Preparation method of cyclotriphosphazene Schiff base carboxylic acid rare earth complex and application of cyclotriphosphazene Schiff base carboxylic acid rare earth complex in preparation of flame-retardant high polymer material

Abstract

The invention discloses a preparation method of a cyclotriphosphazene Schiff base carboxylic acid rare earth complex and application of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex in preparation of a flame-retardant high polymer material. The cyclotriphosphazene Schiff base carboxylic acid rare earth complex is prepared by reacting raw materials including p-hydroxybenzaldehyde, anhydrous potassium carbonate, phosphonitrilic chloride trimer, p-aminobenzoic acid and rare earth chloride heptahydrate. The cyclotriphosphazene Schiff base carboxylic acid rare earth complex prepared by the invention has the effects of catalyzing char formation and capturing free radicals based on the combined action of rare earth elements and phosphorus elements, has an efficient flame retardant effect, is small in addition amount, and can effectively reduce the total addition amount of the flame retardant when being compounded with other halogen-free flame retardants.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardant materials, and specifically relates to a preparation method of a cyclotriphosphazene Schiff base carboxylic acid rare earth complex and an application thereof in the preparation of flame retardant polymer materials. Background Art

[0002] In recent years, polymer materials have been widely used in many fields such as electronics, high-speed rail, ships, and aerospace due to their advantages such as light weight, high strength, and easy processing. However, most polymer materials are composed of elements such as carbon (C), hydrogen (H), and oxygen (O), and are inherently flammable or combustible materials, which are prone to fire and cause property losses. In addition, polymer materials will produce a lot of smoke and toxic gases when burning. Therefore, it is of great significance to modify polymer materials to be flame retardant in order to broaden their application areas and protect life and health.

[0003] In the existing technology, halogen-free flame retardants are mainly used to modify polymer materials to make them flame-retardant, so as to avoid the harm caused by halogen flame retardants to the environment and human body. However, the main technical challenge faced by halogen-free flame retardants is that their flame retardant efficiency is lower than that of halogen-based flame retardants, and a larger amount of addition is required to meet the flame retardant requirements of the materials, which often leads to a significant decrease in the mechanical properties of the materials. Therefore, technical personnel in the industry are actively exploring new flame retardant compounds and flame retardant synergists to improve the flame retardant efficiency of halogen-free flame retardants. Summary of the invention

[0004] The present invention aims to overcome the defects of the prior art and provide a method for preparing a cyclotriphosphazene Schiff base carboxylic acid rare earth complex.

[0005] Another object of the present invention is to provide the use of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex prepared by the above preparation method

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a cyclotriphosphazene Schiff base carboxylic acid rare earth complex comprises the following steps:

[0008] (1) adding p-hydroxybenzaldehyde and anhydrous potassium carbonate to N,N-dimethylformamide and stirring at room temperature;

[0009] (2) adding hexachlorocyclotriphosphazene to the material obtained in step (1), and stirring at room temperature for reaction;

[0010] (3) pouring the material obtained in step (2) into water, dispersing and filtering, washing the obtained precipitate with water and ethanol, and then drying to obtain compound a;

[0011] (4) dissolving compound a in tetrahydrofuran at room temperature, adding p-aminobenzoic acid, and stirring to react at room temperature;

[0012] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying to obtain SCCP;

[0013] (6) After mixing the SCCP obtained in step (5), N,N-dimethylformamide and deionized water, sodium hydroxide is added, heated to 55-65° C. and stirred until dissolved, rare earth chloride heptahydrate is added, stirred evenly, cooled and filtered, the precipitate is washed with DMF and ethanol respectively, and then dried to obtain the product.

[0014] In a preferred embodiment of the present invention, the molar ratio of p-hydroxybenzaldehyde, anhydrous potassium carbonate and hexachlorocyclotriphosphazene is 36-72:36-72:5-10; the molar ratio of compound a to p-aminobenzoic acid is 2-3:7-9; and the molar ratio of SCCP, sodium hydroxide and rare earth chloride heptahydrate is 6-9:15-20:15-20.

[0015] Further preferably, the volume ratio of N,N-dimethylformamide to deionized water in step (6) is 2:1.

[0016] In a preferred embodiment of the present invention, the rare earth chloride heptahydrate is selected from lanthanum chloride heptahydrate, cerium chloride heptahydrate, yttrium chloride heptahydrate, scandium chloride heptahydrate, praseodymium chloride heptahydrate and neodymium chloride heptahydrate.

[0017] The cyclotriphosphazene Schiff base carboxylic acid rare earth complex prepared by the preparation method is used in the preparation of flame retardant polymer materials.

[0018] In a preferred embodiment of the present invention, the raw materials of the flame retardant polymer material include a polymer substrate, the cyclotriphosphazene Schiff base carboxylic acid rare earth complex and a phosphorus nitrogen flame retardant, and the weight ratio of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex to the phosphorus nitrogen flame retardant is 1:1-6.

[0019] Further preferably, the polymer substrate is selected from at least one of polypropylene, polyethylene, polyamide, polyester, polycarbonate, polylactic acid, acrylonitrile-butadiene-styrene copolymer and ethylene-vinyl acetate copolymer, and the phosphorus-nitrogen flame retardant is selected from at least one of ammonium polyphosphate, piperazine pyrophosphate, diethyl aluminum hypophosphite, aluminum hypophosphite, melamine cyanurate, melamine polyphosphate, triethyleneimine phosphate, diaminomethyl phosphate, polyol pyrophosphate and N,N'-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxane-2-yl)ethylenediamine.

[0020] A flame retardant polymer material, the raw materials of which include a polymer substrate, the cyclotriphosphazene Schiff base carboxylic acid rare earth complex and a phosphorus-nitrogen flame retardant.

[0021] The content of polymer matrix is ​​82-96.5wt%,

[0022] The weight ratio of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex to the phosphorus nitrogen flame retardant is 1:1-6.

[0023] In a preferred embodiment of the present invention, the polymer substrate is at least one selected from polypropylene, polyethylene, polyamide, polyester, polycarbonate, polylactic acid, acrylonitrile-butadiene-styrene copolymer and ethylene-vinyl acetate copolymer.

[0024] In a preferred embodiment of the present invention, the phosphorus-nitrogen flame retardant is selected from at least one of ammonium polyphosphate, piperazine pyrophosphate, diethylaluminum hypophosphite, aluminum hypophosphite, melamine cyanurate, melamine polyphosphate, triethyleneimine phosphate, diaminomethyl phosphate, polyol pyrophosphate and N,N'-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxane-2-yl)ethylenediamine.

[0025] The beneficial effects of the present invention are as follows: the cyclotriphosphazene Schiff base carboxylic acid rare earth complex prepared by the present invention plays a role of catalyzing carbonization and capturing free radicals based on the joint action of rare earth elements and phosphorus elements, plays a role of efficient flame retardancy, and has a small addition amount. It can effectively reduce the total addition amount of the flame retardant when compounded with other halogen-free flame retardants. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The infrared spectra of Compound a, SCCP and the complex La@SCCP in Examples 1 to 4 of the present invention are shown.

[0027] Figure 2 The H NMR spectra of Compound a and SCCP in Examples 1 to 4 of the present invention.

[0028] Figure 3 TG / DTG curves of the complexes La@SCCP in Examples 1 to 4 of the present invention under argon atmosphere (a) and air atmosphere (b).

[0029] Figure 4 Graphs showing the relationship between HRR (a), THR (b), SPR (c) and TSP (d) and time in cone calorimetry experiments of PLA and flame retardant polymer materials in the embodiments of the present invention and comparative examples, wherein the curves of PLA-3, PLA-7 and PLA-8 correspond to the flame retardant polymer materials prepared in Examples 6, 7 and 8, respectively. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0031] Example 1

[0032] (1) 72 mmol of p-hydroxybenzaldehyde and 72 mmol of anhydrous potassium carbonate were added to 400 mL of N,N-dimethylformamide and stirred at room temperature for 2 h;

[0033] (2) adding 10 mmol of hexachlorocyclotriphosphazene to the material obtained in step (1), stirring at room temperature for 12 h, and then stopping the reaction;

[0034] (3) The material obtained in step (2) was poured into 400 mL of water, dispersed and filtered, the precipitate was washed three times with water and then three times with ethanol, and dried in a vacuum oven at 80° C. to obtain Figure 1 and Figure 2 Compound a shown here (Compound a);

[0035] (4) Compound a (23.2 mmol) was added to 300 mL of tetrahydrofuran and dissolved at room temperature, and then p-aminobenzoic acid (88.6 mmol) was added and stirred at room temperature for 12 h.

[0036] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding 200 mL of dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying it to obtain Figure 1 and Figure 2 The compound shown is 2,2,4-tris(4-(4-carboxyphenyliminomethyl)phenoxy)-4,6,6-tris(4-formyl)-phenoxy)cyclotriphosphazene (SCCP for short);

[0037] (6) Take 8.21 mmol of the product obtained in step (5), add 200 mL of N,N-dimethylformamide and 100 mL of deionized water, then add 17.1 mmol of sodium hydroxide, heat to 60°C and stir for 0.5 h until dissolved, then add 16.2 mmol of lanthanum chloride heptahydrate, stir for 6 h, cool and filter, wash the precipitate with DMF and ethanol respectively, and dry in a vacuum oven at 80°C to obtain Figure 1 and Figure 3 The cyclotriphosphazene Schiff base lanthanum carboxylate complex La@SCCP is shown.

[0038] Example 2

[0039] (1) 36 mmol of p-hydroxybenzaldehyde and 36 mmol of anhydrous potassium carbonate were added to 400 mL of N,N-dimethylformamide and stirred at room temperature for 2 h;

[0040] (2) adding 10 mmol of hexachlorocyclotriphosphazene to the material obtained in step (1), stirring at room temperature for 12 h, and then stopping the reaction;

[0041] (3) The material obtained in step (2) was poured into 400 mL of water, dispersed and filtered, the precipitate was washed three times with water and then three times with ethanol, and dried in a vacuum oven at 80° C. to obtain Figure 1 and Figure 2 Compound a shown here (Compound a);

[0042] (4) Take 20 mmol of compound a, add it into 300 mL of tetrahydrofuran and dissolve it at room temperature, then add 70 mmol of p-aminobenzoic acid, and stir the reaction at room temperature for 12 h;

[0043] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding 200 mL of dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying it to obtain Figure 1 and Figure 2 The compound shown is 2,2,4-tris(4-(4-carboxyphenyliminomethyl)phenoxy)-4,6,6-tris(4-formyl)-phenoxy)cyclotriphosphazene (SCCP for short);

[0044] (6) Take 6 mmol of the product obtained in step (5), add 200 mL of N,N-dimethylformamide and 100 mL of deionized water, then add 15 mmol of sodium hydroxide, heat to 60°C and stir for 0.5 h until dissolved, then add 15 mmol of lanthanum chloride heptahydrate, stir for 6 h, cool and filter, wash the precipitate with N,N-dimethylformamide and ethanol respectively, and dry in a vacuum oven at 80°C to obtain Figure 1 and Figure 3 The cyclotriphosphazene Schiff base lanthanum carboxylate complex La@SCCP is shown.

[0045] Example 3

[0046] (1) Take 50 mmol of p-hydroxybenzaldehyde and 50 mmol of anhydrous potassium carbonate and add them to 400 mL of N,N-dimethylformamide and stir at room temperature for 2 h;

[0047] (2) adding 10 mmol of hexachlorocyclotriphosphazene to the material obtained in step (1), stirring at room temperature for 12 h, and then stopping the reaction;

[0048] (3) The material obtained in step (2) was poured into 400 mL of water, dispersed and filtered, the precipitate was washed three times with water and then three times with ethanol, and dried in a vacuum oven at 80° C. to obtain Figure 1 and Figure 2Compound a shown here (Compound a);

[0049] (4) Take 30 mmol of compound a, add it into 300 mL of tetrahydrofuran and dissolve it at room temperature, then add 90 mmol of p-aminobenzoic acid, and stir the reaction at room temperature for 12 h;

[0050] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding 200 mL of dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying it to obtain Figure 1 and Figure 2 The compound shown is 2,2,4-tris(4-(4-carboxyphenyliminomethyl)phenoxy)-4,6,6-tris(4-formyl)-phenoxy)cyclotriphosphazene (SCCP for short);

[0051] (6) Take 9 mmol of the product obtained in step (5), add 200 mL of N,N-dimethylformamide and 100 mL of deionized water, then add 15 mmol of sodium hydroxide, heat to 90°C and stir for 0.5 h until dissolved, then add 15 mmol of lanthanum chloride heptahydrate, stir for 8 h, cool and filter, wash the precipitate with N,N-dimethylformamide and ethanol respectively, and dry in a vacuum oven at 80-90°C to obtain Figure 1 and Figure 3 The cyclotriphosphazene Schiff base lanthanum carboxylate complex La@SCCP is shown.

[0052] Example 4

[0053] (1) Take 50 mmol of p-hydroxybenzaldehyde and 50 mmol of anhydrous potassium carbonate and add them to 400 mL of N,N-dimethylformamide and stir at room temperature for 2 h;

[0054] (2) adding 10 mmol of hexachlorocyclotriphosphazene to the material obtained in step (1), stirring at room temperature for 12 h, and then stopping the reaction;

[0055] (3) The material obtained in step (2) was poured into 400 mL of water, dispersed and filtered, the precipitate was washed three times with water and then three times with ethanol, and dried in a vacuum oven at 80° C. to obtain Figure 1 and Figure 2 Compound a shown here (Compound a);

[0056] (4) Take 30 mmol of compound a, add it into 300 mL of tetrahydrofuran and dissolve it at room temperature, then add 90 mmol of p-aminobenzoic acid, and stir the reaction at room temperature for 12 h;

[0057] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding 200 mL of dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying it to obtain Figure 1 and Figure 2 The compound shown is 2,2,4-tris(4-(4-carboxyphenyliminomethyl)phenoxy)-4,6,6-tris(4-formyl)-phenoxy)cyclotriphosphazene (SCCP for short);

[0058] (6) Take 9 mmol of the product obtained in step (5), add 200 mL of N,N-dimethylformamide and 100 mL of deionized water, then add 15 mmol of sodium hydroxide, heat to 90°C and stir for 0.5 h until dissolved, then add 15 mmol of cerium chloride heptahydrate, stir for 8 h, cool and filter, wash the precipitate with N,N-dimethylformamide and ethanol respectively, and dry in a vacuum oven at 80-90°C to obtain Figure 1 and Figure 3 The cyclotriphosphazene Schiff base lanthanum carboxylate complex Ce@SCCP is shown.

[0059] Example 5

[0060] (1) 72 mmol of p-hydroxybenzaldehyde and 72 mmol of anhydrous potassium carbonate were added to 400 mL of N,N-dimethylformamide and stirred at room temperature for 2 h;

[0061] (2) adding 10 mmol of hexachlorocyclotriphosphazene to the material obtained in step (1), stirring at room temperature for 12 h, and then stopping the reaction;

[0062] (3) The material obtained in step (2) was poured into 400 mL of water, dispersed and filtered, the precipitate was washed three times with water and then three times with ethanol, and dried in a vacuum oven at 80° C. to obtain Figure 1 and Figure 2 Compound a shown here (Compound a);

[0063] (4) Compound a (23.2 mmol) was added to 300 mL of tetrahydrofuran and dissolved at room temperature, and then p-aminobenzoic acid (88.6 mmol) was added and stirred at room temperature for 12 h.

[0064] (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding 200 mL of dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying it to obtain Figure 1 and Figure 2 The compound shown is 2,2,4-tris(4-(4-carboxyphenyliminomethyl)phenoxy)-4,6,6-tris(4-formyl)-phenoxy)cyclotriphosphazene (SCCP for short);

[0065] (6) Take 8.21 mmol of the product obtained in step (5), add 200 mL of N,N-dimethylformamide and 100 mL of deionized water, then add 17.1 mmol of sodium hydroxide, heat to 60°C and stir for 0.5 h until dissolved, then add 16.2 mmol of cerium chloride heptahydrate, stir for 6 h, cool and filter, wash the precipitate with DMF and ethanol respectively, and place in a vacuum oven at 80°C to dry to obtain cyclotriphosphazene Schiff base carboxylic acid cerium complex Ce@SCCP.

[0066] Example 6

[0067] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0068] 96.5% polylactic acid, 0.5% cyclotriphosphazene Schiff base carboxylate lanthanum complex prepared in Example 1, 3% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is ammonium polyphosphate.

[0069] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0070] Example 7

[0071] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0072] 96% polylactic acid, 1% cyclotriphosphazene Schiff base carboxylate lanthanum complex prepared in Example 1, and 3% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is ammonium polyphosphate.

[0073] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0074] Example 8

[0075] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0076] 96% polylactic acid, 2% cyclotriphosphazene Schiff base carboxylate lanthanum complex prepared in Example 1, and 2% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is ammonium polyphosphate.

[0077] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0078] Example 9

[0079] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0080] 82% polyethylene, 3% cyclotriphosphazene Schiff base carboxylate lanthanum complex prepared in Example 1, 15% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is piperazine pyrophosphate.

[0081] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0082] Example 10

[0083] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0084] 82% polyamide, 2% cyclotriphosphazene Schiff base carboxylate lanthanum complex prepared in Example 1, 12% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is diethyl aluminum hypophosphite.

[0085] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0086] Embodiment 11

[0087] A flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex, comprising the following components:

[0088] 96.5% polylactic acid, 0.5% cyclotriphosphazene Schiff base carboxylic acid cerium complex prepared in Example 5, and 3% phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant is ammonium polyphosphate.

[0089] The preparation method of the flame retardant polymer material based on cyclotriphosphazene Schiff base carboxylic acid rare earth complex is as follows: each component is premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, granulated by stranding, and dried to obtain the final product.

[0090] Comparative Example 1

[0091] The relationship between HRR, THR, SPR and TSP and time in cone calorimetry experiment of pure polylactic acid (PLA) is shown in Figure 4 shown.

[0092] Comparative Example 2

[0093] The invention discloses a flame retardant polyethylene, which is composed of 82% polyethylene and 18% piperazine pyrophosphate. The components are premixed by a high-speed mixer, melt-extruded by a twin-screw extruder, and then granulated by strands and dried to obtain the final product.

[0094] Comparative Example 3

[0095] A flame retardant polyamide is composed of 82% polyamide and 18% diethyl aluminum hypophosphite. The components are premixed in a high-speed mixer, melt-extruded through a twin-screw extruder, and then granulated and dried to obtain the final product.

[0096]

[0097] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing a cyclotriphosphazene Schiff base carboxylic acid rare earth complex, characterized in that: The steps include: (1) adding p-hydroxybenzaldehyde and anhydrous potassium carbonate to N,N-dimethylformamide and stirring at room temperature; (2) adding hexachlorocyclotriphosphazene to the material obtained in step (1), and stirring at room temperature for reaction; (3) pouring the material obtained in step (2) into water, dispersing and filtering, washing the obtained precipitate with water and ethanol, and then drying to obtain compound a; (4) dissolving compound a in tetrahydrofuran at room temperature, adding p-aminobenzoic acid, and stirring to react at room temperature; (5) removing tetrahydrofuran from the material obtained in step (4) by rotary evaporation, adding dichloromethane, washing the precipitate, and then filtering and separating it by suction, adding ethanol to wash the precipitate, and then drying to obtain SCCP; (6) After mixing the SCCP obtained in step (5), N,N-dimethylformamide and deionized water, sodium hydroxide is added, heated to 55-65° C. and stirred until dissolved, rare earth chloride heptahydrate is added, stirred evenly, cooled and filtered, the precipitate is washed with DMF and ethanol respectively, and then dried to obtain the product.

2. The preparation method according to claim 1, characterized in that: The molar ratio of p-hydroxybenzaldehyde, anhydrous potassium carbonate and hexachlorocyclotriphosphazene is 36-72:36-72:5-10; the molar ratio of compound a and p-aminobenzoic acid is 2-3:7-9; and the molar ratio of SCCP, sodium hydroxide and rare earth chloride heptahydrate is 6-9:15-20:15-20.

3. The preparation method according to claim 2, characterized in that: The volume ratio of N,N-dimethylformamide to deionized water in step (6) is 2:

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The rare earth chloride heptahydrate is selected from lanthanum chloride heptahydrate, cerium chloride heptahydrate, yttrium chloride heptahydrate, scandium chloride heptahydrate, praseodymium chloride heptahydrate and neodymium chloride heptahydrate.

5. Use of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex prepared by the preparation method according to any one of claims 1 to 4 in the preparation of flame retardant polymer materials.

6. The use according to claim 5, characterized in that: The raw materials of the flame retardant polymer material include a polymer substrate, the cyclotriphosphazene Schiff base carboxylic acid rare earth complex and a phosphorus nitrogen flame retardant, and the weight ratio of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex to the phosphorus nitrogen flame retardant is 1:1-6.

7. The use according to claim 6, characterized in that: The polymer substrate is selected from at least one of polypropylene, polyethylene, polyamide, polyester, polycarbonate, polylactic acid, acrylonitrile-butadiene-styrene copolymer and ethylene-vinyl acetate copolymer, and the phosphorus-nitrogen flame retardant is selected from at least one of ammonium polyphosphate, piperazine pyrophosphate, diethyl aluminum hypophosphite, aluminum hypophosphite, melamine cyanurate, melamine polyphosphate, triethyleneimine phosphate, diaminomethyl phosphate, polyol pyrophosphate and N,N'-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxane-2-yl)ethylenediamine.

8. A flame retardant polymer material, characterized in that: The raw materials include polymer substrate, the cyclotriphosphazene Schiff base carboxylic acid rare earth complex and phosphorus nitrogen flame retardant. The content of polymer matrix is ​​82-96.5wt%, The weight ratio of the cyclotriphosphazene Schiff base carboxylic acid rare earth complex to the phosphorus nitrogen flame retardant is 1:1-6.

9. A flame retardant polymer material according to claim 8, characterized in that: The polymer substrate is selected from at least one of polypropylene, polyethylene, polyamide, polyester, polycarbonate, polylactic acid, acrylonitrile-butadiene-styrene copolymer and ethylene-vinyl acetate copolymer.

10. The flame retardant polymer material according to claim 8, characterized in that: The phosphorus-nitrogen flame retardant is selected from at least one of ammonium polyphosphate, piperazine pyrophosphate, diethylaluminum hypophosphite, aluminum hypophosphite, melamine cyanurate, melamine polyphosphate, triethyleneimine phosphate, diaminomethyl phosphate, polyol pyrophosphate and N,N'-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxane-2-yl)ethylenediamine.

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