Preparation method of high-temperature-resistant easy-to-tear PVC (polyvinyl chloride) cable material and product thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a preparation method of a high-temperature-resistant easy-to-tear PVC (polyvinyl chloride) cable material and a product thereof, and the preparation method comprises the following steps: mixing diatomite and mica according to a mass ratio, introducing a silane coupling agent into a reaction kettle after mixing, heating, adding a reactive compatilizer, and reacting to obtain a dual modified filler; mixing magnesium hydroxide with phytic acid, grinding, and drying to obtain phytic acid coated modified magnesium hydroxide; the preparation method comprises the following steps: adding pvc resin and other auxiliaries into an internal mixer, heating, and then adding dicumyl peroxide to obtain a premix with a sea-island structure; dividing the premix into an inner layer and an outer layer, adding nano montmorillonite and modified magnesium hydroxide into the inner layer, adding double modified filler into the outer layer, cooling, cutting and granulating to obtain the high-temperature-resistant easy-to-tear PVC cable material. The prepared high-temperature-resistant easy-to-tear PVC cable material can form a weak interface layer when the material is subjected to mechanical action, controllable tearing is achieved, and the environment-friendly and flame-retardant effects are achieved by adding the green flame retardant.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a preparation method and a product of a high-temperature resistant and easily tearable PVC cable material. Background Art

[0002] PVC (polyvinyl chloride) is a very widely used general-purpose plastic. Due to its excellent physical and mechanical properties, electrical properties, flame retardant properties, and good oil resistance, corona resistance, chemical corrosion resistance, and water resistance, and its low price and excellent processing performance, it is widely used as an insulating material for wires and cables. The polyvinyl chloride used for wires and cables has a relatively high temperature resistance grade of 90 °C as specified in GB / T8815-2002, and wire and cable materials need to have a certain high-temperature resistance. And during the recycling process of wires and cables, it is necessary to separate the wire core from the sheath layer. In the prior art, there is a lack of cable materials that can be applied to occasions that require frequent peeling (such as when connecting equipment and electrical boxes, during wire maintenance or replacement), and a cable material with easy tearability is needed.

[0003] However, with the improvement of various requirements for modern electrical facilities in all aspects, a PVC cable material with better high-temperature performance and mechanical properties is needed. In the prior art, cable materials usually use antimony-based flame retardants, which have the defects of high toxicity, large smoke, and easy aging at high temperature for a long time. At the same time, they also lack easy tearability and require special tools for cutting, increasing costs and being unfavorable for cable use.

[0004] Therefore, there is a need for a preparation method and application of a cable material with high-temperature resistance and easy tearability. Summary of the Invention

[0005] The main object of the present invention is to provide a preparation method and a product of a high-temperature resistant and easily tearable PVC cable material, aiming to solve the problems of insufficient properties such as high-temperature resistance and easy tearability of cable materials in the prior art.

[0006] To achieve the above object, the present invention proposes a preparation method of a high-temperature resistant and easily tearable PVC cable material, which includes the following steps:

[0007] Pretreatment of fillers: Mix diatomite and mica according to a mass ratio, then introduce a silane coupling agent into the reaction kettle after mixing, and raise the temperature to 50-80 °C for 1 h. Then add a reactive compatibilizer into the reaction kettle, raise the temperature to 100-120 °C and react for 0.5-1.5 h to obtain a double-modified filler;

[0008] Modification of flame retardants: Mix magnesium hydroxide and phytic acid according to a mass ratio of 25:1, then grind them with a ball mill for 2 h and transfer them to a drying kettle to complete drying to obtain phytic acid-coated modified magnesium hydroxide;

[0009] Dynamic vulcanization premixing: Add PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer to a kneader, heat up to 160°C and knead for 5 minutes, then add dicumyl peroxide and continue kneading for 10 minutes to obtain a sea-island structure premix.

[0010] Layered coextrusion molding: Divide the premix into an inner layer and an outer layer. Add nano-montmorillonite and modified magnesium hydroxide to the inner layer, and add double-modified filler to the outer layer. Coextrude through a twin-screw extruder under a temperature gradient, cool and cut into pellets to obtain a high-temperature and easy-to-tear PVC cable material.

[0011] Preferably, the steps for pretreating the filler, which include mixing diatomite and mica in a mass ratio, then introducing a silane coupling agent into the reaction kettle, heating up to 50 - 80°C and treating for 1 hour, and then adding a reactive compatibilizer into the reaction kettle, heating up to 100 - 120°C and reacting for 0.5 - 1.5 hours to obtain a double-modified filler, are as follows:

[0012] Put diatomite and mica into a high-speed mixer according to the mass ratio, and premix at a speed of 200 - 400 r / min for 10 - 15 minutes.

[0013] Dissolve the silane coupling agent in absolute ethanol to prepare a 5 wt% solution, spray it onto the surface of the mixed filler, heat up to 50 - 80°C, and mix and stir at a speed of 600 - 800 r / min for 1 hour.

[0014] Add the reactive compatibilizer, heat up to 100 - 120°C, stir and mix at a speed of 200 - 300 r / min, discharge after reacting for 0.5 - 1.5 hours, then conduct vacuum drying at 80°C for 4 hours, and sieve the dried filler through a 200-mesh sieve to obtain the double-modified filler.

[0015] Preferably, the steps for modifying the flame retardant, which include mixing magnesium hydroxide and phytic acid in a mass ratio of 25:1, then ball-milling for 2 hours through a ball mill and transferring to a drying kettle to complete drying to obtain phytic acid-coated modified magnesium hydroxide, are as follows:

[0016] Put magnesium hydroxide and phytic acid into a planetary ball mill according to the mass ratio of 25:1, use zirconia balls as the medium, ball-mill for 2 hours in a nitrogen atmosphere, and maintain the rotation speed at 300 r / min.

[0017] Perform spray drying on the ball-milled slurry to obtain phytic acid-coated modified magnesium hydroxide.

[0018] Preferably, the steps for dynamic vulcanization premixing: Add PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer to a kneader, heat up to 160°C and knead for 5 minutes, then add dicumyl peroxide and continue kneading for 10 minutes to obtain a sea-island structure premix, are as follows:

[0019] Preheat the internal mixer to 150°C, add PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer in sequence, and mix at a speed of 40-60 r / min for 5 minutes;

[0020] Dicumyl peroxide and calcium stearate were premixed in a mass ratio of 1:2, and then added to an internal mixer in three batches, with an interval of 2 minutes between each addition. The temperature was raised to 160±2°C, and mixing was continued at a speed of 80-100 r / min for 10 minutes to obtain a sea-island structure premix.

[0021] Preferably, the layered co-extrusion molding comprises the steps of dividing the premix into an inner layer and an outer layer, adding nano-montmorillonite and modified magnesium hydroxide to the inner layer, adding a double modified filler to the outer layer, co-extruding the premix under a temperature gradient through a twin-screw extruder, and cutting and granulating the premix after cooling to obtain a high temperature resistant and easy-to-tear PVC cable material, comprising:

[0022] The inner layer premix is divided into an inner layer and an outer layer according to a mass ratio of 7:3;

[0023] The inner layer is mixed with the premix, modified magnesium hydroxide and nano-montmorillonite in a ratio of 100:15:5 by mass;

[0024] The outer layer is mixed with the premix and the double modified filler in a ratio of 100:24 by mass;

[0025] The inner layer and the outer layer are fed into a twin-screw extruder, the inner layer is heated at 160-180°C in different zones, and the outer layer is heated at 150-165°C in different zones. The screw speed of the twin-screw extruder is 200-250r / min. Extrusion is performed, and the extrusion is cooled in a water tank. After cooling, the extruder is cut and granulated with a pelletizer to obtain a high-temperature resistant and easy-to-tear PVC cable material.

[0026] Preferably, the silane coupling agent is KH-560, the reactive compatibilizer is maleic anhydride, the plasticizer is epoxy fatty acid methyl ester, the heat stabilizer is calcium zinc stabilizer, and the mass ratio of diatomaceous earth to mica is 2:1 to 3:1.

[0027] The present invention also provides a product of a high temperature resistant and easy-tear PVC cable material, and the application of the product of the high temperature resistant and easy-tear PVC cable material is prepared by the preparation method of a high temperature resistant and easy-tear PVC cable material described in any one of the above technical solutions, and the product of the high temperature resistant and easy-tear PVC cable material comprises the following components in parts by mass:

[0028] 100 parts of PVC resin;

[0029] Thermoplastic elastomer 8-15 parts;

[0030] 10-20 parts of phytic acid coated modified magnesium hydroxide;

[0031] 5 - 10 parts of nano - montmorillonite;

[0032] 15 - 25 parts of diatomite - mica composite filler (diatomite: mica = 3:1 - 2:1);

[0033] Among them, the diatomite - mica composite filler is modified by both silane coupling agent KH - 560 and maleic anhydride.

[0034] Preferably, the thermoplastic elastomer is at least one of TPU and SEBS.

[0035] In the present invention, by adding thermoplastic elastomer, a weak interface layer is formed when the material is subjected to mechanical action to achieve controllable tearing. Also, modified magnesium hydroxide and montmorillonite are compounded to replace the traditional antimony - based flame retardant to achieve environmental protection flame retardancy. Moreover, a double - modified filler is obtained by compounding and modifying diatomite and mica to enhance the interfacial bonding force. At the same time, the tearing sensitivity is improved through the pore structure design to further enhance the easy - tearing performance. Through the dynamic vulcanization and layer - by - layer co - extrusion process, the inner layer is set as a high - temperature - resistant layer and the outer layer is set as an easy - tearing layer for zoning design to solve the functional conflict, which is suitable for industrial continuous production and solves the problems of insufficient properties such as high - temperature resistance and easy - tearing property of the cable materials in the prior art. Detailed implementation manners

[0036] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The thermoplastic elastomer involved in the present invention can ensure the mechanical properties during actual use and also provide an easy-tearing effect when stripping the cable material, so as to provide directional (longitudinal) easy-tearing performance. The present invention also discloses a flame retardant system formed by compounding modified magnesium hydroxide and nano-montmorillonite. By coating and modifying magnesium hydroxide with phytic acid, the addition amount of magnesium hydroxide is reduced, avoiding the influence on the mechanical properties of the material caused by the excessive addition amount of magnesium hydroxide in other prior art solutions using magnesium hydroxide as a flame retardant. Nano-montmorillonite can also enhance the flame retardant effect and improve the mechanical properties of the material.

[0040] The present invention discloses specific application examples 1-3 and comparative examples 1-2 of pvc cable materials using the prior art, and performance comparison experiments are carried out with examples 1-3 and comparative examples 1-2, as follows:

[0041] Example 1:

[0042] Raw materials (by mass):

[0043] 1. 100 parts of pvc resin (VA content 18%);

[0044] 2. 12 parts of thermoplastic elastomer TPU;

[0045] 3. 15 parts of phytic acid-coated modified magnesium hydroxide;

[0046] 4. 5 parts of nano-montmorillonite;

[0047] 5. 17 parts of diatomite-mica compound filler (diatomite: mica = 3:1);

[0048] 6. 20 parts of plasticizer epoxy fatty acid methyl ester;

[0049] 7. 3 parts of heat stabilizer calcium-zinc stabilizer.

[0050] Example 2:

[0051] Raw materials (by mass):

[0052] 1. 100 parts of pvc resin (VA content 18%);

[0053] 2. 8 parts of thermoplastic elastomer TPU;

[0054] 3. 12 parts of phytic acid-coated modified magnesium hydroxide;

[0055] 4. 8 parts of nano-montmorillonite;

[0056] 5. 20 parts of diatomite-mica compound filler (diatomite: mica = 2:1);

[0057] 6. Epoxy fatty acid methyl ester plasticizer: 20 parts;

[0058] 7. Calcium-zinc stabilizer heat stabilizer: 3 parts.

[0059] Example 3:

[0060] Raw materials (by mass parts):

[0061] 1. PVC resin (VA content 18%): 100 parts;

[0062] 2. Thermoplastic elastomer TPU: 15 parts;

[0063] 3. Phytate-coated modified magnesium hydroxide: 20 parts;

[0064] 4. Nano-montmorillonite: 10 parts;

[0065] 5. Diatomite-mica compound filler: 20 parts (diatomite: mica = 3:1);

[0066] 6. Epoxy fatty acid methyl ester plasticizer: 20 parts;

[0067] 7. Calcium-zinc stabilizer heat stabilizer: 3 parts.

[0068] Control Example 1:

[0069] Raw materials (by mass parts):

[0070] 1. PVC resin (VA content 18%): 100 parts;

[0071] 2. TOTM plasticizer: 50 parts;

[0072] 3. Filler calcium carbonate 60 parts + talc powder 40 parts;

[0073] 4. Calcium-zinc stabilizer heat stabilizer: 5 parts;

[0074] 5. Epoxidized soybean oil: 10 parts;

[0075] 6. Trioctyl trimellitate: 40 parts.

[0076] Control Example 2:

[0077] Raw materials (by mass parts):

[0078] 1. PVC resin (VA content 18%): 100 parts;

[0079] 2. TOTM plasticizer: 50 parts;

[0080] 3. Filler calcium carbonate 60 parts + talc powder 40 parts;

[0081] 4. Calcium-zinc stabilizer heat stabilizer: 5 parts;

[0082] 5. 18 parts of epoxidized soybean oil;

[0083] 6. 100 parts of trioctyl trimellitate.

[0084] Specifically, the present invention also discloses the following performance comparison experiments:

[0085] I. Tear strength test:

[0086] Experimental equipment: Universal tensile testing machine;

[0087] Experimental conditions: Clamp spacing 50 mm, tensile speed 500 mm / min, pre-cut depth of the specimen 5 mm;

[0088] Experimental steps:

[0089] 1. Prepare the products of each group of examples into dumbbell-shaped tear strength specimens with a thickness of 2 mm according to GB / T 529, and prepare 5 specimens for each group of examples;

[0090] 2. Place the specimens in a standard environment (23 °C, 50% humidity) for 24 h;

[0091] 3. Fix one end of the specimen with the upper clamp and hold the other end with the lower clamp, with an initial clamping distance of 50 ± 1 mm, and adjust the specimen so that the tearing direction coincides with the tensile axis;

[0092] 4. Start the universal tensile testing machine and perform tensile testing at a tensile speed of 500 mm / min, and record the load-displacement curve in real time until the specimen is completely broken.

[0093] Among them, the calculation formula for tear strength is as follows:

[0094]

[0095] Among them, F max is the maximum load, t is the thickness of the specimen, w is the width of the specimen, and σ t is the tear strength; eliminate the noise data with a deviation > 10%, and take the average value of 5 specimens.

[0096] II. Heat distortion temperature test:

[0097] Experimental equipment: Heat distortion tester, silicone oil bath, three-point bending device;

[0098] Specimen conditions: Rectangular specimens of 80 * 10 * 4 mm;

[0099] Experimental steps:

[0100] 1. Prepare the products of each group of examples into rectangular specimens of 80*10*4 mm according to GB / T 1634.2-2019, and prepare 5 specimens for each group of examples.

[0101] 2. Place the specimen horizontally on two supports (span 64 mm).

[0102] 3. Place the loading indenter at the center of the specimen and apply a bending stress of 1.8 MPa to the specimen.

[0103] 4. Set the initial temperature to 30 °C. After the liquid level of the silicone oil bath completely submerges the specimen, increase the temperature at a rate of 120 °C / h.

[0104] 5. When the deflection of the specimen reaches 0.25 mm, record the current temperature. If it does not reach within 10 min, terminate the test and record the maximum temperature.

[0105] III. Oxygen index test:

[0106] Experimental equipment: Oxygen index tester, glass combustion cylinder;

[0107] Specimen conditions: Specimens of 100*10*3 mm, with the edges of the specimens polished smoothly;

[0108] Experimental steps:

[0109] 1. Prepare the products of each group of examples into specimens of 100*10*3 mm according to GB / T 2406-2009, and prepare 5 specimens for each group of examples.

[0110] 2. Set the initial oxygen concentration, adjust the oxygen / nitrogen flow rate to control the oxygen concentration at 25%, and the gas flow rate is 40 mm / s.

[0111] 3. Ignite the top of the specimen with a propane flame with a height of 20 mm. After 3 s of ignition, remove the flame and observe the combustion situation.

[0112] 4. If the combustion time of the specimen > 30 s or the combustion length > 50 mm, reduce the oxygen concentration by 0.5%. Otherwise, increase the oxygen concentration and repeat until the critical value.

[0113] IV. Smoke density test:

[0114] Experimental equipment: Smoke density chamber, laser light source, photodetector;

[0115] Specimen conditions: Square sheets of 75*75*3 mm;

[0116] Experimental steps:

[0117] 1. Prepare the products of each group of examples into square sheets with a size of 75 * 75 * 3 mm according to GB / T 8323.2 - 2008, and prepare 5 for each group of examples.

[0118] 2. Baseline calibration: When there is no sample, adjust the light flux to 100%. After inserting the standard filter (transmittance 50%), verify that the instrument reading has an error ≤ 2%.

[0119] 3. Place the test bar above the radiation furnace in the smoke density chamber, ignite the propane flame, and test for 10 minutes.

[0120] 4. Record the specific optical density (D s ) in real - time, and take the maximum smoke density value (SDR) as the result.

[0121] Among them, the calculation formula of the specific optical density is as follows:

[0122]

[0123] Among them, I0 is the incident light intensity, I is the transmitted light intensity after being absorbed by the smoke, V is the volume of the smoke chamber, A is the combustion area of the test bar, and L is the path length of the light passing through the smoke chamber.

[0124] V. Artificial peel force simulation test:

[0125] Experimental equipment: Universal testing machine (equipped with a customized peeling fixture), force sensor (range 50 N);

[0126] Test bar conditions: Cable section with a diameter of 5 ± 0.1 mm and a length of 100 mm;

[0127] Experimental steps:

[0128] 1. Prepare the products of each group of examples into cable sections with a diameter of 5 ± 0.1 mm and a length of 100 mm according to the test bar conditions, and prepare 5 for each group of examples.

[0129] 2. Clamp the cable insulation layer with the upper fixture (clamping length 10 mm), and clamp the conductor with the lower fixture (clamping length 10 mm), with an initial spacing of 30 mm.

[0130] 3. Start the universal testing machine, peel vertically at a speed of 100 ± 5 mm / min, and record the maximum force value (peak value) during the peeling process.

[0131] 4. Continuously test 10 times, eliminate the highest / lowest values, and then take the average value and mark the peel force range.

[0132] The summary of the performance experiment data is shown in the following table:

[0133] Table 1 Summary of performance experiment data

[0134]

[0135] Experimental conclusion:

[0136] From the experimental data of the above three groups of examples and two groups of control examples, it can be seen that the tear strength shown in Examples 1-3 disclosed in the present invention is less than 15 N / m 2 , and the manual peeling force is less than 7 N, which is significantly better than the control example; and the heat distortion temperature of Examples 1-3 is significantly higher than that of Control Examples 1-2, and the oxygen index and smoke density show excellent performance, far better than the control examples.

[0137] Combining all the above examples, in the present invention, a longitudinal weak interface layer is formed in the matrix by using a TPU elastomer, and the porous structure of diatomite enables the material to be torn along a predetermined direction under the influence of a slight external force. The sea-island structure obtained by the dynamic vulcanization process balances the strength and tearability, realizing tearability by hand. Also, through the synergistic effect of nano-montmorillonite, phytic acid-coated magnesium hydroxide, and calcium-zinc stabilizer, while improving the thermal stability of the material, environmental protection and safety are ensured, and a cable material with high-temperature resistance and tearability can be obtained.

[0138] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the description of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A preparation method of a high-temperature resistant and easily tearable PVC cable material, characterized in that, It includes the following steps: Filler pretreatment: Mix diatomite and mica according to a mass ratio. After mixing, introduce a silane coupling agent into the reaction kettle, heat up to 50 - 80 °C and treat for 1 h. Then add a reactive compatibilizer into the reaction kettle, heat up to 100 - 120 °C and react for 0.5 - 1.5 h to obtain a double-modified filler; Flame retardant modification: Mix magnesium hydroxide and phytic acid according to a mass ratio of 25:1, then ball mill for 2 h through a ball mill and transfer to a drying kettle to complete drying to obtain phytic acid-coated modified magnesium hydroxide; Dynamic vulcanization premixing: Add PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer into a mixer, heat up to 160 °C and knead for 5 min, then add dicumyl peroxide and continue to knead for 10 min to obtain a sea-island structure premix; Layered co-extrusion molding: Divide the premix into an inner layer and an outer layer. Add nano-montmorillonite and modified magnesium hydroxide to the inner layer, and add double-modified filler to the outer layer. Co-extrude through a twin-screw extruder under a temperature gradient, cool and then cut into pellets to obtain a high-temperature resistant and easy-to-tear PVC cable material.

2. The preparation method of a high-temperature resistant and easily tearable PVC cable material according to claim 1, characterized in that, The step of the filler pretreatment, which mixes diatomite and mica according to a mass ratio, introduces a silane coupling agent into the reaction kettle after mixing, heats up to 50 - 80 °C and treats for 1 h, then adds a reactive compatibilizer into the reaction kettle, heats up to 100 - 120 °C and reacts for 0.5 - 1.5 h to obtain a double-modified filler, includes: Put diatomite and mica into a high-speed mixer according to a mass ratio and premix at a speed of 200 - 400 r / min for 10 - 15 min; Dissolve the silane coupling agent in absolute ethanol to prepare a 5 wt% solution, spray it onto the surface of the mixed filler, heat up to 50 - 80 °C, and mix and stir at 600 - 800 r / min for 1 h; Add a reactive compatibilizer, heat up to 100 - 120 °C, stir and mix at a speed of 200 - 300 r / min, discharge after reacting for 0.5 - 1.5 h, then conduct vacuum drying at 80 °C for 4 h, and pass the dried filler through a 200-mesh sieve to obtain a double-modified filler.

3. The preparation method of a high-temperature resistant and easily tearable PVC cable material as described in claim 1, characterized in that, The step of the flame retardant modification, which mixes magnesium hydroxide and phytic acid according to a mass ratio of 25:1, then ball mill for 2 h through a ball mill and transfer to a drying kettle to complete drying to obtain phytic acid-coated modified magnesium hydroxide, includes: Put magnesium hydroxide and phytic acid into a planetary ball mill according to a mass ratio of 25:1, use zirconia balls as the medium, ball mill for 2 h under a nitrogen atmosphere, and maintain the rotation speed at 300 r / min; Spray dry the ball-milled slurry to obtain phytic acid-coated modified magnesium hydroxide.

4. The preparation method of a high-temperature resistant and easily tearable PVC cable material as claimed in claim 1, wherein, The step of the dynamic vulcanization premixing, which adds PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer into a mixer, heats up to 160 °C and kneads for 5 min, then adds dicumyl peroxide and continues to knead for 10 min to obtain a sea-island structure premix, includes: Preheat the mixer to 150 °C, sequentially add PVC resin, thermoplastic elastomer, plasticizer, and heat stabilizer, and knead at a speed of 40 - 60 r / min for 5 min; After premixing dicumyl peroxide and calcium stearate at a mass ratio of 1:2, they are added to the internal mixer in three batches, with an interval of 2 minutes between each addition. The temperature is raised to 160 ± 2 °C, and mixing is continued at a rotation speed of 80 - 100 r / min for 10 minutes to obtain a sea-island structure premix.

5. The preparation method of a high-temperature resistant and easy-to-tear PVC cable material as claimed in claim 1, wherein, The steps of the layered coextrusion molding, which divides the premix into an inner layer and an outer layer, adds nano-montmorillonite and modified magnesium hydroxide to the inner layer, adds a double-modified filler to the outer layer, and performs coextrusion through a twin-screw extruder under a temperature gradient, followed by cooling and pelletizing to obtain a high-temperature resistant and easy-to-tear PVC cable material, include: Dividing the inner-layer premix into an inner layer and an outer layer according to a mass ratio of 7:3; Mixing the premix, modified magnesium hydroxide, and nano-montmorillonite in the inner layer according to a ratio of 100:15:5 by mass; Mixing the premix and the double-modified filler in the outer layer according to a ratio of 100:24 by mass; Feeding the inner layer and the outer layer into a twin-screw extruder. The inner layer is heated in zones at 160 - 180 °C, and the outer layer is heated in zones at 150 - 165 °C. The screw rotation speed of the twin-screw extruder is 200 - 250 r / min for extrusion. After extrusion, it is cooled in a water bath and then pelletized with a pelletizer to obtain a high-temperature resistant and easy-to-tear PVC cable material.

6. The preparation method of a high-temperature resistant and easily tearable PVC cable material as claimed in claim 1, characterized in that, The silane coupling agent is selected as KH-560, the reactive compatibilizer is selected as maleic anhydride, the plasticizer is selected as epoxy fatty acid methyl ester, the heat stabilizer is selected as calcium-zinc stabilizer, and the mass ratio of diatomite to mica is 2:1 - 3:

1.

7. A product of a high-temperature resistant and easily tearable PVC cable material, characterized in that, The product of the high-temperature resistant and easy-to-tear PVC cable material is prepared by the preparation method of a high-temperature resistant and easy-to-tear PVC cable material described in any one of claims 1 - 6. The product of the high-temperature resistant and easy-to-tear PVC cable material, calculated by mass, includes the following components: 100 parts of PVC resin; 8 - 15 parts of thermoplastic elastomer; 10 - 20 parts of phytic acid-coated modified magnesium hydroxide; 5 - 10 parts of nano-montmorillonite; 15 - 25 parts of diatomite-mica composite filler (diatomite:mica = 3:1 - 2:1); Among them, the diatomite-mica composite filler is double-modified with silane coupling agent KH-560 and maleic anhydride.

8. The product of a high-temperature resistant and easily tearable PVC cable material according to claim 7, characterized in that, The thermoplastic elastomer is at least one of TPU and SEBS.

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