Manufacturing method of highly reactive polyphenylene sulfide resin and its products

Abstract

The present invention discloses a method for producing highly active polyphenylene sulfide by controlling the content of water in the polymerization process, and the produced highly active polyphenylene sulfide resin. The production method includes using sodium hydrosulfide and paradichlorobenzene as raw materials, using N-methyl-2-pyrrolidone as a solvent, carrying out a polycondensation reaction until the conversion rate of paradichlorobenzene reaches 97% or more, adding deionized water, lowering the temperature in the reaction vessel to 250-260°C, keeping the temperature for 1-3 hours to react, and then cooling and carrying out post-treatment. The molar amount of deionized water added for 1.0 mol of sodium hydrosulfide is 1.0-2.5 mol. The present invention discloses a method for producing highly active polyphenylene sulfide, which can be realized simultaneously in the polymerization process of PPS, that is, there is no need to add an end-capping agent that affects the molecular weight and thermal stability of the finally produced PPS, and there is no need to perform an activation treatment after the production of PPS resin, which adds to the process flow and production costs.

Description

[Technical field]

[0001] The present invention relates to the technical field of polyphenylene sulfide, and in particular to a method for producing a highly reactive polyphenylene sulfide resin by controlling the water content in the polymerization process, and the highly reactive polyphenylene sulfide produced. [Background technology]

[0002] Polyphenylene sulfide is the sixth engineering plastic, which has the advantages of high mechanical strength, high long-term use temperature, chemical resistance, excellent electrical properties, high flame retardancy, etc., and is widely used in the fields of environmental protection, automotive electronics, machinery and space. However, its molecular structure is an alternating arrangement of benzene rings and sulfur, with few activating groups, and low interaction and reactivity with silane coupling agents. In order to improve the toughness and impact resistance of polyphenylene sulfide, researchers have typically introduced activating groups, most commonly carboxyl groups, to its end groups. Resins containing carboxyl groups can greatly improve the resin activity, and can be physically and chemically crosslinked with silane coupling agents, glass fibers or other fillers in the extrusion and modification of the resin, improving compatibility, toughness and impact resistance.

[0003] In order to increase the carboxyl group content at the end of the PPS resin, in the patent document JP6682793B2, 0.2-0.35 mol of parachlorobenzoic acid (per mol of sulfur source) is introduced as an auxiliary during the polymerization reaction to synthesize a polyphenylene sulfide resin, and the carboxyl group content at the end of the polyphenylene sulfide resin is 500 μmol / g or more. However, the end-capping agent is generally a monofunctional molecule, and introducing a large amount of it will cause premature end-capping of PPS, which will affect the increase in molecular weight. Therefore, the number average molecular weight of the polyphenylene sulfide resin synthesized in the example of the patent document is only 5000-6000.

[0004] The Chinese patent document with publication number CN108164702 A discloses that a polyphenylene sulfide resin is obtained by polycondensation reaction using sulfur-containing compounds, alkaline substances and paradichlorobenzene as raw materials and fatty acids as polycondensation assistants, and then by purification treatment to obtain a primary product of polyphenylene sulfide resin, which is then reacted with an end group regulator containing a hydroxy aromatic thiol compound and 4-thiophenyl-benzenethiol at high temperature to obtain a polyphenylene sulfide resin, which has a thermal stability index of 0.95 or more, a reactivity of 2.5 or more, and a melting temperature of 230-260°C. Although this method achieves both thermal stability and reactivity of the resin, the reactivity still cannot meet the requirements.

[0005] Therefore, in order to achieve high reactivity of PPS having active carboxyl end groups, it is generally necessary to add an additional end-capping agent, which increases costs and the reaction conversion rate does not reach 100%, which affects the recovery of solvents in post-treatment. In addition, the stability of the carboxyl end groups formed by adding an auxiliary such as parachlorobenzoic acid is not higher than that of the end groups themselves, resulting in reduced thermal stability. Summary of the Invention

[0006] In response to the above problems in the prior art, the present invention discloses a method for producing a highly reactive polyphenylene sulfide resin, which can be realized simultaneously during the polymerization process of PPS, i.e., there is no need to add an end-capping agent that would affect the molecular weight and thermal stability of the final PPS produced, and there is also no need to carry out a chain extension treatment after the production of the PPS resin, which adds to the process flow and production costs.

[0007] The technical solutions are specifically as follows: A method for producing a highly reactive polyphenylene sulfide resin, comprising: using sodium hydrosulfide and paradichlorobenzene as raw materials; using N-methyl-2-pyrrolidone as a solvent; carrying out a polycondensation reaction until the conversion rate of paradichlorobenzene reaches 97% or more; adding deionized water; lowering the temperature in the reactor to 250-260°C; keeping the temperature for 1-3 hours to carry out the reaction; and then cooling and carrying out post-treatment; The molar amount of deionized water added is 1.0 to 2.5 mol for 1.0 mol of total sulfur content in the system.

[0008] The present invention discloses a method for producing highly active polyphenylene sulfide by controlling the water content in the polymerization process. After numerous tests, the inventors have found that after the growth of PPS molecular chains basically stops (the conversion rate of dichlorobenzene reaches 97% or more), if a certain amount of water is continued to be added, NMP (N-methyl-2-pyrrolidone) will hydrolyze in an alkaline environment to produce SMAB, and at a temperature 10-20°C higher than the temperature at which PPS resin precipitates (250-260°C), SMAB will continue to react with the chlorine end group of PPS, and continue to react for 1-3 hours to synthesize PPS resin with a large amount of carboxyl end groups. The specific reaction formula is as shown in the following formula: JPEG2025511650000001.jpg30117

[0009] As a result of the test, it was found that there are several points in this manufacturing method. First, the timing of adding water. Water needs to be added after the growth of the PPS molecular chain has basically stopped. As a result of the test, it was found that adding water in advance, for example at the polymerization stage, is disadvantageous to the synthesis of PPS resin with a large amount of carboxyl end groups. Even if water is added after the end of polymerization, if the conversion rate of paradichlorobenzene does not reach 97% or more, the molecular weight of the PPS resin will stop growing in advance, will not reach the ideal molecular weight, and will result in a loss of the raw material PDCB (paradichlorobenzene). Second, the molar ratio of the water to be added to the sulfur source in the system. Water is a poor solvent for PPS, so the test results show that if too much water is added, the solubility of PPS in NMP-H2O will decrease, the reactivity of the end group will be poor, and the activity will be significantly lower than that of the 1.0-2.5 mol / mol sulfur source, which will cause a large amount of NMP loss, and the pressure in the kettle will be too high and the risk of polymerization will increase if a large amount of water is added; if too little water is added, the carboxyl end group generated will be insufficient and the activity requirements cannot be met, so the amount of water added is controlled to 1.0-2.5 mol / mol sulfur source. Thirdly, the temperature in the reaction kettle is controlled to be lowered to 250-260°C after adding water. The test results show that if the temperature is lowered too much, it may cause precipitation of PPS resin, and the reactivity of the end group will be insufficient, and if the temperature is not lowered enough, excessive side reactions may occur, which may cause chain scission and risk of depolymerization of PPS.

[0010] Preferably, the polycondensation reaction is carried out until the conversion rate of paradichlorobenzene reaches 99% or more, and then deionized water is added. Test results show that by controlling the conversion rate of dichlorobenzene to 99% or more, a highly reactive PPS resin with a higher molecular weight can be produced.

[0011] Preferably, the deionized water to be added should be preheated to 80-90° C., thereby avoiding a sudden drop in temperature in the reaction vessel after addition.

[0012] The deionized water to be added is preferably 1.5 to 2.5 mol / mol of the sulfur source, more preferably 1.5 to 2.0 mol / mol of the sulfur source, and even more preferably 2.0 mol / mol of the sulfur source.

[0013] With the molar amount of deionized water being constantly optimized, the PPS resin produced has higher reactivity, excellent thermal stability and high molecular weight.

[0014] Preferably, after adding the deionized water, the temperature inside the reaction vessel is lowered to 250 to 260° C. at a cooling rate of 1.0 to 3.0° C. / min.

[0015] Test results show that the control of the cooling speed is also important, if the temperature drop is too slow, NMP will form by-products under high temperature due to the action of water, and the longer the time of PPS chain exchange side reaction, the more likely it is that PPS molecular chains will be cut and depolymerized. During the process of adding water, some water will evaporate, causing the pressure inside the reactor to rise, and the rapid drop in temperature means that the faster the water is added, the faster the pressure will rise, which will cause too strong an impact on the reactor body and the sealing system of the reactor, making it easy to cause damage to the equipment.

[0016] More preferably, the temperature inside the reaction vessel is lowered to 250 to 260° C. at a cooling rate of 1.0 to 2.0° C. / min.

[0017] The method for producing highly active polyphenylene sulfide by controlling the water content in the polymerization process disclosed in the present invention specifically includes the following steps:

[0018] (1) An aqueous solution of sodium hydrosulfide, an aqueous solution of alkali metal hydroxide, optionally added auxiliary agents and N-methyl-2-pyrrolidone are charged into a reaction vessel, and the vessel is heated to 180-200°C under the protection of a nitrogen atmosphere to dehydrate, and then cooled to 160-180°C.

[0019] (2) Paradichlorobenzene and N-methyl-2-pyrrolidone are added to a reaction vessel, and the temperature is first raised to 220-240°C to carry out a polymerization reaction until the conversion rate of paradichlorobenzene reaches 85% or more, and then the temperature is raised to 260-280°C to carry out a polymerization reaction until the conversion rate of paradichlorobenzene reaches 97% or more, preferably until the conversion rate of paradichlorobenzene reaches 99% or more.

[0020] (3) Add deionized water to the reaction vessel, and lower the temperature inside the reaction vessel to 250-260°C. Keep the temperature for 1-3 hours to react, then lower the temperature to 100-150°C to obtain a PPS reaction liquid, which is then post-treated to obtain highly active polyphenylene sulfide.

[0021] In step (1), The concentration of the aqueous sodium hydrosulfide solution is 40 to 55 wt %, and the concentration of the aqueous alkali metal hydroxide solution is 45 to 55 wt %, The molar amount of alkali metal hydroxide is 1.0 to 1.4 mol per 1.0 mol of NaHS in the sodium hydrosulfide aqueous solution. Preferably, said aqueous alkali metal hydroxide solution is selected from aqueous sodium hydroxide solution.

[0022] The selectively addable auxiliary is selected from C5-C6 fatty acid salts, and is added in the form of a 35-45 wt% aqueous solution, and the molar amount of the auxiliary added is 0.1-0.5 mol per 1.0 mol of NaHS in the sodium hydrosulfide aqueous solution; Preferably, the C5-C6 fatty acid salt is selected from one or more of sodium 2-ethylbutyrate, sodium valerate, sodium isovalerate, and sodium hexanoate.

[0023] The molar amount of N-methyl-2-pyrrolidone to be added per 1.0 mol of NaHS in the aqueous sodium hydrosulfide solution is 2.4 to 3.0 mol.

[0024] Preferably, in step (1), The temperature is increased to 180-200°C at a rate of 0.7-1.5°C / min to dehydrate the material. The dehydration is carried out until the molar ratio of water / sulfur content in the system reaches 0.9 to 1.2:1.

[0025] In step (2), For every 1.0 mol of total sulfur content in the system, the molar amount of paradichlorobenzene is 0.99-1.05 mol. After adding N-methyl-2-pyrrolidone, the molar amount of N-methyl-2-pyrrolidone in the system is 3.5-4.5 mol for each 1.0 mol of total sulfur content in the system; Preferably, First, the temperature is increased to 220-240° C. at a rate of 0.6-1.5° C. / min to carry out a polymerization reaction, and then the temperature is increased to 260-280° C. at a rate of 0.5-1.0° C. / min to carry out a polymerization reaction.

[0026] In step (3), After the warming, the particle size of the produced PPS particles can be controlled by controlling the temperature after cooling. The temperature is preferably controlled to be lowered to 110 to 150°C.

[0027] The post-treatment includes filtering, washing and drying. The filtering step includes filtering the resulting PPS reaction solution through a 150 mesh screen.

[0028] The washing includes washing with NMP heated to 100 to 150°C in an amount equal to the mass of the filter cake obtained by filtration, dehydrating, further washing with a dilute hydrochloric acid solution in an amount equal to the mass of the filter cake, dehydrating, and finally washing with deionized water at 70 to 100°C multiple times until chloride ions reach a standard level.

[0029] The filtrates produced during the washing process are combined and collected, and are first separated from the auxiliary by azeotropic distillation, then rectified to remove water, and finally distilled under reduced pressure to recover the solvent NMP, and the residue produced by distillation can be incinerated.

[0030] In step (3), Preferably, the molar amount of deionized water added is 1.5 to 2.5 mol per 1.0 mol of the total sulfur content in the system; The temperature inside the reactor is lowered to 250-260°C at a cooling rate of 1.0-3.0°C / min, and then the reaction is carried out while keeping the temperature at 250-260°C for 1-3 hours.

[0031] The present invention further discloses a highly reactive polyphenylene sulfide resin produced by the above method, wherein the highly reactive polyphenylene sulfide resin has a carboxyl group content of ≧100 mmol / kg, and preferably has a carboxyl group content of 150-250 mmol / kg.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The present invention discloses a method for producing highly reactive polyphenylene sulfide resin, which can be realized simultaneously during the polymerization process of PPS, i.e., there is no need to add an end-capping agent that would affect the molecular weight and thermal stability of the final PPS produced, and there is also no need to perform chain extension treatment after the production of PPS resin, which adds to the process flow and production costs.

[0034] The highly reactive polyphenylene sulfide resin produced by the present invention has a carboxyl group content of ≧100 mmol / kg, more preferably 150 to 250 mmol / kg, and at the same time, the highly reactive polyphenylene sulfide resin has both a high molecular weight and high thermal stability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail with reference to the following embodiments and drawings. However, it should be understood that the specific embodiments described herein are merely for the purpose of illustrating the present invention, and are not intended to limit the present invention.

[0036] The properties of the PPS resins produced in the examples and comparative examples of the present invention were tested by the following methods.

[0037] Carboxyl group content test: The PPS powder is melted in a hot press at 315 ° C and compressed into tablets to produce an amorphous film. The infrared spectrum is measured using a micro infrared spectrophotometer (Thermo Nicolet iN10, Thermo Scientific) using the transmission method. The 1704 cm -1 , 3065cm -1 The peak height of each absorption peak is calculated, and the corrected height is H 3065 , H 1704 and the formula C=(H 1704 / H 3065 *4) The carboxyl group content is estimated by / 40 / 108.161*1000000.

[0038] Reactivity test: Take 100 parts by mass of PPS resin, add 0.8 parts by mass of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, mix uniformly, and then measure the melt viscosity according to the above melt viscosity measurement method. The degree of viscosity increase is calculated from the ratio of the melt viscosity after the addition of the coupling agent to the melt viscosity before the addition of the coupling agent, and the greater the degree of viscosity increase, the higher the reactivity.

[0039] Molecular weight test: The weight average molecular weight (Mw) of the polymer was measured using high-temperature gel permeation chromatography (GPC), and the weight average molecular weight was calculated as a polystyrene equivalent value. Solvent: 1-chloronaphthalene, temperature: 210°C, detector: UV detector (360 nm).

[0040] Thermal stability: According to the melt viscosity measurement method, the melt viscosity of the polymer sample at 310℃ is measured, and the melt viscosity after heating and keeping for 5 minutes and 30 minutes is measured, and the thermal stability is calculated from the ratio of the two. Specifically, it is as follows.

[0041] The polymer sample was held at 310°C for 5 min and then subjected to a shear rate of 1216 s -1The melt viscosity (MV1) was measured at a shear rate of 1216 s for the same polymer sample after holding at 310°C for 30 min. -1 The melt viscosity (MV2) was measured at 100° C. Then, based on these measurements, a ratio (MV2 / MV1) called the thermal stability index was calculated, with a higher ratio indicating a higher thermal stability of the polymer.

[0042] Melting temperature (T m ) Test: The melting point of the PPS resin is measured using a differential scanning calorimeter (DSC), and 2 to 3 mg of PPS base resin is heated to 340°C at a heating rate of 10°C / min.

[0043] Example 1 Dehydration: 24.80 kg (250.0 mol) of NMP, 11.00 kg (100.0 mol) of 51.0 wt% aqueous sodium hydrosulfide solution, 7.74 kg (102.5 mol) of 53.0 wt% aqueous sodium hydroxide solution, and 2.00 kg (6.45 mol) of 40.0 wt% aqueous sodium valerate solution are added to a 100 L reactor, and the air in the reactor is replaced with nitrogen. The temperature is increased at a rate of 1.0 ° C / min with a stirring speed of 130 rpm. When the temperature rises to 195 ° C and the water content in the reaction system becomes less than 1.1 mol / mol sulfur, the dehydration process is terminated, and 10.18 kg of solution is removed from the reactor at this time (water content 98.0 wt%, 2.0 wt% NMP remains). Through testing, the loss of hydrogen sulfide was calculated to be 1.5 mol, the sulfur source in the kettle was 98.5 mol, and the water / sulfur molar ratio was 1.08.

[0044] Polymerization: When the mixture is cooled to 170 ℃, add 14.85kg (100.5mol) PDCB and 15.02kg NMP to the reactor, the molar ratio of PDCB / total sulfur is 1.02, and the molar ratio of NMP / total sulfur is 4. Heat to 225 ℃ at a rate of 0.8 ℃ / min, keep warm for 2 hours, then heat to 270 ℃ at a rate of 0.5 ℃ / min and keep warm for 2 hours, detect that the PDCB conversion rate reaches more than 99%, at this time the molecular weight of the resin is almost not growing, add 1.5mol / mol sulfur source water preheated to 80 ℃ by high pressure pump, reduce the temperature to 255 ℃ at a rate of 2.0 ℃ / min, and continue to react for 2 hours. After the reaction is completed, cool quickly to 110 ℃, filter the resin through a 150 mesh screen, wash the resin with NMP, 0.3% dilute hydrochloric acid, and water, respectively, wash until the chloride ion content reaches the standard, and then dry. The filtrates produced during the washing process are combined and collected, and then first separated from the sodium valerate by azeotropic distillation, then rectified to remove water, and finally distilled under reduced pressure to recover the solvent NMP, and the residue produced by distillation can be incinerated.

[0045] As a result of the test, the melting temperature of the PPS resin produced in this example was 298.6°C, and M w The molecular weight is 50470, and other data are as shown in Table 1 below.

[0046] Example 2 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after keeping at 270°C for 2 hours, add 1.5 mol / mol sulfur source water by high-pressure pump, lower the temperature to 252°C at a rate of 2.0°C / min, and continue reacting for 1.5 hours.

[0047] As a result of the test, the melting temperature of the PPS resin produced in this example was 299.3° C., the Mw was 51630, and other data are as shown in Table 1 below.

[0048] Example 3 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after keeping at 270℃ for 2 hours, add 1 mol / mol sulfur source water by high-pressure pump, lower the temperature to 258℃ at a rate of 2.0℃ / min, and continue reacting for 1 hour.

[0049] As a result of the test, the melting temperature of the PPS resin produced in this example was 298.7° C., the Mw was 49870, and other data are as shown in Table 1 below.

[0050] Example 4 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after keeping at 270℃ for 2 hours, add 2mol / mol sulfur source water by high-pressure pump, lower the temperature to 255℃ at a rate of 2.0℃ / min, and continue reacting for 2 hours.

[0051] As a result of the test, the melting temperature of the PPS resin produced in this example was 298.9° C., the Mw was 49760, and other data are as shown in Table 1 below.

[0052] Example 5 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after keeping at 270℃ for 2 hours, add 2.5 mol / mol sulfur source water by high-pressure pump, lower the temperature to 250℃ at a rate of 2.0℃ / min, and continue reacting for 3 hours.

[0053] As a result of the test, the melting temperature of the PPS resin produced in this example was 299.1° C., the Mw was 48430, and other data are as shown in Table 1 below.

[0054] Example 6 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after adding 1.5 mol / mol sulfur source water by high pressure pump, the temperature is lowered to 255°C at a rate of 1.0°C / min, and the reaction is continued for 2 hours.

[0055] As a result of the test, the melting temperature of the PPS resin produced in this example was 298.5° C., the Mw was 48560, and other data are as shown in Table 1 below.

[0056] Example 7 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after adding 1.5 mol / mol sulfur source water by high pressure pump, the temperature is lowered to 260°C at a rate of 3.0°C / min, and the reaction is continued for 1 hour.

[0057] As a result of the test, the melting temperature of the PPS resin produced in this example was 297.9° C., the Mw was 46760, and other data are as shown in Table 1 below.

[0058] Example 8 The dehydration process was exactly the same as in Example 1. Polymerization: In the polymerization stage, the raw materials are added to the reactor in the same ratio as in Example 1. The temperature is raised to 225°C at a rate of 0.6°C / min, kept at the temperature for 2 hours, then raised to 270°C at a rate of 0.5°C / min, kept at the temperature for 1.5 hours, and when it is detected that the conversion rate of PDCB reaches 97% or more, the water of 1.5mol / mol sulfur source preheated to 80°C is added by high-pressure pump, the temperature is lowered to 255°C at a rate of 2.0°C / min, and the reaction is continued for 2 hours.

[0059] As a result of the test, the melting temperature of the PPS resin produced in this example was 297.5° C., the Mw was 35680, and other data are as shown in Table 1 below.

[0060] Comparative Example 1 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after keeping at 270°C for 2 hours, water is not added, and the temperature is only lowered to 255°C, and the reaction is continued for 2 hours.

[0061] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 299.4° C., the Mw was 43260, and other data are as shown in Table 1 below.

[0062] Comparative Example 2 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after adding 1.5 mol / mol sulfur source water by high pressure pump, the temperature is lowered to 240°C at a rate of 2.0°C / min, and the reaction is continued for 1.5 hours.

[0063] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 299.2° C., the Mw was 46640, and other data are as shown in Table 1 below.

[0064] Comparative Example 3 The dehydration process was exactly the same as in Example 1. Polymerization: In the polymerization stage, the raw materials are added to the reactor in the same ratio as in Example 1. The temperature is raised to 225°C at a rate of 1.5°C / min, kept at the temperature for 2 hours, and the water of 1.5mol / mol sulfur source preheated to 80°C by high pressure pump is added, and the temperature is raised to 270°C at a rate of 0.5°C / min, kept at the temperature for 2 hours, and the conversion rate of PDCB reaches 99% or more. After the temperature is lowered to 253°C at a rate of 3.0°C / min, and the reaction is continued for 1.5 hours.

[0065] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 298.5° C., the Mw was 47680, and other data are as shown in Table 1 below.

[0066] Comparative Example 4 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, except that after adding 1.5 mol / mol sulfur source water by high pressure pump, the temperature is lowered to 255°C at a rate of 0.5°C / min, and the reaction is continued for 2 hours.

[0067] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 296.5° C., the Mw was 37620, and other data are as shown in Table 1 below.

[0068] Comparative Example 5 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process in the polymerization stage is basically the same as that in Example 1, with the only difference being that water of 0.5 mol / mol sulfur source is added by a high pressure pump.

[0069] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 299.5° C., the Mw was 51380, and other data are as shown in Table 1 below.

[0070] Comparative Example 6 The dehydration process was exactly the same as in Example 1. Polymerization: The preparation process of the polymerization stage is basically the same as that of Example 1, the only difference being that water of 3.0 mol / mol sulfur source is added by a high pressure pump.

[0071] As a result of the test, the melting temperature of the PPS resin produced in this comparative example was 297.8° C., the Mw was 48610, and other data are as shown in Table 1 below.

[0072] Table 1 JPEG2025511650000002.jpg176141

[0073] Here, as can be seen from the results of Comparative Examples 2 and 3, the reaction temperature after the addition of deionized water and the timing of adding deionized water all have a significant effect on the carboxyl group content and reactivity. As can be seen from the results of Comparative Example 6, when 3.0 mol / mol sulfur source water was added, the carboxyl group content, thermal stability, and reactivity all decreased, and especially the thermal stability was obviously decreased, compared with when 1.5 mol / mol (Example 1) or 2.0 mol / mol (Example 4) sulfur source water was added.

Claims

1. A method for producing a highly reactive polyphenylene sulfide resin using sodium hydrosulfide and paradichlorobenzene as raw materials and N-methyl-2-pyrrolidone as a solvent, comprising the steps of: Carry out polycondensation reaction until the conversion rate of paradichlorobenzene reaches 97% or more, add deionized water, and lower the temperature in the reactor to 250-260°C. Keep the temperature for 1-3 hours to carry out the reaction, then cool and carry out post-treatment. A method for producing a highly reactive polyphenylene sulfide resin, characterized in that the molar amount of deionized water added is 1.0 to 2.5 mol per 1.0 mol of total sulfur content in the system.

2. The method for producing the highly reactive polyphenylene sulfide resin according to claim 1, characterized in that the polycondensation reaction is carried out until the conversion rate of paradichlorobenzene is 99% or more, and then deionized water is added to lower the temperature in the reaction vessel to 250-260°C at a cooling rate of 1.0-3.0°C / min.

3. in particular, Step (1): adding sodium hydrosulfide aqueous solution, alkali metal hydroxide aqueous solution, optional auxiliary and N-methyl-2-pyrrolidone into a reactor, and heating to 180-200°C under nitrogen atmosphere to dehydrate, and then cooling to 160-180°C; (2) adding paradichlorobenzene and N-methyl-2-pyrrolidone to a reaction vessel, first raising the temperature to 220-240° C. to carry out a polymerization reaction, and then carrying out the reaction until the conversion rate of paradichlorobenzene reaches 85% or more, and then raising the temperature to 260-280° C. to carry out a polymerization reaction; and (3) adding deionized water to the reaction vessel, lowering the temperature in the reaction vessel to 250-260°C, and then lowering the temperature to 100-150°C after keeping the temperature for 1-3 hours to react, to obtain a PPS reaction liquid, which is then subjected to post-treatment to obtain a highly reactive polyphenylene sulfide.

4. In step (1), The concentration of the sodium hydrosulfide aqueous solution is 40 to 55 wt %, and the concentration of the alkali metal hydroxide aqueous solution is 45 to 55 wt %, The molar amount of the alkali metal hydroxide is 1.0 to 1.4 mol per 1.0 mol of NaHS in the aqueous sodium hydrosulfide solution. the selectively addable auxiliary is selected from C5-C6 fatty acid salts, and is added in the form of a 35-45 wt % aqueous solution, and the molar amount of the auxiliary added is 0.1-0.5 mol per 1.0 mol of NaHS in the aqueous sodium hydrosulfide solution; 4. The method for producing a highly reactive polyphenylene sulfide resin according to claim 3, wherein the molar amount of N-methyl-2-pyrrolidone added is 2.4 to 3.0 mol per 1.0 mol of NaHS in the aqueous sodium hydrosulfide solution.

5. In step (1), The temperature is increased to 180-200°C at a rate of 0.7-1.5°C / min to dehydrate the mixture. The method for producing a highly reactive polyphenylene sulfide resin according to claim 3, wherein the dehydration is carried out until the molar ratio of water / sulfur content in the system becomes 0.9 to 1.2:

1.

6. In step (2), The molar amount of paradichlorobenzene is 0.99 to 1.05 mol relative to the total sulfur content of 1.0 mol in the system. After adding N-methyl-2-pyrrolidone, the molar amount of N-methyl-2-pyrrolidone in the system is 3.5-4.5 mol for every 1.0 mol of total sulfur content in the system; The method for producing the highly reactive polyphenylene sulfide resin according to claim 3, characterized in that the polymerization reaction is carried out by first increasing the temperature to 220 to 240°C at a temperature increase rate of 0.6 to 1.5°C / min, and then increasing the temperature to 260 to 280°C at a temperature increase rate of 0.5 to 1.0°C / min.

7. In step (3), The molar amount of deionized water added is 1.0 to 2.5 mol for every 1.0 mol of total sulfur content in the system. The method for producing the highly reactive polyphenylene sulfide resin according to claim 3, characterized in that the temperature in the reaction vessel is lowered to 250-260°C at a cooling rate of 1.0-3.0°C / min, and then the reaction is carried out by keeping the temperature for 1-3 hours.

8. In step (3), 4. The method for producing a highly reactive polyphenylene sulfide resin according to claim 3, wherein the post-treatment includes filtering, washing and drying.

9. A highly reactive polyphenylene sulfide resin produced by the method according to any one of claims 1 to 8, characterized in that the highly reactive polyphenylene sulfide resin has a carboxyl group content of ≧100 mmol / kg.

10. The highly reactive polyphenylene sulfide resin according to claim 9, wherein the highly reactive polyphenylene sulfide resin has a carboxyl group content of 150 to 250 mmol / kg.

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