A preparation method of TBC flame retardant

Abstract

The invention discloses a preparation method of a TBC flame retardant, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: bromination and crystallization; in the bromination, TAIC and dichloromethane are mixed, stirred at 26-30 DEG C, bromine is added dropwise, stirred after the addition is completed, deionized water is added, stirred, a sodium sulfite aqueous solution is added dropwise until the red brown color disappears, a debrominating agent is added after the addition is completed, stirred, allowed to stand, an organic layer is taken, the organic layer is mixed with a sodium hydroxide aqueous solution, stirred at 25-30 DEG C, allowed to stand, the organic layer is taken, suction filtration is performed, a filtrate is taken, and the filtrate is washed; the preparation method of the invention can reduce the loss of dichloromethane in reuse, improve the crystallization precipitation speed and yield of the prepared TBC flame retardant, ensure that the particle size distribution of the prepared TBC flame retardant is uniform, reduce the chroma of the prepared TBC flame retardant, and reduce environmental pollution.

Description

Technical Field

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

[0002] The chemical name of TBC flame retardant is tris (2,3-dibromopropyl) isocyanurate. It appears as white powder or crystalline powder. It is a new, high-efficiency, additive bromine flame retardant with the advantages of good flame retardant effect, low volatility, good compatibility, good durability, good light resistance, good water resistance and non-toxicity. It can be widely used in polyolefins, polyvinyl chloride, foamed polyurethane, unsaturated polyester, synthetic rubber and synthetic fiber products.

[0003] The traditional preparation method of TBC flame retardant is to add triallyl isocyanurate (TAIC) to dichloromethane, then add bromine to react, obtain a dichloromethane solution containing TBC flame retardant, and then drop the dichloromethane solution containing TBC flame retardant into a precipitant, the commonly used precipitant is methanol, and the precipitant causes the TBC flame retardant to crystallize and precipitate to obtain TBC flame retardant. This method has the following problems: in the reuse of dichloromethane, dichloromethane and the precipitant need to be separated, resulting in a large loss of dichloromethane in the reuse; in the reuse of dichloromethane, the separated sewage containing the precipitant is directly discharged, resulting in serious environmental pollution; after the addition of the precipitant, the TBC flame retardant cannot be completely crystallized, resulting in a low yield of the TBC flame retardant; the obtained TBC flame retardant contains a small amount of bromine, resulting in a high chromaticity of the TBC flame retardant.

[0004] In view of the above problems, the existing solutions are as follows: first, using a high boiling point precipitant that does not contain methanol, when separating dichloromethane from the precipitant, pure dichloromethane can be obtained by distillation, and then the precipitant is directly reused, thereby reducing the loss of dichloromethane in the reuse and reducing the pollution to the environment; second, mixing high-purity TBC flame retardant powder with the precipitant, that is, adding a dichloromethane solution containing TBC flame retardant dropwise into a mixture of high-purity TBC flame retardant powder and the precipitant, and using the high-purity TBC flame retardant powder as a seed to increase the crystallization amount of TBC flame retardant, thereby improving the yield of TBC flame retardant; third, using a reducing agent sodium bisulfite aqueous solution to treat the dichloromethane solution of TBC flame retardant to remove bromine and reduce the chromaticity of the TBC flame retardant.

[0005] However, it was found in the experiment that the above solution has the following shortcomings: first, since methanol has a low molecular weight, strong dispersibility and strong polarity, the high boiling point precipitant has a high molecular weight and weaker polarity than methanol. Therefore, compared with methanol, the precipitation rate of the high boiling point precipitant is slow, resulting in a slower crystallization rate of the TBC flame retardant, which further prolongs the preparation time of the TBC flame retardant; second, when the dichloromethane solution containing the TBC flame retardant is added dropwise to the mixture of the high-purity TBC flame retardant powder and the precipitant, part of the high-purity TBC flame retardant powder will dissolve, resulting in a slower crystallization rate, which further prolongs the preparation time of the TBC flame retardant, and there will also be a problem of uneven crystal growth rate, resulting in uneven particle size distribution of the prepared TBC flame retardant; third, since bromine can be dissolved in dichloromethane, the reducing agent sodium bisulfite aqueous solution cannot completely remove bromine in the dichloromethane solution of the TBC flame retardant, resulting in limited effect on reducing the chromaticity of the TBC flame retardant. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing a TBC flame retardant, which can reduce the loss of dichloromethane in recycling, improve the crystallization precipitation speed and yield of the prepared TBC flame retardant, ensure that the particle size distribution of the prepared TBC flame retardant is uniform, reduce the chroma of the prepared TBC flame retardant, and reduce environmental pollution.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a TBC flame retardant, comprising the following steps: bromination, crystallization;

[0009] The bromination, TAIC, dichloromethane are added to a reactor, the temperature in the reactor is controlled to 26-30 ° C, the stirring speed is controlled to 100-200rpm, stirring for 20-30min, bromine is added dropwise, stirring for 140-160min after the addition is completed, deionized water is added, stirring for 20-30min, sodium sulfite aqueous solution is added dropwise until the red brown color disappears, a debrominating agent is added after the addition is completed, stirring for 30-40min, standing for 2-2.5h, taking an organic layer, adding the organic layer and sodium hydroxide aqueous solution to a reactor, the temperature in the reactor is controlled to 25-30 ° C, the stirring speed is controlled to 200-400rpm, stirring for 20-30min, standing for 2-2.5h, taking an organic layer, filtering, taking a filtrate, washing the filtrate with deionized water 2-3 times, and obtaining a dichloromethane solution containing TBC flame retardant;

[0010] In the bromination, the mass ratio of TAIC, dichloromethane, bromine, deionized water, debrominating agent, and sodium hydroxide aqueous solution is 1000:3000-3200:1970-2030:950-1050:32-35:1400-1500;

[0011] The mass purity of the TAIC is 99.0%;

[0012] The mass purity of the bromine is 99.4%;

[0013] The mass concentration of the sodium sulfite aqueous solution is 10%;

[0014] The mass concentration of the sodium hydroxide aqueous solution is 10%;

[0015] The dropping speed of the bromine is 45-50g / min;

[0016] The dropping speed of the sodium sulfite aqueous solution is 30-40 g / min;

[0017] The preparation method of the debrominating agent comprises the following steps: adding sodium aluminate and deionized water into a reactor, controlling the temperature of the reactor to 30-35° C., controlling the stirring speed to 100-300 rpm, stirring for 15-20 min, adding urea, stirring for 50-60 min, transferring the mixture into a hydrothermal reactor, sealing the hydrothermal reactor, placing the hydrothermal reactor in an oven, controlling the temperature of the oven to 120-130° C., placing the mixture for 4-5 h, opening the hydrothermal reactor, transferring the mixture into a centrifuge, controlling the centrifugal speed of the centrifuge to 7000-8000 rpm, centrifuging for 9-10 min, taking a precipitate, washing the precipitate with deionized water for 3-4 times, and then drying the mixture to obtain the debrominating agent;

[0018] In the preparation of the debromination agent, the mass ratio of sodium aluminate, deionized water and urea is 82-85:1000-1050:180-190;

[0019] The crystallization comprises adding high-purity TBC flame retardant powder, sodium hexadecyl sulfate, hexadecyltrimethylammonium bromide, ethanol and isopropanol into a reactor, controlling the temperature of the reactor to 55-58° C., controlling the stirring speed to 200-250 rpm, stirring for 30-40 min, dripping a dichloromethane solution containing the TBC flame retardant, stirring for 70-80 min after the dripping is completed, controlling the temperature of the reactor to 20-30° C., stirring for 20-25 min, collecting and reusing the dichloromethane evaporated throughout the process, and then filtering, taking the filtrate and the filter residue respectively, the filtrate being a mixed solution of ethanol and isopropanol, reusing the filtrate, washing the filter residue with deionized water for 5-6 times, and then drying to obtain the TBC flame retardant;

[0020] In the crystallization, the mass ratio of high-purity TBC flame retardant powder, sodium cetyl sulfate, cetyltrimethylammonium bromide, ethanol and isopropanol is 270-300:28-30:28-30:15000-16000:4000-6000;

[0021] The mass ratio of the high-purity TBC flame retardant powder in the crystallization to the TAIC in the bromination is 270-300:1000;

[0022] The dropping speed of the dichloromethane solution containing TBC flame retardant is 40-50g / min;

[0023] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The preparation method of TBC flame retardant of the present invention comprises the following steps: in the bromination step, a debrominating agent is added to the bromination product, wherein the debrominating agent is aluminum hydroxide microspheres having a large specific surface area and strong adsorption prepared by a hydrothermal method using sodium metaaluminate as a raw material. After the debrominating agent is added to the bromination product, on the one hand, it can play a catalytic role, and on the other hand, it can adsorb the remaining bromine in the dichloromethane and further react with the unreacted TAIC, thereby improving the total conversion rate of the TBC flame retardant, and also adsorbing the remaining bromine, thereby reducing the chromaticity of the TBC flame retardant. After adding a sodium hydroxide aqueous solution, the debrominating agent and the bromine on its surface react with the sodium hydroxide, thereby removing the debrominating agent and the bromine. Then, after standing, the organic layer is taken out and filtered to further remove impurities, thereby obtaining to a dichloromethane solution containing TBC flame retardant; in the crystallization step, the present invention also adds a surfactant, specifically a cationic surfactant and an anionic surfactant, to the mixture of the high-purity TBC flame retardant powder and the precipitant. During crystallization, the cationic surfactant and the anionic surfactant form vesicles on the surface of the high-purity TBC flame retardant powder under the action of electrostatics and groups, thereby protecting the high-purity TBC flame retardant powder from being dissolved by dichloromethane, thereby improving the total conversion rate of the TBC flame retardant; in the process of dripping the dichloromethane solution containing the TBC flame retardant, the presence of the vesicles can promote the growth of crystal grains, avoid the problem of uneven crystal growth rate, thereby ensuring that the prepared TBC flame retardant has a uniform particle size distribution;

[0026] (2) The preparation method of the TBC flame retardant of the present invention avoids the use of methanol and omits the subsequent separation process of dichloromethane and methanol, thereby reducing the loss of dichloromethane during recycling, avoiding the discharge of wastewater containing methanol, and reducing environmental pollution;

[0027] (3) The preparation method of the TBC flame retardant of the present invention can improve the crystallization rate of the prepared TBC flame retardant. After the dichloromethane solution containing the TBC flame retardant is added dropwise, the mixture is stirred at 55-58°C for 70-80 minutes and at 20-30°C for 20-25 minutes to complete the crystallization.

[0028] (4) The preparation method of the TBC flame retardant of the present invention can improve the yield of the prepared TBC flame retardant. The total yield of the TBC flame retardant prepared by the present invention is 95.6-96.4%, and the mass purity is 99.1-99.3%;

[0029] (5) The preparation method of the TBC flame retardant of the present invention can ensure that the particle size distribution of the prepared TBC flame retardant is uniform. The particle size distribution width SPAN value of the TBC flame retardant prepared by the present invention is 0.8-0.9;

[0030] (6) The preparation method of the TBC flame retardant of the present invention can reduce the chromaticity of the prepared TBC flame retardant. The chromaticity APHA of the TBC flame retardant prepared by the present invention is 14-17. DETAILED DESCRIPTION

[0031] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0032] The calculation formula of the total yield in Examples 1-3 and Comparative Examples 1-3 is: [(the mass of the TBC flame retardant obtained in the second crystallization step × the mass purity of the TBC flame retardant obtained in the second crystallization step - the mass of the high-purity TBC flame retardant powder added in the second crystallization step × the mass purity of the high-purity TBC flame retardant powder added in the second crystallization step) / 729] / [(the mass of TAIC added in the first bromination step × the mass purity of TAIC added in the first bromination step) / 249]×100%;

[0033] Particle size distribution width SPAN value = (D90 particle size - D10 particle size) / D50 particle size × 100%.

[0034] Example 1

[0035] A method for preparing a TBC flame retardant, specifically comprising:

[0036] 1. Bromination: Add 1000g TAIC and 3000g dichloromethane to a reactor, control the temperature in the reactor to 26°C, control the stirring speed to 100rpm, stir for 20min, add 1970g bromine dropwise, control the dropping speed to 45g / min, stir for 140min after the dropping is completed, add 950g deionized water, stir for 20min, add sodium sulfite aqueous solution dropwise until the reddish brown color disappears, control the dropping speed to 30g / min, add 32g debrominating agent after the dropping is completed, stir for 30min, let stand for 2h, take the organic layer, add the organic layer and 1400g sodium hydroxide aqueous solution to the reactor, control the temperature in the reactor to 25°C, control the stirring speed to 200rpm, stir for 20min, let stand for 2h, take the organic layer, filter, take the filtrate, wash the filtrate twice with deionized water, and use 1000g of deionized water each time to obtain a dichloromethane solution containing TBC flame retardant;

[0037] The mass purity of the TAIC is 99.0%;

[0038] The mass purity of the bromine is 99.4%;

[0039] The mass concentration of the sodium sulfite aqueous solution is 10%;

[0040] The mass concentration of the sodium hydroxide aqueous solution is 10%;

[0041] The preparation method of the debrominating agent is as follows: 82g of sodium aluminate and 1000g of deionized water are added into a reactor, the temperature of the reactor is controlled to 30°C, the stirring speed is controlled to 100rpm, the mixture is stirred for 15min, 180g of urea is added, the mixture is stirred for 50min, the mixture is transferred into a hydrothermal reactor, the hydrothermal reactor is sealed, the hydrothermal reactor is placed in an oven, the temperature of the oven is controlled to 120°C, the mixture is placed for 4h, the hydrothermal reactor is opened, the mixture is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 7000rpm, the mixture is centrifuged for 9min, a precipitate is taken, the precipitate is washed 3 times with deionized water, 400g of deionized water is used for each washing, and the mixture is dried to obtain the debrominating agent;

[0042] 2. Crystallization: 270g high-purity TBC flame retardant powder, 28g sodium hexadecyl sulfate, 28g hexadecyltrimethylammonium bromide, 15000g ethanol, 4000g isopropanol were added to the reactor, the temperature of the reactor was controlled to 55°C, the stirring speed was controlled to 200rpm, and the mixture was stirred for 30min. The dichloromethane solution containing all the TBC flame retardants obtained in the first step of the bromination step was added dropwise, and the dropping speed was controlled to 40g / min. After the addition was completed, the mixture was stirred for 70min. The temperature of the reactor was controlled to 20°C, and the mixture was stirred for 20min. The dichloromethane evaporated was collected and reused throughout the process, and then filtered, and the filtrate and the residue were taken respectively. The filtrate was a mixed solution of ethanol and isopropanol. The filtrate was reused, and the residue was washed with deionized water 5 times. The amount of deionized water used for each washing was 11000g, and then dried to obtain TBC flame retardant.

[0043] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0044] The mass of the TBC flame retardant obtained in this example is 3067.3 g, the mass purity is 99.1%, the total yield is 95.6%, the particle size distribution width SPAN value is 0.8, and the chromaticity APHA is 17.

[0045] Example 2

[0046] A method for preparing a TBC flame retardant, specifically comprising:

[0047] 1. Bromination: 1000g TAIC, 3100g dichloromethane were added to the reactor, the temperature in the reactor was controlled to 28 ° C, the stirring speed was controlled to 150rpm, stirred for 25min, 2000g bromine was added dropwise, the dropping speed was controlled to 48g / min, and the stirring was continued for 150min after the addition was completed. 1000g deionized water was added and stirred for 25min, and sodium sulfite aqueous solution was added dropwise until the reddish brown color disappeared, and the dropping speed was controlled to 35g / min. After the addition was completed, 34g of debrominating agent was added, stirred for 35min, and allowed to stand for 2.5h, and the organic layer was taken. The organic layer and 1450g of sodium hydroxide aqueous solution were added to the reactor, the temperature in the reactor was controlled to 28 ° C, the stirring speed was controlled to 300rpm, stirred for 25min, and allowed to stand for 2.5h, the organic layer was taken, and the filtrate was taken by suction. The filtrate was washed 3 times with deionized water, and the amount of deionized water used for each washing was 1050g to obtain a dichloromethane solution containing TBC flame retardant;

[0048] The mass purity of the TAIC is 99.0%;

[0049] The mass purity of the bromine is 99.4%;

[0050] The mass concentration of the sodium sulfite aqueous solution is 10%;

[0051] The mass concentration of the sodium hydroxide aqueous solution is 10%;

[0052] The preparation method of the debrominating agent is as follows: 84g of sodium aluminate and 1020g of deionized water are added into a reactor, the temperature of the reactor is controlled to 32°C, the stirring speed is controlled to 200rpm, the reaction is stirred for 18min, 185g of urea is added, the reaction is stirred for 55min, the reaction is transferred into a hydrothermal reactor, the hydrothermal reactor is sealed, the hydrothermal reactor is placed in an oven, the temperature of the oven is controlled to 125°C, the reaction is placed for 4.5h, the hydrothermal reactor is opened, the reaction is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 7500rpm, the reaction is centrifuged for 10min, a precipitate is taken, the precipitate is washed 4 times with deionized water, the amount of deionized water used in each washing is 450g, and then the reaction is dried to obtain the debrominating agent;

[0053] 2. Crystallization: 280g high-purity TBC flame retardant powder, 29g sodium hexadecyl sulfate, 29g hexadecyltrimethylammonium bromide, 15500g ethanol, 5000g isopropanol were added to the reactor, the temperature of the reactor was controlled to 56°C, the stirring speed was controlled to 250rpm, and the mixture was stirred for 35min. The dichloromethane solution containing all the TBC flame retardants obtained in the first step of the bromination step was added dropwise, and the dropping speed was controlled to 45g / min. After the addition was completed, the mixture was stirred for 75min. The temperature of the reactor was controlled to 25°C, and the mixture was stirred for 23min. The dichloromethane evaporated was collected and reused throughout the process, and then filtered, and the filtrate and the residue were taken respectively. The filtrate was a mixed solution of ethanol and isopropanol. The filtrate was reused, and the residue was washed with deionized water 6 times. The amount of deionized water used for each washing was 12000g, and then dried to obtain TBC flame retardant.

[0054] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0055] The mass of the TBC flame retardant obtained in this example is 3095.1 g, the mass purity is 99.3%, the total yield is 96.4%, the particle size distribution width SPAN value is 0.8, and the chromaticity APHA is 14.

[0056] Example 3

[0057] A method for preparing a TBC flame retardant, specifically comprising:

[0058] 1. Bromination: 1000g TAIC, 3200g dichloromethane were added to the reactor, the temperature in the reactor was controlled to 30°C, the stirring speed was controlled to 200rpm, and the stirring was performed for 30min. 2030g bromine was added dropwise, and the dropping speed was controlled to 50g / min. After the dropping was completed, the stirring was performed for 160min. 1050g deionized water was added, and the stirring was performed for 30min. A sodium sulfite aqueous solution was added dropwise until the reddish brown color disappeared, and the dropping speed was controlled to 40g / min. After the dropping was completed, 35g of a bromine removal agent was added, and the mixture was stirred for 40min. The mixture was allowed to stand for 2.5h. The organic layer was taken, and the organic layer and 1500g of a sodium hydroxide aqueous solution were added to the reactor, the temperature in the reactor was controlled to 30°C, the stirring speed was controlled to 400rpm, and the mixture was stirred for 30min. The mixture was allowed to stand for 2.5h. The organic layer was taken, and the filtrate was taken by suction. The filtrate was washed 3 times with deionized water, and the amount of deionized water used for each washing was 1100g to obtain a dichloromethane solution containing a TBC flame retardant.

[0059] The mass purity of the TAIC is 99.0%;

[0060] The mass purity of the bromine is 99.4%;

[0061] The mass concentration of the sodium sulfite aqueous solution is 10%;

[0062] The mass concentration of the sodium hydroxide aqueous solution is 10%;

[0063] The preparation method of the debrominating agent is as follows: 85g of sodium aluminate and 1050g of deionized water are added into a reactor, the temperature of the reactor is controlled to 35°C, the stirring speed is controlled to 300rpm, the mixture is stirred for 20min, 190g of urea is added, the mixture is stirred for 60min, the mixture is transferred into a hydrothermal reactor, the hydrothermal reactor is sealed, the hydrothermal reactor is placed in an oven, the temperature of the oven is controlled to 130°C, the mixture is placed for 5h, the hydrothermal reactor is opened, the mixture is transferred into a centrifuge, the centrifugal speed of the centrifuge is controlled to 8000rpm, the mixture is centrifuged for 10min, a precipitate is taken, the precipitate is washed 4 times with deionized water, 500g of deionized water is used for each washing, and the mixture is dried to obtain the debrominating agent;

[0064] 2. Crystallization: 300g high-purity TBC flame retardant powder, 30g sodium hexadecyl sulfate, 30g hexadecyltrimethylammonium bromide, 16000g ethanol, and 6000g isopropanol were added to a reactor, the temperature of the reactor was controlled to 58°C, the stirring speed was controlled to 250rpm, and the mixture was stirred for 40min. The dichloromethane solution containing all the TBC flame retardants obtained in the first step of the bromination step was added dropwise, and the dropping speed was controlled to 50g / min. After the addition was completed, the mixture was stirred for 80min. The temperature of the reactor was controlled to 30°C, and the mixture was stirred for 25min. The dichloromethane evaporated was collected and reused throughout the process, and then filtered, and the filtrate and the residue were taken respectively. The filtrate was a mixed solution of ethanol and isopropanol. The filtrate was reused, and the residue was washed with deionized water 6 times. The amount of deionized water used for each washing was 13000g, and then dried to obtain TBC flame retardant.

[0065] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0066] The mass of the TBC flame retardant obtained in this example is 3109.4 g, the mass purity is 99.3%, the total yield is 96.2%, the particle size distribution width SPAN value is 0.9, and the chromaticity APHA is 15.

[0067] Comparative Example 1

[0068] Based on the preparation method of the TBC flame retardant in Example 2, the addition of the debromination agent is omitted in the first bromination step, that is, the first bromination step is changed to:

[0069] 1. Bromination: Add 1000g TAIC and 3000g dichloromethane to a reactor, control the temperature in the reactor to 26°C, control the stirring speed to 100rpm, stir for 20min, add 1970g bromine dropwise, control the dropping speed to 45g / min, stir for 140min after the dropping is completed, add 950g deionized water, stir for 20min, add sodium sulfite aqueous solution dropwise until the reddish brown color disappears, control the dropping speed to 30g / min, stir for 30min after the dropping is completed, let stand for 2h, take the organic layer, add the organic layer and 1400g sodium hydroxide aqueous solution to the reactor, control the temperature in the reactor to 25°C, control the stirring speed to 200rpm, stir for 20min, let stand for 2h, take the organic layer, filter, take the filtrate, wash the filtrate twice with deionized water, and use 1000g of deionized water each time to obtain a dichloromethane solution containing TBC flame retardant;

[0070] The mass purity of the TAIC is 99.0%;

[0071] The mass purity of the bromine is 99.4%;

[0072] The mass concentration of the sodium sulfite aqueous solution is 10%;

[0073] The mass concentration of the sodium hydroxide aqueous solution is 10%.

[0074] The remaining operations are the same as those in Example 2.

[0075] The mass of the TBC flame retardant obtained in this comparative example is 3001.7 g, the mass purity is 98.9%, the total yield is 92.8%, the particle size distribution width SPAN value is 0.7, and the chromaticity APHA is 44.

[0076] Comparative Example 2

[0077] Based on the preparation method of the TBC flame retardant of Example 2, the addition of sodium cetyl sulfate and cetyl trimethyl ammonium bromide is omitted in the second crystallization step, that is, the second crystallization step is changed to:

[0078] 2. Crystallization: 280g high-purity TBC flame retardant powder, 15500g ethanol, and 5000g isopropanol were added to a reactor, the temperature of the reactor was controlled to 56°C, the stirring speed was controlled to 250rpm, and the mixture was stirred for 35min. The dichloromethane solution containing all the TBC flame retardants obtained in the first bromination step was added dropwise, and the dropping speed was controlled to 45g / min. After the addition was completed, the mixture was stirred for 75min. The temperature of the reactor was controlled to 25°C, and the mixture was stirred for 23min. The dichloromethane evaporated was collected and reused throughout the process, and then filtered, and the filtrate and the residue were taken respectively. The filtrate was a mixed solution of ethanol and isopropanol. The filtrate was reused, and the residue was washed with deionized water 6 times. The amount of deionized water used for each washing was 12000g, and then dried to obtain TBC flame retardant.

[0079] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0080] The remaining operations are the same as those in Example 2.

[0081] The mass of the TBC flame retardant obtained in this comparative example is 2583.2 g, the mass purity is 99.2%, the total yield is 78.8%, the particle size distribution width SPAN value is 2.0, and the chromaticity APHA is 16.

[0082] Comparative Example 3

[0083] Based on the preparation method of the TBC flame retardant of Comparative Example 2, the crystallization time in the second crystallization step is multiplied by 2, that is, the second crystallization step is changed to:

[0084] 2. Crystallization: 280g high-purity TBC flame retardant powder, 15500g ethanol, and 5000g isopropanol were added to a reactor, the temperature of the reactor was controlled to 56°C, the stirring speed was controlled to 250rpm, and the mixture was stirred for 35min. The dichloromethane solution containing all the TBC flame retardants obtained in the first step of bromination was added dropwise, and the dropping speed was controlled to 45g / min. After the addition was completed, the mixture was stirred for 150min. The temperature of the reactor was controlled to 25°C, and the mixture was stirred for 23min. The dichloromethane evaporated was collected and reused throughout the process, and then filtered, and the filtrate and the residue were taken respectively. The filtrate was a mixed solution of ethanol and isopropanol. The filtrate was reused, and the residue was washed with deionized water for 6 times. The amount of deionized water used for each washing was 12000g, and then dried to obtain TBC flame retardant.

[0085] The mass purity of the high-purity TBC flame retardant powder is 99.5%.

[0086] The remaining operations are the same as those in Example 2.

[0087] The mass of the TBC flame retardant obtained in this example is 3058.7 g, the mass purity is 99.2%, the total yield is 95.1%, the particle size distribution width SPAN value is 2.8, and the chromaticity APHA is 17.

[0088] It can be seen from the above results that in Comparative Example 1, the addition of the bromine removal agent is omitted in the first bromination step, resulting in low yield and mass purity of the prepared TBC flame retardant and high chromaticity APHA; in Comparative Example 2, the addition of sodium hexadecyl sulfate and hexadecyltrimethylammonium bromide is omitted in the second crystallization step, resulting in low yield of the prepared TBC flame retardant and large particle size distribution width SPAN value. In order to prove the influence of sodium hexadecyl sulfate and hexadecyltrimethylammonium bromide on the crystallization time, Comparative Example 3 is added. Comparative Example 3 prolongs the crystallization time on the basis of Comparative Example 2. Compared with Comparative Example 2, the yield of the prepared TBC flame retardant is improved, but there is still a problem of large particle size distribution width SPAN value, which further illustrates that the addition of sodium hexadecyl sulfate and hexadecyltrimethylammonium bromide can shorten the crystallization time and reduce the particle size distribution width SPAN value.

[0089] Unless otherwise specified, all percentages used in the present invention are by mass.

[0090] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a tris(2,3-dibromopropyl)isocyanurate flame retardant, characterized in that: The method comprises the following steps: bromination, crystallization; The bromination comprises mixing TAIC and dichloromethane, stirring at 26-30° C. for 20-30 min, dropping bromine, stirring for 140-160 min after the dropping, adding deionized water, stirring for 20-30 min, dropping sodium sulfite aqueous solution until the reddish brown color disappears, adding a debrominating agent after the dropping, stirring for 30-40 min, standing for 2-2.5 h, taking an organic layer, mixing the organic layer with a sodium hydroxide aqueous solution, stirring for 20-30 min at 25-30° C., standing for 2-2.5 h, taking an organic layer, filtering, taking a filtrate, washing the filtrate, and obtaining a dichloromethane solution containing tris(2,3-dibromopropyl)isocyanurate flame retardant; The preparation method of the debrominating agent comprises the following steps: mixing sodium aluminate and deionized water, stirring at 30-35° C. for 15-20 minutes, adding urea, stirring for 50-60 minutes, performing a hydrothermal reaction at 120-130° C. for 4-5 hours, centrifuging, taking a precipitate, washing the precipitate and drying it to obtain the debrominating agent; The crystallization comprises mixing high-purity tris(2,3-dibromopropyl)isocyanurate flame retardant powder, sodium cetyl sulfate, cetyltrimethylammonium bromide, ethanol and isopropanol, stirring at 55-58° C. for 30-40 minutes, dropping a dichloromethane solution containing the tris(2,3-dibromopropyl)isocyanurate flame retardant, stirring for 70-80 minutes after the dropping is completed, stirring at 20-30° C. for 20-25 minutes, filtering by suction, taking a filter residue, washing the filter residue and drying it to obtain the tris(2,3-dibromopropyl)isocyanurate flame retardant.

2. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: In the bromination, the mass ratio of TAIC, dichloromethane, bromine, deionized water, debrominating agent and sodium hydroxide aqueous solution is 1000:3000-3200:1970-2030:950-1050:32-35:1400-1500.

3. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: In the bromination, the mass concentration of the sodium sulfite aqueous solution is 10%; The mass concentration of the sodium hydroxide aqueous solution is 10%.

4. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: In the bromination, the dropping speed of the bromine is 45-50 g / min; The dropping speed of the sodium sulfite aqueous solution is 30-40 g / min.

5. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: In the preparation of the debromine agent, the mass ratio of sodium aluminate, deionized water and urea is 82-85:1000-1050:180-190.

6. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: In the crystallization, the mass ratio of high-purity tris (2, 3-dibromopropyl) isocyanurate flame retardant powder, sodium cetyl sulfate, cetyl trimethyl ammonium bromide, ethanol and isopropanol is 270-300: 28-30: 28-30: 15000-16000: 4000-6000.

7. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: The mass ratio of the high-purity tris(2,3-dibromopropyl)isocyanurate flame retardant powder in the crystallization to the TAIC in the bromination is 270-300:1000.

8. The method for preparing the tris(2,3-dibromopropyl)isocyanurate flame retardant according to claim 1, characterized in that: During the crystallization, the dropping speed of the dichloromethane solution containing tris(2,3-dibromopropyl)isocyanurate flame retardant is 40-50 g / min.