Method for preparing DOPO reactive flame retardant through continuous flow

Abstract

The invention relates to a method for preparing a DOPO reactive flame retardant through continuous flow, and belongs to the field of organic synthesis. By selecting specific continuous flow reaction conditions, high-efficiency, high-quality and high-selectivity continuous flow preparation of the DOPO reactive flame retardant is realized. According to the method for preparing the DOPO reactive flame retardant through the continuous flow, the reaction process is optimized through a specific continuous flow feeding mode, a traditional reaction kettle and a traditional device are replaced, and the yield of a reaction product is increased; the purity of the reaction product DOPO can be further improved by precisely regulating and controlling the content of zinc and aluminum elements in the catalyst, safe, environment-friendly and efficient synthesis of the flame retardant is achieved, and the application prospect is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing a DOPO reactive flame retardant in a continuous flow. Background Art

[0002] With the rapid development of modern science and technology and industry, polymer materials have been widely used in various fields. However, due to the flammability of polymer materials, once a fire occurs, it will cause huge losses of life and property. Usually, it is necessary to add flame retardants to polymer materials to improve the flame retardant properties of polymer materials in order to ensure the safety of people's lives and property.

[0003] .

[0004] Among many flame retardants, phosphorus-containing flame retardants have the advantages of good flame retardant effect, good thermal stability, good environmental performance, and good economy, and are widely used in plastics, rubber, textiles, coatings and other materials. 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives have the advantages of good flame retardant performance, halogen-free and non-toxic, and environmentally friendly, and are widely added to polymer materials to improve the flame retardant properties of polymer materials. DOPO has a unique chemical structure, and its active PH bond is easy to react with carbon-carbon double bonds, epoxy, and carbonyl groups to obtain DOPO derivatives. Therefore, it is of great significance to develop a method for preparing DOPO compounds with simple operation, high product yield and purity.

[0005] Traditional reactor devices have a lot of drawbacks when producing DOPO, such as large investment in vacuum distillation equipment, repeated heating and cooling during the kettle reaction, cumbersome operation, and long-term operation will seriously damage the life of the machine, causing safety hazards. CN102617644A discloses a method for synthesizing a flame retardant intermediate DOPO, which is cumbersome to operate, will cause a large amount of phosphorus trichloride loss during the reaction, and will have an impact on the environment during production. In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a method for preparing a DOPO reactive flame retardant in a continuous flow. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a method for preparing a DOPO reactive flame retardant by continuous flow, comprising the following steps: S1, mixing the composite catalyst and the phosphorus trichloride solution to form a suspension, and then transporting them to a continuous flow preheating reactor for preheating, and then pumping the preheated mixture and the preheated OPP into the first premixing module in the microchannel reactor for full premixing; S2, the premixed materials are then pumped into the first reaction module, the second reaction module, and the third reaction module in sequence for programmed temperature control reaction to obtain a mixed solution; S3. Decolorize, filter, hydrolyze and wash the outflowing mixed solution to obtain DOPO.

[0007] The reaction route of the method is: ; The molar ratio of the raw material OPP to the raw material PCl3 is 1: (1.0-1.5); The composite catalyst is a composite catalyst formed by anhydrous zinc chloride and any one or more of anhydrous aluminum chloride, anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous nickel chloride, anhydrous molybdenum chloride and anhydrous manganese chloride.

[0008] The mass ratio of the raw material OPP to the composite catalyst is 1:(0.005-0.15); the molar proportion of zinc element in the composite catalyst is 60-95%.

[0009] The composite catalyst and phosphorus trichloride solution are preheated to 70-90°C in a continuous flow preheating reactor; Preheat OPP to 70~90℃.

[0010] The temperature in the first premixing module is 80-90°C, and more preferably, the temperature in the first premixing module is set to 85°C.

[0011] The temperature of the first reaction module is 80-85°C, and the reaction time is 4-5h; The temperature of the second reaction module is 130~150℃, and the reaction time is 1-4h; The temperature of the third reaction module is 160-180°C, and the reaction time is 10-14h.

[0012] A decolorant composition is introduced during the decolorization process, wherein the decolorant composition is a mixture of toluene, activated carbon, and diatomaceous earth in a mass ratio of 1:(0.01-0.1):(0.005-0.05).

[0013] The present invention achieves the purpose of continuously preparing DOPO reactive flame retardant with high efficiency, high quality and high selectivity by selecting specific continuous flow reaction conditions. Compared with the prior art, the method of preparing DOPO reactive flame retardant by continuous flow of the present invention has the following beneficial effects: (1) The continuous flow reactor was used to replace the traditional reactor and its equipment, thus simplifying the reaction process; (2) Compared with the traditional batch continuous method, the reactants are fed slowly, and the amount of catalyst used in the reaction process is reduced by 50-70%, which is safer; (3) Compared with the traditional process, different temperature gradients are used to react the synthesis process of CDOP. The reaction temperature of the first gradient is 80-85°C. Since the boiling point of phosphorus trichloride is 77°C, this can greatly improve the reaction efficiency of phosphorus trichloride in the system and minimize the loss of phosphorus trichloride. The reaction temperature of the second gradient is 130-150°C. At this time, the monoester compound in the system is stable. The temperature is further increased to make it fully react and evaporate all the excess phosphorus trichloride in the system, so that the free phosphorus trichloride in the system is as small as possible. The third gradient uses 160-180°C for reaction. At this time, the active sites of zinc and other salt catalysts such as aluminum salts can be increased to fully react with the monoester to generate CDOP. In addition, it is convenient to monitor the content of effective components in the system at any time, which significantly improves the yield and purity of the reaction product. (4) A composite catalyst is used in the reaction. The catalyst does not require special preparation methods. Anhydrous zinc chloride is directly mixed with other salts such as solid salts of anhydrous aluminum chloride in proportion. The composite catalyst can coordinate with the unpaired lone pairs of electrons in the nitrogen atoms in the polymer matrix. Compared with the addition of a single zinc catalyst, this effect can enhance the loading stability of the metal active component and improve the dispersion of the metal active component.

[0014] (5) In the continuous flow reactor of the present invention, the entire process is a continuous process, which avoids other problems encountered in traditional kettle reactions, such as: dust or solvent volatilization generated during manual feeding, inaccurate local temperature control, long feeding time, occupational hazards caused by manual operation and contact with materials during material transfer, etc., realizes automated control, reduces the risk and cost of manual operation, and thus realizes safe, environmentally friendly, healthy and efficient green chemical production.

[0015] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0016] The above contents of the present invention are further described in detail below through specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the process of Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The reagents and raw materials used in the following examples and experimental examples are all commercially available unless otherwise specified.

[0019] Embodiment 1: Step 1, open the continuous flow condenser and set the condensing water temperature to 0°C, fully mix phosphorus trichloride and the composite catalyst to form a suspension, and then pass the continuous flow preheating reactor 1 to make its temperature 70-90°C to prepare a mixed solution A; pass OPP through the continuous flow preheating reactor 2 to make its temperature 70-90°C to prepare a solution B; wherein OPP and PCl3 are mixed in a ratio of 1:1.1, wherein the composite catalyst (anhydrous zinc chloride and anhydrous aluminum chloride, the addition amount is 1.5% of the mass of OPP, and the zinc element in the catalyst accounts for 85%) The mixed solution A and solution B are pumped into the continuous flow mixer through metering pump 1 and metering pump 2 respectively and the temperature is set to 85°C, and then pass through the continuous flow reactor 1 in turn to be heated at 80-85°C for 4 hours to obtain a colorless transparent liquid; then pass through the continuous flow reactor 2 to heat to 130-150°C and keep it for 1 hour, heat to 160-180°C and keep it for 10 hours, and then cool to 50-70°C for hydrolysis, washing, crystallization and other operations.

[0020] During the reaction, the flow rate ratio of metering pump 1: metering pump 2 is 1:1.1. Metering pump 1 and metering pump 2 are turned on, and the tail gas is passed into tail gas treatment device 1 and reaches stability.

[0021] Step 2, toluene: activated carbon: diatomaceous earth = 1: 0.08: 0.03 is mixed into a suspension and then pumped into a continuous flow reactor 3 through a metering pump 3 for decolorization treatment for 1 to 3 hours, and then passed through a continuous flow filter 1 to obtain a colorless and transparent CDOP solution, which is post-treated by conventional hydrolysis, water washing and other means to obtain a DOPO reactive flame retardant.

[0022] Embodiment 2: Step 1, open the continuous flow condenser and set the condensing water temperature to 0°C, fully mix phosphorus trichloride and the composite catalyst to form a suspension, and then pass the continuous flow preheating reactor 1 to make its temperature 70-90°C to prepare a mixed solution A; pass OPP through the continuous flow preheating reactor 2 to make its temperature 70-90°C to prepare a solution B; wherein OPP and PCl3 are mixed in a ratio of 1:1.1, wherein the composite catalyst (anhydrous zinc chloride and anhydrous magnesium chloride, the addition amount is 1.5% of the mass of OPP, and the zinc element in the catalyst accounts for 85%) The mixed solution A and solution B are pumped into the continuous flow mixer through metering pump 1 and metering pump 2 respectively and the temperature is set to 85°C, and then pass through the continuous flow reactor 1 in turn to be heated at 80-85°C for 4 hours to obtain a colorless transparent liquid; then pass through the continuous flow reactor 2 to heat to 130-150°C and keep it for 1 hour, heat to 160-180°C and keep it for 10 hours, and then cool to 50-70°C for hydrolysis, washing, crystallization and other operations.

[0023] During the reaction, the flow rate ratio of metering pump 1: metering pump 2 is 1:1.1. Metering pump 1 and metering pump 2 are turned on, and the tail gas is passed into tail gas treatment device 1 and reaches stability.

[0024] Step 2, toluene: activated carbon: diatomaceous earth = 1: 0.08: 0.03 is mixed into a suspension and then pumped into a continuous flow reactor 3 through a metering pump 3 for decolorization treatment for 1 to 3 hours, and then passed through a continuous flow filter 1 to obtain a colorless and transparent CDOP solution, which is post-treated by conventional hydrolysis, water washing and other means to obtain a DOPO reactive flame retardant.

[0025] Embodiment 3: Step 1, open the continuous flow condenser and set the condensing water temperature to 0°C, fully mix phosphorus trichloride and the composite catalyst to form a suspension, and then pass the continuous flow preheating reactor 1 to make its temperature 70-90°C to prepare a mixed solution A; pass OPP through the continuous flow preheating reactor 2 to make its temperature 70-90°C to prepare a solution B; wherein OPP and PCl3 are mixed in a ratio of 1:1.1, wherein the composite catalyst (anhydrous zinc chloride and anhydrous zinc chloride, the addition amount is 1.5% of the mass of OPP, and the zinc element in the catalyst accounts for 90%) The mixed solution A and solution B are pumped into the continuous flow mixer through metering pump 1 and metering pump 2 respectively and the temperature is set to 85°C, and then pass through the continuous flow reactor 1 in turn to be heated at 80-85°C for 4 hours to obtain a colorless transparent liquid; then pass through the continuous flow reactor 2 to heat to 130-150°C and keep it for 1 hour, heat to 160-180°C and keep it for 10 hours, and then cool to 50-70°C for hydrolysis, washing, crystallization and other operations.

[0026] During the reaction, the flow rate ratio of metering pump 1: metering pump 2 is 1:1.1. Metering pump 1 and metering pump 2 are turned on, and the tail gas is passed into tail gas treatment device 1 and reaches stability.

[0027] Step 2, toluene: activated carbon: diatomaceous earth = 1: 0.08: 0.03 is mixed into a suspension and then pumped into a continuous flow reactor 3 through a metering pump 3 for decolorization treatment for 1 to 3 hours, and then passed through a continuous flow filter 1 to obtain a colorless and transparent CDOP solution, which is post-treated by conventional hydrolysis, water washing and other means to obtain a DOPO reactive flame retardant.

[0028] Embodiment 4: Step 1, open the continuous flow condenser and set the condensing water temperature to 0°C, fully mix phosphorus trichloride and the composite catalyst to form a suspension, and then pass the continuous flow preheating reactor 1 to make its temperature 70-90°C to prepare a mixed solution A; pass OPP through the continuous flow preheating reactor 2 to make its temperature 70-90°C to prepare a solution B; wherein OPP and PCl3 are mixed in a ratio of 1:1.1, wherein the composite catalyst (anhydrous zinc chloride and anhydrous nickel chloride, the addition amount is 1.5% of the mass of OPP, and the zinc element in the catalyst accounts for 70%) The mixed solution A and solution B are pumped into the continuous flow mixer through metering pump 1 and metering pump 2 respectively and the temperature is set to 85°C, and then pass through the continuous flow reactor 1 in turn to be heated at 80-85°C for 4 hours to obtain a colorless transparent liquid; then pass through the continuous flow reactor 2 to heat to 130-150°C and keep it for 1 hour, heat to 160-180°C and keep it for 10 hours, and then cool to 50-70°C for hydrolysis, washing, crystallization and other operations.

[0029] During the reaction, the flow rate ratio of metering pump 1: metering pump 2 is 1:1.1. Metering pump 1 and metering pump 2 are turned on, and the tail gas is passed into tail gas treatment device 1 and reaches stability.

[0030] Step 2, toluene: activated carbon: diatomaceous earth = 1: 0.08: 0.03 is mixed into a suspension and then pumped into a continuous flow reactor 3 through a metering pump 3 for decolorization treatment for 1 to 3 hours, and then passed through a continuous flow filter 1 to obtain a colorless and transparent CDOP solution, which is post-treated by conventional hydrolysis, water washing and other means to obtain a DOPO reactive flame retardant.

[0031] Embodiment 5: Step 1, open the continuous flow condenser and set the condensing water temperature to 0°C, fully mix phosphorus trichloride and the composite catalyst to form a suspension, and then pass the continuous flow preheating reactor 1 to make its temperature 70-90°C to prepare a mixed solution A; pass OPP through the continuous flow preheating reactor 2 to make its temperature 70-90°C to prepare a solution B; wherein OPP and PCl3 are mixed in a ratio of 1:1.1, wherein the composite catalyst (anhydrous zinc chloride and anhydrous aluminum chloride, the addition amount is 1.5% of the mass of OPP, and the zinc element in the catalyst accounts for 95%) The mixed solution A and solution B are pumped into the continuous flow mixer through metering pump 1 and metering pump 2 respectively and the temperature is set to 85°C, and then pass through the continuous flow reactor 1 in turn to be heated at 80-85°C for 4 hours to obtain a colorless transparent liquid; then pass through the continuous flow reactor 2 to heat to 130-150°C and keep it for 1 hour, heat to 160-180°C and keep it for 10 hours, and then cool to 50-70°C for hydrolysis, washing, crystallization and other operations.

[0032] During the reaction, the flow rate ratio of metering pump 1: metering pump 2 is 1:1.1. Metering pump 1 and metering pump 2 are turned on, and the tail gas is passed into tail gas treatment device 1 and reaches stability.

[0033] Step 2, toluene: activated carbon: diatomaceous earth = 1: 0.08: 0.03 is mixed into a suspension and then pumped into a continuous flow reactor 3 through a metering pump 3 for decolorization treatment for 1 to 3 hours, and then passed through a continuous flow filter 1 to obtain a colorless and transparent CDOP solution, which is post-treated by conventional hydrolysis, water washing and other means to obtain a DOPO reactive flame retardant.

[0034] The reaction conditions and yields of the above five groups of examples were compared with the purity and yield of DOPO prepared by traditional batch reaction. The results are shown in Table 1.

[0035] Control group 1 The method and steps are the same as in Example 1, except that no catalyst is added.

[0036] Control group 2 The method and steps are the same as those in Example 1, except that only zinc chloride is added as the catalyst.

[0037] Control group 2 The method and steps are the same as those in Example 1, except that only aluminum chloride is added as the catalyst.

[0038] Table 1 Purity and yield of DOPO generated during continuous flow reaction as a function of zinc addition

[0039] From the data in Table 1 above, it can be seen that the DOPO prepared by the DOPO continuous flow reactor is higher than that prepared by the traditional reactor (control group 1); the quality and yield of DOPO produced by the reaction catalyzed by a single catalyst are lower than those using a composite catalyst; appropriately increasing the flow rate of pump 2 has no effect on its quality, but will reduce its reaction yield. Accurately controlling the proportion of zinc in the composite catalyst is conducive to further improving the purity of the product DOPO.

[0040] It can be seen from the above embodiments and experimental examples that the present invention realizes the continuous flow preparation of DOPO reactive flame retardant with high efficiency and high quality, has the advantages of simple process and low risk, and has good application prospects.

Claims

1. A method for preparing a DOPO reactive flame retardant by continuous flow, characterized in that: S1, mixing the composite catalyst with the phosphorus trichloride solution to form a suspension, and then transporting it to a continuous flow preheating reactor for preheating, and then pumping the preheated mixture and the preheated OPP into the first premixing module in the microchannel reactor respectively for sufficient premixing; S2, the premixed materials are then pumped into the first reaction module, the second reaction module, and the third reaction module in sequence for programmed temperature control reaction to obtain a mixed solution; S3. Decolorize, filter, hydrolyze and wash the outflowing mixed solution to obtain DOPO.

2. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 1, characterized in that: The molar ratio of raw material OPP and raw material PCl3 is 1: (1.0~1.5); The composite catalyst is a composite catalyst formed by anhydrous zinc chloride and any one or more of anhydrous aluminum chloride, anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous nickel chloride, anhydrous molybdenum chloride and anhydrous manganese chloride.

3. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 2, characterized in that: The mass ratio of the raw material OPP to the composite catalyst is 1:(0.005-0.15); the molar proportion of zinc element in the catalyst in the composite catalyst is 60-95%.

4. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 1, characterized in that: The composite catalyst and phosphorus trichloride solution are preheated to 70-90°C in a continuous flow preheating reactor; Preheat OPP to 70~90℃.

5. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 1, characterized in that: The temperature in the first premixing module is 80~90℃.

6. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 1, characterized in that: The temperature of the first reaction module is 80-85°C, and the reaction time is 4-5h; The temperature of the second reaction module is 130~150℃, and the reaction time is 1-4h; The temperature of the third reaction module is 160-180°C, and the reaction time is 10-14h.

7. The method for preparing DOPO reactive flame retardant by continuous flow according to claim 1, characterized in that: A decolorant composition is introduced during the decolorization process, wherein the decolorant composition is a mixture of toluene, activated carbon, and diatomaceous earth in a mass ratio of 1:(0.01-0.1):(0.005-0.05).

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