Flexible high-temperature-resistant and fire-resistant control cable and preparation method thereof

Abstract

The invention relates to the technical field of cables, and discloses a flexible high-temperature-resistant fire-resistant control cable and a preparation method thereof.The control cable comprises a high-temperature-resistant fire-resistant sheath layer, and the sheath layer comprises, by weight, 100 parts of polypropylene, 2-5 parts of nano silicon dioxide, 7-15 parts of a phthalic diamide polymer, 20-30 parts of ammonium polyphosphate and the like; the nano silicon dioxide is not easy to agglomerate, has good dispersity and has a better toughening effect, the impact strength and flexibility of the polypropylene sheath layer are improved, the phthalamide polymer contains a large amount of imide nitrogen heterocyclic rings and nitrogen elements, a better nitrogen-phosphorus flame-retardant system is formed by the phthalamide polymer and ammonium polyphosphate, the limit oxygen index of polypropylene is improved, and the flame-retardant performance of the polypropylene sheath layer is improved. And the imide ring has good high-temperature resistance and is not easy to thermally decompose, so that the thermal decomposition temperature and the high-temperature resistance of the polypropylene sheath layer can be improved.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a flexible high-temperature and fire-resistant control cable and its preparation method. Background Technology

[0002] Polypropylene (PP) possesses advantages such as high strength, high hardness, low dielectric constant, and good weather resistance, making it widely used in cable sheathing materials. However, PP is easily flammable when exposed to open flames and has poor toughness, resulting in poor flame retardancy and flexibility in PP sheathing materials. This hinders its practical application in flame-retardant cables and other applications. Therefore, flame-retardant and other modifications are necessary for PP and its sheathing materials.

[0003] Common flame retardants for polypropylene include inorganic flame retardants such as aluminum hydroxide and organic flame retardants such as ammonium polyphosphate. Among them, ammonium polyphosphate is halogen-free and environmentally friendly, has high processing adaptability, and has flame retardant effects such as heat insulation, oxygen isolation and smoke suppression. However, the flame retardant effect of using ammonium polyphosphate alone is not good. It needs to be compounded with nitrogen-containing flame retardant charring agents to achieve better flame retardant effect. In addition, the addition of ammonium polyphosphate will affect the heat resistance and high temperature resistance of polypropylene. Summary of the Invention

[0004] Technical problem solved: This invention solves the problem of poor flexibility and flame retardancy of the polypropylene sheath layer.

[0005] The technical solution of the present invention is: a flexible high-temperature and fire-resistant control cable, comprising a conductor, an insulation layer, and a flexible high-temperature and fire-resistant sheath layer; The preparation method of the flexible high-temperature resistant and fire-resistant sheath layer is as follows: (1) N-(2-bromoethyl)phthalimide, diallylamine, and an acid-binding agent were added to N,N-dimethylformamide to carry out a substitution reaction. After cooling, a saturated sodium bicarbonate solution was added, and the mixture was extracted with ethyl acetate. After separation, the organic layer was dried to remove water, and after rotary evaporation, it was separated by column chromatography to obtain N-[2-(diallylamine)ethyl]phthalimide. The reaction formula is: .

[0006] (2) N-[2-(diallylamine)ethyl]phthalimide was added to the reaction solvent, stirred, and then an aqueous solution of lysine and sodium hydroxide was added. The polymerization reaction was carried out under a nitrogen atmosphere. After filtration, the polymer was washed with water and ethanol and dried to obtain the phthalamide polymer. The reaction formula is: .

[0007] (3) Mix nano-silica and phthalamide polymer in a high-speed mixer, then add polypropylene, ammonium polyphosphate and antioxidant, continue mixing, melt blend the mixture in a screw extruder and extrude it to obtain a high-temperature resistant fire-resistant sheath layer.

[0008] Furthermore, in (1), the molar ratio of N-(2-bromoethyl)phthalimide, diallylamine, and acid-binding agent is (1-1.2):1:(2.5-3.2).

[0009] Furthermore, in (1), the acid-binding agent is potassium carbonate or sodium carbonate.

[0010] Furthermore, the substitution reaction in (1) is carried out at 80-90℃ for 18-30h.

[0011] Furthermore, in (2), the reaction solvent is methanol or ethanol.

[0012] Furthermore, in (2), the molar ratio of N-[2-(diallylamine)ethyl]phthalimide, lysine, and sodium hydroxide is (1.04-1.1):1:(1-1.02).

[0013] Furthermore, in (2), the polymerization reaction is refluxed at 50-70℃ for 24-36 hours.

[0014] Furthermore, in (3), the amount of polypropylene is 100 parts by weight, nano silica is 2-5 parts by weight, phthalamide polymer is 7-15 parts by weight, ammonium polyphosphate is 20-30 parts by weight, dicumyl peroxide is 0.4-0.7 parts by weight, and antioxidant is 0.1-0.25 parts by weight.

[0015] Furthermore, in (3), the temperature of zones 1-5 of the screw extruder is 170-200℃, and the screw speed is 50-100r / min.

[0016] The beneficial technical effects of this invention are as follows: N-[2-(diallylamine)ethyl]phthalimide and lysine undergo an addition polymerization reaction to obtain a phthalamide polymer. This polymer is then compounded with nano-silica, polypropylene, ammonium polyphosphate, etc., to obtain a flexible high-temperature resistant and fire-resistant sheath layer and its cable. The phthalamide polymer contains a large number of carboxyl groups, which interact with the surface of nano-silica, coating the silica surface and helping to reduce silica agglomeration and improve dispersibility. Simultaneously, the phthalamide polymer contains terminal alkenyl groups, which undergo a chemical cross-linking reaction with polypropylene during extrusion, enhancing the interfacial force between silica and polypropylene. This results in better toughening of the nano-silica, significantly improving the impact strength and flexibility of the polypropylene sheath layer. The uniformly dispersed nano-silica also enhances the high-temperature resistance of polypropylene.

[0017] The phthalamide polymer of the present invention contains a large amount of imide nitrogen-containing heterocycles and nitrogen elements, which form a better nitrogen-phosphorus flame retardant system with ammonium polyphosphate, improves the limiting oxygen index of polypropylene, and enhances its flame retardant performance. The imide rings have good high-temperature resistance and are not easily thermally decomposed. Adding them to polypropylene helps to increase the thermal decomposition temperature, and improves the high-temperature resistance of the polypropylene sheath layer. Detailed Implementation

[0018] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0019] Example 1: A flexible high-temperature and fire-resistant control cable, comprising a copper conductor, a polyvinyl chloride insulation layer, and a flexible high-temperature and fire-resistant sheath layer; the preparation method of the flexible high-temperature and fire-resistant sheath layer is as follows: (1) Add 1.2 mol N-(2-bromoethyl)phthalimide, 1 mol diallylamine, and 2.5 mol potassium carbonate to 2.5 L N,N-dimethylformamide, heat to 90 °C, stir for 18 h, cool, add saturated sodium bicarbonate solution, extract with ethyl acetate, separate, dry the organic layer to remove water, evaporate by rotary evaporation, and separate by column chromatography. The mobile phase is a mixture of ethyl acetate and petroleum ether to obtain N-[2-(diallylamine)ethyl]phthalimide.

[0020] (2) Add 0.52 mol N-[2-(diallylamine)ethyl]phthalimide to 4 L of methanol, stir, and then add 600 mL of an aqueous solution containing 0.5 mol lysine and 0.5 mol sodium hydroxide. Heat to 60 °C in a nitrogen atmosphere, reflux for 36 h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0021] (3) Mix 40g of nano silica and 140g of phthalamide polymer in a high-speed mixer for 40min, then add 2kg of polypropylene, 600g of ammonium polyphosphate, 8g of dicumyl peroxide and 5g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 60r / min. Extrude the mixture to obtain a high-temperature resistant and fire-resistant sheath layer.

[0022] Example 2: A flexible high-temperature and fire-resistant control cable, comprising an aluminum conductor, a polyvinyl chloride insulation layer, and a flexible high-temperature and fire-resistant sheath layer; the preparation method of the flexible high-temperature and fire-resistant sheath layer is as follows: (1) Add 1 mol of N-(2-bromoethyl)phthalimide, 1 mol of diallylamine, and 3.2 mol of sodium carbonate to 3 L of N,N-dimethylformamide, heat to 80 °C, stir for 30 h, cool, add saturated sodium bicarbonate solution, extract with ethyl acetate, separate, dry the organic layer to remove water, evaporate by rotary evaporation, and separate by column chromatography. The mobile phase is a mixed solution of ethyl acetate and petroleum ether to obtain N-[2-(diallylamine)ethyl]phthalimide.

[0023] (2) Add 0.55 mol N-[2-(diallylamine)ethyl]phthalimide to 4 L of ethanol, stir, and then add 800 mL of an aqueous solution containing 0.5 mol lysine and 0.5 mol sodium hydroxide. Heat to 70 °C in a nitrogen atmosphere, reflux for 24 h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0024] (3) Mix 60g of nano silica and 200g of phthalamide polymer in a high-speed mixer for 40min, then add 2kg of polypropylene, 530g of ammonium polyphosphate, 10g of dicumyl peroxide and 4g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 100r / min. Extrude the mixture to obtain a high-temperature resistant and fire-resistant sheath layer.

[0025] Example 3: A flexible high-temperature and fire-resistant control cable, comprising a copper conductor, a polyvinyl chloride insulation layer, and a flexible high-temperature and fire-resistant sheath layer; the preparation method of the flexible high-temperature and fire-resistant sheath layer is as follows: (1) Add 0.54 mol N-[2-(diallylamine)ethyl]phthalimide (prepared according to the method of Example 1) to 4L methanol, stir, add 700 mL of aqueous solution containing 0.5 mol lysine and 0.5 mol sodium hydroxide, heat to 50°C in a nitrogen atmosphere, reflux for 36 h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0026] (2) Mix 80g of nano silica and 250g of phthalamide polymer in a high-speed mixer for 60min, then add 2kg of polypropylene, 460g of ammonium polyphosphate, 12g of dicumyl peroxide and 3.2g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures in zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 40r / min. Extrude the mixture to obtain a high-temperature resistant and fire-resistant sheath layer.

[0027] Example 4: A flexible high-temperature and fire-resistant control cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, and a flexible high-temperature and fire-resistant sheath layer; the preparation method of the flexible high-temperature and fire-resistant sheath layer is as follows: (1) Add 0.52 mol N-[2-(diallylamine)ethyl]phthalimide (prepared according to the method of Example 1) to 4L methanol, stir, add 600 mL of aqueous solution containing 0.5 mol lysine and 0.5 mol sodium hydroxide, heat to 60°C in a nitrogen atmosphere, reflux for 24 h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0028] (2) Mix 100g of nano silica and 300g of phthalamide polymer in a high-speed mixer for 60min, then add 2kg of polypropylene, 400g of ammonium polyphosphate, 14g of dicumyl peroxide and 2g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 100r / min. Extrude the mixture to obtain a high-temperature resistant and fire-resistant sheath layer.

[0029] Comparative Example 1: A flexible high-temperature and fire-resistant control cable, composed of a copper conductor, a polyvinyl chloride insulation layer, and a sheath layer; the method for preparing the sheath layer is as follows: (1) Mix 40g of nano silica, 2kg of polypropylene, 600g of ammonium polyphosphate, 8g of dicumyl peroxide and 5g of antioxidant 1010 in a high-speed mixer for 20min. Then, melt-blend the mixture in a screw extruder. The temperatures in zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 60r / min. Extrusion molding is then performed to obtain the sheath layer.

[0030] Comparative Example 2: A flexible high-temperature and fire-resistant control cable, comprising a copper conductor, a polyvinyl chloride insulation layer, and a sheath layer; the method for preparing the sheath layer is as follows: (1) Add 0.52 mol N-[2-(diallylamine)ethyl]phthalimide (prepared according to the method of Example 1) to 4L methanol, stir, add 600mL of aqueous solution containing 0.5 mol ethylenediamine, heat to 60°C in a nitrogen atmosphere, reflux for 36h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0031] (2) Mix 40g of nano silica and 140g of phthalamide polymer in a high-speed mixer for 40min, then add 2kg of polypropylene, 600g of ammonium polyphosphate, 8g of dicumyl peroxide and 5g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 60r / min. Extrude to obtain the sheath layer.

[0032] Comparative Example 3: A flexible high-temperature and fire-resistant control cable, composed of a copper conductor, a polyvinyl chloride insulation layer, and a sheath layer; the method for preparing the sheath layer is as follows: (1) Add 0.52 mol N-methyldiallylamine to 4L methanol, stir, and then add 600 mL of an aqueous solution containing 0.5 mol lysine and 0.5 mol sodium hydroxide. Heat to 60°C in a nitrogen atmosphere, reflux for 36 h, filter, wash with water and ethanol, and dry to obtain N-methyldiallylamine polymer.

[0033] (2) Mix 40g of nano silica and 140g of N-methyldiallylamine polymer in a high-speed mixer for 40min, then add 2kg of polypropylene, 600g of ammonium polyphosphate, 8g of dicumyl peroxide and 5g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 60r / min. Extrude the mixture to obtain the sheath layer.

[0034] Comparative Example 4: A flexible high-temperature and fire-resistant control cable, composed of a copper conductor, a polyvinyl chloride insulation layer, and a sheath layer; the method for preparing the sheath layer is as follows: (1) Add 0.5 mol N-[2-(diallylamine)ethyl]phthalimide to 4 L methanol, stir, and then add 600 mL of an aqueous solution containing 0.52 mol lysine and 0.52 mol sodium hydroxide. Heat to 60 °C in a nitrogen atmosphere, reflux for 36 h, filter, wash with water and ethanol, and dry to obtain phthalamide polymer.

[0035] (2) Mix 40g of nano silica and 140g of phthalamide polymer in a high-speed mixer for 40min, then add 2kg of polypropylene, 600g of ammonium polyphosphate, 8g of dicumyl peroxide and 5g of antioxidant 1010, and continue mixing for 20min. Then melt-blend the mixture in a screw extruder. The temperatures of zones 1-5 are 170℃, 185℃, 195℃, 200℃ and 195℃, and the screw speed is 60r / min. Extrude the mixture to obtain a high-temperature resistant and fire-resistant sheath layer.

[0036] Performance testing: The components are mixed in a mixer (the amount of each component and the mixing method are described in the above examples and comparative examples), melt-blended by a screw extruder, extruded and granulated, and then injection molded into test strips by an injection molding machine. The combustion behavior is tested according to GB / T 2406.1-2008 standard, and the impact performance is tested according to GB / T 1843-2008 standard.

[0037] Thermal properties were tested using a thermogravimetric analyzer in a nitrogen atmosphere at a heating rate of 5℃ / min and a temperature range of 20-800℃.

[0038] Table 1 Performance of Sheath Layer Test Samples

[0039] The nano-silica in Comparative Example 1 exhibited poor dispersibility, resulting in poor toughening effect and low impact strength of the polypropylene sheath layer.

[0040] The phthalamide polymers added in each embodiment contain a large number of carboxyl groups, which interact with the surface of nano-silica, coating the silica surface and helping to reduce silica agglomeration and improve dispersibility. At the same time, the phthalamide polymers contain terminal alkenyl groups, which undergo chemical cross-linking reactions with polypropylene during extrusion, enhancing the interfacial forces between silica and polypropylene, giving nano-silica a better toughening effect, significantly improving the impact strength and flexibility of the polypropylene sheath layer. The uniformly dispersed nano-silica also improves the high-temperature resistance of polypropylene. Furthermore, the phthalamide polymers contain a large number of imide nitrogen-containing heterocycles and nitrogen elements, forming a better nitrogen-phosphorus flame retardant system with ammonium polyphosphate, further improving the limiting oxygen index of polypropylene and enhancing its flame retardant properties. The imide rings have good high-temperature resistance and are not easily thermally decomposed, which helps to increase the thermal decomposition temperature of polypropylene and improve its high-temperature resistance.

[0041] The phthalamide polymer in Comparative Example 2 does not contain carboxyl groups, making it difficult to form an interaction with the surface of nano-silica and difficult to coat the surface of silica, which is not conducive to reducing agglomeration. The nano-silica is not dispersible, and the interfacial force with polypropylene is weak, resulting in poor toughening effect. Its impact strength is lower than that of Example 1, and its initial thermal decomposition temperature is also lower than that of Example 1.

[0042] The N-methyldiallylamine polymer of Comparative Example 3 does not contain an imide ring, and its limiting oxygen index and initial thermal decomposition temperature are lower than those of Example 1.

[0043] In Comparative Example 4, the excess of lysine resulted in the preparation of a phthalamide polymer that did not contain terminal alkenyl groups. This prevented it from undergoing a chemical crosslinking reaction with polypropylene, making it difficult to enhance the interfacial forces between silica and polypropylene. Consequently, the toughening effect was poor, and the impact strength was lower than that of Example 1.

[0044] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a flexible high-temperature and fire-resistant control cable, characterized in that, The control cable includes a conductor, an insulation layer, and a flexible high-temperature and fire-resistant sheath. The flexible high-temperature resistant and fire-resistant sheath layer comprises 100 parts by weight of polypropylene, 2-5 parts by weight of nano-silica, 7-15 parts by weight of phthalamide polymer, 20-30 parts by weight of ammonium polyphosphate, 0.4-0.7 parts by weight of dicumyl peroxide, and 0.1-0.25 parts by weight of antioxidant. The preparation method of the phthalamide polymer is as follows: N-[2-(diallylamine)ethyl]phthalimide is added to the reaction solvent, and after stirring, an aqueous solution of lysine and sodium hydroxide is added. The polymerization reaction is carried out under a nitrogen atmosphere, filtered, washed, and dried to obtain the phthalamide polymer.

2. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 1, characterized in that, The reaction solvent is methanol or ethanol.

3. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 1, characterized in that, The molar ratio of N-[2-(diallylamine)ethyl]phthalimide, lysine, and sodium hydroxide is (1.04-1.1):1:(1-1.02).

4. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 1, characterized in that, The polymerization reaction is refluxed at 50-70°C for 24-36 hours.

5. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 1, characterized in that, The preparation method of N-[2-(diallylamine)ethyl]phthalimide is as follows: N-(2-bromoethyl)phthalimide, diallylamine, and an acid-binding agent are added to N,N-dimethylformamide, heated to 80-90℃, reacted for 18-30h, cooled, and then saturated sodium bicarbonate solution is added. After extraction and separation, the organic layer is dried to remove water, and after rotary evaporation, it is separated by column chromatography to obtain N-[2-(diallylamine)ethyl]phthalimide.

6. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 5, characterized in that, The molar ratio of N-(2-bromoethyl)phthalimide, diallylamine, and acid-binding agent is (1-1.2):1:(2.5-3.2).

7. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 5, characterized in that, The acid-binding agent is potassium carbonate or sodium carbonate.

8. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 1, characterized in that, The preparation method of the flexible high-temperature resistant and fire-resistant sheath layer is as follows: nano-silica and phthalamide polymer are mixed in a high-speed mixer, then polypropylene, ammonium polyphosphate, dicumyl peroxide and antioxidant are added, and mixing is continued. The mixture is then melt-blended and extruded in a screw extruder to obtain the high-temperature resistant and fire-resistant sheath layer.

9. The method for preparing the flexible high-temperature and fire-resistant control cable according to claim 8, characterized in that, The temperature of zones 1-5 of the screw extruder is 170-200℃, and the screw speed is 50-100 r / min.

10. A flexible high-temperature resistant and fire-resistant control cable obtained by the preparation method according to any one of claims 1-9.

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