A high-temperature resistant and stable heating wire and its preparation method and application

Abstract

The present application relates to the technical field of polymer conductive fibers, in particular to a high-temperature resistant and stable heating wire and its preparation method and application. A high-temperature resistant and stable heating wire includes a core wire and a high-temperature resistant electric heating composite layer, the thickness of the high-temperature resistant electric heating composite layer is 50-1500μm; the resistivity of the high-temperature resistant electric heating composite layer is 0.5-50Ω·cm; the high-temperature resistant electric heating composite layer contains at least a conductive filler composition, a high-temperature resistant organic polymer, a surface modifier, and an anti-aging additive, and the conductive filler composition content is 20-40wt%; the high-temperature resistant organic polymer is a thermosetting high-temperature resistant resin or a thermoplastic high-temperature resistant resin. The heating wire prepared in this application can be stably used at 40 to 400°C, and after 1000 cycles of heating tests, the resistance value change rate of the heating wire at 25°C is less than 3%, and the resistance value change rate at 400°C is less than 5%.

Description

Technical Field

[0001] This application relates to the field of polymer conductive fiber technology, and in particular to a high-temperature resistant and stable heating wire. Background Art

[0002] Heating wires possess good electrical conductivity, converting electrical energy into internal energy when energized. This characteristic of releasing heat when energized makes them widely used in heating and insulation applications. Common heating wires include metal alloy conductive wires, graphene carbon paste wires, and carbon fiber conductive wires. Metal alloy conductive wires have good conductivity and heat resistance, but their weight and poor bending performance limit their application range. Although graphene carbon paste wires are inexpensive and simple to manufacture, their poor wear resistance leads to graphene detachment during use, causing uneven overall resistance and limiting their application range. Carbon fiber wires have good conductivity and high-temperature stability, but their manufacturing process is demanding, and high-performance carbon fiber conductive materials rely on imports, resulting in high overall costs and making them unsuitable for large-scale commercial applications. Furthermore, the overall bending toughness of carbon fiber is relatively worse than that of metal alloy wires, limiting its application and development. Therefore, the inventors provide a high-temperature resistant and stable heating wire and its preparation method. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a high-temperature resistant and stable heating wire, its preparation method, and its application.

[0004] The high-temperature resistant and stable heating wire provided in this application is achieved through the following technical solution:

[0005] A high-temperature resistant and stable heating wire includes a core wire and a high-temperature resistant electrothermal composite layer covering the outer wall of the core wire. The high-temperature resistant electrothermal composite layer is coated with an insulating layer. The thickness of the high-temperature resistant electrothermal composite layer is 50-1500 μm. The resistivity of the high-temperature resistant electrothermal composite layer is 0.5-50 Ω·cm. The high-temperature resistant electrothermal composite layer contains at least a conductive filler composition, a high-temperature resistant organic polymer, a surface modifier, and an aging resistant agent. The content of the conductive filler composition is 20-40 wt%. The high-temperature resistant organic polymer is a thermosetting high-temperature resistant resin or a thermoplastic high-temperature resistant resin.

[0006] Preferably, the thermosetting high-temperature resistant resin includes at least one of thermosetting polyphenylene sulfide resin PPS and thermosetting polyimide resin TPI; the thermoplastic high-temperature resistant resin includes at least one of thermoplastic polyimide resin TPI, thermoplastic polyphenylene sulfide resin PPS, and thermoplastic fluorocarbon resin; and the polytetrafluoroethylene resin includes at least one of polytetrafluoroethylene PTFE, polychlorotrifluoroethylene PCTFE, polyvinylidene fluoride PVDF, ethylene-tetrafluoroethylene copolymer ETFE, and ethylene-chlorotrifluoroethylene copolymer ECTFE.

[0007] Preferably, the high-temperature resistant electrothermal composite layer is made of the following raw materials in weight percentages: 20-40 wt% conductive filler composition, 0.8-1 wt% surface modifier, 0.8-1.6 wt% aging resistant additive, 3-6 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS).

[0008] Preferably, the high-temperature resistant electrothermal composite layer is made of the following raw materials in weight percentages: 20-40 wt% conductive filler composition, 1.2-1.8 wt% surface modifier, 0.6-1.2 wt% aging resistant additive, 4-8 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF).

[0009] Preferably, the conductive filler composition is made from the following raw materials in the indicated weight percentages: 5-20 wt% flake graphite, 20-40 wt% nano-barium titanate, 1-5 wt% titanium diboride whiskers, 3-8 wt% titanium nitride, 5-20 wt% molybdenum disilicide nanosheets, 0-5 wt% graphene, and the balance being microcrystalline graphite.

[0010] The heating wire prepared in this application can be used stably from -40 to 200°C, and after 1000 cycles of heating test, the resistance change rate of the heating wire is less than 3% at 25°C and less than 5% at 200°C.

[0011] Preferably, the surface modifier is composed of at least one of 3-propyl isocyanate triethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane combined with titanate coupling agent HY-201.

[0012] By adopting the above technical solution, the uniformity of the conductive filler composition in the high-temperature resistant organic polymer can be improved, thereby improving the conductivity of the prepared heating wire, and at the same time improving the overall heat resistance stability and service life.

[0013] Preferably, the conductive filler composition is made from the following raw materials in the indicated weight percentages: 10-12 wt% flake graphite, 32-36 wt% nano-barium titanate, 2-4 wt% titanium diboride whiskers, 5-6 wt% titanium nitride, 10-15 wt% molybdenum disilicide nanosheets, 0.5-2 wt% graphene, with the balance being microcrystalline graphite.

[0014] By optimizing the conductive filler composition, the conductivity of the resistance wire can be guaranteed while improving its heat resistance stability and reducing production costs.

[0015] The method for preparing a high-temperature resistant and stable heating wire provided in this application is achieved through the following technical solution:

[0016] A method for preparing a high-temperature resistant and stable heating wire includes the following steps:

[0017] Step 1: Production of raw materials for preparing the high-temperature resistant electrothermal composite layer:

[0018] When thermosetting high-temperature resistant resin is used in the high-temperature resistant electrothermal composite layer, the thermosetting high-temperature resistant resin monomer is first reacted until the system viscosity is 6000-20000 mPa·s / 25℃, and then the accurately metered conductive filler composition, surface modifier, and anti-aging additive are added and mixed evenly to obtain the high-temperature resistant electrothermal paste.

[0019] When thermoplastic high-temperature resistant resin is used in the high-temperature resistant electrothermal composite layer, the high-temperature resistant electrothermal masterbatch is made by melt extrusion, drawing, cooling, granulation and drying of conductive filler composition, thermoplastic high-temperature resistant resin, surface modifier and anti-aging agent.

[0020] Step 2: When the high-temperature resistant electrothermal composite layer is made of high-temperature resistant electrothermal paste, the core wire is immersed in the high-temperature resistant electrothermal paste and pulled at a speed of 1-10cm / s so that the high-temperature resistant electrothermal paste adheres to the outer wall of the core wire. Then, it is transferred to an oven for curing, thus bonding the high-temperature resistant electrothermal composite layer to the outside of the core wire to obtain the finished heating wire.

[0021] When the high-temperature resistant electrothermal composite layer is made of high-temperature resistant electrothermal masterbatch, the molten extruded material obtained after melting and extruding the high-temperature resistant electrothermal masterbatch is attached to the outer surface of the core wire, and the finished heating wire can be obtained by water cooling, heat treatment and drying.

[0022] The method for preparing the heating wire in this application is relatively simple, easy to operate, and easy to industrialize.

[0023] The high-temperature resistant and stable heating wire in this application is used in the field of heat tracing wires and has excellent high-temperature stability.

[0024] In summary, this application has the following advantages:

[0025] 1. The heating wire prepared in this application can be used stably from -40 to 400°C, and after 1000 cycles of heating test, the resistance change rate of the heating wire is less than 3% at 25°C and less than 5% at 400°C.

[0026] 2. The application of this invention incorporates an appropriate amount of graphene into the heating wire, which can improve the overall conductivity and effectively enhance the overall flame retardant safety performance.

[0027] 3. The method for preparing the heating wire in this application is relatively simple, easy to operate, and easy to realize industrial production. DETAILED DESCRIPTION

[0028] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples and comparative examples.

[0029] Example

[0030] A high-temperature resistant and stable heating wire includes a core wire and a high-temperature resistant electrothermal composite layer covering the outer wall of the core wire. The high-temperature resistant electrothermal composite layer is coated with an insulating layer. The thickness of the high-temperature resistant electrothermal composite layer is 50-1500 μm, and the resistivity of the high-temperature resistant electrothermal composite layer is 0.5-50 Ω·cm. That is, the thicker the high-temperature resistant electrothermal composite layer, the better the conductivity of the prepared heating wire. The core wire can be selected from at least one of conductive or non-conductive chemical fiber filaments, metal wires, alloy wires, carbon fiber filaments, and conductive ceramic wires, depending on the resistance requirements.

[0031] The high-temperature resistant electrothermal composite layer contains at least a conductive filler composition, a high-temperature resistant organic polymer, a surface modifier, and an aging resistant agent. The conductive filler composition content is 20-40 wt%. The high-temperature resistant organic polymer can be a thermosetting high-temperature resistant resin or a thermoplastic high-temperature resistant resin, depending on the customer's requirements for the heating wire.

[0032] The surface modifier is composed of at least one of propyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane combined with titanate coupling agent HY-201.

[0033] The anti-aging additive is composed of at least one of silicon nitride and silicon dioxide, combined with antioxidant 1010, antioxidant 168 and UV stabilizer 326.

[0034] The conductive filler composition is made from the following raw materials in the following weight percentages: 5-20 wt% flake graphite, 20-40 wt% nano barium titanate, 1-5 wt% titanium diboride whiskers, 3-8 wt% titanium nitride, 5-20 wt% molybdenum disilicide nanosheets, 0-5 wt% graphene, and the balance being microcrystalline graphite.

[0035] Preferably, the conductive filler composition is made from the following raw materials in the indicated weight percentages: 10-12 wt% flake graphite, 32-36 wt% nano-barium titanate, 2-4 wt% titanium diboride whiskers, 5-6 wt% titanium nitride, 10-15 wt% molybdenum disilicide nanosheets, 0.5-2 wt% graphene, with the balance being microcrystalline graphite.

[0036] A method for preparing a high-temperature resistant and stable heating wire includes the following steps:

[0037] Step 1, Production of raw materials for preparing high-temperature resistant electrothermal composite layer: First, react the thermosetting high-temperature resistant resin monomers until the system viscosity is 6000-20000 mPa·s / 25℃, then add the accurately metered conductive filler composition, surface modifier, and anti-aging additive and mix evenly to obtain high-temperature resistant electrothermal paste.

[0038] Step 2: Immerse the core wire in high-temperature resistant electrothermal paste, and pull the core wire at a speed of 1-10cm / s to allow the high-temperature resistant electrothermal paste to adhere to the outer wall of the core wire. Then transfer it to an oven for curing, thus bonding a high-temperature resistant electrothermal composite layer onto the outside of the core wire to obtain the finished heating wire.

[0039] Preferably, the high-temperature resistant electrothermal composite layer is made of the following raw materials in weight percentages: 20-40 wt% conductive filler composition, 1.2-1.8 wt% surface modifier, 0.6-1.2 wt% aging resistant additive, 4-8 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF).

[0040] Preferably, the high-temperature resistant electrothermal composite layer is made of the following raw materials in weight percentages: 20-40 wt% conductive filler composition, 0.8-1 wt% surface modifier, 0.8-1.6 wt% aging resistant additive, 3-6 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS).

[0041] A method for preparing a high-temperature resistant and stable heating wire includes the following steps:

[0042] Step 1, Production of raw materials for preparing high-temperature resistant electrothermal composite layer: The high-temperature resistant electrothermal masterbatch is prepared by melt extrusion, fiber drawing, cooling, granulation and drying of conductive filler composition, thermoplastic high-temperature resistant resin, surface modifier, and anti-aging additive.

[0043] Step 2: After melting and extruding the high-temperature resistant electric heating masterbatch, the resulting molten extruded material is attached to the outer surface of the core wire. Water cooling, heat treatment, and drying are then performed to obtain the finished heating wire.

[0044] The high-temperature resistant and stable heating wire in this application can be used in the field of heat tracing wire and can replace expensive carbon fiber conductive wire products.

[0045] Example 1: A high-temperature resistant and stable heating wire includes a core wire and a high-temperature resistant electrothermal composite layer covering the outer wall of the core wire. The high-temperature resistant electrothermal composite layer is coated with a 50nm Al2O3 insulating layer by a sol-gel method. The core wire is Vectran 50D aramid yarn from Kuraray, Japan.

[0046] The high-temperature resistant electrothermal composite layer is made of high-temperature resistant electrothermal masterbatch, which is made of the following raw materials by weight percentage: 20wt% conductive filler composition, 1.2wt% surface modifier, 1wt% aging resistant additive, 6wt% dibutyl phthalate (DBP), and the balance is polyvinylidene fluoride (PVDF) (French Arkema 740 extrusion grade).

[0047] The surface modifier is composed of 3-propyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and titanate coupling agent HY-201 in a mass ratio of 4:3:3. The anti-aging additive is composed of nano-silicon nitride, antioxidant 1010, antioxidant 168, and UV stabilizer 326 in a mass ratio of 5:4:1:5.

[0048] The conductive filler composition is made from the following raw materials in the following weight percentages: 10 wt% flake graphite (brand: Yuchen Graphite, average particle size customized 1μm), 30 wt% nano barium titanate (BT-2 high purity nano electronic grade barium titanate BaTiO3, brand: Wohai Chemical), 2 wt% titanium diboride whiskers, 5 wt% nano titanium nitride (brand: Huaxiang, average particle size 700nm), 10 wt% molybdenum disilicide nanosheets (XF137 small diameter thin-layer molybdenum disulfide nanosheets from Xianfeng Nano, sheet diameter: 20-500nm, thickness: 1-5nm), and the balance is microcrystalline graphite (brand: Jingao, 2000 mesh earthy graphite microcrystalline graphite powder).

[0049] Preparation method of titanium diboride whiskers: Weigh 347g of titanium dioxide, 204g of boron oxide, 260g of activated carbon, 63g of sodium chloride (a whisker growth flux), and 26g of nickel (a whisker growth catalyst) and mix them to obtain a composite powder. The composite powder is then placed in a cylinder ball mill and dry-milled with alumina balls for 8 hours. After passing through a 100-mesh sieve, it is placed into a graphite reaction vessel with a cap at one end, a closed bottom, and multiple holes in the middle. The circular holes are evenly distributed on the outer wall of the graphite reaction vessel, with a diameter of approximately 10mm and a distance of approximately 20mm from the end. This reaction vessel is then placed in a high-temperature sintering furnace for whisker cultivation. The specific process is as follows: heating rate of 100℃ / min, argon atmosphere protection, holding at 1500℃ for 60min, and cooling to room temperature at a cooling rate of 10℃ / min to synthesize the desired titanium diboride whisker material.

[0050] A method for preparing a high-temperature resistant and stable heating wire includes the following steps:

[0051] Step 1: Production of raw materials for preparing the high-temperature resistant electrothermal composite layer: The conductive filler composition, polyvinylidene fluoride (PVDF) resin, surface modifier, dibutyl phthalate (DBP), and anti-aging additive are placed in a high-speed dispersion kettle and mixed at 400 rpm for 60 minutes. The resulting mixture is then placed in a twin-screw extruder and melt-extruded at 240-260°C. The resulting melt extrudate is drawn into fibers, cooled, granulated, and dried to obtain a high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0 mm.

[0052] Step two: The high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0 mm obtained in step one is fed into a twin-screw extruder and melt-extruded at 240-260℃. The resulting molten extruded material adheres to the outer surface of Vectran 50D aramid filament. The traction speed of the Vectran 50D aramid filament is 1.2 m / s. After water cooling for 15 seconds, the Vectran 50D aramid filament with the high-temperature resistant electrothermal composite material on its outer surface is sent to an oven at 1200℃ for 30 minutes of heat treatment, followed by drying in an oven at 80℃ for 120 minutes. Finally, a 50 nm coated Al2O3 insulating layer is laminated onto the high-temperature resistant electrothermal composite layer using a sol-gel method to obtain the finished heating wire. The thickness of the high-temperature resistant electrothermal composite layer is 927.5 μm. The resistivity of the high-temperature resistant electrothermal composite layer in the finished heating wire is 39.41 Ω·cm, and its surface resistivity is 6.94 × 10⁻⁶. 14 Ω·cm, meaning the surface is insulated and has good thermal conductivity, and the steady-state heating temperature of the finished heating wire can be controlled by controlling the voltage.

[0053] The difference between Example 2 and Example 1 is that the high-temperature resistant electrothermal masterbatch is made from the following raw materials by weight percentage: 30 wt% conductive filler composition, 1.5 wt% surface modifier, 1 wt% aging resistant agent, 7.2 wt% dibutyl phthalate (DBP), and the balance is polyvinylidene fluoride (PVDF). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 958.1 μm, and the resistivity of the resulting finished heating wire is 27.25 Ω·cm. The steady-state heating temperature of the finished heating wire can be controlled by controlling the voltage.

[0054] The difference between Example 3 and Example 1 is that the high-temperature resistant electrothermal masterbatch is made from the following raw materials by weight percentage: 35 wt% conductive filler composition, 1.65 wt% surface modifier, 1 wt% aging resistant agent, 7.5 wt% dibutyl phthalate (DBP), and the balance is polyvinylidene fluoride (PVDF). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 964.1 μm, and the resistivity of the resulting finished heating wire is 22.49 Ω·cm. The steady-state heating temperature of the finished heating wire can be controlled by controlling the voltage.

[0055] The difference between Example 4 and Example 1 is that the high-temperature resistant electrothermal masterbatch is made from the following raw materials by weight percentage: 40 wt% conductive filler composition, 1.8 wt% surface modifier, 1 wt% aging resistant agent, 8 wt% dibutyl phthalate (DBP), and the balance is polyvinylidene fluoride (PVDF). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 972.5 μm, and the resistivity of the resulting finished heating wire is 18.25 Ω·cm. The steady-state heating temperature of the finished heating wire can be controlled by controlling the voltage.

[0056] The difference between Example 5 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 12 wt% flake graphite, 35 wt% nano-barium titanate, 3.2 wt% titanium diboride whiskers, 5.4 wt% nano-titanium nitride, 15 wt% molybdenum disilicide nanosheets, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 938.1 μm, and the resistivity of the resulting heating wire is 40.05 Ω·cm.

[0057] The difference between Example 6 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 12 wt% flake graphite, 35 wt% nano-barium titanate, 3.2 wt% titanium diboride whiskers, 5.4 wt% nano-titanium nitride, 15 wt% molybdenum disilicide nanosheets, 2 wt% graphene, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 918.7 μm, and the resistivity of the resulting heating wire is 27.38 Ω·cm.

[0058] The difference between Example 7 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 5 wt% flake graphite, 20 wt% nano-barium titanate, 1 wt% titanium diboride whiskers, 3 wt% nano-titanium nitride, 5 wt% molybdenum disilicide nanosheets, 5 wt% graphene, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 921.2 μm, and the resistivity of the resulting heating wire is 12.07 Ω·cm.

[0059] The difference between Example 8 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 20 wt% flake graphite, 40 wt% nano-barium titanate, 5 wt% titanium diboride whiskers, 5 wt% nano-titanium nitride, 15 wt% molybdenum disilicide nanosheets, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 940.4 μm, and the resistivity of the resulting heating wire is 44.29 Ω·cm.

[0060] The difference between Example 9 and Example 1 is that the high-temperature resistant electrothermal masterbatch is made from the following raw materials in weight percentages: 40 wt% conductive filler composition, 1.8 wt% surface modifier, 1 wt% aging resistant agent, 8 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF). The conductive filler composition is made from the following raw materials in weight percentages: 5 wt% flake graphite, 20 wt% nano-barium titanate, 1 wt% titanium diboride whiskers, 3 wt% nano-titanium nitride, 5 wt% molybdenum disilicide nanosheets, 5 wt% graphene, and the balance being microcrystalline graphite.

[0061] The difference in the preparation method of the heating wire is as follows: In step two, the high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0 mm obtained in step one is fed into a twin-screw extruder and melt-extruded at 240-260℃. The resulting melt-extruded material is attached to the outer surface of Vectran 50D aramid yarn. The traction speed of Vectran 50D aramid yarn is 4.0 m / s. After the Vectran 50D aramid yarn with the high-temperature resistant electrothermal composite material attached to its outer surface is cooled by water cooling for 15 seconds, it is sent to an oven at 120℃ for 30 minutes of heat treatment, and then sent to an oven at 80℃ for 120 minutes of drying treatment to obtain the finished heating wire. The thickness of the high-temperature resistant electrothermal composite layer is 208.4 μm, and the resistivity of the finished heating wire is 15.30 Ω·cm.

[0062] The difference between Example 10 and Example 9 is as follows: In step two, the high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0 mm obtained in step one is fed into a twin-screw extruder and melt-extruded at 240-260℃. The resulting melt-extruded material adheres to the outer surface of Vectran 50D aramid filament. The traction speed of the Vectran 50D aramid filament is 0.75 m / s. After the Vectran 50D aramid filament with the high-temperature resistant electrothermal composite material attached to its outer surface is cooled by water cooling for 15 seconds, it is sent to an oven at 1200℃ for 30 minutes of heat treatment, and then sent to an oven at 80℃ for 120 minutes of drying treatment to obtain the finished heating wire. The thickness of the high-temperature resistant electrothermal composite layer is 1458.6 μm, and the resistivity of the finished heating wire is 2.08 Ω·cm.

[0063] The difference between Comparative Example 1 and Example 1 is that the high-temperature resistant electrothermal composite layer is made of high-temperature resistant electrothermal masterbatch, which is made of the following raw materials by weight percentage: 10 wt% conductive filler composition, 1 wt% surface modifier, 1 wt% aging resistant agent, 5 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 909.8 μm, and the resistivity of the resulting finished heating wire is 87.35 Ω·cm.

[0064] The difference between Comparative Example 2 and Example 1 is that the high-temperature resistant electrothermal composite layer is made of high-temperature resistant electrothermal masterbatch, which is made of the following raw materials by weight percentage: 50 wt% conductive filler composition, 2 wt% surface modifier, 1 wt% aging resistant agent, 8 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 981.4 μm, and the resistivity of the resulting finished heating wire is 15.51 Ω·cm.

[0065] The difference between Comparative Example 3 and Example 1 is that the surface modifier is γ-methacryloyloxypropyltrimethoxysilane. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 965.1 μm, and the resistivity of the resulting finished heating wire is 44.72 Ω·cm.

[0066] The difference between Comparative Example 4 and Example 1 is that the anti-aging additive is composed of antioxidant 1010, antioxidant 168, and UV stabilizer 326 in a mass ratio of 4:1:5. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 925.1 μm, and the resistivity of the resulting finished heating wire is 40.19 Ω·cm.

[0067] The difference between Comparative Example 5 and Example 1 is that the conductive filler composition is made of 20 wt% flake graphite and 80 wt% microcrystalline graphite. The finished heating wire has a high-temperature resistant electrothermal composite layer thickness of 879.1 μm and a resistivity of 37.29 Ω·cm.

[0068] The difference between Comparative Example 6 and Example 1 is that the conductive filler composition is made of 20 wt% flake graphite, 10 wt% molybdenum disilicide nanosheets, and 70 wt% microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 911.8 μm, and the resistivity of the resulting finished heating wire is 42.69 Ω·cm.

[0069] The difference between Comparative Example 7 and Example 1 is that the conductive filler composition is made of 20 wt% flake graphite, 5 wt% nano-silicon nitride, and 75 wt% microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 907.8 μm, and the resistivity of the resulting finished heating wire is 35.58 Ω·cm.

[0070] The difference between Comparative Example 8 and Example 1 is that the conductive filler composition is made of 20 wt% flake graphite, 20 wt% nano-barium titanate, 10 wt% molybdenum disilicide nanosheets, and 50 wt% microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 921.7 μm, and the resistivity of the resulting finished heating wire is 40.72 Ω·cm.

[0071] The difference between Example 11 and Example 1 is that the high-temperature resistant electrothermal composite layer is made of the following raw materials by mass percentage: 20wt% conductive filler composition, 0.8wt% surface modifier, 1.2wt% anti-aging agent, 4wt% hyperbranched PPS resin, and the balance is thermoplastic polyphenylene sulfide resin PPS (Toray A504X90).

[0072] Preparation method of hyperbranched PPS resin: First, add 3,5-dichlorothiophenol 3,5-DB (2.5 g), anhydrous K2CO3 (3.350 g), and 20 mL of anhydrous NMP (dried from anhydrous sodium sulfate) to a 100 mL three-necked flask equipped with a condenser and a magnetic inlet. Vacuum the flask three times with nitrogen. Then, under a nitrogen flow, heat the system in an oil bath with vigorous stirring until it reaches 150 °C. Continue the reaction at this temperature for 8 hours. After the reaction is complete, cool to room temperature and pour the product from the flask into 75 mL of 6mol... In a 1 / L HCl solution, the mixture was stirred vigorously for 2 hours, producing a large amount of precipitate. The precipitate was then vacuum filtered and washed with a large amount of deionized water until the filtrate was colorless. The product was then separated by vacuum filtration and dried under vacuum at 40°C for 24 hours. Finally, the dried product was dissolved in a small amount of tetrahydrofuran and added dropwise to 4 times its volume of anhydrous ethanol. The mixture was stirred for another 1 hour, producing a large amount of precipitate. The precipitate was then vacuum filtered and washed with a large amount of anhydrous ethanol until the filtrate was colorless. The product was then separated and dried to obtain a grayish-white powder product, HPPS resin.

[0073] A method for preparing a high-temperature resistant and stable heating wire includes the following steps:

[0074] Step 1: Production of raw materials for preparing the high-temperature resistant electrothermal composite layer: The conductive filler composition, thermoplastic polyphenylene sulfide resin (PPS), surface modifier, hyperbranched PPS resin, and anti-aging additive are placed in a high-speed dispersion kettle and mixed at 400 rpm for 60 minutes. The resulting mixture is then placed in a twin-screw extruder and melt-extruded at 320-335℃. Specifically, the feeding section temperature is 195℃, the barrel temperature is 300-335℃, the connector temperature is 320-335℃, and the die temperature is 300-320℃. The resulting melt extrudate is drawn into fibers, cooled, granulated, and dried to obtain a high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0 mm.

[0075] Step two: The high-temperature resistant electrothermal masterbatch with a particle size of 1.8-2.0mm obtained in step one is fed into a twin-screw extruder and melt-extruded at 320-335℃. Specifically, the feeding section temperature is 195℃, the barrel temperature is 300-335℃, the connector temperature is 320-335℃, and the die temperature is 300-320℃. The resulting melt-extruded material adheres to the outer surface of Vectran 50D aramid filament. The traction speed of the Vectran 50D aramid filament is 1.5m / s. The resulting Vectran... After 50D aramid yarn is cooled by water for 25 seconds, it is placed in an oven at 1200℃ for 30 minutes of heat treatment, and then placed in an oven at 95℃ for 120 minutes of drying to obtain the finished heating wire. The thickness of the high-temperature resistant electrothermal composite layer is 856.4μm, and the resistivity of the obtained heating wire is 41.08Ω·cm. The steady-state heating temperature of the finished heating wire can be controlled by controlling the voltage.

[0076] The difference between Example 12 and Example 1 is that the high-temperature resistant electrothermal composite layer is made from the following raw materials by weight percentage: 30 wt% conductive filler composition, 1 wt% surface modifier, 1.2 wt% aging resistant additive, 5 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 860.5 μm, and the resistivity of the resulting finished heating wire is 32.45 Ω·cm.

[0077] The difference between Example 13 and Example 1 is that the high-temperature resistant electrothermal composite layer is made from the following raw materials by weight percentage: 40 wt% conductive filler composition, 1 wt% surface modifier, 1.2 wt% aging resistant additive, 6 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 872.5 μm, and the resistivity of the resulting finished heating wire is 20.59 Ω·cm.

[0078] The difference between Example 14 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 12 wt% flake graphite, 35 wt% nano-barium titanate, 3.2 wt% titanium diboride whiskers, 5.4 wt% nano-titanium nitride, 15 wt% molybdenum disilicide nanosheets, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 867.1 μm, and the resistivity of the resulting heating wire is 41.74 Ω·cm.

[0079] The difference between Example 15 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 12 wt% flake graphite, 35 wt% nano-barium titanate, 3.2 wt% titanium diboride whiskers, 5.4 wt% nano-titanium nitride, 15 wt% molybdenum disilicide nanosheets, 2 wt% graphene, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 875.1 μm, and the resistivity of the resulting heating wire is 28.74 Ω·cm.

[0080] The difference between Example 16 and Example 1 is that the conductive filler composition is made from the following raw materials in the indicated weight percentages: 5 wt% flake graphite, 20 wt% nano-barium titanate, 1 wt% titanium diboride whiskers, 3 wt% nano-titanium nitride, 5 wt% molybdenum disilicide nanosheets, 5 wt% graphene, and the balance being microcrystalline graphite. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 867.9.5 μm, and the resistivity of the resulting heating wire is 13.56 Ω·cm.

[0081] The difference between Comparative Example 9 and Example 1 is that the high-temperature resistant electrothermal composite layer is made from the following raw materials by weight percentage: 10 wt% conductive filler composition, 0.8 wt% surface modifier, 1.2 wt% aging resistant additive, 4 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 867.2 μm, and the resistivity of the resulting finished heating wire is 93.75 Ω·cm.

[0082] The difference between Comparative Example 10 and Example 1 is that the high-temperature resistant electrothermal composite layer is made from the following raw materials by weight percentage: 45 wt% conductive filler composition, 0.8 wt% surface modifier, 1.2 wt% aging resistant additive, 6 wt% hyperbranched PPS resin, and the balance being thermoplastic polyphenylene sulfide resin (PPS). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 877.5 μm, and the resistivity of the resulting finished heating wire is 17.41 Ω·cm.

[0083] The difference between Comparative Example 11 and Example 1 is that the high-temperature resistant electrothermal composite layer is made from the following raw materials by weight percentage: 20 wt% conductive filler composition, 0.8 wt% surface modifier, 1.2 wt% aging resistant additive, and the balance being thermoplastic polyphenylene sulfide resin (PPS). The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 938.4 μm, and the resistivity of the resulting finished heating wire is 52.08 Ω·cm.

[0084] The difference between Comparative Example 12 and Example 1 is that the surface modifier is γ-methacryloyloxypropyltrimethoxysilane. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 879.5 μm, and the resistivity of the resulting finished heating wire is 45.54 Ω·cm.

[0085] The difference between Comparative Example 13 and Example 1 is that the anti-aging additive is composed of antioxidant 1010, antioxidant 168, and UV stabilizer 326 in a mass ratio of 4:1:5. The thickness of the high-temperature resistant electrothermal composite layer in the finished heating wire is 881.4 μm, and the resistivity of the resulting finished heating wire is 41.64 Ω·cm.

[0086] The difference between Comparative Example 14 and Example 1 is that the conductive filler composition is made of 20 wt% flake graphite and 80 wt% microcrystalline graphite. The finished heating wire has a high-temperature resistant electrothermal composite layer with a thickness of 851.5 μm and a resistivity of 38.32 Ω·cm.

[0087] Table 1: Test parameters of the finished heating wires in Examples 1-10 and Comparative Examples 1-8

[0088]

[0089] As can be seen from Examples 1-10 and Comparative Examples 1-8 and Table 1, the conductive filler composition compounded in this application can impart good conductivity and high-temperature stability to the heating wire. The resistivity of the finished heating wire in this application is 0.5-50 Ω·cm. After 1000 cycles of heating test, the resistance change rate of the heating wire is less than 3% at 25°C and less than 5% at 200°C. It is applied to the field of heat tracing wire with PTC effect, specifically for the insulation of oil pipelines.

[0090] As can be seen from Examples 1-10 and Comparative Examples 1-8 and Table 1, the finished heating wire obtained by using the compounded surface modifier in this application has better resistance stability and makes the conductive filler composition uniformly dispersed, thus ensuring the overall mechanical strength of the heating wire.

[0091] As can be seen from Examples 1-10 and Comparative Examples 1-8 and Table 1, the finished heating wires obtained by using the compounded anti-aging additives in this application have better resistance stability and heat resistance stability, and are easier to reduce the thermo-oxidative degradation of the resin during processing, thereby improving the overall high-temperature resistance stability, service life and mechanical strength.

[0092] Table 2: Time-temperature parameters of the finished heating wire in Example 1 at 110V voltage

[0093]

[0094] Table 3: Time-temperature parameters of the finished heating wire in Example 9 at 110V voltage

[0095]

[0096] Table 4: Time-temperature parameters of the finished heating wire in Example 10 at 36V voltage

[0097]

[0098] As can be seen from Examples 1 and 9-10 and Tables 2-4, the heating wire prepared in this application can be used at 36-110V and the steady-state temperature is controlled at 200℃, exhibiting excellent high-temperature stability.

[0099] Table 5: Test parameters of the finished heating wires in Examples 11-16 and Comparative Examples 9-14

[0100]

[0101]

[0102] As can be seen from Examples 11-16 and Comparative Examples 9-14, and Table 5, the conductive filler composition compounded in this application can impart good conductivity and high-temperature stability to the heating wire. The resistivity of the finished heating wire in this application is 0.5-50 Ω·cm. After 1000 cycles of heating test, the resistance change rate of the heating wire is less than 1.8% at 25°C and less than 3.5% at 200°C.

[0103] As can be seen from Examples 11-16 and Comparative Examples 9-14 and Table 2, the finished heating wire obtained by using the surface modifier in this application has better resistance stability and makes the conductive filler composition uniformly dispersed, thus ensuring the overall mechanical strength of the heating wire.

[0104] As can be seen from Examples 11-16 and Comparative Examples 9-14 and Table 2, the finished heating wires obtained by using the anti-aging additives in this application have better resistance stability and heat resistance stability, and are easier to reduce the thermo-oxidative degradation of the resin during processing, thereby improving the overall high-temperature stability, service life and mechanical strength.

[0105] Table 6: Time-Temperature Parameters of the Finished Heating Wire in Example 16 at 72V Voltage

[0106]

[0107] In summary, the heating wire prepared in this application can be used stably from -40 to 200°C, and after 1000 cycles of heating test, the resistance change rate of the heating wire is less than 3% at 25°C and less than 5% at 200°C.

[0108] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-temperature resistant and stable heating wire, characterized in that: The device comprises a core wire and a high-temperature resistant electrothermal composite layer covering the outer wall of the core wire. The high-temperature resistant electrothermal composite layer is coated with an insulating layer. The thickness of the high-temperature resistant electrothermal composite layer is 50-1500 μm. The resistivity of the high-temperature resistant electrothermal composite layer is 0.5-50 Ω·cm. The high-temperature resistant electrothermal composite layer is made of the following raw materials in the indicated weight percentages: 20-40 wt% conductive filler composition, 1.2-1.8 wt% surface modifier, 0.6-1.2 wt% aging resistant agent, 4-8 wt% dibutyl phthalate (DBP), and the balance being polyvinylidene fluoride (PVDF). The surface modifier is composed of at least one of 3-propyl isocyanatetriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane combined with titanate coupling agent HY-201. The conductive filler composition is made from the following raw materials in the indicated weight percentages: 5-20 wt% flake graphite, 20-40 wt% nano-barium titanate, 1-5 wt% titanium diboride whiskers, 3-8 wt% titanium nitride, 5-20 wt% molybdenum disilicide nanosheets, 0-5 wt% graphene, and the balance being microcrystalline graphite. The anti-aging additive is composed of silicon nitride combined with antioxidant 1010, antioxidant 168 and UV stabilizer 326.

2. The high-temperature resistant and stable heating wire according to claim 1, characterized in that: The conductive filler composition is made from the following raw materials in the indicated weight percentages: 10-12 wt% flake graphite, 32-36 wt% nano-barium titanate, 2-4 wt% titanium diboride whiskers, 5-6 wt% titanium nitride, 10-15 wt% molybdenum disilicide nanosheets, 0.5-2 wt% graphene, with the balance being microcrystalline graphite.

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