Magnesium hydroxide / attapulgite flame retardant, preparation method thereof and flame-retardant material

Abstract

The invention belongs to the technical field of flame-retardant additive materials, and particularly relates to a magnesium hydroxide / attapulgite flame retardant, a preparation method thereof and a flame-retardant material. The preparation method comprises the following steps: by taking attapulgite as a carrier, reacting inorganic magnesium salt with attapulgite at 80-200 DEG C in an alkali solution system, so that magnesium hydroxide is subjected to in-situ nucleation growth on the surface of the attapulgite, and the magnesium hydroxide / attapulgite flame retardant is obtained. According to the preparation method, the agglomeration phenomenon of magnesium hydroxide is effectively avoided by regulating and controlling the reaction environment, uniform loading of magnesium hydroxide on the surface of attapulgite is realized, and the performance of the magnesium hydroxide / attapulgite flame retardant is improved. The preparation method disclosed by the invention is simple, convenient to operate, low in production cost, green, environment-friendly and convenient for large-scale production. The limit oxygen index value of the flame-retardant material prepared from the magnesium hydroxide / attapulgite flame retardant is 28.4%-29.3%, the limit oxygen index value is remarkably increased, and the flame-retardant efficiency is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardant additive materials, and particularly relates to a magnesium hydroxide / palygorskite flame retardant, a preparation method thereof, and a flame retardant material. Background Art

[0002] With the dual demands for the flame retardant safety and environmental friendliness of materials, the development of halogen-free flame retardants has become a research hotspot in the field of polymer materials. Magnesium hydroxide is regarded as an important candidate to replace halogen-based flame retardants due to its high decomposition temperature, excellent smoke suppression performance, good environmental compatibility, etc. However, traditional magnesium hydroxide flame retardants have significant limitations in practical applications: to achieve an ideal flame retardant effect, a high filling amount of 50% - 60% needs to be added, which not only greatly reduces the mechanical properties of the matrix material but also deteriorates the processing fluidity. This is because the two-dimensional sheet structure of magnesium hydroxide is prone to disordered stacking in the polymer matrix, and its surface polarity is relatively high, resulting in poor interfacial compatibility with the organic matrix, making it difficult to improve the flame retardant efficiency.

[0003] To improve the flame retardant efficiency of magnesium hydroxide, existing technologies mainly improve the dispersion and flame retardant efficiency of magnesium hydroxide through surface modification, nanosizing, and compounding with synergistic agents. Among them, the development of mineral synergistic agents has attracted much attention, and the total addition amount of flame retardants can be significantly reduced through the synergistic effect of multiple components. Palygorskite, as a natural nano-fibrous magnesium-aluminum silicate clay, exhibits unique flame retardant potential. The crystal structure of palygorskite contains abundant nano-pores, and adsorbed water is contained in the pores. During the initial stage of combustion, it will escape from the pores, absorb heat, and prevent the combustion from proceeding; in the case of continuous combustion, the structure of palygorskite is destroyed, losing the zeolite water and crystal water in its structure, which can isolate the combustion-supporting gas and absorb heat, thus achieving the flame retardant effect. And palygorskite does not produce toxic gases and smoke during the combustion process and can be used as a green and environmentally friendly flame retardant.

[0004] However, existing magnesium hydroxide / palygorskite composite systems mostly adopt a simple physical blending process. Mechanical mixing is difficult to achieve uniform loading of magnesium hydroxide on the surface of palygorskite, resulting in weak interfacial binding force between the two phases and easy phase separation at high temperatures; in addition, the synthesized magnesium hydroxide is prone to form micron-sized aggregates, with a low specific surface area and insufficient active sites, leading to limited improvement in flame retardant efficiency. Summary of the Invention

[0005] In order to solve the technical problems in the above-mentioned existing technologies that it is difficult to achieve uniform loading of magnesium hydroxide on the surface of palygorskite in the magnesium hydroxide / palygorskite composite system, and the synthesized magnesium hydroxide is prone to form micron-sized aggregates, resulting in limited improvement in flame retardant efficiency, the present invention provides a magnesium hydroxide / palygorskite flame retardant, a preparation method thereof, and an application.

[0006] In the present invention, attapulgite is used as a carrier. In a solvent system, an inorganic magnesium salt and attapulgite are mixed and then placed in a closed container for reaction. By controlling the reaction temperature, magnesium hydroxide grows uniformly on the surface of attapulgite. At the same time, under the high-pressure environment formed by high temperature and a closed environment, the crystal growth of magnesium hydroxide proceeds smoothly, and the internal stress is effectively released, resulting in a significant reduction in internal defects of the crystal and a more complete and ordered crystal structure. The uniform loading of magnesium hydroxide on the surface of attapulgite is achieved, avoiding the irregular morphology and agglomeration of magnesium hydroxide.

[0007] When the magnesium hydroxide / attapulgite flame retardant is used in the preparation of a composite material, the uniformity and stability of the composite material are improved.

[0008] The first object of the present invention is to provide a preparation method of a magnesium hydroxide / attapulgite flame retardant, comprising the following steps:

[0009] Using attapulgite as a carrier, in an alkaline solution system, attapulgite and an inorganic magnesium salt are reacted at 80°C to 200°C, enabling the in-situ nucleation and growth of magnesium hydroxide on the surface of attapulgite to obtain the magnesium hydroxide / attapulgite flame retardant.

[0010] It should be noted that attapulgite can provide a large specific surface area and pore structure, enhancing the mechanical stability of the composite material. At the same time, attapulgite belongs to layered silicate minerals, and its structure contains a large number of silicon-oxygen tetrahedrons and magnesium-oxygen octahedrons, forming a heat-insulating layer at high temperatures and having a certain flame retardancy.

[0011] In the present invention, attapulgite is used as the substrate for the growth of magnesium hydroxide. Through the interaction between the surface hydroxyl groups of attapulgite and the Mg(OH)2 precursor, magnesium hydroxide nanoparticles are uniformly deposited and grown along the surface of attapulgite, forming a uniformly dispersed composite structure, which improves the uniformity and stability of the composite material. Through this composite structure, a physical barrier is formed to delay the thermal decomposition and release of combustibles during combustion, thereby improving the flame retardancy.

[0012] Preferably, the mass ratio of the inorganic magnesium salt to attapulgite is 1:1 to 10.

[0013] Preferably, the reaction temperature is 80°C to 200°C, and the reaction time is 6h to 24h. This is because the reaction temperature and reaction time affect the crystal morphology and size of magnesium hydroxide. A higher temperature promotes crystal growth and forms a more stable structure, but too high a temperature results in too large particles, affecting the dispersibility.

[0014] Preferably, the specific preparation method of the magnesium hydroxide / attapulgite flame retardant is as follows:

[0015] Mix attapulgite, an inorganic magnesium salt, and an alkaline solution, and stir at room temperature to obtain a precursor solution.

[0016] The precursor solution is reacted at 80 °C to 200 °C to cause in-situ nucleation and growth of magnesium hydroxide on the surface of attapulgite, obtaining a magnesium hydroxide / attapulgite flame retardant.

[0017] Preferably, the pH value of the precursor solution is 8 to 14.

[0018] Preferably, the stirring time is 1 h to 3 h.

[0019] Preferably, the alkali solution is ammonia water, sodium hydroxide solution or potassium hydroxide solution.

[0020] Preferably, the dosage ratio of the inorganic magnesium salt to the alkali solution is 1 g: 100 mL to 1000 mL; the molar concentration of the alkali solution is 0.1 mol / L to 1 mol / L.

[0021] Preferably, the attapulgite is obtained by purifying attapulgite ore; the specific method of the purification treatment is as follows:

[0022] The attapulgite ore is crushed and coarsely screened to obtain coarsely purified attapulgite; the coarsely purified attapulgite and an oxidizing acid are mixed for acidification treatment to obtain attapulgite.

[0023] After the attapulgite ore is acidified, on the one hand, impurities in the attapulgite are removed, and on the other hand, the surface of the attapulgite is activated to increase the number of surface hydroxyl groups, improve its hydrophilicity and reactivity, and facilitate the subsequent loading of Mg(OH)2.

[0024] Preferably, the dosage ratio of the attapulgite to the oxidizing acid is 1 g: 100 mL to 1000 mL.

[0025] Preferably, the oxidizing acid is concentrated sulfuric acid, concentrated nitric acid, dilute nitric acid, nitrous acid or halogen-containing oxyacid; the halogen-containing oxyacid is hypochlorous acid, chloric acid or perchloric acid.

[0026] The second object of the present invention is to provide a magnesium hydroxide / attapulgite flame retardant prepared by the preparation method of the above magnesium hydroxide / attapulgite flame retardant.

[0027] The third object of the present invention is to provide the application of the above magnesium hydroxide / attapulgite flame retardant in the preparation of flame retardant materials.

[0028] Preferably, the preparation method of the flame retardant material is as follows:

[0029] After the magnesium hydroxide / attapulgite flame retardant and the matrix resin are mixed, they are heated at 70 °C to 100 °C to disperse the magnesium hydroxide / attapulgite flame retardant in the matrix resin, a curing agent is added for stirring, and after pouring and curing, a flame retardant material is obtained.

[0030] Preferably, the mass ratio of the magnesium hydroxide / palygorskite flame retardant to the matrix resin is 2.0-3.5:10; the mass ratio of the matrix resin to the curing agent is 10:2.6-3.5.

[0031] Preferably, the matrix resin is epoxy resin or phenolic resin; the curing agent is 4,4'-diaminodiphenyl sulfone.

[0032] Preferably, the heating time is 30 min to 120 min.

[0033] Preferably, the stirring time is 0.5 h to 4 h.

[0034] Preferably, the curing temperature is 160 °C, and the curing time is 30 min to 120 min.

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] 1. In the present invention, palygorskite is used as a carrier. Under a solvent system and alkaline conditions, an inorganic magnesium salt and palygorskite are mixed and then placed in a closed container for reaction. By regulating the reaction environment, magnesium hydroxide is in-situ uniformly nucleated and grown on the surface of palygorskite; meanwhile, under the high-pressure environment formed by high temperature and a closed environment, the growth of magnesium hydroxide crystals is promoted, and the internal stress is effectively released, so that a large number of defects inside the crystals are reduced, and the crystal structure becomes more complete and ordered. The agglomeration phenomenon is effectively avoided, the uniform loading of magnesium hydroxide on the surface of palygorskite is realized, and the performance of the magnesium hydroxide / palygorskite flame retardant is improved.

[0037] 2. Compared with the flame retardants prepared by the prior art, the limiting oxygen index value of the flame retardant material containing the magnesium hydroxide / palygorskite flame retardant prepared by the present invention is 28.4%-29.3%, and the limiting oxygen index value is significantly improved, and the flame retardant efficiency is higher.

[0038] 3. Under the high-pressure environment formed by high temperature and a closed environment in the present invention, magnesium hydroxide and palygorskite are tightly combined to form a complex with a stable structure, thereby improving its dispersibility and compatibility in matrixes such as epoxy resin, which helps to improve the comprehensive performance of the composite material.

[0039] 4. The preparation method of the present invention is simple, easy to operate, low in production cost, environmentally friendly and convenient for large-scale production. Description of the Drawings

[0040] Figure 1 SEM diagram of the magnesium hydroxide / palygorskite flame retardant prepared in Comparative Example 1.

[0041] Figure 2 SEM diagram of the magnesium hydroxide / palygorskite flame retardant prepared in Example 1.

[0042] Figure 3 The limiting oxygen indices of the flame retardant materials prepared in Comparative Example 1, the flame retardant materials prepared in Examples 1 to 6, and epoxy resin; among them, 1 is epoxy resin, 2 is the flame retardant material prepared in Example 1, 2 is the flame retardant material prepared in Example 1, 3 is the flame retardant material prepared in Example 2, 4 is the flame retardant material prepared in Example 3, 5 is the flame retardant material prepared in Example 4, 6 is the flame retardant material prepared in Example 5, 7 is the flame retardant material prepared in Example 6, and 8 is the flame retardant material prepared in Comparative Example 1. Detailed implementation manners

[0043] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific examples and drawings.

[0044] In the description of the present invention, unless otherwise specified, the reagents used are commercially available, and the methods used are conventional techniques in the art.

[0045] Example 1

[0046] A preparation method of a magnesium hydroxide / palygorskite flame retardant, comprising the following steps:

[0047] Crush and roughly screen palygorskite ore, with the mesh number of the rough screening being 400 meshes, to obtain roughly purified palygorskite.

[0048] According to the dosage ratio of roughly purified palygorskite to concentrated sulfuric acid solution of 1 g:1000 mL, wherein the mass concentration of the concentrated sulfuric acid solution is 20%, add the roughly purified palygorskite to the concentrated sulfuric acid solution, and stir at room temperature for 1 h to obtain modified palygorskite.

[0049] Wash the modified palygorskite with deionized water and then dry it to obtain purified palygorskite.

[0050] Mix 1 g of MgCl₂·6H₂O, 100 mL of ammonia water solution with a mass concentration of 13%, and 1 g of purified palygorskite, and stir at room temperature for 1 h to obtain a precursor solution.

[0051] Place the precursor solution in a reaction kettle, react at 80 °C for 24 h, naturally cool, then wash repeatedly with deionized water and ethanol, and dry in a constant temperature blast drying oven at 60 °C for 12 h to obtain the magnesium hydroxide / palygorskite flame retardant.

[0052] Example 2

[0053] A preparation method of a magnesium hydroxide / palygorskite flame retardant, comprising the following steps:

[0054] The attapulgite ore is crushed and roughly screened with a mesh size of 400 meshes to obtain roughly purified attapulgite.

[0055] According to the dosage ratio of attapulgite to concentrated nitric acid solution of 1 g: 500 mL, where the concentration of the concentrated nitric acid solution is 0.5 mol / L, the roughly purified attapulgite is added to the concentrated nitric acid solution and stirred at room temperature for 1 h to obtain modified attapulgite.

[0056] The modified attapulgite is washed with deionized water and then dried to obtain purified attapulgite.

[0057] 1 g of MgSO4·6H2O, 500 mL of sodium hydroxide solution with a concentration of 0.5 mol / L and 5 g of purified attapulgite are mixed and stirred at room temperature for 1 h to obtain a precursor solution.

[0058] The precursor solution is placed in a reaction kettle and reacted at 100 °C for 20 h. After natural cooling, it is repeatedly washed with deionized water and ethanol and dried in a constant temperature air blast drying oven at 80 °C for 4 h to obtain magnesium hydroxide / attapulgite flame retardant.

[0059] Example 3

[0060] A preparation method of magnesium hydroxide / attapulgite flame retardant, comprising the following steps:

[0061] The attapulgite ore is crushed and roughly screened with a mesh size of 400 meshes to obtain roughly purified attapulgite.

[0062] According to the dosage ratio of attapulgite to dilute nitric acid solution of 1 g: 300 mL, where the concentration of the dilute nitric acid solution is 1 mol / L; the roughly purified attapulgite is added to the dilute nitric acid solution and stirred at room temperature for 1 h to obtain modified attapulgite.

[0063] The modified attapulgite is washed with deionized water and then dried to obtain purified attapulgite.

[0064] 1 g of MgCl2·6H2O, 1000 mL of potassium hydroxide solution with a concentration of 0.1 mol / L and 10 g of purified attapulgite are mixed and stirred at room temperature for 3 h to obtain a precursor solution.

[0065] The precursor solution is placed in a reaction kettle and reacted at 150 °C for 12 h. After natural cooling, it is repeatedly washed with deionized water and ethanol and dried in a constant temperature air blast drying oven at 60 °C for 10 h to obtain magnesium hydroxide / attapulgite flame retardant.

[0066] Example 4

[0067] A preparation method of magnesium hydroxide / attapulgite flame retardant, comprising the following steps:

[0068] The attapulgite ore is crushed and coarsely screened with a mesh size of 400 meshes to obtain coarsely purified attapulgite.

[0069] According to the dosage ratio of the coarsely purified attapulgite to the nitrous acid solution of 1 g: 100 mL, wherein the concentration of the nitrous acid solution is 0.5 mol / L; the coarsely purified attapulgite is added to the nitrous acid solution and stirred at room temperature for 4 h to obtain modified attapulgite.

[0070] The modified attapulgite is washed with deionized water and then dried to obtain purified attapulgite.

[0071] 1 g of MgCl₂·6H₂O, 100 mL of ammonia water solution with a mass concentration of 13% and 1 g of purified attapulgite are mixed and stirred at room temperature for 1 h to obtain a precursor solution.

[0072] The precursor solution is placed in a reaction kettle and reacted at 180 °C for 10 h. After natural cooling, it is repeatedly washed with deionized water and ethanol and dried in a constant temperature air blast drying oven at 80 °C for 10 h to obtain a magnesium hydroxide / attapulgite flame retardant.

[0073] Example 5

[0074] A preparation method of a magnesium hydroxide / attapulgite flame retardant, comprising the following steps:

[0075] The attapulgite ore is crushed and coarsely screened with a mesh size of 400 meshes to obtain coarsely purified attapulgite.

[0076] According to the dosage ratio of attapulgite to hypochlorous acid solution of 1 g: 1000 mL, wherein the concentration of the hypochlorous acid solution is 1 mol / L; the coarsely purified attapulgite is added to the hypochlorous acid solution and stirred at room temperature for 1 h to obtain modified attapulgite.

[0077] The modified attapulgite is washed with deionized water and then dried to obtain purified attapulgite.

[0078] 1 g of MgCl₂·6H₂O, 100 mL of ammonia water solution with a mass concentration of 13% and 1 g of purified attapulgite are mixed and stirred at room temperature for 1 h to obtain a precursor solution.

[0079] The precursor solution is placed in a reaction kettle and reacted at 200 °C for 6 h. After natural cooling, it is repeatedly washed with deionized water and ethanol and dried in a constant temperature air blast drying oven at 80 °C for 10 h to obtain a magnesium hydroxide / attapulgite flame retardant.

[0080] Comparative Example 1

[0081] A preparation method of a magnesium hydroxide / attapulgite flame retardant, comprising the following steps:

[0082] The attapulgite ore is crushed and roughly screened with a mesh size of 400 meshes to obtain roughly purified attapulgite.

[0083] According to the dosage ratio of attapulgite to chloric acid solution of 1 g: 1000 mL, wherein the concentration of the chloric acid solution is 1 mol / L; the roughly purified attapulgite is added to the chloric acid solution and stirred at room temperature for 1 h to obtain modified attapulgite.

[0084] The modified attapulgite is washed with deionized water and then dried to obtain purified attapulgite.

[0085] 1 g of MgCl₂·6H₂O, 100 mL of ammonia water solution with a mass concentration of 13% and 1 g of purified attapulgite are mixed and stirred at room temperature for 1 h to obtain a precursor solution.

[0086] The precursor solution is aged at room temperature for 24 h to obtain a magnesium hydroxide / attapulgite flame retardant.

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

[0088] In this comparative example, the precursor solution is not hydrothermally treated in a reaction kettle.

[0089] Application Example 1

[0090] A preparation method of a flame retardant material, comprising the following steps:

[0091] 10 g of epoxy resin E-44 and 2.0 g of the magnesium hydroxide / attapulgite flame retardant prepared in Example 1 are mixed and heated at 70 °C for 120 min. After presenting a grayish-white emulsion, 3.5 g of 4,4'-diaminodiphenyl sulfone is added, stirred evenly, and then quickly poured into a mold and cured at 160 °C to form a shape. After natural cooling and demolding, a flame retardant material is obtained.

[0092] Application Example 2

[0093] A preparation method of a flame retardant material, comprising the following steps:

[0094] 10 g of epoxy resin E-44 and 2.3 g of the magnesium hydroxide / attapulgite flame retardant prepared in Example 2 are mixed and heated at 90 °C for 60 min. After presenting a grayish-white emulsion, 3.5 g of 4,4'-diaminodiphenyl sulfone is added, stirred evenly, and then quickly poured into a mold and cured at 160 °C to form a shape. After natural cooling and demolding, a flame retardant material is obtained.

[0095] Application Example 3

[0096] A preparation method of a flame retardant material, comprising the following steps:

[0097] After mixing 10 g of epoxy resin E-44 with 2.3 g of the magnesium hydroxide / palygorskite flame retardant prepared in Example 3 and heating at 100 °C for 30 min, when a grayish-white emulsion appeared, 2.6 g of 4,4'-diaminodiphenyl sulfone was added. After stirring evenly, it was quickly poured into a mold and cured at 160 °C. After natural cooling and demolding, a flame retardant material was obtained.

[0098] Application Example 4

[0099] A method for preparing a flame retardant material, comprising the following steps:

[0100] After mixing 10 g of epoxy resin E-44 with 2.8 g of the magnesium hydroxide / palygorskite flame retardant prepared in Example 4 and heating at 100 °C for 30 min, when a grayish-white emulsion appeared, 3.5 g of 4,4'-diaminodiphenyl sulfone was added. After stirring evenly, it was quickly poured into a mold and cured at 160 °C. After natural cooling and demolding, a flame retardant material was obtained.

[0101] Application Example 5

[0102] A method for preparing a flame retardant material, comprising the following steps:

[0103] After mixing 10 g of epoxy resin E-44 with 3.0 g of the magnesium hydroxide / palygorskite flame retardant prepared in Example 5 and heating at 100 °C for 30 min, when a grayish-white emulsion appeared, 3.5 g of 4,4'-diaminodiphenyl sulfone was added. After stirring evenly, it was quickly poured into a mold and cured at 160 °C. After natural cooling and demolding, a flame retardant material was obtained.

[0104] Application Example 6

[0105] A method for preparing a flame retardant material, comprising the following steps:

[0106] After mixing 10 g of epoxy resin E-44 with 3.5 g of the magnesium hydroxide / palygorskite flame retardant prepared in Example 1 and heating at 100 °C for 30 min, when a grayish-white emulsion appeared, 3.5 g of 4,4'-diaminodiphenyl sulfone was added. After stirring evenly, it was quickly poured into a mold and cured at 160 °C. After natural cooling and demolding, a flame retardant material was obtained.

[0107] Application Comparative Example 1

[0108] A method for preparing a flame retardant material, comprising the following steps:

[0109] After mixing 10 g of epoxy resin E-44 with 2.0 g of the magnesium hydroxide / palygorskite flame retardant prepared in Comparative Example 1 and heating at 70 °C for 120 min, after presenting a grayish-white emulsion, 3.5 g of 4,4'-diaminodiphenyl sulfone was added, stirred evenly, and then quickly poured into a mold and cured at 160 °C to form a shape. After natural cooling and demolding, a flame retardant material was obtained.

[0110] Experimental tests:

[0111] 1. SEM characterization.

[0112] As Figure 1 shown, magnesium hydroxide grows uniformly on the surface of palygorskite, forming a uniformly distributed surface morphology; compared with the surface morphology of the magnesium hydroxide / palygorskite flame retardant prepared in Example 1, as Figure 2 shown, the magnesium hydroxide in Comparative Example 1 grows unevenly on the surface of palygorskite, the particle distribution is uneven, and there is an obvious agglomeration phenomenon. This shows that by regulating the reaction environment, the present invention enables magnesium hydroxide to nucleate and grow in situ and uniformly on the surface of palygorskite, effectively avoiding the agglomeration phenomenon and improving the performance of the magnesium hydroxide / palygorskite flame retardant.

[0113] 2. Flame retardancy test.

[0114] According to the GB / T 2406-2009 standard, the present invention conducts flame retardancy tests on the flame retardant materials prepared in Application Examples 1 to 6 and Application Comparative Example 1. The full English name of the limiting oxygen index is Limiting Oxygen Index, and the English abbreviation is LOI. LOI is an important index to measure the flame retardancy of materials, and the higher the value, the better the flame retardancy of the materials.

[0115] As Figure 3 shown, the LOI value of pure epoxy resin is 21%, indicating that the flame retardancy of pure epoxy resin is poor. The LOI value of the flame retardant material prepared in Application Comparative Example 1 is 23.3%. Although it is slightly higher than the LOI value of pure epoxy resin, it is still relatively low, indicating that its flame retardancy is not ideal. The LOI values of the flame retardant materials prepared in Application Examples 1 to 6 are between 28.4% and 29.3%, significantly higher than those of pure epoxy resin and the flame retardant material prepared in Application Comparative Example 1, indicating that after adding the magnesium hydroxide / palygorskite flame retardant, the flame retardancy of the epoxy resin composite material has been significantly improved.

[0116] This indicates that the dispersibility and synergistic effect of the magnesium hydroxide / palygorskite flame retardant prepared by the present invention in epoxy resin significantly improve the flame retardancy of the flame retardant material. Specifically, magnesium hydroxide will decompose and release crystal water at high temperatures, absorbing a large amount of heat, thereby reducing the temperature of the material and delaying or preventing combustion. As an inorganic filler, palygorskite has good thermal stability and mechanical properties, can enhance the overall properties of the material, and form a protective oxide layer during the combustion process, further improving the flame retardant effect.

[0117] It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and either of the two endpoints can be selected. Since the step methods adopted are the same as those in the embodiments, in order to prevent repetition, the present invention describes preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept, and these changes and modifications all fall within the scope of the present invention.

[0118] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention also intends to include these changes and deformations.

Claims

1. Preparation method of magnesium hydroxide / palygorskite flame retardant, characterized in that, It includes the following steps: Using attapulgite as a carrier, in an alkaline solution system, attapulgite and inorganic magnesium salt react at 80°C to 200°C, enabling magnesium hydroxide to nucleate and grow in-situ on the surface of attapulgite to obtain magnesium hydroxide / attapulgite flame retardant.

2. The preparation method of the magnesium hydroxide / palygorskite flame retardant according to claim 1, wherein The mass ratio of inorganic magnesium salt to attapulgite is 1:1 to 10.

3. The preparation method of the magnesium hydroxide / palygorskite flame retardant according to claim 1, characterized in that, The reaction time is 6h to 24h.

4. The preparation method of the magnesium hydroxide / palygorskite flame retardant according to claim 1, characterized in that, The specific preparation method of magnesium hydroxide / attapulgite flame retardant is as follows: Mix attapulgite, inorganic magnesium salt and alkaline solution, and stir at room temperature to obtain a precursor solution; Place the precursor solution at 80°C to 200°C for reaction, enabling magnesium hydroxide to nucleate and grow in-situ on the surface of attapulgite to obtain magnesium hydroxide / attapulgite flame retardant.

5. The preparation method of the magnesium hydroxide / palygorskite flame retardant according to claim 4, characterized in that, The pH value of the precursor solution is 8 to 14.

6. The preparation method of the magnesium hydroxide / palygorskite flame retardant according to claim 1, characterized in that, Attapulgite is obtained by purifying attapulgite ore; The specific purification method is as follows: Crush the attapulgite ore and perform coarse screening to obtain roughly purified attapulgite; mix the roughly purified attapulgite with oxidizing acid for acidification treatment to obtain attapulgite; The oxidizing acid is concentrated sulfuric acid, concentrated nitric acid, dilute nitric acid, nitrous acid or halogen-containing oxyacid.

7. A magnesium hydroxide / palygorskite flame retardant, characterized in that, The magnesium hydroxide / attapulgite flame retardant is prepared by using the preparation method of the magnesium hydroxide / attapulgite flame retardant according to any one of claims 1 to 6.

8. A flame retardant material, characterized in that, The flame retardant material includes the magnesium hydroxide / attapulgite flame retardant according to claim 6.

9. The flame retardant material according to claim 8, characterized in that, The flame retardant material is prepared by the following method: Mix the magnesium hydroxide / attapulgite flame retardant and matrix resin, and heat at 70°C to 100°C to disperse the magnesium hydroxide / attapulgite flame retardant in the matrix resin. Then, add a curing agent and stir. After casting and curing, the flame retardant material is obtained; Among them, the mass ratio of magnesium hydroxide / attapulgite flame retardant to matrix resin is 2.0 to 3.5:10; The mass ratio of matrix resin to curing agent is 10:2.6 to 3.

5.

10. The flame retardant material according to claim 9, wherein, The matrix resin is epoxy resin or phenolic resin; The curing agent is 4,4'-diaminodiphenyl sulfone.

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