Preparation method of halogenated cyclotriphosphazene flame retardant

Abstract

The invention relates to the technical field of flame retardant preparation, in particular to a preparation method of a halogenated cyclotriphosphazene flame retardant, which comprises the following steps: adding a preset marker into a first mixed solution obtained after the reaction is completed, and stirring to obtain a second mixed solution; introducing the second mixed solution into a flash tank for flash evaporation, and determining the flash evaporation degree according to the chromaticity of gas in the flash tank so as to judge whether to adjust the gas pressure in the flash tank; the air pressure in the flash tank is adjusted based on the judgment result of air pressure adjustment, and the flash evaporation progress is determined according to the air flow direction and flow speed of a plurality of positions in the flash tank; and if the flash evaporation progress meets the preset standard, outputting the gas in the flash evaporation tank to obtain the high-purity halogenated cyclotriphosphazene. The purification efficiency and the yield can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant preparation, and in particular to a method for preparing a halogenated cyclotriphosphazene flame retardant. Background Art

[0002] Phosphazene is an inorganic-organic hybrid compound with alternating phosphorus and nitrogen atoms in the skeleton. Due to the conjugation effect between phosphorus and nitrogen on the main chain, the structure is stable and not easily oxidized, so that it has the physical properties of organic compounds, insoluble in water but soluble in organic solvents. Phosphazene flame retardant has a high thermal decomposition temperature and flame retardant effect due to the good synergistic effect between phosphorus and nitrogen, and has less smoke and toxic gas, making it an environmentally friendly flame retardant material. At the same time, the chlorine on the phosphorus atom is very active and can be easily replaced by various nucleophilic reagents, so phosphazene has the excellent properties of both organic and inorganic substances. By changing the functional groups of the side groups, cyclic phosphazene compounds with different functions can be obtained. It is precisely because of the diversity of the side groups of phosphazene compounds that they give them diversity in properties after polymerization, and the application and development prospects of polyphosphazene compounds are very broad. At present, they are used in a variety of applications such as new high-efficiency flame retardants, side chain liquid crystals, special rubbers and electronic materials.

[0003] The existing technical solutions for preparing pentafluoroethoxy cyclotriphosphazene all use hexachlorocyclotriphosphazene as raw material. The solutions provided by patents CN104558045A, CN105732718A, etc. are first perfluorinated and then ethoxylated, but the first step of fluorination uses fluorine salts such as potassium fluoride and sodium fluoride, and reacts under the action of a catalyst. Since there are a large number of solids in the system, the stirring effect of the reaction equipment is required to be high, and since the chloride produced by the reaction will contain fluorine salts, the fluorine salts need to be greatly excessive to complete the fluorination reaction, thus generating a large amount of inorganic solid waste, which has an adverse effect on the environment; and the fluorination reaction temperature using fluorine salts such as potassium fluoride and sodium fluoride is high, the reaction time is long, and a large amount of energy is consumed; in addition, since the intermediate hexafluorocyclotriphosphazene has a relatively low boiling point and is very volatile, conventional reaction methods and purification methods are prone to cause hexafluorocyclotriphosphazene to escape, greatly reducing the yield. The method provided by patent CN102702268A is to firstly ethoxylate hexachlorocyclotriphosphazene, then fluorinate it, and then distill off the byproducts and solvent.

[0004] It can be seen that the above invention has the following problems: after the reaction is completed, the by-products and the solvent are separated from the product by distillation, the purification efficiency is relatively low, and the yield may be low. Summary of the invention

[0005] To this end, the present invention provides a method for preparing a halogenated cyclotriphosphazene flame retardant, which is used to overcome the problems of low flash distillation purification efficiency and low yield in the prior art.

[0006] To achieve the above object, the present invention provides a method for preparing a halogenated cyclotriphosphazene flame retardant, comprising:

[0007] Step S1, adding a preset marker to the first mixed solution obtained after the reaction is completed, and stirring to obtain a second mixed solution; the second mixed solution includes a preset marker, a key solvent and a halogenated cyclotriphosphazene; the boiling point of the preset marker is lower than the boiling point of the key solvent; the key solvent is one or more of acetonitrile, ethyl acetate and xylene;

[0008] Step S2, passing the second mixed solution into a flash tank for flash evaporation, and determining the degree of flash evaporation according to the chromaticity of the gas in the flash tank to determine whether to adjust the gas pressure in the flash tank;

[0009] Step S3, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment, and determining the progress of flash evaporation according to the gas flow direction and flow rate at several positions in the flash tank;

[0010] Step S4: if the flash evaporation progress meets the preset standard, the gas in the flash evaporation tank is output to obtain high-purity halogenated cyclotriphosphazene.

[0011] Furthermore, the preset marker is determined according to the boiling point of the first mixed solution.

[0012] Further, in step S3, the flash evaporation process includes:

[0013] Step S31, heating the flash tank to a first preset temperature under a first preset pressure;

[0014] Step S32, obtaining the solution temperature and solution volume of the second mixed solution;

[0015] Step S33, determining whether to adjust the flash evaporation pressure according to the solution temperature and the solution volume.

[0016] Further, in the step S3, the flash degree is determined according to the chromaticity of the gas in the flash tank;

[0017] Wherein, if the gas chromaticity is less than a first preset chromaticity threshold, it is a first flash evaporation degree;

[0018] If the gas chromaticity is greater than or equal to the first preset chromaticity threshold and less than or equal to the second preset chromaticity threshold, it is the second flash degree;

[0019] If the gas chromaticity is greater than the second preset chromaticity threshold, it is the third flash evaporation level.

[0020] Further, in step S4, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment includes:

[0021] If the first flash evaporation degree is met, adjusting the gas pressure in the flash tank according to a first preset adjustment method;

[0022] If the second flash degree is met, adjusting the gas pressure in the flash tank according to a second preset adjustment method;

[0023] If the third flash degree is met, the gas pressure in the flash tank is not adjusted;

[0024] Wherein, the first preset adjustment method is to output all the gas in the flash tank to adjust the gas pressure in the flash tank;

[0025] The second preset adjustment method is to determine the gas pressure adjustment amount in the flash tank according to the current temperature of the second mixed solution.

[0026] Furthermore, in step S3, step S34 is also included, determining the flash characteristic point according to the chromaticity change curve of the preset marker in the flash tank and the pressure change curve in the flash tank.

[0027] Furthermore, in step S4, step S41 is also included, adjusting the gas pressure in the flash tank according to the pressure in the flash tank corresponding to the flash characteristic point and the flash preset pressure.

[0028] Furthermore, in step S4, after the gas pressure in the flash tank is adjusted, the progress of flash evaporation is determined according to the gas flow direction at the corresponding positions of the upper and middle parts of the flash tank, the gas flow rate at the corresponding position of the middle part of the flash tank, and the pressure change in the flash tank.

[0029] Furthermore, in step S4,

[0030] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are different, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the initial flash progress is met;

[0031] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the mid-term flash progress is met;

[0032] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change in the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is not less than a preset flow rate change threshold, and the pressure change in the flash tank is less than a preset pressure threshold, it is determined that the terminal flash progress is met.

[0033] Furthermore, in the step S5, if it is determined that the final flash evaporation is progressing, the preset standard is met.

[0034] Compared with the prior art, the beneficial effect of the present invention is that the present invention adds a preset marker to the first mixed solution obtained after the reaction is completed to obtain a second mixed solution, and flashes the second mixed solution, which can quickly realize the evaporation and separation of the preset marker, key solvent and halogenated cyclotriphosphazene in the second mixed solution, thereby improving the purification efficiency. Since the preset marker is different in color from other substances and has the lowest boiling point, the chromaticity of the gas in the flash tank can quickly judge the degree of flash evaporation to determine whether to adjust the air pressure in the flash tank, thereby determining whether to adjust the air pressure in the flash tank, and further improving the purification efficiency. By adjusting the air pressure in the flash tank, and determining the progress of flash evaporation according to the gas flow direction and flow rate at several positions in the flash tank, and determining whether to output the gas in the flash tank to obtain high-purity halogenated cyclotriphosphazene according to the progress of flash evaporation, the purification yield can be improved.

[0035] Furthermore, the present invention can improve production efficiency by first adjusting the pressure and temperature in the flash tank, and then adjusting the flash pressure according to the solution temperature and solution volume of the second mixed solution, which can further improve the subsequent purification efficiency.

[0036] Furthermore, the present invention can quickly determine the flash evaporation degree according to the gas chromaticity in the flash tank, and can quickly and accurately adjust the gas pressure in the flash tank according to the flash evaporation degree, thereby improving the purification efficiency.

[0037] Furthermore, the present invention can further improve the accuracy of adjusting the flash tank by determining the flash characteristic point according to the chromaticity change curve and the pressure change curve in the flash tank, and further adjusting the gas pressure in the flash tank, thereby improving the purification efficiency.

[0038] Furthermore, in the present invention, since the boiling points of various substances are different, vaporizing low-boiling-point liquids through flash evaporation will affect the gas pressure in the flash tank. Whether to output the gas in the flash tank is determined according to the progress of flash evaporation and preset standards, which can improve the purification yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of the preparation method of the halogenated cyclotriphosphazene flame retardant;

[0040] Figure 2 This is a flow chart of the flash evaporation process according to an embodiment of the present invention;

[0041] Figure 3 This is a logical judgment diagram of the flash evaporation degree in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0044] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0045] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] See also Figure 1 and Figure 3 As shown, Figure 1 The present invention is a flow chart of the preparation method of the halogenated cyclotriphosphazene flame retardant; Figure 3 This is a logical judgment diagram of the flash evaporation degree in an embodiment of the present invention.

[0047] The present invention provides a method for preparing a halogenated cyclotriphosphazene flame retardant, comprising:

[0048] Step S1, adding a preset marker to the first mixed solution obtained after the reaction is completed, and stirring to obtain a second mixed solution; the second mixed solution includes a preset marker, a key solvent and a halogenated cyclotriphosphazene; the boiling point of the preset marker is lower than the boiling point of the key solvent; the key solvent is one or more of acetonitrile, ethyl acetate and xylene;

[0049] Specifically, the key solvent may be one or more of acetonitrile, ethyl acetate, xylene, dichloroethane, and benzonitrile.

[0050] In implementation, the halogenated cyclotriphosphazene includes ethoxypentafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, and hexafluorocyclotriphosphazene.

[0051] Specifically, the preset marker is determined according to the boiling point of the first mixed solution.

[0052] In implementation, the preset marker can be any liquid with a color other than colorless, which does not chemically react with any substance in the first mixed solution and has a boiling point lower than that of the key solvent.

[0053] Specifically, under standard atmospheric pressure, the preset marker boiling point temperature is less than the key solvent boiling point temperature, and the key solvent boiling point temperature is less than the halogenated cyclotriphosphazene boiling point temperature. Preferably, the boiling point temperature range of the key solvent boiling point temperature is less than or equal to 25°C of the halogenated cyclotriphosphazene boiling point temperature to less than or equal to 5°C of the halogenated cyclotriphosphazene boiling point temperature.

[0054] Step S2, passing the second mixed solution into a flash tank for flash evaporation, and determining the degree of flash evaporation according to the chromaticity of the gas in the flash tank to determine whether to adjust the gas pressure in the flash tank;

[0055] In practice, those skilled in the art know that any structure in the prior art that can perform flash evaporation to separate liquid falls within the protection scope of the present invention and will not be described in detail herein.

[0056] Step S3, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment, and determining the progress of flash evaporation according to the gas flow direction and flow rate at several positions in the flash tank;

[0057] Step S4: if the flash evaporation progress meets the preset standard, the gas in the flash evaporation tank is output to obtain high-purity halogenated cyclotriphosphazene.

[0058] The present invention adds a preset marker to the first mixed solution obtained after the reaction is completed to obtain a second mixed solution, and flashes the second mixed solution, so that the preset marker, key solvent and halogenated cyclotriphosphazene in the second mixed solution can be quickly realized. Evaporation and separation, improve the purification efficiency. Since the preset marker is different in color from other substances and has the lowest boiling point, the chromaticity of the gas in the flash tank can quickly judge the degree of flash evaporation to judge whether to adjust the air pressure in the flash tank, thereby judging whether to adjust the air pressure in the flash tank, further improve the purification efficiency. By adjusting the air pressure in the flash tank, and determining the progress of flash evaporation according to the gas flow direction and flow rate at several positions in the flash tank, it is determined whether to output the gas in the flash tank to obtain high-purity halogenated cyclotriphosphazene according to the progress of flash evaporation, and the purification yield can be improved.

[0059] See also Figure 2 As shown, it is a flow chart of the flash evaporation process of an embodiment of the present invention; specifically, in step S3, the flash evaporation process includes:

[0060] Step S31, heating the flash tank to a first preset temperature under a first preset pressure;

[0061] During implementation, actual implementers can set the first preset temperature and the first preset pressure based on the boiling point of the preset marker according to actual conditions. The first preset temperature can be set to 0.7 to 0.8 times the boiling point of the preset marker, and the first preset pressure can be set to 0.8 to 0.9 times the standard atmospheric pressure.

[0062] Step S32, obtaining the solution temperature and solution volume of the second mixed solution;

[0063] In implementation, since the reaction temperature is relatively high and the reaction time is relatively long, the temperature of the first mixed solution is close to the reaction temperature, and the boiling point of the preset marker at standard atmospheric pressure is lower than the reaction temperature. Therefore, in order to avoid the preset marker being affected when it is added to the first mixed solution, the temperature of the preset marker is adjusted to 0.45 to 0.55 times the boiling point of the preset marker, and the volume of the preset marker and the volume of the first mixed solution are 1:1 to 1:1.2.

[0064] Step S33, determining whether to adjust the flash evaporation pressure according to the solution temperature and the solution volume.

[0065] In implementation, if the solution temperature is lower than a preset temperature threshold and the solution volume is higher than a preset volume threshold, the flash evaporation pressure needs to be adjusted.

[0066] Specifically, the actual implementer can determine the preset temperature threshold based on the boiling point and temperature of the preset marker and the reaction temperature according to the actual situation. Preferably, the value range of the preset temperature threshold is 1 to 1.2 times the difference between the reaction temperature and the preset marker temperature. The actual implementer can set the preset volume threshold based on the volume of the flash tank according to the actual situation. Preferably, the value range of the preset volume threshold is 1 / 4 to 1 / 5 of the flash tank.

[0067] The present invention can improve production efficiency by first adjusting the pressure and temperature in the flash tank, and then adjusting the flash pressure according to the solution temperature and solution volume of the second mixed solution, which can further improve the subsequent purification efficiency.

[0068] Please continue reading Figure 3 As shown, specifically, in the step S3, the flash degree is determined according to the chromaticity of the gas in the flash tank;

[0069] Wherein, if the gas chromaticity is less than a first preset chromaticity threshold, it is a first flash evaporation degree;

[0070] If the gas chromaticity is greater than or equal to the first preset chromaticity threshold and less than or equal to the second preset chromaticity threshold, it is the second flash degree;

[0071] If the gas chromaticity is greater than the second preset chromaticity threshold, it is the third flash evaporation level.

[0072] In implementation, actual implementers can set the first preset chromaticity threshold and the second preset chromaticity threshold based on the chromaticity of the preset marker according to actual conditions. Preferably, the first preset chromaticity threshold is 0.4 to 0.5 times the chromaticity of the preset marker, and the second preset chromaticity threshold is 0.8 to 0.9 times the chromaticity of the preset marker. The chromaticity of the preset marker is the chromaticity measured of a single preset marker steam of the preset marker at a first preset pressure and the same volume of the preset marker mixed with the first mixed solution.

[0073] Specifically, in step S4, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment includes:

[0074] If the first flash evaporation degree is met, adjusting the gas pressure in the flash tank according to a first preset adjustment method;

[0075] If the second flash degree is met, adjusting the gas pressure in the flash tank according to a second preset adjustment method;

[0076] If the third flash degree is met, the gas pressure in the flash tank is not adjusted;

[0077] Wherein, the first preset adjustment method is to output all the gas in the flash tank to adjust the gas pressure in the flash tank;

[0078] The second preset adjustment method is to determine the gas pressure adjustment amount in the flash tank according to the current temperature of the second mixed solution.

[0079] In implementation, at the first flash evaporation degree, the gas chromaticity is less than the first preset chromaticity threshold value. At this time, only a small part of the preset markers in the second mixed solution are vaporized, indicating that the flash evaporation pressure does not meet the flash evaporation requirements, and the degree of reducing the boiling point is relatively low. The flash evaporation pressure needs to be adjusted. The flash evaporation pressure can be greatly reduced by outputting all the gas in the flash tank. At the second flash evaporation degree, the gas chromaticity is greater than or equal to the first preset chromaticity threshold value and less than or equal to the second preset chromaticity threshold value. At this time, most of the preset markers in the second mixed solution are vaporized, but some preset markers still exist in the second mixed solution. The flash evaporation pressure needs to be adjusted to further reduce the boiling point, but the reduction is relatively small. The air pressure adjustment amount P in the flash tank can be determined according to the current temperature T0 of the second mixed solution to reduce the current flash pressure. Preferably, the air pressure adjustment amount P can be determined according to the following formula:

[0080] P = ((T1-T0) / (T2-T0)) × P0;

[0081] Wherein, T1 is the first preset temperature; T2 is the preset boiling point of the marker under standard atmospheric pressure; T0 is the current temperature of the second mixed solution; P0 is the first preset pressure;

[0082] At the third flash evaporation degree, the gas chromaticity is greater than the second preset chromaticity threshold. At this time, most of the preset markers in the second mixed solution are vaporized, and there is no need to adjust the gas pressure in the flash tank to avoid waste of resources.

[0083] The present invention can quickly determine the flash evaporation degree according to the gas chromaticity in the flash evaporation tank, and can quickly and accurately adjust the gas pressure in the flash evaporation tank according to the flash evaporation degree, thereby improving the purification efficiency.

[0084] Specifically, step S3 further includes step S34, determining the flash characteristic point according to the chromaticity change curve of the preset marker in the flash tank and the pressure change curve in the flash tank.

[0085] In implementation, the time period with the fastest color change is determined based on the color change curve of the preset marker, and the pressure corresponding to the time period in the pressure change curve is determined to obtain the critical pressure. If the critical pressure is greater than the preset flash pressure, the point corresponding to the critical pressure is determined as the flash characteristic point.

[0086] Specifically, step S4 further includes step S41, adjusting the gas pressure in the flash tank according to the pressure in the flash tank corresponding to the flash characteristic point and the preset flash pressure.

[0087] In practice, the pressure corresponding to the flash characteristic point is the key pressure GP, and the pressure adjustment amount QP in the flash tank is determined according to the following formula:

[0088] QP = (GP - SP) × a;

[0089] Wherein, SP is the preset pressure of flash evaporation; a is the pressure coefficient.

[0090] Specifically, the actual implementer may determine the preset flash evaporation pressure and pressure coefficient based on historical data according to the average value of the ratio of the pressure change in the flash tank in each continuous time period during the flash evaporation process.

[0091] The present invention determines the flash characteristic point according to the chromaticity change curve and the pressure change curve in the flash tank, and further adjusts the gas pressure in the flash tank, which can further improve the accuracy of adjusting the flash tank, thereby improving the purification efficiency.

[0092] Specifically, in step S4, after the gas pressure in the flash tank is adjusted, the progress of flash evaporation is determined according to the gas flow direction at the corresponding positions of the upper and middle parts of the flash tank, the gas flow rate at the corresponding position of the middle part of the flash tank, and the pressure change in the flash tank.

[0093] Specifically, in step S4,

[0094] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are different, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the initial flash progress is met;

[0095] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the mid-term flash progress is met;

[0096] If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change in the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is not less than a preset flow rate change threshold, and the pressure change in the flash tank is less than a preset pressure threshold, it is determined that the terminal flash progress is met.

[0097] In implementation, actual implementers may determine the preset flow rate change threshold value based on the maximum value of the gas flow rate change detected during the flash evaporation process in historical data according to actual conditions.

[0098] Specifically, after the gas pressure in the flash tank is adjusted, when the initial flash evaporation progresses, the preset markers in the flash tank are basically all vaporized and tend to be stable, and the key solvent begins to vaporize, which will slowly affect the gas flow direction and flow rate in the flash tank. At this time, the gas flow rate in the flash tank is relatively low and less than the preset flow rate change threshold; when the mid-term flash evaporation progresses, the key solvent begins to gradually vaporize, so that the gas flow direction in the flash tank gradually becomes the same, and the gas flow rate in the flash tank is increased, but the change in gas flow rate per unit time is still less than the preset flow rate change threshold; when the final flash evaporation progresses, the key solvent vaporizes in large quantities, the gas flow direction in the flash tank is the same, and the change in gas flow rate per unit time is greater than or equal to the preset flow rate change threshold, the gas in the flash tank increases significantly, and when the pressure change in the flash tank is less than the preset pressure threshold, it indicates that the key solvent is basically all vaporized, which reduces the pressure change in the flash tank.

[0099] In implementation, actual implementers may determine the preset pressure threshold according to actual conditions based on the pressure change in the flash tank during the flash evaporation process in historical data.

[0100] Specifically, in step S5, if it is determined that the final flash evaporation is progressing, the preset standard is met.

[0101] In the present invention, since the boiling points of various substances are different, the low boiling point liquid is vaporized by flash evaporation, which will affect the gas pressure in the flash tank. Whether to output the gas in the flash tank is determined according to the progress of flash evaporation and preset standards, which can improve the purification yield.

[0102] Embodiment 1:

[0103] This embodiment provides a specific process flow for preparing ethoxy pentafluorocyclotriphosphazene to obtain a first mixed solution after the reaction is completed:

[0104] (1) A mol of hexachlorocyclotriphosphazene crystals and 250 ml-300 ml of a first solvent are placed in a 500 ml three-necked bottle and stirred under a stirring paddle until the crystals are completely dissolved; the value of A is in the range of 0.05-0.1; the first solvent can be one or more of hexane, toluene, benzene, acetonitrile, acetone, and cyclohexane;

[0105] (2) adding A mol sodium ethoxide, reacting at 50° C.-80° C. for 5 hours-8 hours, and filtering to obtain a phosphazene derivative (ethoxypentachlorocyclotriphosphazene);

[0106] (3) The phosphazene derivative (ethoxypentachlorocyclotriphosphazene) obtained above is dissolved in 35 g to 55 g of a key solvent, 5×A mol sodium fluoride is added under stirring, and then the mixture is reacted at 60° C. to 80° C. for 5 hours to 8 hours to prepare ethoxypentafluorocyclotriphosphazene. After the reaction is completed, a first mixed solution (including at least ethoxypentafluorocyclotriphosphazene and a key solvent) is obtained.

[0107] In this embodiment, liquid bromine is used as the preset marker.

[0108] Embodiment 2:

[0109] This embodiment provides a specific process flow for preparing hexachlorocyclotriphosphazene to obtain a first mixed solution after the reaction is completed:

[0110] (1) preparing raw materials according to the molar ratio of acid binding agent (triethylamine): anhydrous metal chloride (aluminum chloride): key solvent (chlorobenzene): main raw material A (ammonium chloride): main raw material B (phosphorus pentachloride) = (1-2): (0.1-1): (5-10): (1-1.4): 1;

[0111] (2) adding an acid binding agent (triethylamine) and anhydrous metal chloride (aluminum chloride) into a 500 ml flask according to the above molar ratio, stirring at 80 to 120° C. for 1 to 2 hours to prepare an ionic liquid;

[0112] (3) The key solvent (chlorobenzene), ammonium chloride, and phosphorus pentachloride are sequentially added into the flask containing the ionic liquid according to the above molar ratio, and then hexachlorocyclotriphosphazene is prepared by stirring at a temperature of 90° C. to 130° C. for 2 to 5 hours. After the reaction is completed, a first mixed solution (including at least hexachlorocyclotriphosphazene and the key solvent) is obtained.

[0113] In this embodiment, liquid bromine is used as the preset marker.

[0114] Embodiment 3:

[0115] This embodiment provides a specific process flow for preparing hexafluorocyclotriphosphazene to obtain a first mixed solution after the reaction is completed:

[0116] (1) Raw material preparation: the mass ratio of ethylene glycol monomethyl ether to ethylene glycol monobutyl ether is 1:(1-10), the amount of the combined catalyst is 1%-20% of the mass of hexachlorocyclotriphosphazene, and the mass ratio of the fluorinating agent to hexachlorocyclotriphosphazene is 1:(1-1.2);

[0117] (2) Synthesis reaction: In a 1000mL three-necked flask equipped with an electric stirrer, a reflux condenser, and a thermometer, add 300g of n-hexane (key solvent), cool to 0°C-2°C, add 100g of hexachlorocyclotriphosphazene and 100g of potassium fluoride, stir for 10min, dropwise add a catalyst combination liquid (a mixture of 10g of ethylene glycol monomethyl ether and 10g of ethylene glycol monobutyl ether), control the reaction temperature at 20°C-60°C for 2h-3h, then cool to 20°C-30°C and keep the temperature for 1-2h to prepare hexafluorocyclotriphosphazene. If no hexachlorocyclotriphosphazene remains in the reaction, the reaction is complete. After the reaction is completed, a first mixed solution (at least including hexafluorocyclotriphosphazene and the key solvent) is obtained.

[0118] In this embodiment, liquid bromine is used as the preset marker.

[0119] In the above three embodiments, the purity and yield of the high-purity halogenated cyclotriphosphazene obtained by the preparation method of the embodiment of the present invention and the purity and yield of the substance obtained by conventional distillation of the corresponding first mixed solution are shown in Table 1 below:

[0120] Table 1

[0121] purity Yield Example 1 99.76％ 94.32％ Distillation of the first mixed solution Comparative Example 1 98.12％ 89.26％ Example 2 87.28％ 83.14％ Distillation of the first mixed solution Comparative Example 2 86.36％ 78.62％ Example 3 92.47％ 91.38％ Distillation of the first mixed solution Comparative Example 3 89.11％ 84.34％

[0122] Table 1 shows that the purity of the high-purity halogenated cyclotriphosphazene prepared by the preparation method of the present invention is relatively higher than that of the halogenated cyclotriphosphazene obtained by conventional distillation, and the yield of the product is significantly improved. Therefore, the preparation method of the present invention can improve the purity and yield of the halogenated cyclotriphosphazene.

[0123] It should be noted that the above process flow is only used to explain part of the technical principles of the present invention, and does not limit the protection scope of the present invention. Those skilled in the art know that any method for preparing halogenated cyclotriphosphazene in the prior art falls within the protection scope of the present invention and will not be described in detail herein.

[0124] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for preparing a halogenated cyclotriphosphazene flame retardant, characterized in that: include: Step S1, adding a preset marker to the first mixed solution obtained after the reaction is completed, and stirring to obtain a second mixed solution; The second mixed solution includes a preset marker, a key solvent and a halogenated cyclotriphosphazene; the boiling point of the preset marker is lower than the boiling point of the key solvent; the key solvent is one or more of acetonitrile, ethyl acetate and xylene; Step S2, passing the second mixed solution into a flash tank for flash evaporation, and determining the degree of flash evaporation according to the chromaticity of the gas in the flash tank to determine whether to adjust the gas pressure in the flash tank; Step S3, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment, and determining the progress of flash evaporation according to the gas flow direction and flow rate at several positions in the flash tank; Step S4: if the flash evaporation progress meets the preset standard, the gas in the flash evaporation tank is output to obtain high-purity halogenated cyclotriphosphazene.

2. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 1, characterized in that: The preset marker is determined according to the boiling point of the first mixed solution.

3. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 2, characterized in that: In step S3, the flash evaporation process includes: Step S31, heating the flash tank to a first preset temperature under a first preset pressure; Step S32, obtaining the solution temperature and solution volume of the second mixed solution; Step S33, determining whether to adjust the flash evaporation pressure according to the solution temperature and the solution volume.

4. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 3, characterized in that: In the step S3, the flash degree is determined according to the chromaticity of the gas in the flash tank; Wherein, if the gas chromaticity is less than a first preset chromaticity threshold, it is a first flash evaporation degree; If the gas chromaticity is greater than or equal to the first preset chromaticity threshold and less than or equal to the second preset chromaticity threshold, it is the second flash degree; If the gas chromaticity is greater than the second preset chromaticity threshold, it is the third flash evaporation level.

5. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 4, characterized in that: In step S4, adjusting the gas pressure in the flash tank based on the judgment result of the gas pressure adjustment includes: If the first flash evaporation degree is met, adjusting the gas pressure in the flash tank according to a first preset adjustment method; If the second flash evaporation degree is met, adjusting the gas pressure in the flash tank according to a second preset adjustment method; If the third flash degree is met, the gas pressure in the flash tank is not adjusted; Wherein, the first preset adjustment method is to output all the gas in the flash tank to adjust the gas pressure in the flash tank; The second preset adjustment method is to determine the gas pressure adjustment amount in the flash tank according to the current temperature of the second mixed solution.

6. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 1, characterized in that: In step S3, step S34 is also included, determining the flash characteristic point according to the chromaticity change curve of the preset marker in the flash tank and the pressure change curve in the flash tank.

7. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 6, characterized in that: In step S4, step S41 is also included, adjusting the gas pressure in the flash tank according to the pressure in the flash tank corresponding to the flash characteristic point and the preset flash pressure.

8. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 1, characterized in that: In step S4, after the gas pressure in the flash tank is adjusted, the progress of flash evaporation is determined according to the gas flow direction at the corresponding positions of the upper and middle parts of the flash tank, the gas flow rate at the corresponding position of the middle part of the flash tank, and the pressure change in the flash tank.

9. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 8, characterized in that: In step S4, If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are different, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the initial flash progress is met; If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change of the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is less than the preset flow rate change threshold, it is determined that the mid-term flash progress is met; If the gas flow directions at the corresponding positions of the upper and middle parts of the flash tank are the same, and the change in the gas flow rate per unit time at the corresponding position of the middle part of the flash tank is not less than a preset flow rate change threshold, and the pressure change in the flash tank is less than a preset pressure threshold, it is determined that the terminal flash progress is met.

10. The method for preparing the halogenated cyclotriphosphazene flame retardant according to claim 9, characterized in that: In the step S5, if it is determined that the final flash evaporation is progressing, it meets the preset standard.

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