Fire resistant flame retardant power cable and method of making same

Abstract

This invention relates to the field of cable technology and proposes a fire-resistant and flame-retardant power cable and its preparation method. A fire-resistant and flame-retardant power cable comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following components by weight: 80 parts polyethylene, 16-20 parts silicone rubber material, 1-3 parts antioxidant, 2-5 parts plasticizer, 8-12 parts flame retardant, 3-6 parts compatibilizer, and 0.5-1 part vulcanizing agent. The silicone rubber material comprises the following components by weight: 16-20 parts silicone rubber, 4-6 parts oxide, 3-5 parts acetylacetone metal complex, 2-5 parts magnesium aluminum hydrotalcite, and 0.5-1 part hydroxyl silicone oil. This technical solution solves the problem of poor flame-retardant performance of the sheath layer in related technologies.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a fire-resistant and flame-retardant power cable and its preparation method. Background Technology

[0002] Power cables, as a key carrier for power transmission and distribution, are widely used in construction, transportation, energy, and industry. With the increasing demands for power supply security in modern society, especially in special locations such as high-rise buildings, subways, and nuclear power plants, cables not only need to possess good conductivity and mechanical properties, but also excellent fire resistance and flame retardancy to prevent the spread of fire along the cables in the event of a fire, ensuring personnel safety and equipment integrity.

[0003] Currently, most common power cable sheaths are made of polymer materials such as polyethylene (PE) and polyvinyl chloride (PVC). While these materials possess certain electrical insulation and processing properties, their flame-retardant properties are limited. Under high-temperature or open-flame conditions, they are prone to combustion, melting, and even dripping, not only failing to effectively block flames but also potentially fueling the fire and releasing large amounts of toxic fumes, causing secondary hazards. To improve the fire resistance and flame-retardant properties of cable sheaths, modifications are typically made by adding flame retardants or introducing high-temperature resistant components such as silicone rubber. However, traditional flame-retardant materials often require large amounts to be effective, and high filler content severely affects the processing performance of the sheath material. Although silicone rubber has certain high-temperature resistance properties, its charring ability at high temperatures is still insufficient when used alone, making it difficult to meet the fire resistance and flame-retardant requirements of cables under high-heat conditions.

[0004] Therefore, developing a fire-resistant and flame-retardant power cable with good flame-retardant properties for its sheath layer is of great significance for the use of power cables in high-temperature environments. Summary of the Invention

[0005] This invention proposes a fire-resistant and flame-retardant power cable and its preparation method, which solves the problem of poor flame-retardant performance of the sheath layer of power cables in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] This invention proposes a fire-resistant and flame-retardant power cable, comprising, from the inside out, a conductor, an insulation layer, and a sheath layer, wherein the sheath layer comprises the following components in parts by weight:

[0008] 80 parts polyethylene, 16-20 parts silicone rubber, 1-3 parts antioxidant, 2-5 parts plasticizer, 8-12 parts flame retardant, 3-6 parts compatibilizer, and 0.5-1 part vulcanizing agent;

[0009] The silicone rubber material comprises the following components in parts by weight:

[0010] 16-20 parts silicone rubber, 4-6 parts oxide, 3-5 parts acetylacetone metal complex, 2-5 parts magnesium aluminum hydrotalcite, and 0.5-1 part hydroxyl silicone oil.

[0011] As a further technical solution, the acetylacetone metal complex includes one or more of copper acetylacetone, iron acetylacetone, and platinum acetylacetone.

[0012] As a further technical solution, when the acetylacetone metal complex is iron acetylacetone and platinum acetylacetone, the weight ratio of iron acetylacetone and platinum acetylacetone is 1.5 to 3:1, for example, it can be 1.5:1, 2:1, 2.5:1, or 3:1.

[0013] In the fire-resistant and flame-retardant power cable sheath layer of the present invention, when the weight ratio of iron acetylacetone to platinum acetylacetone is 1.5 to 3:1, the flame-retardant performance of the power cable sheath layer can be further improved, and its oxygen index can be increased to more than 37.6%. When the weight ratio of iron acetylacetone to platinum acetylacetone is outside the range of 1.5 to 3:1, the flame-retardant performance of the power cable sheath layer is slightly worse.

[0014] As a further technical solution, the silicone rubber includes one or more of methyl vinyl silicone rubber, methyl phenyl silicone rubber, and methyl phenyl vinyl silicone rubber, preferably methyl vinyl silicone rubber.

[0015] As a further technical solution, the oxide includes boron oxide.

[0016] In the fire-resistant and flame-retardant power cable sheath layer of the present invention, the oxide includes boron oxide, which is a low-melting-point oxide. When the external temperature of the silicone rubber rises to a certain level, the boron oxide begins to melt and fill the space between the silicon oxide generated by the heated silicone rubber and the magnesium aluminum hydrotalcite filler, playing a connecting role and forming a uniform and stable ceramic layer, ultimately making the power cable sheath layer structure more compact and stable.

[0017] As a further technical solution, the preparation method of the silicone rubber material includes the following steps: blending the silicone rubber, the oxide, and the hydroxyl silicone oil, performing a first mixing, adding the remaining components of the silicone rubber material and mixing, performing a second mixing, to obtain the silicone rubber material.

[0018] As a further technical solution, the time for the first mixing and the second mixing is 10-15 minutes each.

[0019] As a further technical solution, the silicone rubber material also includes 0.3 to 1 part of sulfur- and nitrogen-containing organic compounds, for example, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part, preferably 0.5 to 0.8 parts.

[0020] As a further technical solution, the sulfur- and nitrogen-containing organic compounds include one of diphenylmethylthioacetamide and aminosulfonic acid, preferably diphenylmethylthioacetamide.

[0021] As a further technical solution, the preparation method of the silicone rubber material includes the following steps:

[0022] The magnesium-aluminum hydrotalcite is mixed with a first anhydrous ethanol and dispersed evenly to obtain a suspension. The sulfur- and nitrogen-containing organic compound is mixed with a second anhydrous ethanol and dispersed evenly a second time. The suspension is then added, mixed evenly, concentrated, and dried to obtain a magnesium-aluminum hydrotalcite pretreated product. The silicone rubber, the oxide, and the hydroxyl silicone oil are blended and kneaded for a first time. The magnesium-aluminum hydrotalcite pretreated product and the acetylacetone metal complex are then added and kneaded for a second time to obtain the silicone rubber material.

[0023] Magnesium-aluminum hydrotalcite has a unique layered structure and excellent flame-retardant properties. In this invention, a sulfur- and nitrogen-containing organic compound is introduced into the fire-resistant and flame-retardant power cable sheath layer. This compound includes one of diphenylmethylthioacetamide and aminosulfonic acid, preferably diphenylmethylthioacetamide. First, diphenylmethylthioacetamide is used to modify the magnesium-aluminum hydrotalcite, which can expand the interlayer spacing to a certain extent. When preparing silicone rubber materials, this improves the dispersion of magnesium-aluminum hydrotalcite within the silicone rubber system. After melt-blending the silicone rubber material with polyethylene to obtain the power cable sheath layer, the mechanical properties of the sheath layer are improved. Simultaneously, when the external temperature of the power cable sheath layer rises to a certain level, the sulfur and nitrogen elements formed by the thermal decomposition of the sulfur- and nitrogen-containing organic compounds can participate in the cross-linking of the silicone rubber, forming additional cross-linking points and promoting charring of the silicone rubber material. Ultimately, this improves the mechanical properties of the power cable sheath layer while ensuring its excellent flame-retardant performance.

[0024] In the fire-resistant and flame-retardant power cable sheath layer of the present invention, by optimizing and adjusting the amount of sulfur- and nitrogen-containing organic compounds added, when the amount of sulfur- and nitrogen-containing organic compounds added is 0.5 to 0.8 parts, the mechanical properties of the power cable sheath layer can be further improved.

[0025] As a further technical solution, when the first dispersion is uniform, the stirring speed is 600~800 rpm and the time is 20~30 min.

[0026] As a further technical solution, when the mixture is homogeneous, it is refluxed and stirred at 600~800 rpm for 4~5 hours.

[0027] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 1024, and antioxidant 1076, preferably antioxidant 1010;

[0028] The plasticizer includes one or two of dioctyl phthalate and dioctyl sebacate, preferably dioctyl phthalate;

[0029] The flame retardant includes one or more of phosphorus-based flame retardants, hydroxide-based flame retardants, and nitrogen-based flame retardants;

[0030] The compatibilizer includes maleic anhydride-grafted polyethylene.

[0031] The vulcanizing agent includes one of dicumyl peroxide and benzoyl peroxide, preferably dicumyl peroxide.

[0032] In the sheath layer of the fire-resistant and flame-retardant power cable of the present invention, the phosphorus-based flame retardant can be any one or more conventional phosphorus-based flame retardants in the art, such as ammonium polyphosphate or triisopropylphenyl phosphate; the hydroxide flame retardant can be any one or more conventional hydroxide flame retardants in the art, such as magnesium hydroxide or aluminum hydroxide; and the nitrogen-based flame retardant can be any one or more conventional nitrogen-based flame retardants in the art, such as melamine or melamine urea, preferably ammonium polyphosphate.

[0033] As a further technical solution, the conductor is one of an aluminum alloy conductor and a copper alloy conductor, preferably an aluminum alloy conductor;

[0034] The insulation layer is a polyethylene insulation layer.

[0035] This invention proposes a method for preparing a fire-resistant and flame-retardant power cable, which includes the following steps: after setting the insulation layer on the outside of the conductor, the components of the sheath layer are blended, extruded onto the outside of the insulation layer, and vulcanized to obtain the fire-resistant and flame-retardant power cable.

[0036] The working principle and beneficial effects of this invention are as follows:

[0037] This invention relates to a fire-resistant and flame-retardant power cable. A silicone rubber material is prepared using silicone rubber, oxides, acetylacetone metal complexes, magnesium aluminum hydrotalcite, and hydroxyl silicone oil as raw materials. Adding this material to the sheath layer effectively improves the flame-retardant performance of the power cable sheath. The silicone rubber material uses silicone rubber as the main material, with acetylacetone metal complexes added. When the external ambient temperature of the cable rises to a certain value, the addition of the acetylacetone metal complexes can catalyze the formation of a carbon layer in the silicone rubber at a relatively low temperature. This results in a dense and stable structure in the power cable sheath layer at high temperatures, thus improving the flame-retardant performance of the power cable sheath layer. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] In the following examples and comparative examples, methyl vinyl silicone rubber, model 110-2S, was purchased from Ningbo Daoruo Organosilicon Co., Ltd.; platinum acetylacetone had an active ingredient content of 98% and CAS number 15170-57-7; iron acetylacetone had an active ingredient content of 99% and CAS number 14024-18-1; copper acetylacetone had an active ingredient content of 99% and CAS number 13395-16-9; the polyethylene was linear low-density polyethylene, model DFDA-8320; in the polyethylene insulation layer, the polyethylene was linear low-density polyethylene, model DFDA-8320; the average particle size of boron oxide was 50 nm; and the average particle size of magnesium aluminum hydrotalcite was 20 μm.

[0040] Example 1

[0041] A method for preparing a fire-resistant and flame-retardant power cable includes the following steps:

[0042] S1. Mix 16 parts of methyl vinyl silicone rubber, 4 parts of boron oxide, and 0.5 parts of hydroxyl silicone oil, and knead for 10 minutes. Add 2 parts of magnesium aluminum hydrotalcite and 3 parts of acetylacetone platinum, and knead for 10 minutes to obtain silicone rubber material.

[0043] S2. After setting a polyethylene insulation layer on the outside of the aluminum alloy conductor, 80 parts of polyethylene, 16 parts of the above-mentioned silicone rubber material, 1 part of antioxidant 1010, 2 parts of dioctyl phthalate, 8 parts of ammonium polyphosphate, 3 parts of maleic anhydride-grafted polyethylene and 0.5 parts of dicumyl peroxide are blended, extruded on the outside of the polyethylene insulation layer, and vulcanized to obtain a fire-resistant and flame-retardant power cable.

[0044] Example 2

[0045] A method for preparing a fire-resistant and flame-retardant power cable includes the following steps:

[0046] S1. Mix 18 parts of methyl vinyl silicone rubber, 5 parts of boron oxide and 1 part of hydroxyl silicone oil, knead for 15 min, add 4 parts of magnesium aluminum hydrotalcite and 5 parts of acetylacetone iron, knead for 15 min to obtain silicone rubber material.

[0047] S2. After setting a polyethylene insulation layer on the outside of the aluminum alloy conductor, 80 parts of polyethylene, 18 parts of the above-mentioned silicone rubber material, 2 parts of antioxidant 1010, 3 parts of dioctyl phthalate, 10 parts of ammonium polyphosphate, 4.5 parts of maleic anhydride-grafted polyethylene and 1 part of dicumyl peroxide are blended, extruded on the outside of the polyethylene insulation layer, and vulcanized to obtain a fire-resistant and flame-retardant power cable.

[0048] Example 3

[0049] A method for preparing a fire-resistant and flame-retardant power cable includes the following steps:

[0050] S1. Mix 20 parts of methyl vinyl silicone rubber, 6 parts of boron oxide and 1 part of hydroxyl silicone oil, knead for 15 min, add 5 parts of magnesium aluminum hydrotalcite and 5 parts of copper acetylacetonate, knead for 15 min to obtain silicone rubber material.

[0051] S2. After setting a polyethylene insulation layer on the outside of the aluminum alloy conductor, 80 parts of polyethylene, 20 parts of the above-mentioned silicone rubber material, 3 parts of antioxidant 1010, 5 parts of dioctyl phthalate, 12 parts of ammonium polyphosphate, 6 parts of maleic anhydride-grafted polyethylene and 1 part of dicumyl peroxide are blended, extruded on the outside of the polyethylene insulation layer, and vulcanized to obtain a fire-resistant and flame-retardant power cable.

[0052] Example 4

[0053] The only difference between this embodiment and Embodiment 2 is that in this embodiment, 5 parts of ferric acetylacetone are replaced with 2.5 parts of ferric acetylacetone and 2.5 parts of platinum acetylacetone.

[0054] Example 5

[0055] The only difference between this embodiment and Embodiment 2 is that in this embodiment, 5 parts of ferric acetylacetone are replaced with 4 parts of ferric acetylacetone and 1 part of platinum acetylacetone.

[0056] Example 6

[0057] The only difference between this embodiment and Embodiment 2 is that in this embodiment, 5 parts of ferric acetylacetone are replaced with 3 parts of ferric acetylacetone and 2 parts of platinum acetylacetone.

[0058] Example 7

[0059] The only difference between this embodiment and Embodiment 2 is that in this embodiment, 5 parts of ferric acetylacetone are replaced with 3.75 parts of ferric acetylacetone and 1.25 parts of platinum acetylacetone.

[0060] Example 8

[0061] The only difference between this embodiment and Embodiment 7 is that the preparation method of the fire-resistant and flame-retardant power cable in this embodiment is different, specifically:

[0062] S0. Mix 4 parts of magnesium aluminum hydrotalcite with 40 parts of anhydrous ethanol and stir at 700 rpm for 25 min to obtain a suspension; mix 0.3 parts of aminosulfonic acid with 5 parts of anhydrous ethanol, disperse evenly, add the above suspension, reflux and stir at 700 rpm for 5 h, concentrate, and dry to obtain magnesium aluminum hydrotalcite pretreated material.

[0063] S1. Mix 18 parts of methyl vinyl silicone rubber, 5 parts of boron oxide, and 0.8 parts of hydroxyl silicone oil, and knead for 15 minutes. Add 4 parts of magnesium aluminum hydrotalcite pretreatment material and 5 parts of acetylacetone iron, and knead for 15 minutes to obtain silicone rubber material.

[0064] S2. After setting a polyethylene insulation layer on the outside of the aluminum alloy conductor, 80 parts of polyethylene, 18 parts of the above-mentioned silicone rubber material, 2 parts of antioxidant 1010, 3 parts of dioctyl phthalate, 10 parts of ammonium polyphosphate, 4.5 parts of maleic anhydride-grafted polyethylene and 1 part of dicumyl peroxide are blended, extruded on the outside of the polyethylene insulation layer, and vulcanized to obtain a fire-resistant and flame-retardant power cable.

[0065] Example 9

[0066] The only difference between this embodiment and Embodiment 8 is that in this embodiment, aminosulfonic acid is replaced with an equal amount of diphenylmethylthioacetamide.

[0067] Example 10

[0068] The only difference between this embodiment and Example 8 is that in this embodiment, 0.5 parts of diphenylmethylthioacetamide are added.

[0069] Example 11

[0070] The only difference between this embodiment and Example 8 is that in this embodiment, 0.8 parts of diphenylmethylthioacetamide are added.

[0071] Example 12

[0072] The only difference between this embodiment and Example 8 is that in this embodiment, the amount of diphenylmethylthioacetamide added is 1 part.

[0073] Comparative Example 1

[0074] The only difference between this comparative example and Example 2 is that in this comparative example, the silicone rubber material is replaced with an equal amount of methyl vinyl silicone rubber.

[0075] Comparative Example 2

[0076] A method for preparing a fire-resistant and flame-retardant power cable includes the following steps:

[0077] After setting a polyethylene insulation layer on the outside of the aluminum alloy conductor, 80 parts of polyethylene, 18 parts of methyl vinyl silicone rubber, 5 parts of boron oxide, 1 part of hydroxyl silicone oil, 4 parts of magnesium aluminum hydrotalcite, 5 parts of acetylacetone iron, 2 parts of antioxidant 1010, 3 parts of dioctyl phthalate, 10 parts of ammonium polyphosphate, 4.5 parts of maleic anhydride grafted polyethylene and 1 part of dicumyl peroxide are blended, extruded on the outside of the polyethylene insulation layer, and vulcanized to obtain a fire-resistant and flame-retardant power cable.

[0078] Experimental Example 1

[0079] Three samples were cut from the sheath of the power cables prepared in Examples 1-12 and Comparative Examples 1-2 to form Type IV oxygen index samples. The oxygen index was tested according to the method in GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". The diffusion ignition method was used in the test. The test result is the average value of the three samples. The test results are shown in Table 1.

[0080] Table 1. Flame retardant performance test results of Examples 1-12 and Comparative Examples 1-2

[0081]

[0082] As can be seen from Table 1, compared with Comparative Examples 1-2, the oxygen index of the power cable sheath prepared in Examples 1-12 is improved, indicating that adding the silicone rubber material obtained by mixing silicone rubber, oxide, acetylacetone metal complex, magnesium aluminum hydrotalcite, and hydroxyl silicone oil into the sheath can effectively improve the flame retardant performance of the power cable sheath.

[0083] Experiment Example 2

[0084] Three samples were cut from each of the power cable sheaths prepared in Examples 7-12. The samples were prepared into dumbbell-shaped specimens with a thickness of 2 mm according to the method in GB / T2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods for Thickness and Dimensional Measurement and Mechanical Properties Test". The tensile strength was tested and the test results are shown in Table 2.

[0085] Table 2 shows the mechanical property test results of Examples 7-12.

[0086]

[0087] As can be seen from Table 2, compared with Example 7, the tensile strength of the power cable sheath layer prepared in Examples 8 to 12 is improved. This indicates that when sulfur-containing and nitrogen-containing organic compounds are added to the silicone rubber material, the modification treatment of magnesium aluminum hydrotalcite with sulfur-containing and nitrogen-containing organic compounds can effectively improve the mechanical properties of the power cable sheath layer, increasing its tensile strength to above 27.4 MPa.

[0088] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fire-resistant and flame-retardant power cable, comprising, from the inside out, a conductor, an insulation layer, and a sheath layer, characterized in that, The sheath layer comprises the following components in parts by weight: 80 parts polyethylene, 16-20 parts silicone rubber, 1-3 parts antioxidant, 2-5 parts plasticizer, 8-12 parts flame retardant, 3-6 parts compatibilizer, and 0.5-1 part vulcanizing agent; The silicone rubber material comprises the following components in parts by weight: 16-20 parts silicone rubber, 4-6 parts oxide, 3-5 parts acetylacetone metal complex, 2-5 parts magnesium aluminum hydrotalcite, and 0.5-1 part hydroxyl silicone oil; The acetylacetone metal complex is iron acetylacetone and platinum acetylacetone, and the weight ratio of iron acetylacetone to platinum acetylacetone is 1.5~3:1; The silicone rubber material also includes sulfur- and nitrogen-containing organic compounds; The sulfur- and nitrogen-containing organic compounds include diphenylmethylthioacetamide.

2. The fire-resistant and flame-retardant power cable according to claim 1, characterized in that, The silicone rubber includes one or more of methyl vinyl silicone rubber, methyl phenyl silicone rubber, and methyl phenyl vinyl silicone rubber.

3. The fire-resistant and flame-retardant power cable according to claim 1, characterized in that, The oxide includes boron oxide.

4. The fire-resistant and flame-retardant power cable according to claim 1, characterized in that, The diphenylmethylthioacetamide is present in amounts of 0.5 to 0.8 parts.

5. A fire-resistant and flame-retardant power cable according to claim 4, characterized in that, The preparation method of the silicone rubber material includes the following steps: The magnesium-aluminum hydrotalcite is mixed with a first anhydrous ethanol and dispersed evenly to obtain a suspension. The sulfur- and nitrogen-containing organic compound is mixed with a second anhydrous ethanol and dispersed evenly a second time. The suspension is then added, mixed evenly, concentrated, and dried to obtain a magnesium-aluminum hydrotalcite pretreated product. The silicone rubber, the oxide, and the hydroxyl silicone oil are blended and kneaded for a first time. The magnesium-aluminum hydrotalcite pretreated product and the acetylacetone metal complex are then added and kneaded for a second time to obtain the silicone rubber material.

6. The fire-resistant and flame-retardant power cable according to claim 1, characterized in that, The antioxidant includes one or more of antioxidant 1010, antioxidant 1024, and antioxidant 1076; The plasticizer includes one or both of dioctyl phthalate and dioctyl sebacate. The flame retardant includes one or more of phosphorus-based flame retardants, hydroxide-based flame retardants, and nitrogen-based flame retardants; The compatibilizer includes maleic anhydride-grafted polyethylene. The vulcanizing agent includes one of dicumyl peroxide and benzoyl peroxide.

7. A method for preparing a fire-resistant and flame-retardant power cable, used to prepare a fire-resistant and flame-retardant power cable as described in any one of claims 1 to 6, characterized in that, Includes the following steps: After the insulation layer is applied to the outside of the conductor, the components of the sheath layer are blended, extruded onto the outside of the insulation layer, and vulcanized to obtain the fire-resistant and flame-retardant power cable.

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