Antibacterial high light flame-retardant uv-resistant polypropylene composite material and preparation method thereof

Abstract

An antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material and its preparation method are disclosed. This invention relates to the field of polypropylene composite material technology. It is prepared from the following raw materials in parts by weight: 60-80 parts high-gloss polypropylene, 1-5 parts composite antibacterial agent, 5-15 parts halogen-free flame-retardant synergistic system, 0.5-3 parts UV-resistant compound system, 2-8 parts compatibilizer, and 0.1-1 parts lubricant. The composite antibacterial agent is a mixture of organic antibacterial agent, inorganic antibacterial agent, and dispersant. The halogen-free flame-retardant synergistic system is a mixture of phosphate ester flame retardant, melamine cyanurate, and modified nano-synergistic agent. The UV-resistant compound system is a mixture of UV absorber and hindered amine light stabilizer. Through innovative formula design and process optimization, the antibacterial, high-gloss, flame-retardant, and UV-resistant properties are simultaneously improved, while ensuring stable mechanical properties and excellent processing performance. The preparation process is simple and controllable, with moderate cost, meeting the needs of high-end applications such as outdoor building materials, high-end home appliance casings, and automotive interiors.

Description

Technical Field

[0001] This invention relates to the field of polypropylene composite material technology, specifically to an antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material and its preparation method. Background Technology

[0002] Polypropylene (PP) is a high-performance general-purpose plastic with advantages such as low density (0.90-0.91 g / cm³), good processing performance, high mechanical strength, low cost, and excellent chemical stability. It is widely used in many fields such as building materials, home appliances, automobiles, packaging, and medical devices, and is one of the plastic varieties with the largest output and widest application.

[0003] However, pure polypropylene has significant performance defects that limit its promotion in high-end applications: First, it has extremely poor antibacterial properties, easily breeding harmful bacteria such as Escherichia coli and Staphylococcus aureus. Especially in humid and high-temperature environments, bacteria multiply rapidly, leading not only to mold and deterioration of the material but also potential harm to human health. Second, it has insufficient flame retardant properties. The limiting oxygen index (LOI) of pure polypropylene is only 17-18%, classifying it as a flammable material. While it burns without dripping and produces little smoke, its rapid combustion makes it difficult to meet the flame retardant safety requirements of construction, home appliances, and automobiles. Third, it has poor resistance to ultraviolet (UV) aging. Long-term exposure to outdoor UV radiation can cause photo-oxidative degradation of the polypropylene molecular chains, leading to yellowing, brittleness, and cracking, resulting in a sharp decline in mechanical and aesthetic properties and severely shortening the material's service life. Fourth, its high-gloss properties are easily compromised. After adding functional additives such as antibacterial, flame-retardant, and UV-resistant additives, the poor compatibility and uneven dispersion between the additives and the polypropylene matrix can easily lead to increased surface roughness and decreased gloss, failing to meet the high-gloss appearance requirements of high-end home appliance casings and decorative materials.

[0004] Currently, existing technologies for functional modification of polypropylene composites mostly focus on single-performance modification or simple functional superposition, failing to achieve simultaneous optimization of four properties: antibacterial, high gloss, flame retardant, and UV resistant. Therefore, developing a polypropylene composite material that simultaneously achieves excellent antibacterial, high gloss, flame retardant, and UV resistant properties, while also possessing stable mechanical properties, good compatibility, a simple preparation process, and moderate cost, to overcome the shortcomings of existing technologies, has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing an antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material and its preparation method. Through innovative formula design and process optimization, the antibacterial, high-gloss, flame-retardant, and UV-resistant properties are simultaneously improved, while ensuring stable mechanical properties and excellent processing performance. The preparation process is simple and controllable, with moderate cost, meeting the needs of high-end application scenarios such as outdoor building materials, high-end home appliance shells, and automotive interiors.

[0006] To achieve the above objectives, the antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material of the present invention is prepared from the following raw materials in parts by weight: 60-80 parts of high-gloss polypropylene, 1-5 parts of composite antibacterial agent, 5-15 parts of halogen-free flame-retardant synergistic system, 0.5-3 parts of UV-resistant compound system, 2-8 parts of compatibilizer, and 0.1-1 parts of lubricant; wherein the composite antibacterial agent is a compound of organic antibacterial agent, inorganic antibacterial agent, and dispersant; the halogen-free flame-retardant synergistic system is a compound of phosphate ester flame retardant, melamine cyanurate, and modified nano-synergist; and the UV-resistant compound system is a compound of UV absorber and hindered amine light stabilizer.

[0007] Furthermore, the composite antibacterial agent is composed of the following components in the following weight ratio: organic antibacterial agent: inorganic antibacterial agent: dispersant = 3:1:1; the organic antibacterial agent is dodecyl dimethyl benzyl ammonium chloride, the inorganic antibacterial agent is nano-silver particles (particle size 50-100nm), and the dispersant is chitosan.

[0008] Furthermore, the halogen-free flame retardant synergistic system is composed of the following components in the following weight ratio: phosphate ester flame retardant: melamine cyanurate: modified nano synergist = 4:3:3; the phosphate ester flame retardant is triphenyl phosphate, and the modified nano synergist is silane coupling agent KH-550 modified nano magnesium hydroxide (particle size 20-50nm).

[0009] Furthermore, the preparation method of the silane coupling agent KH-550 modified nano magnesium hydroxide is as follows: add nano magnesium hydroxide to deionized water and ultrasonically disperse for 30-40 min to obtain a dispersion; add 2-3% by mass of nano magnesium hydroxide and silane coupling agent KH-550 to the dispersion, stir and react at 60-70℃ for 2-3 h, filter, wash and dry to obtain silane coupling agent KH-550 modified nano magnesium hydroxide.

[0010] Furthermore, the UV-resistant compound system is composed of the following components in the following weight ratio: UV absorber: hindered amine light stabilizer = 2:2; the UV absorber is benzotriazole UV-327, and the hindered amine light stabilizer is HALS 770.

[0011] Furthermore, the compatibilizer is a compound of maleic anhydride-grafted polypropylene (PP-g-MAH) and polyolefin elastomer (POE) in a weight ratio of 3:2; the high-gloss polypropylene is homopolymer polypropylene with a melt index of 8-15 g / 10 min and a gloss (60°) ≥90% under the test conditions of 230℃ / 2.16kg.

[0012] Furthermore, the lubricant is calcium stearate; the performance indicators of the composite material meet the following requirements: antibacterial rate (against Escherichia coli and Staphylococcus aureus) ≥99%, flame retardancy rating reaches UL94 V-0 level (3.2mm), limiting oxygen index (LOI) ≥28%, gloss (60°) ≥85%, and after 1000h UV aging, tensile strength retention rate ≥85% and impact strength retention rate ≥80%.

[0013] The preparation method of the antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material of the present invention is characterized by comprising the following steps: Step 1, Raw material pretreatment: Place the high-gloss polypropylene in a constant temperature drying oven at 80-85℃ and dry for 2-3 hours to remove moisture; place the composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer, and lubricant in a constant temperature drying oven at 70-75℃ and dry for 1-2 hours respectively, for later use. Step 2, Mixing: According to the preset weight parts, add the pretreated high-gloss polypropylene, composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer and lubricant into the high-speed mixer in sequence. Set the mixing temperature to 80-100℃, the stirring speed to 800-1000r / min, and mix for 10-15min to obtain a uniform premix. Step 3, Extrusion Granulation: The premix obtained in Step 2 is fed into a twin-screw extruder for melt mixing and extrusion granulation. The temperature of each section of the twin-screw extruder is controlled as follows: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 190-200℃, and Die Head 200-210℃. The screw speed is 300-350 r / min, and the traction speed is 2-3 m / min. After granulation, particles with a particle size of 2-3 mm are obtained, which are then cooled, sieved, and ready for use. Step 4, Molding: The granules obtained in Step 3 are fed into an injection molding machine and injection molded to obtain the finished product. The injection temperature is controlled at 190-210℃, the injection pressure at 80-100MPa, the holding pressure at 60-70MPa, the holding time at 10-15s, and the cooling time at 20-30s.

[0014] Furthermore, in step 3, the length-to-diameter ratio of the twin-screw extruder is 40:1, and the feeding speed of the extruder is 20-25 kg / h; the cooling adopts a combination of air cooling and water cooling, with an air cooling temperature of 25-30℃ and a water cooling temperature of 15-20℃.

[0015] Furthermore, in step 4, the clamping force of the injection molding machine is 200-250t, and the injection speed is 50-60mm / s; the molded finished product needs to be placed in a constant temperature aging chamber at 60-70℃ for 2-3 hours to eliminate internal stress.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides an antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material and its preparation method. Addressing the technical problems of existing polypropylene composite materials, such as difficulty in simultaneously achieving antibacterial, flame-retardant, and UV-resistant properties, easy degradation of high gloss by functional additives, severe attenuation of mechanical properties, poor dispersibility of antibacterial agents, low flame-retardant efficiency, poor UV aging resistance, and poor compatibility between functional additives and the matrix, this invention achieves simultaneous improvement in antibacterial, high-gloss, flame-retardant, and UV-resistant properties through innovative formulation design and process optimization. Simultaneously, it ensures stable mechanical properties and excellent processing performance of the material. The preparation process is simple and controllable, with moderate cost, meeting the needs of high-end application scenarios such as outdoor building materials, high-end home appliance casings, and automotive interiors. Attached Figure Description

[0017] Figure 1 This is a table of experimental data for the embodiments and comparative samples of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. The preferred embodiments described are only examples. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material described in this example is prepared from the following raw materials in parts by weight: 70 parts high-gloss polypropylene, 2 parts composite antibacterial agent, 10 parts halogen-free flame-retardant synergistic system, 1 part UV-resistant compound system, 5 parts compatibilizer, and 0.5 parts lubricant.

[0020] in: Composite antibacterial agent: Dodecyl dimethyl benzyl ammonium chloride: nano silver particles: chitosan = 3:1:1 (weight ratio), total weight 2 parts; Halogen-free flame retardant synergistic system: Triphenyl phosphate: MCA: Modified nano magnesium hydroxide = 4:3:3 (weight ratio), total weight 10 parts; UV-resistant compound system: UV-327:HALS 770 = 2:2 (by weight), total weight 1 part; Compatibilizer: PP-g-MAH:POE = 3:2 (by weight), total weight 5 parts; Lubricant: 0.5 parts calcium stearate.

[0021] The preparation method of the antibacterial, high-light-retardant, and UV-resistant polypropylene composite material described in this embodiment is as follows: Step 1, Raw material pretreatment: Place the high-gloss polypropylene in a constant temperature drying oven at 82℃ and dry for 2.5h; place the composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer, and lubricant in a constant temperature drying oven at 72℃ and dry for 1.5h respectively, and cool to room temperature for later use. Step 2, Mixing: Add all the pretreated raw materials to the high-speed mixer in sequence, set the mixing temperature to 90℃, the stirring speed to 900r / min, and mix for 12min to obtain a uniform premix. Step 3, Extrusion Granulation: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The feeding speed is 22 kg / h, and the temperature of each section is controlled as follows: Zone 1 165℃, Zone 2 175℃, Zone 3 185℃, Zone 4 195℃, and Die Head 205℃. The screw speed is 320 r / min, and the traction speed is 2.5 m / min. After extrusion, the material is cooled by a combination of air cooling (28℃) and water cooling (18℃). After cooling to room temperature, the material is granulated to obtain granules with a particle size of 2.5 mm. The granules are then sieved and set aside for later use. Step 4, Molding: The granules are fed into an injection molding machine with a clamping force of 220t, an injection speed of 55mm / s, an injection temperature of 200℃, an injection pressure of 90MPa, a holding pressure of 65MPa, a holding time of 12s, and a cooling time of 25s. After molding, the finished product is placed in a constant temperature aging chamber at 65℃ for 2.5h to eliminate internal stress and obtain the final product.

[0022] Example 2: The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material described in this example is prepared from the following raw materials in parts by weight: 75 parts high-gloss polypropylene, 3 parts composite antibacterial agent, 8 parts halogen-free flame-retardant synergistic system, 1.5 parts UV-resistant compound system, 4 parts compatibilizer, and 0.3 parts lubricant.

[0023] in: Composite antibacterial agent: Dodecyl dimethyl benzyl ammonium chloride: nano silver particles: chitosan = 3:1:1 (weight ratio), total weight 3 parts; Halogen-free flame retardant synergistic system: Triphenyl phosphate: MCA: Modified nano magnesium hydroxide = 4:3:3 (weight ratio), total weight 8 parts; UV-resistant compound system: UV-327:HALS 770 = 2:2 (by weight), total weight 1.5 parts; Compatibilizer: PP-g-MAH:POE = 3:2 (by weight), total weight 4 parts; Lubricant: 0.3 parts calcium stearate.

[0024] The preparation method of the antibacterial, high-light-retardant, and UV-resistant polypropylene composite material described in this embodiment is as follows: Step 1, Raw material pretreatment: Place the high-gloss polypropylene in a constant temperature drying oven at 80℃ and dry for 3 hours; place the composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer, and lubricant in a constant temperature drying oven at 70℃ and dry for 2 hours, then cool to room temperature for later use. Step 2, Mixing: Add all the pretreated raw materials to the high-speed mixer in sequence, set the mixing temperature to 80℃, the stirring speed to 800r / min, and mix for 15min to obtain a uniform premix. Step 3, Extrusion Granulation: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The feeding speed is 20 kg / h, and the temperature of each section is controlled as follows: Zone 1 160℃, Zone 2 170℃, Zone 3 180℃, Zone 4 190℃, and Die Head 200℃. The screw speed is 300 r / min, and the traction speed is 2 m / min. After extrusion, the material is cooled by a combination of air cooling (25℃) and water cooling (15℃). After cooling to room temperature, the material is granulated to obtain granules with a particle size of 2 mm. After sieving, the granules are ready for use. Step 4, Molding: The granules are fed into an injection molding machine with a clamping force of 200t, an injection speed of 50mm / s, an injection temperature of 190℃, an injection pressure of 80MPa, a holding pressure of 60MPa, a holding time of 10s, and a cooling time of 20s. After molding, the finished product is placed in a constant temperature aging chamber at 60℃ for 3 hours to eliminate internal stress and obtain the final product.

[0025] Example 3: The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material described in this example is prepared from the following raw materials in parts by weight: 65 parts high-gloss polypropylene, 4 parts composite antibacterial agent, 12 parts halogen-free flame-retardant synergistic system, 2 parts UV-resistant compound system, 6 parts compatibilizer, and 0.7 parts lubricant.

[0026] in: Composite antibacterial agent: Dodecyl dimethyl benzyl ammonium chloride: nano silver particles: chitosan = 3:1:1 (weight ratio), total weight 4 parts; Halogen-free flame retardant synergistic system: Triphenyl phosphate: MCA: Modified nano magnesium hydroxide = 4:3:3 (weight ratio), total weight 12 parts; UV-resistant compound system: UV-327:HALS 770 = 2:2 (by weight), total weight 2 parts; Compatibilizer: PP-g-MAH:POE = 3:2 (by weight), total weight 6 parts; Lubricant: 0.7 parts calcium stearate.

[0027] The preparation method of the antibacterial, high-light-retardant, and UV-resistant polypropylene composite material described in this embodiment is as follows: Step 1, Raw material pretreatment: Place the high-gloss polypropylene in a constant temperature drying oven at 85℃ and dry for 2 hours; place the composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer, and lubricant in a constant temperature drying oven at 75℃ and dry for 1 hour, then cool to room temperature for later use. Step 2, Mixing: Add all the pretreated raw materials to the high-speed mixer in sequence, set the mixing temperature to 100℃, the stirring speed to 1000r / min, mix for 10min, and obtain a uniform premix. Step 3, Extrusion Granulation: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The feeding speed is 25 kg / h, and the temperature of each section is controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 200℃, and Die Head 210℃. The screw speed is 350 r / min, and the traction speed is 3 m / min. After extrusion, the material is cooled by a combination of air cooling (30℃) and water cooling (20℃). After cooling to room temperature, the material is granulated to obtain granules with a particle size of 3 mm. After sieving, the granules are ready for use. Step 4, Molding: The granules are fed into an injection molding machine with a clamping force of 250t, an injection speed of 60mm / s, an injection temperature of 210℃, an injection pressure of 100MPa, a holding pressure of 70MPa, a holding time of 15s, and a cooling time of 30s. After molding, the finished product is placed in a constant temperature drying oven at 70℃ for 2 hours to eliminate internal stress and obtain the final product.

[0028] The raw materials used in Examples 1-3 were all commercially available conventional products with the following specifications to ensure the repeatability of the experiments: High-gloss polypropylene: Homopolymer polypropylene, melt index of 10g / 10min under test conditions of 230℃ / 2.16kg, gloss (60°) 92%, density 0.905g / cm³, tensile strength 34MPa, impact strength 19.5kJ / m². Dodecyl dimethyl benzyl ammonium chloride: Commercially available, 98% purity; Silver nanoparticles: 80nm particle size, 99.9% purity; Chitosan: Degree of deacetylation ≥ 90%; Triphenyl phosphate: Commercially available, 99% purity; Melamine cyanurate (MCA): Commercially available, 99% purity; Nano magnesium hydroxide: particle size 30nm, purity 99%; Silane coupling agent KH-550: Commercially available, 98% purity; UV-327: Benzotriazole, commercially available, 99% purity; HALS 770: Hindered amine light stabilizer, commercially available, 99% purity; PP-g-MAH: Maleic anhydride-grafted polypropylene, grafting rate 1.2%; POE: Polyolefin elastomer, melt index 2 g / 10 min (230℃ / 2.16 kg); Calcium stearate: Commercially available, 98% purity.

[0029] In Examples 1-3, the preparation method of silane coupling agent KH-550 modified nano-magnesium hydroxide was as follows: nano-magnesium hydroxide was added to deionized water and ultrasonically dispersed for 35 min (ultrasonic power 250W) to obtain a uniform dispersion; 2.5% by mass of nano-magnesium hydroxide and silane coupling agent KH-550 were added to the dispersion, and the mixture was stirred at 65℃ for 2.5 h (stirring speed 350 r / min). After the reaction was completed, the mixture was filtered, washed three times with deionized water, and then placed in a constant temperature drying oven at 82℃ for 2.5 h. After cooling to room temperature, silane coupling agent KH-550 modified nano-magnesium hydroxide was obtained.

[0030] Compared with the prior art, the beneficial effects of the present invention are: 1. Excellent overall performance and multi-functional synergistic optimization: This invention achieves simultaneous improvement in antibacterial, high gloss, flame retardancy, UV resistance and mechanical properties. The antibacterial rate (against Escherichia coli and Staphylococcus aureus) of the material is ≥99%, the flame retardancy rating reaches UL94 V-0 level (3.2mm), the limiting oxygen index (LOI) is ≥28%, the gloss (60°) is ≥85%, and after 1000h UV aging, the tensile strength retention rate is ≥85% and the impact strength retention rate is ≥80%. It solves the technical problems of existing technologies, such as difficulty in achieving multiple functions, easy damage to high gloss, and serious degradation of mechanical properties. The overall performance is superior to existing similar products.

[0031] 2. Excellent stability, strong durability, and long service life: Chitosan in the composite antibacterial agent effectively solves the problem of agglomeration of nano-silver particles, ensuring uniform dispersion of the antibacterial agent. Simultaneously, the sustained-release effect of chitosan prolongs the antibacterial durability, allowing the material to maintain excellent antibacterial effects even after long-term use. Modified nano-magnesium hydroxide improves the compatibility of the flame-retardant system with the polypropylene matrix, resulting in stable flame-retardant effects and no flame-retardant precipitation issues. The UV-resistant compound system features a synergistic effect of UV absorbers and light stabilizers, providing excellent UV aging resistance. The material is less prone to yellowing, brittleness, and cracking when exposed to outdoor environments for extended periods, significantly extending its outdoor service life (by more than 30% compared to existing products).

[0032] 3. Excellent processing performance, enabling industrial production: The preparation process of this invention is simple and highly controllable. It can achieve industrial mass production using conventional high-speed mixers, twin-screw extruders, injection molding machines, and other equipment without the need for special equipment, resulting in high production efficiency. The parameters of each step are precisely controllable, which can effectively ensure the stability of product quality and reduce the defect rate during the production process. At the same time, the amount of functional additives added is reasonable, avoiding processing difficulties caused by excessive additives, and the material has excellent extrusion and injection molding performance.

[0033] 4. Moderate production cost and environmentally friendly: The raw materials used in this invention are all commercially available conventional products, which are easy to purchase, and the amount of functional additives added is reasonable (the total amount added is controlled at 10-30 parts). Compared with existing high-end functional polypropylene composite materials, the production cost is reduced by 10-15%, which has a significant cost advantage. At the same time, the halogen-free flame retardant system does not produce toxic or harmful gases and smoke when burning, and the antibacterial agent, lubricant and other components are non-toxic and environmentally friendly, which meets the environmental protection requirements of national environmental protection policies and high-end application scenarios.

[0034] 5. Wide range of applications, high practical value and great potential for promotion: The composite material of this invention has excellent antibacterial, high gloss, flame retardant, UV resistant and mechanical properties. It can be widely used in outdoor building materials (such as outdoor railings, decorative panels and sunshades), high-end home appliance shells (such as air conditioner, refrigerator and washing machine shells), automotive interiors (such as dashboards, door panels and armrests), food packaging, medical device shells and other fields with high requirements for antibacterial, high gloss, flame retardant and UV resistant properties. It has broad market application prospects and has great practical value and promotion significance.

[0035] To verify the beneficial effects of the present invention, four sets of comparative samples were set up, namely blank sample, comparative sample 1 (single antibacterial agent), comparative sample 2 (single flame retardant), and comparative sample 3 (single UV resistant agent). The formulation, preparation method (consistent with Example 1), and performance test results of each comparative sample are as follows. By comparing with the examples, the innovation and superiority of the present invention are highlighted.

[0036] Comparative Sample 1 (Blank Sample): Only 79 parts of high-gloss polypropylene and 0.5 parts of lubricant were used. No composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, or compatibilizer were added. The preparation method was completely consistent with Example 1.

[0037] Comparative Sample 2 (Single Antibacterial Agent): The formulation consists of 70 parts of high-gloss polypropylene, 2 parts of a single antibacterial agent (dodecyl dimethyl benzyl ammonium chloride), 10 parts of a halogen-free flame retardant synergistic system, 1 part of a UV-resistant compound system, 5 parts of a compatibilizer, and 0.5 parts of a lubricant. The types and proportions of the halogen-free flame retardant synergistic system, the UV-resistant compound system, the compatibilizer, and the lubricant are the same as in Example 1, and the preparation method is the same as in Example 1 (only the compound antibacterial agent is replaced with a single organic antibacterial agent).

[0038] Comparative Sample 3 (single flame retardant): The formulation consists of 70 parts high-gloss polypropylene, 2 parts composite antibacterial agent, 10 parts single flame retardant (triphenyl phosphate), 1 part UV-resistant compound system, 5 parts compatibilizer, and 0.5 parts lubricant. The types and proportions of the composite antibacterial agent, UV-resistant compound system, compatibilizer, and lubricant are the same as in Example 1, and the preparation method is the same as in Example 1 (only the halogen-free flame retardant synergistic system is replaced with a single flame retardant).

[0039] Comparative Sample 4 (Single UV absorber): The formulation consists of 70 parts high-gloss polypropylene, 2 parts composite antibacterial agent, 10 parts halogen-free flame retardant synergistic system, 1 part single UV absorber (UV-327), 5 parts compatibilizer, and 0.5 parts lubricant. The types and proportions of the composite antibacterial agent, halogen-free flame retardant synergistic system, compatibilizer, and lubricant are the same as in Example 1, and the preparation method is the same as in Example 1 (only the UV absorber compound system is replaced with a single UV absorber).

[0040] In the comparative experiments, the performance testing methods for each sample were all performed in accordance with national or industry standards to ensure the accuracy and authority of the test results. The specific test methods are as follows: 1. Antibacterial rate: Tested according to GB / T 31402-2015 "Test method for antibacterial properties of plastic surfaces", the test strains were Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 6538), and the test sample thickness was 3.2 mm; 2. Flame retardant performance: The flame retardant rating was tested according to UL94 standard (sample thickness 3.2mm), and the limiting oxygen index (LOI) was tested according to GB / T 2406-2021 "Determination of Burning Behavior by Oxygen Index Method for Plastics". 3. Gloss: Tested according to GB / T 8807-1988 "Test Method for Mirror Gloss of Plastics", with a test angle of 60°; 4. UV aging resistance: Tested according to GB / T 16422.2-2014 "Laboratory Light Source Exposure Test Method for Plastics Part 2: Xenon Arc Lamp", using xenon lamp aging for 1000h, testing the tensile strength and impact strength before and after aging, and calculating the mechanical property retention rate. 5. Mechanical properties: Tensile strength was tested according to GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General rules", and impact strength was tested according to GB / T 1843-2008 "Determination of impact strength of plastic cantilever beams" (simply supported beams without notches). The thickness of the test sample was 3.2 mm.

[0041] For detailed test results, please see Figure 1 ,Depend on Figure 1The performance test data clearly show that the antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite materials prepared in Examples 1-3 of this invention exhibit excellent performance in antibacterial, flame-retardant, high-gloss, UV aging resistance, and mechanical properties. Furthermore, they achieve synergistic optimization of multiple properties, significantly outperforming the comparative samples. Specific analysis is as follows: 1. Antibacterial Performance Analysis: The antibacterial rates of Examples 1-3 against Escherichia coli and Staphylococcus aureus all reached over 99.5%, with the highest reaching 99.8 / 99.7%, fully meeting the preset performance index of ≥99%, achieving broad-spectrum and highly efficient antibacterial activity. The antibacterial rate of Comparative Sample 1 (blank sample) was only 8.2 / 7.8%, almost without any antibacterial effect, indicating that the antibacterial component added in this invention is key to achieving the antibacterial function. The antibacterial rate of Comparative Sample 2 (single antibacterial agent) was 90.5 / 89.8%, far lower than the examples, confirming the synergistic advantages of the "organic-inorganic-dispersant" composite antibacterial system of this invention—chitosan effectively solved the aggregation problem of nano-silver particles, making the antibacterial agent more uniformly dispersed. Simultaneously, it synergistically broadened the antibacterial spectrum and prolonged the antibacterial durability with dodecyl dimethyl benzyl ammonium chloride, completely solving the technical pain points of low antibacterial efficiency and narrow antibacterial range of single antibacterial agents.

[0042] 2. Flame retardant performance analysis: The flame retardant ratings of Examples 1-3 all reach UL94 V-0 level (3.2mm), with a limiting oxygen index (LOI) ≥28.2%, and a maximum of 29.0%, which meets the preset flame retardant performance requirements. Moreover, the halogen-free flame retardant system is environmentally friendly and pollution-free. Comparative sample 1 (blank sample) has a flame retardancy rating of only UL94 HB level and an LOI of only 21.0%, classifying it as a flammable material that fails to meet safety requirements. Comparative sample 3 (single flame retardant) has a flame retardancy rating of only UL94 V-2 level and an LOI of 25.1%, exhibiting poor flame retardancy and significant degradation in mechanical and gloss properties (tensile strength 29.8 MPa, gloss 82%). This demonstrates that the halogen-free flame retardant synergistic system of triphenyl phosphate-MCA-modified nano magnesium hydroxide designed in this invention achieves excellent flame retardancy with an addition amount of only 5-15 parts through the synergistic effect of the three components. It also avoids the defects of traditional single flame retardant additions that lead to excessive addition and damage to the overall material performance, achieving synergistic optimization of "flame retardancy + high gloss + mechanical stability".

[0043] 3. High-gloss performance analysis: The gloss (60°) of Examples 1-3 remained between 87% and 89%, meeting the preset requirement of ≥85%, and close to the 92% of the blank sample. This indicates that the functional additive system and the compatibility system of the present invention work synergistically to effectively avoid the damage to high-gloss performance caused by uneven dispersion of functional components. The gloss of Comparative Sample 3 (single flame retardant) was only 82%, and the gloss of Comparative Sample 4 (single UV resistant agent) was 86%, both lower than the examples. The core reason is that the present invention reduces the interface defects between the functional additive and the polypropylene matrix by modifying nano-magnesium hydroxide with a silane coupling agent, precisely controlling the UV resistant compound ratio, and regulating the compatibility of PP-g-MAH and POE, ensuring the smoothness of the material surface and achieving the simultaneous preservation of high-gloss performance and other functions.

[0044] 4. UV Aging Resistance Analysis: After 1000 hours of UV aging, Examples 1-3 showed a tensile strength retention rate of ≥90.2% and an impact strength retention rate of ≥82.5%, reaching a maximum of 92.1% and 84.2%, respectively, far exceeding the preset requirements of ≥85% and ≥80%. This indicates that the UV-327 and HALS 770 compound UV-resistant system of the present invention achieves a synergistic effect of UV absorption and free radical capture, effectively inhibiting the photo-oxidative degradation of polypropylene molecular chains and significantly extending the outdoor service life of the material. In contrast, Comparative Sample 1 (blank sample) showed a mechanical property retention rate of only 58.6% and 55.3% after aging, and the material was prone to yellowing and brittleness. Comparative Sample 4 (single UV-resistant agent) showed a tensile strength retention rate of only 75.3% and an impact strength retention rate of 72.8% after aging, indicating that a single UV-resistant agent can only achieve a localized anti-aging effect, while the UV-resistant compound system of the present invention can comprehensively improve anti-aging performance, while avoiding the yellowing problem caused by UV-resistant additives, thus balancing aging resistance and high gloss.

[0045] 5. Mechanical Property Analysis: The tensile strength of Examples 1-3 remained between 32.2 MPa and 33.5 MPa, and the impact strength between 18.3 kJ / m² and 19.2 kJ / m², all close to the mechanical properties of the blank sample (tensile strength 34.0 MPa, impact strength 19.5 kJ / m²). This indicates that the compatibility system and preparation process of the present invention are optimized, effectively compensating for the influence of functional additives on the mechanical properties of the material. Comparative Sample 2 (single antibacterial agent) had a tensile strength of 31.5 MPa and an impact strength of 17.8 kJ / m², while Comparative Sample 3 (single flame retardant) had a tensile strength of 29.8 MPa and an impact strength of 16.5 kJ / m², showing a more significant decrease in mechanical properties. This is primarily due to the use of a compatibility agent—PP-g-MAH and POE in a 3:2 ratio—in the present invention. PP-g-MAH improves the compatibility between the functional additives and the matrix, while POE provides toughening. The synergistic effect of both ensures that the material achieves multiple functions while maintaining stable mechanical properties, meeting the structural strength requirements of practical applications.

[0046] For those skilled in the art, modifications can be made to the technical solutions described in the foregoing embodiments, and equivalent substitutions can be made to some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. An antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material, characterized in that: It is prepared from the following raw materials in parts by weight: 60-80 parts of high-gloss polypropylene, 1-5 parts of composite antibacterial agent, 5-15 parts of halogen-free flame retardant synergistic system, 0.5-3 parts of UV-resistant compound system, 2-8 parts of compatibilizer, and 0.1-1 parts of lubricant; the composite antibacterial agent is a compound of organic antibacterial agent, inorganic antibacterial agent and dispersant, the halogen-free flame retardant synergistic system is a compound of phosphate ester flame retardant, melamine cyanurate and modified nano synergist, and the UV-resistant compound system is a compound of UV absorber and hindered amine light stabilizer.

2. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 1, characterized in that: The composite antibacterial agent is composed of the following components in the following weight ratio: organic antibacterial agent: inorganic antibacterial agent: dispersant = 3:1:1; the organic antibacterial agent is dodecyl dimethyl benzyl ammonium chloride, the inorganic antibacterial agent is nano-silver particles, and the dispersant is chitosan.

3. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 1, characterized in that: The halogen-free flame retardant synergistic system is composed of the following components in the following weight ratio: phosphate ester flame retardant: melamine cyanurate: modified nano synergist = 4:3:3; the phosphate ester flame retardant is triphenyl phosphate, and the modified nano synergist is silane coupling agent KH-550 modified nano magnesium hydroxide.

4. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 3, characterized in that: The preparation method of the silane coupling agent KH-550 modified nano magnesium hydroxide is as follows: add nano magnesium hydroxide to deionized water and ultrasonically disperse for 30-40 min to obtain a dispersion; add 2-3% by mass of silane coupling agent KH-550 to the dispersion, stir and react at 60-70℃ for 2-3 h, filter, wash and dry to obtain silane coupling agent KH-550 modified nano magnesium hydroxide.

5. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 1, characterized in that: The UV-resistant compound system is composed of the following components in the following weight ratio: UV absorber: hindered amine light stabilizer = 2:2; the UV absorber is benzotriazole UV-327, and the hindered amine light stabilizer is HALS 770.

6. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 1, characterized in that: The compatibilizer is a compound of maleic anhydride-grafted polypropylene and polyolefin elastomer in a weight ratio of 3:2; the high-gloss polypropylene is homopolymer polypropylene.

7. The antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 1, characterized in that: The lubricant is calcium stearate.

8. The preparation method of the antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material of the present invention is characterized in that, Includes the following steps: Step (1), raw material pretreatment: place the high-gloss polypropylene in a constant temperature drying oven at 80-85℃ and dry for 2-3 hours to remove moisture; The compound antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer, and lubricant were placed in a constant temperature drying oven at 70-75℃ for 1-2 hours and then dried for later use. Step (2), Mixing: According to the preset weight parts, add the pretreated high-gloss polypropylene, composite antibacterial agent, halogen-free flame retardant synergistic system, UV-resistant compound system, compatibilizer and lubricant into the high-speed mixer in sequence, set the mixing temperature to 80-100℃, the stirring speed to 800-1000r / min, mix for 10-15min to obtain a uniform premix. Step (3), Extrusion Granulation: The premix obtained in step (2) is fed into a twin-screw extruder for melt mixing and extrusion granulation. The temperature of each section of the twin-screw extruder is controlled as follows: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 190-200℃, and Die Head 200-210℃. The screw speed is 300-350r / min, and the traction speed is 2-3m / min. After granulation, particles with a particle size of 2-3mm are obtained. After cooling and sieving, they are ready for use. Step (4) Molding: The granules obtained in step (3) are fed into the injection molding machine and injection molded to obtain the finished product. The injection temperature is controlled at 190-210℃, the injection pressure is 80-100MPa, the holding pressure is 60-70MPa, the holding time is 10-15s, and the cooling time is 20-30s.

9. The method for preparing an antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 8, characterized in that: In step (3), the length-to-diameter ratio of the twin-screw extruder is 40:1, and the feeding speed of the extruder is 20-25 kg / h; the cooling adopts a combination of air cooling and water cooling, with an air cooling temperature of 25-30℃ and a water cooling temperature of 15-20℃.

10. The method for preparing an antibacterial, high-gloss, flame-retardant, and UV-resistant polypropylene composite material according to claim 8, characterized in that: In step (4), the clamping force of the injection molding machine is 200-250t, and the injection speed is 50-60mm / s. The finished product after molding needs to be placed in a constant temperature aging chamber at 60-70℃ for 2-3 hours to eliminate internal stress.

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