Preparation method of low-cost cyclotriphosphazene flame retardant

Abstract

The invention provides a preparation method of a low-cost cyclotriphosphazene flame retardant, which comprises the following steps: weighing aniline, dissolving in ethylene glycol dimethyl ether in a beaker A, and weighing triethylamine in a beaker B; weighing phosphonitrilic chloride trimer, and dissolving phosphonitrilic chloride trimer in ethylene glycol dimethyl ether in a beaker C; pouring the solution in the beaker C into a three-necked flask, introducing condensate water, installing a dropping funnel on one neck, sealing the other neck with a glass plug, setting the water bath temperature to be 50-65 DEG C, and starting to heat; the solutions in the beakers A and B are poured into a dropping funnel, dropping is started when the temperature reaches 50-65 DEG C, timing is conducted, heating and stirring are stopped after the reaction is completed, and a reaction device is closed; after the three-necked flask is cooled to the room temperature, a reaction system in the three-necked flask is subjected to reduced-pressure suction filtration, filtrate obtained after suction filtration is dried, impurities are removed, then drying is conducted again, the cyclotriphosphazene flame retardant is obtained, the cyclotriphosphazene flame retardant has good expansion performance and flame retardant performance, and experimental data are provided for further improving the flame retardant performance of a green expansion type flame retardant.

Description

Technical Field

[0001] This invention relates to the field of flame retardant technology, and specifically to a low-cost method for preparing cyclotriphosphazene flame retardants. Background Technology

[0002] Flame retardants, as additives that effectively prevent materials from being ignited and inhibit flame propagation, are widely used to improve the fire resistance of materials and have become important additives in the synthesis of polymer materials. Halogenated flame retardants are among the most produced organic flame retardants globally. However, some brominated flame retardants and their flame-retardant materials generate dioxins during photolysis or combustion, posing potential hazards to human health, safety, and the environment. This has attracted high attention and vigilance from environmental organizations and governments worldwide, and some have already been banned.

[0003] Halogen-free organophosphorus flame retardants are organic flame retardants that are equally important as halogenated flame retardants. They are favored by users and researchers due to their variety, wide applications, high efficiency, and low toxicity. Hexachlorocyclotriphosphazene, as a novel organophosphorus flame retardant framework material, possesses a stable six-membered ring conjugated structure, resulting in excellent thermal stability. It also exhibits the characteristic of easy derivatization with multiple side groups, and its derivatives combine the excellent properties of both inorganic and organic compounds, exhibiting good thermal stability. Therefore, it has broad research and application prospects in the field of flame retardancy.

[0004] Reactive cyclotriphosphazene flame retardants mainly participate in the chemical reactions of polymer synthesis as auxiliary reagents or monomers, becoming structural units of the polymer. They exhibit good compatibility with materials, introducing effective cyclotriphosphazene structural units into the polymer chain through polymerization, making them less prone to migration within the material and providing long-lasting flame retardancy.

[0005] However, due to the generally high cost and complex synthesis process of cyclotriphosphazene flame retardants, most research results are currently limited to the laboratory and have not yet entered industrial production and application. Developing low-cost cyclotriphosphazene flame retardants and optimizing their synthesis processes are urgent problems to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost method for preparing cyclotriphosphazene flame retardants. Using hexachlorocyclotriphosphazene and aniline as reactants, a cyclotriphosphazene flame retardant is synthesized through a substitution reaction. This method is cheaper and easier to operate than traditional methods for preparing cyclotriphosphazene flame retardants.

[0007] The technical solution of this invention is implemented as follows:

[0008] This invention provides a low-cost method for preparing cyclotriphosphazene flame retardants, comprising the following steps:

[0009] Step 1: Measure ethylene glycol dimethyl ether into beaker A, then weigh aniline and pour it into beaker A. Stir to mix aniline and ethylene glycol dimethyl ether thoroughly. Then weigh triethylamine into beaker B for later use.

[0010] Step 2: Measure ethylene glycol dimethyl ether into beaker C, then weigh hexachlorocyclotriphosphazene, pour the weighed hexachlorocyclotriphosphazene into beaker C, stir to fully dissolve the hexachlorocyclotriphosphazene, and set aside.

[0011] Step 3: Fix the three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300 RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask, introduce cooling water, install a dropping funnel on one of the necks, seal the other neck with a glass stopper, set the water bath temperature to the preset temperature, and start heating.

[0012] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solutions when the temperature reaches the preset temperature and start timing. After the reaction is complete, stop heating and stirring, and turn off the reaction apparatus.

[0013] Step 5: Turn off the cooling water, remove the three-necked flask, and after the three-necked flask has cooled to room temperature, pour the reaction system in the three-necked flask into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the drying oven temperature to 80℃ and the time to 4 hours to dry.

[0014] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0015] Furthermore, in step 1, the ratio of ethylene glycol dimethyl ether, aniline, and triethylamine is 10 mL: 3.21–3.85 g: 3.49 g.

[0016] Furthermore, in step 2, the ratio of ethylene glycol dimethyl ether to hexachlorocyclotriphosphazene is 10 mL: 2.00 g.

[0017] Furthermore, in step 2, the stirring time is 3 minutes.

[0018] Furthermore, in step 3, the preset temperature is 50–65°C.

[0019] Furthermore, in step 4, the drop rate is 5 seconds per drop, and the reaction time is 2 to 8 hours.

[0020] Furthermore, when measuring ethylene glycol dimethyl ether into beaker C, the process was carried out in batches. First, 70% of the ethylene glycol dimethyl ether was measured to dissolve hexachlorocyclotriphosphazene and poured into a three-necked flask. Then, 30% of the ethylene glycol dimethyl ether was measured to rinse beaker C, and the rinsed solution was poured back into the three-necked flask.

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention provides a low-cost method for preparing cyclotriphosphazene flame retardants, using hexachlorocyclotriphosphazene and aniline as reactants to synthesize a cyclotriphosphazene flame retardant through a substitution reaction. The method is cheaper and easier to operate than traditional methods for preparing cyclotriphosphazene flame retardants.

[0023] 2. Cyclotriphosphazene flame retardants are mainly reactive flame retardants that can be used for flame retardancy of thermosetting materials such as epoxy resins, polyurethanes, and fibers. These flame retardants greatly improve the flame retardant performance and thermal stability of materials with relatively low addition amounts, overcoming the disadvantages of high addition amounts of inorganic flame retardants and environmental pollution of halogenated flame retardants.

[0024] 3. This application uses hexachlorocyclotriphosphazene as a substrate and ethylene glycol dimethyl ether as a solvent. By substituting the two amino groups on aniline with the six chlorine atoms on hexachlorocyclotriphosphazene through a substitution reaction and grafting a new nitrogen source, a cyclotriphosphazene flame retardant was successfully synthesized. It has good expansion and flame retardant properties, providing experimental data for further improving the flame retardant properties of green intumescent flame retardants.

[0025] 4. The reaction between aniline and hexachlorocyclotriphosphazene produces hydrochloric acid as a byproduct. Triethylamine acts as an acid-binding agent to remove hydrochloric acid, control and reduce the emission of acidic substances, thereby enabling the reaction system to proceed in the forward direction.

[0026] 5. The cyclotriphosphazene flame retardant prepared in this application belongs to the intumescent type. The cyclotriphosphazene flame retardant prepared in this application exhibits highly efficient flame retardant properties. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of the addition of hexachlorocyclotriphosphazene after aniline was dissolved in Comparative Example 1;

[0029] Figure 2A schematic diagram of the addition of triethylamine to the mixed solution of aniline and hexachlorocyclotriphosphazene in Comparative Example 1;

[0030] Figure 3 This is a schematic diagram of the reaction of aniline, hexachlorocyclotriphosphazene, and triethylamine in Comparative Example 1, after being mixed and poured into a three-necked flask.

[0031] Figure 4 This is a photographic illustration of the mixed solution of hexachlorocyclotriphosphazene and triethylamine in Comparative Example 2 being poured into a dropping funnel;

[0032] Figure 5 This is a photographic illustration showing the precipitation of hexachlorocyclotriphosphazene (HCTP) after a period of time following the initial addition of a mixed solution of hexachlorocyclotriphosphazene and triethylamine to a three-necked flask from a dropping funnel in Comparative Example 2.

[0033] Figure 6 A schematic diagram showing the large amount of hexachlorocyclotriphosphazene precipitated after the mixed solution of hexachlorocyclotriphosphazene and triethylamine was added dropwise to triethylamine in Comparative Example 2;

[0034] Figure 7 This is a schematic diagram showing the precipitation of hexachlorocyclotriphosphazene in Comparative Example 3, which prevented it from entering the reaction vessel.

[0035] Figure 8 A photographic schematic diagram of the combustion of the product obtained in Comparative Example 1;

[0036] Figure 9 This is a schematic photograph of the product obtained in Comparative Example 1 after combustion.

[0037] Figure 10 This is a schematic diagram of thermogravimetric analysis of products obtained by using different material ratios in an embodiment of the present invention;

[0038] Figure 11 This is a photographic illustration of the ignition of the cyclotriphosphazene flame retardant product obtained by the preparation method of Example 10 of the present invention;

[0039] Figure 12 This is a schematic diagram of a photograph of hexachlorocyclotriphosphazene after ignition.

[0040] Figure 13 This is a schematic diagram of aniline after it has been ignited. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] This invention provides a low-cost method for preparing cyclotriphosphazene flame retardants, comprising the following steps:

[0043] Step 1: Measure 10ml of ethylene glycol dimethyl ether into 50ml beaker A, then weigh 3.38g of aniline and pour it into beaker A. Stir to mix the aniline and ethylene glycol dimethyl ether thoroughly. Then weigh 3.49g of triethylamine into beaker B for later use.

[0044] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, then weigh 2.00 g of hexachlorocyclotriphosphazene, pour the weighed hexachlorocyclotriphosphazene into beaker C, stir for 3 minutes to fully dissolve the hexachlorocyclotriphosphazene, and set aside.

[0045] Step 3: Fix the three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300 RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3 ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50-65℃ and start heating.

[0046] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. When the temperature reaches the preset temperature, start adding the solution and start timing. The dropping rate is 5 drops / second. After the reaction time is 2 to 8 hours, stop heating and stirring, and turn off the reaction device.

[0047] Step 5: Turn off the cooling water, remove the three-necked flask, and after the three-necked flask has cooled to room temperature, pour the reaction system in the three-necked flask into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the drying oven temperature to 80℃ and the time to 2-8 hours to dry.

[0048] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0049] It should be noted that the instrument capacity is described here. The three-necked flask used in this embodiment of the invention is 100ml, and the beaker is 50ml.

[0050] The following are specific embodiments.

[0051] Example 1

[0052] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.38 g of aniline and pour it into beaker A, stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0053] Step 2: Measure 7 mL of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0054] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0055] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0056] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0057] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0058] Example 2

[0059] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.38 g of aniline and pour it into beaker A, stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0060] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0061] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 55℃ and start heating.

[0062] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 55°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0063] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0064] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0065] Example 3

[0066] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.38 g of aniline and pour it into beaker A, stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0067] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0068] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 60℃ and start heating.

[0069] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 60°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0070] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0071] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0072] Example 4

[0073] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.38 g of aniline and pour it into beaker A, stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0074] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0075] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 65℃ and start heating.

[0076] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 65°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0077] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0078] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0079] Example 5

[0080] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.21 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0081] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0082] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0083] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0084] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0085] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0086] Example 6

[0087] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.54 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0088] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0089] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0090] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0091] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0092] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0093] Example 7

[0094] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.70 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0095] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0096] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0097] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0098] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0099] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0100] Example 8

[0101] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.85 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0102] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0103] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0104] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 4 hours, stop heating and stirring and turn off the reaction apparatus.

[0105] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0106] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0107] Example 9: Same as Example 7, except that the reaction time is 2 hours.

[0108] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.70 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0109] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0110] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0111] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 2 hours, stop heating and stirring and turn off the reaction apparatus.

[0112] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0113] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0114] Example 10: Same as Example 7, except that the reaction time is 6 hours.

[0115] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.70 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0116] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0117] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0118] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 6 hours, stop heating and stirring and turn off the reaction apparatus.

[0119] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0120] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0121] Example 11: Same as Example 7, except that the reaction time is 7 hours.

[0122] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.70 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0123] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0124] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0125] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 7 hours, stop heating and stirring and turn off the reaction apparatus.

[0126] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0127] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0128] Example 12: Same as Example 7, except that the reaction time is 8 hours.

[0129] Step 1: Measure 10 ml of ethylene glycol dimethyl ether into a 50 ml beaker A, then weigh 3.70 g of aniline and pour it into beaker A. Stir to mix thoroughly, then weigh 3.49 g of triethylamine into beaker B and set aside for later use.

[0130] Step 2: Measure 7 ml of ethylene glycol dimethyl ether into beaker C, accurately weigh 2.00 g of hexachlorocyclotriphosphazene, pour it into the beaker and stir for three minutes to dissolve it completely, then set aside.

[0131] Step 3: Fix the 100ml three-necked flask in the water bath, install the condenser, insert the magnetic stir bar, set the rotation speed to 300RPM, and after the rotation speed stabilizes, quickly pour the solution in beaker C into the three-necked flask. Then measure 3ml of ethylene glycol dimethyl ether into beaker C, and quickly pour all the remaining solution in beaker C into the three-necked flask. Pour in cooling water, install a dropping funnel on one neck, and seal the other neck with a glass stopper. Set the water bath temperature to 50℃ and start heating.

[0132] Step 4: Pour the solutions in beakers A and B into the dropping funnel in sequence. Start adding the solution when the temperature reaches 50°C and start timing. The dropping rate is 5 drops / second. After reacting for 8 hours, stop heating and stirring and turn off the reaction apparatus.

[0133] Step 5: Turn off the cooling water, remove the three-necked flask, and let it cool to room temperature. Then pour it into the Buchner funnel and start vacuum filtration. Pour the filtrate into a watch glass, remove the filter paper from the Buchner funnel, place the filter paper on a new watch glass, and place both watch glasses together in an electric heating drying oven. Set the oven temperature to 80℃ and the time to 4 hours to dry.

[0134] Step 6: After cooling, remove the product and weigh it. The filter paper contains triethylamine hydrochloride. After drying the filtrate, wash it with 1 mol / L sodium hydroxide solution, and then wash it with deionized water to make the pH of the washed filtrate 6-7. Then dry it again to obtain the cyclotriphosphazene flame retardant.

[0135] Comparative Example 1: Same as Example 6, except that hexachlorocyclotriphosphazene, aniline, and triethylamine were mixed together. Specifically, aniline was dissolved in ethylene glycol dimethyl ether and then hexachlorocyclotriphosphazene was added. See [link to example]. Figure 1 Then add triethylamine to the solution obtained in the previous step, see Figure 2 The three reactants were mixed and poured into a three-necked flask for reaction, see... Figure 3 .

[0136] For the flame retardant performance test of the product obtained from the reaction of the three solutions in Comparative Example 1, please refer to [link / reference]. Figures 8-9 During combustion, black smoke is produced, and the molten droplets fall rapidly. The flames on the product, even after it has moved away from the heat source, do not extinguish. The black color of the molten droplets accompanied by black smoke indicates that the product obtained after the reaction of the three solutions has virtually no flame-retardant properties.

[0137] Comparative Example 2: Same as Example 6, except that triethylamine was used as the substrate. The triethylamine was placed in a three-necked flask, and hexachlorocyclotriphosphazene and aniline were added to the dropping funnel. Specifically:

[0138] Pour a mixed solution of hexachlorocyclotriphosphazene and triethylamine into a dropping funnel, see... Figure 4After a mixed solution of hexachlorocyclotriphosphazene and triethylamine was initially added dropwise from a dropping funnel to a three-necked flask, hexachlorocyclotriphosphazene began to precipitate after a period of time. Figure 5 The reason is that the solubility of hexachlorocyclotriphosphazene in ethylene glycol dimethyl ether decreases due to the low temperature; after the mixed solution is added dropwise, a large amount of hexachlorocyclotriphosphazene remains precipitated, see... Figure 6 .

[0139] Comparative Example 3: Same as Example 6, except that aniline was used as the substrate. Aniline was dissolved in ethylene glycol dimethyl ether and then placed in a three-necked flask. Hexachlorocyclotriphosphazene and triethylamine were added to the dropping funnel. Specifically, a mixed solution of hexachlorocyclotriphosphazene and triethylamine was first added to the dropping funnel, and then the mixed solution was added dropwise to the three-necked flask (which contained the dissolved aniline solution). As in Comparative Example 2, hexachlorocyclotriphosphazene precipitated and could not enter the reaction vessel. See [link to Comparative Example 2]. Figure 7 .

[0140] Comparative Example 4: Same as Example 6, except that the washing solvent was different. Comparative Example 4 conducted multiple experiments using different solvents such as anhydrous ethanol, deionized water, ethyl acetate, methanol, and petroleum ether. The product showed poor stability in all of these solvents.

[0141] The following is an analysis of the experimental results:

[0142] Since the product obtained from the reaction is a liquid, after drying, the product may contain unreacted hexachlorocyclotriphosphazene and aniline, as well as the byproduct triethylamine hydrochloride. After trying solvents such as anhydrous ethanol, deionized water, ethyl acetate, methanol, and petroleum ether, it was found that the product has the best stability in a 1 mol / L sodium hydroxide solution, exhibiting a dispersed state (solution temperature 35℃). The dissolution experiment used 10 ml of solvent and 0.1 g of solid.

[0143] In a 1 mol / L sodium hydroxide solution, the solvent was continuously added up to 30 ml and the solution remained dispersed. This solvent can be used to remove impurities later.

[0144] Therefore, through repeated experiments, in the embodiments of the present invention, the solvent for washing the product is a 1 mol / L sodium hydroxide solution to remove impurities.

[0145] The yields of Examples 1-8 and Comparative Examples 1-3 are shown in Table 1 below:

[0146] Table 1

[0147] Example Yield Example 1 89.26% Example 2 87.12% Example 3 84.24% Example 4 83.72% Example 5 81.43% Example 6 84.12% Example 7 91.85% Example 8 90.26% Example 9 85.26% Example 10 96.07% Example 11 94.11% Example 12 93.56% Comparative Example 1 57.59% Comparative Example 2 45.37% Comparative Example 3 44.44%

[0148] It should be noted that the molar ratio of hexachlorocyclotriphosphazene to aniline is 1:6 for the reaction to be complete. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.21.

[0149] The following are some comparative experiments conducted by the inventors to explore the effect of different reaction conditions on the yield:

[0150] I. Investigating the effect of different water bath temperatures on reaction yield:

[0151] Examples 1-4: Except for the water bath temperature, the other reaction conditions were the same. The material ratio was 5% excess aniline, meaning that the mass of hexachlorocyclotriphosphazene and aniline was 5% greater than the mass of aniline after the reaction was just complete. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline was 2.00:3.38.

[0152] The effect of different water bath temperatures on the yield was investigated, as shown in Table 2 below:

[0153] Table 2

[0154] Example Example 1 Example 2 Example 3 Example 4 water bath temperature 50℃ 55℃ 60℃ 65℃ Yield 89.26% 87.12% 84.24% 83.72%

[0155] II. Investigating the effect of different material ratios on reaction yield:

[0156] Examples 1 and 5-8: The reaction conditions were the same except for the material ratio.

[0157] Aniline is not in excess: hexachlorocyclotriphosphazene and aniline react completely, with a mass ratio of hexachlorocyclotriphosphazene to aniline of 2.00:3.21.

[0158] Aniline in excess by 5%: Based on the complete reaction of hexachlorocyclotriphosphazene and aniline, the mass of aniline is in excess by 5%. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.38.

[0159] Aniline in excess by 10%: Based on the complete reaction of hexachlorocyclotriphosphazene and aniline, the mass of aniline is in excess by 10%. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.54.

[0160] Aniline in excess by 15%: Based on the complete reaction of hexachlorocyclotriphosphazene and aniline, the mass of aniline is in excess by 15%. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.70.

[0161] Aniline in excess by 20%: Based on the complete reaction of hexachlorocyclotriphosphazene and aniline, the mass of aniline is in excess by 20%. Converted to mass, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.85.

[0162] The effects of different material ratios on the yield and the flame retardant properties of the resulting flame retardant are shown in Table 3 below:

[0163] Table 3

[0164] Example 5 Example 1 Example 6 Example 7 Example 8 Material ratio Aniline not in excess 5% excess aniline 10% excess aniline 15% excess aniline Aniline in excess (20%) Mass ratio of hexachlorocyclotriphosphazene to aniline 2.00：3.21 2.00：3.38 2.00：3.54 2.00：3.70 2.00：3.85 Yield 81.43% 89.26% 84.12% 91.85% 90.26%

[0165] III. The effect of different reaction times on the reaction yield is shown in Table 4 below:

[0166] Table 4

[0167] Example Example 9 Example 7 Example 10 Example 11 Example 12 reaction time 2h 4h 6h 7h 8h Yield 85.26% 91.85% 96.07% 94.11% 93.56%

[0168] In summary, as shown in Table 2, within the temperature range of 50℃ to 65℃, the yield decreases to a certain extent with increasing temperature, while the yield is highest and most stable at 50℃.

[0169] As shown in Table 3, when aniline is in 15% excess, the reaction yield is highest when the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.70.

[0170] Table 4 shows that the reaction yield is highest when the reaction time is 6 hours.

[0171] IV. Investigating the effects of different reaction conditions on the flame retardant properties of the obtained products:

[0172] Through extensive experimentation, the inventors discovered that as long as the material ratio remains the same, the final product obtained is identical regardless of changes in reaction time or water bath temperature, and its flame-retardant properties are also the same. Therefore, changes in reaction time or water bath temperature only affect the reaction yield, not its flame-retardant properties.

[0173] The flame retardant properties of the products differ only when the material ratio is different, as revealed by thermogravimetric analysis. (See [reference needed]). Figure 10 It can be seen that when aniline is in 10% excess, the residual carbon content at 800℃ reaches 52.14%. Therefore, it can be concluded that when aniline is in 10% excess, the mass ratio of hexachlorocyclotriphosphazene to aniline is 2.00:3.54, resulting in the best flame retardant performance.

[0174] V. Flame retardant test:

[0175] The cyclotriphosphazene flame retardant product, hexachlorocyclotriphosphazene, and aniline prepared by the method in Example 10 of this invention were ignited, and corresponding photographs were obtained.

[0176] Figure 11 This is a photographic illustration of the ignition of the cyclotriphosphazene flame retardant product obtained by the preparation method of Example 10 of the present invention; Figure 12 This is a schematic diagram of a photograph of hexachlorocyclotriphosphazene after ignition. Figure 13 This is a schematic diagram of aniline after it has been ignited.

[0177] As can be seen from the photos:

[0178] The cyclotriphosphazene flame retardant product prepared by the method in Example 10 of this invention extinguishes rapidly after ignition with very little smoke;

[0179] Hexachlorocyclotriphosphazene: Produces a large amount of toxic and harmful gases when ignited;

[0180] Aniline: Flammable and burns continuously.

[0181] The above experiments verified that the product prepared according to the embodiments of the present invention has flame retardant properties, is a cyclotriphosphazene flame retardant, and belongs to the intumescent type of flame retardant.

[0182] Innovation points:

[0183] The innovation of this invention lies in the development of a new process route: the reaction system uses a specific solvent, ethylene glycol dimethyl ether, a specific mass ratio of hexachlorocyclotriphosphazene and aniline, a specific feeding method, a specific reaction time, and a specific reaction temperature, all working together to achieve control over the reaction system. Under mild conditions of only 6 hours of reaction time and 50°C, a high yield of 96.07% is obtained. The energy consumption of the reaction system in this application is low, greatly reducing costs.

[0184] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of low cost cyclic phosphazene based flame retardant characterized in that, It comprises the following steps: Step 1: measure the glycol dimethyl ether in a beaker A, then measure the aniline and pour it into the beaker A, stir to mix the aniline and glycol dimethyl ether, then measure the triethylamine in a beaker B, and reserve it; Step 2: measure the glycol dimethyl ether in a beaker C, then measure the hexachlorocyclotriphosphazene, pour it into the beaker C, stir to dissolve the hexachlorocyclotriphosphazene, and reserve it; Step 3: fix the three-necked flask in a water bath, install the condenser, put in a magnet, set the rotation speed to 300 RPM, pour the solution in the beaker C into the three-necked flask after the rotation speed is stable, pour in the condensing water, install the dropping funnel in one neck, seal the other neck with a glass plug, set the water bath temperature to the preset temperature, and start heating; Step 4: pour the solutions in the beakers A and B into the dropping funnel in turn, start dropping when the temperature reaches the preset temperature and count the time, stop heating and stirring after the reaction is completed, and close the reaction device; Step 5: turn off the condensing water, take out the three-necked flask, pour the reaction system in the three-necked flask into a Buchner funnel after the three-necked flask cools to room temperature, start reducing pressure filtration, pour the filtrate into a surface dish, take out the filter paper in the Buchner funnel, place the filter paper on a new surface dish, and place the two surface dishes in an electric heating air drying oven, set the drying oven temperature to 80℃, and dry for 4h; Step 6: take out after cooling, weigh respectively, the filter paper is triethylamine hydrochloride, the filtrate is washed with 1 mol / L sodium hydroxide solution and deionized water, so that the pH value of the washed filtrate is 6-7, then it is dried again to obtain the cyclotriphosphazene flame retardant.

2. A process for the preparation of low cost cyclic phosphazene flame retardant as claimed in claim 1, wherein, In step 1, the amount ratio of glycol dimethyl ether, aniline and triethylamine is 10 mL: 3.21-3.85 g: 3.49 g.

3. A process for the preparation of low cost cyclotriphosphazene based flame retardant as claimed in claim 1, wherein, In step 2, the amount ratio of glycol dimethyl ether and hexachlorocyclotriphosphazene is 10 mL: 2.00 g.

4. A process for the preparation of low cost cyclotriphosphazene based flame retardant as claimed in claim 1, wherein, In step 2, the stirring time is 3 minutes.

5. A process for the preparation of low cost cyclic phosphazene flame retardant as claimed in claim 1, wherein, In step 3, the preset temperature is 50-65℃.

6. A process for the preparation of low cost cyclotriphosphazene based flame retardant as claimed in claim 1, wherein, In step 4, the dropping rate is 5s / drop, and the reaction time is 2-8h.

7. The method for preparing a low-cost cyclotriphosphazene flame retardant according to claim 1, characterized in that, In step 2, the stirring time is 3 minutes. In step 3, the preset temperature is 50-65℃. In step 4, the dropping rate is 5s / drop, and the reaction time is 2-8h.

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