Rare earth hybrid flame retardant as well as preparation method and application thereof

Abstract

The invention discloses a rare earth hybrid flame retardant as well as a preparation method and application thereof, and belongs to the technical fields of inorganic synthesis, flame retardants and high polymer materials. Rare earth hydroxide is successfully loaded on the surface of a flame retardant through an in-situ deposition method to prepare a rare earth hybrid flame retardant, and the rare earth hybrid flame retardant is further dispersed in a high polymer material matrix through melt blending to prepare the flame-retardant high polymer composite material. The hybrid flame retardant prepared by a deposition method can significantly improve the dispersion compatibility of the flame retardant in a high polymer material, and effectively alleviates the mechanical property degradation caused by the filling of the traditional flame retardant; based on the gas phase-condensation phase synergistic effect of the rare earth hydroxide and the flame retardant, the flame retardance and smoke suppression performance of the high polymer material can be synchronously improved. The rare earth hybrid flame retardant can be applied to various high polymer materials such as polyolefin cables, thermoplastic elastomers, polyurethane and the like, can synchronously improve flame retardance, smoke suppression, mechanical performance and comprehensive performance, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical fields of inorganic synthesis, flame retardants, and polymer materials, and particularly relates to a rare earth hybrid flame retardant and its preparation method and application. Background Art

[0002] Polymer materials are widely used in fields such as construction, transportation, and electronics. However, common materials such as polyolefins, polystyrenes, and polyurethanes contain a large number of elements such as C, H, O, and N in their molecular structures. The limiting oxygen index (LOI) is only 17 - 20%, making them highly flammable. When exposed to an open flame or continuous high temperature, they are prone to combustion, generating a large amount of thermal radiation and releasing toxic fumes, which not only causes material failure but also easily triggers fires.

[0003] Adding flame retardants is one of the most effective ways to obtain flame - retardant polymer materials. Although halogen - based flame retardants can achieve high flame - retardant efficiency at low addition amounts, they are gradually phased out due to their environmental toxicity. With the enhancement of sustainable development and global environmental awareness, flame retardants are gradually developing towards the direction of high efficiency, halogen - free, non - toxic, environmentally friendly, and good compatibility with polymer materials. Halogen - free flame retardants are often divided into inorganic metal hydroxides, phosphorus - based, nitrogen - based, phosphorus - nitrogen - based, silicon - based, antimony - based, boron - based, intumescent flame retardants, etc. Among them, inorganic metal hydroxide flame retardants represented by magnesium hydroxide and aluminum hydroxide have advantages such as non - toxicity, smoke suppression, wide resources, good thermal stability, and environmental friendliness. However, their flame - retardant efficiency is low, and a high filling amount (>60 wt.%) is required to achieve good flame - retardant effects, which has a negative impact on the mechanical and processing properties of polymer materials. Ammonium polyphosphate, as an inorganic phosphorus - based flame retardant with high flame - retardant efficiency, non - toxicity, and environmental friendliness, is also limited in its application in flame - retardant polymers due to its high hygroscopicity and poor dispersibility. How to make full use of the inherent advantages of traditional flame retardants and study high - efficiency flame - retardant modification technologies for polymers has become a current topic of great concern and urgent need to be solved.

[0004] Due to the advantages of rare earth metals such as high reactivity, esterification and dehydrogenation catalytic activity, thermal stability, and environmental friendliness, it has promoted the rapid development of rare earth - based flame retardants. Among them, rare earth oxides, rare earth ion - doped compounds, rare earth metal complexes, etc. are mostly involved in polymer flame retardancy. Rare earth hydroxides have the flame - retardant advantages of both rare earth elements (catalytic carbonization) and inorganic hydroxides (cooling and dilution), but they have not been fully studied and reported. However, the application of single rare earth hydroxide as a flame retardant will significantly increase the cost of the flame retardant and polymer composite materials.

[0005] Therefore, the present invention provides a rare earth hybrid flame retardant (REH@FR), which can simultaneously improve the flame retardancy, smoke suppression, and mechanical properties of polymer materials, and is of great significance for promoting the technological progress in the field of flame - retardant materials. Summary of the Invention

[0006] The object of the present invention is to provide a rare earth hybrid flame retardant, its preparation method and application, and to prepare a rare earth hybrid flame retardant REH@FR for use in polymer materials, which plays a flame retardant role in both the gas phase and the condensed phase, and by changing the proportion of the hybrid flame retardant, the effects of the rare earth hybrid flame retardant on the comprehensive properties of polymer materials such as flame retardancy, smoke suppression, thermal stability, and mechanical properties are regulated, so as to solve the problems raised in the background art.

[0007] To achieve the above object, the present invention provides a preparation method of a rare earth hybrid flame retardant, in which rare earth hydroxide is loaded on the surface of the flame retardant by an in-situ deposition method, and the specific steps are as follows: S1. Add a rare earth compound to a solvent, stir and dissolve to obtain solution A, and then add a flame retardant, and ultrasonically stir for 20 - 40 min to obtain suspension B; S2. After heating suspension B to 90 °C, gradually dropwise add ammonia water with a content of 25.0 - 28.0% until the pH value of the solution is 10 - 11 to obtain solution C; S3. Continuously stir and react solution C at 90 °C for 12 - 24 h. After the reaction is completed, cool the mixed solution to room temperature, centrifuge to collect the product, and wash it thoroughly with deionized water and ethanol. The obtained product is dried to constant weight in an oven at 80 - 100 °C to obtain the solid target product REH@FR.

[0008] Preferably, in step S1, the rare earth compound is one of rare earth nitrates and rare earth chlorides, and among them, the rare earth element is one of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0009] Preferably, in step S1, the flame retardant is one or more of magnesium hydroxide, aluminum hydroxide, hydrotalcite, double hydroxide, basic magnesium carbonate, ammonium polyphosphate, piperazine pyrophosphate, melamine phosphate, melamine polyphosphate, melamine cyanurate, pentaerythritol, aluminum hypophosphite, aluminum phosphinate, expandable graphite, zinc borate, graphene, transition metal disulfide, carbon nanotube, halloysite, sepiolite, and kaolin.

[0010] Preferably, in step S1, the molar volume ratio of the rare earth compound to the solvent is (0.02 - 0.04 mol):1 L; among them, the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol is 1:(0 - 3).

[0011] Preferably, the mass ratio of the rare earth hydroxide generated in step S2 to the addition amount of the flame retardant in step S1 is 1:99 - 50:50.

[0012] The present invention also provides a rare earth hybrid flame retardant prepared by the above preparation method.

[0013] The present invention also provides the use of the rare earth hybrid flame retardant in the preparation of flame retardant polymer composite materials.

[0014] Preferably, the preparation method of the flame retardant polymer composite material is: take a polymer material, a rare earth hybrid flame retardant, a compatibilizer and a lubricant, pre-mix them and place them in a torque rheometer, melt blend them at 120-180°C, and press them into a sheet at 130-200°C through a flat vulcanizer to prepare the flame retardant polymer composite material.

[0015] Preferably, based on weight, it includes 30-100 parts of polymer material, 10-60 parts of rare earth hybrid flame retardant, 0-4 parts of compatibilizer and 0-1 part of lubricant.

[0016] Preferably, the polymer material is one of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, thermoplastic elastomer, polyurethane, polystyrene, EPDM rubber, polyamide, polylactic acid, polycarbonate, epoxy resin, styrene-butadiene-styrene block copolymer, polyester, polyphenylene sulfide, polyphenylene oxide, polymethyl methacrylate, and natural rubber; The lubricant is one or more of silicone powder, zinc stearate, paraffin wax, and PE wax; The compatibilizer is one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted ethylene propylene rubber, and maleic anhydride grafted hydrogenated styrene-butadiene-styrene block copolymer.

[0017] Therefore, the rare earth hybrid flame retardant and its preparation method and application provided by the present invention have the following beneficial effects: (1) The present invention innovatively adopts an in-situ deposition method to successfully load rare earth hydroxides on the surface of flame retardants, thereby constructing a REH@FR rare earth hybrid flame retardant to achieve condensed phase-gas phase dual-phase synergistic flame retardancy. In the condensed phase, the rare earth oxides obtained by the decomposition of rare earth components can act as catalysts to promote the dehydrogenation and cross-linking reactions of the polymer, thereby forming a more continuous and dense carbon layer, which effectively blocks the transfer of heat and combustible substances, can significantly reduce smoke density and improve flame retardant properties. In the gas phase, the rare earth hydroxide can release water vapor when it is thermally decomposed, which can not only dilute the concentration of combustible gases and slow down the rate of combustion reactions, but also absorb heat from the combustion zone, play a cooling role, and curb the intensification of combustion. By adjusting the ratio of rare earth hybrid flame retardants to change the interaction between rare earth hydroxides and flame retardants, and then optimize the flame retardant synergistic effect of the two in the condensed phase and gas phase, this has important practical significance for improving the safety of polymer materials in fire scenarios.

[0018] (2) The rare earth hybrid flame retardant proposed by the present invention can directly regulate its own particle size distribution and surface morphology by adjusting the hybridization ratio, so as to improve its dispersibility in the polymer matrix. This characteristic is beneficial to slowing down the adverse effects of flame retardant filling on the mechanical properties of polymer materials, thereby improving the comprehensive properties of polymer materials. It promotes the wide application of flame-retardant polymer composites in fields with high requirements for mechanical properties such as automobile manufacturing and building decoration.

[0019] (3) The preparation process of the rare earth hybrid flame retardant involved in the present invention is relatively simple. By using the one-step precipitation method, the hybridization of rare earth hydroxide and flame retardant can be achieved, and the whole process only needs to be carried out under normal pressure environment and low temperature conditions of 90 °C. This method is simple and easy to operate, easy to control, greatly reducing the energy consumption and equipment cost in the production process. Moreover, the entire process flow is green and environmentally friendly, without the participation of toxic solvents, improving the environmental protection performance.

[0020] The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings

[0021] Figure 1 It is the XRD pattern of the 1#-3# hybrid flame retardants prepared in Examples 1-3 of the present invention; Figure 2 It is the scanning electron microscope image of the 1#-3# hybrid flame retardants prepared in Examples 1-3 of the present invention; among them, a is MH; b is 3% LaH@MH (1#); c is 5% LaH@MH (2#); d is 10% LaH@MH (3#); Figure 3 It is the XRD pattern of the 4# hybrid flame retardant prepared in Example 4 of the present invention; Figure 4 It is the scanning electron microscope image of the 4# hybrid flame retardant prepared in Example 4 of the present invention; among them, a is MH; b is 5% NdH@MH (4#); Figure 5 It is the XRD pattern of the 5# hybrid flame retardant prepared in Example 5 of the present invention; Figure 6 It is the scanning electron microscope image of the 5# hybrid flame retardant prepared in Example 5 of the present invention; among them, a is ATH; b is 5% SmH@ATH (5#); Figure 7 It is the XRD pattern of the 6#-7# hybrid flame retardants prepared in Examples 6-7 of the present invention; Figure 8 It is the scanning electron microscope image of the 6#-7# hybrid flame retardants prepared in Examples 6-7 of the present invention; among them, a is PAPP; b is 5% LaH@PAPP (6#); c is APP; d is the scanning electron microscope image of 5% LaH@APP (7#). Detailed implementation manners

[0022] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application and belong to the protection scope of the present invention.

[0023] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The term "embodiment" appearing in various positions in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0024] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the technical field to which this application belongs; the use of the relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0025] Unless otherwise specified in the present invention, the reagents, instruments, equipment, and performance testing methods used are all the reagents, instruments, equipment, and methods commonly used by those skilled in the art in this field.

[0026] Example 1 This example provides a preparation method of a rare earth hybrid flame retardant, which specifically includes the following steps: (1) Add 28 mmol (10.40 g) of lanthanum chloride heptahydrate to 700 ml of deionized water, stir and dissolve to obtain solution A, and then add 171.9 g of magnesium hydroxide (so that the mass ratio of lanthanum hydroxide to magnesium hydroxide (MH) is 3:97), and ultrasonically stir for 30 min to obtain suspension B.

[0027] (2) After heating suspension B to 90 °C, dropwise add ammonia water with a content of 25.0 - 28.0% until the pH value of the solution is 11 to obtain solution C.

[0028] (3) Keep the solution C stirred at a constant temperature of 90 °C for 24 h. After the reaction, cool the mixture to room temperature, centrifuge to separate and collect the precipitate, and wash it thoroughly with deionized water and ethanol. Finally, place the obtained product in an oven and dry it at 80 °C to a constant weight to obtain the 1# hybrid flame retardant, denoted as 3% LaH@MH.

[0029] Example 2 This example provides a preparation method of a rare earth hybrid flame retardant. The difference from Example 1 is that in this example, 101.03 g of magnesium hydroxide is added to solution A (so that the mass ratio of lanthanum hydroxide to magnesium hydroxide is 5:95), and finally the 2# hybrid flame retardant is obtained, denoted as 5% LaH@MH.

[0030] Example 3 This example provides a preparation method of a rare earth hybrid flame retardant. The difference from Example 1 is that in this example, 47.85 g of magnesium hydroxide is added to solution A (so that the mass ratio of lanthanum hydroxide to magnesium hydroxide is 10:90), and finally the 3# hybrid flame retardant is obtained, denoted as 10% LaH@MH.

[0031] From Figure 1 the X-ray diffraction (XRD) pattern analysis, it can be seen that the diffraction peaks of the 1#-3# hybrid flame retardants all contain the characteristic diffraction peaks of La(OH)3 (JCPDS no.36-1481) and Mg(OH)2 (JCPDS no. 86-0441), indicating that the 1-3# hybrid flame retardants all contain these two substances. Figure 2 is the scanning electron microscope image of the 1#-3# hybrid flame retardants. It can be seen from the figure that pure magnesium hydroxide is a smooth sheet on the surface, while nanoparticles appear on the surface of the sheets of the 1#-3# hybrid flame retardants. Moreover, as the loading amount of lanthanum hydroxide increases, the size and number of the nanoparticles increase, indicating that lanthanum hydroxide is successfully loaded onto the surface of magnesium hydroxide, and the 1#-3# hybrid flame retardants are prepared.

[0032] Example 4 This example provides a preparation method of a rare earth hybrid flame retardant. The difference from Example 1 is that in this example, 28 mmol (10.04 g) of neodymium chloride hexahydrate is added to 700 ml of deionized water and stirred to dissolve to obtain solution A, and then 103.87 g of magnesium hydroxide is added (so that the mass ratio of neodymium hydroxide to magnesium hydroxide is 5:95), and finally the 4# hybrid flame retardant is obtained, denoted as 5% NdH@MH.

[0033] From Figure 3From the XRD pattern analysis, it can be seen that the diffraction peaks of the 4# hybrid flame retardant contain the characteristic diffraction peaks of Nd(OH)3 (JCPDS no.70-0214) and Mg(OH)2 (JCPDS no. 86-0441), indicating that the 4# hybrid flame retardant contains both of the above two substances. Figure 4 Figure Figure 4 is the scanning electron micrograph of the 4# hybrid flame retardant. From the figure, it can be seen that pure magnesium hydroxide is a relatively smooth sheet, while there are many nanoparticles on the surface of the sheet of the 4# hybrid flame retardant, indicating that neodymium hydroxide is successfully loaded onto the surface of magnesium hydroxide, and the 4# hybrid flame retardant is prepared.

[0034] Example 5 This example provides a preparation method of a rare earth hybrid flame retardant. The difference from Example 1 is only that in this example, 28 mmol (10.22 g) of samarium chloride heptahydrate is added to 700 ml of deionized water and stirred to dissolve to obtain solution A, and then 134.27 g of aluminum hydroxide is added (so that the mass ratio of samarium hydroxide to aluminum hydroxide is 5:95), and finally the 5# hybrid flame retardant is obtained, denoted as 5%SmH@ATH.

[0035] From Figure 5 From the XRD pattern analysis, it can be seen that the diffraction peaks of the 5# hybrid flame retardant contain the characteristic diffraction peaks of Sm(OH)3 (JCPDS no. 83-2036) and Al(OH)3 (JCPDS no. 33-0018), indicating that the 5# hybrid flame retardant contains both of the above two substances. Figure 6 Figure Figure 6 is the scanning electron micrograph of the 5# hybrid flame retardant. From the figure, it can be seen that pure aluminum hydroxide is a relatively smooth sheet, while there are many nanoparticles on the surface of the sheet of the 5# hybrid flame retardant, indicating that samarium hydroxide is successfully loaded onto the surface of aluminum hydroxide, and the 5# hybrid flame retardant is prepared.

[0036] Example 6 This example provides a preparation method of a rare earth hybrid flame retardant, which specifically includes the following steps: (1) Add 16 mmol (6.93 g) of lanthanum nitrate hexahydrate to an ethanol-water (volume ratio 3:1) mixed solvent with a total volume of 800 ml, stir to dissolve to obtain solution A, and then add 57.73 g of piperazine pyrophosphate (so that the mass ratio of lanthanum hydroxide to piperazine pyrophosphate (PAPP) is 5:95), and ultrasonically stir for 30 min to obtain suspension B; (2) After heating the suspension B to 90 °C, gradually dropwise add ammonia water with a content of 25.0 - 28.0% until the pH value of the solution is about 10 to obtain solution C; (3) Keep the solution C stirred at a constant temperature of 90 °C for 12 h. After the reaction, cool the mixture to room temperature, centrifuge to collect the precipitate, and wash it thoroughly with ethanol. Finally, place the obtained product in an oven and dry it at 80 °C to a constant weight to obtain the 6# hybrid flame retardant, denoted as 5% LaH@PAPP.

[0037] Example 7 This example provides a preparation method of a rare earth hybrid flame retardant. The difference from Example 6 is that in this example, 57.73 g of ammonium polyphosphate is added to solution A (so that the mass ratio of lanthanum hydroxide to ammonium polyphosphate (APP) is 5:95), and finally the 7# hybrid flame retardant is obtained, denoted as 5% LaH@APP.

[0038] From Figure 7 the XRD pattern analysis, it can be seen that the diffraction peaks of the 6#-7# hybrid flame retardants contain La(OH)3 (JCPDS no. 36-1481) and the characteristic diffraction peaks of the corresponding original flame retardants PAPP or APP, indicating that the 6#-7# hybrid flame retardants contain both of the above two substances. Figure 8 is the scanning electron micrograph of the 6-7# hybrid flame retardant. It can be seen from the figure that both PAPP and APP are smooth-surfaced blocks, while the surfaces of the corresponding 6#-7# hybrid flame retardants become rough after loading lanthanum hydroxide and are distributed with many nanoparticles, indicating that lanthanum hydroxide is successfully loaded onto the surfaces of PAPP and APP, and the 6#-7# hybrid flame retardants are prepared.

[0039] To verify the performance of the rare earth hybrid flame retardant REH@FR prepared in the above examples, it was added to the polymer material to explore the changes in its flame retardancy, smoke suppression, and mechanical properties. The following application examples are methods for preparing flame-retardant polymer composites using rare earth hybrid flame retardants.

[0040] Application Example 1 Weigh 36 parts of EVA, 60 parts of the 1# hybrid flame retardant (3% LaH@MH), 4 parts of the compatibilizer maleic anhydride grafted ethylene-vinyl acetate copolymer, and 0.3 parts of the lubricant silicone powder according to the ratio. Premix the above components according to the ratio and place them in a torque rheometer to melt and blend at 130 °C, and press them into plates at 160 °C through a flat vulcanizer to prepare the flame-retardant polymer composite.

[0041] Application Example 2 The difference from Application Example 1 is that Application Example 2 uses the 2# hybrid flame retardant (5% LaH@MH).

[0042] Application Example 3 The difference from Application Example 1 is that Application Example 3 uses the 3# hybrid flame retardant (10% LaH@MH).

[0043] Application Example 4 The difference from Application Example 1 is that Application Example 4 uses the 4# hybrid flame retardant (5% NdH@MH).

[0044] Application Example 5 The difference from Application Example 1 is that Application Example 5 uses the 5# hybrid flame retardant (5% SmH@ATH).

[0045] To further verify the performance of the 1-5# rare earth hybrid flame retardants, pure resin (Comparative Example 1), unmodified magnesium hydroxide (Comparative Example 2), and aluminum hydroxide (Comparative Example 3) were used to replace the rare earth hybrid flame retardants in equal amounts for the flame retardancy of EVA. And a comparative formula as shown in Table 1 was designed, and its limiting oxygen index, vertical burning, cone calorimetry, smoke density, and mechanical properties were tested. Table 1 is the formula and main performance parameters of the flame retardant EVA composite material.

[0046] Table 1 Formula and Main Performance Parameters of Flame Retardant EVA Composite Material ; In the table, LOI: Limiting Oxygen Index; UL-94: Vertical Burning Flame Retardant Grade; pHRR: Peak Heat Release Rate; THR: Total Heat Release; pCOPR: Peak CO Release Rate; PCO2PR: Peak CO2 Release Rate; Ds-max: Maximum Smoke Density.

[0047] Application Example 6 Weigh 68 parts of thermoplastic elastomer TPE and 32 parts of the 6# hybrid flame retardant (5% LaH@PAPP) by proportion. After premixing each component in the above proportion, place it in a torque rheometer and melt-blend at 180 °C, and press it into a sheet at 195 °C through a flat vulcanizer to prepare a flame retardant polymer composite material.

[0048] To further verify the performance of the 6# hybrid flame retardant (5% LaH@PAPP), it was used to replace pure resin (Comparative Example 4) and unmodified PAPP in equal amounts for the flame retardancy of TPE (Comparative Example 5), and a comparative formula as shown in Table 2 was designed, and its limiting oxygen index, vertical burning, cone calorimetry, smoke density, and mechanical properties were tested. Table 2 is the formula and main performance parameters of the flame retardant TPE composite material.

[0049] Table 2 Formula and Main Performance Parameters of Flame Retardant TPE Composite Material ; In the table, LOI: Limiting Oxygen Index; UL-94: Vertical Burning Flame Retardant Rating; pHRR: Peak Heat Release Rate; THR: Total Heat Release; pCOPR: Peak CO Release Rate; PCO2PR: Peak CO2 Release Rate; Ds-max: Maximum Smoke Density.

[0050] Application Example 7 Weigh 93.5 parts of polyurethane TPU and 6.5 parts of 7# hybrid flame retardant (5% LaH@APP) proportionally. Premix each component according to the above proportion and then melt blend and pelletize through a twin-screw extruder at 180 °C, and press it into a sheet at 195 °C through an injection molding machine to prepare the flame-retardant polymer composite material.

[0051] To further verify the performance of 7# hybrid flame retardant (5% LaH@APP), it was applied to the flame retardancy of TPU by replacing it with pure resin (Comparative Example 6) and unmodified APP in equal amounts (Comparative Example 7). A comparative formula as shown in Table 3 was designed, and its limiting oxygen index, vertical burning, cone calorimetry, smoke density and mechanical properties were tested. Table 3 is the formula and main performance parameters of the flame-retardant TPU composite material.

[0052] Table 3 Formula and Main Performance Parameters of Flame-Retardant TPU Composite Material ; In the table, LOI: Limiting Oxygen Index; UL-94: Vertical Burning Flame Retardant Rating; pHRR: Peak Heat Release Rate; THR: Total Heat Release; pCOPR: Peak CO Release Rate; PCO2PR: Peak CO2 Release Rate; Ds-max: Maximum Smoke Density.

[0053] Based on the above experimental results, the following conclusions are drawn: (1) All the prepared 1-7# rare earth hybrid flame retardants can make the polymer composite material pass the UL-94 V-0 level, and the limiting oxygen index is higher than that of the pure polymer and the polymer composite material filled with unmodified flame retardant, indicating that it has significant advantages in suppressing the combustion of polymer materials and improving the fire safety of materials.

[0054] (2) For the flame-retardant polymer composite material prepared from rare earth hybrid flame retardants, its thermal and non-thermal hazards are reduced compared with those of the pure polymer and the polymer composite material filled with unmodified flame retardant, indicating that rare earth hybrid flame retardants have both good flame retardancy and smoke suppression performance.

[0055] (3) The compatibility between rare earth hybrid flame retardants and polymer substrates is improved. Therefore, the tensile strength and elongation at break of the prepared flame-retardant polymer composite material are better than those of the polymer composite material filled with unmodified flame retardant, effectively alleviating the negative impact of flame retardant filling on the mechanical and comprehensive properties of the polymer matrix.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements do not enable the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a rare earth hybrid flame retardant, characterized in that, The rare earth hydroxide is loaded on the surface of the flame retardant by an in-situ deposition method, and the specific steps are as follows: S1. Add a rare earth compound to a solvent, stir and dissolve to obtain solution A, then add a flame retardant, and ultrasonically stir for 20 - 40 min to obtain suspension B; S2. After heating suspension B to 90 °C, dropwise add ammonia water with a content of 25.0 - 28.0% until the pH value of the solution is 10 - 11 to obtain solution C; S3. Continuously stir and react solution C at 90 °C for 12 - 24 h. After the reaction is completed, cool the mixed solution to room temperature, centrifuge to collect the product, and wash it thoroughly with deionized water and ethanol. The obtained product is dried in an oven at 80 - 100 °C to constant weight to obtain the solid target product REH@FR.

2. The preparation method of a rare earth hybrid flame retardant according to claim 1, characterized in that: In step S1, the rare earth compound is one of rare earth nitrates and rare earth chlorides, and among them, the rare earth element is one of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

3. The preparation method of a rare earth hybrid flame retardant according to claim 1, characterized in that: In step S1, the flame retardant is one or more of magnesium hydroxide, aluminum hydroxide, hydrotalcite, double hydroxide, basic magnesium carbonate, ammonium polyphosphate, piperazine pyrophosphate, melamine phosphate, melamine polyphosphate, melamine cyanurate, pentaerythritol, aluminum hypophosphite, aluminum phosphinate, expandable graphite, zinc borate, graphene, transition metal disulfide, carbon nanotube, halloysite, sepiolite, and kaolin.

4. The preparation method of a rare earth hybrid flame retardant according to claim 1, characterized in that: In step S1, the molar volume ratio of the rare earth compound to the solvent is (0.02 - 0.04 mol):1 L; among them, the solvent is a mixed solvent of water and ethanol, and the volume ratio of water to ethanol is 1:(0 - 3).

5. The preparation method of a rare earth hybrid flame retardant according to claim 1, characterized in that: The mass ratio of the rare earth hydroxide generated in step S2 to the addition amount of the flame retardant in step S1 is 1:99 - 50:

50.

6. A rare earth hybrid flame retardant, characterized in that: The rare earth hybrid flame retardant is prepared by the preparation method according to any one of claims 1 - 5.

7. The application of a rare earth hybrid flame retardant as described in claim 6, characterized in that: The rare earth hybrid flame retardant is applied to the preparation of a flame-retardant polymer composite material.

8. The application of a rare earth hybrid flame retardant according to claim 7, characterized in that, The preparation method of the flame-retardant polymer composite material is as follows: Take a polymer material, a rare earth hybrid flame retardant, a compatibilizer, and a lubricant, premix them and place them in a torque rheometer, and perform melt blending at 120 - 180 °C, and press them into a plate at 130 - 200 °C by a flat vulcanizer to make a flame-retardant polymer composite material.

9. Use of a rare earth hybrid flame retardant according to claim 8, characterized in that: By weight, it includes 30 - 100 parts of a polymer material, 10 - 60 parts of a rare earth hybrid flame retardant, 0 - 4 parts of a compatibilizer, and 0 - 1 part of a lubricant.

10. Use of a rare earth hybrid flame retardant according to claim 8, characterized in that: The polymer material is one of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, thermoplastic elastomer, polyurethane, polystyrene, ethylene propylene diene monomer rubber, polyamide, polylactic acid, polycarbonate, epoxy resin, styrene-butadiene-styrene block copolymer, polyester, polyphenylene sulfide, polyphenylene ether, polymethyl methacrylate, and natural rubber; The lubricant is one or more of silicone powder, zinc stearate, paraffin wax, and PE wax; The compatibilizer is one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene-vinyl acetate copolymer, maleic anhydride grafted ethylene propylene diene monomer rubber, and maleic anhydride grafted hydrogenated styrene-butadiene-styrene block copolymer.

Images