High-dispersity magnesium hydroxide flame retardant as well as preparation method and application thereof

Abstract

The invention relates to a high-dispersity magnesium hydroxide flame retardant as well as a preparation method and application thereof. The flame retardant comprises a magnesium hydroxide crystal and a multifunctional composite group which is modified on the surface of the magnesium hydroxide crystal and is used for improving the flame retardant property, wherein the magnesium hydroxide crystal accounts for 90-98% by mass, and the multifunctional composite group accounts for 2-10% by mass; the multifunctional composite group is composed of an organosilicon group, an olefin group, a nitrogen-containing group, a hydrophilic group and a hydrophobic group. A magnesium hydroxide crude product is subjected to surface modification treatment by adopting the weakly hydrophobic and strongly hydrophobic modifiers, and wet modification and dry modification processes are combined, so that the distribution narrowness (span) of the flame retardant is improved, the dispersion effect and the compatibility of the material are further improved, and the overall flame retardant property of the material is remarkably improved; meanwhile, the mechanical property of the filling material is maintained or enhanced, and an innovative solution is provided for developing an efficient and environment-friendly polymer flame-retardant material.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, and in particular to a highly dispersible magnesium hydroxide flame retardant, a preparation method thereof, and applications thereof. Background Art

[0002] Magnesium hydroxide (Mg(OH)), as a highly effective and environmentally friendly inorganic flame retardant, has attracted considerable attention in the field of polymer flame retardancy due to its non-toxicity, smoke suppression, high thermal stability, and readily available raw materials. Its flame retardant mechanism primarily relies on its decomposition at high temperatures (approximately 340°C) to produce magnesium oxide (MgO) and water (HO), which absorb large amounts of heat and can reduce the surface temperature of the material. The water vapor released during decomposition dilutes the concentration of combustible gases and oxygen, inhibiting the combustion chain reaction. Furthermore, the generated MgO can form a dense protective layer that blocks heat and oxygen transfer. Compared to traditional halogen-based flame retardants, magnesium hydroxide releases no halogen.

[0003] Although magnesium hydroxide has significant advantages, its practical application is still limited by problems such as high surface polarity, poor dispersibility, and insufficient compatibility with the polymer matrix. In recent years, a number of patents have attempted to solve these problems through surface modification and process optimization, but the following shortcomings still exist: First, the surface modification is single and the functional synergy is poor. For example, stearic acid is used for single modification and hydrophobicity is improved by physical coating, but the binding force between stearic acid and the surface of magnesium hydroxide is weak and it is easy to desorb during high-temperature processing, resulting in a decrease in flame retardant efficiency. Alternatively, only silane coupling agents (such as KH-550) are used for surface grafting. Although the compatibility with the polymer is improved, nitrogen-containing flame retardant groups are not introduced, and the gas-phase flame retardant effect is limited. Second, the preparation process is poor, resulting in a lack of control over the crystal morphology, mechanical force chemical modification destroys the crystal structure, and surface defects increase. The existing process lacks precise control of crystal morphology such as size, thickness, specific surface area and surface functionalization, making it difficult to achieve uniform dispersion under high filling amount, and mostly relies on single modifiers such as stearic acid and silane coupling agents, lacks multi-functional group collaborative design, resulting in limited comprehensive performance. Therefore, it is urgent to develop a magnesium hydroxide flame retardant to overcome the above-mentioned defects of the prior art. Summary of the Invention

[0004] To solve the above problems, the present invention provides a highly dispersible magnesium hydroxide flame retardant, introduces a multifunctional composite group, and adopts a strong and weak hydrophobic composite modification process to improve the compatibility of the magnesium hydroxide flame retardant and the material, thereby better exerting the flame retardant effect and improving the overall flame retardant performance of the material.

[0005] One of the inventive points of the present invention is a highly dispersible magnesium hydroxide flame retardant, which includes magnesium hydroxide crystals and multifunctional composite groups modified on the surface of the magnesium hydroxide crystals to improve flame retardancy; wherein the mass fraction ratio is: 90-95% of the magnesium hydroxide crystals and 5-10% of the multifunctional composite groups.

[0006] Furthermore, the multifunctional composite group consists of an organosilicon group, an olefin group, a nitrogen-containing group, a hydrophilic group, and a hydrophobic group.

[0007] Furthermore, the multifunctional composite group is formulated in the following proportions by mass: 1.0-2.5 parts of organosilicon group, 0.3-0.8 parts of nitrogen-containing group, 0.4-1.2 parts of hydrophilic group, 0.8-2.0 parts of hydrophobic group, and 0.5-1.5 parts of olefin group.

[0008] Furthermore, the flame retardant has a layered ring structure, which is as follows from the inside to the outside:

[0009] The inner core is a magnesium hydroxide crystal. The middle layer connected to the inner core and extending outward is composed of olefin groups, nitrogen-containing groups, and hydrophilic groups. The hydrophobic groups and silicone groups are connected to the middle layer and arranged outward, thereby forming a strongly hydrophobic shell covering the surface of the middle layer.

[0010] Furthermore, the crystal structure of the flame retardant is hexagonal.

[0011] Preferably, the flame retardant crystals have an average particle size of 500-1500 nm and a thickness of 200-800 nm.

[0012] Another invention of the present invention is a method for preparing a highly dispersible magnesium hydroxide flame retardant, comprising the following steps:

[0013] (1) preparing magnesium sulfate solution;

[0014] (2) adding an organic precipitant to the magnesium sulfate solution to generate magnesium hydroxide precipitate;

[0015] (3) heating the suspension after precipitation in step 2) to react;

[0016] (4) adding a weak hydrophobic modifier to the suspension after the reaction in step 3) to perform weak hydrophobic modification;

[0017] (5) drying the suspension after the reaction in step 4) to obtain a preliminarily modified magnesium hydroxide powder;

[0018] (6) A strong hydrophobic modifier is used to perform secondary modification on the magnesium hydroxide powder initially modified in step 5) to obtain a magnesium hydroxide flame retardant.

[0019] Furthermore, the mass fraction of the magnesium sulfate solution in step 1) is 20-50%;

[0020] The temperature of the precipitation reaction in step 2) is 25-60° C., and the amount of the organic precipitant added is 28-47% of the mass of the magnesium sulfate.

[0021] The reaction temperature of the suspension in step 3) is 220-250° C., and the reaction time is 3-24 hours;

[0022] The hydrophilic modification reaction temperature in step 4) is 40-100° C., the time is 3-5 hours, and the amount of the weak hydrophobic modifier added is 1-4% of the mass of the magnesium hydroxide;

[0023] The drying method in step 5) is selected from any one of spray drying, vacuum drying, oven drying, and freeze drying; the drying time is 12 to 24 hours, and the temperature is 80 to 100°C.

[0024] The reaction temperature of the strong hydrophobic modification in step 6) is 25-45° C., the reaction time is 1-3 hours, and the amount of the strong hydrophobic modifier added is 1-4% of the mass of the magnesium hydroxide.

[0025] Preferably, the organic precipitant in step 2) is selected from any one of ethanolamine, diethanolamine, triethanolamine or ethylenediamine.

[0026] Preferably, the weakly hydrophobic modifier in step 4) is selected from any one of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane.

[0027] Preferably, the strong hydrophobic modifier in step 6) is selected from any one of dodecylchlorosilane, dodecyldichlorosilane, erucamidopropyldimethyl tertiary amine, and dodecyldiethoxysilane.

[0028] The third invention of the present invention is a flame-retardant electric wire, comprising the highly dispersible magnesium hydroxide flame retardant as described above or the highly dispersible magnesium hydroxide flame retardant prepared by the method described above;

[0029] Preferably, the amount of the magnesium hydroxide flame retardant added to the wire material is 10% to 60%.

[0030] The fourth invention of the present invention is a flame retardant application of the highly dispersible magnesium hydroxide flame retardant described above or the highly dispersible magnesium hydroxide flame retardant prepared by the method described above in the fields of plastics, rubber, electronic appliances or coatings.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The present invention introduces multifunctional composite groups. Through the synergistic effect of the composite groups, the compatibility of the flame retardant with different matrices is achieved, the dispersibility of the flame retardant in the material and the interfacial bonding strength are improved. The hydrophobic outer layer reduces the moisture absorption of magnesium hydroxide, preventing agglomeration and performance degradation. The present invention achieves controllable modification of functional groups on the surface of magnesium hydroxide.

[0033] 2. In the present invention, a weakly alkaline organic base precipitant is used instead of a strong alkaline precipitant such as sodium hydroxide, ammonia water or lime milk to moderate the precipitation reaction. By precisely controlling the magnesium sulfate concentration, reaction temperature and time, the hexagonal flake crystals prepared have a narrow particle distribution and good dispersibility, which significantly improves the interfacial bonding strength between the flame retardant and the matrix, achieving the technical effect of precisely controlling the crystal morphology.

[0034] 3. The surface of the crude magnesium hydroxide product is modified by using weakly hydrophobic and strongly hydrophobic modifiers. At the same time, a process combining wet modification and dry modification is used to improve the compatibility of the magnesium hydroxide flame retardant and the material, thereby improving the overall flame retardant properties of the material. It can also maintain the mechanical properties of the filling material and even improve some of the mechanical properties, providing an innovative solution for the development of efficient and environmentally friendly polymer flame retardant materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 (A) is a scanning electron microscope image of the highly dispersible magnesium hydroxide flame retardant product of Test Example 1, (B) is an XRD pattern of the highly dispersible magnesium hydroxide flame retardant product of Test Example 1, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Test Example 1;

[0036] Figure 2 (A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of Comparative Example 1 of the present invention, (B) is an XRD pattern of the magnesium hydroxide flame retardant product of Comparative Example 1, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Comparative Example 1;

[0037] Figure 3 (A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of Comparative Example 2 of the present invention, (B) is an XRD pattern of the magnesium hydroxide flame retardant product of Comparative Example 2, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Comparative Example 2;

[0038] Figure 4 (A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of Comparative Example 3 of the present invention, (B) is an XRD pattern of the magnesium hydroxide flame retardant product of Comparative Example 3, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Comparative Example 3;

[0039] Figure 5 (A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of Comparative Example 4 of the present invention, (B) is an XRD pattern of the magnesium hydroxide flame retardant product of Comparative Example 4, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Comparative Example 4;

[0040] Figure 6(A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of Comparative Example 5 of the present invention, (B) is an XRD pattern of the magnesium hydroxide flame retardant product of Comparative Example 5, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of Comparative Example 5;

[0041] Figure 7 (A) is a scanning electron microscope image of the magnesium hydroxide flame retardant product of comparative example 6 of the present invention, (B) is an XRD diagram of the magnesium hydroxide flame retardant product of comparative example 6, and (C) is a particle size distribution diagram of the highly dispersible magnesium hydroxide flame retardant product of comparative example 6.

[0042] Specific implementation methods

[0043] To make the purpose, technical solutions and advantages of this application more clear, this application is further described in detail below. However, it should be understood that the description herein is only used to explain this application and is not intended to limit the scope of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended solely for the purpose of describing specific embodiments and are not intended to limit this application. The reagents and instruments used herein are commercially available, and the characterization methods involved can be found in the relevant descriptions in the prior art and will not be further elaborated herein.

[0045] In order to further understand the present application, the present application is further described in detail below in conjunction with the best embodiment.

[0046] Example 1

[0047] The invention provides a highly dispersible magnesium hydroxide flame retardant. The flame retardant comprises magnesium hydroxide crystals and multifunctional composite groups modified on the surface of the magnesium hydroxide crystals. The mass fraction ratio is: 90-98% of the magnesium hydroxide crystals and 2-10% of the multifunctional composite groups. The multifunctional composite groups are composed of an organosilicon group, an olefin group, a nitrogen-containing group, a hydrophilic group, and a hydrophobic group.

[0048] 7. As a further preferred embodiment, the main active ingredients of the flame retardant are as follows: 90-98% by weight of magnesium hydroxide, 1.0-2.5 parts of organosilicon groups, 0.3-0.8 parts of nitrogen-containing groups, 0.4-1.2 parts of hydrophilic groups, 0.8-2.0 parts of hydrophobic groups, and 0.5-1.5 parts of olefin groups.

[0049] Preferably, the mass fraction thereof is composed of: magnesium hydroxide 90-98%, for example, it can be 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or any value between any two values;

[0050] 1.0-2.5 parts of the organosilicon group, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 parts or any value between any two values;

[0051] 0.3-0.8 parts of nitrogen-containing groups, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 parts or any value between any two values;

[0052] 0.4-1.2 parts of hydrophilic groups, for example, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, parts or any value between any two values;

[0053] 0.8-2.0 parts of hydrophobic groups, for example, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 parts or any value between any two values;

[0054] The olefin group is 0.5-1.5 parts, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 parts or any value between any two values.

[0055] Magnesium oxide crystals are colorless, transparent crystals with the chemical formula Mg(OH)2. They possess a certain degree of toughness and strength, typically appearing as colorless hexagonal prisms. The crystal structure of magnesium hydroxide crystals is layered, with one layer consisting of tightly packed hexagonal magnesium oxide ions and another layer consisting of octahedral hydroxide ions. This layered structure gives magnesium hydroxide crystals excellent solubility and ion exchange capacity.

[0056] This application is a modification of magnesium hydroxide crystals, so the structure of the flame retardant is still a crystal structure.

[0057] As a further preferred embodiment, the flame retardant has a layered ring structure, which is as follows from the inside to the outside: inner layer: magnesium hydroxide crystals; middle layer: the inner layer extends outward to link olefin groups, nitrogen-containing groups, and hydrophilic groups; the olefin groups enhance the compatibility with the polymer, and the hydrophilic groups enhance the affinity; the nitrogen-containing groups preferentially release non-combustible gases such as NH3 and H2O, dilute the oxygen concentration, interrupt the combustion chain reaction, and exert a gas-phase flame retardant effect; outer layer: the middle layer arranges hydrophobic groups and silicone groups outward, and covers the surface of the middle layer through chemical bonds or physical coating to form a strong hydrophobic shell, thereby improving dispersibility.

[0058] The synergistic effect of multifunctional composite groups, for example, the hierarchical design of weakly and strongly hydrophobic groups, ensures the compatibility of the flame retardant with different matrices. The vinyl and siloxane networks enhance physical entanglement with polymer chains, improving the dispersion and interfacial adhesion of the flame retardant in the material. The strongly hydrophobic outer layer reduces moisture absorption by the magnesium hydroxide, preventing agglomeration and performance degradation. This allows for the controlled modification of functional groups on the magnesium hydroxide surface.

[0059] From the inside out, the synergistic effect of "flame retardant core-interface reinforcement-hydrophobic protection" is achieved in sequence; the high-temperature stability of the modified layer is ensured by combining covalent bonds (Si-O-Mg) with physical coatings (long-chain alkyl groups); the regular crystal structure is conducive to uniform dispersion in the matrix, reducing stress concentration and maintaining the mechanical properties of the material.

[0060] As a further preferred embodiment, the organosilicon group includes silanol (-Si-OH), siloxane (-Si-O-Si-) and siloxy (-Si-O-Mg); the nitrogen-containing group includes amino (-NH); the hydrophilic group includes hydroxyl (-OH) and silanol (-Si-OH); the hydrophobic group includes any one of methyl (-CH) or long-chain alkyl.

[0061] As a further preferred embodiment, the organic silicon group further includes a methylsilyl group (-Si-CH); and the nitrogen-containing group further includes an amide group (-CONH-).

[0062] The organosilicon group can give the flame retardant excellent high-temperature stability, delay thermal decomposition and enhance the bonding strength with the matrix. The silane coupling agent firmly anchors the functional group to the surface of magnesium hydroxide through the Si-O-Mg bond.

[0063] Nitrogen-containing groups decompose at high temperatures to release NH3, H2O, etc., which can dilute oxygen and inhibit the combustion chain reaction, forming a synergistic effect with the solid-phase flame retardant of magnesium hydroxide to improve the overall flame retardant efficiency. It can also adjust the surface polarity to enhance the interfacial bonding force with polar polymers.

[0064] Weakly hydrophobic groups can enhance the affinity of the material with other media, thereby improving the dispersibility and wettability of the material. At the same time, they can form hydrogen bonds or chemical bonds with the polymer matrix to enhance interfacial activity. They can also provide reactive activity and provide bonding sites for subsequent modifiers to achieve a gradient functionalized surface.

[0065] The hydrophobic group can also form a physical barrier to block water penetration, prevent magnesium hydroxide from absorbing moisture and agglomerating, and enhance moisture resistance. The methyl group gives the magnesium hydroxide flame retardant hydrophobicity and interfacial compatibility, thereby optimizing its dispersibility, stability and flame retardant properties in the polymer; the long-chain alkyl or siloxane group (-Si-O-Si-) has good compatibility with non-polar polymers and reduces interfacial defects.

[0066] The olefin group participates in the free radical termination reaction at high temperature, inhibiting the chain growth of the combustion process. It can also provide unsaturated double bonds, enabling it to react with free radicals or double bonds in the polymer matrix (such as polyethylene, polypropylene, etc.) to form chemical bonds, significantly improving the interfacial bonding strength between the magnesium hydroxide particles and the polymer. This chemical bonding reduces phase separation and makes the magnesium hydroxide more evenly dispersed in the polymer, thereby improving the tensile strength, impact resistance and other mechanical properties of the composite material.

[0067] As a further preferred embodiment, the crystal structure of the flame retardant is hexagonal.

[0068] As a further preferred embodiment, the average particle size of the flame retardant crystals is 500nm-1500nm, for example, it can be 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1100nm, 1200nm, 1500nm or any value between any two values.

[0069] The XRD thickness of the magnesium hydroxide crystals is 200 nm-300 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm or any value between any two values.

[0070] As a further preferred embodiment, the flame retardant contains Mg, O, H, C, N, and Si elements, wherein Mg: 40%, O: 54%, H: 3%, C: 1%, N: 0.2%, and Si: 0.3%.

[0071] Example 2

[0072] The present invention provides a method for preparing a highly dispersible magnesium hydroxide flame retardant, comprising the following steps:

[0073] (1) preparing magnesium sulfate solution;

[0074] (2) adding an organic precipitant to the magnesium sulfate solution to generate magnesium hydroxide precipitate;

[0075] (3) reacting the suspension obtained after precipitation in step 2) under certain conditions;

[0076] (4) adding a hydrophilic modifier to the suspension after the reaction in step 3) to perform hydrophilic modification;

[0077] (5) drying the suspension after the reaction in step 5) for 12-24 hours at a temperature of 80-100° C. to obtain a preliminarily modified magnesium hydroxide powder;

[0078] (6) A strong hydrophobic modifier is used to perform secondary modification on the magnesium hydroxide powder initially modified in step 5) to obtain a magnesium hydroxide flame retardant.

[0079] As a further preferred embodiment, the mass fraction of the magnesium sulfate solution in step 1) is 20-50%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% or any value between any two values.

[0080] The present invention selects a magnesium sulfate solution with a mass fraction of 20-50%, which can ensure sufficient magnesium ion supply and avoid oversaturation problems, thereby optimizing reaction efficiency and product quality. If the concentration is less than 20%, magnesium ions (Mg 2+ ) is insufficient, the precipitation reaction rate is low, the magnesium hydroxide yield decreases, and the concentration >50% increases the solution viscosity, which may lead to local supersaturated crystallization and the generation of impurities, affecting the product purity.

[0081] As a further preferred embodiment, the temperature of the precipitation reaction in step 2) is 25-60° C., and the amount of the organic precipitant added is 28%-47% of the mass of the magnesium sulfate.

[0082] As a further preferred embodiment, the reaction temperature of the suspension in step 3) is 220-250°C, for example, it can be 220°C, 221°C, 222°C, 223°C, 224°C, 225°C, 226°C, 227°C, 228°C, 229°C, 230°C, 231°C, 232°C, 233°C, 234°C, 235°C, 236°C, 237°C, 238°C, 239°C, 240°C, 241°C, 242°C, 243°C, 244°C, 245°C, 246°C, 247°C, 248°C, 249°C, 250°C or any value between any two values.

[0083] A temperature of 220-250°C is conducive to the directional growth of magnesium hydroxide crystals, forming a high-purity hexagonal shape. This accelerates the reaction rate of the precipitant and magnesium sulfate, shortens the reaction time, ensures complete reaction, and reduces residual unreacted impurities. Magnesium hydroxide crystals tend to form a regular lamellar structure, which is conducive to uniform dispersion in the polymer matrix and enhances the flame retardant effect. Furthermore, at this temperature, autogenous pressure is generated within the reactor, further promoting crystal growth and structural optimization, avoiding the incomplete crystal growth at normal pressure. Temperatures too high or below 220°C also result in incomplete crystal growth.

[0084] The reaction time is 3 to 24 hours, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 hours or any number between any two numbers.

[0085] Preferably, the reaction time of the suspension is 12 to 24 hours. A longer reaction time ensures that the magnesium sulfate is completely converted into magnesium hydroxide, avoids unreacted impurities affecting the purity of the product, and gradually regularizes the crystal morphology, significantly improving flame retardancy and thermal stability. In addition, the crystal size can be gradually increased, making it more suitable for composite materials requiring high mechanical strength.

[0086] As a further preferred embodiment, the hydrophilic modification reaction temperature in step 4) is 40-100°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C, 100°C or any value between any two values.

[0087] Vinyl silane coupling agents are more susceptible to hydrolysis at temperatures between 40°C and 100°C, generating silanol groups (-Si-OH), which then undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of magnesium hydroxide, forming a stable Si-O-Mg bond. Organic modifiers (such as surfactants and coupling agents) may decompose or become ineffective at high temperatures. A temperature range of 40°C to 100°C ensures reaction efficiency while preventing modifier decomposition. The appropriate temperature promotes the adsorption and bonding of modifier molecules on the surface of magnesium hydroxide, forming a uniform coating and improving the hydrophilicity and dispersibility of the particles.

[0088] The reaction time is 3 to 5 hours, for example, 3, 4, 5 hours or any value between any two values.

[0089] A reaction time of 3-5 hours is sufficient for the modifier to be fully hydrolyzed, adsorbed and bonded to the surface of magnesium hydroxide to ensure uniform modification effect. Too long a reaction time may cause self-condensation of the modifier (such as silane coupling agent to generate siloxane oligomers), reducing modification efficiency. At the same time, while ensuring the modification effect, production efficiency and economy are taken into account.

[0090] Preferably, the amount of the weakly hydrophobic modifier added is 1 to 4% of the mass of the magnesium hydroxide.

[0091] As a further preferred embodiment, the drying method in step 5) is selected from any one of spray drying, vacuum drying, oven drying, and freeze drying;

[0092] Spray drying is suitable for large-scale production, quickly drying the suspension into microsphere particles and retaining the dispersion of the particles; vacuum drying is reduced pressure drying at low temperature (60-80℃) to avoid high temperature damage to the surface modification layer; oven drying is simple and direct, but the temperature must be controlled (80-100℃) to prevent particle agglomeration; freeze drying can retain the porous structure.

[0093] As a further preferred embodiment, the reaction temperature of the strong hydrophobic modification in step 6) is 25-45° C., the reaction time is 1-3 hours, and the amount of the strong hydrophobic modifier added is 1-3% of the mass of the magnesium hydroxide.

[0094] As a further preferred embodiment, the organic precipitant in step 2) is any one of ethanolamine, diethanolamine, triethanolamine or ethylenediamine,

[0095] For example, in the present invention, if ethanolamine is used as an organic precipitant, it can slowly react with magnesium sulfate to form magnesium hydroxide precipitate. The amino group (-NH) of ethanolamine provides an alkaline environment for efficient precipitation of Mg 2+ At the same time, nitrogen-containing groups are introduced to provide active sites for the weak hydrophobic modification (such as aminosilane bonding) in step 4. Some ethanolamine molecules can also form hydrogen bonds or weak coordination bonds with the hydroxyl groups (-OH) on the surface of magnesium hydroxide through amino groups (-NH) or hydroxyl groups (-OH), and adsorb on the surface of particles to reduce the tendency of agglomeration before drying. Therefore, ethanolamine has the function of an alkaline precipitant and a surface pre-modifier.

[0096] As a further preferred embodiment, the hydrophilic modifier in step 4) is selected from any one of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(2-methoxyethoxy)silane.

[0097] For example, in the present invention, when vinyltriethoxysilane is used as a coupling agent in a weak hydrophobic modifier, vinyl groups (CH=CH-) and silanol groups (-Si(OCHCH)3) are mainly introduced, wherein the silanol groups are hydrolyzed to form silanol groups (-Si-OH), which then undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of the magnesium hydroxide crystals to form a stable Si-O-Mg covalent bond, thereby firmly anchoring the vinyl groups on the surface of the magnesium hydroxide, and the unreacted silanol groups (-Si-OH) can serve as hydrophilic groups.

[0098] As a further preferred embodiment, the strong hydrophobic modifier in step 6) is selected from any one of dodecylchlorosilane, dodecyldichlorosilane, erucamidopropyldimethyl tertiary amine, and dodecyldiethoxysilane.

[0099] Strong hydrophobic modifier can introduce hydrophobic group, and the hydrolysis-condensation reaction of dodecylchlorosilane, dodecyldichlorosilane, erucamide propyl dimethyl tertiary amine, dodecyldiethoxysilane can also produce silicon oxygen bond and be connected to magnesium hydroxide surface equally.For example, in the present invention, if dodecyldiethoxysilane is used to carry out hydrophobic modification, after dodecyldiethoxysilane is hydrolyzed, ethoxyl group (OCH CH) falls off, releases ethanol (CH CHOH), and remaining silane molecule passes through silanol (Si-OH) and the hydroxyl group (OH) of magnesium hydroxide particle surface generation condensation reaction, forms stable Si-O-Mg covalent bond.Finally, the alkyl in silane molecule is connected to magnesium hydroxide surface by chemical bond, forms strong hydrophobic layer, if erucamide propyl dimethyl tertiary amine is used, then amide group (CONH-) can be introduced.

[0100] The present invention first uses wet modification and then dry modification. First, the function optimization can be carried out in stages. First, wet modification (weak hydrophobic modification) is carried out in solution to improve its hydrophilicity and dispersibility. A stable particle basis is provided for subsequent drying and strong hydrophobic modification to avoid particle agglomeration during the drying process. Then dry modification (strong hydrophobic modification) is used to directly introduce hydrophobic groups on the surface of the dry particles to avoid solvent interference and ensure efficient coverage of the strong hydrophobic agent. Dry heating promotes the hydrolysis and condensation of the silane coupling agent to form a dense hydrophobic layer, thereby improving the interfacial compatibility of the flame retardant in the polymer. Second, the process controllability. The wet modification accurately controls the surface polar groups (such as amino groups) through solution reaction; the dry modification optimizes the coverage and bonding strength of the hydrophobic group through heating conditions. Third, the economy and efficiency are improved. The wet modification utilizes the dispersibility of the solution to reduce the amount of modifier; the dry modification does not require a solvent, saves costs and simplifies the post-processing steps. In summary, the advantages of the step-by-step modification of the present invention are that the wet modification optimizes the dispersibility and surface activity, and the dry modification enhances the hydrophobicity and interfacial compatibility, and the two synergistically improve the comprehensive performance of the magnesium hydroxide flame retardant.

[0101] Example 3

[0102] The present invention provides a flame-retardant electric wire comprising the above-mentioned highly dispersible magnesium hydroxide flame retardant.

[0103] As a further preferred embodiment, the addition amount of the highly dispersible magnesium hydroxide flame retardant in the wire material is 10% to 60%.

[0104] As a further preferred embodiment, the wire material is any one of polyvinyl chloride (PVC), polyethylene (PE) or polypropylene (PP).

[0105] As a further preferred embodiment, the present invention also provides a flame retardant application of the above-mentioned highly dispersible magnesium hydroxide flame retardant in the fields of plastics, rubber or coatings.

[0106] Example 4

[0107] According to the content of this application, a highly dispersible magnesium hydroxide flame retardant and a preparation method thereof are specifically described. If no specific steps or conditions are specified in the examples, they can be carried out according to conventional methods or conditions described in the literature in this field.

[0108] The present invention is further described in detail below with reference to specific examples. These examples should not be construed as limiting the scope of protection claimed in the present invention.

[0109] Test Example 1

[0110] 1. Preparation of highly dispersible magnesium hydroxide flame retardant 1

[0111] 1. Material Preparation

[0112] 1.1 Materials and Reagents

[0113] Magnesium sulfate (MgSO·7HO): analytical grade, used for the preparation of magnesium sulfate solution.

[0114] Ethanolamine (CHNO): analytically pure, used as a precipitant.

[0115] Vinyltriethoxysilane (CHOSi): analytically pure, used for preliminary modification.

[0116] Dodecyldimethyldiethoxysilane (C 18 H 37 OSi): analytically pure, used for secondary modification.

[0117] Deionized water: used to dissolve magnesium sulfate.

[0118] Ethanol: used to wash the precipitate.

[0119] 1.2 Instruments and Equipment

[0120] Electronic balance: used to weigh reagents.

[0121] Magnetic stirrer: used to stir the reaction solution.

[0122] Constant temperature water bath: used to control the reaction temperature.

[0123] Vacuum drying oven: used to dry magnesium hydroxide powder.

[0124] pH meter: used to detect the pH value of the solution.

[0125] Centrifuge: used to separate sediment.

[0126] Burette: used for adding reagents.

[0127] 1.3 Prepare 35% magnesium sulfate solution;

[0128] 1. Calculate the dosage:

[0129] Assume that to prepare 100mL of 35% magnesium sulfate solution, the mass of magnesium sulfate required is:

[0130] Magnesium sulfate mass = 100mL × 1.0g / mL × 35% = 35g; weigh 35g of magnesium sulfate

[0131] (MgSO·7HO). Dissolution operation:

[0132] Add 35g of magnesium sulfate to a beaker and about 80mL of deionized water. Stir until completely dissolved. Transfer the solution to a 100mL volumetric flask, dilute to the mark with deionized water, and shake well for later use.

[0133] 2. Preparation Process

[0134] 1) Take 100ml of 35% magnesium sulfate solution,

[0135] (2) Add 10 g of ethanolamine (mass) to a 35% magnesium sulfate solution at 50° C. to generate a magnesium hydroxide precipitate;

[0136] (3) reacting the suspension after precipitation in step 2) at 250° C. for 24 hours;

[0137] (4) Add 5 ml of vinyltriethoxysilane to the suspension after the reaction in step 3) and react at 100° C. for 5 hours;

[0138] (5) vacuum drying the suspension after the reaction in step 4) at 60° C. for 24 hours to obtain a preliminarily modified magnesium hydroxide powder;

[0139] Specific drying method:

[0140] The suspension after the reaction in step (4) is centrifuged to collect the precipitate.

[0141] The precipitate was washed three times with ethanol to remove unreacted reagents.

[0142] The precipitate was transferred to a vacuum drying oven, set at 60°C and a vacuum degree of -0.1 MPa, and dried for 24 hours to obtain preliminarily modified magnesium hydroxide powder.

[0143] (6) 3 ml of dodecyldiethoxysilane was used to react at 25° C. for 2 hours to perform secondary modification on the magnesium hydroxide powder obtained in step 5) to obtain magnesium hydroxide flame retardant 1, such as Figure 1 shown.

[0144] Test Example 2

[0145] Preparation method of highly dispersible magnesium hydroxide flame retardant 2:

[0146] The preparation method of highly dispersible magnesium hydroxide flame retardant 2 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that the organic precipitant in step 2) is changed to diethanolamine; the temperature in step 3) is changed to 220 ° C., the reaction time is changed to 3 hours, the temperature in step 4) is changed to 40 ° C., the reaction time is changed to 3 hours, vinyltrimethoxysilane is used as a weak hydrophobic modifier; dodecylchlorosilane is used as a strong hydrophobic modifier in step 6), and the remaining steps are the same to obtain magnesium hydroxide flame retardant 2.

[0147] Test Example 3

[0148] Preparation method of highly dispersible magnesium hydroxide flame retardant 3:

[0149] The preparation method of highly dispersible magnesium hydroxide flame retardant 2 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that the organic precipitant in step 2 is changed to triethanolamine; the temperature in step 3) is changed to 230 ° C., the reaction time is changed to 12 hours, the temperature in step 4) is changed to 80 ° C., the reaction time is changed to 4 hours, and vinyl tris (2-methoxyethoxy) silane is used as a weak hydrophobic modifier; dodecyldichlorosilane is used as a strong hydrophobic modifier in step 6), and the remaining steps are the same to obtain magnesium hydroxide flame retardant 3.

[0150] Comparative Example 1

[0151] Preparation method of magnesium hydroxide flame retardant 4:

[0152] The preparation method of magnesium hydroxide flame retardant 4 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that step 6) strong hydrophobic modification is not performed. The remaining steps are the same to obtain magnesium hydroxide flame retardant 4. Figure 2 shown.

[0153] Comparative Example 2

[0154] Preparation method of magnesium hydroxide flame retardant 5:

[0155] The preparation method of magnesium hydroxide flame retardant 5 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that step 4) weak hydrophobic modification is not performed. The remaining steps are the same to obtain magnesium hydroxide flame retardant 5. Figure 3 shown.

[0156] Comparative Example 3

[0157] Preparation method of magnesium hydroxide flame retardant 6:

[0158] The preparation method of magnesium hydroxide flame retardant 6 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that step 4) weak hydrophobic modification and step 6) strong hydrophobic modification are not performed. The remaining steps are the same to obtain magnesium hydroxide flame retardant 6. Figure 4 shown.

[0159] Comparative Example 4

[0160] Preparation method of magnesium hydroxide flame retardant 7:

[0161] The preparation method of magnesium hydroxide flame retardant 7 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Test Example 1, except that the precipitant in step 2) is changed to sodium hydroxide, and the weak hydrophobic modifier in step 4) is changed to aminopropyltriethoxysilane. The remaining steps are the same to obtain magnesium hydroxide flame retardant 7. Figure 5 shown.

[0162] Comparative Example 5

[0163] Preparation method of magnesium hydroxide flame retardant 8:

[0164] The preparation method of magnesium hydroxide flame retardant 8 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Experimental Example 1, except that the reaction conditions of step 4) and step 6) are exchanged, namely:

[0165] Step 4) Add 3 ml of dodecyldiethoxysilane to the suspension after the reaction in step 3) and react at 25° C. for 2 hours.

[0166] Step 6) Add 5 ml of vinyltriethoxysilane and react at 100° C. for 5 hours. The magnesium hydroxide powder obtained in step 5) is subjected to secondary modification to obtain magnesium hydroxide flame retardant 8.

[0167] The rest of the steps are the same.

[0168] Comparative Example 6

[0169] Preparation method of magnesium hydroxide flame retardant 9:

[0170] The preparation method of magnesium hydroxide flame retardant 9 is roughly the same as that of highly dispersible magnesium hydroxide flame retardant 1 in Experimental Example 1, except that the temperature in step 3) is changed to 400 ° C. and the reaction time is changed to 1 hour. The temperature in step 4) is changed to 25 ° C. and the reaction time is changed to 1 hour. The remaining steps are the same to obtain magnesium hydroxide flame retardant 9.

[0171] Experimental Example 1 (Structure Verification)

[0172] 1. Hexagonal Shape Analysis: The hexagonal flaky structure of magnesium hydroxide was observed using a scanning electron microscope (SEM). The sample was dispersed on a conductive adhesive and then gold-sprayed. The particle morphology was then observed under an SEM at a magnification of typically 10,000-50,000x to confirm the hexagonal flaky structure and size distribution. See Table 1 for details.

[0173] 2. XRD structure analysis: The crystal structure and grain size of magnesium hydroxide can be analyzed by X-ray diffraction (XRD). Using Cu-Kα radiation The scanning range 2θ = 10°-80°, the step size 0.02°, and the scanning speed 2° / min. The grain size was calculated using the Scherrer formula: D = Kλ / (βcosθ), where K is the shape factor (typically 0.89), λ is the X-ray wavelength, β is the half-width at half-maximum of the diffraction peak, and θ is the diffraction angle. See Table 1 for details.

[0174] 3. Surface functional group analysis: The surface functional groups of magnesium hydroxide can be analyzed by Fourier transform infrared spectroscopy (FT-IR). The sample is mixed with KBr and pressed into a pellet, and scanned in the range of 4000-400 cm-1 with a resolution of 4 cm -1 The grafting status of the surface modifier was judged by characteristic absorption peaks (such as Si-O-Si, CH, NH, etc.), as shown in Table 1.

[0175] 4. Dispersion: Laser particle size analysis is used to measure the dispersion of magnesium hydroxide by laser diffraction. The particle size distribution of the particles is measured by laser diffraction using a laser particle size analyzer. The sample is dispersed in deionized water (or a solvent that matches the matrix material) and ultrasonically treated for 10-15 minutes to ensure that the particles are fully dispersed. The suspension is injected into a test tank and the particle size distribution of the particles is measured by laser diffraction to record the volume average particle size (D50) and the polydispersity index (PDI). Dispersion is calculated as: PDI = (D90-D10) / D50, where D10, D50, and D90 are the particle sizes corresponding to 10%, 50%, and 90% of the cumulative distribution, respectively. The smaller the PDI value, the more uniform the particle distribution and the better the dispersion. See Table 1 for details.

[0176] Experimental Example 2 Magnesium Hydroxide Flame Retardant Performance Test

[0177] Preparation of flame retardant wire 1:

[0178] 1. Material selection

[0179] 1) Base material: Polyethylene (PE) is selected as the base material for the insulation layer of the wire.

[0180] 2) Flame retardant: The highly dispersible magnesium hydroxide flame retardant 1 of Test Example 1 of the present invention was selected as the flame retardant.

[0181] 3) Other additives: Appropriate amounts of dispersants, stabilizers, antioxidants, etc. may be added to improve processing performance and material stability. Other additives account for 0.5%-2% of dispersants, 1%-3% of stabilizers, and 0.1%-1% of antioxidants. Dispersants include one of polyethylene wax (PE wax), zinc stearate, and ethylene bisstearamide (EBS). Stabilizers include one of calcium zinc composite stabilizers (environmentally friendly) and organic tin stabilizers (such as dibutyltin dilaurate). Antioxidants include one of butylated hydroxytoluene (BHT), hindered phenol antioxidants (Irganox 1010), and phosphite synergistic antioxidants (antioxidant 168).

[0182] 2. Preparation process

[0183] (1) The polymer substrate PE is mixed with the prepared highly dispersed magnesium hydroxide flame retardant 1, dispersant, stabilizer, and antioxidant according to the formula ratio, wherein the polymer substrate PE is 56.5g, the magnesium hydroxide flame retardant is 140g, the dispersant PE wax is 1g, the stabilizer calcium zinc composite stabilizer is 2g, and the antioxidant BHT is 0.5g.

[0184] (2) Use a high-speed mixer or internal mixer to mix and ensure that all components are evenly dispersed.

[0185] (3) The mixed material is extruded into granules through a twin-screw extruder, and the extrusion temperature is controlled at 200°C.

[0186] (4) The extruded pellets are cooled and pelletized to obtain flame retardant masterbatch.

[0187] (5) The flame retardant masterbatch is extruded through a wire extruder at 200°C and coated on the surface of the conductor.

[0188] (6) The extruded wire is subjected to cooling, drawing, winding and other processes to be made into a flame-retardant wire 1.

[0189] 3. Preparation of other wires

[0190] The preparation methods of the remaining flame-retardant wires 2, 3, 4, 5, 6, 7, 8, and 9 are roughly the same as the preparation method of the above-mentioned flame-retardant wire 1, except that the magnesium hydroxide flame retardant 1 is replaced by magnesium hydroxide flame retardants 2, 3, 4, 5, 6, 7, 8, and 9. The remaining steps are the same to obtain the remaining flame-retardant wires.

[0191] 1. Mechanical Properties: Tensile strength testing is conducted using an electronic tensile testing machine in accordance with ISO 527. The wire sample is clamped in a fixture and stretched at a rate of 50 mm / min. The maximum force at break is recorded and the tensile strength (MPa) is calculated.

[0192] 2. Flame retardant performance test

[0193] Vertical Flame Test: In accordance with UL 94 standards, the wire is fixed vertically on a flame test stand, ignited with a flame for 10 seconds, and the burning time, dripping, and self-extinguishing conditions are observed.

[0194] 3. Extrusion effect

[0195] Surface smoothness: Evaluate the surface smoothness of the wire sheath by visual inspection or touch. The wire is qualified if there are no obvious particles, bubbles or cracks.

[0196] The specific test results are shown in Table 1 below.

[0197] Table 1 Performance test table of magnesium hydroxide flame retardant and flame retardant wire

[0198]

[0199] As shown in the data in the above table, the organic base precipitant with weak alkalinity is used in the present invention provided by the present invention to replace the precipitant with strong alkalinity such as sodium hydroxide, ammonia or milk of lime, so that precipitation reaction is relaxed, and by the accurate control of magnesium sulfate concentration, reaction temperature and time, the hexagonal plate crystals prepared, average single crystal particle size 500-1500nm, thickness is 200-800nm, and distribution narrowness is 0.68-1.2, significantly improving flame retardant and matrix interface bonding force, reaching the technical effect of accurate regulation of crystal morphology. The crude magnesium hydroxide product is surface modified using weak hydrophobic and strong hydrophobic modifiers, while using the process combined with wet modification and dry modification, the compatibility of magnesium hydroxide fire retardant and material is improved, and then the flame retardant performance of the material as a whole is improved, the mechanical properties of the filling material can also be not decreased, and even some mechanical properties are improved.

[0200] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A highly dispersible magnesium hydroxide flame retardant, characterized in that, The flame retardant comprises magnesium hydroxide crystals and multifunctional composite groups modified on the surface of the magnesium hydroxide crystals for improving flame retardancy; the mass fraction ratio is: 90-98% of the magnesium hydroxide crystals and 2-10% of the multifunctional composite groups.

2. The flame retardant according to claim 1, wherein the multifunctional composite group is composed of an organosilicon group, an olefin group, a nitrogen-containing group, a hydrophilic group, and a hydrophobic group.

3. The flame retardant according to claim 1, characterized in that The multifunctional composite group is mixed in the following proportions by mass: 1.0-2.5 parts of organosilicon group, 0.3-0.8 parts of nitrogen-containing group, 0.4-1.2 parts of hydrophilic group, 0.8-2.0 parts of hydrophobic group and 0.5-1.5 parts of olefin group.

4. The flame retardant according to claim 1, characterized in that The flame retardant has a layered ring structure, which is as follows from the inside to the outside: The inner core is a magnesium hydroxide crystal. The middle layer connected to the inner core and extending outward is composed of olefin groups, nitrogen-containing groups, and hydrophilic groups. The hydrophobic groups and silicone groups are connected to the middle layer and arranged outward, thereby forming a strongly hydrophobic shell covering the surface of the middle layer.

5. The flame retardant according to claim 1, characterized in that The crystal structure of the flame retardant is hexagonal; Preferably, the flame retardant crystals have an average particle size of 500-1500 nm and a thickness of 200-800 nm.

6. A method for preparing a highly dispersible magnesium hydroxide flame retardant according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) preparing magnesium sulfate solution; (2) adding an organic precipitant to the magnesium sulfate solution to generate magnesium hydroxide precipitate; (3) heating the suspension after precipitation in step 2) to react; (4) adding a weak hydrophobic modifier to the suspension after the reaction in step 3) to perform weak hydrophobic modification; (5) drying the suspension after the reaction in step 4) to obtain a preliminarily modified magnesium hydroxide powder; (6) A strong hydrophobic modifier is used to perform secondary modification on the magnesium hydroxide powder initially modified in step 5) to obtain a magnesium hydroxide flame retardant.

7. The method according to claim 6, characterized in that The mass fraction of the magnesium sulfate solution in step 1) is 20-50%; The temperature of the precipitation reaction in step 2) is 25-60° C., and the amount of the organic precipitant added is 28-47% of the mass of the magnesium sulfate. The reaction temperature of the suspension in step 3) is 220-250° C., and the reaction time is 3-24 hours; The hydrophilic modification reaction temperature in step 4) is 40-100° C., the time is 3-5 hours, and the amount of the hydrophobic modifier added is 1-4% of the mass of the magnesium hydroxide; The drying method in step 5) is selected from any one of spray drying, vacuum drying, oven drying, and freeze drying; the drying time is 12 to 24 hours, and the temperature is 80 to 100°C. The reaction temperature of the strong hydrophobic modification in step 6) is 25-45° C., the reaction time is 1-3 hours, and the amount of the strong hydrophobic modifier added is 1-4% of the mass of the magnesium hydroxide.

8. The method according to claim 5, characterized in that The organic precipitant is selected from any one of ethanolamine, diethanolamine, triethanolamine or ethylenediamine; Preferably, the weakly hydrophobic modifier is selected from any one of vinyltrimethoxysilane, vinyltriethoxysilane and vinyltri(2-methoxyethoxy)silane. Preferably, the strong hydrophobic modifier is selected from any one of dodecylchlorosilane, dodecyldichlorosilane, erucamidopropyldimethyl tertiary amine, and dodecyldiethoxysilane.

9. A flame retardant electric wire, characterized in that: Comprising the highly dispersible magnesium hydroxide flame retardant according to any one of claims 1 to 5 or the highly dispersible magnesium hydroxide flame retardant prepared by the method according to any one of claims 6 to 8; Preferably, the amount of the magnesium hydroxide flame retardant added to the wire material is 10% to 60%.

10. A flame retardant application of the highly dispersible magnesium hydroxide flame retardant according to any one of claims 1 to 5 or the highly dispersible magnesium hydroxide flame retardant prepared by the method according to any one of claims 6 to 8 in the fields of plastics, rubber, electronic appliances or coatings.

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