Preparation method of antibacterial and antistatic PVC (polyvinyl chloride) pipeline containing bamboo charcoal black

Abstract

The invention discloses a preparation method of an antibacterial and antistatic PVC (polyvinyl chloride) pipeline containing bamboo carbon black. The preparation method comprises the following steps: carrying out acid pickling and silane coupling agent surface modification treatment on the bamboo carbon black; premixing the modified bamboo charcoal black, the PVC resin and the auxiliary agent; carrying out melt blending and extrusion molding on the premix through a double-screw extruder; and carrying out gradient cooling on the extruded pipeline. Natural bamboo carbon black is used as a core additive, the antibacterial performance of the PVC pipeline is improved by means of a microporous adsorption network formed by uniform dispersion of the bamboo carbon black, the environmental risk of a chemical additive is avoided, and potential safety hazards caused by static accumulation are eliminated by means of a continuous conductive network constructed by the bamboo carbon black in a matrix; and the bamboo charcoal black is used as an efficient ultraviolet screening agent, so that a PVC molecular chain can be effectively protected, and the service life of the pipeline is prolonged. Meanwhile, natural and renewable bamboo charcoal is used as a raw material source, so that introduction of toxic metals or chemical synthetic antibacterial agents is avoided fundamentally, and no toxic substances are released.

Description

Technical Field

[0001] This invention relates to the field of plastic pipe technology, and more specifically, to a method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black. Background Technology

[0002] Polyvinyl chloride (PVC) pipes are widely used in water supply and drainage, construction, agriculture, and other fields due to their advantages such as corrosion resistance and low cost. However, traditional PVC pipes have the following significant drawbacks:

[0003] 1. Insufficient antibacterial properties: The surface of pipes, especially in aquatic or humid environments, is prone to the growth of bacteria, mold and other microorganisms, causing microbial contamination;

[0004] 2. Static electricity buildup: PVC itself is an excellent insulator, but it is prone to accumulating static electricity due to friction and other reasons during long-term use, which poses a safety hazard.

[0005] To improve the above performance, existing technologies mostly use metal additives or chemical antibacterial agents, but these methods have significant drawbacks: metal (such as silver ion) additives are expensive and easily oxidized and degraded; some chemical antibacterial agents may release harmful substances, which do not meet environmental protection requirements; conventional antistatic agents have poor compatibility with PVC matrix, are easy to migrate and precipitate, and have unstable performance.

[0006] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black. This method uses natural bamboo charcoal black as a core additive, aiming to simultaneously endow PVC pipes with excellent antibacterial properties and stable antistatic capabilities.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black includes the following steps:

[0010] Step S1: The bamboo charcoal black is subjected to acid washing and surface modification treatment with silane coupling agent;

[0011] Step S2: Premix the modified bamboo charcoal black, PVC resin and auxiliary additives; based on 100% of the mass of the mixture, the mixture includes 70%-85% PVC resin, 8%-12% modified bamboo charcoal black, and the remainder is auxiliary additives.

[0012] Step S3: The premixed material is melt-blended and extruded using a twin-screw extruder;

[0013] Step S4: The extruded pipe is subjected to gradient cooling and then cut to a fixed length.

[0014] Furthermore, in step S1, the modification treatment of bamboo charcoal black includes the following steps:

[0015] Step S11: Treat bamboo charcoal black with 5% hydrochloric acid at 60°C for 1 hour.

[0016] Step S12: Wash the acid-washed bamboo charcoal black with water until it is neutral.

[0017] Step S13: Mix the washed bamboo charcoal black with γ-aminopropyltriethoxysilane, the amount of γ-aminopropyltriethoxysilane added is 2.5% of the mass of bamboo charcoal black, and react at 75°C for 2 hours.

[0018] Step S14: The bamboo charcoal black treated with γ-aminopropyltriethoxysilane is dried at 120°C to complete the surface modification.

[0019] Furthermore, in step S2, the modified bamboo charcoal black, PVC resin and auxiliary additives are first hot-mixed at a temperature controlled at 100℃-120℃ during premixing, and then cold-mixed at a temperature controlled at 55℃-60℃.

[0020] Furthermore, the auxiliary agents include processing aids, stabilizers, and lubricants.

[0021] Furthermore, in step S2, the modified bamboo charcoal black is first premixed with a portion of PVC resin and a portion of auxiliary additives in a high-speed mixer, and then granulated by a twin-screw extruder to produce bamboo charcoal black masterbatch; then the bamboo charcoal black masterbatch is mixed with the remaining PVC resin and the remaining auxiliary additives in a high-speed mixer.

[0022] Furthermore, in step S4, the extruded pipe is slowly cooled sequentially through three temperature zones: 100°C, 60°C, and 25°C.

[0023] Furthermore, the bamboo charcoal black is uniformly dispersed within the pipe to form a continuous conductive network, and the surface resistivity of the pipe is ≤10. 6 On the order of Ω•cm.

[0024] Furthermore, during the pipe extrusion process, the overall distribution of bamboo charcoal black within the pipe is evaluated by combining the formation efficiency of the conductive network with the uniformity of bamboo charcoal black distribution.

[0025]

[0026] In the formula, To assess the overall uniformity of bamboo charcoal black distribution; It is a relative efficiency index used to reflect the efficiency of forming a conductive network; The coefficient of variation of electrical conductivity is used to reflect the uniformity of bamboo charcoal black distribution. This is the maximum permissible coefficient of variation.

[0027] Furthermore, the relative efficiency index Calculate using the following formula:

[0028]

[0029] In the formula, The average measured conductivity of the current cross-section of the pipe; This represents the theoretical electrical conductivity at the current bamboo charcoal black addition level.

[0030] Furthermore, the spatial variation coefficient of conductivity Calculate using the following formula:

[0031]

[0032] In the formula, The standard deviation of conductivity at different measurement locations at the current cross-section of the pipe; This represents the average measured conductivity of the current cross-section of the pipe.

[0033] The beneficial effects of this invention are:

[0034] This invention utilizes natural bamboo charcoal black as a core additive, leveraging the microporous adsorption network formed by the uniform dispersion of bamboo charcoal black to enhance the antibacterial properties of PVC pipes. This avoids the environmental risks associated with chemical additives. The continuous conductive network constructed by bamboo charcoal black within the matrix eliminates safety hazards caused by static electricity buildup. Furthermore, bamboo charcoal black, as a highly efficient ultraviolet shielding agent, effectively protects the PVC molecular chains, extending the pipe's service life. Simultaneously, using natural and renewable bamboo charcoal as a raw material source fundamentally avoids the introduction of toxic metals or chemically synthesized antibacterial agents, resulting in no release of toxic substances. Detailed Implementation

[0035] 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.

[0036] Example: A method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black, comprising the following steps:

[0037] Step S1: The bamboo charcoal black is subjected to acid washing and surface modification treatment with silane coupling agent.

[0038] Among them, bamboo charcoal black is a micron-sized powder obtained by carbonizing bamboo in an oxygen-deficient environment, grinding and classifying it, with a particle size ≤4μm.

[0039] The modification process of bamboo charcoal black includes the following steps:

[0040] Step S11: Use 5% hydrochloric acid to treat bamboo charcoal black at 60°C for 1 hour; this method removes ash from bamboo charcoal black and avoids excessive ash content (>5%) which would reduce the toughness of the final pipe.

[0041] Step S12: Wash the acid-washed bamboo charcoal black with water until it is neutral.

[0042] Step S13: The washed bamboo charcoal black is mixed with γ-aminopropyltriethoxysilane (KH550), the amount of γ-aminopropyltriethoxysilane added is 2.5% of the mass of bamboo charcoal black, and the mixture is reacted at 75°C for 2 hours; the primary amine group in the γ-aminopropyltriethoxysilane molecule reacts with HCl generated during the decomposition of PVC during processing to produce a synergistic stabilizing effect;

[0043] Step S14: The bamboo charcoal black treated with γ-aminopropyltriethoxysilane is dried at 120°C to complete the surface modification.

[0044] In step S1, bamboo charcoal black is pretreated using a three-step process of "acid washing - coupling agent coating - heat treatment" to obtain surface activation properties, enhance the interfacial bonding with PVC, and lay the foundation for uniform dispersion and functional performance in the PVC matrix.

[0045] Step S2: Premix the modified bamboo charcoal black, PVC resin and auxiliary additives; based on 100% of the mass of the mixture, the mixture includes 70%-85% PVC resin, 8%-12% modified bamboo charcoal black, and the remainder is auxiliary additives; the auxiliary additives include processing aids, stabilizers and lubricants.

[0046] As a preferred option, ACR processing aid is used as the processing aid, calcium-zinc composite stabilizer is used as the stabilizer, and stearic acid is used as the lubricant.

[0047] It should be noted that when the proportion of modified bamboo charcoal black is less than 8%, the antibacterial effect of the extruded pipe is poor; when the proportion of modified bamboo charcoal black is greater than 12%, the melt strength decreases.

[0048] Furthermore, the modified bamboo charcoal black is dispersed in PVC resin in two steps, specifically:

[0049] The first step is to take a portion (e.g., 20%-30% of the total PVC resin) from the 70%-85% PVC resin as a carrier resin. This portion of PVC resin, along with the total amount of modified bamboo charcoal black and a portion of auxiliary additives, is added to a high-speed mixer (hot mixer). The mixture is then subjected to high-speed shear mixing at a temperature of 100℃-120℃ to soften the PVC resin particles and allow the modified bamboo charcoal black to initially coat and embed under high shear force. After uniform mixing, the material is transferred to a cold mixer and rapidly cooled to 55℃-60℃ to prevent clumping, resulting in high-concentration bamboo charcoal black masterbatch.

[0050] The second step involves putting the obtained high-concentration bamboo charcoal black masterbatch, the remaining PVC resin (accounting for 70%-80% of the total PVC), and the remaining auxiliary additives into a high-speed mixer for hot and cold mixing again. Under the same hot and cold mixing process, the high-concentration masterbatch is fully dispersed, and the modified bamboo charcoal black dispersion is further distributed and diluted in the entire PVC resin system.

[0051] Because bamboo charcoal black has a large specific surface area and is prone to agglomeration, mixing it with a large amount of PVC resin in a single step dilutes the shear force, making it difficult to break up the firmly aggregated clusters. By first dispersing it in a small amount of PVC resin, the higher shear stress at a high filler concentration forces the agglomerates apart, achieving good pre-dispersion. The pre-dispersed masterbatch becomes PVC micro-units rich in bamboo charcoal black. When mixed with a large amount of PVC resin, the process of homogenizing the spatial distribution of these micro-units is far less difficult than directly dispersing primary agglomerates, ensuring the consistency of bamboo charcoal black distribution on a macroscopic scale. Simultaneously, in the subsequent twin-screw extruder melt blending and extrusion molding process, the pre-dispersed masterbatch significantly reduces the dispersion pressure on the screw in the melt section. Combined with the use of a two-stage anti-agglomeration screw element, the anti-agglomeration design efficiency of the screw is improved by 30%.

[0052] Step S3: The premixed material is melt-blended through a twin-screw extruder and extruded into a pipe; wherein, the screw adopts a two-stage reverse thread element to prevent bamboo charcoal black from agglomerating in the high shear zone.

[0053] Step S4 involves gradient cooling of the extruded pipe, followed by fixed-length cutting. The extruded pipe is slowly cooled sequentially through three temperature zones: 100℃, 60℃, and 25℃, to prevent stress concentration caused by direct water cooling.

[0054] The method proposed in this invention utilizes natural bamboo charcoal black as a core additive, aiming to simultaneously impart excellent antibacterial properties and stable antistatic capabilities to PVC pipes. Specifically:

[0055] 1. Antibacterial properties:

[0056] Bamboo charcoal black possesses a rich microporous structure and high specific surface area, enabling it to effectively adsorb microorganisms in the water environment inside pipes, disrupting their normal growth and reproduction environment, thereby achieving physical antibacterial effects. Simultaneously, the uniform dispersion of bamboo charcoal black ensures continuous and widespread adsorption sites, efficiently trapping flowing microorganisms and guaranteeing a high antibacterial rate. Furthermore, as an inorganic / carbon material, bamboo charcoal black is chemically stable and does not deplete with use. Its antibacterial effect relies primarily on physical adsorption rather than chemical release, thus its performance will not diminish due to the migration or deactivation of active ingredients. Additionally, surface modification with silane coupling agents enhances the interfacial bonding with PVC, preventing bamboo charcoal black from detaching from the matrix and ensuring functional durability.

[0057] 2. Antistatic properties:

[0058] When the amount of bamboo charcoal black added reaches or exceeds a certain threshold, and uniform dispersion is achieved through optimized processes (such as secondary addition of bamboo charcoal black or specific screw shearing), the originally mutually insulating bamboo charcoal black particles can overlap, forming a continuous conductive network within the insulating PVC matrix. This conductive network provides a discharge channel for static charges, allowing accumulated charges to be rapidly conducted and dissipated, thereby reducing the surface resistivity from the insulation level of ordinary PVC (typically >10 Ω·cm). 12 The value (on the order of Ω•cm) is reduced to the range of antistatic materials (e.g., ≤10). 6 (on the order of Ω•cm), effectively eliminating the safety hazards caused by static electricity accumulation.

[0059] 3. Improved weather resistance:

[0060] Bamboo charcoal black has excellent shielding and absorption properties against ultraviolet rays. Its carbonaceous structure can effectively absorb and scatter ultraviolet rays, reducing the direct radiation of ultraviolet rays to the PVC polymer chain. At the same time, bamboo charcoal black is uniformly dispersed in the pipe wall, which is equivalent to constructing an ultraviolet protection net throughout the material, greatly delaying the photoaging process of the PVC matrix.

[0061] 4. Environmental advantages:

[0062] Using natural and renewable bamboo charcoal as a raw material source avoids the introduction of toxic metals or chemically synthesized antibacterial agents at the source. Bamboo charcoal black is non-toxic, and the auxiliary agents selected, such as "calcium-zinc composite stabilizer," are environmentally friendly heat stabilizers, and the lubricant "stearic acid" is also a common non-toxic additive. The entire formula system does not depend on or contain any intentionally added toxic substances.

[0063] As a preferred alternative, bamboo charcoal black can be replaced by other biochar (such as coconut shell charcoal), but bamboo charcoal black has higher porosity and better adsorption performance.

[0064] Furthermore, during the pipe extrusion process, to obtain the distribution of bamboo charcoal black within the pipe, this invention designs a method for detecting the comprehensive distribution of bamboo charcoal black in the PVC matrix based on the amount of bamboo charcoal black added and the electrical conductivity network formed by the interlocking of bamboo charcoal black particles. Specifically:

[0065] Step 1, Establish a benchmark model: Establish the optimal addition amount of bamboo charcoal black under a completely uniform distribution state through experiments. With the ideal conductivity of the pipeline The baseline function model between;

[0066]

[0067] In the formula, The permeation threshold is the value when the bamboo charcoal black content... Below the seepage threshold At this stage, bamboo charcoal black particles are isolated from each other and cannot form a continuous network in the PVC matrix, resulting in pipes that exhibit insulation or extremely low conductivity; when the content... Above the seepage threshold When bamboo charcoal black particles come into contact with each other and form a conductive path that runs through the entire material, the conductivity will increase sharply with the increase of the amount added. and , where a is a constant, is a parameter of the material system obtained by fitting experimental data. Constant a reflects the efficiency or intensity of the improvement in conductivity per unit bamboo charcoal black content after the formation of an effective conductive network. Constant b is the percolation index, which is generally set to 1.5-2.0.

[0068] Step 2, Online Data Acquisition and Processing: An annular conductivity monitoring device is installed at the die exit of the extruder. This device contains multiple pairs of electrodes evenly distributed around the circumference of the extrusion pipe. All electrodes maintain stable and consistent slight contact with the outer surface of the extrusion pipe. Simultaneously, the real-time addition amount of bamboo charcoal black is obtained from the feeding system. Meanwhile, a temperature probe can be integrated next to the electrode to monitor the pipe temperature in the measurement area in real time, which is used to perform temperature compensation correction on the conductivity data.

[0069] Step 3, comprehensively evaluate the distribution status:

[0070] Based on the real-time conductivity values ​​of each point in the pipeline measured by each electrode Calculate the average conductivity of the current cross section. and the standard deviation of conductivity at different measurement locations of the current cross-section; simultaneously based on the real-time bamboo charcoal black addition amount The corresponding ideal conductivity is calculated using the established benchmark model. ;

[0071] Relative efficiency index Calculate using the following formula:

[0072]

[0073] Coefficient of variation of conductivity Calculate using the following formula:

[0074]

[0075] Bamboo charcoal black overall distribution uniformity Calculate using the following formula:

[0076]

[0077] In the formula, The maximum permissible coefficient of variation is defined as the upper limit of the spatial non-uniformity of electrical conductivity that can be accepted in the dispersion state of bamboo charcoal black, i.e., when the spatial coefficient of variation of electrical conductivity... When a certain critical value is exceeded, it means that the uneven distribution of bamboo charcoal black has reached a certain level, which will directly lead to the failure of the product's core functions or substandard performance, such as localized exceeding of antistatic standards or significant shortcomings in antibacterial properties. (Bamboo charcoal black overall distribution uniformity) The range is 0-1, and the larger the value, the closer the distribution is to the ideal uniform state.

[0078] Relative efficiency index The ratio of "actually measured conductivity" to "theoretically optimal conductivity achievable at the current addition level" is used to evaluate the efficiency of bamboo charcoal black particles in constructing a continuous conductive network in a PVC matrix; if the relative efficiency index... The relative efficiency index is low, indicating that even with sufficient bamboo charcoal black addition, its conductivity potential is not fully realized. This is likely due to the agglomeration of the bamboo charcoal black particles. The closer the value is to 1, the more fully the electrical conductivity potential of the surface bamboo charcoal black is realized. Relative efficiency index Value range: 0≤ ≤1.

[0079] Coefficient of variation of conductivity Directly measuring the fluctuation of conductivity at different locations on a pipe's cross-section focuses on the spatial dispersion of conductivity values; when the spatial coefficient of conductivity... The smaller the value, the more consistent the conductivity of the pipe from the center to the edge, indicating a more uniform spatial distribution of bamboo charcoal black; when the spatial variation coefficient of conductivity is... The larger the value, the higher the concentration of bamboo charcoal black in some areas and the lower the concentration in others. (Conductivity spatial variation coefficient) Value range: 0≤ .

[0080] Through the relative efficiency index and the spatial variation coefficient of conductivity By combining these methods, a comprehensive and detailed diagnosis of the distribution of bamboo charcoal black can be achieved, encompassing both "overall effectiveness" and "spatial structure".

[0081] Step 4, Establish Diagnosis and Regulation:

[0082] If the relative efficiency index High and the spatial variation coefficient of conductivity The lowest value is the optimal state, which is highly efficient and evenly distributed.

[0083] If the relative efficiency index Low and conductivity spatial variation coefficient High values ​​represent the worst-case scenario, characterized by low efficiency, uneven distribution, and severe clustering.

[0084] If the relative efficiency index Low and conductivity spatial variation coefficient If the dispersion is low, the overall dispersion is insufficient, but there is no local segregation.

[0085] If the relative efficiency index High and the spatial variation coefficient of conductivity If the value is high, a conductive network has been formed, but there are local inhomogeneities.

[0086] Based on the diagnostic results, adjust the process parameters of the twin-screw extruder, including screw speed, melt temperature, and feed rate, or adjust the premixing time of the raw materials. For example, when the diagnostic results indicate severe agglomeration and uneven dispersion of bamboo charcoal black, adjustments can be made by changing the screw speed; when the relative efficiency index... Normal, but the spatial variation coefficient of conductivity If the temperature is too high, the uniformity of melt flow can be improved by fine-tuning the temperature settings of each temperature zone in the barrel.

[0087] Preferably, when establishing the benchmark model, a series of PVC standard samples with different amounts of bamboo charcoal black added, ensuring complete uniform distribution, are prepared. The electrical conductivity of each sample is measured to obtain multiple sets ( For each data pair, a nonlinear least squares method is used to fit the data pairs and determine the parameters. , and The value of .

[0088] The antibacterial properties, antistatic properties, and weather resistance were verified separately below:

[0089] 1. Antibacterial properties:

[0090] Test sample: PVC sheet containing 10% modified bamboo charcoal black was prepared according to the present invention;

[0091] Control sample: PVC sample sheet without bamboo charcoal black;

[0092] Test method: According to GB / T 31402-2015, film coating method, culture for 24 hours.

[0093] Test results:

[0094] Test strains Average colony count (CFU / mL) in the control group Average colony count (CFU / mL) in the experimental group Antibacterial rate (R) E. coli <![CDATA[1.25×10 5 ]]> <![CDATA[9.8×10 2 ]]> 99.22% Staphylococcus aureus <![CDATA[1.18×10 5 ]]> <![CDATA[8.50×10 5 ]]> 99.28%

[0095] The data shows that the pipe of this invention has an antibacterial rate of over 99% against two common pathogens, which directly demonstrates the powerful physical antibacterial efficacy of the bamboo charcoal black adsorption network.

[0096] 2. Antistatic properties:

[0097] Test samples: PVC pipes containing bamboo charcoal black prepared according to the present invention (3 different batches);

[0098] Control sample: Commercially available ordinary PVC water supply pipes;

[0099] Test method: Surface resistivity was measured in accordance with GB / T 1410-2006.

[0100] Test results:

[0101] Sample number Surface resistivity (Ω·cm) control group PVC pipe <![CDATA[3.2×10 14 ]]> Test sample - batch 1 <![CDATA[5.4×10 6 ]]> Test sample - batch 2 <![CDATA[7.2×10 6 ]]> Test sample - batch 3 <![CDATA[5.8×10 6 ]]>

[0102] Data shows that the resistivity of ordinary PVC pipe is 10. 14 The resistivity is on the order of Ω·cm, belonging to the typical insulator category; the resistivity of the pipe material of this invention is stable at 10 Ω·cm. 6 It has an Ω·cm range and exhibits excellent and stable antistatic properties.

[0103] 3. Weather resistance:

[0104] Test sample: PVC strips containing bamboo charcoal black were prepared according to the present invention;

[0105] Control sample: PVC strips without bamboo charcoal black;

[0106] Test method: According to ISO4892-3, the tensile strength was tested before and after aging by irradiating with a UVA-340 lamp for 1000 hours.

[0107] Test results:

[0108] Performance indicators control sample test sample Initial tensile strength (MPa) 45.0±1.2 45.0±1.0 Tensile strength (MPa) after aging for 1000 hours 31.5±2.5 40.7±1.3 Tensile strength retention 70% 90.4%

[0109] Data shows that after 1000 hours of accelerated UV aging, the tensile strength retention rate of ordinary PVC samples is only 70%, while the tensile strength retention rate of the samples of this invention is as high as 90.4%.

[0110] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black, characterized in that, Includes the following steps: Step S1: The bamboo charcoal black is subjected to acid washing and surface modification treatment with silane coupling agent; Step S2: Premix the modified bamboo charcoal black, PVC resin and auxiliary additives; based on 100% of the mass of the mixture, the mixture includes 70%-85% PVC resin, 8%-12% modified bamboo charcoal black, and the remainder is auxiliary additives. Step S3: The premixed material is melt-blended and extruded using a twin-screw extruder; Step S4: The extruded pipe is subjected to gradient cooling and then cut to a fixed length.

2. The method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black according to claim 1, characterized in that, In step S1, the modification treatment of bamboo charcoal black includes the following steps: Step S11: Treat bamboo charcoal black with 5% hydrochloric acid at 60°C for 1 hour. Step S12: Wash the acid-washed bamboo charcoal black with water until it is neutral; Step S13: Mix the washed bamboo charcoal black with γ-aminopropyltriethoxysilane, the amount of γ-aminopropyltriethoxysilane added is 2.5% of the mass of bamboo charcoal black, and react at 75°C for 2 hours. Step S14: The bamboo charcoal black treated with γ-aminopropyltriethoxysilane is dried at 120°C to complete the surface modification.

3. The method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black according to claim 1, characterized in that, In step S2, the modified bamboo charcoal black, PVC resin and auxiliary agents are first hot-mixed at a temperature of 100℃-120℃, and then cold-mixed at a temperature of 55℃-60℃.

4. The method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black according to claim 1, characterized in that, The auxiliary agents include processing aids, stabilizers, and lubricants.

5. The method for preparing an antibacterial and antistatic PVC pipe containing bamboo charcoal black according to claim 1, characterized in that, In step S2, the modified bamboo charcoal black is first premixed with a portion of PVC resin and a portion of auxiliary additives in a high-speed mixer, and then granulated by a twin-screw extruder to produce bamboo charcoal black masterbatch; then the bamboo charcoal black masterbatch is mixed with the remaining PVC resin and the remaining auxiliary additives in a high-speed mixer.

6. The method for preparing an antibacterial and antistatic PVC pipe containing bamboo charcoal black according to claim 1, characterized in that, In step S4, the extruded pipe is slowly cooled sequentially through three temperature zones: 100°C, 60°C, and 25°C.

7. The method for preparing an antibacterial and antistatic PVC pipe containing bamboo charcoal black according to claim 1, characterized in that, Bamboo charcoal black is uniformly dispersed within the pipe to form a continuous conductive network, and the surface resistivity of the pipe is ≤10. 6 On the order of Ω•cm.

8. The method for preparing antibacterial and antistatic PVC pipes containing bamboo charcoal black according to claim 1, characterized in that, During the pipe extrusion process, the overall distribution of bamboo charcoal black within the pipe is evaluated by combining the formation efficiency of the conductive network with the uniformity of bamboo charcoal black distribution. In the formula, To determine the overall uniformity of bamboo charcoal black distribution; It is a relative efficiency index used to reflect the efficiency of forming a conductive network; The coefficient of variation of electrical conductivity is used to reflect the uniformity of bamboo charcoal black distribution. This is the maximum permissible coefficient of variation.

9. The method for preparing an antibacterial and antistatic PVC pipe containing bamboo charcoal black according to claim 8, characterized in that, Relative efficiency index Calculate using the following formula: In the formula, The average measured conductivity of the current cross-section of the pipe; This represents the theoretical electrical conductivity at the current bamboo charcoal black addition level.

10. The method for preparing an antibacterial and antistatic PVC pipe containing bamboo charcoal black according to claim 8, characterized in that, Coefficient of variation of conductivity Calculate using the following formula: In the formula, This represents the standard deviation of conductivity at different measurement locations across the current cross-section of the pipe. This represents the average measured conductivity of the current cross-section of the pipe.

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