Flame-retardant insulated cable for robot as well as preparation method and application of flame-retardant insulated cable

Abstract

According to the flame-retardant insulated cable material for the robot and the preparation method of the flame-retardant insulated cable material, recycled polypropylene is used as a matrix, and an ionic copolymer, polyphenylene sulfide, a nitrogen-phosphorus flame retardant, a carbon-forming agent and other components in a specific proportion are added, so that flame retardant molecular migration is effectively inhibited, the flame-retardant efficiency is improved, and meanwhile, excellent insulating performance is kept. The material shows excellent mechanical property, flame-retardant stability and electrical insulation property in a high-temperature and high-humidity environment. The innovative N-Si-P compound flame-retardant system and the ionic copolymer are applied, so that the comprehensive performance of the material is improved, the dosage of the flame retardant is reduced, and the balance of environmental protection and performance is realized. The cable material is particularly suitable for robot cable insulation layers in outdoor high-temperature and high-humidity environments, and a breakthrough solution is provided for high-performance and green development of robot cables.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable materials, and in particular relates to a flame-retardant insulated cable for robots, a preparation method thereof, and an application thereof. Background Art

[0002] Due to its excellent properties, polypropylene is widely used in many fields such as automobiles, home appliances, and cables. This has led to a large amount of waste polypropylene generated from scrapped cars and home appliances. However, waste polypropylene is difficult to degrade in the natural environment, and long-term accumulation poses a serious threat to the ecological environment. The use of recycling and modification technology to treat waste polypropylene can not only achieve resource recycling and reduce environmental pollution, but also significantly improve the technical content of the material and the added value of the product. It is a key way to promote the recycling and utilization of waste polypropylene. However, it should be noted that during the polypropylene recycling process, due to multiple melt processing, the molecular chain breaks and the molecular weight decreases, which in turn affects the toughness of the material. Therefore, how to effectively solve the problem of reduced toughness caused by molecular chain breakage during the recycling process has become the key to improving the performance of recycled polypropylene and promoting its widespread application.

[0003] Polypropylene, as a cable base material, offers significant advantages in many areas. First, in terms of electrical properties, polypropylene offers excellent electrical insulation. Its high breakdown voltage is unaffected by ambient humidity and electric field frequency, making it an ideal cable material. Regarding heat resistance, polypropylene maintains stable performance over long periods of time within a temperature range of 100-120°C. Its higher current carrying capacity compared to traditional materials makes it particularly suitable for use in high-temperature environments. Regarding chemical stability, polypropylene has low water absorption and high chemical resistance, effectively resisting attack by most chemicals. Furthermore, in terms of mechanical properties, polypropylene not only offers high strength and rigidity, but also exhibits excellent stress cracking resistance, ductility, and flex fatigue resistance. These properties make it easily adaptable to the complex environments in which cable is manufactured and used. Cable materials must not only possess excellent mechanical and electrical properties, but also flame retardancy and insulation properties. However, there is a conflict between the addition of flame retardants and insulation performance: the addition of large amounts of inorganic flame retardants (such as magnesium hydroxide or aluminum hydroxide) significantly reduces the volume resistivity, failing to meet insulation performance requirements. Furthermore, due to the use of large amounts of inorganic flame retardants, the volume resistivity of halogen-free, low-smoke flame-retardant insulation materials is difficult to reach the level of traditional insulation materials (such as pure PE). To overcome this problem, researchers have attempted to use organic flame retardants (such as nitrogen-phosphorus flame retardants) instead of inorganic flame retardants. However, these organic flame retardants typically contain polar groups (such as phosphates and amino groups), while common polymer matrices (such as polyolefins) are mostly non-polar materials. This polarity difference leads to weak interfacial bonding, and the flame retardant easily migrates to the material surface, thereby reducing flame retardancy. Therefore, how to maintain or improve insulation performance while improving flame retardancy has become an important direction in current cable material research.

[0004] In response to the above problems, the present invention provides a flame-retardant insulated cable and a preparation method thereof. Recycled polypropylene is used as the matrix material, and ionic copolymers are utilized to effectively inhibit the migration of flame retardant molecules. Especially under high temperature and high humidity processing conditions, the diffusion of flame retardants to the material surface is significantly reduced, thereby greatly improving the flame retardant efficiency and achieving dual optimization of flame retardancy and insulation performance. Summary of the Invention

[0005] This invention aims to address the key deficiencies of the aforementioned existing cable materials by proposing a flame-retardant insulated cable based on a recycled polypropylene matrix and its preparation process. This not only efficiently utilizes waste polypropylene resources, but also specifically addresses challenges such as the insufficient toughness of recycled polypropylene and the migration and degradation of flame retardants during processing. The optimized composite system maintains excellent mechanical durability, flame retardant stability, and electrical insulation properties under complex operating conditions. It is particularly suitable for use as the insulation layer of flexible cables for industrial robots operating in outdoor high-temperature and high-humidity environments, providing a breakthrough solution for the high-performance and green development of robotic cables.

[0006] The present invention provides a flame-retardant insulated cable for robots, comprising: a conductor layer, a shielding layer, a modified insulating layer and an outer sheath layer; the modified insulating layer is a polypropylene composite material.

[0007] The polypropylene composite material comprises the following raw materials in parts by weight: 100 parts of recycled polypropylene, 1-5 parts of ionic copolymer, 10-20 parts of polyphenylene sulfide, 5-10 parts of nitrogen-phosphorus flame retardant, 1-5 parts of carbon former, 8-15 parts of toughening agent, 1-5 parts of compatibilizer, 0.5-5 parts of chain extender, 0.5-5 parts of initiator, 0.5-3 parts of antioxidant, and 0.5-3 parts of lubricant.

[0008] Preferably, the recycled polypropylene has a melt mass flow rate of 10-50 g / 10 min at 230° C. and a load of 2.16 kg.

[0009] Preferably, the ionic copolymer is one of ethylene-methacrylic acid sodium salt, ethylene-methacrylic acid zinc salt or ethylene-methacrylic acid magnesium salt.

[0010] Preferably, the melt flow rate of the polyphenylene sulfide at 316° C. and 5 kg is 400-1200 g / 10 min.

[0011] Preferably, the nitrogen-phosphorus flame retardant is at least one of piperazine pyrophosphate, melamine polyphosphate, and ammonium polyphosphate.

[0012] Preferably, the carbon-forming agent is at least one of montmorillonite and silicon dioxide, and the average particle size of the montmorillonite and silicon dioxide is 0.5-50 μm.

[0013] Preferably, the toughening agent is at least one of ethylene-octene copolymer, ethylene propylene diene monomer rubber, styrene-butadiene-styrene block copolymer, and ethylene-vinyl acetate copolymer.

[0014] Preferably, the compatibilizer is at least one of maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, maleic anhydride grafted ethylene-octene copolymer, and glycidyl methacrylate grafted polypropylene.

[0015] Preferably, the chain extender includes one or more of vinylphosphonic acid, methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate and diethyl vinylphosphonate.

[0016] Preferably, the initiator includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide.

[0017] Preferably, the lubricant comprises at least one of silicone, polyethylene wax, hexylene biserucamide, and ethylene biserucamide. More preferably, the lubricant is at least one of hexylene biserucamide and ethylene biserucamide.

[0018] Preferably, the antioxidant is one or more of hindered phenol antioxidants, phosphite antioxidants or thioether antioxidants.

[0019] Preferably, the method for preparing the polypropylene composite material comprises the following steps:

[0020] The components are mixed evenly in proportion, melt-extruded in a twin-screw extruder, granulated, and dried to obtain a polypropylene composite material.

[0021] Preferably, the extrusion temperature of the twin-screw extruder is 180-240° C., the drying temperature is 70-100° C., and the drying time is 1-3 hours.

[0022] The present invention also relates to a method for preparing a flame-retardant insulated cable for a robot, comprising the following steps:

[0023] (1) Preparation of conductor core layer: The conductor material is drawn to obtain a wire to prepare the conductor layer;

[0024] (2) preparing a shielding layer: using an extrusion die to coat the shielding layer on the surface of the conductor layer in step (1) to obtain a shielding layer;

[0025] (3) preparing a modified insulating layer: wrapping the modified insulating layer on the surface of the shielding layer in step (2) to obtain a modified insulating layer;

[0026] (4) Preparing an outer sheath layer: Extruding an outer sheath layer on the surface of the insulating layer in step (3) to obtain a flame-retardant insulated cable.

[0027] Preferably, the present invention also provides the application of the above-mentioned flame-retardant insulated cable in the field of robotics, which is characterized in that it is used in various robot systems such as industrial automation equipment, service robots, medical robots, logistics robots, etc., especially in outdoor high temperature and high humidity, complex working conditions, and scenarios with high environmental protection requirements. It can effectively ensure the flame retardancy, insulation, mechanical durability and environmental adaptability of the robot cable, and meet the stable operation requirements of the robot in complex environments.

[0028] In the present invention, the metal ions (such as Na + 、Zn 2+ Mg 2+ ) can coordinate with the phosphate groups in the flame retardant to form dynamic bonds, thereby constructing a cross-linked network. This cross-linked network can effectively limit the migration of flame retardant molecules, especially under high-temperature processing conditions, and can inhibit the diffusion of flame retardants to the surface of the material, making it more evenly dispersed in the polypropylene matrix. In addition, the non-polar segments in the ionic polymer have good compatibility with PP, acting as a "bridge" to reduce the phase separation and surface precipitation of flame retardants caused by polarity differences, thereby significantly improving the flame retardant efficiency. However, the amount of ionic polymer needs to be strictly controlled. When the amount is too small, the flame retardant is prone to precipitation; when the amount is too much, the free metal ions in the polymer (especially Zn 2+ and Mg 2+ ) may migrate and form conductive pathways in the material, thereby reducing the volume resistivity of the material and affecting the insulation performance of the cable. Therefore, the amount of ionomer should be controlled within the range of 1-5wt% of recycled polypropylene to achieve the best balance between flame retardancy and insulation properties.

[0029] Polyphenylene sulfide (PPS) is a material with excellent insulating properties, maintaining excellent electrical insulation performance, particularly at high temperatures (200-240°C) and in humid environments. Furthermore, with an oxygen index of 44%-53%, PPS exhibits excellent flame retardancy. Incorporating PPS into polypropylene composites significantly improves the composite's insulation and flame retardancy, effectively enhancing the insulation stability and safety of the cable.

[0030] The present invention uses a compound system of nitrogen-phosphorus flame retardants such as piperazine pyrophosphate and melamine polyphosphate and silicon-containing carbon-forming agents (montmorillonite and silica) in the use of flame retardants. Nitrogen-phosphorus flame retardants decompose to generate acidic substances such as phosphoric acid when heated, which promotes the dehydration of the polymer into carbon, forming a dense carbon layer, which effectively blocks the transfer of heat and oxygen; at the same time, the silicon-containing carbon-forming agent generates a stable inorganic carbon layer during the combustion process, which synergizes with the carbon layer formed by the nitrogen-phosphorus flame retardant to further enhance the stability and density of the carbon layer, thereby more effectively blocking heat and oxygen. This N-Si-P synergistic compound system not only improves the carbonization efficiency, but also reduces the amount of flame retardant used, while significantly improving the flame retardant properties of the material.

[0031] The present invention conducts a chain extension reaction between vinylphosphonic acid and its ester compounds (such as methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate and diethyl vinylphosphonate) and recycled polypropylene under the action of a free radical initiator. This not only increases the molecular weight of the recycled polypropylene, thereby significantly improving its impact resistance, tensile strength and elongation at break; but also introduces phosphonic acid groups that decompose to generate acidic substances such as phosphoric acid during combustion, promoting the dehydration of the polypropylene surface into carbon, and forming a dense carbon layer. This carbon layer can effectively prevent the transfer of heat and oxygen, thereby significantly improving the flame retardant properties of the material.

[0032] The present invention prefers biserucamide as a lubricant. Biserucamide, which has long-chain hydrophobic groups and polar amide groups, can act as a surfactant or compatibilizer, reducing the interfacial tension between the flame retardant and the polymer substrate, thereby promoting uniform dispersion of the flame retardant in the material. During material processing, biserucamide can coat piperazine pyrophosphate and melamine polyphosphate flame retardants, reducing thermal decomposition of the flame retardant during thermal processing and lowering the risk of flame retardant degradation due to flame retardant precipitation or degradation.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The flame-retardant insulated cable for robots provided by the present invention has excellent flame retardant properties, insulation properties and mechanical properties. By adding an ionic polymer with a specific ratio, the migration of flame retardant molecules is effectively restricted, and the diffusion of flame retardants to the surface of the material is inhibited, thereby achieving an optimal balance between flame retardant properties and insulation properties. At the same time, the N-Si-P composite flame retardant system is combined to synergistically improve the carbonization efficiency, significantly improving the flame retardant properties of the material when the amount of flame retardant is small. In addition, the present invention uses recycled polypropylene to replace virgin materials, reducing resource waste and environmental impact. DETAILED DESCRIPTION

[0035] To better illustrate the purpose, technical solutions and advantages of the present invention, the technical solutions of the present invention are further described below through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0036] Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available.

[0037] Recycled polypropylene PP-1: Commercially available recycled material from washing machine tub shells, with a melt mass flow rate of 45 g / 10 min at 230°C and 2.16 kg load, available from Qingyuan Haipeng Chemical Plastics Co., Ltd.

[0038] Recycled polypropylene PP-2: Commercially available TV casing recycled material, with a melt flow rate of 25g / 10min measured at 230°C and a load of 2.16kg, produced by Qingyuan Haipeng Chemical Plastics Co., Ltd.

[0039] Recycled polypropylene PP-3: Polypropylene turnover basket, melt flow rate measured at 230°C and 2.16 kg load is 10 g / 10 min, Qingyuan Haipeng Chemical Plastics Co., Ltd.

[0040] Polyphenylene sulfide resin 1: PPS-1, brand PPS1150C, melt flow rate of 450 g / 10 min at 316°C and 5 kg load, Xinhecheng Special Materials Co., Ltd.

[0041] Polyphenylene sulfide resin 2: PPS-2, brand PPS1190C, melt flow rate at 316°C and 5 kg load is 1050 g / 10 min, Xinhecheng Special Materials Co., Ltd.

[0042] The ionic copolymers ethylene-methacrylic acid sodium salt, ethylene-methacrylic acid zinc salt or ethylene-methacrylic acid magnesium salt are commercial products of DuPont.

[0043] Example

[0044] The preparation method of the modified polypropylene composite material for the insulating layer in the embodiment and the comparative example comprises the following steps:

[0045] (1) Weigh various raw materials according to the ratio;

[0046] (2) adding the raw materials of step (1) into a mixer and mixing them uniformly to obtain a mixed material;

[0047] (3) adding the mixture obtained in step (2) into a twin-screw extruder for extrusion granulation, wherein the temperature of the twin-screw extruder from the feeding section to the die is: 180-190°C, 180-190°C, 190-200°C, 190-200°C, 190-210°C, 190-220°C, 190-230°C, the drying temperature is 80°C, and the drying time is 2h to obtain the polypropylene composite material.

[0048] The distribution ratios (parts by weight) of each group in Table 1 are as follows.

[0049]

[0050]

[0051] Table 2 Comparative Examples The distribution ratios of each group (parts by weight) are as follows

[0052]

[0053]

[0054] Performance Testing

[0055] The polypropylene composite materials prepared in the examples and comparative examples were subjected to relevant performance tests, and the specific test methods are as follows:

[0056] (1) Tensile strength test: The tensile strength of the polypropylene composite material was tested using ISO 527-2012 “Test methods for tensile properties of plastics” at a tensile rate of 10 mm / min.

[0057] (2) Notched impact strength: tested in accordance with ISO 180-2019.

[0058] (3) Elongation at break: Tested in accordance with ISO 527-1-2019, test condition: 25°C.

[0059] (4) Flame retardant performance test: Flame retardant performance test was conducted on the specimens according to the relevant standards of UL94-2015. The sample thickness was 1.5mm and was divided into V0, V1, V2 and NG (flame retardant grade does not reach V2). The oxygen index was measured according to GB / T2406-93. A high oxygen index indicates good flame retardant effect.

[0060] Another group of samples were immersed in distilled water at 60°C for 72 hours to test the flame retardancy and oxygen index.

[0061] (5) Insulation performance test: The volume resistance test was conducted in accordance with GB / T 1410-2016. Another set of samples was immersed in distilled water at 60°C for 72 hours, wiped dry, and then tested for volume resistance at 25°C.

[0062] The test results are shown in Table 3

[0063]

[0064]

[0065]

[0066] According to the test results in Table 3, the recycled polypropylene composite material of the embodiment of the present invention exhibits excellent comprehensive properties: in terms of mechanical properties, the material has good tensile strength, elongation at break and notched impact strength; the flame retardant performance is outstanding, and the oxygen index remains above 24% after being soaked in distilled water for 72 hours, and the flame retardant grade is V0; the electrical insulation performance is excellent, and the volume resistivity exceeds 2.4×10 13 These properties make it particularly suitable for the insulation layer of robot cables in outdoor high temperature and high humidity environments, and can effectively meet the requirements of mechanical durability, fire safety and electrical stability under complex working conditions.

[0067] By comparing the performance of Example 1 with that of Examples 5-7, it can be found that Example 1 and Example 5-7 have similar performances in mechanical properties and insulation properties, but in terms of flame retardant properties, Example 1 is significantly better than Examples 5-7, especially in terms of flame retardancy after distilled water immersion. This may be attributed to the fact that the biserucamide used in Example 1 can be used as a surfactant or compatibilizer, which can effectively reduce the interfacial tension between the flame retardant and the polymer substrate, thereby promoting the uniform distribution of the flame retardant in the material. In addition, biserucamide can also coat piperazine pyrophosphate and melamine polyphosphate flame retardants, reducing the thermal decomposition of flame retardants during thermal processing. This synergistic effect significantly improves the flame retardant properties of polypropylene composites, making them more advantageous in practical applications.

[0068] By comparing the performance of Example 1 with Comparative Examples 1-3, it can be found that the amount of ionic polymer used in Comparative Example 1 is too high. Although its flame retardant and mechanical properties are close to those of Example 1, its volume resistivity is significantly lower than that of Example 1. This may be due to the excessive amount of ionic polymer causing the free metal ions (especially Zn 2+ and Mg 2+) migrate in the material and form a conductive path, thereby reducing the volume resistivity of the material and affecting the insulation performance of the cable. In contrast, the content of the ionic polymer in Comparative Example 2 is too low, and no ionic polymer is added in Comparative Example 3, resulting in the migration and diffusion of the flame retardant molecules to the surface of the material at high temperature after the polypropylene material is immersed in deionized water, which eventually causes the flame retardant to separate and precipitate on the surface, significantly reducing the flame retardancy. Therefore, in order to achieve the best balance between flame retardancy and insulation performance, the amount of ionic polymer should be strictly controlled within the range of 1-5wt% of the recycled polypropylene. This optimized amount can not only effectively inhibit the migration and precipitation of the flame retardant, but also ensure the stability of the comprehensive performance of the material in complex environments.

[0069] By comparing the performance of Example 1 with Comparative Examples 4-5, it can be found that the polyphenylene sulfide is omitted in Comparative Example 4, resulting in a significant decrease in the flame retardant properties and electrical insulation properties of the composite material after distilled water impregnation, which shows that the introduction of polyphenylene sulfide can significantly improve the insulation and flame retardant properties of the polypropylene composite material. Comparative Example 5 omits the vinyl phosphate chain extender, resulting in a decrease in the toughness and flame retardant properties of the composite material. This may be because the vinyl phosphate chain extension reaction can increase the molecular weight of the recycled polypropylene, thereby significantly improving its impact resistance, tensile strength and elongation at break. In addition, the phosphonic acid group introduced by the vinyl phosphate chain extender will decompose to produce acidic substances such as phosphoric acid during combustion. These substances can promote the dehydration of the polypropylene surface into carbon, forming a dense carbon layer, thereby significantly improving the flame retardant properties of the material. Therefore, the reasonable addition of polyphenylene sulfide and vinyl phosphate chain extender is crucial to improving the comprehensive performance of the polypropylene composite material.

[0070] By comparing the performance of Example 1 with that of Comparative Examples 6-7, it can be found that Comparative Example 6 only uses nitrogen-phosphorus flame retardants, while Comparative Example 7 only uses carbon-forming agents. This single flame retardant system causes the prepared polypropylene composite material to have a significant decrease in flame retardant properties, especially after being impregnated with deionized water, the reduction in flame retardant properties is particularly obvious. In contrast, the present invention adopts a compounding system of nitrogen-phosphorus flame retardants and silicon-containing carbon-forming agents (montmorillonite and silica) to show a significant synergistic effect. Nitrogen-phosphorus flame retardants decompose to generate acidic substances such as phosphoric acid when heated, which promotes the dehydration of the polymer into carbon, forming a dense carbon layer, which effectively prevents the transfer of heat and oxygen. At the same time, the silicon-containing carbon-forming agent generates a stable inorganic carbon layer during the combustion process, which synergizes with the carbon layer formed by the nitrogen-phosphorus flame retardant to further enhance the stability and density of the carbon layer, thereby more effectively blocking heat and oxygen. This N-Si-P synergistic compounding system can meet the requirements of excellent flame retardant properties even when the flame retardant dosage is low.

[0071] The embodiments provided by the present invention are only for illustration and are not intended to limit the embodiments of the present invention. Based on the disclosure of the present invention, those skilled in the art may make formal modifications or adaptive adjustments to the technical solution without departing from the basic principles. There is no need to exhaustively enumerate all possible implementation forms. Any reasonable improvement, equivalent replacement or technical deduction made within the core idea and protection scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A flame-retardant insulated cable for robots, characterized in that: include: Conductor layer, shielding layer, modified insulating layer and outer sheath layer; the modified insulating layer is made of polypropylene composite material; The polypropylene composite material comprises the following raw materials in parts by weight: 100 parts of recycled polypropylene, 1-5 parts of ionic copolymer, 10-20 parts of polyphenylene sulfide, 5-10 parts of nitrogen-phosphorus flame retardant, 1-5 parts of carbon former, 8-15 parts of toughening agent, 1-5 parts of compatibilizer, 0.5-5 parts of chain extender, 0.5-5 parts of initiator, 0.5-3 parts of antioxidant, and 0.5-3 parts of lubricant; The ionic copolymer is one of ethylene-methacrylic acid sodium salt, ethylene-methacrylic acid zinc salt or ethylene-methacrylic acid magnesium salt; The nitrogen-phosphorus flame retardant is at least one of piperazine pyrophosphate, melamine polyphosphate, and ammonium polyphosphate; and the carbon-forming agent is at least one of montmorillonite and silicon dioxide.

2. The flame-retardant insulated cable for robots according to claim 1, wherein: The melt mass flow rate of the recycled polypropylene at 230° C. and a load of 2.16 kg is 10-50 g / 10 min; the melt flow rate of the polyphenylene sulfide at 316° C. and a load of 5 kg is 400-1200 g / 10 min.

3. The flame-retardant insulated cable for robots according to claim 1, wherein: The toughening agent is at least one of ethylene-octene copolymer, ethylene propylene diene monomer rubber, styrene-butadiene-styrene block copolymer, and ethylene-vinyl acetate copolymer.

4. The flame-retardant insulated cable for robots according to claim 1, wherein: The compatibilizer is at least one of maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, maleic anhydride grafted ethylene-octene copolymer, and glycidyl methacrylate grafted polypropylene.

5. The flame-retardant insulated cable for robots according to claim 1, wherein: The chain extender includes at least one of vinylphosphonic acid, methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate and diethyl vinylphosphonate.

6. The flame-retardant insulated cable for robots according to claim 1, wherein: The initiator includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide; the antioxidant is one or more of hindered phenol antioxidants, phosphite antioxidants, or thioether antioxidants; and the lubricant includes at least one of silicone, polyethylene wax, hexylene biserucamide, and ethylene biserucamide.

7. The flame-retardant insulated cable for robots according to claim 7, wherein: The lubricant is at least one of hexylene biserucamide and ethylene biserucamide.

8. The flame-retardant insulated cable for robots according to claim 1, wherein: The preparation method of the polypropylene composite material comprises the following steps: The components are mixed evenly in proportion, melt-extruded in a twin-screw extruder, granulated, and dried to obtain a polypropylene composite material; the extrusion temperature of the twin-screw extruder is 180-240°C, the drying temperature is 70-100°C, and the drying time is 1-3 hours.

9. A method for preparing a flame-retardant insulated cable for robots according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of the conductor layer: The conductor material is drawn to obtain a wire to prepare the conductor layer; (2) preparing a shielding layer: using an extrusion die to coat the shielding layer on the surface of the conductor layer in step (1) to obtain a shielding layer; (3) preparing a modified insulating layer: wrapping the modified insulating layer on the surface of the shielding layer in step (2) to obtain a modified insulating layer; (4) Preparing an outer sheath layer: Extruding an outer sheath layer on the surface of the insulating layer in step (3) to obtain a flame-retardant insulated cable.

10. An application of the flame-retardant insulated cable for robots according to any one of claims 1 to 8, characterized in that: Robotic cables for use in high temperature and high humidity environments.

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