Polyethylene composite flame-retardant material based on high-entropy oxide and preparation method thereof
By introducing spinel-type high-entropy oxides composed of Fe, Mn, Cu, Co, Ni and Cr into polyethylene materials, a synergistic mechanism of gas-phase catalytic oxidation and condensed-phase carbonization is constructed, which solves the problems of flammability and toxic gas release in polyethylene, and achieves efficient smoke suppression and toxicity reduction as well as improved thermal stability. It is suitable for high-safety-level scenarios such as construction, rail transportation and electronic appliances.
Patent Information
- Application Number
- CN202511998948.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-03-03
AI Technical Summary
Existing polyethylene materials are flammable and release toxic gases during combustion. Traditional intumescent flame retardants have poor thermal stability and cannot meet the requirements of high-safety-level scenarios.
By introducing spinel-type high-entropy oxides composed of Fe, Mn, Cu, Co, Ni and Cr, and through a synergistic mechanism of gas-phase catalytic oxidation and condensed-phase carbonization, combined with ammonium polyphosphate and triazine char-forming agents, a highly efficient flame-retardant composite material is constructed.
It achieves efficient smoke suppression and toxicity reduction, improves the thermal stability and safety of materials, and meets the usage requirements of high-safety-level scenarios such as buildings, rail transit, and electronic appliances.
Smart Images
Figure CN121592099A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer flame retardant materials technology, specifically relating to polyethylene composite flame retardant materials based on high-entropy oxides and their preparation methods. Background Technology
[0002] Polyethylene, with its excellent mechanical strength, good electrical insulation properties, and outstanding processing adaptability, has been widely used in many fields such as wire and cable insulation, building decoration materials, transportation pipelines, and packaging materials. However, polyethylene itself has highly flammable properties and is prone to violent combustion during pyrolysis or combustion, releasing large amounts of toxic and harmful gases such as carbon monoxide and ethylene, as well as molten drippings. This defect seriously limits the further application of polyethylene materials in fields with high fire safety requirements, such as construction, rail transportation, and electronic appliances.
[0003] To improve the flame retardant properties of polyethylene, the industry commonly uses intumescent flame retardant systems to modify polyethylene. These systems form an expanded porous carbon layer through acid-catalyzed carbonization at high temperatures. This carbon layer physically blocks heat transfer and oxygen contact, thus inhibiting the continued combustion of the polymer matrix. However, traditional intumescent flame retardant systems still face significant technical bottlenecks: firstly, their thermal stability is poor, and they are prone to premature decomposition at lower temperatures, causing their flame retardant efficiency to decrease rapidly with increasing temperature; secondly, their smoke suppression and toxicity reduction capabilities are limited. In the early stages of a fire, the carbon layer forms slowly and is insufficiently dense, making it difficult to effectively intercept toxic gases produced by polyethylene pyrolysis. Furthermore, the carbon layer is prone to cracking and detachment in the later stages of high-temperature combustion, failing to achieve coordinated control of heat release and toxic gas emissions, and thus still failing to meet the requirements of high-safety-level scenarios.
[0004] In recent years, polymetallic oxides have been extensively studied due to their excellent thermal stability and surface catalytic activity, and have been applied as synergistic flame retardants in polymer material systems. Among them, high-entropy oxides, as novel multi-component functional materials, consist of five or more metal elements in equimolar or near-equimolar ratios forming a solid solution structure, exhibiting high structural stability, abundant oxygen vacancies, and excellent redox capabilities. High-entropy oxides demonstrate significant advantages in catalytic carbonization, degradation of toxic gases, and catalytic oxidation, and are expected to become a hot topic in high-performance flame retardant research in recent years.
[0005] However, the strategy of systematically introducing high-entropy oxides into polyethylene flame-retardant systems has not yet been studied. On the one hand, during the preparation of high-entropy oxides, various metal elements are prone to component segregation, structural inhomogeneity, and particle agglomeration; on the other hand, their dispersibility, catalytic synergy mechanism, and structural stability in polyethylene systems urgently need to be addressed. Therefore, it is urgent to develop a high-entropy oxide system with uniform structure, good dispersibility, and synergistic flame-retardant effects in both the gas and condensed phases, and to construct highly efficient flame-retardant composite materials compatible with polyethylene materials. Summary of the Invention
[0006] This invention aims to provide a polyethylene composite flame retardant material based on high-entropy oxides and its preparation method. By introducing high-entropy oxides composed of Fe, Mn, Cu, Co, Ni and Cr, the gas-phase catalytic oxidation and condensed-phase carbonization behavior of polyethylene during combustion are synergistically regulated, thereby achieving the flame retardant goals of efficient smoke suppression, toxicity reduction and improved structural thermal stability.
[0007] On the one hand, the polyethylene composite flame-retardant material based on high-entropy oxides provided by this invention adopts the following technical solution: The polyethylene composite flame retardant material based on high-entropy oxides comprises the following components by mass percentage: Polyethylene 65-69%, maleic anhydride grafted polyethylene 5%, flame retardant 25-29%, and spinel-type high entropy oxide 0.5-3%; The spinel-type high-entropy oxide includes the following elements: Fe, Mn, Cu, Co, Ni, and Cr.
[0008] Preferably, the method for preparing the spinel-type high-entropy oxide includes the following steps: 1) Prepare ferric chloride hexahydrate, manganese chloride tetrahydrate, copper chloride dihydrate, cobalt chloride hexahydrate, nickel chloride hexahydrate, and chromium chloride hexahydrate. Mix them with melamine at a mass ratio of 1:18 to obtain six parts of the mixture. Dissolve the six parts of the mixture in a mixture of water and hydrochloric acid, and heat and stir until the solvent evaporates to dryness to obtain six parts of solid metal precursors. 2) Take six parts of the solid metal precursor obtained in step 1) and calcine them in an air atmosphere to obtain six parts of metal-based precursor. 3) Disperse the six portions of the metal-based precursor obtained in step 2) in hydrochloric acid buffer, add dopamine hydrochloride, sonicate and stir the reaction, centrifuge, dry and calcine in air to obtain a high-entropy oxide with a spinel structure.
[0009] Preferably, in step 1), the volume ratio of water to hydrochloric acid in the mixture is 4:1; and the heating and stirring temperature is 90-130℃.
[0010] Preferably, the calcination temperature in step 2) is 500-600℃, and the heating rate is 5℃ / min.
[0011] Preferably, the stirring time in step 3) is 18-26 hours; the calcination temperature is 800-950°C; and the calcination time is 1-3 hours.
[0012] Preferably, the flame retardant includes ammonium polyphosphate and triazine charring agents; The mass ratio of ammonium polyphosphate to triazine char-forming agent is 7:3.
[0013] On the other hand, the present invention also provides a method for preparing polyethylene composite flame retardant materials based on high-entropy oxides as described above, specifically adopting the following scheme: The preparation method of polyethylene composite flame retardant material based on high-entropy oxide includes the following steps: 1) Polyethylene and maleic anhydride-grafted polyethylene are mixed and plasticized in an internal mixer; 2) Add flame retardant and spinel-type high entropy oxide to the internal mixer in step 1), and mix at 60 rpm for 10 min to obtain a mixture; 3) Cool the mixture obtained in step 2), perform hot pressing, and then cool to obtain polyethylene composite flame retardant material.
[0014] Preferably, the mixing temperature in step 1) is 150-180℃ and the mixing time is 8-15 minutes; The mixing temperature in step 2) is 150-180℃, and the mixing time is 8-15 minutes.
[0015] Preferably, the temperature of the hot pressing treatment in step 3) is 160-170℃, the pressure is 8-12MPa, and the hot pressing time is 10-20min.
[0016] In summary, the beneficial effects of the present invention are as follows: 1. This invention introduces a six-member spinel-type high-entropy oxide (Fe-Mn-Cu-Co-Ni-Cr) to construct a dual flame-retardant mechanism of gas-phase catalytic oxidation and condensed-phase carbonization protection. The multi-metal solid solution structure of the spinel-type high-entropy oxide provides abundant redox active sites, which can catalyze the conversion of combustible and toxic gases such as carbon monoxide and hydrocarbons produced by polyethylene pyrolysis into harmless carbon dioxide, and can also efficiently promote the formation and stabilization of a dense carbon layer. Combined with flame retardants containing ammonium polyphosphate and triazine charring agents, the thermal stability of the composite material is greatly improved, effectively solving the defects of insufficient carbon layer density and easy cracking and peeling at high temperatures in traditional intumescent flame retardants, and achieving a highly efficient and long-lasting flame-retardant effect.
[0017] 2. The high-entropy oxide of the present invention has excellent smoke suppression and toxicity reduction functions; it significantly reduces the generation of toxic gases such as carbon monoxide through catalytic oxidation, while inhibiting the release of particulate matter in the smoke, and the smoke release rate is significantly reduced compared with traditional flame retardant systems; finally, the composite material exhibits low smoke and low toxicity characteristics under flame action, which can greatly reduce the risk of death and injury to people due to toxic smoke in fire scenarios, and meet the use requirements of high-safety-level scenarios such as buildings, rail transit, and electronic appliances.
[0018] 3. This invention employs a one-pot process involving melamine precursor complexation and dopamine hydrochloride-assisted coating to successfully prepare spinel-type high-entropy oxides with uniform particle size and no elemental segregation. Dopamine hydrochloride, acting as both a surfactant and coating agent, effectively inhibits metal ion aggregation and component segregation, ensuring atomic-level uniform distribution of six metal elements (Fe, Mn, Cu, Co, Ni, and Cr) within the crystal lattice. The spinel-type high-entropy oxide exhibits good compatibility with polyethylene and flame retardants, dispersing uniformly in the composite material. This avoids the catalytic activity loss problem caused by uneven dispersion in traditional multi-metal oxides, fully leveraging the synergistic flame-retardant potential of high-entropy oxides. Attached Figure Description
[0019] Figure 1 XRD patterns of spinel-type high-entropy oxides prepared in embodiments of the present invention; Figure 2 TEM image of the spinel-type high-entropy oxide prepared in an embodiment of the present invention; Figure 3 TEM-mapping image of the spinel-type high-entropy oxide prepared in the embodiments of the present invention; Figure 4 The TGA curves are shown for the polyethylene composite flame-retardant materials prepared in Examples 1-2 and Comparative Examples 1-3 of this invention. Figure 5 The graphs show the heat release rate curves of the polyethylene composite flame retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention. Figure 6 The total heat release curves are shown for the polyethylene composite flame-retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention. Figure 7 The graphs show the smoke release rate curves of the polyethylene composite flame retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention. Detailed Implementation
[0020] The following examples, comparative examples, test cases, and appendices are presented in conjunction with embodiments, comparative examples, test cases, and appendices. Figure 1-6 The present invention will be described in further detail below.
[0021] Example Example 1 The preparation method of polyethylene composite flame retardant material based on high-entropy oxide includes the following steps: S1. Weigh 9g of melamine and 0.5g of ferric chloride hexahydrate and add them to a mixture of 120mL of deionized water and 30mL of hydrochloric acid. Stir magnetically at 115℃ until the solvent evaporates to dryness to obtain a solid metal precursor. Calcinate the solid metal precursor in air at 550℃ for 2h at a heating rate of 2℃ / min to obtain the Fe-based precursor (Fe-PHEOs). Prepare five portions of melamine, each weighing 9g, and prepare 0.5g each of manganese chloride tetrahydrate, copper chloride dihydrate, cobalt chloride hexahydrate, nickel chloride hexahydrate, and chromium chloride hexahydrate. Prepare Mn-based precursors (Mn-PHEOs), Cu-based precursors (Cu-PHEOs), Co-based precursors (Co-PHEOs), Ni-based precursors (Ni-PHEOs), and Cr-based precursors (Cr-PHEOs) according to the above-mentioned method for preparing Fe-based precursors. S2. Take 1 g each of Fe-based, Mn-based, Cu-based, Co-based, Ni-based, and Cr-based precursors, disperse them in 100 mL of hydrochloric acid buffer, add 0.6 g of dopamine hydrochloride, sonicate for 1 hour, and stir at room temperature for 24 hours. Centrifuge, wash, and dry the product, then calcine it in air at 900 °C for 2 hours to obtain a spinel-type high-entropy oxide with uniform composition and stable structure. Among them, the purity of dopamine hydrochloride is over 98%; S3. Weigh out ammonium polyphosphate and triazine charring agent in a mass ratio of 7:3, and mix them to prepare flame retardant; S4. Weigh polyethylene and maleic anhydride-grafted polyethylene and mix and plasticize them in a mixer. Set the mixer temperature to 160℃ and mix for 8-15 minutes. Then add the flame retardant obtained in step S3 and the spinel-type high entropy oxide obtained in step S2. Mix at 160℃ and 60 rpm for 10 minutes to obtain a mixture. The amount of polyethylene added is 69 wt% of the mixture system; the amount of maleic anhydride-grafted polyethylene added is 5 wt% of the mixture system; the amount of spinel-type high-entropy oxide added is 1 wt% of the mixture system; and the amount of flame retardant added is 26 wt% of the mixture system. S5. Cool the mixture obtained in step S4 and perform hot pressing treatment. The hot pressing treatment conditions are 165℃, 10MPa, and 15min. Then cool for 5min to obtain polyethylene composite flame retardant material.
[0022] Example 2 The preparation method of polyethylene composite flame retardant material based on high-entropy oxide differs from that in Example 1 in that, in step S4, the amount of spinel-type high-entropy oxide added is 2 wt% of the mixture system, while the remaining steps are the same as in Example 1.
[0023] Comparative Example Comparative Example 1 The preparation method of the polyethylene composite flame retardant material differs from that of Example 1 in that spinel-type high-entropy oxide is not added in step s4, while the remaining steps are the same as those in Example 1.
[0024] Comparative Example 2 The preparation method of the polyethylene composite flame retardant material differs from that of Comparative Example 1 in that the amount of flame retardant added is 25 wt% of the mixture system, while the remaining steps are the same as those of Comparative Example 1.
[0025] Comparative Example 3 The preparation method of the polyethylene composite flame retardant material differs from that of Comparative Example 1 in that the amount of flame retardant added is 29 wt% of the mixture system, while the remaining steps are the same as those of Comparative Example 1.
[0026] Comparative Example 4 The preparation method of the polyethylene composite flame retardant material differs from Comparative Example 1 in that the amount of flame retardant added is 30 wt% of the mixture system, while the remaining steps are the same as in Comparative Example 1. Test case Test Example 1 Reference Figure 1 The spinel-type high-entropy oxide prepared in Example 1 was examined using X-ray diffraction. Figure 1 It can be seen that the observed diffraction peaks at 18.4°, 30.3°, 35.7°, 37.3°, 43.3°, 53.8°, 57.3°, 63.0°, and 66.2° point to the (111), (220), (311), (222), (400), (422), (511), and (440) planes of the spinel structure (e.g., (PDF#54-0964)). Its crystallization is in the Fd-3m space group. These diffraction peaks prove that the prepared spinel-type high-entropy oxide is indeed a spinel, with no impurity peaks and high purity. The results indicate that the spinel-type high-entropy oxide synthesized in this embodiment of the invention has a typical face-centered cubic spinel structure, with no impurity peaks and high phase purity.
[0027] Test Example 2 Reference Figure 2 The high-entropy oxide prepared in Example 1 was obtained by high-resolution transmission electron microscopy. Figure 2 It can be seen that the prepared high-entropy oxide has a stable size, basically around 50 nm.
[0028] Test Example 3 Reference Figure 3 The high-entropy oxide prepared in Example 1 was obtained by high-resolution transmission electron microscopy. Figure 3It can be seen that Fe, Mn, Cu, Co, Ni, Cr and O elements are uniformly distributed in spinel high-entropy oxide, with no signs of elemental segregation, confirming the successful synthesis.
[0029] Test Example 4 Reference Figure 4 , Figure 4 The TGA curves of the polyethylene composite flame retardant materials prepared in Examples 1-2 and Comparative Examples 1-3 of this invention are shown. Thermogravimetric analysis was used to detect the thermogravimetric curves of the polyethylene composite flame retardant materials based on high-entropy oxides prepared in Examples 1-2 and Comparative Examples 1-3. Specifically, the polyethylene composite flame retardant material prepared in Example 1 corresponds to polyethylene @ 26 wt% flame retardant @ 1 wt% high-entropy oxide; the polyethylene composite flame retardant material prepared in Example 2 corresponds to polyethylene @ 26 wt% flame retardant @ 2 wt% high-entropy oxide; the polyethylene composite flame retardant material prepared in Comparative Example 1 corresponds to polyethylene @ 26 wt% flame retardant; the polyethylene composite flame retardant material prepared in Comparative Example 2 corresponds to polyethylene @ 25 wt% flame retardant; and the polyethylene composite flame retardant material prepared in Comparative Example 3 corresponds to polyethylene @ 29 wt% flame retardant. As shown in the figure, the polyethylene composite flame retardant material based on high-entropy oxide prepared in Example 2 has good thermal stability. The char rate at 700°C after adding 2wt% high-entropy oxide to the polyethylene@26wt% flame retardant sample is 21.2%, which is significantly higher than the char rate of 16.5% of the polyethylene@26wt% flame retardant sample at 700°C.
[0030] Test Example 5 Reference Figure 5 and Figure 6 The polyethylene composite flame retardant materials based on high-entropy oxides prepared in Examples 1-2 and Comparative Examples 1, 2 and 4 were obtained by cone calorimeter testing. Figure 5 The graphs show the heat release rate curves of the polyethylene composite flame retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention. Figure 6The figures show the total heat release curves of the polyethylene composite flame-retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention. Specifically, the polyethylene composite flame-retardant material prepared in Example 1 corresponds to polyethylene @ 26 wt% flame retardant @ 1 wt% high-entropy oxide; the polyethylene composite flame-retardant material prepared in Example 2 corresponds to polyethylene @ 26 wt% flame retardant @ 2 wt% high-entropy oxide; the polyethylene composite flame-retardant material prepared in Comparative Example 1 corresponds to polyethylene @ 26 wt% flame retardant; the polyethylene composite flame-retardant material prepared in Comparative Example 2 corresponds to polyethylene @ 25 wt% flame retardant; and the polyethylene composite flame-retardant material prepared in Comparative Example 4 corresponds to polyethylene @ 30 wt% flame retardant. Compared to the polyethylene composite material without added high-entropy oxide, the heat release rate of the sample prepared in Example 2 with added high-entropy oxide as a catalytic synergist was somewhat suppressed. The total heat release rate of the sample with 2 wt% high-entropy oxide decreased from 59 MJ / m² to that without added high-entropy oxide. 2 Reduced to 41 MJ / m 2 This indicates that the flame retardant properties of the polyethylene composite material based on high-entropy oxides prepared in Example 2 are significantly improved.
[0031] Test Example 6 Reference Figure 7 , Figure 7 The smoke release rate curves of the polyethylene composite flame retardant materials prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 of this invention are shown. The smoke release rate curves of the polyethylene composite flame retardant materials based on high-entropy oxides prepared in Examples 1-2 and Comparative Examples 1, 2, and 4 were obtained using a cone calorimeter. Specifically, the polyethylene composite flame retardant material prepared in Example 1 corresponds to polyethylene @ 26wt% flame retardant @ 1wt% high-entropy oxide; the polyethylene composite flame retardant material prepared in Example 2 corresponds to polyethylene @ 26wt% flame retardant @ 2wt% high-entropy oxide; the polyethylene composite flame retardant material prepared in Comparative Example 1 corresponds to polyethylene @ 26wt% flame retardant; the polyethylene composite flame retardant material prepared in Comparative Example 2 corresponds to polyethylene @ 25wt% flame retardant; and the polyethylene composite flame retardant material prepared in Comparative Example 4 corresponds to polyethylene @ 30wt% flame retardant. Compared to the polyethylene composite material without added high-entropy oxides, the smoke release rate of the material prepared in Example 2, with the addition of high-entropy oxides as a catalytic synergist, was significantly suppressed. The smoke release rate with the addition of 2 wt% high-entropy oxides was much lower than that of the sample without the same proportion. This indicates that the flame retardant properties of the polyethylene composite material based on high-entropy oxides prepared in Example 2 are significantly improved.
[0032] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A polyethylene composite flame-retardant material based on high-entropy oxides, characterized in that, By mass percentage, it includes the following components: Polyethylene 65-69%, maleic anhydride grafted polyethylene 5%, flame retardant 25-29%, and spinel-type high entropy oxide 0.5-3%; The spinel-type high-entropy oxide includes the following elements: Fe, Mn, Cu, Co, Ni, and Cr.
2. The polyethylene composite flame-retardant material based on high-entropy oxides according to claim 1, characterized in that, The preparation method of the spinel-type high-entropy oxide includes the following steps: 1) Prepare ferric chloride hexahydrate, manganese chloride tetrahydrate, copper chloride dihydrate, cobalt chloride hexahydrate, nickel chloride hexahydrate, and chromium chloride hexahydrate. Mix them with melamine at a mass ratio of 1:18 to obtain six parts of the mixture. Dissolve the six parts of the mixture in a mixture of water and hydrochloric acid, and heat and stir until the solvent evaporates to dryness to obtain six parts of solid metal precursors. 2) Take six parts of the solid metal precursor obtained in step 1) and calcine them in an air atmosphere to obtain six parts of metal-based precursor. 3) Disperse the six portions of the metal-based precursor obtained in step 2) in hydrochloric acid buffer, add dopamine hydrochloride, sonicate and stir the reaction, centrifuge, dry and calcine in air to obtain a high-entropy oxide with a spinel structure.
3. The polyethylene composite flame-retardant material based on high-entropy oxides according to claim 2, characterized in that, In step 1), the volume ratio of water to hydrochloric acid in the mixture is 4:1; the heating and stirring temperature is 90-130℃.
4. The polyethylene composite flame-retardant material based on high-entropy oxides according to claim 2, characterized in that, The calcination temperature in step 2) is 500-600℃, the time is 1.5-2h, and the heating rate is 2-5℃ / min.
5. The polyethylene composite flame-retardant material based on high-entropy oxides according to claim 2, characterized in that, The stirring time in step 3) is 18-26 hours; the calcination temperature is 800-950℃ and the calcination time is 1-3 hours.
6. The polyethylene composite flame-retardant material based on high-entropy oxides according to claim 1, characterized in that, The flame retardant includes ammonium polyphosphate and triazine charring agents; The mass ratio of ammonium polyphosphate to triazine char-forming agent is 7:
3.
7. A method for preparing a polyethylene composite flame-retardant material based on high-entropy oxides as described in any one of claims 1-6, characterized in that, Includes the following steps: 1) Polyethylene and maleic anhydride-grafted polyethylene are mixed and plasticized in an internal mixer; 2) Add flame retardant and spinel-type high entropy oxide to the internal mixer in step 1), and mix at 60 rpm for 10 min to obtain a mixture; 3) Cool the mixture obtained in step 2), perform hot pressing, and then cool to obtain polyethylene composite flame retardant material.
8. The method for preparing polyethylene composite flame retardant material based on high-entropy oxides according to claim 7, characterized in that, The mixing temperature in step 1) is 150-180℃, and the mixing time is 8-15 minutes. The mixing temperature in step 2) is 150-180℃, and the mixing time is 8-15 minutes.
9. The method for preparing polyethylene composite flame retardant material based on high-entropy oxides according to claim 7, characterized in that, The hot pressing process in step 3) is carried out at a temperature of 160-170℃, a pressure of 8-12MPa, and a time of 10-20min.