Electric car cable sheath material and preparation method thereof

Abstract

The invention relates to an electric car cable sheath material and a preparation method thereof, and belongs to the technical field of cables. The electric car cable sheath material provided by the invention is prepared from the following components in parts by weight: 100 parts of PVC (Polyvinyl Chloride), 20 to 40 parts of aconite, 0.5 to 1 part of an absorption type anti-ultraviolet additive, 5 to 10 parts of a flame retardant, 0.5 to 2 parts of a lubricating agent and 1 to 5 parts of a heat stabilizer. The electric car cable sheath material has better cold resistance, high temperature resistance and ultraviolet resistance, is safe and environment-friendly, is suitable for being directly contacted and used by a user, can meet the use scene of the electric car cable in cold or sunny weather and high heating power, is proper in hardness, convenient to process and excellent in wear resistance, and is suitable for being used as the electric car cable sheath material.

Description

Technical Field

[0001] The present application relates to a tram cable sheath material and a preparation method thereof, belonging to the technical field of cables. Background Art

[0002] With the rapid popularization of new energy electric vehicles, the performance improvement of cables inside electric vehicles and on charging equipment has been severely challenged. Compared with traditional cable sheaths, electric vehicle cable sheath materials have more stringent requirements on safety and durability in the field of new energy electric vehicles. For example, electric vehicle cables used for outdoor charging of new energy electric vehicles need to meet the following requirements.

[0003] The first is the environmental friendliness of the material. In the field of new energy electric vehicles, the chances of cables coming into contact with the human body increase significantly, which means that the probability of plasticizers in the PVC composite sheath migrating into the human body increases. Traditional cable plasticizers use toxic phthalates, which are extremely harmful to the human body, especially the reproductive system of adolescents.

[0004] Secondly, the environment in which tram cables are located is more complex. They are not used stably and for a long time in a single place. Most of them are exposed to the outdoors and face the climate of extreme heat and cold. They need to have a wider temperature range and good anti-ultraviolet performance. However, the current environmentally friendly plasticizers replace the benzene ring in the main structure, which ensures safety and non-toxicity while also weakening the anti-ultraviolet performance of the material. In the face of long-term light, it is difficult for the cable sheath material to maintain good long-term stability.

[0005] Finally, due to the influence of their structure, existing plasticizers make it difficult to balance the plasticization stability of the material at high and low temperatures. The operating temperature range is narrow and they cannot be used stably for a long time.

[0006] Based on the actual use needs of tram cables, there is an urgent need to provide a cable sheath material with good cold resistance, high temperature resistance, and UV resistance, which is safe and environmentally friendly and suitable for direct contact by users. It can meet the charging performance requirements of new energy trams in cold or sunny weather and high heat power usage scenarios. Summary of the invention

[0007] In order to solve the above problems, a tram cable sheath material and a preparation method thereof are provided. The tram cable sheath material has good cold resistance, high temperature resistance, and UV resistance, and is safe and environmentally friendly and suitable for direct contact by users. It can meet the use scenarios of tram cables in cold or sunny weather and high heating power, and has appropriate hardness, is easy to process, and has excellent wear resistance, and is suitable as a sheath material for tram cables.

[0008] The present application provides a tram cable sheath material, which comprises the following components by weight: 100 parts of PVC, 20-40 parts of aconitate, 0.5-1 part of an absorption-type anti-ultraviolet additive, 5-10 parts of a flame retardant, 0.5-2 parts of a lubricant, and 1-5 parts of a heat stabilizer.

[0009] Optionally, the aconitate ester is selected from one or more of tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate, tri-n-octyl aconitate or tri(2-ethylhexyl) aconitate.

[0010] Optionally, the absorbing anti-ultraviolet additive is selected from one or more of UV-623 or UV3035.

[0011] Optionally, the flame retardant is selected from one or more of tris(2-chloropropyl) phosphate, aluminum hydroxide or magnesium hydroxide.

[0012] Optionally, the lubricant is selected from one or more of butyl stearate or chlorinated polyethylene wax.

[0013] Optionally, the heat stabilizer is selected from one or more of calcium stearate, zinc stearate or methyl tin mercaptan.

[0014] Optionally, the tram cable sheath material comprises the following components by weight: 100 parts of PVC, 35 parts of aconitate, 0.6 parts of absorption-type anti-ultraviolet additive, 7 parts of flame retardant, 1 part of lubricant, and 3 parts of heat stabilizer.

[0015] The present application provides a method for preparing a tram cable comprising the above tram cable sheath material, characterized in that the preparation method comprises the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 450-550 rpm, stir for 5-15 min, and obtain an additive mixture; 2) PVC, aconitate and the auxiliary agent mixture obtained in step 1) are mixed and added into a twin-screw extruder, and the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C, and 160°C, the rotation speed is 50-70 rpm, and the extrusion mass flow rate is 30-40 kg / h. After melt blending, the mixture is extruded on the outside of the cable core; 3) The coated cable core is passed through a thermoplastic box to form a protective layer, and finally cooled and solidified to obtain a tram cable including the tram cable sheath.

[0016] Optionally, the preparation method comprises the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 500 rpm, and stir for 10 min to obtain an additive mixture; 2) PVC, aconitate and the additive mixture obtained in step 1) are mixed and added into a twin-screw extruder, and the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C, and 160°C, the rotation speed is 60 rpm, and the extrusion mass flow rate is 35 kg / h. After melt blending, the mixture is extruded on the outside of the cable core; 3) The coated cable core is passed through a thermoplastic box to form a protective layer, and finally cooled and solidified to obtain a tram cable including the tram cable sheath.

[0017] The beneficial effects of this application include but are not limited to: 1. The tram cable sheath material according to the present application has good environmental protection and non-toxicity. Compared with traditional cables, tram cable sheaths are more likely to come into contact with the human body. Compared with traditional phthalate plasticizers, the aconitate plasticizer used in the tram cable sheath material in the present application has good non-toxic environmental protection and will not threaten human safety and health.

[0018] 2. According to the electric vehicle cable sheath material of the present application, the added aconitate not only has a plasticizing effect, but the "conjugated double bond" structure of the aconitate itself can also effectively absorb ultraviolet light, and at the same time form a good synergistic effect with the absorption type anti-ultraviolet additive UV-623 or UV3050 in the material, further improving the anti-ultraviolet performance of the material.

[0019] 3. According to the electric vehicle cable sheath material of the present application, the aconitate ester is selected from tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate, tri-n-octyl aconitate or tri-(2-ethylhexyl) aconitate, which has a wider operating temperature range. When the carbon number of the aconitate ester group is ≤8, its own triester structure can be effectively compatible with PVC, improving the mobility of the PVC molecular chain, thereby making the material exhibit good cold resistance. At the same time, when the carbon number of the ester group is ≥4, the aconitate ester has a larger molecular weight and is difficult to volatilize to the outside, so that the heat resistance of the material is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is a graph showing the changes in mechanical properties before and after aging involved in Example 1 of the present application. DETAILED DESCRIPTION

[0021] The present application is described in detail below in conjunction with examples, but the present application is not limited to these examples. Unless otherwise specified, the raw materials and catalysts in the examples of the present application are purchased through commercial channels.

[0022] Anti-ultraviolet additives are mainly divided into two categories. One is an absorption-type anti-ultraviolet agent, which works by selectively absorbing high-energy ultraviolet rays and converting them into other forms of lower energy (such as light with a longer wavelength or heat) for release; the other is a reflective anti-ultraviolet additive, which works by reflecting and shielding ultraviolet rays to prevent them from reaching the PVC surface and reducing the occurrence of photochemical reactions. The anti-ultraviolet additives used in this application are absorption-type anti-ultraviolet additives, such as UV-623 and UV3035, but are not limited to them. The anti-ultraviolet additives used in this application can play a synergistic and complementary role with the conjugated double bonds in aconitate. The combination of the two can not only increase the ultraviolet absorption wavelength range, but also enhance the material's ability to absorb ultraviolet rays, making it more resistant to ultraviolet rays. However, experiments have found that the reflective anti-ultraviolet additives are contrary to the ultraviolet absorption properties of aconitate and do not have a good synergistic anti-ultraviolet effect.

[0023] In the present application, PVC was purchased from Ningxia Jinyuyuan Chemical Group Co., Ltd.; aconitate was purchased from Chengdu Kamel Pharmaceutical Technology Co., Ltd.; UV-623 was purchased from Weihai Huaen Rubber and Plastic New Materials Co., Ltd.; UV3035 was purchased from Qingdao Jidejia New Materials Technology Co., Ltd.; tri(2-chloropropyl) phosphate was purchased from Zhangjiagang Xinya Chemical Co., Ltd.; aluminum hydroxide was purchased from Guangzhou Jicheng Import and Export Trading Co., Ltd.; magnesium hydroxide was purchased from Nanjing Hengqiao Chemical Technology Materials Co., Ltd.; butyl stearate was purchased from Shanghai Rongli Chemical Technology Co., Ltd.; chlorinated polyethylene wax was purchased from Dongguan Dinghai Plastic Chemical Co., Ltd.; calcium stearate was purchased from Nanjing Jinling Chemical Plant Co., Ltd.; zinc stearate was purchased from Shandong Johnson Chemical Co., Ltd.; methyl tin thiol was purchased from Hubei Nordina Biotechnology Co., Ltd.

[0024] It should be noted that, since the present application scheme focuses on the sheath material of tram cables, unless otherwise specified, tram cables containing cable cores are not prepared in the performance test. Therefore, the tram cable sheath material does not contain a cable core during the test, and the test is not conducted on the tram cable finally prepared in the embodiment. Those skilled in the art should be able to understand that the specific test is conducted using specimens of tram cable sheath materials prepared in accordance with GB / T1040.2-2006.

[0025] Example 1 In this embodiment, the basic formula of the tram cable sheath material is composed of the following components by weight: 100 parts of PVC, 35 parts of aconitate, 0.6 parts of absorption-type anti-ultraviolet additive, 7 parts of flame retardant, 1 part of lubricant, and 3 parts of heat stabilizer. The aconitate is tri-n-butyl aconitate, the absorption-type anti-ultraviolet additive is UV-623, the flame retardant is tris(2-chloropropyl) phosphate, the lubricant is butyl stearate, and the heat stabilizer is calcium stearate.

[0026] The preparation process of the tram cable includes the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 550 rpm, and stir for 5 min to obtain an additive mixture; 2) PVC, tri-n-butyl aconitate and the additive mixture in step 1) are mixed and added into a twin-screw extruder, and the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C, and 160°C, the rotation speed is 60 rpm, and the extrusion mass flow rate is 35 kg / h. After melt blending, it is extruded on the outside of the cable core, and then the coated cable core is passed through a thermoplastic box for thermoplasticization to obtain a protective layer. Finally, after cooling and curing, an environmentally friendly and non-toxic tram cable is obtained.

[0027] Example 2 In this embodiment, the basic formula of the tram cable sheath material is composed of the following components by weight: 100 parts of PVC, 20 parts of aconitate, 0.5 parts of absorption-type anti-ultraviolet additive, 5 parts of flame retardant, 2 parts of lubricant, and 5 parts of heat stabilizer. The aconitate is tri-n-hexyl aconitate, the absorption-type anti-ultraviolet additive is ultraviolet absorber UV3035, the flame retardant is aluminum hydroxide, the lubricant is chlorinated polyethylene wax, and the heat stabilizer is zinc stearate.

[0028] The preparation process of the tram cable includes the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 500 rpm, and stir for 10 min to obtain an additive mixture; 2) PVC, tri-n-hexyl aconitate and the additive mixture in step 1) are mixed and added into a twin-screw extruder, the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C and 160°C, 50 rpm is applied, and the extrusion mass flow rate is 30 kg / h. After melt blending, it is extruded on the outside of the cable core, and then the coated cable core is passed through a thermoplastic box for thermoplasticization to obtain a protective layer. Finally, after cooling and curing, an environmentally friendly and non-toxic tram cable is obtained.

[0029] Example 3 In this embodiment, the basic formula of the tram cable sheath material is composed of the following components by weight: 100 parts of PVC, 40 parts of aconitate, 0.5 parts of absorption-type anti-ultraviolet additive, 10 parts of flame retardant, 0.5 parts of lubricant, and 1 part of heat stabilizer. The aconitate is tri-n-octyl aconitate, the absorption-type anti-ultraviolet additive is UV absorber UV3035, the flame retardant is magnesium hydroxide, the lubricant is butyl stearate, and the heat stabilizer is methyl tin mercaptan.

[0030] The preparation process of the tram cable includes the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 450 rpm, and stir for 15 min to obtain an additive mixture; 2) PVC, tri-n-octyl aconitate and the additive mixture in step 1) are mixed and added into a twin-screw extruder, the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C and 160°C, 70 rpm is applied, and the extrusion mass flow rate is 40 kg / h. After melt blending, it is extruded on the outside of the cable core, and then the coated cable core is passed through a thermoplastic box for thermoplasticization to obtain a protective layer. Finally, after cooling and curing, an environmentally friendly and non-toxic tram cable is obtained.

[0031] Comparative Example 1 This comparative example is substantially the same as Example 1, except that it does not contain aconitate, but is replaced by an equal amount of dibutyl phthalate as a plasticizer.

[0032] Comparative Example 2 This comparative example is substantially the same as Example 1, except that aconitate is not contained, but an equal amount of di(2-ethylhexyl)phthalate is used as a plasticizer instead.

[0033] Comparative Example 3 This comparative example is substantially the same as Example 1, except that aconitate is not contained and an equal amount of epoxidized soybean oil is used as a plasticizer instead.

[0034] Test Example 1 Performance tests were carried out on the tram cable sheath materials prepared in the embodiments and comparative examples, including cold resistance, high temperature resistance, and UV resistance tests. Among them, the specimens of tram cable sheath materials prepared according to GB / T1040.2-2006 were subjected to tensile strength, elongation at break, and UV resistance aging tests. Among them, the hardness is in accordance with GB / T531-2008 "Indentation Hardness Test Method, Shore Hardness Tester Method", and the hardness represents the plasticizing performance of the material. The smaller the value, the better the plasticizing effect; the tensile strength is in accordance with GB / T1040-2006 "Plastic Tensile Performance Test", the tensile speed is 50 mm / min, the temperature is 25°C, the tensile strength represents the strength of the material, and the larger the value, the higher the material strength; the elongation at break is in accordance with GB / T1040-2006 "Plastic Tensile Performance Test", the tensile speed is 50 mm / min, the temperature is 25°C, the elongation at break represents the toughness of the material, and the higher the elongation at break, the stronger the toughness; in the anti-ultraviolet aging test, the prepared specimens are placed in a test box, and the experimental conditions are a 6KW xenon lamp. After irradiation for 2000 hours, it is left at room temperature for 24 hours, and then the tensile strength and elongation tests are carried out, and the retention rate is calculated. The test results are shown in Table 1 below.

[0035] Table 1

[0036] According to the data in Table 1, the tram cable sheath materials in Examples 1 to 3 have good heat and UV resistance, and have lower tensile strength and hardness than the control example, indicating that aconitate has a good plasticizing effect on the sheath material; at the same time, the PVC product plasticized with aconitate has suitable strength and elongation at break, and has a smaller hardness difference after aging, a high tensile strength retention rate after aging, and a high elongation at break retention rate after aging, indicating that the sheath material has better aging resistance, and is therefore suitable for preparing tram cable products to meet high temperature and sun exposure scenarios.

[0037] Experimental Example 1 The experimenters tested the effect of adding aconitate esters with different ester carbon numbers on the performance of tram cable sheath materials. The difference between the test sample and that in Example 1 is the type of aconitate ester. For specific differences, see Table 2 below. The performance results of the prepared tram cable sheath are shown in Table 3. The hardness test method is the same as that in Test Example 1; the low-temperature brittle temperature is tested in accordance with GB / T 15256-2014; the volatility test is a test of the volatility of plasticizers such as aconitate esters involved in the embodiments and test examples in PVC to reflect the volatility of different types of plasticizers. The test is carried out with reference to HG / T 4458-2012 "Determination of Plasticizer Loss - Activated Carbon Method", the test temperature is 70°C, and the test time is 24 h.

[0038] Table 2

[0039] Table 3

[0040] According to the data in Table 3, the selection of tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate, and tri-n-octyl aconitate to be added to the tram cable sheath material can balance the cold resistance, high temperature resistance and plasticization properties, because the ester carbon number of aconitate esters is ≤8 and has a wider operating temperature range, and the triester structure of these types of aconitate esters is effectively compatible with PVC, which improves the mobility of the PVC molecular chain, thereby making the material exhibit good cold resistance. At the same time, when the ester carbon number is ≥4, aconitate has a large molecular weight and is difficult to volatilize to the outside world, so that the heat resistance of the material is enhanced.

[0041] When the carbon number of the ester group of aconitate is less than 4, the molecular weight of aconitate is lower and it is easier to extract from PVC, affecting the plasticizing effect and high temperature resistance of the material; when the carbon number of the ester group is greater than 8, the molecular weight of aconitate is higher. At this time, although aconitate is difficult to extract from PVC, its polar ester molecular chain becomes longer and its polarity increases accordingly, resulting in poor compatibility with PVC, poor plasticizing effect on PVC, and poor effect with absorption-type anti-ultraviolet additives, affecting the anti-ultraviolet performance of PVC.

[0042] The tram cable sheath prepared with tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate and tri-n-octyl aconitate is more suitable for the use scenarios of tram cables. While meeting certain cold resistance effects and excellent high temperature resistance and UV resistance, it also has good plasticizing properties.

[0043] Experimental Example 2 The experimenters tested the effect of adding aconitate plasticizer and reflective anti-UV additive on UV absorption and anti-UV performance. Samples 7 to 8 differed from Example 1 only in the type of anti-UV additive. In addition, the performance testing method was the same as that of Test Example 1. The specific selection of anti-UV additives is shown in Table 4 below, and the test results are shown in Table 5 below.

[0044] Table 4

[0045] Table 5

[0046] According to the results in Table 5, aconitate has a good synergistic effect with the absorbing UV additives UV3035 and UV-623, and has a better synergistic UV absorption effect than the reflective anti-UV additives, thereby making the anti-UV performance of the plasticized material PVC more excellent.

[0047] Test Example 2 The experimenters tested the genetic toxicity of the characterization materials according to GB 15193.5-2014 "National Food Safety Standard Mammalian Red Blood Cell Micronucleus Test". Positive results indicate that the test results indicate that the test results indicate that the test results indicate that among the plasticizers, tri-n-butyl aconitate is negative, tri-n-hexyl aconitate is negative, tri-n-octyl aconitate is negative, dibutyl phthalate (DBP) is positive, di(2-ethylhexyl) phthalate (DOP) is positive, and epoxidized soybean oil is negative.

[0048] The bioaccumulation of the material was tested according to GB / T 21853-2008 "Partition Coefficient of Chemicals (n-octanol-water) Shake Flask Test". According to the standard of "Bioaccumulation Test of Chemicals in Sediments for Benthic Oligochaeta Annelida", when the log Pow>3, the material is considered to have a certain bioaccumulation, and when the log Pow<3, the material has no bioaccumulation. The test found that the log Pow of tri-n-butyl aconitate was 2.95, the log Pow of tri-n-hexyl aconitate was 2.96, the log Pow of tri-n-octyl aconitate was 2.97, the log Pow of dibutyl phthalate (DBP) was 4.45, the log Pow of di(2-ethylhexyl) phthalate (DOP) was 7.50, and the log Pow of epoxidized soybean oil was 2.97.

[0049] It can be seen that the addition of aconitate esters to the tram cable sheath material not only has a good plasticizing effect, but also has a good cold-resistant, high-temperature-resistant and UV-resistant effect. Compared with petroleum-based phthalate plasticizers, aconitate esters are environmentally friendly and non-toxic. The plasticized material obtained after adding PVC plasticizer is safer and more environmentally friendly, suitable for human contact, and will not produce toxic side effects.

[0050] According to the experimental results of Examples 1 to 3 of the scheme of the present invention, when aconitate esters with 4≤ ester carbon number≤8 are used for PVC plasticization, a plasticized product with higher tensile strength and suitable elongation at break can be obtained, which is more suitable for industrial molding and processing; at the same time, when the ester carbon number is in this range, aconitate ester can stably exist in the PVC material, is not easy to migrate and volatilize, and can form a good synergistic effect with the absorption-type anti-ultraviolet absorber. The superposition of plasticization and anti-ultraviolet effects makes the PVC plasticized product have better anti-ultraviolet performance and cold resistance, high tensile strength retention rate after aging and elongation at break retention rate after aging, and low low-temperature brittle temperature; aconitate ester plasticizer products are environmentally friendly and non-toxic compared to petroleum-based plasticizers, log Pow<3, and the use of such plasticized products will not affect human health. Due to the particularity of the usage scenarios, tram cables need to be exposed to the outdoor environment for a long time and have a long contact time with the human body. Therefore, the substrate for preparing tram cables has high requirements on cold resistance, high temperature resistance, UV resistance, and non-toxicity and environmental protection. The PVC plasticized product prepared by the present invention meets the requirements of tram cable substrate and is suitable for the production of tram cables for outdoor charging of new energy trams.

[0051] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A tram cable sheath material, characterized in that: The tram cable sheath material comprises the following components by weight: 100 parts of PVC, 20-40 parts of aconitate, 0.5-1 part of an absorption-type anti-ultraviolet additive, 5-10 parts of a flame retardant, 0.5-2 parts of a lubricant, and 1-5 parts of a heat stabilizer.

2. The electric vehicle cable sheath material according to claim 1, characterized in that: The aconitate ester is selected from one or more of tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate, tri-n-octyl aconitate or tri(2-ethylhexyl) aconitate.

3. The electric vehicle cable sheath material according to claim 1, characterized in that: The absorption type anti-ultraviolet additive is selected from one or more of UV-623 and UV3035.

4. The electric vehicle cable sheath material according to claim 1, characterized in that: The flame retardant is selected from one or more of tris(2-chloropropyl) phosphate, aluminum hydroxide or magnesium hydroxide.

5. The electric vehicle cable sheath material according to claim 1, characterized in that: The lubricant is selected from one or more of butyl stearate and chlorinated polyethylene wax.

6. The electric vehicle cable sheath material according to claim 1, characterized in that: The heat stabilizer is selected from one or more of calcium stearate, zinc stearate or methyl tin mercaptan.

7. The electric vehicle cable sheath material according to claim 1, characterized in that: The tram cable sheath material comprises the following components by weight: 100 parts of PVC, 35 parts of aconitate, 0.6 parts of absorption-type anti-ultraviolet additive, 7 parts of flame retardant, 1 part of lubricant, and 3 parts of heat stabilizer.

8. A method for preparing a tram cable comprising the tram cable sheath material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 450-550 rpm, stir for 5-15 min, and obtain an additive mixture; 2) PVC, aconitate and the auxiliary agent mixture obtained in step 1) are mixed and added into a twin-screw extruder, and the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C, and 160°C, the rotation speed is 50-70 rpm, and the extrusion mass flow rate is 30-40 kg / h. After melt blending, the mixture is extruded on the outside of the cable core; 3) The coated cable core is passed through a thermoplastic box to form a protective layer, and finally cooled and solidified to obtain a tram cable including the tram cable sheath.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises the following steps: 1) Add the absorption type anti-ultraviolet additive, flame retardant, lubricant and heat stabilizer to the stirrer, set the speed to 500 rpm, and stir for 10 min to obtain an additive mixture; 2) PVC, aconitate and the auxiliary agent mixture obtained in step 1) are mixed and added into a twin-screw extruder, and the temperature of each zone of the twin-screw is adjusted to 120°C, 130°C, 150°C, 170°C, 170°C, and 160°C, the rotation speed is 60rpm, and the extrusion mass flow rate is 35kg / h. After melt blending, the mixture is extruded on the outside of the cable core; 3) The coated cable core is passed through a thermoplastic box to form a protective layer, and finally cooled and solidified to obtain a tram cable including the tram cable sheath.

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