Antibacterial fresh-keeping refrigerator based on composite material and preparation method of antibacterial fresh-keeping refrigerator

Abstract

The invention discloses an antibacterial fresh-keeping refrigerator based on a composite material and a preparation method of the antibacterial fresh-keeping refrigerator, and relates to the technical field of household appliances and food packaging. The composite material is used as a functional additive to be added into a preparation base material of a refrigerator polymer component, the composite material takes biochar as a carrier to load graphene and nano-copper particles, the biochar provides high specific surface area and adsorbability, the graphene enhances conductivity and provides adhesion mechanical strength for nano-copper, electron transfer is promoted, and the composite material is used for preparing the refrigerator polymer component. Nano-copper is activated, the nano-copper generates active oxygen through photocatalysis, copper ions are released and destroy the microbial structure, the copper ions are bound by cage walls formed by graphene to form potential difference, the antibacterial ability is further improved, and the antibacterial activity, stability and dispersity are improved through the synergistic effect of the nano-copper, the copper ions and the graphene. The high-molecular part of the refrigerator is prepared through the processes of melt blending, extrusion, injection molding and the like.

Description

Technical Field

[0001] This invention relates to the fields of home appliance and food packaging technology, specifically to an antibacterial and food preservation refrigerator based on composite materials and its preparation method. Background Technology

[0002] The human environment is teeming with various pathogenic microorganisms, including bacteria and viruses. Bacterial infections or inflammations are one of the main causes of illness and even death in humans, significantly increasing healthcare costs worldwide. As human history continues to evolve, bacterial and viral infections remain a serious challenge for humanity. Antimicrobial materials (ABPs) typically refer to functional materials that have the ability to kill or inhibit the growth and reproduction of harmful bacteria and microorganisms. Antimicrobial agents (AGs) are the core components of antimicrobial materials that are highly sensitive to pathogenic microorganisms. Based on their source and chemical composition, they can be broadly classified into three categories: natural antimicrobial agents, organic antimicrobial agents, and inorganic antimicrobial agents. Traditional refrigerator antibacterial solutions often employ silver-based inorganic or organic antibacterial agents, but these suffer from high costs, poor durability, and potential toxicity. Furthermore, silver-based antibacterial agents are prone to oxidation and deactivation, and heavy metal ions can migrate into food. Organic antibacterial agents have poor heat resistance and are easily decomposed and ineffective. In addition, the high humidity environment inside refrigerators easily breeds bacteria and mold, and ordinary plastic parts lack active antibacterial capabilities. In recent years, nano-copper / carbon-based composite materials have attracted much attention due to their low cost and strong antibacterial properties. However, nano-copper is prone to agglomeration and oxidation, and has poor compatibility with plastic matrices. Graphene and biochar can be used as carriers to improve the dispersibility and stability of nano-copper, but composite materials still face challenges in uniform dispersion, processing adaptability, and long-term effectiveness in complex refrigerator components. Summary of the Invention

[0003] This invention provides an antibacterial preservation refrigerator based on composite materials and its preparation method, which can effectively solve the problems mentioned in the background art, such as the high cost, poor durability, and potential toxicity of existing solutions that use silver-based inorganic or organic antibacterial agents. Nano-copper is prone to agglomeration and oxidation and has poor compatibility with plastic matrices. Graphene and biochar as carriers can improve the dispersibility and stability of nano-copper, but composite materials have problems with uniform dispersion, processing adaptability, and long-term effectiveness in complex refrigerator components.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an antibacterial preservation refrigerator based on composite materials, wherein the antibacterial preservation refrigerator uses a composite material composed of nano-copper, graphene and biochar as the core functional additive. The composite material uses biochar as a carrier to load graphene and nano-copper particles. Biochar prevents nano-copper from agglomerating, graphene enhances dispersibility and electronic conduction, and provides adhesion mechanical strength for nano-copper. By integrating it into the polymer components of the refrigerator, which include the inner liner, air duct, fan, drawers, and light cover; The refrigerator also includes the following parts: Intelligent environmental monitoring system using temperature, humidity, ethylene concentration, and light sensors; A smart control system that integrates IoT technology with a smartphone app; An automatic control system that can automatically adjust temperature, humidity, and antibacterial function based on the refrigerator's internal environment data; An antibacterial and preservative material based on nano-copper, graphene, and biochar composite materials is embedded in the polymer components of a refrigerator. The composite material is used for antibacterial, ethylene removal, moisture absorption, and odor removal. The intelligent control system automatically adjusts the refrigerator's temperature, humidity, and antibacterial effect based on the following comprehensive objective function, as shown in the formula below: in: It is an energy efficiency function, a multidimensional function based on temperature (T), humidity (H), and ethylene concentration (C); This represents the deviation between the target temperature and the actual temperature. The deviation between the target humidity and the actual humidity; The antibacterial activity function depends on the performance of the composite material under temperature and humidity conditions; , , , These are the weighting coefficients for each parameter, representing the importance of energy efficiency, temperature and humidity regulation, and antibacterial effect, respectively.

[0005] According to the above technical solution, the biochar, as a carrier phase, is derived from biomass acidified under limited oxygen conditions, and the biochar captures ethylene gas, moisture and odor molecules. The graphene is used as a reinforcing phase and is composited in the form of graphene oxide. Graphene oxide is grown on the surface of biochar by hydrothermal method to form a stable three-dimensional conductive network. Graphene promotes electron transfer and activates the photocatalytic activity of nano-copper. The nano-copper, serving as the active phase, is chemically reduced to control the copper loading and anchor it to the surface of the graphene and biochar support. The nano-copper generates reactive oxygen species and releases copper ions through photocatalysis, disrupting microbial cell membranes and DNA. Under visible light, the nano-copper excites photogenerated electrons, which are then transferred through graphene to generate reactive oxygen species. Simultaneously, Cu... 2+ Disrupts cell membranes, while Cu 2+Furthermore, the potential difference formed by the "cage wall" of graphene further enhances its antibacterial ability.

[0006] According to the above technical solution, the polymer components such as the inner liner, air duct, fan, drawer and lampshade are all made of engineering plastic as the base material, with 1-10wt% of a composite material composed of nano copper, graphene and biochar added. Composite materials were added as functional additives to the polymer components of the refrigerator, and each polymer component was prepared by melt blending and extrusion molding.

[0007] According to the above technical solution, the substrate of the inner liner is selected as a high-impact polystyrene HIPS or PP modified HIPS blend (APS), which is formed by extrusion and vacuum adsorption. The base material for the air duct and fan is selected from high-impact polystyrene HIPS or ABS resin, and is injection molded. The base material for the drawer and lampshade is made of transparent material, specifically polyethylene terephthalate (PET) or its copolymers PETG and PCTG.

[0008] The importance of regulating and antibacterial effects.

[0009] According to the above technical solution, functional additives also need to be added to the polymer components, specifically including toughening agents and antioxidants; The toughening agent is a thermoplastic elastomer of SEBS, SBS or POE, and its addition amount is 5-10 parts, while the antioxidant addition amount is 0.5-1 parts.

[0010] The importance of regulating and antibacterial effects.

[0011] According to the above technical solution, the polymer components also need to undergo special treatment, specifically, chitosan or sodium carboxymethyl cellulose coatings can be applied to the surface of each polymer component.

[0012] According to the above technical solution, a method for preparing an antibacterial and food-preserving refrigerator based on composite materials includes the following preparation process: Step S1: Synthesis of ternary composite materials; Step S2, processing of polymer components for refrigerators; Step S3: Simulated environmental preservation test; S1 includes the following steps: Step S101, preparation of biochar; Step S102, graphene loading; Step S103, nano-copper anchoring; S2 includes the following steps: Step S201: Mix materials according to the weight ratio; Step S220: Melt blending extrusion; Step S203: Injection molding; Step S204, surface coating finishing.

[0013] According to the above technical solution, in S101, during the biochar preparation process, biomass is carbonized under limited oxygen conditions at a temperature of 500°C for 2 hours to obtain primary biochar. The biomass can be straw, wood, or bamboo powder. Next, the ash is removed by acid washing, specifically by using hydrochloric acid or sulfuric acid to wash the biochar, resulting in a porous biochar carrier; In step S102, during the graphene loading process, the biochar carrier and the graphene oxide dispersion are uniformly mixed and placed in a high-pressure reactor. The concentration of the graphene oxide dispersion is 10 mg / mL. During the hydrothermal reaction at 180℃ for 12 hours, graphene oxide is partially reduced and self-assembled, firmly adhering to the porous surface and channels of biochar to form a three-dimensional composite carrier, allowing graphene to grow uniformly on the surface of biochar, forming a biochar-graphene carrier. In step S103, during the nano-copper anchoring process, a quantitative amount of CuSO4 solution is added to the biochar and graphene support, and the adsorption is fully achieved by stirring. The concentration is controlled to ensure that the final CuSO4 solution loading reaches 5 wt%. Under stirring, sodium borohydride solution, a reducing agent, is added dropwise to carry out a reduction reaction, thereby removing the adsorbed Cu. 2+ The ions are reduced to zero-valent copper nanoparticles and firmly anchored on the graphene surface. Finally, the reaction products are collected by centrifugation and washing, and then dried to obtain the final powdered composite material.

[0014] According to the above technical solution, in the mixing process, S201 needs to be mixed in proportion according to the specified weight parts, and the specific materials include polymer substrate, composite material, toughening agent and antioxidant. The polymer substrate is an engineering plastic, specifically HIPS, APS or ABS, with a ratio of 100 parts. The composite material has a ratio of 5 parts. The toughening agent is a thermoplastic elastomer, specifically SBS, SEBS or POE, with a ratio of 8 parts. The antioxidant has a ratio of 0.5 parts. All materials are put into a high-speed mixer. In step S202, the mixed material is fed into a twin-screw extruder, and the twin-screw extruder performs segmented temperature-controlled extrusion granulation at a temperature of 190-220℃, specifically using six-segment temperature control. The strips extruded by the twin-screw extruder are cooled by water and air-dried, and then cut into uniform composite plastic masterbatches by a pelletizer. S203 involves manufacturing refrigerator liner, air duct, fan, drawer and lampshade components. Specifically, injection molding and vacuum adsorption molding processes are used to mold different types of polymer components, and finally the molded polymer components are assembled. Among them, injection molding is used for the rapid shaping of complex structural parts such as air ducts and fans. Specifically, composite plastic masterbatch is added to the hopper of the injection molding machine, heated and plasticized, and then injected into a closed mold cavity under high pressure. After holding the pressure and cooling, the mold is opened to obtain the part. Vacuum adsorption molding is used for the molding of inner liner panels. The inner liner panels are first formed into flat panels by extruding composite plastic masterbatch. Then, the panels are heated and softened. The heated and softened panels are placed on the refrigerator inner liner mold. The panels are adsorbed by the mold and vacuumed to make them tightly adsorbed onto the mold surface. After cooling, the inner liner parts of the specified shape are obtained. The S204 is a smart responsive coating of chitosan or sodium carboxymethyl cellulose applied to the surface of the molded component by a spraying process.

[0015] According to the above technical solution, S3 specifically involves testing the antibacterial rate of the drawer containing this material against Escherichia coli and Staphylococcus aureus in a simulated refrigerator environment. The simulated refrigerator environment has a temperature of 4°C and a humidity of 85%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Using a ternary composite material composed of nano-copper, graphene, and biochar as the core functional additive, and integrating it into the polymer components of the refrigerator, active antibacterial and preservation are achieved. This overcomes the defects of single components and replaces traditional silver-based or organic antibacterial agents. The antibacterial rate is improved through the synergistic effect of the ternary composite material. It also has the functions of broad-spectrum antibacterial, ethylene degradation, humidity regulation, and odor adsorption. It is suitable for long-term use in high-humidity environments. Biochar improves the dispersibility of nano-copper in plastics, avoids melt fracture, and facilitates easy and friendly processing. Nano-copper is an essential trace element for the human body, and biochar is degradable, safe, and environmentally friendly. Furthermore, the ternary composite material has the functions of antibacterial, moisture absorption, ethylene removal, and odor removal, meeting the requirements of multifunctional use and having high industrialization value.

[0017] 2. By adding composite materials as functional additives to the substrate of refrigerator manufacturing, the composite material uses biochar as a carrier to load graphene and copper nanoparticles. Biochar provides high specific surface area and adsorption capacity to capture ethylene and odor molecules. Graphene enhances conductivity and provides adhesion mechanical strength for copper nanoparticles, promotes electron transfer, and activates copper nanoparticles. Copper nanoparticles generate reactive oxygen and release copper ions through photocatalysis, destroying the structure of microorganisms. The copper ions are then bound by the "cage walls" formed by graphene, creating a potential difference that further enhances their antibacterial ability. The synergistic effect of the three enhances antibacterial activity, stability, and dispersibility. The refrigerator is prepared through melt blending and extrusion molding processes, giving it broad-spectrum antibacterial, mold-inhibiting, ethylene gas degradation, and free radical concentration suppression functions, significantly extending the shelf life of food, and is safe and environmentally friendly. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0019] In the attached diagram: Figure 1 This is a schematic diagram of the composition of the polymer components of the antibacterial and food-preserving refrigerator of the present invention; Figure 2 This is a flowchart of the steps in preparing the antibacterial and food-preserving refrigerator of the present invention; The following are labeled in the diagram: 1. Inner liner; 2. Air duct; 3. Fan; 4. Drawer; 5. Lampshade. Detailed Implementation

[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] Example: Figure 1 As shown, the present invention provides a technical solution, an antibacterial preservation refrigerator based on composite materials. The antibacterial preservation refrigerator uses a composite material composed of nano-copper, graphene and biochar as the core functional additive. The composite material uses biochar as a carrier to load graphene and nano-copper particles. Biochar avoids the agglomeration of nano-copper, and graphene enhances dispersibility and electronic conduction. By integrating it into the polymer components of the refrigerator, active antibacterial and preservation are achieved. The polymer components of the refrigerator include the inner liner, air duct, fan, drawer and light cover. The refrigerator also includes the following parts: Intelligent environmental monitoring system using temperature, humidity, ethylene concentration, and light sensors; A smart control system that integrates IoT technology with a smartphone app; An automatic control system that can automatically adjust temperature, humidity, and antibacterial function based on the refrigerator's internal environment data; An antibacterial and preservative material based on nano-copper, graphene, and biochar composite materials is embedded in the polymer components of a refrigerator. The composite material is used for antibacterial, ethylene removal, moisture absorption, and odor removal. The intelligent control system automatically adjusts the refrigerator's temperature, humidity, and antibacterial effect based on the following comprehensive objective function, as shown in the formula below: in: It is an energy efficiency function, a multidimensional function based on temperature (T), humidity (H), and ethylene concentration (C); This represents the deviation between the target temperature and the actual temperature. The deviation between the target humidity and the actual humidity; The antibacterial activity function depends on the performance of the composite material under temperature and humidity conditions; , , , These are the weighting coefficients for each parameter, representing the importance of energy efficiency, temperature and humidity regulation, and antibacterial effect, respectively.

[0022] Energy efficiency function The formula for indicating refrigerator energy efficiency, optimizing temperature, humidity, and ethylene concentration regulation, is: in: η is the energy efficiency coefficient, which represents the energy efficiency level of the refrigerator under different temperature and humidity conditions; and For target temperature and humidity, , , , These represent the maximum and minimum values ​​of temperature and humidity, respectively. C represents the ethylene concentration, indicating the metabolic activity of food; Antibacterial activity The antibacterial effect of the composite material is related to temperature and humidity conditions, as shown in the formula: in: This represents the antibacterial activity constant. For optimal antibacterial temperature and humidity conditions; γ and δ are adjustment parameters used to adjust the antibacterial effect according to the ethylene concentration (C); The attenuation effect of ethylene concentration on antibacterial efficacy; The refrigerator's temperature and humidity control and antibacterial function adjustment are achieved through the following comprehensive optimization objective function: The refrigerator automatically adjusts its internal operating status based on the actual environment and user-set temperature and humidity, optimizing antibacterial effects, energy efficiency, and preservation capabilities. The intelligent control system monitors environmental parameters such as temperature, humidity, and ethylene concentration in real time, automatically adjusting the refrigerator's operating status to optimize energy efficiency and extend the shelf life of food. This technology not only effectively inhibits the growth of bacteria and mold, delaying food spoilage, but also reduces energy consumption through intelligent adjustment, improving the refrigerator's energy-saving performance and demonstrating strong market application potential and environmental value.

[0023] Based on the above technical solution, biochar is used as a carrier phase. It is derived from biomass acidified under limited oxygen conditions to form a porous structure with a high specific surface area. The biomass includes bamboo powder and straw. The limited oxygen condition is carbonization at 500℃ for 2 hours. Biochar provides adsorption activity to capture ethylene gas, moisture and odor molecules, and reduce the respiration intensity of fruits and vegetables. Graphene is used as a reinforcing phase in the form of graphene oxide. Graphene oxide is grown on the surface of biochar by hydrothermal method to form a stable three-dimensional conductive network. The hydrothermal reaction conditions are: 180℃ for 12 hours. Graphene improves the mechanical strength and conductivity of the carrier, promotes electron transfer, activates the photocatalytic activity of nano-copper, and improves the barrier properties, reducing the respiration intensity of fruits and vegetables. Nano-copper was used as the active phase, and a chemical reduction method was employed to control the copper loading at 5 wt%. Specifically, the chemical reduction method involved the reaction of CuSO4 solution with NaBH4, anchoring the nano-copper onto the surface of graphene and biochar supports. The nano-copper then photocatalyzed the generation of reactive oxygen species (ROS) and copper ions (Cu). 2+ Released, disrupting microbial cell membranes and DNA, nano-copper, under visible light, generates photoelectrons, which are then transferred through graphene to produce reactive oxygen species. Simultaneously, Cu... 2+ It damages the cell membrane. And Cu 2+ Furthermore, the potential difference formed by the "cage wall" of graphene further enhances its antibacterial ability.

[0024] Based on the above technical solution, the polymer component liner, air duct, fan, drawer and lampshade are all made of engineering plastic as the base material, with 6wt% of a composite material composed of nano copper, graphene and biochar added. By adding composite materials as functional additives to the polymer components of the refrigerator, long-lasting antibacterial and preservation effects are achieved. Each polymer component is processed and prepared through melt blending and extrusion molding.

[0025] Based on the above technical solution, the substrate of the inner liner is selected as high-impact polystyrene (HIPS), which is suitable for vacuum adsorption molding. A large area of ​​antibacterial surface is provided inside the inner liner through uniformly dispersed composite materials. The base material for the air duct and fan is ABS resin, which is injection molded to ensure the antibacterial properties of the airflow channel. The base material for the drawers and lampshades is made of transparent material, specifically polyethylene terephthalate (PET), which balances aesthetics and food preservation.

[0026] Based on the above technical solution, functional additives also need to be added to the polymer components, specifically including toughening agents and antioxidants. The toughening agent is specifically SEBS thermoplastic elastomer, with an addition amount of 8 parts, which improves the impact resistance of the parts and prevents brittleness. The antioxidant prevents the material from oxidizing and degrading during processing, with an addition amount of 0.5 parts.

[0027] Based on the above technical solution, the polymer components also need to undergo special treatment. Specifically, a chitosan coating can be applied to the surface of each polymer component to release antibacterial components in a high-humidity environment and enhance the timeliness of antibacterial action.

[0028] like Figure 2 As shown, a method for preparing an antibacterial and food-preserving refrigerator based on composite materials includes the following preparation process: Step S1: Synthesis of ternary composite materials; Step S2, processing of polymer components for refrigerators; Step S3: Simulated environmental preservation test; S1 includes the following steps: Step S101, preparation of biochar; Step S102, graphene loading; Step S103, nano-copper anchoring; S2 includes the following steps: Step S201: Mix materials according to the weight ratio; Step S220: Melt blending extrusion; Step S203: Injection molding; Step S204, surface coating finishing.

[0029] Based on the above technical solution, S101, in the process of biochar preparation, biomass is carbonized under limited oxygen conditions at 500℃ for 2 hours to obtain primary biochar, and the biomass is selected from bamboo powder. Next, the ash is removed by acid washing, specifically by using hydrochloric acid to wash the biochar, remove impurities, increase surface functional groups and further expand pores, to obtain a pure porous biochar carrier. S102, during the graphene loading process, the biochar support and the graphene oxide dispersion GO were uniformly mixed and placed in a high-pressure reactor. The concentration of the graphene oxide dispersion was 10 mg / mL. During the hydrothermal reaction at 180℃ for 12 hours, graphene oxide is partially reduced and self-assembled, firmly adhering to the porous surface and channels of biochar to form a three-dimensional composite carrier, allowing graphene to grow uniformly on the surface of biochar, forming a biochar-graphene carrier. In the S103 process of nano-copper anchoring, a certain amount of CuSO4 solution is added to the biochar and graphene carrier, and the adsorption is fully achieved by stirring. The concentration is controlled to ensure that the final CuSO4 solution loading reaches 5 wt%. Under stirring, sodium borohydride solution (NaBH4) is added dropwise to carry out a reduction reaction, thereby removing the adsorbed Cu. 2+ The ions are reduced to zero-valent copper nanoparticles and firmly anchored on the graphene surface. Finally, the reaction products are collected by centrifugation and washing, and then dried to obtain the final powdered composite material.

[0030] Based on the above technical solution, S201, during the mixing process, it is necessary to mix the materials according to the specified weight proportions, and the specific materials include polymer substrate, composite material, toughening agent and antioxidant. The polymer substrate is an engineering plastic, specifically HIPS, with a ratio of 100 parts; the composite material has a ratio of 5 parts; the toughening agent is a thermoplastic elastomer, specifically SEBS, with a ratio of 8 parts; and the antioxidant has a ratio of 0.5 parts. Add all materials to a high-speed mixer and mix thoroughly to ensure uniform dispersion of each material; S202, the mixed material is fed into a twin-screw extruder, and the twin-screw extruder performs segmented temperature-controlled extrusion granulation at a temperature of 210℃ to ensure that the plastic is completely melted and the composite material is uniformly dispersed without being damaged. Specifically, six-segment temperature control is adopted to ensure uniform dispersion, avoid the agglomeration of nano-copper, and avoid thermal degradation. The strips extruded by the twin-screw extruder are cooled by water and air-dried, and then cut into uniform composite plastic masterbatches by a pelletizer. S203 manufactures refrigerator liner, air duct, fan, drawer and lampshade parts. Specifically, it uses injection molding and vacuum adsorption molding processes to mold different types of polymer parts, and finally assembles the molded polymer parts. Among them, injection molding is used for the rapid shaping of complex structural parts such as air ducts and fans. Specifically, composite plastic masterbatch is added to the hopper of the injection molding machine, heated and plasticized, and then injected into a closed mold cavity under high pressure. After holding the pressure and cooling, the mold is opened to obtain parts with precise dimensions. Vacuum adsorption molding is used for the molding of inner liner panels. The inner liner panels are first formed into flat panels by extruding composite plastic masterbatch. Then, the panels are heated and softened. The heated and softened panels are placed on the refrigerator inner liner mold. The panels are adsorbed by the mold and vacuumed to make them tightly adsorbed onto the mold surface. After cooling, the inner liner parts of the specified shape are obtained. S204 is a chitosan coating applied to the surface of molded parts through a spraying process to enhance the immediate antibacterial effect in high humidity environments.

[0031] Based on the above technical solution, S3, specifically, in a simulated refrigerator environment, the antibacterial rate of the drawer containing this material against Escherichia coli and Staphylococcus aureus is tested for preservation. The simulated refrigerator environment has a temperature of 4°C and a humidity of 85%. Preservation test results: Antibacterial rate against Escherichia coli and Staphylococcus aureus >99%, strawberry rot rate reduced by 50% after 7 days of storage, and also has the functions of removing ethylene and resisting odor.

[0032] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are 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. An antibacterial and food-preserving refrigerator based on composite materials, characterized in that: This antibacterial preservation refrigerator uses a composite material composed of nano-copper, graphene and biochar as the core functional additive. The composite material uses biochar as a carrier to load graphene and nano-copper particles. Biochar prevents nano-copper from agglomerating, while graphene enhances dispersibility and electronic conduction, and provides adhesion mechanical strength for nano-copper. By integrating it into the polymer components of the refrigerator, which include the inner liner, air duct, fan, drawers, and light cover; The refrigerator also includes the following parts: Intelligent environmental monitoring system using temperature, humidity, ethylene concentration, and light sensors; A smart control system that integrates IoT technology with a smartphone app; An automatic control system that can automatically adjust temperature, humidity, and antibacterial function based on the refrigerator's internal environment data; An antibacterial and preservative material based on nano-copper, graphene, and biochar composite materials is embedded in the polymer components of a refrigerator. The composite material is used for antibacterial, ethylene removal, moisture absorption, and odor removal. The intelligent control system automatically adjusts the refrigerator's temperature, humidity, and antibacterial effect based on the following comprehensive objective function, as shown in the formula below: in: It is an energy efficiency function, a multidimensional function based on temperature (T), humidity (H), and ethylene concentration (C); This represents the deviation between the target temperature and the actual temperature. The deviation between the target humidity and the actual humidity; The antibacterial activity function depends on the performance of the composite material under temperature and humidity conditions; , , , These are the weighting coefficients for each parameter, representing the importance of energy efficiency, temperature and humidity regulation, and antibacterial effect, respectively.

2. The antibacterial and food-preserving refrigerator based on composite materials according to claim 1, characterized in that: The biochar, as a carrier phase, is derived from the acidification treatment of biomass under limited oxygen conditions. The biochar captures ethylene gas, moisture, and odor molecules. The graphene is used as a reinforcing phase and is composited in the form of graphene oxide. Graphene oxide is grown on the surface of biochar by hydrothermal method to form a stable three-dimensional conductive network. Graphene promotes electron transfer and activates the photocatalytic activity of nano-copper. The nano-copper, serving as the active phase, is chemically reduced to control the copper loading and anchor it to the surface of the graphene and biochar support. The nano-copper generates reactive oxygen species and releases copper ions through photocatalysis, disrupting microbial cell membranes and DNA. Under visible light, the nano-copper excites photogenerated electrons, which are then transferred through graphene to generate reactive oxygen species. Simultaneously, Cu... 2+ Disrupts cell membranes, while Cu 2+ Furthermore, the potential difference formed by the "cage wall" of graphene further enhances its antibacterial ability.

3. The antibacterial preservation refrigerator based on composite materials according to claim 1, characterized in that: The polymer components, including the inner liner, air duct, fan, drawer, and lampshade, are all made of engineering plastics as the base material, with 1-10 wt% of a composite material composed of nano-copper, graphene, and biochar added. Composite materials were added as functional additives to the polymer components of the refrigerator, and each polymer component was prepared by melt blending and extrusion molding.

4. The antibacterial preservation refrigerator based on composite materials according to claim 3, characterized in that: The inner liner is made of a blend of high-impact polystyrene (HIPS) or PP-modified HIPS (APS), and is formed by extrusion and vacuum adsorption. The base material for the air duct and fan is selected from high-impact polystyrene HIPS or ABS resin, and is injection molded. The base material for the drawer and lampshade is made of transparent material, specifically polyethylene terephthalate (PET) or its copolymers PETG and PCTG.

5. The antibacterial preservation refrigerator based on composite materials according to claim 3, characterized in that: The polymer components also require the addition of functional additives, specifically toughening agents and antioxidants. The toughening agent is a thermoplastic elastomer of SEBS, SBS or POE, and its addition amount is 5-10 parts, while the antioxidant addition amount is 0.5-1 parts.

6. The antibacterial preservation refrigerator based on composite materials according to claim 3, characterized in that: The polymer components also require special treatment, specifically, the surface of each polymer component can be coated with chitosan or sodium carboxymethyl cellulose.

7. A method for preparing an antibacterial and food-preserving refrigerator based on composite materials according to any one of claims 1-6, characterized in that: The preparation process includes the following: Step S1: Synthesis of ternary composite materials; Step S2, processing of polymer components for refrigerator; Step S3: Simulated environmental preservation test; S1 includes the following steps: Step S101, preparation of biochar; Step S102, graphene loading; Step S103, nano-copper anchoring; S2 includes the following steps: Step S201: Mix materials according to the weight ratio; Step S220: Melt blending extrusion; Step S203: Injection molding; Step S204, surface coating finishing.

8. The method for preparing an antibacterial and food-preserving refrigerator based on composite materials according to claim 7, characterized in that: In the S101 process, biomass is carbonized under limited oxygen conditions at 500°C for 2 hours to obtain primary biochar. The biomass can be straw, wood, or bamboo powder. Next, the ash is removed by acid washing, specifically by using hydrochloric acid or sulfuric acid to wash the biochar, resulting in a porous biochar carrier; In step S102, during the graphene loading process, the biochar carrier and the graphene oxide dispersion are uniformly mixed and placed in a high-pressure reactor. The concentration of the graphene oxide dispersion is 10 mg / mL. During the hydrothermal reaction at 180℃ for 12 hours, graphene oxide is partially reduced and self-assembled, firmly adhering to the porous surface and channels of biochar to form a three-dimensional composite carrier, allowing graphene to grow uniformly on the surface of biochar, forming a biochar-graphene carrier. In step S103, during the nano-copper anchoring process, a quantitative amount of CuSO4 solution is added to the biochar and graphene support, and the adsorption is fully achieved by stirring. The concentration is controlled to ensure that the final CuSO4 solution loading reaches 5 wt%. Under stirring, sodium borohydride solution, a reducing agent, is added dropwise to carry out a reduction reaction, thereby removing the adsorbed Cu. 2+ The ions are reduced to zero-valent copper nanoparticles and firmly anchored on the graphene surface. Finally, the reaction products are collected by centrifugation and washing, and then dried to obtain the final powdered composite material.

9. The method for preparing an antibacterial and food-preserving refrigerator based on composite materials according to claim 7, characterized in that: The S201, during the mixing process, needs to be mixed in proportion according to the specified weight parts. The specific materials include polymer substrate, composite material, toughening agent and antioxidant. The polymer substrate is an engineering plastic, specifically HIPS, APS or ABS, with a ratio of 100 parts. The composite material has a ratio of 5 parts. The toughening agent is a thermoplastic elastomer, specifically SBS, SEBS or POE, with a ratio of 8 parts. The antioxidant has a ratio of 0.5 parts. All materials are put into a high-speed mixer. In step S202, the mixed material is fed into a twin-screw extruder, and the twin-screw extruder performs segmented temperature-controlled extrusion granulation at a temperature of 190-220℃, specifically using six-segment temperature control. The strips extruded by the twin-screw extruder are cooled by water and air-dried, and then cut into uniform composite plastic masterbatches by a pelletizer. S203 involves manufacturing refrigerator liner, air duct, fan, drawer and lampshade components. Specifically, injection molding and vacuum adsorption molding processes are used to mold different types of polymer components, and finally the molded polymer components are assembled. Among them, injection molding is used for the rapid shaping of complex structural parts such as air ducts and fans. Specifically, composite plastic masterbatch is added to the hopper of the injection molding machine, heated and plasticized, and then injected into a closed mold cavity under high pressure. After holding the pressure and cooling, the mold is opened to obtain the part. Vacuum adsorption molding is used for the molding of inner liner panels. The inner liner panels are first formed into flat panels by extruding composite plastic masterbatch. Then, the panels are heated and softened. The heated and softened panels are placed on the refrigerator inner liner mold. The panels are adsorbed by the mold and vacuumed to make them tightly adsorbed onto the mold surface. After cooling, the inner liner parts of the specified shape are obtained. The S204 is a smart responsive coating of chitosan or sodium carboxymethyl cellulose applied to the surface of the molded component by a spraying process.

10. A method for preparing an antibacterial and food-preserving refrigerator based on composite materials according to claim 7, characterized in that: Specifically, in a simulated refrigerator environment, the drawer containing this material is tested for its antibacterial rate against Escherichia coli and Staphylococcus aureus. The simulated refrigerator environment has a temperature of 4°C and a humidity of 85%.

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