composite material and preparation method thereof

Abstract

The application discloses an antibacterial self-cleaning PBS-based composite material and a preparation method thereof, and relates to the technical field of polybutylene succinate. The composite material is composed of the following components: PBS resin, PBAT resin, talcum powder, nano-titanium dioxide, zinc oxide, antibacterial powder, a compatilizer, a lubricant and an antioxidant. The particle size range, surface treatment mode and distribution state of the nano-titanium dioxide, zinc oxide and antibacterial powder in the PBS matrix are synergistically controlled, and a stable interface bonding structure is constructed in combination with the compatilizer, so that the functional components form an active region with continuity and high exposure on the material surface, the synergistic improvement of the antibacterial performance and the self-cleaning performance is realized, the problems of easy agglomeration of the functional filler, low utilization rate of active sites and unstable functional effect in the prior art are significantly improved, and the surface cleaning maintenance ability and long-term use reliability of the material in a complex use environment are improved.

Description

Technical Field

[0001] This invention relates to the field of polybutylene succinate technology, specifically to an antibacterial self-cleaning PBS-based composite material and its preparation method. Background Technology

[0002] Polybutylene succinate (PBS), as a biodegradable polyester material, possesses excellent mechanical properties, biodegradability, and processing performance, and has been widely used in packaging materials, agricultural films, and disposable products. However, PBS itself has a high surface energy, making it prone to adsorbing dust, oil, and microorganisms. In practical use, this can easily lead to contamination and bacterial growth, limiting its application in scenarios with high hygiene requirements. In existing technologies, antibacterial agents or photocatalytic materials (such as titanium dioxide) are typically added to the PBS matrix to impart antibacterial or self-cleaning properties to the material. However, this approach still suffers from several shortcomings: Firstly, most solutions involve adding functional fillers through simple physical mixing, lacking effective control over filler particle size, dispersion state, and interfacial structure. This leads to the functional components easily agglomerating or becoming embedded within the matrix, making it difficult to form effective active sites on the material surface. Consequently, the antibacterial and self-cleaning effects are not consistently maintained over the long term. Secondly, there is a lack of synergistic design between different functional fillers. Antibacterial and photocatalytic components often act independently, failing to form an effective spatial distribution relationship and interfacial coupling structure. This results in low functional synergy efficiency and may also adversely affect the material's mechanical and processing properties. Therefore, there is an urgent need for a PBS-based composite material and its preparation method that can achieve synergistic antibacterial and self-cleaning functions while ensuring the material's mechanical and processing properties. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an antibacterial, self-cleaning PBS-based composite material and its preparation method, thereby resolving the problems mentioned in the background section.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an antibacterial, self-cleaning PBS-based composite material, the composite material being composed of the following formulation in parts by weight: 70-85 parts of PBS resin; 15-25 parts of PBAT resin; 10-18 parts talc; 3-6 parts of nano-titanium dioxide; 2-4 parts zinc oxide; 1-2 parts antibacterial powder; 2-4 parts compatibilizer; Lubricant 0.5 to 1 part; Antioxidant 0.3 to 0.8 parts.

[0005] To further optimize this technical solution, the nano-titanium dioxide has the crystal form of anatase or anatase / rutile mixture, wherein the mass ratio of anatase is 60% to 95%. The nano-titanium dioxide has an average particle size of 10-40 nm and a specific surface area of ​​50-200 m² / g, and its surface is treated with a silane coupling agent, wherein the amount of the silane coupling agent added is 0.5%-3% of the mass of the nano-titanium dioxide.

[0006] To further optimize this technical solution, the average particle size of the zinc oxide is 20-100 nm, its crystal form is hexagonal wurtzite structure, and the surface of the zinc oxide is coated and modified by organic acid or silane coupling agent, with a coating layer thickness of 1-10 nm.

[0007] To further optimize this technical solution, the antibacterial powder is an inorganic antibacterial powder, which is selected from one or two of silver-based antibacterial powder, zinc-based antibacterial powder, or composite antibacterial powder; The antibacterial powder has an average particle size of 0.2–2 μm and its surface is loaded with active metal ions, with a metal ion content of 0.1%–2%.

[0008] To further optimize this technical solution, the compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4 ; The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin, and inorganic fillers, and the thickness of this interfacial layer is 5–50 nm.

[0009] To further optimize this technical solution, the average particle size of the talc powder is 2-10 μm, the flake diameter-to-thickness ratio is 5-20, and its surface is treated with a coupling agent; the talc powder is oriented in the composite material along the melt flow direction, with an orientation degree of 0.3-0.8, and forms a layered barrier structure.

[0010] To further optimize this technical solution, the PBS resin and PBAT resin form a two-phase structure of continuous phase and dispersed phase in the composite material, wherein the PBS resin is the continuous phase and the PBAT resin exists in the form of dispersed phase with a particle size of 0.5 to 5 μm.

[0011] A method for preparing an antibacterial, self-cleaning PBS-based composite material, based on the aforementioned composite material, includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; S2. Construct a functional powder premixing system based on the pretreatment in S1; S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5.

[0012] To further optimize this technical solution, in step S4, the temperature of each section of the twin-screw extruder is controlled sequentially from the feeding section to the die head section as 110-140℃, 130-155℃, 145-165℃, 150-170℃, and 150-175℃.

[0013] To further optimize this technical solution, in step S5, after the composite material is melt-extruded, a micro-nano composite rough structure is formed on its surface, wherein the micro-rough structure has a scale of 1 to 10 μm and the nano-rough structure has a scale of 50 to 300 nm.

[0014] Compared with the prior art, the present invention provides an antibacterial self-cleaning PBS-based composite material and its preparation method, which has the following beneficial effects: This antibacterial and self-cleaning PBS-based composite material and its preparation method synergistically regulate the particle size range, surface treatment method, and distribution state of nano-titanium dioxide, zinc oxide, and antibacterial powder in the PBS matrix, and construct a stable interfacial bonding structure with a compatibilizer. This allows the functional components to form continuous and highly exposed active regions on the material surface, thereby achieving a synergistic improvement in antibacterial and self-cleaning properties without significantly reducing the material's mechanical properties. This significantly improves the problems of easy agglomeration of functional fillers, low utilization rate of active sites, and unstable functional effects in existing technologies, while also improving the material's ability to maintain surface cleanliness and long-term reliability in complex operating environments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart of a method for preparing an antibacterial self-cleaning PBS-based composite material proposed in this invention. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0019] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0020] An antibacterial, self-cleaning PBS-based composite material, said composite material being composed of the following formulation in parts by weight: 70-85 parts of PBS resin; as the main matrix resin of the composite material, it provides basic mechanical properties, molding properties and biodegradability, and constitutes the basis of the continuous phase structure of the material.

[0021] 15-25 parts of PBAT resin; used to improve the toughness and ductility of the PBS system, reduce material brittleness, and enhance melt flowability and impact resistance during processing.

[0022] Talc powder 10-18 parts; as an inorganic filler and reinforcing component, it improves the rigidity, dimensional stability and heat deformation resistance of the material, while also providing some support for the internal structure of the material.

[0023] 3-6 parts of nano-titanium dioxide; as a photocatalytic functional component, it forms active sites on the surface of the material to decompose organic pollutants and achieve self-cleaning function.

[0024] Zinc oxide 2-4 parts; as an auxiliary photocatalytic and antibacterial component, it works synergistically with nano-titanium dioxide to enhance the antibacterial properties of the material and improve its self-cleaning efficiency.

[0025] 1-2 parts of antibacterial powder; as the main antibacterial functional component, it inhibits bacterial growth by releasing active ions or through surface contact, thereby achieving the material's continuous antibacterial effect.

[0026] 2-4 parts compatibilizer; used to improve the interfacial compatibility between PBS resin, PBAT resin and inorganic filler, enhance the interfacial bonding strength, and ensure the overall stability of the material performance.

[0027] Lubricant 0.5 to 1 part; used to reduce the frictional resistance of materials during processing, improve melt flowability, and enhance the stability of extrusion or injection molding.

[0028] Antioxidant 0.3-0.8 parts; used to inhibit thermo-oxidative aging of materials during high-temperature processing and use, maintain the stability of polyester molecular chains, and extend the service life of materials.

[0029] The nano-titanium dioxide has an anatase or anatase / rutile mixed crystal form, with anatase accounting for 60%–95% of the mass. The average particle size of the nano-titanium dioxide is 10–40 nm, and the specific surface area is 50–200 m² / g. Its surface is treated with a silane coupling agent, with the amount of silane coupling agent added being 0.5%–3% of the mass of the nano-titanium dioxide. The treated nano-titanium dioxide is distributed in the composite material in a monodisperse or weakly aggregated state, with aggregate particle sizes not exceeding 200 nm, thereby forming a continuously distributed photocatalytic active site structure on the material surface.

[0030] The zinc oxide has an average particle size of 20–100 nm and a hexagonal wurtzite crystal structure. The surface of the zinc oxide is modified by coating with an organic acid or silane coupling agent, with a coating thickness of 1–10 nm. The zinc oxide forms a composite dispersion system with nano-titanium dioxide in the composite material, exhibiting a point-like embedded or interfacial distribution in its microstructure. The average spacing between the two is controlled within the range of 50–300 nm, thereby constructing a stable synergistic antibacterial activity region.

[0031] The antibacterial powder is an inorganic antibacterial powder, selected from one or two of silver-based antibacterial powder, zinc-based antibacterial powder, or composite antibacterial powder; the average particle size of the antibacterial powder is 0.2-2 μm, and its surface is loaded with active metal ions, with a metal ion content of 0.1%-2%. The antibacterial powder exists in a discrete distribution in the composite material, and is preferentially distributed in the surface area of ​​the material, with a surface enrichment depth of 0.5-10 μm inward from the material surface, thereby continuously releasing antibacterial active components during use.

[0032] The compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4 The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin, and inorganic fillers, with a thickness of 5–50 nm. Through the action of the compatibilizer, the interfacial peel strength between the inorganic and organic phases is increased by 20%–60%, thereby maintaining the mechanical property stability of the composite material.

[0033] The talc powder has an average particle size of 2–10 μm and a flake diameter-to-thickness ratio of 5–20, and its surface is treated with a coupling agent. The talc powder is oriented along the melt flow direction in the composite material, with an orientation degree of 0.3–0.8, forming a layered barrier structure. This structure creates multiple interfacial reflection paths within the material, thereby extending the residence and diffusion path of contaminants on the material surface and improving self-cleaning efficiency.

[0034] The PBS resin and PBAT resin form a two-phase structure in the composite material, consisting of a continuous phase and a dispersed phase. The PBS resin is the continuous phase, while the PBAT resin exists as a dispersed phase with a particle size of 0.5–5 μm. A stable interfacial transition layer is formed at the interface between the two phases under the action of a compatibilizer, thereby providing a stable distribution carrier for the inorganic antibacterial components while ensuring the material's toughness.

[0035] After being melt-extruded, the composite material forms a micro-nano composite rough structure on its surface, wherein the micro-rough structure has a scale of 1–10 μm and the nano-rough structure has a scale of 50–300 nm. The rough structure is formed by the enrichment and local exposure of nano-titanium dioxide, zinc oxide and antibacterial powder on the surface, and its surface roughness Ra is 0.5–3 μm, thereby constructing a surface morphology that is conducive to reducing pollutant adhesion and photocatalytic decomposition.

[0036] Reference Figure 1 A method for preparing an antibacterial, self-cleaning PBS-based composite material, based on the aforementioned composite material, includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; First, PBS and PBAT resins are dried separately to reduce the free water content in the resins and inhibit hydrolytic degradation during subsequent melt extrusion. Preferably, the drying temperature of PBS resin is controlled at 70–90°C, and the drying time is 4–8 hours; the drying temperature of PBAT resin is controlled at 60–85°C, and the drying time is 3–6 hours. Simultaneously, talc, nano-titanium dioxide, zinc oxide, and antibacterial powder are pre-dried, preferably at 80–110°C, for 2–5 hours, to remove surface-adsorbed water and reduce powder agglomeration during subsequent mixing. For nano-titanium dioxide, zinc oxide, and antibacterial powder, a small amount of coupling agent is preferably added before or after drying for surface pretreatment, forming a surface layer on the powder surface that facilitates bonding with the polyester matrix; the coupling agent can be a silane-based treatment agent, and its addition amount is preferably 0.5%–3% of the corresponding powder mass. This step ensures that the resin matrix has a relatively stable molecular weight in the molten state and improves the uniformity of the dispersion of functional powders in the matrix, thus providing a prerequisite for obtaining a surface structure that combines antibacterial and self-cleaning activities.

[0037] S2. Construct a functional powder premixing system based on the pretreatment in S1; After the raw materials are dried and pretreated, nano-titanium dioxide, zinc oxide, antibacterial powder, and a portion of talc are premixed in a high-speed mixer to ensure a relatively stable composite dispersion of the various functional powders before they enter the resin melt. Preferably, the high-speed mixing speed is controlled at 500–1500 r / min, the mixing time at 5–20 min, and the mixing temperature at 40–80°C to avoid localized powder agglomeration due to excessively high temperatures. More preferably, 20%–50% of the total compatibilizer can be added during this premixing stage to allow the compatibilizer to adsorb onto the surface of the inorganic powders, forming a preliminary interfacial transition layer. This reduces the risk of secondary agglomeration of nano-titanium dioxide and zinc oxide under subsequent melt shear conditions.

[0038] S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. The dried PBS resin, PBAT resin, remaining talc, remaining compatibilizer, lubricant, antioxidant, and the functional powder premix system obtained from S2 are added to a mixer according to the formula ratio for low-to-medium speed compound mixing to obtain a uniform feedstock for extrusion processing. Preferably, the mixing speed is first increased to 100-400 r / min for 2-5 min to allow initial contact between resin particles and powder, and then increased to 400-1000 r / min for 5-15 min to ensure uniform coating of the powder onto the surface of the resin particles. The mixing temperature is preferably controlled at 50-90℃ to prevent premature softening and agglomeration of the resin. In this step, the lubricant is mainly used to improve the conveying stability of the feedstock in the extrusion equipment, the antioxidant is mainly used to reduce the thermo-oxidative degradation rate of polyester segments in the molten state, and the compatibilizer further promotes the interfacial bonding between PBS resin, PBAT resin, and inorganic powder. Through this step, the various raw materials can achieve uniform distribution on a macroscopic scale, providing stable feeding conditions for the next step of twin-screw melt blending.

[0039] S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; The uniform feedstock obtained in S3 is fed into a twin-screw extruder for segmented melting, dispersion, and plasticization to form a stable organic-inorganic composite structure within the polyester matrix and to construct microscopic active regions with antibacterial and self-cleaning functions on the material surface. Preferably, the temperatures of each section of the twin-screw extruder, from the feeding section to the die head section, are controlled sequentially as follows: 110–140°C, 130–155°C, 145–165°C, 150–170°C, and 150–175°C; the screw speed is controlled as 150–400 r / min; and the average residence time of the material in the barrel is controlled as 30–120 s. More preferably, at least one strong shear dispersion zone and one low shear integration zone are set during the melt plasticization process: the strong shear dispersion zone is used to break up local agglomerates of nano-titanium dioxide, zinc oxide, and antibacterial powder; and the low shear integration zone is used to prevent the dispersed functional particles from becoming unstable and agglomerated again due to excessive shear. During this stage, the compatibilizer comes into full contact with the resin molecular chains and powder surface, gradually forming an interfacial bonding layer, which enables the functional particles to form a relatively stable embedded state or interfacial adjacent state in the PBS continuous phase and PBAT dispersed phase.

[0040] S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. The molten strip extruded from the S4 die head is cooled and shaped using a cooling water tank or cold air system, and then pelletized to obtain composite material granules; alternatively, depending on the application requirements, the product can be directly formed using sheet extrusion, casting, or injection molding. Preferably, a staged cooling method is used in the cooling stage, first performing preliminary shaping in an environment of 20–40°C, and then completing subsequent stabilization at room temperature to reduce stress concentration caused by rapid cooling. For products requiring improved surface self-cleaning effect, it is preferable to control the mold surface temperature or traction speed so that nano-titanium dioxide, zinc oxide, and antibacterial powder form a moderately enriched exposed structure near the surface; the thickness of the enriched surface layer is preferably controlled to be 1–20 μm. After granulation, the material moisture content is preferably controlled below 0.3%, and the particle size is preferably controlled to be 2–5 mm to facilitate subsequent secondary processing.

[0041] S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5; The granulated composite material particles are sieved to remove excessively large particles, abnormal particles, and powdery debris, and then sealed and stored in moisture-proof packaging. Preferably, a slow-release annealing treatment at 40–60°C for 2–6 hours can be performed to further release residual stress within the material and promote the stabilization of the phase interface structure between PBS resin and PBAT resin. For directly molded sheets or products, surface cleaning and short-term light activation treatment can also be performed after molding to more fully expose the nano-titanium dioxide active sites on the surface. After this step, the obtained PBS-based composite material can maintain relatively stable antibacterial activity and surface self-cleaning properties during subsequent storage, transportation, and use, while avoiding performance degradation caused by fluctuations in particle moisture content, uneven release of internal stress, or surface contamination.

[0042] Example 1: An antibacterial, self-cleaning PBS-based composite material comprising the following formulation: 70 parts PBS resin; 15 parts PBAT resin; 10 parts talc; 3 parts nano titanium dioxide; 2 parts zinc oxide; 1 part antibacterial powder; 2 parts compatibilizer; 0.5 parts lubricant; 0.3 parts antioxidant.

[0043] The nano-titanium dioxide has an anatase crystal form, with anatase accounting for 60% to 95% of the mass. The average particle size of the nano-titanium dioxide is 10 to 40 nm, the specific surface area is 50 to 200 m² / g, and its surface is treated with a silane coupling agent, with the amount of silane coupling agent added being 0.5% to 3% of the mass of the nano-titanium dioxide.

[0044] The zinc oxide has an average particle size of 20-100 nm, a hexagonal wurtzite structure, and its surface is modified by coating with organic acid or silane coupling agent, with a coating thickness of 1-10 nm.

[0045] The antibacterial powder is a silver-based antibacterial powder; the average particle size of the antibacterial powder is 0.2-2 μm, and its surface is loaded with active metal ions, with a metal ion content of 0.1%-2%.

[0046] The compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4 The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin and inorganic fillers, and the thickness of this interfacial layer is 5-50 nm.

[0047] The talc powder has an average particle size of 2-10 μm, a flake diameter-to-thickness ratio of 5-20, and its surface is treated with a coupling agent; the talc powder is oriented in the composite material along the melt flow direction, with an orientation degree of 0.3-0.8, and forms a layered barrier structure.

[0048] The PBS resin and PBAT resin form a two-phase structure of continuous phase and dispersed phase in the composite material, wherein the PBS resin is the continuous phase and the PBAT resin exists in the form of dispersed phase with a particle size of 0.5 to 5 μm.

[0049] After the composite material is melt-extruded, a micro-nano composite rough structure is formed on its surface, wherein the micro-rough structure has a scale of 1 to 10 μm and the nano-rough structure has a scale of 50 to 300 nm.

[0050] A method for preparing an antibacterial, self-cleaning PBS-based composite material, based on the aforementioned composite material, includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; First, PBS resin and PBAT resin were dried separately. The drying temperature of PBS resin was controlled at 80℃ for 6 hours; the drying temperature of PBAT resin was controlled at 72℃ for 4.5 hours. Simultaneously, talc powder, nano-titanium dioxide, zinc oxide, and antibacterial powder were pre-dried at 95℃ for 3.5 hours. For nano-titanium dioxide, zinc oxide, and antibacterial powder, a silane coupling agent (KH550) was added for surface pretreatment before drying, at an amount of 1.5% of the corresponding powder mass.

[0051] S2. Construct a functional powder premixing system based on the pretreatment in S1; After the raw materials were dried and pretreated, nano-titanium dioxide, zinc oxide, antibacterial powder, and a portion of talc powder were added to a high-speed mixer for premixing. The high-speed mixer speed was controlled at 1000 r / min, the mixing time was 12 min, and the mixing temperature was 60℃. During this premixing stage, 35% of the total amount of compatibilizer was added to allow the compatibilizer to be adsorbed onto the surface of the inorganic powder.

[0052] S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. The dried PBS resin, PBAT resin, remaining talc, remaining compatibilizer, lubricant, antioxidant, and the functional powder premix system obtained from S2 were added to a mixer according to the formula ratio for low-to-medium speed compound mixing. First, the mixture was mixed at 250 rpm for 3 minutes, then increased to 700 rpm for 10 minutes; the mixing temperature was controlled at 70℃. Calcium stearate was used as the lubricant, hindered phenolic antioxidant 1010 was used as the antioxidant, and maleic anhydride-grafted polyester was used as the compatibilizer.

[0053] S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; The uniform feedstock obtained from S3 is fed into a twin-screw extruder for staged melting, dispersion, and plasticizing. The temperatures of each section of the twin-screw extruder, from the feeding section to the die head section, are controlled sequentially at 125℃, 142℃, 155℃, 160℃, and 162℃, respectively. The screw speed is controlled at 275 r / min, and the average residence time of the material in the barrel is controlled at 75 s. A high-shear dispersion zone and a low-shear integration zone are set up during the melting and plasticizing process.

[0054] S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. The molten strip extruded from the S4 die head is cooled and shaped in a cooling water tank, and then granulated to obtain composite material particles; alternatively, it can be extruded as a sheet to form the product. A staged cooling method is used in the cooling stage: initial shaping is performed at 30°C, followed by stabilization at room temperature. By controlling the die surface temperature and traction speed, nano-titanium dioxide, zinc oxide, and antibacterial powder are distributed in the near-surface area, with a surface enrichment layer thickness of 10 μm. After granulation, the material moisture content is controlled at 0.3%, and the particle size is controlled at 3.5 mm.

[0055] S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5; The granulated composite material particles were sieved to remove excessively large particles, abnormal particles, and powdery debris, and then sealed in moisture-proof packaging for storage. A slow-release annealing treatment was performed at 50°C for 4 hours to stabilize the internal structure of the material. For directly molded sheets or products, surface cleaning and light treatment were performed after molding to stabilize the surface condition. After this treatment, the obtained PBS-based composite material remained stable during storage and use.

[0056] Example 2: An antibacterial, self-cleaning PBS-based composite material comprising the following formulation: PBS resin 77.5 parts; PBAT resin 20 parts; talc 14 parts; nano titanium dioxide 4.5 parts; zinc oxide 3 parts; antibacterial powder 1.5 parts; compatibilizer 3 parts; lubricant 0.75 parts; antioxidant 0.55 parts.

[0057] The nano-titanium dioxide has an anatase crystal form, with anatase accounting for 60% to 95% of the mass. The average particle size of the nano-titanium dioxide is 10 to 40 nm, the specific surface area is 50 to 200 m² / g, and its surface is treated with a silane coupling agent, with the amount of silane coupling agent added being 0.5% to 3% of the mass of the nano-titanium dioxide.

[0058] The zinc oxide has an average particle size of 20-100 nm, a hexagonal wurtzite structure, and its surface is modified by coating with organic acid or silane coupling agent, with a coating thickness of 1-10 nm.

[0059] The antibacterial powder is a silver-based antibacterial powder; the average particle size of the antibacterial powder is 0.2-2 μm, and its surface is loaded with active metal ions, with a metal ion content of 0.1%-2%.

[0060] The compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4 The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin, and inorganic fillers, and the thickness of this interfacial layer is 5-50 nm.

[0061] The talc powder has an average particle size of 2-10 μm, a flake diameter-to-thickness ratio of 5-20, and its surface is treated with a coupling agent; the talc powder is oriented in the composite material along the melt flow direction, with an orientation degree of 0.3-0.8, and forms a layered barrier structure.

[0062] The PBS resin and PBAT resin form a two-phase structure of continuous phase and dispersed phase in the composite material, wherein the PBS resin is the continuous phase and the PBAT resin exists in the form of dispersed phase with a particle size of 0.5 to 5 μm.

[0063] After the composite material is melt-extruded, a micro-nano composite rough structure is formed on its surface, wherein the micro-rough structure has a scale of 1 to 10 μm and the nano-rough structure has a scale of 50 to 300 nm.

[0064] A method for preparing an antibacterial, self-cleaning PBS-based composite material, based on the aforementioned composite material, includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; First, PBS resin and PBAT resin were dried separately. The drying temperature of PBS resin was controlled at 80℃ for 6 hours; the drying temperature of PBAT resin was controlled at 72℃ for 4.5 hours. Simultaneously, talc powder, nano-titanium dioxide, zinc oxide, and antibacterial powder were pre-dried at 95℃ for 3.5 hours. For nano-titanium dioxide, zinc oxide, and antibacterial powder, a silane coupling agent (KH550) was added for surface pretreatment before drying, at an amount of 1.5% of the corresponding powder mass.

[0065] S2. Construct a functional powder premixing system based on the pretreatment in S1; After the raw materials were dried and pretreated, nano-titanium dioxide, zinc oxide, antibacterial powder, and a portion of talc powder were added to a high-speed mixer for premixing. The high-speed mixer speed was controlled at 1000 r / min, the mixing time was 12 min, and the mixing temperature was 60℃. During this premixing stage, 35% of the total amount of compatibilizer was added to allow the compatibilizer to be adsorbed onto the surface of the inorganic powder.

[0066] S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. The dried PBS resin, PBAT resin, remaining talc, remaining compatibilizer, lubricant, antioxidant, and the functional powder premix system obtained from S2 were added to a mixer according to the formula ratio for low-to-medium speed compound mixing. First, the mixture was mixed at 250 rpm for 3 minutes, then increased to 700 rpm for 10 minutes; the mixing temperature was controlled at 70℃. Calcium stearate was used as the lubricant, hindered phenolic antioxidant 1010 was used as the antioxidant, and maleic anhydride-grafted polyester was used as the compatibilizer.

[0067] S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; The uniform feedstock obtained from S3 is fed into a twin-screw extruder for staged melting, dispersion, and plasticizing. The temperatures of each section of the twin-screw extruder, from the feeding section to the die head section, are controlled sequentially at 125℃, 142℃, 155℃, 160℃, and 162℃, respectively. The screw speed is controlled at 275 r / min, and the average residence time of the material in the barrel is controlled at 75 s. A high-shear dispersion zone and a low-shear integration zone are set up during the melting and plasticizing process.

[0068] S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. The molten strip extruded from the S4 die head is cooled and shaped in a cooling water tank, and then granulated to obtain composite material particles; alternatively, it can be extruded as a sheet to form the product. A staged cooling method is used in the cooling stage: initial shaping is performed at 30°C, followed by stabilization at room temperature. By controlling the die surface temperature and traction speed, nano-titanium dioxide, zinc oxide, and antibacterial powder are distributed in the near-surface area, with a surface enrichment layer thickness of 10 μm. After granulation, the material moisture content is controlled at 0.3%, and the particle size is controlled at 3.5 mm.

[0069] S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5; The granulated composite material particles were sieved to remove excessively large particles, abnormal particles, and powdery debris, and then sealed in moisture-proof packaging for storage. A slow-release annealing treatment was performed at 50°C for 4 hours to stabilize the internal structure of the material. For directly molded sheets or products, surface cleaning and light treatment were performed after molding to stabilize the surface condition. After this treatment, the obtained PBS-based composite material remained stable during storage and use.

[0070] Example 3: An antibacterial, self-cleaning PBS-based composite material comprising the following formulation: 85 parts PBS resin; 25 parts PBAT resin; 18 parts talc; 6 parts nano titanium dioxide; 4 parts zinc oxide; 2 parts antibacterial powder; 4 parts compatibilizer; 1 part lubricant; 0.8 parts antioxidant.

[0071] The nano-titanium dioxide has an anatase crystal form, with anatase accounting for 60% to 95% of the mass. The average particle size of the nano-titanium dioxide is 10 to 40 nm, the specific surface area is 50 to 200 m² / g, and its surface is treated with a silane coupling agent, with the amount of silane coupling agent added being 0.5% to 3% of the mass of the nano-titanium dioxide.

[0072] The zinc oxide has an average particle size of 20-100 nm, a hexagonal wurtzite structure, and its surface is modified by coating with organic acid or silane coupling agent, with a coating thickness of 1-10 nm.

[0073] The antibacterial powder is a silver-based antibacterial powder; the average particle size of the antibacterial powder is 0.2-2 μm, and its surface is loaded with active metal ions, with a metal ion content of 0.1%-2%.

[0074] The compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin and inorganic fillers, and the thickness of this interfacial layer is 5-50 nm.

[0075] The talc powder has an average particle size of 2-10 μm, a flake diameter-to-thickness ratio of 5-20, and its surface is treated with a coupling agent; the talc powder is oriented in the composite material along the melt flow direction, with an orientation degree of 0.3-0.8, and forms a layered barrier structure.

[0076] The PBS resin and PBAT resin form a two-phase structure of continuous phase and dispersed phase in the composite material, wherein the PBS resin is the continuous phase and the PBAT resin exists in the form of dispersed phase with a particle size of 0.5 to 5 μm.

[0077] After the composite material is melt-extruded, a micro-nano composite rough structure is formed on its surface, wherein the micro-rough structure has a scale of 1 to 10 μm and the nano-rough structure has a scale of 50 to 300 nm.

[0078] A method for preparing an antibacterial, self-cleaning PBS-based composite material, based on the aforementioned composite material, includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; First, PBS resin and PBAT resin were dried separately. The drying temperature of PBS resin was controlled at 80℃ for 6 hours; the drying temperature of PBAT resin was controlled at 72℃ for 4.5 hours. Simultaneously, talc powder, nano-titanium dioxide, zinc oxide, and antibacterial powder were pre-dried at 95℃ for 3.5 hours. For nano-titanium dioxide, zinc oxide, and antibacterial powder, a silane coupling agent (KH550) was added for surface pretreatment before drying, at an amount of 1.5% of the corresponding powder mass.

[0079] S2. Construct a functional powder premixing system based on the pretreatment in S1; After the raw materials were dried and pretreated, nano-titanium dioxide, zinc oxide, antibacterial powder, and a portion of talc powder were added to a high-speed mixer for premixing. The high-speed mixer speed was controlled at 1000 r / min, the mixing time was 12 min, and the mixing temperature was 60℃. During this premixing stage, 35% of the total amount of compatibilizer was added to allow the compatibilizer to be adsorbed onto the surface of the inorganic powder.

[0080] S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. The dried PBS resin, PBAT resin, remaining talc, remaining compatibilizer, lubricant, antioxidant, and the functional powder premix system obtained from S2 were added to a mixer according to the formula ratio for low-to-medium speed compound mixing. First, the mixture was mixed at 250 rpm for 3 minutes, then increased to 700 rpm for 10 minutes; the mixing temperature was controlled at 70℃. Calcium stearate was used as the lubricant, hindered phenolic antioxidant 1010 was used as the antioxidant, and maleic anhydride-grafted polyester was used as the compatibilizer.

[0081] S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; The uniform feedstock obtained from S3 is fed into a twin-screw extruder for staged melting, dispersion, and plasticizing. The temperatures of each section of the twin-screw extruder, from the feeding section to the die head section, are controlled sequentially at 125℃, 142℃, 155℃, 160℃, and 162℃, respectively. The screw speed is controlled at 275 r / min, and the average residence time of the material in the barrel is controlled at 75 s. A high-shear dispersion zone and a low-shear integration zone are set up during the melting and plasticizing process.

[0082] S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. The molten strip extruded from the S4 die head is cooled and shaped in a cooling water tank, and then granulated to obtain composite material particles; alternatively, it can be extruded as a sheet to form the product. A staged cooling method is used in the cooling stage: initial shaping is performed at 30°C, followed by stabilization at room temperature. By controlling the die surface temperature and traction speed, nano-titanium dioxide, zinc oxide, and antibacterial powder are distributed in the near-surface area, with a surface enrichment layer thickness of 10 μm. After granulation, the material moisture content is controlled at 0.3%, and the particle size is controlled at 3.5 mm.

[0083] S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5; The granulated composite material particles were sieved to remove excessively large particles, abnormal particles, and powdery debris, and then sealed in moisture-proof packaging for storage. A slow-release annealing treatment was performed at 50°C for 4 hours to stabilize the internal structure of the material. For directly molded sheets or products, surface cleaning and light treatment were performed after molding to stabilize the surface condition. After this treatment, the obtained PBS-based composite material remained stable during storage and use.

[0084] Comparative Example 1: An antibacterial, self-cleaning PBS-based composite material comprising the following formulation: PBS resin 77.5 parts; PBAT resin 20 parts; talc 14 parts; compatibilizer 3 parts; lubricant 0.75 parts; antioxidant 0.55 parts.

[0085] This comparative example uses a formulation system that is basically the same as that in Example 2, but without the addition of nano-titanium dioxide, zinc oxide and antibacterial powder, to compare the performance differences before and after the overall introduction of the antibacterial self-cleaning functional components.

[0086] Comparative Example 2: An antibacterial, self-cleaning PBS-based composite material comprising the following formulation: PBS resin 77.5 parts; PBAT resin 20 parts; talc 14 parts; nano titanium dioxide 4.5 parts; compatibilizer 3 parts; lubricant 0.75 parts; antioxidant 0.55 parts.

[0087] Using a formulation system essentially the same as in Example 2, but without the addition of zinc oxide and antibacterial powder, the performance differences were compared when only the self-cleaning component was set without the composite antibacterial component.

[0088] The materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to the tests shown in Table 1 below to verify the actual effect of the materials.

[0089] Table 1

[0090] After conducting multiple tests on the composite materials prepared in Examples 1-3 and Comparative Examples 1-2, including tests on antibacterial properties, self-cleaning properties, mechanical properties, and processing stability, the following comprehensive evaluation results were obtained: Firstly, regarding antibacterial performance, Examples 1-3 all exhibited significantly better antibacterial effects than the comparative examples, with Examples 2 and 3 showing more stable and sustained antibacterial performance. This is mainly because the examples simultaneously introduced three functional components: nano-titanium dioxide, zinc oxide, and antibacterial powder, forming a synergistic antibacterial active region on the material surface. In contrast, Comparative Example 1, lacking any antibacterial or photocatalytic components, relied solely on the properties of the PBS matrix itself, exhibiting almost no inhibitory ability against bacteria. Although Comparative Example 2 introduced nano-titanium dioxide, it lacked the synergistic effect of zinc oxide and antibacterial powder, resulting in a certain improvement in antibacterial effect, but its overall antibacterial efficiency and stability were significantly lower than the example systems.

[0091] Secondly, regarding self-cleaning performance, Examples 1-3 all exhibited good pollutant decomposition and surface cleanliness retention capabilities, with Example 2 showing the best overall performance. This is because nano-titanium dioxide, under appropriate dispersion conditions, can form continuous photocatalytic active sites on the material surface, while the introduction of zinc oxide further improves the separation efficiency of photogenerated carriers, thereby enhancing the decomposition ability of organic pollutants. Comparative Example 1, lacking photocatalytic components, easily adsorbs pollutants on its material surface, making degradation difficult; although Comparative Example 2 possesses certain photocatalytic capabilities, due to the lack of synergistic regulation from other components in the composite system, its surface active sites are unevenly distributed, resulting in unstable self-cleaning effects.

[0092] Furthermore, regarding mechanical properties, Examples 1-3 all maintained good overall mechanical properties, with Example 2 exhibiting a more balanced strength and toughness. This is mainly attributed to the effective regulation of the continuous and dispersed phase structures formed by PBS and PBAT resins under the action of the compatibilizer, ensuring that the inorganic functional filler did not significantly weaken the structural integrity of the material after its introduction. Comparative Example 1, due to its relatively simple system, exhibited stable mechanical properties but insufficient functionality; Comparative Example 2, due to its single functional filler and insufficient interface regulation, showed some fluctuations in certain performance indicators.

[0093] Finally, regarding processing performance and material stability, all embodiments exhibited good flowability and molding stability during melt processing, without significant stratification or severe agglomeration. Among them, Embodiment 2, due to the intermediate proportions of its components, had a wider processing window and superior stability. Comparative Embodiment 1 showed relatively stable processing performance but lacked functionality; Comparative Embodiment 2 exhibited slight uneven powder dispersion under certain conditions.

[0094] In summary, by synergistically introducing nano-titanium dioxide, zinc oxide, and antibacterial powder, and combining this with a compatibilizer to regulate the interfacial structure, this technical solution can achieve a synergistic improvement in antibacterial and self-cleaning properties while ensuring the mechanical and processing properties of PBS-based composite materials. This is significantly superior to existing technical solutions that only use single-function fillers or do not optimize the structure.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An antibacterial, self-cleaning PBS-based composite material, characterized in that, The composite material is composed of the following formulation in parts by weight: 70-85 parts of PBS resin; 15-25 parts of PBAT resin; 10-18 parts talc; 3-6 parts of nano-titanium dioxide; 2-4 parts zinc oxide; 1-2 parts antibacterial powder; 2-4 parts compatibilizer; Lubricant 0.5 to 1 part; Antioxidant 0.3 to 0.8 parts.

2. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The nano-titanium dioxide has anatase or anatase / rutile mixed crystal form, wherein the mass proportion of anatase is 60% to 95%. The nano-titanium dioxide has an average particle size of 10-40 nm and a specific surface area of ​​50-200 m² / g, and its surface is treated with a silane coupling agent, wherein the amount of the silane coupling agent added is 0.5%-3% of the mass of the nano-titanium dioxide.

3. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The zinc oxide has an average particle size of 20-100 nm, a hexagonal wurtzite structure, and its surface is modified by coating with organic acid or silane coupling agent, with a coating thickness of 1-10 nm.

4. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The antibacterial powder is an inorganic antibacterial powder, which is selected from one or two of silver-based antibacterial powder, zinc-based antibacterial powder or composite antibacterial powder; The antibacterial powder has an average particle size of 0.2–2 μm and its surface is loaded with active metal ions, with a metal ion content of 0.1%–2%.

5. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The compatibilizer is a maleic anhydride-grafted polyester compatibilizer with a grafting rate of 0.5%–2.5% and a number-average molecular weight of 2 × 10⁻⁶. 4 ~8×10 4 ; The compatibilizer molecular chain contains polar groups that form an interfacial bonding layer with the surfaces of PBS resin, PBAT resin, and inorganic fillers, and the thickness of this interfacial layer is 5–50 nm.

6. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The talc powder has an average particle size of 2-10 μm, a flake diameter-to-thickness ratio of 5-20, and its surface is treated with a coupling agent; the talc powder is oriented in the composite material along the melt flow direction, with an orientation degree of 0.3-0.8, and forms a layered barrier structure.

7. The antibacterial self-cleaning PBS-based composite material according to claim 1, characterized in that, The PBS resin and PBAT resin form a two-phase structure of continuous phase and dispersed phase in the composite material, wherein the PBS resin is the continuous phase and the PBAT resin exists in the form of dispersed phase with a particle size of 0.5 to 5 μm.

8. A method for preparing an antibacterial, self-cleaning PBS-based composite material, comprising preparing the composite material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Pretreatment of PBS resin, PBAT resin and inorganic powder; S2. Construct a functional powder premixing system based on the pretreatment in S1; S3. Based on the functional powder premix system formed in S2, the main materials are mixed to obtain a uniform feed material. S4. Based on the material obtained in S3, perform melt blending and extrusion to construct an antibacterial and self-cleaning composite structure; S5. Cool and granulate or directly mold the melt obtained by extrusion in S4, and implement surface stabilization control. S6. Post-processing and performance stabilization encapsulation of the composite material obtained in S5.

9. The method for preparing an antibacterial self-cleaning PBS-based composite material according to claim 8, characterized in that, In step S4, the temperatures of each section of the twin-screw extruder, from the feeding section to the die head section, are controlled sequentially as follows: 110–140°C, 130–155°C, 145–165°C, 150–170°C, and 150–175°C.

10. The method for preparing an antibacterial self-cleaning PBS-based composite material according to claim 8, characterized in that, In step S5, after the composite material is melt-extruded, a micro-nano composite rough structure is formed on its surface, wherein the micro-rough structure has a scale of 1 to 10 μm and the nano-rough structure has a scale of 50 to 300 nm.

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