Method for producing polyarylene sulfide resin and method for measuring it

Abstract

To provide a method for producing polyarylene sulfide (PAS) resin and a method for measuring the concentration of sulfur compounds using a measurement method that can measure the concentration of sulfur compounds with high accuracy in a short time. [Solution] A method for producing PAS resin, comprising reacting a polyhalo-aromatic compound with (i) an alkali metal sulfide, or (ii) an alkali metal hydroxide and an alkali metal hydroxide in an organic polar solvent, the method comprising measuring the concentration of the alkali metal sulfide or the alkali metal hydroxide by near-infrared spectroscopy, and adjusting the raw material ratio or polymerization reaction conditions based on the concentration.

Description

Technical Field

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

Background Art

[0002] Polyarylene sulfide resins (hereinafter sometimes referred to as PAS resins) typified by polyphenylene sulfide resin (hereinafter sometimes referred to as PPS resin) are excellent in heat resistance, chemical resistance, etc., and are widely used as super engineering plastics in applications such as electric and electronic parts, automotive parts, water heater parts, fibers, and films.

[0003] PPS resin is a resin obtained by a condensation polymerization reaction using sulfur compounds such as alkali metal sulfides and alkali metal hydrosulfides and polyhalo aromatic compounds as raw materials. In recent years, the requirements for the quality of PPS resin have become stricter, and in order to obtain a high-quality resin, it is essential to more precisely control the blending ratio of the polymerization raw materials. Therefore, a technique for measuring the concentration (purity) of the sulfur compound as a raw material with high precision has been demanded, but there has been no standardized procedure.

[0004] Also, from the viewpoints of environmental response and production rationalization, studies have been underway to recover hydrogen sulfide scattered in the production process of PPS resin and reuse it as a sulfur compound (for example, Patent Document 1, etc.), and a method that can measure the concentration (purity) of the sulfur compound simply and with high precision in a short time has been demanded.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the problem that the present invention aims to solve is to provide a method for producing PAS resin and a method for measuring the concentration of sulfur compounds using a measurement method that can measure the concentration of sulfur compounds with high accuracy in a short amount of time. [Means for solving the problem]

[0007] After conducting various studies, the inventors discovered that the above problem could be solved by using near-infrared spectroscopy.

[0008] In other words, the present invention encompasses the following aspects. [1] A method for producing a polyarylene sulfide resin, comprising reacting a polyhalo-aromatic compound with (i) an alkali metal sulfide, or (ii) an alkali metal hydroxide and an alkali metal hydroxide in an organic polar solvent, the method comprising measuring the concentration of the alkali metal sulfide or the alkali metal hydroxide by near-infrared spectroscopy, and adjusting the raw material ratio or polymerization reaction conditions based on the concentration. [2] The method for producing a polyarylene sulfide resin according to [1], wherein the raw material ratio or reaction conditions include one or more selected from the group consisting of the molar ratio of the polyhalo-aromatic compound to the alkali metal sulfide, the molar ratio of the polyhalo-aromatic compound to the alkali metal hydroxide, the molar ratio of the alkali metal hydroxide to the alkali metal hydroxide, the amount of the organic polar solvent, the time of the polymerization reaction, the temperature of the liquid phase during the polymerization reaction, and the pressure of the gas phase during the polymerization reaction. [3] A method for producing a polyarylene sulfide resin according to [1], wherein at least one of the alkali metal sulfide or alkali metal hydroxide contains recycled raw materials. [4] A method for measuring the concentration of a sulfur compound using spectroscopic analysis, wherein the sulfur compound contains at least an alkali metal sulfide or alkali metal hydrosulfide, and the spectroscopic analysis is near-infrared spectroscopy. [5] The measurement method according to [4], wherein the sulfur compound is recycled or recovered from one or more selected from the group consisting of waste, waste liquid, exhaust gas, and vapor generated when manufacturing polyarylene sulfide resin.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a method for producing a PAS resin and a measuring method using a measuring method capable of simply and accurately measuring the concentration of a sulfur compound in a short time with high precision.

Embodiments for Carrying Out the Invention

[0010] 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.

[0011] <Method for Producing PAS Resin> The method for producing a PAS resin according to this embodiment is a method for producing a polyarylene sulfide resin in which a polyhaloaromatic compound and (i) an alkali metal sulfide or (ii) an alkali metal hydrosulfide and an alkali metal hydroxide are reacted in an organic polar solvent, and includes measuring the concentration of the alkali metal sulfide or the alkali metal hydrosulfide by near-infrared spectroscopy and adjusting the raw material ratio or the polymerization reaction conditions based on the concentration. This will be described in detail below.

[0012] As an example of the polymerization step of this embodiment, a step of obtaining a reaction mixture (slurry) containing a PAS resin obtained by reacting at least one polyhalogenoaromatic compound and at least one sulfur compound in a polar solvent (for example, a polar organic solvent) under appropriate polymerization conditions will be described below. In addition, in this embodiment, a form in which the reaction mixture (slurry) is obtained by reacting while continuously or intermittently adding a polyhalogenoaromatic compound and / or an organic solvent in the presence of a sulfidizing agent and an organic solvent is also included.

[0013] In this invention, the polyhalogenoaromatic compound is, for example, a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic ring. Specifically, examples include dihaloaromatic 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 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 present invention, alkali metal sulfides or alkali hydroxides and alkali metal hydroxides (hereinafter sometimes collectively referred to as sulfidating agents) are used as raw materials.

[0017] In the present invention, 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 forms. Alkali metal sulfides can also be obtained 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 hydrosulfide, sodium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures thereof. Such alkali metal hydrosulfides can be used as hydrates, aqueous mixtures, or anhydrides.

[0019] 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 invention, a hydrous sulfidizing agent can also be used as a raw material. In that case, it is preferable to subject the hydrous sulfidizing agent 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 sulfidizing agent, it is preferable to dehydrate the hydrous sulfidizing agent and the aprotic polar solvent in the presence of a polyhaloaromatic compound.

[0021] In the dehydration step of the hydrous sulfidizing agent, at least an aprotic polar solvent, a hydrous alkali metal sulfide or a hydrous alkali metal hydrosulfide as the hydrous sulfidizing agent, 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 sulfidizing agent.

[0022] The sulfidizing agent may be a virgin raw material, but it may also be a recycled or recovered raw material. For example, it may be recycled or recovered from one or more selected from the group consisting of waste, waste liquid, exhaust gas, and vapor generated when manufacturing PAS resin. The waste, waste liquid, exhaust gas, and vapor generated when polymerizing PAS resin may be, for example, solid waste containing by-products and unreacted raw materials, organic polar solvents containing unreacted raw materials recovered after polymerization, washing solutions containing unreacted raw materials recovered after the washing process, exhaust gas and vapor generated during the polymerization reaction or during the dewatering of the polymerization raw materials, and their condensates, etc. The recycling and recovery methods are not particularly limited.

[0023] In addition, examples of organic polar solvents in the present invention 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. The organic polar solvent can be a virgin raw material, but it can also be a recycled or recovered raw material.

[0024] In the PAS polymerization process, the polymerization reaction of the PAS resin involves reacting the alkali metal sulfide and the polyhalo-aromatic compound as sulfidating agents in the presence of these organic polar solvents. Alternatively, the polymerization reaction of the PAS resin involves reacting the alkali metal hydroxide and alkali metal hydroxide as sulfidating agents with the polyhalo-aromatic compound in the presence of these organic polar solvents. 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 sulfidating agent. 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 of the sulfidating agent. 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 consideration of the polymerization method, the molecular weight of the obtained polymer, and productivity. Specifically, the dehydration operation is carried out so that the amount of water is in the range of 2.0 moles or less, preferably 1.6 moles or less, per mole of sulfur atoms of the sulfidating agent. 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 amount of water should be in the range of 0.9 moles or less, preferably 0.05 to 0.3 moles, more preferably 0.01 to 0.02 moles or less.

[0025] Specific embodiments of polymerizing a sulfidating agent 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.

[0026] In this embodiment, the manufacturing process for PAS resin may be a batch process or a continuous process.

[0027] The method for producing the PAS resin described herein includes measuring the concentration of the alkali metal sulfide or alkali metal hydrosulfide described above by near-infrared spectroscopy.

[0028] The spectroscopic analysis applicable in this embodiment is near-infrared spectroscopy (NIR) using near-infrared light. Preferably, the system is capable of measuring transmitted and diffusely reflected light, and is equipped with a liquid measurement module. The spectrum obtained by the analysis is preferably a Fourier transform spectrum. By using such near-infrared spectroscopy, the concentration of the sulfur compound can be evaluated quickly and with high accuracy. Furthermore, near-infrared spectroscopy does not require special sample preparation and is suitable for in-line measurement.

[0029] In this embodiment, the conditions for near-infrared spectroscopy are not limited, but may be as follows: Measurement container: Glass vial Measurement method: Transmission method Measurement temperature: room temperature (23℃) Total number of times: 50 Resolution: 16cm -1 Measurement wavelength: 4000-10000cm -1

[0030] In this embodiment, the measurement cell used for near-infrared spectroscopy is not particularly limited. It can be used depending on the sample, measurement method, and measurement situation, and analysis may be performed not only offline but also atline, online, or inline. Near-infrared spectroscopy can be performed by taking a sample and measuring it with a near-infrared analyzer in an analysis laboratory, but it is also possible to perform continuous measurements by integrating a near-infrared analyzer into the PAS resin manufacturing line. In particular, inline analysis is preferable because it reduces the risk of workers coming into contact with highly toxic alkali metal sulfides and alkali metal hydrosulfides, and because it allows for easy real-time and continuous analysis.

[0031] The near-infrared spectral data used in this embodiment may be the original spectral data, but it is preferable to use processed original spectral data. Examples of data processing methods include multi-order derivatives (first, second, third, etc.), smoothing, spectral subtraction, normalization, MSC correction, and standardization (SNV correction). These processing methods may be used individually or in combination. Among these, multi-order derivatives, smoothing, normalization, and standardization are particularly preferred processing methods.

[0032] The method for calculating the purity (concentration) of sulfur compounds from the results of near-infrared spectroscopy 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 spectroscopy using a pre-prepared calibration model. The calibration model can be created using conventional quantitative analysis methods by multivariate analysis. For example, a calibration model can be created from the spectral intensity at a specific wavelength 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.

[0033] 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.

[0034] 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.

[0035] The method for producing the PAS resin described herein includes measuring the concentration of the alkali metal sulfide or alkali metal hydroxide described above by near-infrared spectroscopy, and adjusting the raw material ratio or polymerization reaction conditions based on the measurement results. Examples of raw material ratios include the molar ratio of the polyhalo-aromatic compound to the alkali metal sulfide, the molar ratio of the polyhalo-aromatic compound to the alkali metal hydroxide, and the molar ratio of the alkali metal hydroxide to the alkali metal hydroxide. The amount (ratio) of the polymerization raw materials and the organic polar solvent used as the polymerization solvent is also included. Examples of polymerization reaction conditions include the time of the polymerization reaction, the temperature of the liquid phase during the polymerization reaction, and the pressure of the gas phase during the polymerization reaction.

[0036] By adjusting the raw material ratios or polymerization reaction conditions as described above, the physical properties of the resulting PAS resin can be precisely controlled. For example, melt viscosity, molecular weight, amount of terminal functional groups, amount of metal ions, molecular structure, crystallization rate, crosslinking rate, etc., can be controlled.

[0037] The mixture containing the PAS resin obtained through the polymerization reaction described above may be used as PAS resin powder after further purification and drying, or it may be further washed, followed by solid-liquid separation and drying to prepare a powdered or granular PAS resin. Furthermore, the obtained powdered or granular PAS resin can be heat-treated to produce a crosslinked PAS resin.

[0038] While there are no particular restrictions on the purification method, examples include the following purification processes 1 to 5. Purification process 1: After the polymerization reaction is complete, the reaction mixture (slurry) is first removed under reduced pressure or atmospheric pressure, either as is or after adding an acid or base. Then, the solid matter (crude PAS resin) remaining after solvent removal is washed once or twice or more with a washing solution such as (hot) water, the reaction solvent (or an organic solvent with equivalent solubility to the low molecular weight polymer), acetone, methyl ethyl ketone, or alcohols. Further neutralization, washing with (hot) water, filtration, and drying are performed. Purification process 2: After the polymerization reaction is complete, a solvent such as (hot) water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, or aliphatic hydrocarbons (solvents that are soluble in the organic solvent used for polymerization and are poor solvents for at least PAS resin) is added to the reaction mixture (slurry) as a precipitating agent to settle the solid matter (crude PAS resin) containing PAS resin and inorganic salts, etc., and then these are filtered, washed, and dried. Purification process 3: After the polymerization reaction is complete, the reaction mixture (slurry) is mixed with the reaction solvent (or an organic solvent having equivalent solubility to the low molecular weight polymer) and stirred. The solid material (crude PAS resin) obtained by filtering to remove the low molecular weight polymer is then washed once or twice or more with a washing solution such as (hot) water, acetone, methyl ethyl ketone, or alcohols, followed by neutralization, (hot) water washing, filtration, and drying. Purification process 4: After the polymerization reaction is complete, (hot) water is added to the reaction mixture (slurry) as a washing solution for (hot) water washing, and the resulting solid (crude PAS resin) is filtered. If necessary, acid is added during (hot) water washing for acid treatment, and then the mixture is dried. Purification process 5: After the polymerization reaction is complete, the reaction mixture (slurry) is filtered to obtain a solid (crude PAS resin), which may be washed once or twice or more with a reaction solvent as a washing solution, and further washed with (hot) water, filtered, and dried. In addition, in the purification processes exemplified in the above purification processes 1 to 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.

[0039] The purification method preferably involves adding a washing solution to a reaction mixture (slurry) containing PAS resin obtained by a polymerization reaction, or to the crude PAS resin which is the solid component of the reaction mixture (slurry), followed by washing, filtering, and drying. Furthermore, the washing, filtering, and drying processes, each of which involves adding the washing solution, can be performed at least once or multiple times. In this specification, "crude PAS resin" refers to the solid content obtained by separating the reaction mixture (slurry) containing the PAS resin obtained in the polymerization process one or more times using solid-liquid separation.

[0040] The above cleaning treatment is not particularly limited, and acid cleaning, (hot) water cleaning, and solution cleaning with the above cleaning solution or reaction solvent can be performed once or multiple times. The cleaning solutions that can be used in the cleaning treatment in this embodiment are not particularly limited, and examples include water, hot water, acid solution, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dimethyl sulfone, acetone, methyl ethyl ketone, diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, tetrahydrofuran, chloroform, methylene chloride, trichloroethylene, dichloroethylene, dichloroethane, dichloroethane, chlorobenzene, methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, benzene, toluene, xylene, etc. The above cleaning solutions may be used individually or as a mixture of two or more.

[0041] The temperature of the above-mentioned cleaning solution is preferably 140 to 260°C. A preferred method of cleaning with a cleaning solution at 140 to 260°C is to clean the crude PAS resin while pressurizing the cleaning solution (for example, in a pressure range of 0.1 to 5 MPa).

[0042] The above filtration process is not particularly limited as long as it can separate solid and liquid, and examples include methods using filters, centrifuges, etc. The above drying process is also not particularly limited, but drying at a drying temperature of 120 to 270°C is preferred. The atmosphere for the drying process can be under reduced pressure, under an inert gas atmosphere such as nitrogen or an inert gas atmosphere, under an oxidizing atmosphere such as oxygen or air, or under a mixed gas atmosphere of air and nitrogen. The drying time is preferably 0.5 to 53 hours.

[0043] The PAS resin of this disclosure, manufactured by the method described above, can be processed into molded articles with excellent heat resistance, moldability, dimensional stability, etc., by various melting processes such as injection molding, extrusion molding, compression molding, and blow molding.

[0044] Furthermore, the PAS resin of the present invention can be used as a PAS resin composition in combination with various fillers in order to further improve performance such as strength, heat resistance, and dimensional stability. The fillers are not particularly limited, but examples include fibrous fillers and inorganic fillers. Examples of fibrous fillers include glass fibers, carbon fibers, silane glass fibers, ceramic fibers, aramid fibers, metal fibers, potassium titanate, silicon carbide, calcium sulfate, calcium silicate, and natural fibers such as wollastonite. Examples of inorganic fillers include barium sulfate, calcium sulfate, clay, pyroferrite, bentonite, sericite, zeolite, mica, talc, atalpulgite, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, and glass beads. Additionally, various additives such as mold release agents, colorants, heat stabilizers, UV stabilizers, foaming agents, rust inhibitors, flame retardants, lubricants, coupling agents, antibacterial agents, antiviral agents, and pigments can be included as additives during the molding process.

[0045] Furthermore, the PAS resin obtained by the present invention may be used as a PAS resin composition that appropriately incorporates synthetic resins such as polyester, polyamide, polyimide, polyetherimide, polycarbonate, polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, polyetherketone, polyarylate, polyethylene, polypropylene, polytetrafluoroethylene, polydifluoroethylene, polystyrene, ABS resin, epoxy resin, silicone resin, phenolic resin, urethane resin, liquid crystal polymer, or elastomers such as polyolefin rubber, fluororubber, or silicone rubber, depending on the application.

[0046] The PAS resin of the present invention possesses the inherent properties of PAS resin, such as heat resistance and dimensional stability, and is therefore widely useful as a material for various molding processes, such as injection molding or compression molding of electrical and electronic components such as connectors, printed circuit boards and encapsulated molded products, automotive parts such as lamp reflectors and various electrical components, plumbing components such as pipes and valves for transporting liquids, interior materials for various buildings, aircraft and automobiles, or precision parts such as OA equipment parts, camera parts and watch parts, or as a material for various molding processes such as extrusion molding or pultrusion of composites, sheets and pipes, or as a material for fibers or films. In particular, the cross-linked PAS resin of the present invention is useful when used as a material for injection molding because it has high toughness and excellent processability.

[0047] <Measurement method> The measurement method according to this embodiment is a method for measuring the concentration of a sulfur compound using spectroscopic analysis, wherein the sulfur compound contains an alkali metal sulfide or alkali metal hydrosulfide, and the spectroscopic analysis is near-infrared spectroscopy.

[0048] The measurement method disclosed herein can be used with virgin raw materials, as well as recycled and recovered raw materials. For example, the raw materials may be recycled or recovered from one or more selected from the group consisting of waste, waste liquid, exhaust gas, and vapor generated when manufacturing PAS resin. Examples of waste, waste liquid, exhaust gas, and vapor generated when polymerizing PAS resin include solid waste containing by-products and unreacted raw materials, organic polar solvents containing unreacted raw materials recovered after polymerization, washing solutions containing unreacted raw materials recovered after the washing process, exhaust gas and vapor generated during the polymerization reaction or dewatering of the polymer raw materials, and their condensates, etc. The recycling and recovery methods are not particularly limited. By being able to measure such sulfur compounds, recovered raw materials can be utilized efficiently. Furthermore, by using this method as a subsequent process following the purification or extraction of the recycled or recovered raw materials, the recovery efficiency and capture rate can be evaluated. In particular, by performing in-line analysis, the recovery efficiency and capture rate can be evaluated in real time. [Examples]

[0049] 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.

[0050] <Example 1> (Calibration curve creation between the concentration of sulfide agent raw materials and near-infrared spectra) Calibration curves were created for near-infrared spectra and NaSH and sodium sulfide (Na2S) concentrations using "Sodium Hydrosulfide (Liquid)" manufactured by Nagao Co., Ltd. (hereinafter referred to as "NaSH aqueous solution") and NaSH recovery solution (hereinafter referred to as "recovered NaSH aqueous solution"), which is a recycled raw material recovered by the method described below. The near-infrared spectrum was measured three times for each lot of aqueous solution, and the NaSH and Na2S concentrations were determined by performing neutralization titrations twice for each. Measurements were performed on 10 lots each of the NaSH aqueous solution and the recovered NaSH aqueous solution, and calibration curves were created by analyzing the near-infrared spectra and corresponding neutralization titration values ​​using PLS regression analysis. Depending on the range for which the calibration curve was to be created, some lots of the NaSH aqueous solution and recovered NaSH aqueous solution were used with the concentrations adjusted by adding acid or base. The correlation coefficient R of the calibration curve was calculated. 2 All values ​​were 0.99 or higher, showing a clear correlation between near-infrared radiation and neutralization titration. In near-infrared radiation measurements, the time required for sample preparation and measurement was 1 minute and 3 minutes, respectively. In neutralization titration, the time required for sample preparation and measurement was 15 minutes and 30 minutes, respectively.

[0051] <Example 2> A polymerization reaction of PPS was carried out using an aqueous NaSH solution manufactured by Nagao Corporation, with a target melt viscosity of 40 Pa·s and a target sodium content of 400 ppm by mass for the resulting PPS resin. Before the polymerization reaction, the concentration of the aqueous NaSH solution was measured, and the amount of sulfide-forming agent raw material to be added was determined based on the measurement results.

[0052] (Concentration measurement process for sulfide agent raw materials) Near-infrared radiation measurements were performed on an aqueous NaSH solution manufactured by Nagao Corporation, and the concentration of the aqueous NaSH solution was evaluated using the calibration curve created in Example 1. The NaSH concentration was 46.84% by mass, and the Na2S concentration was 0.54% by mass. The time required for sample preparation and measurement was 1 minute and 3 minutes, respectively, which was sufficiently rapid. Based on the measurement results, the amounts of aqueous NaSH solution and other polymerization raw materials, aqueous NaOH solution and p-dichlorobenzene (hereinafter abbreviated as p-DCB), were determined.

[0053] (Preparation process for sulfide agent raw materials) An autoclave equipped with stirring blades, connected to a condenser, pressure gauge, thermometer, decanter, and rectification column, and then connected to a gas absorption bottle pre-loaded with 2.00 kg of 20 wt% sodium hydroxide aqueous solution, was charged with 27.300 kg of NaSH aqueous solution (230 moles as NaSH), 18.533 kg of 49.21 mass% NaOH aqueous solution (228 moles), 33.472 kg of p-DCB (228 moles), and 4.560 kg of NMP (46 moles).

[0054] (Polymerization and purification process of PPS) The autoclave was heated to 173°C over 5 hours under a nitrogen atmosphere while stirring, and 26.794 kg of water was distilled off. The hydrogen sulfide scattered during dehydration was absorbed into an aqueous sodium hydroxide solution using a gas absorption bottle to obtain 2.00 kg of aqueous sodium hydroxide solution (A) that had absorbed the hydrogen sulfide. The amount of sulfur source in aqueous sodium hydroxide solution (A) in terms of NaSH was 6.45 g (0.12 mol). The vessel was then sealed. The DCB distilled off by azeotrope during dehydration was separated in a decanter and returned to the vessel as needed. After dehydration, the contents of the vessel were in a state where particulate anhydrous sodium sulfide composition was dispersed in p-DCB.

[0055] The internal temperature was cooled to 160°C, 45.212 kg (456 moles) of NMP was charged, and the temperature was raised to 185°C. When the pressure reached 0.00 MPa, the valve connected to the rectification column was opened, and the internal temperature was raised to 200°C over 1 hour. During this time, the temperature at the outlet of the rectification column was controlled by cooling and valve opening to keep it below 110°C. The distilled DCB and water mixture vapor was condensed in a condenser, separated in a decanter, and the DCB was returned to the boiler. The amount of water distilled was 273 g. The internal temperature was raised from 200°C to 230°C over 3 hours, stirred at 230°C for 1 hour, then raised to 250°C and stirred for 1 hour. The final pressure was 0.50 MPa.

[0056] After the reaction, the slurry obtained was cooled to room temperature, and then dried under reduced pressure at 150°C for 3 hours using a vacuum dryer to remove NMP. Next, 142 kg of 70°C hot water was added and stirred, then filtered, and another 81 kg of 70°C hot water was added and filtered to obtain 66 kg of hydrated cake and 209 kg of wastewater (B). The amount of sulfur source in wastewater (B) in NaSH equivalent was 644.69 g (11.5 mol). 170 g of the obtained hydrated cake and 180 g of deionized water were placed in a 0.5 liter autoclave and stirred at 220°C for 30 minutes. After cooling to room temperature, the mixture was filtered, and 480 g of 70°C deionized water was added to the filtered cake to wash it. Then, it was dried at 120°C for 4 hours to obtain PPS resin (1). The melt viscosity of the obtained PPS resin (1) was 38 Pa·s, and the sodium content was 410 ppm by mass. The errors between the measured value and the target value for melt viscosity and sodium content were 5% and 3%, respectively. The errors were calculated using the formula "|(measured value) - (target value)| ÷ (target value) × 100" (the same formula applies below).

[0057] <Example 3> The polymerization reaction of PPS was carried out using the same NaSH aqueous solution and recovered NaSH aqueous solution as in Example 2, with a target melt viscosity of 50 Pa·s and a target sodium content of 400 ppm by mass for the resulting PPS resin. Before the polymerization reaction, the concentration of the recovered NaSH solution was measured, and the amount of recovered NaSH solution to be charged was determined based on the measurement results.

[0058] (Recovery process for recovered NaSH aqueous solution) A gas absorption bottle containing the sodium hydroxide aqueous solution (A) obtained in Example 1 was connected to a sealed container equipped with a stirrer, pH meter, gas inlet tube, and dropping funnel. Wastewater (B) obtained in Example 1 was added to the sealed container, and while introducing N2 gas (50 ml / min), the mixture was stirred. Hydrochloric acid was added dropwise to the wastewater (B) to adjust the pH to 6.2, and the mixture was stirred for 60 minutes to generate hydrogen sulfide gas. The generated hydrogen sulfide gas was absorbed by the sodium hydroxide aqueous solution (A), and 2.30 kg of NaSH recovery solution was obtained. The amount of sulfur source contained in the NaSH recovery solution in NaSH equivalent terms was 489.96 g (8.74 mol).

[0059] (Concentration measurement process of recovered NaSH aqueous solution) Near-infrared radiation was used to measure the recovered NaSH aqueous solution, and its concentration was evaluated using the calibration curve created in Example 1. The NaSH concentration was 18.25% by mass, and the Na2S concentration was 4.28% by mass. The sample preparation and measurement took 1 minute and 3 minutes, respectively, which was sufficiently rapid.

[0060] (Preparation process for sulfidating agent raw materials or recovered sulfidating agent raw materials) The autoclave used in Example 1 was charged with 6.045 kg of the recovered NaSH aqueous solution (23 moles of NaSH, with a reuse rate of 10% of the total sulfur source), 24.570 kg of NaSH aqueous solution (207 moles of NaSH), 18.194 kg (224 moles) of 49.21% by mass NaOH aqueous solution, 33.302 kg (227 moles) of p-DCB, and 2.280 kg (23 moles) of NMP.

[0061] (Polymerization / purification process of PPS resin) 30.203 kg of water was distilled off in the same manner as in Example 1. Then, 47.492 kg (479 mol) of NMP was charged, and 273 g of water was distilled off in the same manner as in Example 1. From there, PPS resin (2) was obtained in the same manner as in Example 1. The melt viscosity of the obtained PPS resin (2) was 49 Pa·s, and the sodium content was 420 ppm by mass. The errors from the target values ​​for melt viscosity and sodium content were 2% and 5%, respectively.

[0062] <Reference example 1> Polymerization reactions of PPS were carried out using the NaSH aqueous solution from Example 2 and the recovered NaSH aqueous solution from Example 3, with the same target melt viscosity and target sodium content as in Example 3. The procedure was the same as in Example 3, except that the concentrations of the NaSH aqueous solution and the recovered NaSH aqueous solution were measured by neutralization titration instead of near-infrared measurement. The NaSH concentration in the NaSH aqueous solution was 46.81% by mass, and the Na2S concentration was 0.58% by mass. The NaSH concentration in the recovered NaSH solution was 18.15% by mass, and the Na2S concentration was 4.31% by mass. The time required for sample preparation and measurement was 15 minutes and 30 minutes, respectively. The melt viscosity of the obtained PPS resin (R1) was 49 Pa·s, and the sodium content was 430 ppm by mass. The errors from the target values ​​for melt viscosity and sodium content were 2.0% and 7.5%, respectively.

[0063] <Rating> (1) Determination of NaSH concentration and Na2S concentration (1-1) Near-infrared spectrum measurement A 5 mL sample was measured by transmission at room temperature (23°C) using a Bruker TANGO-T Fourier transform near-infrared spectrometer. The obtained spectrum was measured in the range of 5000–9000 cm⁻¹. -1 Peak intensities originating from NaSH or Na2S in two to five regions within the wavenumber range were extracted and used as a calibration curve. (1-2) Neutralization titration analysis 90 g of a 110-fold diluted aqueous solution of the sample was accurately weighed using decarbonated water. While stirring the solution, neutralization titration was performed with 0.01 mol / L hydrochloric acid using a potentiometric automatic titrator, and the Na2S concentration was calculated from the titration volume at the first equivalence point. Subsequently, while stirring the solution, neutralization titration was performed with 0.5 mol / L hydrochloric acid, and the neutralization titration was continued until the second equivalence point. The NaSH concentration was calculated from the difference between the titration volume from the first to the second equivalence point and the titration volume at the first equivalence point.

[0064] (2) Determination of sulfur sources contained in sodium hydroxide aqueous solution (A) and wastewater (B) 0.5 g of the sample solution was accurately weighed into a beaker, then diluted with 70 ml of pure water, 4 ml of 1% sodium hydroxide aqueous solution was added, and the sample was titrated with 0.02 mol / L silver nitrate using a potentiometric automatic titrator while stirring.

[0065] (3) Measurement of melt viscosity Using a Shimadzu Corporation flow tester "CFT-500D," PAS resin was tested at 300°C, L / D = 10 (mm) / 1 (mm), and load of 20 kgf / cm². 2 The melt viscosity (Pa·s) was measured after holding the material in the furnace for 6 minutes.

[0066] (4) Determination of sodium content PPS resin was weighed into a platinum crucible, and concentrated sulfuric acid was added to the crucible until it was submerged. The crucible was then heated in a muffle furnace at 700°C for 5 hours to completely ashify the resin. After cooling to room temperature, the resulting ash was dissolved in a 1% hydrochloric acid aqueous solution, and the amount of metal in the solution was measured using an atomic absorption spectrophotometer. The amount of metal in the PPS resin was calculated from the obtained values. The water used in this procedure had a conductivity of 18.2 MΩ·cm.

Claims

1. A method for producing polyarylene sulfide resin, comprising reacting a polyhalo-aromatic compound with (i) an alkali metal sulfide, or (ii) an alkali metal hydroxide and an alkali metal hydroxide, in an organic polar solvent, The concentration of the alkali metal sulfide or alkali metal hydrosulfide is measured by near-infrared spectroscopy, Adjusting the raw material ratio or polymerization reaction conditions based on the aforementioned concentration, A method for producing polyarylene sulfide resin, including [the specified element].

2. A method for producing a polyarylene sulfide resin according to claim 1, wherein the raw material ratio or reaction conditions include one or more selected from the group consisting of the molar ratio of the polyhalo-aromatic compound to the alkali metal sulfide, the molar ratio of the polyhalo-aromatic compound to the alkali metal hydroxide, the molar ratio of the alkali metal hydroxide to the alkali metal hydroxide, the amount of the organic polar solvent, the time of the polymerization reaction, the temperature of the liquid phase during the polymerization reaction, and the pressure of the gas phase during the polymerization reaction.

3. A method for producing a polyarylene sulfide resin according to claim 1, wherein at least one of the alkali metal sulfide or alkali metal hydrosulfide contains a recycled raw material.

4. This is a method for measuring the concentration of sulfur compounds using spectroscopic analysis. The sulfur compound comprises at least an alkali metal sulfide or alkali metal hydrosulfide, A measurement method in which the aforementioned spectroscopic analysis is near-infrared spectroscopy.

5. The measurement method according to claim 4, wherein the sulfur compound is recycled or recovered from one or more selected from the group consisting of waste, waste liquid, exhaust gas, and vapor generated when manufacturing polyarylene sulfide resin.