Polyphenylene ether resin composition, and pellets and molded article using same

Abstract

A polyphenylene ether resin composition according to one embodiment of the present invention contains a polyphenylene ether resin (A), a styrene resin (B) having a syndiotactic structure, and an inorganic filler (C). The mass ratio of the polyphenylene ether resin (A) contained in the polyphenylene ether resin composition is 15-40 mass parts per 100 total mass parts of the polyphenylene ether resin (A) and styrene resin (B) having a syndiotactic structure. The polyphenylene ether resin composition has a cold crystallization temperature of 150°C or higher as determined by differential scanning calorimetry.

Description

Polyphenylene ether-based resin composition, pellets and molded articles using the same.

[0001] This invention relates to a polyphenylene ether-based resin composition, pellets and molded articles using the same.

[0002] Polyphenylene ether resins are excellent in various properties such as heat resistance, flame retardancy, and electrical properties, and also possess excellent properties such as low specific gravity and hydrolysis resistance. Furthermore, the moldability of polyphenylene ether resins can be improved by compounding them with styrene resins.

[0003] Resin compositions containing such polyphenylene ether resins and styrene resins are widely used as materials for various applications such as electrical and electronic equipment materials, automotive and electronic components, home appliances, various machine parts, and industrial materials, due to their characteristics.

[0004] For example, as resin compositions containing polyphenylene ether resins and styrene resins, Patent Documents 1 to 3 disclose styrene resin compositions containing polyphenylene ether or modified polyphenylene ether and a styrene resin having a syndiotactic structure.

[0005] International Publication No. 2022 / 158374 JP 02-064140 JP 03-126743

[0006] However, because polyphenylene ether resins are amorphous resins, they have low chemical resistance. Therefore, resin compositions containing polyphenylene ether resins (i.e., polyphenylene ether resin compositions) have the problem that their physical properties are easily degraded by chemicals.

[0007] Furthermore, in order to improve the chemical resistance of the above-mentioned polyphenylene ether resin, conventional methods have involved blending it with polyamide resins, polypropylene resins, etc., thereby improving the chemical resistance of the polyphenylene ether resin. However, this method has the problem of poor dimensional stability of the polyphenylene ether resin composition under temperature changes.

[0008] Therefore, in various fields where polyphenylene ether-based resin compositions are used as materials, there has been a demand for polyphenylene ether-based resin compositions that achieve both improved chemical resistance and dimensional stability under temperature changes.

[0009] This invention has been made in view of the above circumstances, and aims to provide a polyphenylene ether-based resin composition that has excellent chemical resistance and high dimensional stability under temperature changes, as well as pellets and molded articles using the same.

[0010] To solve the above-mentioned problems and achieve the objective, the polyphenylene ether-based resin composition, pellets and molded articles using the same according to the present invention have any of the following configurations.

[0011] In other words, the polyphenylene ether resin composition according to the present invention is a polyphenylene ether resin composition comprising [1] a polyphenylene ether resin (A), a styrene resin having a syndiotactic structure (B), and an inorganic filler (C), wherein the mass ratio of the polyphenylene ether resin (A) is 15 to 40 parts by mass with respect to 100 parts by mass of the total of the polyphenylene ether resin (A) and the styrene resin having a syndiotactic structure (B), and the temperature of crystallization by differential scanning calorimetry is 150°C or higher.

[0012] Furthermore, the polyphenylene ether resin composition according to the present invention is characterized in that, in the invention described in [1] above, when the linear thermal expansion coefficient of the polyphenylene ether resin composition at the time of molding is defined as the MD value, and the linear thermal expansion coefficient in the direction perpendicular to the flow direction is defined as the TD value, the ratio of the TD value to the MD value (TD / MD), which indicates the anisotropy of the linear thermal expansion coefficient of the polyphenylene ether resin composition, is 3.0 or less.

[0013] Furthermore, the polyphenylene ether resin composition according to the present invention is characterized in that, in the invention described in [1] or [2] above, the mass ratio of the polyphenylene ether resin (A) is 20 to 40 parts by mass with respect to a total of 100 parts by mass of the polyphenylene ether resin (A) and the styrene resin (B) having a syndiotactic structure.

[0014] Furthermore, the pellets according to the present invention are characterized in that [4] they contain the polyphenylene ether resin composition described in any one of [1] to [3] above.

[0015] Furthermore, the molded article according to the present invention is characterized in that [5] it contains the polyphenylene ether resin composition described in any one of [1] to [3] above.

[0016] The present invention provides a polyphenylene ether-based resin composition that exhibits excellent chemical resistance and high dimensional stability under temperature changes, as well as pellets and molded articles using the same.

[0017] The following describes in detail preferred embodiments of the polyphenylene ether-based resin composition, pellets, and molded articles using the same according to the present invention. However, the present invention is not limited to the embodiments described below. Furthermore, in this specification, unless otherwise specified, the notation "~" is used to mean that the numerical values ​​before and after it include the lower and upper limits, respectively.

[0018] [Polyphenylene ether resin composition] The polyphenylene ether resin composition according to an embodiment of the present invention (hereinafter referred to as PPE resin composition (Z)) is a resin composition containing a polyphenylene ether resin (A), a styrene resin having a syndiotactic structure (B), and an inorganic filler (C). In the PPE resin composition (Z), the mass ratio of the polyphenylene ether resin (A) is 15 to 40 parts by mass with respect to 100 parts by mass of the total of the polyphenylene ether resin (A) and the styrene resin having a syndiotactic structure (B). Furthermore, the temperature at which the PPE resin composition (Z) crystallizes by differential scanning calorimetry is 150°C or higher.

[0019] Hereinafter, each component constituting the PPE-based resin composition (Z), and pellets, molded articles and the like using the PPE-based resin composition (Z) will be described in detail.

[0020] [Polyphenylene ether-based resin (A)] First, the polyphenylene ether-based resin (A), which is one component constituting the PPE-based resin composition (Z) according to the embodiment of the present invention, will be described in detail. The polyphenylene ether-based resin (A) is a resin containing polyphenylene ether resin or an acid-modified product thereof, or both of them. For example, the polyphenylene ether resin contained in the polyphenylene ether-based resin (A) (hereinafter referred to as polyphenylene ether resin (Aa)) is preferably a resin represented by the following general formula (1). Note that the resin represented by general formula (1) does not particularly define the type or the like of the polyphenylene ether resin (Aa). That is, the polyphenylene ether-based resin (A) is not limited by the resin represented by general formula (1) (polyphenylene ether resin (Aa)).

[0021]

[0022] In general formula (1), R 11 to R 15 and R 21 to R 24 are each independently a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 4 carbon atoms. R 25 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n is the number of repeating constitutional units, and is an integer of 10 or greater. The term "alkyl group having 1 to 4 carbon atoms" means an alkyl group containing 1 to 4 carbon atoms.

[0023] Further, in general formula (1), R 11 to R 15 and R 21 to R 25The alkyl group having 1 to 4 carbon atoms in each of the above may be either a linear or branched alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Among these, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group is preferred, and a methyl group is more preferred.

[0024] Further, in general formula (1), R 11 , R 13 , R 21 and R 23 each are preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. R 12 , R 14 , R 22 and R 24 each are preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a methyl group. R 25 is preferably a hydrogen atom.

[0025] Further, in general formula (1), n is 10 or more as described above, and is more preferably an integer of 20 or more. The upper limit of n is not particularly limited, but is preferably 300 or less.

[0026] As the polyphenylene ether resin (Aa) contained in the polyphenylene ether-based resin (A), poly(2,6-dimethyl-1,4-phenylene ether) and a 2,6-dimethylphenol / 2,3,6-trimethylphenol random copolymer are preferred. In particular, a resin represented by the following chemical formula (2), that is, poly(2,6-dimethyl-1,4-phenylene ether) is preferred. In chemical formula (2), n is the same integer as in general formula (1) described above. Further, as the polyphenylene ether resin (Aa), a polyphenylene ether resin that defines the number of terminal groups and the copper content as described in Japanese Patent Application Laid-Open No. 2005-344065 can also be suitably used.

[0027]

[0028] From the viewpoint of improving molding processability, the intrinsic viscosity of the polyphenylene ether resin (A), which is measured at a temperature of 30°C using chloroform as a solvent, is preferably 0.20 to 0.60 dL / g, more preferably 0.30 to 0.50 dL / g, and still more preferably 0.35 to 0.45 dL / g.

[0029] Furthermore, as the polyphenylene ether resin (A), commercially available products such as PX100F or PX100L, which are poly(2,6-dimethyl-1,4-phenylene ether) manufactured by Polyxylenol Singapore, can be used, for example. The glass transition temperatures of PX100F and PX100L are 207°C and 210°C, respectively. The intrinsic viscosities of PX100F and PX100L, which are measured at a temperature of 30°C using chloroform as a solvent, are 0.37 dL / g and 0.47 dL / g, respectively.

[0030] The method for producing the polyphenylene ether resin (Aa) used in the present embodiment is not particularly limited, and may follow a known method. For example, a method of oxidative polymerization of a monomer such as 2,6-dimethylphenol in the presence of an amine copper catalyst can be employed. In this case, the intrinsic viscosity can be controlled to a desired range by selecting reaction conditions. Control of the intrinsic viscosity can be achieved by selecting conditions such as polymerization temperature, polymerization time, and catalyst amount. The polyphenylene ether resin (Aa) produced by these methods is usually in powder form.

[0031] The polyphenylene ether resin (A) may contain an acid-modified polyphenylene ether resin, i.e., a modified polyphenylene ether resin (hereinafter referred to as modified polyphenylene ether resin (Ab)). Examples of the modified polyphenylene ether resin (Ab) include fumaric acid-modified polyphenylene ether, maleic anhydride-modified polyphenylene ether, (styrene-maleic anhydride)-polyphenylene ether-graft polymer, glycidyl methacrylate-modified polyphenylene ether, amine-modified polyphenylene ether, and the like. When the polyphenylene ether resin (A) contains a modified polyphenylene ether resin (Ab), the modified polyphenylene ether resin (Ab) may act in the same manner as the acid-modified resin described later.

[0032] As the modified polyphenylene ether resin (Ab), an acid-modified product of the resin represented by general formula (1) is preferred. Examples of such acid-modified products include resins obtained by modifying the resin represented by general formula (1) with a carboxylic acid or a carboxylic acid derivative. As the carboxylic acid or carboxylic acid derivative, an unsaturated carboxylic acid and its derivatives are preferred from the viewpoint of reactivity with the resin represented by general formula (1).

[0033] For example, unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, and angelic acid. Derivatives of unsaturated carboxylic acids include acid anhydrides, esters, amides, imides, and metal salts. Specific examples include maleic anhydride, maleic acid esters, fumaric acid esters, maleimide and its N-substituted derivatives, maleate salts, fumarate salts, acrylic acid, acrylic acid esters, acrylamide, acrylicate salts, methacrylic acid, methacrylic acid esters, methacrylamide, methacrylate salts, and glycidyl methacrylate. Among these, maleic anhydride and glycidyl methacrylate are preferred as derivatives, with maleic anhydride being particularly preferred. As an acid-modified product of the resin represented by general formula (1), from the viewpoint of availability, a resin obtained by modifying the resin represented by general formula (1) with maleic anhydride or fumaric acid is preferred. In other words, a maleic acid modified product of the resin represented by general formula (1), or a fumaric acid modified product of the resin represented by general formula (1), is preferred. Note that one of the above-mentioned modifying agents may be used alone, or two or more may be used in combination.

[0034] Examples of acid-modified resins of the resin represented by general formula (1) include resins having the structure represented by the following general formula (3) and resins having the structure represented by the following general formula (4).

[0035]

[0036]

[0037] In general formula (3), R 11 ~R 15 , R 21 , R 23 , R 24 , R 25 And n are independently equivalent to those in the general formula (1) above. Also, in general formula (4), R 11 ~R 15 , R 21 , R 23 , R 24And n are, independently, equivalent to those in the general formula (1) described above.

[0038] The amount of modification of the modified polyphenylene ether resin (Ab) is the amount of modifier of the polyphenylene ether resin (Aa) contained in the polyphenylene ether resin (A), and is expressed as the mass ratio of the polyphenylene ether resin (Aa) in the polyphenylene ether resin (A) to 100% by mass. For example, the lower limit of the amount of modification of the modified polyphenylene ether resin (Ab) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and particularly preferably 0.2% by mass or more. The upper limit of the amount of modification of the modified polyphenylene ether resin (Ab) is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5.0% by mass or less. When the amount of modification of the modified polyphenylene ether resin (Ab) is within the above range, a PPE-based resin composition (Z) and a molded article thereof having good mechanical strength and heat resistance can be obtained. The degree of modification of such modified polyphenylene ether resin (Ab) can be determined by the neutralization titration volume measured in accordance with JIS K0070-1992.

[0039] Modified polyphenylene ether resin (Ab) is obtained by reacting the above-mentioned polyphenylene ether resin (Aa) with a modifying agent. There are no particular restrictions on the method for modifying the polyphenylene ether resin (Aa), and known methods can be used.

[0040] For example, preferred methods for modifying polyphenylene ether resin (Aa) include melt modification and solution modification. Among these, melt modification is more preferred because it yields a higher degree of modification and has high productivity. That is, the modified polyphenylene ether resin (Ab) is preferably a modified polyphenylene ether resin produced by melt modification or a modified polyphenylene ether resin produced by solution modification, and more preferably a modified polyphenylene ether resin produced by melt modification.

[0041] Melt modification is a method for obtaining a modified polyphenylene ether resin by melt-kneading a polyphenylene ether resin and a modifying agent in the presence or absence of a radical generator. Specifically, melt modification is a method in which the polyphenylene ether resin and the modifying agent are melt-kneaded at a temperature in the range of 150 to 350°C using a roll mill, Banbury mixer, extruder, etc., thereby causing the polyphenylene ether resin and the modifying agent to react.

[0042] More specifically, a preferred method involves uniformly dry-blending a polyphenylene ether resin, a modifier, and an optional radical generator at room temperature, followed by carrying out the melt reaction at a temperature in the range of 260 to 350°C, which is substantially the kneading temperature of the polyphenylene ether resin. If the kneading temperature is 260°C or higher, the melt viscosity of the polyphenylene ether resin can be adequately maintained. Furthermore, if the kneading temperature is 350°C or lower, the decomposition of the polyphenylene ether resin can be suppressed.

[0043] The lower limit of the amount of modifying agent used in the above melt modification is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the polyphenylene ether resin to be modified. The upper limit of the amount of modifying agent used in the above melt modification is preferably 22 parts by mass or less, more preferably 17 parts by mass or less, even more preferably 12 parts by mass or less, and particularly preferably 7.0 parts by mass or less, per 100 parts by mass of the polyphenylene ether resin to be modified. When the amount of modifying agent used is within the above range, a PPE-based resin composition (Z) and a molded article thereof having good mechanical strength and heat resistance can be obtained.

[0044] As the radical generating agent used in the above-mentioned melting modification, it is preferable that the temperature at which it exhibits a half-life of 1 minute is 300°C or higher. Specific examples of such radical generating agents include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylhexane, and 2,3-dimethyl-2,3-di(p-methylphenyl)butane. Among these, 2,3-dimethyl-2,3-diphenylbutane, which exhibits a half-life of 1 minute at 330°C, is preferably used.

[0045] The lower limit of the radical generating agent used in the above melt modification is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of the polyphenylene ether resin to be modified. The upper limit of the radical generating agent used in the above melt modification is preferably 3 parts by mass or less, and more preferably 2 parts by mass or less, per 100 parts by mass of the polyphenylene ether resin to be modified. If the radical generating agent is used at a rate of 0.1 parts by mass or more, a high modification effect on the polyphenylene ether resin can be obtained. Furthermore, if the radical generating agent is used at a rate of 3 parts by mass or less, the polyphenylene ether resin can be modified efficiently, and insoluble components are less likely to be generated.

[0046] When the polyphenylene ether resin (A) contains a modified polyphenylene ether resin (Ab), the content ratio of the modified polyphenylene ether resin (Ab) may be set by focusing on the mass ratio to 100% by mass of the total of the polyphenylene ether resin (Aa) and the modified polyphenylene ether resin (Ab) in the polyphenylene ether resin (A). In this case, the lower limit of the content ratio of the modified polyphenylene ether resin (Ab) is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and particularly preferably 10% by mass or more. Furthermore, the upper limit of the content ratio of the modified polyphenylene ether resin (Ab) is preferably 95% by mass or less, more preferably 80% by mass or less, even more preferably 65% ​​by mass or less, even more preferably 50% by mass or less, and particularly preferably 35% by mass or less. When the content ratio of modified polyphenylene ether resin (Ab) in polyphenylene ether resin (A) is within the above range, a PPE-based resin composition (Z) and a molded article thereof can be obtained that have good mechanical strength and heat resistance.

[0047] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and styrene resin (B) having a syndiotactic structure, the lower limit of the content of modified polyphenylene ether resin (Ab) in the PPE resin composition (Z) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and particularly preferably 1.0% by mass or more, when the total PPE resin composition (Z) is considered as 100% by mass. Furthermore, the upper limit of the content of the modified polyphenylene ether resin (Ab) is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 27% by mass or less, and particularly preferably 25% by mass or less.

[0048] As described above, the polyphenylene ether resin (A) is a resin with excellent heat resistance, and therefore can improve the load deflection temperature and dimensional stability under temperature changes of the PPE resin composition (Z) containing it. Dimensional stability under temperature changes refers to the physical property of the PPE resin composition (Z) exhibiting dimensional stability (resistance to dimensional change) with respect to temperature changes after molding. On the other hand, since the polyphenylene ether resin (A) is an amorphous resin, it has low chemical resistance. Therefore, if the polyphenylene ether resin (A) is included in excess in the PPE resin composition (Z), the chemical resistance of the PPE resin composition (Z) tends to decrease.

[0049] Therefore, the polyphenylene ether resin (A) is included in the PPE resin composition (Z) to suppress a decrease in the chemical resistance of the PPE resin composition (Z) and to improve the load deflection temperature and dimensional stability during temperature changes. More specifically, the polyphenylene ether resin (A) is included in the PPE resin composition (Z) together with the styrene resin (B) having a syndiotactic structure described later, and the mass ratio of the polyphenylene ether resin (A) is 15 to 40 parts by mass per 100 parts by mass of the total of the polyphenylene ether resin (A) and the styrene resin (B) having a syndiotactic structure. The lower limit of the mass ratio of the polyphenylene ether resin (A) is more preferably 18 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 25 parts by mass or more. Furthermore, the upper limit of the mass percentage of the polyphenylene ether resin (A) is more preferably 39 parts by mass or less, even more preferably 37 parts by mass or less, and particularly preferably 35 parts by mass or less.

[0050] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and styrene resin (B) having a syndiotactic structure, the lower limit of the content of polyphenylene ether resin (A) in the PPE resin composition (Z) is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more, when the total PPE resin composition (Z) is considered to be 100% by mass. Furthermore, the upper limit of the content of polyphenylene ether resin (A) is preferably 35% by mass or less, more preferably 33% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

[0051] The chemical resistance of the PPE resin composition (Z) is expressed by the retention rate of the flexural strength of a molded body of the PPE resin composition (Z) before and after immersion in a chemical. The flexural strength of the molded body is measured in accordance with ISO-178. Furthermore, the temperature of deflection under load (DTUL) is a physical property that represents the heat resistance of the PPE resin composition (Z) and is measured in accordance with ISO-75-2. Details regarding dimensional stability under temperature changes will be described later.

[0052] Furthermore, the lower limit of the glass transition temperature of the polyphenylene ether resin (A) is preferably 195°C or higher, and more preferably 200°C or higher. Furthermore, the upper limit of the glass transition temperature of the polyphenylene ether resin (A) is preferably 220°C or lower, and more preferably 215°C or lower. By setting the glass transition temperature of the polyphenylene ether resin (A) to be above the above lower limit, molded articles obtained from the PPE resin composition (Z) containing the polyphenylene ether resin (A) tend to maintain higher mechanical strength at high temperatures. Furthermore, by setting the glass transition temperature of the polyphenylene ether resin (A) to be below the above upper limit, the fluidity of the PPE resin composition (Z) during processing is improved, and thus the processability of the PPE resin composition (Z) tends to improve.

[0053] The mechanical strength of the PPE resin composition (Z) is expressed by its tensile strength. The tensile strength of the PPE resin composition (Z) is measured in accordance with ISO-527. Furthermore, the processability (flowability) of the PPE resin composition (Z) is expressed by its melt volume flow rate (hereinafter sometimes abbreviated as MVR). The MVR is measured in accordance with ISO-1133.

[0054] The polyphenylene ether resin (A) may be a single polyphenylene ether resin or a mixture of two or more polyphenylene ether resins. When the PPE resin composition (Z) contains two or more polyphenylene ether resins (A), the glass transition temperature of the polyphenylene ether resins (A) described above shall be the weighted average value.

[0055] Furthermore, the polyphenylene ether resin (A) used in the PPE resin composition (Z) may be recycled (including recovered products, material recycled products, chemical recycled products, etc.), or it may be a rejected product or scrap material from the molding of polyphenylene ether resin.

[0056] [Styrene-based resin having a syndiotactic structure (B)] Next, a styrene-based resin having a syndiotactic structure (B) according to an embodiment of the present invention will be described in detail. Hereinafter, "styrene-based resin having a syndiotactic structure (B)" may be abbreviated as "SPS-based resin (B)". SPS-based resin (B) is exemplified by SPS (Syndiotactic Polystyrene) and is included in the PPE-based resin composition (Z) as one of the resin components constituting the PPE-based resin composition (Z).

[0057] In this specification, "syndiotactic structure" refers to a structure in which the phenyl rings of adjacent styrene units are arranged alternately with respect to the plane formed by the main chain of the polymer block at a high rate. Hereinafter, in the syndiotactic structure of SPS resin (B), the arrangement of the phenyl rings of adjacent styrene units alternately with respect to the plane formed by the main chain of the polymer block, as described above, may be referred to as "syndiotacticity."

[0058] Generally, the stereoregularity (tacticity) of resin structures is determined by nuclear magnetic resonance spectroscopy using isotopic carbon. 13 It can be quantitatively identified by 13C-NMR. That is, the proportion of multiple consecutive constituent units in the syndiotactic structure of SPS resin (B) is 13 It can be quantified by C-NMR. For example, in the syndiotactic structure of SPS resin (B), two consecutive monomer units can be quantified as a dyad, three monomer units as a triad, and five monomer units as a pentad.

[0059] In the present invention, "styrene-based resin having a syndiotactic structure" means a styrene-based polymer having a predetermined syndiotacticity, a hydrogenated polymer or mixture of said styrene-based polymer, or a copolymer mainly composed of these. The syndiotacticity of the styrene-based polymer is preferably 75 mol% or more in the racemic diad (r), and more preferably 85 mol% or more. Alternatively, the syndiotacticity of the styrene-based polymer is preferably 30 mol% or more in the racemic pentad (rrrr), and more preferably 50 mol% or more. Examples of said styrene-based polymers include polystyrene, poly(hydrocarbon-substituted styrene), poly(halogenated styrene), poly(halogenated alkyl styrene), poly(alkoxy styrene), and poly(vinyl benzoate ester).

[0060] For example, poly(hydrocarbon-substituted styrene) includes poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), and poly(vinylstyrene). Poly(halogenated styrene) includes poly(chlorostyrene), poly(bromostyrene), and poly(fluorostyrene). Poly(halogenated alkylstyrene) includes poly(chloromethylstyrene). Poly(alkoxystyrene) includes poly(methoxystyrene) and poly(ethoxystyrene).

[0061] Examples of comonomer components in copolymers containing the above-mentioned structural units in the syndiotactic structure of SPS resin (B) include, in addition to the monomers of the styrene polymer, olefin monomers, diene monomers, polar vinyl monomers, etc. Examples of olefin monomers include ethylene, propylene, butene, hexene, and octene. Examples of diene monomers include butadiene and isoprene. Examples of polar vinyl monomers include cyclic olefin monomers, cyclic diene monomers, methyl methacrylate, maleic anhydride, and acrylonitrile.

[0062] Suitable copolymers for use as SPS resin (B) include, for example, copolymers of styrene and p-methylstyrene, copolymers of styrene and p-tert-butylstyrene, and copolymers of styrene and divinylbenzene. Among these, copolymers of styrene and p-methylstyrene are preferred.

[0063] Furthermore, as the SPS resin (B), one or more selected from the group consisting of polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and copolymers of styrene and p-methylstyrene are preferred. Among these, one or more selected from the group consisting of polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), and copolymers of styrene and p-methylstyrene are more preferred, and polystyrene or copolymers of styrene and p-methylstyrene are even more preferred.

[0064] The lower limit of the weight-average molecular weight of the SPS resin (B) is 1 × 10⁻⁶, from the viewpoint of resin fluidity during molding and the strength of the resulting molded article. 4 Preferably, it is 5 x 10 4 It is more preferable that the above conditions are met. Furthermore, the upper limit of the weight-average molecular weight of the SPS resin (B) is 1 × 10⁻⁶. 6 The following is preferable: 5 × 10 5 The following is more preferable: The weight-average molecular weight of the SPS resin (B) is 1 × 10 4 If the above conditions are met, a molded article with sufficient strength can be obtained from the PPE resin composition (Z) containing the SPS resin (B), etc. 6 If the following conditions are met, there will be no problem with the fluidity of the PPE resin composition (Z) containing the SPS resin (B), etc., during molding.

[0065] In this specification, unless otherwise specified, the weight-average molecular weight of SPS resin (B) is determined by gel permeation chromatography at 145°C using a Tosoh Corporation GPC instrument (HLC-8321GPC / HT) and a Tosoh Corporation GPC column (GMHHR-H(S)HTC / HT) with 1,2,4-trichlorobenzene as the eluent, and converted using a calibration curve for standard polystyrene.

[0066] The SPS-based resin (B) described above is a crystalline resin. Because chemicals do not easily penetrate the crystalline parts of a crystalline resin, crystalline resins tend to have high chemical resistance. For this reason, the chemical resistance of a PPE-based resin composition (Z) containing SPS-based resin (B) generally tended to increase with increasing amounts (content) of SPS-based resin (B). However, as a result of our diligent research, we unexpectedly found that when SPS-based resin (B) is included in the PPE-based resin composition (Z) at a specific mass ratio relative to the resin components, the chemical resistance is higher than when SPS-based resin (B) is included alone (100 parts by mass) as the resin component.

[0067] By mixing (alloying) an SPS-based resin (B) with a polyphenylene ether-based resin (A), the processability (fluidity) of a PPE-based resin composition (Z) containing this mixture can be improved. The fluidity of this PPE-based resin composition (Z) tends to improve as the amount (content) of the styrene-based resin (B) having the syndiotactic structure increases.

[0068] On the other hand, the SPS resin (B) is compatible with the polyphenylene ether resin (A), thereby lowering the glass transition temperature of the PPE resin composition (Z) containing this mixture. This glass transition temperature decreases as the amount of SPS resin (B) added increases, approaching the glass transition temperature of the SPS resin (B) alone. Therefore, when SPS resin (B) is mixed with polyphenylene ether resin (A), it may reduce the heat resistance of the PPE resin composition (Z) containing this mixture.

[0069] Therefore, the SPS resin (B) is included in the PPE resin composition (Z) in such a way that it can improve chemical resistance and fluidity without unnecessarily reducing the heat resistance of the PPE resin composition (Z). More specifically, the SPS resin (B) is included in the PPE resin composition (Z) together with the polyphenylene ether resin (A) and the like described above. In particular, in order to exhibit better chemical resistance than the SPS resin (B), the mass ratio of the SPS resin (B) is preferably 60 to 85 parts by mass per 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). The lower limit of the mass ratio of the SPS resin (B) is more preferably 61 parts by mass or more, even more preferably 63 parts by mass or more, and particularly preferably 65 parts by mass or more. The upper limit of the mass ratio of the SPS resin (B) is more preferably 82 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 75 parts by mass or less.

[0070] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and SPS resin (B), the lower limit of the content of SPS resin (B) in the PPE resin composition (Z) is preferably 35% by mass or more, more preferably 37% by mass or more, even more preferably 40% by mass or more, and particularly preferably 45% by mass or more, when the total PPE resin composition (Z) is considered as 100% by mass. Furthermore, the upper limit of the content of SPS resin (B) is preferably 65% ​​by mass or less, more preferably 63% by mass or less, even more preferably 60% by mass or less, and particularly preferably 55% by mass or less.

[0071] Furthermore, when the melt flow rate (MFR) of the SPS resin (B) is measured under conditions of a temperature of 300°C and a load of 1.2 kgf, the lower limit of the MFR is preferably 2 g / 10 min or more, and more preferably 4 g / 10 min or more. The upper limit of the MFR is preferably 50 g / 10 min or less, and more preferably 30 g / 10 min or less. If the lower limit of the MFR is 2 g / 10 min or more, there will be no problem with the fluidity of the PPE resin composition (Z) containing the SPS resin (B) during molding. Also, if the lower limit of the MFR is 50 g / 10 min or less, preferably 30 g / 10 min or less, a molded product with sufficient mechanical properties can be obtained from the PPE resin composition (Z) containing the SPS resin (B) or the like.

[0072] The method for producing SPS resin (B) is not particularly limited, and known methods can be employed. For example, as described in Japanese Patent Application Publication No. 2009-068022, SPS resin (B) can be produced by polymerizing a styrene monomer (a monomer corresponding to the above-mentioned styrene polymer) in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product of water and trialkylaluminum (aluminoxane) as catalysts.

[0073] [Inorganic Filler (C)] Next, the inorganic filler (C) according to the embodiment of the present invention will be described in detail. The inorganic filler (C) is a component (inorganic filler) that constitutes the PPE-based resin composition (Z) according to the embodiment of the present invention, and is included in the PPE-based resin composition (Z) primarily for the purpose of improving the mechanical strength of the PPE-based resin composition (Z).

[0074] Examples of inorganic fillers (C) include fibrous fillers, granular fillers, amorphous fillers, plate-like fillers, or flake-like fillers. For example, examples of fibrous inorganic fillers (C) include glass fibers, carbon fibers, basalt fibers, wollastonite, and potassium titanate fibers. Examples of granular or amorphous inorganic fillers (C) include calcium carbonate, titanium dioxide, feldspar minerals, clay, and glass beads. Examples of plate-like inorganic fillers (C) include talc. Examples of flake-like inorganic fillers (C) include glass flakes, mica, and graphite. Among these, from the viewpoint of improving the mechanical strength of the PPE-based resin composition (Z), fibrous inorganic fillers (C) are preferred, and glass fibers are particularly preferred.

[0075] As the glass fibers mentioned above, chopped glass fibers are preferred, for example, which are formed by bundling 1,000 to 10,000 glass fibers together and cutting them to a predetermined length. Specifically, the number-average fiber length (length) of the glass fibers is preferably 0.5 to 10 mm, and more preferably 1 to 5 mm. By using glass fibers with such a number-average fiber length as an inorganic filler (C), the mechanical strength of the PPE-based resin composition (Z) containing the inorganic filler (C) can be further improved.

[0076] In this specification, the number-average fiber length of glass fibers is calculated by randomly selecting glass fibers to be measured from among multiple glass fibers contained in an image obtained by observation with an optical microscope, measuring the long side of the selected glass fibers, and obtaining the measured value. At this time, the observation magnification is 20x, and the number of measured fibers is 1,000 or more. The number-average fiber length calculated in this way generally corresponds to the cut length of the glass fibers.

[0077] Furthermore, the cross-sectional shape of the glass fiber may be any shape, such as circular, elliptical, oblong, rectangular, a rectangle with semicircles attached to both short sides, or cocoon-shaped. Among these, circular is preferred. Here, "circular" means not only a circular shape in the geometric sense, but also shapes that are commonly referred to as circular in the technical field of the present invention.

[0078] The lower limit of the number-average fiber diameter (diameter) of the above glass fibers is preferably 4.0 μm or more, more preferably 4.5 μm or more, and even more preferably 5.0 μm or more. The upper limit of the number-average fiber diameter of the above glass fibers is preferably 15.0 μm or less, and more preferably 14.0 μm or less. By using glass fibers having a number-average fiber diameter within such upper and lower limit ranges as an inorganic filler (C), it is possible to obtain molded articles with superior mechanical strength of the PPE-based resin composition (Z) containing the inorganic filler (C), etc.

[0079] In this specification, the number-average fiber diameter of glass fibers is calculated by randomly selecting glass fibers to be measured from among multiple glass fibers contained in an image obtained by observation with an electron microscope, measuring the length of the line segment passing through the outer periphery and the center of the cross-section of the selected glass fiber as the fiber diameter, and then calculating from the obtained measurement value. At this time, the observation magnification shall be 1,000 times, and the number of measurements shall be 1,000 or more. For glass fibers with a cross-section other than circular, the number-average fiber diameter shall be the number-average fiber diameter when converted to a circle with the same area as the area of ​​the cross-section.

[0080] Furthermore, it is more preferable to use inorganic filler (C) that has been surface-treated with a surface treatment agent such as a coupling agent to improve adhesion with the resin. Inorganic filler (C), such as glass fiber, to which a surface treatment agent has been applied tends to have excellent durability, resistance to humid heat, resistance to hydrolysis, and resistance to thermal shock.

[0081] Any conventionally known surface treatment agent can be used as the above surface treatment agent. Specifically, various coupling agents such as aminosilane, epoxysilane, allylsilane, vinylsilane, or titanate are suitable examples of the above surface treatment agent. Among these, aminosilane, epoxysilane, and vinylsilane surface treatment agents are preferred. Specific examples of these preferred surface treatment agents include silane compounds such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane. These silane compounds may be used individually or in combination. Furthermore, as the inorganic filler (C), if necessary, a lubricant such as a fatty acid amide compound or silicone oil, an antistatic agent such as a quaternary ammonium salt, a resin with film-forming ability such as epoxy resin or urethane resin, or a mixture of such a resin with film-forming ability and a heat stabilizer or flame retardant may be used.

[0082] The inorganic filler (C) described above has the effect of improving the mechanical strength of the resin composition containing the resin when blended with the resin. Therefore, the inorganic filler (C) contained in the synthetic components of the polyphenylene ether resin (A) and SPS resin (B) that constitute the PPE resin composition (Z) can improve the mechanical strength of the PPE resin composition (Z). Furthermore, since the inorganic filler (C) exhibits little dimensional change with temperature changes, it can improve the dimensional stability of the PPE resin composition (Z) under temperature changes. In addition, by including the inorganic filler (C) in the PPE resin composition (Z), the proportion of resin components in the overall PPE resin composition (Z) can be reduced. As a result, the proportion of resin components that are susceptible to chemicals in the PPE resin composition (Z) decreases, thereby improving the chemical resistance of the PPE resin composition (Z). On the other hand, if the amount of inorganic filler (C) in the PPE-based resin composition (Z) is too high, it may reduce the processability (fluidity) and toughness of the PPE-based resin composition (Z).

[0083] Therefore, the inorganic filler (C) is included in the PPE-based resin composition (Z) in such a way that it can improve mechanical strength, dimensional stability under temperature changes, and chemical resistance without unnecessarily reducing the processability and toughness of the PPE-based resin composition (Z). More specifically, the lower limit of the inorganic filler (C) content in the PPE-based resin composition (Z) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether-based resin (A) and SPS-based resin (B) described above. Furthermore, the upper limit of the inorganic filler (C) content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0084] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and SPS resin (B), the lower limit of the inorganic filler (C) content in the PPE resin composition (Z) is preferably 15% by mass or more, more preferably 17% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more, when the total PPE resin composition (Z) is considered as 100% by mass. Furthermore, the upper limit of the inorganic filler (C) content is preferably 45% by mass or less, more preferably 43% by mass or less, even more preferably 40% by mass or less, and particularly preferably 35% by mass or less. The PPE resin composition (Z) may contain only one type of inorganic filler (C) or two or more types. When the PPE-based resin composition (Z) contains two or more inorganic fillers (C), it is preferable that the total mass percentage of these two or more inorganic fillers (C) is within the above range relative to 100% by mass of the entire PPE-based resin composition (Z).

[0085] Furthermore, the total mass ratio (content ratio) of the polyphenylene ether resin (A), SPS resin (B), and inorganic filler (C) contained in the PPE resin composition (Z) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the PPE resin composition (Z). By keeping the total content ratio within the above range, a PPE resin composition (Z) with good chemical resistance and dimensional stability under temperature changes can be obtained.

[0086] When using glass fibers as an inorganic filler (C), the glass fibers can be those obtained by melt-spinning commonly supplied glass. Examples of commonly supplied glass include E-glass (Electrical glass), C-glass (Chemical glass), A-glass (Alkali glass), S-glass (High-strength glass), D-glass, and alkali-resistant glass. The glass fibers used as the inorganic filler (C) are not particularly limited and can be formed into fibrous glass. Among these, E-glass is preferred as the inorganic filler (C) contained in the PPE-based resin composition (Z).

[0087] The glass fibers mentioned above are available as commercially produced products. Examples of such commercially produced products include T-286H, T-756H, T-127, T-289H, T-249, T-249H, and T-852H from Nippon Electric Glass Co., Ltd., DEFT2A from Owens Corning, HP3540 from PPG, and CSG3PA810, CSG3PA820, and CSG3PA830 from Nitto Boseki Co., Ltd.

[0088] [Phosphorus-based heat stabilizer (D)] Next, the phosphorus-based heat stabilizer (D) applied to the PPE-based resin composition (Z) according to the embodiment of the present invention will be described in detail. In addition to the polyphenylene ether resin (A), SPS resin (B), and inorganic filler (C) described above, the PPE-based resin composition (Z) may also contain a phosphorus-based heat stabilizer (D). The phosphorus-based heat stabilizer (D) is a component that is appropriately included in the PPE-based resin composition (Z) for the purpose of improving the stability (heat resistance) of the PPE-based resin composition (Z) during processing (for example, during melt kneading in the molding process) and during long-term use. Furthermore, by being included in the PPE-based resin composition (Z), the phosphorus-based heat stabilizer (D) can act as an antioxidant for the PPE-based resin composition (Z) and improve its hydrolysis resistance.

[0089] Examples of phosphorus-based heat stabilizers (D) include phosphite compounds and phosphonite compounds. These compounds may be used individually as phosphorus-based heat stabilizers (D), or two or more may be used in combination. Preferably, phosphorus-based heat stabilizers (D) contain at least one of the phosphite compounds and phosphonite compounds.

[0090] Examples of phosphite compounds include phosphite esters. Specific examples of phosphite compounds include tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol-diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, 4,4'-butylidene-bis-(3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris(2-methyl-4-di-tridecylphosphite-5-t-butylphenyl)butane, tris(mixed mono and di-nonylphenyl) phosphite, tris(nonylphenyl) phosphite, and 4,4'-isopropylidenebis(phenyl-dialkylphosphite). Among these, tris(2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-diphosphite are preferred.

[0091] Specific examples of phosphonite compounds include, for example, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,5-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,3,4-trimethylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,3-dimethyl-5-ethylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,6-di-t-butyl-5-ethylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,3,4-tributylphenyl)-4,4'-biphenylenediphosphonite, and tetrakis(2,4,6-tri-t-butylphenyl)-4,4'-biphenylenediphosphonite. Among these, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite is preferred.

[0092] When the PPE resin composition (Z) contains a phosphorus-based heat stabilizer (D), the lower limit of the mass percentage (content ratio) of the phosphorus-based heat stabilizer (D) in the PPE resin composition (Z) is preferably 0.05 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.4 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). Furthermore, the upper limit of the mass percentage of this phosphorus-based heat stabilizer (D) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1 part by mass or less, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B).

[0093] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and SPS resin (B), the lower limit of the content of the phosphorus-based heat stabilizer (D) in the PPE resin composition (Z) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, when the total PPE resin composition (Z) is considered as 100% by mass. Furthermore, the upper limit of the content of the phosphorus-based heat stabilizer (D) is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0094] [Additives] Next, the additives applied to the PPE-based resin composition (Z) according to the embodiment of the present invention will be described in detail. The PPE-based resin composition (Z) may contain other additives in addition to the components described above, such as the polyphenylene ether resin (A), SPS resin (B), and inorganic filler (C), without departing from the spirit of the present invention. Examples of such additives include acid-modified resins, heat stabilizers other than the phosphorus-based heat stabilizer (D) described above, flame retardants, flame retardant aids, ultraviolet absorbers, phenolic antioxidants, weather resistance improvers, foaming agents, lubricants, plasticizers, flow improvers, dispersants, conductive agents, antistatic agents, colorants, and the like.

[0095] Among the additives described above, the acid-modified resin is a resin that acts as a compatibilizer to improve the compatibility between the resin component and components other than the resin. As described above, the PPE-based resin composition (Z) according to the embodiment of the present invention contains resin components such as polyphenylene ether resin (A) and SPS resin (B) and an inorganic filler (C). Therefore, in order to improve the compatibility between the resin component and the inorganic filler (C), an acid-modified resin may be included in addition to the modified polyphenylene ether resin (Ab) described above.

[0096] In detail, the acid-modified resin has compatibility with the resin components (particularly polyphenylene ether resin (A) and SPS resin (B)) in the PPE-based resin composition (Z). From the viewpoint of improving the compatibility between the resin components and the inorganic filler (C), it is preferable that the acid-modified resin has polar groups that can react with the inorganic filler (C). By adding such an acid-modified resin, the compatibility between the resin components in the PPE-based resin composition (Z) and the inorganic filler (C) can be improved, and thus the interfacial strength between these resin components and the inorganic filler (C) can be improved.

[0097] A preferred structure for the acid-modified resin is one that contains chains compatible with polyphenylene ether resin (A) and SPS resin (B) within the polymer chain. Examples of such structures include those containing chains of polystyrene, polyvinyl methyl ether, etc., as the main chain or graft chain of the polymer chain.

[0098] Furthermore, if the acid-modified resin has a polar group that can react with the inorganic filler (C), the polar group is a functional group that can react with the polar group of the inorganic filler (C). Specific examples of such polar groups include acid anhydride groups, carboxylic acid groups, carboxylic acid ester groups, carboxylic acid halide groups, carboxylic acid amide groups, carboxylic acid bases, sulfonic acid groups, sulfonic acid ester groups, sulfonate chloride groups, sulfonic acid amide groups, sulfonic acid bases, epoxy groups, amino groups, imide groups, oxazoline groups, and the like. Among these, the carboxylic acid group is preferred as the polar group.

[0099] The inclusion of the above-described acid-modified resin in the PPE-based resin composition (Z) improves the compatibility between the resin components in the PPE-based resin composition (Z) and the inorganic filler (C). Specifically, the wettability of the inorganic filler (C), such as glass fibers, is improved, thereby improving the adhesion between the resin components in the PPE-based resin composition (Z) and the inorganic filler (C).

[0100] Furthermore, among the above additives, the phenolic antioxidant (hereinafter referred to as phenolic antioxidant (E)) is a component that is appropriately included in the PPE resin composition (Z) primarily for the purpose of preventing oxidation of the PPE resin composition (Z). In addition, the phenolic antioxidant (E) is a component that is appropriately included in the PPE resin composition (Z) for the purpose of improving the stability (heat resistance stability) of the PPE resin composition (Z) during processing (for example, during melt mixing in the molding process) and during long-term use.

[0101] When the PPE resin composition (Z) contains a phenolic antioxidant (E), the lower limit of the mass percentage (content ratio) of the phenolic antioxidant (E) in the PPE resin composition (Z) is preferably 0.05 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.4 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). Furthermore, the upper limit of the mass percentage of this phenolic antioxidant (E) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1 part by mass or less, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B).

[0102] Focusing on the total mass of the PPE resin composition (Z) containing the above-mentioned polyphenylene ether resin (A) and SPS resin (B), the lower limit of the content of the phenolic antioxidant (E) in the PPE resin composition (Z) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, when the total PPE resin composition (Z) is considered as 100% by mass. Furthermore, the upper limit of the content of the phenolic antioxidant (E) is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0103] Specific examples of phenolic antioxidants (E) include, for example, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, 1,6-hexanediol-bis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate], pentaerythritol-tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate], 2,6-di-t-butyl-4-methylphenol, and 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]un Examples include decane, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)benzene, 2,2-thio-diethylenebis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate], tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, and N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxyhydrocinnamide). Among these, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, 1,6-hexanediol-bis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate], 2,6-di-t-butyl-4-methylphenol, and 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane are preferred.

[0104] Furthermore, among the additives mentioned above, examples of heat stabilizers other than phosphorus-based heat stabilizers (D) and phenol-based antioxidants (E) include sulfur-based compounds and zinc oxide. These compounds may be used individually as heat stabilizers, or two or more may be used in combination.

[0105] Specific examples of sulfur compounds include didodecylthiodipropionate, ditetradecylthiodipropionate, dioctadecylthiodipropionate, pentaerythritoltetrakis(3-dodecylthiopropionate), pentaerythrityltetrakis(3-tetradecylthiopropionate), pentaerythrityltetrakis(3-tridecylthiopropionate), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropylxanthate, and trilauryltrithiophosphite. Among these, thioether-based antioxidants having a thioether structure are particularly suitable for use as heat stabilizers because they receive oxygen from oxidized substances and reduce them. The lower limit of the molecular weight of the sulfur compound is usually 200 or more, preferably 500 or more. The upper limit of the molecular weight of the sulfur compound is usually 3,000 or less.

[0106] As for the zinc oxide, for example, those with an average particle size of 0.02 to 1 μm are preferred, and those with an average particle size of 0.08 to 0.8 μm are more preferred.

[0107] When the PPE-based resin composition (Z) contains the above-mentioned stabilizer, the lower limit of the mass percentage (content ratio) of the stabilizer in the PPE-based resin composition (Z) is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). Furthermore, the upper limit of the mass percentage (content ratio) of the stabilizer in the PPE-based resin composition (Z) is preferably 1 part by mass or less, more preferably 0.7 parts by mass or less, and even more preferably 0.5 parts by mass or less, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). By setting the lower limit of the mass percentage of the above-mentioned stabilizer to 0.001 parts by mass or more, a sufficient improvement in the thermal stability of the PPE-based resin composition (Z) can be obtained. Furthermore, by limiting the mass ratio of the stabilizer to 1 part by mass or less, it is possible to prevent contamination of the mold when molding the PPE-based resin composition (Z) and to prevent a decrease in the mechanical strength of the PPE-based resin composition (Z).

[0108] Furthermore, among the above additives, examples of colorants include white pigments and dyes. The PPE resin composition (Z) may contain at least one of these colorants for the purpose of color matching.

[0109] Examples of white pigments include titanium dioxide, zinc sulfide, and lithopone. When the PPE resin composition (Z) contains a white pigment, the upper limit of the mass percentage (content ratio) of the white pigment in the PPE resin composition (Z) is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 2.0 parts by mass or less, based on 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B). The lower limit of this mass percentage of the white pigment is not particularly defined as long as the PPE resin composition (Z) can be color-matched, but it is preferably 0.01 parts by mass or more. By including a white pigment within this range in the PPE resin composition (Z), the PPE resin composition (Z) can be color-matched without impairing its mechanical strength.

[0110] The PPE-based resin composition (Z) may contain one of the additives described above, or it may contain a mixture of two or more additives. The PPE-based resin composition (Z) can effectively exhibit the functions of each additive it contains. For example, when a weather-resistant modifier and a lubricant are added to the PPE-based resin composition (Z), the weather resistance and mold release properties during injection molding tend to improve.

[0111] [Other Resin Components] Next, other resin components contained in the PPE resin composition (Z), other than the polyphenylene ether resin (A), SPS resin (B), and acid-modified resin described above, will be described in detail. The PPE resin composition (Z) may contain other resin components in addition to the polyphenylene ether resin (A), SPS resin (B), and acid-modified resin described above, without departing from the spirit of the present invention.

[0112] More specifically, other resin components mentioned above include, for example, thermoplastic resins or thermosetting resins. Examples of thermoplastic resins include polyamide resins, polystyrene resins, polyester resins, polyphenylene sulfide resins, liquid crystal polyester resins, polycarbonate resins, polyacetal resins, polyacrylonitrile resins, acrylic resins, and polyethylene resins. Examples of thermosetting resins include epoxy resins, melamine resins, and silicone resins.

[0113] The PPE-based resin composition (Z) may contain two or more thermoplastic resins, two or more thermosetting resins, or a combination of two or more of these thermoplastic resins and thermosetting resins as the other resin components. Furthermore, the upper limit of the mass percentage of the other resin components in 100% by mass of the PPE-based resin composition (Z) is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5% by mass or less.

[0114] [Dimensional Stability under Temperature Changes] Next, the dimensional stability of the PPE-based resin composition (Z) under temperature changes according to the embodiment of the present invention will be described in detail. The dimensional stability of the PPE-based resin composition (Z) under temperature changes (hereinafter sometimes abbreviated as the dimensional stability of the PPE-based resin composition (Z)) refers to the dimensional stability of the PPE-based resin composition (Z) with respect to temperature changes after molding. That is, the dimensional stability under temperature changes is a physical property that indicates how difficult it is for the molded article of the PPE-based resin composition (Z) to change dimensions due to expansion or contraction with respect to temperature changes. For example, the higher the dimensional stability of the PPE-based resin composition (Z), the smaller the amount of dimensional change (amount of expansion or contraction) of the molded article of the PPE-based resin composition (Z) with respect to temperature changes. Such dimensional stability of the PPE-based resin composition (Z) is expressed by the coefficient of linear expansion of the PPE-based resin composition (Z).

[0115] Furthermore, the PPE-based resin composition (Z) contains inorganic fillers (C) in its resin components. Inorganic fillers (C) are components with a large aspect ratio, as exemplified by glass fibers. Therefore, when the molten PPE-based resin composition (Z) is injected into a mold for molding, the inorganic fillers (C) in the PPE-based resin composition (Z) tend to orient in the flow direction (MD) due to the shear force during injection molding. That is, in a molded body of the PPE-based resin composition (Z), the proportion of inorganic fillers (C) oriented in the flow direction (MD) is higher than the proportion oriented in the perpendicular direction (TD). As a result, there is a difference in the amount of dimensional change in the molded body due to temperature changes between the flow direction (MD) and the perpendicular direction (TD). In other words, there is anisotropy in the coefficient of linear expansion of the PPE-based resin composition (Z) between the flow direction (MD) and the perpendicular direction (TD). The flow direction (MD) is the flow direction of the PPE-based resin composition (Z) flowing inside the mold. The perpendicular direction (TD) is the direction perpendicular to the flow direction (MD).

[0116] The anisotropy of the linear expansion coefficient of a PPE-based resin composition (Z) is expressed by the ratio of the linear expansion coefficient in the flow direction (MD) to the linear expansion coefficient in the perpendicular direction (TD) of the PPE-based resin composition (Z). For example, if the linear expansion coefficient in the flow direction (MD) of the PPE-based resin composition (Z) during molding is denoted as the MD value and the linear expansion coefficient in the perpendicular direction (TD) is denoted as the TD value, then the anisotropy of the linear expansion coefficient of the PPE-based resin composition (Z) is expressed by the anisotropy ratio (TD / MD), which is the ratio of the TD value to the MD value. In this invention, the anisotropy ratio (TD / MD) is the value obtained by dividing the TD value by the MD value.

[0117] Generally, when inorganic fillers such as glass fibers are included in the molten resin injected into a mold, these inorganic fillers are more likely to be oriented in the flow direction (MD) than in the direction perpendicular to the injection-molded resin article (TD). Therefore, the coefficient of linear expansion in the flow direction (MD) (MD value) of the resin article tends to be lower than the coefficient of linear expansion in the direction perpendicular to the flow direction (TD value). Consequently, when the anisotropy ratio (TD / MD) is calculated for the resin article, it is usually greater than 1. If the anisotropy ratio (TD / MD) of the resin article is excessively large compared to 1, the anisotropy of the coefficient of linear expansion of the resin article is large, which can lead to defects such as warping. Therefore, from the viewpoint of dimensional stability under temperature changes, it is desirable for the anisotropy of the coefficient of linear expansion of the resin article to be small.

[0118] In the present invention, in order to reduce the anisotropy of the coefficient of linear expansion of the PPE-based resin composition (Z), it is preferable to make the anisotropy ratio (TD / MD) of the PPE-based resin composition (Z) close to 1. More specifically, the lower limit of the anisotropy ratio (TD / MD) of the PPE-based resin composition (Z) is preferably 0.7 or higher, more preferably 0.8 or higher, even more preferably 0.9 or higher, and particularly preferably 0.95 or higher. Furthermore, the upper limit of the anisotropy ratio (TD / MD) is preferably 4.0 or lower, more preferably 3.5 or lower, and even more preferably 3.0 or lower. By making the anisotropy ratio (TD / MD) of the PPE-based resin composition (Z) within the range of the above upper and lower limits, it is possible to suppress defects such as warping due to dimensional changes in the PPE-based resin composition (Z) and changes in the shape of the molded product.

[0119] [Crystallization Temperature by Temperature Increase] Next, the crystallization temperature by temperature increase of the PPE-based resin composition (Z) according to the embodiment of the present invention will be described in detail. In this specification, the crystallization temperature by temperature increase is the temperature at which the resin components in a resin molded article obtained by resin injection molding crystallize when the temperature of the resin molded article is increased. The crystallization temperature by temperature increase of the PPE-based resin composition (Z) is determined by differential scanning calorimetry (DSC) and is 150°C or higher, as described above.

[0120] One method for measuring the temperature of crystallization by heating is to use a differential scanning calorimeter. For example, in this measurement method, a test piece cut from a molded body of a PPE-based resin composition (Z) is placed in the measuring pan of a differential scanning calorimeter, and the test piece is heated to a temperature above its melting point under a nitrogen atmosphere at a heating rate of 10°C / min. After pretreatment by rapidly cooling the heated test piece, the temperature of the crystallization by heating of the test piece is measured. At this time, the temperature at the peak top of the exothermic peak (i.e., the crystallization peak) that appears when the test piece is heated at a heating rate of 10°C / min is measured as the temperature of crystallization by heating.

[0121] As described above, the PPE-based resin composition (Z) is a resin composition in which a temperature-induced crystallization peak appears when differential scanning calorimetry is performed on its molded article. In other words, a molded article of the PPE-based resin composition (Z) contains portions of the resin components that did not crystallize during injection molding.

[0122] On the other hand, resin molded articles that do not show a temperature-induced crystallization peak when differential scanning calorimetry is of either type 1 or type 2 as described below. Type 1 resin molded articles are those in which the contained resin components have completely crystallized during injection molding. Type 2 resin molded articles are those in which the crystallization of the resin components is inhibited by amorphous resin in the contained resin components, and the resin components do not have a crystalline structure. When the resin molded article is of type 1, the anisotropy of the coefficient of linear expansion is excessively large in the direction perpendicular to the flow direction (MD) and the direction perpendicular to the flow direction (TD), resulting in low dimensional stability of the resin molded article with respect to temperature changes. When the resin molded article is of type 2, the resin molded article has low chemical resistance.

[0123] Therefore, the PPE-based resin composition (Z) is preferably one that can form a molded article containing a resin component that can crystallize (hereinafter referred to as the crystalline component) but is not completely crystallized (hereinafter referred to as the first condition), and in which a temperature-induced crystallization peak appears when differential scanning calorimetry is performed (hereinafter referred to as the second condition). In the present invention, the PPE-based resin composition (Z) contains an amorphous resin, a polyphenylene ether-based resin (A), and a crystalline component, an SPS-based resin (B), and contains the polyphenylene ether-based resin (A) in a ratio of 15 to 40 parts by mass per 100 parts by mass of the total of these resin components. As a result, the PPE-based resin composition (Z) satisfies the first condition described above. Furthermore, since the temperature-induced crystallization temperature of the PPE-based resin composition (Z) is 150°C or higher, the temperature-induced crystallization peak appears in a molded article of the PPE-based resin composition (Z) at temperatures of 150°C or higher. In other words, the PPE-based resin composition (Z) satisfies not only the first condition but also the second condition.

[0124] Furthermore, the dimensions of a molded article of the PPE-based resin composition (Z) change as the crystallization of the contained resin components progresses. For this reason, it is preferable that the temperature at which the PPE-based resin composition (Z) crystallizes is not within the range of the operating temperature of the molded article. In the present invention, since the temperature at which the PPE-based resin composition (Z) crystallizes is 150°C or higher, if a molded article of the PPE-based resin composition (Z) is used within a temperature range of less than 150°C, the crystallization of the resin components in the molded article will not progress. This suppresses dimensional changes due to crystallization of the molded article, thereby improving the dimensional stability of the molded article with respect to temperature changes. For example, if the operating temperature of the molded article is set to -30 to 140°C, the operating temperature is less than 150°C, so high dimensional stability of the PPE-based resin composition (Z) can be maintained within this operating temperature range.

[0125] [Method for Producing PPE-based Resin Composition (Z)] Next, a method for producing the PPE-based resin composition (Z) according to an embodiment of the present invention will be described in detail. The method for producing the PPE-based resin composition (Z) is not limited to a specific method, and known methods can be employed. Examples of such production methods include a melt-kneading method in which various components, such as the polyphenylene ether resin (A), SPS resin (B), inorganic filler (C), phosphorus-based heat stabilizer (D), and phenol-based antioxidant (E) described above, are melt-kneaded in a kneader and then cooled and solidified, or a solution mixing method in which the various components are appropriately added to a suitable solvent and mixed in a suspension state, either with other soluble components or with other soluble components. Examples of kneaders used in such production methods include single-screw extruders, multi-screw extruders, Banbury mixers, rolls, Bravender plastograms, etc. Examples of solvents include hydrocarbons such as hexane, heptane, benzene, toluene, and xylene, and their derivatives.

[0126] From an industrial cost standpoint, a melt-kneading method is preferred for manufacturing the PPE-based resin composition (Z). In this melt-kneading method, the kneading temperature and kneading time can be arbitrarily selected depending on the desired PPE-based resin composition (Z), the type of kneader, and other conditions. For example, the kneading temperature is preferably 200 to 350°C, and more preferably 220 to 320°C. The kneading time is preferably 20 minutes or less. If the kneading temperature exceeds 350°C, thermal degradation of the polyphenylene ether-based resin (A) or SPS-based resin (B) may occur. As a result, there is a risk of a decrease in physical properties or defects in appearance in the molded article of the PPE-based resin composition (Z).

[0127] [Pellets and Molded Articles] Next, pellets and molded articles according to embodiments of the present invention will be described in detail. Pellets according to embodiments of the present invention are an example of a molded article containing the above-described PPE-based resin composition (Z), and can be obtained, for example, by pelletizing the PPE-based resin composition (Z). Molded articles according to embodiments of the present invention are an example of a molded article containing the above-described PPE-based resin composition (Z), and can be manufactured, for example, by molding the pellets of the above-described PPE-based resin composition (Z) using various molding methods. Alternatively, the molded articles may be manufactured by directly molding the PPE-based resin composition (Z) that has been melt-kneaded in a kneader, without going through the above-described pellets.

[0128] The molding method for the PPE-based resin composition (Z) is not limited to a specific method, and known methods can be employed. For example, various molding methods for the PPE-based resin composition (Z) include injection molding, injection compression molding, hollow molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, and press molding.

[0129] The pellets and molded articles produced by the above molding method contain the PPE-based resin composition (Z) according to the embodiment of the present invention, and therefore possess the excellent properties of the various components contained in the PPE-based resin composition (Z). In particular, the molded articles combine heat resistance due to the polyphenylene ether resin (A), processability and chemical resistance due to the SPS resin (B), high mechanical strength due to the inorganic filler (C), and high dimensional stability due to the combination of these components.

[0130] Because these pellets and molded products possess the excellent properties described above, they can be widely used in various applications such as electrical and electronic equipment components, automotive and electronic components, home appliances, various machine parts, and industrial materials.

[0131] As described above, the PPE-based resin composition (Z) according to the embodiment of the present invention contains a polyphenylene ether resin (A), an SPS resin (B), and an inorganic filler (C). In this PPE-based resin composition (Z), the mass ratio of the polyphenylene ether resin (A) is 15 to 40 parts by mass per 100 parts by mass of the total of the polyphenylene ether resin (A) and the SPS resin (B), and the temperature of crystallization by differential scanning calorimetry is 150°C or higher.

[0132] Therefore, high dimensional stability (dimensional stability under temperature changes) can be obtained by blending polyphenylene ether resin (A), SPS resin (B), and inorganic filler (C). Furthermore, the decrease in chemical resistance caused by the amorphous polyphenylene ether resin (A) is improved by the crystalline SPS resin (B), and high chemical resistance can be obtained from the SPS resin (B). As a result, the PPE resin composition (Z) can be made to have excellent chemical resistance and high dimensional stability under temperature changes.

[0133] Furthermore, by molding the PPE-based resin composition (Z) described above, pellets and molded articles that benefit from the effects of the PPE-based resin composition (Z) can be easily obtained. By selecting the constituent components of the PPE-based resin composition (Z) used as the material, such pellets and molded articles can possess various properties required for their application (such as chemical resistance and dimensional stability under temperature changes).

[0134] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0135] (Examples 1 and 2, Comparative Examples 1 to 3 and Reference Example) [Components of the Polyphenylene Ether Resin Composition] The components of the polyphenylene ether resin composition (PPE resin composition) in each of Examples 1 and 2, Comparative Examples 1 to 3 and Reference Example are as shown in Table 1.

[0136] In each of Examples 1 and 2, the polyphenylene ether resin (A), styrene resin having a syndiotactic structure (B) (SPS resin (B)), inorganic filler (C), phosphorus-based heat stabilizer (D), and phenol-based antioxidant (E) shown in Table 1 are used as needed. Specifically, as the SPS resin (B), syndiotactic polystyrene resin (SPS) is used, as shown in Table 1.

[0137] In Comparative Examples 1 to 3 and the Reference Example, each of the above components is used as needed. For example, in Comparative Example 3, a polyphenylene ether resin composition that does not contain polyphenylene ether resin (Aa) is used. In the Reference Example, a styrene resin (Bx) that does not have a syndiotactic structure is used instead of the SPS resin (B) used in Examples 1 and 2. Specifically, as shown in Table 1, high-impact polystyrene (HIPS) is used as the styrene resin (Bx) that does not have a syndiotactic structure.

[0138] As shown in Table 1, component (A-1) is used as the polyphenylene ether resin (A). Component (Aa-1) is used as the polyphenylene ether resin (Aa) contained in component (A-1). Component (Ab-1) is used as the modified polyphenylene ether resin (Ab) contained in component (A-1). Component (B-1) is used as the SPS resin (B). Component (Bx-1) is used as the styrene resin (Bx) that does not have a syndiotactic structure. Component (C-1) is used as the inorganic filler (C). Component (D-1) is used as the phosphorus-based heat stabilizer (D). Component (E-1) is used as the phenol-based antioxidant (E).

[0139] The melt flow rate (MFR) listed in Table 1 is measured in accordance with JIS K7210. The measurement conditions for the MFR are a temperature of 300°C and a load of 1.2 kgf.

[0140]

[0141] [Method for producing pellets of PPE-based resin composition] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the components shown in Table 1 above were mixed in the proportions (based on parts by mass) shown in Table 2 below. The mixture of the above components was melt-kneaded using a twin-screw extruder (Shibaura Machinery Co., Ltd.: TEM18SS) with the cylinder temperature set to 280°C, the die head temperature to 280°C, and the screw rotation speed set to 400 rpm. This produced a PPE-based resin composition. Subsequently, the strands of this PPE-based resin composition were extruded, and the extruded strands were cut (pelletized) to obtain pellets of this PPE-based resin composition. The obtained pellets of the PPE-based resin composition were used for the measurements and evaluations shown below.

[0142] [Measurement of Crystallization Temperature by Temperature Increase] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the crystallization temperature by temperature increase was measured for molded articles of PPE-based resin compositions made using pellets obtained by the above manufacturing method. Specifically, the pellets of the PPE-based resin composition obtained by the above manufacturing method were dried at 100°C for 4 hours, and then supplied to an injection molding machine (Shibaura Machine Co., Ltd.: EC75SX). Using this injection molding machine, 4 mm thick ISO 3167:93A type test specimens (hereinafter referred to as ISO test specimens) made of the PPE-based resin composition were injection molded in accordance with ISO-15103. At this time, the injection molding conditions were a cylinder temperature of 310°C and a mold temperature of 70°C.

[0143] Approximately 10 mg of a specimen was cut from the parallel section of the ISO specimen prepared as described above, and the crystallization temperature of the cut specimen was measured by differential scanning calorimetry (DSC). Specifically, the cut specimen was placed in the measurement pan of the differential scanning calorimeter, and the specimen was heated to a temperature above its melting point under a nitrogen atmosphere at a heating rate of 10°C / min, followed by rapid cooling as a pretreatment. After that, the specimen was heated at a heating rate of 10°C / min, and the temperature at the peak top of the exothermic peak (crystallization peak) that appeared at this time was measured as the crystallization temperature of the specimen.

[0144] [Chemical Resistance] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, chemical resistance was evaluated using the ISO test specimens obtained as described above. Specifically, the parallel portion of the ISO test specimen obtained as described above was machined in accordance with ISO-75-2 to produce a strip-shaped test specimen with dimensions of length × width × thickness = 80 mm × 10 mm × 4 mm. The obtained strip-shaped test specimens were annealed at 140°C for 3 hours, and then immersed in a chemical for 22 hours at a temperature of 23°C and a humidity of 50%. A 0.4% xylene aqueous solution was used as the chemical.

[0145] The bending strength of strip-shaped test specimens before and after immersion in chemicals was measured in an environment of 23°C and 50% humidity, using a measurement method compliant with ISO-178. Based on the obtained measurement results, the retention rate of the bending strength (unit: MPa) of the strip-shaped test specimens before and after immersion in chemicals was calculated, and this retention rate (unit: %) was evaluated as chemical resistance. In this evaluation, the retention rate of bending strength was calculated by dividing the bending strength of the strip-shaped test specimen after immersion in chemicals by the bending strength of the strip-shaped test specimen before immersion in chemicals.

[0146] [Dimensional Stability under Temperature Changes] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the dimensional stability under temperature changes was evaluated using the ISO test specimens obtained as described above. Specifically, a test specimen measuring 10 mm × 10 mm × 4 mm (length × width × thickness) was cut from the center of the ISO test specimen obtained as described above, in accordance with ISO 11359-2. The cut-out test specimen was annealed at 140°C for 3 hours and then used to measure the coefficient of linear expansion.

[0147] In measuring the coefficient of linear expansion, the specimen cut as described above was placed in a thermomechanical analyzer (TMA) so that the resin flow direction (MD) and perpendicular direction (TD) were the target of measurement. In accordance with ISO 11359-2, the dimensional change in the flow direction (MD) and perpendicular direction (TD) of the specimen was measured while the specimen was heated from -30°C to 140°C at a heating rate of 3°C / min. From the ratio (slope) of the measured dimensional change to the temperature change, the coefficient of linear expansion in the flow direction (MD value) and the coefficient of linear expansion in the perpendicular direction (TD value) of the specimen in the temperature range of -30 to 140°C were calculated. In this measurement, the unit of the coefficient of linear expansion is 1 / °C.

[0148] Furthermore, based on the MD and TD values ​​calculated as described above, the anisotropy ratio (TD / MD), which indicates the anisotropy of the linear expansion coefficient of the test specimen, was calculated. The dimensional stability of the test specimen under temperature changes was evaluated using the anisotropy ratio (TD / MD) calculated in this way. For example, the closer the anisotropy ratio (TD / MD) is to 1, the less anisotropy there is in the linear expansion coefficient of the test specimen, and therefore the higher the dimensional stability of the test specimen under temperature changes.

[0149] [Heat Resistance Evaluation] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the heat resistance of the ISO test specimens obtained as described above was evaluated. Specifically, the parallel portion of the ISO test specimen obtained as described above was machined in accordance with ISO-75-2, thereby producing a strip-shaped test specimen with dimensions of length × width × thickness = 80 mm × 10 mm × 4 mm. Using the obtained strip-shaped test specimen, the temperature of deflection under load conditions of 1.80 MPa (unit: °C) was measured. The heat resistance of the test specimen was evaluated by the temperature of deflection under load (DTUL) measured in this manner.

[0150] [Evaluation of Mechanical Strength] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the mechanical strength was evaluated using the ISO test specimens obtained as described above. Specifically, the tensile strength (unit: MPa) of the ISO test specimens obtained as described above was measured in an environment of 23°C using a measurement method compliant with ISO-527. The mechanical strength of the test specimens was evaluated based on the tensile strength measured in this manner.

[0151] [Evaluation of Processability] In each of Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the melt volume flow rate (MVR) was evaluated as the processability (fluidity) of the PPE resin composition. Specifically, for each PPE resin composition in Examples 1 and 2, Comparative Examples 1 to 3, and the Reference Example, the MVR (unit: cm) was evaluated in accordance with ISO-1133 under conditions of a temperature of 300°C and a load of 2.16 kgf. 3 The value ( / 10 min) was measured.

[0152] [Evaluation Results] Table 2 shows the content ratio (based on parts by mass) of each component of the PPE resin composition in each of Examples 1 and 2, Comparative Examples 1 to 3, and Reference Example, along with the results of the above measurements and evaluations. In Table 2, the content ratio of each component is shown as the mass ratio relative to 100 parts by mass of the total of component (A-1) and component (B-1). The content ratio of component (A-1) is shown as the sum of component (Aa-1) and component (Ab-1). In Reference Example, where the PPE resin composition contains component (Bx-1) instead of component (B-1), the content ratio of each component is shown as the mass ratio relative to 100 parts by mass of the total of component (A-1) and component (Bx-1). In Table 2, "No Peak" means that no heating crystallization peak appeared in the measurement of the heating crystallization temperature of the PPE resin composition by differential scanning calorimetry (i.e., there is no heating crystallization temperature). In Table 2, "dimensional stability" refers to dimensional stability under temperature changes.

[0153] In Examples 1 and 2, as shown in Table 2, measurement results for the temperature rise crystallization temperature and evaluation results for chemical resistance, dimensional stability under temperature changes, heat resistance, mechanical strength, and processability were obtained. Specifically, in both Examples 1 and 2, the mass ratio of component (A-1) to 100 parts by mass of the total of component (Aa-1) and component (B-1) (the total mass ratio of component (Aa-1) and component (Ab-1)) satisfies 15 to 40 parts by mass, and therefore the chemical resistance is better than that of Comparative Examples 1 to 3 and the Reference Example. Accordingly, both PPE-based resin compositions in Examples 1 and 2 had a higher retention rate of bending strength before and after immersion in chemicals than Comparative Examples 1 to 3 and the Reference Example, and exhibited excellent chemical resistance. In particular, a comparison between Examples 1 and 2, which contain amorphous components (Aa-1) and (Ab-1) in a total ratio of 15 to 40 parts by mass, and Comparative Example 3, which has the highest content ratio of crystalline resin component (B-1) in the resin components (crystalline component ratio), shows that Examples 1 and 2 exhibit higher chemical resistance than Comparative Example 3, which is a noteworthy result.

[0154] Furthermore, the anisotropy ratio (TD / MD) of the coefficient of linear expansion for both PPE-based resin compositions in Examples 1 and 2 was 3 or less, which is lower than that of Comparative Examples 1 to 3. In other words, higher dimensional stability was obtained in both Examples 1 and 2 than in Comparative Examples 1 to 3. In particular, the temperature at which crystallization occurred in both Examples 1 and 2 was 150°C or higher, which is higher than that of Comparative Example 3. That is, unlike the PPE-based resin compositions of Comparative Examples 1 to 3 and the Reference Example, both PPE-based resin compositions in Examples 1 and 2 satisfy the first condition that "a molded article containing crystalline components but not completely crystallized can be formed" in the temperature range below 150°C, and the second condition that "a temperature-induced crystallization peak appears when differential scanning calorimetry is performed" in the temperature range of 150°C or higher. Therefore, both PPE-based resin compositions of Examples 1 and 2 can produce molded articles that maintain the high dimensional stability described above within a temperature range of less than 150°C, for example, within a wide range of operating temperatures of -30 to 140°C.

[0155] Furthermore, as described above, Examples 1 and 2 obtained excellent heat resistance and high dimensional stability, as well as excellent heat resistance, mechanical strength, and processability, as shown in Table 2. Among these, the mechanical strength (tensile strength) of Examples 1 and 2 was higher than that of Comparative Examples 1 to 3 and the Reference Example.

[0156] Furthermore, the processability (MVR) of Examples 1 and 2 was higher than that of Comparative Examples 1 and 2, which contained components (Aa-1) and (B-1) respectively. Generally, the MVR of a PPE resin composition depends on the content ratio of styrene resin, so the PPE resin composition of Comparative Example 3, which contains component (B-1) but does not contain component (Aa-1), had a high MVR. However, the PPE resin composition of Comparative Example 3, which does not contain component (Aa-1), had a poor balance of components (A-1) and (B-1), and its physical properties other than MVR were inferior to those of Examples 1 and 2. In particular, Comparative Example 3 was significantly inferior to Examples 1 and 2 in terms of heat resistance and dimensional stability under temperature changes, which are obtained by the inclusion of components (Aa-1) and (Ab-1).

[0157] Furthermore, the PPE resin composition of the reference example has a blending balance of polyphenylene ether resin and styrene resin that is similar to that of Example 1. However, the styrene resin contained in this PPE resin composition is component (Bx-1) and does not have a syndiotactic structure. In other words, component (Bx-1) is an amorphous resin and is not a resin component (crystalline component) that can improve chemical resistance. Therefore, the chemical resistance of the reference example is significantly inferior to that of Examples 1 and 2, as shown in Table 2.

[0158]

[0159] It should be noted that the present invention is not limited to the embodiments and examples described above, and configurations that appropriately combine the above-described components are also included in the present invention. Furthermore, all other embodiments, examples, and operational techniques based on the embodiments described above by those skilled in the art are also included in the scope of the present invention.

[0160] The polyphenylene ether-based resin composition according to the present invention is suitable for realizing resin compositions that have excellent chemical resistance and high dimensional stability under temperature changes, as well as pellets and molded articles using the same.

Claims

1. A polyphenylene ether resin composition comprising a polyphenylene ether resin (A), a styrene resin having a syndiotactic structure (B), and an inorganic filler (C), wherein the mass ratio of the polyphenylene ether resin (A) is 15 to 40 parts by mass per 100 parts by mass of the total of the polyphenylene ether resin (A) and the styrene resin having a syndiotactic structure (B), and the temperature of crystallization by differential scanning calorimetry is 150°C or higher.

2. The polyphenylene ether resin composition according to claim 1, characterized in that, when the linear thermal expansion coefficient of the polyphenylene ether resin composition during molding is defined as the MD value, and the linear thermal expansion coefficient in the direction perpendicular to the flow direction is defined as the TD value, the ratio of the TD value to the MD value (TD / MD), which indicates the anisotropy of the linear thermal expansion coefficient of the polyphenylene ether resin composition, is 3.0 or less.

3. The polyphenylene ether resin composition according to claim 1, characterized in that the mass ratio of the polyphenylene ether resin (A) is 20 to 40 parts by mass with respect to 100 parts by mass of the total of the polyphenylene ether resin (A) and the styrene resin (B) having a syndiotactic structure.

4. A pellet comprising the polyphenylene ether-based resin composition described in any one of claims 1 to 3.

5. A molded article characterized by comprising the polyphenylene ether resin composition described in any one of claims 1 to 3.

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