阅读说明：本技术 一种合成溴化聚苯乙烯的方法 (Method for synthesizing brominated polystyrene ) 是由 汪静莉 潘兵波 谢滋东 袁东华 耿飞 陈健 夏震宇 于 2019-10-30 设计创作，主要内容包括：本发明涉及一种合成溴化聚苯乙烯的方法,在氮气保护条件下,聚苯乙烯的二氯乙烷溶液与一定量的催化剂、自由基抑制剂混合均匀,再滴加溴素,控制其滴加时间、滴完后温度,后进行保温反应,保温反应结束后进行后处理得到粗品,粗品干燥至恒重得到产品溴化聚苯乙烯。本发明的合成溴化聚苯乙烯的方法具有工艺简单,易控制,所合成的溴化聚苯乙烯具有高稳定性、高溴含量、低色度,分子量分布窄。(The invention relates to a method for synthesizing brominated polystyrene, under the protection of nitrogen, dichloroethane solution of polystyrene is uniformly mixed with a certain amount of catalyst and free radical inhibitor, then bromine is dripped, the dripping time and the temperature after dripping are controlled, then heat preservation reaction is carried out, after the heat preservation reaction is finished, post-treatment is carried out to obtain a crude product, and the crude product is dried to constant weight to obtain the brominated polystyrene product. The method for synthesizing brominated polystyrene has the advantages of simple process and easy control, and the synthesized brominated polystyrene has high stability, high bromine content, low chroma and narrow molecular weight distribution.)

1. A method for synthesizing brominated polystyrene is characterized in that: the method comprises the following steps:

(1) adding a dichloroethane solution of polystyrene into the four-neck flask, and replacing air in the four-neck flask with nitrogen;

(2) adding a catalyst into the four-neck flask, cooling to-5 ~ 20 ℃, and adding a free radical inhibitor;

(3) dropwise adding bromine for 0.5-2 hours, adjusting the temperature to 0 ~ 20 ℃ after the dropwise adding of the bromine is finished, and keeping the temperature for 0.5 ~ 3 hours;

(4) after the heat preservation is finished, adding a small amount of sodium sulfite solution to destroy residual bromine, then carrying out alkali washing and water washing on an organic layer to neutrality, dropwise adding the organic layer into boiling water to remove a solvent to obtain a crude product, and drying the crude product to constant weight to obtain a product;

wherein, the moisture of the dichloroethane solution of the polystyrene in the step (1) is less than 200ppm, and dry nitrogen is introduced for protection in the steps (2) and (3).

2. The method of synthesizing brominated polystyrene of claim 1, wherein: the content of polystyrene in the dichloroethane solution of polystyrene in step (1) is 5%.

3. The method for synthesizing brominated polystyrene according to claim 1, wherein in step (2), the catalyst is one or two of aluminum trihalide and antimony trihalide, and the amount of the catalyst added is 1% ~ 10% by weight of polystyrene.

4. The method of synthesizing brominated polystyrene of claim 3, wherein: the aluminum trihalide is aluminum trichloride or aluminum tribromide, and the antimony trihalide is antimony trichloride.

5. The method of synthesizing brominated polystyrene of claim 1, wherein: in the step (2), the free radical inhibitor is dibutyl hydroxy toluene or 2,2,6, 6-tetramethyl piperidine-nitrogen-oxide.

6. The method of synthesizing brominated polystyrene of claim 1, wherein: the temperature in step (2) is 0 ℃.

7. The method of synthesizing brominated polystyrene of claim 1, wherein: the step (3) is specifically as follows: the bromine dropping time is 1 hour, the heat preservation temperature is 10 ℃, and the heat preservation time is 2 hours.

8. The method of synthesizing brominated polystyrene of claim 1 or 7, wherein: the addition amount of the bromine is 4.3 times of the mass of the polystyrene.

Technical Field

The invention belongs to the technical field of preparation of macromolecular brominated flame retardants, and particularly relates to a method for synthesizing brominated polystyrene.

Background

The research and application of brominated polystyrene in foreign countries are early, the synthesis process is mature, and the industrial production of the brominated polystyrene is realized first in the 80 th century by Ferro company and Great Lake company in the United states. Great Lake company uses styrene as raw material, bromizes the styrene to obtain brominated styrene monomer, and then polymerizes the monomer to obtain poly-brominated styrene (PBS), and U.S. Pat. No. 5369202 provides a method for synthesizing poly-brominated styrene product PDBS-80. The synthesis route of Great Lake company is to bromize and then polymerize, thus avoiding the halogenation reaction of brominating agent on the main chain, so that the prepared poly brominated styrene has excellent thermal stability, basically does not release corrosive hydrogen halide gas when being used as a flame retardant and being melted and blended with a flame-retardant base material, and does not cause damage to operators and operating equipment; the polybrominated styrene product has excellent color and high whiteness, and as an additive, the lighter the color is, the wider the application range is; it is also possible to improve the compatibility of the copolymer with certain resins, to increase the flowability, and to prevent foaming of the material by first preparing a brominated styrene monomer and then copolymerizing it with a monomer having other functional groups.

However, the above synthetic routes have the disadvantages that: (1) the synthesis route is too long, the synthesis process is complex, the requirement on production equipment is high, the product cost is increased, the production period is long, and the market competitiveness is reduced; (2) the tribromostyrene monomer has high reaction activity, so that the polymerization reaction is difficult to control, and dibromostyrene is generally adopted for polymerization, so that the bromine content of a polymerized product is not high and is about 60 percent, more bromine needs to be added to achieve the same flame-retardant effect, the original performance of a flame-retardant material is greatly influenced, and the flame-retardant cost is increased.

In addition, in the existing synthesis method of brominated polystyrene, polystyrene and bromine are adopted to react, except the bromine substitution reaction on a benzene ring, the reaction can also be subjected to substitution reaction with active hydrogen on a tertiary carbon atom on a main chain, and due to the low bond energy, the side product is easy to chain scission under the environment with slightly high temperature, so that the molecular weight of the brominated polystyrene is reduced, and the distribution is widened.

Disclosure of Invention

The invention aims to provide a method for synthesizing brominated polystyrene, which has the advantages of simple process, low cost and easy control, and the synthesized brominated polystyrene has high stability, high bromine content, low chroma and narrow molecular weight distribution.

The technical scheme adopted by the invention for solving the problems is as follows: a method of synthesizing brominated polystyrene, comprising the steps of:

(1) a dichloroethane solution of polystyrene was added to the four-necked flask, and the air in the four-necked flask was replaced with nitrogen.

(2) And adding a catalyst into the four-neck flask, cooling to-5-20 ℃, and adding a free radical inhibitor.

(3) Dropwise adding bromine for 0.5-2 hours, adjusting the temperature to 0 ~ 20 ℃ after the dropwise adding of the bromine is finished, and keeping the temperature for 0.5 ~ 3 hours.

(4) And after the heat preservation is finished, adding a small amount of sodium sulfite solution to destroy residual bromine, then carrying out alkali washing and water washing on the organic layer to neutrality, dropwise adding the organic layer into boiling water to remove the solvent to obtain a crude product, and drying the crude product to constant weight to obtain the product.

Wherein, the moisture of the dichloroethane solution of the polystyrene in the step (1) is less than 200ppm, and dry nitrogen is introduced for protection in the steps (2) and (3).

Preferably, the content of polystyrene in the dichloroethane solution of polystyrene in step (1) is 5%.

Preferably, in the step (2), the catalyst is one or two of aluminum trihalide and antimony trihalide, and the addition amount of the catalyst is 1% ~ 10% of the weight of the polystyrene.

More preferably, the aluminum trihalide is aluminum trichloride or aluminum tribromide, and the antimony trihalide is antimony trichloride.

Preferably, the radical inhibitor in step (2) is dibutyl hydroxy toluene (BHT) or 2,2,6, 6-tetramethyl piperidine-nitrogen-oxide (TEMPO).

Preferably, the temperature in step (2) is 0 ℃.

Preferably, the step (3) is specifically: the bromine dropping time is 1 hour, the heat preservation temperature is 10 ℃, and the heat preservation time is 2 hours.

Preferably, the addition amount of the bromine is 4.3 times of the mass of the polystyrene.

Compared with the prior art, the invention has the advantages that:

(1) the method has simple process, easy control and suitability for large-scale industrial application, and the synthesized brominated polystyrene has high stability, high bromine content, low chroma and narrow molecular weight distribution.

(2) The invention adds the free radical inhibitor to inhibit bromine free radical substitution reaction on an alkyl chain, adopts a dry nitrogen displacement and protection system, strictly controls the moisture of the system, obtains products without chain breakage and low chromatic value, can obtain products with expected color when being applied to plastics, and does not generate black impurities due to the decomposition of low molecular compounds in the processing process.

(3) Compared with the process for preparing the brominated polystyrene by the bromine chloride method, the brominated polystyrene prepared by the full bromine method does not contain chloride ions, so that the thermal stability of the product is improved; the brominated polystyrene product with higher bromine content can be obtained by increasing the proportion of bromine.

Detailed Description

The present invention will be described in further detail with reference to examples.