Method for modifying polyarylene sulfide resin, production method, and polyarylene sulfide resin composition

Abstract

To provide a modification method for easily improving the melt viscosity and molecular weight of a polyarylene sulfide (PAS) resin contained in a PAS resin composition, and to provide a PAS resin composition capable of providing a PAS resin molded article excellent in mechanical strength.SOLUTION: A method for modifying a PAS resin composition, comprising a step of blending a PAS resin and a cyclic oligoarylene sulfide as essential components and melt-kneading them at a temperature equal to or higher than the melting point of the PAS resin, and a step of heat-treating the resulting resin composition at an oxygen concentration of 21% or less and in a temperature range of 200 to 260 °C, wherein the blending amount of the cyclic oligoarylene sulfide is in the range of 0.1 to 30 parts by mass relative to 100 parts by mass of the PAS resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for modifying a polyarylene sulfide resin, a method for producing the same, and a polyarylene sulfide resin composition. [Background technology]

[0002] Polyarylene sulfide (PAS) resins, typified by polyphenylene sulfide (PPS) resin, have excellent heat resistance, chemical resistance, etc., and are widely used in electrical and electronic components, automotive parts, water heater parts, fibers, films, etc. Demand for high-molecular-weight PAS resins has been increasing in recent years due to their excellent mechanical properties, such as toughness.

[0003] Meanwhile, in order to realize a sustainable society, demand for the recycling of various materials is increasing. In particular, since a large amount of industrial waste collected from automobiles and home appliances is discharged, there is a demand for efficient reuse of the waste plastics contained therein. However, in general, the resins contained in plastic products that have been molded, processed, or used are deteriorated by physical and chemical damage, resulting in scission of molecular chains, and therefore, when reused as raw materials, it is not possible to obtain a resin composition with the same physical properties.

[0004] Therefore, for example, Patent Document 1 discloses a method for producing a glass fiber-reinforced recycled PPS resin composition, which comprises crushing a molded article containing polyphenylene sulfide resin and glass fiber to obtain (A) crushed molded article material, and mixing the crushed molded article material with (B) a PPS resin composition containing 40 to 90% by weight of a PPS resin having a weight-average molecular weight of 20,000 to 60,000 and 10 to 60% by weight of glass fiber. This method describes that by mixing a resin composition that has not been melt-molded (so-called virgin material) with the PPS resin derived from the molded article, it is possible to suppress deterioration of mechanical properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 002903 Brochure Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned method requires the use of virgin material to recycle waste PAS resin, which limits the amount of waste PAS resin that can be recycled.

[0007] Therefore, the problem that the present invention aims to solve is to provide a modification method that easily improves the melt viscosity and molecular weight of the PAS resin contained in a PAS resin composition, and to provide a PAS resin composition that can provide PAS resin molded products with excellent mechanical strength. [Means for solving the problem]

[0008] As a result of various investigations, the inventors discovered that a PAS resin composition can be easily modified by blending a certain amount of cyclic oligoarylene sulfide (hereinafter referred to as cyclic PAS oligomer) with PAS resin to produce a resin composition, and then heat-treating the resin composition under specific conditions, thereby completing the present invention.

[0009] That is, the present invention includes the following aspects. [1] A step (1) of blending a polyarylene sulfide resin and a cyclic oligoarylene sulfide as essential components and melt-kneading them at a temperature equal to or higher than the melting point of the polyarylene sulfide resin; (2) heat-treating the obtained resin composition at an oxygen concentration of 21% or less and at a temperature in the range of 200 to 260°C; A method for modifying a polyarylene sulfide resin composition, wherein the amount of the cyclic oligoarylene sulfide blended is in the range of 0.1 to 30 parts by mass per 100 parts by mass of the polyarylene sulfide resin. [2] The method for modifying a polyarylene sulfide resin composition according to [1] above, wherein the polyarylene sulfide resin contains recycled polyarylene sulfide resin. [3] The recycled polyarylene sulfide resin is a step (3) of heating a mixture (A) containing at least a resin composition or molded article containing a polyarylene sulfide resin and an organic polar solvent as essential components to 200°C or higher to dissolve the polyarylene sulfide resin in the organic polar solvent; a step (4) of removing a solid phase component from the mixture (A) by solid-liquid separation to obtain a liquid phase component containing at least a polyarylene sulfide resin and an organic polar solvent; Step (5) of cooling the liquid phase component to 200°C or less to obtain a mixture (B); A step (6) of subjecting the mixture (B) to solid-liquid separation to obtain a solid phase component containing at least a polyarylene sulfide resin; The method for modifying a polyarylene sulfide resin composition according to [2] above, wherein the polyarylene sulfide resin is a recycled polyarylene sulfide resin obtained by the step (7) of washing the solid phase component with water. [4] The method for modifying a polyarylene sulfide resin composition according to any one of [1] to [3] above, wherein the rate of change in peak molecular weight of the polyarylene sulfide resin before and after the treatment in step (2) is 150 to 300%. [5] The method for modifying a polyarylene sulfide resin composition according to any one of [1] to [4] above, wherein the rate of change in melt viscosity of the polyarylene sulfide resin before and after the treatment in the step (2) is 150 to 1,000%. (However, the melt viscosity was measured using a capillary rheometer at 315°C, L / D = 40 mm / 1 mm, and a shear rate of 1,216 sec -1 The values ​​were measured at [6] A method for producing a modified polyarylene sulfide resin composition, comprising a step of modifying the resin composition by heat treating it using the method according to any one of [1] to [5] above. [7] A polyarylene sulfide resin composition modified by the modification method according to any one of [1] to [6] above.

[0010] In the present disclosure, a polymer compound having repeating units of 2 to 50 (a mixture of dimers to 50-mers) may be referred to as an "oligomer".

[0011] In the present disclosure, the term "modification" refers to increasing the molecular weight of the PAS resin contained as a raw material component or increasing the viscosity of the PAS resin contained as a raw material component for the purpose of improving the properties of the PAS resin contained as a raw material component or eliminating the drawbacks of the PAS resin.

Effects of the Invention

[0012] According to the present invention, it is possible to provide a modification method for easily improving the melt viscosity and molecular weight of the PAS resin contained in the PAS resin composition, and to provide a PAS resin composition capable of providing a PAS resin molded product having excellent mechanical strength.

Embodiments for Carrying Out the Invention

[0013] 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.

[0014] <Method for Modifying PAS Resin Composition> The method for producing a PAS resin according to the present embodiment includes a step (1) of blending a PAS resin and a cyclic PAS oligomer as essential components and melt-kneading them at a temperature equal to or higher than the melting point of the PAS resin, and a step (2) of heat-treating the obtained resin composition in an oxygen concentration of 21% or less and in a temperature range of 200 to 260°C. This will be described in detail below.

[0015] Step (1) Step (1) is a step of blending a PAS resin and a cyclic PAS oligomer as essential components and melt-kneading them at a temperature equal to or higher than the melting point of the PAS resin.

[0016] The PAS resin applicable to this embodiment has a resin structure in which a structure in which an aromatic ring and a sulfur atom are bonded together is a repeating unit, and specifically, a PAS resin represented by the following general formula (1):

[0017] [ka] (In the formula, R 1 and R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a nitro group, an amino group, a phenyl group, a methoxy group, or an ethoxy group, and, if necessary, a structural portion represented by the following general formula (2):

[0018] [ka] The resin has a trifunctional structural moiety represented by formula (2) and a repeating unit represented by formula (3). The trifunctional structural moiety represented by formula (2) is preferably present in an amount of 0.001 to 3 mol %, and particularly preferably in an amount of 0.01 to 1 mol %, based on the total number of moles of the trifunctional structural moiety and other structural moieties.

[0019] Here, the structural moiety represented by the general formula (1) is particularly R 1 and R 2 is preferably a hydrogen atom from the viewpoint of the mechanical strength of the PAS resin, and in that case, examples include those bonded at the para position represented by the following formula (3) and those bonded at the meta position represented by the following formula (4).

[0020] [ka] Among these, a structure in which the sulfur atom is bonded to the aromatic ring in the repeating unit at the para position represented by the general formula (3) is particularly preferred in terms of heat resistance and crystallinity of the PAS resin.

[0021] The PAS resin may contain not only the structural moieties represented by the general formulas (1) and (2) but also the structural moieties represented by the following structural formulas (5) to (8):

[0022] [ka] The structural moieties represented by the general formulas (1) and (2) may account for 30 mol % or less of the total of the structural moieties represented by the general formulas (1) and (2). In particular, in the present invention, it is preferable that the structural moieties represented by the general formulas (5) to (8) account for 10 mol % or less from the viewpoint of the heat resistance and mechanical strength of the PAS resin. When the PAS resin contains the structural moieties represented by the general formulas (5) to (8), the bonding mode thereof may be either a random copolymer or a block copolymer.

[0023] The PAS resin may also have naphthyl sulfide bonds or the like in its molecular structure, but the amount is preferably 3 mol % or less, and particularly preferably 1 mol % or less, of the total number of moles including other structural moieties.

[0024] The physical properties of the PAS resin are not particularly limited as long as they do not impair the effects of the present invention, but are as follows.

[0025] (melt viscosity) The melt viscosity of the PAS resin used in this embodiment is not particularly limited, but in order to obtain a good balance between fluidity and mechanical strength, the melt viscosity (V6) measured at 300°C is preferably in the range of 1 Pa·s or more, and preferably in the range of 1000 Pa·s or less, more preferably in the range of 800 Pa·s or less, and even more preferably in the range of 500 Pa·s or less. The melt viscosity (V6) is measured using a Shimadzu flow tester, CFT-500D, at 300°C and a load of 1.96×10 6 The melt viscosity is measured after holding the sample at a pressure of 10 Pa and L / D=10 (mm) / 1 (mm) for 6 minutes.

[0026] (Non-Newtonian exponents) The non-Newtonian index of the PAS resin used in this embodiment is not particularly limited, but is preferably in the range of 0.90 to 2.00. However, in the present invention, the non-Newtonian index (N value) is a value calculated using the following formula after measuring the shear rate (SR) and shear stress (SS) using a capillograph under conditions of a melting point of +20°C and an orifice length (L) to orifice diameter (D) ratio of L / D = 40. The closer the non-Newtonian index (N value) is to 1, the more linear the structure is, and the higher the non-Newtonian index (N value), the more branched the structure is.

[0027]

number

[0028] (Manufacturing method) Methods for producing PAS resins are not particularly limited, but examples include (Production Method 1) a method in which a dihalogenoaromatic compound is polymerized in the presence of sulfur and sodium carbonate, optionally with a polyhalogenoaromatic compound or other copolymerization component; (Production Method 2) a method in which a dihalogenoaromatic compound is polymerized in a polar solvent in the presence of a sulfidizing agent or the like, optionally with a polyhalogenoaromatic compound or other copolymerization component; (Production Method 3) a method in which p-chlorothiophenol is added, optionally with other copolymerization components, and then self-condensed; and (Production Method 4) a method in which a diiodoaromatic compound and elemental sulfur are melt-polymerized under reduced pressure in the presence of a polymerization inhibitor that may have a functional group such as a carboxyl group or an amino group. Among these methods, (Production Method 2) is preferred because it is versatile. During the reaction, alkali metal salts of carboxylic acids or sulfonic acids or alkali hydroxides may be added to adjust the degree of polymerization. Among the above-mentioned (Production Method 2) methods, there is a method for producing a PAS resin by adding a water-containing sulfidizing agent to a mixture containing a heated organic polar solvent and a dihalogeno aromatic compound at a rate at which water can be removed from the reaction mixture, and then adding the dihalogeno aromatic compound and the sulfidizing agent, and optionally a polyhalogeno aromatic compound, in the organic polar solvent to react with each other, and controlling the amount of water in the reaction system to be in the range of 0.02 to 0.5 moles per mole of the organic polar solvent (see JP-A-07-228699). Particularly preferred is a compound obtained by a method in which a dihalogenoaromatic compound and, if necessary, a polyhalogenoaromatic compound or other copolymerization component are added in the presence of an alkali metal sulfide and an aprotic polar organic solvent, and an alkali metal hydrosulfide and an organic acid alkali metal salt are reacted while controlling the amount of organic acid alkali metal salt in the range of 0.01 to 0.9 mol per mol of the sulfur source and the amount of water in the reaction system to 0.02 mol or less per mol of the aprotic polar organic solvent (see WO2010 / 058713 pamphlet).Specific examples of dihalogenoaromatic compounds include p-dihalobenzene, m-dihalobenzene, o-dihalobenzene, 2,5-dihalotoluene, 1,4-dihalonaphthalene, 1-methoxy-2,5-dihalobenzene, 4,4'-dihalobiphenyl, 3,5-dihalobenzoic acid, 2,4-dihalobenzoic acid, 2,5-dihalonitrobenzene, 2,4-dihalonitrobenzene, 2,4-dihaloanisole, p,p'-dihalodiphenyl ether, 4,4'-dihalobenzophenone, 4,4'-di Examples of the polyhalogenoaromatic compounds include 1,2,3-trihalobenzene, 1,2,4-trihalobenzene, 1,3,5-trihalobenzene, 1,2,3,5-tetrahalobenzene, 1,2,4,5-tetrahalobenzene, 1,4,6-trihalonaphthalene, etc. The halogen atoms contained in the above compounds are preferably chlorine atoms or bromine atoms.

[0029] The method for post-treating the reaction mixture containing the PAS resin obtained by the polymerization step is not particularly limited, and examples thereof include: (post-treatment 1) after the completion of the polymerization reaction, first distilling off the solvent under reduced pressure or normal pressure, either as is or after adding an acid or base, and then washing the solid remaining after solvent distillation once or twice or more times with a solvent such as water, the reaction solvent (or an organic solvent having a similar solubility to the low-molecular-weight polymer), acetone, methyl ethyl ketone, or alcohols, followed by neutralization, washing with water, filtration, and drying; or (post-treatment 2) after the completion of the polymerization reaction, adding a solvent such as water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, or aliphatic hydrocarbons (which is soluble in the polymerization solvent used and is a poor solvent for at least the PAS resin) to the reaction mixture. or (post-treatment 3) after the polymerization reaction is complete, the reaction mixture is added with the reaction solvent (or an organic solvent having equivalent solubility to the low molecular weight polymer) and stirred, and the mixture is then filtered to remove the low molecular weight polymer. The mixture is then washed once or twice or more times with a solvent such as water, acetone, methyl ethyl ketone, or an alcohol, followed by neutralization, washing with water, filtration, and drying. (post-treatment 4) after the polymerization reaction is complete, the reaction mixture is added with water, washed with water, filtered, and if necessary, treated with an acid or base during the water washing, and then dried. (post-treatment 5) after the polymerization reaction is complete, the reaction mixture is filtered, and if necessary, washed once or twice or more times with the reaction solvent, followed by further washing with water, filtration, and drying.

[0030] In the post-treatment methods exemplified above as (Post-treatment 1) to (Post-treatment 5), the PAS resin may be dried in a vacuum, in air, or in an inert gas atmosphere such as nitrogen.

[0031] Examples of organic polar solvents that can be used in the method for producing PAS resins 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-imidazolidinoic acid; sulfolanes such as sulfolane and dimethylsulfolane; nitriles such as benzonitrile; ketones such as methyl phenyl 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-imidazolidinoic acid, are preferred, and N-methyl-2-pyrrolidone is more preferred.

[0032] The conditions for contacting the organic polar solvent with the PAS resin are not particularly limited, but from the viewpoint of promoting dissolution of the PAS resin, the temperature is preferably 100° C. or higher, more preferably 200° C. or higher, and preferably 300° C. or lower, more preferably 250° C. or lower. From the same viewpoint, the contact is preferably carried out at a pressure of 0.1 to 2 MPa (gauge pressure).

[0033] The PAS resin used in this embodiment may be virgin PAS resin, recycled PAS resin, or a mixture thereof. Processing (recycling) of PAS resin molded articles and PAS resin products into recycled materials can be carried out by known methods. Examples include a method in which the molded article or product is fragmented into chips or pellets by cutting or crushing, and reused as raw material; a method in which the fragmented molded article is dissolved in a solvent and then subjected to solid-liquid separation to remove fillers and recover only the PAS resin; and a method in which the fragmented molded article is brought into contact with a solvent to extract and remove components other than the PAS resin.

[0034] As a method for producing recycled PAS resin other than those described above, for example, a production method having the following steps can be mentioned. a step (3) of heating a mixture (A) containing at least a resin composition or molded article containing a PAS resin and an organic polar solvent as essential components to 200°C or higher to dissolve the PAS resin in the organic polar solvent; a step (4) of removing a solid phase component from the mixture (A) by solid-liquid separation to obtain a liquid phase component containing at least a PAS resin and an organic polar solvent; Step (5) of cooling the liquid phase component to 200°C or less to obtain a mixture (B); a step (6) of subjecting the mixture (B) to solid-liquid separation to obtain a solid phase component containing at least a PAS resin; Step (7) of washing the solid phase component with water.

[0035] In step (3), the resin composition or molded article containing PAS resin to be recycled may be a recovered PAS resin molded article provided by a consumer, an out-of-spec PAS resin molded article provided by a molded article manufacturer, or waste generated during molding (such as a runner in injection molding).

[0036] In step (3), the organic polar solvent for dissolving the PAS resin can be the same as the organic polar solvent applicable to the above-mentioned method for producing a PAS resin.

[0037] In step (4), the solid-liquid separation is not particularly limited as long as it does not impair the effects of the present invention. For example, it can be performed by filtration using a filtration device, or by using a water washing tank equipped with a stirrer and a centrifuge for solid-liquid separation. The solid-liquid separation can also be performed in a vessel with a mixing function, which has an internal stirring blade and a filtration filter at the bottom. Since the solid-liquid separation in step (4) proceeds while the PAS resin remains dissolved in the organic polar solvent, it is preferable that the device used for solid-liquid separation has a heating function or a heat-retaining function.

[0038] In step (5), the cooling rate for cooling the liquid phase component is not particularly limited, but a range of 0.1°C / min to 5°C / min is usually preferred. Furthermore, it is not necessary to cool at the same rate throughout the entire cooling step; a method in which the cooling rate is in the range of 0.1°C / min to 1°C / min until the PAS resin granules crystallize, and then cooling at a rate of 1°C / min or faster is also preferred. It is preferable to finally cool to 70°C or higher, preferably 100°C or higher and 200°C or lower, to obtain mixture (B). By cooling, the PAS resin precipitates, becoming a complex incorporating the dispersant, which is a component insoluble in the organic polar solvent.

[0039] This embodiment also includes a configuration in which step (5) involves flashing a liquid phase component containing at least the PAS resin and the organic polar solvent, thereby simultaneously carrying out step (6). The flashing method involves evaporating the solvent in the mixture to recover the solvent and simultaneously recovering the solid material. Typically, the mixture is flashed from a high-temperature, high-pressure state into an atmosphere under atmospheric or reduced pressure, distilling off and recovering the solvent, while simultaneously recovering the solid material containing the PAS resin in the form of powder or granules. A preferred embodiment of the flashing method involves ejecting a high-temperature, high-pressure (usually 240°C or higher, 0.3 MPa or higher) mixture of the organic polar solvent and the PAS resin from a nozzle into an atmosphere of nitrogen or water vapor under atmospheric pressure. The ambient temperature during flashing under reduced or normal pressure is 200°C or lower. If insufficient solvent is removed from the mixture, heating may be continued in an atmosphere of 150–200°C after flashing.

[0040] In step (7), the amount of water added to the solid-phase component for water washing is preferably in the range of 2 to 10 times the theoretical yield of the PAS resin finally obtained, which is preferable from the viewpoint of washing efficiency. It is preferable to divide the amount of water into 2 to 10, preferably 2 to 4, portions for water washing. The water washing is preferably carried out in a nitrogen or air atmosphere at a water temperature in the range of 20 to 300°C. From the viewpoint of good washing efficiency, it is more preferable to carry out the water washing in the range of 50 to 100°C, and most preferably in the range of 70 to 90°C. The water washing can be carried out once or repeatedly multiple times. When water washing is carried out multiple times, the atmospheric and temperature conditions may be the same or different.

[0041] The cyclic PAS oligomer blended as an essential component in this embodiment has a cyclic structure and the repeating unit of the PAS resin is 2 to 50 (dimer to pentamer). The cyclic PAS oligomer may be a mixture of oligomers with different repeating units (mixture of dimers to pentamers).

[0042] In this embodiment, the amount of cyclic PAS oligomer blended is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 25 parts by mass, per 100 parts by mass of PAS resin. Within this range, excellent processability during melt-kneading and excellent molecular chain elongation effect in the subsequent step (2) are achieved. Addition exceeding this range reduces the melt viscosity of the entire resin composition, resulting in poor mechanical properties and increased gas generation during melt molding of the resin composition. Furthermore, addition of an amount below this range results in poor molecular chain elongation effect.

[0043] In this embodiment, the incorporation of the cyclic PAS oligomer may be such that the effects of the present invention are not impaired. For example, the cyclic PAS oligomer may be used as an impurity in the PAS resin production process without being washed away, or may be prepared separately and incorporated into the resin. The method for producing the cyclic PAS oligomer is not particularly limited. For example, a polyhaloaromatic compound may be reacted with (i) an alkali metal sulfide or (ii) an alkali metal hydrosulfide and an alkali metal hydroxide in an organic polar solvent to obtain a crude reaction mixture containing at least the PAS resin, the cyclic PAS oligomer, the alkali metal halide, and the organic polar solvent. The solid component is then removed by solid-liquid separation to obtain a liquid component containing at least the cyclic PAS oligomer, and the organic polar solvent is then removed.

[0044] In the present embodiment, the method for melt-kneading the essential components is not particularly limited, but examples include a method in which the essential components and optional components, as needed, are blended and melt-kneaded; more specifically, a method in which the components are uniformly dry-mixed, as needed, using a tumbler, a Henschel mixer, or the like, and then the mixture is charged into a twin-screw extruder and melt-kneaded.

[0045] The melt-kneading can be carried out by heating the resin to a temperature range in which the resin temperature is equal to or higher than the melting point of the PAS resin, preferably equal to or higher than the melting point + 10°C, more preferably equal to or higher than the melting point + 10°C, even more preferably equal to or higher than the melting point + 20°C, to a temperature range in which the resin temperature is equal to or lower than the melting point + 100°C, more preferably equal to or lower than the melting point + 50°C.

[0046] The melt-kneading machine is preferably a twin-screw extruder from the viewpoint of dispersibility and productivity. For example, it is preferable to melt-knead while appropriately adjusting the resin component discharge rate in the range of 5 to 500 (kg / hr) and the screw rotation speed in the range of 50 to 500 (rpm), and more preferably melt-kneading under conditions where the ratio (discharge rate / screw rotation speed) is in the range of 0.02 to 5 (kg / hr / rpm). Furthermore, the components may be added and mixed to the melt-kneading machine simultaneously or in portions. The atmosphere in which melt-kneading is performed need not be particularly limited, but it is preferable to perform the melt-kneading in the air, specifically in an atmosphere with an oxygen concentration of more than 21%.

[0047] After the melt-kneading, the PAS resin composition according to this embodiment is preferably processed into pellets, chips, granules, powder, or other forms by a known method, for example, by extruding the molten resin composition into a strand shape.

[0048] Process (2) Step (2) is a step of heat treating the resin composition obtained in the above step at an oxygen concentration of 21% or less and at a temperature in the range of 200 to 260°C.

[0049] The heating means is not particularly limited, and known, commonly used devices and methods can be used. The heating time for the heat treatment is not particularly limited as long as it does not impair the effects of the present invention. However, it is preferable to adjust the heating time so that 20 parts by mass or more of the added cyclic PAS oligomer is consumed, from the viewpoints of sufficiently modifying the resin by extending the molecular weight and reducing the weight loss (amount of gas generated during heating) of the resulting resin, and it is more preferable to consume 40 parts by mass or more. The atmosphere during the heat treatment may have an oxygen concentration of 21% or less, and examples thereof include air, an inert gas (nitrogen gas, carbon dioxide gas, helium gas, etc.), and a mixed gas atmosphere of air and an inert gas.

[0050] In this process, heat treatment in an atmosphere with an oxygen concentration of 21% or less suppresses the formation of branched structures in the PAS resin during heat treatment, enabling the resin to be polymerized while maintaining its linear structure. While the reason for this effect is not entirely clear, it is presumed to be due to the following mechanism: In a high-temperature environment with an oxygen concentration of 21% or less, the cyclic PAS oligomers contained in the resin composition open their rings, resulting in molecular chain extension at the terminals of the PAS resin. Note that the above mechanism is merely speculative, and even if the effects of the present invention are achieved for other reasons, they are still within the scope of the present invention.

[0051] In step (2), the rate of change in peak molecular weight of the PAS resin before and after treatment is preferably 150 to 300%, more preferably 170 to 280%. Within this range, the resin composition achieves an excellent balance between improved mechanical properties and moldability. In this disclosure, the peak molecular weight refers to the average molecular weight at the point where the detection intensity of the chromatogram measured by gel permeation chromatography is maximum. In this disclosure, the molecular weight of the PAS resin is measured as follows. Calibration was performed using six types of monodisperse polystyrene. Equipment: Ultra-high temperature polymer molecular weight distribution measuring device (SSC-7000 manufactured by Senshu Scientific Co., Ltd.) Column: UT-805L (Showa Denko K.K.) Column temperature: 210℃ Solvent: 1-chloronaphthalene Measurement method: UV detector (360 nm)

[0052] In step (2), the rate of change in melt viscosity of the PAS resin before and after the treatment is preferably 150 to 1,000%, more preferably 200 to 500%. Within this range, the resin composition has an excellent balance between improved mechanical properties and moldability. The melt viscosity in this disclosure is measured using a Capilograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd. at 315°C, L / D = 40 mm / 1 mm, and a shear rate of 1,216 sec. -1 The values ​​were measured at .

[0053] The PAS resin composition of the present disclosure may contain optional additives such as release agents, colorants, heat stabilizers, UV stabilizers, foaming agents, rust inhibitors, flame retardants, lubricants, coupling agents, and fillers in step (1), provided that the effects of the present invention are not impaired. When a silane coupling agent is added in this embodiment, the amount of the silane coupling agent added is not particularly limited as long as the effects of the present invention are not impaired, but is preferably in the range of 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, to preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the PAS resin.

[0054] When a filler is blended in this embodiment, known and commonly used materials can be used as long as they do not impair the effects of the present invention. Examples include fillers of various shapes, such as fibrous fillers and non-fibrous fillers such as granular and plate-shaped fillers. Specifically, fibrous fillers such as glass fiber, carbon fiber, silane glass fiber, ceramic fiber, aramid fiber, metal fiber, potassium titanate, silicon carbide, calcium silicate, and wollastonite, as well as natural fibers, can be used, regardless of fiber length. Non-fibrous fillers such as glass beads, glass flakes, barium sulfate, clay, pyrophyllite, bentonite, sericite, mica, talc, attapulgite, ferrite, calcium silicate, calcium carbonate, glass beads, zeolite, milled fiber, and calcium sulfate can also be used. From the viewpoint of improving mechanical properties, it is preferable to blend a filler, and when blended, for example, the amount of the filler is preferably 5 to 600 parts by mass, more preferably 15 to 400 parts by mass, and even more preferably 30 to 300 parts by mass, per 100 parts by mass of the PAS resin. Fillers that have been treated with a surface treatment agent or a sizing agent can also be used.

[0055] The PAS resin composition of the present disclosure may further contain the following synthetic resins and elastomers as optional components in step (1), provided 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, polydifluoroethylene, polystyrene, ABS resin, epoxy resin, silicone resin, phenolic resin, urethane resin, and liquid crystal polymer. Examples of elastomers include polyolefin rubber, fluororubber, and silicone rubber. When a synthetic resin is added, from the viewpoints of processability and mechanical properties, it is preferably added in an amount of 1 to 50 parts by mass, and more preferably 5 to 25 parts by mass, per 100 parts by mass of the PAS resin.

[0056] The PAS resin composition obtained by the modification method or production method of the present disclosure can be melt-molded to form a molded article. Specifically, the present disclosure includes a molded article obtained by melt-molding the resin composition described above. The present disclosure also includes a method for producing a molded article, comprising the step of melt-molding the resin composition described above. Melt molding can be performed using various molding methods, such as injection molding, compression molding, extrusion molding of composites, sheets, and pipes, pultrusion molding, blow molding, and transfer molding, but is particularly suitable for injection molding. When molding by injection molding, the molding conditions are not particularly limited, and molding can be performed using conventional methods. For example, the PAS resin composition can be melted in an injection molding machine at a resin temperature above the melting point of the PAS resin, preferably at a temperature above the melting point +10°C, more preferably at a temperature between the melting point +10°C and the melting point +100°C, and even more preferably at a temperature between the melting point +20°C and the melting point +50°C, and then injected into a mold through a resin outlet. In this case, the mold temperature may be set within a known temperature range, for example, from room temperature (23°C) to 300°C, preferably from 130 to 190°C.

[0057] The method for producing a molded article of the present disclosure may further include a step of annealing the molded article. The optimal conditions for the annealing treatment are selected depending on the application or shape of the molded article. The annealing temperature is a temperature range equal to or higher than the glass transition temperature of the PAS resin, preferably a temperature range equal to or higher than the glass transition temperature +10°C, and more preferably a temperature range equal to or higher than the glass transition temperature +30°C. The annealing time is preferably 260°C or lower, and more preferably 240°C or lower. The annealing time is not particularly limited, but is preferably 0.5 hours or higher, more preferably 1 hour or higher. The annealing time is preferably 10 hours or lower, and more preferably 8 hours or lower. This range is preferred because it reduces distortion in the resulting molded article, improves the crystallinity of the resin, and further improves thermal conductivity, mechanical properties, and fuel barrier properties. The annealing treatment may be performed in air, but is preferably performed in an inert gas such as nitrogen gas.

[0058] The PAS resin composition obtained by the modification method according to this embodiment can be used in a wide range of known and commonly used applications, for example, as injection-molded or compression-molded products such as electrical and electronic components, including connectors, printed circuit boards, and encapsulated molded products; automobile components, including lamp reflectors and various electrical components; interior materials for various buildings, aircraft, and automobiles; precision components, including office equipment components, camera components, and watch components; and extrusion-molded or pultrusion-molded products, including fibers, films, sheets, and pipes. [Example]

[0059] The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting. Unless otherwise specified, "%" and "parts" are based on mass.

[0060] <Production Example 1: Production and Evaluation of Cyclic PAS Oligomer> A 100-L autoclave equipped with a stirring blade, connected to a pressure gauge, thermometer, and condenser, was charged with 12.942 kg of flaky sodium sulfide (60.3 wt % NaS) and 30,000 kg of N-methyl-2-pyrrolidone (NMP). The mixture was heated to 209°C with stirring under a nitrogen stream, and 3.096 kg of water was distilled off (the remaining water content was 1.13 moles per mole of sodium sulfide). The autoclave was then sealed and cooled to 180°C. 14.790 kg of p-dichlorobenzene (hereinafter referred to as DCB) and 12,000 kg of NMP were then charged. The liquid temperature was increased to 150°C, and the gauge pressure was increased to 0.1 MPa using nitrogen gas, and the temperature was raised. The reaction proceeded with stirring for 3 hours at a liquid temperature of 260°C. The maximum pressure during the reaction was 0.85 MPa. After the reaction, the reaction slurry was cooled and filtered at 120°C. 32,000 kg of NMP was added, and the cake was washed and filtered. The amount of NMP filtrate obtained was 53,600 kg. The entire NMP filtrate was placed in a 150 L vacuum agitator dryer, and the NMP was removed by distillation under reduced pressure at 150°C, yielding 1.835 kg of a composition containing a cyclic PPS oligomer. 3.0 kg of 70°C ion-exchanged water was added to and mixed with the resulting PPS oligomer-containing composition, followed by washing (stirring and filtration) three times and drying in a hot air dryer at 120°C for 4 hours, yielding 0.5 kg of a cyclic PPS oligomer.

[0061] <Examples 1 to 3, Reference Example 1, Comparative Example 1> ·Process (1) Using recycled PPS resin made by cutting and grinding PPS molded products (containing 40 parts by mass of glass fiber and 0.3 parts by mass of silane coupling agent) into chips, the various materials were compounded according to the composition and amounts listed in Table 1. These compounded materials were then fed into a vented twin-screw extruder "TEX-30α (product name)" manufactured by The Japan Steel Works, Ltd., and melt-kneaded at a resin component output rate of 30 kg / hr, a screw rotation speed of 200 rpm, and a set resin temperature of 310°C to obtain pellets of the resin composition. The materials were uniformly mixed in a tumbler beforehand and then fed into the top feeder.

[0062] The glass fiber blended into the PPS molded product was "T-717H" manufactured by Nippon Electric Glass Co., Ltd., with a fiber length of 3 mm and an average diameter of 10 μm, and the silane coupling agent used was epoxy silane 3-glycidoxypropyltrimethoxysilane "SH-6040" manufactured by Dow Corning Co., Ltd.

[0063] ·Process (2) All of the pellets prepared in step (1) were heat-treated for 35 hours in an inert gas oven at 240°C under an inert gas atmosphere. The obtained pellets were dried in a gear oven at 140°C for 2 hours, and then injection-molded to prepare various test pieces, which were then subjected to the following tests.

[0064] <Evaluation>

[0065] (1) Measurement of tensile elongation at break The pellets obtained in each example and comparative example were fed into a Sumitomo Heavy Industries injection molding machine (SE-75D-HP) with a cylinder temperature set to 310°C, and injection molding was performed using an ISO Type-A dumbbell specimen mold with a mold temperature controlled at 140°C to obtain ISO Type-A dumbbell specimens. The resin was injected from a single gate to produce test specimens that did not include welds. The tensile elongation at break of the obtained test specimens was measured using a measurement method based on ISO 527-1 and 2.

[0066] (2) Measurement of Charpy impact strength The pellets obtained in each example and comparative example were fed into a Sumitomo Heavy Industries injection molding machine (SE-75D-HP) set at a cylinder temperature of 310°C, and injection molding was carried out using a mold for molding ISO Type 1A dumbbell specimens, the mold temperature of which was controlled at 140°C, to obtain ISO Type-A dumbbell specimens. The resin was injected from a single gate so that the test specimens did not include welds. The central portion of the dumbbell-shaped test specimen was cut into a rod shape measuring 80 mm in length, 10 mm in width, and 4 mm in thickness, and notched to prepare an impact resistance test specimen. A Charpy impact test was carried out in accordance with ISO179-1 / 1eA to measure the impact strength (kJ / m 2 ) was measured.

[0067] [Table 1]

[0068] <Example 4, Reference Example 2>

[0069] ·Process (1) Using recycled PPS resin obtained through steps (3) to (7) below, each material was compounded according to the composition and amounts shown in Table 2. These compounded materials were then fed into a vented twin-screw extruder "TEX-30α (product name)" manufactured by The Japan Steel Works, Ltd., and melt-kneaded at a resin component output rate of 30 kg / hr, a screw rotation speed of 200 rpm, and a set resin temperature of 310°C to obtain pellets of the resin composition. The materials were uniformly mixed in advance in a tumbler and then fed into the top feeder.

[0070] ·Process (2) All of the pellets prepared in step (1) were heat-treated for 35 hours in an inert gas oven at 240°C under an inert gas atmosphere. The obtained pellets were dried for 2 hours in a gear oven at 140°C, and then injection-molded to prepare various test pieces, which were then tested for tensile strength and Charpy impact strength.

[0071] ·Process (3) A 100 L autoclave equipped with a stirring blade and connected to a pressure gauge, thermometer, and condenser was charged with 2 kg of a molded product made of a resin composition containing 60 parts by mass of PAS resin, 0.02 kg of the cyclic oligomer obtained in Production Example 1 so that the PPS oligomer contained in the composition was equivalent to 0.5 parts by mass relative to the PPS resin, and 60 kg of NMP. The temperature was raised from room temperature to 250°C under a nitrogen atmosphere with stirring, and the mixture was stirred for 12 hours.

[0072] ·Process (4) After the reaction was completed, the bottom valve of the autoclave was opened, and the mixture was passed through 50A diameter strainers heated to 250°C with openings of 100 μm, 50 μm, and 20 μm in that order to obtain a solution containing crude PPS resin.

[0073] ·Process (5) The entire solution containing the PPS resin was immediately flushed into a 150 L vacuum agitator dryer at 120°C and -90 kPaG to remove the NMP, and then cooled to room temperature, yielding a slurry containing 3.0% by mass of crude PPS resin.

[0074] ·Process(6) The resulting slurry containing the crude PPS resin was subjected to solid-liquid separation using a centrifugal filter to obtain a crude PPS mixture.

[0075] ·Process(7) 7.2 kg of 70°C ion-exchanged water was added to the obtained crude PPS mixture, mixed, washed three times (by stirring and filtering), and then dried in a hot air dryer at 120°C for 4 hours to obtain a PPS resin.

[0076] <Example 5, Reference Example 3> The same procedure as in Example 4 was carried out except that step (5) was carried out as follows. The entire solution containing the PPS resin was immediately cooled to 120° C. over 5 hours, yielding a slurry containing 3.0% by mass of crude PPS resin.

[0077] [Table 2]

[0078] Table 1 shows that Examples 1 to 3 had increased peak molecular weights and melt viscosities after step (2) and superior tensile strength and Charpy impact strength values ​​compared to Reference Example 1, which did not contain any oligomer. Comparative Example 2, which contained a large amount of oligomer, had poor physical properties for the pellets obtained through step (1), and the effect of improving mechanical strength after heat treatment was poor. Table 2 shows that, even when the PAS resin recycling method was different, the Examples exhibited superior mechanical strength to the Reference Example.

Claims

1. A step (1) of blending a polyarylene sulfide resin and a cyclic oligoarylene sulfide as essential components and melt-kneading the mixture at a temperature equal to or higher than the melting point of the polyarylene sulfide resin; The method includes a step (2) of heat-treating the obtained resin composition at an oxygen concentration of 21% or less and at a temperature in the range of 200 to 260°C, The method for modifying a polyarylene sulfide resin composition, wherein the amount of the cyclic oligoarylene sulfide blended is in the range of 0.1 to 30 parts by mass per 100 parts by mass of the polyarylene sulfide resin.

2. 2. The method for modifying a polyarylene sulfide resin composition according to claim 1, wherein the polyarylene sulfide resin comprises recycled polyarylene sulfide resin.

3. The recycled polyarylene sulfide resin is a step (3) of heating a mixture (A) containing, as essential components, a resin composition or a molded article containing at least a polyarylene sulfide resin and an organic polar solvent to 200°C or higher to dissolve the polyarylene sulfide resin in the organic polar solvent; a step (4) of removing a solid phase component from the mixture (A) by solid-liquid separation to obtain a liquid phase component containing at least a polyarylene sulfide resin and an organic polar solvent; Step (5) of cooling the liquid phase component to 200°C or less to obtain a mixture (B); A step (6) of subjecting the mixture (B) to solid-liquid separation to obtain a solid phase component containing at least a polyarylene sulfide resin; 3. The method for modifying a polyarylene sulfide resin composition according to claim 2, wherein the polyarylene sulfide resin is a recycled polyarylene sulfide resin obtained by the step (7) of washing the solid phase component with water.

4. 3. The method for modifying a polyarylene sulfide resin composition according to claim 1, wherein the rate of change in peak molecular weight of the polyarylene sulfide resin before and after the treatment in step (2) is 150 to 300%.

5. 3. The method for modifying a polyarylene sulfide resin composition according to claim 1, wherein the rate of change in melt viscosity of the polyarylene sulfide resin before and after the treatment in step (2) is 150 to 1,000%. (Melt viscosity was measured using a capillary rheometer at 315°C, L / D = 40 mm / 1 mm, and a shear rate of 1,216 sec.) －１ (The values ​​are measured at

6. A method for producing a modified polyarylene sulfide resin composition, comprising a step of modifying the resin composition by heat treating it using the method according to claim 1 or 2.

7. A polyarylene sulfide resin composition modified by the modification method according to claim 1 or 2.

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