JP7485254B1 - Polyarylene sulfide resin composition and method for producing molded article - Google Patents

Abstract

To provide a method for producing a polyarylene sulfide (PAS) resin composition having excellent electrical conductivity by highly dispersing carbon nanotubes (CNTs) in the PAS resin. More specifically, the method for producing a PAS resin composition having CNTs dispersed in the PAS resin includes the steps of contacting an organic polar solvent with the PAS resin to obtain a mixture (A) in which at least a portion of the PAS resin is dissolved in the organic polar solvent, adding a CNT dispersion to the mixture (A) to obtain a mixture (B), and subjecting the mixture (B) to solid-liquid separation to remove the liquid phase, wherein the CNT dispersion contains at least CNTs and the organic polar solvent.

Description

The present invention relates to a polyarylene sulfide resin composition and a method for producing a molded article.

Polyarylene sulfide resins (hereinafter abbreviated as PAS resins), typified by polyphenylene sulfide resins (hereinafter abbreviated as PPS resins), are excellent in heat resistance, mechanical strength, chemical resistance, moldability, and dimensional stability, and therefore are widely used in fields such as automobile parts and electrical and electronic products.

On the other hand, since PPS resin has a property of low electrical conductivity, resin compositions containing conductive fillers such as carbon black and carbon fiber have been developed to improve this property. However, as the range of applications of PPS resin expands, the required electrical conductivity performance increases year by year, and in order to impart sufficient electrical conductivity to the resin composition, it has been necessary to highly fill the conductive filler. This high filler filling has the problem of impairing the mechanical properties and molding processability inherent to the PPS resin.

As a method for solving this problem, the use of carbon nanotubes (hereinafter abbreviated as CNTs), which can impart high conductivity with a small amount of addition, has been considered. For example, a manufacturing method has been considered in which CNTs are highly dispersed in a PAS resin by polymerizing the PAS resin in the presence of CNTs (e.g., Patent Documents 1 and 2, etc.). However, the degree of polymerization of the PAS resin obtained by this manufacturing method is low, so there are limitations on processing conditions and applications.

For resins that are soluble in organic solvents in the presence of CNTs, a method has been proposed in which the resin is completely dissolved in an organic solvent before being mixed to highly disperse the CNTs in the resin (e.g., Patent Document 3, etc.). However, since dissolving PAS resin requires high temperatures of 200°C or higher, the associated high pressure and harsh environment, in order to highly disperse CNTs in PAS resin using this method, it is necessary to select a solvent and binder that can withstand the dissolving conditions of PAS resin. In addition, this method cannot be adopted because it imposes a very large environmental burden, and therefore a method under milder conditions has been sought.

JP 2005-232247 A JP 2007-507562 A JP 2010-242091 A

Therefore, an object of the present invention is to provide a method for producing a PAS resin composition having excellent electrical conductivity by dispersing CNTs to a high degree in the PAS resin under relatively mild conditions.

As a result of various investigations, the inventors of the present application discovered that a PAS resin composition in which CNTs are highly dispersed in the PAS resin can be obtained by adding a CNT dispersion liquid to a mixture in which at least a portion of the PAS resin is dissolved in an organic polar solvent, and then performing solid-liquid separation, and thus completed the present invention.

That is, the present disclosure provides a method for producing a PAS resin composition in which CNTs are dispersed in a PAS resin, comprising:
A step (1) of contacting an organic polar solvent with a PAS resin to obtain a mixture (A) in which at least a portion of the PAS resin is dissolved in the organic polar solvent;
A step (2) of adding a CNT dispersion to the mixture (A) to obtain a mixture (B); and
and (3) subjecting the mixture (B) to solid-liquid separation to remove the liquid phase, wherein the CNT dispersion contains at least CNTs and an organic polar solvent and/or water.

The present disclosure also provides a method for producing a PAS resin composition, comprising a step of melt-kneading the PAS resin composition obtained by the above-described production method with a PAS resin,
The present invention relates to a method for producing a PAS resin composition, in which the CNT content per 100 parts by mass of the obtained PAS resin composition is 1.0 part by mass or less, and the volume resistivity is 1.0×10 ¹⁰ Ω·cm or less.

According to the present invention, it is possible to provide a method for producing a PAS resin composition having excellent electrical conductivity by dispersing CNTs to a high degree in the PAS resin.

Hereinafter, an embodiment of the present invention will be described in detail, but 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. In addition, when multiple upper and lower limit values are described for a specific parameter, any upper and lower limit values can be combined to form a suitable numerical range.

First Embodiment
The method for producing a PAS resin composition according to the first embodiment of the present disclosure includes a step (1) of contacting an organic polar solvent with a PAS resin to obtain a mixture (A) in which at least a part of the PAS resin is dissolved in the organic polar solvent, a step (2) of adding a CNT dispersion to the mixture (A) to obtain a mixture (B), and a step (3) of subjecting the mixture (B) to solid-liquid separation to remove the liquid phase. The steps are described in detail below.

<Step (1)>
Step (1) is a step of contacting an organic polar solvent with a PAS resin to obtain a mixture (A) in which at least a portion of the PAS resin is dissolved in the organic polar solvent. The obtained mixture (A) contains at least the PAS resin and the organic polar solvent, and at least a portion of the PAS resin is dissolved in the organic polar solvent.

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

（式中、Ｒ^１及びＲ^２は、それぞれ独立して水素原子、炭素原子数１～４の範囲のアルキル基、ニトロ基、アミノ基、フェニル基、メトキシ基、エトキシ基を表す。）で表される構造部位と、必要に応じてさらに下記一般式（２）

(wherein R ¹ and R ² each independently represent 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):

で表される３官能性の構造部位と、を繰り返し単位とする樹脂である。式（２）で表される３官能性の構造部位は、他の構造部位との合計モル数に対して０．００１～３モル％の範囲が好ましく、特に０．０１～１モル％の範囲であることが好ましい。

The trifunctional structural unit represented by formula (2) is preferably in the range of 0.001 to 3 mol %, particularly preferably 0.01 to 1 mol %, based on the total number of moles of the trifunctional structural unit and other structural units.

Here, the structural portion represented by the general formula (1), particularly ^R1 and ^R2 in the formula, are preferably hydrogen atoms from the viewpoint of the mechanical strength of the PAS resin. In this case, examples of the structural portion 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).

これらの中でも、特に繰り返し単位中の芳香族環に対する硫黄原子の結合は前記一般式（３）で表されるパラ位で結合した構造であることが前記ＰＡＳ樹脂の耐熱性や結晶性の面で好ましい。

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

The PAS resin may include 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).

で表される構造部位を、前記一般式（１）と一般式（２）で表される構造部位との合計の３０モル％以下で含んでいてもよい。特に本発明では上記一般式（５）～（８）で表される構造部位は１０モル％以下であることが、ＰＡＳ樹脂の耐熱性、機械的強度の点から好ましい。前記ＰＡＳ樹脂中に、上記一般式（５）～（８）で表される構造部位を含む場合、それらの結合様式としては、ランダム共重合体、ブロック共重合体の何れであってもよい。

The structural moiety represented by the general formula (1) and the structural moiety represented by the general formula (2) may be contained in an amount of 30 mol % or less of the total of the structural moieties represented by the general formula (1) and the general formula (2). In particular, in the present invention, it is preferable that the structural moieties represented by the general formulas (5) to (8) are 10 mol % or less in terms of the heat resistance and mechanical strength of the PAS resin. When the structural moieties represented by the general formulas (5) to (8) are contained in the PAS resin, the bonding mode thereof may be either a random copolymer or a block copolymer.

The PAS resin may have naphthyl sulfide bonds or the like in its molecular structure, but the amount of such bonds is preferably 3 mol % or less, and particularly preferably 1 mol % or less, based on the total molar amount including other structural portions.

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.

(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 500 Pa·s or less, and even more preferably in the range of 200 Pa·s or less. However, the melt viscosity (V6) is measured by using a Shimadzu flow tester, CFT-500D, and is the measured value of the melt viscosity after holding the PAS resin at 300°C, load: 1.96×10 ⁶ Pa, L/D=10 (mm)/1 (mm) for 6 minutes.

(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 by measuring the shear rate (SR) and shear stress (SS) using a capillograph under the conditions of melting point +20°C and the ratio of the orifice length (L) to the orifice diameter (D) L/D=40. The closer the non-Newtonian index (N value) is to 1, the closer the structure is to a linear structure, and the higher the non-Newtonian index (N value), the more branched the structure is.

［ただし、ＳＲは剪断速度（秒^－１）、ＳＳは剪断応力（ダイン／ｃｍ^２）、そしてＫは定数を示す。］

[where SR is the shear rate (sec ^-1 ), SS is the shear stress (dynes/ ^cm2 ), and K is a constant.]

(Production method)
The method for producing the PAS resin is not particularly limited, but examples thereof include (production method 1) a method in which a dihalogeno aromatic compound is polymerized in the presence of sulfur and sodium carbonate, and if necessary, a polyhalogeno aromatic compound or other copolymerization component is added, (production method 2) a method in which a dihalogeno aromatic compound is polymerized in the presence of a sulfidizing agent or the like in a polar solvent, and if necessary, a polyhalogeno aromatic compound or other copolymerization component is added, (production method 3) a method in which p-chlorothiophenol is added, and if necessary, other copolymerization components are added, and self-condensed, and (production method 4) a method in which a diiodo aromatic 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 carboxy group or an amino group. Among these methods, (production method 2) is preferred because it is versatile. During the reaction, an alkali metal salt of a carboxylic acid or sulfonic acid or an alkali hydroxide 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 introducing a water-containing sulfidizing agent into 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 reacting the dihalogeno aromatic compound and the sulfidizing agent in the organic polar solvent, and optionally adding a polyhalogeno aromatic compound, and controlling the amount of water in the reaction system to within a range of 0.02 to 0.5 mol per mol of the organic polar solvent (see JP-A-07-228699). Particularly preferred is a method in which a dihalogeno-aromatic compound and, if necessary, a polyhalogeno-aromatic 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 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 be 0.02 mol or less per mol of the aprotic polar organic solvent (see WO2010/058713 pamphlet). Specific examples of the dihalogeno aromatic compound 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 polyhalogeno aromatic 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.

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-treating 1) a method in which, after the completion of the polymerization reaction, the reaction mixture is first distilled off under reduced pressure or normal pressure, either as is or after the addition of an acid or a base, and then the solid matter remaining after the solvent distillation is washed 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, and then neutralized, washed with water, filtered, and dried; or (post-treating 2) a method in which, after the completion of the polymerization reaction, the reaction mixture is dissolved in a solvent such as water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, or aliphatic hydrocarbons (soluble in the polymerization solvent used and a poor solvent for at least the PAS resin). or (a certain solvent) is added as a precipitant to precipitate solid products such as PAS resin and inorganic salts, which are then filtered off, washed with water, and dried; or (post-treatment 3) after the polymerization reaction is completed, a reaction solvent (or an organic solvent having a solubility equivalent to that of the low molecular weight polymer) is added to the reaction mixture, the mixture is stirred, and the mixture is filtered to remove the low molecular weight polymer, followed by washing once or twice or more times with a solvent such as water, acetone, methyl ethyl ketone, or alcohols, followed by neutralization, washing with water, filtration, and drying; (post-treatment 4) after the polymerization reaction is completed, water is added to the reaction mixture, the mixture is washed with water, filtered, and if necessary, an acid or a base is added during the water washing, followed by drying; or (post-treatment 5) after the polymerization reaction is completed, the reaction mixture is filtered, and if necessary, the mixture is washed once or twice or more times with the reaction solvent, followed by further washing with water, filtration, and drying.

In the post-treatment methods exemplified above in (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.

The PAS resin used in this embodiment may be a recycled PAS resin. When the PAS resin used in this embodiment contains the recycled material, the proportion of the recycled material in the resin is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The processing (recycling process) of the PAS resin molded product into a recycled material can be carried out by a known method. For example, a method of dividing the molded product into chips or pellets by cutting or crushing, a method of dissolving the divided molded product in a solvent and then performing solid-liquid separation to remove the filler, and a method of contacting the divided molded product with a solvent to extract and remove components other than the PAS resin. The recycling process is often carried out based on collected PAS resin molded products provided by consumers, out-of-spec PAS resin molded products provided by molded product manufacturers, and losses generated during molding (such as runners in injection molding). By using recycled PAS resin, the amount of waste resin and molded products can be reduced, thereby reducing the environmental load.

Examples of organic polar solvents that can be used in the present embodiment include amides, ureas, and lactams such as formamide, acetamide, N-methylformamide, N,N-dimethylacetamide, tetramethylurea, N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methyl-ε-caprolactam, ε-caprolactam, hexamethylphosphoramide, N-dimethylpropyleneurea, and 1,3-dimethyl-2-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.

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 performed at 0.1 to 2 MPa (gauge pressure).

In addition, the state in which at least a portion of the PAS resin is dissolved in the organic polar solvent in the mixture (A) obtained in this process includes not only a state in which the PAS resin is solvated in the organic polar solvent, but also, for example, a state in which the organic polar solvent penetrates and is retained (swelled) in the amorphous portion of the PAS resin.

<Step (2)>
Step (2) is a step of adding a CNT dispersion to the mixture (A) to obtain a mixture (B). The obtained mixture (B) contains at least a PAS resin, an organic polar solvent, and a CNT dispersion, with at least a portion of the PAS resin dissolved in the organic polar solvent.

The amount of CNT dispersion added is not particularly limited, but from the viewpoint of highly dispersing CNT in the PAS resin while suppressing aggregation, it is preferable to adjust the amount of CNT to 20 parts by mass or less, and more preferably to adjust it to 5 parts by mass or less, relative to 100 parts by mass of the PAS resin contained in the mixture (A). It is also preferable that it is 0.05 parts by mass or more. If the content of CNT is too small, a conductive path is not formed in the resin composition, and it is difficult to exhibit excellent conductive properties. On the other hand, if the content of CNT is too high, material costs will increase, and there may be cases where the viscosity increases or physical properties decrease due to an increase in the interface between the CNT and the resin in the resin composition.

The conditions for adding the CNT dispersion to the mixture (A) are not particularly limited, but from the viewpoint of the heat resistance of the dispersion and the binder, the temperature is preferably 200° C. or less, and more preferably 100° C. or less.

CNT Dispersion Next, a CNT dispersion applicable to this embodiment will be described. A CNT dispersion applicable to this embodiment contains at least CNT and an organic polar solvent and/or water. In this disclosure, the dispersion refers to a dispersion in which CNT is dispersed in an organic polar solvent and/or water, and further, in this disclosure, it is preferable that the CNT is dispersed without forming aggregates.

CNT has a shape of a cylinder formed by rolling one surface of graphite, and includes single-walled nanotubes (SWNT) with a structure of one layer rolled up, and multi-walled nanotubes (MWNT) with two or more layers rolled up, and any of these can be used in the present invention. Among these, from the viewpoint of exhibiting electrical conductivity with a smaller amount of addition, SWNT with a diameter of 20 nm or less is preferable, and those that form bundles with a bundle diameter of 1 μm or less are preferable, and those that form bundles of 100 nm or less are more preferable. In addition, from the viewpoint of facilitating the formation of a conductive path in the PAS resin, those with a length of 100 nm or more are preferable. In addition, CNT can generally be produced by a laser ablation method, an arc thermal CVD method, a plasma CVD method, a gas phase method, a combustion method, or the like, but CNT produced by any method can be used.

The surface and ends of the CNT used in this embodiment may be modified with functional groups to increase the affinity with the resin, for example, functionalized with hydroxyl groups, carboxyl groups, or amino groups using an acid or alkali, as long as the effect of the present invention is not impaired. Furthermore, the CNT may be pretreated with a coupling agent, such as an isocyanate compound, an organic silane compound, an organic titanate compound, or an epoxy compound.

The organic polar solvent contained in the CNT dispersion liquid used in this embodiment is not particularly limited, but it is preferable to use the same organic polar solvent as that contacted with the PAS resin in step (1) from the viewpoint of affinity. The content of the organic polar solvent and/or water in the CNT dispersion liquid is preferably 10 parts by mass or more and preferably 500 parts by mass or less with respect to 100 parts by mass of the CNT dispersion liquid. Within this range, the CNTs can maintain an optimal bundle diameter for imparting electrical conductivity.

The CNT dispersion may also contain a dispersion aid. The dispersion aid that can be applied to this embodiment is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include water-soluble resins such as polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), and polythiophene (PT). In particular, when a water-soluble resin having a hydrogen bond term (dH) in the Hansen solubility parameter of 1 to 10 [MPa ^0.5 ] is used as a dispersion aid, the affinity between the CNT and the resin can be improved, and therefore the CNT added to the resin can exhibit its function (electrical conductivity and thermal conductivity) in a smaller amount, which is preferable. The hydrogen bond term (dH) in the Hansen solubility parameter is a value calculated by the atomic group contribution method based on the chemical structure using the Hansen Solubility Parameter Software (HSPiP).

The content of the dispersion aid in the CNT dispersion liquid is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 100 parts by mass or more, and is preferably 500 parts by mass or less, and more preferably 400 parts by mass or less, relative to 100 parts by mass of CNT. Within such a range, the affinity between CNT and resin can be efficiently improved.

<Step (3)>
The step (3) is a step of subjecting the mixture (B) to solid-liquid separation to remove the liquid phase.

The method for solid-liquid separation in this step is not particularly limited, and known devices and methods can be used. For example, a suitable method such as vacuum distillation, centrifugation, screw decanter, vacuum filtration, pressure filtration, etc. can be selected. These methods can also be combined or repeated.

The mixture (B) from which the liquid phase has been removed is recovered, and may then be dried as is and used as a PAS resin composition powder, or may be further washed with warm water, hot water, or the like, followed by solid-liquid separation and drying to prepare a powdered or granular PAS resin composition.

The PAS resin composition obtained by the method for producing a PAS resin composition according to the present embodiment has a structure in which CNTs are highly dispersed in the PAS resin, and therefore exhibits excellent electrical conductivity. The electrical conductivity of the PAS resin composition in the present disclosure is not particularly limited, but for example, the volume resistivity is 1.0×10 ¹⁰ [Ω·cm] or less. The volume resistivity is a value measured by the method in the examples.

Second Embodiment
The method for producing a PAS resin composition according to the second embodiment of the present disclosure is a method for producing a PAS resin composition comprising a step of melt-kneading the PAS resin composition obtained by the above-described method with a PAS resin. In other words, the method for producing a PAS resin composition is a method for producing a PAS resin composition in which the PAS resin composition obtained by the above-described method is used as a master batch and further diluted with a PAS resin.

The PAS resin for dilution (hereinafter sometimes abbreviated as diluted PAS resin) applicable to this embodiment can be the same as the PAS resin used in step (1) in the first embodiment. The physical properties of the diluted PAS resin are not particularly limited as long as they do not impair the effects of the present invention, and can be selected in accordance with the processing conditions and applications of the PAS resin composition obtained after melt-kneading.

The method for producing the PAS resin composition of the present embodiment includes a step of blending the above essential components and melt-kneading them at a temperature range equal to or higher than the melting point of the PAS resin. More specifically, the PAS resin composition of the present embodiment is composed of each essential component and, if necessary, optional components described below. The method for producing the resin composition used in the present invention is not particularly limited, but includes a method of blending the essential components and, if necessary, optional components, and melt-kneading them, more specifically, a method of uniformly dry-mixing them using a tumbler or Henschel mixer, if necessary, and then feeding them into a twin-screw extruder to melt-knead them.

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, preferably equal to or lower than the melting point + 100°C, more preferably equal to or lower than the melting point + 50°C.

The melt kneader is preferably a twin-screw kneading extruder from the viewpoint of dispersibility and productivity. For example, it is preferable to melt knead while appropriately adjusting the range of the discharge amount of the resin component to 5 to 500 (kg/hr) and the range of the screw rotation speed to 50 to 500 (rpm), and it is more preferable to melt knead under the condition that the ratio (discharge amount/screw rotation speed) is in the range of 0.02 to 5 (kg/hr/rpm). In addition, the addition and mixing of each component to the melt kneader may be performed simultaneously or in portions. For example, when a fibrous filler or the like is added as an optional component, it is preferable to feed the extruder from the side feeder of the twin-screw kneading extruder from the viewpoint of dispersibility. The position of the side feeder is preferably such that the ratio of the distance from the extruder resin input part (top feeder) to the side feeder to the total screw length of the twin-screw kneading extruder is 0.1 or more, more preferably 0.3 or more. In addition, such a ratio is preferably 0.9 or less, more preferably 0.7 or less.

In the present embodiment, the blending ratio of the diluted PAS resin to the PAS resin composition is preferably adjusted so that the CNT content of the PAS resin composition obtained after melt kneading is 0.05 to 1.0 parts by mass per 100 parts by mass of the PAS resin. Within this range, the resulting PAS resin composition exhibits excellent electrical conductivity and mechanical strength.

In the method for producing the PAS resin composition according to the present embodiment, a filler can be blended as an optional component as necessary. As these fillers, known and commonly used materials can be used as long as they do not impair the effects of the present invention, and fillers of various shapes such as granular, plate-like, and fibrous ones can be used. For example, fillers such as glass fiber, carbon fiber, aramid fiber, glass beads, glass flakes, barium sulfate, clay, pyrophyllite, bentonite, sericite, mica, talc, attapulgite, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, zeolite, milled fiber, and calcium sulfate can also be used.

In the method for producing the PAS resin composition according to the present embodiment, a silane coupling agent can be blended as an optional component as necessary. The silane coupling agent is not particularly limited as long as it does not impair the effects of the present invention, but a silane coupling agent having a functional group that reacts with a carboxy group, such as an epoxy group, an isocyanato group, an amino group, or a hydroxyl group, is preferably mentioned. Examples of such silane coupling agents include epoxy group-containing alkoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, and γ-isocyanatopropyltrichlorosilane; amino group-containing alkoxysilane compounds such as γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane; and hydroxyl group-containing alkoxysilane compounds such as γ-hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane.

In the method for producing the PAS resin composition according to the present embodiment, in addition to the above components, synthetic resins such as polyester resin, polyamide resin, polyimide resin, polyetherimide resin, polycarbonate resin, polyphenylene ether resin, polysulfone resin, polyphenylene sulfide sulfone resin, polyether sulfone resin, polyether ether ketone resin, polyether ketone resin, polyarylene resin, polyethylene resin, polypropylene resin, polytetrafluoroethylene resin, polyethylene difluoroethylene resin, polystyrene resin, ABS resin, phenol resin, urethane resin, liquid crystal polymer, and thermoplastic elastomer (hereinafter simply referred to as synthetic resin) can be blended as an optional component depending on the application.

In the method for producing the PAS resin composition according to the present embodiment, other known and commonly used additives such as colorants, antistatic agents, antioxidants, heat stabilizers, UV stabilizers, UV absorbers, foaming agents, flame retardants, flame retardant assistants, rust inhibitors, and release agents (metal salts or esters of fatty acids having 18 to 30 carbon atoms, including stearic acid or montanic acid, polyolefin waxes such as polyethylene, etc.) can be blended as optional components as necessary. These additives are not essential components, and may be used in an amount of, for example, preferably 0.01 parts by mass or more relative to 100 parts by mass of the PAS resin, and preferably 1000 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 10 parts by mass or less, depending on the purpose and application so as not to impair the effects of the present invention.

In addition, the method for producing a PAS resin composition according to the present embodiment provides the resulting PAS resin composition with excellent electrical conductivity. The electrical conductivity is not particularly limited, but for example, the volume resistivity is 1.0×10 ¹⁰ Ω·cm or less. The volume resistivity is a value measured by the method in the examples.

The PAS resin composition of the present disclosure can be subjected to various molding processes such as injection molding, compression molding, extrusion molding of composites, sheets, pipes, etc., pultrusion molding, blow molding, and transfer molding, but is particularly suitable for injection molding applications. When molding by injection molding, various molding conditions are not particularly limited, and molding can be performed by a normal general method. For example, in an injection molding machine, the PAS resin composition is melted at a resin temperature in a temperature range of the melting point of the PAS resin or higher, preferably in a temperature range of the melting point + 10°C or higher, more preferably in a temperature range of the melting point + 10°C to the melting point + 100°C, and even more preferably in a temperature range of the melting point + 20°C to the melting point + 50°C, and then the resin is injected into a mold from a resin discharge port and molded. At that time, the mold temperature may also be set to a known temperature range, for example, room temperature (23°C) to 300°C, preferably 130 to 190°C.

The method for producing a molded article of the present disclosure may 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, and the annealing temperature is in a temperature range equal to or higher than the glass transition temperature of the PAS resin, preferably in a temperature range of the glass transition temperature + 10 ° C. or higher, and more preferably in a temperature range of the glass transition temperature + 30 ° C. or higher. On the other hand, it is preferably in a range of 260 ° C. or lower, and more preferably in a range of 240 ° C. or lower. The annealing time is not particularly limited, but is preferably in a range of 0.5 hours or higher, and more preferably in a range of 1 hour or higher. On the other hand, it is preferably in a range of 10 hours or lower, and more preferably in a range of 8 hours or lower. In such a range, the distortion of the molded article obtained is reduced and the crystallinity of the resin is improved, which is preferable. The annealing treatment may be performed in air, but is preferably performed in an inert gas such as nitrogen gas.

The applications of the PAS resin molded products of the present disclosure are not particularly limited and can be used as various products. However, since the PAS resin molded products are characterized by excellent electrical conductivity in addition to the inherent chemical resistance of the PAS resin, they are particularly suitable for use in parts that require chemical resistance and antistatic properties, such as fuels (the term fuel includes fossil fuels such as crude oil, shale oil, shale gas, LNG, gasoline, kerosene, diesel, heavy oil, etc., saturated hydrocarbons such as n-hexane, isohexane, n-nonane, isononane, dodecane, isododecane, etc., 1-hexene, 1-heptane, etc., and the like). The hydrocarbons may be one or more of unsaturated hydrocarbons such as cyclohexane, cycloheptane, cyclooctane, cyclodecane, decalin, etc., cyclic saturated hydrocarbons such as cyclohexene, cycloheptene, cyclooctene, 1,1,3,5,7-cyclooctatetraene, cyclododecene, etc., and aromatic hydrocarbons such as benzene, toluene, xylene, etc. The hydrocarbons may be one or more of unsaturated hydrocarbons such as cyclohexane ... In addition, the PAS resin molded article of the present disclosure can also be suitably used for containers that come into contact with or are immersed in inks or paints containing the above-mentioned hydrocarbons, for example, printing parts and painting parts used in printing equipment such as nozzles, brushes, cartridges, pumps, transfer bodies, and transfer belts, sliding parts exemplified by gears that come into contact with lubricating oil, and parts of cleaning equipment such as brushes, hoses, and nozzles used in cleaning using hydrocarbons as a solvent. Furthermore, in addition to the above, the PAS resin molded article can also be made into the following ordinary resin molded articles. For example, electrical and electronic components such as protective and supporting members for box-shaped integrated modules of electrical and electronic components, multiple individual semiconductors or modules, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, terminal blocks, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, motor brush holders, parabolic antennas, computer-related components, etc.; VTR components, television components, irons, hair dryers, rice cooker components, microwave oven components, Home and office electrical appliance parts such as audio parts, audio/visual equipment parts such as audio/laser discs, compact discs, DVD discs, and Blu-ray discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, and water-related equipment parts such as water heaters, bath water volume and temperature sensors; office computer related parts, telephone related parts, facsimile related parts, copier related parts, cleaning jigs, motor parts, lighters, typewriters, and other machine related parts; optical equipment and precision machinery related parts such as microscopes, binoculars, cameras, and watches; alternator terminals, alternator connectors, brush holders, slip rings, IC regulators, potentiometer bases for light dimmers, relay blocks, inhibitor switches, various valves such as exhaust gas valves, various pipes for fuel, exhaust systems and intake systems, air intake nozzle snorkels, intake manifolds, engine coolant joints, carburetor main bodies, carburetor spacers, exhaust gas sensors, coolant sensors, oil temperature sensors, brake pad wear sensors, throttle position sensors, crankshaft position sensors, temperature sensors, air flow meters, brake pad wear sensors, thermostat bases for air conditioners, heating hot air flow control valves, brush holders for radiator motors, water Examples of automobile and vehicle related parts include pump impellers, turbine vanes, wiper motor related parts, distributors, starter switches, ignition coils and bobbins, motor insulators, motor rotors, motor cores, starter relays, transmission wire harnesses, windshield washer nozzles, air conditioner panel switch boards, coils for fuel-related electromagnetic valves, fuse connectors, horn terminals, electrical component insulating plates, step motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid bobbins, engine oil filters, ignition device cases, and other various other applications.

The present invention will be described below using examples and comparative examples, but is not limited to these examples. In the following, unless otherwise specified, "%" and "parts" are based on mass.

<Reference Example: Production of PAS resin mixture>
220.5g (1.5 mol) of p-dichlorobenzene (p-DCB), 39.7g (0.30 mol) of N-methyl-2-pyrrolidone (NMP), 186.9g (1.5 mol) of 45% NaSH, and 125.0g (1.5 mol) of 48% NaOH were charged into a 1L autoclave equipped with a stirring blade and a bottom valve connected to a pressure gauge, a thermometer, a condenser, and a decanter, and the temperature was raised to 173°C under a nitrogen atmosphere while stirring. After 167.8g of water was distilled out, the kettle was sealed. At that time, the p-DCB distilled by azeotropy was separated in a decanter and returned to the kettle as needed. After the dehydration was completed, the temperature inside the autoclave was cooled to 160°C, 457.2g (4.6 mol) of NMP was added, and the temperature was raised to 220°C and stirred for 2 hours, and then the temperature was raised to 250°C and stirred for 1 hour to polymerize a PPS resin of 105 Pa·s. The crude reaction mixture containing the PAS resin after polymerization was cooled to 40° C., and taken out in a slurry state to be used as a PAS resin mixture.

Example 1-1 Mixing PPS and CNT Dispersion
A PAS resin mixture weighed out so that the PPS resin content was 20 g was mixed with 40 g of CNT dispersion and 60 g of NMP, and the mixture was stirred at room temperature for 1 hour. The amount of CNT in the mixed solution at this time was 0.8% by mass relative to the PPS resin, and the amount of NMP was 5 times (mass ratio) relative to the PPS resin. The CNT dispersion used was TUBALL (registered trademark) SWCNT (product name: TUBALL BATT NMP PVDF) from OCSiAl, in which 0.4% by mass of SWCNT and 2% by mass of PVDF were dispersed in NMP.

Example 1-2 Liquid Phase Removal and Cleaning
The mixture obtained by stirring was heated to 150°C under vacuum while stirring, and NMP was removed over 5 hours. After that, it was cooled to room temperature, and 200g of 70°C hot water was added to reslurry, and stirred for 10 minutes. While suction filtering the mixture, 200g of 70°C hot water was poured in three times to wash the cake. After repeating the reslurry and cake washing three times, the obtained cake and 200g of water were charged into a 500ml autoclave and washed with hot water at 230°C for 1 hour. After the hot water washing, the mixture was cooled to room temperature, and while suction filtering, 200g of 70°C hot water was poured in three times to wash the cake. The obtained cake was dried at 120°C for 4 hours to obtain 19.9g of PPS resin composition (1).

Example 2
The same procedure as in Example 1 was carried out, except that the amount of CNT dispersion added was changed from 40 g to 250 g, to obtain 24.7 g of a PPS resin composition (2-1). 6.2 g of the obtained PPS resin composition (2-1) was blended with 25.2 g of a PPS resin (linear type, melt viscosity (V6) 106 Pa·s), and the mixture was melt-kneaded and diluted at 310° C. for 10 minutes using a Labo Plastomill to obtain a PPS resin composition (2-2). The composition of the resin composition (2-2) was PPS/CNT/PVDF=100/0.8/4 (mass%).

<Comparative Example 1>
The same procedures as in Examples 1-1 and 1-2 were carried out except that the amount of the CNT dispersion liquid added was changed from 40 g to 0 g, thereby obtaining 18.6 g of a PPS resin composition (C1).

<Comparative Example 2>
In the reference example, except that 457.2 g of NMP charged in a 1 L autoclave was changed to 324.6 g of CNT dispersion and 132.6 g of NMP, a polymerization reaction was carried out in the same manner as in Example 1-2 to obtain a PPS resin crude product containing CNT. The obtained crude product was purified in the same manner as in Example 1-2, except that it was used instead of the "mixture obtained by stirring", to obtain 155.7 g of a PPS resin composition (C2).

<Evaluation>

(1) Evaluation of Electrical Conductivity Electrical conductivity was evaluated from the volume resistivity of the resin composition obtained in each Example and Comparative Example. The volume resistivity was measured using "Loresta AX MCP-T370" (upper limit of measurement: 10 ⁶ Ω·cm) manufactured by Nitto Seiko Analytech Co., Ltd., under conditions of room temperature of 21°C and humidity of 67 RH%, in accordance with JIS K 7194 "Test method for resistivity of conductive plastics by four-probe method". The test pieces were made by pressing the resin compositions obtained in each Example and Comparative Example at 310°C for 2 minutes and molding them into a plate shape (50 mm x 50 mm x 2 mmt). The results are shown in Table 1. The resin composition of Comparative Example 1 exceeded the upper limit of measurement by the instrument, so it was described as O.L.

(2) Measurement of Melt Viscosity (V6) The melt viscosity (V6) of the resin compositions obtained in each of the Examples and Comparative Examples was measured using a Shimadzu Corporation flow tester "CFT-500D" under the conditions of 300°C, load: 1.96 x ¹⁰⁶ Pa, and L/D = 10 (mm)/1 (mm) after holding for 6 minutes. The results are shown in Table 1.

From Table 1, comparing Examples 1 and 2 with Comparative Example 1, it was shown that CNTs were highly dispersed in the resin compositions obtained in the Examples, and that a reduction in volume resistivity was achieved by adding a small amount of CNTs. Also, comparing Examples 1 and 2 with Comparative Example 2, it was shown that the resin compositions of the Examples showed a higher melt viscosity at the same CNT content, and were more excellent in processability and mechanical strength.

Claims (7)

A method for producing a polyarylene sulfide resin composition in which carbon nanotubes are dispersed in a polyarylene sulfide resin, comprising the steps of:
A step (1) of contacting an organic polar solvent with a polyarylene sulfide resin to obtain a mixture (A) in which at least a portion of the polyarylene sulfide resin is dissolved in the organic polar solvent;
(2) adding a carbon nanotube dispersion liquid to the mixture (A) to obtain a mixture (B); and
A step (3) of subjecting the mixture (B) to solid-liquid separation to remove a liquid phase,
The method for producing a polyarylene sulfide resin composition, wherein the carbon nanotube dispersion contains at least carbon nanotubes and an organic polar solvent and/or water. The method for producing a polyarylene sulfide resin composition according to claim 1, wherein the content of the carbon nanotubes in 100 parts by mass of the resulting polyarylene sulfide resin composition is 20 parts by mass or less. The method for producing a polyarylene sulfide resin composition according to claim 1 or 2, wherein the carbon nanotube dispersion further contains a dispersion aid. 4. The method for producing a polyarylene sulfide resin composition according to claim 3 , wherein the hydrogen bond term (dH) in the Hansen solubility parameters of the dispersion aid is 1 to 10 [MPa ^0.5 ].
(Note that the hydrogen bond term (dH) is a value calculated by the atomic group contribution method using the Hansen Solubility Parameter software (HSPiP).) 3. The method for producing a polyarylene sulfide resin composition according to claim 1 or 2, wherein the volume resistivity of the obtained polyarylene sulfide resin composition is 1.0×10 ¹⁰ Ω·cm or less. A method for producing a polyarylene sulfide resin composition, comprising a step of melt-kneading the polyarylene sulfide resin composition obtained by the method for producing a polyarylene sulfide resin according to claim 1 or 2 with a polyarylene sulfide resin,
The method for producing a polyarylene sulfide resin composition, wherein the content of the carbon nanotubes in 100 parts by mass of the obtained polyarylene sulfide resin composition is 1.0 part by mass or less, and the volume resistivity is 1.0×10 ¹⁰ Ω·cm or less. A method for producing a polyarylene sulfide resin molded product, comprising a step of melt molding the polyarylene sulfide resin composition obtained by the manufacturing method described in claim 6.