Polyolefin cable material for energy storage cables and method for the production thereof

Abstract

The application discloses polyolefin cable material for energy storage cable and a preparation method thereof, and relates to the technical field of cable material.The polyolefin cable material comprises the following raw materials in parts by mass: 30-55 parts of base resin, 40-70 parts of flame retardant, 2-10 parts of compatible toughening agent, 1-8 parts of smoke suppressant, and 1.0-5.0 parts of processing aid; the flame retardant comprises coated aluminum hypophosphite and ceramic powder; the ceramic powder is mullite powder treated by amino silicon oil, and the coated aluminum hypophosphite is aluminum hypophosphite coated by ammonium polyphosphate and melamine-formaldehyde resin. The preparation method comprises the following steps: S1, preparing raw materials according to the required proportion, premixing the base resin, and then hot-mixing the other raw materials to obtain premix; and S2, melt blending, extruding, cooling and cutting the premix to obtain the polyolefin cable material for energy storage cable. The polyolefin cable material for energy storage cable has the advantages of high toughness and no melting drop characteristic on the basis of high flame retardance and low smoke emission.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cable materials, and specifically relates to a polyolefin cable material for energy storage cables and a preparation method thereof. BACKGROUND

[0002] The battery clusters in the energy storage cabin are concentrated, the energy density is extremely high, and the cable wiring is dense. Once a fire is caused by overheating, short circuit or electric arc, the thick smoke and toxic gas released by the traditional cable combustion will seriously hinder personnel evacuation and fire rescue, and may cause a disastrous chain reaction. Therefore, the cable used in the cabin must have extremely high flame retardant grade, extremely low smoke density, never produce molten droplets, and excellent thermal stability.

[0003] Low-smoke halogen-free flame-retardant polyolefin material is the first choice to meet the above requirements. The current technology mainly relies on filling a high proportion of metal hydroxides such as aluminum hydroxide (ATH) or magnesium hydroxide in the polyolefin matrix (such as EVA, PE). These fillers play a flame-retardant role by decomposing heat and releasing water vapor. However, this system has inherent defects: first, to achieve UL94 V-0 level, the extremely high filling amount seriously deteriorates the mechanical properties of the material, resulting in poor flexibility, low elongation and easy brittle fracture; second, high filling amount makes the melt viscosity increase sharply, making it difficult to process and extrude, and the cable surface is rough; finally, the flame-retardant efficiency of hydroxide is limited, and the loose and porous carbon layer formed during combustion has poor smoke and heat suppression effect, which is difficult to meet the demand for extreme safety in the energy storage scenario.

[0004] To improve the above problems, the industry has tried various methods, such as compounding different particle sizes of hydroxides, using silane coupling agents for surface treatment, or introducing intumescent flame retardants (such as ammonium polyphosphate APP). But these improvement schemes often have pros and cons: ammonium polyphosphate has poor compatibility with polyolefin, is easy to absorb moisture, and is easy to decompose at processing temperature, resulting in a decrease in thermal stability and surface deterioration of the material; simple surface treatment has limited effect on improving the processing fluidity under extremely high filling; and systematic synergistic research on smoke suppression and anti-melt dripping is still insufficient. Patent document CN109627568A discloses a polyolefin cable sheath material and a preparation method thereof, which uses coated aluminum hypophosphite to prepare microencapsulated aluminum hypophosphite as a flame retardant. The flame retardant formed by a single coating agent only solves the oxidation and corrosiveness of aluminum hypophosphite, and three different microcapsules need to be compounded at the same time to achieve a certain flame-retardant effect. SUMMARY

[0005] The present application is to overcome the above technical problems, and therefore provides a polyolefin cable material for energy storage cables and a preparation method thereof. The polyolefin cable material for energy storage cables of the present application has the advantages of high flame retardance, low smoke emission, high toughness and no melt dripping.

[0006] The present application solves the above technical problems by the following technical solutions.

[0007] The polyolefin cable material for energy storage cable comprises the following raw materials by mass: 30-55 parts of base resin, 40-70 parts of flame retardant, 2-10 parts of compatible toughening agent, 1-8 parts of smoke suppressant, and 1.0-5.0 parts of processing aid;

[0008] Preferably, the polyolefin cable material for energy storage cable comprises the following raw materials by mass: 35-50 parts of base resin, 50-65 parts of flame retardant, 3-8 parts of compatible toughening agent, 2-6 parts of smoke suppressant, and 1.5-4.0 parts of processing aid;

[0009] The base resin comprises 15-50% polyolefin elastomer and the balance polyethylene resin by mass; preferably, the base resin comprises 20-40% polyolefin elastomer and the balance polyethylene resin by mass;

[0010] The flame retardant comprises coated aluminum hypophosphite and ceramic powder; the coated aluminum hypophosphite is aluminum hypophosphite coated with ammonium polyphosphate and melamine-formaldehyde resin; wherein, the ammonium polyphosphate decomposes to generate phosphoric acid compounds at the initial stage of combustion, catalyzes the dehydration crosslinking of the polymer matrix, forms an expanded carbon layer, and captures free radicals in the gas phase; the hydrophobicity of the melamine-formaldehyde resin can reduce moisture absorption;

[0011] The ceramic powder is mullite powder treated with amino silicone oil; wherein, the mullite powder itself is more hydrophilic, and the mullite powder treated with amino silicone oil has better compatibility with the base resin; in addition, the pore structure on the surface of the mullite provides adsorption and catalytic sites, converting the traditional gas-solid phase flame retardation into a condensed phase carbonization flame retardation mode.

[0012] According to some embodiments of the present application, the flame retardant comprises 5-25wt% coated aluminum hypophosphite, 3-20wt% ceramic powder, 0.5-2.5% silicone powder, and the balance magnesium hydroxide by mass;

[0013] Preferably, the flame retardant comprises 10-20wt% coated aluminum hypophosphite, 5-15wt% ceramic powder, 0.8-1.5% silicone powder, and the balance magnesium hydroxide by mass;

[0014] According to some embodiments of the present application, the polyethylene resin is at least one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and ethylene-vinyl acetate copolymer (EVA);

[0015] Preferably, the polyethylene resin is low-density polyethylene (LDPE) or ethylene-vinyl acetate copolymer (EVA with VA content of 18-28%).

[0016] According to some embodiments of the present application, the polyolefin elastomer is at least one of ethylene-octene copolymer (POE), ethylene-butene copolymer (PBE), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), and terpolymer ethylene-propylene rubber (EPDM); preferably, the polyolefin elastomer is ethylene-octene copolymer (POE).

[0017] According to some embodiments of the present application, the D50 of the mullite powder is 30-60 μm, preferably 40-50 μm.

[0018] According to some embodiments of the present application, the refractoriness of the mullite powder is ≥1780 ℃, preferably 1790-1800 ℃.

[0019] According to some embodiments of the present application, the mullite powder comprises, by mass fraction, 51-54% SiO2, 44-46% Al2O3, ≤0.8% Fe2O3, ≤1.4% TiO2, and ≤0.3% CaO+MgO.

[0020] According to some embodiments of the present application, the D50 of the magnesium hydroxide is 3-10 μm.

[0021] According to some embodiments of the present application, the D50 of the aluminum hypophosphite is 10-40 μm.

[0022] According to some embodiments of the present application, the compatible toughening agent is maleic anhydride grafted polymer, preferably maleic anhydride grafted polyolefin elastomer (POE-g-MAH), maleic anhydride grafted polyethylene (PE-g-MAH), or maleic anhydride grafted ethylene-vinyl acetate (EVA-g-MAH).

[0023] According to some embodiments of the present application, the smoke suppressant is 15-45% ferrocene and the balance zinc borate; preferably, the smoke suppressant is 20-40% ferrocene and the balance zinc borate. The ferrocene can capture gas-phase free radicals, and the zinc borate can be condensed into porcelain and suppress dripping in the condensed phase.

[0024] According to some embodiments of the present application, the processing aid is at least one of lubricant, antioxidant, and dispersant.

[0025] Further, the lubricant is one or more of zinc stearate, calcium stearate, polyethylene wax, and oxidized polyethylene wax, preferably zinc stearate.

[0026] Further, the antioxidant is at least one of antioxidant 1076, antioxidant 1010, and dilauryl thiodipropionate (DLTP), preferably antioxidant 1076.

[0027] Further, the dispersant is one of ethylene bis-stearamide (EBS), N,N'-ethyl bis-stearamide or silicone powder.

[0028] According to some embodiments of the present application, the limiting oxygen index (LOI) of the polyolefin cable material for energy storage cable is 39-42%;

[0029] According to some embodiments of the present application, the smoke density (Ds) of the polyolefin cable material for energy storage cable is 80-100;

[0030] According to some embodiments of the present application, the tensile strength of the polyolefin cable material for energy storage cable is ≥12 MPa;

[0031] According to some embodiments of the present application, the elongation at break of the polyolefin cable material for energy storage cable is ≥180%.

[0032] The present application also discloses a preparation method of the low-smoke halogen-free flame-retardant polyolefin cable material for energy storage cable, comprising the following steps:

[0033] S1. Prepare raw materials according to the required ratio, pre-mix the base resin, and then hot-mix other raw materials to obtain a pre-mixed material;

[0034] S2. Obtain the polyolefin cable material for energy storage cable by melt blending, extruding, cooling and granulating the pre-mixed material.

[0035] S1 further comprises the step of preparing key components, i.e. the preparation of aluminum hypophosphite-coated, the preparation of ceramic powder and the preparation of flame retardant.

[0036] In S1, the preparation of aluminum hypophosphite-coated: 100 parts of aluminum hypophosphite is added to water to prepare a suspension with a solid content of 20-40%, and the pH is adjusted to 7.5-8.5; after the suspension is warmed to 65-75℃, 5-15 parts of ammonium polyphosphate is added and stirred for 60-120 min, then 3-10 parts of melamine and 2.4-12 parts of formaldehyde solution (37%) are slowly added, the pH is adjusted to 4.5-5.5, and the stirring is continued for 120-180 min after the reaction is completed, and the aluminum hypophosphite-coated is obtained.

[0037] In S1, the preparation of ceramic powder: mullite powder is placed in a high-speed mixer and preheated to 70-90℃, 1.0-3.0% of amino silicone oil based on the mass of mullite is slowly added by atomizing spraying at a speed of 500-800 rpm, and after the spraying is completed, the stirring is continued for 20-40 min, and the material is discharged and cooled.

[0038] In S1, the preparation of the flame retardant: after mixing the coated aluminum hypophosphite, ceramic powder and magnesium hydroxide, slowly add silicone powder at 50-70℃, mix at 500-800rpm for 10-20min to obtain the flame retardant;

[0039] In S1, the premix is stirred at 45-65℃ for 5-15min;

[0040] In S1, the hot mixing is mixed at 65-85℃ at a speed of 600-900rpm for 10-20min;

[0041] In S2, the melt blending adopts a twin-screw extruder; the temperature of each section of the twin-screw extruder is set as: feeding section 140-160℃, melting section 150-170℃, first mixing section 165-180℃, second mixing section 170-185℃, exhaust section 165-175℃, head 165-175℃; the speed of the twin-screw is 250-400rpm, and the vacuum degree is controlled at-0.06--0.08MPa.

[0042] In S2, the cooling adopts a water cooling method at 25-45℃.

[0043] On the basis of conforming to the common sense of the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] 1. The base resin selected in the present application is polyethylene resin and polyolefin elastomer respectively, which can improve the performance deterioration problem caused by high filling to some extent. The polyolefin elastomer can provide flexibility and impact resistance.

[0046] 2. The coated aluminum hypophosphite can effectively isolate the direct contact between aluminum hypophosphite and the base resin, completely avoiding the catalytic degradation of acidic substances to polymer molecular chains during high-temperature melt processing, ensuring the melt viscosity and stability. Compared with traditional physical coating and single-function coating agent, the dual-function coating agent of ammonium polyphosphate and melamine-formaldehyde resin is used in the present application, which sequentially coats the aluminum hypophosphite by aqueous solution chemical coating method. After the aluminum hypophosphite is coated, in the initial stage of combustion, the polyphosphoric acid catalyzes the dehydration of the matrix to form carbon, forming an expanded carbon layer, and the nitrogen gas generated by the decomposition of melamine-formaldehyde resin further promotes the expansion of the carbon layer. It solves the high flame-retardant and high stability demand of traditional aluminum hypophosphite which cannot meet the energy storage scene.

[0047] 3.The composite flame-retardant system of the present application is composed of magnesium hydroxide, ceramic powder (mainly mullite) and coated aluminum hypophosphite, and each component realizes efficient, low smoke and non-dripping flame-retardant performance through synergistic effect. As an environmentally friendly inorganic flame retardant, magnesium hydroxide cools the material surface by endothermic decomposition (about 340℃), releases water vapor to dilute the concentration of combustible gas and oxygen, and forms a stable oxide covering layer on the material surface. The mullite ceramic powder has a porous structure that can adsorb smoke particles and volatile hydrocarbon products released during combustion, and at the same time, build a dense barrier layer on the surface to inhibit heat and mass transfer. The coated aluminum hypophosphite decomposes into phosphorus-nitrogen flame-retardant active substances at high temperature, promotes the formation of a carbon layer and enhances its density; and synergizes with the smoke suppressant ferrocene in the system. Ferrocene, as a free radical scavenger, effectively inhibits the combustion chain reaction and reduces the release of smoke and toxic gases.

[0048] 4.The cable material of the present application has high flame retardance and low smoke emission, and also has high toughness and non-dripping characteristics. It is expected to be used in energy storage cables to ensure the safety of energy storage facilities. DETAILED DESCRIPTION

[0049] In order to facilitate the understanding of the present application, the following will combine the preferred embodiments to describe the present application more comprehensively and in detail, but the protection scope of the present application is not limited to the following specific embodiments.

[0050] Unless otherwise defined, all professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0051] The ranges disclosed herein are intended to be "open" ranges, unless expressly specified otherwise. For example, a range of "1 to 10" is intended to include all whole numbers and fractions within this range, e.g., 1, 1.1, 1.2.,..., 10. Similarly, a range of "5-10" is intended to include, 5, 5.1, 5.2,..., 10. Also, the ranges disclosed herein are intended to be "inclusive" of the minimum and maximum values, unless specifically indicated otherwise. For example, a range of "between 1 and 10" is intended to include the values of 1 and 10. Also, when referring to a parameter as being an integer, it is understood that the parameter can be, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0053] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0054] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0055] Unless otherwise specified, "including" and "comprising" mentioned in the present application means open-ended, and can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0056] If not otherwise specifically defined, the term "or" within this disclosure is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions fulfill the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0057] The raw material information used in the following examples is as follows:

[0058] Ethylene-vinyl acetate copolymer (EVA) with a vinyl acetate content of 18%, a tensile breaking strength of 19 MPa;

[0059] Ethylene-octene copolymer (POE) from Dow with a melt flow rate (190°C, 2.16 kg) of 5.0 g / 10 min, an elongation at break of 550%, and a tensile strength of 2.4 MPa;

[0060] The D50 of aluminum hypophosphite is 15 μm;

[0061] The mullite powder is purchased from Yichu City Xinyan Calcined Kaolin 325 mesh, with a refractoriness of ≥1790°C, and a mullite phase content of 55-60%;

[0062] The amino silicone oil is Kangdouning 8040A;

[0063] The maleic anhydride grafted polyolefin elastomer (POE-g-MAH) is purchased from Jia Yirong Polymer (Shanghai) Co., Ltd. FB521A;

[0064] Including but not limited to the above manufacturer model.

[0065] Example 1

[0066] 1. The raw materials for preparing the polyolefin cable material for energy storage cables in this example are as follows:

[0067] 42.0 parts of base resin, 58 parts of flame retardant, 5.5 parts of compatible toughening agent, 4.0 parts of smoke suppressant, and 2.8 parts of processing aid;

[0068] The base resin in this example is 29.4 parts of EVA and 12.6 parts of POE;

[0069] The flame retardant in this example is 15 wt% coated aluminum hypophosphite, 10 wt% ceramic powder, 1.2 wt% silicone powder, and the balance magnesium hydroxide;

[0070] The compatible toughening agent in this example is POE-g-MAH;

[0071] The coated aluminum hypophosphite is aluminum hypophosphite coated with ammonium polyphosphate and melamine-formaldehyde resin;

[0072] The ceramic powder is a mullite powder treated with amino silicone oil;

[0073] The processing aid in this embodiment is 1.7 parts of zinc stearate, 0.5 parts of antioxidant 1076 and 0.6 parts of EBS;

[0074] The smoke suppressant in this embodiment is 30 wt% ferrocene and the balance zinc borate.

[0075] 2. The preparation method of the polyolefin cable material for energy storage cables in this embodiment is as follows:

[0076] S1.1. Preparation of key components

[0077] Preparation of ceramic powder: Place the mullite powder in a high-speed mixer, preheat to 80°C, slowly add 2.0% of the mass of the mullite of amino silicone oil in a spray misting manner at a speed of 600 rpm, continue to stir at 80°C for 30 min after spraying is completed, and then cool the discharge;

[0078] Preparation of aluminum hypophosphite coating: Add 100 parts of aluminum hypophosphite (D50=10 μm) to water to prepare a suspension with a solid content of 30%, and adjust the pH to 8.0 with ammonia water; After the suspension is heated to 70°C, 10 parts of ammonium polyphosphate is added and stirred for 90 min, then 6 parts of melamine and 7.5 parts of 37% formaldehyde solution are slowly added, and the pH is adjusted to 5.0 with 10% acetic acid solution and continue to stir for 150 min. The reaction is completed to obtain the coated aluminum hypophosphite.

[0079] Preparation of flame retardant: According to the requirements of the previous formula, mix magnesium hydroxide, coated aluminum hypophosphite and ceramic powder in a high-speed mixer; then slowly add silicone powder at 60°C, treat for 12 min at a speed of 600 rpm, and discharge for standby;

[0080] S1.2 Mixing

[0081] Put the base resin into a high-speed mixer, stir at a speed of 400 rpm at 55°C for 10 min to obtain a premixed resin;

[0082] Add the remaining raw materials to the premixed resin, and hot mix at 75°C for 15 min at a speed of 700 rpm to obtain a premix.

[0083] S2. Send the premix into a twin-screw extruder;

[0084] Temperature settings for each section of the screw: feeding section 150°C, melting section 160°C, first mixing section 175°C, second mixing section 180°C, exhaust section 170°C, and die head 170°C;

[0085] The screw rotation speed was 320 rpm, and the vacuum degree was controlled at -0.07 MPa; the melt-extruded strip was cooled in a 35°C water tank; and the cooled strip was cut into cylindrical particles with a particle size of 3.0 mm.

[0086] Example 2

[0087] The difference between this example and Example 1 is that:

[0088] 47.6 parts of base resin, 52 parts of flame retardant, 6.7 parts of compatible toughening agent, 5.0 parts of smoke suppressant, and 2.8 parts of processing aid;

[0089] The base resin of this example is 13.5 parts of EVA and 34.1 parts of POE;

[0090] The other raw materials, steps, and parameters are the same as in Example 1.

[0091] Example 3

[0092] The difference between this example and Example 1 is that:

[0093] The flame retardant of this example is 15 wt% coated aluminum hypophosphite, 5 wt% ceramic powder, 1.2 wt% silicone powder, and the balance magnesium hydroxide;

[0094] The other raw materials, steps, and parameters are the same as in Example 1.

[0095] Example 4

[0096] The difference between this example and Example 1 is that:

[0097] The flame retardant of this example is 20 wt% coated aluminum hypophosphite, 5 wt% ceramic powder, 1.2 wt% silicone powder, and the balance magnesium hydroxide;

[0098] The other raw materials, steps, and parameters are the same as in Example 1.

[0099] Example 5

[0100] The difference between this example and Example 1 is that:

[0101] The ceramic powder of this example is mullite powder, which is not treated with amino silicone oil;

[0102] The other raw materials, steps, and parameters are the same as in Example 1.

[0103] The ceramic powder of this example has poor compatibility with the base resin, is not uniformly dispersed, and has significantly reduced smoke suppression and mechanical properties.

[0104] Example 6

[0105] The difference between this example and Example 1 is that:

[0106] The smoke suppressant of this example is only ferrocene;

[0107] The other raw materials, steps and parameters are the same as in Example 1.

[0108] Example 7

[0109] The difference between this example and Example 1 is that:

[0110] The smoke suppressant of this example is only zinc borate;

[0111] The other raw materials, steps and parameters are the same as in Example 1.

[0112] Zinc borate has good carbonization and dripping suppression effect, but lacks gas-phase free radical trapping ability, and the smoke suppression performance is insufficient.

[0113] Comparative Example 1

[0114] The difference between this comparative example and Example 1 is that:

[0115] The flame retardant of this comparative example is aluminum hypophosphite, which has not been coated;

[0116] The other raw materials, steps and parameters are the same as in Example 1.

[0117] The acidic aluminum hypophosphite of this comparative example will degrade the base resin during processing, resulting in a decrease in molecular weight. Although the flame retardancy is acceptable, the material loses its value for use.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 1 is that:

[0120] The flame retardant of this comparative example does not contain ceramic powder, and the flame retardant is 20wt% coated aluminum hypophosphite, 1.2wt% silicone powder and the balance magnesium hydroxide;

[0121] The other raw materials, steps and parameters are the same as in Example 1.

[0122] This comparative example does not contain ceramic powder, and the flame retardant efficiency is low, and the smoke and dripping suppression function is poor.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 1 is that:

[0125] The flame retardant of this comparative example is 15wt% ceramic powder, 1.2wt% silicone powder and the balance magnesium hydroxide; the flame retardant does not contain coated aluminum hypophosphite;

[0126] The other raw materials, steps and parameters are the same as in Example 1.

[0127] Comparative Example 4

[0128] The difference between the present comparative example and Example 1 is that:

[0129] The flame retardant of the present comparative example is 15wt% coated aluminum hypophosphite, 10wt% talc powder, 1.2wt% silicone powder and the balance of magnesium hydroxide; the flame retardant of the present comparative example uses talc powder instead of mullite powder treated with amino silicone oil;

[0130] The other raw materials, steps and parameters are the same as those of Example 1.

[0131] The talc powder of the present comparative example only plays a physical filling role, and due to the lack of porous structure on its surface, it is difficult to replace the ceramic powder.

[0132] Test Example

[0133] The polyolefin cable material for energy storage cable prepared from the above examples and comparative examples was subjected to the following tests, and the test results are shown in Table 1;

[0134] Limiting oxygen index (LOI) test: GB / T 2406.2-2009;

[0135] Smoke density (Ds) test: GB / T 8323.2-2008, using a cone calorimeter, 50kW / m 2 Maximum specific optical density under radiation intensity;

[0136] Tensile strength and elongation at break: GB / T 1040.2-2006;

[0137] Dripping test: GB / T 2408-2021, observe whether the defatted cotton is ignited and the dripping condition in the vertical combustion test.

[0138]

[0139] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods. The above specific examples further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. Polyolefin cable compound for energy storage cables, characterized in that, The preparation raw materials include the following components by mass: 30-55 parts of base resin, 40-70 parts of flame retardant, 2-10 parts of compatible toughening agent, 1-8 parts of smoke suppressant, and 1.0-5.0 parts of processing aid; The base resin is 15-50% polyolefin elastomer and the balance polyethylene resin by mass fraction; The flame retardant includes coated aluminum hypophosphite and ceramic powder; the coated aluminum hypophosphite is aluminum hypophosphite coated with ammonium polyphosphate and melamine-formaldehyde resin; The ceramic powder is mullite powder treated with amino silicon oil; The processing aid is at least one of lubricant, antioxidant, and dispersant.

2. The polyolefin cable compound for energy storage cables according to claim 1, characterized in that, The flame retardant is 5-25wt% coated aluminum hypophosphite, 3-20wt% ceramic powder, 0.5-2.5% silicone powder, and the balance magnesium hydroxide by mass fraction.

3. The polyolefin cable compound for energy storage cables according to claim 2, characterized in that, The polyethylene resin is at least one of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and ethylene-vinyl acetate copolymer; And / or, the polyolefin elastomer is at least one of ethylene-octene copolymer, ethylene-butene copolymer, styrene-butadiene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and ternary ethylene-propylene rubber.

4. The polyolefin cable compound for energy storage cables according to claim 2, characterized in that, At least one of the following conditions a-d is met: a. The D50 of the mullite powder is 30-60μm; b. The refractoriness of the mullite powder is ≥1780℃; c. The D50 of the magnesium hydroxide is 3-10μm; d. The D50 of the aluminum hypophosphite is 10-40μm.

5. The polyolefin cable compound for energy storage cables according to claim 1, wherein At least one of the following conditions a-b is met: a. The compatible toughening agent is maleic anhydride grafted polymer; b. The smoke suppressant is 15-45% ferrocene and the balance zinc borate.

6. The polyolefin cable compound for energy storage cables according to claim 1, wherein, The compatible toughening agent is maleic anhydride grafted polyolefin elastomer, maleic anhydride grafted polyethylene, or maleic anhydride grafted ethylene-vinyl acetate.

7. The polyolefin cable compound for energy storage cables according to claim 1, wherein, At least one of the following conditions a-d is met: a. The limiting oxygen index of the polyolefin cable material for energy storage cable is 39-42%; b. The smoke density of the polyolefin cable material for energy storage cable is 80-100; c. The tensile strength of the polyolefin cable material for energy storage cable is ≥12MPa; d. The elongation at break of the polyolefin cable material for energy storage cable is ≥180%.

8. The process for preparing low smoke zero halogen flame retardant polyolefin cable material for energy storage cable according to any one of claims 1 to 7, characterized in that, The method includes the following steps: S1. Prepare raw materials according to the required ratio, pre-mix the base resin, and then hot-mix the other preparation raw materials to obtain a pre-mixed material; S2. Obtain the polyolefin cable material for energy storage cable by melt blending, extruding, cooling, and pelletizing the pre-mixed material.

9. The preparation method of the low-smoke halogen-free flame-retardant polyolefin cable material for energy storage cables as described in claim 8, characterized in that, S1 further includes the step of pre-preparing key components, i.e. the preparation of coated aluminum hypophosphite, the preparation of ceramic powder, and the preparation of flame retardant; The preparation of the flame retardant: mix the coated aluminum hypophosphite, ceramic powder, and magnesium hydroxide, then slowly add silicone powder at 50-70℃, and mix at 500-800rpm for 10-20min to obtain the flame retardant; In S1, the pre-mixing is stirred at 45-65℃ for 5-15min; In S1, the hot-mixing is mixed at 65-85℃ at a speed of 600-900rpm for 10-20min.

10. The method for preparing low-smoke halogen-free flame-retardant polyolefin cable material for energy storage cables as described in claim 9, characterized in that, The preparation of the coated aluminum hypophosphite: 100 parts of aluminum hypophosphite is added to water to prepare a suspension with a solid content of 20-40%, and the pH is adjusted to 7.5-8.5; after the suspension is heated to 65-75℃, 5-15 parts of ammonium polyphosphate is added and stirred for 60-120 min, then 3-10 parts of melamine and 2.4-12 parts of formaldehyde solution are slowly added, the pH is adjusted to 4.5-5.5, and stirring is continued for 120-180 min, and the coated aluminum hypophosphite is obtained after the reaction is completed; And / or, the preparation of the ceramic powder: mullite powder is placed in a high-speed mixer, preheated to 70-90℃, and 1.0-3.0% of amino silicone oil based on the mass of the mullite is slowly added in an atomized spray manner at a rotation speed of 500-800 rpm, and after the spraying is completed, the temperature is maintained and stirring is continued for 20-40 min, and the material is discharged and cooled.

11. The method for preparing low-smoke halogen-free flame-retardant polyolefin cable material for energy storage cables as described in claim 8, characterized in that, In S2, the melt blending is performed using a twin-screw extruder; wherein the temperature of each section of the twin-screw extruder is set as follows: feeding section 140-160℃, melting section 150-170℃, first mixing section 165-180℃, second mixing section 170-185℃, exhaust section 165-175℃, and die head 165-175℃; and / or the rotation speed of the twin screw is 250-400 rpm, and the vacuum degree is controlled at -0.06~-0.08MPa; And / or, in S2, the cooling is performed using a water cooling method at 25-45℃.

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