Synthesis method of brominated polystyrene with high thermal stability

Abstract

The invention relates to a synthetic method of brominated polystyrene with high thermal stability. The synthetic method comprises the following steps: S01, dissolving polystyrene in a halogenated hydrocarbon solvent in a reaction bottle to obtain a polystyrene solution; s02, adding aluminum chloride and bromine into another reaction bottle; s03, introducing hydrogen bromide gas into the reaction bottle in S02, and starting stirring to react at room temperature; s04, after the reaction in the step S03 is finished, reducing the temperature of the polystyrene solution in the step S01 to the reaction temperature, starting stirring, adding a free radical inhibitor, and dropwise adding the bromine and catalyst mixed solution obtained by the reaction in the step S03 into the polystyrene solution; s05, after dropwise adding is finished, adjusting the temperature to the heat preservation temperature, and carrying out heat preservation reaction for a period of time; and S06, after the heat preservation is finished, carrying out post-treatment to obtain the brominated polystyrene. According to the synthetic method of brominated polystyrene, the halogenation phenomenon of a main chain can be inhibited, the use of a catalyst is reduced, and the thermal stability of brominated polystyrene is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis technology, and particularly relates to a method for synthesizing brominated polystyrene with high thermal stability. Background Art

[0002] In industrial production, brominated polystyrene (BPS) is usually obtained by directly brominating polystyrene (PS). However, while the brominating agent undergoes electrophilic substitution on the benzene ring of polystyrene, a small amount of free radical substitution also occurs on the main chain. The halogenation on the main chain not only has an adverse effect on the color of the product, but also reduces the thermal stability of the product.

[0003] Current research shows that the thermal stability of brominated polystyrene is related to the content of α-alkyl bromide in brominated polystyrene. The higher the content, the lower the thermal stability of brominated polystyrene. In addition, since the bond energy of aliphatic carbon-halogen bonds is relatively low, they will break when heated to about 200°C, causing brominated polystyrene to decompose in the early or middle stages of the material's processing temperature, releasing hydrogen halide gas, which damages the original performance of the material and corrodes the processing equipment. During the processing of the material, even a small amount of main chain halogenation will cause severe discoloration of the material, which will greatly limit the application range of brominated polystyrene. At the same time, the catalyst will also bring a small amount of unstable small molecular bromine and chlorine compound impurities to the product. The thermal decomposition temperature of these trace impurities is low, which will also lead to a decrease in the thermal stability of the final product. Summary of the invention

[0004] The purpose of the present invention is to provide a method for synthesizing brominated polystyrene with high thermal stability, which can inhibit the halogenation of the main chain, reduce the use of catalysts, and improve the thermal stability of brominated polystyrene.

[0005] The technical solution adopted by the present invention to solve the above problem is: a method for synthesizing brominated polystyrene with high thermal stability, comprising the following steps: S01, dissolving polystyrene in a halogenated hydrocarbon solvent in a reaction bottle to obtain a polystyrene solution; S02, adding aluminum chloride and bromine into another reaction bottle; S03, introduce hydrogen bromide gas into the S02 reaction bottle, start stirring to react at room temperature, and introduce the tail gas into the tail gas system; After the reaction of S04 and S03 is completed, the temperature of the S01 polystyrene solution is lowered to the reaction temperature, stirring is started, a free radical inhibitor is added, and the bromine and catalyst mixture obtained by the reaction in S03 is dripped into the polystyrene solution; S05, after the dropwise addition is completed, the temperature is adjusted to a holding temperature and the reaction is kept for a period of time; S06, after the insulation is completed, keep stirring, add water dropwise for quenching, continue stirring after the addition is completed, let stand for stratification, then wash the organic layer with alkali and water until neutral, and let stand for stratification; S07, adding the organic layer washed to neutrality dropwise into hot water, removing the solvent, filtering to obtain a crude product, and drying at high temperature to obtain the product.

[0006] Preferably, the molecular weight of the polystyrene in S01 is 3000-150000, the water content of the halogenated hydrocarbon solvent is less than 100 ppm, the halogenated hydrocarbon solvent is one or more of dichloromethane, 1,2-dichloroethane, chloroform, and bromochloromethane, and the content of polystyrene in the halogenated hydrocarbon solvent is 5-10%.

[0007] Preferably, the amount of aluminum chloride in S02 is 1-5% of the mass of polystyrene, and the molar amount of bromine is 2-3 times the molar amount of polystyrene benzene ring.

[0008] More preferably, the molar amount of bromine is 2.7 times the molar amount of polystyrene benzene ring.

[0009] Preferably, the source of hydrogen bromide gas in S03 is a hydrogen bromide gas cylinder or brominated polystyrene reaction tail gas, and the tail gas system is sealed with a halogenated hydrocarbon solvent at the first level and water or alkaline solution absorption liquid at the second level.

[0010] The reaction equation in S03 is AlCl3 + 3HBr→AlBr3 + 3HCl, where bromine is the solvent, and hydrogen bromide gas and aluminum chloride are the reaction raw materials.

[0011] Preferably, the reaction temperature in S04 is -10 to 20° C., the free radical inhibitor is butylated hydroxytoluene BHT or 2,2,6,6-tetramethylpiperidine-nitrogen-oxide TEMPO, the amount of the free radical inhibitor is 0.1 to 0.5% of the mass of polystyrene, and the dripping time of the bromine and catalyst mixture is 0.5 to 2 h.

[0012] Preferably, the insulation temperature in S05 is -10~20°C, and the insulation time is 0.5~2h.

[0013] Preferably, the mass of water used for quenching, alkali washing and water washing in S06 is 0.5 to 2 times the mass of the halogenated hydrocarbon solvent, and the alkali washing solution used in the alkali washing is a 1% sodium hydroxide aqueous solution.

[0014] Preferably, the hot water temperature in S07 is 70-95° C., the drying temperature is 130-150° C., and the drying time is 3-5 hours.

[0015] Compared with the prior art, the advantages of the present invention are: (1) The activity of aluminum bromide is higher than that of aluminum chloride. The polystyrene bromination reaction of the present invention can achieve the same catalytic effect as that of aluminum chloride with a higher feed amount by using a smaller feed amount of aluminum bromide, thereby reducing the feed amount of the catalyst, thereby reducing the unstable small molecular bromine and chlorine compound impurities brought to the product by the catalyst, and improving the thermal stability of the product.

[0016] (2) The present invention makes full use of the hydrogen bromide tail gas generated in the process of bromination of polystyrene with bromine to react with aluminum chloride to prepare aluminum bromide with higher activity online. No new raw materials are introduced in the process of online preparation of aluminum bromide, which is green and environmentally friendly. In addition, the cost of aluminum bromide is much higher than that of aluminum chloride. Compared with directly using aluminum bromide, the present invention uses aluminum chloride to prepare aluminum bromide online, which is low-cost.

[0017] (3) The online aluminum bromide preparation system of aluminum chloride in the present invention is relatively closed, which prevents aluminum bromide powder from releasing a large amount of white smoke and losing activity when it contacts the air, thereby reducing the waste of part of the catalyst caused by the deactivation of aluminum bromide and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a synthetic flow chart of the brominated polystyrene with high thermal stability according to the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below with reference to the accompanying drawings.

[0020] like Figure 1 As shown, the synthesis flow chart of brominated polystyrene with high thermal stability of the present invention.

[0021] Example 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a moisture content of less than 100ppm were added to a 1000mL four-necked flask, stirred to dissolve, the temperature of the solution in the reaction flask was lowered to 0°C, 1g of aluminum chloride and 0.06g of BHT were added, the 1000mL four-necked flask was also connected to a tail gas pipe via a connecting tube, and the tail gas pipe was connected to the bottom of a 100mL four-necked flask containing 0.6g of aluminum chloride and 85g of bromine, and hydrogen bromide gas entered the 100mL four-necked flask through the tail gas pipe, and the other side opening of the 100mL four-necked flask was connected to the tail gas system as a tail gas opening, and the 100mL four-necked flask was opened for stirring; 85g of bromine was added dropwise to the 1000mL four-necked flask using a peristaltic pump, the dropping time was controlled to be 1h, the temperature was controlled to be 0°C after the dropping was completed, the reaction was kept warm for 1h, the connecting tube to the 100mL four-necked flask was disconnected, 200g of deionized water was added dropwise, and the stratification was allowed to stand after stirring for 0.5h.

[0022] Post-treatment method: The organic layer separated above was stirred and washed with 200g of 1% sodium hydroxide aqueous solution for 0.5h, and then allowed to stand for separation. The organic layer was stirred and washed with 200g of water for 0.5h, and then allowed to stand for separation. The organic layer was dropped into 85℃ hot water for flash evaporation to remove dichloroethane, and a mixture of product and water was obtained. After cooling, the wet product was filtered and dried in a blast drying oven at 140℃ for 4h to obtain 61.8g of brominated polystyrene product, the bromine content of the product was 66.9%, and the 1% TGA was 341℃. Example 1

[0023] Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0℃, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting tube, and the tail gas pipe is connected to the bottom of a 100mL four-necked bottle containing 0.6g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side port of the 100mL four-necked flask is connected to the tail gas system as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in the example is supplemented to 85g (bromine will be blown out during the process of passing the tail gas of the bromination reaction and then passing the gas after the reaction of the 100mL four-necked flask out, and the mass of bromine will be reduced); then a peristaltic pump is used to drop the reactants in the 100mL four-necked flask in the example (including bromine and catalyst mixed solution) into the 1000mL four-necked flask, and the dropping time is controlled to be 1h. After the dropping is completed, the temperature is controlled to be 0℃, and the reaction is kept warm for 1h. The connecting tube with the 100mL four-necked flask is disconnected, 200g of deionized water is added, and the mixture is allowed to stand for stratification after stirring for 0.5h. Then, the post-treatment was carried out in the same manner as in the example to obtain 62.3 g of brominated polystyrene product, the bromine content of the product was 67.1%, and the 1% TGA was 349°C. Example 2

[0024] Add 20g of polystyrene with a molecular weight of 4000 and 380g of ethylene dichloride with a water content of 200ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0°C, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and the tail gas pipe is connected to the bottom of the 100mL four-necked flask containing 1g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side of the 100mL four-necked flask is connected to the tail gas system as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in Example 1 is supplemented to 85g, and the reactants in the 100mL four-necked flask (including bromine and catalyst mixed solution) are added dropwise to the 1000mL four-necked flask by a peristaltic pump, and the dropping time is controlled to be 1h. After the dropping is completed, the temperature is controlled to be 0℃, and the reaction is kept warm for 1h, and the connecting tube with the 100mL four-necked flask is disconnected, 200g deionized water is added dropwise, and the mixture is stirred for 0.5h and then allowed to stand for stratification. Then the post-treatment is carried out in the same way as in the example. 59.3 g of brominated polystyrene product was obtained. The bromine content of the product was 64.2% and the 1% TGA was 332°C. Example 3

[0025] Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0℃, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and the tail gas pipe is connected to the bottom of the 100mL four-necked flask containing 0.6g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side of the 100mL four-necked flask is connected to the tail gas system as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in Example 2 is supplemented to 85g, and the reactants in the 100mL four-necked flask (including bromine and catalyst mixed solution) are added dropwise to the 1000mL four-necked flask by a peristaltic pump, and the dropping time is controlled to be 1h. After the dropping is completed, the temperature is controlled to be 0℃, and the reaction is kept warm for 1h, and the connecting tube with the 100mL four-necked flask is disconnected, 200g deionized water is added dropwise, and the mixture is stirred for 0.5h and then allowed to stand for stratification. Then the post-treatment is carried out in the same way as in the example. 62.6 g of brominated polystyrene product was obtained. The bromine content of the product was 67.4% and the 1% TGA was 345°C. Example 4

[0026] Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 20°C, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and the tail gas pipe is connected to the bottom of the 100mL four-necked flask containing 0.6g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side of the 100mL four-necked flask is connected to the tail gas system as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in Example 3 is supplemented to 85g, and the reactants in the 100mL four-necked flask (including bromine and catalyst mixed solution) are added dropwise to the 1000mL four-necked flask by a peristaltic pump, and the dropping time is controlled to be 1h. After the dropping is completed, the temperature is controlled to be 20°C, and the reaction is kept warm for 1h, and the connecting tube with the 100mL four-necked flask is disconnected, 200g deionized water is added dropwise, and the mixture is stirred for 0.5h and then allowed to stand for stratification. Then the post-treatment is carried out in the same way as in the example. 62.0 g of brominated polystyrene product was obtained. The bromine content of the product was 66.5% and the 1% TGA was 332°C. Example 5

[0027] Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0℃, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and the tail gas pipe is connected to the bottom of the 100mL four-necked flask containing 0.6g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side of the 100mL four-necked flask is connected to the tail gas absorption system as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in Example 4 is supplemented to 85g, and the reactants in the 100mL four-necked flask (including bromine and catalyst mixed solution) are added dropwise to the 1000mL four-necked flask by a peristaltic pump, and the dropping time is controlled to be 0.5h. After the dropping is completed, the temperature is controlled to be 0℃, and the reaction is kept warm for 0.5h. The connecting tube with the 100mL four-necked flask is disconnected, 200g deionized water is added dropwise, and the mixture is allowed to stand for stratification after stirring for 0.5h. Then the post-treatment is carried out in the same way as in the example. 61.8 g of brominated polystyrene product was obtained. The bromine content of the product was 66.5% and the 1% TGA was 341°C. Example 6

[0028] Add 20g of polystyrene with a molecular weight of 11000 and 380g of ethylene dichloride with a water content of less than 100ppm into a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0℃, and add 0.06g BHT, the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and the tail gas pipe is connected to the bottom of the 100mL four-necked flask containing 0.6g aluminum chloride and 85g bromine. The hydrogen bromide gas enters the 100mL four-necked flask through the tail gas pipe, and the other side of the 100mL four-necked flask is connected to the tail gas absorption liquid as the tail gas port. The 100mL four-necked flask is opened for stirring and reaction, and then the bromine in the 100mL four-necked flask in Example 5 is supplemented to 85g, and the reactants in the 100mL four-necked flask (including bromine and catalyst mixed solution) are added dropwise to the 1000mL four-necked flask by a peristaltic pump, and the dropping time is controlled to be 1h. After the dropping is completed, the temperature is controlled to be 0℃, and the reaction is kept warm for 1h, and the connecting tube with the 100mL four-necked flask is disconnected, 200g deionized water is added dropwise, and the mixture is stirred for 0.5h and then allowed to stand for stratification. Then the post-treatment is carried out in the same way as in the example. 62.6 g of brominated polystyrene product was obtained. The bromine content of the product was 67.1% and the 1% TGA was 357°C.

[0029] Comparative Example 1 Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm to a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0°C, add 0.6g of aluminum bromide and 0.06g of BHT, and the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and its tail gas pipe is connected to the tail gas absorption liquid. Use a peristaltic pump to drop 85g of bromine into the 1000mL four-necked flask, control the drop time to 1h, control the temperature to 0°C after the drop addition, keep warm for 1h, disconnect the connecting tube with the 100mL four-necked flask, drop 200g of deionized water, stir for 0.5h and then stand for stratification. Then perform post-treatment in the same way as in the example. 57.5g of brominated polystyrene product is obtained, the bromine content of the product is 63.8%, and the 1% TGA is 326°C.

[0030] Comparative Example 2 Add 20g of polystyrene with a molecular weight of 4000 and 380g of dichloroethane with a water content of less than 100ppm to a 1000mL four-necked flask, stir to dissolve the polystyrene, lower the temperature of the solution in the reaction flask to 0°C, add 1.2g of aluminum bromide and 0.06g of BHT, and the 1000mL four-necked flask is also connected to the tail gas pipe through a connecting pipe, and its tail gas pipe is connected to the tail gas absorption liquid. Use a peristaltic pump to drop 85g of bromine into the 1000mL four-necked flask, control the drop time to 1h, control the temperature to 0°C after the drop addition, keep warm for 1h, disconnect the connecting tube with the 100mL four-necked flask, drop 200g of deionized water, stir for 0.5h and then stand for stratification. Then perform post-treatment in the same way as in the example. Obtain 62.0g of brominated polystyrene product, the bromine content of the product is 66.9%, and 1% TGA is 345°C.

[0031] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A method for synthesizing brominated polystyrene with high thermal stability, characterized in that: The following steps are involved: S01, dissolving polystyrene in a halogenated hydrocarbon solvent in a reaction bottle to obtain a polystyrene solution; S02, adding aluminum chloride and bromine into another reaction bottle; S03, introduce hydrogen bromide gas into the S02 reaction bottle, start stirring to react at room temperature, and introduce the tail gas into the tail gas system; After the reaction of S04 and S03 is completed, the temperature of the S01 polystyrene solution is lowered to the reaction temperature, stirring is started, a free radical inhibitor is added, and the bromine and catalyst mixture obtained by the reaction in S03 is dripped into the polystyrene solution; S05, after the dropwise addition is completed, the temperature is adjusted to a holding temperature and the reaction is kept for a period of time; S06, after the insulation is completed, keep stirring, add water dropwise for quenching, continue stirring after the addition is completed, let stand for stratification, then wash the organic layer with alkali and water until neutral, and let stand for stratification; S07, adding the organic layer washed to neutrality dropwise into hot water, removing the solvent, filtering to obtain a crude product, and drying at high temperature to obtain the product.

2. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The molecular weight of the polystyrene in S01 is 3000-150000, the water content of the halogenated hydrocarbon solvent is less than 100 ppm, the halogenated hydrocarbon solvent is one or more of dichloromethane, 1,2-dichloroethane, chloroform, and bromochloromethane, and the content of polystyrene in the halogenated hydrocarbon solvent is 5-10%.

3. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The amount of aluminum chloride added in S02 is 1-5% of the mass of polystyrene, and the molar amount of bromine is 2-3 times the molar amount of polystyrene benzene ring.

4. The method for synthesizing brominated polystyrene with high thermal stability according to claim 3, characterized in that: The molar amount of bromine is 2.7 times the molar amount of polystyrene benzene ring.

5. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The source of the hydrogen bromide gas in S03 is a hydrogen bromide gas cylinder or tail gas from the brominated polystyrene reaction.

6. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The reaction temperature in S04 is -10 to 20°C, the free radical inhibitor is butylated hydroxytoluene BHT or 2,2,6,6-tetramethylpiperidine-nitrogen-oxide TEMPO, the amount of the free radical inhibitor is 0.1 to 0.5% of the mass of polystyrene, and the dripping time of the bromine and catalyst mixture is 0.5 to 2 hours.

7. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The insulation temperature in S05 is -10~20°C, and the insulation time is 0.5~2h.

8. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The mass of water used for quenching, alkali washing and water washing in S06 is 0.5 to 2 times the mass of the halogenated hydrocarbon solvent, and the alkali washing liquid used in the alkali washing is a 1% sodium hydroxide aqueous solution.

9. The method for synthesizing brominated polystyrene with high thermal stability according to claim 1, characterized in that: The hot water temperature in S07 is 70-95°C, the drying temperature is 130-150°C, and the drying time is 3-5h.

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