Method for producing polyarylene sulfide resin

Abstract

To provide a method for producing polyarylene sulfide (PAS) resin of stable quality by evaluating the monomer composition during polymerization in a simple and short time. [Solution] A method for producing PAS resin by polymerizing a polyhalo-aromatic compound and a sulfur source in a reaction vessel in an organic polar solvent, comprising: (1) measuring the concentration of at least one selected from the polyhalo-aromatic compound, sulfur source, organic polar solvent, and water in the gas phase portion of the reaction vessel or the condensate formed by the condensation of the gas phase portion by spectroscopic analysis; and (2) calculating the raw material concentration in the liquid phase portion of the polymerization reaction system based on the measured concentration and controlling the raw material ratio or reaction conditions.

Description

Technical Field

[0001] The present invention relates to a method for producing a polyarylene sulfide resin.

Background Art

[0002] Polyarylene sulfide (hereinafter referred to as PAS) resins typified by polyphenylene sulfide (hereinafter referred to as PPS) resins are excellent in heat resistance, chemical resistance, etc., and are widely used in applications such as electric and electronic parts, automotive parts, hot water supply machine parts, fibers, and films. Among them, high molecular weight PAS resins have been in increasing demand in recent years because of their excellent mechanical properties such as toughness.

[0003] As a method for producing a PAS resin, for example, a method is known in which a hydrous alkali metal sulfide is introduced into a heated mixed solution of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) and a polyhaloaromatic compound at a rate at which water can be removed from the reaction mixture, and dehydration and polymerization of the mixture are carried out in parallel to produce a PAS resin (see Patent Document 1). Also, a method for producing a PAS resin by mixing a hydrous alkali metal sulfide, less than 1 mol of NMP per 1 mol of a hydrous alkali metal hydroxide, and a polyhaloaromatic compound, performing azeotropic dehydration of the mixture, and then heating and polymerizing it (see Patent Document 2), and a method for producing a PAS resin by a multi-step process in which a step of heating and stirring NMP and a hydrous alkali metal hydroxide to produce a hydrolyzate of NMP, a dehydration and prepolymerization step, and a polymerization step are each carried out in different reaction vessels (see Patent Document 3) are known.

[0004] However, despite the critical importance of controlling the molar ratio of monomer composition in the polymerization reaction of PAS resin, a rapid and accurate analytical method for determining the monomer composition during polymerization has not been established. Conventional methods have involved extracting and analyzing a portion of the reaction slurry, but sampling from a polymerization vessel undergoing high temperature and pressure is dangerous, complex, and time-consuming. Furthermore, because the polymerization reaction of PAS resin proceeds under a strongly alkaline and high-temperature environment, directly monitoring the liquid phase (reaction slurry) is difficult due to concerns about damage to or degradation of analytical equipment and its impact on the polymerization reaction. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-228699 [Patent Document 2] Japanese Patent Application Publication No. 8-231723 [Patent Document 3] Special Publication No. 2016-536443 [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, the problem that the present invention aims to solve is to provide a method for producing polyarylene sulfide resin of stable quality by evaluating the monomer composition during polymerization in a simple and short time. [Means for solving the problem]

[0007] This disclosure includes the following: [1] A method for producing polyarylene sulfide resin by polymerizing a polyhalo-aromatic compound and a sulfur source in a reaction vessel in an organic polar solvent, (1) A step of measuring the concentration of at least one selected from the polyhalo-aromatic compound, sulfur source, organic polar solvent, and water in the gas phase portion of the reaction vessel, or in the condensate formed by the condensation of the gas phase portion, by spectroscopic analysis. A method for producing a polyarylene sulfide resin, comprising a step (2) of calculating an estimated value of the raw material concentration in the liquid phase part of the polymerization reaction system based on the measured value of the concentration and controlling the raw material ratio or reaction conditions. [2] The method for producing a polyarylene sulfide resin according to [1], wherein the technique used for spectroscopic analysis in the step (1) is at least one selected from the group consisting of near-infrared spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, and laser spectroscopy. [3] The method for producing a polyarylene sulfide resin according to [1] to [2], wherein the steps (1) and (2) are continuously performed during the progress of the reaction. [4] The raw material ratio or reaction conditions controlled in the step (2) include one or more selected from the group consisting of the molar ratio of the polyhaloaromatic compound and the sulfur source in the liquid phase part of the polymerization reaction system, the amount of the polyhaloaromatic compound contained in the liquid phase part of the polymerization reaction system, the amount of the sulfur source contained in the liquid phase part of the polymerization reaction system, the time of the polymerization reaction, the temperature of the liquid phase part, and the pressure of the gas phase part. The method for producing a polyarylene sulfide resin according to [1] to [3]. [Advantages of the Invention]

[0008] According to the present invention, it is possible to provide a method for producing a polyarylene sulfide resin with stable quality by simply and quickly evaluating the monomer composition during polymerization. [Embodiments for Carrying out the Invention]

[0009] Hereinafter, an embodiment of the present invention will be described in detail. However, the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Also, when a plurality of upper limit values and lower limit values are described for specific parameters, any upper limit value and lower limit value can be combined to form a suitable numerical range.

[0010] [Method for Producing PAS Resin] The method for producing PAS resin according to this embodiment is a method for producing PAS resin by polymerizing a polyhalo-aromatic compound and a sulfur source in a reaction vessel in an organic polar solvent, and is characterized by comprising: (1) measuring the concentration of at least one selected from the polyhalo-aromatic compound, sulfur source, organic polar solvent, and water in the gas phase portion of the reaction vessel or the condensate formed by the condensation of the gas phase portion by spectroscopic analysis; and (2) calculating an estimated value of the raw material concentration in the liquid phase portion of the polymerization reaction system based on the measured concentration and controlling the raw material ratio or reaction conditions. Details are described below.

[0011] In this specification, "sulfur source" means a sulfur compound containing sulfur atoms that can carry out a polymerization reaction to produce a PAS 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 source that reacts with the polyhalo-aromatic compound in the polymerization reaction solution. The resulting PAS 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.

[0012] Examples of organic polar solvents suitable for this embodiment include amides, ureas, and lactams such as 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-imidazolidinonic acid; sulfolanes such as sulfolane and dimethylsulfolane; nitriles such as benzonitrile; ketones such as methylphenyl ketone, and mixtures thereof. Among these, amides having an aliphatic cyclic structure such as N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, and 1,3-dimethyl-2-imidazolidinonic acid are preferred, and N-methyl-2-pyrrolidone is even more preferred.

[0013] Examples of polyhalo-aromatic compounds suitable for this embodiment include halogenated aromatic compounds having two or more halogen atoms directly bonded to an aromatic ring, specifically dihalo-aromatic compounds such as 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, as well as mixtures thereof. These compounds may also be block copolymerized. Among these, dihalogenated benzenes are preferred, and those containing 80 mol% or more of p-dichlorobenzene are particularly preferred. Furthermore, in order to increase the viscosity of the PAS resin by creating a branched structure, polyhalo-aromatic compounds having three or more halogen substituents in one molecule may be used as branching agents as desired. Examples of such polyhalo-aromatic compounds include 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, and 1,4,6-trichloronaphthalene. Furthermore, examples include polyhalo-aromatic compounds having functional groups with active hydrogens such as amino groups, thiol groups, and hydroxyl groups. Specifically, these 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 is replaced with a thiol group or a hydroxyl group in mixtures thereof.Furthermore, active hydrogen-containing polyhalo-aromatic compounds can also be used in which the hydrogen atoms bonded to the carbon atoms forming the aromatic ring in these active hydrogen-containing polyhalo-aromatic compounds are substituted with other inert groups, such as hydrocarbon groups like alkyl groups.

[0014] Among these various active hydrogen-containing polyhalo-aromatic compounds, the preferred is an active hydrogen-containing dihalo-aromatic compound, and the most preferred is dichloroaniline.

[0015] 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-chloro-3,5-dinitropyridine; and various dihalonitronaphthalenes.

[0016] Furthermore, in the manufacturing method of this embodiment, the sulfur source can be, for example, one or more sulfur sources selected from alkali metal sulfides, alkali metal hydroxides, hydrogen sulfide, and their precursors.

[0017] In the manufacturing method of this embodiment, the alkali metal sulfide includes lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. Such alkali metal sulfides can be used as hydrates, aqueous mixtures, or anhydrous products. Alkali metal sulfides can also be produced by the reaction of alkali metal hydroxides with alkali metal hydroxides. In addition, it is acceptable to add a small amount of alkali metal hydroxide to react with the alkali metal hydroxides and alkali metal thiosulfates that are usually present in trace amounts in the alkali metal sulfides.

[0018] In addition, examples of the alkali metal hydrosulfide include lithium hydrogen sulfide, sodium hydrogen sulfide, rubidium hydrogen sulfide, cesium hydrogen sulfide, and mixtures thereof. Such alkali metal hydrosulfides can be used as hydrates, aqueous mixtures, or anhydrides.

[0019] Further, the alkali metal hydrosulfide is used in combination with an alkali metal hydroxide. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, etc. These may be used alone or in combination of two or more. Among these, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferred because they are easily available, and sodium hydroxide is particularly preferred.

[0020] In the method for producing the PAS resin of the present embodiment, a sulfur-containing water source can also be used as a raw material. In that case, it is preferable to subject the sulfur-containing water source to a dehydration step in the presence of at least an aprotic polar solvent and then use it in the polymerization reaction of the PAS resin. When the charged amount of the aprotic polar solvent is small, for example, less than 1 mol per 1 mol of the sulfur atom of the sulfur source, it is preferable to dehydrate the sulfur-containing water source and the aprotic polar solvent in the presence of a polyhaloaromatic compound.

[0021] In the dehydration step of the sulfur-containing water source, at least an aprotic polar solvent, a hydrated alkali metal sulfide or a hydrated alkali metal hydrosulfide as the sulfur-containing water source, and an alkali metal hydroxide are charged into a reaction vessel equipped with a distillation apparatus, and heated to a temperature at which water is removed by azeotropy, specifically, in the range of 300°C or lower, preferably in the range of 80 to 220°C, more preferably in the range of 100 to 200°C, and water is discharged out of the system by distillation. In the dehydration step, it is preferable to dehydrate until the amount of water in the system for carrying out the polymerization reaction is in the range of 5 mol or less, more preferably 0.01 to 2.0 mol, per 1 mol of the sulfur atom of the sulfur source.

[0022] In the PAS polymerization process, the polymerization reaction of the PAS resin is carried out by reacting the alkali metal sulfide as a sulfur source with the polyhalo-aromatic compound in a reaction vessel in the presence of the above-mentioned organic polar solvent. Alternatively, the polymerization reaction of the PAS resin is carried out by reacting the alkali metal hydroxide and alkali metal hydroxide as a sulfur source with the polyhalo-aromatic compound in a reaction vessel in the presence of the above-mentioned organic polar solvent. The polymerization conditions are generally in the temperature range of 200 to 330°C, and the pressure should be in a range that substantially maintains the polymerization solvent and the polyhalo-aromatic compound, which is the polymerization monomer, in the liquid phase, and is generally selected from the range of 0.1 to 20 MPa, preferably from 0.1 to 2 MPa. The amount of polyhalo-aromatic compound to be charged is prepared in the range of 0.2 moles to 5.0 moles, preferably from 0.8 to 1.3 moles, and more preferably from 0.9 to 1.1 moles, per mole of sulfur atoms of the sulfur source. Furthermore, the amount of aprotic polar solvent charged is adjusted to be in the range of 1.0 to 6.0 moles, preferably 2.5 to 4.5 moles, per mole of sulfur atoms in the sulfur source. The polymerization reaction is preferably carried out in the presence of a small amount of water, and the proportion is preferably adjusted as appropriate in balance with the polymerization method, the molecular weight of the obtained polymer, and productivity. Specifically, the dehydration operation is carried out to a range of 2.0 moles or less, preferably 1.6 moles or less, per mole of sulfur atoms in the sulfur source. However, if the dehydration operation is carried out in the presence of a polyhalo-aromatic compound (for example, the method in "5)" in the specific embodiment below), the dehydration operation should be carried out to a range of 0.9 moles or less, preferably 0.05 to 0.3 moles, more preferably 0.01 to 0.02 moles or less.

[0023] Specific embodiments of polymerizing a sulfur source and a polyhalo-aromatic compound in the presence of the aforementioned aprotic polar solvent include, for example, 1) A method using polymerization aids such as alkali metal carboxylates or lithium halides. 2) A method using branching agents such as aromatic polyhalogen compounds, 3) A method in which polymerization is carried out in the presence of a small amount of water, and then water is added to further polymerize the molecule. 4) A method in which, during the reaction of an alkali metal sulfide with an aromatic dihalogen compound, the gas phase portion of the reaction vessel is cooled to condense a portion of the gas phase inside the reaction vessel and reflux it into the liquid phase. 5) A method for producing PAS resin, which has the following essential manufacturing steps: 1) Reacting an alkali metal sulfide, or a hydrated alkali metal hydroxide and alkali metal hydroxide, with an amide, urea, or lactam having an aliphatic cyclic structure in the presence of a polyhalo-aromatic compound, while dehydrating, to produce a slurry containing a solid alkali metal sulfide; 2) After producing the slurry, adding a polar organic solvent such as NMP and removing the water by distillation to dehydrate the slurry; and 3) Reacting a polyhalo-aromatic compound, an alkali metal hydroxide, and an alkali metal salt of the hydrolysis product of the amide, urea, or lactam having an aliphatic cyclic structure in the slurry obtained through the dehydration step, at a rate of 0.02 moles or less of water present in the reaction system per mole of a polar organic solvent such as NMP, to carry out polymerization.

[0024] There are no particular limitations on the post-treatment method for the reaction mixture containing the PAS resin obtained by the polymerization step. For example, (post-treatment 1) after the polymerization reaction is complete, first the reaction mixture is treated as is, or an acid or base is added, and the solvent is removed under reduced pressure or atmospheric pressure. Then the solid after solvent removal is washed once or twice or more with a solvent such as water, the reaction solvent (or an organic solvent having equivalent solubility to the low molecular weight polymer), acetone, methyl ethyl ketone, or alcohols, and then neutralized, washed with water, filtered, and dried. Or, (post-treatment 2) after the polymerization reaction is complete, the reaction mixture is treated with a solvent such as water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, or aliphatic hydrocarbons (solubilable in the polymerization solvent used and poorly soluble in at least PAS). Methods include adding a solvent (as a medium) as a precipitating agent to precipitate solid products such as PAS and inorganic salts, then filtering, washing, and drying them; (Post-treatment 3) After the polymerization reaction is complete, adding the reaction solvent (or an organic solvent having equivalent solubility to the low molecular weight polymer) to the reaction mixture and stirring, then filtering to remove the low molecular weight polymer, washing once or twice or more with a solvent such as water, acetone, methyl ethyl ketone, or alcohols, then neutralizing, washing with water, filtering, and drying; (Post-treatment 4) After the polymerization reaction is complete, adding water to the reaction mixture and washing with water, filtering, adding acid during water washing as needed for acid treatment, and then drying; (Post-treatment 5) After the polymerization reaction is complete, filtering the reaction mixture, washing once or twice or more with the reaction solvent as needed, and then further washing with water, filtering, and drying.

[0025] Furthermore, in the post-treatment methods exemplified above (Post-treatment 1) to (Post-treatment 5), the drying of the PAS resin may be carried out in a vacuum, in air, or in an inert gas atmosphere such as nitrogen.

[0026] In this way, by polymerizing a dihalo-aromatic compound with a sulfur source in an organic polar solvent, PAS resin is obtained as the product, but PAS oligomers are also produced as by-products. Other substances contained after the reaction may include by-products such as alkali metal-containing inorganic salts, carboxyalkylamino group-containing compounds, terminal SH group-containing compounds, unreacted raw materials, and water.

[0027] The method for producing the polyarylene sulfide resin described herein involves performing the following steps (1) and (2) in the method for producing the PAS resin described above.

[0028] ·Process (1) Step (1) is a step of measuring the concentration of at least one selected from the polyhalo-aromatic compound, sulfur source, organic polar solvent, and water in the gas phase portion of the reaction vessel, or in the condensate formed by the condensation of the gas phase portion, by spectroscopic analysis.

[0029] During a polymerization reaction, the gas phase of the reaction vessel contains some of the reaction raw materials, products, and by-products in the form of vapor, gas, or fine particles. Specifically, for example, polyhalo-aromatic compounds, hydrogen sulfide, organic polar solvents, and water are present in the gas phase. In this process, the gas phase or at least a portion of it is recovered, and the condensate obtained by cooling is the target of measurement. The cooling temperature is preferably 100°C or lower, and more preferably room temperature (23°C) or lower. By cooling to this temperature, the components contained in the gas phase condense to obtain a liquid.

[0030] The method for recovering the gas phase from the reaction vessel is not particularly limited as long as it does not impair the effects of the present invention, but for example, it can be recovered through a pipe connected to the reaction vessel. For this reason, it is preferable that the reaction vessel used in this embodiment is equipped with a gas phase recovery device and a cooling device at the top (above the liquid level). When measuring the gas phase as is, it may be measured directly in the reaction vessel, or it may be recovered and measured first.

[0031] The spectroscopic analysis method that can be used in this embodiment is any method that can quantify the concentration of the polyhalo-aromatic compound, the sulfur source, or both. Examples of applicable spectroscopic analysis methods 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 operation 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 quantification of the concentration of each component in a short time.

[0032] The apparatus used for spectroscopic analysis in this process is not particularly limited; any publicly known and publicly available apparatus capable of measuring spectra and analyzing the measured spectra can be used, and measurements can be performed according to conventional methods. More specifically, for example, a spectroscopic analyzer equipped with at least a measurement terminal, a spectrometer, an analysis device, and equipment for connecting the measurement terminal and the spectrometer (e.g., optical fiber) can be used. The analysis device may be built into the spectroscopic analyzer or may be located remotely if connected online. Furthermore, it is preferable that the spectrometer is capable of continuous measurement while the solution is flowing, not just batch measurement. In addition, from a safety standpoint, it is preferable that it has an explosion-proof structure.

[0033] While there are no particular limitations on the duration of a single measurement using spectroscopic analysis, from the viewpoint of balancing measurement accuracy and immediacy, it is preferably 5 minutes or less, more preferably 1 minute or less, and even more preferably 30 seconds or less. Furthermore, while there are no particular limitations on the interval between each measurement in spectroscopic analysis, it is preferably 1 minute or less, more preferably 30 seconds or less, and even more preferably 1 second or less, and it is particularly preferable to perform the measurements continuously. By taking measurements at short intervals, changes in the system conditions can be immediately detected, feedback control to the reactor can be expedited, and a product with consistent quality can be obtained more efficiently.

[0034] In this process, the substances whose concentrations are calculated in the gas phase or the condensate include, specifically, polyhalo-aromatic compounds, hydrogen sulfide, organic polar solvents, and water. While it is sufficient to calculate the concentration of at least one of these substances, two or more may be calculated. Since hydrogen sulfide is generated in the polymerization solution by an equilibrium reaction of the sulfur source, the concentration of the sulfur source can be calculated in the next step by measuring the hydrogen sulfide concentration in the gas phase or the condensate.

[0035] 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.

[0036] ·Process (2) Step (2) is a step in which an estimated value of the raw material concentration in the liquid phase of the polymerization reaction system is calculated based on the concentration measurement value obtained in step (1), and the raw material ratio or reaction conditions are controlled.

[0037] Based on a good correlation between the concentrations of each component (polyhalo-aromatic compound, hydrogen sulfide, organic polar solvent, water) in the gas phase or condensate and the concentrations of each component (polyhalo-aromatic compound, hydrogen sulfide, organic polar solvent, water) in the liquid phase of the polymerization reaction system, estimated concentrations of the polyhalo-aromatic compound and sulfur source in the liquid phase 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 concentrations of each component can be obtained based on that calibration curve. The concentration of the sulfur source in the liquid phase may be, for example, the total concentration of one or more sulfur sources selected from alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0038] Calibration curves are created, for example, by a method that includes measuring the concentrations of polyhalo-aromatic compounds and sulfur sources in the liquid phase and in the gas phase or condensate during polymerization reaction tests using the reactor itself or a reactor having substantially the same configuration as the reactor used to produce PAS resin, while obtaining estimated 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 liquid phase and the concentration of polyhalo-aromatic compounds or sulfur sources 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 to produce 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, but 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 sources in polymerization reaction tests.

[0039] 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.

[0040] The raw material ratio that can be controlled in this process is the ratio of polyhalo-aromatic compounds to sulfur sources. Adjusting the molar ratio of polyhalo-aromatic compounds to sulfur sources in the liquid phase includes, for example, calculating an estimated molar ratio of polyhalo-aromatic compounds to sulfur sources in the liquid phase from estimated amounts of polyhalo-aromatic compounds and sulfur sources in the liquid phase, and adjusting the amounts of polyhalo-aromatic compounds, sulfur sources, or both in the liquid phase 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. In this case, the polyhalo-aromatic compounds and sulfur sources can also be added after being dissolved in an organic polar solvent.

[0041] Furthermore, the reaction conditions that can be controlled in this process include, for example, the time of the polymerization reaction, the temperature of the liquid phase, the pressure of the gas phase, the heating rate, the cooling rate, and the rotation speed of the stirrer installed in the polymerization vessel. Such control is preferably performed automatically by a process computer from the viewpoint of product stabilization or manufacturing efficiency. In other words, it is preferable to control using a process computer to which the spectroscopic analyzer and the calculation device are connected.

[0042] Furthermore, if the raw material ratio is to be adjusted in this process, the coagulation liquid used in process (1) may be used.

[0043] In the manufacturing method according to this embodiment, it is preferable from the viewpoint of improving and stabilizing the quality of the resulting PAS resin that steps (1) and (2) are carried out continuously while the reaction is in progress. Note that steps (1) and (2) being carried out continuously while the reaction is in progress means that steps (1) and (2) are repeated many times between the start and end of the polymerization reaction. The frequency and interval of the repetition of steps (1) and (2) are not particularly limited and can be selected as appropriate. The substance measured by spectroscopic analysis in step (1) may be the same or different each time. The method used for spectroscopic analysis in step (1) may be the same or different each time. The raw material ratio or reaction conditions controlled in step (2) may be the same or different each time.

[0044] <Composition / Applications, etc.> The PAS resin obtained by the manufacturing method according to this embodiment can be mixed with additives such as mold release agents, colorants, heat stabilizers, UV stabilizers, foaming agents, rust inhibitors, flame retardants, lubricants, coupling agents, and fillers, as long as the effects of the present invention are not impaired. As fillers, known and conventional materials can be used as long as they do not impair the effects of the present invention, and examples include inorganic fillers of various shapes, such as fibrous materials and non-fibrous materials such as granular or plate-shaped materials. Specifically, fibrous fillers such as glass fibers, carbon fibers, silane glass fibers, ceramic fibers, aramid fibers, metal fibers, potassium titanate, silicon carbide, calcium silicate, wollastonite, and other fibers and natural fibers can be used, as well as non-fibrous fillers such as glass beads, glass flakes, barium sulfate, clay, pyrophyllite, bentonite, sericite, mica, talc, attapulgite, ferrite, calcium carbonate, zeolite, milled fiber, and calcium sulfate.

[0045] The PAS resin obtained by the manufacturing method according to this embodiment can also be used by mixing it with the following synthetic resins and elastomers, to the extent that the effects of the present invention are not impaired. Examples of these synthetic resins include polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylene, polyethylene, polypropylene, polytetrafluoroethylene, polyhexafluoropropylene, polystyrene, ABS resin, epoxy resin, silicone resin, phenolic resin, urethane resin, liquid crystal polymer, etc. Examples of elastomers include polyolefin rubber, fluororubber, silicone rubber, etc.

[0046] Furthermore, the PAS resin obtained by the manufacturing method according to this embodiment exhibits excellent heat resistance, moldability, and dimensional stability when subjected to various melting processes such as injection molding, extrusion molding, compression molding, and blow molding. For this reason, it can be widely used as, for example, electrical and electronic components such as connectors, printed circuit boards, and encapsulated molded products; automotive parts such as lamp reflectors and various electrical components; interior materials for various buildings, aircraft, and automobiles; injection-molded and compression-molded products such as precision parts such as OA equipment parts, camera parts, and watch parts; or extrusion-molded and pultruded products such as fibers, films, sheets, and pipes. [Examples]

[0047] The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting. Unless otherwise specified, "%" and "parts" refer to mass.

[0048] <Rating>

[0049] (1) Measurement of melt viscosity (V6) Using a Shimadzu CFT-500D flow tester, the temperature was set to 300°C and the load to 20 kgf / cm². 2 The melt viscosity was measured after holding the mixture for 6 minutes at a ratio of L / D = 10 (mm) / 1 (mm).

[0050] (2) Spectroscopic analysis of the condensate (gas phase) The condensate obtained by cooling the sampled gas phase to room temperature (23°C) was used as the sample, and its components were quantified by near-infrared spectroscopy. A Bruker "MPA" was used, with wavelengths of 780-2500 nm and a measurement time of 15 seconds. From the obtained spectra, the content of components (p-DCB amount, hydrogen sulfide) in the measured sample was determined using a calibration curve. The calibration curve was created using the following method. Calibration curves were created by performing near-infrared spectroscopy measurements on 10 solutions each of p-DCB and hydrogen sulfide at different concentrations. Specifically, the absorbance spectral data at wavelengths of 780 to 2500 nm were subjected to second-order differential analysis, followed by PLS regression analysis to plot the relative intensity ratios of absorbance for each concentration.

[0051] (3) Calculation of raw material concentration in the liquid phase of the polymerization reaction system The concentration of the raw materials in the liquid phase during the polymerization reaction was determined from the content of the components (amount of p-DCB, hydrogen sulfide) in the condensate (gas phase) obtained in (2) using the calibration curve shown below. The calibration curve was created using the following method. Prior to the experiment, samples were taken of the liquid and gas phases during the reaction process in reaction systems with different reaction conditions. The reaction slurry from the liquid phase and the condensate from the gas phase, obtained by cooling each to room temperature (23°C), were used as samples. Using gas chromatography (Shimadzu GC2014) and silver nitrate titration (Kyoto Electronics Industrial AT710), the amount of p-DCB and sulfur source (S) in the liquid phase and the p-DCB and sulfur source (S) in the gas phase condensate were calculated. Calibration curves were created by plotting the relative relationships between the calculated p-DCB and sulfur source (S) in the liquid phase and gas phase condensates, respectively.

[0052] <Examples 1-2, Comparative Examples 1-2>

[0053] [Example 1] 294.0 g (2.0 mol) of p-dichlorobenzene (hereinafter abbreviated as p-DCB) and 779.0 g (7.9 mol) of N-methylpyrrolidone (hereinafter abbreviated as NMP) were charged into a 2 L autoclave reactor at room temperature, and the temperature was raised to 220°C under a nitrogen atmosphere while stirring. While maintaining 220°C, 233.6 g (2.0 mol) of 48% NaSH aqueous solution and 166.7 g (2.0 mol) of 48% NaOH aqueous solution were continuously supplied from the supply line using a metering pump over a period of 5 hours. Simultaneously, water was continuously removed from the reactor using a distillation apparatus connected to the reactor, while controlling the pressure to a gauge pressure of 0.20 MPa with a pressure regulating valve. Furthermore, the p-DCB in the removed liquid was separated in a standing tank and returned to the reactor. In addition, the gas from the distillation apparatus was passed through 0.5 kg of 8% sodium hydroxide aqueous solution downstream of the pressure regulating valve to completely absorb and recover hydrogen sulfide before being exhausted. After supplying 48% NaSH aqueous solution and 48% NaOH aqueous solution over 5 hours, the gas phase in the reaction system was sampled. The sampled gas phase was cooled to room temperature (23°C) to obtain a condensate, and near-infrared spectroscopy was performed to calculate the amount of p-DCB and hydrogen sulfide in the condensate (gas phase). Based on the calculated concentrations of substances in the condensate, the raw material concentration in the liquid phase of the polymerization reaction system was calculated using a pre-prepared calibration curve, and the composition ratio (molar ratio) of the raw materials in the polymerization reaction system was found to be p-DCB / S (sulfur source) = 99 / 100. After reducing the pressure to 0.10 MPa, the reaction system was sealed, and 0.29 g (0.2 mol%) of p-DCB was added to the reaction apparatus from the standing tank to correct the composition ratio to p-DCB / S = 100:100. The time required from sampling to correction was 15 minutes. The polymerization solution in the reaction apparatus was then heated to 230°C, stirred for 2 hours, and then cooled to stop the reaction. The melt viscosity (V6) of the PPS resin contained in the slurry after the reaction was 52 Pa·s.

[0054] [Example 2] A polymerization operation was carried out using the same raw materials as in Example 1 in a separate batch, and the gas phase in the reaction system was sampled. After cooling the sampled gas phase to room temperature (23°C) to obtain a condensate, near-infrared spectroscopy was performed to calculate the amount of p-DCB and hydrogen sulfide in the condensate (gas phase). Based on the calculated concentrations of substances in the condensate, the raw material concentration in the liquid phase of the polymerization reaction system was calculated using a pre-prepared calibration curve, and the composition ratio (molar ratio) of the raw materials in the polymerization reaction system was found to be p-DCB / (sulfur source)S = 102:100. In order to make this composition ratio p-DCB / S = 100:100, 0.59 g (0.4 mol%) of p-DCB separated into the standing tank during the process of reducing the pressure to 0.10 MPa was not returned to the reaction apparatus, and the reaction system was sealed, and the composition ratio (molar ratio) of the polymerization reaction system was adjusted to p-DCB / S = 100:100, thereby correcting the reaction system. The time required from sampling to correction was 15 minutes. The polymerization solution in the reaction apparatus was then heated to 230°C, stirred for 2 hours, and then cooled to stop the reaction. The melt viscosity (V6) of the PPS resin contained in the slurry after the reaction was 49 Pa·s.

[0055] [Comparative Example 1] Polymerization was carried out using the same raw materials as in Example 1. After supplying the raw materials, the pressure was reduced to 0.10 MPa, and the liquid phase in the reaction system was sampled. Then, the polymerization solution in the reactor was heated to 230°C and stirred for 2 hours. During this time, the sampled liquid phase reaction slurry was cooled to room temperature (23°C), and the slurry was analyzed using gas chromatography (Shimadzu GC2014) and silver nitrate titration (Kyoto Electronics Industrial AT710) to calculate the p-DCB / S (sulfur source) in the liquid phase. The result showed that the composition ratio (molar ratio) of the raw materials in the polymerization reaction system was p-DCB / S (sulfur source) = 99 / 100. Therefore, to correct this composition ratio to p-DCB / S = 100:100, 0.29 g (0.2 mol%) of p-DCB was added to the reactor from the standing tank. 120 minutes were required from sampling to correction, and continuing heating any further would exceed the reaction time, so the reaction was stopped by cooling immediately after the correction. The melt viscosity (V6) of the PPS resin contained in the slurry after the reaction was 65 Pa·s.

[0056] [Comparative Example 2] Polymerization was carried out using the same raw materials as in Example 1. After supplying the raw materials, the pressure was reduced to 0.10 MPa, and the liquid phase in the reaction system was sampled. The polymerization solution in the reaction apparatus was then heated to 230°C and stirred for 2 hours. During this time, the sampled liquid phase reaction slurry was cooled to room temperature (23°C), and the slurry was analyzed using gas chromatography (Shimadzu GC2014) and silver nitrate titration (Kyoto Electronics Industrial AT710) to calculate the p-DCB / S (sulfur source) in the liquid phase. The result showed that the composition ratio (molar ratio) of the raw materials in the polymerization reaction system was p-DCB / S (sulfur source) = 102 / 100. Since 120 minutes were required from sampling to correction, exceeding the reaction time, it was not possible to correct the composition ratio to p-DCB / S = 100:100, and the reaction was stopped by cooling. The melt viscosity (V6) of the PPS resin contained in the slurry after the reaction was 22 Pa·s.

[0057] [Table 1]

Claims

1. In a method for producing polyarylene sulfide resin by polymerizing a polyhalo-aromatic compound and a sulfur source in a reaction vessel in an organic polar solvent, (1) A step of measuring the concentration of at least one selected from the polyhalo-aromatic compound, sulfur source, organic polar solvent, and water in the gas phase portion of the reaction vessel, or in the condensate formed by the condensation of the gas phase portion, by spectroscopic analysis. A method for producing polyarylene sulfide resin, comprising the step (2) of calculating an estimated value of the raw material concentration in the liquid phase of the polymerization reaction system based on the measured concentration and controlling the raw material ratio or reaction conditions.

2. A method for producing a polyarylene sulfide resin according to claim 1, wherein the method used for spectroscopic analysis in step (1) is at least one selected from the group consisting of near-infrared spectroscopy, Raman spectroscopy, X-ray fluorescence spectroscopy, and laser spectroscopy.

3. The method for producing a polyarylene sulfide resin according to claim 1, wherein steps (1) and (2) are carried out continuously while the reaction is progressing.

4. The method for producing a polyarylene sulfide resin according to claim 1, wherein the raw material ratio or reaction conditions controlled in step (2) include one or more selected from the group consisting of the molar ratio of the polyhalo-aromatic compound to the sulfur source in the liquid phase of the polymerization reaction system, the amount of the polyhalo-aromatic compound contained in the liquid phase of the polymerization reaction system, the amount of the sulfur source contained in the liquid phase of the polymerization reaction system, the time of the polymerization reaction, the temperature of the liquid phase, and the pressure of the gas phase.

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