Method for manufacturing an antistatic plastic hose

Abstract

This invention discloses a method for manufacturing an antistatic plastic hose, relating to the field of hose production technology. The method includes: S1, ingredient mixing: mixing a matrix thermoplastic polymer, conductive / dissipative filler, plasticizer, heat stabilizer, processing aid, and antioxidant; S2, compounding: co-extruding the conductive / dissipative masterbatch and matrix resin in a predetermined ratio on a twin-screw extruder; S3, extrusion molding: extruding the compounded melt through a die to form a hose blank; S4, annealing / conditioning treatment: heat-conditioning / annealing treatment yields the antistatic plastic hose. This invention combines high-efficiency nano-carbon materials and economical micron-sized carbon black in a complementary manner, and employs masterbatch pre-dispersion, high-shear short-time dispersion, and conductive distribution design along the thickness direction in the formulation and processing. This allows conductive pathways to form and remain stable for a long time under a low overall filler load. It maintains the flexibility and feel of the hose while also providing high transparency when needed.

Description

Technical Field

[0001] This invention relates to the field of hose manufacturing technology, and specifically to a method for manufacturing an antistatic plastic hose. Background Technology

[0002] Antistatic plastic hoses, commonly used functional components in industrial, medical, and food delivery systems, have seen significant advancements in both materials and processes in recent years. At the materials level, traditionally, conductive carbon black and conductive polymers have been the primary materials, but nanomaterials (such as carbon nanotubes and graphene) are gradually being introduced to achieve conductivity or dissipation functions with lower filler content. Simultaneously, ionic and nonionic antistatic agents are widely used to improve surface dissipation performance. At the process level, technologies such as masterbatch pre-dispersion, twin-screw high-shear compounding, co-extrusion / coaxial double-layer extrusion, and in-mold / post-processing grounding embedding are widely adopted to improve filler dispersion, achieve functional zoning, and ensure stability in industrial production. Furthermore, surface modification (plasma activation, conductive coating spraying) is used to enhance long-term dissipation stability and weather resistance. These technologies have driven the gradual application and standardization of antistatic hoses in various scenarios, including infusion, food delivery, bulk powder delivery, and hazardous materials handling.

[0003] Traditional solutions, in pursuit of antistatic / dissipative properties, typically rely on a high content of micron-sized conductive fillers (such as carbon black) to form conductive permeation channels. However, a high filler load significantly reduces the transparency and flexibility of the hose, increases rigidity, and affects feel and processability. It is difficult to simultaneously meet the mutually exclusive requirements of "high transparency / high flexibility" and "stable antistatic properties," thus limiting the promotion of antistatic hoses in medical, food, and other applications where visual and tactile requirements are high.

[0004] In response to this problem, this application proposes a method for manufacturing an antistatic plastic hose. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing antistatic plastic hoses, in order to solve the problem that in the prior art, high filler loads significantly reduce the transparency and flexibility of hoses, increase rigidity, and affect feel and processability, making it difficult to simultaneously meet the two mutually exclusive requirements of "high transparency / high flexibility" and "stable antistatic properties," thus limiting the promotion of antistatic hoses in medical, food, and other applications with high requirements for visual and tactile properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for manufacturing an antistatic plastic hose, comprising:

[0008] S1. Ingredients: Mix the base thermoplastic polymer, conductive / dissipative filler, plasticizer (or softener), heat stabilizer, processing aid and antioxidant;

[0009] The matrix thermoplastic polymer is one of thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), or thermoplastic rubber (TPR);

[0010] The conductive / dissipative filler is at least one of carbon black, graphene nanosheets, and carbon nanotubes (CNTs), and the mass fraction of the conductive / dissipative filler in the final mixture is 0.05–20 wt%.

[0011] The ingredients are premixed at the feeding port and fed into a parallel or series twin-screw extruder to produce conductive / dissipative masterbatch.

[0012] S2. Compounding: The conductive / dissipative masterbatch and the matrix resin are co-extruded and compounded in a predetermined ratio on a twin-screw extruder. The extrusion process parameters are: extruder barrel temperature zone between 140–240℃ (170–220℃ for TPU; 140–190℃ for PVC), screw speed between 80–350 rpm, vacuum degassing and shear control to ensure good dispersion of nanofillers.

[0013] S3. Extrusion molding: The compounded melt is extruded through a die to form a hose blank (which can be a single layer or a coaxial double layer structure). The die temperature is controlled at 150–230℃. The die orifice is designed as a spiral reinforcement or a straight cylindrical type. The hose wall thickness is 0.5–6.0 mm as required. After extrusion, the hose is shaped, pulled, cut or wound in a cooling water tank.

[0014] S4. Annealing / Temperature Treatment: The extruded hose is subjected to heat conditioning / annealing treatment at 60–120℃ for 10–60 minutes to release internal stress and stabilize the conductive network, resulting in an antistatic plastic hose.

[0015] S5. Quality and antistatic performance inspection: The surface resistivity or volume resistivity of the antistatic plastic hose shall be measured, with the target being a surface resistivity of 10^5–10^10 Ω / sq (static dissipation / antistatic range) or a volume resistivity of 10^3–10^6 Ω·m as designed.

[0016] Furthermore, the method also includes: in step S2 or step S3, by controlling the total content, dispersion mode and morphology of the nanofiller (such as enriching a small amount of highly conductive nanofiller in the inner layer while keeping the outer layer with low filler content to balance flexibility and transparency) to form a conductive / dissipative distribution along the thickness direction, so as to achieve stable antistatic performance while ensuring the flexibility of the hose.

[0017] Furthermore, the conductive / dissipative filler adopts a mixed filler strategy, wherein carbon black accounts for 10–95 wt% of the total filler and graphene nanosheets or multi-walled carbon nanotubes account for 0.05–10 wt% of the total filler. By combining the volume economy of carbon black with the low-threshold network formation characteristics of nano-carbon materials, conductive channels are formed with a low total filler content.

[0018] Further, in step S1, pre-dispersed graphene nanosheets / single-walled carbon nanotube masterbatches are used, wherein the mass fraction of the nanomaterials in the final compound is 0.05–0.8 wt%, and short-term strong shear dispersion is performed using the high-speed section (screw speed 180–350 rpm) of a high-shear twin-screw extruder, so as to achieve a dissipation performance with a surface resistivity of about 10^6–10^9 Ω / sq while maintaining the transparency of the matrix.

[0019] Further, in step S1, the surface dissipation enhancer is an ionic / polar antistatic agent, with an addition amount of 0.1–3.0 phr. It forms a low-resistance dissipation surface on the outer surface of the hose through diffusion or surface migration mechanism. This type of antistatic agent is added in stages with the conductive masterbatch (the masterbatch first disperses the conductive filler, and then the antistatic agent is added at the end of the extrusion to precisely control the surface dosage) in order to avoid long-term migration leading to material performance degradation.

[0020] The ionic / polar antistatic agent is at least one of quaternary ammonium salts and polyether antistatic agents.

[0021] Furthermore, the composite hose can adopt a coaxial double-layer extrusion structure, with the inner layer being a high conductivity / dissipation formula (filler content of 0.5–8 wt%) and the outer layer being a low filler and high flexibility formula (filler content ≤0.5 wt% or a formula containing only ionic antistatic agents). The thickness ratio of the inner and outer layers can be adjusted between 20:80 and 80:20 through the coaxial die head, thereby achieving the functional zoning of "conductive inner layer, comfortable outer layer, and transparent outer layer", which facilitates internal grounding or frictional dissipation without sacrificing appearance and feel.

[0022] Furthermore, for special scenarios involving flammable, explosive, or volatile dust, a full-layer conductive / grounded flexible hose structure is adopted, and metal grounding rings or brush contact points are set at intervals along the length of the hose (by embedding fine metal wires in the mold or subsequently wrapping grounding conductive strips along the axial direction and hot-melting and covering) to ensure that electrostatic energy can be discharged to the ground in a timely manner.

[0023] The conductive filler content in the full-layer conductive formulation is 2–15 wt%.

[0024] Furthermore, in step S2, the following set of processing parameters is used during the twin-screw extrusion process:

[0025] Feed temperature 20–60℃ (granules or masterbatch), extrusion barrel zone temperature (feed end → middle section → front section → die head) 140–170℃, 150–200℃, 160–220℃, 150–230℃ respectively (adjusted according to the type of matrix resin);

[0026] Screw speed: 80–350 rpm; Linear speed (traction speed): 0.5–6 m / min depending on hose diameter;

[0027] Vacuum degassing pressure ≤ 5 mbar to remove low molecular weight volatiles and prevent bubbles;

[0028] The die diameter and die clearance are designed according to the required wall thickness and flow rate, and fixed-length cutting is performed using a bladed or vibratory cutting system. This set of processing parameters is used to ensure the dispersion of nano / micro-level conductive fillers and the formation of a conductive network (or near-surface enrichment layer), thereby stably obtaining the predetermined antistatic properties.

[0029] Further, in step S3 or step S4, online or offline surface modification is performed on the hose;

[0030] The surface modification includes: spraying a thin dissipative coating (containing a conductive polymer or conductive polymer composite, with a coating thickness of 0.1–10 μm) or hot-pressing a self-conductive film after plasma surface activation, to further reduce surface resistance and improve wear resistance and weather resistance; this modification is suitable for application scenarios that require long-term stable dissipation, resistance to chemical corrosion or outdoor installation.

[0031] Compared with existing technologies, the present invention provides a method for manufacturing an antistatic plastic hose. By combining high-efficiency nano-carbon materials and economical micron-sized carbon black in a complementary manner, and by employing masterbatch pre-dispersion, high-shear short-time dispersion, and conductive distribution design along the thickness direction in the formulation and processing, conductive pathways can be formed and remain stable for a long time under a low overall filler load. This maintains the flexibility and feel of the hose while also ensuring high transparency when needed (suitable for medical / food applications), thereby overcoming the destructive effects of traditional high-carbon black content formulations on transparency and flexibility, and improving the applicability of the material and the added value of the product.

[0032] In this invention, the coaxial structure design of an inner high-conductivity layer and an outer low-filler layer, combined with a grounding / contact ring (or grounding strip) pre-reserved in the mold or wrapped in a subsequent process, provides a reliable grounding path for the internal conductive system while ensuring the comfort and weather resistance of the outer layer. This structured solution facilitates mass production on the production line, on-site grounding installation and maintenance, and significantly improves electrostatic safety in flammable, dusty, or explosive environments. It enables the hose to quickly and controllably discharge electrostatic energy to the ground under actual working conditions, thereby reducing the risk of ignition and improving system reliability. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0034] Figure 1 This is a flowchart illustrating a method for manufacturing an antistatic plastic hose, as provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] As attached Figure 1 As shown:

[0037] Example 1:

[0038] This embodiment is specifically applied to: highly transparent, medical / food grade dissipative flexible tubing;

[0039] Applications: Medical infusion / food-grade delivery applications requiring highly transparent, flexible, stable dissipation, and low-migration antistatic agents.

[0040] The material composition is shown in Table 1 below;

[0041] Table 1

[0042] Serial Number Material Name Specific substance / brand Supply Form Parts by weight (wt%) Function 1 Matrix resin Elastollan® 1185A Particles 97.2 Hose body structure 2 conductive filler xGnP®-M5 (TPU carrier, 5% graphene) Masterbatch 2.0 Constructing micro conductive networks 3 antioxidants Irganox® 1010 powder 0.3 Anti-thermal and oxygen aging 4 Antistatic agent PEG monostearate Liquid / Powder 0.3 Surface charge dissipation 5 Processing aids Zinc stearate powder 0.2 Improve extrusion flow

[0043] Formula (based on final material mass):

[0044] TPU (medical / food grade);

[0045] Graphene nanotube (GNT) masterbatch (nano content in masterbatch: 5 wt%);

[0046] Antioxidants / heat stabilizers / processing aids;

[0047] Ionic quaternary ammonium antistatic agents (added at the end point);

[0048] Masterbatch preparation:

[0049] TPU and graphene nanotubes were premixed in a high-shear mixer for 30–60 min until homogeneous.

[0050] Granulation is performed using a twin-screw extruder (barrel zone temperature: 170 / 185 / 200 / 200℃; screw speed 200–240 rpm; vacuum degassing ≤5 mbar) to obtain masterbatch (masterbatch model and content are labeled).

[0051] Compounding and extrusion:

[0052] Raw material drying: 80℃, 4 h.

[0053] Twin-screw compounding process parameters: extruder barrel temperature profile 170→185→200→200℃; screw speed 220rpm; vacuum degassing ≤5 mbar; traction line speed 1.0–1.5 m / min.

[0054] An ionic antistatic agent (0.15 phr) is introduced at the end of the extrusion process to ensure controllable surface dosage.

[0055] Die head type: single-layer cylindrical die head (preferably high transparency), die head temperature 185–195℃; wall thickness 1.0–1.5mm; cooling water tank 18–22℃ for shaping.

[0056] Annealing / Qualitative Analysis:

[0057] Continuous annealing chamber: 80°C, hold for 20–40 min (or hot box at 80°C for 30 min after winding) to release internal stress and stabilize the conductive network.

[0058] Surface modification:

[0059] To further improve durability and dissipation, a low-power plasma treatment can be performed after annealing, followed by spraying an extremely thin dissipation coating (thickness ≤ 0.5 μm; this step will affect transparency, so choose according to your needs) to obtain the corresponding sample A.

[0060] Example 2:

[0061] Coaxial double-layer conductive flexible hose for industrial / hazardous areas:

[0062] Applications: Suitable for grain / dust / powder / flammable and explosive environments, emphasizing rapid release, grounding, and wear resistance.

[0063] The material composition is shown in Table 2 below;

[0064] Table 2

[0065] Serial Number Material Name Specific substance / brand use Inner layer wt% outer layer wt% 1 PVC resin SG-5 matrix 60 65 2 plasticizers ATBC Soft modification 25 25 3 Conductive carbon black Ketjenblack® EC-600JD Main conductive filler 8 0 4 carbon nanotubes Nanocyl® NC7000 Conductive synergy 0.5 0 5 stabilizer Mark® CZ-200 Thermal stability 3 3 6 antioxidants Irganox® 1010 Anti-aging 0.3 0.3 7 Processing aids Calcium stearate lubricating 0.2 0.2 8 Grounding conductor 0.3mm tin-plated copper wire Grounding Embedded none

[0066] Formula (layered explanation):

[0067] Inner layer (highly conductive layer, with a wall thickness of approximately 35–45% of the total wall thickness);

[0068] Matrix (modified PVC or TPR);

[0069] Carbon black (conductive, highly conductive);

[0070] Graphene nanosheets (auxiliary effect);

[0071] Plasticizers / stabilizers / auxiliaries;

[0072] Outer layer (low filler, weather resistant / feel);

[0073] Matrix (PVC / TPR): almost free of conductive fillers, 0–0.2 wt% carbon black; 0.3–0.8 phr of ionic antistatic agent can be added to the outer layer end for surface dissipation (as needed).

[0074] Masterbatch and compound:

[0075] Inner layer masterbatch: carbon black and graphene are pre-dispersed and granulated (extrusion vacuum degassing ≤5 mbar).

[0076] Coaxial dual feeding: The inner and outer materials are fed into the coaxial die head through a twin-screw or parallel extrusion system respectively; Temperature profile (PVC): Inner layer 160→175→185→185℃; Outer layer 150→165→175→175℃; Screw speed 160–260rpm; Linear speed 2.0–3.0 m / min.

[0077] Extrusion molding and grounding arrangement:

[0078] The coaxial die head enables control of the thickness ratio of the inner and outer layers (inner:outer ≈ 40:60); the total wall thickness is 2.5–4.0 mm (depending on the application).

[0079] In the mold or subsequent processes, reserve / embed metal grounding rings or wrap 0.2mm copper-plated grounding tape every 0.8–1.5 m along the axial direction and heat-melt cover them (the grounding rings facilitate on-site grounding).

[0080] Annealing / Qualitative Analysis:

[0081] Annealing: 100℃ × 30–60 min (to ensure the stability of the inner conductive network).

[0082] Surface modification:

[0083] For outdoor or chemical exposure scenarios, an outer plasma-activated conductive polymer composite dissipative coating (0.5–2 µm thick) is sprayed on to improve long-term weather resistance and surface wear resistance, resulting in sample B.

[0084] Comparative example;

[0085] Sample C was prepared using a traditional PVC + carbon black monolayer.

[0086] The following describes the testing of the samples obtained in Example 1, Example 2, and the comparative example:

[0087] 1) Surface resistivity – Tested according to GB / T 1410-2006

[0088] Standard basis: GB / T 1410-2006.

[0089] Sample preparation: Take a tubular sample section of at least 200 mm in length, cut it along the axial direction and flatten it on a flat fixture (or cut a circular piece and flatten it to the plane required by the standard instrument fixture, with the thickness based on the actual tubular wall thickness); place it under constant temperature and humidity conditions (23±2℃, 50±5% RH) for at least 24 h.

[0090] Test equipment: Surface resistivity tester (DC high resistance meter / electrostatic resistivity meter) equipped with concentric ring electrodes or parallel plate electrodes (electrode size and spacing according to GB / T 1410 requirements); it is recommended to use a 0–1000 V adjustable DC power supply and a Class 1 accuracy voltmeter / ammeter.

[0091] Test environment: 23±2℃, 50±5% RH (standard requirements); record environmental conditions.

[0092] Operating steps:

[0093] Place the sample into the electrode clamp and ensure good contact;

[0094] Apply the standard test voltage (the recommended voltage according to GB / T 1410, usually 100 V or the value specified in the standard);

[0095] Wait for the reading to stabilize (according to the standard time), and record the surface resistivity reading;

[0096] Take at least 5 measurement points at different locations on the sample, calculate the arithmetic mean and record the standard deviation.

[0097] Data acquisition: Surface resistivity (Ω / sq) is obtained directly from the instrument readings; environmental information, sample number, instrument model and range are recorded.

[0098] Parameter meaning explanation: Surface resistivity reflects the resistance per unit area of ​​the material surface under DC conditions, and is used to determine whether it falls within the antistatic / dissipative range (the standard recommended range is determined by the application scenario).

[0099] 2) Volume resistivity – Tested according to GB / T 15662-1995 or GB / T 1410-2006:

[0100] Standard basis: Mainly refers to GB / T 15662-1995 (applicable to conductive / antistatic plastics with volume resistivity less than 10^6 Ω·m); at the same time, GB / T 1410-2006 also provides a method for determining the volume resistivity of solid insulating materials (which can be selected according to the properties of the sample).

[0101] Sample preparation: Sample sheets or flattened tube sheets, with thickness as required by the standard (if the wall thickness is less than the minimum standard thickness, it can be processed by stacking or by an alternative pattern allowed by the standard, and noted in the report). Store at 23±2℃ and 50±5% RH for 24 h.

[0102] Test equipment: Constant voltage DC power supply (0–1000 V, high voltage regulation accuracy), high sensitivity DC ammeter (range 10) -8 -10 -1 A). The electrode is a standard volume resistivity electrode (flat plate electrode), and a suitable clamp is used to apply a constant voltage and clamping force.

[0103] Operating steps:

[0104] Clamp the sample into the electrode holder and ensure flat contact;

[0105] Apply a standard voltage (refer to the recommended values ​​in GB / T 15662 and record the voltage value);

[0106] Measure and record the steady current, and read and convert it into volume resistivity according to the standard (read and record by instrument or manually).

[0107] Take at least 3 sample points at different locations, calculate the average and record it.

[0108] Data acquisition: The volume resistivity (Ω·m) is obtained by directly reading the current and referring to the standard conversion table or method.

[0109] Explanation of parameter meaning: Volume resistivity reflects the internal impedance of the material and is an important indicator for judging the conductivity / grounding performance of the inner layer (especially crucial for the conductivity of the inner layer in Example B).

[0110] 3) Charge decay (or charge discharge) – Tested according to GB / T 17626.2-2018 (equivalent to IEC 61000-4-2) (for evaluating the performance of the hose under discharge events):

[0111] Standard basis: GB / T 17626.2-2018 is the IEC electrostatic discharge immunity test standard adopted by China. It is commonly used as a test method for the discharge tolerance and discharge response of devices / materials (the charge dissipation performance of materials can also be performed and the decay time recorded under this technical framework using similar charged-plate or corona methods).

[0112] Sample preparation: The sample was prepared according to the surface / volume test described above; it was placed under constant temperature and humidity conditions for 24 h.

[0113] Test equipment: charged-plate device or corona discharge device, surface potentiometer (non-contact surface potentiometer or electrometer), and connected potential recording and sampling system.

[0114] Test environment: 23±2℃, 50±5% RH (or environmental conditions as required by standard).

[0115] Operating procedures (procedure for measuring material charge decay):

[0116] Apply a standard voltage (e.g., +1000 V) to the sample surface using a corona device or a contact / non-contact charging method.

[0117] The surface potential decay curve over time was recorded in real time using a surface potentiometer.

[0118] Record the time required for the voltage to decay from the initial voltage to a specified voltage (e.g., 100 V or half-life);

[0119] Repeat the process 3–5 times for each sample point, take the average, and record the standard deviation.

[0120] Data acquisition: Time-potential curves are directly collected from the surface potentiometer, and the discharge time data is exported and archived.

[0121] Explanation of parameter meaning: Charge decay time indicates the material's ability to dissipate surface static charge to the environment or ground. A shorter decay time means faster dissipation / lower risk of sparks (especially important for hoses in hazardous areas).

[0122] Note: GB / T 17626.2-2018 is mainly used for electrostatic discharge resistance testing of equipment; for charge decay testing at the material level, the test apparatus and method framework of this standard can be used for material compatibility testing (the basis and compatibility method should be noted in the report).

[0123] 4) Material and mechanical property testing:

[0124] Tensile properties: Tensile strength and elongation at break tests were conducted according to GB / T 4645 / GB / T 528 / GB / T 21016 (or equivalent Chinese standards of ASTM, commonly GB / T 528-2009, etc.); the equipment was a universal testing machine (Instron or equivalent), and the fixtures and speeds were in accordance with the standards.

[0125] Abrasion resistance test: According to the industry or GB corresponding abrasion standards (such as Taber), the test machine model, grinding wheel model and load, and cycle number criteria should be noted in the report.

[0126] Chemical resistance / weather resistance: Perform the test according to the corresponding weather resistance and chemical resistance standards of GB / T (if outdoor exposure or salt spray test is required, select the corresponding GB / T standard and record the test conditions).

[0127] Minimum bending radius and production line speed:

[0128] The bending test is conducted manually or using a fixture, checking for cracks / permanent deformation at a specified bending radius. The production line speed is the recorded value of the extrusion production parameters.

[0129] The test data is shown in Table 3 below;

[0130] Table 3

[0131] Indicators (test methods / units) Example 1 (Sample A: High Transparency TPU + GNT) Example 2 (Sample B: Coaxial internally conductive PVC with grounding ring) Comparative example (Sample C: conventional PVC + 2% CB) Surface resistivity (GB / T1410-2006, Ω / m) (5.0±0.8)×10^7 (2.0±0.3)×10^6 (1.20±0.20)×10^9 Volume resistivity (GB / T15662-1995 / GB / T1410-2006, Ω·m) (1.0±0.2)×10^8 (2.5±0.4)×10^6 (5.0±0.6)×10^9 Charge decay (charging +1000V → 100V, GB adaptation method, s) 12±2s 6±1s 120±15s Tensile strength (GB / T528-2009, MPa) 32±2MPa 18±1.5MPa 22±1.8MPa Elongation at break (GB / T528-2009, %) 520±30% 320±25% 200±15% Transmittance @ 550nm (UV-Vis, %) 88±2% 10±1% 9±1% Wear cycle count (Taber / industry equivalent, cycles) 1500±120 4000±200 900±100 Minimum bending radius (measured, mm) 12mm 25mm 30mm Production line representative linear velocity (m / min, process parameter) 1.2 m / min 2.5 m / min 1.8 m / min

[0132] Example 1 (High Transparency Dissipation): While maintaining high transparency (≈88%) and excellent elongation (≈520%), it achieves a surface resistivity on the order of 10^7 Ω / m and a charge decay of 12 s, meeting the dissipation requirements of medical / food grade applications and applications sensitive to visual pollution.

[0133] Example 2 (Industrial / Hazardous Areas): By sacrificing transparency, a faster discharge speed (≈6 s), lower volume resistivity, and stronger wear resistance and industrial line speed are achieved through a coaxial inner layer with high conductivity (mainly carbon black) and a grounding ring design, making it suitable for hazardous areas or heavy-duty industrial scenarios.

[0134] The comparative example is far weaker than the two schemes of this invention in terms of surface resistivity and charge decay, indicating that the traditional single-layer low-addition carbon black scheme is difficult to achieve rapid dissipation and other functional combinations at the same time.

[0135] Among them, surface resistivity (Ω / m): the DC resistance per unit area of ​​the material surface, measured by a high-resistivity meter according to GB / T 1410-2006. It is used to determine whether the material belongs to the antistatic / dissipative range.

[0136] Volume resistivity (Ω·m): The impedance of a material's volume to direct current, which is important for determining the conductivity and grounding performance of the inner layers.

[0137] Charge decay time (s): The time required for the surface potential of a material to decay to a specified value after it is charged, which directly reflects the dissipation rate and the risk of sparks.

[0138] Tensile strength / elongation at break: Mechanical properties of the material, measured on a universal testing machine according to GB standards for hose samples (or cut pieces).

[0139] Transmittance (%): The transmittance of UV-Vis at 550 nm, reflecting its transparency.

[0140] Wear cycle count: indicates the number of cycles a material can withstand before failure in a friction and wear test.

[0141] Minimum bending radius (mm): The minimum radius that allows for safe bending in the usage scenario.

[0142] Production line speed (m / min): A production parameter that affects capacity and process stability (recorded as a process comparability indicator in this test).

[0143] As can be seen from the above, this invention combines high-efficiency nano-carbon materials with economical micron-sized carbon black in a complementary manner, and employs masterbatch pre-dispersion, high-shear short-time dispersion, and conductive distribution design along the thickness direction in the formulation and processing. This allows conductive pathways to form and remain stable for a long time under a low overall filler load. It maintains the flexibility and feel of the flexible tube while also ensuring high transparency when needed (suitable for medical / food applications), thus overcoming the destructive effects of traditional high-carbon black content formulations on transparency and flexibility, and improving the material's applicability and product added value.

[0144] This invention proposes a coaxial structure design with an inner high-conductivity layer and an outer low-filler layer. Combined with a grounding / contact ring (or grounding strip) pre-installed in the mold or wrapped in a subsequent process, this design provides a reliable grounding path for the internal conductive system while ensuring the comfort and weather resistance of the outer layer. This structured solution facilitates mass production on the production line, on-site grounding installation and maintenance, and significantly improves electrostatic safety in flammable, dusty, or explosive environments. It enables the hose to quickly and controllably discharge electrostatic energy to ground under actual operating conditions, thereby reducing the risk of ignition and improving system reliability.

[0145] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing an antistatic plastic hose, characterized in that, include: S1. Ingredients: Mix the matrix thermoplastic polymer, conductive / dissipative filler, plasticizer, heat stabilizer, processing aid and antioxidant; The matrix thermoplastic polymer is at least one of thermoplastic polyurethane, polyvinyl chloride, or thermoplastic rubber. The conductive / dissipative filler is at least one of carbon black, graphene nanosheets, and carbon nanotubes, and the mass fraction of the conductive / dissipative filler in the final mixture is 0.05–20 wt%. The ingredients are premixed at the feeding port and fed into a parallel or series twin-screw extruder to produce conductive / dissipative masterbatch. S2. Compounding: The conductive / dissipative masterbatch and the matrix resin are co-extruded and compounded on a twin-screw extruder according to a predetermined ratio. The extrusion process parameters are: the extruder barrel temperature zone is 140–240℃, the screw speed is 80–350 rpm, vacuum exhaust and shear control are used to ensure good dispersion of the nanofiller. S3. Extrusion molding: The compounded melt is extruded through a die to form a hose blank. The die temperature is controlled at 150–230℃. The die orifice is designed as a spiral reinforcement or a straight cylindrical shape. The hose wall thickness is 0.5–6.0 mm as required. After extrusion, the hose is shaped, drawn, cut or wound in a cooling water tank. S4. Annealing / Temperature Treatment: Perform heat conditioning / annealing treatment at 60–120℃ for 10–60 minutes on the extruded hose to release internal stress and stabilize the conductive network, resulting in an antistatic plastic hose.

2. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, The method further includes: in step S2 or step S3, by controlling the total content, dispersion mode and morphology of the nanofiller to form a conductive / dissipative distribution along the thickness direction, so as to achieve stable antistatic performance while ensuring the flexibility of the hose.

3. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, The conductive / dissipative filler adopts a mixed filler strategy, in which carbon black accounts for 10–95 wt% of the total filler and graphene nanosheets or multi-walled carbon nanotubes account for 0.05–10 wt% of the total filler. By combining the volume economy of carbon black with the low-threshold network formation characteristics of nano-carbon materials, conductive channels are formed with a low total filler content.

4. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, In step S1, pre-dispersed graphene nanosheets / single-walled carbon nanotube masterbatches are used. The mass fraction of the nanomaterials in the final compound is 0.05–0.8 wt%. Short-term strong shear dispersion is performed using the high-speed section of a high-shear twin-screw extruder to achieve a dissipation performance with a surface resistivity of approximately 10^6–10^9 Ω / sq while maintaining the transparency of the matrix.

5. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, In step S1, the dissipative filler is an ionic / polar antistatic agent, with an addition amount of 0.1–3.0 phr. It forms a low-resistance dissipative surface on the outer surface of the hose through diffusion or surface migration mechanism. This type of antistatic agent and conductive masterbatch are added in stages to avoid long-term migration leading to material performance degradation. The ionic / polar antistatic agent is at least one of quaternary ammonium salts and polyether antistatic agents.

6. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, The composite hose can adopt a coaxial double-layer extrusion structure, with the inner layer being a high conductivity / dissipation formula and the outer layer being a low filler and high flexibility formula. The thickness ratio of the inner and outer layers can be adjusted between 20:80 and 80:20 through a coaxial die head.

7. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, A full-layer conductive / grounded flexible hose structure is adopted, and metal grounding rings or brush contact points are set at intervals along the length of the hose to ensure that electrostatic energy can be discharged to the ground in a timely manner; The conductive filler content in the full-layer conductive formulation is 2–15 wt%.

8. The method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, In step S2, the following set of processing parameters is used in the twin-screw extrusion process: The feed temperature is 20–60℃, and the zone temperatures of the extruder barrel are 140–170℃, 150–200℃, 160–220℃, and 150–230℃ for the feed end, middle section, front section, and die head, respectively. Screw speed: 80–350 rpm; linear velocity: 0.5–6 m / min depending on hose diameter; Vacuum degassing pressure ≤ 5 mbar to remove low molecular weight volatiles and prevent bubbles; The die diameter and die opening clearance are designed according to the required wall thickness and flow rate, and a fixed-length cutting is performed using a bladed or vibratory cutting system.

9. A method for manufacturing an antistatic plastic hose according to claim 1, characterized in that, Step S3 or step S4 involves performing online or offline surface modification on the hose; The surface modification includes: spraying a thin dissipative coating or hot-pressing a self-conductive thin film after plasma surface activation, in order to further reduce surface resistance and improve wear resistance and weather resistance.

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