阅读说明：本技术 聚苯硫醚及其合成方法 (Polyphenylene sulfide and synthetic method thereof ) 是由 李勇 梁平 于 2020-06-16 设计创作，主要内容包括：本发明涉及聚苯硫醚的合成方法,属于高分子材料树脂的合成技术领域。本发明解决的技术问题是提供一种聚苯硫醚的合成方法。该方法包括：1)多水硫化钠、LiCl和NMP混合,进行共沸脱水；2)脱水后物料与氯苯混合,升温到250～270℃反应1.5～3小时；3)降温至220～235℃,加入对二氯苯混合反应2～3小时,然后升温至250～270℃,反应4～5小时,得到反应后物料；4)反应后物料冷却,过滤,固体洗涤,干燥,得到聚苯硫醚。本发明首次采用氯苯与硫化钠反应生成苯硫酚类单官能团物质,再加入对二氯苯进入反应聚合,其方法操作简单,成本低,聚合时间短,得到的聚苯硫醚中的活性端基数量少,提高了聚苯硫醚的稳定性,便于后期加工。(The invention relates to a synthetic method of polyphenylene sulfide, belonging to the technical field of synthesis of high polymer material resin. The invention aims to provide a synthetic method of polyphenylene sulfide. The method comprises the following steps: 1) mixing the sodium sulfide, LiCl and NMP for azeotropic dehydration; 2) mixing the dehydrated material with chlorobenzene, heating to 250-270 ℃ and reacting for 1.5-3 hours; 3) cooling to 220-235 ℃, adding p-dichlorobenzene, mixing, reacting for 2-3 hours, heating to 250-270 ℃, and reacting for 4-5 hours to obtain a reacted material; 4) and cooling the reacted materials, filtering, washing the solid, and drying to obtain the polyphenylene sulfide. The invention adopts chlorobenzene to react with sodium sulfide for the first time to generate thiophenol monofunctional group substances, and then adds p-dichlorobenzene to carry out reaction polymerization.)

1. The synthetic method of the polyphenylene sulfide is characterized by comprising the following steps:

1) dehydrating raw material sodium sulfide: mixing the sodium sulfide, LiCl and NMP, and performing azeotropic dehydration to obtain a dehydrated material;

2) pretreatment: mixing the dehydrated material with chlorobenzene, heating to 250-270 ℃, and reacting for 1.5-3 hours to obtain a pretreated material;

3) polymerization: cooling the pretreated material to 220-235 ℃, mixing with p-dichlorobenzene, reacting for 2-3 hours, then heating to 250-270 ℃, and reacting for 4-5 hours to obtain a reacted material;

4) and (3) post-treatment: and cooling the reacted materials, filtering, washing the solid, and drying to obtain the polyphenylene sulfide.

2. The method for synthesizing polyphenylene sulfide according to claim 1, characterized in that: in the step 1), the molar ratio of the sodium sulfide monohydrate to the NMP to the LiCl is 1: 4-5: 0.3-0.6.

3. The method for synthesizing polyphenylene sulfide according to claim 1, characterized in that: in the step 1), azeotropic dehydration is carried out by heating to 195-210 ℃ under a protective atmosphere for evaporation.

4. The method for synthesizing polyphenylene sulfide according to claim 3, characterized in that: the protective atmosphere is inert atmosphere or nitrogen.

5. The method for synthesizing polyphenylene sulfide according to claim 4, characterized in that: the inert atmosphere is helium, neon, argon, krypton or xenon.

6. The method for synthesizing polyphenylene sulfide according to claim 1, characterized in that: in the step 2), the molar ratio of sodium sulfide to chlorobenzene in the dehydrated material is 1: 0.05-0.1.

7. The method for synthesizing polyphenylene sulfide according to claim 1, characterized in that: the molar ratio of the p-dichlorobenzene in the step 3) to the sodium sulfide dihydrate in the step 1) is 1-1.01: 1.

8. The method for synthesizing polyphenylene sulfide according to claim 1, characterized in that: in the step 4), after the reaction materials are vacuumized and the solvent is recovered, deionized water is added for soaking and cooling.

9. The method for synthesizing polyphenylene sulfide according to claim 8, characterized in that: washing with deionized water.

10. The polyphenylene sulfide resin synthesized by the method for synthesizing polyphenylene sulfide according to any one of claims 1 to 9.

Technical Field

The invention relates to a synthetic method of polyphenylene sulfide, belonging to the technical field of synthesis of high polymer material resin.

Background

The polyphenylene sulfide resin has excellent chemical resistance and high-temperature thermal stability, and has the performances of flame retardance, insulation, radiation resistance and the like. The engineering plastic is suitable for producing various electronic devices, automobile parts and the like by injection molding, extrusion molding and other methods.

At present, in the industrial production of polyphenylene sulfide resin, water-containing sodium sulfide and p-dichlorobenzene are mostly used as raw materials, no matter the sodium sulfide is excessive or the p-dichlorobenzene is excessive, the end groups of the produced polyphenylene sulfide resin are mainly chlorine-containing groups and sulfydryl-containing groups, the groups still have activity in the high-temperature processing process, and because the end group active groups are too many, the groups are easy to react at high temperature and then are separated or react with other substances, degrade or crosslink, and have poor flowability, the processing of a screw extruder is seriously influenced in the modification processing process of the polyphenylene sulfide resin, particularly inorganic materials are added in a high filling mode, therefore, the polyphenylene sulfide resin with certain stable viscosity is needed, the change of the melt index in the processing process is reduced, and the polyphenylene sulfide resin has a more stable resin melt index.

In order to reduce the reactive end groups of polyphenylene sulfide resins, a common method in the art is to add an end-capping agent. For example, patent WO1990000575 discloses a terminal-capped copolymerization to prepare a terminal-capped copolymer arylene sulfide by heating a diiodo aromatic compound and a small amount of a monoiodo aromatic compound in the presence of elemental sulfur, wherein the monoiodo aromatic compound is used as a chain terminator. The copolymerized polyarylene sulfide is prepared by using p-diiodobenzene as a raw material, the p-diiodobenzene is expensive and reacts with sulfur, so that a plurality of polysulfide bonds are generated, and although a monoiodoaromatic compound is used as a chain termination agent, the problem that the chain breakage of the polysulfide bonds during the processing of the resin still exists, the temperature resistance of the PPS resin is not high, and the change of a melt index at a high temperature is large is caused.

Chinese invention patent CN106633062A discloses a low-chlorine-content polyphenylene sulfide obtained by end capping with 4-phenylthio-benzenethiol (PTT), a method for preparing the same, a resin composition, and a molded article. The preparation method of the polyphenylene sulfide takes a sulfur-containing compound, an alkaline substance and p-dichlorobenzene as raw materials, takes fatty acid as a polycondensation auxiliary agent and takes PTT as an end group regulator to carry out polycondensation reaction. The method has the advantages of high product yield and low cost, the obtained polyphenylene sulfide product has low chlorine content and excellent fluidity and heat resistance, but the method does not reduce the number of active end groups, only changes the chlorine end group into another sulfur end group, does not change the total amount of the sulfur end group and the chlorine end group, has the activity of the sulfur mercapto end group, and simultaneously causes the problems of high cost and difficult preparation for the production of resin because the PTT is difficult to produce.

Disclosure of Invention

In order to overcome the defects, the invention provides a synthetic method of polyphenylene sulfide.

The synthetic method of the polyphenylene sulfide comprises the following steps:

1) dehydrating raw material sodium sulfide: mixing the sodium sulfide, LiCl and NMP, and performing azeotropic dehydration to obtain a dehydrated material;

2) pretreatment: mixing the dehydrated material with chlorobenzene, heating to 250-270 ℃, and reacting for 1.5-3 hours to obtain a pretreated material;

3) polymerization: cooling the pretreated material to 220-235 ℃, mixing with p-dichlorobenzene, reacting for 2-3 hours, then heating to 250-270 ℃, and reacting for 4-5 hours to obtain a reacted material;

4) and (3) post-treatment: and cooling the reacted materials, filtering, washing the solid, and drying to obtain the polyphenylene sulfide.

Preferably, in the step 1), the molar ratio of the sodium sulfide monohydrate to the NMP to the LiCl is 1:4 to 5:0.3 to 0.6.

Preferably, in the step 1), the azeotropic dehydration is carried out by heating to 195 to 210 ℃ under a protective atmosphere.

Preferably, the protective atmosphere is an inert atmosphere or nitrogen.

Preferably, the inert atmosphere is helium, neon, argon, krypton or xenon.

Preferably, in the step 2), the molar ratio of sodium sulfide to chlorobenzene in the dehydrated material is 1: 0.05-0.1.

Preferably, the molar ratio of the p-dichlorobenzene in the step 3) to the sodium sulfide dihydrate in the step 1) is 1-1.01: 1.

Preferably, in the step 4), after the reaction materials are vacuumized to recover the solvent, deionized water is added for soaking and cooling.

Preferably, deionized water is used for washing.

The invention also provides the polyphenylene sulfide resin synthesized by the method for synthesizing the polyphenylene sulfide.

The polyphenylene sulfide resin is partially end-capped polyphenylene sulfide, and end-capped end groups are benzene rings, so that the amount of chlorine and sulfur in active end groups can be reduced, and the stability of the polyphenylene sulfide is improved.

The method controls the raw material of the sodium sulfide polyhydrate, namely Na is used₂S·3H₂O is firstly dehydrated and then reacts with chlorobenzene to generate a certain amount of thiophenol monofunctional substance, and then p-dichlorobenzene is added for reaction polymerization. Due to the existence of monofunctional active thiophenolate, part of polymers only have one active group in the polymerization and reaction processes, and the reaction is carried out in one direction, so that the polyphenylene sulfide with relatively high molecular weight is obtained, and part of end groups are benzene rings, so that the number of active end groups chlorine or sulfur is reduced, and the polyphenylene sulfide with reduced active end groups chlorine and sulfur is obtained.

Compared with the prior art, the invention has the following beneficial effects:

the method adopts chlorobenzene to react with sodium sulfide for the first time to generate thiophenol monofunctional group substances, and then adds p-dichlorobenzene to perform reaction polymerization.

Detailed Description

The synthetic method of the polyphenylene sulfide comprises the following steps:

1) dehydrating raw material sodium sulfide: mixing the sodium sulfide, LiCl and NMP, and performing azeotropic dehydration to obtain a dehydrated material;

2) pretreatment: mixing the dehydrated material with chlorobenzene, heating to 250-270 ℃, and reacting for 1.5-3 hours to obtain a pretreated material;

3) polymerization: cooling the pretreated material to 220-235 ℃, mixing with p-dichlorobenzene, reacting for 2-3 hours, then heating to 250-270 ℃, and reacting for 4-5 hours to obtain a reacted material;

4) and (3) post-treatment: and cooling the reacted materials, filtering, washing the solid, and drying to obtain the polyphenylene sulfide.

In the conventional PPS production method, each linear PPS molecule has two end groups which are respectively chlorine or sulfur-containing groups, and the two groups have higher activity in the high-temperature processing process to cause the decomposition or chain growth of polyphenylene sulfide, so that the polyphenylene sulfide is easy to be extracted or participate in the reaction to cause the change of a melt index (melt index). The method of the invention utilizes chlorobenzene to react with a large amount of sulfur-containing compounds at high temperature to generate substances containing thiophenolate firstly, and plays a role of monofunctional group regulation polymerization reaction in the polymerization process to reduce the number of active end groups such as sulfure mercapto end groups or chlorine end groups in the polyphenylene sulfide resin generated by the reaction of p-dichlorobenzene and sodium sulfide, thereby achieving the purpose of reducing the active end groups and obtaining the polyphenylene sulfide containing a certain amount of relatively inert benzene end groups.

The step 1) is a step of azeotropic dehydration of sodium sulfide, and can be carried out by adopting a conventional method.

Preferably, in the step 1), the molar ratio of the sodium sulfide monohydrate to the NMP to the LiCl is 1:4 to 5:0.3 to 0.6.

Preferably, in the step 1), the azeotropic dehydration is carried out by heating to 195 to 210 ℃ under a protective atmosphere.

The protective atmosphere in the invention is an atmosphere which does not participate in the reaction. Preferably, the protective atmosphere is an inert atmosphere or a nitrogen atmosphere. The inert atmosphere is inert gas protection, and preferably, the inert atmosphere is helium, neon, argon, krypton or xenon.

And step 2) is a pretreatment step, chlorobenzene is added to react with sodium sulfide to generate a substance containing thiophenolate. Due to the difference of the K values of the reaction constants of chlorobenzene and p-dichlorobenzene, if the chlorobenzene and the p-dichlorobenzene exist simultaneously, sodium sulfide firstly reacts with the p-dichlorobenzene, the chlorobenzene participates in the reaction with great difficulty, and thus the expected effect cannot be achieved. Or chlorobenzene is added after the polymerization is completed, and since the activity of the long-chain PPS becomes low, chlorobenzene does not play a role in polymerization end capping at all. Therefore, the present invention requires a pretreatment before polymerization to allow chlorobenzene to react with sodium sulfide first.

Preferably, in the step 2), the molar ratio of sodium sulfide to chlorobenzene in the dehydrated material is 1: 0.05-0.1.

And 3) a polymerization reaction step, wherein sodium sulfide and p-dichlorobenzene react to generate polyphenylene sulfide. The common ratio of sodium sulfide to p-dichlorobenzene is suitable for the invention. Preferably, the molar ratio of the p-dichlorobenzene in the step 3) to the sodium sulfide dihydrate in the step 1) is 1-1.01: 1.

And 4) a post-treatment step, namely obtaining the polyphenylene sulfide resin from the polyphenylene sulfide-containing slurry.

Preferably, in the step 4), after the reaction materials are vacuumized to recover the solvent, deionized water is added for soaking and cooling. The solvent can be recycled after being recovered, and the synthesis cost of the polyphenylene sulfide is reduced.

In order to reduce the introduction of impurity ions, it is preferable that, in step 4), deionized water is used for washing.

The invention also provides the polyphenylene sulfide resin synthesized by the synthesis method.

The polyphenylene sulfide resin is partially end-capped polyphenylene sulfide, and end-capped end groups are benzene rings, so that the amount of chlorine and sulfur in active end groups can be reduced, and the stability of the polyphenylene sulfide is improved.

The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.