Preparation method of flame-retardant magnetic wire and wire

Abstract

The application discloses a preparation method of a flame-retardant magnetic attraction wire rod and the wire rod, and relates to the technical field of wire rods. The wire rod is prepared by the following steps: mixing rare earth iron-nitrogen (R-Fe-N) magnetic powder with ferrite magnetic powder, adding an elastic base material and a flame retardant, and then mixing the flame-retardant magnetic attraction layer material obtained through the mixing with a wire core to be extruded and formed together, and then magnetizing the wire rod to obtain the wire rod.

Description

Technical Field

[0001] This invention relates to the field of wire and its preparation technology, specifically to a wire with magnetic adsorption function and flame retardant effect, which can be used to prepare data cables, power cables, signal cables and other fields. Background Technology

[0002] Cables, including data cables, signal cables, and power cords, are widely used in home appliances and consumer electronics. For ease of use, cables used in consumer electronics and home appliances must have a certain length, typically 0.9m or more. Convenient storage is a common problem with traditional cables.

[0003] Flexible bonded magnets, made from polymers such as magnetic materials and elastomers, generate magnetic fields in their orientation and / or magnetization directions, leading to magnetic attraction between opposite poles. Utilizing these properties of magnetic materials, incorporating these flexible bonded magnets into wire structures makes it possible to conveniently store wires using magnetic attraction. With increasingly stringent material safety and environmental protection requirements worldwide, low-smoke flame retardancy, especially halogen-free low-smoke flame retardancy, has become a mandatory requirement for wires, particularly in the home appliance and consumer electronics sectors. Therefore, wires with magnetic adsorption capabilities should also possess flame-retardant properties.

[0004] Currently, existing technologies disclose some technical solutions for magnetically attracted cables. Invention patent CN 113674921B, entitled "A Method for Preparing a Magnetically Attractable Automatically Curled and Freely Stretched Data Cable," discloses a magnetically attracted cable whose structure includes a central flexible permanent magnet coating layer. This coating layer is a flexible coating layer made of a modified polymer composite material of permanent magnet samarium iron nitrogen (SMR) magnetic powder, binder, and additives. The median particle size D50 of the SMR magnetic powder is 1–5 μm for anisotropic SMR magnetic powder and 5–50 μm for isotropic SMR magnetic powder. The weight percentage of the permanent magnet coating layer is: 85–93% permanent magnet magnetic material powder, 7–16% binder, and 0–5% processing aids. The permanent magnet coating produced by this patented method lacks flame-retardant properties. Instead, it proposes adding flame retardants to the outer sheath of the wire. According to current flame-retardant testing standards, this is clearly difficult, if not impossible, to achieve an overall flame-retardant effect for the wire, failing to meet safety standards in various countries. Furthermore, the anisotropic samarium iron nitride (SMR) magnetic powder used in this patent has a D50 particle size of 1–5 μm. However, when the D50 of the anisotropic SMR magnetic powder is greater than 3 μm, its magnetic properties are low, resulting in weak magnetic attraction and poor mechanical properties in the wire. Moreover, the magnetic layer in this patent uses only SMR magnetic powder, which is not conducive to achieving an optimal combination of flame-retardant, magnetic attraction, and mechanical properties. Furthermore, this patent does not achieve halogen-free operation, failing to meet the environmental requirements of some countries.

[0005] Utility model patent CN 217036223 U – Data Cable – discloses a data cable in which the inner sheath material includes samarium iron nitride (SMR), and a temperature-resistant shielding layer is set on both the inner and outer sides of the inner sheath as a method to solve the problem that SMR is easily oxidized and burned, resulting in poor overall flame retardancy of the cable. It is evident that the inner sheath material using SMR in this patent has no flame-retardant function and does not contain flame-retardant materials. Furthermore, it does not mention halogen-free.

[0006] For cables, especially data cables and charging cables, flame retardancy is a mandatory legal requirement in many countries. Magnetic powder materials, particularly anisotropic samarium iron nitrogen magnetic powder, are submicron particle size magnetic powders, based on their molecular formula (Sm2Fe2O3). 17 Nitrogen oxides (N3) have a high iron content and are inherently flammable. To ensure both magnetic effectiveness and mechanical properties, excessive flame retardants cannot be added. Therefore, achieving flame retardancy in magnetic wires is a crucial challenge that must be addressed. Summary of the Invention

[0007] The purpose of this invention is to provide a wire with magnetic adsorption and flame retardant functions and its preparation method, so as to realize convenient storage of data cables, signal cables, power cables and other cables.

[0008] The first aspect of the present invention provides a method for preparing a flame-retardant magnetic wire, wherein the flame-retardant magnetic wire is provided from the inside out with a wire core, a middle sheath layer and an optional outer sheath layer, wherein the middle sheath layer is a flame-retardant magnetic layer, and the method for preparing the wire includes:

[0009] (1) The wire core and the flame-retardant magnetic layer material are extruded together to obtain a wire core covered with a flame-retardant magnetic layer. The flame-retardant magnetic layer material includes an elastic substrate, a magnetic material and a flame retardant; wherein the magnetic material includes rare earth iron nitrogen magnetic powder, and further, the magnetic material includes rare earth iron nitrogen magnetic powder and ferrite magnetic powder.

[0010] Optionally, an outer sheath is prepared on the outside of the wire core covered by the obtained flame-retardant magnetic layer;

[0011] (2) Shape the wire obtained in step (1);

[0012] (3) Magnetize the wire obtained in step (2) to obtain the flame-retardant magnetic wire;

[0013] Furthermore, in the flame-retardant magnetic layer material, the content of the elastic substrate is 15wt% to 25wt%, the content of the magnetic material is 55wt% to 75wt%, and the content of the flame retardant is 5wt% to 15wt%.

[0014] According to the method of the first aspect, wherein the rare earth iron-nitrogen magnetic powder is samarium iron-nitrogen magnetic powder and / or neodymium iron-nitrogen magnetic powder;

[0015] Further, the D50 of the samarium iron nitrogen magnetic powder is 1.9–3 μm, the D50 of the neodymium iron nitrogen magnetic powder is 1.5–1.9 μm, and the D50 of the ferrite magnetic powder is 1.5–1.8 μm; and / or

[0016] Furthermore, the samarium iron nitrogen magnetic powder, neodymium iron nitrogen magnetic powder and / or the ferrite magnetic powder are anisotropic;

[0017] Furthermore, in the magnetic material, the mass ratio of rare earth iron nitride magnetic powder to ferrite magnetic powder is (0.5-1):(0-0.5), and even further, the mass ratio of rare earth iron nitride magnetic powder to ferrite magnetic powder is (0.5-0.9):(0.1-0.5).

[0018] According to the method of the first aspect, in step (1), during the extrusion molding, the extruder head adopts permanent magnet orientation or electromagnetic orientation;

[0019] Furthermore, the orientation field of the permanent magnet orientation is 8000–13000 Oe; or

[0020] Furthermore, the orientation field of the electromagnetic orientation is ≥13000 Oe.

[0021] According to the method of the first aspect, the elastic substrate in the flame-retardant magnetic layer material is:

[0022] Polyvinyl chloride (PVC), further, the hardness of the polyvinyl chloride (PVC) is 40 to 100A;

[0023] Silicone rubber, further, wherein the hardness of the silicone rubber is 40-70A; or

[0024] The thermoplastic elastomer, further, has a melting point of 80–200°C; the thermoplastic elastomer, further, is one or more of the following: styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, diene-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, urethane-based thermoplastic elastomers (TPU), polyester-based thermoplastic elastomers (TPEE), polyamide-based thermoplastic elastomers (TPAE), thermoplastic elastomer-based thermoplastic resins (EEA), thermoplastic vulcanized rubbers (TPV), and silicone-based thermoplastic elastomers; and even further, the thermoplastic elastomer is one or more of halogen-free materials among TPEE, TPU, TPV, and TPAE.

[0025] According to the method of the first aspect, the flame retardant in the flame-retardant magnetic layer material is selected from organic flame retardants and / or inorganic flame retardants, preferably halogen-free flame retardants;

[0026] Furthermore, the flame-retardant magnetic layer material also includes processing aids, which include one or more of coupling agents, plasticizers, toughening agents, lubricants, and antioxidants.

[0027] According to the method of the first aspect, in step (1), the magnetic material is surface modified by a coupling agent;

[0028] Furthermore, the coupling agent is a silane coupling agent or a titanane coupling agent;

[0029] Furthermore, the magnetic material is modified at 80–150°C using a coupling agent comprising 0.2–2 wt% of the total weight of the magnetic material.

[0030] According to the method of the first aspect, in step (1), the outer layer material is selected from one or more of woven materials, TPU, TPEE, TPV, and silicone rubber;

[0031] Furthermore, the braiding material is a flame-retardant braiding material;

[0032] Furthermore, the weaving material is one or more of flame-retardant nylon, flame-retardant aramid, and flame-retardant aramid.

[0033] According to the method of the first aspect, in step (1), the material is extruded by a single screw wire extruder and a permanent magnet orientation extruder head;

[0034] Furthermore, the extrusion speed is ≥30 m / s;

[0035] Furthermore, when the elastic substrate is silicone rubber, the extruder and die are at room temperature;

[0036] Furthermore, the elastic substrate is a thermoplastic elastomer, and the screw temperature in each section of the extruder is 100–200°C; and / or

[0037] Furthermore, when the elastic substrate is a thermoplastic elastomer, the extruder die temperature is 120–200°C.

[0038] According to the method of the first aspect, in step (2), when the elastic substrate is a thermoplastic elastomer, it is baked at 200-300°C for shaping;

[0039] In step (2), when the elastic substrate is silicone rubber, it is vulcanized and shaped through a heating channel at a temperature of 200–400°C; and / or

[0040] In step (3), the wire is magnetized in a coiled state using a spiral coil magnetizing device with a magnetic field of 35000kOe or more, or in a flat state using a grooved magnetizing device.

[0041] A second aspect of the present invention provides a flame-retardant magnetic wick, said wick being prepared by the method of the first aspect;

[0042] Furthermore, the Shore hardness of the wire is ≤90A;

[0043] Furthermore, the flame retardancy rating of the wire meets VW-1;

[0044] Furthermore, the wire is halogen-free; and / or

[0045] Furthermore, the surface magnetic field strength of the wire in the magnetization direction is above 500 Gs.

[0046] According to the flame-retardant magnetic wire of the second aspect, the thickness of the middle sheath of the wire is 0.3 to 2 mm, preferably 0.3 to 1 mm, and / or the thickness of the outer sheath of the wire is ≤1 mm, preferably ≤0.3 mm;

[0047] Furthermore, the wire core comprises one or more individual conductors covered with an insulation layer;

[0048] Furthermore, the wire core is also provided with fiber material, which is selected from one or more of glass fiber, basalt fiber, and aramid fiber;

[0049] Furthermore, a shielding layer is provided between the wire core and the inner sheath of the wire, and the shielding layer wraps the conductor and fiber material.

[0050] The method for preparing the flame-retardant magnetic wire of the present invention has, but is not limited to, the following beneficial effects:

[0051] The preparation method of this invention utilizes anisotropic rare-earth iron-nitrogen magnetic powder, further compounding the rare-earth iron-nitrogen magnetic powder with ferrite magnetic powder, and extruding the wire using a die head with magnetic field orientation function. This eliminates the need for a temperature-resistant shielding layer, achieving the wire preparation scheme with the least amount of flame retardant, the highest magnetic attraction performance, and the best mechanical properties currently available. The prepared wire possesses good flexibility, as well as excellent tear and tensile strength. It maintains excellent flame retardant properties while reducing the amount of flame retardant added, and simultaneously achieves high magnetic properties. Attached Figure Description

[0052] Figure 1 A cross-sectional schematic diagram of the flame-retardant magnetic wire (without shielding layer) of the present invention is shown.

[0053] Figure 2 A cross-sectional schematic diagram of the flame-retardant magnetic wire (with shielding layer) of the present invention is shown.

[0054] Figure 3A schematic diagram of the extruder head magnetic field orientation device (permanent magnet orientation) of the extrusion mechanism of the present invention is shown.

[0055] Figure 4 A cross-sectional schematic diagram of the extruder head magnetic field orientation device (permanent magnet orientation) of the extrusion mechanism of the present invention is shown.

[0056] Figure 5 A schematic diagram of the extruder head magnetic field orientation device (electromagnetic orientation) of the present invention is shown.

[0057] Figure 6 A schematic diagram of a magnetization scheme for the flame-retardant magnetic wire of the present invention is shown.

[0058] Figure 7 A schematic diagram illustrating the storage effect of the flame-retardant magnetic wire of the present invention is shown.

[0059] Explanation of reference numerals in the attached figures:

[0060] 1. Core wire; 11. Conductor wire; 2. Middle sheath; 3. Outer sheath; 4. Shielding layer; 5. Magnetic field orientation device; 51. Magnetic conductor; 52. Permanent magnet; 53. Outlet port; 54. Extrusion channel; 55. Magnetic field core mold; 6. Electromagnet; 61. Magnetic pole head; 62. Soft iron pole; 63. Yoke; 64. Coil; 7. Solenoid cylinder; 8. Wire to be magnetized; 9. Magnetizer; 10. Fixture. Detailed Implementation

[0061] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0062] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0063] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0064] This invention provides a method for preparing a flame-retardant magnetic wire, wherein the flame-retardant magnetic wire comprises, from the inside out, a wire core, a middle sheath layer, and an optional outer sheath layer, wherein the middle sheath layer is a flame-retardant magnetic layer, and the method for preparing the wire includes:

[0065] (1) The wire core and the flame-retardant magnetic layer material are extruded together to obtain a wire core covered with a flame-retardant magnetic layer. The flame-retardant magnetic layer material includes an elastic substrate, a magnetic material and a flame retardant; wherein the magnetic material includes rare earth iron nitrogen magnetic powder, and further, the magnetic material includes rare earth iron nitrogen magnetic powder and ferrite magnetic powder.

[0066] Optionally, an outer sheath is prepared on the outside of the wire core covered by the obtained flame-retardant magnetic layer;

[0067] (2) Shape the wire obtained in step (1);

[0068] (3) Magnetize the wire obtained in step (2) to obtain the flame-retardant magnetic wire;

[0069] Furthermore, in the flame-retardant magnetic layer material, the content of the elastic substrate is 15wt% to 25wt%, the content of the magnetic material is 55wt% to 75wt%, and the content of the flame retardant is 5wt% to 15wt%.

[0070] In a preferred embodiment, the content of the elastic substrate is 15wt% to 20wt%, the content of the magnetic material is 65wt% to 75wt%, and the content of the flame retardant is 5wt% to 10wt%.

[0071] Rare earth iron-nitrogen (R-Fe-N) materials are a class of permanent magnet materials containing rare earth elements, possessing R... a Fe b N c The chemical formula is given, where R is a rare earth element selected from one or more of samarium (Sm), neodymium (Nd), lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), europium (Eu), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), yttrium (Y), and scandium (Sc), and a, b, and c are non-zero natural numbers. The rare earth iron-nitrogen magnetic powder described in this invention can be samarium iron-nitrogen magnetic powder, neodymium iron-nitrogen magnetic powder, etc. Among them, samarium iron-nitrogen can be Th₂Zn 17 Sm2Fe with rhombohedral crystal structure 17 N x Neodymium iron nitrogen can be used to produce ThMn 12 NdFe3O4 with a tetragonal crystal structure 12 N x Compared with rare earth permanent magnet materials such as samarium cobalt and neodymium iron boron, rare earth iron nitrogen has better magnetic properties and good particle size characteristics, as well as excellent oxidation and corrosion resistance.

[0072] To achieve good flame retardant effects, a common method in existing technologies is to increase the use of flame retardants in composite materials. However, in the field of magnetic wires, adding too many flame retardants not only fails to maintain the flexibility and toughness of the material, but also significantly reduces its magnetic performance. In the technical solution of this invention, by further adding ferrite magnetic powder, not only can the reduction in magnetic performance be reduced, but also, due to the oxide properties of the ferrite magnetic powder itself, it is beneficial to achieve flame retardant performance with less added flame retardant. In one embodiment, the rare earth iron-nitrogen magnetic powder is samarium iron-nitrogen magnetic powder and / or neodymium iron-nitrogen magnetic powder;

[0073] Further, the D50 of the samarium iron nitrogen magnetic powder is 1.9–3 μm, the D50 of the neodymium iron nitrogen magnetic powder is 1.5–1.9 μm, and the D50 of the ferrite magnetic powder is 1.5–1.8 μm; and / or

[0074] Furthermore, the samarium iron nitrogen magnetic powder, neodymium iron nitrogen magnetic powder and / or the ferrite magnetic powder are anisotropic;

[0075] Furthermore, in the magnetic material, the mass ratio of rare earth iron nitride magnetic powder to ferrite magnetic powder is (0.5-1):(0-0.5), and even further, the mass ratio of rare earth iron nitride magnetic powder to ferrite magnetic powder is (0.5-0.9):(0.1-0.5).

[0076] The magnetic material of this invention can be selected from isotropic or anisotropic magnetic powders. More specifically, the magnetic material powder is anisotropic samarium iron nitrogen powder with a D50 of 1.9–3 μm and / or anisotropic neodymium iron nitrogen powder with a D50 of 1.5–1.9 μm. Furthermore, it is compounded with anisotropic ferrite magnetic powder to achieve flame retardancy and enhanced magnetic properties. Under oriented conditions, the anisotropic rare earth iron nitrogen powder can achieve high magnetic properties not currently available in other magnetic powder materials on the market. Simultaneously, based on the characteristics of nitrides, it possesses excellent corrosion resistance, rust prevention, aging resistance, and oxidation resistance. In addition, based on the particle size characteristics of samarium iron nitrogen magnetic powder (D50 between 1.9–3 μm), neodymium iron nitrogen magnetic powder (D50 between 1.5–1.9 μm), and ferrite magnetic powder (D50 between 1.5–1.8 μm), it can be well combined with common elastomer materials, resulting in wires with good flexibility as well as good tear and tensile strength. When the D50 of anisotropic rare earth iron-nitrogen magnetic powder is too large (>3μm), the magnetic properties of the anisotropic rare earth iron-nitrogen magnetic powder are low, the magnetic attraction of the wires made from it is not high, and the mechanical properties are poor.

[0077] In one embodiment, the mass ratio of rare earth iron-nitrogen magnetic powder to ferrite magnetic powder in the magnetic material is (0.5-1):(0-0.5). By adjusting the appropriate ratio of magnetic powder to flame retardant in the flame-retardant magnetic layer, the resulting wire simultaneously possesses excellent magnetic attraction, flame retardant properties, and mechanical properties. In a specific embodiment, the mass ratio of rare earth iron-nitrogen to ferrite magnetic powder in the magnetic powder is (0.5-0.9):(0.1-0.5). When the content of ferrite magnetic powder is too high, the magnetic properties of the resulting intermediate layer are too low, failing to meet the wire's requirements for magnetic attraction.

[0078] In one embodiment, during step (1), the extrusion head adopts permanent magnet orientation or electromagnetic orientation during the extrusion molding process;

[0079] Furthermore, the orientation field of the permanent magnet orientation is 8000–13000 Oe; or

[0080] Furthermore, the orientation field of the electromagnetic orientation is ≥13000 Oe.

[0081] In one embodiment, the elastic substrate in the flame-retardant magnetic layer material is:

[0082] Polyvinyl chloride (PVC), further, the hardness of the polyvinyl chloride (PVC) is 40 to 100A;

[0083] Silicone rubber, further, wherein the hardness of the silicone rubber is 40-70A; or

[0084] The thermoplastic elastomer, further, has a melting point of 80–200°C; the thermoplastic elastomer, even further, is one or more of the following: styrene-based thermoplastic elastomers (SBS, SIS, SEBS, SEPS), olefin-based thermoplastic elastomers (TPO, TPV), diene-based thermoplastic elastomers (TPB, TPI), vinyl chloride-based thermoplastic elastomers (TPVC, TCPE), urethane-based thermoplastic elastomers (TPU), polyester-based thermoplastic elastomers (TPEE), polyamide-based thermoplastic elastomers (TPAE), thermoplastic elastomer resins (EEA, Ethylene Ethyl Acrylate copolymer), thermoplastic vulcanizate (TPV), and silicone-based thermoplastic elastomers; and still further, the thermoplastic elastomer is one or more of the following halogen-free materials: TPEE, TPU, TPV, and TPAE.

[0085] In one embodiment, the flame retardant in the flame-retardant magnetic layer material is selected from organic flame retardants and / or inorganic flame retardants, preferably halogen-free flame retardants;

[0086] Furthermore, the flame-retardant magnetic layer material also includes processing aids, which include one or more of coupling agents, plasticizers, toughening agents, lubricants, and antioxidants.

[0087] The elastic substrate can be selected from one or more of PVC, silicone rubber, and thermoplastic elastomers. The PVC has a hardness of 40–100 A, for example, 40 A, 50 A, 60 A, 70 A, 80 A, 90 A, or 100 A. The silicone rubber has a hardness of 40–70 A, for example, 40 A, 50 A, 60 A, or 70 A. The thermoplastic elastomer is preferably a material with a melting point between 80 and 200 degrees Celsius, for example, melting points of 80°C, 100°C, 120°C, 150°C, 180°C, or 200°C. Using these elastomers can achieve the following effects: the material has good flexibility and good molding flowability, is halogen-free, and meets safety and environmental protection standards. If the selected thermoplastic elastomer has a too low melting point, the resulting wire will have poor mechanical properties; if the selected thermoplastic elastomer has a too high melting point, the high temperature during processing will lead to a reduction in magnetic properties, and the resulting wire will not achieve high magnetic properties.

[0088] The flame retardant of the present invention can be an organic flame retardant or an inorganic flame retardant. Organic flame retardants include, but are not limited to, flame retardants with bromine-based, chlorine-based, phosphorus-nitrogen-based, nitrogen-based, and red phosphorus and their compounds as main components. Inorganic flame retardants include, but are not limited to, flame retardants with antimony trioxide, magnesium hydroxide, aluminum hydroxide, etc., as main components. The flame retardant may contain halogens or not, preferably halogen-free flame retardants.

[0089] Coupling agents, plasticizers, toughening agents, and lubricants in processing aids can be made from conventional materials and can be selected according to requirements.

[0090] In one embodiment, in step (1), the magnetic material is surface modified by a coupling agent;

[0091] Furthermore, the coupling agent is a silane coupling agent or a titanane coupling agent;

[0092] Furthermore, the magnetic material is modified at 80–150°C using a coupling agent comprising 0.2–2 wt% of the total weight of the magnetic material.

[0093] In one specific embodiment, the magnetic material is surface modified by mixing and stirring with 0.5 to 2 wt% of a coupling agent at a temperature between 80°C and 150°C and then drying.

[0094] This invention utilizes coupling agents to modify the surface of magnetic materials, thereby increasing the flowability of magnetic material powder and improving its bonding effect with elastomer materials, ensuring the orientation effect of magnetic materials in magnetic fields and the flexibility of the materials.

[0095] In one specific embodiment, the flame-retardant magnetic layer material is prepared as granules before the preparation of the intermediate layer.

[0096] In one embodiment, in step (1), the outer layer material is selected from one or more of woven materials, TPU, TPEE, TPV, and silicone rubber. Further, the woven material is a flame-retardant woven material. Even further, the woven material is one or more of flame-retardant nylon, flame-retardant aramid, and flame-retardant aramid.

[0097] In one embodiment, in step (1), the wire rod is extruded using a single screw wire extruder and a permanent magnet orientation extruder head;

[0098] Furthermore, the extrusion speed is ≥30 m / s;

[0099] Furthermore, when the elastic substrate is silicone rubber, the extruder and die are at room temperature;

[0100] Furthermore, when the elastic substrate is a thermoplastic elastomer, the screw temperature in each section of the extruder is 100–200°C; and / or

[0101] Furthermore, when the elastic substrate is a thermoplastic elastomer, the extruder die temperature is 120–200°C.

[0102] When the temperature of the extruder die head is too high, it may cause high-temperature demagnetization.

[0103] In one embodiment, in step (2), when the elastic substrate is a thermoplastic elastomer, it is baked at 200-300°C for shaping;

[0104] In step (2), when the elastic substrate is silicone rubber, it is vulcanized and shaped through a heating channel at a temperature of 200–400°C; and / or

[0105] In step (3), the wire is magnetized in a coiled state using a spiral coil magnetizing device with a magnetic field of 35000kOe or more, or in a flat state using a grooved magnetizing device.

[0106] The present invention also provides a flame-retardant magnetic wick, which is prepared by the aforementioned method;

[0107] Furthermore, the Shore A hardness of the wire is ≤90A, that is, the Shore A hardness of the wire of the present invention does not exceed 90 degrees.

[0108] Furthermore, the flame retardant rating of the wire reaches VW-1;

[0109] Furthermore, the wire is halogen-free; and / or

[0110] Furthermore, the surface magnetic field strength of the wire in the magnetization direction is above 500 Gs.

[0111] In one embodiment, the thickness of the middle sheath of the wire is 0.3 to 1 mm, and / or the thickness of the outer sheath of the wire is ≤0.3 mm;

[0112] Furthermore, the wire core comprises one or more individual conductors covered with an insulation layer;

[0113] Furthermore, the wire core is also provided with fiber material, which is selected from one or more of glass fiber, basalt fiber, and aramid fiber;

[0114] Furthermore, a shielding layer is provided between the wire core and the inner sheath of the wire, and the shielding layer wraps the conductor and fiber material.

[0115] The flame-retardant magnetic wire prepared by this invention consists of a core, a middle sheath, and an outer sheath from the inside out.

[0116] The conductor consists of one or more individually insulated wires, which can be twisted or arranged in parallel. Fiber materials such as glass fiber, basalt fiber, and aramid can be added inside the conductor to enhance tensile strength and heat dissipation. The conductor and fibers can be wrapped with materials such as aluminum foil as a shielding layer.

[0117] The middle layer is a flame-retardant magnetic layer, prepared from an elastic substrate, magnetic material powder, flame retardant, and at least one of coupling agent, plasticizer, toughening agent, lubricant, and antioxidant, preferably a halogen-free material. The thickness of the middle layer is preferably 0.3–1 mm.

[0118] The outer layer can be wrapped with woven materials (preferably flame-retardant woven materials, including but not limited to flame-retardant nylon, flame-retardant aramid, etc.), TPU, TPEE, TPV, silicone rubber, etc. If woven materials are used, adhesive can also be applied directly to the weave. The thickness of the outer layer is preferably no more than 0.3mm, and halogen-free outer layer materials are preferred.

[0119] Figure 1 A cross-sectional schematic diagram of the wire of the present invention is shown, showing a wire core 1, a middle sheath 2, and an outer sheath 3 arranged sequentially from the inside out. The wire core 1 contains multiple conductors 11, and the interior of the wire core may include fibrous material to improve the mechanical properties and heat dissipation performance of the wire. Figure 2 As shown, a shielding layer 4 can be wrapped around the outside of the wire core.

[0120] After preparation, the outer diameter of the wire is preferably no more than 5 mm (thickness / width / diameter), the Shore hardness is ≤90A, and the flame retardancy rating of the wire reaches VW-1.

[0121] In one specific embodiment, the preparation method includes:

[0122] Mix in the following proportions:

[0123] 55wt%-75wt% magnetic powder,

[0124] 15wt%-25wt% elastomer material,

[0125] 10wt%-30wt% of processing aids, including 5wt%-15wt% of flame retardant.

[0126] Magnetic granules were prepared using a twin-screw extruder, with the screw temperature in each section ranging from 100 to 200°C.

[0127] Flame-retardant magnetic wire is extruded using a single-screw wire extruder through an extruder head with magnetic field orientation function. The wire cross-sectional shape is circular, oval, or rectangular, and the extrusion speed is ≥30 m / s. The screw temperature of each section of the extruder is 100-200℃, and the die temperature is 120-200℃. The extruder head uses permanent magnet orientation or electromagnetic orientation. With permanent magnet orientation, the orientation field can reach 8000-13000 Oe; with electromagnetic orientation, the orientation field is ≥13000 Oe.

[0128] Figure 3 A schematic diagram of the extruder head magnetic field orientation device (permanent magnet orientation) of the extrusion mechanism of the present invention is shown. Figure 4 A cross-sectional schematic diagram of the magnetic field orientation device (permanent magnet orientation) is shown. The magnetic field orientation device 5 includes two magnetic conductors 51 and two permanent magnets 52. The permanent magnets 52 are sandwiched between the two magnetic conductors 51, and are located on opposite sides of the extrusion channel 54. Magnetic lines of force generated between the two permanent magnets penetrate the extrusion channel 54, thereby oriented the molten flame-retardant magnetic material within the extrusion channel 54. The magnetic field core mold 55 guides the passage of the wire, allowing it to pass through more smoothly. Figure 5A schematic diagram of the extruder head magnetic field orientation device (electromagnetic orientation) of the present invention is shown, including an electromagnet 6 and a magnetic field mandrel (not shown). The N and S poles of the electromagnet 6 are arranged opposite each other, and there is a gap between the N and S poles. Specifically, the electromagnet 6 is a ring with a notch, so that the N and S poles of the electromagnet 6 are arranged opposite each other. Magnetic pole heads 61 are respectively connected to the N and S poles of the electromagnet 6. The magnetic pole heads 61 are trapezoidal to enhance the magnetic concentration effect. The upper ends of the two magnetic pole heads 61 are respectively a soft ferromagnetic pole 62 and a magnetic material (i.e., a yoke 63). The magnetic material is connected to form a magnetic field circuit. Coils 64 are placed on both sides of each magnetic pole, and the magnetic lines of force of the coils 64 on both sides of the same magnetic pole are in the same direction. When the outer layer is wrapped with materials such as TPU, TPEE, or TPV, after the aforementioned middle layer is extruded, the outer layer is extruded through a double-layer extrusion device. When the outer layer is wrapped with a braided material, the braided outer layer is prepared by a braiding device.

[0129] If necessary, the shape of the coiled wire can be initially shaped using baking equipment.

[0130] When using silicone or silicone rubber as the elastic substrate of the middle layer, after the magnetic powder has been surface modified, it can be mixed with magnetic powder, processing aids, and flame retardants in the aforementioned proportions, and vulcanizing agent can be added according to conventional processes. After being mixed evenly, the wire can be directly extruded at room temperature using a single screw extruder with magnetic field orientation function, and then vulcanized and shaped through a heating channel at a temperature of 200-400°C.

[0131] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of over 35000 kOe, and in a flat state using a grooved magnetization device. After preparation, the surface magnetic field strength of the wire in the magnetization direction is over 500 Gs.

[0132] Figure 6 This diagram illustrates a magnetization scheme for the flame-retardant magnetic wire of the present invention. The wire 8 to be magnetized is coiled around a solenoid cylinder 7, fixed by a clamp 10, and magnetized by a magnetizer 9. After magnetization, the magnetic field strength on the upper surface of the wire in the magnetization direction is above 500 Gs, thus enabling convenient storage. Figure 7 A schematic diagram illustrating the storage effect of the flame-retardant magnetic wire of the present invention is shown.

[0133] This invention does not impose any special restrictions on the source of any raw materials; unless otherwise specified, they are all conventional products that can be obtained commercially.

[0134] Samarium iron nitrogen magnetic powder was purchased from Ningxia Junci New Material Technology Co., Ltd.

[0135] Ferrite magnetic powder was purchased from Zhejiang Dongci Hutian Magnetic Industry Co., Ltd.

[0136] TPV, model 1190A-S0204, purchased from Gillespie, USA.

[0137] TPEE, model SHF 50A-3S1981, purchased from Gillespie, USA.

[0138] The TPU, model Elastollan SP1150A15P, was purchased from BASF.

[0139] Silicone rubber, model 107 room temperature vulcanizing silicone rubber, purchased from Jinan Yingyu Chemical Co., Ltd.

[0140] PVC, model S080 PR-640, purchased from Formosa Plastics Ningbo.

[0141] The wire cores in the following embodiments use halogen-free flame-retardant five-core wires with an outer insulation layer.

[0142] The ferrite magnetic powder used in the following examples is anisotropic.

[0143] Example 1

[0144] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.05 μm) and ferrite magnetic powder (D50 of 1.64 μm) were modified using KH550 silane coupling agent at 1.5 wt% of the magnetic powder weight. The modification process included dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding the magnetic powder, mixing and stirring at 110 °C using a Hensel mixer-dryer, and then drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0145] Magnetic granules were prepared by thoroughly mixing 45 wt% modified anisotropic samarium iron nitrogen magnetic powder, 20 wt% modified ferrite magnetic powder, 20 wt% TPV (melting point 170℃), 10 wt% phosphorus nitrogen-based halogen-free flame retardant KSW-03, and 5 wt% additives containing antioxidants and plasticizers (including 2 wt% antioxidant 1076 and 3 wt% plasticizer DEHP). The screw temperature of each section was 100-200℃.

[0146] A single-screw wire extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire with a permanent magnet orientation field of 12000 Oe. The wire diameter and cross-sectional shape were flat and round, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 150℃. The thickness of the inner coating was 0.6 mm.

[0147] Flame-retardant nylon woven outer quilts were prepared using weaving equipment, with an outer quilt layer thickness of 0.3 mm.

[0148] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0149] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0150] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional height of 4.6mm, a flat section width of 0.5mm, a cross-sectional width of 4.8mm, and a Shore hardness of 70A. After magnetization, the flat section has a measured magnetic field of 650Gs. The cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0151] Example 2

[0152] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.1 μm) and ferrite magnetic powder (D50 of 1.75 μm) were modified using KH550 silane coupling agent at 2 wt% of the magnetic powder weight, respectively. The modification process included: dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding magnetic powder, mixing and stirring at 130 °C using a Hensel mixer-dryer, and drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0153] Magnetic granules were prepared by thoroughly mixing 48 wt% modified anisotropic samarium iron nitrogen magnetic powder, 22 wt% modified ferrite magnetic powder, 20 wt% TPEE (melting point 150℃), 5 wt% aluminum hydroxide halogen-free flame retardant, and 5% additives containing antioxidants and toughening agents (including 2 wt% antioxidant 1076 and 3 wt% toughening agent DEHP). The screw temperature of each section was 100-200℃.

[0154] A single-screw wire extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire with an electromagnetic orientation field of 14000 Oe. The wire cross-section was circular, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 180℃. The thickness of the inner coating was 0.5 mm.

[0155] The outer layer is coated with halogen-free flame-retardant TPEE extruded using a double-layer extrusion device, with an outer layer thickness of 0.3 mm.

[0156] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0157] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0158] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional diameter of 4.4mm, and a Shore hardness of 80A. After magnetization, the flat section has a measured magnetic field of 750Gs. The finished cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0159] Example 3

[0160] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.3 μm) and ferrite magnetic powder (D50 of 1.68 μm) were modified using KH550 silane coupling agent at 0.5 wt% of the magnetic powder weight. The modification process included dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration of 20 wt%), adding the magnetic powder, mixing and stirring at 80 °C using a Hensel mixer-dryer, and drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0161] Magnetic granules were prepared by thoroughly mixing 48 wt% modified anisotropic samarium iron nitrogen magnetic powder, 25 wt% modified ferrite magnetic powder, 15 wt% TPU (melting point 200℃), 7 wt% magnesium hydroxide halogen-free flame retardant, and 5 wt% additives containing antioxidants, toughening agents, and lubricants (including 2 wt% antioxidant 1076, 2 wt% toughening agent DEHP, and 1 wt% lubricant PMX-200). The screw temperature of each section was 100-200℃.

[0162] A single-screw wire rod extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire rod with an electromagnetic orientation field of 14000 Oe. The wire rod had a square cross-sectional shape, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 180℃. The thickness of the inner coating layer was 0.8 mm.

[0163] Flame-retardant aramid woven outer coverings were prepared using weaving equipment, with an outer covering layer thickness of 0.3 mm.

[0164] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0165] Magnetization was performed by laying the wire flat along its height using a trench magnetization device with a magnetic field of 35000kOe and an extremely wide spacing of 10mm.

[0166] The aforementioned magnetic data cable has its cores laid flat, with a width of 4mm and a height of 1.5mm. The finished cable cross-section has a width of 5mm and a height of 3.7mm, with a Shore hardness of 90A. After magnetization, the magnetic field strength measured in the height direction is 850Gs. The finished cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0167] Example 4

[0168] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.78 μm) and ferrite magnetic powder (D50 of 1.73 μm) were modified using KH550 silane coupling agent at 1.3 wt% of the magnetic powder weight, respectively. The modification process included: dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding magnetic powder, mixing and stirring at 110 °C using a Hensel mixing dryer, and drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0169] 45 wt% modified anisotropic samarium iron nitrogen magnetic powder, 20% modified ferrite magnetic powder, 20% silicone rubber, 10% phosphorus-nitrogen flame retardant KSW-03, and 4.5% additives containing antioxidants and plasticizers (including 2 wt% antioxidant 1076 and 2.5 wt% plasticizer DEHP) were thoroughly mixed, and 0.5 wt% vulcanizing agent TMTD was added. The mixture was thoroughly mixed at room temperature using an internal mixer. A single-screw wire rod extruder was used, with a permanent magnet orientation die head at an orientation field of 12000 Oe, to extrude and coat a flame-retardant magnetic wire with a flattened oval cross-section. The extrusion speed was 30 m / s. The extruder screw and die were not heated. The thickness of the inner coating was 0.8 mm. After extrusion, the wire rod was vulcanized and set in a 300℃ heated channel.

[0170] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0171] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional height of 4.4mm, a flat section width of 0.5mm, a cross-sectional width of 4.6mm, and a Shore hardness of 70A. After magnetization, the flat section has a measured magnetic field of 700Gs. The cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0172] Example 5

[0173] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.53 μm) and ferrite magnetic powder (D50 of 1.65 μm) were modified using KH550 silane coupling agent at 1.5 wt% of the magnetic powder weight. The modification process included dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding the magnetic powder, mixing and stirring at 130 °C using a Hensel mixer-dryer, and then drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0174] Magnetic granules were prepared by thoroughly mixing 48 wt% modified anisotropic samarium iron nitrogen magnetic powder, 22 wt% modified ferrite magnetic powder, 15 wt% TPEE (melting point 150℃), 5 wt% PVC (melting point 200℃), 5 wt% aluminum hydroxide halogen-free flame retardant, and 5% additives containing antioxidants and toughening agents (including 2 wt% antioxidant 1076 and 3 wt% toughening agent DEHP). The screw temperature of each section was 100-200℃.

[0175] A single-screw wire rod extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire rod with an electromagnetic orientation field of 14000 Oe. The wire rod had a circular cross-sectional shape, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 180℃. The thickness of the inner coating layer was 0.6 mm.

[0176] The outer layer is coated with halogen-free flame-retardant TPEE extruded using a double-layer extrusion device, with an outer layer thickness of 0.3 mm.

[0177] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0178] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0179] The aforementioned magnetic data cable has a core diameter of 3.0mm, a finished cross-sectional diameter of 4.6mm, and a Shore hardness of 90A. After magnetization, the flat section has a measured magnetic field of 800Gs. The finished cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0180] Example 6

[0181] Anisotropic samarium iron nitrogen magnetic powder (D50 of 1.95 μm) was modified using KH550 silane coupling agent at 2 wt% of the magnetic powder weight. The modification process included: dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding the magnetic powder, mixing and stirring at 110 °C using a Hensel mixer-dryer, and drying to obtain modified anisotropic samarium iron nitrogen magnetic powder.

[0182] 55 wt% modified anisotropic samarium iron nitrogen magnetic powder, 20 wt% TPV (melting point 170℃), 20 wt% phosphorus nitrogen-based halogen-free flame retardant KSW-03, and 5 wt% additives containing antioxidants and plasticizers (including 2 wt% antioxidant 1076 and 3 wt% plasticizer DEHP) were thoroughly mixed and magnetic granules were prepared using a twin-screw extruder with the screw temperature of each section being 100-200℃.

[0183] A single-screw wire extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire with a permanent magnet orientation field of 12000 Oe. The wire diameter and cross-sectional shape were flat and round, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 150℃. The thickness of the inner coating was 0.6 mm.

[0184] Flame-retardant nylon woven outer quilts were prepared using weaving equipment, with an outer quilt layer thickness of 0.3 mm.

[0185] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0186] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0187] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional height of 4.6mm, a flat section width of 0.5mm, a cross-sectional width of 4.8mm, and a Shore hardness of 65A. After magnetization, the flat section has a measured magnetic field of 700Gs. The cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0188] Example 7

[0189] Anisotropic samarium iron nitrogen magnetic powder (D50 of 2.15 μm) and ferrite magnetic powder (D50 of 1.70 μm) were modified using KH550 silane coupling agent at 0.5 wt% of the magnetic powder weight. The modification process included dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration of 20 wt%), adding the magnetic powder, mixing and stirring at 110 °C using a Hensel mixer-dryer, and then drying to obtain modified anisotropic samarium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0190] 35 wt% of modified anisotropic samarium iron nitrogen magnetic powder, 35 wt% of modified ferrite magnetic powder, 20 wt% of TPV (melting point 170℃), 5 wt% of phosphorus nitrogen-based halogen-free flame retardant KSW-03, and 5 wt% of additives containing antioxidants and plasticizers (including 2 wt% antioxidant 1076 and 3 wt% plasticizer DEHP) were thoroughly mixed and magnetic granules were prepared using a twin-screw extruder with the screw temperature of each section being 100-200℃.

[0191] A single-screw wire extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire with a permanent magnet orientation field of 12000 Oe. The wire diameter and cross-sectional shape were flat and round, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 150℃. The thickness of the inner coating was 0.6 mm.

[0192] Flame-retardant nylon woven outer quilts were prepared using weaving equipment, with an outer quilt layer thickness of 0.3 mm.

[0193] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0194] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0195] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional height of 4.6mm, a flat section width of 0.5mm, a cross-sectional width of 4.8mm, and a Shore hardness of 70A. After magnetization, the flat section has a measured magnetic field of 550Gs. The cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0196] Example 8

[0197] Anisotropic neodymium iron nitrogen magnetic powder (D50 of 1.65 μm) and ferrite magnetic powder (D50 of 1.70 μm) were modified using KH550 silane coupling agent at 1.5 wt% of the magnetic powder weight, respectively. The modification process included: dissolving KH550 silane coupling agent in anhydrous ethanol (silane coupling agent concentration 20 wt%), adding magnetic powder, mixing and stirring at 120 °C using a Hensel mixing dryer, and drying to obtain modified anisotropic neodymium iron nitrogen magnetic powder and modified ferrite magnetic powder.

[0198] 55 wt% of modified anisotropic neodymium iron nitrogen magnetic powder, 15 wt% of modified ferrite magnetic powder, 20 wt% of TPV (melting point 170℃), 5 wt% of phosphorus nitrogen-based halogen-free flame retardant KSW-03, and 5 wt% of additives containing antioxidants and plasticizers (including 2 wt% antioxidant 1076 and 3 wt% plasticizer DEHP) were thoroughly mixed and magnetic granules were prepared using a twin-screw extruder with the screw temperature of each section being 100–200℃.

[0199] A single-screw wire extruder was used to extrude a halogen-free, flame-retardant, magnetically oriented wire with a permanent magnet orientation field of 12000 Oe. The wire diameter and cross-sectional shape were flat and round, and the extrusion speed was 30 m / s. The screw temperature in each section of the extruder was 100–200℃, and the die temperature was 150℃. The thickness of the inner coating was 0.8 mm.

[0200] Flame-retardant nylon woven outer quilts were prepared using weaving equipment, with an outer quilt layer thickness of 0.3 mm.

[0201] The wire is initially shaped by baking equipment at a temperature of 280℃.

[0202] The wire is magnetized in a coiled state using a spiral coil magnetization device with a magnetic field of 35000kOe.

[0203] The aforementioned magnetic data cable has a core diameter of 2.8mm, a finished cross-sectional height of 5.0mm, a flat section width of 0.7mm, a cross-sectional width of 5.2mm, and a Shore hardness of 65A. After magnetization, the flat section has a measured magnetic field strength of 550Gs. The cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0204] Comparative Example 1

[0205] The material from Example 1 was extruded through a die without magnetic field orientation function. All other manufacturing processes were exactly the same. After magnetization, the flat part was measured to have a magnetic field of 280 Gs and a Shore hardness of 70 A. The finished wire was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0206] Comparative Example 2

[0207] The magnetic powders (anisotropic samarium iron nitride magnetic powder and ferrite magnetic powder) in Example 1 were completely replaced with isotropic neodymium iron boron magnetic powder (D50 of 103 μm). The powder was extruded through a die without magnetic field orientation function, while all other manufacturing processes remained identical. After magnetization, the flat section measured a magnetic field of 480 Gs and a Shore hardness of 90 A. The finished wire was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and failed the test.

[0208] Comparative Example 3

[0209] The mixture ratio in Example 1 was changed to 45 wt% modified isotropic samarium iron nitrogen magnetic powder, 15% modified ferrite magnetic powder, 20% TPV, 15% phosphorus nitrogen-based halogen-free flame retardant, and 5% additives containing antioxidants and plasticizers. The mixture was thoroughly mixed and extruded through a die without magnetic field orientation function. All other manufacturing processes remained the same. After magnetization, the flat section measured a magnetic field of 450 Gs and a Shore hardness of 90 A. The finished wire was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and failed the test.

[0210] Comparative Example 4

[0211] The flame retardant in the mixture of Example 1 was replaced with anisotropic samarium iron nitrogen magnetic powder, that is, 55 wt% of modified anisotropic samarium iron nitrogen magnetic powder, 20% of modified ferrite magnetic powder, 20% of TPV, and 5% of additives containing antioxidants and plasticizers were fully mixed, and the other manufacturing processes were completely the same.

[0212] After magnetization, the flat section measured a magnetism of 700 Gs and a Shore hardness of 85 A. The completed cable was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, but failed.

[0213] Comparative Example 5

[0214] In Example 1, the anisotropic samarium iron nitrogen magnetic powder and ferrite magnetic powder were not modified with KH550 silane coupling agent, and the other manufacturing processes were completely the same. After magnetization, the flat part measured a magnetic field of 400 Gs and a Shore hardness of 90 A. The finished wire was tested for flame retardancy using a cable flame retardancy testing device according to the UL1581 standard, and the flame retardancy rating was VW-1.

[0215] Comparative Example 6

[0216] Anisotropic samarium iron nitrogen magnetic powder (86.5 wt%), TPU (11 wt%), and antioxidants and lubricants (2.5 wt%) were thoroughly mixed and then used to prepare intermediate-layer granules using a twin-screw extruder. The D50 of the anisotropic samarium iron nitrogen magnetic powder was 4 μm.

[0217] The outer coating granules were prepared by thoroughly mixing powder containing fillers and pigments (86.5 wt%), TPU (11 wt%), phosphorus-nitrogen flame retardant KSW-03, antioxidant 1076, and lubricant PMX-200 silicone oil (2.5 wt%) in a mass ratio of 1:1:1, and using a twin-screw extruder.

[0218] The inner coating granules are extruded using a single-screw wire extruder, while the outer coating granules are extruded using a double-layer extrusion device.

[0219] The core diameter is 2.8mm, the middle sheath thickness is 0.7mm, and the outer sheath thickness is 0.4mm. The wire was magnetized while coiled using a spiral coil magnetization device. After magnetization, the wire surface magnetism was 200Gs, and the Shore hardness was 95A. A flame retardancy test was performed using a cable flame retardancy testing device according to the UL1581 standard; the test failed.

[0220] The wires in Examples 1-8 and Comparative Examples 1-6 were subjected to high-temperature winding and cold bending experiments, respectively.

[0221] High-temperature winding test conditions: 100℃ / 1 hour, the diameter of the winding mandrel is twice the outer diameter of the wire, observe whether the wire has cracks or defects, no cracks or defects are qualified, cracks or defects are unqualified;

[0222] Cold bending test conditions: -20℃ / 4 hours, the diameter of the winding mandrel is twice the outer diameter of the wire, observe whether the wire has cracks or defects. No cracks or defects are acceptable, and cracks or defects are unacceptable.

[0223] The test results are shown in Table 1 below:

[0224] Table 1

[0225] Serial Number Magnetic surface Flame retardant test hardness High-temperature winding Cold bending test Example 1 650Gs VW-1 70A qualified qualified Example 2 750Gs VW-1 80A qualified qualified Example 3 850Gs VW-1 90A qualified qualified Example 4 700Gs VW-1 70A qualified qualified Example 5 800Gs VW-1 90A qualified qualified Example 6 700Gs VW-1 65A qualified qualified Example 7 550Gs VW-1 70A qualified qualified Example 8 550Gs VW-1 65A qualified qualified Comparative Example 1 280Gs VW-1 70A qualified qualified Comparative Example 2 480Gs Unqualified 90A Unqualified Unqualified Comparative Example 3 450Gs Unqualified 90A Unqualified Unqualified Comparative Example 4 700Gs Unqualified 85A qualified qualified Comparative Example 5 400Gs VW-1 90A Unqualified Unqualified Comparative Example 6 200Gs Unqualified 95A Unqualified Unqualified

[0226] As can be seen from the above results, the wires prepared in Examples 1-8 of the present invention all have good flame retardant properties and high surface magnetic properties, and exhibit excellent mechanical properties in high-temperature winding and cold bending tests. Comparative Example 1's flame-retardant magnetic layer material was extruded through a die without magnetic field orientation, resulting in a low surface magnetic field, which failed to meet the magnetic adsorption requirements of the wire. Comparative Example 2 used isotropic neodymium iron boron magnetic powder as the magnetic material, which, compared with the anisotropic samarium iron nitride magnetic powder and ferrite magnetic powder composite scheme in Example 1, had poor flame-retardant effect and poor mechanical properties. Comparative Example 3 used isotropic samarium iron nitride magnetic powder, increasing the content of flame retardant, resulting in a wire with a low surface magnetic field, and its flame-retardant effect and mechanical properties could not reach the level of the examples. Comparative Example 4 did not add flame retardant, and the flame-retardant test failed. The anisotropic samarium iron nitride magnetic powder and ferrite magnetic powder in Comparative Example 5 were not modified with coupling agent, and the surface magnetic field was only 400 Gs, failing to reach the level of the examples, and the mechanical properties were unqualified. Comparative Example 6 adopted the existing technology CN 113674921. The method disclosed in B uses samarium iron nitrogen magnetic powder with a D50 of 4 μm as the magnetic material, and only adds flame retardant to the outer layer. However, due to the excessively large D50 of the anisotropic samarium iron nitrogen magnetic powder in Comparative Example 6, its magnetic properties are low, the magnetic attraction of the wire is not high (surface magnetic 200 Gs), the bonding with the elastomer is also poor, and the hardness is too high (95A), resulting in the flame retardant performance and mechanical properties not reaching the level of the example.

[0227] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A method for preparing a flame-retardant magnetic wire, characterized in that, The flame-retardant magnetic wire comprises, from the inside out, a wire core, a middle sheath layer, and an outer sheath layer, wherein the middle sheath layer is a flame-retardant magnetic sheath layer. The preparation method of the wire includes: (1) The wire core and the flame-retardant magnetic layer material are extruded together to obtain a wire core covered with a flame-retardant magnetic layer. The flame-retardant magnetic layer material includes an elastic substrate, a magnetic material and a flame retardant; wherein the magnetic material includes rare earth iron nitrogen magnetic powder and ferrite magnetic powder. In step (1), the magnetic material is surface modified by a coupling agent; the magnetic material is modified at 80-150°C using a coupling agent accounting for 0.2-2 wt% of the total weight of the magnetic material, wherein the coupling agent is a silane coupling agent; An outer sheath is prepared on the outside of the wire core covered by the obtained flame-retardant magnetic layer; (2) Shape the wire obtained in step (1); (3) Magnetize the wire obtained in step (2) to obtain the flame-retardant magnetic wire.

2. The method according to claim 1, characterized in that, In the flame-retardant magnetic layer material, the content of the elastic substrate is 15wt% to 25wt%, the content of the magnetic material is 55wt% to 75wt%, and the content of the flame retardant is 5wt% to 15wt%.

3. The method according to claim 1, characterized in that, The rare earth iron-nitrogen magnetic powder is samarium iron-nitrogen magnetic powder and / or neodymium iron-nitrogen magnetic powder.

4. The method according to claim 3, characterized in that, The D50 of the samarium iron nitrogen magnetic powder is 1.9–3 μm, the D50 of the neodymium iron nitrogen magnetic powder is 1.5–1.9 μm, and the D50 of the ferrite magnetic powder is 1.5–1.8 μm; and / or The samarium iron nitrogen magnetic powder, neodymium iron nitrogen magnetic powder and / or the ferrite magnetic powder are anisotropic.

5. The method according to claim 4, characterized in that, In the magnetic material, the mass ratio of rare earth iron-nitrogen magnetic powder to ferrite magnetic powder is (0.5-1):(0-0.5).

6. The method according to claim 5, characterized in that, In the magnetic material, the mass ratio of rare earth iron-nitrogen magnetic powder to ferrite magnetic powder is (0.5-0.9):(0.1-0.5).

7. The method according to claim 1, characterized in that, In step (1), during the extrusion molding process, the extruder head adopts permanent magnet orientation or electromagnetic orientation.

8. The method according to claim 7, characterized in that, The orientation field of the permanent magnet is 8000–13000 Oe; or The orientation field of the electromagnetic orientation is ≥13000 Oe.

9. The method according to claim 1, characterized in that, The elastic substrate in the flame-retardant magnetic layer material is: Polyvinyl chloride (PVC) Silicone rubber; and / or Thermoplastic elastomers.

10. The method according to claim 9, characterized in that, The hardness of the polyvinyl chloride (PVC) is 40-100A.

11. The method according to claim 9, characterized in that, The hardness of the silicone rubber is 40 to 70A.

12. The method according to claim 9, characterized in that, The melting point of the thermoplastic elastomer is 80–200°C.

13. The method according to claim 12, characterized in that, The thermoplastic elastomer is one or more of the following: styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, diene-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, urethane-based thermoplastic elastomers (TPU), polyester-based thermoplastic elastomers (TPEE), polyamide-based thermoplastic elastomers (TPAE), thermoplastic elastomers and thermoplastic resins (EEA), thermoplastic vulcanized rubbers (TPV), and silicone-based thermoplastic elastomers.

14. The method according to claim 13, characterized in that, The thermoplastic elastomer is one or more halogen-free materials selected from TPEE, TPU, TPV, and TPAE.

15. The method according to claim 1, characterized in that, The flame retardant in the flame-retardant magnetic layer material is selected from organic flame retardants and / or inorganic flame retardants.

16. The method according to claim 15, characterized in that, The flame retardant in the flame-retardant magnetic layer material is a halogen-free flame retardant.

17. The method according to claim 15, characterized in that, The flame-retardant magnetic layer material also includes processing aids, which include one or more of coupling agents, plasticizers, toughening agents, lubricants, and antioxidants.

18. The method according to claim 1, characterized in that, In step (1), the outer layer material is selected from one or more of the following: woven material, TPU, TPEE, TPV, and silicone rubber.

19. The method according to claim 18, characterized in that, The weaving material is a flame-retardant weaving material.

20. The method according to claim 19, characterized in that, The weaving material is one or more of flame-retardant nylon, flame-retardant aramid, and flame-retardant aramid.

21. The method according to claim 1, characterized in that, In step (1), the material is extruded using a single-screw wire extruder and a permanent magnet orientation extruder head.

22. The method according to claim 21, characterized in that, Extrusion speed ≥ 30 m / s.

23. The method according to claim 21, characterized in that, When the elastic substrate is silicone rubber, the extruder and die are at room temperature.

24. The method according to claim 21, characterized in that, The elastic substrate is a thermoplastic elastomer, and the screw temperature in each section of the extruder is 100-200℃.

25. The method according to claim 21, characterized in that, When the elastic substrate is a thermoplastic elastomer, the extruder die temperature is 120–200°C.

26. The method according to any one of claims 1 to 25, characterized in that, In step (2), when the elastic substrate is a thermoplastic elastomer, it is baked at 200-300℃ for shaping; In step (2), when the elastic substrate is silicone rubber, it is vulcanized and shaped through a heating channel at a temperature of 200–400°C; and / or In step (3), the wire is magnetized in a coiled state using a spiral coil magnetizing device with a magnetic field of 35000kOe or more, or in a flat state using a grooved magnetizing device.

27. A flame-retardant magnetic wire, characterized in that, The wire is prepared by the method of any one of claims 1 to 26.

28. The flame-retardant magnetic wire according to claim 27, characterized in that, The Shore hardness of the wire is ≤90A.

29. The flame-retardant magnetic wire according to claim 27, characterized in that, The flame retardancy rating of the wire meets VW-1.

30. The flame-retardant magnetic wire according to claim 27, characterized in that, The wire is halogen-free.

31. The flame-retardant magnetic wire according to claim 27, characterized in that, The surface magnetic field strength of the wire in the magnetization direction is above 500 Gs.

32. The flame-retardant magnetic wire according to any one of claims 27 to 31, characterized in that, The thickness of the middle sheath of the wire is 0.3 to 2 mm, and / or the thickness of the outer sheath of the wire is ≤1 mm.

33. The flame-retardant magnetic wire according to claim 32, characterized in that, The thickness of the inner lining layer of the wire is 0.3 to 1 mm.

34. The flame-retardant magnetic wire according to claim 32, characterized in that, The outer sheath thickness of the wire is ≤0.3mm.

35. The flame-retardant magnetic wire according to claim 32, characterized in that, The wire core comprises one or more individual conductors covered with an insulation layer.

36. The flame-retardant magnetic wire according to claim 35, characterized in that, The wire core is further provided with fiber material, which is selected from one or more of glass fiber, basalt fiber, and aramid.

37. The flame-retardant magnetic wire according to claim 36, characterized in that, A shielding layer is also provided between the wire core and the inner sheath of the wire, and the shielding layer wraps the conductor and fiber material.

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