High-flame-retardant PVC (polyvinyl chloride) sheath material as well as preparation method and application thereof

Abstract

The invention provides a high-flame-retardant PVC sheath material and a preparation method and application thereof.The high-flame-retardant PVC sheath material is prepared from PVC resin, a composite flame retardant, a composite plasticizer, a stabilizer, internal and external lubricants and pyrogallol in specific parts by weight through reasonable matching of all the components, especially by adding pyrogallol as a compatilizer, the high-flame-retardant PVC sheath material is prepared from the PVC resin, the composite flame retardant, the composite plasticizer, the stabilizer, the internal and external lubricants and pyrogallol; the compatibility among the PVC resin, the composite flame retardant and the composite plasticizer is effectively improved, so that the obtained high-flame-retardancy PVC sheath material has excellent flame retardancy and insulating property, also has excellent mechanical properties, and particularly has relatively high elongation at break and tensile strength.

Description

Technical Field

[0001] The invention belongs to the technical field of sheathing materials, and particularly relates to a highly flame-retardant PVC sheathing material and a preparation method and application thereof. Background Art

[0002] Wires and cables are wire products used to transmit electrical energy, information and realize electromagnetic energy conversion. Among them, PVC cable sheath material is currently the most widely used low-voltage cable material due to its excellent physical and chemical properties, mature processing and application technology and low cost.

[0003] Traditional PVC cable materials are based on PVC resin, which is mixed together by adding plasticizers, stabilizers, lubricants, flame retardants and other additives and then plasticizing through screw extrusion. For example, CN105504476A discloses a high-temperature resistant and flame-retardant polyolefin cable and a preparation method thereof; the raw material formula components of the high-temperature resistant and flame-retardant polyolefin cable include, by weight: a. 100 parts by weight of a copolymer of ethylene and vinyl acetate; b. 40-50 parts by weight of magnesium hydroxide; c. 15-20 parts by weight of antimony trioxide; d. 1-3 parts by weight of a thiobisphenol antioxidant; e. 1-3 parts by weight of a pentaerythritol ester antioxidant; f. 1-3 parts by weight of a phosphite antioxidant; g. 0-2 parts by weight of an auxiliary agent. The preparation method of the high-temperature resistant and flame-retardant polyolefin cable is as follows: all the raw materials are added to a high-speed mixer and mixed to obtain a mixture, and the mixture is made into a granular masterbatch to obtain the high-temperature resistant and flame-retardant polyolefin cable material; the high-temperature resistant and flame-retardant polyolefin cable prepared by this invention can reach a temperature resistance grade of 150°C.

[0004] However, the flame retardants and plasticizers added to traditional PVC cable materials, including the above-mentioned invention, are usually not compatible with PVC resins, are easy to precipitate, and have a serious impact on the flame retardant properties. In addition, the amount of flame retardant added is usually large, resulting in a decrease in the mechanical properties of the resulting PVC cable materials.

[0005] Therefore, in response to the above technical problems, developing a highly flame retardant PVC sheathing material with excellent flame retardant properties, insulation properties and mechanical properties is still a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a highly flame-retardant PVC sheathing material, a preparation method thereof, and an application thereof. The highly flame-retardant PVC sheathing material, by adding a composite plasticizer and a composite flame retardant, and adding pyrogallol as a compatibilizer, can have both excellent flame retardant and insulating properties, and also has excellent mechanical properties, especially high tensile strength and elongation at break.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0009]

[0010] The highly flame-retardant PVC sheathing material provided by the present invention comprises specific weight parts of PVC resin, a composite flame retardant, a composite plasticizer, a stabilizer, internal and external lubricants, and pyrogallol. The PVC resin is used as a matrix, and the composite flame retardant, composite plasticizer, stabilizer, internal and external lubricants, and pyrogallol are added as auxiliary agents. In particular, by adding the composite plasticizer and the composite flame retardant, and adding pyrogallol as a compatibilizer, the composite plasticizer and the composite flame retardant can be adsorbed on the surface of the composite flame retardant and the composite toughening agent to form a coating layer, thereby effectively improving the compatibility among the PVC resin, the composite flame retardant, and the composite plasticizer. The obtained highly flame-retardant PVC sheathing material has both excellent flame retardant and insulating properties, and the formed coating layer can also be carbonized to form a protective layer under high temperature environment, which can further improve the flame retardancy of the obtained PVC sheathing material. At the same time, it is ensured that the obtained highly flame-retardant PVC sheathing material also has high elongation at break and tensile strength, and excellent mechanical properties.

[0011] The content of the PVC resin may be 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, 38 parts by weight, 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight, 48 parts by weight or 50 parts by weight, etc.

[0012] The content of the composite flame retardant can be 20 parts by weight, 22 parts by weight, 24 parts by weight, 26 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, 38 parts by weight or 40 parts by weight, etc.

[0013] The content of the composite plasticizer can be 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight or 30 parts by weight, etc.

[0014] The content of the stabilizer can be 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, 2.8 parts by weight or 3 parts by weight, etc.

[0015] The content of the internal and external lubricants can be 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, 2.8 parts by weight or 3 parts by weight, etc.

[0016] The content of the pyrogallol can be 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight or 2 parts by weight, etc.

[0017] Preferably, the degree of polymerization of the PVC resin is 1200-1400, for example, 1220, 1240, 1260, 1280, 1300, 1320, 1340, 1360, 1380 or 1400.

[0018] Preferably, the composite flame retardant includes magnesium hydroxide, antimony trioxide and red phosphorus.

[0019] As a preferred technical solution of the present invention, the above-mentioned three flame retardants of magnesium hydroxide, antimony trioxide and red phosphorus are used in combination as a composite flame retardant, which can further improve the flame retardant properties of the obtained highly flame retardant PVC sheathing material.

[0020] Preferably, the mass ratio of the magnesium hydroxide, antimony trioxide and red phosphorus is 1:(0.5-1.5):(0.1-0.5);

[0021] Wherein, the mass ratio of the magnesium hydroxide to antimony trioxide can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc.

[0022] The mass ratio of the magnesium hydroxide to red phosphorus can be 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5, etc.

[0023] Preferably, the composite plasticizer includes any one of diisodecyl phthalate, diisooctyl phthalate, dioctyl terephthalate (DOTP) or chlorinated paraffin, or a combination of at least two thereof, and more preferably a combination of dioctyl terephthalate and chlorinated paraffin.

[0024] As a preferred technical solution of the present invention, the combination of dioctyl terephthalate and chlorinated paraffin as a composite plasticizer can further improve the volume resistivity of the obtained high flame retardant PVC sheath material, making it have more excellent insulation performance.

[0025] Preferably, the mass ratio of dioctyl terephthalate to chlorinated paraffin is (3-5):1, for example, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, etc.

[0026] Preferably, the stabilizer comprises a calcium-zinc composite heat stabilizer.

[0027] Preferably, the internal and external lubricants include any one of white carbon black, EVA wax, calcium carbonate, calcium stearate or zinc stearate, or a combination of at least two thereof.

[0028] In a second aspect, the present invention provides a method for preparing the highly flame-retardant PVC sheathing material as described in the first aspect, the preparation method comprising the following steps:

[0029] (1) mixing a composite flame retardant, a composite plasticizer, and pyrogallol in water and drying the mixture to obtain a premix A; and mixing a stabilizer and an internal and external lubricant to obtain a premix B;

[0030] (2) mixing the premix A obtained in step (1) with a PVC resin to obtain a mixture;

[0031] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) to obtain the highly flame-retardant PVC sheathing material.

[0032] Preferably, the mixing temperature of mixing the composite flame retardant, the composite plasticizer and pyrogallol in water in step (1) is 20-40°C, for example, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C, etc.

[0033] Preferably, the mixing time of mixing the composite flame retardant, the composite plasticizer and pyrogallol in water in step (1) is 0.5 to 3 hours, for example, 0.5 hours, 0.7 hours, 0.9 hours, 1.1 hours, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.1 hours, 2.3 hours, 2.5 hours, 2.7 hours or 3 hours, etc.

[0034] Preferably, the mixing temperature of the stabilizer and the internal and external lubricants in step (1) is 70-90°C, for example, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C.

[0035] Preferably, the mixing time of the stabilizer and the internal and external lubricants in step (1) is 3 to 5 minutes, for example, 3 minutes, 3.2 minutes, 3.4 minutes, 3.6 minutes, 3.8 minutes, 4 minutes, 4.2 minutes, 4.4 minutes, 4.6 minutes, 4.8 minutes or 5 minutes.

[0036] Preferably, the mixing in step (2) is carried out in a high-speed mixer.

[0037] Preferably, the mixing temperature in step (2) is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C.

[0038] Preferably, the mixing time in step (2) is 2 to 5 min, for example, 2 min, 2.2 min, 2.4 min, 2.6 min, 2.8 min, 3 min, 3.2 min, 3.4 min, 3.6 min, 3.8 min, 4 min, 4.2 min, 4.4 min, 4.6 min, 4.8 min or 5 min, etc.

[0039] In a third aspect, the present invention provides a use of the highly flame-retardant PVC sheathing material as described in the first aspect in the preparation of a transmission cable.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The highly flame-retardant PVC sheathing material provided by the present invention comprises specific weight portions of PVC resin, composite flame retardant, composite plasticizer, stabilizer, internal and external lubricant, and pyrogallol. By rationally matching the above components, especially by adding pyrogallol as a compatibilizer, the compatibility between the PVC resin, composite flame retardant, and composite plasticizer is effectively improved, so that the obtained highly flame-retardant PVC sheathing material has both excellent flame retardant properties and insulation properties, and also has excellent mechanical properties, especially high elongation at break and tensile strength.

[0042] (2) By further optimizing the types of the composite flame retardant and the composite plasticizer, the flame retardant grade of the high flame retardant PVC sheathing material provided by the present invention after being cabled can meet the B2 index in GB 31247-2014 and reach the d0 level in GB 31247-2014, that is, there is no dripping or particle after burning within 1200 seconds after being exposed to fire, and the bundle combustion meets the bundle A, B, and C combustion requirements in GB / T18380, and the volume resistivity is not less than 2.6×10 10 Ω·m, the elongation at break is not less than 337%, and the tensile strength is not less than 16.8MPa. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] The detailed information of some raw materials involved in the following specific embodiments is as follows:

[0045] (1) PVC resin: degree of polymerization 1300, purchased from Formosa Plastics S-70;

[0046] (2) Calcium zinc composite heat stabilizer: purchased from Hangzhou Stable Rubber Material Co., Ltd., brand H102;

[0047] (3) Chlorinated paraffin: long-chain chlorinated paraffin, CA number: 63449-39-8.

[0048] Example 1

[0049] A highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0050]

[0051] The composite flame retardant comprises magnesium hydroxide, antimony trioxide and red phosphorus in a mass ratio of 1:1:0.25;

[0052] The composite plasticizer includes dioctyl terephthalate and chlorinated paraffin in a mass ratio of 4:1;

[0053] The preparation method of the highly flame-retardant PVC sheath material provided in this embodiment 1 comprises the following steps:

[0054] (1) The composite flame retardant, composite plasticizer and pyrogallol were mixed in water at 30°C for 2 hours and dried to obtain premix A; the calcium zinc composite heat stabilizer and white carbon black were mixed at 80°C for 4 minutes to obtain premix B;

[0055] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 4 minutes to obtain a mixture;

[0056] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled between 165 and 175° C., to obtain the highly flame-retardant PVC sheathing material.

[0057] Example 2

[0058] A highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0059]

[0060]

[0061] The composite flame retardant comprises magnesium hydroxide, antimony trioxide and red phosphorus in a mass ratio of 1:0.8:0.35;

[0062] The composite plasticizer includes dioctyl terephthalate and chlorinated paraffin in a mass ratio of 3.5:1;

[0063] The preparation method of the highly flame-retardant PVC sheath material provided in this embodiment 2 comprises the following steps:

[0064] (1) Mixing the composite flame retardant, composite plasticizer, and pyrogallol in water at 25° C. for 3 h, and drying to obtain a premix A;

[0065] The calcium zinc composite heat stabilizer and EVA wax were mixed at 90°C for 3 minutes to obtain a premix B;

[0066] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 50° C. for 5 minutes to obtain a mixture;

[0067] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the highly flame-retardant PVC sheathing material.

[0068] Example 3

[0069] A highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0070]

[0071] The composite flame retardant comprises magnesium hydroxide, antimony trioxide and red phosphorus in a mass ratio of 1:1.3:0.15;

[0072] The composite plasticizer includes dioctyl terephthalate and chlorinated paraffin in a mass ratio of 4.5:1;

[0073] The preparation method of the highly flame-retardant PVC sheath material provided in this embodiment 3 comprises the following steps:

[0074] (1) Mixing the composite flame retardant, composite plasticizer, and pyrogallol in water at 40° C. for 1 hour and drying to obtain a premix A;

[0075] The calcium zinc composite heat stabilizer and calcium stearate were mixed at 70° C. for 5 minutes to obtain a premix B;

[0076] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 3 minutes to obtain a mixture;

[0077] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the highly flame-retardant PVC sheathing material.

[0078] Example 4

[0079] A highly flame-retardant PVC sheathing material is different from Example 1 in that the composite flame retardant is only magnesium hydroxide and antimony trioxide in a mass ratio of 1:1, and does not contain red phosphorus. Other substances, amounts and preparation methods are the same as those in Example 1.

[0080] Example 5

[0081] A highly flame-retardant PVC sheathing material is different from Example 1 in that the composite flame retardant is only magnesium hydroxide and red phosphorus in a mass ratio of 1:0.25, and does not contain antimony trioxide. Other substances, dosages and preparation methods are the same as those in Example 1.

[0082] Example 6

[0083] A highly flame-retardant PVC sheathing material is different from Example 1 in that the composite flame retardant is only antimony trioxide and red phosphorus in a mass ratio of 1:0.25, and does not contain magnesium hydroxide. Other substances, amounts and preparation methods are the same as those in Example 1.

[0084] Example 7

[0085] A highly flame-retardant PVC sheathing material is disclosed. The difference between the embodiment 1 is that the mass ratio of dioctyl terephthalate and chlorinated paraffin in the composite plasticizer is 2:1, and the other substances, amounts and preparation methods are the same as those in embodiment 1.

[0086] Example 8

[0087] A highly flame-retardant PVC sheathing material is disclosed. The difference between the embodiment 1 is that the mass ratio of dioctyl terephthalate and chlorinated paraffin in the composite plasticizer is 6:1, and the other substances, amounts and preparation methods are the same as those in embodiment 1.

[0088] Comparative Example 1

[0089] A PVC sheathing material is provided, which differs from Example 1 in that pyrogallol is not added, and other substances, amounts used, and preparation methods are the same as those in Example 1.

[0090] Comparative Example 2

[0091] A PVC sheath material comprises the following components in parts by weight:

[0092]

[0093] The composite plasticizer comprises dioctyl terephthalate and chlorinated paraffin in a mass ratio of 4:1;

[0094] The preparation method of the highly flame-retardant PVC sheath material provided in this comparative example 2 comprises the following steps:

[0095] (1) Magnesium hydroxide, a composite plasticizer, and pyrogallol were mixed in water at 30° C. for 2 h, and dried to obtain a premix A;

[0096] The calcium zinc composite heat stabilizer and white carbon black were mixed at 80°C for 4 minutes to obtain a premix B;

[0097] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 4 minutes to obtain a mixture;

[0098] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the PVC sheath material.

[0099] Comparative Example 3

[0100] A PVC sheath material comprises the following components in parts by weight:

[0101]

[0102] The composite plasticizer comprises dioctyl terephthalate and chlorinated paraffin in a mass ratio of 4:1;

[0103] The preparation method of the highly flame-retardant PVC sheath material provided in this comparative example 3 comprises the following steps:

[0104] (1) Antimony trioxide, a composite plasticizer, and pyrogallol were mixed in water at 30° C. for 2 h and dried to obtain a premix A;

[0105] The calcium zinc composite heat stabilizer and white carbon black were mixed at 80°C for 4 minutes to obtain a premix B;

[0106] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 4 minutes to obtain a mixture;

[0107] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the PVC sheath material.

[0108] Comparative Example 4

[0109] A highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0110]

[0111] The composite flame retardant comprises magnesium hydroxide, antimony trioxide and red phosphorus in a mass ratio of 1:1:0.25;

[0112] The preparation method of the high flame retardant PVC sheath material provided in this comparative example 4 comprises the following steps:

[0113] (1) The composite flame retardant, dioctyl terephthalate, and pyrogallol were mixed in water at 30° C. for 2 h and dried to obtain a premix A;

[0114] The calcium zinc composite heat stabilizer and white carbon black were mixed at 80°C for 4 minutes to obtain a premix B;

[0115] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 4 minutes to obtain a mixture;

[0116] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the highly flame-retardant PVC sheathing material.

[0117] Comparative Example 5

[0118] A highly flame-retardant PVC sheathing material, comprising the following components in parts by weight:

[0119]

[0120] 2 parts by weight of calcium zinc composite heat stabilizer;

[0121] 2 parts by weight of white carbon black;

[0122] 1.5 parts by weight of pyrogallol;

[0123] The composite flame retardant comprises magnesium hydroxide, antimony trioxide and red phosphorus in a mass ratio of 1:1:0.25;

[0124] The preparation method of the high flame retardant PVC sheath material of this comparative example 5 comprises the following steps:

[0125] (1) The composite flame retardant, chlorinated paraffin, and pyrogallol were mixed in water at 30° C. for 2 h and dried to obtain a premix A;

[0126] The calcium zinc composite heat stabilizer and white carbon black were mixed at 80°C for 4 minutes to obtain a premix B;

[0127] (2) placing the premix A obtained in step (1) and the PVC resin in a high-speed mixer and mixing at 55° C. for 4 minutes to obtain a mixture;

[0128] (3) Extruding the mixture obtained in step (2) and the premix B in step (1) in a twin-screw extruder, wherein the speed of the twin-screw extruder is 300 rpm and the body temperature is controlled at 165-175° C., to obtain the highly flame-retardant PVC sheathing material.

[0129] Performance testing:

[0130] (1) Flame retardant performance: The flame retardant grade of the PVC cable material after cable formation is tested in accordance with the GB31247-2014 standard.

[0131] (2) Volume resistivity: PVC cable materials were tested according to the test method provided in GB / T 31838.2-2019.

[0132] (3) Elongation at break and tensile strength: PVC cable materials were tested according to the test method provided in GB / T 1040.3-2006.

[0133] The test was carried out according to the above test method. The test results are shown in Table 1:

[0134] Table 1

[0135] Flame retardant grade / level Volume resistivity / Ω·m Elongation at break / % Tensile strength / MPa Example 1 B2 <![CDATA[2.6×10 10 ]]> 346 17.4 Example 2 B2 <![CDATA[3.1×10 10 ]]> 357 18.1 Example 3 B2 <![CDATA[2.8×10 10 ]]> 337 16.8 Example 4 B2 <![CDATA[2.5×10 10 ]]> 345 17.1 Example 5 B3 <![CDATA[2.6×10 10 ]]> 355 18.3 Example 6 B3 <![CDATA[2.5×10 10 ]]> 358 17.2 Example 7 B3 <![CDATA[1.8×10 10 ]]> 332 16.1 Example 8 B2 <![CDATA[1.6×10 10 ]]> 323 15.9 Comparative Example 1 B3 <![CDATA[1.9×10 10 ]]> 318 14.2 Comparative Example 2 B3 <![CDATA[2.0×10 10 ]]> 327 15.5 Comparative Example 3 B3 <![CDATA[2.1×10 10 ]]> 329 14.9 Comparative Example 4 B2 <![CDATA[1.0×10 10 ]]> 322 14.1 Comparative Example 5 B2 <![CDATA[0.9×10 10 ]]> 318 13.9

[0136] According to the data in Table 1, we can see that:

[0137] The highly flame-retardant PVC sheathing material provided by the present invention has excellent flame retardant and insulating properties, as well as excellent mechanical properties, especially high elongation at break and high tensile strength;

[0138] Specifically, the flame retardant grade of the highly flame retardant PVC sheathing materials provided in Examples 1 to 3 can all reach B2 level, and the volume resistivity is not less than 2.6×10 10 Ω·m, the elongation at break is not less than 337%, and the tensile strength is not less than 16.8MPa.

[0139] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the flame retardant grade of the PVC sheath material obtained without adding pyrogallol is only B2, and the volume resistivity is only 1.9×10 10 Ω·m, the elongation at break is only 318%, and the tensile strength is only 14.2MPa. The flame retardant, insulation and mechanical properties are relatively poor.

[0140] Comparing the data of Example 1 and Comparative Examples 2-3, it can be seen that the flame retardant grade of the PVC sheath material obtained by using only magnesium hydroxide or only antimony trioxide as a flame retardant is also only B2, and the flame retardant performance is relatively poor.

[0141] Further comparison of the data of Example 1 and Comparative Examples 4-5 shows that using only dioctyl terephthalate or only chlorinated paraffin as a plasticizer will result in a significant decrease in the volume resistivity of the resulting PVC sheath material and relatively poor insulation.

[0142] Finally, by comparing the data of Example 1 with those of Examples 4 to 8, it can be seen that the type of composite flame retardant and the mass ratio of each substance in the composite plasticizer will also affect the flame retardancy and insulation performance of the obtained PVC sheathing material.

[0143] The applicant declares that the present invention, through the above-described embodiments, illustrates a highly flame-retardant PVC sheathing material, its preparation method, and its application. However, the present invention is not limited to the above-described embodiments, and does not necessarily rely on the above-described embodiments for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the raw materials of the present invention, addition of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A highly flame-retardant PVC sheathing material, characterized in that: The highly flame-retardant PVC sheath material comprises the following components in parts by weight:

2. The highly flame-retardant PVC sheathing material according to claim 1, characterized in that: The polymerization degree of the PVC resin is 1200-1400.

3. The highly flame-retardant PVC sheathing material according to claim 1 or 2, characterized in that: The composite flame retardant includes magnesium hydroxide, antimony trioxide and red phosphorus; Preferably, the mass ratio of the magnesium hydroxide, antimony trioxide and red phosphorus is 1:(0.5-1.5):(0.1-0.5).

4. The highly flame-retardant PVC sheathing material according to any one of claims 1 to 3, characterized in that: The composite plasticizer comprises any one of diisodecyl phthalate, diisooctyl phthalate, dioctyl terephthalate or chlorinated paraffin, or a combination of at least two thereof, preferably a combination of dioctyl terephthalate and chlorinated paraffin; Preferably, the mass ratio of dioctyl terephthalate to chlorinated paraffin is (3-5):

1.

5. The highly flame-retardant PVC sheathing material according to any one of claims 1 to 4, characterized in that: The stabilizer includes a calcium-zinc composite heat stabilizer.

6. The highly flame-retardant PVC sheathing material according to any one of claims 1 to 5, characterized in that: The internal and external lubricants include any one of white carbon black, EVA wax, calcium carbonate, calcium stearate or zinc stearate, or a combination of at least two of them.

7. A method for preparing the highly flame-retardant PVC sheathing material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) mixing a composite flame retardant, a composite plasticizer, and pyrogallol in water and drying the mixture to obtain a premix A; and mixing a stabilizer and an internal and external lubricant to obtain a premix B; (2) mixing the premix A obtained in step (1) with a PVC resin to obtain a mixture; (3) Extruding the mixture obtained in step (2) and the premix B in step (1) to obtain the highly flame-retardant PVC sheathing material.

8. The preparation method according to claim 7, characterized in that In step (1), the mixing temperature of the composite flame retardant, the composite plasticizer and pyrogallol in water is 20 to 40° C. and the mixing time is 0.5 to 3 hours; Preferably, the mixing temperature of the stabilizer and the internal and external lubricants in step (1) is 70-90° C., and the mixing time is 3-5 minutes.

9. The preparation method according to claim 7 or 8, characterized in that The mixing in step (2) is carried out in a high-speed mixer; Preferably, the mixing temperature in step (2) is 50-60° C. and the mixing time is 2-5 minutes.

10. Use of the highly flame-retardant PVC sheathing material according to any one of claims 1 to 6 in the preparation of power transmission cables.

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