A migration resistant modified aluminum diethylphosphinate and a method for its preparation

Abstract

The application relates to an anti-migration modified aluminum diethyl phosphinate and a preparation method thereof, and belongs to the technical field of flame retardants. The preparation method of the anti-migration modified aluminum diethyl phosphinate comprises three steps of synthesizing aluminum diethyl phosphinate superfine powder, one-time coating of hydroxyapatite and secondary coating of MQ silicon resin. After the anti-migration modified aluminum diethyl phosphinate is added into nylon 66 at an addition amount of 6 wt%, the tensile strength of the nylon 66 is 80.8-84.2 MPa, the bending strength is 120.6-124.1 MPa, the bending modulus is 3.1-3.3 GPa, the notched impact strength is 11.8-14.9 kJ / m 2 , the limiting oxygen index is 34.3-35.6%, the UL-94 V flame retardant grade reaches V-0 grade, the dispersion uniformity is 0, the anti-migration property is no precipitation, and the acidic corrosion loss amount is 0.07-0.1%.

Description

Technical Field

[0001] This invention relates to a migration-resistant modified aluminum diethylphosphinate and its preparation method, belonging to the field of flame retardant technology. Background Technology

[0002] Aluminum diethylphosphonate (ADP) is a novel, highly efficient halogen-free organophosphorus flame retardant with high thermal stability, chemical stability, and environmental friendliness. It can be used alone or in combination with other flame retardants, achieving good results in both applications. Polymers with added ADP produce an expanded char layer during combustion, achieving heat insulation, oxygen isolation, and preventing further spread of surface flames. It exhibits good char-forming self-extinguishing properties and excellent flame-retardant performance on materials such as polyesters (PET and PBT), nylon, epoxy resins, SEBS, and EPDM rubber. It is particularly suitable for flame retardant applications in wires and cables, high-end engineering plastics, high-temperature nylon, PA, PBT, and PET. However, with the expanding application of ADP in the flame-retardant field, two significant problems have also emerged.

[0003] First, due to its synthesis process and inherent properties, aluminum diethylphosphonate is highly acidic, exhibiting significant degradation of polymers and corrosion of equipment. This negative effect is particularly pronounced when the application system involves high-temperature heating. Second, with the development of the electronics industry, aluminum diethylphosphonate is increasingly used in printed circuit boards, electronic potting compounds, polyester films, and other electronic materials to create flame-retardant products. In these applications, ultrafine powder of aluminum diethylphosphonate (with a particle size measured by a laser particle size analyzer) is typically added. 90 The particle size is generally below 15μm to improve flame retardant efficiency and reduce the impact of large-particle aluminum diethylphosphonate on the mechanical properties of polymer products. However, in actual use, it has been found that the ultrafine powder of aluminum diethylphosphonate is prone to migration and agglomeration. For example, when it is mixed with epoxy resin, polyurethane resin, acrylic resin and other materials and coated on the surface of printed circuit boards and polyester film materials, the ultrafine powder of aluminum diethylphosphonate is very easy to migrate to the surface and precipitate, and agglomerate on the surface, resulting in granular white spots on the surface of printed circuit boards and polyester film materials. When the migration and precipitation problem is serious, it will significantly affect the yield of printed circuit boards and polyester film materials. Therefore, solving the above two major problems is of great practical significance for expanding the application scope of aluminum diethylphosphonate in the flame retardant field and improving the quality of flame retardant products.

[0004] Chinese patent CN113817229A discloses a migration-resistant modified aluminum diethylphosphonate, its preparation method, and its application. This patent employs pyrophosphate coating treatment of aluminum diethylphosphonate and surface coupling treatment with a silane coupling agent. After these two surface treatments, the migration-resistant modified aluminum diethylphosphonate obtained by this patent essentially solves the problems of agglomeration and migration precipitation. However, the migration-resistant modified aluminum diethylphosphonate still exhibits strong acidity with a pH value of 4.8-6.4. Furthermore, the particle size of the aluminum diethylphosphonate powder processed by this patent is very large. 50 With a particle size of 15~40μm, it does not belong to the ultrafine powder of aluminum diethylphosphinate, making it difficult to use in relatively high-end polymer materials such as printed circuit boards and polyester film materials.

[0005] Chinese patent CN109851852A discloses a low-corrosion dialkylphosphine acid salt composition and its application. This low-corrosion dialkylphosphine acid salt composition, by weight percentage, comprises: a dialkylphosphine acid salt mixture of 99-99.999 wt%; a sulfate of 0.001-1 wt%; the dialkylphosphine acid salt mixture includes at least diethylphosphine acid salt; and the sulfate is selected from inorganic sulfates. This patent significantly reduces the acid corrosion of the dialkylphosphine acid salt composition, but it does not solve the problems of dispersion and migration precipitation of fine-particle-size powders of the dialkylphosphine acid salt composition.

[0006] As can be seen above, ultrafine diethyl phosphonate powder still suffers from problems such as difficulty in uniform dispersion, migration and precipitation, and acid corrosion in flame retardant applications. Therefore, developing an ultrafine diethyl phosphonate powder that is easy to disperse, has good migration resistance, and is free from acid corrosion is of great significance for improving the quality of flame retardant polymer products made from aluminum diethyl phosphonate. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a migration-resistant modified aluminum diethylphosphinate and its preparation method, achieving the following objective: to prepare an easily dispersed, migration-resistant, and acid-corrosion-free ultrafine aluminum diethylphosphinate powder through surface modification.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A migration-resistant modified aluminum diethylphosphinate and its preparation method are disclosed. The migration-resistant modified aluminum diethylphosphinate, when incorporated into nylon 66 at a dosage of 6 wt%, results in nylon 66 with a tensile strength of 80.8–84.2 MPa, a flexural strength of 120.6–124.1 MPa, a flexural modulus of 3.1–3.3 GPa, and a notched impact strength of 11.8–14.9 kJ / m. 2It has a limiting oxygen index of 34.3~35.6%, a UL-94V flame retardant rating of V-0, a dispersion uniformity of 0, no exudation in terms of migration resistance, and an acid corrosion loss of 0.07~0.1%. The method for preparing the anti-migration modified aluminum diethylphosphinate includes three steps: synthesizing aluminum diethylphosphinate ultrafine powder, primary coating with hydroxyapatite, and secondary coating with MQ silicone resin. The following are further improvements to the above technical solution: Step 1: Synthesis of aluminum diethylphosphinate Sodium diethylphosphonate aqueous solution was placed in a reaction vessel and heated to the reaction temperature. Phytic acid aqueous solution was added under low-speed stirring to adjust the pH of the liquid in the vessel to 2.3-3.6. Then, aluminum sulfate aqueous solution was added dropwise, while phytic acid aqueous solution was added dropwise and the dropwise rate was controlled to keep the pH of the liquid in the reaction vessel at 2.3-4. After the aluminum sulfate solution was added, the temperature was raised to the holding temperature. After the holding reaction was completed, the product was filtered, washed, and dried to obtain aluminum diethylphosphonate ultrafine powder. The sodium diethylphosphonate aqueous solution has a mass concentration of 20-40 wt%. The phytic acid aqueous solution contains 25-35 wt% phytic acid. The aluminum sulfate aqueous solution has a mass concentration of 25-35 wt%. The mass ratio of sodium diethylphosphonate aqueous solution to aluminum sulfate aqueous solution is 20~97:30; The reaction temperature is 45~65℃; The low-speed stirring has a stirring rate of 600~1300 rpm; The aluminum sulfate aqueous solution is added at a rate of 8-50 g / min. The insulation temperature is 65~75℃; The heat preservation reaction is completed, and the heat preservation reaction time is 3 to 6 hours; The washing process involves washing 2-3 times with deionized water at a temperature of 80-95°C, with the mass of deionized water used in each wash being equal to the mass of the wet solid being washed. The drying process involves a drying temperature of 100-115℃ and a drying time of 3-6 hours.

[0009] Step 2: One-time coating of hydroxyapatite Diethylphosphonate aluminum ultrafine powder, calcium chloride, and deionized water were placed in a dispersion vessel and strongly dispersed evenly. After the dispersion rate was reduced, diammonium hydrogen phosphate aqueous solution was added dropwise. After the addition was completed, the dispersion reaction was continued until complete. Then, the mixture was allowed to stand for aging, filtered, washed with water, and dried to obtain diethylphosphonate aluminum ultrafine powder coated with hydroxyapatite once. The mass ratio of the aluminum diethylphosphinate ultrafine powder, calcium chloride, deionized water, and diammonium hydrogen phosphate aqueous solution is 55~150:4~30:360~1200:40~110; The mass concentration of diammonium hydrogen phosphate in the aqueous solution of diammonium hydrogen phosphate is 8-17 wt%. The diammonium hydrogen phosphate aqueous solution was added dropwise at a rate of 20-300 g / min. The strong dispersion is uniform, with a dispersion rate of 6000~9500 rpm and a dispersion time of 4~7 hours; The dispersion rate is reduced to 2400~4000 rpm; After the dispersion reaction is complete, the dispersion reaction time is 1 to 2.5 hours. The static aging process takes 10 to 20 hours. The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.5-7. The drying process involves a drying temperature of 85-110℃ and a drying time of 9-15 hours.

[0010] Step 3: Secondary coating with MQ silicone resin Hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, and phytic acid were added to a dispersion reactor and strongly dispersed until uniform. Then, the dispersion rate was reduced, and the temperature was raised to the reaction temperature. Tetraethyl orthosilicate was added, and the hydrolysis reaction was carried out under reflux. After the hydrolysis reaction was completed, hexamethyldisiloxane was added, and the dispersion reaction was continued until complete. After filtration, washing with water, and drying, the migration-resistant modified aluminum diethylphosphonate was obtained. The mass ratio of the hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane is 55~130:20~80:150~360:4~25:15~50:5~13. The strong dispersion is uniform, with a dispersion rate of 7000~9500 rpm and a dispersion time of 3~6 hours; The dispersion rate is reduced to 1500~3000 rpm; The reaction temperature is 65~80℃; The hydrolysis reaction is to be completed within 0.3 to 0.8 hours. The continued dispersion reaction is complete, and the reaction time is 2.5 to 5 hours; The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.4 to 6.9. The drying process involves a drying temperature of 80-100℃ and a drying time of 13-18 hours.

[0011] Compared with the prior art, the present invention achieves the following beneficial effects: 1. This invention aims to obtain ultrafine aluminum diethylphosphonate powder with a small particle size. Phytic acid is added during the synthesis of aluminum diethylphosphonate to regulate its precipitation rate. Phytic acid slows down the reaction rate between sodium diethylphosphonate and aluminum sulfate because it exhibits a strong complexation effect with aluminum ions under acidic conditions. In the reaction system, the concentration of completely free aluminum ions, unbound by the complexation effect, is low. This reduces the concentration of aluminum ions, one of the reactants. Furthermore, the concentration of free aluminum ions can be controlled by adjusting the amount of phytic acid added, thereby slowing down the precipitation reaction rate of aluminum ions with sodium diethylphosphonate. Ultimately, controllable particle size is achieved, and D... 90 Ultrafine powder of aluminum diethylphosphinate below 15 μm; 2. To address the problem that ultrafine diethylphosphonate powder is acidic and easily causes acid corrosion to processing equipment, this invention employs an in-situ reaction method to coat the ultrafine diethylphosphonate powder with hydroxyapatite. Hydroxyapatite is weakly alkaline and can effectively neutralize the acidity of the ultrafine diethylphosphonate powder. Test results show that without surface coating with hydroxyapatite, the acid corrosion loss to equipment during high-temperature processing is as high as 0.64%, while with surface coating with hydroxyapatite, the acid corrosion loss is reduced to 0.07-0.1%. Furthermore, hydroxyapatite has a very high melting point, and using it as a coating layer has no impact on the flame retardancy of the diethylphosphonate itself. 3. In order to improve the dispersibility of aluminum diethylphosphonate ultrafine powder in polymers and further enhance its anti-migration properties after incorporation into polymers, this invention further applies a secondary coating of aluminum diethylphosphonate ultrafine powder with MQ silicone resin on the basis of the primary coating with hydroxyapatite. After the primary coating with hydroxyapatite, the polarity of the surface of aluminum diethylphosphonate ultrafine powder is not reduced because hydroxyapatite is an inorganic material, and it still exhibits strong polarity, making it difficult to achieve uniform dispersion in polymers. However, MQ silicone resin not only has weak polarity but also has very good flame retardant properties due to its relatively high silicon content. Therefore, the secondary coating with MQ silicone resin can reduce the surface polarity of aluminum diethylphosphonate ultrafine powder, significantly improve the dispersion uniformity of aluminum diethylphosphonate ultrafine powder in polymers, and does not affect the improvement of the flame retardant properties of aluminum diethylphosphonate ultrafine powder in polymers. 4. The anti-migration modified aluminum diethylphosphinate obtained in this invention has a particle size D 10 The values ​​range from 1.144 to 1.311 μm, D 50 The values ​​range from 3.263 to 3.776 μm, D 90The micrometer value ranges from 12.630 to 14.085 μm. When nylon 66 is incorporated at a concentration of 6 wt%, the tensile strength of nylon 66 is 80.8–84.2 MPa, the flexural strength is 120.6–124.1 MPa, the flexural modulus is 3.1–3.3 GPa, and the notched impact strength is 11.8–14.9 kJ / m. 2 It has a limiting oxygen index of 34.3~35.6%, a UL-94V flame retardant rating of V-0, a dispersion uniformity of 0, a migration resistance of no exudation, and an acid corrosion loss of 0.07~0.1%. Attached Figure Description

[0012] Figure 1 The image is a scanning electron microscope image at 10,000x magnification of the anti-migration modified aluminum diethylphosphinate obtained in Example 1. Figure 2 The image is a scanning electron microscope image at 10,000x magnification of the anti-migration modified aluminum diethylphosphinate obtained in Example 2. Figure 3 The image is a scanning electron microscope image magnified 10,000 times of the migration-resistant modified aluminum diethylphosphinate obtained in Example 3. Detailed Implementation

[0013] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0014] Example 1: A method for preparing migration-resistant modified aluminum diethylphosphinate Step 1: Synthesis of aluminum diethylphosphinate Sodium diethylphosphonate aqueous solution was placed in a reaction vessel and heated to the reaction temperature. Phytic acid aqueous solution was added under low-speed stirring to adjust the pH of the liquid in the vessel to 2.8. Then, aluminum sulfate aqueous solution was added dropwise, while phytic acid aqueous solution was added dropwise and the dropwise rate was controlled to keep the pH of the liquid in the reaction vessel at 3.6. After the aluminum sulfate solution was added, the temperature was raised to the holding temperature. After the holding reaction was completed, the solution was filtered, washed and dried to obtain aluminum diethylphosphonate ultrafine powder. The sodium diethylphosphonate aqueous solution has a mass concentration of 33 wt%. The phytic acid aqueous solution has a phytic acid concentration of 30 wt%. The aluminum sulfate aqueous solution contained 19 wt% aluminum sulfate. The mass ratio of the sodium diethylphosphonate aqueous solution to the aluminum sulfate aqueous solution is 67:30. The reaction temperature is 60°C; The low-speed stirring has a stirring rate of 900 rpm; The aluminum sulfate aqueous solution was added at a rate of 35 g / min. The insulation temperature is 70℃; The heat preservation reaction is complete, and the heat preservation reaction time is 5 hours; The washing process involves washing twice with deionized water at a temperature of 90°C, with the mass of deionized water used in each wash being equal to the mass of the wet solid being washed. The drying process is carried out at a temperature of 110°C for 4 hours.

[0015] Step 2: One-time coating of hydroxyapatite Diethylphosphonate aluminum ultrafine powder, calcium chloride, and deionized water were placed in a dispersion vessel and strongly dispersed evenly. After the dispersion rate was reduced, diammonium hydrogen phosphate aqueous solution was added dropwise. After the addition was completed, the dispersion reaction was continued until complete. Then, the mixture was allowed to stand for aging, filtered, washed with water, and dried to obtain diethylphosphonate aluminum ultrafine powder coated with hydroxyapatite once. The mass ratio of the aluminum diethylphosphinate ultrafine powder, calcium chloride, deionized water, and diammonium hydrogen phosphate aqueous solution is 90:15:900:80. The mass concentration of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution is 11 wt%. The diammonium hydrogen phosphate aqueous solution was added dropwise at a rate of 150 g / min. The strong dispersion is uniform, with a dispersion rate of 7500 rpm and a dispersion time of 6 hours; The dispersion rate is reduced to 3000 rpm; After the dispersion reaction is complete, the dispersion reaction time is 2 hours. The static aging process lasts for 14 hours. The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.8. The drying process was carried out at a temperature of 95°C for 11 hours.

[0016] Step 3: Secondary coating with MQ silicone resin Hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, and phytic acid were added to a dispersion reactor and strongly dispersed until uniform. Then, the dispersion rate was reduced, and the temperature was raised to the reaction temperature. Tetraethyl orthosilicate was added, and the hydrolysis reaction was carried out under reflux. After the hydrolysis reaction was completed, hexamethyldisiloxane was added, and the dispersion reaction was continued until complete. After filtration, washing with water, and drying, the migration-resistant modified aluminum diethylphosphonate was obtained. The mass ratio of the hydroxyapatite-coated aluminum diethylphosphinic acid ultrafine powder, deionized water, anhydrous ethanol, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane is 110:70:270:17:30:11. The strong dispersion is uniform, with a dispersion rate of 8500 rpm and a dispersion time of 4 hours; The dispersion rate is reduced to 2000 rpm; The reaction temperature is 70°C; The hydrolysis reaction is to be completed in 0.5 hours. The continued dispersion reaction was complete, and the reaction time was 4 hours; The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.7. The drying process is carried out at a temperature of 90°C for 15 hours.

[0017] Example 2: A method for preparing migration-resistant modified aluminum diethylphosphinate Step 1: Synthesis of aluminum diethylphosphinate Sodium diethylphosphonate aqueous solution was placed in a reaction vessel and heated to the reaction temperature. Phytic acid aqueous solution was added under low-speed stirring to adjust the pH value of the liquid in the vessel to 2.3. Then, aluminum sulfate aqueous solution was added dropwise, while phytic acid aqueous solution was added dropwise and the dropwise rate was controlled to keep the pH value of the liquid in the reaction vessel at 2.3. After the aluminum sulfate solution was added, the temperature was raised to the holding temperature. After the holding reaction was completed, the solution was filtered, washed and dried to obtain aluminum diethylphosphonate ultrafine powder. The sodium diethylphosphonate aqueous solution has a mass concentration of 20 wt%. The phytic acid aqueous solution has a phytic acid concentration of 25 wt%. The aluminum sulfate aqueous solution has an aluminum sulfate concentration of 25 wt%. The mass ratio of the sodium diethylphosphonate aqueous solution to the aluminum sulfate aqueous solution is 20:30. The reaction temperature is 45°C; The low-speed stirring has a stirring rate of 600 rpm; The aluminum sulfate aqueous solution was added at a rate of 8 g / min. The insulation temperature is 65℃; The heat preservation reaction is complete, and the heat preservation reaction time is 6 hours; The washing process involves washing three times with deionized water at a temperature of 80°C, with the mass of deionized water used in each wash being equal to the mass of the wet solid being washed. The drying process is carried out at a temperature of 100°C for 6 hours.

[0018] Step 2: One-time coating of hydroxyapatite Diethylphosphonate aluminum ultrafine powder, calcium chloride, and deionized water were placed in a dispersion vessel and strongly dispersed evenly. After the dispersion rate was reduced, diammonium hydrogen phosphate aqueous solution was added dropwise. After the addition was completed, the dispersion reaction was continued until complete. Then, the mixture was allowed to stand for aging, filtered, washed with water, and dried to obtain diethylphosphonate aluminum ultrafine powder coated with hydroxyapatite once. The mass ratio of the aluminum diethylphosphinate ultrafine powder, calcium chloride, deionized water, and diammonium hydrogen phosphate aqueous solution is 55:4:360:40. The mass concentration of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution is 8 wt%. The diammonium hydrogen phosphate aqueous solution was added dropwise at a rate of 20 g / min. The strong dispersion is uniform, with a dispersion rate of 6000 rpm and a dispersion time of 7 hours; The dispersion rate is reduced to 2400 rpm; After the dispersion reaction is complete, the dispersion reaction time is 1 hour. The static aging process lasts for 10 hours. The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.5. The drying process involves a drying temperature of 110°C and a drying time of 9 hours.

[0019] Step 3: Secondary coating with MQ silicone resin Hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, and phytic acid were added to a dispersion reactor and strongly dispersed until uniform. Then, the dispersion rate was reduced, and the temperature was raised to the reaction temperature. Tetraethyl orthosilicate was added, and the hydrolysis reaction was carried out under reflux. After the hydrolysis reaction was completed, hexamethyldisiloxane was added, and the dispersion reaction was continued until complete. After filtration, washing with water, and drying, the migration-resistant modified aluminum diethylphosphonate was obtained. The mass ratio of the hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane is 55:20:150:4:15:5. The strong dispersion is uniform, with a dispersion rate of 7000 rpm and a dispersion time of 6 hours; The dispersion rate is reduced to 1500 rpm; The reaction temperature is 65°C; The hydrolysis reaction is to be completed in 0.3 hours. The continued dispersion reaction was completed within 2.5 hours; The water washing involves repeatedly washing the filter with deionized water until the pH of the washing solution is 6.4. The drying process involves a drying temperature of 80°C and a drying time of 18 hours.

[0020] Example 3: A method for preparing migration-resistant modified aluminum diethylphosphinate Step 1: Synthesis of aluminum diethylphosphinate Sodium diethylphosphonate aqueous solution was placed in a reaction vessel and heated to the reaction temperature. Phytic acid aqueous solution was added under low-speed stirring to adjust the pH of the liquid in the vessel to 3.6. Then, aluminum sulfate aqueous solution was added dropwise, while phytic acid aqueous solution was added dropwise and the dropwise rate was controlled to keep the pH of the liquid in the reaction vessel at 4. After the aluminum sulfate solution was added, the temperature was raised to the holding temperature. After the holding reaction was completed, the solution was filtered, washed and dried to obtain aluminum diethylphosphonate ultrafine powder. The sodium diethylphosphonate aqueous solution has a mass concentration of 40 wt%. The phytic acid aqueous solution has a phytic acid concentration of 35 wt%. The aluminum sulfate aqueous solution has an aluminum sulfate concentration of 35 wt%. The mass ratio of the sodium diethylphosphonate aqueous solution to the aluminum sulfate aqueous solution is 97:30. The reaction temperature is 65°C; The low-speed stirring has a stirring rate of 1300 rpm; The aluminum sulfate aqueous solution was added at a rate of 50 g / min. The insulation temperature is 75℃; The heat preservation reaction is complete, and the heat preservation reaction time is 3 hours; The washing process involves washing twice with deionized water at a temperature of 95°C, with the mass of deionized water used in each wash being equal to the mass of the wet solid being washed. The drying process was carried out at a temperature of 115°C for 3 hours.

[0021] Step 2: One-time coating of hydroxyapatite Diethylphosphonate aluminum ultrafine powder, calcium chloride, and deionized water were placed in a dispersion vessel and strongly dispersed evenly. After the dispersion rate was reduced, diammonium hydrogen phosphate aqueous solution was added dropwise. After the addition was completed, the dispersion reaction was continued until complete. Then, the mixture was allowed to stand for aging, filtered, washed with water, and dried to obtain diethylphosphonate aluminum ultrafine powder coated with hydroxyapatite once. The mass ratio of the aluminum diethylphosphinate ultrafine powder, calcium chloride, deionized water, and diammonium hydrogen phosphate aqueous solution is 150:30:1200:110. The mass concentration of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution is 17 wt%. The diammonium hydrogen phosphate aqueous solution was added dropwise at a rate of 300 g / min. The strong dispersion is uniform, with a dispersion rate of 9500 rpm and a dispersion time of 4 hours; The dispersion rate is reduced to 4000 rpm; After the dispersion reaction is complete, the dispersion reaction time is 2.5 hours. The static aging process lasts for 20 hours. The water washing involves repeatedly washing the filter with deionized water until the pH of the washing solution is 7. The drying process involves a drying temperature of 85°C and a drying time of 15 hours.

[0022] Step 3: Secondary coating with MQ silicone resin Hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, and phytic acid were added to a dispersion reactor and strongly dispersed until uniform. Then, the dispersion rate was reduced, and the temperature was raised to the reaction temperature. Tetraethyl orthosilicate was added, and the hydrolysis reaction was carried out under reflux. After the hydrolysis reaction was completed, hexamethyldisiloxane was added, and the dispersion reaction was continued until complete. After filtration, washing with water, and drying, the migration-resistant modified aluminum diethylphosphonate was obtained. The mass ratio of the hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane is 130:80:360:25:50:13. The strong dispersion is uniform, with a dispersion rate of 9500 rpm and a dispersion time of 3 hours; The dispersion rate is reduced to 3000 rpm; The reaction temperature is 80°C; The hydrolysis reaction is to be completed in 0.8 hours. The continued dispersion reaction was complete, and the reaction time was 5 hours; The water washing involves repeatedly washing the filtrate with deionized water until the pH of the washing solution is 6.9. The drying process is carried out at a temperature of 100°C for 13 hours.

[0023] Comparative Example 1: Based on Example 1, in step 1, the synthesis of aluminum diethylphosphonate, phytic acid aqueous solution was not added to control the pH value of the reaction system. The specific operation is as follows: Step 1: Synthesis of aluminum diethylphosphinate Sodium diethylphosphonate aqueous solution was placed in a reaction vessel and heated to the reaction temperature. Aluminum sulfate aqueous solution was added dropwise under low-speed stirring. After the aluminum sulfate solution was added, the temperature was raised to the holding temperature. After the holding reaction was completed, the solution was filtered, washed and dried to obtain aluminum diethylphosphonate ultrafine powder. Other operations were the same as in Example 1. Steps 2 and 3 are the same as in Example 1.

[0024] Comparative Example 2: Based on Example 1, step 2, the primary coating with hydroxyapatite, was omitted; only step 3, the secondary coating with MQ silicone resin, was performed. The specific operation is as follows: Step 1 is the same as in Example 1; Step 2 is omitted; hydroxyapatite is coated once. Step 3: Secondary coating with MQ silicone resin Ultrafine aluminum diethylphosphonate powder, deionized water, anhydrous ethanol, and phytic acid were added to a dispersion reactor and strongly dispersed until uniform. The dispersion rate was then reduced, and the temperature was raised to the reaction temperature. Tetraethyl orthosilicate was then added, and the hydrolysis reaction was carried out under reflux. After the hydrolysis reaction was completed, hexamethyldisiloxane was added, and the dispersion reaction was continued until complete. After filtration, washing with water, and drying, the migration-resistant modified aluminum diethylphosphonate was obtained.

[0025] Comparative Example 3: Based on Example 1, step 3, the secondary coating with MQ silicone resin, is omitted; only step 2, the primary coating with hydroxyapatite, is performed. The specific operation is as follows: Step 1 is the same as in Example 1; Step 2: One-time coating of hydroxyapatite Ultrafine aluminum diethylphosphonate powder, calcium chloride, and deionized water were placed in a dispersion vessel and strongly dispersed evenly. After the dispersion rate was reduced, diammonium hydrogen phosphate aqueous solution was added dropwise. After the addition was completed, the dispersion reaction was continued until complete. Then, the mixture was allowed to stand for aging, filtered, washed with water, and dried to obtain anti-migration modified aluminum diethylphosphonate. Other operations were the same as in Example 1. Step 3, MQ silicone resin secondary coating, is not performed.

[0026] Performance testing: The anti-migration modified aluminum diethylphosphonate obtained in Examples 1, 2, 3 and Comparative Examples 1, 2, 3 was added to Nylon 66 at an addition ratio of 6 wt%. The mixture was melted, extruded, granulated, and injection molded by a twin-screw extruder to obtain standard test samples. Nylon 66 standard test samples without aluminum diethylphosphonate were prepared in the same way as blank examples for testing mechanical properties and flame retardant properties. The samples were processed accordingly to facilitate testing of indicators such as dispersion uniformity, anti-migration and acid corrosion loss. In addition, the particle size of the anti-migration modified aluminum diethylphosphonate obtained in the three examples and three comparative examples was measured using a laser particle size analyzer. The specific test metrics and test methods are based on the following: 1. Tensile strength: Tested according to GB / T 1040.1-2025 Determination of tensile properties of plastics - Part 1: General rules; 2. Bending strength: Tested according to GB / T 9341-2008 Determination of bending properties of plastics; 3. Flexural modulus: Tested according to GB / T 9341-2008 Determination of Flexural Properties of Plastics; 4. Notched impact strength: Tested according to GB / T 1043.1-2008 Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact testing; 5. Limiting oxygen index and UL-94V flame retardant rating (tested according to GB / T 2408-2021 Determination of flammability of plastics by horizontal and vertical methods); 6. Evaluation of Dispersion Uniformity: Compress the tablets into 0.1~0.2mm thin tablets using a tablet press. Observe against the light to check for any powder pockets. Rate the uniformity on a scale of 0-10: 0 - no powder pockets, 1-2 - slightly present, 3 - ... 4 is obvious, 5 and above are more common, and 10 is the most frequent; 7. Evaluation of anti-migration properties: Place the prepared nylon 66 sample in a constant temperature and humidity chamber and place it at 85℃ and 85% relative humidity for 7 days. Visually observe the state of the sample surface after 7 days of high temperature and high humidity to see if white spots appear. 8. Evaluation of acid corrosion: A metal block is placed on the twin-screw die head. The high-temperature material comes into contact with the metal block at the die head. The amount of metal loss is tested after 100 kg of material is granulated. The higher the loss, the more severe the acid corrosion of the sample. The specific test results are shown in Table 1: Table 1 As can be seen from the data in Table 1, the anti-migration modified aluminum diethylphosphinate obtained in Examples 1-3, when added to Nylon 66 at a ratio of 6 wt%, exhibits excellent dispersion and anti-migration properties, significantly reducing acid corrosion. The limiting oxygen index of the blended Nylon 66 increases to over 34.3%, and the UL-94V flame retardant rating reaches V-0. Compared to the unblended blank, the mechanical properties show only a slight decrease. This indicates that the present invention, through two surface modification treatments—one primary coating with hydroxyapatite and a secondary coating with MQ silicone resin—prepares a highly resistant material. The ultrafine powder of aluminum diethylphosphinate exhibits good dispersion, anti-migration properties, and is free from acid corrosion. This powder significantly improves the flame retardant properties of polymers while having minimal impact on their mechanical properties. In Comparative Example 1, during step 1 and the synthesis of aluminum diethylphosphinate, no phytic acid aqueous solution was added to control the pH of the reaction system. Comparative Example 1 showed the largest particle size among all examples and comparative examples, while its mechanical properties and flame retardant properties were the worst among all examples and comparative examples. This indicates that the addition of phytic acid can effectively regulate the properties of aluminum diethylphosphinate. The precipitation rate of aluminum diethylphosphinate is controlled to prevent excessively rapid particle size growth, thus ensuring the final ultrafine powder of aluminum diethylphosphinate is obtained. Comparative Example 2 does not undergo primary coating with hydroxyapatite, but only MQ silicone resin coating. The dispersion uniformity and migration resistance of Comparative Example 2 are basically the same as those of Example 1. The mechanical properties and flame retardant properties of the nylon 66 blended in Comparative Example 2 are also basically similar to those of Example 1. However, the acid corrosion loss of Comparative Example 2 is significantly increased. This indicates that the main function of primary coating with hydroxyapatite is to neutralize the acidity of the ultrafine aluminum diethylphosphinate powder. Comparative Example 3, without secondary coating with MQ silicone resin, only underwent primary coating with hydroxyapatite. The dispersion uniformity and migration resistance of Comparative Example 3 were very poor, leading to a sharp decrease in the mechanical properties and flame retardant properties of the nylon 66 sample after incorporation. However, the acid corrosion loss of Comparative Example 3 was almost the same as that of Example 1. This indicates that the main function of hydroxyapatite coating is to reduce the acidity of the aluminum diethylphosphinate ultrafine powder, while the MQ silicone resin coating mainly promotes the uniform dispersion of the aluminum diethylphosphinate ultrafine powder and improves its migration resistance.

[0027] Appendix Figure 1 Appendix Figure 2 Appendix Figure 3 The images show scanning electron microscope (SEM) images at 10,000x magnification of the anti-migration modified aluminum diethylphosphonate obtained in Examples 1, 2, and 3, respectively. In all three images, the anti-migration modified aluminum diethylphosphonate exhibits an approximately spherical morphology with a relatively smooth surface, likely due to the outermost layer of MQ silicone resin. The particle size in most of the three images is within 3-5 μm, which is consistent with D... 50The values ​​are roughly consistent between 3.263 and 3.776 μm, which also intuitively illustrates that the present invention has obtained ultrafine aluminum diethylphosphonate powder with a relatively fine particle size.

[0028] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing anti-migration modified aluminum diethylphosphinate, characterized in that: The method for preparing the anti-migration modified aluminum diethylphosphinate includes three steps: synthesizing aluminum diethylphosphinate ultrafine powder, primary coating with hydroxyapatite, and secondary coating with MQ silicone resin. The synthesis of aluminum diethylphosphonate involves placing an aqueous solution of sodium diethylphosphonate into a reaction vessel, heating it to the reaction temperature, adding an aqueous solution of phytic acid while stirring at low speed to adjust the pH of the liquid in the vessel to 2.3-3.6, then adding an aqueous solution of aluminum sulfate dropwise while simultaneously adding an aqueous solution of phytic acid dropwise at a controlled rate to maintain the pH of the liquid in the reaction vessel at 2.3-4. After the aluminum sulfate solution has been added, the temperature is raised to the holding temperature. After the holding reaction is complete, the product is filtered, washed, and dried to obtain ultrafine aluminum diethylphosphonate powder. The hydroxyapatite one-time coating is achieved by placing diethylphosphonic aluminum ultrafine powder, calcium chloride, and deionized water into a dispersion vessel, dispersing them vigorously and evenly, reducing the dispersion rate, adding diammonium hydrogen phosphate aqueous solution dropwise, continuing the dispersion reaction until complete, and then allowing them to stand for aging, filtering, washing with water, and drying to obtain hydroxyapatite one-time coated diethylphosphonic aluminum ultrafine powder. The MQ silicone resin secondary coating process involves adding ultrafine diethylphosphonic acid powder coated with hydroxyapatite, deionized water, anhydrous ethanol, and phytic acid to a dispersion reactor. After strong and uniform dispersion, the dispersion rate is reduced, and the temperature is raised to the reaction temperature. Tetraethyl orthosilicate is then added, and the hydrolysis reaction is carried out under reflux. After the hydrolysis reaction is completed, hexamethyldisiloxane is added, and the dispersion reaction is continued until complete. Finally, the mixture is filtered, washed with water, and dried to obtain anti-migration modified diethylphosphonic acid.

2. The method for preparing anti-migration modified aluminum diethylphosphinate according to claim 1, characterized in that: The sodium diethylphosphonate aqueous solution has a mass concentration of 20-40 wt%. The phytic acid aqueous solution contains 25-35 wt% phytic acid. The aluminum sulfate aqueous solution has a mass concentration of 25-35 wt%. The mass ratio of sodium diethylphosphonate aqueous solution to aluminum sulfate aqueous solution is 20~97:30; The mass concentration of diammonium hydrogen phosphate in the aqueous solution of diammonium hydrogen phosphate is 8~17wt%.

3. The method for preparing anti-migration modified aluminum diethylphosphinate according to claim 1, characterized in that: The mass ratio of the aluminum diethylphosphinate ultrafine powder, calcium chloride, deionized water, and diammonium hydrogen phosphate aqueous solution is 55~150:4~30:360~1200:40~110; The diammonium hydrogen phosphate aqueous solution is added dropwise at a rate of 20-300 g / min.

4. The method for preparing anti-migration modified aluminum diethylphosphinate according to claim 1, characterized in that: The mass ratio of the hydroxyapatite-coated aluminum diethylphosphonate ultrafine powder, deionized water, anhydrous ethanol, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane is 55~130:20~80:150~360:4~25:15~50:5~13.

5. The anti-migration modified aluminum diethylphosphinate obtained by any one of the preparation methods according to claims 1-4, characterized in that: The obtained migration-resistant modified aluminum diethylphosphinate, when incorporated into nylon 66 at a dosage of 6 wt%, resulted in nylon 66 exhibiting a tensile strength of 80.8–84.2 MPa, a flexural strength of 120.6–124.1 MPa, a flexural modulus of 3.1–3.3 GPa, and a notched impact strength of 11.8–14.9 kJ / m. 2 It has a limiting oxygen index of 34.3~35.6%, a UL-94V flame retardant rating of V-0, a dispersion uniformity of 0, a migration resistance of no exudation, and an acid corrosion loss of 0.07~0.1%.

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