JP2023000930A - Method for evaluating polyarylenesulfide resin - Google Patents

Abstract

To provide a method for evaluating polyarylenesulfide resin that can homogeneously quantify the surface characteristics of polyarylenesulfide resin, and thus has less variation and more homogeneous reactivity than a conventional evaluation method.SOLUTION: The present disclosure is a method for evaluating polyarylenesulfide resin having a preparation step of preparing polyarylenesulfide resin, and an evaluation step of evaluating a test piece formed from at least part of the polyarylenesulfide resin. In the method for evaluating polyarylenesulfide resin, the evaluation step has a test piece manufacturing step of solidifying melted polyarylenesulfide resin obtained by melting the polyarylenesulfide resin to obtain the test piece, and a zeta potential measuring step of measuring the zeta potential of the surface of the test piece with a flow potential method.SELECTED DRAWING: None

Description

The present invention relates to a method for evaluating polyarylene sulfide resins.

Polyarylene sulfide resins (hereinafter also abbreviated as "PAS resins") typified by polyphenylene sulfide resins (hereinafter abbreviated as "PPS resins") are excellent in heat resistance, chemical resistance, etc. Therefore, it is widely used for electrical and electronic parts, automobile parts, plumbing parts, fibers, films, and the like. The PAS resin used for the above applications maximizes its functions by combining various additives such as glass fibers, fillers, elastomers, and the like. Therefore, controlling the interfacial reactivity between an additive such as glass fiber and the PAS resin and the reactivity between the elastomer and the PAS resin is an essential technology for the functional expression of the obtained PAS resin (parts). For example, Patent Literature 1 discloses a technique related to a PAS resin having higher reactivity with epoxysilane than conventional PAS resins.

JP-A-06-256517

However, in the technique of Patent Document 1, no consideration has been given to the functional group at the molecular end of the PAS resin, which is a factor that greatly contributes to the reactivity of the interface between the PAS resin and the different material. In addition, the PAS resin has a unique circumstance that it is polymerized at a high temperature of 200° C. or higher and under a high pressure. As a result, many side reactions occur during the polymerization of the PAS resin, resulting in the presence of various functional groups at the molecular ends of the PAS resin, which greatly contribute to the reactivity. Furthermore, the high heat resistance/chemical resistance of PAS resins limits the analytical prescriptions, and the present situation is that the amounts of various functional groups have not yet been quantified.
Therefore, controlling and evaluating the reactivity of the interface between the PAS resin and the dissimilar material by the molecular terminal structure of the PAS resin is a very difficult technology, but it is expected to be applied in various fields. It is a technology required by

Therefore, the present disclosure provides a method for evaluating a PAS resin that has less variation and more accurate reactivity than the conventional evaluation method using the degree of viscosity increase by quantifying the surface properties of the PAS resin. for the purpose.

In view of the above problems, the present inventors have made intensive research and repeated experiments. The present invention has been completed.

[1] The present disclosure provides a preparatory step of preparing a polyarylene sulfide resin;
A method for evaluating a polyarylene sulfide resin, comprising: an evaluation step of evaluating a test piece formed from at least a portion of the polyarylene sulfide resin,
The evaluation step includes a test piece preparation step of obtaining the test piece by solidifying the molten polyarylene sulfide resin obtained by melting the polyarylene sulfide resin;
and a zeta potential measurement step of measuring the zeta potential of the surface of the test piece by a streaming potential method.
[2] A more preferred embodiment of the present disclosure is a polymerization step of obtaining a polyarylene sulfide resin;
A purification step of purifying the polyarylene sulfide resin;
and an evaluation step of evaluating a test piece formed from at least a portion of the purified polyarylene sulfide resin obtained through the purification step.
The evaluation step includes a test piece preparation step of obtaining the test piece by solidifying the molten PAS resin obtained by melting the polyarylene sulfide resin;
and a zeta potential measurement step of measuring the zeta potential of the surface of the test piece under conditions of pH 3 to 9 by streaming potential method.

According to the present disclosure, by evaluating the surface properties of the PAS resin using the zeta potential, it is possible to grasp the reactivity of the PAS resin with less variation and with higher accuracy than the evaluation method using the degree of viscosity increase.

FIG. 1 is a schematic diagram showing an example of a method for measuring zeta potential by streaming potential method.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail. can be implemented.

[Method for evaluating polyarylene sulfide resin]
The PAS resin evaluation method according to the present embodiment includes a preparation step of preparing the PAS resin and an evaluation step of evaluating a test piece produced from at least part of the PAS resin obtained in the preparation step. The evaluation step includes a test piece preparation step of obtaining the test piece by melting the PAS resin obtained in the preparation step to prepare a molten PAS resin, and then solidifying the molten PAS resin; and a zeta potential measurement step of measuring the zeta potential of the surface of the piece by a streaming potential method.
In other words, in the method for evaluating the PAS resin of the present embodiment, for the purpose of evaluating the surface properties of the prepared PAS resin, a test piece, which is an evaluation sample, is prepared from at least a part of the PAS resin, and then the streaming potential method is used. The surface characteristics of the prepared PAS resin are grasped by measuring the zeta-potential of the test piece.
As a result, the surface properties of the PAS resin can be uniformly quantified, so the reactivity of the PAS resin can be evaluated with less variation and with higher accuracy than conventional evaluation methods (e.g., degree of viscosity increase using MFR, etc.). .
Further, in the PAS resin evaluation method according to the present embodiment, the zeta potential measurement step preferably measures the zeta potential of the surface of the test piece under conditions of pH 3 to 9, more preferably pH 7.8 to 8.2. It is preferable to measure under the conditions of
This not only reduces variations but also makes it easier to evaluate the properties of the PAS resin with higher accuracy.
Furthermore, in a preferred aspect of the PAS resin evaluation method according to the present embodiment, the zeta potential value of the surface of the test piece measured in a range under a predetermined pH condition is within a specific range by the zeta potential measurement step. It may further have a determination step of determining whether or not it is included. Although the determination step will be described later, for example, the zeta potential value of the surface of the test piece measured in the range of pH 7.8 to 8.2 (eg, pH = 8.0) by the zeta potential measurement step , -50 to -65 mV. Thereby, a PAS resin having excellent reactivity can be provided.

（上記一般式（１）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）：

で表される３官能性の構造部位と、を繰り返し単位に有する樹脂構造であることが好ましい。前記一般式（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。 Each step of the PAS resin evaluation method of the present embodiment will be described below.
"Preparation process"
The preparation step in this embodiment is a step of preparing a PAS resin. The PAS resin prepared as an evaluation target of the present embodiment is not particularly limited as long as it has a chemical structure in which a structure in which an aromatic ring and a sulfur atom are bonded is a repeating unit, and a known polymerization It may be a PAS resin obtained by the process or a commercially available PAS resin may be used. In addition, although the known polymerization method is not particularly limited, an example of the polymerization method includes the polymerization method described in the section of the polymerization process below.
(PAS resin)
Specifically, the chemical structure of the PAS resin used in the evaluation method of this embodiment is represented by the following general formula (1):

(In general formula (1) above, 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, the following general formula (2):

It is preferable that the resin structure has a trifunctional structural site represented by and a repeating unit. The trifunctional structural site represented by the general formula (2) is preferably in the range of 0.001 to 3 mol%, particularly 0.01 to 1 mol%, relative to the total number of moles with other structural sites. is preferably in the range of

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

Among these, the 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 desirable in terms of heat resistance and crystallinity of the PAS resin. preferable.

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。 In addition, the PAS resin is not only the structural site represented by the general formula (1) or (2), but also the following general formulas (5) to (8):

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

In addition, the PAS resin may have a naphthyl sulfide bond or the like in its molecular structure. The following are preferable.
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.
In the preparation step in the present embodiment, the PAS resin is preferably prepared by a polymerization step for obtaining the PAS resin, and more preferably, the PAS resin is prepared by a polymerization step for obtaining the PAS resin and a purification step for purifying the PAS resin. to prepare. In this embodiment, one example of the polymerization step and the purification step will be described below.

(Polymerization process)
In the present embodiment, the polymerization process for obtaining the PAS resin is not particularly limited, and a known polymerization method can be applied depending on the chemical structure of the PAS resin to be evaluated or the intended use of the PAS resin. Further, as a preferred aspect of the polymerization step in the present embodiment, the zeta potential value of the surface of the test piece, which is an evaluation sample formed from at least a part of the obtained PAS resin, is pH = 7.8 to 8.2 ( For example, a specific polymerization that tends to exhibit a range of -50 to -65 mV at pH = 8.0) or a range of -30 to -45 mV at pH = 4.8 to 5.2 (e.g., pH = 5.0) Additional conditions may apply.
Therefore, a general polymerization method applicable to the present embodiment will be described below, and then specific polymerization conditions will be described in detail.

<Polymerization method>
Representative examples of polymerization methods applicable to the present embodiment include, for example, Production Methods 1 to 4 below.
(Manufacturing method 1): A method of polymerizing a dihalogeno aromatic compound in the presence of sulfur and sodium carbonate, if necessary, by adding a polyhalogeno aromatic compound or other copolymerization components (Manufacturing method 2): Solvent (e.g., A dihalogeno aromatic compound is added in the presence of a sulfidating agent or the like in a polar solvent, an organic solvent, or a polar organic solvent), and if necessary, a polyhalogeno aromatic compound or other copolymerization components (hereinafter referred to as dihalogeno aromatic compounds) are added. (Manufacturing method 3): Self-condensation by adding p-chlorothiophenol and, if necessary, other copolymerization components (Manufacturing method 4): A diiodo aromatic compound and elemental sulfur are combined with carboxy A method of melt-polymerizing under reduced pressure in the presence of a polymerization inhibitor which may have a functional group such as a group or an amino group.

Among the above production methods 1 to 4, the above (production method 2) method is versatile and preferred. During the reaction, an alkali metal salt of carboxylic acid or sulfonic acid, or an alkali hydroxide may be added in order to adjust the degree of polymerization. Among the above (manufacturing method 2) methods, a compound containing a dihalogenoaromatic compound, a polar organic solvent, and a sulfidating agent has a ratio of (polar organic solvent)/(sulfidating agent)=0.02/1 to 0. .9/1 (molar ratio) is charged to the reactor, and the temperature is preferably started to rise in an open system under an inert gas atmosphere to dehydrate the compound and solidify as the dehydration progresses. After precipitating the substance and obtaining a low water content solid in which each component is uniformly dispersed, it is cooled to a predetermined temperature, and if necessary, a polar organic solvent and / or a dihalogeno aromatic compound is further added to the low water content solid. and, if necessary, a dihalogeno aromatic compound in the presence of a solid alkali metal sulfide and an aprotic polar organic solvent. A polyhalogeno aromatic compound or other copolymerization components are added, and an alkali metal hydrosulfide and an organic acid alkali metal salt are added in an amount of 0.01 to 0.9 mol per 1 mol of the sulfur source. Particularly preferred is a method of conducting the reaction while controlling the amount of water in the reaction system within the range of 0.02 mol or less per 1 mol of the aprotic polar organic solvent (see WO2010/058713 pamphlet).

The polymerization process of the present embodiment includes a polymerization method using the production method 2, more specifically, at least one polyhalogenoaromatic compound and at least one sulfidation in a polar solvent (e.g., a polar organic solvent). An example of the process of obtaining a reaction mixture (slurry) containing a PAS resin obtained by reacting a PAS resin under appropriate polymerization conditions will be described below.
Further, in the present embodiment, the reaction mixture (slurry) is obtained by reacting the polyhalogenoaromatic compound and/or the organic solvent in the presence of the sulfidating agent and the organic solvent while continuously or intermittently adding the compound. It also includes forms that are

-material-
The polyhalogenoaromatic compound in the present embodiment is a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic ring. called a compound. Specific examples of the 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'-dihalodiphenyl sulfone, 4,4'-dihalodiphenyl sulfoxide, 4,4'-dihalodiphenyl sulfide, and each of the above compounds Examples thereof include compounds having an alkyl group having 1 to 18 carbon atoms on the aromatic ring. The above dihalogeno aromatic compounds may be used alone or in combination of two or more. Polyhalogeno aromatic compounds other than dihalogeno 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 and the like. Moreover, you may block-copolymerize these compounds. Among the above specific examples, preferred are dihalogenated benzenes, and particularly preferred are those containing 80 mol % or more of p-dichlorobenzene. The polyhalogeno aromatic compounds described above may be used alone or in combination of two or more. Further, the halogen atoms contained in each halogenoaromatic compound are preferably chlorine atoms and/or bromine atoms.

For the purpose of increasing the viscosity of the PAS resin by forming a branched structure, a polyhalogeno aromatic compound having 3 or more halogen substituents in one molecule may be used as a branching agent, if desired. Examples of such polyhalogenoaromatic compounds include 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,4,6-trichloronaphthalene and the like.

Furthermore, polyhalogeno aromatic compounds having functional groups with active hydrogen such as amino groups, thiol groups, hydroxyl groups, etc. can be mentioned, and specifically, 2,6-dichloroaniline and 2,5-dichloroaniline. , 2,4-dichloroaniline, 2,3-dichloroaniline and other dihaloanilines; 2,3,4-trichloroaniline, 2,3,5-trichloroaniline, 2,4,6-trichloroaniline, 3, trihaloanilines such as 4,5-trichloroaniline; dihaloaminodiphenyl ethers such as 2,2'-diamino-4,4'-dichlorodiphenyl ether and 2,4'-diamino-2',4-dichlorodiphenyl ether and compounds in which an amino group is replaced with a thiol group or a hydroxyl group in a mixture thereof.

In addition, active hydrogen-containing polyhalogens in which the hydrogen atoms bonded to the carbon atoms forming the aromatic ring in these active hydrogen-containing polyhalogeno aromatic compounds are substituted with other inert groups, for example, hydrocarbon groups such as alkyl groups. Aromatic compounds can also be used. Among these various active hydrogen-containing polyhaloaromatic compounds, preferred are active hydrogen-containing dihalogenoaromatic compounds, and particularly preferred is dichloroaniline.

Examples of polyhalogenoaromatic compounds having a nitro group include mono- or dihalonitrobenzenes such as 2,4-dinitrochlorobenzene and 2,5-dichloronitrobenzene; 2-nitro-4,4'-dichlorodiphenyl ether and the like. dihalonitrodiphenyl ethers; 3,3′-dinitro-4,4′-dichlorodiphenyl sulfones such as dihalonitrodiphenyl sulfones; 2,5-dichloro-3-nitropyridine, 2-chloro-3,5 - mono- or dihalonitropyridines such as dinitropyridine; or various dihalonitronaphthalenes.

In this embodiment, the PAS resin must be dissolved in an organic solvent, so the organic solvent used must be capable of dissolving the PAS resin under certain conditions. The conditions for dissolving the PAS resin may be room temperature or heating, but currently known solvents require heating to a certain temperature in order to dissolve the PAS resin having a molecular weight above a certain level. Organic solvents capable of dissolving the PAS resin include N-methyl-2-pyrrolidone, formamide, acetamide, N-methylformamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methyl-ε-caprolactam, ε - caprolactam, hexamethylphosphoramide, tetramethylurea, N-dimethylpropyleneurea, amidourea of 1,3-dimethyl-2-imidazolidinoic acid and lactams; sulfolanes such as sulfolane, dimethylsulfolane; benzonitrile ketones such as methylphenylketone; other solvents such as polyethylene dialkyl ether, 1-chloronaphthalene, diphenyl sulfide and the like.

Examples of the sulfidating agent used in the present embodiment include alkali metal sulfides and alkali metal hydrosulfides (both are collectively referred to as alkali metal sulfides hereinafter). Such alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide and mixtures thereof. Such alkali metal sulfides can be used as hydrates or as aqueous mixtures or as anhydrates. Alkali metal sulfides can also be derived from the reaction between alkali metal hydrosulfides and alkali metal hydroxides.
The alkali metal hydrosulfides include sodium hydrosulfide, potassium hydrosulfide, lithium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide, and mixtures of two or more thereof.
A small amount of alkali metal hydroxide may be added in order to react with alkali metal hydrosulfide and alkali metal thiosulfate, which are usually present in trace amounts in alkali metal sulfide. In the polymerization reaction of the PAS resin, the above alkali metal sulfides and alkali metal hydroxides, which are called so-called sulfidating agents, can be reacted with the polyhalogenoaromatic compound in the presence of these organic polar solvents.

-Polymerization conditions and recovery-
A preferable polymerization temperature of the PAS resin in this embodiment is in the range of 200 to 330°C. Further, the pressure during polymerization of the PAS resin should be in a range such that the polyhalogenoaromatic compound, which is the polymerization solvent and the polymerization monomer, is substantially kept in the liquid layer, and generally preferably in the range of 0.1 to 20 MPa. , more preferably from the range of 0.1 to 2 MPa. The polymerization reaction time varies depending on temperature and pressure, but is generally preferably in the range of 10 minutes to 72 hours, more preferably in the range of 1 hour to 48 hours.
Further, in the present embodiment, the reaction mixture (slurry) containing the PAS resin obtained in the polymerization step is subjected to an appropriate means (reduced pressure distillation method, centrifugal separation method, screw decanter method, reduced pressure filtration method) in the purification step described later. , a suitable method such as pressure filtration can be selected), and after separating and removing the organic solvent, the crude polyarylene sulfide resin (PAS resin that has not undergone the purification step) can be recovered.

In the polymerization step of the present embodiment, a reaction mixture containing a PAS resin obtained by reacting at least one polyhalogenoaromatic compound with at least one alkali metal sulfide as a sulfidating agent in an organic solvent ( It is preferable to be a step of obtaining a slurry). Therefore, in the polymerization step, it is sufficient that the organic solvent, the polyhalogeno aromatic compound, and the alkali metal sulfides, which are added as raw materials, are brought into contact with each other so that the polymerization reaction proceeds. At least one selected from the group consisting of aromatic compounds and alkali metal sulfides may not be added in an amount required for the polymerization reaction from the charging stage. In other words, at least one selected from the group consisting of the organic solvent, the polyhalogenoaromatic compound, and the alkali metal sulfides is added until the polymerization reaction is completed, in order to make the amount of raw materials charged necessary for the polymerization reaction. The reaction may be performed while adding continuously or intermittently.

In the polymerization step of the present embodiment, dehydration treatment may be performed before polymerization, if necessary, for the purpose of adjusting the amount of water in the reaction system. Specifically, the organic solvent, polyhalogenoaromatic compound and alkali metal sulfide or alkali metal hydrosulfide, which are raw materials, are heated at a temperature range of normal temperature (25° C.) to 230° C., preferably in an inert gas atmosphere. On the other hand, it is preferable to proceed with the polymerization step after performing the dehydration treatment.
The amount of water in the reaction system is the amount obtained by subtracting the amount of water removed from the reaction system from the amount of water added to the reaction system as an aqueous solution or hydrate when the raw materials were charged.
Further, the order of adding the organic solvent, the polyhalogenoaromatic compound and the alkali metal sulfides to a reactor such as an autoclave is not particularly limited, but for example, the polymerization step in the present embodiment is as follows. Embodiments (A) and (B) are preferred.
Mode (A): After bringing the alkali metal sulfides, the organic solvent, and the polyhalogenoaromatic compound into contact, the alkali metal sulfides, the organic solvent, and the polyhalogenoaromatic compound were brought into contact with each other at room temperature (25° C. ) above, preferably to near the polymerization temperature (170° C. to 300° C.).
Embodiment (B): The alkali metal sulfides and the organic solvent are brought into contact with each other, and the alkali metal sulfides and the organic solvent are heated to room temperature (25° C.) or higher, preferably around the polymerization temperature (170° C. to 300° C.). After heating to , the alkali metal sulfides and the polyhalogenoaromatic compound are brought into contact.
In addition, the conditions described in the section "-Polymerization conditions and recovery-" may be applied to the polymerization steps using the above modes (A) and (B).

<Specific polymerization conditions>
When the PAS resin used in the preparation step of the present embodiment is prepared by the polymerization step, it is an evaluation sample formed from at least a part of the PAS resin obtained by the polymerization step (or the polymerization step and the purification step described later). The zeta potential value of the surface of the test piece preferably exhibits a range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0). PAS resin, which exhibits a zeta potential value on the surface of the test piece in the range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0), has excellent reactivity. The PAS resin composition further containing the material and its molded product can exhibit fluidity with little variation and excellent mechanical properties. The specific polymerization conditions necessary for the zeta potential value of the surface of the test piece to tend to show a range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0) are as follows. conditions (a) to (c).
(a) The total amount of the organic solvent used from the charging of the raw materials to the completion of the polymerization reaction is preferably 1 to 6 mol per 1 mol of the alkali metal sulfides as the sulfur source.
(b) The amount of the organic solvent initially charged is preferably 0.01 to 0.50 mol per 1 mol of the alkali metal sulfides as the sulfur source.
(c) It is preferable to add an acid or a hydrogen salt to the PAS resin (or reaction mixture (slurry)) after the polymerization reaction in the polymerization step. More preferably, an acid or a hydrogen salt is added to the PAS resin (or reaction mixture (slurry)) after the polymerization reaction in the polymerization step to adjust the pH of the reaction mixture to 7-11.

As the organic solvent under the above conditions (a) and (b), aliphatic cyclic compounds are preferred, such as N-methyl-2-pyrrolidone (NMP), N-cyclohexylpyrrolidone, N-methylcaprolactam, ε-caprolactam, sulfolane. Or dimethylsulfolane is more preferred, and N-methyl-2-pyrrolidone (NMP) is particularly preferred.

Examples of the acid under the condition (c) include saturated fatty acids such as carbonic acid, oxalic acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and monochloroacetic acid; acrylic acid, crotonic acid, oleic acid, and the like; aromatic carboxylic acids such as unsaturated fatty acids, benzoic acid, phthalic acid and salicylic acid; dicarboxylic acids such as oxalic acid, maleic acid and fumaric acid; organic acids such as methanesulfonic acid and sulfonic acids such as p-toluenesulfonic acid; Inorganic acids such as sulfuric acid, sulfurous acid, nitric acid, nitrous acid or phosphoric acid may be mentioned.
Examples of the hydrogen salt under the condition (c) include sodium hydrogen sulfate, disodium hydrogen phosphate, sodium hydrogen carbonate, and the like. Organic acids that cause less corrosion to metal members are preferred for use in actual machines.

In the polymerization step of the present embodiment, when the above condition (a) is adopted, the concentration of the PAS resin during polymerization increases, so that the reaction in which the ring-opened product of the aliphatic cyclic compound is imparted to the end of the PAS resin proceeds. specific zeta potential values because it is easier to
In the polymerization step of the present embodiment, when the above condition (b) is adopted, the concentration of the PAS resin during polymerization increases, so that the reaction in which the ring-opened product of the aliphatic cyclic compound is imparted to the end of the PAS resin proceeds. specific zeta potential values because it is easier to
In the polymerization step of the present embodiment, when the above condition (c) is adopted, the acidic component is included in the PAS resin, and the acidic component oozes out in the purification step, resulting in some of the terminal functional groups of the PAS resin. can exhibit a particular zeta potential value because it ion-exchanges and protonates.

In the present embodiment, in order for the zeta potential value of the surface of the test piece to be in the range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0), the polymerization step or the following purification step WHEREIN: It is preferable to add an acid to the said PAS resin. Therefore, among the above polymerization conditions (a) to (c), particularly by satisfying (c), there is a strong tendency for the zeta potential value to fall within a predetermined range.
As another aspect of this embodiment, the zeta potential value of the surface of the test piece tends to show a range of -30 to -45 mV at pH 4.8 to 5.2 (eg, pH = 5.0). As specific polymerization conditions, the above conditions (a) to (c) can be applied.

As one aspect of the preferred polymerization process of the present embodiment, a PAS resin obtained by reacting at least one polyhalogenoaromatic compound with at least one alkali metal sulfide as a sulfidating agent in an organic solvent is prepared. In the step of obtaining a reaction mixture (slurry) containing the organic solvent, the total amount of the organic solvent used until the completion of the reaction is 1 to 6 mol per 1 mol of the total amount of the alkali metal sulfides. Further, it is more preferable to combine the main polymerization step with the above aspect (A) or the above aspect (B).

Further, as another preferred aspect of the polymerization step of the present embodiment, after contacting at least one alkali metal sulfide, an organic solvent and at least one polyhalogenoaromatic compound, the alkali metal sulfide , the organic solvent, and the polyhalogenoaromatic compound are heated to room temperature (25°C) or higher, preferably to the vicinity of the polymerization temperature (170°C to 300°C), to form the polyhalogenoaromatic compound and the polyhalogenoaromatic compound in the organic solvent. A step of obtaining a reaction mixture (slurry) containing a PAS resin obtained by reacting with an alkali metal sulfide,
When the alkali metal sulfides, the organic solvent, and the polyhalogenoaromatic compound are brought into contact, the amount of the organic solvent is in the range of 0.01 to 0.50 mol per 1 mol of the alkali metal sulfides. Preferably.

Furthermore, as another preferred aspect of the polymerization process of the present embodiment, a polymer obtained by reacting at least one polyhalogenoaromatic compound with at least one alkali metal sulfide as a sulfidating agent in an organic solvent. a step of obtaining a reaction mixture (slurry) containing a PAS resin that can , preferably after heating to near the polymerization temperature (170 ° C. to 300 ° C.), the reaction mixture (slurry) obtained by contacting the alkali metal sulfides and the polyhalogeno aromatic compound to react. Alternatively, it is a step of adding a hydrogen salt to adjust the pH of the reaction mixture (slurry) to 7 to 11.

(Refining process)
In the present embodiment, it is preferable to further perform a purification step after the polymerization step, if necessary. The purification step of the present embodiment can be a step of purifying the PAS resin obtained from the polymerization step. This allows the surface properties of the PAS resin to be more modified or more homogenized.
For the purification step in this embodiment, a known purification process can be applied according to the chemical structure of the PAS resin to be evaluated. In addition, when the PAS resin used in the preparation step of the present embodiment is prepared by the polymerization step, the zeta of the surface of the test piece, which is the evaluation sample, formed from at least a part of the PAS resin obtained by the polymerization step and the purification step. The potential value preferably exhibits a range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0). A PAS resin having good reactivity can be provided by exhibiting a zeta potential value in the range of -50 to -65 mV at pH 7.8 to 8.2 (for example, pH = 8.0) on the surface of the test piece.
As a preferred aspect of the purification step in the present embodiment, a specific Additional purification conditions apply.
Another preferred aspect of the purification step in the present embodiment is that the zeta potential value of the surface of the test piece is in the range of -30 to -45 mV at pH = 4.8 to 5.2 (eg, pH = 5.0). Specific purification conditions that are easy to demonstrate may also be applied.

Hereinafter, after explaining the purification process applicable to the present embodiment, the specific purification conditions will be explained in detail.
In the present embodiment, the purification treatment of the PAS resin (reaction mixture (slurry) containing the PAS resin) obtained in the polymerization step is not particularly limited, but for example, the following purification treatments 1 to 5 can be mentioned. be done.
Purification process 1: After the completion of the polymerization reaction, the reaction mixture (slurry) is used as it is, or after adding an acid or base, the solvent is distilled off under reduced pressure or normal pressure, and then the solid after solvent distillation (crude PAS The resin) is washed once or twice with a washing solution such as (hot) water, a reaction solvent (or an organic solvent having an equivalent solubility for the low-molecular-weight polymer), acetone, methyl ethyl ketone, alcohols, etc., and then neutralized. , (hot) washing, filtering and drying,
Purification process 2: After the polymerization reaction is completed, the reaction mixture (slurry) is added with solvents such as (hot) water, acetone, methyl ethyl ketone, alcohols, ethers, halogenated hydrocarbons, aromatic hydrocarbons, and aliphatic hydrocarbons ( A solvent that is soluble in the organic solvent used and is a poor solvent for at least the PAS resin) is added as a precipitant to precipitate the solid matter (crude PAS resin) containing the PAS resin and inorganic salts. , a method of filtering, washing and drying these,
Purification process 3: After completion of the polymerization reaction, the reaction mixture (slurry) was added with a reaction solvent (or an organic solvent having an equivalent solubility to the low-molecular-weight polymer) and stirred, followed by filtration to remove the low-molecular-weight polymer. The solid (crude PAS resin) is washed once or twice with a washing solution such as (hot) water, acetone, methyl ethyl ketone, alcohols, etc., then neutralized, washed with (hot) water, filtered and dried. Method,
Purification process 4: After completion of the polymerization reaction, add (hot) water as a washing solution to the reaction mixture (slurry), wash with (hot) water, and filter the resulting solid (crude PAS resin). Depending on the situation, an acid is added at the time of (hot) water washing for acid treatment, followed by drying. On the other hand, if necessary, a method of washing with a reaction solvent as a washing solution once or twice or more, further washing with (hot) water, filtering and drying, and the like can be mentioned.
In the purification treatments exemplified in the purification treatments 1 to 5 above, the drying of the PAS resin may be carried out in a vacuum, in the air, or in an atmosphere of an inert gas such as nitrogen. .

In the purification step of the present embodiment, a washing solution is added to the reaction mixture (slurry) containing the PAS resin obtained in the polymerization step or the crude PAS resin, which is the solid content of the reaction mixture (slurry), for washing treatment and filtration. It is preferable that it is a step of performing a treatment and a drying treatment. In addition, each of the washing treatment, filtering treatment and drying treatment in which the washing solution is added can be performed at least once or more than once.
The term "crude PAS resin" as used herein refers to a solid content obtained by subjecting the reaction mixture (slurry) containing the PAS resin obtained in the polymerization step to solid-liquid separation one or more times.

The washing treatment is not particularly limited, and acid washing, (hot) water washing, solution washing with the above washing solution or reaction solvent can be performed once or multiple times.
The cleaning solution that can be used for the cleaning treatment in this embodiment is not particularly limited, and examples include water, hot water, acid solution, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, and dimethylsulfoxide. , dimethyl sulfone, acetone, methyl ethyl ketone, diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, tetrahydrofuran, chloroform, methylene chloride, trichlorethylene, ethylene dichloride, dichloroethane, tetrachloroethane, chlorobenzene, methanol, ethanol, propanol, butanol, pen Tanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, benzene, toluene, xylene and the like. The cleaning solutions may be used singly or in combination of two or more.
The temperature of the cleaning solution is preferably 140-260°C. As a method of washing with a washing solution at 140 to 260° C., it is preferable to wash the crude PAS resin while pressurizing the washing solution (for example, a pressure range of 0.1 to 5 MPa).
The drying treatment is not particularly limited, and drying is preferably performed at a drying temperature of 120 to 270°C. The atmosphere for the drying treatment includes a reduced pressure atmosphere, a nitrogen or inert gas atmosphere, an oxidizing atmosphere such as oxygen or air, and a mixed gas atmosphere of air and nitrogen. The drying time is preferably 0.5 to 53 hours. The filtration treatment is not particularly limited as long as it is a method capable of solid-liquid separation, and examples include a method of solid-liquid separation using a filter, a centrifuge, or the like.

<Specific purification conditions>
In the purification step of the present embodiment, the zeta potential value of the surface of the test piece tends to be in the range of -50 to -65 mV at pH 7.8 to 8.2 (eg, pH = 8.0). Purification conditions include the following conditions (d) to (f).
(d) In the purification step, it is preferable to acid-treat the crude PAS resin with a predetermined amount or more of an acid solution. More preferably, the acid treatment is performed using an acid solution of about twice the total weight of the PAS resin.
(e) The pH of the acid solution used in the acid treatment of (d) is preferably 6 or less.
(f) In the purification step, it is preferable to wash the PAS resin with hot water at 140 to 260° C. in an amount of 1.5 to 10 times the total weight of the PAS resin.

When the conditions (d), (e), and (f) above are employed in the purification step of the present embodiment, ion exchange occurs and the terminal functional groups of the PAS resin can be protonated.
The acid used for the acid solution is not particularly limited as long as an acid solution having a pH of 6 or less can be prepared, and the acid under the condition (c) above can be used.

In the present embodiment, the polymerization step or In the purification step, an acid may be added to the PAS resin. More specifically, in the preferred purification step of the present embodiment, the PAS resin obtained in the polymerization step (including the reaction mixture (slurry)) or the reaction mixture (slurry) containing the PAS resin obtained in the polymerization step is This includes acid treatment by adding an acid solution to the crude PAS resin, which is the solid content after solid-liquid separation.
Further, as another aspect of the preferred purification step of the present embodiment, the PAS resin obtained in the polymerization step (including the reaction mixture (slurry)) or the reaction mixture containing the PAS resin obtained in the polymerization step (slurry In the step of adding a washing solution to the solid content of the crude PAS resin, washing, filtering and drying, the crude PAS resin is subjected to acid treatment by adding an acid solution once or more.
As another aspect of the present embodiment, the zeta potential value of the surface of the test piece tends to be in the range of -30 to -45 mV at pH 4.8 to 5.2 (eg, pH = 5.0). As the necessary specific purification steps, conditions (d) to (f) above can be applied in the same manner as in the measurement system at pH 7.8 to 8.2 (eg, pH=8.0).

"Evaluation process"
The evaluation step in this embodiment is a step of evaluating a test piece produced from at least part of the PAS resin obtained in the preparation step. The evaluation process includes a test piece preparation process and a zeta potential measurement process.
In other words, in the evaluation step in the present embodiment, a test piece (=evaluation sample) is prepared from at least a portion of the PAS resin (including the polymerized and purified PAS resin) obtained in the preparation step, and the test piece is prepared. This is a step of measuring the zeta potential under predetermined conditions to evaluate the surface physical properties of the test piece and grasp the physical properties of the PAS resin. Therefore, in the evaluation process of the present embodiment, the chemical properties of the PAS resin, which is the raw material of the test piece, are quantified using the zeta potential value of the surface of the test piece, which is an evaluation sample formed from the PAS resin. Accordingly, it is not necessary to evaluate the entire amount of the PAS resin prepared in the preparation step, and it is sufficient to evaluate the PAS resin obtained in the preparation step. Moreover, the test piece obtained in the test piece preparation step is preferably made of an amorphous PAS resin.
Since the evaluation step in the present embodiment can identify a PAS resin having a zeta potential value within a predetermined range, the surface properties of the PAS resin can be quantified with high accuracy.

The test piece preparation process and the zeta potential measurement process will be described in detail below.
(Test piece preparation process)
The test piece preparation step in this embodiment is a step of preparing a molten PAS resin by melting the PAS resin obtained in the preparation step, and then solidifying the molten PAS resin to prepare a test piece.
In other words, in the test piece preparation step in the present embodiment, at least part of the PAS resin (including polymerized and purified PAS resin) obtained in the preparation step is sampled and melted once, and then the melted PAS resin is It is a step of producing a test piece having a predetermined shape and surface characteristics by solidification. From the viewpoint of performing evaluations that are more in line with the molten state, the test piece of the present embodiment is preferably in an amorphous state.

The term "amorphous state" as used herein refers to a state in which no crystalline phase exists in the PAS resin constituting the test piece, and more specifically, the following condition (i) is satisfied.
(i) In the DSC measurement of the PAS resin film which is the test piece, when the temperature range from 40 ° C. to 350 ° C. is raised at 20 ° C./min, an exothermic peak accompanying crystallization occurs between 100 ° C. and 200 ° C. is not confirmed.

In addition, in the evaluation method of the present embodiment, the zeta potential value of the surface of the test piece made from the PAS resin is used to quantify the chemical properties of the PAS resin that is the raw material of the test piece. The reason why the reactivity of the PAS resin is evaluated from the surface chemical properties is that the PAS resin has extremely high chemical resistance. With respect to PPS resin, which is a particularly preferred embodiment of PAS resin, the presence of a solvent capable of dissolving the PPS resin at 200° C. or lower has not yet been found. This is because there is practically no technique for directly measuring the molecular ends in the PAS resin, which greatly contributes to reactivity. Therefore, in the present disclosure, by using a specific test piece as a reference, the properties of the PAS resin, which is the constituent material of the test piece, are understood.

<melting>
In this embodiment, the method of melting the PAS resin obtained in the preparation step to prepare the molten PAS resin includes a method of heating and melting the purified PAS resin using a heating means.
The heating means is not particularly limited as long as it can heat and melt the PAS resin obtained in the preparatory step, and known heating means can be employed. Specific examples include hot plates, oil baths, hot/cold air circulation type constant temperature ovens, microwave or (far) infrared heaters, rolls heated for temperature control, heat pipe rolls, metal belts or hot presses. .
The heating time for heating the PAS resin using the heating means is not particularly limited as long as the PAS resin is melted, and is, for example, about 30 seconds to 10 minutes. In the present embodiment, the temperature for melting the PAS resin obtained in the preparatory step may be at least the melting point of the PAS resin, preferably 300° C. or higher and 400° C. or lower. Since the PAS resin undergoes an oxidative cross-linking reaction at a temperature of 200° C. or higher, it may be thermally melted in a non-oxidizing inert gas atmosphere.

In the test piece preparation step of the present embodiment, the PAS resin obtained in the preparation step may be heated and melted through the sheet body for the purpose of easily obtaining a test piece of a predetermined size. As a more detailed heat-melting method, after placing the PAS resin (for example, powdered PAS resin) obtained in the preparation step on the sheet body, the sheet body is heated using a heating means. It is preferable to prepare a molten PAS resin by melting the PAS resin. As another method of heating and melting, the PAS resin obtained in the preparation step (for example, solid or powdered purified PAS resin) is sandwiched between a pair of sheets, and then heated by the heating means. It is preferable that the pair of sheets or one of the pair of sheets is heated using to melt the PAS resin to prepare a molten PAS resin.

By using the sheet body, it is possible to easily collect the test piece in which the molten PAS resin is solidified. In particular, the sheet body preferably has releasability. As a result, the test piece can be easily collected without the solidified PAS resin adhering to it, so that deterioration of the appearance characteristics (thickness, etc.) can be reduced, or breakage of the test piece can be suppressed.
The material of the sheet body must have a melting point higher than that of the PAS resin, and examples thereof include metal materials (martensitic stainless steel such as SUS404C), fluororesins, polyimides, and ceramics.
Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene/ethylene copolymer (ETFE), tetrafluoroethylene/hexafluoropropylene copolymer polymer (FEP), polyvinylidene fluoride (PVDF) or ethylene-chlorotrifluoroethylene copolymer (ECTFE). In addition, the fluororesin may contain an inorganic filler such as glass fiber, if necessary.
In the test piece preparation process of the present embodiment, when a sheet body is used to prepare a test piece, the sheet body preferably has a melting point higher than that of the PAS resin and preferably has a hydrophobic surface.

<Solidification>
In this embodiment, the method of solidifying the molten PAS resin includes a method of solidifying the molten PAS resin by cooling.
The cooling may be natural cooling or rapid cooling, and rapid cooling is preferred. A known cooling means can be employed as the cooling method. Examples of the cooling means include rolls whose surface temperature can be adjusted (cooling rolls), air knives, immersion in water (a water tank, etc.), and direct or indirect contact with metal materials at 35° C. or lower.
In addition, as described above, the test piece of the present embodiment is preferably made of PAS resin in an amorphous state. As a method for producing such an amorphous PAS resin, it is preferable to solidify the molten PAS resin by rapidly cooling it.
By rapid cooling, it is possible to produce an amorphous PAS resin that does not contain a crystalline phase. Therefore, it becomes easier to uniformly evaluate the PAS resin even by surface measurement, and it becomes an index of reactivity in the molten state. This is preferable from the viewpoint of ease of use.
In the test piece preparation step according to the present embodiment, the PAS resin obtained in the preparation step is melted at 300 ° C. or higher, and then cooled at a rate of 10 ° C./sec or higher. More preferably, the PAS resin is melted at 280° C. or higher and 400° C. or lower and then cooled at a rate of 10° C./second or higher and 100° C./second or lower. Moreover, the cooling rate is preferably maintained in the temperature range from 400° C. to at least the Tg of the PAS resin.
As a result, the PAS resin can be solidified in an amorphous state, the PAS resin can be uniformly evaluated even by surface measurement, and the measurement can easily serve as an index of reactivity in the molten state.
In the present embodiment, it is preferable to cool the molten PAS resin at a cooling rate of 10° C./sec or more and 100° C./sec or less to the Tg or less of the PAS resin, preferably 90° C. or less.
In the test piece preparation process of the present embodiment, the molten PAS resin may be solidified through the sheet body for the purpose of easily obtaining a test piece of a predetermined size. As a more detailed method of solidifying the molten PAS resin, it is preferable to use cooling means to cool the sheet on which the molten PAS resin is placed, thereby solidifying the molten PAS resin and recovering the test piece. Another method for solidifying the molten PAS resin is to solidify the molten PAS resin between the pair of sheet bodies by cooling at least one of a pair of sheet bodies placed so as to sandwich the molten PAS resin. It is preferable to collect the test piece by
As a result, the test piece can be easily collected without the solidified PAS resin adhering to it, so that deterioration of the appearance characteristics (thickness, etc.) can be reduced, or breakage of the test piece can be suppressed.
A suitable test piece preparation step in the present embodiment is to place the PAS resin obtained in the preparation step on a sheet body, and then heat the sheet body using a heating means to melt the PAS resin. After preparing the molten PAS resin, a cooling means is used to cool the sheet on which the molten PAS resin is placed, thereby preparing a test piece in which the molten PAS resin is solidified.

<Test piece>
The test piece in the present embodiment is an example of the object to be measured for zeta potential measurement. ) must be provided. Therefore, in the test piece preparation process of the present embodiment, a test piece having a predetermined shape, size and thickness is prepared as an object to be measured for convenience of zeta potential measurement. It is considered that the test piece in this embodiment is not particularly limited as long as it does not affect the measured value itself for each zeta potential measurement as much as possible. The test piece in this embodiment is a flat plate (film-like) having a thickness of 0.05 to 0.15 cm and a rectangular shape (4.5 to 5.5 cm (length) x 2.5 to 3.5 cm (width)). including.) is preferred.
In this specification, the test piece is 4.5 to 5.5 cm (length) × 2.5 to 3.5 cm (width) × 0.05 to 0.15 cm (thickness) for convenience of zeta potential measurement. ) film-like PAS resin is used. However, it goes without saying that the shape, size, thickness, etc. of the test piece are not particularly limited as long as they do not affect the zeta potential measurement value itself as much as possible.
In other words, the test piece preparation process in this embodiment is a flat plate of 4.5 to 5.5 cm (length) × 2.5 to 3.5 cm (width) × 0.05 to 0.15 cm (thickness) It is preferable that the step is a step of producing a test piece composed of a PAS resin in an amorphous state (including a film shape). In other words, when DSC measurement is performed by heating the test piece of the present embodiment at a temperature range of 40° C. to 350° C. at a rate of 20° C./min, an exothermic peak associated with crystallization is confirmed between 100° C. and 200° C. preferably not.
Since it depends on the size of the measuring device used, the longitudinal length of the test piece in this embodiment is preferably 4.5 to 5.5 cm. Further, the length (=width) of the minor axis of the test piece of this embodiment is preferably 2.5 to 3.5 cm. Furthermore, the thickness of the test piece of this embodiment is preferably 0.05 to 0.15 mm.
In this specification, the "length and width of the test piece" are measured using vernier calipers. On the other hand, the "thickness of the test piece" means that the test piece is cut at 5 points in the longitudinal direction at 8 mm intervals in the direction perpendicular to the longitudinal direction, and 5 test pieces at 5 mm intervals in the width direction on each cut surface. The thickness is measured using a TH-104 film thickness measuring machine (manufactured by Tester Sangyo Co., Ltd.), and refers to the average value of the thickness of a total of 25 points.

Further, in the present embodiment, the surface of the test piece or the surface of the sheet body may be surface-treated for the purpose of suppressing variations in measured values.
The surface treatment method is not particularly limited, and can be appropriately selected from known methods within a range that does not impair the characteristics of the test piece. For example, degreasing with an organic solvent such as acetone in which the PAS resin is insoluble is mentioned.

(Zeta potential measurement step)
The zeta potential measurement step in the present embodiment is a step of measuring the zeta potential on the surface of the test piece obtained by the test piece preparation step by a streaming potential method.
By using the zeta potential value as an index of the surface properties of the PAS resin, it is possible to relatively easily measure the surface properties of the evaluation sample and to easily grasp the properties of the PAS resin. In addition, when the zeta potential value is measured multiple times for the same PAS resin sample, the fluctuation range (variation coefficient) of the zeta potential value due to the measurement is smaller than in the viscosity increase measurement using the conventional MFR.
The zeta potential measurement step in the present embodiment is preferably a step of measuring the zeta potential of the surface of the test piece by streaming potential method under conditions of pH 3 to 9, and under conditions of pH 4.0 to 8.5. More preferably, it is a step of measuring at pH 6.5 to 8.4, and even more preferably under pH 7.8 to 8.2. In another embodiment, the step of measuring by streaming potential method under conditions of pH 4.5 to 6.0 is preferable, and pH 4.8 to 5.2 is more preferable.
By setting the zeta potential measurement conditions within the range of pH 3 to 9, not only is the variation in the measured values further reduced, but the absolute value of the observed zeta potential value itself can be increased. As a result, for example, the amount of difference in zeta potential value increases, so that it becomes easier to detect the difference in zeta potential value between the same or different PAS resins, and it becomes easier to evaluate the properties of the PAS resins with higher accuracy.
In particular, by setting the zeta potential measurement conditions within the range of pH 7.8 to 8.2, it is possible to significantly reduce the variation in the measured values and to significantly increase the absolute value of the observed zeta potential value itself. Therefore, it becomes easy to evaluate the properties of the PAS resin with extremely high accuracy.
In addition, the zeta potential measurement step in the present embodiment may measure the zeta potential of the surface of the test piece under a plurality of mutually different pH ranges by streaming potential method. Furthermore, for example, when it is difficult to adjust pH near pH = 8 (eg, pH 6.5 to 8.4) near the inflection point of the titration curve, near pH = 5 (eg, pH 4.5 to 6.0 ) to measure the zeta potential of the surface of the test piece.

<Zeta potential>
The zeta potential in the present embodiment is preferably measured within a pH range of 3 to 9 using streaming potential method. The measurement of zeta potential by the streaming potential method will be described below with reference to FIG. For convenience of explanation, the case where pH is around 8 in the preferred pH range of 3 to 9 will be described below with reference to FIG. 1 as an example.

FIG. 1 shows, as an example of the measurement of zeta potential by the streaming potential method, the electric potential of the solid-liquid interface between the evaluation sample (=measurement object), which is a flat plate-like (including film-like) test piece 2, and the electrolytic solution 3. It is a schematic diagram which represented the mode of the multilayer typically. For convenience of explanation, FIG. 1 shows an example in which the test piece 2 made of PAS resin is negatively charged.
In the zeta potential measurement by the streaming potential method of the present disclosure, a PAS film, which is a test piece 2, is set on at least one side of the clamp cell 1 shown in FIG. is flowed, the voltage generated by the pressure difference (Δp) is measured, and the zeta potential is measured from the Helmholtz-Smoluchowski formula (formula (II)) described later.

（上記式（Ｉ）及び（ＩＩ）中、Ｉ_ｓｔｒは流動電流を表し、Ｕ_ｓｔｒは流動電位を表し、Δｐは差圧を表し、ηは電解溶液の粘度を表し、εｒ×ε０は電解質溶液の誘電率を表し、ＫＢは電気伝導率を表し、Ｌ／Ａは流路のパラメータを表す。）
からゼータ電位（ζ）が算出される。
以上のことから、本実施形態において、流動電位法によるゼータ電位は、試験片２と電解溶液３との固液界面の電気二重層を形成することにより生じる、試験片２の表面近傍における電解溶液３の層流と試験片２から遠位（試験片２の表面近傍から離間した位置、例えば、クランプセル１中央部）における電解溶液３の層流との層流の差、電解溶液３の粘度、及び電解溶液３の誘電率を計測して、ヘルムホルツ－スモルコフシキの式から算出されうる。 As shown in FIG. 1, when the test piece 2 is negatively charged, positively charged fine particles or ions gather on the surface of the test piece 2 in the electrolytic solution 3 to form a so-called electric double layer. When an electric field is applied between the electrodes 4a and 4b in this state, a flow (laminar flow) toward the negative electrode 4a occurs near the surface of the test piece 2 due to positively charged fine particles or ions. As a result, a flow in the opposite direction (laminar flow) occurs in the central portion of the clamp cell 1 in order to compensate for this flow (laminar flow). In FIG. 1 , arrows indicate the direction of flow of the electrolytic solution 3 . Compressed air or an inert gas may also be used to sweep away the electrolyte solution 3 with a constant pressure difference (ΔP) to create a flow.
Then, using the values of the laminar flow velocity difference (or pressure difference), the viscosity of the electrolytic solution 3, the dielectric constant of the electrolytic solution 3, etc., measured by the above principle, the following Helmholtz-Smoluchowski formula formula:

(In the above formulas (I) and (II), I _str represents the streaming current, U _str represents the streaming potential, Δp represents the differential pressure, η represents the viscosity of the electrolyte solution, and εr × ε0 represents the electrolyte solution. represents the dielectric constant of , KB represents the electrical conductivity, and L/A represents the parameters of the channel.)
The zeta potential (ζ) is calculated from
From the above, in this embodiment, the zeta potential by the streaming potential method is generated by forming an electric double layer at the solid-liquid interface between the test piece 2 and the electrolytic solution 3, and the electrolytic solution near the surface of the test piece 2 3 and the laminar flow of the electrolytic solution 3 at a distance from the test piece 2 (a position away from the surface of the test piece 2, for example, the center of the clamp cell 1), the viscosity of the electrolytic solution 3 , and the dielectric constant of the electrolytic solution 3 can be measured and calculated from the Helmholtz-Smolkowski equation.

<Zeta potential measurement conditions>
In the present embodiment, the electrolytic solution that can be used to measure the zeta potential is preferably an aqueous solution containing a monovalent-monovalent electrolyte, such as an aqueous potassium chloride solution, an aqueous sodium chloride solution, an aqueous lithium chloride solution, an aqueous potassium hydroxide solution, An aqueous sodium hydroxide solution or an aqueous lithium hydroxide solution may be mentioned. An aqueous potassium chloride solution is employed herein.
Further, as the acid or alkali for pH adjustment used in measuring the zeta potential, a general acid or alkali aqueous solution is used, and HCl or KOH is mainly used. The electrolyte concentration in the electrolytic solution is preferably 0.1 to 1000 mmol/L. In this specification, 1 mmol/L is used as an example of the electrolyte concentration in the electrolytic solution.
In this embodiment, when zeta potential measurement is performed under conditions of a specific pH range, a buffer solution may be used as an electrolytic solution that can be used. The buffer solution can be appropriately selected according to the pH conditions to be measured. Further, the buffer solution refers to a weak acid and its salt (conjugate base), or a mixed solution of a weak base and its salt (conjugate acid), which can be combined to adjust the desired pH. For example, when setting the pH to 4 or more and less than 6, acetic acid and sodium acetate, acetic acid and potassium acetate, acetic acid and ammonium acetate, disodium hydrogen phosphate and potassium dihydrogen phosphate, disodium hydrogen phosphate and citric acid, citric acid and Examples include sodium citrate, citric acid and potassium citrate, hydrochloric acid and sodium citrate, or succinic acid and sodium succinate. Moreover, when setting to pH 6 or more and less than 8, a phosphate buffer solution, a MES buffer solution, a Tris buffer solution, or a HEPES buffer solution is mentioned. Furthermore, when setting to pH 8 or more and less than 9, CHES buffer solution, TAPS buffer solution, or Bicine buffer solution is mentioned.
On the other hand, when setting a broad pH range of 2.6 to 12, Britton-Robinson buffer solution can be mentioned.

The pH of the electrolytic solution used in the zeta potential measurement step in the present embodiment is preferably in the range of 3 to 9, and in a preferred example of the present embodiment, an electrolytic solution with a pH of 4.8 to 8.2 is used. ing. Also, the conductivity of the zeta potential electrolyte solution in this embodiment may be in the range of 14-15 mS/m. In addition, the pH and conductivity measurement methods in this specification are measured using a pH and conductivity meter (SurPASS3 (Anton Paar)).
The zeta potential measurement temperature in the present embodiment is preferably around room temperature (22 to 28° C.).

The zeta potential measurement process in this embodiment uses the following conditions as an example.
・ Type of electrolytic solution: KCl aqueous solution ・ Ultrapure water used for electrolytic solution: ASTM I grade (ASTM D 1193-06 (2018) type 1)
・ Concentration of electrolytic solution: 1 mmol / L
・Electrolytic solution conductivity: 14 to 15 mS/m
・Measurement temperature: 20 to 28°C
・pH: 4.8 to 8.2
・Cell type: Clamp cell ・Cell material: PVDF
・Gap between cell and test piece (evaluation sample): adjusted to 100 to 120 μm ・Measurement pressure range: 200 to 450 mbar

"Discrimination process"
In the PAS resin evaluation method according to the present embodiment, it is determined whether the zeta potential value of the surface of the test piece measured by the zeta potential measurement step is in the range of -1 to -80 mV at pH 3 to 9. It is preferable to further have a discrimination step (1).
By providing a determination step (1) for determining whether the zeta potential value of the surface of the test piece measured under the condition of pH 3 to 9 is within the range of -1 to -80 mV, the properties of the PAS resin can be evaluated with higher accuracy.
In the present embodiment, a preferred aspect of the discrimination step (1) is that the zeta potential value measured under conditions of pH 7.8 to 8.2 (eg pH = 8.0) in the zeta potential measurement step is -50 It can be a determination step (2) of determining whether or not it is included in the range of to -65 mV.
As a result, it is possible to evaluate a PAS resin having a zeta potential value of a specific magnitude, so that it is possible to evaluate the reactivity with higher accuracy than the PAS resin quantified by the conventional viscosity increase method such as MFR. It is possible to provide a PAS resin having When the zeta potential of the surface of the test piece is measured at a predetermined pH (for example, pH 3 to 9), if the zeta potential value is large, a reactive functional group (for example, , a functional group containing an oxygen atom or a nitrogen atom) tends to be large, the reactivity of the prepared PAS resin is naturally considered to be high. In particular, when the zeta potential values of test pieces having the same molecular weight of PAS resin as constituent components are compared, it is confirmed that the reactivity of the PAS resin used in the test piece having a large zeta potential value tends to be high.
In another aspect of the present embodiment, instead of the discrimination step (2), or in combination with the discrimination step (2), the zeta potential measurement step pH 4.8 to 5.2 (for example, pH = 5 A determination step (3) of determining whether the zeta potential value of the surface of the test piece measured under the condition of .0) is within the range of -30 to -45 mV. When it is included in the said range, a PAS resin excellent in reactivity can be provided.
In addition, the measurement system of pH 7.8 to 8.2 (eg, pH = 8.0) is the same or Since the zeta potential values and their differences between different PPS resins become larger, it becomes easier to evaluate the properties of the PPS resins with higher accuracy.
As for the relationship between the pH value used in the zeta potential measurement of the surface of the test piece and the zeta potential value, the obtained zeta potential value also fluctuates depending on the pH to be measured. Therefore, in the present disclosure, as an example of a particularly suitable PAS resin evaluation method, the above-described discrimination steps (1) to (3) are only given, and in particular, both discrimination steps (2) and (3) is a discrimination step in which the pH used for measuring the zeta potential value is different. Therefore, the scope of the present disclosure also encompasses other pHs and zeta potential values at those pHs, with zeta potentials in the range of −50 to −65 mV at pH 7.8 to 8.2 (especially pH=8.0). values, or zeta potential values in the range of −30 to −45 mV at pH 4.8 to 5.2 (eg, pH=5.0).

[Preferred form of evaluation method of PAS resin]
The present disclosure comprises a polymerization step of obtaining a PAS resin, a purification step of purifying the PAS resin, and an evaluation step of evaluating a test piece formed from at least a portion of the purified PAS resin obtained through the purification step. wherein the evaluation step includes a test piece preparation step of obtaining the test piece by solidifying the molten PAS resin obtained by melting the PAS resin; , and a zeta potential measurement step of measuring under pH 3 to 9 conditions by streaming potential method.
In the evaluation method of the PAS resin in the present embodiment, a test piece having a specific shape and specific physical properties is used as a standard sample to measure the zeta potential value, so the zeta potential value can be easily measured. However, the measurement accuracy is higher than that of conventional evaluation methods (for example, degree of viscosity increase using MFR or the like).
In addition, the preferred range of the zeta potential value of the surface of the test piece in the present embodiment is -51 to -64 mV at pH 7.8 to 8.2 (eg, pH = 8.0), more preferably -53 to It is -63 mV, more preferably -55 to -62 mV. In the present embodiment, the isoelectric point pH of the test piece containing the PAS resin as a constituent is preferably in the range of 1-6.0, more preferably 2-3.

Although the embodiments of the present disclosure have been described above, the evaluation method of the PAS resin of the present disclosure is not limited to the above examples, and can be modified as appropriate.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the following, unless otherwise specified, "%" or "parts" are based on mass.

(Manufacturing of PPS resin)
[Synthesis Example 1]
22.050 kg (150 mol) of p-dichlorobenzene (p-DCB) and 2 N-methyl-2-pyrrolidone (NMP) were placed in a 150-liter autoclave equipped with a stirring blade and bottom valve connected to a pressure gauge, thermometer, condenser, and decanter. .974 kg (30 mol), 12.362 kg (150 mol) of 68% NaSH and 12.500 kg (150 mol) of 48% NaOH were fed and heated to 173° C. under a nitrogen atmosphere with stirring. After distilling off 12.353 kg of water, the kettle was closed. At that time, the p-DCB distilled azeotropically was separated with a decanter and returned to the kettle as needed. After dehydration, the internal temperature of the autoclave was cooled to 160°C, and 29.486 kg (297 mol) of NMP was supplied, then 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. did. The final pressure was 0.28 MPa. After the reaction, the bottom valve of the autoclave is opened, NMP is extracted into a 150-liter vacuum stirring dryer with a stirring blade while the pressure is reduced, and then the NMP is sufficiently removed by stirring at 150 ° C. for 2 hours under reduced pressure, and the powder is obtained. A mixture (A-1) of the PPS resin and salts was obtained. A process of adding 1000 g of ion-exchanged water at 70° C. to 417 g of the mixture (A-1), stirring for 20 minutes and filtering was repeated twice. The resulting hydrous cake and 600 g of ion-exchanged water were supplied to a 1-liter autoclave equipped with a stirrer and stirred at 160° C. for 30 minutes. After cooling to room temperature, 800 g of ion-exchanged water at 70° C. was further added to the water-containing cake obtained by filtration, followed by filtration. The resulting water-containing cake and 600 g of ion-exchanged water were placed in a 1-liter autoclave equipped with a stirrer, stirred at 220°C for 30 minutes, cooled to room temperature, filtered, and 600 g of ion-exchanged water at 70°C was added to the obtained water-containing cake. was added and filtered. After that, 600 g of carbonated water having a pH of 4 at 20° C. was added and filtered, and further 600 g of ion-exchanged water at 70° C. was added and filtered. The resulting water-containing cake was dried in a hot air circulation dryer at 120° C. for 6 hours to obtain a white powdery PPS resin. Table 1 shows the results of measuring the degree of viscosity increase and the zeta potential of the PPS resin obtained in Synthesis Example 1 three times each.

[Synthesis Example 2]
19.413 kg of flaky sodium sulfide (60.3% by weight Na ₂ S) and 45.0 kg of NMP were fed into a 150-liter autoclave equipped with a stirring blade and bottom valve connected to a pressure gauge, a thermometer, and a condenser. The temperature was raised to 209° C. while stirring under a nitrogen stream, and 4.644 kg of water was distilled off (the remaining water content was 1.13 mol per 1 mol of sodium sulfide). The autoclave was then closed and cooled to 180° C. and further cooled while feeding 22.185 kg of p-DCB and 18.0 kg of NMP. At a liquid temperature of 150° C., the inside of the autoclave was pressurized to a gauge pressure of 0.1 MPa by nitrogen gas, and heating was started again. The liquid temperature was raised from 200° C. to 250° C. over 3 hours and held at 250° C. for 1 hour for reaction, then 0.635 kg of water was pressurized and cooled to 220° C. over 40 minutes. Thereafter, cooling was further continued, and 0.284 kg (2.25 mol) of oxalic acid dihydrate and 0.663 kg of NMP were injected under pressure at 200°C. Further cooling was continued, and at 100°C, the bottom valve was opened and the reaction slurry was transferred to a 150-liter flat plate filter and pressure filtered at 120°C. Subsequently, 16 kg of NMP was added and filtered under pressure. After filtration, the mixture was stirred under reduced pressure at 150° C. for 2 hours using a 150-liter vacuum dryer equipped with a stirring blade to remove NMP, thereby obtaining a powdery PPS resin-salt mixture (B-1). To 417 g of the mixture (B-1) was added 1000 g of ion-exchanged water at 70° C., stirred for 20 minutes and then filtered. After repeating this operation once more, the resulting water-containing cake and 600 g of ion-exchanged water were supplied to a 1-liter autoclave equipped with a stirrer and stirred at 160° C. for 30 minutes. After cooling to room temperature, 600 g of ion-exchanged water at 70° C. was added to the resulting water-containing cake, followed by filtration. The resulting water-containing cake was dried in a hot air circulation dryer at 120° C. for 6 hours to obtain a white powdery PPS resin. Table 1 shows the results of three measurements of the degree of viscosity increase and the zeta potential of the PPS resin obtained in Synthesis Example 2.

(Evaluation method of PPS resin)
(1) Measurement of Viscosity Increase of PPS Resin The viscosity increase of the PPS resins obtained in Synthesis Examples 1 and 2 when epoxysilane was added was measured by the following method.
The degree of increase in melt viscosity during melt kneading with the addition of γ-glycidoxypropyltrimethoxysilane of 1.0% (mass ratio of solid content to PPS resin) was evaluated. Here, the melt-kneading was performed at 320° C. and 100 rpm for 5 minutes using Labo Plastomill (20-200C, using R-60 type mixer, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The degree of increase in melt viscosity during melt-kneading with the addition of epoxysilane is expressed by the following equation.
Degree of viscosity increase (magnification) = (MFR after addition of epoxysilane)/(MFR when no addition of epoxysilane)

(2) Measurement of zeta potential (ζ potential) of PPS resin (2-1) Method for preparing test piece used for zeta potential measurement The PPS resin was sandwiched between two Teflon sheets containing glass fibers (Nitoflon manufactured by Nitto Denko Corporation) and heated for 1 minute using a hot plate preheated to 350°C. At this time, the PPS resin melted, so that it was pressed from above with a metal plate heated to 350° C. to form a film with a thickness of 0.1 cm.
After further heating the film-like PPS resin for 1 minute, the two Teflon sheets sandwiching the film-like molten PPS resin were transferred from the hot plate onto a metal plate at room temperature (28°C), and immediately heated to room temperature from above. (28° C.) and cooled to room temperature (28° C.) to solidify the molten PPS resin. Thereafter, the solidified film-like PPS resin was cut into pieces of 5 cm×3 cm to prepare amorphous test pieces each containing at least a part of the PPS resin produced in Synthesis Example as a constituent component.
(2-2) Zeta potential measurement method After degreasing the surface of each amorphous test piece containing the PPS resin obtained above with acetone, SurPASS3 (Anton Paar), a zeta potential meter exclusively for solids Co.), the zeta potential value of the surface of each test piece in the amorphous state was measured three times by the streaming potential method under the following measurement conditions.
"Measurement condition"
・Electrolyte solution: 1 mmol/L KCl aqueous solution ・Measurement temperature: 22 to 26°C
- pH: 8.0 or 5.0

(3) DSC measurement 4 mg was taken from a film-shaped PPS resin test piece prepared for zeta potential measurement, and measured from 40 ° C. to 350 ° C. at 20 ° C./min with a differential scanning calorimeter (DSC), PerkinElmer's DSC8500. The temperature was raised at . Since no exothermic peak due to crystallization of the resin was observed between 100° C. and 200° C., it was confirmed that each film-like test piece was in an amorphous state.

In Table 1 above, when Examples 1 to 4 and Comparative Examples 1 and 2 are compared, the CV value (%), which is the coefficient of variation, is reduced by about 10 times, and it is also an index of measurement accuracy. Corresponding amount of change in the difference between the average values of Synthesis Example 1 and Synthesis Example 2 [%] (= [average value of Synthesis Example 2 - average value of Synthesis Example 1] / [average value of Synthesis Example 2] × 100) However, it has improved by a maximum of 5.1%. Therefore, it was confirmed that the evaluation method of the present embodiment can evaluate a reactive PPS resin with less variation than the conventional evaluation method using the degree of viscosity increase with high accuracy. In addition, when comparing Examples 1 and 2 with Examples 3 and 4, setting the pH to around 8 not only reduces the variation, but also reduces the zeta potential values between the same or different PPS resins. and the difference between them becomes larger, it was confirmed that the properties of the PPS resin can be easily evaluated with higher accuracy.

According to the present disclosure, since the surface properties of the PAS resin can be quantified, it is possible to provide a method for evaluating the reactivity of the PAS resin with less variation and with higher accuracy than the conventional evaluation method using viscosity. can.

1 clamp cell 2 test piece 3 electrolytic solution 4a negative electrode 4b positive electrode

Claims (6)

A preparatory step of preparing a polyarylene sulfide resin;
A method for evaluating a polyarylene sulfide resin, comprising: an evaluation step of evaluating a test piece formed from at least a portion of the polyarylene sulfide resin,
The evaluation step includes a test piece preparation step of obtaining the test piece by solidifying the molten polyarylene sulfide resin obtained by melting the polyarylene sulfide resin;
and a zeta potential measurement step of measuring the zeta potential of the surface of the test piece by a streaming potential method. 2. The method for evaluating a polyarylene sulfide resin according to claim 1, wherein the zeta potential measurement step measures the zeta potential of the surface of the test piece under pH 3-9 conditions. The evaluation step determines whether the zeta potential value of the surface of the test piece measured by the zeta potential measurement step is within the range of -50 to -65 mV at pH 7.8 to 8.2. 3. The method for evaluating a polyarylene sulfide resin according to claim 1, further comprising a determination step (2). When the temperature range of the test piece is increased from 40 ° C. to 350 ° C. at a rate of 20 ° C./min and subjected to DSC measurement, an exothermic peak associated with crystallization is not confirmed between 100 ° C. and 200 ° C. , The method for evaluating the polyarylene sulfide resin according to any one of claims 1 to 3. 5. The method for evaluating a polyarylene sulfide resin according to claim 1, wherein said preparing step prepares said polyarylene sulfide resin by a polymerization step for obtaining said polyarylene sulfide resin. a polymerization step of obtaining a polyarylene sulfide resin;
A purification step of purifying the polyarylene sulfide resin;
and an evaluation step of evaluating a test piece formed from at least a portion of the purified polyarylene sulfide resin obtained through the purification step.
The evaluation step includes a test piece preparation step of obtaining the test piece by solidifying the molten polyarylene sulfide resin obtained by melting the polyarylene sulfide resin;
and a zeta potential measurement step of measuring the zeta potential of the surface of the test piece under conditions of pH 3 to 9 by streaming potential method.

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