Insulation-grade high-voltage-resistant flame-retardant polyvinyl chloride sheath material and preparation method thereof

Abstract

The invention relates to the field of cable sheath materials, in particular to an insulation-grade high-voltage-resistant flame-retardant polyvinyl chloride sheath material and a preparation method thereof. The sheath material comprises the following components in parts by weight: 100 parts of polyvinyl chloride, 35-45 parts of a plasticizer A, 3-7 parts of a plasticizer B, 15-20 parts of aluminum hydroxide, 5-7 parts of a stabilizer, 10-14 parts of calcined clay, 0.5-0.8 part of polyethylene wax, 2-5 parts of a flame retardant, 15-25 parts of calcium carbonate and 5-7 parts of chlorinated polyethylene. In the debugging process, the high-electrical-property stabilizer and the high-purity calcined pottery clay are added to serve as materials for improving the volume resistance, the flame retardant and chlorinated polyethylene formula systems are matched, and by means of the system matching, the better mechanical property and the better insulating and flame-retardant property can be obtained at the same time.

Description

Technical Field

[0001] This invention relates to the field of cable sheathing materials, and in particular to an insulating-grade, high-voltage resistant, flame-retardant polyvinyl chloride sheathing material and its preparation method. Background Technology

[0002] With the rapid development of the global power and communications industries, the demand for high-performance cable materials is increasing. Especially in fields such as urban rail transit, high-voltage power transmission, and special electronic equipment, cables, as the core medium for energy and information transmission, are of paramount importance in terms of safety and reliability. Polyvinyl chloride (PVC), due to its excellent mechanical properties, electrical insulation, and cost advantages, has long been widely used as insulation and sheathing material for wires and cables.

[0003] However, as people's requirements for equipment safety and system reliability continue to increase, traditional PVC sheathing materials have gradually exposed a series of problems, especially in terms of high-pressure resistance and flame retardancy. The volume resistivity standard for PVC sheathing materials at 90℃ specified in GB / T8815-2008 is 1.0 × 10⁻⁶. 9 The current standard for 90℃ PVC sheathing materials used in high-voltage power transmission networks (66kV and above) needs to meet certain insulation performance requirements, and the volume resistivity standard for the sheathing material needs to be increased to 5.0×10 Ω·m. 12 With some cables requiring even higher volume resistivity (Ω·m), the development of a PVC sheath material that combines excellent insulation performance, high-voltage resistance, and flame retardant properties has become an urgent need for the industry. This new material can not only improve the safe operation of cables but also ensure the stability and reliability of systems in complex environments, thus providing solid technical support for the development of the power and communications industries. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low high pressure resistance and poor flame retardant effect in the prior art, thereby providing a stable and reliable polyvinyl chloride (PVC) sheath material.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing insulating-grade high-voltage resistant flame-retardant polyvinyl chloride sheathing material, comprising the following steps: S11: By weight, mix 100 parts polyvinyl chloride (PVC), 35-45 parts plasticizer A, 3-7 parts plasticizer B, 15-20 parts aluminum hydroxide, 5-7 parts stabilizer, 10-14 parts calcined clay, 0.5-0.8 parts polyethylene wax, 2-5 parts flame retardant, 15-25 parts calcium carbonate and 5-7 parts chlorinated polyethylene (CPE, CAS No. 63231-66-3, model 135A, molecular weight 4w-30w) to obtain the raw material for sheath processing; S12: The raw material for sheath processing is extruded and granulated to obtain sheath molding material; S13: Cool the sheath molding material to room temperature (25°C) to obtain the insulating grade high voltage resistant flame retardant polyvinyl chloride sheath material.

[0006] In the debugging process, this invention adds a high-electric stabilizer and high-purity calcined clay as materials to improve volume resistivity, and combines them with a composite flame retardant and chlorinated polyethylene formulation system. The combination of the above system can simultaneously obtain better mechanical properties and insulation and flame retardant properties.

[0007] Preferably, in step S11, the mixing method is as follows: S21: By weight, mix 100 parts of polyvinyl chloride, 35-45 parts of plasticizer A, 3-7 parts of plasticizer B, 5-7 parts of stabilizer, 0.5-0.8 parts of polyethylene wax and 2-5 parts of flame retardant at a speed of 200-300 rpm for 50-70 seconds, and then heat and mix at a speed of 700-800 rpm and 75-85℃ to obtain the first mixture; S22: By weight, add 15-20 parts of aluminum hydroxide, 10-14 parts of calcined clay and 15-25 parts of calcium carbonate to the first mixture and heat and mix at 120-140°C to obtain the second mixture; S23: Add 5-7 parts by weight of chlorinated polyethylene to the second mixture and mix for 25-35 seconds.

[0008] Preferably, the polyvinyl chloride is polyvinyl chloride resin powder, model SG-3, with a degree of polymerization of 1200-1400.

[0009] Preferably, plasticizer A is dioctyl terephthalate (DOTP), and plasticizer B is epoxidized soybean oil (CAS No. 8013-07-8).

[0010] Preferably, the volume resistivity of the dioctyl terephthalate is not less than 2.0*10⁻⁶. 10 Ω·m, flash point (open cup) is 210℃.

[0011] Preferably, the polyethylene wax is a low molecular weight polyethylene homopolymer with CAS number 9002-88-4, a density of 0.93-0.98, a melting point of 90-120℃, and a molecular weight of 1500-5000.

[0012] Preferably, the flame retardant is a silicon-magnesium composite flame retardant (purchased from Shanghai Lianggao, model Z-S20C).

[0013] Preferably, the stabilizer is a calcium-zinc stabilizer (purchased from Changzhou Ruidin, model RDC8028).

[0014] Preferably, the whiteness of the calcined clay is 84-86% (purchased from Shanxi Jinyu, model HP-90B).

[0015] Preferably, in step S12, a twin-screw extruder is used for extrusion, and a single-screw extruder is used for granulation; when the twin-screw extruder is used for extrusion, the temperature of the twin-screw extruder is: Zone 1: 95-105℃, Zone 2: 105-115℃, Zone 3: 110-120℃, Zone 4: 115-125℃, Zone 5: 120-130℃, Zone 6: 125-135℃, Zone 7: 130-140℃, Zone 8: 135-145℃.

[0016] Preferably, in step S13, the cooling method is air cooling.

[0017] The present invention also provides an insulating-grade high-voltage resistant flame-retardant polyvinyl chloride sheath material prepared by the above preparation method.

[0018] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: This invention aims to provide a high-performance, high-voltage, flame-retardant PVC sheathing material with superior insulation properties, addressing the shortcomings of existing technologies and driving industry development. By optimizing raw material selection and formulation design, this invention significantly improves the high-voltage resistance and flame-retardant characteristics of the material while ensuring good electrical insulation. Furthermore, this technology emphasizes environmental performance, effectively reducing the release of toxic gases during combustion, aligning with current green and environmentally friendly development trends. From an industry perspective, the application of this patented technology will help improve the overall performance of cable products, reduce safety hazards caused by material aging or fire accidents, and thus provide strong support for the sustainable development of the power and communications sectors. Simultaneously, the successful development of this technology also provides new ideas and methods for the modification research of PVC sheathing materials, possessing significant theoretical and practical value. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 This is a physical image of the insulating-grade high-voltage resistant flame-retardant polyvinyl chloride sheath material of Embodiment 1 of the present invention; Figure 2 This is a physical image of a cable made from the insulating, high-voltage resistant, flame-retardant polyvinyl chloride sheath material of Embodiment 1 of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] Example 1:

[0023] The formulation of this embodiment consists of: 100 kg of PVC resin powder (model SG-3, degree of polymerization 1200-1400), 42 kg of DOTP, 3 kg of epoxidized soybean oil, 15 kg of aluminum hydroxide, 5 kg of calcium-zinc stabilizer, 10 kg of calcined clay (purchased from Shanxi Jinyu, model HP-90B), 0.8 kg of polyethylene wax (CAS number 9002-88-4, molecular weight 1500-5000), 3 kg of silicon-magnesium composite flame retardant (purchased from Shanghai Lianggao, model Z-S20C), 25 kg of calcium carbonate, and 5 kg of CPE (CPE, CAS number 63231-66-3, model 135A, molecular weight 4w-30w).

[0024] Processing technology: This product is uniformly mixed using a Guangdong Sanyou high-efficiency mixing pot (model SM-750L), processed by twin-screw extrusion, then granulated by single-screw extrusion, and finally air-cooled conveying and packaging of the finished product. The specific production process is as follows: a. Add 100 kg of PVC resin powder, 42 kg of DOTP plasticizer, 3 kg of epoxidized soybean oil plasticizer, 5 kg of calcium-zinc stabilizer, 0.8 kg of polyethylene wax, and 3 kg of silicon-magnesium composite flame retardant to a high-speed mixing pot. Start the high-speed mixing pot and mix at 200 rpm for 1 minute, then mix at high speed until the material temperature reaches 80℃, and then mix at 800 rpm. Next, add 15 kg of aluminum hydroxide, 25 kg of calcium carbonate, and 10 kg of calcined clay with a whiteness of 85%, and mix at high speed until the temperature reaches 130℃. Finally, add 5 kg of CPE and stir for 30 seconds.

[0025] b. Feed the well-mixed raw materials directly into the twin-screw extruder. The twin-screw extruder temperatures are: Zone 1: 100℃, Zone 2: 110℃, Zone 3: 115℃, Zone 4: 120℃, Zone 5: 125℃, Zone 6: 130℃, Zone 7: 135℃, Zone 8: 140℃.

[0026] c. Add the twin-screw extruded material to a single-screw extruder for granulation. The single-screw extrusion temperature is: Zone 1: 90℃, Zone 2: 95℃, and Die head: 130℃.

[0027] d. After granulation, air-cool the granules to 25°C and package the finished product.

[0028] Example 2:

[0029] The method is the same as in Example 1, except that the amount of calcined clay added is 12 kg.

[0030] Example 3:

[0031] The method is the same as in Example 1, except that the amount of calcium-zinc stabilizer added is 6 kg and the amount of calcined clay added is 14 kg.

[0032] Example 4:

[0033] The method is the same as in Example 1, except that the amount of calcium-zinc stabilizer added is 7 kg, the amount of calcined clay added is 14 kg, and the amount of calcium carbonate added is 20 kg.

[0034] Comparative Example 1: The method is the same as in Example 1, except that the amount of calcined clay added is 8 kg.

[0035] Comparative Example 2: The method is the same as in Example 1, except that no calcined clay is added.

[0036] Table 1. Composition schemes of the examples and comparative examples (unit: kg)

[0037] Effect evaluation: In this invention, the reference standard for density is GB / T1033-2008; the reference standards for tensile strength and elongation at break are GB / T1040-2006; the reference standard for low-temperature embrittlement is GB / T5470-2008; the reference standard for oxygen index is GB / T2406-2009; and the reference standard for volume resistivity is GB / T1410-2006. The examples and comparative examples were tested using the above standards, and the results are shown in Table 2.

[0038] Table 2 Performance Test Data

[0039] Experimental results show that the insulation and mechanical properties of the product obtained by this invention are superior to those of traditional materials. (1) Calcination of clay can improve the mechanical properties (such as strength and hardness) and heat resistance of PVC cable materials, while also enhancing electrical insulation performance. Its high-temperature insulation performance can ensure the safety of cable use; (2) Calcium-zinc stabilizers in cable materials need to pass the volume resistivity test. The formula can improve electrical insulation performance by adding calcined kaolin to ensure electrical safety. (3) This invention uses a silicon-magnesium composite flame retardant as a substitute for antimony trioxide, which can effectively reduce costs and provide better flame retardant performance. The price of antimony trioxide has been rising continuously in recent years, and the supply is tight, which has promoted the research and development and application of alternative materials such as composite flame retardants.

[0040] The main advantage of this invention is its excellent insulation performance, with a volume resistivity of up to 3.2*10⁻⁶. 13 Ω.m and above, suitable for high voltage and ultra-high voltage cables.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an insulating, high-voltage resistant, flame-retardant polyvinyl chloride sheathing material, characterized in that, Includes the following steps: S11: By weight, mix 100 parts polyvinyl chloride, 35-45 parts plasticizer A, 3-7 parts plasticizer B, 15-20 parts aluminum hydroxide, 5-7 parts stabilizer, 10-14 parts calcined clay, 0.5-0.8 parts polyethylene wax, 2-5 parts flame retardant, 15-25 parts calcium carbonate and 5-7 parts chlorinated polyethylene to obtain the raw material for sheath processing; S12: The raw material for sheath processing is extruded and granulated to obtain sheath molding material; S13: Cool the sheath molding material to room temperature to obtain the insulating grade high-voltage flame-retardant polyvinyl chloride sheath material.

2. The preparation method according to claim 1, characterized in that: In step S11, the mixing method is as follows: S21: By weight, mix 100 parts of polyvinyl chloride, 35-45 parts of plasticizer A, 3-7 parts of plasticizer B, 5-7 parts of stabilizer, 0.5-0.8 parts of polyethylene wax and 2-5 parts of flame retardant at a speed of 200-300 rpm for 50-70 seconds, and then heat and mix at 75-85℃ and 700-800 rpm to obtain the first mixture; S22: By weight, add 15-20 parts of aluminum hydroxide, 10-14 parts of calcined clay and 15-25 parts of calcium carbonate to the first mixture and heat and mix at 120-140°C to obtain the second mixture; S23: Add 5-7 parts by weight of chlorinated polyethylene to the second mixture and mix for 25-35 seconds.

3. The preparation method according to claim 1, characterized in that: The polyvinyl chloride is polyvinyl chloride resin powder with a degree of polymerization of 1200-1400.

4. The preparation method according to claim 1, characterized in that: Plasticizer A is dioctyl terephthalate, and plasticizer B is epoxidized soybean oil.

5. The preparation method according to claim 1, characterized in that: The flame retardant is a silicon-magnesium composite flame retardant.

6. The preparation method according to claim 1, characterized in that: The stabilizer is a calcium-zinc stabilizer.

7. The preparation method according to claim 1, characterized in that: The whiteness of the calcined clay is 84-86%.

8. The preparation method according to claim 1, characterized in that: In step S12, a twin-screw extruder is used for extrusion, and a single-screw extruder is used for granulation.

9. The preparation method according to claim 1, characterized in that: In step S13, the cooling method is air cooling.

10. An insulating-grade, high-voltage resistant, flame-retardant polyvinyl chloride sheath material prepared by the preparation method according to any one of claims 1-9.

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