Protective sleeve for flame-retardant cable, preparation method and flame-retardant cable

Abstract

The invention relates to a protective sleeve for a flame-retardant cable, a preparation method of the protective sleeve and the flame-retardant cable. The protective sleeve for the flame-retardant cable comprises the following components in parts by weight: 40-60 parts of chlorinated polyethylene, 1-10 parts of a polyolefin elastomer, 1-10 parts of modified magnesium hydroxide, 1-10 parts of an antimony-containing flame retardant and 1-8 parts of modified magnesium-aluminum hydrotalcite. The flame-retardant cable comprises a conductor, an insulating layer and the protective sleeve, wherein the insulating layer comprises the following components in parts by weight: 40-60 parts of ethylene propylene diene monomer and 30-60 parts of modified magnesium hydroxide. The formula of the protective sleeve for the flame-retardant cable is reasonably designed, so that the prepared protective sleeve has excellent flame retardance, torsion resistance and aging resistance. The flame-retardant cable is further matched with a protective sleeve and an insulating layer containing modified magnesium hydroxide, and the flame-retardant cable which is suitable for wind power generation and passes an A-type bunching combustion test is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a protective sleeve for a flame-retardant cable, a preparation method thereof and a flame-retardant cable. BACKGROUND

[0002] At present, with the continuous upgrading of wind power technology and the continuous expansion of installed capacity, the performance requirements of key components for the whole machine are increasingly improved, especially the safety and reliability of the internal cable of the wind turbine are put forward with higher standards, which must meet the dual technical indexes of high flame-retardant fireproof grade and long-term stable operation to effectively prevent fire risk and ensure long-term safe operation of the wind turbine.

[0003] Such stringent technical requirements are due to the obvious shortcomings of traditional cable materials in terms of flame retardant performance and environmental adaptability. In terms of safety performance, although the traditional cable sheath material has initial flame retardancy, a large amount of toxic smoke and hydrogen halide gas is released in the fire, which seriously threatens the safety of personnel escaping from airtight space (such as offshore wind turbine cabin). Although halogen-free materials can avoid halogen toxicity, their flame retardant grade generally only reaches C-class flame retardant standard, which cannot meet the A-class flame retardant requirement for dense laying in the wind turbine cabin.

[0004] CN102634105A discloses a soft halogen-free flame-retardant cable material. Aluminum hydroxide, magnesium hydroxide and the like are used as flame retardants, which have the advantages of low price, wide source, non-toxicity, non-corrosion and no secondary pollution in combustion. By blending low-hardness thermoplastic elastomer with polyolefin resin, the softness of the material is greatly improved. However, due to the poor dispersibility and affinity of aluminum hydroxide and magnesium hydroxide in the system, the filling amount is often uneven, which seriously affects the tensile strength, elongation and apparent quality of the product.

[0005] CN112940388A discloses a B2-grade low-smoke halogen-free polyolefin cable material and a preparation method thereof. Aluminum hydroxide, magnesium hydroxide and the like are used as flame retardants, and are matched with ethylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer and ultra-low density polyethylene to make the disclosed B2-grade low-smoke halogen-free polyolefin cable material have the advantages of excellent mechanical properties and long service life. However, it only reaches the B2-grade flame retardant level, which cannot meet the A-class flame retardant requirement for dense laying in the wind turbine cabin.

[0006] Therefore, it is urgent to develop a flame-retardant cable with A-grade flame retardant level, high strength, torsion resistance, high aging resistance and long-term stable operation to ensure the safe operation of the whole wind power machine. SUMMARY

[0007] To solve the above technical problems, the application provides a protective sleeve for a flame-retardant cable, a preparation method thereof and a flame-retardant cable, wherein the formula of the protective sleeve for the flame-retardant cable is reasonably designed, so that the prepared protective sleeve has excellent flame retardance, torsion resistance and aging resistance. The application further matches the protective sleeve with an insulating layer containing modified magnesium hydroxide, thereby obtaining a flame-retardant cable suitable for wind power generation and passing the A-class bundled burning test.

[0008] To achieve the above purpose, the application adopts the following technical solutions:

[0009] In a first aspect, the application provides a protective sleeve for a flame-retardant cable, wherein the components of the protective sleeve for the flame-retardant cable include, by weight, 40-60 parts of chlorinated polyethylene, 1-10 parts of a polyolefin elastomer, 1-10 parts of modified magnesium hydroxide, 1-10 parts of an antimony-containing flame retardant and 1-8 parts of modified magnesium-aluminum hydrotalcite.

[0010] For example, 40-60 parts can be 40 parts, 42 parts, 45 parts, 47 parts, 50 parts, 52 parts, 55 parts, 57 parts or 60 parts; 1-10 parts can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts; and 1-8 parts can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts.

[0011] In the application, modified magnesium hydroxide, an antimony-containing flame retardant and modified magnesium-aluminum hydrotalcite are added to the protective sleeve for the flame-retardant cable to act as flame-retardant components. Modified magnesium hydroxide is a halogen-free flame retardant, which has good flame-retardant effect in the cable. When it is decomposed by heat, it can absorb a large amount of heat and release water vapor to achieve further flame-retardant effect. The antimony-containing flame retardant can combine with halogens in chlorinated polyethylene in the protective sleeve components to capture H· and OH· free radicals generated during combustion, terminate chain reactions and achieve flame-retardant effect. The formed antimony halide compound covers the surface of the protective sleeve to form a protective film to isolate air, which also has certain flame-retardant effect. Modified magnesium-aluminum hydrotalcite contains CO3 2- in the structure, which can release water vapor and CO2 at high temperature to absorb heat, reduce temperature and dilute oxygen. The three flame-retardant components have a compounding effect, which can synergistically improve the flame-retardant effect of the protective sleeve.

[0012] Compared with the conventional technical solution of matching a halogen-containing flame retardant with an antimony-containing flame retardant, the application uses chlorinated polyethylene as the protective sleeve base resin, and the smoke emission and acid gas generated during combustion of chlorinated polyethylene are significantly lower than those of the halogen-containing flame retardant. In addition, chlorinated polyethylene also has a certain plasticizing effect, which can improve the mechanical properties of the protective sleeve.

[0013] The following is a preferred technical solution of the present application, but is not a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the purpose and beneficial effects of the present application can be better achieved and implemented.

[0014] Preferably, the modified magnesium hydroxide is polydopamine modified magnesium hydroxide.

[0015] The present application preferably uses polydopamine modified magnesium hydroxide, which is modified by coating magnesium hydroxide with polydopamine. The polydopamine can be carbonized to form a dense nitrogen-doped carbon layer, which cooperates with magnesium hydroxide to block heat and oxygen, further enhancing the flame retardation of magnesium hydroxide.

[0016] Preferably, the antimony-containing flame retardant includes antimony trioxide.

[0017] Preferably, the purity of the antimony trioxide is greater than or equal to 99.8%, for example, it can be 99.8%, 99.9% or 100%, etc. High-purity antimony trioxide can improve the flame retardation efficiency and prolong the service life of the cable.

[0018] Preferably, the modified magnesium-aluminum hydrotalcite includes zinc-magnesium-aluminum hydrotalcite surface modified by a coupling agent.

[0019] Preferably, the coupling agent includes a silane coupling agent containing ethoxy and amino groups, preferably silane coupling agent KH550.

[0020] The present application preferably uses zinc-magnesium-aluminum hydrotalcite surface modified by a coupling agent. The introduction of zinc elements can further enhance its smoke suppression and lubricity, and improve the mechanical properties of the protective sleeve. The surface of the magnesium-aluminum hydrotalcite is modified by a coupling agent. The hydrolyzable ethoxy in the coupling agent forms a covalent bond with the hydroxyl groups on the surface of the hydrotalcite. At the same time, the amino functional group can interact with the polymer matrix in the protective sleeve, thereby simultaneously improving the interfacial compatibility and nanoscale dispersion uniformity of the hydrotalcite and chlorinated polyethylene, and synergistically promoting the construction of a dense heat-insulating carbon layer during combustion, which can effectively inhibit the transfer of heat and combustible volatile substances.

[0021] Preferably, the components of the flame-retardant cable protective sleeve further include any one or a combination of at least two of 1-10 parts of white carbon black, 10-30 parts of modified micro-fine kaolin, 0.5-3 parts of antioxidant, 1-10 parts of light magnesium oxide, 1-5 parts of microcrystalline wax, 1-5 parts of colorant, 2-20 parts of plasticizer, 1-5 parts of vulcanizing agent, or 0.5-2 parts of vulcanization aid, by weight.

[0022] Among them, 1-10 parts can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc.; 10-30 parts can be 10 parts, 12 parts, 15 parts, 17 parts, 20 parts, 22 parts, 25 parts, 37 parts or 30 parts, etc.; 0.5-3 parts may be 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, etc.; 1-5 parts may be 1 part, 2 parts, 3 parts, 4 parts or 5 parts, etc.; 2-20 parts may be 2 parts, 5 parts, 10 parts, 15 parts or 20 parts, etc.; 0.5-2 parts may be 0.5 parts, 1 part, 1.5 parts or 2 parts, etc.

[0023] Preferably, the anti-aging agent comprises 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

[0024] Preferably, the aging synergist comprises 2-mercaptobenzimidazole.

[0025] Preferably, the lubricant comprises paraffin oil.

[0026] Preferably, the vulcanizing agent comprises dicumyl peroxide.

[0027] Preferably, the vulcanizing aid comprises triallyl isocyanurate.

[0028] Preferably, the colorant comprises carbon black.

[0029] Preferably, the plasticizer comprises trioctyl trimellitate and / or diisooctyl sebacate.

[0030] In a second aspect, the present application provides a preparation method of the protective sleeve for the flame-retardant cable as described in the first aspect, and the preparation method of the protective sleeve for the flame-retardant cable comprises the following steps:

[0031] Mixing the components of the flame-retardant cable protective sleeve to obtain the flame-retardant cable protective sleeve.

[0032] Preferably, the temperature of the mixing is 85-95℃, which may be 85℃, 87℃, 90℃, 92℃ or 95℃, etc., and the mixing time is 5-20min, which may be 5min, 10min, 15min or 20min, etc.

[0033] Preferably, after mixing, it further comprises the operations of thinning and molding.

[0034] In a third aspect, the present application provides a flame-retardant cable, which comprises a conductor, a wrapping tape, an insulation layer and the protective sleeve for the flame-retardant cable as described in the first aspect.

[0035] Preferably, the components of the insulation layer comprise 40-60 parts of ethylene-propylene-diene rubber and 30-60 parts of modified magnesium hydroxide by weight.

[0036] Among them, 40-60 parts can be 40 parts, 42 parts, 45 parts, 47 parts, 50 parts, 52 parts, 55 parts, 57 parts or 60 parts, etc.; 30-60 parts can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts or 60 parts, etc.

[0037] Preferably, the components of the insulating layer further include, by weight parts, any one or a combination of at least two of 1-5 parts of white carbon black, 0.5-3 parts of zinc oxide, 1-5 parts of microcrystalline wax, 0.5-3 parts of titanium white powder, 0.5-3 parts of stearic acid, 1-5 parts of anti-aging agent, 1-5 parts of aging synergist, 1-10 parts of lubricant, 1-5 parts of coupling agent, 1-5 parts of vulcanizing agent or 0.5-2 parts of vulcanizing aid.

[0038] Among them, 1-10 parts can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc.; 0.5-3 parts can be 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts or 3 parts, etc.; 1-5 parts can be 1 parts, 2 parts, 3 parts, 4 parts or 5 parts, etc.; 1-5 parts can be 1 parts, 2 parts, 3 parts, 4 parts or 5 parts, etc.; 0.5-2 parts can be 0.5 parts, 1 parts, 1.5 parts or 2 parts, etc.

[0039] Preferably, the modified magnesium hydroxide in the components of the insulating layer is polydopamine modified magnesium hydroxide.

[0040] Preferably, the anti-aging agent in the components of the insulating layer includes 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

[0041] Preferably, the aging synergist in the components of the insulating layer includes 2-mercaptobenzimidazole.

[0042] Preferably, the lubricant in the components of the insulating layer includes paraffin oil.

[0043] Preferably, the vulcanizing agent in the components of the insulating layer includes dicumyl peroxide.

[0044] Preferably, the vulcanizing aid in the components of the insulating layer includes triallyl isocyanurate.

[0045] Preferably, the coupling agent in the components of the insulating layer includes vinyltri(2-methoxyethoxy)silane.

[0046] The present application further matches the protective sleeve and the insulating layer containing the modified magnesium hydroxide to prepare a flame-retardant cable suitable for wind power and passing the Class A bundled burning test.

[0047] Preferably, the insulating layer is prepared by the following preparation method:

[0048] Mixing each component of the flame-retardant cable insulation layer to obtain the flame-retardant cable insulation layer.

[0049] Preferably, the temperature of the mixing is 85-95 DEG C, for example, can be 85 DEG C, 87 DEG C, 90 DEG C, 92 DEG C or 95 DEG C, etc., and the mixing time is 5-20 min, for example, can be 5 min, 10 min, 15 min or 20 min, etc.

[0050] Preferably, after mixing, it further includes the operation of thin passing and forming.

[0051] Compared with the prior art, the present application has at least the following beneficial effects:

[0052] (1) The present application prepares a protective sleeve for flame-retardant cable with excellent flame retardancy, torsion resistance and aging resistance, and good processing stability and low cost by reasonably designing the formula of the protective sleeve.

[0053] (2) The present application further introduces polydopamine modified magnesium hydroxide into the insulation layer, and the prepared insulation layer also has excellent flame retardancy, torsion resistance and aging resistance, and the flame-retardant cable obtained by matching the protective sleeve can pass the A-class bundled combustion test, and the flame-retardant cable suitable for wind power generation can guarantee the safe operation of the wind power generator.

[0054] (3) The flame-retardant cable material provided by the present application does not contain halogen-containing flame retardant, releases less toxic gas during combustion, has low smoke, environmental protection and excellent flame-retardant effect.

[0055] (4)Specifically, the present application provides a protective sleeve for flame-retardant cables, which has a tensile strength of 12.9-13.5 MPa, an elongation at break of 398-486%, a tensile strength change rate after aging of-7.2%-10.2%, a tensile strength of 11.7-12.5 MPa after aging, an elongation at break change rate after aging of-9.8%-20.1%, an elongation at break of 359-389% after aging, a tensile strength change rate after mineral oil immersion of-5.1%-7.5%, a tensile strength of 11.9-12.8 MPa after mineral oil immersion, an elongation at break change rate after mineral oil immersion of-7.7%-10.6%, an elongation at break of 368-435% after mineral oil immersion, an elongation under thermal extension load of 10-20%, a permanent deformation after thermal extension and cooling of less than or equal to 10%, a tear strength of 9.1-11.9 MPa, an elongation at break during low-temperature tensile fracture of 100-120%, an oxygen index of 37-39, and no cracks during low-temperature impact. The flame-retardant cable provided by the present application can pass the Class A bundled burning test, has a tensile strength of 8.12-9.21 MPa, an elongation at break of 260-300%, a tensile strength change rate after aging of-2.5%-5.8%, a tensile strength of 7.7-8.7 MPa after aging, an elongation at break change rate after aging of 1.8%-4.5%, an elongation at break of 272-310% after aging, an elongation under thermal extension load of 5%, no permanent deformation after thermal extension and cooling, an oxygen index of 24-26, and no cracks after ozone resistance test. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is a schematic diagram of the structure of the flame-retardant cable provided by the present application;

[0057] 1-conductor, 2-sheath, 3-insulating layer, 4-protective sleeve;

[0058] Figure 2 is a schematic diagram of the cable burning situation of the flame-retardant cable provided by the present application after the Class A bundled burning test. DETAILED DESCRIPTION

[0059] The technical solutions of the present application are further described below in combination with the drawings and through specific embodiments. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0060] In the following specific embodiments of the present application, the specific information of the materials used is as follows:

[0061] Chlorinated polyethylene, CM135B, purchased from Hangzhou Kelai Chemical Co., Ltd.;

[0062] Polyolefin elastomer, POE5371, purchased from ExxonMobil Chemical

[0063] Polydopamine modified magnesium hydroxide, purchased from Yantai Aiver Flame Retardant Technology Co., Ltd.;

[0064] Antimony trioxide, purchased from Yantai Aiver Flame Retardant Technology Co., Ltd.;

[0065] Zinc-magnesium-aluminum hydrotalcite surface modified by coupling agent, purchased from Hefei Anhehe New Material Technology Co., Ltd.;

[0066] Ethylene propylene diene rubber, KEP210, purchased from South Korea Kimhak Chemical Industry;

[0067] Examples 1-3

[0068] Examples 1-3 respectively provide a protective sleeve for a flame-retardant cable and a preparation method thereof, components of the protective sleeve for a flame-retardant cable are shown in Table 1 (the amount of each component of the protective sleeve in Table 1 is by weight fraction, and the preparation method is:

[0069] After mixing the components of the flame-retardant cable protective sleeve at 90℃ for 15min, thinning, molding, the flame-retardant cable protective sleeve is obtained.

[0070] Table 1

[0071]

[0072]

[0073] Comparative Example 1

[0074] This comparative example provides a protective sleeve for a flame-retardant cable and a preparation method thereof, which is different from Example 1 in that: the components of the protective sleeve do not contain polydopamine modified magnesium hydroxide, antimony trioxide and zinc-magnesium-aluminum hydrotalcite surface modified by coupling agent.

[0075] Comparative Example 2

[0076] This comparative example provides a protective sleeve for a flame-retardant cable and a preparation method thereof, which is different from Example 1 in that: the components of the protective sleeve do not contain zinc-magnesium-aluminum hydrotalcite surface modified by coupling agent and antimony trioxide, and the amount of polydopamine modified magnesium hydroxide is 16 parts.

[0077] Comparative Example 3

[0078] This comparative example provides a protective sleeve for a flame-retardant cable and a preparation method thereof, which is different from Example 1 in that: the components of the protective sleeve do not contain polydopamine modified magnesium hydroxide and zinc-magnesium-aluminum hydrotalcite surface modified by coupling agent, and the amount of antimony trioxide is 16 parts.

[0079] Comparative Example 4

[0080] This comparative example provides a protective sleeve for flame-retardant cables and its preparation method. The difference from Example 1 is that the protective sleeve does not contain polydopamine-modified magnesium hydroxide and antimony trioxide, and the amount of zinc-magnesium aluminum hydrotalcite modified with coupling agent is 16 parts.

[0081] Comparative Example 5

[0082] This comparative example provides a protective sleeve for flame-retardant cables and its preparation method. The difference from Example 1 is that the protective sleeve does not contain polydopamine-modified magnesium hydroxide, the amount of antimony trioxide is 8.7 parts, and the amount of zinc-magnesium aluminum hydrotalcite modified with coupling agent is 7.3 parts.

[0083] Comparative Example 6

[0084] This comparative example provides a protective sleeve for flame-retardant cables and its preparation method. The difference from Example 1 is that the protective sleeve does not contain antimony trioxide, the amount of polydopamine-modified magnesium hydroxide is 8 parts, and the amount of zinc-magnesium-aluminum hydrotalcite modified with coupling agent is 8 parts.

[0085] Comparative Example 7

[0086] This comparative example provides a protective sleeve for flame-retardant cables and its preparation method. The difference from Example 1 is that the components of the protective sleeve do not contain zinc-magnesium-aluminum hydrotalcite modified with coupling agent, and the amount of antimony trioxide is 8.7 parts and the amount of polydopamine-modified magnesium hydroxide is 7.3 parts.

[0087] Application Example 1

[0088] Application Example 1 provides a flame-retardant cable, such as Figure 1 As shown, the flame-retardant cable includes a conductor 1, a wrapping tape 2, an insulation layer 3, and a protective sleeve 4 for the flame-retardant cable provided in Example 1.

[0089] The insulating layer comprises, by weight, 50 parts of EPDM rubber, 40 parts of polydopamine-modified magnesium hydroxide, 2 parts of silica, 2 parts of zinc oxide, 5 parts of microcrystalline wax, 2 parts of titanium dioxide, 1.2 parts of stearic acid, 1 part of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 1 part of 2-thiol-benzimidazole, 2 parts of paraffin oil, 1.2 parts of vinyltris(2-methoxyethoxy)silane, 3 parts of dicumyl peroxide, and 1.5 parts of triallyl isocyanurate.

[0090] The insulation layer is prepared by the following method: the components of the flame-retardant cable insulation layer are mixed at 90°C for 15 minutes, and then thinned and shaped to obtain the flame-retardant cable insulation layer.

[0091] Application Example 2

[0092] Application Example 2 provides a flame-retardant cable, which comprises a conductor, a wrapping tape, an insulation layer and the protective jacket for the flame-retardant cable provided in Application Example 2.

[0093] The components of the insulation layer comprise, by weight fraction, 40 parts of EPDM, 30 parts of polydopamine modified magnesium hydroxide, 1 part of white carbon black, 1 part of zinc oxide, 3 parts of microcrystalline wax, 3 parts of titanium white, 5 parts of stearic acid, 3 parts of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 3 parts of 2-mercapto benzimidazole, 5 parts of paraffin oil, 3 parts of vinyl tri(2-methoxyethoxy) silane, 1 part of dicumyl peroxide and 0.5 part of triallyl isocyanurate.

[0094] The preparation method of the insulation layer is the same as that in Application Example 1.

[0095] Application Example 3

[0096] Application Example 3 provides a flame-retardant cable, which comprises a conductor, a wrapping tape, an insulation layer and the protective jacket for the flame-retardant cable provided in Application Example 3.

[0097] The components of the insulation layer comprise, by weight fraction, 60 parts of EPDM, 60 parts of polydopamine modified magnesium hydroxide, 5 parts of white carbon black, 3 parts of zinc oxide, 2 parts of microcrystalline wax, 1 part of titanium white, 3 parts of stearic acid, 5 parts of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 5 parts of 2-mercapto benzimidazole, 3 parts of paraffin oil, 5 parts of vinyl tri(2-methoxyethoxy) silane, 4 parts of dicumyl peroxide and 2 parts of triallyl isocyanurate.

[0098] The preparation method of the insulation layer is the same as that in Application Example 1.

[0099] Comparative Application Examples 1-7

[0100] Comparative Application Examples 1-7 respectively provide a flame-retardant cable, which is different from Application Example 1 in that the protective jacket in the flame-retardant cable of Application Example 1 is replaced by the protective jacket provided in Comparative Application Examples 1-7.

[0101] Comparative Application Example 8

[0102] The present comparative application example provides a flame-retardant cable, which is different from Application Example 1 in that the polydopamine modified magnesium hydroxide is not contained in the components of the insulation layer.

[0103] Comparative Application Example 9

[0104] The present comparative application example provides a flame-retardant cable, which is different from Application Example 1 in that the addition amount of the polydopamine modified magnesium hydroxide in the components of the insulation layer is 20 parts.

[0105] Comparative Application Example 10

[0106] The comparative application example provides a flame-retardant cable, which is different from the application example 1 in that the amount of the polydopamine modified magnesium hydroxide added in the component of the insulation layer is 60 parts.

[0107] Test method

[0108] (1) The protective sheath of the flame-retardant cable provided by the examples 1-3 and the comparative examples 1-7 is tested for the following performances:

[0109] The mechanical performance before aging is tested according to GB / T 2951-11, and the test results are that the tensile strength is greater than or equal to 10 MPa, and the elongation at break is greater than or equal to 250%, which meet the actual use conditions.

[0110] The mechanical performance after air oven aging is tested according to GB / T 295-12, the test temperature is 120±2℃, the test time is 168h, and the test results are that the tensile strength change rate is less than or equal to-30%, and the elongation at break change rate is less than or equal to-40%, which meet the actual use conditions.

[0111] The hot elongation performance is tested according to GB / T 2951-21, the test temperature is 200±3℃, the test time is 15min, and the test results are that the elongation under load is less than or equal to 175%, and the permanent deformation after cooling is less than or equal to 15%, which meet the actual use conditions.

[0112] The oxygen index is tested according to GB / T 10707, the test is carried out at 25℃, the minimum oxygen concentration value of the sheath sample maintaining continuous combustion in a specific oxygen concentration environment is determined by adjusting the mixing ratio of oxygen and nitrogen. The test results are that the oxygen index is greater than or equal to 30%, which meet the actual use conditions.

[0113] The mechanical performance after mineral oil immersion is tested according to GB / T 2951-21, the aging temperature is 100±2℃, the aging time is 24h, and the test results are that the tensile strength change rate is less than or equal to-40%, and the elongation at break change rate is less than or equal to-40%, which meet the actual use conditions.

[0114] The tear resistance is tested according to JB / T 10696.7, and the test results are that the tear strength is greater than or equal to 5.0MPa, which meet the actual use conditions.

[0115] The low temperature tensile is tested according to GB / T 2951-14, the test temperature is-25±2℃, and the test results are that the elongation when not broken is greater than or equal to 30%, which meet the actual use conditions.

[0116] The low temperature impact is tested according to GB / T 2951-14, the test temperature is-25±2℃, and whether there is a crack is evaluated as the test standard.

[0117] (2) The insulating layer of the flame-retardant cable provided by Application Examples 1-3 and Comparative Examples 8-10 was subjected to the following performance tests: mechanical properties before aging, tested in accordance with GB / T 2951-11, the test results were that the tensile strength was ≥4.2 MPa and the elongation at break was ≥200%, meeting the actual use conditions;

[0118] mechanical properties after air oven aging, tested in accordance with GB / T 295-12, the test temperature was 135±2℃, the test time was 168h, the test results were that the tensile strength change rate was ≤±30% and the elongation at break change rate was ≤±30%, meeting the actual use conditions;

[0119] thermal elongation performance, tested in accordance with GB / T 2951-21, the test temperature was 250±3℃, the test time was 15min, the test results were that the elongation under load was ≤175% and the permanent deformation after cooling was ≤15%, meeting the actual use conditions;

[0120] oxygen index, tested in accordance with ASTM D2863;

[0121] ozone resistance, tested in accordance with GB / T 2951-21, the test temperature was 25±2℃, the test time was 24h, the ozone concentration was 0.025-0.030%, and whether there was a crack was evaluated.

[0122] oxygen index, tested in accordance with GB / T 10707; the test was carried out at 25℃, by adjusting the mixing ratio of oxygen and nitrogen, the minimum oxygen concentration value at which the insulating sample could sustain continuous combustion in a specific oxygen concentration environment was determined;

[0123] (3) The flame-retardant cables provided by Application Examples 1-6 and Comparative Application Examples 1-10 were subjected to the following performance tests:

[0124] combustion performance: tested in accordance with GB / T 18380.33-2022 Cable and optical cable-Combustion test in the presence of a flame-Part 33: Vertical installation of bunched electrical wires and cables-Flame propagation test in the vertical direction for class A, and the carbonization height was evaluated to be ≤2.5 meters.

[0125] Figure 2 The cable diagram of the flame-retardant cable provided by Application Example 1 after the class A bunched combustion experiment, from the diagram, the carbonization height was 1.15 meters, meeting the class A bunched combustion requirement.

[0126] Test results

[0127] The performance results of the protective sheath of the flame-retardant cable provided by Examples 1-3 and Comparative Examples 1-7 are shown in Table 2 below:

[0128] Table 2

[0129]

[0130] The performance test results of the insulating layer of the flame-retardant cable provided by application examples 1-3 and comparative application examples 8-10 are shown in Table 3 below:

[0131] Table 3

[0132]

[0133] The performance test results of the flame-retardant cable provided by application examples 1-3 and comparative application examples 1-10 are shown in Table 4, and " / " indicates that it does not pass the Class A bundled burning test:

[0134] Table 4

[0135]

[0136] From the test results, it can be seen that:

[0137] (1) From Examples 1 to 3, it can be seen that by reasonably designing the formula of the protective sleeve, the prepared protective sleeve has excellent flame retardance, twist resistance and aging resistance. The tensile strength of the protective sleeve for flame-retardant cable provided by the present application can reach 12.9-13.5 MPa, the elongation at break can reach 398-486%, the tensile strength change rate after aging is -7.2% to -10.2%, the tensile strength after aging is 11.7-12.5 MPa, the elongation at break change rate after aging is -9.8% to -20.1%, the elongation at break after aging is 359-389%, the tensile strength change rate after mineral oil immersion is -5.1% to -7.5%, the tensile strength after mineral oil immersion is 11.9-12.8 MPa, the elongation at break change rate after mineral oil immersion is -7.7% to 10.6%, the elongation at break after mineral oil immersion is 368-435%, the elongation under thermal extension load is 10-20%, the permanent deformation after thermal extension cooling is less than or equal to 10%, the tear strength can reach 9.1-11.9 MPa, the elongation at break during low-temperature tensile fracture can reach 100-120%, the oxygen index is 37-39, and there is no crack during low-temperature impact.

[0138] (2) From Examples 1 and Comparative Examples 1-7, it can be seen that by adding modified magnesium hydroxide, antimony-containing flame retardant and modified magnesium-aluminum hydrotalcite as a flame-retardant component to the protective sleeve for flame-retardant cable, better flame retardance and aging resistance can be achieved.

[0139] (3) Through application examples 1 to 3, it can be seen that the flame-retardant cable provided by the application can pass the Class A bundled burning test, the tensile strength of the cable can reach 8.12-9.21 MPa, the elongation at break can reach 260-300%, the tensile strength change rate after aging is-2.5% to-5.8%, the tensile strength after aging is 7.7-8.7 MPa, the elongation at break change rate after aging is 1.8% to 4.5%, the elongation at break after aging is 272-310%, the elongation under thermal extension load is 5%, there is no permanent deformation after thermal extension cooling, the oxygen index is 24-26, and there is no crack after ozone resistance test.

[0140] (4) Through application examples 1-3 and comparative application examples 1-10, it can be seen that the protective sleeve and the insulation layer containing modified magnesium hydroxide prepared by the application can be used to prepare a flame-retardant cable suitable for wind power and passing the Class A bundled burning test. By introducing modified magnesium hydroxide into the insulation layer, the flame-retardant technical effect of the insulation layer can be further improved. When no modified magnesium hydroxide is used or too much or too little modified magnesium hydroxide is added, the overall flame-retardant performance and mechanical properties of the cable are deteriorated.

[0141] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the application can be easily thought of by any person skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A protective sleeve for flame-retardant cables, characterized in that, The components of the flame-retardant cable protective sheath, by weight, include 40-60 parts of chlorinated polyethylene, 1-10 parts of polyolefin elastomer, 1-10 parts of modified magnesium hydroxide, 1-10 parts of antimony-containing flame retardant, and 1-8 parts of modified magnesium aluminum hydrotalcite.

2. The protective sheath for flame-retardant cables according to claim 1, characterized in that, The modified magnesium hydroxide includes polydopamine-modified magnesium hydroxide; Preferably, the antimony-containing flame retardant includes antimony trioxide; Preferably, the modified magnesium-aluminum hydrotalcite comprises zinc-magnesium-aluminum hydrotalcite surface modified with a coupling agent; Preferably, the coupling agent comprises a silane coupling agent containing ethoxy and amino groups.

3. The protective sheath for flame-retardant cables according to claim 1 or 2, characterized in that, The components of the protective sheath for the flame-retardant cable, by weight, also include any one or a combination of at least two of the following: 1-10 parts of silica, 10-30 parts of modified fine kaolin, 0.5-3 parts of antioxidant, 1-10 parts of light magnesium oxide, 1-5 parts of microcrystalline wax, 1-5 parts of colorant, 2-20 parts of plasticizer, 1-5 parts of vulcanizing agent, or 0.5-2 parts of vulcanizing aid.

4. The protective sheath for flame-retardant cables according to claim 3, characterized in that, The antioxidant comprises a 2,2,4-trimethyl-1,2-dihydroquinoline polymer; Preferably, the aging enhancer comprises 2-thiol-benzimidazole; Preferably, the lubricant comprises paraffin oil; Preferably, the vulcanizing agent comprises dicumyl peroxide; Preferably, the vulcanizing aid comprises triallyl isocyanurate; Preferably, the colorant comprises carbon black; Preferably, the plasticizer comprises trioctyl trimellitate and / or diisooctyl sebacate.

5. A method for preparing a protective sheath for a flame-retardant cable as described in any one of claims 1-4, characterized in that, The method for preparing the protective sheath for the flame-retardant cable includes the following steps: The components of the flame-retardant cable protective sheath are mixed to obtain the flame-retardant cable protective sheath.

6. The method for preparing a protective sheath for a flame-retardant cable according to claim 5, characterized in that, The mixing temperature is 85-95℃, and the mixing time is 5-20 minutes; Preferably, the mixture also includes thin-passing and forming operations.

7. A flame-retardant cable, characterized in that, The flame-retardant cable includes a conductor, a sheath, an insulation layer, and a flame-retardant cable protective sheath as described in any one of claims 1-4.

8. The flame-retardant cable according to claim 7, characterized in that, The insulating layer comprises, by weight, 40-60 parts of EPDM rubber and 30-60 parts of modified magnesium hydroxide.

9. The flame-retardant cable according to claim 7 or 8, characterized in that, The insulating layer also includes, by weight, any one or a combination of at least two of the following components: 1-5 parts of silica, 0.5-3 parts of zinc oxide, 1-5 parts of microcrystalline wax, 0.5-3 parts of titanium dioxide, 0.5-3 parts of stearic acid, 1-5 parts of antioxidant, 1-5 parts of aging enhancer, 1-10 parts of lubricant, 1-5 parts of coupling agent, 1-5 parts of vulcanizing agent, or 0.5-2 parts of vulcanizing aid. Preferably, the modified magnesium hydroxide in the insulating layer is polydopamine-modified magnesium hydroxide; Preferably, the antioxidant in the components of the insulating layer includes a 2,2,4-trimethyl-1,2-dihydroquinoline polymer; Preferably, the aging enhancer in the components of the insulating layer includes 2-thiol-benzimidazole; Preferably, the lubricant in the composition of the insulating layer includes paraffin oil; Preferably, the vulcanizing agent in the components of the insulating layer includes dicumyl peroxide; Preferably, the vulcanizing aid in the components of the insulating layer includes triallyl isocyanurate; Preferably, the coupling agent in the components of the insulating layer includes vinyltris(2-methoxyethoxy)silane.

10. The flame-retardant cable according to any one of claims 7-9, characterized in that, The insulating layer is prepared by the following method: The components of the flame-retardant cable insulation layer are mixed to obtain the flame-retardant cable insulation layer; Preferably, the mixing temperature is 85-95℃ and the mixing time is 5-20 minutes; preferably, the mixing process also includes thin-passing and forming operations.

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