Method and reaction apparatus for producing polyarylene sulfide resin

Abstract

This disclosure relates to a method for efficiently monitoring the concentration of raw materials in a reaction solution in a short time during a polymerization reaction for producing polyarylene sulfide resins. [Solution] A method for producing a polyarylene sulfide resin, comprising: forming a reaction solution containing an organic polar solvent, a polyhalo-aromatic compound, and a sulfur source in a plurality of interconnected reaction vessels such that a gas phase remains in each of the reaction vessels; and forming a polyarylene sulfide resin by polymerization; during the polymerization reaction, measuring the concentration of the polyhalo-aromatic compound, the sulfur compound, or both in the gas phase in the reaction vessel, or in the condensate formed by the condensation of the gas phase, by spectroscopic analysis; and determining an estimated value of the concentration of the polyhalo-aromatic compound, the sulfur source, or both in the reaction solution from the concentrations.

Description

Technical Field

[0001] The present disclosure relates to a method for producing a polyarylene sulfide resin and a reaction apparatus.

Background Art

[0002] A polyarylene sulfide resin (hereinafter sometimes referred to as "PAS resin") may be produced by a method in which an organic amide solvent, a sulfur source, and a dihaloaromatic compound are supplied to a reaction vessel, and the sulfur source and the dihaloaromatic compound are continuously polymerized in the reaction vessel (for example, Patent Document 1).

[0003] In the continuous polymerization reaction of a PAS resin, in order to obtain a PAS resin with stable quality, it is often necessary to strictly control the molar ratio of raw materials in the reaction solution. Therefore, conventionally, the molar ratio of raw materials during the polymerization reaction and the like have sometimes been monitored by analyzing a sample collected from the slurry-like reaction solution.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The polymerization reaction for obtaining a PAS resin is generally carried out under high-temperature and high-pressure conditions, and the reaction solution is a strongly alkaline slurry. Therefore, it is not easy to obtain a sample for analysis from the reaction solution during the polymerization reaction, and in order to analyze the strongly alkaline reaction solution, it is necessary to apply an analysis method that requires a relatively long time. Therefore, it is difficult to quickly adjust the conditions of the polymerization reaction based on the analysis results, and there is a limit to the stabilization of the quality of the PAS resin.

[0006] One aspect of this disclosure relates to a novel method for producing polyarylene sulfide resins of stable quality. [Means for solving the problem]

[0007] This disclosure includes the following: [1] The reaction solution containing an organic polar solvent, a polyhalo-aromatic compound, and a sulfur source is formed in a plurality of interconnected reaction vessels, such that a gas phase remains in each of the reaction vessels. A polyarylene sulfide resin is formed by a polymerization reaction in the aforementioned reaction solution, The process involves removing the reaction solution containing the polyarylene sulfide resin from one or more of the reaction vessels, During the polymerization reaction, the concentrations of the polyhalo-aromatic compound, sulfur compound, or both in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, are measured by spectroscopic analysis. From the measured concentrations, estimates of the concentrations of the polyhalo-aromatic compound, the sulfur source, or both in the reaction solution, or estimates of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution are obtained. including, A method for producing polyarylene sulfide resin. [2] The method according to [1], further comprising adjusting the conditions of the polymerization reaction based on the estimated values. [3] The conditions for the polymerization reaction to be adjusted include one or more selected from the group consisting of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution, the timing at which the reaction solution containing the polyarylene sulfide resin is to be withdrawn from one or more reaction vessels, the amount of the polyhalo-aromatic compound contained in the reaction solution, the amount of the sulfur source contained in the reaction solution, the time of the polymerization reaction, the temperature of the reaction solution, and the pressure of the gas phase. The method described in [2]. [4] Adjusting the conditions of the polymerization reaction, From the estimated concentrations of the polyhalo-aromatic compound and the sulfur source in the reaction solution, an estimated value of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution is calculated. The amounts of the polyhalo-aromatic compound, the sulfur source, or both of these in the reaction solution are adjusted so that the estimated value of the molar ratio approaches the target value of the molar ratio. The method described in [2], including the method described in [2]. [5] Adjusting the conditions of the polymerization reaction, The method further includes calculating an estimated value of the reaction rate of the polyhalo-aromatic compound from the estimated value of the concentration of the polyhalo-aromatic compound in the reaction solution, The method according to [4], wherein, after the estimated value of the reaction rate becomes equal to or greater than the target value of the reaction rate, the amount of the polyhalo-aromatic compound, the sulfur source, or both thereof in the reaction solution is adjusted once or more so that the estimated value of the molar ratio approaches the target value of the molar ratio. [6] Adjusting the conditions of the polymerization reaction, From the estimated concentration of the polyhalo-aromatic compound in the reaction solution, an estimated value of the reaction rate of the polyhalo-aromatic compound is calculated. The timing for starting to withdraw the reaction solution containing the polyarylene sulfide resin from one or more reaction vessels is determined so that the estimated reaction rate is equal to or greater than the target reaction rate. The method described in [2], including the method described in [2]. [7] The method further includes preparing a calibration curve representing the relationship between the concentration of the polyhalo-aromatic compound in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, and the concentration of the polyhalo-aromatic compound in the reaction solution, a calibration curve representing the relationship between the concentration of the sulfur compound in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, and the concentration of the sulfur source in the reaction solution, or both of these. The estimated value is obtained using the calibration curve. The method described in any of [1] to [6]. [8] The method according to any one of [1] to [7], wherein the reaction liquid is formed in the reaction kettle so that the gas phase portion does not flow between the plurality of reaction kettles. [9] The method according to any one of [1] to [8], wherein the spectroscopic analysis is at least one selected from the group consisting of near-infrared spectroscopy, Raman spectroscopy, fluorescent X-ray spectroscopy, and laser spectroscopy.

[10] A plurality of reaction kettles, A pipe connecting between the plurality of reaction kettles so that the plurality of reaction kettles communicate with each other, A condensing section for forming a condensate from the gas in the reaction kettle, A reaction apparatus comprising: The plurality of reaction kettles include a first reaction kettle and one or more additional reaction kettles arranged downstream of the first reaction kettle, and the first reaction kettle and the one or more additional reaction kettles are arranged in series via the pipe. The condensing section is connected to the first reaction kettle, the additional reaction kettle, or both. Reaction apparatus.

[11] A plurality of reaction kettles, A pipe connecting between the plurality of reaction kettles so that the plurality of reaction kettles communicate with each other, A gas phase analysis section for analyzing the gas in the reaction kettle or the condensate formed by condensation of the gas by spectroscopic analysis, [[ID=3k2]]A reaction apparatus comprising: The plurality of reaction kettles include a first reaction kettle and one or more additional reaction kettles arranged downstream of the first reaction kettle, and the first reaction kettle and the one or more additional reaction kettles are arranged in series via the pipe. The gas phase analysis section is connected to the first reaction kettle, the additional reaction kettle, or both. Reaction apparatus.

[12] The reaction apparatus according to

[10] or

[11] , further comprising an initial raw material introduction section for introducing a raw material into the first reaction kettle and an additional raw material introduction section for introducing an additional raw material into the additional reaction kettle. [Effects of the Invention]

[0008] A novel method capable of producing a polyarylene sulfide resin with stable quality can be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic diagram showing an example of a reaction apparatus for producing a polyarylene sulfide resin.

Embodiments for Carrying Out the Invention

[0010] The scope of the present invention is not limited to the examples described below, and various modifications can be made without departing from the spirit of the present invention. When a plurality of upper limit values and lower limit values are described for specific parameters, a numerical range combined with an upper limit value and a lower limit value arbitrarily selected from those upper limit values and lower limit values can be applied.

[0011] An example of a method for producing a polyarylene sulfide resin (PAS resin) includes forming a reaction solution containing an organic polar solvent, a polyhaloaromatic compound, and a sulfur source in a plurality of reaction vessels communicating with each other such that a gas phase portion remains in each reaction vessel, forming a polyarylene sulfide resin by a polymerization reaction in the reaction solution, extracting a reaction solution containing the polyarylene sulfide resin from one or more reaction vessels, measuring the concentration of the polyhaloaromatic compound, the sulfur compound, or both in the gas phase portion in one or more reaction vessels or the condensate formed by condensation of the gas phase portion during the polymerization reaction by spectroscopic analysis, and obtaining an estimated value of the amount of the polyhaloaromatic compound, the sulfur source, or both in the reaction solution from the measured concentration.

[0012] In this specification, "sulfur source" means a sulfur compound containing sulfur atoms that can carry out a polymerization reaction to produce a polyarylene sulfide resin by reacting with a polyhalo-aromatic compound. The sulfur source is not limited to a compound that reacts directly with the polyhalo-aromatic compound, but may also be a precursor compound that generates a sulfur compound that reacts with the polyhalo-aromatic compound in the reaction solution. The resulting polyarylene sulfide resin is a polymer formed by the alternating bonding of aromatic rings derived from the polyhalo-aromatic compound and sulfur atoms derived from the sulfur source.

[0013] To form a reaction solution, an organic polar solvent, a polyhalo-aromatic compound, and a sulfur source or a sulfur source precursor are each supplied to one or more of a plurality of reaction vessels.

[0014] The organic polar solvents constituting the reaction solution can be, for example, amides, ureas, lactams, sulfolanes, nitriles, ketones, or combinations thereof. Examples of amides include formamide, acetamide, N-methylformamide, N,N-dimethylacetamide, tetramethylurea, N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, and 1,3-dimethyl-2-imidazolidinoneic acid. Examples of sulfolanes include sulfolane and dimethylsulfolane. An example of a nitrile is benzonitrile. An example of a ketone is methylphenyl ketone. The organic polar solvent may be N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropylene urea, 1,3-dimethyl-2-imidazolidinone acid, or a combination thereof, or it may be N-methyl-2-pyrrolidone.

[0015] A polyhalo-aromatic compound can be a halogenated aromatic compound having an aromatic ring and two or more halogen atoms directly bonded to the aromatic ring. A polyhalo-aromatic compound may also be a dihalo-aromatic compound having two halogen atoms, a trihalo-aromatic compound having three halogen atoms, or a tetrahalo-aromatic compound having four halogen atoms. Examples include p-dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibrombenzene, diiodobenzene, tribrombenzene, dibromnaphthalene, triiodobenzene, dichlorodiphenylbenzene, dibromdiphenylbenzene, dichlorobenzophenone, dibrombenzophenone, dichlorodiphenyl ether, dibromdiphenyl ether, dichlorodiphenyl sulfide, dibromdiphenyl sulfide, dichlorobiphenyl, and dibrombiphenyl. A polyhalo-aromatic compound may be a combination of two or more selected from these. Two or more polyhalo-aromatic compounds may be combined to produce a block copolymer, known as PAS resin. The polyhalo-aromatic compound may be a dihalogenated benzene (e.g., p-dichlorobenzene). At least 80 mol% of the total amount of polyhalo-aromatic compounds supplied to the reaction solution may be p-dichlorobenzene. Polyphenylene sulfide resin (PPS resin) can be produced by polymerization of p-dichlorobenzene.

[0016] A PAS resin having a branched structure may be produced by combining a polyhalo-aromatic compound having three or more halogen atoms with a dihalo-aromatic compound as a branching agent. Examples of polyhalo-aromatic compounds having three or more halogen atoms include 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, and 1,4,6-trichloronaphthalene.

[0017] Polyhalo-aromatic compounds having functional groups with active hydrogen, such as amino groups, thiol groups, and hydroxyl groups, can also be used. Examples of polyhalo-aromatic compounds having functional groups with active hydrogen include dihaloanilines such as 2,6-dichloroaniline, 2,5-dichloroaniline, 2,4-dichloroaniline, and 2,3-dichloroaniline; trihaloanilines such as 2,3,4-trichloroaniline, 2,3,5-trichloroaniline, 2,4,6-trichloroaniline, and 3,4,5-trichloroaniline; dihaloaminodiphenyl ethers such as 2,2'-diamino-4,4'-dichlorodiphenyl ether and 2,4'-diamino-2',4-dichlorodiphenyl ether, and compounds in which the amino group in these compounds is replaced with a thiol group or a hydroxyl group. The aromatic ring in the polyhalo-aromatic compound having functional groups with active hydrogen may be substituted with an inert group (e.g., a hydrocarbon group such as an alkyl group). The polyhalo-aromatic compound having a functional group with active hydrogen may be dichloroaniline in particular.

[0018] Polyhalo-aromatic compounds may have a nitro group. Examples of polyhalo-aromatic compounds having a nitro group include mono- or dihalonitrobenzenes such as 2,4-dinitrochlorobenzene and 2,5-dichloronitrobenzene; dihalonitrodiphenyl ethers such as 2-nitro-4,4'-dichlorodiphenyl ether; dihalonitrodiphenyl sulfones such as 3,3'-dinitro-4,4'-dichlorodiphenyl sulfone; mono- or dihalonitropyridines such as 2,5-dichloro-3-nitropyridine and 2-chlor-3,5-dinitropyridine; and dihalonitronaphthalene.

[0019] The sulfur source can be, for example, one or more sulfur compounds selected from alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0020] The alkali metal sulfides may be, for example, lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide, or a combination thereof. Hydrates, aqueous mixtures, or anhydrous forms of alkali metal sulfides may be supplied to the reaction vessel.

[0021] Alkali metal hydroxides can produce alkali metal sulfides in the reaction mixture. For example, by supplying alkali metal hydroxides and alkali metal hydroxides to the reaction mixture, alkali metal sulfides can be produced in the reaction mixture by the reaction of alkali metal hydroxides and alkali metal hydroxides. Examples of alkali metal hydroxides include lithium hydrogen sulfide, sodium hydrogen sulfide, rubidium hydrogen sulfide, cesium hydrogen sulfide, and combinations thereof. Hydrates, aqueous mixtures, or anhydrous forms of alkali metal hydroxides may be supplied to the reaction vessel. Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and combinations thereof. The alkali metal hydroxide may be lithium hydroxide, sodium hydroxide, or potassium hydroxide, or it may be sodium hydroxide.

[0022] An aqueous alkali metal sulfide solution containing alkali metal sulfide and water may be supplied to the reaction mixture. Alternatively, an aqueous alkali metal hydroxide solution containing alkali metal hydroxide and water, and an aqueous alkali metal hydroxide solution containing alkali metal hydroxide and water may be supplied to the reaction mixture.

[0023] The reaction solution formed in the reaction vessel may further contain other components as needed. For example, the reaction solution may further contain polymerization aids such as alkali metal carboxylates and lithium halides.

[0024] Figure 1 is a schematic diagram showing an example of a reaction apparatus for producing PAS resin by the method according to the present disclosure. The reaction apparatus 100 shown in Figure 1 has a plurality of reaction vessels (first reaction vessel 11, second reaction vessel 12, and third reaction vessel 13), piping 51, 52 connecting the plurality of reaction vessels, and a condensation section 30 for forming a condensate from the gas in the reaction vessels. The plurality of reaction vessels include the first reaction vessel 11 and two additional reaction vessels, the second reaction vessel 12 and the third reaction vessel 13, which are arranged sequentially downstream of the first reaction vessel 11. The first reaction vessel 11, the second reaction vessel 12, and the third reaction vessel 13 are arranged in series via piping 51, 52 so as to be in communication with each other. In the example shown in Figure 1, the condensation section 30 is connected to the second reaction vessel, which is an additional reaction vessel.

[0025] The reaction apparatus 100 further includes a stirring device 15 having stirring blades inserted into each reaction vessel, an initial raw material introduction section 20 connected to the first reaction vessel 11, an additional raw material introduction section 25 connected to the third reaction vessel, two reflux devices 40 connected to the first and second reaction vessels respectively, and a withdrawal pipe 53 connected to the third reaction vessel. A valve B1 is provided on the pipe 51 connecting the first reaction vessel 11 and the second reaction vessel 12, and a valve B2 is provided on the pipe 52 connecting the second reaction vessel 12 and the third reaction vessel 13. A valve B3 is provided on the withdrawal pipe 53.

[0026] The initial raw material introduction section 20 includes, for example, a supply line for an organic polar solvent, a supply line for a polyhalo-aromatic compound, and a supply line for a sulfur source. Figure 1 shows an example where the organic polar solvent is N-methylpyrrolidone (NMP), the polyhalo-aromatic compound is p-dichlorobenzene (p-DCB), and sodium hydrogen sulfide (NaSH) is supplied together with sodium hydroxide (NaOH) as the sulfur source. For example, the reaction is formed in each reaction vessel by supplying a polyhalo-aromatic compound and an organic polar solvent to the first reaction vessel 11 with valve B1 closed, heating the reaction solution 1A in the first reaction vessel 11 containing these, further supplying an aqueous NaSH solution and an aqueous NaOH solution to the first reaction vessel 11, removing some of the water in the reaction solution 1A using a reflux device 40, opening valve B1 to transfer the reaction solution 1A from the first reaction vessel 11 to the second reaction vessel 12, thereby forming the reaction solution 1B in the second reaction vessel 12, and opening valve B2 to transfer the reaction solution 1B from the second reaction vessel 12 to the third reaction vessel 13, thereby forming the reaction solution 1C in the third reaction vessel 13. Before the reaction solutions are transferred, the organic polar solvent may be placed in the second reaction vessel 12 and the third reaction vessel 13 respectively and preheated. The resulting reaction solutions 1A, 1B, and 1C typically contain an organic polar solvent (NMP), a polyhalo-aromatic compound (p-DCB), and a sulfur source (Na2S). The polymerization reaction may have progressed to some extent by the time the reaction solutions are transferred to the third reaction vessel 13.

[0027] Reaction solutions 1A, 1B, and 1C are contained in the first reaction vessel 11, the second reaction vessel 12, and the third reaction vessel 13, respectively, such that gas phase portions 2A, 2B, and 2C remain within each vessel. Reaction solutions 1A, 1B, and 1C are formed within each reaction vessel in such a way that the gas phase portion does not flow between the first reaction vessel 11, the second reaction vessel 12, and the third reaction vessel 13. The fact that the gas phase portion does not flow between the reaction vessels is advantageous in that, as will be described later, spectroscopic analysis of the gas phase portion and the condensate of the gas phase portion can be performed in each reaction vessel, and the pressure or the amount of water in the system in each reaction vessel can be changed independently.

[0028] After reaction solutions 1A, 1B, and 1C are formed in the first reaction vessel 11, the second reaction vessel 12, and the third reaction vessel 13, respectively, a steady-state polymerization reaction can be carried out to produce a PAS resin having desired properties in terms of molecular weight, etc. During the polymerization reaction, reaction solutions 1A, 1B, and 1C may be stirred by a stirring device 15. The reaction solution containing the produced PAS resin is withdrawn from a withdrawal pipe 53 connected to the third reaction vessel 13. The steady-state polymerization reaction may be carried out while withdrawing the reaction solution containing the produced PAS resin.

[0029] During the polymerization reaction, the concentrations of polyhalo-aromatic compounds, sulfur compounds, or both in the gas phase 2B within the second reaction vessel 12, or in the condensate formed by the condensation of the gas phase 2B, are measured by spectroscopic analysis. The measured concentrations may be the molar concentrations of each component. In the example shown in Figure 1, the gas phase 2B is condensed by the condensation unit 30, and the resulting condensate is analyzed by spectroscopic analysis using an analytical instrument. The sulfur compounds contained in the gas phase are mainly hydrogen sulfide. Therefore, the concentration of hydrogen sulfide in the gas phase or the condensate may also be measured by spectroscopic analysis.

[0030] The spectroscopic analysis method can be any method capable of quantifying the concentrations of polyhalo-aromatic compounds, sulfur compounds, organic polar solvents, water, or all of these. The spectroscopic analysis method may also be one capable of quantifying the concentrations of polyhalo-aromatic compounds, sulfur compounds, or both. Examples of applicable spectroscopic analyses include near-infrared spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, laser spectroscopy, ultraviolet-visible spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, wavelength-dispersive X-ray spectroscopy, and energy-dispersive X-ray spectroscopy. In particular, from the viewpoint of ease of measurement and equipment, spectroscopic analysis may be selected from near-infrared spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, and laser spectroscopy. Spectroscopic analysis allows for the efficient and rapid quantification of the concentration of each component.

[0031] The method for calculating the concentration of each component from the results of spectroscopic analysis is not particularly limited and can be arbitrarily selected from conventional methods. For example, the concentration of each component may be calculated from the spectral spectrum obtained by spectroscopic analysis using a pre-prepared calibration model. The calibration model can be created by conventional quantitative analysis methods using multivariate analysis. For example, a calibration model can be created from the spectral intensity of specific wavelengths corresponding to each component using principal component analysis, PLS regression analysis, or multiple regression analysis. The concentration of each raw material may be automatically calculated using a calculation device that stores the calibration model. The calculation device for this purpose may have a storage unit and a calculation unit.

[0032] An analytical apparatus for spectroscopic analysis includes, for example, a measurement terminal, a spectrometer, an analysis device, and equipment (such as optical fibers) for connecting the measurement terminal and the spectrometer. The analysis device may be located remotely from the main body of the analytical apparatus and connected online to the main body. The spectrometer may be a device capable of batch measurement or continuous measurement.

[0033] The measurement time for a single spectroscopic analysis is not particularly limited, but from the viewpoint of balancing measurement accuracy and immediacy, it may be 5 minutes or less, 1 minute or less, or 30 seconds or less. Multiple measurements for spectroscopic analysis may be performed during the polymerization reaction, and the interval between measurements in this case may be 1 minute or less, 30 seconds or less, or 1 second or less. Measurements for spectroscopic analysis may be performed continuously during the polymerization reaction. By obtaining spectroscopic analysis results at short intervals or continuously, the reaction conditions can be quickly adjusted in response to changes in the system, and as a result, a product with stable quality can be obtained more efficiently.

[0034] A gas-phase analysis unit may be installed in a second reaction vessel, which is an additional reaction vessel, or in any other reaction vessel, and the gas phase in the reaction vessel, or the condensate formed by the condensation of the gas phase, may be analyzed by spectroscopic analysis in the gas-phase analysis unit. For example, the reaction apparatus 100 illustrated in Figure 1 has a gas-phase analysis unit 31 provided between the condensation unit 30 and the second reaction vessel 12. In this case, the condensate of the gas phase 2B formed by the condensation unit 30 can be analyzed by the gas-phase analysis unit 31. For this purpose, the gas-phase analysis unit 31 may have a probe for spectroscopic analysis by near-infrared spectroscopy or the like. A gas-phase analysis unit capable of directly analyzing the gas phase may be installed in the reaction vessel. For example, a gas-phase analysis unit having a tunable semiconductor laser can be installed in the reaction vessel.

[0035] Based on the good correlation between the concentrations of each component (polyhalo-aromatic compounds, sulfur compounds) in the gas phase or condensate and the concentrations of the polyhalo-aromatic compounds and sulfur source in the reaction solution, estimated values ​​of the concentrations of polyhalo-aromatic compounds and sulfur source in the reaction solution can be obtained from the measured concentrations in the gas phase or condensate. For example, a calibration curve relating to the correlation between the two can be prepared in advance, and estimated values ​​of the concentrations of polyhalo-aromatic compounds and sulfur source can be obtained based on that calibration curve. When the condensate formed by the condensation of the gas phase 2B in the second reaction vessel 12 is analyzed by spectroscopic analysis, the calibration curve prepared may include a calibration curve representing the relationship between the concentration of the polyhalo-aromatic compounds in the condensate formed by the condensation of the gas phase 2B and the concentration of the polyhalo-aromatic compounds in the reaction solution 1B, a calibration curve representing the relationship between the concentration of the sulfur compounds in the condensate formed by the condensation of the gas phase 2B and the concentration of the sulfur source in the reaction solution 1B, or both. When the gas phase 2B in the second reaction vessel 12 is analyzed by spectroscopic analysis, the calibration curves prepared may include a calibration curve showing the relationship between the concentration of the polyhalo-aromatic compound in the gas phase 2B and the concentration of the polyhalo-aromatic compound in the reaction solution 1B, a calibration curve showing the relationship between the concentration of the sulfur compound in the gas phase 2B and the concentration of the sulfur source in the reaction solution 1B, or both. The concentration of the sulfur source in the reaction solution may be, for example, the total concentration of one or more sulfur compounds selected from alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0036] Calibration curves are created, for example, by a method that includes measuring the concentrations of polyhalo-aromatic compounds and sulfur sources in the reaction solution and the concentrations of polyhalo-aromatic compounds and sulfur compounds in the gas phase or condensate during polymerization reaction tests using the reactor itself or a reactor having substantially the same configuration, while estimating the concentrations of each component by spectroscopic analysis. Calibration curves can also be created by the least squares method from the relationship between the concentration of polyhalo-aromatic compounds or sulfur sources in the reaction solution and the concentration of polyhalo-aromatic compounds or sulfur compounds in the gas phase or condensate. The polymerization reaction conditions, such as the reaction temperature, in the polymerization reaction tests for calibration curve creation may be set to several conditions that are substantially the same as, or close to, the conditions for the polymerization reaction used for the production of PAS resin. Polymerization reaction tests may be performed under multiple conditions with different supply amounts of polyhalo-aromatic compounds or sulfur sources. The method for measuring the concentration of each component in the gas phase or condensate for calibration curve measurement is not limited to spectroscopic analysis and can be any method. For example, a combination of gas chromatography and silver nitrate titration can be used to measure the concentrations of polyhalo-aromatic compounds and sulfur compounds in polymerization reaction tests.

[0037] By adjusting the polymerization reaction conditions based on the estimated concentrations of each component, PAS resin with desired properties in terms of molecular weight and other characteristics can be stably produced. Spectroscopic analysis allows for analysis in a short time, enabling adjustment of the polymerization reaction conditions at the appropriate timing during the reaction.

[0038] Examples of conditions for the polymerization reaction to be adjusted include the molar ratio of polyhalo-aromatic compounds to sulfur source in the reaction solution, the timing of the withdrawal of the reaction solution containing PAS resin from the reaction vessel, the amount of polyhalo-aromatic compounds in the reaction solution, the amount of sulfur source in the reaction solution, the polymerization reaction time, the temperature of the reaction solution, and the pressure of the gas phase.

[0039] Adjusting the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution includes, for example, calculating an estimated molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution from estimated amounts of the polyhalo-aromatic compound and the sulfur source in the reaction solution, and adjusting the amounts of the polyhalo-aromatic compound, the sulfur source, or both in the reaction solution one or more times so that the estimated molar ratio approaches the target molar ratio. The target molar ratio is set, for example, within the range of polyhalo-aromatic compound / sulfur source (molar ratio) = 80 / 100 to 150 / 100.

[0040] If the proportion of the polyhalo-aromatic compound in the estimated molar ratio is smaller than the proportion in the target molar ratio, additional polyhalo-aromatic compounds may be supplied to the reaction mixture to bring the molar ratio closer to the target value. In the example in Figure 1, additional polyhalo-aromatic compounds can be supplied from the additional raw material introduction section 25 connected to the third reaction vessel. If the proportion of the polyhalo-aromatic compound in the estimated molar ratio is larger than the proportion in the target molar ratio, the amount of polyhalo-aromatic compounds supplied to the reaction mixture may be reduced, or additional sulfur sources or their precursors (e.g., NaSH and NaOH) may be supplied to the reaction mixture to bring the molar ratio closer to the target value.

[0041] Adjusting the timing for withdrawing the reaction solution containing PAS resin from the reaction vessel includes, for example, calculating an estimated reaction rate of the polyhalo-aromatic compound from an estimated amount of the polyhalo-aromatic compound in the reaction solution, and determining the timing for withdrawing the reaction solution containing PAS resin from the reaction vessel so that the estimated reaction rate is equal to or greater than the target reaction rate. After the estimated reaction rate reaches a predetermined target value or greater, the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution may be adjusted using the method described above, and then the reaction solution containing PAS resin may be withdrawn from the reaction vessel. The target reaction rate is set, for example, within the range of 89.0 to 91.0 mol%. The timing for withdrawing the reaction solution containing PAS resin from the reaction vessel may be determined so that the estimated reaction rate in the reaction solution of the second reaction vessel is equal to or greater than the target value.

[0042] After the estimated reaction rate exceeds the target reaction rate, and before beginning to remove the reaction solution containing the PAS resin from the reaction vessel, the amounts of the polyhalo-aromatic compound, the sulfur source, or both of these in the reaction solution may be adjusted so that the estimated molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution approaches the target molar ratio. Furthermore, while the steady-state polymerization reaction is proceeding while removing the reaction solution containing the generated PAS resin, the amounts of the polyhalo-aromatic compound, the sulfur source, or both of these in the reaction solution may be adjusted so that the estimated molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution approaches the target molar ratio.

[0043] During the polymerization reaction, the gas phase 2A in the first reaction vessel 11, the gas phase 2B in the second reaction vessel 12, or both, may be condensed by the reflux apparatus 40, and the polyhalo-aromatic compound recovered by condensation may be returned to the reaction solution 1A or 1B. The reflux apparatus 40 consists of a distillation column 41, a condenser 43, a decanter 45, and a valve B40. For example, a gas containing hydrogen sulfide and vapor containing an organic polar solvent and water formed by azeotropy is introduced into the distillation column 41. The gas containing the polyhalo-aromatic compound, hydrogen sulfide, and water discharged from the top of the distillation column 41 is condensed in the condenser 43 to form a condensate mainly containing the polyhalo-aromatic compound and water. The temperature at which the gas is cooled for condensation can be, for example, 100°C or lower, or room temperature (23°C) or lower. The condensate is separated into the polyhalo-aromatic compound and water in the decanter 45. The separated polyhalo-aromatic compounds can be returned to reaction solution 1A or 1B as needed. For example, the amount of polyhalo-aromatic compounds returned from decanter 45 to reaction solution 1A or 1B may be adjusted so that the estimated molar ratio of polyhalo-aromatic compounds to sulfur source in the reaction solution, determined by the method described above, approaches the target molar ratio. The gaseous components discharged from condenser 43 are usually discharged to the outside after hydrogen sulfide is removed by contact with an alkaline aqueous solution. A gas phase analysis unit for spectroscopic analysis of the condensate may be provided between the distillation column 41 and the second reaction vessel of reflux apparatus 40.

[0044] During the polymerization reaction, the temperature of the reaction mixture is maintained in a range of, for example, 200 to 330°C. The pressure in the gas phase within each reaction vessel may be, for example, 0.1 to 20 MPa or 0.1 to 2 MPa.

[0045] The total amount of polyhalo-aromatic compound supplied to the reaction solution may be in the range of 0.2 to 5.0 moles, 0.8 to 1.3 moles, or 0.9 to 1.1 moles per mole of sulfur atoms contained in the sulfur compound supplied as a sulfur source to the reaction solution. The total amount of organic polar solvent supplied to the reaction vessel may be in the range of 1.0 to 6.0 moles, or 2.5 to 4.5 moles per mole of sulfur atoms contained in the sulfur compound supplied as a sulfur source to the reaction solution.

[0046] The reaction solution may contain water derived from an aqueous solution of a sulfur source or its precursor. The proportion of water in the reaction solution may be, for example, 5.0 moles or less, 2.0 moles or less, 1.6 moles or less, or 0.01 moles or more per mole of sulfur atoms contained in the sulfur compound as a sulfur source. To adjust the proportion of water, water may be removed from the reaction solution by refluxing apparatus 40. Water may be added to the reaction solution during the polymerization reaction.

[0047] A PAS resin composition can be obtained by mixing the PAS resin obtained by the methods exemplified above with any components used as needed. The components that the PAS resin composition according to this disclosure may optionally contain are the same as those used in ordinary PAS resin compositions, and examples include synthetic resins other than PAS resin, elastomers, mold release agents, colorants, heat stabilizers, UV stabilizers, foaming agents, rust inhibitors, flame retardants, lubricants, coupling agents, and fillers. The PAS resin composition according to this disclosure can be used as a molding material for forming resin molded articles used in various applications, similar to ordinary PAS resin compositions. [Examples]

[0048] The present invention will be specifically described below with reference to examples. The present invention is not limited to these examples.

[0049] 1. Creating a calibration curve A reaction apparatus was prepared having a first, second, and third reaction vessel with an internal volume of 2 liters, and having a configuration similar to the reaction apparatus shown in Figure 1. Using this reaction apparatus, a polymerization reaction to produce polyphenylene sulfide (PPS) resin was carried out in the reaction liquid in the first, second, and third reaction vessels under the same conditions as in Example 1 described later. While the polymerization reaction was progressing, samples for concentration measurement were taken from the reaction liquid and the gas phase in the second reaction vessel. The sample from the gas phase was taken as a condensate generated by cooling the gas phase. By analyzing each sample by gas chromatography (apparatus: Shimadzu GC2014) and silver nitrate titration (apparatus: Kyoto Electronics Industrial AT710), the molar concentrations (mol%) of p-DCB and sulfur source in the reaction liquid (liquid phase) and the molar concentrations (mol%) of p-DCB and hydrogen sulfide in the condensate of the gas phase were determined. In polymerization reactions under several conditions with different amounts of each raw material, the molar concentrations of each component in the reaction solution and the condensate in the gas phase were determined using the same method as described above. From the obtained results, a first calibration curve representing the relationship between the molar concentration of p-DCB in the condensate in the gas phase and the molar concentration of p-DCB in the reaction solution, and a second calibration curve representing the relationship between the molar concentration of hydrogen sulfide in the condensate in the gas phase and the molar concentration of the sulfur source in the reaction solution were created using the least squares method.

[0050] 2. Synthesis of PPS resin [Example 1] A polymerization reaction to synthesize polyphenylene sulfide (PPS) resin was carried out using the same reactor that was used to create the calibration curve. With the valve between the first and second reaction vessels closed, a reaction solution containing 147.0 g (1.0 mol) of p-dichlorobenzene (p-DCB) and 378.7 g (3.8 mol) of N-methylpyrrolidone (NMP) was placed in the first reaction vessel, leaving a gas phase portion into which nitrogen had been introduced. The reaction solution was stirred under a nitrogen atmosphere, and the temperature of the reaction solution was raised from room temperature to 220°C. While maintaining the temperature of the reaction solution at 220°C, a 48% by mass aqueous NaSH solution and a 48% by mass aqueous NaOH solution were continuously supplied to the first reaction vessel over 3 hours using a metering pump. The supply rate of the NaSH solution was 0.50 mL / min, and the supply rate of the NaOH solution was 0.31 mL / min. While supplying NaSH aqueous solution and NaOH aqueous solution, water was continuously removed from the gas phase using a distillation column connected to the first reaction vessel, while controlling the gauge pressure to 0.2 MPa with a pressure regulating valve. The p-DCB contained in the removed water was separated in a decanter (standing tank) and returned to the first reaction vessel.

[0051] When the supply of NaSH aqueous solution reached 90 mL and the supply of NaOH aqueous solution reached 56 mL, the continuous supply of p-DCB and NMP was started while continuing the supply of NaSH and NaOH aqueous solutions. The supply rate of p-DCB was set to 0.66 mL / min, and the supply rate of NMP was set to 2.04 mL / min.

[0052] 189.4 g (1.9 mol) of NMP was pre-filled into the second reaction vessel and heated to 220°C. Subsequently, 189.4 g (1.9 mol) of NMP was pre-filled into the third reaction vessel and heated to 230°C. After the continuous supply of p-DCB and NMP to the first reaction vessel was started, the valve between the first and second reaction vessels was opened, and the reaction mixture was continuously transferred from the first to the second reaction vessel at a flow rate of 3.50 mL / min over 3 hours. After the transfer of the reaction mixture to the second reaction vessel began, water was continuously removed from the gas phase using a distillation column connected to the second reaction vessel, while controlling the gauge pressure to 0.10 MPa with a pressure regulating valve. The p-DCB contained in the removed water was separated in a decanter (standing tank) and returned to the second reaction vessel.

[0053] At the point when the reaction mixture was continuously transferred from the first reaction vessel to the second reaction vessel over a period of 3 hours, the supply of p-DCB, NaSH aqueous solution, NaOH aqueous solution, and NMP to the first reaction vessel was stopped, and the polymerization reaction continued. When the supply of raw materials was stopped, the condensate formed by cooling the gas phase in the second reaction vessel to room temperature (25°C) using a condenser attached to the second reaction vessel was collected. The spectral spectrum of the obtained condensate in the wavelength range of 780 to 2500 nm was measured for 15 seconds using a near-infrared spectrometer (Bruker MPA). From the obtained spectral spectrum, the molar concentrations of p-DCB and hydrogen sulfide in the condensate were determined by referring to a pre-prepared calibration curve for spectral analysis. The calibration curve for spectral analysis was created by near-infrared spectroscopy measurements of 10 different test solutions containing p-DCB and hydrogen sulfide at different concentrations. To create a calibration curve, the absorbance in the spectral spectrum in the wavelength range of 780–2500 nm was subjected to second derivative analysis, and then PLS regression analysis was performed to plot the relative intensity ratio of absorbance for each concentration.

[0054] From the obtained molar concentration of p-DCB and the first calibration curve for p-DCB molar concentration prepared in advance, the estimated molar concentration of p-DCB in the reaction solution was calculated by multivariate analysis. By comparing the molar concentration of p-DCB with the amount of p-DCB supplied to the reaction vessel, the reaction rate of p-DCB was estimated to be 85.2 mol%. At 1 hour and 2 hours after the supply of raw materials was stopped, the condensate formed by condensation of the gas phase in the second reaction vessel was collected and similarly analyzed by near-infrared spectroscopy. The estimated reaction rate of p-DCB was 87.6 mol% at 1 hour and 90.1 mol% at 2 hours.

[0055] Once it was confirmed that the reaction rate of p-DCB in the second reaction vessel reached 90.1 mol%, the molar concentration of the sulfur source in the reaction solution was estimated from near-infrared spectroscopy analysis of the condensate in the gas phase of the second reaction vessel and the second calibration curve for the sulfur source concentration. The molar ratio of p-DCB to sulfur source (p-DCB / sulfur source) obtained from the estimated molar concentration was 99 / 100, which was insufficient for the target value of 100 / 100. Therefore, 0.15 g of p-DCB was added to the third reaction vessel. 0.15 g of p-DCB corresponds to 0.1 mol% of the amount of sulfur source in the reaction solution, which was determined from the estimated sulfur source concentration.

[0056] After adding p-DCB to the third reaction vessel, the continuous supply of each raw material to the first and second reaction vessels was resumed. The valve between the second and third reaction vessels was opened, and the reaction solution was continuously transferred from the second to the third reaction vessel at a flow rate of 3.50 mL / min over 3 hours. When the liquid level of the reaction solution in the third reaction vessel became the same as the liquid level of the reaction solution in the second reaction vessel, the continuous supply of each raw material to the first and second reaction vessels was stopped. The polymerization reaction continued for 3 hours after the supply of raw materials was stopped. After that, the reaction solution was continuously withdrawn from the third reaction vessel. The period from the start of the withdrawal of the reaction solution was considered the steady state of the polymerization reaction. From the reaction solution withdrawn from the reaction vessel in the initial stage of the steady state polymerization reaction, purified PPS resin was obtained by a conventional method. The melt viscosity of the obtained PPS resin was 51 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced. The melt viscosity was measured using a Shimadzu CFT-500D flow tester under the conditions of 300°C, load: 20 kgf / cm², and L / D = 10 (mm) / 1 (mm), after holding for 6 minutes.

[0057] At 1 hour of steady-state polymerization, the estimated molar concentration of the sulfur source in the reaction solution was calculated using the same spectroscopic analysis as described above. Since the molar ratio of p-DCB to sulfur source (p-DCB / sulfur source) was 99 / 100, 0.15 g of p-DCB was added to the third reaction vessel. Subsequently, the reaction solution was collected from the third reaction vessel, and purified PPS resin was obtained by conventional methods. The melt viscosity of the obtained PPS resin was 49 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced.

[0058] At 2 hours into the steady-state polymerization reaction, the estimated molar concentration of the sulfur source in the reaction solution was calculated using the same spectroscopic analysis as described above. Since the molar ratio of p-DCB to the sulfur source (p-DCB / S) was 100 / 100, the reaction was continued without correction by adding p-DCB. Subsequently, the reaction solution was collected from the third reaction vessel, and purified PPS resin was obtained by conventional methods. The melt viscosity of the obtained PPS resin was 50 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced.

[0059] [Example 2] A polymerization reaction test to produce PPS resin was conducted under the same conditions as in Example 1. The estimated p-DCB reaction rate was determined for the reaction solution at 0 hours, 1 hour, and 2 hours of polymerization in the second reaction vessel using the same method as in Example 1. The estimated reaction rates obtained are shown in Table 1. The polymerization reaction time in the second reaction vessel is the elapsed time from the point when the reaction solution was continuously transferred from the first reaction vessel to the second reaction vessel over a period of 3 hours.

[0060] The estimated reaction rate of p-DCB in the reaction solution in the second reaction vessel was confirmed to be 89.8 mol%. The estimated molar ratio of p-DCB to sulfur source (p-DCB / S) in the reaction solution at that point was calculated in the same manner as in Example 1, and it was found to be 101 / 100, confirming that the amount of p-DCB was excessive. Therefore, the p-DCB (approximately 0.15 g) separated from the water removed from the reaction solution in the second reaction vessel in a decanter (standing tank) was not returned from the decanter to the second reaction vessel, thereby adjusting the molar ratio to be close to the target value of 100 / 100.

[0061] After confirming the molar ratio of p-DCB to sulfur source in the reaction solution, the continuous supply of each raw material to the first and second reaction vessels was resumed. The valve between the second and third reaction vessels was opened, and the reaction solution was continuously transferred from the second to the third reaction vessel over a period of 3 hours. When the liquid level of the reaction solution in the third reaction vessel became the same as the liquid level of the reaction solution in the second reaction vessel, the continuous supply of each component to the first and second reaction vessels was stopped. The polymerization reaction continued for 3 hours after the supply of raw materials was stopped. After that, the reaction solution was continuously withdrawn from the third reaction vessel. The period from the start of the withdrawal of the reaction solution was considered the steady state of the polymerization reaction. The melt viscosity of the purified PPS resin obtained from the reaction solution withdrawn from the reaction vessel at the beginning of the steady state polymerization reaction was 49 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced.

[0062] At 1 hour of steady-state polymerization, the molar concentration of the sulfur source in the reaction solution was estimated using the same spectroscopic analysis as described above. The estimated molar ratio of p-DCB to sulfur source (p-DCB / sulfur source) obtained from the estimated molar concentration was 101 / 100, confirming that the amount of p-DCB was excessive. Therefore, the molar ratio was adjusted to approach the target value of 100 / 100 by not returning the p-DCB (approximately 0.15 g) separated from the water removed from the reaction solution in the second reaction vessel in a decanter (standing tank) back into the second reaction vessel. Subsequently, the reaction solution was collected from the third reaction vessel, and PPS resin was obtained by a conventional method. The melt viscosity of the obtained PPS resin was 48 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced.

[0063] At 2 hours into the steady-state polymerization reaction, the estimated molar concentration of the sulfur source in the reaction solution was calculated using the same spectroscopic analysis as described above. Since the molar ratio of p-DCB to sulfur source (p-DCB / sulfur source) was 100 / 100, the reaction was continued without correcting for p-DCB. Subsequently, the reaction solution was collected from the third reaction vessel, and purified PPS resin was obtained by conventional methods. The melt viscosity of the obtained PPS resin was 51 Pa·s, confirming that a PPS resin with a molecular weight within the target range was produced.

[0064] [Table 1]

[0065] [Comparative Example 1] A polymerization reaction test to produce PPS resin was conducted under the same conditions as in Example 1. Samples were taken from the second reaction vessel at 0, 1, and 2 hours of polymerization. After taking the sample at 2 hours, the continuous supply of each component to the first and second reaction vessels was resumed, and the valve between the second and third reaction vessels was opened to continuously transfer the reaction solution from the second to the third reaction vessel over 3 hours. When the liquid level of the reaction solution in the third reaction vessel became the same as the liquid level of the reaction solution in the second reaction vessel, the continuous supply of each component to the first and second reaction vessels was stopped. The polymerization reaction continued for 3 hours after the supply of raw materials was stopped. After that, the reaction solution was continuously withdrawn from the third reaction vessel. The period from the start of the withdrawal of the reaction solution was considered the steady state of the polymerization reaction. The melt viscosity of the purified PPS resin obtained from the reaction solution withdrawn from the reaction vessel in the early stages of the steady state polymerization reaction was 73 Pa·s, indicating that a PPS resin with a molecular weight larger than the target molecular weight range had been produced.

[0066] The molar concentrations of p-DCB and sulfur source in the reaction solution were determined by analyzing samples of the reaction solution taken during the polymerization reaction using gas chromatography (apparatus: Shimadzu GC2014) and silver nitrate titration (apparatus: Kyoto Electronics Industrial AT710). At 2 hours of polymerization in the second reaction vessel, the p-DCB / sulfur source (molar ratio) was 98 / 100, confirming that the amount of p-DCB was insufficient. The results of the analysis are shown in Table 2.

[0067] At 1 hour of steady-state polymerization, the reaction solution was collected from the third reaction vessel and purified by conventional methods to obtain PPS resin. The melt viscosity of the purified PPS resin was 88 Pa·s, indicating that the PPS resin produced had a molecular weight larger than the target molecular weight range. By analyzing the sample of the collected reaction solution, the molar concentrations of p-DCB and sulfur source in the reaction solution were determined. The p-DCB / sulfur source (molar ratio) was 97 / 100, confirming that the amount of p-DCB was insufficient.

[0068] The same purification and analysis were performed at a point when the steady-state polymerization reaction time was 2 hours. The results of the analysis are shown in Table 2.

[0069] [Comparative Example 2] A polymerization reaction test to produce PPS resin was conducted under the same conditions as in Example 1. Samples were taken from the second reaction vessel at 0 hours, 1 hour, and 2 hours of polymerization. After taking the sample at 2 hours, the continuous supply of each component to the first and second reaction vessels was resumed, and the valve between the second and third reaction vessels was opened to continuously transfer the reaction solution from the second to the third reaction vessel over 3 hours. When the liquid level of the reaction solution in the third reaction vessel became the same as the liquid level of the reaction solution in the second reaction vessel, the continuous supply of each component to the first and second reaction vessels was stopped. The polymerization reaction continued for 3 hours after the supply of raw materials was stopped. After that, the reaction solution was continuously withdrawn from the third reaction vessel. The period from the start of the withdrawal of the reaction solution was considered to be the steady state of the polymerization reaction. The melt viscosity of the purified PPS resin obtained from the reaction solution withdrawn from the reaction vessel in the early stages of the steady state polymerization reaction was 21 Pa·s, indicating that a PPS resin with a molecular weight smaller than the target molecular weight range was produced.

[0070] The concentrations of p-DCB and sulfur source in the reaction solution were determined by analyzing samples of the reaction solution taken during the polymerization reaction using gas chromatography (Shimadzu GC2014) and silver nitrate titration (Kyoto Electronics Industrial AT710). At 2 hours of polymerization in the second reaction vessel, the p-DCB / sulfur source (molar ratio) was 10² / 100, confirming an excess of p-DCB. The results of the analysis are shown in Table 2.

[0071] At 1 hour of steady-state polymerization, the reaction solution was collected from the third reaction vessel and purified by conventional methods to obtain PPS resin. The melt viscosity of the purified PPS resin was 9 Pa·s, indicating that the PPS resin produced had a molecular weight smaller than the target molecular weight range. By analyzing the sample of the collected reaction solution, the molar concentrations of p-DCB and sulfur source in the reaction solution were determined. The p-DCB / sulfur source (molar ratio) was 10³ / 100, confirming an excess of p-DCB. The results of the analysis are shown in Table 2.

[0072] The same purification and analysis were performed at a point when the steady-state polymerization reaction time was 2 hours. The results of the analysis are shown in Table 2.

[0073] [Table 2] [Explanation of symbols]

[0074] 1A, 1B, 1C... Reaction solution, 2A, 2B, 2C... Gas phase section, 11... First reaction vessel, 12... Second reaction vessel (additional reaction vessel), 13... Third reaction vessel (additional reaction vessel), 15... Stirring device, 20... Initial raw material introduction section, 25... Additional raw material introduction section, 30... Condensing section, 31... Gas phase analysis section, 41... Distillation column, 43... Condenser, 45... Decanter, 51, 52... Piping, 53... Extraction piping, 100... Reaction apparatus, B1, B2, B3, B40... Valves.

Claims

1. The reaction solution containing an organic polar solvent, a polyhalo-aromatic compound, and a sulfur source is formed in a plurality of interconnected reaction vessels, such that a gas phase remains in each of the reaction vessels. A polyarylene sulfide resin is formed by a polymerization reaction in the aforementioned reaction solution, The process involves removing the reaction solution containing the polyarylene sulfide resin from one or more of the reaction vessels, During the polymerization reaction, the concentrations of the polyhalo-aromatic compound, sulfur compound, or both in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, are measured by spectroscopic analysis. From the measured concentrations, estimates of the concentrations of the polyhalo-aromatic compound, the sulfur source, or both in the reaction solution are obtained. including, A method for producing polyarylene sulfide resin.

2. The method according to claim 1, further comprising adjusting the conditions of the polymerization reaction based on the estimated values.

3. The conditions for the polymerization reaction to be adjusted include one or more selected from the group consisting of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution, the timing at which the reaction solution containing the polyarylene sulfide resin is to be withdrawn from one or more reaction vessels, the amount of the polyhalo-aromatic compound contained in the reaction solution, the amount of the sulfur source contained in the reaction solution, the time of the polymerization reaction, the temperature of the reaction solution, and the pressure of the gas phase. The method according to claim 2.

4. Adjusting the conditions of the polymerization reaction, From the estimated concentrations of the polyhalo-aromatic compound and the sulfur source in the reaction solution, an estimated value of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the reaction solution is calculated. The amounts of the polyhalo-aromatic compound, the sulfur source, or both of these in the reaction solution are adjusted so that the estimated value of the molar ratio approaches the target value of the molar ratio. The method according to claim 2, including the method described in claim 2.

5. Adjusting the conditions of the polymerization reaction, The method further includes calculating an estimated value of the reaction rate of the polyhalo-aromatic compound from the estimated value of the concentration of the polyhalo-aromatic compound in the reaction solution, The method according to claim 4, wherein, after the estimated value of the reaction rate becomes equal to or greater than the target value of the reaction rate, the amounts of the polyhalo-aromatic compound, the sulfur source, or both thereof in the reaction solution are adjusted one or more times so that the estimated value of the molar ratio approaches the target value of the molar ratio.

6. Adjusting the conditions of the polymerization reaction, From the estimated concentration of the polyhalo-aromatic compound in the reaction solution, an estimated value of the reaction rate of the polyhalo-aromatic compound is calculated. The timing for starting to withdraw the reaction solution containing the polyarylene sulfide resin from one or more reaction vessels is determined so that the estimated reaction rate is equal to or greater than the target reaction rate. The method according to claim 2, including the method described in claim 2.

7. The method further includes preparing a calibration curve representing the relationship between the concentration of the polyhalo-aromatic compound in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, and the concentration of the polyhalo-aromatic compound in the reaction solution, a calibration curve representing the relationship between the concentration of the sulfur compound in the gas phase portion of one or more reaction vessels, or in the condensate formed by the condensation of the gas phase portion, and the concentration of the sulfur source in the reaction solution, or both of these. The estimated value is obtained using the calibration curve. The method according to claim 1.

8. The method according to claim 1, wherein the reaction liquid is formed inside the reaction vessel so that the gas phase does not flow between the plurality of reaction vessels.

9. The method according to any one of claims 1 to 8, wherein the spectroscopic analysis is at least one selected from the group consisting of near-infrared spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, and laser spectroscopy.

10. Multiple reaction vessels, A pipe is provided to connect the plurality of reaction vessels so that they are in communication with one another. A condensation section for forming a condensate from the gas in the reaction vessel, A reaction apparatus comprising, The plurality of reaction vessels include a first reaction vessel and one or more additional reaction vessels arranged downstream of the first reaction vessel, and the first reaction vessel and the one or more additional reaction vessels are arranged in series via the piping. The condensing section is connected to the first reaction vessel, the additional reaction vessel, or both thereof. Reaction apparatus.

11. Multiple reaction vessels, A pipe is provided to connect the plurality of reaction vessels so that they are in communication with one another. A gas phase analysis unit analyzes the gas in the reaction vessel, or the condensate formed by the condensation of the gas, by spectroscopic analysis. A reaction apparatus comprising, The plurality of reaction vessels include a first reaction vessel and one or more additional reaction vessels arranged downstream of the first reaction vessel, and the first reaction vessel and the one or more additional reaction vessels are arranged in series via the piping. The gas phase analysis unit is connected to the first reaction vessel, the additional reaction vessel, or both thereof. Reaction apparatus.

12. The reaction apparatus according to claim 10 or 11, further comprising an initial raw material introduction unit for introducing raw materials into the first reaction vessel, and an additional raw material introduction unit for introducing additional raw materials into the additional reaction vessel.

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