Vinyl-modified magnesium-based flame retardant, and preparation method and application thereof

Abstract

The application relates to the technical field of functional materials, in particular to a vinyl-modified magnesium-based flame retardant as well as a preparation method and application thereof, which comprises the following steps: adding water-magnesite into an ethanol solution to stir into a slurry, adding a modification aid, heating to 50-80 DEG C, constant-temperature stirring for 10-20 min, then filtering, drying, and obtaining the vinyl-modified magnesium-based flame retardant; the mass ratio of the water-magnesite to the modification aid is 1:(0.001-0.005). The vinyl-modified magnesium-based flame retardant does not contain halogen, has high-efficiency flame retardation, has good compatibility with high-molecular materials, and can improve the mechanical properties of high-molecular polymer materials when used.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a vinyl-modified magnesium-based flame retardant, its preparation method, and its application. Background Technology

[0002] With the widespread application of polymer materials in construction, electronics, transportation, and other fields, the safety hazards posed by their flammability are becoming increasingly prominent. Flame retardants, as key additives for improving the flame retardant properties of polymer materials, have attracted much attention in their research and application, with aluminum hydroxide and magnesium hydroxide being the most widely used. Aluminum hydroxide has a low decomposition temperature, making it suitable for polymers with processing temperatures below their decomposition temperature; magnesium hydroxide has a decomposition temperature of 300–330℃, making it suitable for polymers with higher processing temperatures. It also possesses advantages such as being non-toxic, halogen-free, smoke-suppressing, and environmentally friendly, and has become one of the most promising new flame retardants. However, magnesium hydroxide and aluminum hydroxide are expensive, resulting in high preparation costs. Furthermore, the proportion of magnesium hydroxide or aluminum hydroxide added is strictly limited because they readily cause a decrease in the mechanical properties of materials. Therefore, it is necessary to develop new flame retardants to replace aluminum hydroxide and magnesium hydroxide.

[0003] Magnesia hydrate is a green and environmentally friendly flame retardant that emerged after aluminum hydroxide and magnesium hydroxide. It has vast reserves, and research on magnesia hydrate is gradually increasing. For example, CN117844165A discloses "a method for preparing a flame-retardant material and the flame-retardant material," which modifies magnesia hydrate using an acid containing double bonds to obtain modified magnesia hydrate; reacts the modified magnesia hydrate with glycerol esters to obtain a flame-retardant substance; and mixes the flame-retardant substance, an antioxidant, and acrylonitrile-butadiene-styrene resin to obtain a flame-retardant material with good flame-retardant properties.

[0004] For example, CN117089224A discloses "a multi-layer natural product modified ultrafine hydromagnesia composite powder and its preparation method and application". Solution 1 is prepared using caffeic acid, inorganic salts, and a solvent. Then, hydromagnesia and the solvent are mixed to obtain dispersion 2. Dispersion 2 is added to solution 1 to react and obtain caffeic acid modified hydromagnesia powder CA-UHM. Then, phenylboronic acid derivatives, inorganic salts, and a solvent are mixed to obtain solution 3. The caffeic acid modified hydromagnesia powder CA-UHM is mixed with the solvent to obtain dispersion 4. Dispersion 4 is added dropwise to solution 3 to react and obtain multi-layer natural product modified ultrafine hydromagnesia composite powder 4-TA-CA-UHM. This ultrafine hydromagnesia composite powder simultaneously achieves synergistic flame retardant effects in both the condensed phase and the gas phase, resulting in significant comprehensive flame retardant and smoke suppression effects.

[0005] However, when used as a flame retardant, hydrated magnesium hydroxide has high polarity and poor compatibility with polymer materials such as rubber, easily leading to agglomeration and a decline in material performance. Although the aforementioned patents have made some modifications to hydrated magnesium hydroxide, the modified hydrated magnesium hydroxide has relatively limited properties, which still restricts its application.

[0006] Therefore, it is urgent to develop a halogen-free magnesium-based flame retardant that is highly efficient in flame retardancy, has good compatibility with polymer materials, and has a wide range of applications. Summary of the Invention

[0007] The main objective of this invention is to provide a vinyl-modified magnesium-based flame retardant and its preparation method. This vinyl-modified magnesium-based flame retardant is halogen-free, has high flame retardancy, good compatibility with polymer materials, and can improve the mechanical and flame retardant properties of polymer materials during use.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a method for preparing a vinyl-modified magnesium-based flame retardant, comprising the following steps: adding hydrated magnesium hydroxide to an ethanol solution and stirring to form a slurry; adding a modifying agent; heating to 50-80°C; stirring at a constant temperature for 10-20 minutes; then filtering and drying to obtain the vinyl-modified magnesium-based flame retardant; wherein the mass ratio of hydrated magnesium hydroxide to the modifying agent is 1:(0.001-0.005).

[0010] Magnesium hydrate has been proven to have certain flame-retardant effects, and due to its abundant reserves and readily available raw materials, it is increasingly being used. However, due to its high polarity, magnesium hydrate is prone to agglomeration in polymer applications, leading to a decline in the performance of polymer materials. Furthermore, research has found that achieving high flame-retardant performance requires the introduction of large amounts of magnesium hydrate, but this compromises the material's mechanical and processing properties.

[0011] This application solves the above-mentioned technical problems by using hydromagnesia as the main raw material and modifying it with a specific structure of modifying agent. At the same time, the modified hydromagnesia can also improve the crosslinking effect with the polymer matrix and further enhance the mechanical properties of the material.

[0012] This application, by adjusting the mass ratio of hydrated magnesium hydroxide to the modifying agent, can prevent the modifying agent from forming a thick coating layer around the hydrated magnesium hydroxide, thereby reducing the flow properties of the hydrated magnesium hydroxide and consequently reducing its processing performance.

[0013] In some embodiments, the modified additive has the structure shown in Formula I.

[0014]

[0015] This application discloses a self-made modified additive with a specific structure. This modified additive can effectively graft and modify MgCl2, improving not only the compatibility of MgCl2 with polymer materials but also its flame retardant properties. Furthermore, it allows for increased MgCl2 addition without reducing the material's mechanical properties. The reasons for this are likely as follows: First, the modified additive contains a large number of siloxane structures, which can react with the hydroxyl groups on the surface of MgCl2, anchoring the additive to the surface through chemical bonds, reducing the polarity of MgCl2, enhancing its compatibility with the material, and preventing agglomeration that could lead to a decline in material performance. Second, the modified additive contains a large amount of N and P elements and is halogen-free, significantly improving the flame retardant properties of MgCl2. Third, the modified additive contains vinyl structures, which can crosslink with the matrix resin under radiation crosslinking processes to form a three-dimensional network structure. This network structure can form chemical bonds at the flame retardant-matrix interface, enhancing interfacial bonding and thus improving mechanical properties.

[0016] In some embodiments, the preparation method of the modified additive includes the following steps:

[0017] S1. Acryloyl chloride, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, the first solvent, and azobisisobutyronitrile were mixed, heated to 60-70°C, and stirred at a constant temperature for 12-14 hours. After the reaction was completed, the mixture was filtered, dried, and subjected to column chromatography to obtain the compound shown in Formula II.

[0018]

[0019] S2. Melamine, the compound shown in Formula II from step S1, and acryloyl chloride are mixed, a second solvent is added, followed by an acid-binding agent. The mixture is heated to 30–40°C and stirred at this temperature for 6–8 hours. After the reaction is complete, the mixture is filtered, extracted, and dried to obtain the compound shown in Formula III.

[0020]

[0021] S3. Mix the compound shown in Formula III in step S2 with chloromethyltrimethoxysilane, heat to 100-110°C, stir at a constant temperature for 3-5 hours, add diethyl ether after the reaction is complete, filter, and dry to obtain the modified additive.

[0022] In some embodiments, in step S1, the molar ratio of acryloyl chloride to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1 to 1.3).

[0023] Preferably, in step S1, the molar ratio of acryloyl chloride to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1.2.

[0024] In some embodiments, in step S1, the first solvent is any one of toluene, xylene, tetrahydrofuran, and N,N-dimethylformamide.

[0025] In some embodiments, in step S2, the acid-binding agent is any one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and triethylamine.

[0026] In some embodiments, in step S2, the molar ratio of melamine, the compound represented by Formula II, and acryloyl chloride is 1:(1-1.2):(1-1.2).

[0027] Preferably, in step S2, the molar ratio of melamine, the compound represented by Formula II, and acryloyl chloride is 1:1.1:1.1.

[0028] In some embodiments, the second solvent is any one of 1,4-dioxane, N,N-dimethylformamide, toluene, and chloroform.

[0029] In some embodiments, in step S3, the molar ratio of the compound represented by Formula III to chloromethyltrimethoxysilane is 1:(1 to 1.4).

[0030] Preferably, in step S3, the molar ratio of the compound represented by Formula III to chloromethyltrimethoxysilane is 1:1.2.

[0031] In another aspect, the present invention provides a vinyl-modified magnesium-based flame retardant prepared by the above-described technical solution.

[0032] Another aspect of the present invention provides the application of a vinyl-modified magnesium-based flame retardant in cable materials.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The vinyl-modified magnesium-based flame retardant of the present invention is obtained by using hydrated magnesium as raw material and processing with modifying additives. The vinyl-modified magnesium-based flame retardant is halogen-free, has high flame retardancy, good compatibility with polymer materials, and can improve the mechanical properties of polymer materials when used.

[0035] (2) The modified additive of the present invention is prepared by using melamine, acryloyl chloride, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and chloromethyltrimethoxysilane as the main raw materials. The modified additive contains a large number of siloxane structures, which can react with the hydroxyl groups on the surface of MgO after hydrolysis, so that the modified additive is anchored on the surface of MgO through chemical bonds, reducing the polarity of MgO and enhancing the compatibility between MgO and the material, preventing agglomeration and thus reducing the material performance. Secondly, the modified additive contains a large number of N and P elements and does not contain halogens, which can significantly improve the flame retardant performance of MgO. In addition, the modified additive contains vinyl structures, which can cross-link with the matrix resin under the radiation cross-linking process to form a three-dimensional network structure, which can form chemical bonds at the flame retardant-matrix interface, enhance the interfacial bonding force, and thus improve the mechanical properties. Attached Figure Description

[0036] Figure 1 The 1H NMR spectrum of the modified additive in Example 1 of this application;

[0037] Figure 2 The proton NMR spectrum of the compound shown in Formula II in Example 1 of this application;

[0038] Figure 3 The proton NMR spectrum of the compound shown in Formula III in Example 1 of this application;

[0039] Figure 4 The 1H NMR spectrum of the modified additive in Example 2 of this application;

[0040] Figure 5 The 1H NMR spectrum of the modified additive in Example 3 of this application;

[0041] Figure 6 The 1H NMR spectrum of the modified additive in Example 4 of this application. Detailed Implementation

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of the invention. Various modifications and variations to the specific embodiments described in this specification are apparent to those skilled in the art without departing from the scope or spirit of the invention. Other embodiments derived from this specification will be apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0045] It should be noted that the operations such as "drying", "filtering", and "stirring" described in this invention are conventional operations for those skilled in the art, and should be selected according to actual operation.

[0046] Preparation Example 1

[0047] The preparation method of the modified additive includes the following steps:

[0048] S1. 100 mmol acryloyl chloride, 120 mmol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 500 mL toluene, and 0.2 g azobisisobutyronitrile were mixed, heated to 65 °C, and stirred at this temperature for 13 h. After the reaction was complete, the mixture was filtered, dried, and subjected to column chromatography to obtain the compound shown in Formula II.

[0049]

[0050] Please see the appendix Figure 2 The NMR analysis of the structure shown in Equation III is as follows: 1 H NMR(400MHz,)δ8.00(dd,J=8.0,1.0Hz,1H),7.92-7.84(m,2H),7.52-7.44( m,3H),7.41-7.33(m,2H),3.16-3.09(m,2H),2.75(dt,J=12.0,9.2Hz,2H);

[0051] S2. Mix 91 mmol of melamine, 100 mmol of the compound shown in Formula II from step S1, and 100 mmol of acryloyl chloride. Add 550 mL of 1,4-dioxane, followed by 200 mmol of triethylamine. Heat to 35 °C and stir for 7 h. After the reaction is complete, filter, extract, and dry to obtain the compound shown in Formula III.

[0052]

[0053] Please see the appendix Figure 3 The NMR analysis of the structure shown in Equation III is as follows:1 H NMR (400MHz) δ

[0054] 11.10(s,1H),10.74(s,1H),8.03-7.82(m,4H),7.55-7.30(m,7H),6.58-6.32(m ,4H),5.94(ddd,J=36.0,10.7,3.1Hz,3H),2.91-2.81(m,3H),2.80-2.67(m,3H);

[0055] S3. Mix 100 mmol of the compound shown in Formula III from step S2 with 120 mmol of chloromethyltrimethoxysilane, heat to 105 °C, stir at a constant temperature for 4 h, add diethyl ether until no more precipitate forms, filter, and dry to obtain the modified auxiliary agent with the structure shown in Formula I.

[0056]

[0057] Please see the appendix Figure 1 The NMR analysis of the structure shown in Equation I is as follows: 1 H NMR (400MHz) δ

[0058] 11.11(s,1H),10.75(s,1H),8.00(dt,J=8.0,0.6Hz,1H),7.92-7.83(m,3H),7.51-7.44(m,4H),7.41-7.33(m,3 H),6.46-6.35(m,3H),5.94(ddd,J=36.0,10.7,3.1Hz,3H),3.51(s,9H),2.89-2.81(m,3H),2.78-2.52(m,5H).

[0059] Preparation Example 2

[0060] The preparation method of the modified additive includes the following steps:

[0061] S1. 100 mmol acryloyl chloride, 120 mmol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 500 mL toluene, and 0.2 g azobisisobutyronitrile were mixed, heated to 65 °C, and stirred at this temperature for 13 h. After the reaction was complete, the mixture was filtered, dried, and subjected to column chromatography to obtain the compound shown in Formula II.

[0062]

[0063] S2. Mix 91 mmol of melamine, 100 mmol of the compound shown in Formula II from step S1, and 200 mmol of acryloyl chloride. Add 600 mL of 1,4-dioxane, followed by 300 mmol of triethylamine. Heat to 35 °C and stir for 7 hours. After the reaction is complete, filter, extract, and dry to obtain the compound shown in Formula IV, which is the modifying agent.

[0064]

[0065] Please see the appendix Figure 4 The NMR analysis of the structure shown in Equation IV is as follows: 1 H NMR (400MHz) δ

[0066] 11.11(s,1H),10.75(s,2H),8.00(dt,J=8.0,0.7Hz,1H),7.94-7.77(m,3H),7.59-7.28 (m,7H),6.39(t,J=12.0Hz,2H),5.94(ddd,J=36.0,10.7,3.1Hz,5H),2.93-2.64(m,6H).

[0067] Preparation Example 3

[0068] The preparation method of the modified additive includes the following steps:

[0069] S1. Mix 100 mmol of melamine and 210 mmol of acryloyl chloride, add 250 mL of 1,4-dioxane, then add 260 mmol of triethylamine, heat to 35 °C and stir for 7 h. After the reaction is complete, filter, extract, and dry to obtain the compound shown in Formula II.

[0070]

[0071] S2. Mix 100 mmol of the compound shown in Formula II from step S1 with 120 mmol of chloromethyltrimethoxysilane, heat to 105 °C, stir at a constant temperature for 4 h, add diethyl ether until no more precipitate forms, filter, and dry to obtain the modified auxiliary agent, as shown in Formula V.

[0072]

[0073] Please see the appendix Figure 5 The NMR analysis of the structure shown in Equation V is as follows: 1H NMR (400MHz,) δ10.75 (s, 1H), 6.47-6.34 (m, 6H), 5.94 (ddd, J = 36.0, 10.7, 3.1Hz, 8H), 3.51 (s, 14H), 2.70-2.52 (m, 4H).

[0074] Preparation Example 4

[0075] The preparation method of the modified additive includes the following steps:

[0076] S1. 100 mmol acryloyl chloride, 120 mmol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 500 mL toluene, and 0.2 g azobisisobutyronitrile were mixed, heated to 65 °C, and stirred at this temperature for 13 h. After the reaction was complete, the mixture was filtered, dried, and subjected to column chromatography to obtain the compound shown in Formula II.

[0077]

[0078] S2. Add 91 mmol of melamine and 100 mmol of the compound shown in Formula II from step S1 to 400 mL of 1,4-dioxane, followed by 100 mmol of triethylamine. Heat to 35 °C and stir for 7 h. After the reaction is complete, filter, extract, and dry to obtain the compound shown in Formula VI.

[0079]

[0080] S3. Mix 100 mmol of the compound shown in Formula VI from step S2 with 120 mmol of chloromethyltrimethoxysilane, heat to 105 °C, stir at a constant temperature for 4 h, add diethyl ether until no more precipitate forms, filter, and dry to obtain the modified auxiliary agent, as shown in Formula VII.

[0081]

[0082] Please see the appendix Figure 6 The NMR analysis of the structure shown in Equation VII is as follows: 1 H NMR (400MHz) δ

[0083] 11.06(s,1H),8.02-7.98(m,1H),7.91-7.84(m,3H),7.51-7.45(m,4H),7.40-7.33(m,2H),6 .63-6.51(m,3H),6.38(t,J=8.0Hz,2H),3.51(s,9H),2.90-2.81(m,3H),2.78-2.53(m,5H).

[0084] Example 1

[0085] A method for preparing a vinyl-modified magnesium-based flame retardant includes the following steps: adding 10g of magnesium hydroxide to 200mL of 95wt% ethanol solution and stirring to form a slurry; adding 0.03g of modifying agent; heating to 65℃; stirring at a constant temperature for 15min; then filtering and drying to obtain the vinyl-modified magnesium-based flame retardant.

[0086] The modified additive was prepared in Preparation Example 1.

[0087] Example 2

[0088] A method for preparing a vinyl-modified magnesium-based flame retardant includes the following steps: adding 10g of magnesium hydroxide to 200mL of 93wt% ethanol solution and stirring to form a slurry; adding 0.01g of modifying agent; heating to 50℃; stirring at a constant temperature for 20min; then filtering and drying to obtain the vinyl-modified magnesium-based flame retardant.

[0089] The modified additive was prepared in Preparation Example 1.

[0090] Example 3

[0091] A method for preparing a vinyl-modified magnesium-based flame retardant includes the following steps: adding 10g of magnesium hydroxide to 200mL of 97wt% ethanol solution and stirring to form a slurry; adding 0.05g of modifying agent; heating to 80℃; stirring at a constant temperature for 10min; then filtering and drying to obtain the vinyl-modified magnesium-based flame retardant.

[0092] The modified additive was prepared in Preparation Example 1.

[0093] Example 4

[0094] A method for preparing a vinyl-modified magnesium-based flame retardant is described, with the specific implementation method being the same as in Example 1, except that the modifying agent is prepared in Example 2.

[0095] Example 5

[0096] A method for preparing a vinyl-modified magnesium-based flame retardant is described, with the specific implementation method being the same as in Example 1, except that the modifying agent is prepared in Example 3.

[0097] Example 6

[0098] A method for preparing a vinyl-modified magnesium-based flame retardant is described, with the specific implementation method being the same as in Example 1, except that the modifying agent is prepared in Example 4.

[0099] Comparative Example 1

[0100] A method for preparing a vinyl-modified magnesium-based flame retardant, the specific implementation method is the same as in Example 1, except that the mass of the modifying agent is 0.1g.

[0101] Performance testing:

[0102] (1) Contact angle test: The vinyl-modified magnesium-based flame retardant was pressed into a sheet sample of 2cm×2cm×1cm and the contact angle was tested by the seat drop method.

[0103] (2) Activation index: The activation index is tested according to the standard T / CSTM 01202-2024 "Test method for activation index of organic modified inorganic powder materials". The higher the activation index, the stronger the hydrophobicity.

[0104] The vinyl-modified magnesium-based flame retardants of each embodiment and comparative example were tested according to the above test methods, and the test results are shown in Table 1.

[0105] Table 1

[0106] Contact angle (°) Activation index (%) Example 1 107.6 96 Example 2 105.2 94 Example 3 108.1 96 Example 4 93.8 90 Example 5 90.3 95 Example 6 106.1 97 Comparative Example 1 106.9 94

[0107] Analysis of the data in Table 1 shows that the vinyl-modified magnesium-based flame retardants prepared in Examples 1-3 and Example 6 have good hydrophobic properties and high activation index, which improves the compatibility of the vinyl-modified magnesium-based flame retardant with the polymer matrix. Compared with Example 1, Example 4, due to the change in the molar ratio of melamine, the compound shown in Formula II, and acryloyl chloride, did not introduce the siloxane structure, resulting in a decrease in the activation index and contact angle of the vinyl-modified magnesium-based flame retardant. In Example 5, because the modified additive structure does not contain a phenyl structure, the number of hydrophobic groups in the modified additive structure is reduced, thereby decreasing the hydrophobic properties of the vinyl-modified magnesium-based flame retardant and resulting in a decrease in the contact angle of the vinyl-modified magnesium-based flame retardant. In Comparative Example 1, although the performance change was not significant due to the change in the mass ratio of hydrated magnesium and modified additive, the actual operation was very difficult due to the reduced fluidity, which limited the scope of application.

[0108] 10g of POE 7467, 10g of EVA 2803A, and 0.4g of antioxidant 1010 were mixed, and then further mixed with 15g of vinyl-modified magnesium-based flame retardant and 15g of hydrated magnesium hydroxide, respectively, from each example. The sample mixed with hydrated magnesium hydroxide served as a control group. 60Co-γ was used as the radiation source with an intensity of 3.7 × 10⁻⁶. 15 Bq was irradiated for 5 hours in an N2 atmosphere at an irradiation dose rate of 10 kGy / h, granulated, and then placed at room temperature for 24 hours to obtain cable material masterbatch.

[0109] (3) Oxygen index: The flame retardant properties of cable masterbatch were tested in accordance with GB / T2408-2008;

[0110] (4) Tensile strength: The tensile strength of the cable material masterbatch was tested in accordance with GB / T1040-1992 standard.

[0111] The cable material masterbatch was tested according to the above test method, and the test results are shown in Table 2.

[0112] Table 2

[0113] Oxygen index (%) Tensile strength (MPa) control group 23.7 8.1 Example 1 34.6 15.9 Example 2 32.1 14.0 Example 3 35.7 15.2 Example 4 33.7 19.6 Example 5 27.1 18.8 Example 6 33.8 8.6

[0114] Analysis of the data in Table 2 shows that the cable masterbatch prepared using the vinyl-modified magnesium-based flame retardants of Examples 1-4 has good flame retardant and tensile properties. In Example 5, the lack of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide resulted in a deficiency of phosphorus in the vinyl-modified magnesium-based flame retardant, which prevented the achievement of a multi-element synergistic flame retardant effect, leading to a decrease in the flame retardant properties of the cable masterbatch. However, the increased vinyl group content improved its tensile properties. In Example 6, the lack of vinyl groups in the structure of the vinyl-modified magnesium-based flame retardant prevented the formation of a cross-linked structure with the matrix, resulting in a decrease in the tensile properties of the cable masterbatch.

[0115] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a vinyl-modified magnesium-based flame retardant, characterized in that, The process includes the following steps: adding hydrated magnesium hydroxide to an ethanol solution and stirring to form a slurry; adding a modifying agent; heating to 50-80°C; stirring at a constant temperature for 10-20 minutes; then filtering and drying to obtain a vinyl-modified magnesium-based flame retardant; the mass ratio of hydrated magnesium hydroxide to the modifying agent is 1:(0.001-0.005). The modified additive has the structure shown in Formula I. （Ⅰ）。 2. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 1, characterized in that, The preparation method of the modified additive includes the following steps: S1. Acryloyl chloride, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, the first solvent, and azobisisobutyronitrile were mixed, heated to 60-70°C, and stirred at a constant temperature for 12-14 hours. After the reaction was completed, the mixture was filtered, dried, and subjected to column chromatography to obtain the compound shown in Formula II. （Ⅱ）； S2. Melamine, the compound shown in Formula II from step S1, and acryloyl chloride are mixed, a second solvent is added, followed by an acid-binding agent. The mixture is heated to 30-40°C and stirred for 6-8 hours. After the reaction is complete, the mixture is filtered, extracted, and dried to obtain the compound shown in Formula III. （Ⅲ）； S3. Mix the compound shown in Formula III in step S2 with chloromethyltrimethoxysilane, heat to 100~110℃, stir at a constant temperature for 3~5h, add diethyl ether after the reaction is complete, filter, dry, and obtain the modified additive.

3. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 2, characterized in that, In step S1, the molar ratio of acryloyl chloride and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1~1.3).

4. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 2, characterized in that, In step S2, the acid-binding agent is any one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and triethylamine.

5. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 2, characterized in that, In step S2, the molar ratio of melamine, the compound represented by Formula II, and acryloyl chloride is 1:(1~1.2):(1~1.2).

6. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 2, characterized in that, The second solvent is any one of 1,4-dioxane, N,N-dimethylformamide, toluene, and chloroform.

7. The method for preparing the vinyl-modified magnesium-based flame retardant according to claim 2, characterized in that, In step S3, the molar ratio of the compound represented by Formula III to chloromethyltrimethoxysilane is 1:(1~1.4).

8. A vinyl-modified magnesium-based flame retardant prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the vinyl-modified magnesium-based flame retardant of claim 8 in cable materials.

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