Polyphenylene sulfide having low chlorine content and preparation method therefor

Abstract

The present invention provides a polyphenylene sulfide resin having a low chlorine content and a preparation method therefor. The polyphenylene sulfide resin of the present invention has a weight average molecular weight of 55000 or less and a chlorine element content of 900 ppm or less, and the polyphenylene sulfide resin has a rough-surface structure and a specific surface area of 70.00 m2 / g or more obtained according to a BET test method. The polyphenylene sulfide resin provided by the present invention has good fluidity, processability, environmental friendliness, and very good reaction activity during processing and use. In addition, by means of the preparation method of the present invention, a low-chlorine polyphenylene sulfide resin having a proper molecular weight can be obtained by removing chlorine-containing substances from a reaction system during polymerization by providing a reduced pressure condition at the final stage of a polymerization reaction. The method of the present invention can achieve the preparation of the low-chlorine polyphenylene sulfide resin without using additional capping molecules, and the method is relatively simple and further reduces the environmental burden and the production cost.

Description

Polyphenylene sulfide with low chlorine content and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to a polyphenylene sulfide with low chlorine content and a preparation method thereof, a resin composition and a shaped body, belonging to the field of preparation and processing of engineering plastics, and in particular to the field of preparation and processing of polymer materials in electronic engineering. BACKGROUND

[0002] Polyphenylene sulfide resin (PPS) is an engineering plastic with excellent heat resistance, chemical resistance, flame retardancy, mechanical strength, electrical properties, dimensional stability, etc. Since PPS can be shaped into various shaped products, films, sheets, fibers, etc. by general melt processing methods such as extrusion molding, injection molding, compression molding, etc., it is widely used in the fields of electronic and electrical equipment, automotive equipment, etc.

[0003] If a polymer product such as plastic contains halogen (fluorine, chlorine, bromine, iodine), hydrogen halide gas will be emitted during combustion, rapidly diluting oxygen and thus extinguishing the fire. However, when the concentration of released hydrogen halide is high, it can cause a decrease in visibility, making it impossible to identify an escape route; at the same time, hydrogen halide is highly toxic and can affect the respiratory system. In addition, when hydrogen halide gas released by the combustion of halogen-containing polymers combines with water vapor, it generates a corrosive liquid, causing corrosion to some equipment and buildings. Therefore, polymers used in electronic and electrical equipment have strict requirements on halogen content. For example, the European Union generally requires that the bromine and chlorine content in materials used in the field of electronics and electrical appliances be less than 900 ppm and 1500 ppm, respectively.

[0004] PPS and its modified materials are used to make 50%-60% of electronic and electrical products. PPS does not need to add bromine-based flame retardants for flame retardancy due to its excellent flame retardancy, and there is no participation of bromine element in the commonly used PPS synthesis process, so there is no bromine element in the PPS product.

[0005] The main method for synthesizing PPS at home and abroad at present is Phillips method, i.e. sulfide and polyhalogenated aromatic compound are polycondensed at high temperature in a polar solvent to synthesize PPS resin. Phillips method usually uses sodium sulfide (or sodium hydrosulfide and sodium hydroxide) and p-dichlorobenzene as main raw materials to synthesize PPS, and the reaction equation is shown as follows.

[0006] According to the different proportions of raw materials, the end groups of PPS are mainly chlorine end groups and sodium mercapto end groups, so there is chlorine in the PPS product.

[0007] When PPS resin is synthesized by Phillips method, in order to ensure the stability of the reaction, dichlorobenzene is usually slightly excessive, and the molecular weight of PPS resin is controlled by controlling the excessive degree of dichlorobenzene. In theory, increasing the amount of dichlorobenzene will reduce the molecular weight of PPS resin, at this time the absolute number of end groups will increase, and the proportion of chlorine end groups in the end groups will also increase, thereby causing the chlorine content of PPS resin to increase significantly. The chlorine content of conventional PPS resin is usually above 2000 ppm, which cannot meet the halogen content control requirements of the electronic and electrical industry. Reducing the amount of dichlorobenzene can reduce the chlorine content, but it will make the flowability of PPS resin worse, affecting the modification process and its downstream use.

[0008] From the literature reports, to prepare PPS resin with low chlorine content, the chlorine content can be reduced to the required range by adjusting the raw material ratio, polymerization process, post-treatment purification process and adding end group regulator.

[0009] Both reference document 1 and reference document 2 propose adding various additives, adjusting the addition amount and addition time, and polymerization parameters, etc. to make PPS high molecular weight, thereby reducing the chlorine content in the product PPS, but the flowability of the resin itself will be significantly worse. When PPS is used in the field of electronic and electrical equipment, glass fiber is usually needed to be added in the PPS modified material, therefore, in addition to considering the need to reduce halogen content from environmental regulations, easy molding processing is also needed. As a solution, PPS with lower melt viscosity is needed. The reason is that if the melt viscosity of PPS is too high, it cannot be used for fine electronic small parts or large area thin plates, and materials with poor flowability cannot be well distributed throughout the mold, resulting in defects in injection molded parts. Therefore, there is still a concern that chlorine content and processing and molding cannot be balanced.

[0010] Reference document 3 proposes a method for reducing chlorine content by heating PPS with a compound containing a mercapto group or an alkali metal salt thereof in a solvent that can dissolve PPS. Reference document 4 proposes a method for reducing chlorine content by reacting PPS finished product with 2-mercaptobenzimidazole and sodium hydroxide in a solvent at high temperature. However, these methods need to re-react the separated PPS resin at high temperature for a long time and perform post-treatment, so the efficiency is low.

[0011] In reference 5, in order to obtain PPS with low halogen content, one or more compounds selected from the group consisting of mercapto compounds, metal salts of mercapto compounds, phenolic compounds, metal salts of phenolic compounds, and disulfide compounds are added as end group regulators. The principle of obtaining PPS resin with low halogen content is that the -S- substituent cleaved from benzene thiol or diphenyl disulfide replaces the terminal chlorine of PPS to form -S-C6H5 end group, thereby reducing the halogen content of PPS resin. However, in the examples of this patent document, the chlorine content of the powdered polyarylene sulfide resin synthesized by using benzene thiol, phenol, disulfide compound (diphenyl disulfide, abbreviated as DPDS) and other additives is still greater than 1200 ppm. In addition, benzene thiol has a peculiar odor during the manufacture of PPS resin, so environmental problems will occur in the manufacturing process and the recycling process.

[0012] In reference 6, a novel method is provided to reduce the chlorine content of polyphenylene sulfide, which is capped with 4-phenylthio-phenyl mercaptan. In this invention, the preparation method of polyphenylene sulfide uses sulfur-containing compounds, alkaline substances and p-dichlorobenzene as raw materials, fatty acids as polycondensation aids, and 4-phenylthio-phenyl mercaptan (PTT) as end group regulator for polycondensation reaction. The obtained polyphenylene sulfide product has low chlorine content, excellent flowability and heat resistance, so it can meet the use requirements of low chlorine and high flowability in the electronic and electrical industry, but an end capping agent is used in this process.

[0013] Reference:

[0014] Reference 1: JP61007332A

[0015] Reference 2: US4038263A

[0016] Reference 3: JP Laid-open Sho 62-106929

[0017] Reference 4: US20160208081A1

[0018] Reference 5: JP2010126621A

[0019] Reference 6: CN106633062A SUMMARY

[0020] PROBLEMS TO BE SOLVED BY THE INVENTION

[0021] For polyphenylene sulfide (PPS), for example, the sodium sulfide method, the synthesis of polyphenylene sulfide by sodium sulfide method belongs to step-by-step polycondensation, and the monomers are usually p-dichlorobenzene and sodium sulfide / sodium hydrosulfide. In order to obtain a polymer with high molecular weight, the ratio of the two monomers should be close to 1. However, in actual polymerization, the excessive amount of sulfur source often leads to the risk of depolymerization. Therefore, the amount of p-dichlorobenzene needs to be controlled slightly excessive during production. Therefore, the chlorine end group of the produced polyphenylene sulfide is mostly chlorine end group.

[0022] For the improvement of the end group of polyphenylene sulfide for the purpose of reducing the chlorine content, as mentioned in the above cited documents, the content of end group chlorine can be improved by introducing various end capping agents. However, such a method will inevitably affect or limit the control of molecular weight and thermal stability.

[0023] In addition, the factors related to the chlorine content in the polymer are not only the end group as mentioned above, but also related to the final molecular weight of the polyphenylene sulfide resin.

[0024] For polyphenylene sulfide resin, if its molecular weight is high, the proportion of end group will decrease relatively. Therefore, for high molecular weight polyphenylene sulfide, the control of chlorine content is relatively easy. However, high molecular weight polyphenylene sulfide has reduced flowability, which also limits its application.

[0025] On the contrary, for medium and low molecular weight polyphenylene sulfide, it has good flowability, but due to the increase of end group content, it is difficult to consider both low chlorine content and processing property in this case.

[0026] Therefore, from the prior art, although some research has been done on reducing the chlorine content of polyphenylene sulfide during synthesis, the reduction of chlorine content is not sufficient, and there is still room for further improvement in considering the processability while reducing the chlorine content.

[0027] In view of the above problems, the present application provides a new synthesis method of low chlorine content polyphenylene sulfide resin and a low chlorine content, high activity sulfide resin product. In this method, the content of chlorine element in the final polyphenylene sulfide resin can be reduced without introducing additional end capping molecules. Further, by providing a reduced pressure condition at the end of the polymerization reaction, the chlorine-containing substances are removed from the reaction system during the polymerization process, so that the content of chlorine element in the polymer system can be greatly reduced under the condition of obtaining a polymer with suitable molecular weight. Moreover, more surprisingly, the final polymer particles obtained by the above process operation have excellent surface roughness (multiple micropores) characteristics, thereby endowing the polymer particles with very good reactivity.

[0028] Solution to a problem

[0029] Through long-term research by the inventor, it is found that the above technical problems can be solved by implementing the technical solutions as follows:

[0030] [1]. The present application first provides a low-chlorine-content polyphenylene sulfide resin, wherein the weight average molecular weight of the polyphenylene sulfide resin is 55,000 or less, the content of chlorine element is 900 ppm or less,

[0031] and the polyphenylene sulfide resin has a surface rough structure, and has a specific surface area of 70.00 m 2 / g or more according to the BET test method.

[0032] [2]. The polyphenylene sulfide resin according to [1], wherein the weight average molecular weight of the polyphenylene sulfide is 35,000 to 50,000; and the content of chlorine element is 500 to 800 ppm.

[0033] [3]. The polyphenylene sulfide resin according to [1] or [2], wherein the polyphenylene sulfide resin is a granular resin, and the average particle size of the granules is 800 to 1,300 μm.

[0034] [4]. The polyphenylene sulfide resin according to any one of [1] to [3], wherein the polyphenylene sulfide resin further satisfies one or more of the following conditions:

[0035] i. the crystallization temperature is 240°C or higher;

[0036] ii. the rough structure is a microporous structure, and the pore volume of the micropores is 0.32 to 0.40 cm 3 / g;

[0037] iii. the content of Na ions measured by ICP is 15 to 35 ppm.

[0038] [5]. The polyphenylene sulfide resin according to any one of [1] to [4], wherein all the components in the molecular chain of the polyphenylene sulfide resin are derived from a sulfur source and p-dichlorobenzene as reactants.

[0039] [6]. The present application further provides a method for preparing a low-chlorine-content polyphenylene sulfide resin, wherein the method comprises the following steps:

[0040] a first polymerization step, a second polymerization step, and a post-treatment step,

[0041] wherein,

[0042] in the first polymerization step, a sulfur source and p-dichlorobenzene are subjected to first polymerization,

[0043] the second polymerization step, includes reducing the pressure in the first polymerization to perform the second polymerization,

[0044] the post-treatment step, includes a step of washing the polyphenylene sulfide resin obtained in the second polymerization step.

[0045] [7]. The method according to [6], wherein the step of reducing the pressure to perform the second polymerization is performed when the conversion of the p-dichlorobenzene in the first polymerization is 98.5% to 99.6%.

[0046] [8]. The method according to [6] or [7], wherein the pressure is reduced to the end point of the reduced pressure in 1 to 3 hours.

[0047] [9]. The method according to any one of [6] to [8], wherein the step of the first polymerization and the step of the second polymerization are performed in the presence of a fatty acid.

[0048]

[0010] . The method according to any one of [6] to [9], wherein the temperature of the sodium sulfide and the p-dichlorobenzene in the step of the first polymerization is above 220°C.

[0049]

[0011] . The method according to any one of [6] to

[0010] , wherein the temperature of the reaction system is kept substantially constant when the pressure is reduced in the step of the second polymerization; the pressure in the step of the second polymerization is reduced by 1 to 3 kgf / cm 2 .

[0050]

[0012] . The method according to any one of [6] to

[0011] , wherein the step of the post-treatment, includes a step of washing the polyphenylene sulfide resin obtained in the second polymerization step one or more times with an acid, water or a combination thereof under heating.

[0051]

[0013] . The method according to any one of [6] to

[0012] , wherein the polyphenylene sulfide resin has a weight average molecular weight of 55,000 or less and a content of chlorine of 900 ppm or less.

[0052]

[0014] . The method according to any one of [6] to

[0013] , wherein the polyphenylene sulfide resin obtained by the method is a granular resin, and the average particle size of the granules is 800 to 1,300 μm.

[0053]

[0015] . The method according to

[0014] , wherein the granules have a surface rough structure and a specific surface area of 70.00 m 2 / g or more according to the BET test method.

[0054]

[0016] . In addition, the present invention also provides a composite material, wherein the composite material comprises a polyphenylene sulfide resin according to any one of [1] to [5] and a filler, wherein the filler comprises fibers.

[0055]

[0017] . In addition, the present invention also provides an injection-molded article, wherein it is obtained by injection molding of the composite material according to

[0016] .

[0056] The effects of the invention

[0057] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0058] 1. The polyphenylene sulfide resin provided by the present invention has a low chlorine content and a medium to low molecular weight. Specifically, the weight average molecular weight is below 55,000 and the chlorine content is below 900 ppm. This makes the polyphenylene sulfide resin provided by the present invention more environmentally friendly while maintaining good fluidity and processability during processing and use.

[0059] 2. The polyphenylene sulfide resin provided by this invention also has a rough (microporous) surface structure and a high specific surface area. Specifically, its specific surface area is 70.00 m² obtained according to the BET test method. 2 The concentration of the polymer particles is above a certain level (g), thus endowing the polymer particles with very good reactivity.

[0060] 3. The method for preparing polyphenylene sulfide resin provided by this invention can reduce the chlorine content in the final polyphenylene sulfide resin without using additional end-capping molecules, simply by providing reduced pressure at the end of the polymerization reaction. The method is relatively simple and further reduces environmental burden and production costs.

[0061] 4. The polyphenylene sulfide resin provided by the present invention has a higher specific surface area, resulting in a more significant washing effect, higher purity of PPS resin, and lower ash, volatile matter, and sodium ion content. Detailed Implementation

[0062] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0063] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0064] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0065] In the present specification, the "substantially" or "essentially" means that the error is below 1%, or below 0.8% or below 0.6% compared to the relevant perfect standard or theoretical standard. In addition, when the present specification refers to "all" or "the entire", it also means "substantially" or "essentially" "all" or "the entire".

[0066] In the present specification, "%" means mass percentage unless otherwise specified.

[0067] In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0068] In the present specification, "optional" or "optionally" means that the event or circumstance described next can or can not occur or occur with any described condition, and the description includes the case where the event occurs and the case where the event does not occur.

[0069] In the present specification, the "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", and the like refer to the specific elements (for example, features, structures, properties, and / or characteristics) described in relation to the embodiments are included in at least one embodiment described herein, and can be present in other embodiments or can not be present in other embodiments. In addition, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0070] In the present specification, the use of the terms "comprise" and / or "include" means that the features, steps, operations, devices, components, and / or combinations thereof are present.

[0071] In the present specification, "room temperature" or "ambient temperature" used means "23±2℃" of indoor environmental temperature.

[0072] The present application mainly provides a polyphenylene sulfide resin having a low chlorine content, and particularly, the polyphenylene sulfide resin is a polyphenylene sulfide resin having a medium or low level of molecular weight. The polyphenylene sulfide resin is prepared by a method of a segmented synthesis, and the chlorine content of the final product is reduced by a method of reducing pressure in the latter stage of the reaction, and thus, even if an additional end-capping agent is not used, a polyphenylene sulfide resin product having a reduced chlorine content and excellent surface properties can be obtained.

[0073] <First aspect>

[0074] The first aspect of the present application provides a polyphenylene sulfide resin having a low chlorine content and a medium or low level of molecular weight.

[0075] Specifically, the polyphenylene sulfide resin has a weight average molecular weight of 55000 or less, and a content of chlorine element of 900 ppm or less. In some specific embodiments, the polyphenylene sulfide resin has a weight average molecular weight of 35000-50000, such as 38000, 40000, 42000, 44000, 46000, 48000, etc., and when the weight average molecular weight of the PPS resin is 55000 or less, good flowability and processability can be maintained; and the content of chlorine element can be preferably 100-800 ppm, such as 150 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, etc.

[0076] In the present application, the polyphenylene sulfide resin has a surface roughness (multi-porous) structure, and has a specific surface area of 70.00 m 2 / g or more, such as 72.00 m 2 / g or more, 73.00 m 2 / g or more, 74.00 m 2 / g or more, 75.00 m 2 / g or more, etc., such as 76-85 m 2 / g, etc. The surface roughness (multi-porous) structure of the PPS resin of the present application increases the specific surface area of the PPS resin, thereby endowing the PPS resin with excellent reactivity. In addition, in the washing treatment step in the PPS preparation process described below, due to the surface roughness (multi-porous) structure of the PPS resin, the washing effect is more significantly better, so that the PPS resin has higher purity and lower impurity content, and in the same glass fiber and glass mineral modification system, the injection molding smoke is less, and the PPS resin is more suitable for processing of electronic devices.

[0077] In some specific embodiments, the polyphenylene sulfide resin is a granular resin, and in some specific embodiments, the average particle size of the granular resin is 800-1300 μm, such as 900 μm, 1000 μm, 1100 μm, 1200 μm, etc.

[0078] The pore volume of the polyphenylene sulfide resin microporous structure is not particularly limited, as long as the above-mentioned specific surface area can be achieved, and preferably, the pore volume of the polyphenylene sulfide resin microporous structure is 0.32-0.40 cm 3 / g, such as 0.33 cm 3 / g, 0.34 cm 3 / g, 0.35 cm 3 / g, 0.36 cm 3 / g, 0.37 cm 3 / g, 0.38 cm 3 / g, 0.39 cm 3 / g, etc.

[0079] In some specific embodiments, the polyphenylene sulfide resin has a higher crystallization temperature, in particular, can be 240°C or higher (according to DSC test), for example, 242°C or higher, 245°C or higher, 248°C or higher, 250°C or higher, 255°C or higher, etc., preferably 240-260°C. The higher crystallization temperature makes the polyphenylene sulfide resin of the present application have higher mechanical properties and use performance.

[0080] Further, the polyphenylene sulfide resin has a lower content of impurities, including ash, volatile matter, metal ions, etc., such as Na ions often cited in the preparation process of polyphenylene sulfide resin, the content of Na ions determined by ICP is 15-35 ppm, for example, 18 ppm, 20 ppm, 22 ppm, 25 ppm, 28 ppm, 30 ppm, 32 ppm, etc.

[0081] In addition, in some preferred embodiments of the present application, the components in the molecular chain of the polyphenylene sulfide resin are derived from the sulfur source and p-dichlorobenzene as reactants. In other words, the polyphenylene sulfide resin of the present application forms a molecular chain structure only by the above two components during synthesis, without using other end-capping molecules, which also achieves the purpose of reducing the chlorine content. As for the sulfur source, there is no particular limitation in principle, and elemental sulfur, sulfides of alkali metals, hydrosulfides of alkali metals, etc. commonly used in the art can be used. In the present application, sulfides of alkali metals are preferred, such as sodium sulfide, etc.

[0082] The polyphenylene sulfide resin provided by the present application has low chlorine content, high specific surface area, good flowability, high crystallization temperature, low impurity content, etc., which endows the polyphenylene sulfide resin with excellent reactivity and processability. In some specific embodiments, the polyphenylene sulfide resin of the present application is particularly suitable for semiconductor electronic and electrical applications such as insulated gate bipolar transistors (IGBT) and base materials.

[0083] <Second aspect>

[0084] The second aspect of the present application provides a method for preparing a polyphenylene sulfide resin with low chlorine content, in particular, the method for preparing the polyphenylene sulfide resin described in the first aspect above.

[0085] Specifically, the preparation method can include the following steps:

[0086] The first polymerization step, the second polymerization step, and the post-treatment step.

[0087] In the first polymerization step, the sulfur source and p-dichlorobenzene are subjected to first polymerization; in the second polymerization step, the first polymerization is subjected to reduced pressure for second polymerization.

[0088] The post-treatment step includes a step of washing the polyphenylene sulfide resin obtained in the second polymerization step.

[0089] In the second polymerization step, the pressure in the system is reduced to be lower than the pressure in the first polymerization step, and at least part of the small molecular chlorine-containing substances are discharged from the reaction system.

[0090] (First polymerization step)

[0091] The first polymerization step of the present application mainly includes a polymerization reaction of a sulfur source and dichlorobenzene, especially sodium sulfide and dichlorobenzene, to obtain a polyphenylene sulfide polymer with a certain molecular weight.

[0092] In the first polymerization step, the amount of dichlorobenzene is 0.99-1.05 mol, for example 1.00 mol, 1.02 mol, etc., based on 1 mol of sulfur in the sulfur source.

[0093] In some specific embodiments, the first polymerization is carried out in a solvent, which can be selected from polar solvents commonly used in the art, preferably high-boiling polar solvents such as DMF, DMAc or NMP, and most preferably NMP. Further, the amount of solvent is 3.5-4.5 mol based on 1 mol of sulfur. In other specific embodiments, when the sulfur source is used in the form of an aqueous solution, the first polymerization step can further include a dehydration step to control the water content to 1.0-1.2 mol / mol of sulfur.

[0094] In the first polymerization step, the polymerization of the sulfur source and dichlorobenzene is carried out under heating. The heating temperature can be above 220°C, preferably 220-270°C, for example 230°C, 240°C, 250°C or 260°C, etc. In some specific embodiments, the heating process of the first polymerization step can be carried out in stages to promote the polymerization, and in some preferred embodiments, the first holding reaction includes heating to 220-240°C within 1-1.5 h, and holding for 1-3 h; the second holding reaction includes heating to 250-270°C at a rate of 0.5-1°C / min, and holding for 0.5-1 h.

[0095] In some more specific embodiments, water in the system can be supplemented after the first holding reaction, if necessary. By adding an appropriate amount of water, the system can be phase-separated, which can increase the conversion rate of the dichlorobenzene while increasing the molecular weight of the PPS resin. Specifically, the amount of water added is not particularly limited in principle, and from the perspective of increasing the molecular weight while taking into account cost and efficiency, the ratio of the amount of water added to the amount of sulfur in the system can be 1.5 to 3 mol of water per mol of sulfur, and preferably 1.8 to 2.8 mol of water per mol of sulfur.

[0096] Further, in some preferred embodiments of the present application, the sodium sulfide as the sulfur source in the first polymerization step can be obtained by a dehydration reaction of NaHS and a basic substance. Specifically, the dehydration reaction includes mixing NaHS, a basic substance, and a solvent (NMP), wherein the basic substance can be sodium hydroxide, potassium hydroxide, or a mixture thereof used in the form of an aqueous solution. The specific reaction formula of the dehydration reaction is as follows:

[0097] NaHS + NaOH → Na2S + H2O (1)

[0098] Na2S + H2O → H2S + 2NaOH (2)

[0099] wherein formula (1) is the main reaction of the dehydration reaction, formula (2) is a possible side reaction of the dehydration reaction, and formula (3) is the reaction of partial hydrolysis of the solvent in the basic substance. The product SMAB produced after the hydrolysis of the solvent can further improve the solubility of NaHS, as shown in formula (4) to more efficiently obtain sodium sulfide.

[0100] From the perspective of further promoting the generation of sodium sulfide, in the dehydration reaction, based on 1 mol of NaHS, the amount of the basic substance can be 1.00 to 1.04 mol, such as 1.01 mol, 1.02 mol, 1.03 mol, etc.; and the amount of NMP can be 2.4 to 3.0 mol, such as 2.5 mol, 2.6 mol, 2.7 mol, 2.8 mol, 2.9 mol, etc.

[0101] In some specific embodiments, a fatty acid salt can also be added in the dehydration reaction. Preferably, the fatty acid salt is a sodium salt or a potassium salt of a C5-C6 fatty acid, which can include one or more of the sodium salt or the potassium salt of hexanoic acid, pentanoic acid, isopentanoic acid, 2-ethylbutyric acid, etc. On the one hand, the fatty acid salt can further improve the solubility of the sulfur source, and on the other hand, the fatty acid salt can act as a catalyst in the subsequent polymerization reaction, promoting the growth of PPS molecular weight and reducing polymerization side reactions.

[0102] In some specific embodiments, in order to ensure uniformity of the reaction, the dehydration reaction can be accompanied by a step of stirring. The manner of stirring is not particularly limited and can be selected as desired. In some preferred embodiments, the stirring speed can be 100 to 200 rpm, such as 110 rpm, 130 rpm, 150 rpm, 170 rpm, 190 rpm, etc.

[0103] (Second polymerization step)

[0104] In this embodiment, the first polymerization is followed by a step of reducing the pressure to perform a second polymerization. The "reducing the pressure" refers to a reduction in the pressure under the conditions of the first polymerization.

[0105] In some preferred embodiments of the present application, the step of reducing the pressure comprises reducing the pressure in the reaction system by 1 to 3 kgf / cm 2 , such as by 1.2 kgf / cm 2 , 1.4 kgf / cm 2 , 1.6 kgf / cm 2 , 1.8 kgf / cm 2 , 2.0 kgf / cm 2 , 2.2 kgf / cm 2 , 2.4 kgf / cm 2 , 2.6 kgf / cm 2 , 2.8 kgf / cm 2 , etc., while keeping the temperature of the reaction system substantially constant.

[0106] When the pressure in the reaction system is reduced by 1 to 3 kgf / cm 2 , a low-chlorine polyphenylene sulfide resin having a suitable molecular weight and a microporous structure can be obtained relatively easily. In addition, when the pressure drop is too small, the chlorine content in the system can not decrease significantly; when the pressure drop is too large, the molecular weight of the finished polymer is low, and because a large amount of water is removed during the temperature reduction, if not controlled, it can easily cause a change in the morphology of the particles, thereby possibly losing the microporous structure in part.

[0107] For the condition at which the step of reducing pressure starts, from the perspective of molecular weight control freedom and production efficiency, in some preferred embodiments, when the conversion rate of p-dichlorobenzene in the first polymerization is 98.5% to 99.6%, for example 98.8%, 99.0%, 99.2%, 99.4%, etc., the step of reducing pressure to carry out the second polymerization is performed. When the conversion rate of p-dichlorobenzene is too low, reducing pressure will result in a large amount of p-dichlorobenzene being discharged, and it can not be easy to obtain a product of the required molecular weight; when the conversion rate of p-dichlorobenzene is too high, reducing pressure will not be able to reduce the chlorine content of the final product, because most of the polymer chains have already been terminated by the excess monomer p-dichlorobenzene. When the conversion rate of p-dichlorobenzene is 98.5% to 99.6%, reducing pressure can greatly reduce the chlorine content in the polymer system under the condition of obtaining a polymer of suitable molecular weight.

[0108] In addition, in other preferred embodiments, although not necessarily, the step of reducing pressure to carry out the second polymerization can also be performed when the weight average molecular weight of the polyphenylene sulfide in the first polymerization is 30,000 to 38,000, for example 31,000, 33,000, 35,000, 37,000, etc. When the weight average molecular weight of the polyphenylene sulfide in the first polymerization is 30,000 to 38,000, reducing pressure can further obtain a polymer of suitable molecular weight and obtain a lower chlorine content.

[0109] For the time of reducing pressure, there is no particular restriction in principle, and it can be determined according to the conditions of the equipment and the reaction. In some specific embodiments, the time of reducing pressure can be 1 to 3 hours, preferably 1.5 to 2.5 hours, for example it can be 1.2 hours, 1.5 hours, 1.8 hours, 2.2 hours, 2.4 hours, etc. In some extreme cases, if the speed of reducing pressure is too fast, the control requirement is high, and if the speed of reducing pressure is too slow, the effect of reducing chlorine will be reduced.

[0110] In the present application, the chlorine-containing substance is removed from the reaction system by reducing pressure during polymerization, so that the chlorine content in the polymer system can be greatly reduced under the condition of obtaining a polymer of suitable molecular weight. The reduction of the chlorine content in the polymer system leads to an increase in the sodium mercapto end group and a decrease in the chlorine end group in PPS when the termination reaction occurs, and finally the purpose of reducing the chlorine content in PPS is achieved. In addition, in the process of reducing pressure, low-boiling-point substances in the molten PPS in the reaction concentrated phase continuously form small bubbles due to the decrease in external air pressure. When the pressure generated inside the bubble is greater than the strength of the bubble wall formed by the molten PPS, the molten PPS cannot withstand the stretching of the wall membrane caused by the difference between the internal and external gas pressures, the bubble wall membrane is torn, the gas escapes from the torn place, and open-cell channels are formed. This morphology is retained during subsequent cooling and crystallization, forming high-specific-surface-area multi-microporous PPS particles.

[0111] (post-treatment step)

[0112] In the present application, in addition to the polymerization step described above, an optional post-treatment step can be used to treat the polymerization product after the polymerization reaction is completed.

[0113] In some specific embodiments, the temperature of the system can be lowered to 90-110°C, such as 95°C, 100°C, 105°C, etc., before the post-treatment step is performed.

[0114] In the post-treatment step, one or more cleaning, distillation, etc. steps can be included.

[0115] In some specific embodiments, the cleaning can be performed under heating, and the PPS resin obtained from the second polymerization step can be subjected to one or more acid washing, water washing, or a combination thereof. After the acid washing, the sodium sulfhydryl end group in the PPS is converted to a sulfhydryl end group, which increases the crystallization temperature of the PPS.

[0116] For the distillation step, the residual solvent (NMP) and fatty acid salt, etc. components in the resin can be removed mainly through the distillation step, before and / or after the cleaning described above.

[0117] The polyphenylene sulfide resin prepared by the preparation method of the present application is a granular resin, and the average particle size of the granules is 800-1300 μm. The weight average molecular weight of the polyphenylene sulfide resin is 55000 or less, and the content of chlorine element is 900 ppm or less. In addition, the granules have a rough surface (multiple micropore) structure, and have a specific surface area of 70.00 m 2 / g or more according to the BET test method.

[0118] (Typical preparation method)

[0119] In some specific embodiments of the present application, the preparation method of the low-chlorine-content polyphenylene sulfide of the present application can include the following steps:

[0120] (1) A sulfur source, a basic substance, a portion of an organic solvent, and a fatty acid salt are added to a reaction kettle, and a dehydration reaction is performed by heating;

[0121] (2) After step (1) is completed, p-dichlorobenzene and another portion of the organic solvent are added to the reaction kettle, and the temperature is raised to 210-250°C, and a holding reaction is performed;

[0122] (3) After step (2) is completed, deionized water is added to the reaction kettle, and the temperature is raised to 250-270°C, and a holding reaction is performed.

[0123] (4) Monitoring the conversion rate of p-dichlorobenzene in the system of step (3), when the conversion rate reaches 98.5% to 99.6%, the temperature is kept unchanged, and the pressure is reduced to 13 to 15.5 kgf / cm 2 , and the internal pressure is reduced by 1 to 3 kgf / cm 2 , to obtain polyphenylene sulfide reaction liquid slurry;

[0124] (5) The polyphenylene sulfide reaction liquid slurry of step (4) is treated to obtain polyphenylene sulfide resin.

[0125] In some more specific embodiments of the present application, the method for preparing low-chlorine-content polyphenylene sulfide can comprise the following steps:

[0126] (1) Adding a sulfur source, an alkaline substance, N-methyl pyrrolidone (NMP), and a fatty acid salt into a reaction kettle, and dehydrating at a temperature of 180 to 210°C to obtain an intermediate product until the water content in the system is 1.0 to 1.2 mol / mol sulfur, and then reducing the temperature to 160 to 180°C;

[0127] (2) After step (1) is completed, adding p-dichlorobenzene and additional N-methyl pyrrolidone into the reaction kettle, and increasing the temperature to 210 to 250°C within 1 to 2 hours, and keeping the temperature for 1 to 4 hours;

[0128] (3) After step (2) is completed, adding deionized water at 1.5 to 3.0 mol / mol sulfur into the reaction kettle, and increasing the temperature to 250 to 270°C at a rate of 0.5 to 1°C / min, and keeping the temperature for 0.5 to 1 hour, and the gas pressure reaches 16 to 17.5 kgf / cm 2 .

[0129] (4) Monitoring the conversion rate of p-dichlorobenzene in the system of step (3), when the conversion rate reaches 98.5% to 99.6%, the temperature is kept unchanged, and the pressure is reduced to 13 to 15.5 kgf / cm 2 (reducing by 1 to 3 kgf / cm 2 ), to obtain polyphenylene sulfide reaction liquid slurry; after the reaction is completed, the temperature of the system is reduced to 90 to 110°C;

[0130] (5) The polyphenylene sulfide reaction liquid slurry of step (4) is treated to obtain polyphenylene sulfide resin.

[0131] The post-treatment step of step (5) comprises: centrifugal filtration and spin-drying the PPS reaction liquid slurry after step (4), rinsing with NMP, spin-drying, rinsing with hydrochloric acid solution, spin-drying, combining and collecting the filtrate, recovering C5 to C6 fatty acid and NMP; and drying the filter cake after multiple washing with deionized water to obtain polyphenylene sulfide resin.

[0132] In a further preferred embodiment of the present application, the process for preparing the low-chlorine-content polyphenylene sulfide of the present application can comprise the following steps:

[0133] (1) adding NMP, 45-55 wt% aqueous NaOH solution, 40-55 wt% aqueous sodium hydrosulfide solution and 35-45 wt% aqueous C5-C6 fatty acid salt solution into a reaction kettle, dehydrating at a rate of 0.7-1.5°C / min to 180-200°C under stirring and nitrogen protection until the water content in the system is 1.0-1.2 mol / mol sulfur, and then cooling to 160-180°C;

[0134] (2) adding p-dichlorobenzene (PDCB) and NMP into the reaction kettle after step (1) is completed, heating to 220-240°C within 1.0-1.5 h, and maintaining the temperature for 1-3 h;

[0135] (3) after step (2) is completed, adding 1.5-3.0 mol / mol sulfur of deionized water into the reaction kettle, heating to 250-270°C at a rate of 0.5-1°C / min, maintaining the temperature for 0.5-1 h, and increasing the gas pressure to 16-17.5 kgf / cm 2 .

[0136] (4) monitoring the conversion rate of p-dichlorobenzene in the system of step (3), when the conversion rate reaches 98.7%-99.5%, slowly releasing the gas through the pressure reducing valve, and then the gas is absorbed by NMP to form monomers and enters the tail gas system, and then the temperature is maintained and the pressure is reduced to 14-15.5 kgf / cm 2 (1-3 kgf / cm 2 ) within 1.5-2.5 h to obtain a PPS reaction solution; after the reaction is completed, the temperature of the system is reduced to 90-110°C;

[0137] (5) filtering the PPS reaction solution after step (4) through a 150-200 mesh screen, rinsing the filter cake with NMP at 130-150°C at a mass ratio of 1:1, spinning to dry, then rinsing the filter cake with a hydrochloric acid solution at a mass ratio of 1:1, spinning to dry, and then collecting the filtrate;

[0138] (6) washing the filter cake obtained in step (5) with deionized water at 70-100°C for more than three times until the conductivity of the filtrate is less than 100 μs / cm, drying the filter cake to obtain a polyphenylene sulfide resin;

[0139] (7) stirring the filtrate obtained in step (6), separating the C5-C6 fatty acid through azeotropic distillation in a rectification device equipped with a water trap, then removing the water through rectification, and finally recovering the solvent NMP through reduced pressure distillation, and the distillation residue can be treated by incineration.

[0140] The C5-C6 fatty acid salt aqueous solution in the step (1) is preferably an organic sodium salt of hexanoic acid, valeric acid, isovaleric acid, 2-ethylbutyric acid, and liquid caustic, and a mixture thereof in any ratio.

[0141] The total amount of the C5-C6 fatty acid salt used in the step (1) is 0.05-0.5 mol, the amount of NMP is 2.4-3.0 mol, and the amount of NaOH is 1.00-1.04 mol, based on 1.0 mol of NaHS.

[0142] The amount of PDCB is 0.99-1.05 mol, and the total amount of NMP in the system is 3.5-4.5 mol, based on 1.0 mol of NaHS, after the addition of PDCB and NMP in the step (2).

[0143] The preferred amount of deionized water added in the step (3) is 1.5-2.5 mol, and the total amount of water in the system is 2.5-4.2 mol, based on 1.0 mol of NaHS.

[0144] The mass concentration of hydrochloric acid in the step (5) is 0.1-0.3 wt%.

[0145] The above preparation method of the present application allows the content of chlorine elements in the PPS resin to be reduced by providing a reduced pressure condition at the end of the polymerization reaction without using any other end-capping agent. Moreover, more surprisingly, the final polymer particles obtained by the above process operation have excellent surface roughness characteristics, thereby imparting the polymer particles with very good reactivity.

[0146] <Third aspect>

[0147] The third aspect of the present application provides a composite material including the polyphenylene sulfide resin according to the first aspect of the present application and a filler, which is not particularly limited and can be a fiber or the like.

[0148] <Fourth aspect>

[0149] The fourth aspect of the present application provides an injection-molded product obtained by injection molding the composite material according to the third aspect.

[0150] Examples

[0151] The embodiments of the present application will be described in detail by referring to the following examples, however, it is to be understood that these examples are merely for illustrating the present application and should not be taken in a limiting sense. Unless specifically noted, the conditions in the examples are carried out under conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are conventional products that can be commercially available.

[0152] The measuring methods of the physical properties and characteristics in the present application are as follows:

[0153] (1) Measuring method of halogen content

[0154] The halogen content in PPS is measured by the method of EN 14582:2007, and the chlorine content is measured by ICP using oxygen bomb combustion.

[0155] (2) Measuring method of melt viscosity (Mv)

[0156] The melt viscosity of PPS is measured by LCR7001 capillary rheometer made by Dynisco. The temperature is set to 310℃. The polymer sample is introduced into the device, and after 5 min, the shear rate is 1216 sec-1, and the melt viscosity is measured. -1 The melt viscosity is measured.

[0157] (3) Measuring method of melting point (Tm) and crystallization temperature (Tc)

[0158] The melting point and crystallization temperature of PPS resin are measured by differential scanning calorimeter (DSC). 4.5-5.5 mg of PPS resin is heated to 340℃ at a temperature increasing rate of 20℃ / min, kept for 5 min, and then cooled to 40℃ at a temperature decreasing rate of 10℃ / min.

[0159] (4) Measuring method of ash content

[0160] 1.50 grams of PPS is accurately weighed into a crucible, and the accurate mass is recorded as G0. It is placed in a 750℃ muffle furnace for calcination for 2 h, and then the furnace is turned off for 0.5 h. It is taken out and cooled in a desiccator for 30 min. Then 5 ml of nitric acid is added, and it is slowly dropped along the inner wall of the crucible with a pipette, so as to ensure that there is no sample residue on the inner wall of the crucible, and the sample is completely covered with nitric acid. The crucible is placed in an electric heating furnace for carbonization for 45 min, and heated until there is no smoke. The carbonized crucible is placed in a 750℃ muffle furnace for calcination for 3 h, and then taken out after cooling for 0.5 h. It is confirmed that the sample is completely calcined, and then placed in a sealed desiccator for cooling for 1.5 h, and then weighed and recorded as G1, that is:

[0161] [Ash content] = G1 / G0 x 100%.

[0162] (5) Measuring method of volatile matter

[0163] Accurately weigh 3 g of sample into an aluminum foil dish, record the mass as G2, and place it in a 300°C oven for 1 h. After drying, cool the sample in a desiccator for 30 min, and then weigh it again, recording the mass as G3. The volatile content is calculated as follows:

[0164] [Volatiles content] = (G2 - G3) / G2 x 100%.

[0165] (6) Method for measuring specific surface area

[0166] The specific surface area of the PPS resin was measured by the gas adsorption method for analyzing mesopores and macropores according to the mercury intrusion method and the gas adsorption method for determining the pore size distribution and porosity of solid materials in GB / T 21650.2. The adsorbed gas was nitrogen.

[0167] (7) Method for measuring metal ion content

[0168] The metal ion content in PPS was measured by inductively coupled plasma optical emission spectrometry (ICP-OES) according to the test method in GB / T 23942-2009. The plasma power was 1300 W, the cooling gas flow rate was 12 L / min, the auxiliary gas flow rate was 0.8 L / min, the atomizing gas flow rate was 0.8 L / min, and the additional gas flow rate was 0 L / min.

[0169] Example 1

[0170] Dehydration: In a 100 L reactor, 24.80 kg (250.0 mol) of NMP, 11.00 kg (100.0 mol) of a 51.0 wt% aqueous sodium sulfide solution, 7.74 kg (102.5 mol) of a 53.0 wt% liquid caustic, and 2.00 kg (6.45 mol) of a 40.0 wt% aqueous sodium pentanoate solution were added. After replacing the air in the reactor with nitrogen, the temperature was raised at a rate of 1.0°C / min under stirring at 130 rpm. When the temperature reached 198°C, the dehydration process was completed when the water content in the reaction system was close to 1.1 mol / mol of sulfur. At this time, 10.31 kg of solution was removed from the reactor (containing 98.0 wt% water and 2 wt% NMP). The hydrogen sulfide loss was calculated to be 1.5 mol, and at this time, the sulfur source in the reactor was 98.5 mol, and the water / sulfur molar ratio was 1.08.

[0171] Polymerization: When the above mixture in the reactor cooled to 170°C, 14.92 kg (101.0 mol) of PDCB and 15.02 kg of NMP were added, and the molar ratio of PDCB to total sulfur was 1.025, and the molar ratio of NMP to total sulfur was 4.0. The temperature was raised to 225°C in about 1.5 h, and the temperature was maintained for 2 h. By adding 1.5 mol of water per mol of sulfur through a high-pressure pump, the temperature was further raised (0.5°C / min) to 260°C, and at this time, the pressure stabilized at 16.5 kgf / cm2 When the conversion of p-dichlorobenzene in the system reached 99.0%, the slow release of pressure was started by adjusting the pressure relief valve, and the pressure was reduced to 14.5 kgf / cm2 at a uniform rate for 2 h, during which the temperature was kept constant. After the reaction was completed, the temperature was rapidly reduced to 100°C, and the resin was filtered through a 150-mesh screen, rinsed with NMP at 140°C at a weight ratio of 1:1, spun dry, rinsed with 0.2% dilute hydrochloric acid solution at a weight ratio of 1:1, spun dry, and the filtrate was collected. The filter cake was washed with deionized water at 85°C three times or more until the conductivity of the filtrate was below 100 μs / cm. The filter cake was dried to obtain the polyphenylene sulfide resin. 2 The temperature was kept constant during the reaction. After the reaction was completed, the temperature was rapidly reduced to 100°C, and the resin was filtered through a 150-mesh screen, rinsed with NMP at 140°C at a weight ratio of 1:1, spun dry, rinsed with 0.2% dilute hydrochloric acid solution at a weight ratio of 1:1, spun dry, and the filtrate was collected. The filter cake was washed with deionized water at 85°C three times or more until the conductivity of the filtrate was below 100 μs / cm. The filter cake was dried to obtain the polyphenylene sulfide resin.

[0172] The obtained resin was tested, and the data are shown in Table 1.

[0173] Comparative Example 1:

[0174] The same as in Example 1, except that the pressure was kept constant during the holding at 260°C after the addition of water until the final PPS reaction solution was obtained after 2.6 h. The same post-treatment was used after the reaction was completed.

[0175] The obtained resin was tested, and the data are shown in Table 1.

[0176] Examples 2-5:

[0177] Examples 2-5 were the same as Example 1, except that the slow release of pressure was started by adjusting the pressure relief valve when the conversion of p-dichlorobenzene in the system reached 98.5%, 98.7%, 99.5%, and 99.6%, respectively.

[0178] The obtained resin was tested, and the data are shown in Table 1.

[0179] Comparative Example 2:

[0180] The same as in Example 1, except that the slow release of pressure was started by adjusting the pressure relief valve when the conversion of p-dichlorobenzene in the system reached 99.9%.

[0181] The obtained resin was tested, and the data are shown in Table 1.

[0182] Examples 6-9:

[0183] Examples 6-9 were the same as Example 1, except that the slow release of pressure was started by adjusting the pressure relief valve, and the pressure was reduced to 13.5 kgf / cm2, 14 kgf / cm2, 15 kgf / cm2, and 15.5 kgf / cm2 at a uniform rate for 2 h, respectively. 2 2 2 2

[0184] The obtained resin was tested, and the data are shown in Table 2. ​​​​

[0185] Examples 10-13:

[0186] Examples 10-13 are the same as Example 1, except that the pressure reducing valve is adjusted to slowly release the pressure, reducing it to 14.5 kgf / cm³ at a constant rate over 1 hour, 1.5 hours, 2.5 hours, and 3 hours respectively. 2 .

[0187] The obtained resin was tested, and the data are shown in Table 3.

[0188] Example 14:

[0189] The process is basically the same as in Example 1, except that the polymerization step involves adding 1.5 mol / mol sulfur in water using a high-pressure pump and continuing to heat the mixture (at a rate of 0.5°C / min) to 260°C and holding it therewhile, at which point the pressure stabilizes at 17 kgf / cm³. 2 When the conversion rate of dichlorobenzene in the system reached 99.4%, the pressure reducing valve was adjusted to slowly release the pressure, reducing it to 15 kgf / cm³ over 1.5 hours. 2 The temperature was kept constant during this period. The post-processing procedure was the same.

[0190] The obtained resin was tested, and the data are shown in Table 3.

[0191] Example 15:

[0192] The process is basically the same as in Example 1, except that the polymerization step involves adding 1.5 mol / mol sulfur in water using a high-pressure pump and continuing to heat the mixture (at a rate of 0.5°C / min) to 260°C and holding it at that temperature, where the pressure stabilizes at 16 kgf / cm³. 2 When the conversion rate of dichlorobenzene in the system reached 99.8%, the pressure reducing valve was adjusted to slowly release the pressure, reducing it to 13 kgf / cm³ over 2.5 hours. 2 The temperature was kept constant during this period. The post-processing procedure was the same.

[0193] The obtained resin was tested, and the data are shown in Table 3.

[0194] Example for reference:

[0195] PPS resin was obtained according to the method of Example 1 of CN106633062A, wherein the chlorine content was 750ppm, the molecular weight was 45800, the resin surface was smooth, and there was no obvious rough structure.

[0196] Table 1

[0197] Table 2

[0198] Table 3

[0199] As can be seen from the above examples and comparative examples, the present application can obtain low molecular weight polyphenylene sulfide while reducing the chloride ion content.

[0200] In addition, as can be seen from the comparison of the above examples and comparative examples, the preparation method provided by the present application can obtain polyphenylene sulfide products meeting the expectations of the present application.

[0201] It should be noted that although the technical solutions of the present application are described with specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0202] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles, practical applications, or technical improvements in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A low-chlorine content polyphenylene sulfide resin characterized in that, The polyphenylene sulfide resin has a weight average molecular weight of 55,000 or less and a chlorine content of 900 ppm or less. And, the polyphenylene sulfide resin has a surface rough structure, and has a specific surface area of 70.00 m 2 / g or more according to the BET test method.

2. The polyphenylene sulfide resin according to claim 1, characterized by, The polyphenylene sulfide has a weight average molecular weight of 35,000 to 50,000 and a chlorine content of 500 to 800 ppm.

3. The polyphenylene sulfide resin according to claim 1 or 2, characterized by, The polyphenylene sulfide resin also satisfies one or more of the following conditions: i. a crystallization temperature of 240°C or higher; ii. the rough structure is a microporous structure, the micropores having a pore volume of 0.32 to 0.40 cm3 / g 3 / g; iii. a Na ion content of 15 to 35 ppm as measured by ICP.

4. The polyphenylene sulfide resin according to any one of claims 1 to 3, characterized by, The components in the molecular chain of the polyphenylene sulfide resin are derived from a sulfur source and p-dichlorobenzene as reactants.

5. A process for the preparation of a low-chlorine content polyphenylene sulfide resin, characterized in that, The method includes the following steps: a first polymerization step, a second polymerization step, and a post-treatment step, wherein, in the first polymerization step, a first polymerization of a sulfur source and p-dichlorobenzene is performed, in the second polymerization step, a second polymerization is performed by reducing the pressure based on the first polymerization, in the post-treatment step, a cleaning step of the polyphenylene sulfide resin obtained in the second polymerization step is performed.

6. The method of claim 5, wherein, The step of reducing the pressure to perform the second polymerization is performed when the conversion rate of p-dichlorobenzene in the first polymerization is 98.5% to 99.6%.

7. The method according to claim 5 or 6, characterized in that, In the step of reducing the pressure, the pressure is reduced to the end point of the reduced pressure in 1 to 3 hours.

8. The method according to any one of claims 5 to 7, characterized in that, the second polymerization step is performed under reduced pressure while keeping the temperature of the reaction system substantially constant; the reduced pressure in the second polymerization step results in a decrease in the pressure in the reaction system of 1 to 3 kgf / cm 2 .

9. The method according to any one of claims 5 to 8, characterized in that, The post-treatment step includes one or more of an acid washing, a water washing, or a combination thereof of the polyphenylene sulfide resin obtained in the second polymerization step under heating.

10. A composite material, characterized by, The composite material includes the polyphenylene sulfide resin according to any one of claims 1 to 4 and a filler including a fiber.

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