Antibacterial AS composite material and preparation method thereof

Abstract

The invention relates to the technical field of functional plastics, in particular to an antibacterial AS composite material and a preparation method thereof.The preparation method comprises the following steps that S1, a silver-doped titanium dioxide antibacterial agent is prepared; s2, preparing a surface modified silver doped titanium dioxide antibacterial agent; s3, premixing the raw materials; s4, carrying out melt blending granulation to prepare antibacterial AS master batches; and S5, preparing a finished product. Silver-doped titanium dioxide is prepared and subjected to surface modification at the same time, the master batch is prepared from the silver-doped titanium dioxide, the compatilizer, the AS resin and the like, the master batch is further diluted, and the antibacterial AS composite material is obtained and has the advantages of being free of yellowing, good in anti-aging performance, excellent in antibacterial performance and good in mechanical performance.

Description

Technical Field

[0001] This invention relates to the field of functional plastics technology, and in particular to an antibacterial AS composite material and its preparation method. Background Technology

[0002] Acrylonitrile-styrene copolymer (AS) materials are widely used in home appliances, packaging and medical fields due to their high gloss, excellent rigidity and chemical resistance. However, they do not have antibacterial properties and are prone to becoming a carrier for microbial growth in humid and frequently touched environments. This not only affects the appearance and hygiene of the products, but may also lead to the risk of cross-infection. In existing technologies, silver-based inorganic antibacterial agents are often added through direct blending to impart antibacterial properties. However, this method has significant limitations: Firstly, nano-silver components are prone to oxidation, sulfidation, or inherent color characteristics during high-temperature processing and use, leading to irreversible appearance degradation such as yellowing, graying, or dullness, which greatly limits their application in fields with stringent visual aesthetic requirements. Secondly, inorganic antibacterial agent particles have high surface energy and are prone to agglomeration in organic resin matrices, resulting in poor dispersibility. This not only exacerbates the problem of uneven color but also affects the uniformity and durability of the antibacterial effect and severely degrades the mechanical properties of the material. Furthermore, the poor interfacial compatibility between the antibacterial agent and the resin matrix limits its addition amount. Low addition amounts make it difficult to achieve efficient and broad-spectrum antibacterial effects, while increasing the addition amount further exacerbates performance deterioration, processing difficulties, and discoloration. Therefore, developing an AS composite material preparation technology that can simultaneously solve the problems of easy aggregation of antibacterial agents, weak interfacial bonding, poor processing stability, and especially the critical problem of color degradation, thereby achieving highly efficient antibacterial properties, excellent comprehensive performance, and good appearance, has become an urgent need in this field. Summary of the Invention

[0003] To overcome the above deficiencies, this invention provides an antibacterial AS composite material and its preparation method. The method involves constructing and preparing silver-doped titanium dioxide, modifying its surface, and preparing a masterbatch with a compatibilizer, AS resin, etc. The masterbatch is then further diluted to obtain the antibacterial AS composite material, which has the characteristics of not yellowing, good anti-aging properties, excellent antibacterial properties, and good mechanical properties.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an antibacterial AS composite material includes the following steps: S1. Preparation of silver-doped titanium dioxide antibacterial agent; S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse silver-doped titanium dioxide antibacterial agent powder in a solvent, add silane coupling agent, stir and react at 60-80℃ for 2-4h, and after the reaction is completed, filter, wash and dry to obtain surface-modified silver-doped titanium dioxide antibacterial agent; S3. Raw material premixing: By mass, add 100 parts AS resin powder, 10-15 parts surface-modified silver-doped titanium dioxide antibacterial agent, 1-5 parts compatibilizer, 0.1-0.5 parts antioxidant, 0.1-0.5 parts UV absorber, 0.2-1 parts lubricant, and 0.1-0.5 parts release agent into a high-speed mixer and mix at 800-1200 rpm for 5-15 minutes at room temperature to obtain the premix. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 300-500 rpm and a processing temperature range of 200-240℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:10-15, and then process them into the final product through injection molding or extrusion.

[0005] This invention utilizes the bulk construction (S1) and surface organic modification (S2) of a silver-doped titanium dioxide antibacterial agent. By grafting organic functional groups onto the surface of inorganic particles using a silane coupling agent, the surface energy of the particles is reduced, initially preventing their agglomeration tendency in the subsequent polymer matrix and providing active sites for subsequent reactions with compatibilizers. Insufficient reaction or incomplete washing in this step will lead to uneven modified layers or residual impurities, directly affecting the final dispersion and interfacial strength. In the premixing stage (S3), the surface-modified silver-doped titanium dioxide antibacterial agent, AS resin powder, compatibilizer, and various additives are blended in one step. Macroscopic homogeneity here is a prerequisite for achieving subsequent microscopic homogeneous dispersion. The compatibilizer interacts strongly with the surface functional groups of the antibacterial agent and the AS matrix, acting as a "bridge" connecting the two phases during the melting stage. Insufficient compatibilizer will result in insufficient bridging, while excessive compatibilizer may self-aggregate to form micelles, thus disrupting the system's homogeneity. Melt blending granulation (S4) involves high shear force and a suitable temperature of 200-240℃. During this process, AS resin and compatibilizer fully melt, and the shear force effectively breaks down the antibacterial agent agglomerates. The high temperature provides the necessary energy to drive a chemical reaction between the functional end groups of the compatibilizer and the silane layer on the surface of the antibacterial agent, forming a strong chemical bond. This creates a tough interfacial layer between the inorganic particles and the organic matrix. This temperature range is crucial; if it is too low, the melt becomes viscous, the reaction is delayed, and uneven dispersion occurs. If it is too high, the AS resin will undergo thermal degradation and turn yellow. During this process, antioxidants are used to inhibit the thermo-oxidative degradation of the resin, and lubricants are used to reduce melt viscosity and shear heat. These factors need to be coordinated with the processing temperature and screw speed. Exceeding these ranges will lead to molecular chain breakage or poor plasticization. Finally, by using the masterbatch method to obtain the finished product (S5), a high-concentration antibacterial masterbatch is mixed with ordinary AS resin, ensuring that the excellent dispersibility achieved in the functional masterbatch is maintained in the final product. This achieves high-efficiency antibacterial properties while also taking into account the mechanical properties and appearance of the product.

[0006] Preferably, the specific method for preparing the silver-doped titanium dioxide antibacterial agent in step S1 is as follows: The silver-doped titanium dioxide antibacterial agent is prepared using a sol-gel method with titanium and silver sources as raw materials; the titanium source is tetrabutyl titanate or titanium oxysulfate, and the silver source is silver nitrate or silver acetate; the sol-gel method includes dissolving the titanium source in ethanol to form solution A, wherein the concentration of the titanium source in the ethanol is 0.1-0.5%. The silver source was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3-4. Ethanol was then added to form solution B, where the molar ratio of water to titanium source was 8-12:1, and the volume ratio of deionized water to ethanol was 3-5:1. Solution B was slowly added to solution A over 1-2 hours with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and calcined at 400-600℃ under a nitrogen atmosphere for 2-4 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 1%-3%.

[0007] An excess of water ensures complete ionization of the silver source, allowing it to exist as silver ions in the precursor solution, achieving molecular-level uniform dispersion when mixed with tetrabutyl titanate. Subsequently, tetrabutyl titanate undergoes a quantitative hydrolysis reaction to generate highly reactive Ti-OH groups. These newly formed Ti-OH groups rapidly coordinate or exchange with free silver ions in the solution, forming Ti-O-Ag bonds. This quantitatively anchors silver ions to the gel framework via chemical bonds in the initial stage of titanium dioxide three-dimensional network formation. The subsequent calcination process is carried out under an inert atmosphere, which crystallizes amorphous titanium dioxide into anatase and reduces the fixed silver ions to more antibacterial metallic silver nanoparticles through in-situ carbothermal reduction, preventing their oxidation. Therefore, the 1%-3% silver content in the final product can be uniquely determined by the stoichiometric ratio of the initial feed, while its highly uniform dispersion is guaranteed by the rapid and quantitative chemical reaction between silver ions and Ti-OH groups.

[0008] Preferably, in step S2, the silane coupling agent is one of γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane; the amount of the silane coupling agent is 1%-3% of the mass of the silver-doped titanium dioxide antibacterial agent powder; the solvent is a solution of ethanol and water mixed in a volume ratio of 4-5:1, and the amount of solvent is 5-10 times the mass of the silver-doped titanium dioxide antibacterial agent powder.

[0009] This scheme utilizes a sol-gel method combined with surface modification to synergistically construct a high-performance antibacterial agent. In S1, the addition rate of solution B to solution A is strictly controlled to ensure uniform silver doping within the titanium dioxide lattice. The calcination temperature must be precisely maintained between 400-600℃; too low a temperature results in insufficient crystallization, while too high a temperature leads to particle sintering and loss of silver activity. S2 employs an ethanol-water mixed solvent system to provide the optimal environment for the hydrolysis of the silane coupling agent. The key to selecting γ-aminopropyl or epoxy silanes lies in their terminal active groups, which can both bond to the antibacterial agent surface and react chemically with subsequent compatibilizers. The silane coupling agent dosage of 1%-3% aims to form complete coating modification; excessive dosage will lead to multilayer adsorption, affecting interfacial stability. The entire process, by controlling the matching of material components and reaction parameters, constructs a reactive interfacial layer on the antibacterial agent surface, laying the foundation for interfacial chemical bonding during subsequent melt blending.

[0010] Preferably, in step S3, the lubricant is at least one of stearic acid, zinc stearate, vinyl bis-stearamide, or polyethylene wax.

[0011] Preferably, in step S3, the release agent is at least one of magnesium stearate, calcium stearate, or pentaerythritol stearate.

[0012] Preferably, in step S3, the AS resin powder has a particle size of 50-200 mesh; the antioxidant is a composite antioxidant composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010) and tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168) in a mass ratio of 1:1 to 1:2; and the ultraviolet absorber is 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327) or 2-hydroxy-4-n-octyloxybenzophenone or (UV-531).

[0013] Preferably, the compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 1-5 parts by weight of maleic anhydride, and 0.1-1 parts by weight of initiator are added to a high-speed mixer and mixed at room temperature for 5-10 minutes to obtain a mixed raw material; the initiator is dicumyl oxide (DCP). S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 200-400 rpm and a processing temperature range of 180-220℃. After extrusion, cooling and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained.

[0014] The core mechanism of this compatibilizer preparation lies in introducing active maleic anhydride functional groups onto the acrylonitrile-styrene copolymer molecular chain through a melt free radical grafting reaction. Strict control of the component ratios and process parameters is crucial: the acrylonitrile-styrene copolymer resin, acting as the grafting matrix, has a molecular weight distribution that affects melt flowability and the final entanglement effect between the compatibilizer and the AS matrix; maleic anhydride is a reactive monomer, and its dosage must be precisely balanced—too little will result in insufficient grafting rate and insufficient interfacial active sites, while too much can easily lead to homopolymerization side reactions, generating polymaleic anhydride, which becomes a system defect; the decomposition characteristics of the initiator DCP determine the free radical concentration—too low a dosage results in low grafting reaction efficiency, while too high a dosage leads to excessive chain breakage and degradation of the acrylonitrile-styrene copolymer backbone, weakening its mechanical support role as a compatibilizer. Twin-screw extrusion is crucial for achieving the reaction. The temperature range must simultaneously ensure a balance between the complete melting of the acrylonitrile-styrene copolymer, the efficient half-life decomposition of DCP, and the appropriate volatilization of maleic anhydride. Too low a temperature leads to incomplete reaction, while too high a temperature accelerates maleic anhydride sublimation, resulting in formulation distortion and equipment corrosion. The shear force provided by the screw speed directly affects the uniformity of reactant mixing and residence time; excessive shear also exacerbates degradation. The ultimate goal is to generate a graft copolymer that combines the matrix compatibility of acrylonitrile-styrene copolymer with the interfacial reactivity of maleic anhydride, laying the foundation for building a stable chemical bridge between the subsequent antibacterial agent and AS resin.

[0015] This solution also proposes an antibacterial AS composite material prepared by the above method, which can be used to prepare household appliance parts, food packaging containers, medical devices or automotive interior parts.

[0016] Compared to existing technologies, the advantages of this solution are: From a compositional perspective, this invention achieves synergistic effects of photocatalytic antibacterial and metal ion antibacterial properties by preparing silver-doped titanium dioxide as the antibacterial core, laying the foundation for highly efficient and broad-spectrum antibacterial functions. Subsequently, γ-aminopropyl or epoxy silane coupling agents are introduced to modify the antibacterial agent. This not only allows the silver-doped titanium dioxide to be better dispersed in organic components but also enables it to react and link with maleic anhydride-grafted acrylonitrile-styrene copolymer compatibilizers, thereby constructing a robust molecular bridge between the two via covalent bonds. This further improves its dispersibility in acrylonitrile-styrene copolymers and solves the industry problem of easy agglomeration and weak interfacial bonding of high-content inorganic fillers. Furthermore, the combination of an antioxidant system and the selection of UV absorbers effectively inhibits yellowing, ensuring the long-term appearance stability and mechanical properties of the product. Together, these factors ensure that the composite material achieves excellent antibacterial performance while also possessing superior mechanical strength and appearance quality.

[0017] From a process perspective, although the basic processes in this scheme are all common methods, strict requirements are placed on the design of process steps and parameters in combination with the characteristics of the components. For example, in the process of preparing silver-doped titanium dioxide by sol-gel method, the intrinsic activity of antibacterial agent is ensured by controlling the addition and calcination process of precursor solution. First, the macroscopic pre-dispersion of each component is achieved by high-speed dry mixing, then the masterbatch is formed by twin-screw extrusion, and finally the final material is obtained by dilution. This can make the components more uniformly dispersed and obtain better mechanical and antibacterial properties. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example: A method for preparing an antibacterial AS composite material, comprising the following steps:

[0019] S1. Preparation of silver-doped titanium dioxide antibacterial agent: Tetrabutyl titanate is dissolved in ethanol to form solution A, wherein the concentration of tetrabutyl titanate in ethanol is 0.3 mol / L; Silver nitrate was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3.5. Ethanol was then added to form solution B, in which the molar ratio of water to tetrabutyl titanate was 10:1, and the volume ratio of deionized water to ethanol was 4:1. Solution B was slowly added to solution A over 1.5 hours with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and then calcined at 500°C under a nitrogen atmosphere for 3 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 2%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse the silver-doped titanium dioxide antibacterial agent powder in a solution of ethanol and water with a volume ratio of 4.5:1, which is 7.5 times the mass of the silver-doped titanium dioxide antibacterial agent powder. Add 2% by mass of γ-aminopropyltriethoxysilane to the solution and stir at 70°C for 3 hours. After the reaction is completed, filter, wash and dry to obtain the surface-modified silver-doped titanium dioxide antibacterial agent. S3. Raw Material Premixing: By weight, 100 parts AS resin powder, 12.5 parts surface-modified silver-doped titanium dioxide antibacterial agent, 3 parts compatibilizer, 0.3 parts antioxidant, 0.3 parts UV absorber, 0.6 parts lubricant, and 0.3 parts release agent are added to a high-speed mixer and mixed at 1000 rpm for 10 minutes at room temperature to obtain a premix. The lubricant is polyethylene wax; the release agent is magnesium stearate; the AS resin powder has a particle size of 100 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.5; and the UV absorber is UV-327. The compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 3 parts by weight of maleic anhydride, and 0.5 parts by weight of DCP are added into a high-speed mixer and mixed at room temperature for 7.5 min to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 300 rpm and a processing temperature range of 200°C. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 400 rpm and a processing temperature range of 220℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch and ordinary AS resin particles at a mass ratio of 1:12.5, and then process them into the final product through injection molding. Example: A method for preparing an antibacterial AS composite material, comprising the following steps:

[0020] S1. Preparation of silver-doped titanium dioxide antibacterial agent: Tetrabutyl titanate is dissolved in ethanol to form solution A, wherein the concentration of tetrabutyl titanate in ethanol is 0.1 mol / L; Silver acetate was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3.5. Ethanol was then added to form solution B, in which the molar ratio of water to tetrabutyl titanate was 8:1, and the volume ratio of deionized water to ethanol was 3:1. Solution B was slowly added to solution A over 1 hour with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and then calcined at 400°C under a nitrogen atmosphere for 4 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 1%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse the silver-doped titanium dioxide antibacterial agent powder in a solution of ethanol and water at a volume ratio of 4:1, which is 5 times the mass of the silver-doped titanium dioxide antibacterial agent powder. Add 1% by mass of γ-glycidyl etheroxypropyltrimethoxysilane to the solution. Stir and react at 60°C for 4 hours. After the reaction is completed, filter, wash and dry to obtain the surface-modified silver-doped titanium dioxide antibacterial agent. S3. Raw Material Premixing: By weight, 100 parts AS resin powder, 10 parts surface-modified silver-doped titanium dioxide antibacterial agent, 1 part compatibilizer, 0.1 parts antioxidant, 0.1 parts UV absorber, 0.2 parts lubricant, and 0.1 parts release agent are added to a high-speed mixer and mixed at 800 rpm for 15 minutes at room temperature to obtain a premix. The lubricant is zinc stearate; the release agent is calcium stearate; the AS resin powder has a particle size of 50 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio; the UV absorber is UV-531. The compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 1 part by weight of maleic anhydride, and 0.1 parts by weight of DCP are added into a high-speed mixer and mixed for 5 minutes at room temperature to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 200 rpm and a processing temperature range of 180°C. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 300 rpm and a processing temperature range of 200℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:10, and then process them into the final product through an extrusion process. Example: A method for preparing an antibacterial AS composite material, comprising the following steps:

[0021] S1. Preparation of silver-doped titanium dioxide antibacterial agent: Tetrabutyl titanate is dissolved in ethanol to form solution A, wherein the concentration of tetrabutyl titanate in ethanol is 0.5 mol / L; Silver nitrate was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3. Ethanol was then added to form solution B, in which the molar ratio of water to tetrabutyl titanate was 12:1, and the volume ratio of deionized water to ethanol was 5:1. Solution B was slowly added to solution A over 2 hours with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and then calcined at 600°C under a nitrogen atmosphere for 2 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 3%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse the silver-doped titanium dioxide antibacterial agent powder in a solution of ethanol and water at a volume ratio of 5:1, which is 10 times the mass of the silver-doped titanium dioxide antibacterial agent powder. Add 3% by mass of γ-aminopropyltriethoxysilane to the solution and stir at 80°C for 2 hours. After the reaction is completed, filter, wash and dry to obtain the surface-modified silver-doped titanium dioxide antibacterial agent. S3. Raw Material Premixing: By weight, 100 parts AS resin powder, 15 parts surface-modified silver-doped titanium dioxide antibacterial agent, 5 parts compatibilizer, 0.5 parts antioxidant, 0.5 parts UV absorber, 1 part lubricant, and 0.5 parts release agent are added to a high-speed mixer and mixed at 1200 rpm for 5 minutes at room temperature to obtain a premix. The lubricant is vinyl bis-stearamide; the release agent is pentaerythritol stearate; the AS resin powder has a particle size of 200 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; the UV absorber is UV-327. The compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 5 parts by weight of maleic anhydride, and 1 part by weight of DCP are put into a high-speed mixer and mixed at room temperature for 10 minutes to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 400 rpm and a processing temperature range of 220°C. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 500 rpm and a processing temperature range of 240℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:15, and then process them into the final product through injection molding. Example: A method for preparing an antibacterial AS composite material, comprising the following steps:

[0022] S1. Preparation of silver-doped titanium dioxide antibacterial agent: Titanium oxysulfate is dissolved in ethanol to form solution A, wherein the concentration of titanium oxysulfate in ethanol is 0.2 mol / L; Silver nitrate was dissolved in deionized water, and then nitric acid was added to adjust the pH to 4. Ethanol was then added to form solution B, in which the molar ratio of water to titanium oxysulfate was 9:1, and the volume ratio of deionized water to ethanol was 3.5:1. Solution B was slowly added to solution A over 1.2 hours with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and then calcined at 450°C under a nitrogen atmosphere for 3.5 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 1.5%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse the silver-doped titanium dioxide antibacterial agent powder in a solution of ethanol and water with a volume ratio of 4.2:1, which is 6 times the mass of the silver-doped titanium dioxide antibacterial agent powder. Add 1.5% by mass of γ-glycidyl oxypropyltrimethoxysilane to the solution and stir at 65°C for 3.5 h. After the reaction is completed, filter, wash and dry to obtain the surface-modified silver-doped titanium dioxide antibacterial agent. S3. Raw Material Premixing: By weight, 100 parts AS resin powder, 11 parts surface-modified silver-doped titanium dioxide antibacterial agent, 2 parts compatibilizer, 0.2 parts antioxidant, 0.2 parts UV absorber, 0.4 parts lubricant, and 0.2 parts release agent are added to a high-speed mixer and mixed at 900 rpm for 12 minutes at room temperature to obtain a premix. The lubricant is stearic acid; the release agent is magnesium stearate; the AS resin powder has a particle size of 80 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.2; the UV absorber is UV-531. The compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 2 parts by weight of maleic anhydride, and 0.3 parts by weight of DCP are added into a high-speed mixer and mixed at room temperature for 6 minutes to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 250 rpm and a processing temperature range of 190°C. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 350 rpm and a processing temperature range of 210℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:11, and then process them into the final product through injection molding. Example: A method for preparing an antibacterial AS composite material, comprising the following steps:

[0023] S1. Preparation of silver-doped titanium dioxide antibacterial agent: Titanium oxysulfate is dissolved in ethanol to form solution A, wherein the concentration of titanium oxysulfate in ethanol is 0.4 mol / L; Silver acetate was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3.5. Ethanol was then added to form solution B, in which the molar ratio of water to titanium oxysulfate was 11:1, and the volume ratio of deionized water to ethanol was 4.5:1. Solution B was slowly added to solution A over 1.8 hours with continuous stirring to form a sol. After aging, a gel was obtained. The gel was dried and calcined at 550°C under a nitrogen atmosphere for 2.5 hours to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder was 2.5%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Disperse the silver-doped titanium dioxide antibacterial agent powder in a solution of ethanol and water with a volume ratio of 4.8:1, which is 9 times the mass of the silver-doped titanium dioxide antibacterial agent powder. Add 2.5% by mass of γ-aminopropyltriethoxysilane to the solution and stir at 75°C for 2.5 h. After the reaction is completed, filter, wash and dry to obtain the surface-modified silver-doped titanium dioxide antibacterial agent. S3. Raw Material Premixing: By weight, 100 parts AS resin powder, 14 parts surface-modified silver-doped titanium dioxide antibacterial agent, 4 parts compatibilizer, 0.4 parts antioxidant, 0.4 parts UV absorber, 0.8 parts lubricant, and 0.4 parts release agent are added to a high-speed mixer and mixed at 1100 rpm for 8 minutes at room temperature to obtain a premix. The lubricant is polyethylene wax; the release agent is pentaerythritol stearate; the AS resin powder has a particle size of 150 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.8; the UV absorber is UV-327. The compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, and the preparation method is as follows: S01. 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 4 parts by weight of maleic anhydride, and 0.8 parts by weight of DCP are put into a high-speed mixer and mixed at room temperature for 9 minutes to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 350 rpm and a processing temperature range of 210°C. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 450 rpm and a processing temperature range of 230°C to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:14, and then process them into the final product through an extrusion process.

[0024] Comparative Example 1 The only difference from Example 1 is that silver-doped titanium dioxide was not prepared in S1, while only nano-silver particles in the same proportion as in Example 1 were added in S2.

[0025] Comparative Example 2 The only difference from Example 1 is that silver-doped titanium dioxide was not prepared in S1, while only titanium dioxide powder in the same proportion as in Example 1 was added in S2.

[0026] Comparative Example 3 The only difference from Example 1 is that no ethanol component was added to solution B.

[0027] Comparative Example 4 The only difference from Example 1 is that in solution B, the water component is too small, and the molar ratio of water to tetrabutyl titanate is 5:1.

[0028] Comparative Example 5 The only difference from Example 1 is that the calcination temperature is too high, at 650°C.

[0029] Comparative Example 6 The only difference from Example 1 is that vinyltriethoxysilane is used as the silane coupling agent.

[0030] Comparative Example 7 The only difference from Example 1 is that the S4 masterbatch preparation process is omitted, and the premixed material from S3 is directly introduced into the S5 step to produce the finished product.

[0031] Comparative Example 8 The only difference from Example 1 is that no compatibilizer was added.

[0032] Comparative Example 9 The only difference from Example 1 is that maleic anhydride and DCP are added as compatibilizer components in S3.

[0033] Comparative Example 10 The only difference from Example 1 is that in S5, the antibacterial AS masterbatch and ordinary AS resin particles are mixed and extruded at a ratio of 1:20.

[0034] Comparative Example 11 The only difference from Example 1 is that in S5, the antibacterial AS masterbatch and ordinary AS resin particles are mixed and extruded at a ratio of 1:8.

[0035] Comparative Example 12 The only difference from Example 1 is that solution B is added to solution A within 5 minutes while continuously stirring.

[0036] Performance testing: 1. Silver leaching detection: Refer to GB 4806.7-2016 "Plastic Materials and Products for Food Contact", the silver leaching amount (mg / L) is required to be ≤0.05; Simulation solution: 4% acetic acid (acidic food simulation solution), 50% ethanol (oily food simulation solution); Conditions: soaking at 60℃ for 2 hours, or soaking at 70℃ for 1 hour; Detection instrument: inductively coupled plasma mass spectrometry (ICP-MS).

[0037] 2. Antibacterial performance test: Refer to GB / T 31402-2015 "Test Method for Antibacterial Performance of Plastics", bacterial strains: Escherichia coli (ATCC 25922, Gram-negative), Staphylococcus aureus (ATCC 29213, Gram-positive); sample size: 50mm × 50mm × product thickness (flat and without defects); 3. Contact conditions: 37℃±1℃, incubation for 24h; 4. Calculation: Antibacterial rate = (number of colonies in blank group - number of colonies in sample group) / number of colonies in blank group × 100%.

[0038] 3. Long-lasting antibacterial properties: Refer to GB / T 31402-2015 + artificial aging pretreatment, immerse the sample in deionized water at 60℃ for 72h (simulating a humid environment), or undergo 1000 abrasion resistance tests (CS-10 grinding wheel, 500g load); subsequent antibacterial rate tests are the same as antibacterial rate detection.

[0039] 4. Mechanical property testing: Refer to GB / T 1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", GB / T 1043.1-2008 "Determination of impact properties of simply supported beams of plastics - Part 1: Non-instrumental impact test", and GB / T 9341-2008 "Determination of flexural properties of plastics".

[0040] 5. Appearance and aging test: First, visually inspect for discoloration and yellowing. Then, age the product in a hot air aging chamber at 70℃ for 168 hours. Evaluate the appearance again and test the tensile properties and antibacterial properties after aging.

[0041] The test results are shown in Tables 1-3, where Table 1 shows the antibacterial properties, Table 2 shows the mechanical properties, and Table 3 shows the appearance changes.

[0042] Table 1. Results of antibacterial performance testing for examples and comparative examples.

[0043] Table 2. Mechanical property test results of the examples and comparative examples.

[0044] Table 3. Mechanical appearance inspection results of the examples and comparative examples.

[0045] The embodiment exhibits systematic advantages in antibacterial properties, mechanical properties, and appearance stability: silver-doped titanium dioxide achieves synergy between photocatalysis and metal ion antibacterial properties; silane coupling agent reduces the surface energy of the antibacterial agent and constructs reactive sites by grafting organic functional groups; compatibilizer further bridges the antibacterial agent and AS matrix with covalent bonds, solving the problems of agglomeration and weak interfacial bonding; masterbatch process ensures uniform dispersion of the antibacterial agent; compound antioxidant and UV absorber effectively inhibit yellowing and aging. Ultimately, the embodiment exhibits high initial antibacterial rate, stable long-term antibacterial properties, excellent mechanical properties, and no obvious discoloration. Even after aging, it can still maintain high tensile strength retention and low color change.

[0046] Comparing the comparative examples and Example 1, Comparative Example 1, using only nano-silver particles and lacking the lattice anchoring effect of titanium dioxide, suffers from excessive silver leaching due to easy oxidation and loss of nano-silver, resulting in decreased long-term antibacterial properties. Furthermore, the inherent color characteristics of nano-silver cause initial slight yellowing of the product, with significant color changes after aging. Additionally, the dispersibility of nano-silver is worse than that of silver-doped titanium dioxide, leading to lower mechanical properties compared to Example 1. Comparative Example 2, using only titanium dioxide powder, lacks the synergistic effect of silver ions in antibacterial activity, relying solely on photocatalytic antibacterial action, resulting in low efficiency and a decline in long-term antibacterial properties due to activity decay, failing to achieve the antibacterial effect of Example 1. While its mechanical properties are similar, its antibacterial function is lacking. Comparative Example 3, due to the absence of ethanol in solution B, suffers from an imbalance in the polarity of the sol system, leading to uneven mixing of silver ions and the titanium source, resulting in poor antibacterial properties. Poor dispersibility of the antibacterial agent not only reduces the antibacterial rate but also causes slight yellowing of the product in some areas. Weak interfacial bonding further leads to a decrease in mechanical properties, and the discoloration and performance degradation are more obvious after aging. In Comparative Example 4, the molar ratio of water to titanium source in solution B was too low, resulting in insufficient hydrolysis of the titanium source and the inability to form sufficient Ti-OH groups to anchor silver ions. This led to poor crystallization and doping uniformity of the antibacterial agent, a decrease in antibacterial activity and dispersibility, and a comprehensive deterioration in antibacterial rate, mechanical properties, and appearance stability, with a more significant degree of deterioration than in Comparative Example 3. In Comparative Example 5, the calcination temperature was too high, exceeding the suitable range for titanium dioxide crystallization and silver reduction, resulting in sintering of antibacterial agent particles, loss of silver activity, and a significant decrease in antibacterial efficiency. At the same time, the increased particle agglomeration further reduced the mechanical properties. The color of the sample was dull due to abnormal particle structure, and the color change and performance degradation were most severe after aging. Comparative Example 6 used vinyltriethoxysilane, which has no active terminal groups and cannot react with compatibilizers. It can only slightly improve dispersibility and cannot build strong interfacial bonds, resulting in many defects at the interface between the antibacterial agent and the matrix. The antibacterial rate, mechanical properties and long-term stability are all lower than those of the examples, and slight color change also appeared after aging. Comparative Example 7 skipped the masterbatch preparation process and directly formed the premix. It lacked the high shear dispersion and interfacial chemical reaction enhancement of twin-screw extrusion. The antibacterial agent dispersion was not uniform, the antibacterial rate and mechanical properties decreased, and the performance retention rate after aging was also lower than that of the examples. Comparative Example 8 did not add compatibilizer, and the antibacterial agent did not react with the AS matrix. In Comparative Example 9, maleic anhydride and DCP were directly added to the premix without a pre-prepared graft compatibilizer. This resulted in uneven antibacterial effect and significant deterioration of mechanical properties such as impact strength due to interface defects. The interface bonding was weaker than in the example, leading to decreased antibacterial dispersibility and mechanical properties, and localized darkening and aging discoloration. In Comparative Example 10, the high mixing ratio of masterbatch and ordinary AS resin resulted in excessive dilution of the antibacterial agent concentration, leading to insufficient antibacterial activity. Both the initial and long-term antibacterial rates were significantly lower than in the example. Although the mechanical properties and appearance were similar, the antibacterial function did not meet the standards.Comparative Example 11, due to its excessively low mixing ratio and high antibacterial agent concentration, resulted in excessive inorganic particles disrupting the continuity of the AS matrix, leading to a decline in mechanical properties. Furthermore, the excess antibacterial agent easily agglomerated, causing a slight initial yellowing of the product. Although the color change was mild after aging, the mechanical properties showed a significant disadvantage. Comparative Example 12, due to the rapid addition of solution B, experienced an instantaneous reaction in the sol system, resulting in uneven mixing of silver ions and the titanium source. This led to poor antibacterial agent dispersion, a decrease in antibacterial rate and mechanical properties, and the appearance of localized uneven coloring. After aging, the degree of color change and performance degradation was similar to that of Comparative Example 3.

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial AS composite material, characterized in that, Includes the following steps: S1. Preparation of silver-doped titanium dioxide antibacterial agent: Tetrabutyl titanate is dissolved in ethanol to form solution A, wherein the concentration of tetrabutyl titanate in ethanol is 0.1-0.5 mol / L; The silver source was dissolved in deionized water, and then nitric acid was added to adjust the pH to 3-4. Then ethanol was added to form solution B, in which the molar ratio of water to tetrabutyl titanate was 8-12:1 and the volume ratio of deionized water to ethanol was 3-5:

1. Solution B is slowly added to solution A over 1-2 hours under continuous stirring to form a sol. After aging, a gel is obtained, dried, and calcined to obtain silver-doped titanium dioxide antibacterial agent powder. The mass fraction of silver in the silver-doped titanium dioxide antibacterial agent powder is 1%-3%. S2. Preparation of surface-modified silver-doped titanium dioxide antibacterial agent: Silver-doped titanium dioxide antibacterial agent powder is modified with silane to obtain surface-modified silver-doped titanium dioxide antibacterial agent; S3. Raw material premixing: By mass, mix 100 parts AS resin powder, 10-15 parts surface-modified silver-doped titanium dioxide antibacterial agent, 1-5 parts compatibilizer, 0.1-0.5 parts antioxidant, 0.1-0.5 parts UV absorber, 0.2-1 parts lubricant, and 0.1-0.5 parts release agent, and stir at high speed to obtain a premix. S4. Melt blending and granulation: The above premixed material is melt-extruded and granulated through a twin-screw extruder at a screw speed of 300-500 rpm and a processing temperature range of 200-240℃ to obtain antibacterial AS masterbatch. S5. Obtain the finished product: Mix the above antibacterial AS masterbatch with ordinary AS resin particles at a mass ratio of 1:10-15, and then process them into the final product through injection molding or extrusion.

2. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, The silver source is silver nitrate or silver acetate.

3. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, The calcination process described in S1 is as follows: calcination at 400-600℃ in a nitrogen atmosphere for 2-4 hours.

4. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, The process of modifying the silver-doped titanium dioxide antibacterial agent powder with silane is as follows: the silver-doped titanium dioxide antibacterial agent powder is dispersed in a solution of ethanol and water with a volume ratio of 4-5:1, which is 5-10 times the mass of the silver-doped titanium dioxide antibacterial agent powder. 1%-3% of γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane is added, and the mixture is stirred and reacted at 60-80℃ for 2-4 hours. After the reaction is completed, the mixture is filtered, washed, and dried.

5. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, In S3, the lubricant is at least one of stearic acid, zinc stearate, vinyl bis-stearamide, or polyethylene wax; the release agent is at least one of magnesium stearate, calcium stearate, or pentaerythritol stearate.

6. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, In S3, the particle size of the AS resin powder is 50-200 mesh; the antioxidant is a composite antioxidant made by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-1:2; and the ultraviolet absorber is UV-327 or UV-531.

7. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, In S3, the compatibilizer is a maleic anhydride-grafted acrylonitrile-styrene copolymer, which is prepared by the following method: S01. Add 100 parts by weight of acrylonitrile-styrene copolymer resin particles, 1-5 parts by weight of maleic anhydride, and 0.1-1 parts by weight of DCP into a high-speed mixer and mix for 5-10 minutes at room temperature to obtain a mixed raw material. S02. The mixed raw materials are melt-extruded through a twin-screw extruder at a screw speed of 200-400 rpm and a processing temperature range of 180-220℃. After extrusion, cooling, and pelletizing, the maleic anhydride-grafted acrylonitrile-styrene copolymer is obtained.

8. The method for preparing the antibacterial AS composite material as described in claim 1, characterized in that, In S3, the high-speed stirring process is as follows: mixing at a speed of 800-1200 rpm for 5-15 minutes at room temperature.

9. An antibacterial AS composite material, characterized in that, The antibacterial AS composite material was prepared by the method described in any one of claims 1-8.

10. An antibacterial AS composite material as described in claim 9, characterized in that, It is used to manufacture components for household appliances, food packaging containers, medical equipment, or automotive interior parts.

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