High-flame-retardant power cable

Abstract

The invention discloses a high-flame-retardant power cable, and belongs to the field of cable equipment. Comprising the following raw materials in parts by weight: 80 parts of chlorosulfonated polyethylene rubber, 30 parts of an ethylene-vinyl acetate copolymer, 40-100 parts of MH-polyphosphazene, 30 parts of carbon black, 1.5 parts of an anti-aging agent, 2 parts of a silane coupling agent, 2 parts of stearic acid, 1.5 parts of paraffin, 5 parts of maleic anhydride polybutadiene, 3 parts of N, N '-m-phenylenedimaleimide, 1-5 parts of sulfur and 1.5 parts of an accelerant. Wherein MH-polyphosphazene forms a phosphorus-nitrogen flame-retardant layer on the surface layer of the material, so that the problem of insufficient fire resistance of a common cable sheath material is effectively solved; and the nitrogen and phosphorus groups significantly improve the compatibility and dispersity of magnesium hydroxide in a matrix, and facilitate formation of a phosphorus-nitrogen-magnesium synergistic compact carbon layer. Therefore, the power cable sheath material prepared by the invention has excellent flame retardance, and has important application value in the technical field of power cable flame retardance.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of high flame-retardant power cable, belong to cable equipment field. BACKGROUND

[0002] Cable material is mainly rubber material, by adding a series of additives to rubber material, different properties of rubber material are given. Adding anti-aging agent to rubber material solves its easy aging problem; adding ultraviolet-resistant polymer to rubber material can greatly reduce the aging phenomenon due to long-term exposure to ultraviolet light. Among many cable problems, the fireproof problem of cable has been concerned. Due to excessive power in cable or high temperature, the internal resistance of cable generates heat, and the cable skin is self-ignited due to excessive temperature. The traditional method is to add magnesium hydroxide or aluminum hydroxide as flame retardant to rubber material to achieve flame retardant effect. However, a large amount of magnesium hydroxide (50%-60%) is usually needed to obtain good flame retardant performance. In addition, the compatibility between unmodified hydroxide flame retardant and rubber material is poor, which seriously affects the mechanical properties of rubber material, such as tensile strength and elongation at break.

[0003] Therefore, in order to solve the above problems, the present application provides a preparation method of high flame-retardant power cable skin. SUMMARY

[0004] The present application provides a preparation method of high-temperature-resistant flame-retardant cable skin. The material prepared by the method has excellent flame-retardant effect.

[0005] To achieve the above purpose, the present application adopts the following technical scheme: A high flame-retardant power cable, the skin of which is prepared from the following components by weight: Chlorosulfonated polyethylene rubber (CSM) 80 parts, ethylene-vinyl acetate copolymer (EVA) 30 parts, MH-polyphosphazene 40-100 parts, carbon black (N220) 30 parts, antioxidant 1.5 parts, silane coupling agent (KH-550) 2 parts, stearic acid 2 parts, paraffin 1.5 parts, maleic anhydride polybutadiene 5 parts, N,N'-m-phenylene bismaleimide 3 parts, sulfur 1-5 parts, accelerator 1.5 parts.

[0006] A high flame-retardant power cable, the skin of which is prepared by the following steps: Step 1: first add CSM and EVA in the two-roll mill, the roll temperature is 70℃, plasticize for 5min; add MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin, maleic anhydride polybutadiene, N,N'-m-phenylene bismaleimide in the plasticized rubber in turn, the roll temperature is controlled at 92-98℃, mix for 15min; after mixing, take out the sheet, cool and store, and get the first mixing rubber of cable skin; Step 2: adjust the roll gap of the open mill to 3.0 mm, re-mix the one-stage rubber on the open mill for 5 min, then add sulfur and accelerator, and mix for 10 min, the mixing temperature is 80℃; Step 3: adjust the roll gap to 2.0 mm, after mixing evenly, perform sheeting, and after cooling and storage, obtain the two-stage rubber of the cable sheath; Step 4: vulcanize the two-stage rubber obtained above on a flat vulcanizing machine, the vulcanization temperature is 150℃, the vulcanization pressure is 12 MPa, and the vulcanization time is 42 min, to obtain the cable sheath.

[0007] As a further technical solution, the antioxidant is 2-mercaptobenzimidazole, and the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide.

[0008] As a further technical solution, the MH-polyphosphazene is prepared by the following steps: Step S1: immerse 100 g of magnesium hydroxide in ethanol for 30 min, wash, dry, and mix it with an ethanol / water solution to prepare a magnesium hydroxide slurry with a certain concentration, and stir uniformly.

[0009] Step S2: preparation of silane coupling agent hydrolysate: add 50 ml of deionized water to a 100 ml flask, dropwise add glacial acetic acid, and adjust the solution PH to 3.5-4.5. Weigh 2 parts of silane coupling agent and add it to the prepared solution. Place the reaction system in a 35℃ water bath. Stir and hydrolyze for 30 min at this temperature. When the water bath temperature is heated to 60℃, dropwise add the hydrolysate to a three-necked flask containing the magnesium hydroxide slurry. Stir and react for 4 h at this temperature. Cool at room temperature, filter, wash to neutral, and dry at 80℃ for 24 h to obtain intermediate product A. The specific reaction process is as follows: Step S3: add the reaction raw materials hexacyclic tricyanophosphine, intermediate product A, and melamine to a flask, stir uniformly, then add acid binding agent triethylamine, water bath heating, 60℃ reaction for 4-8h, filter, wash to neutral, 80℃ constant temperature drying for 24h, to obtain MH-polyphosphazene. The specific reaction is as follows.

[0010] As a further technical solution, the ethanol and water mixture in step S1 is 100 ml of ethanol and 20 ml of deionized water.

[0011] As a further technical solution, the amount ratio of silane coupling agent, deionized water, and glacial acetic acid in step S2 is 1 g:25 ml:1.5 ml As a further technical solution, the ratio of the amount of intermediate product A, hexacyclic trisphosphine cyanide, melamine, triethylamine, and tetrahydrofuran in step S3 is 100 g: 15 g: 27 g: 8.7 g: 300 mL.

[0012] From the preparation method, in step S2, Si-OH generated by hydrolysis of the silane coupling agent reacts with the surface hydroxyl group of magnesium hydroxide to introduce an amino active group, thereby preparing intermediate product A; then, in step S3, MH-polyphosphazene is prepared by using intermediate product A, hexacyclic trisphosphine cyanide, and melamine. Hexacyclic trisphosphine cyanide contains P-Cl bonds, which can be nucleophilically substituted by -NH2 in the intermediate product, thereby forming P-N bonds. Due to the reaction steric hindrance and the control of the molar ratio of raw materials, the flame retardant modified by hexacyclic trisphosphine cyanide contains more unreacted P-Cl bonds on the surface. Melamine, as a nucleophile, attacks the residual P-Cl bonds on the hexacyclic trisphosphine cyanide of the flame retardant modifier to form P-N bonds, successfully grafts melamine, and thereby prepares the flame retardant modifier MH-polyphosphazene.

[0013] From the function of the prepared MH-polyphosphazene, the present application uses silicon and phosphorus-nitrogen adjuvants to synergistically modify magnesium hydroxide. The silane group is firmly bonded to the surface hydroxyl group of magnesium hydroxide through Si-O-Si bonds, which to some extent avoids the agglomeration of magnesium hydroxide particles. The phosphorus-nitrogen groups are arranged on the surface layer, which plays a synergistic flame-retardant role of chemical catalysis and gas-phase dilution. During combustion, the phosphorus-nitrogen groups release PO· free radicals and nitrogen, forming an expanded carbon layer. The phosphorus-containing free radicals will combine with each other and terminate active free radicals to achieve the purpose of extinguishing the flame. The nitrogen generated by the thermal decomposition of the phosphorus-nitrogen groups can reduce the concentration of oxygen in the air, thereby slowing down the combustion intensity. At the same time, the phosphoric acid generated by the thermal decomposition of the phosphorus-nitrogen groups can catalyze the dehydration and carbonization of polymers to form an expanded carbon layer to insulate heat and oxygen. Therefore, by the modification method of the present application, the flame-retardant magnesium hydroxide is added as a filler to the rubber matrix, which can greatly increase the flame-retardant performance of the material.

[0014] The beneficial effects of the present application are as follows: The present application designs and synthesizes a multifunctional magnesium hydroxide modifier. The modifier introduces magnesium hydroxide and phosphorus-nitrogen adjuvants in terms of composition, which has a synergistic flame-retardant effect. On the one hand, the magnesium hydroxide in the modifier produces water and MgO upon thermal decomposition, which vaporizes and absorbs heat to achieve a cooling effect. At the same time, the MgO produced after combustion covers the surface of the rubber polymer, forming a protective barrier to inhibit smoke and slow down the fire. On the other hand, the polyphosphazene in the modifier generates phosphoric acid derivatives, nitrogen, and phosphorus-containing free radicals upon thermal decomposition. The phosphoric acid catalyzes the dehydration and carbonization of polymers to form a dense carbon layer, which has a good heat and oxygen insulation effect. The released nitrogen dilutes the oxygen concentration and slows down the fire. The phosphorus-containing free radicals PO· and HPO· released upon heating capture H· and OH· free radicals in the combustion chain reaction, achieving the effect of extinguishing the flame. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0016] Embodiment one Preparation of MH-polyphosphazene Step S1: 100 g of magnesium hydroxide was immersed in ethanol and stirred for 30 min, washed, dried, and mixed with an ethanol / water solution to prepare a magnesium hydroxide slurry with a certain concentration, and stirred uniformly.

[0017] Step S2: Preparation of silane coupling agent hydrolysate: 50 ml of deionized water was added to a 100 ml flask, and glacial acetic acid was added dropwise to adjust the solution PH to 4. Two portions of silane coupling agent were weighed and added to the prepared solution, and the reaction system was placed in a 35°C water bath. The hydrolysis was stirred at this temperature for 30 min. When the water bath temperature was heated to 60°C, the hydrolysate was added dropwise to a three-necked flask containing the magnesium hydroxide slurry. The reaction was stirred at this temperature for 4 h, cooled at room temperature, filtered, washed to neutral, and dried at 80°C for 24 h to obtain intermediate product A.

[0018] Step S3: 7.5 g of hexacyclic trisphosphine cyanide, 50 g of intermediate product A, 13.5 g of melamine, and 150 mL of tetrahydrofuran were added to a flask, stirred uniformly, then 4.35 g of acid-binding agent triethylamine was added, and the reaction was heated in a water bath at 60°C for 4 h. The reaction was filtered, washed to neutral, and dried at 80°C for 24 h to obtain MH-polyphosphazene.

[0019] Embodiment two Preparation of MH-polyphosphazene Step S1: 100 g of magnesium hydroxide was immersed in ethanol and stirred for 30 min, washed, dried, and mixed with an ethanol / water solution to prepare a magnesium hydroxide slurry with a certain concentration, and stirred uniformly.

[0020] Step S2: Preparation of silane coupling agent hydrolysate: 50 ml of deionized water was added to a 100 ml flask, and glacial acetic acid was added dropwise to adjust the solution PH to 4. Two portions of silane coupling agent were weighed and added to the prepared solution, and the reaction system was placed in a 35°C water bath. The hydrolysis was stirred at this temperature for 30 min. When the water bath temperature was heated to 60°C, the hydrolysate was added dropwise to a three-necked flask containing the magnesium hydroxide slurry. The reaction was stirred at this temperature for 4 h, cooled at room temperature, filtered, washed to neutral, and dried at 80°C for 24 h to obtain intermediate product A.

[0021] Step S3: Put 15 g hexacyclic tricyanophosphine, 100 g intermediate product A, 27 g melamine and 300 mL tetrahydrofuran into a flask, stir uniformly, then add acid-binding agent triethylamine 8.70 g, water bath heating, 60℃ reaction for 8 h, filter, wash to neutral, constant temperature drying at 80℃ for 24 h, to obtain MH-polyphosphazene.

[0022] Case three Material for preparing the outer protective sleeve Step 1: First, add CSM and EVA into a two-roll open mill, the roll temperature is 70℃, plasticize for 5 min; then add MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin, maleic anhydride polybutadiene and N,N'-m-phenylene bismaleimide into the plasticized rubber, the roll temperature is controlled at 92℃, mix for 15 min; after mixing, take out the sheet, cool and stop for a while, to obtain the first-stage mixing rubber of the cable outer skin; Step 2: Adjust the roll gap of the open mill to 3.0 mm, re-mix the first-stage mixing rubber on the open mill for 5 min, then add sulfur and accelerator, mix for 10 min, the mixing temperature is 80℃; Step 3: Adjust the roll gap to 2.0 mm, mix uniformly, then take out the sheet, cool and stop for a while, to obtain the second-stage mixing rubber of the cable outer skin; Step 4: Vulcanize the second-stage mixing rubber obtained above on a flat vulcanization machine, the vulcanization temperature is 150℃, the vulcanization pressure is 12 MPa, the vulcanization time is 42 min, to obtain the cable outer skin.

[0023] Case four Material for preparing the outer protective sleeve First, add CSM and EVA into a two-roll open mill, the roll temperature is 70℃, plasticize for 5 min; then add MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin, maleic anhydride polybutadiene and N,N'-m-phenylene bismaleimide into the plasticized rubber, the roll temperature is controlled at 92℃, mix for 15 min; after mixing, take out the sheet, cool and stop for a while, to obtain the first-stage mixing rubber of the cable outer skin; the rest is the same as example 3.

[0024] Case five Material for preparing the outer protective sleeve First, add CSM and EVA into a two-roll open mill, the roll temperature is 70℃, plasticize for 5 min; then add MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin, maleic anhydride polybutadiene and N,N'-m-phenylene bismaleimide into the plasticized rubber, the roll temperature is controlled at 92℃, mix for 15 min; after mixing, take out the sheet, cool and stop for a while, to obtain the first-stage mixing rubber of the cable outer skin; the rest is the same as example 3.

[0025] Case six Material for preparing the outer protective sleeve Firstly, CSM and EVA were added into a two-roll mill, and the roll temperature was 70℃, and plasticizing was performed for 5 min; then, MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin, maleated polybutadiene, and N,N'-m-phenylene bismaleimide were added into the plasticized rubber in sequence, and the roll temperature was controlled at 92℃, and mixing was performed for 15 min; after mixing was completed, the rubber was discharged, and after cooling and standing, the first-stage mixing rubber for cable sheath was obtained; the remaining preparation was the same as in Example 3.

[0026] Comparative case one The ordinary magnesium hydroxide was used to replace the modified magnesium hydroxide in Example 5, and the remaining steps were the same as in Example 5, and the power cable sheath was prepared.

[0027] Comparative case two The same mass of commercially available phosphorus-based flame retardant was used to replace the functional additive in Example 4, and the remaining steps were the same as in Example 4, and the power cable sheath was prepared.

[0028] Performance tests were performed on Examples 3, 4, 5, 6 and Comparative Examples 1 and 2. The oxygen index was determined by the national standard GB / T 2406-2009 "Determination of flammability of plastics - Part 2: Test at room temperature", and the sample size was 100mm * 6mm * 3mm.

[0029] The measured results are shown in the following table: Table 1 Performance test results of the power cable prepared in Examples 3-6 and Comparative Examples 1-2 The measured results are shown in the following table: Test name Oxygen index / % Example 3 29.8 Example 4 34.5 Example 5 31.2 Example 6 35.5 Comparative Example 1 26.3 Comparative Example 2 30.2 As can be seen from Table 1, after adding the self-made MH-polyphosphazene of the application, the heat resistance and flame retardance of the examples are improved. In Examples 3, 5 and 6, by changing the addition amount of MH-polyphosphazene, the limiting oxygen index gradually increases and is greater than that of Comparative Example 1, indicating that the addition of MH-polyphosphazene affects the flame retardance of the material. By comparing Comparative Example 4 and Comparative Example 2, it can be found that changing the flame retardant has a great influence on the flame retardance of the material, therefore, the high-flame-retardant cable sheath prepared by using the application has excellent flame retardance.

[0030] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known methods associated are omitted so as not to obscure the disclosure.

[0031] The foregoing merely illustrates the principles of the application. Various modifications and adaptations will occur to those skilled in the art after consideration of the preceding description. All such modifications and adaptations employing the principles of the application are intended to be within the scope of the application.

Claims

1. A high flame retardant power cable, characterized in that, The cable sheath is prepared from the following components by weight: Chlorosulfonated polyethylene rubber 80 parts, ethylene-vinyl acetate copolymer 30 parts, MH-polyphosphazene 40-100 parts, carbon black 30 parts, antioxidant 1.5 parts, silane coupling agent 2 parts, stearic acid 2 parts, paraffin wax 1.5 parts, maleic anhydride polybutadiene 5 parts, N,N'-m-phenylene bismaleimide 3 parts, sulfur 1-5 parts, accelerator 1.5 parts.

2. A high flame retardant power cable according to claim 1, characterized in that, The preparation method of the cable sheath comprises the following steps: Step 1: In a two-roll open mill, first add CSM and EVA, the roll temperature is 70℃, plasticize for 5min; add MH-polyphosphazene, stearic acid, antioxidant, carbon black, paraffin wax, maleic anhydride polybutadiene, N,N'-m-phenylene bismaleimide in the plasticized rubber in turn, the roll temperature is controlled at 92-98℃, mix for 15min; after mixing is completed, sheet out, cool and stop after storage, to obtain the cable sheath first-stage mix; Step 2: Adjust the roll gap of the open mill to 3.0mm, re-mix the first-stage mix on the open mill for 5min, then add sulfur and accelerator, mix for 10min, the mixing temperature is 80℃; Step 3: Adjust the roll gap to 2.0mm, after mixing evenly, sheet out, cool and stop after storage, to obtain the cable sheath second-stage mix; Step 4: Vulcanize the second-stage mix obtained above on a flat vulcanizing machine, the vulcanization temperature is 150℃, the vulcanization pressure is 12MPa, the vulcanization time is 42min, to obtain the cable sheath.

3. A high flame retardant power cable according to claim 1, characterized in that, The MH-polyphosphazene is prepared by the following steps: Step S1: Soak 100g of magnesium hydroxide in ethanol for 30min, wash, dry, and mix it with an ethanol / water solution to configure a magnesium hydroxide slurry with a certain concentration, and stir uniformly; Step S2: Configuration of silane coupling agent hydrolysis solution: add 50ml of deionized water to a 100ml flask, drop in glacial acetic acid, adjust the solution PH to 3.5-4.5; weigh 2 parts of silane coupling agent and add it to the prepared solution, place the reaction system in a 35℃ water bath, stir and hydrolyze for 30min at this temperature; when the water bath temperature is heated to 60℃, drop the hydrolysis solution into a three-necked flask of magnesium hydroxide slurry, stir and react for 4h at this temperature, cool at room temperature, filter, wash to neutral, and dry at 80℃ for 24h to obtain intermediate product A; Step S3: Add reaction raw materials hexacyclic tricyanophosphine, intermediate product A, melamine and solvent tetrahydrofuran into a flask, stir uniformly, add acid binding agent triethylamine, water bath heating, react for 4-8h at 60℃, filter, wash to neutral, dry at 80℃ for 24h to obtain MH-polyphosphazene.

4. A high flame retardant power cable according to claim 3, characterized in that, The ethanol and water mixture in step S1 is 100mL of ethanol and 20mL of deionized water by volume.

5. A high flame retardant power cable according to claim 3, characterized in that, The amount ratio of silane coupling agent, deionized water and glacial acetic acid in step S2 is 1g:25mL:1.5mL.

6. A high flame retardant power cable according to claim 3, characterized in that, The amount ratio of intermediate product A, hexacyclic tricyanophosphine, melamine, triethylamine and tetrahydrofuran in step S3 is 100g:15g:27g:8.7g:300mL.

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