Modified phosphorus-containing flame retardants, flame-retardant polyamides, flame-retardant polyurethanes, and flame-retardant polyolefins

Abstract

The application discloses a modified phosphorus-containing flame retardant, a preparation method and application thereof. The modified phosphorus-containing flame retardant comprises a phosphorus-containing flame retardant and a coating layer coated on the phosphorus-containing flame retardant, and the coating layer comprises a polyelectrolyte layer and a polyurethane layer coated on the phosphorus-containing flame retardant in sequence. Preferably, the polyurethane in the polyurethane layer is a cured polyurethane. The preparation method comprises the step of coating the phosphorus-containing flame retardant with polyelectrolyte and polyurethane in sequence to prepare the polyelectrolyte layer and the polyurethane layer. The coating is preferably carried out in a solvent containing a dispersant and an inorganic salt. The phosphorus-containing flame retardant of the application has obviously improved bulk density and thermal stability after coating modification, and can be used as a flame retardant for resins such as polyamide, polyurethane or polyolefin.

Description

[0001] The present application is a divisional application of a patent application with the application date of August 29, 2022, the application number of 202211039226.3, and the invention name of modified phosphorus-containing flame retardant and its preparation method and application. TECHNICAL FIELD

[0002] The present application relates to a modified phosphorus-containing flame retardant and its preparation method and application. BACKGROUND

[0003] With the rapid development of the basic chemical industry and the gradual improvement of national safety fire prevention laws and regulations, the development trend in the future will be the flame retardation in the field of engineering plastics, which will further promote the overall improvement of the entire flame retardant industry. At present, the flame retardant in China is still dominated by halogen-based flame retardants, but halogen-based flame retardants are gradually replaced by other flame retardants due to their safety and other reasons. In the future, halogen-free flame retardants will have broader market and development opportunities.

[0004] As a halogen-free flame retardant, phosphorus-containing flame retardant has good thermal stability, long-lasting flame retardant effect, low smoke and low toxicity, low addition amount, high flame retardant efficiency, and is suitable for various types of high molecular materials, etc. In recent years, it has been widely applied to various engineering plastic substrates for flame retardation.

[0005] In order to achieve a certain flame retardant effect in the flame retardant substrate, a large amount of small particle size flame retardant powder is often added to the engineering plastic, and a large amount of dust will be generated in the process, which will damage the environment and be harmful to the health of the processing workers. In addition, due to the small particle size and large specific surface area of the phosphorus-containing flame retardant, the interfacial compatibility between the phosphorus-containing flame retardant and the substrate is poor during the addition to different types of engineering plastic substrates, which leads to uneven dispersion of the flame retardant powder in the substrate, and defects in the performance of the composite material. In addition, the thermal stability of the phosphorus-containing flame retardant needs to be improved, for example, during the processing of high-temperature nylon, a certain amount of phosphorus-containing flame retardant will decompose under high temperature conditions, thereby reducing the flame retardant efficiency, and even toxic gases will be generated during the processing, limiting its application range.

[0006] It is known that Chinese patent document CN101376811A discloses a polyurethane microencapsulated inorganic phosphorus-containing flame retardant, which is prepared by in-situ polymerization of polyurethane as the core and the polyurethane produced by polymerization of polyether diol and diisocyanate as the main monomer and crosslinking monomer pentaerythritol. The flame retardant has improved water resistance and flame retardant performance, but its bulk density and thermal stability are still not high enough.

[0007] It is also known that Chinese patent document CN114181433A discloses a polyurethane-based ionic liquid polymer-coated red phosphorus flame retardant material, which is prepared by in-situ polymerization using red phosphorus, a polyhydroxy compound, an ionic liquid, and isocyanate as raw materials. However, the bulk density and thermal stability of the material are still not high enough and need to be improved.

[0008] It is also known that Chinese patent document CN114163688A discloses a preparation method of clay layer self-assembled coated ammonium polyphosphate, which repeatedly disperses the purified ammonium polyphosphate in a positive electrolyte solution and a negative electrolyte solution, and coats the ammonium polyphosphate by self-assembly. The positive electrolyte is one or more of polyethyleneimine, polyacrylamide, chitosan, polyallyl ammonium chloride, polyvinylamine, and gelatin, and the negative electrolyte is one or more of nanoscale montmorillonite, halloysite, and kaolin. The flame retardancy of the coated ammonium polyphosphate is improved, but its bulk density and thermal stability still need to be improved.

[0009] It is also known that Chinese patent document CN111961254A discloses a preparation method of modified aluminum hypophosphite flame retardant, which uses aluminum hydroxide, hypophosphorous acid, silane coupling agent, and polyethylene as raw materials in a kneader to synthesize aluminum hypophosphite through neutralization reaction, and obtains the modified aluminum hypophosphite flame retardant through thermal coating treatment of the silane coupling agent and polyethylene. The modified flame retardant product obtained by this method has a relatively uniform particle size, but its bulk density and thermal stability still need to be improved. SUMMARY

[0010] In view of the shortcomings and deficiencies of the prior art, the present application provides a modified phosphorus-containing flame retardant, which has a high bulk density and improved thermal stability, and when used for plastic flame retardation, the flame retardancy is also improved.

[0011] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0012] A modified phosphorus-containing flame retardant, which comprises a phosphorus-containing flame retardant and a coating layer coated on the phosphorus-containing flame retardant, the coating layer comprising a polyelectrolyte layer and a polyurethane layer coated on the phosphorus-containing flame retardant in sequence.

[0013] In some embodiments of the present application, the polyelectrolyte in the polyelectrolyte layer is selected from a combination of one or more of sodium polyacrylate, sodium polystyrene sulfonate, polydiallyldimethylammonium chloride, sodium polyvinyl sulfonate, polyphosphate, polyacrylamide hydrochloride, and polyethyleneimine hydrochloride.

[0014] In some embodiments of the present application, the polyurethane in the polyurethane layer is selected from the group consisting of polyether polyurethane, polyester polyurethane, and a combination of one or more of polyether-polyester hybrid polyurethane. Polyurethane is generally polymerized from a polyol and a diisocyanate, wherein the polyol can be a polyether polyol, a polyester polyol, or a hybrid polyol, and the diisocyanate is preferably toluene diisocyanate (TDI) or hexamethylene diisocyanate (HDI).

[0015] In some embodiments of the present application, the polyurethane is a cured polyurethane.

[0016] In some embodiments of the present application, the cured polyurethane is obtained by curing a polyurethane and a curing agent.

[0017] In some embodiments of the present application, the curing agent is selected from the group consisting of a mono-isocyanate, a di-isocyanate, and a combination of one or more of poly-isocyanates.

[0018] In some embodiments of the present application, the di-isocyanate is selected from the group consisting of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI).

[0019] In some embodiments of the present application, the phosphorus-containing flame retardant is a phosphorus-containing aluminum salt flame retardant.

[0020] In some embodiments of the present application, the phosphorus-containing aluminum salt flame retardant is selected from the group consisting of a combination of one or more of aluminum hypophosphite, aluminum phosphite, polymeric aluminum phosphite, and alkyl aluminum hypophosphite, wherein the alkyl group in the alkyl aluminum hypophosphite is a C1-C6 alkyl group.

[0021] In some embodiments of the present application, the alkyl aluminum hypophosphite is selected from the group consisting of a combination of one or more of ethyl aluminum hypophosphite, butyl aluminum hypophosphite, diethyl aluminum hypophosphite, and dibutyl aluminum hypophosphite. In some embodiments of the present application, the modified phosphorus-containing flame retardant is prepared by coating a polyelectrolyte on the phosphorus-containing flame retardant, and then coating a polyurethane on the polyelectrolyte in the presence of a dispersant in a solvent.

[0022] In some embodiments of the present application, the mass ratio of the phosphorus-containing flame retardant, the polyelectrolyte, and the polyurethane is 200-600: 1-10: 1-30.

[0023] In some embodiments of the present application, the dispersant is selected from the group consisting of a combination of one or more of polyvinylpyrrolidone, polyacrylamide, a non-ionic surfactant, and an anionic surfactant.

[0024] In some embodiments of the present application, the polyacrylamide is an anionic polyacrylamide.

[0025] In some embodiments of the present application, the nonionic surfactant is selected from the group consisting of a combination of one or more of a fatty alcohol polyoxyethylene ether, an alkyl phenol polyoxyethylene ether, a fatty acid polyoxyethylene ester, a polyoxyethylene alkyl amine, a polyoxyethylene alkyl alcohol amide, and a polyether.

[0026] In some embodiments of the present application, the anionic surfactant is selected from the group consisting of a combination of one or more of a fatty acid salt, a sulfonic acid salt, a sulfate salt, a phosphate salt, an amino acid salt, a phenol salt, an enolate salt, and a ketosulfonamide salt.

[0027] The present inventors have found that phosphorus-containing flame retardant powder has hydrophobic properties, a large surface energy, and a large specific surface area, which results in a large distance between phosphorus-containing flame retardant powder particles, a fluffy powder, and a small bulk density. The present application coats a polyelectrolyte layer on the surface of the phosphorus-containing flame retardant, and then coats a polyurethane layer. The polyurethane structure contains hydrophilic groups such as amino and carbonyl groups, which are more hydrophilic than the phosphorus-containing flame retardant powder, which is beneficial to reducing the surface energy and reducing the air adsorbed on the surface of the powder, thereby increasing the bulk density of the powder. The polyelectrolyte layer and the polyurethane layer interact through van der Waals forces, electrostatic forces, and hydrogen bonds. The above interactions can effectively achieve uniform coating of the polymer on the surface of the phosphorus-containing flame retardant. The polyurethane layer on the coating is further cured by a curing agent, and the coating layer becomes more dense and forms a more stable interfacial force with the phosphorus-containing flame retardant powder, thereby significantly improving the bulk density and thermal stability of the modified phosphorus-containing flame retardant. This can improve the harm of dust during the processing of the flame retardant powder, and the improvement in thermal stability can improve the flame retardant efficiency when the flame retardant is used in a polymer matrix material.

[0028] The present application also provides a method for preparing the modified phosphorus-containing flame retardant described above, which comprises the step of sequentially coating the phosphorus-containing flame retardant with a polyelectrolyte and a polyurethane to prepare the polyelectrolyte layer and the polyurethane layer.

[0029] In some embodiments of the present application, the coating is carried out in a solvent containing a dispersant and an inorganic salt.

[0030] In some embodiments of the present application, the inorganic salt is selected from the group consisting of a combination of one or more of sodium sulfate, potassium sulfate, and aluminum sulfate.

[0031] In some embodiments of the present application, the solvent is selected from the group consisting of a combination of one or more of water, methanol, ethanol, propanol, and acetone.

[0032] In some embodiments of the present application, the molar concentration of the inorganic salt in the solvent is 0.05-1.0 mol / L.

[0033] In some embodiments of the present application, the mass ratio of the phosphorus-containing flame retardant to the solvent is 1:2-1:10.

[0034] In some embodiments of the present application, the mass concentration of the dispersant in the solvent is 0.1-3 g / L.

[0035] In some embodiments of the present application, the preparation method comprises the following steps: 1) dispersing the phosphorus-containing flame retardant, dispersant and inorganic salt into the solvent, adding a polyelectrolyte to coat a polyelectrolyte layer on the phosphorus-containing flame retardant; 2) heating the solvent to 40-70℃, adding an aqueous polyurethane into the solvent to coat a polyurethane layer on the polyelectrolyte layer.

[0036] In some embodiments of the present application, the step 2) specifically comprises heating the solvent to 40-70℃, adding an aqueous polyurethane into the solvent dropwise, stirring for 0.5-3 h, adding a curing agent into the solvent, and coating a cured polyurethane layer on the polyelectrolyte layer.

[0037] In some embodiments of the present application, the preparation method comprises the following steps: 1) dispersing the phosphorus-containing flame retardant and dispersant into the solvent, stirring for 0.5-2 h, adding the inorganic salt into the solvent again, and stirring for 0.5-2 h to coat a polyelectrolyte layer on the phosphorus-containing flame retardant; 2) heating the solvent to 40-70℃, adding an aqueous polyurethane into the solvent, stirring for 0.5-3 h, adding a curing agent into the solvent, heating the solvent to 60-100℃, and performing a curing reaction for 1-5 h to coat a cured polyurethane layer on the polyelectrolyte layer.

[0038] In some embodiments of the present application, the aqueous polyurethane is a polyurethane emulsion.

[0039] In some embodiments of the present application, the preparation method further comprises post-processing steps of cooling, centrifugation, water washing and drying.

[0040] The present application also provides a use of the modified phosphorus-containing flame retardant as described above as a flame retardant for polyamide, polyurethane or polyolefin.

[0041] The present application also provides a flame retardant composition comprising the modified phosphorus-containing flame retardant as described above.

[0042] The present application also provides a halogen-free flame-retardant polyamide comprising polyamide and a flame retardant, wherein the flame retardant comprises the modified phosphorus-containing flame retardant as described above.

[0043] In some embodiments of the present application, the flame retardant further comprises a combination of one or more of zinc borate, melamine polyphosphate and melamine cyanurate.

[0044] In some embodiments of the present application, the mass ratio of the modified phosphorus-containing flame retardant, zinc borate, melamine polyphosphate and melamine cyanurate is 10-15:0-9.8:0-8.6:0-9.5.

[0045] In some embodiments of the present application, the mass ratio of the modified phosphorus-containing flame retardant, zinc borate, melamine polyphosphate and melamine cyanurate is 10-15:0.2-2.5:3.5-5:4.5-6.

[0046] In some embodiments of the present application, the halogen-free flame-retardant polyamide comprises the following components by weight parts: polyamide 40-85 parts, modified phosphorus-containing flame retardant 5-15 parts, other flame retardant 2-12 parts, toughening agent 0.2-5 parts, antioxidant 0.1-6 parts, coupling agent 0.1-4 parts.

[0047] In some embodiments of the present application, the polyamide is selected from a combination of one or more of PA6, PA66, PA1010, PA-610, PA-612, PA-12, PA-46, PA-6T and PA-9T; and / or, and / or, the other flame retardant is selected from a combination of one or more of zinc borate, melamine polyphosphate, melamine cyanurate and ammonium polyphosphate; and / or, the toughening agent is selected from a combination of one or more of POE grafted maleic anhydride, EPDM grafted maleic anhydride; and / or, the antioxidant is selected from a combination of one or more of phenolic antioxidant 1098, 1076, 1010, 1024, 9228, BHT, phosphorus antioxidant 168, 636, 626, 450, 686, sulfide antioxidant DLTP, DSTP; and / or, the coupling agent is selected from a combination of one or more of silane coupling agent, aluminate coupling agent and titanate coupling agent.

[0048] Compared with the prior art, the present application has the following advantages:

[0049] The modified phosphorus-containing flame retardant of the present application comprises a polyelectrolyte layer and a polyurethane layer successively coated on the phosphorus-containing flame retardant. Since the polyurethane layer is more hydrophilic than the phosphorus-containing flame retardant, it can reduce the surface energy, thereby increasing the bulk density after coating modification, effectively improving the environmental impact and harm to human health of dust during the processing of flame retardant powder. The thermal stability of the phosphorus-containing flame retardant after coating modification is significantly improved, which can be used as a flame retardant for polyamide, polyurethane or polyolefin materials alone, or compounded with other flame retardants as a compounded flame retardant for the aforementioned polymer materials, so that the polymer materials have good flame retardant properties. Attached Figure Description

[0050] Figure 1 The Fourier transform infrared spectrum of diethylaluminum hypophosphite before coating modification in Example 2;

[0051] Figure 2 The Fourier transform infrared spectrum of the modified aluminum diethyl hypophosphite in Example 2 is shown below.

[0052] Figure 3 The image shows the SEM image of the coated modified aluminum diethylphosphite obtained in Example 2. Detailed Implementation

[0053] This invention provides a modified phosphorus-containing flame retardant. The main innovation lies in the sequential coating of a polyelectrolyte layer and a polyurethane layer onto the phosphorus-containing flame retardant. Because the polyurethane structure contains hydrophilic groups such as carbonyl groups, it is more hydrophilic than the phosphorus-containing flame retardant powder, which helps to reduce its surface energy, thereby reducing the air adsorbed on the powder surface and increasing the powder's bulk density. Furthermore, there are van der Waals forces, electrostatic forces, and hydrogen bonds between the coated polyelectrolyte layer and the polyurethane layer. The synergy of these forces effectively achieves uniform coating of the phosphorus-containing flame retardant surface by the polymer. After curing with a curing agent, the coating becomes denser and forms a more stable interfacial force with the phosphorus-containing flame retardant powder, thus significantly improving the bulk density and thermal stability of the modified phosphorus-containing flame retardant.

[0054] Another innovation of this invention lies in the process for preparing the modified phosphorus-containing flame retardant. This invention coats the modified phosphorus-containing flame retardant in a solvent phase, achieving uniform and dense coating of polyelectrolytes and polyurethane on the surface of the phosphorus-containing flame retardant. Furthermore, the modification process is simple and operates under mild conditions. This invention adds inorganic salts to the solvent phase of the coating process to adjust its ionic strength, which is beneficial for improving the utilization rate of the polyelectrolytes and polyurethane during coating.

[0055] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0056] Example 1

[0057] This embodiment provides a coated modified aluminum diethylphosphite, the preparation process of which is as follows:

[0058] 1.2 g of polyvinylpyrrolidone was dissolved in 1.25 L of water to obtain an aqueous solution. Under high-speed stirring, 200 g of aluminum diethylphosphite (D50 2.72 μm, D95 8.21 μm, bulk density 0.4 g / cm³) was added to the aqueous solution. 3 The mixture was stirred at room temperature for 2 hours to obtain a solution. A certain amount of sodium sulfate was then added to the solution to achieve an ionic strength of 0.1 M. 1.25 g of polydiallyl dimethyl ammonium chloride (PDDA) was added and stirred for 0.5 hours. 500 mL of a 3.5 g / L polyester-based waterborne polyurethane was added dropwise to the solution. The temperature was raised to 50°C and stirred at a constant speed for 2 hours, then the temperature was lowered to room temperature. 83 mL of a 1.5 g / L hexamethylene diisocyanate aqueous solution was added. The solution was first heated to 60°C and held for 1 hour, then heated to 85°C and held for 3 hours for curing. After the reaction, the solution was centrifuged to remove moisture, and after three centrifugal washes, it was dried in an oven at 120°C to obtain coated modified aluminum diethylphosphite.

[0059] Example 2

[0060] This embodiment provides a coated modified aluminum diethylphosphite, the preparation process of which is as follows:

[0061] 1.37 g of polyoxyethylene alkylolamide was dissolved in 2 L of water to obtain an aqueous solution. Under high-speed stirring, 450 g of aluminum diethylphosphite (D50 of 2.72 μm, D95 of 8.21 μm, and bulk density of 0.4 g / cm³) was added to the aqueous solution. 3 The mixture was stirred at room temperature for 2 hours to obtain a solution. A certain amount of sodium sulfate was then added to the solution to achieve an ionic strength of 0.25 M. 2.15 g of sodium polystyrene sulfonate was added and stirred for 0.5 hours. 200 mL of a 10.5 g / L polyester-based waterborne polyurethane was added dropwise to the solution, and the temperature was raised to 40°C and stirred at a constant speed for 2 hours. The temperature was then lowered to room temperature. 200 mL of a 1.5 g / L hexamethylene diisocyanate aqueous solution was added, and the solution was first heated to 60°C and held for 1 hour, then heated to 85°C and held for 3 hours to allow for curing. After the reaction, the solution was centrifuged to remove moisture, and after three centrifugal washes, it was dried in an oven at 120°C to obtain coated modified aluminum diethylphosphite.

[0062] The Fourier transform infrared spectra before and after the modification with diethylaluminum hypophosphite coating are as follows: Figures 1-2 As shown, from Figures 1-2 The comparison shows that, after being coated with polyurethane, diethylaluminum hypophosphite has a growth rate of 1726.8 cm⁻¹. -1A C=O double bond vibration absorption peak was detected at a certain wavelength, indicating that polyurethane was effectively modified onto the surface of the diethylaluminum hypophosphite powder. The SEM spectrum of the modified diethylaluminum hypophosphite is shown below. Figure 3 As shown, after modification with sodium polystyrene sulfonate and polyurethane, the surface roughness of aluminum diethyl phosphite is reduced and the surface becomes smoother.

[0063] Example 3

[0064] This embodiment provides a coated modified aluminum diethylphosphite, the preparation process of which is as follows:

[0065] 7.8 g of anionic polyacrylamide was dissolved in 10 L of water to obtain an aqueous solution. Under high-speed stirring, 4 kg of aluminum diethylphosphite (D50 of 2.72 μm, D95 of 8.21 μm, and bulk density of 0.4 g / cm³) was added to the aqueous solution. 3 The mixture was stirred at room temperature for 2 hours to obtain a solution. A certain amount of aluminum sulfate was then added to the solution to achieve an ionic strength of 0.1 M. 18.5 g of polyethyleneimine hydrochloride was added and stirred for 0.5 hours. 800 mL of a 50.8 g / L polyester-based waterborne polyurethane was added dropwise to the mixture, and the temperature was raised to 40°C and stirred at a constant speed for 2 hours. The temperature was then lowered to room temperature. 200 mL of a 1.5 g / L isophorone diisocyanate aqueous solution was added, and the mixture was first heated to 60°C and held for 1 hour, then heated to 85°C and held for 3 hours to allow for curing. After the reaction, the mixture was centrifuged to remove moisture, and after three centrifugal washes, it was dried in an oven at 120°C to obtain coated modified aluminum diethylphosphite.

[0066] Example 4

[0067] This embodiment provides a coated modified dibutyl aluminum hypophosphite. The preparation process of this embodiment is basically the same as that of Example 1, except that: the diethyl aluminum hypophosphite (D50 is 2.72 μm, D95 is 8.21 μm, and bulk density is 0.4 g / cm³) from Example 1 is coated with a modified dibutyl aluminum hypophosphite. 3 Replace with dibutylaluminum hypophosphite (D50 is 6.17 μm, D95 is 13.21 μm, and bulk density is 0.3 g / cm³). 3 ).

[0068] Comparative Example 1

[0069] This comparative example provides a coated and modified aluminum diethylphosphite, the preparation process of which is as follows:

[0070] 1.2 g of polyvinylpyrrolidone was dissolved in 1.25 L of water to obtain an aqueous solution. Under high-speed stirring, 200 g of aluminum diethylphosphite (D50 2.72 μm, D95 8.21 μm, bulk density 0.4 g / cm³) was added to the aqueous solution.3 ), stirred for 2h at room temperature to obtain a mixture. A certain amount of sodium sulfate was added to the mixture to make the ionic strength of the mixture 0.1M. 500mL of polyester type waterborne polyurethane with a concentration of 3.5g / L was added dropwise to the above mixture, the temperature was raised to 50℃, and stirred at a uniform speed for 2h, and then the temperature was reduced to room temperature. 83mL of aqueous solution of hexamethylene diisocyanate with a concentration of 1.5g / L was added, and the temperature was first raised to 60℃ for 1h, and then raised to 85℃ for 3h for curing reaction. After the reaction was completed, the water was removed by centrifugation, and after three times of centrifugal water washing, it was put into an oven and dried at 120℃ to obtain the coated modified aluminum diethyl phosphite.

[0071] Comparative Example 2

[0072] This comparative example provides a coated modified aluminum diethyl phosphite, which is prepared as follows:

[0073] 1.2g of polyvinylpyrrolidone was dissolved in 1.25L of water to obtain an aqueous solution, and 200g of diethyl phosphite (D50 of 2.72 microns, D95 of 8.21 microns, and bulk density of 0.4g / cm 3 ), stirred for 2h at room temperature to obtain a mixture. A certain amount of sodium sulfate was added to the mixture to make the ionic strength of the mixture 0.1M, and 1.25g of polydiallyldimethylammonium chloride (PDDA) was added as a coating polymer layer and stirred for 0.5h. 83mL of aqueous solution of hexamethylene diisocyanate with a concentration of 1.5g / L was added, and the temperature was first raised to 60℃ for 1h, and then raised to 85℃ for 3h. After the reaction was completed, the water was removed by centrifugation, and after three times of centrifugal water washing, it was put into an oven and dried at 120℃ to obtain the coated modified aluminum diethyl phosphite.

[0074] The D50 and D95 particle sizes and bulk densities of the modified flame retardants in Examples 1-4 and Comparative Examples 1-2 were tested by laser particle size analyzer and multifunctional powder bulk density instrument, respectively, and the thermal weight loss temperature at different thermal weight loss percentages was tested by TGA. Among them, the particle size and bulk density results are shown in Table 1.

[0075] Table 1 Particle size and bulk density of modified flame retardants in Examples 1-4 and Comparative Examples 1-2

[0076]

[0077] It can be seen that the bulk density of the phosphorus-containing flame retardant after coating modification of the application is obviously improved compared with before modification, while in Comparative Examples 1 and 2, only the polyelectrolyte layer or the polyurethane layer is used to coat the phosphorus-containing flame retardant, the bulk density of the modified phosphorus-containing flame retardant remains basically unchanged and cannot be improved. The particle size of the phosphorus-containing flame retardant after coating modification of the application is not much different from before modification, and the thickness of the coating layer is between tens of nanometers and hundreds of nanometers. The application can realize the regulation of the thickness of the coating layer at the nanometer level. Since the coating layer is thin, the particle size of the modified phosphorus-containing flame retardant is not greatly increased. When used in resin materials later, the flame retardant effect of the modified phosphorus-containing flame retardant can be ensured, and at the same time, the compatibility with the resin material is better, and the comprehensive mechanical properties of the resin material can be improved.

[0078] The thermal weight loss temperatures of the modified flame retardants in Examples 1-4 and Comparative Examples 1-2 are shown in Table 2.

[0079] Table 2 Thermal weight loss temperatures of modified flame retardants in Examples 1-4 and Comparative Examples 1-2

[0080]

[0081] It can be seen that the thermal stability of the phosphorus-containing flame retardant after coating modification of the application is obviously improved, while in Comparative Examples 1 and 2, only the polyelectrolyte layer or the polyurethane layer is used to coat the phosphorus-containing flame retardant, the thermal stability of the modified phosphorus-containing flame retardant remains basically unchanged.

[0082] Examples 5-10

[0083] The coated modified aluminum diethyl phosphite in Examples 1-3 is used for flame retardation of PA66, and the preparation process of the flame-retardant PA66 material is as follows: the coated modified aluminum diethyl phosphite in Examples 1-3 and other raw materials (see Table 3) are weighed in parts by weight, poured into a high-speed mixer for mixing, stirred at a speed of 900 r / min for 10 minutes, and then granulated by a twin-screw extruder to obtain a halogen-free flame-retardant reinforced PA66 material, which is dried and injection molded into a standard sample.

[0084] Comparative Examples 3-5

[0085] The uncoated modified pure aluminum diethyl phosphite is used for flame retardation of PA66, and the preparation process of the flame-retardant PA66 material is the same as that of Examples 5-10, and the raw material composition is shown in Table 3.

[0086] Table 3 Raw material composition of Examples 7-9 and Comparative Example 3

[0087]

[0088]

[0089] The mechanical and flame retardant properties of the PA66 materials in Examples 5-10 and Comparative Examples 3-5 were tested using methods such as impact strength (GB / T1843-2008), flexural strength (GB / T9341-2008), tensile strength (GB / T1040.2-2006), oxygen index (GB / T2406.2-2009), and vertical burning (GB / T2408-2008). The results are shown in Table 4.

[0090] Table 4 Performance test results of Examples 7-9 and Comparative Examples 3-5

[0091]

[0092] It is evident that when the modified phosphorus-containing flame retardant of the present invention is used in polyamide materials, it can ensure the mechanical properties of the polyamide materials. At the same time, compared with the uncoated modified phosphorus-containing flame retardant, it can improve the flame retardant properties of polyamide materials to a certain extent, such as improving the oxygen index and whiteness of the polyamide materials.

[0093] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0094] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A modified phosphorus-containing flame retardant, said modified phosphorus-containing flame retardant comprising a phosphorus-containing flame retardant and a coating layer coating the phosphorus-containing flame retardant, characterized in that: The coating layer comprises a polyelectrolyte layer and a polyurethane layer sequentially coated on the phosphorus-containing flame retardant.

2. The modified phosphorus-containing flame retardant according to claim 1, characterized in that: The polyelectrolyte in the polyelectrolyte layer is selected from one or more combinations of sodium polyacrylate, sodium polystyrene sulfonate, polydiallyldimethylammonium chloride, sodium polyethylene sulfonate, polyphosphate, polyacrylamide hydrochloride, and polyethyleneimine hydrochloride.

3. The modified phosphorus-containing flame retardant according to claim 1, characterized in that: The polyurethane in the polyurethane layer is selected from one or more combinations of polyether-type polyurethane, polyester-type polyurethane, and polyether-polyester hybrid polyurethane; and / or, the polyurethane in the polyurethane layer is cured polyurethane.

4. The modified phosphorus-containing flame retardant according to claim 1, characterized in that: The phosphorus-containing flame retardant is selected from one or more combinations of phosphorus-aluminum salt flame retardants, melamine phosphate, melamine cyanurate, ammonium polyphosphate, and melamine pyrophosphate.

5. The modified phosphorus-containing flame retardant according to claim 4, characterized in that: The phosphorus-containing aluminum salt flame retardant is selected from one or more combinations of aluminum hypophosphite, aluminum phosphite, polyaluminum phosphite and alkyl aluminum hypophosphite, wherein the alkyl group in the alkyl aluminum hypophosphite is a C1-C6 alkyl group.

6. The modified phosphorus-containing flame retardant according to claim 1, characterized in that: The mass ratio of the phosphorus-containing flame retardant, polyelectrolyte, and polyurethane is 200-600:1-10:1-30.

7. A halogen-free flame-retardant polyurethane, comprising polyurethane and a flame retardant, characterized in that: The flame retardant includes the modified phosphorus-containing flame retardant according to any one of claims 1-6.

8. A halogen-free flame-retardant polyolefin, comprising a polyolefin and a flame retardant, characterized in that: The flame retardant includes the modified phosphorus-containing flame retardant according to any one of claims 1-6.

9. A halogen-free flame-retardant polyamide, comprising polyamide and a flame retardant, characterized in that: The flame retardant includes the modified phosphorus-containing flame retardant according to any one of claims 1-6.

10. The halogen-free flame-retardant polyamide according to claim 9, characterized in that: The flame retardant also includes one or more combinations of zinc borate, melamine polyphosphate, and melamine cyanurate.

11. The halogen-free flame-retardant polyamide according to claim 10, characterized in that: The mass ratio of the modified phosphorus-containing flame retardant, zinc borate, melamine polyphosphate, and melamine cyanurate is 10-15:0-9.8:0-8.6:0-9.

5.

12. The halogen-free flame-retardant polyamide according to claim 9, characterized in that: The halogen-free flame-retardant polyamide comprises the following components in parts by weight: 40-85 parts polyamide, 5-15 parts modified phosphorus-containing flame retardant, 2-12 parts other flame retardants, 0.2-5 parts toughening agent, 0.1-6 parts antioxidant, and 0.1-4 parts coupling agent.

13. The halogen-free flame-retardant polyamide according to claim 12, characterized in that: The polyamide is selected from one or more combinations of PA6, PA66, PA1010, PA-610, PA-612, PA-12, PA-46, PA-6T, and PA-9T; and / or, other flame retardants are selected from one or more combinations of zinc borate, melamine polyphosphate, melamine cyanurate, and ammonium polyphosphate; and / or, toughening agents are selected from one or more combinations of POE-grafted maleic anhydride and EPDM-grafted maleic anhydride; and / or, antioxidants are selected from one or more combinations of phenolic antioxidants 1098, 1076, 1010, 1024, 9228, and BHT, phosphorus-based antioxidants 168, 636, 626, 450, and 686, and thioether-based antioxidants DLTP and DSTP; and / or, coupling agents are selected from one or more combinations of silane coupling agents, aluminate coupling agents, and titanate coupling agents.

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