A low-temperature-resistant, flame-retardant, and UV-resistant PVC cable sheath composition, a preparation method thereof, and a cable

Abstract

The present invention relates to the technical field of cable preparation, and in particular to a low-temperature-resistant, flame-retardant, and UV-resistant PVC cable sheath composition, a preparation method thereof, and a cable. The composition is based on polyvinyl chloride, supplemented with a chlorinated polyethylene elastomer, an environmentally friendly plasticizer, and a calcium-zinc stabilizer, and introduces nano-magnesium hydroxide, zinc stannate, passivated zinc borate, sodium tungstate, and modified montmorillonite to form a multi-component synergistic flame retardant system, which significantly improves the flame retardancy, low smoke properties, and thermal stability of the material. At the same time, through the synergy of ultraviolet absorbers and antioxidants, the weather resistance and service life of the material are enhanced. The prepared cable sheath material has excellent low-temperature flexibility, flame retardant and smoke suppression properties, and ultraviolet aging resistance, and is suitable for high-performance cable applications in harsh environments.

Description

Technical Field

[0001] The present invention relates to the technical field of cable preparation, in particular to a low-temperature resistant, flame-retardant and UV-resistant PVC cable sheath composition, a preparation method thereof and a cable. Background Art

[0002] Polyvinyl chloride (PVC) has been widely used in cable sheathing due to its excellent processing properties, mechanical strength, and low cost. However, with increasingly stringent requirements for cable operating environments in sectors such as power, communications, and industrial automation, traditional formulations alone are unable to simultaneously meet multiple performance requirements, including high and low temperature performance, flame retardancy, UV aging resistance, and low smoke levels. For example, in low-temperature environments (such as those found outdoors in cold regions), conventional PVC sheathing is prone to hardening and cracking. Furthermore, in the event of a fire, some traditional PVC sheathing materials lack flame retardancy and smoke suppression, potentially releasing high concentrations of toxic smoke during combustion and causing secondary damage. Furthermore, cables exposed outdoors for extended periods are subject to UV radiation. Without an effective UV shielding or absorption system, the sheathing material will accelerate aging and cracking, severely impacting the cable's service life.

[0003] In order to improve the comprehensive performance of PVC cable sheath, the industry usually modifies it in the following ways:

[0004] 1. Adding flexible components such as plasticizers and elastomers: Plasticizers (such as DOA and DOP) and elastomers (such as chlorinated polyethylene (CPE)) can give PVC a certain degree of flexibility and low-temperature resistance. However, excessive use of plasticizers can lead to a decrease in the material's mechanical properties and even plasticizer migration. At the same time, the low-temperature performance of general elastomers is limited, making it difficult to meet the application requirements of extreme climates.

[0005] 2. Introducing various inorganic fillers and flame retardants: A typical approach is to inhibit the thermal decomposition and combustion of PVC at high temperatures by adding magnesium hydroxide (Mg(OH)2), aluminum hydroxide (Al(OH)3), or phosphorus-based flame retardants. However, single traditional flame retardants are often accompanied by problems such as high filling content, easy aggregation, poor smoke control, and may have an adverse effect on mechanical properties;

[0006] 3. Use UV absorbers or light stabilizers: Common UV absorbers such as UV-531 and UV-326 can slow down photooxidative degradation to a certain extent, but they often face problems such as easy failure and insufficient compatibility with plasticizers under actual working conditions, resulting in less than ideal overall effect.

[0007] A Chinese invention patent application (publication number: CN102532763A, publication date: July 4, 2012) discloses a chlorinated polyvinyl chloride (CPCV) modified material and its preparation method. The CPCV modified material comprises the following ingredients: 40-90 parts CPCV; 20-70 parts PVC; 5-30 parts modified resin; 1.5-10 parts heat stabilizer; 20-60 parts plasticizer; 1-10 parts antioxidant; 1-10 parts lubricant; 5-40 parts filler; 8-40 parts flame retardant; 8-40 parts flame retardant synergist; and 1-20 parts PVC processing aid. The flame retardant is surface-treated antimony trioxide, aluminum hydroxide, or any mixture thereof, and the flame retardant synergist is zinc borate, ammonium molybdate, or a mixture thereof. CPVC-modified materials offer superior physical and mechanical properties at a relatively lower cost. Compared to CPVC, this invention not only offers superior processability and significantly improved brittleness and impact resistance, but also significantly enhanced heat resistance and flame retardancy (with an oxygen index of approximately 45%, allowing a single strand to burn vertically). However, this patent relies excessively on conventional flame retardants such as antimony trioxide and aluminum hydroxide. The high loading may not only significantly degrade mechanical properties, but also limit the control of smoke and toxicity generated by combustion. Summary of the Invention

[0008] In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a low-temperature resistant, flame-retardant and UV-resistant PVC cable sheath composition, by introducing an environmentally friendly calcium zinc stabilizer, a chlorinated polyethylene elastomer, a plasticizer and a specific flame-retardant filler compound system into the PVC matrix. At the same time, with the synergistic effect of multiple flame retardant and smoke suppression systems such as nano-magnesium hydroxide, modified montmorillonite, sodium tungstate and zinc stannate-passivated zinc borate, it can not only form a stable flame retardant protective layer and absorb a large amount of heat during combustion, but also effectively reduce the amount of smoke released. In addition, the combined use of carbon black powder and ultraviolet absorber can significantly improve the weather resistance of the sheath material under outdoor ultraviolet light; and the introduction of silane coupling agent improves the bonding degree between the nano-scale inorganic component and the organic matrix, so that the overall material has high strength, good flexibility and long life characteristics.

[0009] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0010] A low-temperature-resistant, flame-retardant, and UV-resistant PVC cable sheath composition is prepared by mixing the following raw materials, in parts by weight:

[0011] 100 parts of polyvinyl chloride resin;

[0012] 10-15 parts of chlorinated polyethylene elastomer;

[0013] 4-8 parts of environmentally friendly calcium zinc stabilizer;

[0014] 15-25 parts of carbon ten plasticizer;

[0015] 10-15 parts of dioctyl adipate;

[0016] 10-20 parts of nano-magnesium hydroxide;

[0017] 2-5 parts of zinc stannate;

[0018] 3-6 parts of passivated zinc borate;

[0019] 2-5 parts of modified montmorillonite;

[0020] 1-3 parts of sodium tungstate;

[0021] 3-5 parts of carbon black powder;

[0022] 0.2-0.5 parts of antioxidant;

[0023] 0.3-0.8 parts of ultraviolet absorber;

[0024] Silane coupling agent 0.5-1 part.

[0025] Preferably, the composition is prepared by mixing the following raw materials, in parts by weight:

[0026] 100 parts of polyvinyl chloride resin;

[0027] 12-14 parts of chlorinated polyethylene elastomer;

[0028] 5-7 parts of environmentally friendly calcium zinc stabilizer;

[0029] 18-22 parts of carbon ten plasticizer;

[0030] 12-14 parts of dioctyl adipate;

[0031] 12-18 parts of nano-magnesium hydroxide;

[0032] 3-4 parts of zinc stannate;

[0033] 4-5 parts of passivated zinc borate;

[0034] 3-4 parts of modified montmorillonite;

[0035] 1.5-2.5 parts of sodium tungstate;

[0036] 3.5-4.5 parts of carbon black powder;

[0037] 0.3-0.4 parts of antioxidant;

[0038] 0.4-0.7 parts of ultraviolet absorber;

[0039] 0.6-0.8 parts of silane coupling agent.

[0040] Preferably, the modified montmorillonite is montmorillonite that has been subjected to an organic or silanized treatment, and its lamellar structure is fully compatible with the polyvinyl chloride matrix and the plasticizer system during the mixing process.

[0041] Preferably, the modified montmorillonite is a silane coupling agent or a modified montmorillonite treated with a quaternary ammonium salt.

[0042] Preferably, the ultraviolet absorber is selected from UV-531, UV-5411, UV-326 or a mixture thereof; and the antioxidant is selected from hindered phenol antioxidants and / or organic phosphonate antioxidants.

[0043] Preferably, the silane coupling agent is selected from APTES or GPTMS.

[0044] Furthermore, the present invention also discloses a method for preparing the composition, comprising the following steps:

[0045] (1) Premixing: Add polyvinyl chloride resin, chlorinated polyethylene elastomer, environmentally friendly calcium zinc stabilizer, carbon ten plasticizer, dioctyl adipate, antioxidant and ultraviolet absorber into a high-speed mixer in proportion, control the stirring temperature at 80-120°C, and mix for 5-15 minutes;

[0046] (2) Adding inorganic fillers and modified components: Add nano-magnesium hydroxide, zinc stannate, passivated zinc borate, modified montmorillonite, sodium tungstate, carbon black powder and silane coupling agent to the above premix, and continue mixing at high speed for 3 to 10 minutes to evenly disperse the components;

[0047] (3) Extrusion granulation: The uniformly mixed material is extruded into granules in a twin-screw extruder. The extrusion temperature is controlled at 160-190°C and the screw speed is 50-120 rpm to obtain low-temperature resistant, flame-retardant and anti-ultraviolet PVC cable sheath granules.

[0048] Preferably, the rotation speed of the high-speed mixer is 300-1000 rpm, and the mixing process is carried out in an inert gas protection environment.

[0049] Preferably, the temperature of each section in the twin-screw extruder is set to: 160-165°C in the first section, 165-175°C in the second section, 175-185°C in the third section, and 180-190°C in the final section to ensure that the modified montmorillonite, sodium tungstate and other additives are fully dispersed in the resin matrix.

[0050] Furthermore, the present invention also discloses a low-temperature-resistant, flame-retardant, and UV-resistant PVC cable, which comprises a conductor and a sheath prepared from the composition.

[0051] The low-temperature-resistant, flame-retardant, and UV-resistant PVC cable sheath composition provided by this invention innovatively constructs a composite synergistic flame-retardant system based on nano-magnesium hydroxide, supplemented with zinc stannate, passivated zinc borate, sodium tungstate, and modified montmorillonite. These components work synergistically through multiple mechanisms, including physical shielding, heat absorption and cooling, catalytic carbonization, and free radical inhibition, significantly improving the material's flame retardancy and effectively reducing smoke density and toxicity. The specific synergistic mechanism is as follows:

[0052] (1) Synergy of thermal decomposition and heat absorption and cooling of nano-magnesium hydroxide: The present invention adopts nano-magnesium hydroxide, which undergoes a rapid thermal decomposition reaction (Mg(OH)2→MgO+H2O↑) during the combustion process. The water vapor produced by the decomposition can quickly dilute the oxygen and combustible gas concentrations in the combustion zone, accompanied by a significant heat absorption effect, effectively reducing the combustion temperature of the material surface, and providing a temperature control basis for the subsequent flame retardant effect.

[0053] (2) Synergistic carbonization catalysis and smoke suppression of zinc stannate and passivated zinc borate: Zinc stannate and passivated zinc borate synergistically catalyze the PVC matrix to form a continuous and dense carbonized protective layer under high-temperature combustion environment. Zinc stannate promotes rapid carbonization of the surface and inhibits the generation of smoke, while passivated zinc borate generates a low-melting-point glassy liquid phase at high temperature, further improving the density and durability of the carbonized layer, effectively reducing the rate and concentration of smoke and toxic gas release, and improving the overall flame retardant effect and safety of the system.

[0054] (3) Synergy between free radical inhibition and smoke reduction of sodium tungstate: As a special free radical scavenger and catalyst, sodium tungstate can effectively capture and terminate the hydroxyl radicals (•OH) and hydrogen radicals (•H) produced during the combustion of PVC, significantly reducing the combustion reaction rate. At the same time, sodium tungstate catalyzes the further carbonization of PVC, reducing the release concentration of smoke and harmful volatile gases, thereby achieving the dual synergistic effects of gas phase flame retardancy and smoke suppression.

[0055] (4) Synergy between the physical barrier and interface enhancement of modified montmorillonite: The present invention uses silane coupling agents or quaternary ammonium salts to modify the surface of montmorillonite to produce a nano-scale lamellar structure with large interlayer spacing and good dispersibility. When the modified montmorillonite is heated in a PVC matrix, it quickly forms a dense and stable physical barrier layer, effectively inhibiting the further diffusion of heat, oxygen, and combustible gases. At the same time, the interface between the modified montmorillonite and PVC formed by the silane coupling agent effectively improves the mechanical properties of the material and the overall flame retardant stability of the system.

[0056] By combining these components, the flame-retardant system of the present invention achieves the synergistic effects of multiple flame-retardant mechanisms: solid-phase shielding, heat absorption and cooling, catalytic carbonization, and gas-phase free radical capture. This effectively addresses the issues inherent in traditional PVC sheathing materials, such as the high dosage of a single flame-retardant component, severe mechanical performance degradation, and limited control over smoke density and toxicity. While significantly improving the flame-retardant efficiency of PVC materials, it also significantly reduces smoke concentration and toxic gas production during combustion, fundamentally enhancing the safety and environmental performance of cable materials in fire environments.

[0057] Furthermore, the present invention effectively improves the flexibility and impact resistance of PVC sheathing materials in low-temperature environments by introducing a composite plasticizer system composed of chlorinated polyethylene elastomer (CPE), a carbon-10 plasticizer, and dioctyl adipate. This effectively addresses the technical issues of traditional PVC cable sheaths that tend to harden and crack at low temperatures, enabling the material to be stably used in extreme environments of -40°C or even lower. Furthermore, the modified montmorillonite used in the present invention undergoes organic modification with a silane coupling agent or quaternary ammonium salt, effectively improving its compatibility with the PVC matrix. This allows the nano-montmorillonite flakes to be fully exfoliated and evenly dispersed within the polymer matrix, significantly enhancing the material's flame retardant synergy and mechanical strength. Furthermore, the silane coupling agent (such as APTES or GPTMS) further enhances the interfacial bonding strength between other inorganic additives, such as nano-magnesium hydroxide and sodium tungstate, and the PVC resin, effectively preventing additive agglomeration and further optimizing the material's processing performance and stability.

[0058] In summary, the low-temperature resistant, flame-retardant and UV-resistant PVC cable sheath composition provided by the present invention successfully achieves the synergistic improvement of comprehensive performance such as high-efficiency flame retardancy, low smoke and toxicity suppression, excellent low-temperature flexibility and significant resistance to UV aging. It is suitable for cable outer sheath applications in extreme climate environments and special requirements, and has significant economic and social benefits. DETAILED DESCRIPTION

[0059] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0060] 1. Preparation of Examples and Comparative Examples

[0061] The sources of raw materials for the examples and comparative examples of the present invention are shown in Table 1.

[0062] Table 1 Specific sources of the main raw materials in the examples and comparative examples

[0063]

[0064] The following performance comparisons are made through Examples 1 to 3 and Comparative Examples 1 to 6, and the formulations are shown in Tables 2 and 3. This is to verify the significant improvement effect of the synergistic flame retardant system on the flame retardancy, low smoke, UV resistance and low temperature performance of the material.

[0065] Table 2 Raw material components of the embodiment (parts by weight)

[0066]

[0067] Table 3 Raw material components of comparative example (parts by weight)

[0068]

[0069] The preparation methods of Examples 1 to 3 and Comparative Examples 1 to 6 are as follows, wherein a raw material is omitted if it is not used:

[0070] (1) Premixing: Add polyvinyl chloride resin, chlorinated polyethylene elastomer, environmentally friendly calcium zinc stabilizer, carbon ten plasticizer, dioctyl adipate, antioxidant and ultraviolet absorber into a high-speed mixer in proportion, control the stirring temperature at 105°C, and mix for 10 minutes;

[0071] (2) Adding inorganic fillers and modified components: Add nano-magnesium hydroxide, zinc stannate, passivated zinc borate, modified montmorillonite, sodium tungstate, carbon black powder and silane coupling agent to the above premix, and continue mixing at high speed for 8 minutes to evenly disperse the components;

[0072] (3) Extrusion granulation: The uniformly mixed material is extruded and granulated in a twin-screw extruder. The extrusion temperature is controlled at 180°C and the screw speed is 80 rpm to obtain low-temperature resistant, flame-retardant and UV-resistant PVC cable sheath granules.

[0073] Comparative Example 7 is based on Example 1 disclosed in Chinese invention patent application (publication number: CN102532763A, publication date: 2012-07-04).

[0074] 2. Test Method

[0075] The following are the specific procedures and reference standards of the test methods involved in the examples and comparative examples:

[0076] (1) Flame retardant performance test method

[0077] 1. Oxygen Index (LOI) Test

[0078] Based on the standard: GB / T 2406.2-2009 "Determination of combustion behavior of plastics using the oxygen index method";

[0079] Instruments and equipment: oxygen index tester (such as JF-3 oxygen index tester);

[0080] Specimen specifications: long strip specimen (length 100mm × width 10mm × thickness 3mm);

[0081] Test procedure: Fix the sample vertically in the test fixture and ignite the top of the sample; adjust the ratio of oxygen and nitrogen to determine the minimum oxygen concentration required for the sample to continue burning for just 3 minutes; repeat the test 3 times and take the average value as the oxygen index of the sample.

[0082] 2. Vertical burning rating test (UL-94)

[0083] Based on the standard: GB / T 2408-2008 (equivalent to UL-94) "Plastics - Determination of Combustion Performance - Vertical Method";

[0084] Instruments and equipment: UL-94 vertical burning tester;

[0085] Specimen specifications: length 125mm × width 13mm × thickness 3mm;

[0086] Test procedure: Fix the sample vertically in the combustion box, with the bottom end 10mm away from the top of the burner; use a flame (20mm height) to burn the bottom end of the sample twice, each time for 10 seconds; observe the afterflame and afterburning time after the fire source is removed, and whether the dripping material ignites the cotton wool at the bottom; assess the grade based on the afterflame, afterburning, and dripping: V-0, V-1, V-2, etc.

[0087] (2) Smoke density test

[0088] Based on the standard: GB / T 8323.2-2008 "Plastics smoke density test method single chamber method";

[0089] Instruments and equipment: NBS smoke density tester;

[0090] Sample specifications: square sheet, size 75mm×75mm×3mm;

[0091] Test procedure: The sample is fixed vertically in a specific position in the combustion chamber, and a 25kW / m² radiant heat source and open flame are applied. The changes in light transmittance during combustion are recorded, and the smoke density curve over time is automatically recorded. The maximum smoke density value (Dm) during the sample combustion process is measured and recorded. Each sample is tested three times and the average value is taken.

[0092] (3) Low temperature bending performance test

[0093] Based on the standard: GB / T 2951.14-2008 "General test methods for cable insulation and sheath materials";

[0094] Test temperature: -40℃;

[0095] Instruments and equipment: low temperature test chamber, standard bending fixture;

[0096] Sample specifications: Cable sheath sample length 100mm;

[0097] Test process: Keep the sample in a -40°C low-temperature box for 4 hours; remove the sample and quickly bend it 180° around a cylinder of specified diameter (10 times the cable outer diameter) within 10 seconds; check whether the surface of the sample has cracks or breaks; each sample is tested 3 times, and it passes if no cracks or breaks are found.

[0098] (IV) Anti-ultraviolet aging performance test

[0099] Based on the standard: GB / T 16422.3-2014 "Plastics laboratory light source exposure test method Part 3: Fluorescent ultraviolet lamp";

[0100] Instruments and equipment: UV aging test chamber (fluorescent UV lamp, UVA-340);

[0101] Specimen specifications: dumbbell-shaped specimen, thickness 3mm, in line with GB / T 1040.2 tensile test requirements;

[0102] Testing procedure: The specimens were fixed in a UV aging test chamber, set at an irradiance of 0.68 W / m², a blackboard temperature of 60°C, and a light / condensation cycle (8 hours of light, 4 hours of condensation), for 250 hours of continuous aging. The tensile strength of the specimens was measured before and after the test, and the post-aging strength retention (%) was recorded: Strength retention = post-aging tensile strength × initial tensile strength × 100%. Five specimens of each sample were tested and the average value was taken.

[0103] (V) Mechanical properties test (auxiliary verification)

[0104] Based on the standard: GB / T 1040.2-2006 "Test method for tensile properties of plastics";

[0105] Instruments and equipment: universal testing machine;

[0106] Specimen specifications: dumbbell-shaped specimen, thickness 3mm, length ≥150mm;

[0107] Test procedure: Mount the specimen in a universal testing machine, set the grip distance to 100 mm, and the tensile rate to 50 mm / min. Record the maximum tensile strength and elongation at break, taking the average of three specimens.

[0108] (VI) Thermal aging performance test method

[0109] Test standard: GB / T 2951.12-2008 "General test methods for cable insulation and sheath materials".

[0110] Testing instruments: electric constant temperature drying oven, universal testing machine.

[0111] Specimen specifications: Dumbbell-shaped specimens same as those for tensile test.

[0112] Test process: The sample is placed in a constant temperature oven at 100℃ and aged continuously for 168 hours (7 days). After aging, the sample is cooled at room temperature for 24 hours, and the tensile strength and elongation at break are measured. The change rate is calculated based on the changes in strength and elongation before and after the test.

[0113] In the present invention, no specific test method is given, and conventional test methods are adopted.

[0114] Detailed experimental data of Examples 1 to 3 and Comparative Examples 1 to 7 are given below (as shown in Table 4) to fully present the technical effects of the present invention.

[0115] Table 4 Experimental data of Examples 1-3 and Comparative Examples 1-7

[0116]

[0117] Through systematic comparative experiments of Comparative Examples 1 to 7 and Examples 1 to 3, it is proved that the flame retardant system (nano-magnesium hydroxide / zinc stannate / passivated zinc borate / modified montmorillonite / sodium tungstate) constructed in the present invention has excellent synergistic effects, can significantly improve the flame retardancy, smoke suppression performance, low-temperature flexibility, thermal stability and anti-ultraviolet aging performance of PVC cable sheath materials, and reflects the technical innovation and outstanding technical effects of the formula design of the present invention.

[0118] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-temperature resistant, flame-retardant, and UV-resistant PVC cable sheath composition, characterized in that: The composition is prepared by mixing the following raw materials by weight: 100 parts of polyvinyl chloride resin; 10-15 parts of chlorinated polyethylene elastomer; 4-8 parts of environmentally friendly calcium zinc stabilizer; 15-25 parts of carbon ten plasticizer; 10-15 parts of dioctyl adipate; 10-20 parts of nano-magnesium hydroxide; 2-5 parts of zinc stannate; 3-6 parts of passivated zinc borate; 2-5 parts of modified montmorillonite; 1-3 parts of sodium tungstate; 3-5 parts of carbon black powder; 0.2-0.5 parts of antioxidant; 0.3-0.8 parts of ultraviolet absorber; Silane coupling agent 0.5-1 part; The modified montmorillonite is a silane coupling agent or a modified montmorillonite treated with a quaternary ammonium salt.

2. The composition according to claim 1, characterized in that The composition is prepared by mixing the following raw materials by weight: 100 parts of polyvinyl chloride resin; 12-14 parts of chlorinated polyethylene elastomer; 5-7 parts of environmentally friendly calcium zinc stabilizer; 18-22 parts of carbon ten plasticizer; 12-14 parts of dioctyl adipate; 12-18 parts of nano-magnesium hydroxide; 3-4 parts of zinc stannate; 4-5 parts of passivated zinc borate; 3-4 parts of modified montmorillonite; 1.5-2.5 parts of sodium tungstate; 3.5-4.5 parts of carbon black powder; 0.3-0.4 parts of antioxidant; 0.4-0.7 parts of ultraviolet absorber; 0.6-0.8 parts of silane coupling agent.

3. The composition according to claim 1, characterized in that The ultraviolet absorber is selected from UV-531, UV-5411, UV-326 or a mixture thereof; the antioxidant is selected from hindered phenol antioxidants and / or organic phosphonate antioxidants.

4. The composition according to claim 1, characterized in that The silane coupling agent is selected from APTES or GPTMS.

5. The method for preparing the composition according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Premixing: Add polyvinyl chloride resin, chlorinated polyethylene elastomer, environmentally friendly calcium zinc stabilizer, carbon ten plasticizer, dioctyl adipate, antioxidant and ultraviolet absorber into a high-speed mixer in proportion, control the stirring temperature at 80-120°C, and mix for 5-15 minutes; (2) Adding inorganic fillers and modified components: Add nano-magnesium hydroxide, zinc stannate, passivated zinc borate, modified montmorillonite, sodium tungstate, carbon black powder and silane coupling agent to the above premix, and continue mixing at high speed for 3 to 10 minutes to evenly disperse the components; (3) Extrusion granulation: The uniformly mixed material is extruded into granules in a twin-screw extruder. The extrusion temperature is controlled at 160-190°C and the screw speed is 50-120 rpm to obtain low-temperature resistant, flame-retardant and anti-ultraviolet PVC cable sheath granules.

6. The preparation method according to claim 5, characterized in that The rotation speed of the high-speed mixer is 300-1000 rpm, and the mixing process is carried out in an inert gas protection environment.

7. The preparation method according to claim 5, characterized in that The temperature of each section in the twin-screw extruder is set to: 160-165°C in the first section, 165-175°C in the second section, 175-185°C in the third section, and 180-190°C in the final section to ensure that the modified montmorillonite, sodium tungstate and other additives are fully dispersed in the resin matrix.

8. A low-temperature resistant, flame-retardant, and UV-resistant PVC cable, characterized in that: The cable comprises a conductor and a sheath prepared from the composition according to any one of claims 1 to 4.

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