A high-entropy layered metal hydroxide composite material, a preparation method thereof and a flame-retardant and smoke-suppressing application thereof

Abstract

The application discloses a high-entropy layered metal hydroxide composite material and a preparation method and flame-retardant and smoke-suppressing application thereof. The application aims at the problems of single composition limitation and functional imbalance of traditional LDHs, breaks the composition limitation of traditional LDHs through high-entropy effect design, and constructs a wide-temperature-range stable and high-smoke-suppression-efficiency flame-retardant system by using multi-metal cooperation. The high-entropy metal hydroxide flame-retardant and smoke-suppressing composite material for electric wires and cables has the characteristics of high-efficiency flame retardation, smoke suppression, greenness and high mechanical strength, and is used in the processing of thermoplastic polyurethane for electric wires and cables, so that excellent flame-retardant and smoke-suppressing and toxicity-reducing effects are achieved, and the environment and human bodies are not polluted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flame retardation, and particularly relates to a high-entropy layered metal hydroxide composite material, a preparation method thereof and a flame-retardant and smoke-suppressing application. BACKGROUND

[0002] As a key component in the process of power transportation, wire and cable is prone to fire hazard due to the instability of electricity during long-term use of current, which seriously endangers property safety while endangering life and health. In order to deal with the problems of smoke toxicity hidden danger and insufficient flame retardation of wire and cable in fire scene, the development of a composite material with high smoke suppression, low toxicity and wide range of flame retardation adaptability has become the focus of industry technology research. Thermoplastic polyurethane (TPU) is a kind of high-performance polymer material with very excellent physical and chemical properties, and is widely used in wire and cable materials. However, TPU will release a large amount of smoke and harmful gas during processing and use.

[0003] At present, the methods for improving the smoke suppression performance of TPU mainly include modification of the internal structure of the polymer, blending of additives, and in-situ coating on the surface. Blending of additives is simple in operation, strong in universality, and most commonly used in industrialization. The added additives need to achieve high flame-retardant and smoke-suppressing efficiency and low influence on the mechanical properties of the polymer matrix at a low addition amount, among which, environmental friendliness and price are also important considerations. In the future, the development of environmentally friendly and halogen-free high-efficiency TPU smoke suppression technology will be the research focus, and more environmentally friendly and efficient methods will continue to be explored, and will be widely applied in the fields of intelligent manufacturing and sustainable development.

[0004] In the prior art, layered metal hydroxides (LDHs) are widely used in flame-retardant modification due to their controllable layer and endothermic properties during thermal decomposition. In 2023, the domestic hydrotalcite industry market size reached 145.6 million yuan, and it is expected that the global industrial-grade hydrotalcite market size will reach 320 million US dollars in 2029. LDHs are very promising advanced materials. In recent years, the research on LDHs flame-retardant and smoke-suppressing TPU mainly falls into three categories: LDHs and traditional flame retardants (such as ammonium polyphosphate and aluminum diethyl phosphinate) synergistically flame-retardant and smoke-suppressing TPU (Polym. Degrad. Stab, 2022, 202: 110043. Polym. Degrad. Stab, 2019, 165: 126-136.), LDHs and high-efficiency phosphorus-containing flame retardants (such as DOPO and PEI) synergistically flame-retardant and smoke-suppressing TPU (Appl. Clay Sci., 2024, 258: 107489. Polym. Degrad. Stab, 2020, 178:109179.), and LDHs and inorganic sheet materials (such as Mxene and MoS2) synergistically flame-retardant and smoke-suppressing TPU (J. Polym. Sci., 2024, 62(24): 5693-5705., Constr. Build. Mater., 2024, 457: 139478.). However, there are still some problems in the application of traditional LDHs flame-retardant and smoke-suppressing agents:

[0005] 1. Single component limitation: Traditional LDHs mostly use double / three-metal systems (such as Mg-Al and Zn-Cu), which have limited layer metal types, resulting in low free radical capture efficiency (smoke density level > 70%) and easy layer collapse at high temperatures (thermal stability < 300°C);

[0006] 2. Functional imbalance: Existing solutions mostly focus on optimizing flame-retardant performance (such as reducing heat release rate by > 30%), but the suppression rate of toxic gases such as CO and HCN is insufficient (< 50%), making it difficult to meet the dual requirements of "low smoke and low toxicity" for electrical wires and cables;

[0007] 3. Poor process economy: Multi-metal LDHs require step-by-step co-precipitation or ion exchange, which has a complex process flow and low precision in metal ratio control (deviation > 15%), resulting in high production costs.

[0008] To address the above technical bottlenecks, it is necessary to break the component limitations of traditional LDHs through high-entropy effect design, and to construct a wide-temperature-range stable and high-smoke-suppression-efficiency flame-retardant system through multi-metal synergy (≥ 5 types), which is of great significance to improve the fire safety and environmental friendliness of electrical wires and cables.

[0009] There are some researches on patent applications of high-entropy metal hydroxides, such as the application of high-entropy metal hydroxides as working electrodes (CN118422246A, CN119029197A) and the application of high-entropy metal hydroxides, which shows that high-entropy metal hydroxides have a very promising future, and the multi-metal cooperation has high efficient catalytic effect and stability, but the application of high-entropy metal hydroxides in flame retardation is relatively rare, and there is still a lack of research on the flame retardation application of high-performance TPU materials. It has great research value to design a high-entropy layered metal hydroxide as a low-addition-high-flame-retardant-smoke-suppression efficiency smoke suppression and attenuation hybrid material for TPU as an application of wire and cable material. SUMMARY

[0010] The present application provides a kind of high-entropy layered metal hydroxide composite material and its preparation method and flame-retardant smoke-suppression application to solve the problems of high cost, high toxicity and poor flame retardation of current wire and cable materials. The high-entropy metal hydroxide flame-retardant smoke-suppression composite material has the characteristics of high efficient flame retardation, smoke suppression, green and high mechanical strength. When it is used in the processing of thermoplastic polyurethane for wire and cable, excellent flame retardation and smoke suppression and attenuation effects are achieved, and it is also pollution-free to the environment and human body. The preparation process of the smoke suppression and attenuation composite material is low in cost, easy to operate, green, controllable and batchable.

[0011] Unlike traditional flame retardants, which contain a large amount of toxic elements that may have negative effects on the environment and health, and may release a large amount of toxic gases during fire combustion. The present application focuses on the optimization of flame retardation performance and the dual requirements of low smoke and low toxicity, realizes the multiple effects of process economy and mechanical property optimization, and completes the balance process of synergistic flame retardation and smoke suppression and other properties. The present application designs a kind of high-entropy layered metal hydroxide, which uses multi-metal cooperation (≥5 kinds) to build a wide temperature range stable and high smoke suppression efficiency flame retardation system. The above technologies are the key to preparing low-cost, easy-to-operate, green, low-cost, controllable and high efficient flame retardation and smoke suppression polyurethane material for wire and cable.

[0012] The metal active ingredient of the high-entropy layered metal hydroxide composite material includes multiple kinds of iron, cobalt, nickel, aluminum, magnesium, manganese and zinc.

[0013] Further, the number of metal elements in the metal active ingredient is ≥5.

[0014] Further, the molar ratio of divalent metal to trivalent metal in the metal active ingredient is 2:1 to 3:1, preferably 2:1.

[0015] Exemplarily, the metal active components are 1:1:2:2:2 of iron, aluminum, nickel, cobalt and magnesium, 1:1:2:2:2 of iron, aluminum, nickel, cobalt and manganese, and 1:1:2:2:2 of iron, aluminum, nickel, cobalt and zinc.

[0016] Further, the metal active components are selected from NiCoFeAlMg, NiCoFeAlMn or NiCoFeAlZn.

[0017] Further, the high-entropy layered metal hydroxide has a granular structure or a lamellar structure, and a particle size of 50-200 nm.

[0018] The preparation method of the high-entropy layered metal hydroxide composite material comprises the following steps:

[0019] Step 1: Dissolve the divalent metal salt and the trivalent metal salt in deionized water to obtain a mixed metal salt solution;

[0020] Step 2: Add a precipitating agent to the mixed metal salt solution obtained in Step 1, continuously stir at a temperature of 25-30℃, and obtain a suspension;

[0021] Step 3: Transfer the suspension obtained in Step 2 to a high-pressure reaction kettle, perform hydrothermal reaction at 100-150℃, filter to obtain a precipitate, wash with ethanol and deionized water, and dry to obtain the high-entropy layered metal hydroxide.

[0022] In Step 1, the divalent metal salt and the trivalent metal salt are chlorides of the metal active components, such as magnesium chloride, cobalt chloride, nickel chloride, iron chloride, aluminum chloride, etc. The molar ratio of the divalent metal salt to the trivalent metal salt is between 2:1 and 3:1.

[0023] In Step 2, the precipitating agent is one or more of sodium hydroxide aqueous solution and sodium carbonate aqueous solution. The molar ratio of the precipitating agent to the metal salt is between 2:1 and 4:1.

[0024] The application further provides a preparation method of an organic phosphate in-situ intercalated high-entropy layered metal hydroxide composite material, comprising the following steps:

[0025] Step 1: Dissolve the divalent metal salt and the trivalent metal salt in deionized water to obtain a mixed metal salt solution;

[0026] Step 2: Add an organic phosphate compound and a precipitating agent to the mixed metal salt solution obtained in Step 1, continuously stir at a temperature of 25-30℃, and obtain a suspension;

[0027] Step 3: The suspension obtained in step 2 is transferred to a high-pressure reactor, and a hydrothermal reaction is carried out at 100-150°C, and a precipitate is obtained by filtration, and the precipitate is washed with ethanol and deionized water, and dried to obtain the high-entropy layered metal hydroxide.

[0028] In step 1, the divalent metal salt and the trivalent metal salt are chlorides of metal active components, such as magnesium chloride, cobalt chloride, nickel chloride, iron chloride, aluminum chloride, etc. The molar ratio of the divalent metal salt to the trivalent metal salt is between 2:1 and 3:1.

[0029] In step 2, the organic phosphonate compound is phenylphosphinic acid (PPA) or diphenylphosphoric acid (DPA).

[0030] In step 2, the precipitant is one or more of sodium hydroxide aqueous solution, sodium carbonate aqueous solution.

[0031] The molar ratio of the amount of the precipitant to the metal salt is between 2:1 and 4:1, and the molar ratio of the organic phosphonate to the metal salt is between 1:2 and 1:2.

[0032] The application of the high-entropy layered metal hydroxide composite material is to add the high-entropy layered metal hydroxide as an additive to thermoplastic polyurethane to improve the flame retardant performance and smoke suppression performance of the composite material.

[0033] The application of the organic phosphonate in-situ intercalated high-entropy layered metal hydroxide composite material is to add the organic phosphonate in-situ intercalated high-entropy layered metal hydroxide composite material as an additive to thermoplastic polyurethane to improve the flame retardant performance and smoke suppression performance of the composite material.

[0034] Further, when the high-entropy layered metal hydroxide is added as an additive to thermoplastic polyurethane, a melt blending method is used to construct a TPU composite material. The method includes the following steps:

[0035] (1) The TPU masterbatch is dried in an oven to remove moisture.

[0036] (2) The dried TPU masterbatch is added to a banbury mixer for melting, and then the high-entropy layered metal hydroxide or the organic phosphonate in-situ intercalated high-entropy layered metal hydroxide composite material is added and mixed evenly to obtain a TPU composite material.

[0037] (3) The TPU composite material is hot-pressed on a flat vulcanizing machine to obtain a regular plate.

[0038] Further, the addition amount of the high-entropy layered metal hydroxide or the organic phosphonate in-situ intercalated high-entropy layered metal hydroxide composite material is 1-3wt% of the total mass of the polymer composite material.

[0039] The beneficial effects of the present application are embodied in:

[0040] 1、The present application is aimed at the problems of single component limitation and functional imbalance of traditional LDHs, and breaks the component limitation of traditional LDHs through high-entropy effect design, adopts a multi-metal system to construct an electron-rich structure, and constructs a nano filler with multiple oxygen vacancies and metal defects through scientific interface regulation, thereby having high activity, high structural stability, component adjustability, being conducive to the inhibition of pyrolysis products and the adsorption of toxic gases in the combustion process, and achieving low addition amount and high smoke suppression-flame retardant efficiency through efficient synergistic effect.

[0041] 2、The present application prepares the composite material through one-step hydrothermal method, has a short process route, uses inexpensive raw materials and does not involve flammable and explosive reagents, the process is controllable, the metal ratio regulation precision is high, and has great reference significance for industrial production.

[0042] 3、The present application has simple operation, green production, low production cost, simple process, high efficiency, constructs a wide-temperature-range stable high-smoke-suppression-efficiency flame retardant system, is controllable, has no "three wastes" pollution, saves equipment investment, and is convenient to use. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The embodiments of these drawings illustrate the present application and serve to explain the principles of the present application.

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0045] Figure 1 XRD pattern of NiFeCoAlMg high-entropy LDHs prepared in Example 1.

[0046] Figure 2Scanning electron microscope images of NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and Ni-Fe LDHs prepared in Comparative Example 1; a, b are scanning electron microscope images of Ni-Fe LDHs, the material is rod-like structure, the size is 100-200 nm; c, d are scanning electron microscope images of NiFeCoAlMg, the material is rod-like structure, the size is 1-5 μm; e, f are scanning electron microscope images of NiFeCoAlMn, the material is stacked sheet structure, the size is 30-100 nm; g, h are scanning electron microscope images of NiFeCoAlZn, the material is stacked sheet structure, the size is 100-500 nm.

[0047] Figure 3 N2adsorption and desorption graphs of NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and Ni-Fe LDHs prepared in Comparative Example 1.

[0048] Figure 4 Micro-thermal test results of materials after compounding of different proportions of NiFeCoAlMg high-entropy LDHs prepared in Example 1 with TPU; the peak heat release of the material with an addition amount of 3 wt% is the lowest, and an addition amount of 3 wt% is preferably selected for testing and research.

[0049] Figure 5 Cone calorimeter test results of NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and Ni-Fe LDHs prepared in Comparative Example 1 at 35 kW; a is the heat release rate curve of the material, b is the total heat release curve, c is the smoke release rate curve, d is the total smoke release curve, e is the CO generation rate curve, and f is the CO2 generation rate curve; the addition of high-entropy LDHs significantly reduces the heat release and smoke release of the composite material, and the effect is further improved compared with Ni-Fe LDHs; the effect of NiFeCoAlMn / TPU is the best, with a peak heat release reduction of 40.76%, a total heat release reduction of 22.32%, and a total smoke release reduction of 45.79%. It is proved that the addition of high-entropy LDHs significantly reduces the smoke and heat release of the polyurethane composite material.

[0050] Figure 6Combustion smoke density test results of NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and Ni-Fe LDHs prepared in Comparative Example 1 at 25 kW; a is the smoke density curve of the material, b is the column chart of the maximum value of smoke release, c is the column chart of the time to reach the maximum value of smoke release, the addition of high-entropy LDHs also reduces the combustion smoke density of the composite material before intercalation, the effect of NiFeCoAlMn / TPU is the best, which is reduced by 13.5%, but the addition of all materials will cause the TPU to burn prematurely.

[0051] Figure 7 Tensile test data of NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and Ni-Fe LDHs prepared in Comparative Example 1. a is the tensile property diagram, b is the maximum tensile strength, c is the elongation at break. The addition of high-entropy LDHs reduces the mechanical properties of the material due to uneven distribution.

[0052] Figure 8 Cone calorimeter test results of NiFeCoAlMg / DPA, NiFeCoAlMn / DPA, NiFeCoAlZn / DPA, NiFeCoAlMg / PPA, NiFeCoAlMn / PPA and NiFeCoAlZn / PPA intercalated high-entropy LDHs prepared in Examples 4-9 at 35 kW; a is the heat release rate curve of the material, b is the total heat release curve, c is the smoke release rate curve, d is the total smoke release curve, after intercalation of high-entropy LDHs, the heat release and smoke release of the composite material are further reduced, among which the effect of NiCoFeAlZn / PPA / TPU is the highest, the peak heat release is reduced by 42.09%, and the total smoke release is reduced by 48.55%, indicating that the intercalation of organic acid root further improves the fire safety performance of the material.

[0053] Figure 9 Combustion smoke density test results of NiFeCoAlMg / DPA, NiFeCoAlMn / DPA, NiFeCoAlZn / DPA, NiFeCoAlMg / PPA, NiFeCoAlMn / PPA and NiFeCoAlZn / PPA intercalated high-entropy LDHs prepared in Examples 4-9 at 25 kW; a is the smoke density curve of the material, b is the column chart of the maximum value of smoke release, c is the column chart of the time to reach the maximum value of smoke release. After intercalation, the smoke suppression effect of high-entropy LDHs is significantly improved, with the highest reduction of 61.6%, which reflects the excellent smoke and toxicity suppression effect of intercalated high-entropy LDHs on the material.

[0054] Figure 10Tensile test data of NiFeCoAlMg / DPA, NiFeCoAlMn / DPA, NiFeCoAlZn / DPA, NiFeCoAlMg / PPA, NiFeCoAlMn / PPA and NiFeCoAlZn / PPA intercalated high-entropy LDHs prepared in Examples 4-9, a is the tensile performance diagram, b is the maximum tensile strength, c is the elongation at break. After the material is intercalated, the mechanical properties of the material are improved due to the presence of organic acid anions, which shows that the addition of organic acid anions is beneficial to maintaining the overall performance of the material.

[0055] Figure 11 The fracture surface scanning electron micrographs of the NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and the Ni-Fe LDHs prepared in Comparative Example 1 distributed in the TPU material, a, b, c are the SEM images of the TPU quenched fracture surface, the fracture surface is very smooth; d, e, f are the SEM images of the Ni-Fe LDHs / TPU quenched fracture surface, there are a large number of channels on the fracture surface, which affects the mechanical properties of the material; g, h, i are the SEM images of the NiFeCoAlMg / TPU quenched fracture surface, the channels are significantly smaller; j, k, l are the SEM images of the NiFeCoAlMn / TPU quenched fracture surface, the channels are smaller; m, n, o are the SEM images of the NiFeCoAlZn / TPU quenched fracture surface, the channels are smaller, but still affect the mechanical properties.

[0056] Figure 12 The Raman spectra of the carbon residues generated by combustion of the NiFeCoAlMg, NiFeCoAlMn, NiFeCoAlZn high-entropy LDHs prepared in Examples 1-9 and the NiFeCoAlMg / PPA, NiFeCoAlMn / PPA and NiFeCoAlZn / PPA intercalated high-entropy LDHs and the Ni-Fe LDHs prepared in Comparative Example 1 after compounding in the TPU material. a is the Raman spectrum of the TPU carbon residue, I D / I G is 3.17, b is the Raman spectrum of the NiFeCoAlMg / TPU carbon residue, I D / I G is 4.11, c is the Raman spectrum of the NiFeCoAlMn TPU carbon residue, I D / I G is 4.03, d is the Raman spectrum of the NiFeCoAlZn / TPU carbon residue, I D / I G is 3.34, e is the Raman spectrum of the NiFeCoAlMg / DPA / TPU carbon residue, I D / I GRaman spectrum of the carbon residue of NiFeCoAlMg / DPA / TPU, I D / I G Raman spectrum of the carbon residue of NiFeCoAlMg / DPA / TPU, I D / I G Raman spectrum of the carbon residue of NiFeCoAlMg / DPA / TPU, I D / I G The greater the value, the higher the degree of graphitization of the carbon residue, which is conducive to forming a barrier during combustion.

[0057] Figure 13 Scanning electron microscope images of the carbon residue after combustion of the NiFeCoAlMg, NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and the Ni-Fe LDHs prepared in Comparative Example 1 after being compounded in TPU materials. a, b, c are SEM images of TPU carbon residues, which are broken and loose; d, e, f are SEM images of Ni-Fe LDHs / TPU carbon residues; g, h, i are SEM images of NiFeCoAlMg / TPU carbon residues; j, k, l are SEM images of NiFeCoAlMn / TPU carbon residues; m, n, o are SEM images of NiFeCoAlZn / TPU carbon residues, which become dense. DETAILED DESCRIPTION

[0058] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0059] Except as shown in the working examples or otherwise indicated, all numbers expressing quantities of ingredients, properties such as physical properties, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present disclosure. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Numerical ranges include all numbers and ranges between the numbers, inclusive of those numbers. For example, a range from 1 to 5 includes 1, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0060] Specifically comprising the following steps:

[0061] S1, high-entropy layered metal hydroxides are prepared by a combination of coprecipitation and hydrothermal methods;

[0062] S11, magnesium chloride, cobalt chloride, nickel chloride, iron chloride, aluminum chloride (molar ratio of divalent metal salt to trivalent metal salt is between 2:1-3:1, total metal salt content is 0.16-0.2 mol) are dissolved in deionized water solution; sodium hydroxide solution and / or sodium carbonate aqueous solution are used as precipitants and added to the mixed chloride salt solution, and stirring is continuously carried out at a temperature range of 25-30°C; exemplarily, magnesium chloride is 0.04 mol, cobalt chloride is 0.04 mol, nickel chloride is 0.04 mol, iron chloride is 0.02 mol, and aluminum chloride is 0.02 mol.

[0063] S12, the above suspension is transferred to a high-pressure reaction kettle, and a hydrothermal reaction is carried out at 100-150°C. The precipitated product is obtained by filtration, washed with ethanol and deionized water, collected, and dried in a blast oven to obtain NiFeCoAlMg high-entropy LDHs.

[0064] S13, the preparation method of NiFeCoAlMn high-entropy LDHs and NiFeCoAlZn high-entropy LDHs is similar, and the selected metals are different, and the NiFeCoAlMn high-entropy LDHs select Ni, Fe, Co, Al and Mn; and the NiFeCoAlZn high-entropy LDHs select Ni, Fe, Co, Al and Zn.

[0065] S2, a phosphorus-containing organic acid is used for in-situ intercalation of high-entropy LDHs to obtain organic acid intercalated high-entropy LDHs.

[0066] S21, phenylphosphinic acid (PPA) and diphenylphosphoric acid (DPA) are selected as organic phosphoric acid for in-situ intercalation of high-entropy layered metal hydroxide.

[0067] S22, magnesium chloride, cobalt chloride, nickel chloride, iron chloride, and magnesium chloride (molar ratio of divalent metal salt to trivalent metal salt is between 2:1-3:1, total metal salt content is 0.16-0.2 mol) are dissolved in deionized water solution; sodium hydroxide solution and sodium carbonate aqueous solution containing organic phosphoric acid are used as precipitants and added to the mixed chloride salt solution, and stirring is continuously carried out at a temperature range of 25-30°C; exemplarily, magnesium chloride is 0.04 mol, cobalt chloride is 0.04 mol, nickel chloride is 0.04 mol, iron chloride is 0.02 mol, aluminum chloride is 0.02 mol, and phenylphosphinic acid is 0.1 mol.

[0068] S23, the above suspension is transferred to a high-pressure reactor, and a hydrothermal reaction is carried out at 100-150°C. The precipitate is obtained by filtration, washed with ethanol and deionized water, collected, and dried in a blast oven to obtain PPA intercalated NiFeCoAlMg high-entropy LDHs, denoted as NiFeCoAlMg / PPA.

[0069] S24, the preparation method of DPA intercalated high-entropy LDHs and PPA intercalated high-entropy LDHs is similar, and the selected organic phosphate is changed from phenyl phosphinic acid (PPA) to diphenyl phosphoric acid (DPA) to prepare DPA intercalated NiFeCoAlMg high-entropy LDHs, denoted as NiFeCoAlMg / DPA.

[0070] S25, the preparation method of organic phosphoric acid intercalated NiFeCoAlMn high-entropy LDHs and NiFeCoAlZn high-entropy LDHs is similar, and the selected metal is different. The NiFeCoAlMn high-entropy LDHs selects Ni, Fe, Co, Al and Mn, denoted as NiFeCoAlMn / PPA and NiFeCoAlMn / DPA; the NiFeCoAlZn high-entropy LDHs selects Ni, Fe, Co, Al and Zn, denoted as NiFeCoAlZn / PPA and NiFeCoAlZn / DPA.

[0071] The present disclosure is described in more detail by the following examples, which are merely illustrative and not limiting, as various modifications and changes in the examples obviously can be made by those skilled in the art within the scope of the present disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used as received without further purification, and the instruments used in the examples are commercially available.

[0072] Example 1:

[0073] Different metal chloride precursors are selected to prepare high-entropy LDHs. Taking the preparation of NiFeCoAlMn high-entropy LDHs as an example, the metal salt precursors include nine water and aluminum chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, and six water and magnesium chloride.

[0074] 1. Dissolve nine water and aluminum chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, six water and magnesium chloride in deionized water in a ratio of 2:1-3:1 (molar ratio of divalent metal salt to trivalent metal salt, total metal salt content of 0.16-0.2 mol) and stir constantly to mix evenly at a stirring rate of 300 rpm and a stirring temperature of 25 °C for 1 h. Label this mixed solution as solution A.

[0075] 2. Dissolve 6 g of sodium hydroxide in 100 ml of deionized water at a stirring rate of 300 rpm and a stirring temperature of 25 °C for 1 h. Label this mixed solution as solution B.

[0076] 3. Dissolve 15.9 g of sodium carbonate in 100 ml of deionized water at a stirring rate of 300 rpm and a stirring temperature of 25 °C for 1 h. Label this mixed solution as solution C.

[0077] 4. Slowly add solution A and solution B to solution C while maintaining the pH of solution C at 10, and the entire reaction stirring rate at 300 rpm and a stirring temperature of 25 °C for 10 min. Take 400 ml of the suspension produced by the co-precipitation reaction and transfer it to a Teflon-lined stainless steel autoclave, and perform a hydrothermal reaction at 120 °C for 12 h. After the hydrothermal reaction, collect the precipitated product by centrifugation, wash it with ethanol and deionized water until the pH is about 7, centrifuge at 6000 rpm for 5 min, collect the precipitated product, and dry it in a blast oven at 60 °C for 12 h. Obtain NiFeCoAlMg high-entropy LDHs.

[0078] Example 2:

[0079] Example 2 is basically the same as Example 1, with the main difference being that the metal salt precursors are different. The metal salt precursors include nine water and aluminum chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, and four water and manganese chloride. NiFeCoAlMn high-entropy LDHs are prepared.

[0080] Example 3:

[0081] Example 3 is basically the same as Example 1, with the main difference being that the metal salt precursors are different. The metal salt precursors include nine water and aluminum chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, and zinc chloride. NiFeCoAlZn high-entropy LDHs are prepared.

[0082] Example 4:

[0083] Selecting phosphorus-containing organic acid root for intercalation of high-entropy LDH to achieve high flame retardancy and retention of tensile properties, selecting phenyl phosphinic acid (PPA) for in-situ intercalation experiment of LDH. Taking intercalated NiFeCoAlMg high-entropy LDH as an example. Metal salt precursors include nine water and aluminum chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, and six water and magnesium chloride.

[0084] 1. Mix six water and magnesium chloride, six water and cobalt chloride, six water and nickel chloride, nine water and iron chloride, and nine water and aluminum chloride in a certain proportion (the molar ratio of divalent metal salt to trivalent metal salt is between 2:1 and 3:1, and the total metal salt content is 0.16-0.2 mol), dissolve in 200 ml of deionized water, continuously stir to mix evenly, the stirring rate is 300 rpm, the stirring temperature is 25℃, and the stirring time is 1h. The mixed solution is marked as solution A.

[0085] 2. Dissolve 6g of sodium hydroxide in 100ml of deionized water, add phenyl phosphinic acid PPA (the molar ratio of phenyl phosphinic acid to LDH metal is 0.5-2), the stirring rate is 300 rpm, the stirring temperature is 25℃, and the stirring time is 1h. The mixed solution is marked as solution B.

[0086] 3. Dissolve 15.9 grams of sodium carbonate in 100 ml of deionized water, the stirring rate is 300 rpm, the stirring temperature is 25℃, and the stirring time is 1h. The mixed solution is marked as solution C.

[0087] 4. Slowly add solution A and solution B to solution C, while keeping the pH value of solution C at 10, the whole reaction stirring rate is 300 rpm, the stirring temperature is 25℃, and the reaction stirring time is 10 min. Take 400 ml of the suspension produced by the co-precipitation reaction and transfer it to a Teflon-lined stainless steel high-pressure reactor, and carry out hydrothermal reaction at 120℃ for 12 hours. After hydrothermal reaction, the precipitate product is collected by centrifugation, washed with ethanol and deionized water until the pH is about 7, the centrifugal speed is 6000 rpm, the centrifugal time is 5 min, the obtained precipitate product is collected and placed in a blast drying oven for drying for 12h at 60℃. PPA intercalated NiFeCoAlMg high-entropy LDHs are obtained, marked as NiCoFeAlMg / PPA.

[0088] Example 5:

[0089] Example 5 and Example 4 are substantially the same, the main difference is that the phosphorus-containing organic acid is different, diphenylphosphoric acid (DPA) is selected for in-situ intercalation experiment of LDH, and the metal salt precursors include aluminum chloride nine water, cobalt chloride six water, nickel chloride six water, iron chloride nine water and magnesium chloride six water. DPA intercalated NiFeCoAlMg high-entropy LDHs are obtained, denoted as NiCoFeAlMg / DPA.

[0090] Example 6:

[0091] Example 6 and Example 4 are substantially the same, the main difference is that the metal salt precursors are different, and the metal salt precursors are synthesized by changing the metal salt according to the stoichiometric ratio. The metal salt precursors include aluminum chloride nine water, cobalt chloride six water, nickel chloride six water, iron chloride nine water and manganese chloride four water. The selected organic phosphoric acid is the same, which is phenyl phosphinic acid (PPA). PPA intercalated NiFeCoAlMn high-entropy LDHs are obtained, denoted as NiCoFeAlMn / PPA.

[0092] Example 7:

[0093] Example 7 and Example 5 are substantially the same, the main difference is that the metal salt precursors are different, and the metal salt precursors are synthesized by changing the metal salt according to the stoichiometric ratio. The metal salt precursors include aluminum chloride nine water, cobalt chloride six water, nickel chloride six water, iron chloride nine water and manganese chloride four water. The selected organic phosphoric acid is the same, which is diphenylphosphoric acid (DPA). DPA intercalated NiFeCoAlMn high-entropy LDHs are obtained, denoted as NiCoFeAlMn / DPA.

[0094] Example 8:

[0095] Example 8 and Example 4 are substantially the same, the main difference is that the metal salt precursors are different, and the metal salt precursors are synthesized by changing the metal salt according to the stoichiometric ratio. The metal salt precursors include aluminum chloride nine water, cobalt chloride six water, nickel chloride six water, iron chloride nine water and zinc chloride. The selected organic phosphoric acid is the same, which is phenyl phosphinic acid (PPA). PPA intercalated NiFeCoAlZn high-entropy LDHs are obtained, denoted as NiFeCoAlZn / PPA.

[0096] Example 9:

[0097] Example 9 and Example 5 are substantially the same, the main difference is that the metal salt precursors are different, and the metal salt precursors are synthesized by changing the metal salt according to the stoichiometric ratio. The metal salt precursors include aluminum chloride nine water, cobalt chloride six water, nickel chloride six water, iron chloride nine water and zinc chloride. The selected organic phosphoric acid is the same, which is diphenylphosphoric acid (DPA). DPA intercalated NiFeCoAlZn high-entropy LDHs are obtained, denoted as NiFeCoAlZn / DPA.

[0098] Comparative Example 1:

[0099] Comparative Example 1 and Example 1 are basically the same, the main difference is the difference of metal salt precursor, the metal salt precursor includes six water and nickel chloride and nine water and ferric chloride. The prepared NiFe-LDH is compared with the rest of the high-entropy LDHs.

[0100] Experimental Example 1:

[0101] The NiFeCoAlMg-LDH high-entropy LDHs prepared in Example 1 were analyzed by XRD diffractometer, and the mixed characteristic peaks of NiFe LDH (PDF #40-0215), CoFe LDH (PDF #50-0235), and NiAl LDH (PDF #15-0087) existed in the composite sample, which indicated that the NiFeCoAlMg high-entropy LDHs were successfully prepared, and contained different LDHs.

[0102] Experimental Example 2:

[0103] The NiFeCoAlMg, NiFeCoAlMn, and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and the Ni-Fe LDHs prepared in Comparative Example 1 were analyzed by scanning electron microscopy to analyze the morphology of the synthesized materials. The Ni-Fe LDHs and the NiFeCoAlMg high-entropy LDHs were rod-shaped structures with a size of 100-200 nm, and the NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs were stacked sheet structures with a size of 50-100 nm.

[0104] Experimental Example 3:

[0105] The NiFeCoAlMg, NiFeCoAlMn, and NiFeCoAlZn high-entropy LDHs prepared in Examples 1-3 and the Ni-Fe LDHs prepared in Comparative Example 1 were analyzed by N2 adsorption and desorption to analyze the specific surface area and pore size distribution of the synthesized materials. The four synthesized LDHs were all mesoporous materials, and the N2 adsorption and desorption graphs were all type IV hysteresis loops. The hysteresis loops of the Ni-Fe LDHs and the NiFeCoAlMg high-entropy LDHs were the same, both being H3 type hysteresis loops corresponding to the pores produced by stacked irregular rods. The hysteresis loops of the NiFeCoAlMn and NiFeCoAlZn high-entropy LDHs were the same, both being H4 type hysteresis loops corresponding to the pores of irregular sheets. The analysis results were the same as the conclusions of the scanning electron microscopy data.

[0106] Experimental Example 4:

[0107] The smoke-reducing and attenuated hybrid material is added as an additive to the thermoplastic polyurethane. The composite material is constructed by using a melt blending method. After the TPU master batch is dried, it is subjected to melting in an internal mixer. Then, the LDHs smoke-reducing agent is added to mix uniformly. Thus, the TPU composite material is obtained. The composite material is subjected to hot pressing on a flat vulcanizing machine to obtain a regular plate.

[0108] (1) The TPU master batch is dried in an oven for 6 h to remove water for use.

[0109] (2) The dried TPU master batch is subjected to melting in an internal mixer. The temperature of the internal mixer is 180 °C, and the rotating speed of the internal mixer is 140 rpm. After the TPU is melted, the prepared LDHs smoke-reducing agent is added to the internal mixer under stirring. The addition amount of the smoke-reducing agent is 3 wt%. The mixture is stirred for 5 min to mix uniformly. Thus, the TPU composite material is obtained.

[0110] (3) The obtained irregular TPU composite material is subjected to hot pressing to obtain a regular plate. The material size and standard are determined according to the national standard for combustion test. The hot pressing process is performed on a flat vulcanizing machine. The hot pressing temperature is 185 °C, the pressure is 10 MPa, the preheating time is 3-5 min, and the hot pressing time is 1-3 min.

[0111] The smoke-reducing agent material is selected from the Ni-Fe LDH powder prepared in Comparative Example 1, the NiFeCoAlMg-LDH powder prepared in Example 1, the NiFeCoAlMn-LDH powder prepared in Example 2, the NiFeCoAlZn-LDH powder prepared in Example 3, the NiCoFeAlMg / PPA powder prepared in Example 4, the NiCoFeAlMg / DPA powder prepared in Example 5, the NiCoFeAlMn / PPA powder prepared in Example 6, the NiCoFeAlMn / DPA powder prepared in Example 7, the NiCoFeAlZn / PPA powder prepared in Example 8, and the NiCoFeAlZn / DPA powder prepared in Example 9.

[0112] According to different smoke-reducing agent materials, the prepared composite materials are named as Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU, and NiCoFeAlZn / DPA / TPU.

[0113] The prepared flame-retardant TPU composite (Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU and NiCoFeAlZn / DPA / TPU) and TPU material were tested for heat release rate, total heat release, smoke release rate and total smoke release under 35 kW by a cone calorimeter, as shown in FIGS. Figure 5 and Figure 8 The effects of different smoke suppressants on the combustion process of TPU material are shown, as shown in FIGS. 1 to 8, wherein the addition of high-entropy LDHs significantly reduces the heat release and smoke release of the composite material, and the effect is further improved compared with Ni-Fe LDHs; the effect of NiFeCoAlMn / TPU is the best, with a peak heat release reduction of 40.76%, a total heat release reduction of 22.32% and a total smoke release reduction of 45.79%. It is proved that the addition of high-entropy LDHs significantly reduces the smoke and heat of the polyurethane composite material. When the high-entropy LDHs are intercalated, the heat release and smoke release of the composite material are further reduced, wherein the effect of NiCoFeAlZn / PPA / TPU is the highest, with a peak heat release reduction of 42.09% and a total smoke release reduction of 48.55%, which shows that the intercalation of organic acid root further improves the fire safety performance of the material.

[0114] Experimental Example 5:

[0115] The smoke density of the flame-retardant TPU composite (Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU and NiCoFeAlZn / DPA / TPU) prepared in Experimental Example 4 was tested during combustion, as shown in the smoke density curves of the composite material shown in FIGS. Figure 6 and FIGS. Figure 9 Before intercalation, the addition of high-entropy LDHs also reduces the smoke density of the composite material during combustion, and the effect of NiFeCoAlMn / TPU is the best, with a reduction of 13.5%; after intercalation, the smoke suppression effect of high-entropy LDHs is significantly improved, with a maximum reduction of 61.6%, which reflects the excellent smoke and toxicity suppression effect of high-entropy LDHs after intercalation on the material.

[0116] Experimental Example 6:

[0117] The smoke density during combustion of the flame-retardant TPU composite materials (Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU, and NiCoFeAlZn / DPA / TPU) prepared in Experimental Example 4 was tested. See Appendix. Figure 6 and attached Figure 9 The smoke density curves of the composite materials are shown. Before intercalation, the addition of high-entropy LDHs also reduced the smoke density of the composite materials, with NiFeCoAlMn / TPU showing the best effect, reducing it by 13.5%. After intercalation, the smoke suppression effect of high-entropy LDHs was significantly improved, with a maximum reduction of 61.6%, demonstrating the excellent smoke and toxicity suppression effect of intercalated high-entropy LDHs on the material.

[0118] Experimental Example 7:

[0119] Tensile tests were performed on the flame-retardant TPU composites (Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU, and NiCoFeAlZn / DPA / TPU) prepared in Experimental Example 4 to determine their mechanical properties. See Appendix. Figure 7 and attached Figure 10 The mechanical curves of the composite material are shown. The uneven distribution of high-entropy LDHs reduces the mechanical properties of the material. After intercalation, the presence of organic acid radicals improves the mechanical properties, indicating that the addition of organic acid radicals helps maintain the overall performance of the material. Scanning electron microscopy was performed on the cross-section of the flame-retardant TPU composite material prepared in Experimental Example 4. (See attached image). Figure 11The mechanical curves of the composite materials shown in the figure show that the addition of Ni-Fe LDHs causes uneven distribution and a large number of holes in the material, affecting its mechanical properties; the addition of high-entropy LDHs causes metal dislocation effect, and different lattice spacings make the mechanical properties of the material improve a little, but still decrease compared with pure TPU. After the material is intercalated with organic acid, the addition of organic acid root promotes the dispersion of the material and is beneficial to the improvement of the mechanical properties of the material. Organic acid intercalated high-entropy LDHs can achieve high flame retardancy and tensile strength retention at high filling.

[0120] Experimental Example 8:

[0121] The carbon residues after combustion of the flame-retardant TPU composites (Ni-Fe LDH / TPU, NiFeCoAlMg-LDH / TPU, NiFeCoAlMn-LDH / TPU, NiFeCoAlZn-LDH / TPU, NiCoFeAlMg / PPA / TPU, NiCoFeAlMg / DPA / TPU, NiCoFeAlMn / PPA / TPU, NiCoFeAlMn / DPA / TPU, NiCoFeAlZn / PPA / TPU and NiCoFeAlZn / DPA / TPU) prepared in Experimental Example 4 were subjected to scanning electron microscope test and Raman spectrum test, as shown in the scanning electron microscope images and Raman spectrum images of the carbon residues shown in Figure 12 and Figure 13 The scanning electron microscope images and Raman spectrum images of the carbon residues shown in the figure show that the addition of high-entropy LDHs makes the carbon residues after combustion of the material more compact, which is beneficial to the formation of a barrier to achieve the effect of flame retardation. The results of I D / I G in the Raman spectrum image can also prove this point. The larger I D / I G , the higher the graphitization degree of the carbon residues, which is beneficial to the formation of a barrier during combustion.

[0122] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. The application of a high-entropy layered metal hydroxide composite material, characterized in that: the high-entropy layered metal hydroxide is added as an additive to thermoplastic polyurethane to improve the flame retardant and smoke suppression performance of the composite material; and a preparation method of the high-entropy layered metal hydroxide composite material, comprising the following steps: Step 1: dissolving divalent metal salt and trivalent metal salt in deionized water to obtain a mixed metal salt solution; Step 2: adding a precipitant to the mixed metal salt solution obtained in Step 1, continuously stirring at a temperature of 25-30°C to obtain a suspension; Step 3: transferring the suspension obtained in Step 2 to a high-pressure reaction kettle, performing hydrothermal reaction at 100-150°C, filtering to obtain a precipitate, washing with ethanol and deionized water, and drying to obtain a high-entropy layered metal hydroxide; in Step 1, the divalent metal salt and trivalent metal salt are chlorides of metal active ingredients, and the metal active ingredients are NiFeCoAlMn; in the metal active ingredients, the molar ratio of divalent metal to trivalent metal is 2:1 to 3:

1.

2. The application according to claim 1, characterized in that: in Step 2, the precipitant is one or more of sodium hydroxide and sodium carbonate, and the molar ratio of precipitant addition amount to metal salt is 2:1-4:

1.

3. The application of an organic phosphate in-situ intercalated high-entropy layered metal hydroxide composite material, characterized in that: the organic phosphate in-situ intercalated high-entropy layered metal hydroxide composite material is added as an additive to thermoplastic polyurethane to improve the flame retardant and smoke suppression performance of the composite material; and a preparation method of the organic phosphate in-situ intercalated high-entropy layered metal hydroxide composite material, comprising the following steps: Step 1: dissolving divalent metal salt and trivalent metal salt in deionized water to obtain a mixed metal salt solution; Step 2: adding an organic phosphate compound and a precipitant to the mixed metal salt solution obtained in Step 1, continuously stirring at a temperature of 25-30°C to obtain a suspension; and then performing hydrothermal reaction in Step 3 to obtain an organic phosphate in-situ intercalated high-entropy layered metal hydroxide composite material; in Step 1, the divalent metal salt and trivalent metal salt are chlorides of metal active ingredients, and the metal active ingredients are NiCoFeAlZn; in the metal active ingredients, the molar ratio of divalent metal to trivalent metal is 2:1 to 3:1; and in Step 2, the organic phosphate compound is phenyl phosphinic acid or diphenyl phosphoric acid, and the molar ratio of organic phosphate to metal salt is 1:

2.

4. The application according to claim 3, characterized in that: in Step 2, the precipitant is one or more of sodium hydroxide and sodium carbonate, and the molar ratio of precipitant addition amount to metal salt is 2:1-4:

1. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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