JP7490465B2 - Polyphenylene ether resin composition - Google Patents

Description

The present invention relates to a polyphenylene ether resin composition.

Polyphenylene ether resin (PPE) has a wide range of properties, including excellent mechanical properties, electrical properties, acid and alkali resistance, and heat resistance, as well as low specific gravity, low water absorption, and good dimensional stability, and is therefore widely used as a material for home appliances, office equipment, business machines, information equipment, automobiles, etc. In recent years, there has been an increasing demand for resin materials that can be molded into thinner, lighter, and more attractive molded bodies that can be used without painting for parts used in such applications.

Patent Document 1 discloses a technology relating to a resin composition having improved molding fluidity even when an inorganic filler is added, by blending a specific amount of a terpene phenolic resin or a chromane indene resin with a polyphenylene ether resin reinforced with an inorganic filler.
Furthermore, Patent Document 2 discloses a method for improving adhesion to polyurethane foam by blending a specific amount of a terpene phenol resin with a polyphenylene ether resin composition.
Patent Document 3 describes that by blending a specific amount of a hydrocarbon resin, such as a petroleum resin, having a specific softening point with a poly(arylene ether) resin, molding flow properties and the gloss value of a molded product can be improved.

Japanese Patent Application Laid-Open No. 59-126460 Japanese Patent Application Laid-Open No. 2-199164 International Publication No. 2012/115664

However, because molded products made from conventional polyphenylene ether resins do not have sufficient molding fluidity, when injection molding thin-walled molded products, particularly those with a large surface area, are sometimes molded under high-temperature conditions exceeding 300°C. During molding, silver streaks, thought to be due to decomposition of the resin components and additive components, often appear on the surface of the molded product, deteriorating the appearance of the molded product.

The techniques described in Patent Documents 1 to 3 above do indeed improve molding flowability and produce resin compositions that can improve the gloss of molded products. On the other hand, under harsh molding conditions, silver streaks may occur during molding, which can degrade the surface appearance of the molded product, and are not necessarily sufficient to produce molded products with high appearance that can be used without painting.

The present invention aims to provide a polyphenylene ether resin composition that has an excellent balance between molding flowability and heat resistance, significantly suppresses the occurrence of silver streaks on the surface of molded articles during molding, and can produce molded articles that can be used as thin-walled molded articles with excellent appearance without painting.

The inventors conducted extensive research to solve the above problems with the aim of developing a polyphenylene ether resin composition that has an excellent balance between molding flowability and heat resistance and can be used to mold thin-walled molded articles with excellent appearance without painting. As a result, they discovered that by incorporating a specific ratio of polystyrene resin, a specific elastomer component, and a terpene phenol resin with a specific softening point into a polyphenylene ether resin, it is possible to prevent poor appearance due to silver streaks on the surface of the molded article, improve molding flowability, and enable the stable production of thin-walled molded articles with good molding appearance over long periods of time, thereby completing the present invention.

That is, the present invention is as follows.
[1]
The present invention comprises a polyphenylene ether (A), a styrene-based resin (B) (excluding the block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block) , a block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block, and a terpene-phenol resin (D) having a softening point (measured by a ring and ball method) of 155° C. or higher,
the content of the (A) component is 35 to 75 parts by mass, the content of the (B) component is 5 to 50 parts by mass, the content of the (C) component is 1 to 20 parts by mass, and the content of the (D) component is 0.5 to 15 parts by mass, relative to 100 parts by mass in total of the (A), (B), (C), and (D) components;
A polyphenylene ether resin composition, characterized in that the total content of the components (A), (B), (C), and (D) is 90 mass% or more of the entire polyphenylene ether resin composition .
[2]
The polyphenylene ether resin composition according to [1], further comprising 0.05 to 3 parts by mass of a heat stabilizer (E) having a melting point of 200° C. or higher, per 100 parts by mass of the total amount of the components (A), (B), (C), and (D).
[3]
The polyphenylene ether resin composition according to [1] or [2], wherein the component (C) contains a copolymer (Ca) of a styrene block having a bound styrene content of 55 mass% or more and a hydrogenated conjugated diene compound block.
[4]
The polyphenylene ether resin composition according to [3], further comprising a polyolefin resin (F), and a mass ratio ((Ca)/(F)) of the component (Ca) to the component (F) is within a range of 9/1 to 6/4.
[5 ]
[4] The polyphenylene ether-based resin composition according to any one of [1] to [4], wherein when the polyamide -based resin and/or the polyolefin-based resin (F) is contained, the total content of the polyamide-based resin and the polyolefin-based resin ( F ) in the polyphenylene ether-based resin composition is 8 mass% or less.

The present invention provides a polyphenylene ether resin composition that has an excellent balance between molding flowability and heat resistance, and that significantly suppresses the occurrence of silver streaks during molding, making it possible to obtain molded products that can be used as thin-walled molded articles with excellent appearance without painting.

The following describes in detail the embodiment of the present invention (hereinafter, "the present embodiment"). Note that the present invention is not limited to the following embodiment, and can be modified in various ways within the scope of the gist of the invention.

<Polyphenylene ether resin composition>
The polyphenylene ether-based resin composition of the present embodiment (hereinafter, also simply referred to as "resin composition") contains polyphenylene ether (A), a styrene-based resin (B), a block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block (hydrogenated conjugated diene compound block), and a terpene-phenol resin (D) having a softening point (measured by a ring and ball method) of 155°C or higher, and the content of the (A) component is 35 to 75 parts by mass, the content of the (B) component is 5 to 50 parts by mass, the content of the (C) component is 1 to 20 parts by mass, and the content of the (D) component is 0.5 to 15 parts by mass, relative to 100 parts by mass of the total amount of the (A), (B), (C), and (D) components.
The present inventors have discovered that the above-mentioned resin composition is a polyphenylene ether-based resin composition which has an excellent balance between molding fluidity and heat resistance, and in which the occurrence of silver streaks during molding is significantly suppressed, and which can be used as an unpainted, thin-walled molded article with excellent appearance, and have also discovered that the composition is fully applicable to decorative molded parts used in home electrical and office equipment parts, such as projectors and various lighting fixtures, and electric and electronic equipment, automotive applications, etc.
Each of the components of the resin composition will now be described in detail.

・・・（１）〔ａ〕

・・・（１）〔ｂ〕
上記式（１）〔ａ〕、〔ｂ〕中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５及びＲ_６は、それぞれ独立して、炭素数１～４のアルキル基、炭素数６～１２のアリール基、並びにハロゲン原子及び水素原子からなる群から選ばれる一価の残基であることが好ましい。
但し、かかる場合、Ｒ_５及びＲ_６が同時に水素である場合を除く。
また、前記アルキル基のより好ましい炭素数は１～３であり、前記アリール基のより好ましい炭素数は６～８であり、前記一価の残基の中でもより好ましくは水素である。
尚、上記（１）の〔ａ〕及び〔ｂ〕における繰り返し単位の数については、ポリフェニレンエーテル（Ａ）の分子量分布により様々であるため、特に制限されることはない。 <Polyphenylene ether (A)>
The polyphenylene ether (A) is preferably a homopolymer or copolymer having repeating units represented by [a] and/or [b] of the following general formula (1):

... (1) [a]

... (1) [b]
In the above formula (1) [a] and [b], R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are preferably each independently a monovalent residue selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom and a hydrogen atom.
However, in this case, the case where R ₅ and R ₆ are simultaneously hydrogen is excluded.
The alkyl group more preferably has 1 to 3 carbon atoms, the aryl group more preferably has 6 to 8 carbon atoms, and among the monovalent residues, hydrogen is more preferred.
The number of repeating units in [a] and [b] of the above (1) is not particularly limited since it varies depending on the molecular weight distribution of the polyphenylene ether (A).

Examples of polyphenylene ether homopolymers include, but are not limited to, poly(2,6-dimethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-ethyl-6-n-propyl-1,4-phenylene) ether, poly(2,6-di-n-propyl-1,4-phenylene) ether, poly(2-methyl-6-n-butyl-1,4-phenylene) ether, poly(2-ethyl-6-isopropyl-1,4-phenylene) ether, poly(2-methyl-6-chloroethyl-1,4-phenylene) ether, poly(2-methyl-6-hydroxyethyl-1,4-phenylene) ether, and poly(2-methyl-6-chloroethyl-1,4-phenylene) ether.

In addition, examples of polyphenylene ether copolymers include, but are not limited to, copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol, copolymers of 2,6-dimethylphenol and o-cresol, and copolymers of 2,3,6-trimethylphenol and o-cresol, which are primarily composed of a polyphenylene ether structure.

Among polyphenylene ethers, it is preferable to use poly(2,6-dimethyl-1,4-phenylene) ether.

The polyphenylene ether (A) may be used alone or in combination of two or more kinds.

The polyphenylene ether (A) may contain various phenylene ether units other than [a] and [b] in the formula (1) as partial structures.
Examples of such phenylene ether units include, but are not limited to, 2-(dialkylaminomethyl)-6-methylphenylene ether units and 2-(N-alkyl-N-phenylaminomethyl)-6-methylphenylene ether units described in JP-A-01-297428 and JP-A-63-301222.

The polyphenylene ether (A) may contain structural units other than the phenylene ether units in the main chain.
Such a structural unit may be, for example, a unit derived from diphenoquinone. However, the structural unit other than the phenylene ether unit contained in the main chain is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less, based on 100% by mass of the polyphenylene ether (A).

Furthermore, the polyphenylene ether (A) may be a functionalized polyphenylene ether obtained by reacting (modifying) a part or all of the polyphenylene ether with a functionalizing agent containing one or more selected from the group consisting of carboxylic acid, acid anhydride, acid amide, imide, amine, orthoester, hydroxy, and ammonium carboxylate.

The reduced viscosity of the polyphenylene ether (A) used in the present embodiment is preferably in the range of 0.25 to 0.60 dL/g, more preferably 0.30 to 0.55 dL/g, and even more preferably 0.35 to 0.50 dL/g. From the viewpoint of sufficient mechanical properties, it is preferably 0.25 dL/g or more, and from the viewpoints of moldability and brilliance of the molded product, it is preferably 0.55 dL/g or less.
The reduced viscosity in the present embodiment is a value obtained by measurement using a chloroform solvent, a concentration of 0.50 g/dL, and at 30° C. using an Ubbelohde viscometer.

The ratio of weight average molecular weight Mw to number average molecular weight Mn (Mw/Mn value) of the polyphenylene ether (A) used in the present embodiment before heat processing (polymerized powder property) by extrusion or the like is preferably 1.2 to 3.0, more preferably 1.5 to 2.5, and even more preferably 1.8 to 2.3. The Mw/Mn value is preferably 1.2 or more from the viewpoint of moldability of the resin composition, and is preferably 3.0 or less from the viewpoint of mechanical properties of the resin composition, particularly tensile strength retention.
The weight average molecular weight Mw and the number average molecular weight Mn are obtained from the polystyrene equivalent molecular weight measured by GPC (gel permeation chromatography).

In the polyphenylene ether resin composition of this embodiment, the content of polyphenylene ether (A) is within the range of 35 to 75 parts by mass per 100 parts by mass of the total amount of components (A), (B), (C), and (D) in the resin composition. The content is preferably 40 to 75 parts by mass, more preferably 50 to 70 parts by mass, and even more preferably 55 to 70 parts by mass. From the viewpoint of sufficient heat resistance, it is essential that the content is 35 parts by mass or more, and from the viewpoint of maintaining the molded appearance during molding, it is essential that the content is 75 parts by mass or less.

<Styrene-based resin (B)>
In the resin composition of the present embodiment, a styrene-based resin (B) can be blended mainly for the purpose of improving molding flowability.
In the present embodiment, the styrene-based resin (B) refers to a homopolymer of a styrene-based compound, or a copolymer of a styrene-based compound and a compound copolymerizable with the styrene-based compound (excluding conjugated diene compounds). This (B) component does not include those included in the category of the (C) component described below.
Specific examples of the styrene-based resin (B) include styrene, α-methylstyrene, 2,4-dimethylstyrene, monochlorostyrene, p-methylstyrene, p-tert-butylstyrene, and ethylstyrene.

Compounds that can be copolymerized with styrene-based compounds include methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; and acid anhydrides such as maleic anhydride.

The styrene-based resin (B) can be obtained by polymerizing a styrene-based compound, or a styrene-based compound and a compound copolymerizable with a styrene-based compound, in the presence or absence of a rubber polymer.
Examples of the rubbery polymer include conjugated diene rubber, copolymers of conjugated diene and aromatic vinyl compound, hydrogenated products thereof, and ethylene-propylene copolymer rubber.

In this embodiment, the styrene-based resin (B) is preferably polystyrene or high-impact polystyrene reinforced with a rubber polymer, and more preferably polystyrene.

The content of the styrene-based resin (B) in the resin composition of this embodiment is within the range of 5 to 50 parts by mass, based on 100 parts by mass of the total amount of the components (A), (B), (C), and (D) in the resin composition. It is preferably within the range of 10 to 40 parts by mass, more preferably within the range of 15 to 30 parts by mass, and particularly preferably 15 to 25 parts by mass. From the viewpoint of imparting sufficient molding fluidity, it is essential to contain 5 parts by mass or more, and from the viewpoint of maintaining sufficient heat resistance, it is essential to contain 50 parts by mass or less.

<Block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block>
The resin composition of the present embodiment, which contains the above-mentioned polyphenylene ether (A) and styrene-based resin (B), contains a block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block from the viewpoint of improving impact resistance (hereinafter, this may be referred to as a "block copolymer of a styrene block and a hydrogenated conjugated diene compound block" or a "styrene block-hydrogenated conjugated diene compound block copolymer").

From the viewpoint of thermal stability, the conjugated diene compound block preferably has a hydrogenation rate of 50% or more, more preferably 80% or more, and even more preferably 95% or more.

The conjugated diene compound block may be, but is not limited to, polybutadiene, polyisoprene, poly(ethylene-butylene), poly(ethylene-propylene), vinyl-polyisoprene, etc. The conjugated diene compound block may be used alone or in combination of two or more.

The arrangement of the repeating units constituting the block copolymer may be of either a linear type or a radial type.
The block structure composed of the polystyrene block and the rubber intermediate block may be any of type 2, type 3, and type 4. Among them, from the viewpoint of being able to fully exert the desired effects of the present embodiment, a type 3 linear type block copolymer (SEBS) composed of a polystyrene-poly(ethylene butylene)-polystyrene structure is preferred.
From the viewpoint of imparting impact resistance, the conjugated diene compound block may contain butadiene units in an amount not exceeding 30% by mass.

From the viewpoint of improving impact resistance, the weight average molecular weight Mw of the (C) component is preferably in the range of 40,000 to 300,000, more preferably 50,000 to 280,000, and even more preferably 80,000 to 250,000. From the viewpoint of imparting sufficient impact resistance, it is preferably 40,000 or more, and from the viewpoints of flowability, appearance retention, and miscibility of the molded product, it is preferably 300,000 or less.

The bound styrene content of the styrene block-hydrogenated conjugated diene compound block copolymer is preferably in the range of 20 to 80% by mass, more preferably 50 to 70% by mass, and even more preferably 55 to 75% by mass. From the viewpoint of miscibility, the bound styrene content is preferably 20% by mass or more, and from the viewpoint of imparting impact resistance, it is preferably 80% or less.

From the viewpoints of improving miscibility with resins and improving molding flowability, the component (C) more preferably contains an oil-extended styrene block-hydrogenated conjugated diene compound block copolymer.
Specifically, the oil component is preferably contained in an amount of 5 to 100 parts by mass per 100 parts by mass of the styrene block-hydrogenated conjugated diene compound block copolymer (C), more preferably 10 to 75 parts by mass, and even more preferably 20 to 50 parts by mass.
From the viewpoint of dispersibility of the component (C) in the resin component, the content of the oil component per 100 parts by mass of the styrene block-hydrogenated conjugated diene compound block copolymer (C) is preferably 5 parts by mass or more, and from the viewpoints of heat resistance and prevention of oil bleeding onto the surface of the molded article, the content of the oil component is preferably 100 parts by mass or less.
Here, examples of the oil component include oils generally used as rubber softeners, such as paraffinic, naphthenic, and aromatic process oils, mineral oils such as liquid paraffin, and castor oil. These oil components may be used alone or in combination of two or more. In addition, the oil components may be incorporated in the styrene block-hydrogenated conjugated diene compound block copolymer in advance during production of the copolymer, or may be added during melt-kneading of the styrene block-hydrogenated conjugated diene compound block copolymer using an extruder or the like.

When a high molecular weight type (Mw: 200,000 to 300,000) styrene block-hydrogenated conjugated diene compound block copolymer is used as component (C), its miscibility in the resin composition is insufficient when used alone, and layer delamination may occur in the molded product. For this reason, it is preferable to use in combination a medium molecular weight type (Mw: 50,000 to 150,000) styrene block-hydrogenated conjugated diene compound block copolymer having a bound styrene content of 55 to 80 mass% or an oil-extended styrene block-hydrogenated conjugated diene compound block copolymer.
The mass ratio of the medium molecular weight type and/or oil-extended type styrene block-hydrogenated conjugated diene compound block copolymer having a bound styrene content of 55 to 80% by mass to the high molecular weight type styrene block-hydrogenated conjugated diene compound block copolymer (medium molecular weight type and/or oil-extended type styrene block-hydrogenated conjugated diene compound block copolymer having a bound styrene content of 50 to 80% by mass/high molecular weight type styrene block-hydrogenated conjugated diene compound block copolymer) is preferably in the range of 9/1 to 3/7, more preferably in the range of 7/3 to 5/5.

From the viewpoint of improving impact resistance, it is preferable that component (C) contains a block copolymer (C-a) of a styrene block having a bound styrene content of 55% by mass or more and a hydrogenated conjugated diene compound block. In addition to component (C-a), the resin composition of this embodiment can also contain a polyolefin resin (F) described below as an elastomer component other than component (C).

The content of component (C) in the resin composition of this embodiment is within the range of 1 to 20 parts by mass, based on 100 parts by mass of the total amount of components (A), (B), (C), and (D) in the resin composition. It is preferably within the range of 3 to 20 parts by mass, and more preferably within the range of 5 to 15 parts by mass. The content of component (C) is set to 1 part by mass or more from the viewpoint of obtaining impact resistance, and 20 parts by mass or less from the viewpoint of heat resistance and maintaining rigidity.

<Terpene-phenol resin (D)>
The resin composition of the present embodiment containing the above-mentioned polyphenylene ether (A) and styrene-based resin (B) contains a terpene-phenol resin (D) from the viewpoint of improving molding flowability without decreasing the heat resistance, mechanical strength, impact resistance, and the like of the molded article.

The terpene-phenol resin (D) contained in the resin composition of this embodiment is a terpene-phenol resin with a softening point (measured by the ring and ball method) of 155°C or higher from the viewpoints of suppressing the occurrence of silver streaks on the surface of molded products during high-temperature molding, and maintaining heat resistance, mechanical strength, impact resistance, etc.

The terpene-phenol resin is a copolymer of a terpene and a phenol, and is itself publicly known.
Terpenes are hydrocarbons represented by ( _C5H6 ) _n or oxygen _- containing compounds derived therefrom, such as monoterpenes (when n=2, myrcene, ocimene, pinene, limonene, citronellol, borneol, menthol, camphor, etc.), sesquiterpenes (when n=3, curcumene, etc.), diterpenes (when n=4, campholene, hinokiol, etc.), tetraterpenes (when n=8, carotenoids, etc.), polyterpenes (natural rubber), etc. Preferred terpenes are monoterpenes, and pinene, limonene, etc. are particularly preferred.
Phenols are compounds having at least one hydroxyl group on an aromatic ring such as a benzene ring or a naphthalene ring, and the aromatic ring may have a substituent (e.g., a halogen atom, an alkyl group, etc.). Examples of phenols include phenol, cresol, xylenol, naphthol, catechol, resilicin, hydroquinone, pyrogallol, etc. A preferred phenol is phenol.
A preferred terpene-phenol resin is a copolymer of a monoterpene and phenol, and more preferably a copolymer of a monoterpene such as α-pinene or limonene and phenol.

The softening point of the terpene-phenol resin used in the resin composition of the present embodiment is 155° C. or higher, preferably 155 to 180° C., and more preferably 160 to 170° C., from the viewpoints of suppressing silver streaks in a molded product and maintaining heat resistance, mechanical strength, impact resistance, and the like.
In this disclosure, the softening point refers to a value measured based on the softening point measurement method (ring and ball method) specified in JIS K5902 and JIS K2207.
Regarding the softening point measurement method (ring and ball method), specifically, the sample is melted as quickly as possible at a low temperature and filled into a ring (annular mold) placed on a flat metal plate, taking care not to create bubbles. After cooling, the part that rises from the flat surface including the top end of the ring is cut off with a slightly heated knife. Next, a holder (ring stand) is placed in a glass container (heating bath) with a diameter of 85 mm or more and a height of 127 mm or more, and glycerin is poured to a depth of 90 mm or more. Next, a steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in glycerin without touching each other, and the temperature of the glycerin is maintained at 20°C ± 5°C for 15 minutes. Next, the steel ball is placed on the center of the surface of the sample in the ring, and this is placed in a fixed position on the holder. Next, the distance from the top end of the ring to the glycerin surface is kept 50 mm, a thermometer is placed, the center of the thermometer's mercury ball is positioned at the same height as the center of the ring, and the container is heated. The flame of the Bunsen burner used for heating is placed halfway between the center of the bottom of the container and the edge to ensure uniform heating. After the start of heating and the temperature of the bath reaches 40°C, the rate of increase is 5.0±0.5°C per minute. The sample gradually softens and flows down the ring, and the temperature is read when it finally touches the bottom plate of the container, and this is the softening point. The softening point is measured on two or more samples at the same time, and the average value is used.

The content of the terpene-phenol resin (D) in the resin composition of this embodiment is within the range of 0.5 to 15 parts by mass, preferably 1 to 15 parts by mass, and more preferably 3 to 13 parts by mass, per 100 parts by mass of the total amount of the (A), (B), (C), and (D) components in the resin composition.
From the viewpoint of improving the molding flowability of the resin composition, it is essential that the content is 0.5 parts by mass or more, and from the viewpoint of maintaining sufficient mechanical properties and thermal stability of the resin composition, it is essential that the content is 15 parts by mass or less.

<Heat stabilizer (E)>
The resin composition of the present embodiment preferably contains 0.05 to 3 parts by mass of a heat stabilizer (E) having a melting point of 200° C. or higher per 100 parts by mass of the total amount of the above components (A), (B), (C), and (D).
The resin composition of the present embodiment containing the above-mentioned polyphenylene ether (A) and styrene-based resin (B) preferably contains a heat stabilizer (E) from the viewpoint of improving thermal stability mainly during molding processing, and the heat stabilizer (E) preferably has a melting point of 200° C. or higher from the viewpoint of suppressing the occurrence of silver streaks on the surface of a molded article, particularly during high-temperature molding.

Examples of the heat stabilizer (E) having a melting point of 200° C. or higher include hindered phenol-based heat stabilizers and phosphorus-based heat stabilizers.
Specific examples of the hindered phenol-based heat stabilizer include 3,3',3'',5,5',5''-hexa-tert-butyl-a,a'',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and the like.
Specific examples of phosphorus-based heat stabilizers include 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, and the like.

From the viewpoint of improving the appearance of the molded article (suppressing the occurrence of silver streaks), it is essential that the heat stabilizer (E) used in this embodiment is a heat stabilizer having a melting point of 200° C. or higher. The melting point of component (E) is preferably within the range of 200 to 280° C., more preferably within the range of 210 to 270° C., and even more preferably within the range of 220 to 260° C.
In the present embodiment, the melting point of the component (E) can be measured, for example, using a melting point measuring device (Model: B-545, manufactured by Shibata Scientific Co., Ltd.).

The content of the heat stabilizer (E) having a melting point of 200°C or higher in the resin composition of this embodiment is preferably selected from within the range of 0.05 to 3 parts by mass per 100 parts by mass of the total amount of components (A), (B), (C), and (D) in the resin composition, from the viewpoint of improving the appearance of the molded product (suppressing the occurrence of silver streaks). It is more preferably within the range of 0.1 to 2 parts by mass, and even more preferably within the range of 0.5 to 1 part by mass.

<Polyolefin Resin (F)>
The resin composition of the present embodiment may contain a polyolefin resin (F). Examples of the polyolefin resin (F) include, but are not limited to, polyethylene, polypropylene, ethylene-α-olefin copolymers such as ethylene-propylene copolymers and ethylene-octene copolymers, and ethylene-alkyl (meth)acrylate copolymers such as ethylene-methyl acrylate, ethylene-ethyl acrylate, ethylene-methyl methacrylate, and ethylene-ethyl methacrylate.

When the ethylene-based copolymer is used as the polyolefin-based resin, the mass ratio of the ethylene component to the component copolymerizable with ethylene in the ethylene-based copolymer (ethylene component/component copolymerizable with ethylene) is preferably in the range of 60/40 to 95/5, more preferably 65/35 to 90/10, and even more preferably 70/30 to 85/15, from the viewpoint of improving miscibility with the styrene block-conjugated diene compound block copolymer, heat resistance, mechanical properties, and the like.

When the polyolefin resin (F) is blended alone in the resin composition of this embodiment, it does not have sufficient miscibility in the resin composition, and there is a risk of layer delamination occurring in the molded product. Therefore, it is preferable to blend it in combination with the styrene block-hydrogenated conjugated diene compound block copolymer (C-a) having a bound styrene content of 55% by mass or more.

The content of polyolefin resin (F) is preferably small from the viewpoint of maintaining physical properties, and the mass ratio of the (Ca) component to the (F) component ((Ca)/(F)) is preferably within the range of 9/1 to 6/4, and more preferably within the range of 8/2 to 7/3.

<Other additives>
The resin composition of the present embodiment may further contain other additives such as antioxidants, lubricants, release agents, colorants, etc., within the range that does not significantly deteriorate the heat resistance, mechanical properties, and surface appearance of the molded product of the resin composition.
When the other additives are contained, each of them is preferably contained in the range of 0.001 to 3 mass%, more preferably 0.01 to 2 mass%, and even more preferably 0.05 to 1 mass%, based on 100 mass% of the resin composition. From the viewpoint of sufficient addition effect, the other additives are preferably contained in an amount of 0.001 mass% or more, and from the viewpoint of sufficient retention of the appearance and physical properties of the molded product, the amount is preferably 3 mass% or less.

The resin composition of the present embodiment may contain a small amount of a polyamide resin.
The polyamide resin is not particularly limited, but examples thereof include polyamide 6, polyamide 6,6, polyamide 4,6, polyamide 11, polyamide 12, polyamide 6,10, polyamide 6,12, polyamide 6/6,6, polyamide 6/6,12, polyamide MXD (m-xylylenediamine),6, polyamide 6,T, polyamide 9,T, polyamide 6,I, polyamide 6/6,T, polyamide 6/6,I, polyamide 6,6/6,T, polyamide 6,6/6,I, polyamide 6/6,T/6,I, polyamide 6,6/6,T/6,I, polyamide 6/12/6,T, polyamide 6,6/12/6,T, polyamide 6/12/6,I, and polyamide 6,6/12/6,I.
In the resin composition of the present embodiment, when the resin composition contains a polyamide-based resin and/or a polyolefin-based resin (F), from the viewpoint of maintaining sufficient appearance and physical properties of a molded product, the total content of the polyamide-based resin and the polyolefin-based resin (F) in 100% by mass of the resin composition (when only one of the polyamide-based resin or the polyolefin-based resin (F) is contained, the content of only either one) is preferably 8% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less.

In the resin composition of this embodiment, from the viewpoint of maintaining sufficient molded product appearance and physical properties, the total content of the above components (A), (B), (C), and (D) is preferably 90% by mass or more of the entire resin composition. More preferably, it is 92% by mass or more, even more preferably 95% by mass or more, and particularly preferably 97% by mass or more.

[Method of producing resin composition]
The resin composition of the present embodiment can be produced by melt-kneading raw materials such as the above-mentioned (A), (B), (C), and (D) components, and, if necessary, the (E) component and/or other additives, while appropriately adjusting the melt-kneading conditions.
The conditions for melt-kneading the (A), (B), (C), and (D) components, and the (E) component and/or other additives to produce the resin composition are not particularly limited in the resin composition, but from the viewpoint of obtaining a large amount of a resin composition that can fully exert the desired effects of the present embodiment in a stable manner, it is preferable to use a twin-screw extruder with a screw diameter of 25 to 90 mm. As an example, when using a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53); kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern), a method of melt-kneading under conditions of a cylinder temperature of 270 to 330 ° C., a screw rotation speed of 150 to 700 rpm, an extrusion rate of 150 to 700 kg/h, and a vent vacuum degree of 11.0 to 1.0 kPa can be mentioned.

From the viewpoint of sufficient expression of the effects required for the present application and extrudability, the extrusion temperature is preferably in the range of 280 to 360°C. A more preferred range for the extrusion temperature is 290 to 350°C, and an even more preferred range is 300 to 340°C. From the viewpoint of sufficient miscibility of the resin composition, a temperature of 280°C or higher is preferable, and from the viewpoint of preventing thermal degradation of the resin, a temperature of 360°C or lower is preferable.

When the polyphenylene ether resin composition of the present embodiment is produced using a large twin-screw extruder (screw diameter 40 to 90 mm), attention should be paid to the fact that gels and chars produced from the component (A) during extrusion may be mixed into the extruded resin pellets, which may cause deterioration in the surface appearance, impact resistance, and toughness of the molded product. Therefore, it is preferable to feed the component (A) from the most upstream raw material inlet (top feed), and set the oxygen concentration inside the shooter at the most upstream inlet to 8% by volume or less, more preferably 5% by volume or less, and even more preferably 1% by volume or less.
The oxygen concentration can be adjusted by thoroughly replacing the inside of the raw material storage hopper with nitrogen, sealing the feed line from the raw material storage hopper to the raw material inlet of the extruder so that no air can enter or leave the line, and then adjusting the amount of nitrogen fed and the opening of the gas vent.

[Molding]
A molded article made of the resin composition of the present embodiment can be obtained by molding the above-mentioned resin composition.
The average molding thickness of a molded article made of the polyphenylene ether resin composition of the present embodiment is preferably within a range of 0.5 to 2.5 mm, more preferably within a range of 0.7 to 2.2 mm, and even more preferably within a range of 1.0 to 2.0 mm.
From the viewpoint of maintaining sufficient strength of the molded article, the thickness is preferably 0.5 mm or more, and from the viewpoint of maintaining the light weight of the molded article, the thickness is preferably 2.5 mm or less.

The method for molding the resin composition is not limited to the following, but suitable examples include injection molding, extrusion molding, vacuum molding, and pressure molding. In particular, from the viewpoint of mass productivity, injection molding is more preferably used.
The molding temperature during molding of the resin composition is preferably within the range of the barrel maximum setting temperature of 280 to 340° C., more preferably 300 to 330° C., and even more preferably 300 to 320° C. From the viewpoint of sufficient molding processability, the molding temperature is preferably 280° C. or higher, and from the viewpoint of suppressing thermal degradation of the resin, it is preferably 340° C. or lower.
The mold temperature during molding of the resin composition is preferably within the range of 40 to 160°C, more preferably 80 to 150°C, and even more preferably 80 to 130°C, from the viewpoint of maintaining sufficient appearance of the molded product.

Suitable molded products in this embodiment include decorative molded parts used in home appliances and office automation equipment parts, electrical and electronic equipment, automotive applications, and various industrial products, because deterioration of molded appearance caused by the generation of silver streaks that occurs during molding under high temperature and high shear conditions is significantly suppressed and the product can be used as a molded product with high appearance without painting.

The present embodiment will be described in more detail below with reference to examples and comparative examples, but the present embodiment is not limited to these examples. The methods for measuring physical properties and raw materials used in the examples and comparative examples are shown below.

[Preparation of Molded Pieces and Measurement of Physical Properties]
1. Preparation of molded pieces Pellets of the resin compositions obtained in the following examples and comparative examples were dried in a hot air dryer at 100°C for 2 hours, and then molded into ISO3167, multipurpose test piece type A dumbbell molded pieces using an injection molding machine (IS-100EPN, manufactured by Toshiba Machine Co., Ltd.) equipped with an ISO physical property test piece mold, with the cylinder temperature set to 300°C, mold temperature to 80°C, injection pressure to 50 MPa (gauge pressure), injection speed to 200 mm/sec, and injection time/cooling time to 20 sec/20 sec.

2. Heat resistance (DTUL)
The dumbbell-shaped multipurpose test piece A obtained in the above 1 was cut to prepare three molded pieces of 80 mm x 10 mm x 4 mm. Using the test pieces, a flatwise method was performed in accordance with ISO 75. The deflection temperature under load (DTUL) (°C) was measured at 1.82 MPa.
The evaluation criteria were such that the higher the measured value (average value of three samples), the better the heat resistance.

3. Molding flow rate (MFR)
Pellets of the resin compositions obtained in the following Examples and Comparative Examples were dried in a hot air dryer at 100°C for 2 hours, and then subjected to melt indexing in accordance with ISO 1133 using a melt indexer (P-111, manufactured by Toyo Seiki Co., Ltd.). In Examples 5 to 9 and Comparative Examples 2 to 8, the melt flow rate (MFR) was measured at a set temperature of 250° C. and a load of 10 kg, and in Examples 1 to 4, Comparative Example 1, and Comparative Example 9, the melt flow rate (MFR) was measured at a set temperature of 280° C. and a load of 10 kg. ) (g/10 min) was measured.
As an evaluation criterion, the higher the MFR value, the more excellent the molding flowability was judged to be.
In addition, it was determined that the higher the DTUL value and the higher the MFR value, the better the balance between heat resistance and molding flowability, and the more advantageous it is in terms of material design.

4. Rigidity (flexural strength, flexural modulus)
The dumbbell-shaped multipurpose test piece A obtained in 1 above was cut to prepare three molded pieces of 80 mm x 10 mm x 4 mm. The flexural strength (MPa) and flexural modulus (MPa) of the test pieces were measured at 23°C in accordance with ISO178.
As an evaluation criterion, the higher the measured values of bending strength and bending modulus (average values of three pieces measured), the more excellent the rigidity was judged to be.

5. Impact resistance (Charpy impact strength)
The multipurpose A-type dumbbell molded specimen obtained in 1 above was cut to prepare five molded specimens measuring 80 mm x 10 mm x 4 mm. Using the test specimens, the Charpy impact strength (notched) (kJ/ ^m2 ) was measured at 23°C in accordance with ISO179.
The evaluation criteria were that the higher the measured value (average value of five samples), the better the impact resistance.

6. Retention molding stability (visual inspection of silver streaks)
Pellets of the resin compositions obtained in the following Examples and Comparative Examples were dried in a hot air dryer at 100°C for 2 hours, and then an injection molding machine (IS-100EPN, manufactured by Toshiba Machine Co., Ltd.) equipped with an ISO physical property test piece mold was used to fill the cylinder with the resin composition at a cylinder set temperature of 300°C and retain it for 30 minutes. After that, one shot of the resin composition inside the cylinder was injected, and continuous molding (30 shots) of ISO3167 multipurpose test piece A type dumbbell molded pieces was performed under the above condition 1.
Molded pieces in which no silver streaks were observed from the first or second shot were rated as "◎", molded pieces in which no silver streaks were observed from the third to fifth shot onwards were rated as "◯", molded pieces in which no silver streaks were observed from the sixth to tenth shot onwards were rated as "△", and molded pieces in which silver streaks were observed even from the tenth shot onwards were rated as "×". As evaluation criteria, ◎ and ◯ were judged to be excellent in retention molding stability, and ◎ was judged to be particularly preferable as the resin composition of the present invention.

[raw materials]
<Polyphenylene ether (A)>
(A-1)
Poly(2,6-dimethyl-1,4-phenylene ether) (hereinafter sometimes referred to as "(A-1)") having a reduced viscosity of 0.40 dL/g (0.5 g/dL chloroform solution, 30° C., measured with an Ubbelohde viscometer) was used.
(A-2)
Poly(2,6-dimethyl-1,4-phenylene ether) (hereinafter sometimes referred to as "(A-2)") having a reduced viscosity of 0.30 dL/g (0.5 g/dL chloroform solution, 30° C., measured with an Ubbelohde viscometer) was used.

<Styrene-based resin (B)>
(B-1)
General purpose polystyrene (GPPS) (product name: Polystyrene 680 (registered trademark), manufactured by PS Japan Co., Ltd.; hereinafter, also referred to as "(B-1)") was used.
(B-2)
High impact polystyrene (HIPS) (product name: Polystyrene H9405 (registered trademark), manufactured by PS Japan Co., Ltd.; hereinafter, sometimes referred to as "(B-2)") was used.

<Styrene Block-Hydrogenated Conjugated Diene Compound Block Copolymer (C)>
(C-1)
Oil-extended SEBS (product name: Tuftec H1272 (registered trademark), manufactured by Asahi Kasei Corporation; hereinafter, sometimes referred to as "(C-1)") was used.
(C-a)
A type 3 hydrogenated block copolymer (hereinafter sometimes referred to as "(C-a)") having a bound styrene content of 67% by mass and a hydrogenation rate of the polybutadiene block portion of 98%, and having a polystyrene block-hydrogenated polybutadiene block-polystyrene block structure, was used.

<Terpene-phenol resin (D)>
(D-1)
A terpene-phenol resin having a softening point (measured by the ring and ball method) of 160° C. (product name: YS Polystar T160 (registered trademark), manufactured by Yasuhara Chemical Co., Ltd.; hereinafter, also referred to as “(D-1)”) was used.

<Terpene/phenol resin>
(D'-1)
A terpene-phenol resin having a softening point (measured by the ring and ball method) of 145° C. (product name: YS Polystar T145 (registered trademark), manufactured by Yasuhara Chemical Co., Ltd.; hereinafter, also referred to as “(D′-1)”) was used.
(D'-2)
A terpene-phenol resin having a softening point (measured by the ring and ball method) of 130° C. (product name: YS Polystar T130 (registered trademark), manufactured by Yasuhara Chemical Co., Ltd.; hereinafter, sometimes referred to as “(D′-2)”) was used.

<Aromatic petroleum resin>
An aromatic petroleum resin having a softening point (measured by the ring and ball method) of 165° C. (product name: Nippon Oil Neopolymer 160 (registered trademark), manufactured by JXTG Nippon Oil & Energy Corporation; hereinafter, sometimes simply referred to as “aromatic petroleum resin”) was used.

<Heat stabilizer (E)>
(E-1)
A hindered phenol-based heat stabilizer having a melting point of 242°C (chemical name: 3,3',3'',5,5',5''-hexa-tert-butyl-a,a'',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, product name: Irganox 1330 (registered trademark), manufactured by BASF Corporation; hereinafter, sometimes referred to as "(E-1)") was used.
(E-2)
A phosphorus-based heat stabilizer having a melting point of 225° C. (chemical name: bis(2,4-dicumylphenyl)pentaerythritol diphosphite, product name: DoverPhos S-9228 (registered trademark), manufactured by Dover Chemical Co., hereinafter sometimes referred to as “(E-2)”) was used.

<Polyolefin Resin (F)>
(F-1)
An ethylene-octene copolymer (product name: Engage 8180 (registered trademark), manufactured by DuPont Dow Elastomers; hereinafter, sometimes referred to as "(F-1)") was used.
(F-2)
LDPE (product name: Suntech LD M2004 (registered trademark), manufactured by Asahi Kasei Corporation; hereinafter, also referred to as "(F-2)") was used.

[Comparative Example 1]
74 parts by mass of (A-1), 21 parts by mass of (B-1), 5 parts by mass of (C-a), and 2 parts by mass of (F-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) and melt-kneaded under the conditions of a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 1]
The mixture was melt-kneaded under the same conditions as in the extrusion of Comparative Example 1, except that 10 parts by mass of the 21 parts by mass of (B-1) was replaced with (D-1), to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 2]
74 parts by mass of (A-1), 11 parts by mass of (B-1), 5 parts by mass of (C-a), 10 parts by mass of (D-1), 0.5 parts by mass of (E-1), and 2 parts by mass of (F-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300 ° C., a screw rotation speed of 450 rpm, an extrusion rate of 400 kg / hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 3]
74 parts by mass of (A-1), 11 parts by mass of (B-1), 5 parts by mass of (B-2), 5 parts by mass of (C-a), 5 parts by mass of (D-1), 0.5 parts by mass of (E-1), and 2 parts by mass of (F-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300 ° C., a screw rotation speed of 450 rpm, an extrusion rate of 400 kg / hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.
[Example 4]
The resin composition was melt-kneaded under the same conditions as in Example 3, except that 0.5 parts by mass of (E-1) was replaced with (E-2), to obtain pellets of the resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 2]
29 parts by mass of (A-1), 29 parts by mass of (A-2), 15 parts by mass of (B-1), 20 parts by mass of (B-2), and 7 parts by mass of (C-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 3]
29 parts by mass of (A-1), 29 parts by mass of (A-2), 28 parts by mass of (B-2), and 14 parts by mass of (D-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 5]
29 parts by mass of (A-1), 29 parts by mass of (A-2), 21 parts by mass of (B-2), 7 parts by mass of (C-1), and 14 parts by mass of (D-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 6]
29 parts by mass of (A-1), 29 parts by mass of (A-2), 21 parts by mass of (B-2), 7 parts by mass of (C-1), 14 parts by mass of (D-1), and 1 part by mass of (E-2) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 4]
The resin composition was melt-kneaded under the same extrusion conditions as in Example 6, except that 14 parts by mass of (D-1) was replaced with (D'-1), to obtain pellets of the resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 5]
The resin composition was melt-kneaded under the same extrusion conditions as in Example 6, except that 14 parts by mass of (D-1) was replaced with (D'-2), to obtain pellets of the resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 6]
The resin composition was melt-kneaded under the same conditions as in Example 6, except that 14 parts by mass of (D-1) was changed to an aromatic petroleum resin, to obtain pellets of the resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 7]
The 7 parts by mass of (C-1) was changed to 7 parts by mass of (Ca), and 1 part by mass of (F-1) was further added. Except for this, the mixture was melt-kneaded under the same conditions as in the extrusion of Example 6 to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 8]
Melt kneading was carried out under the same conditions as in the extrusion of Example 7, except that 1 part by mass of (F-1) was changed to 1 part by mass of (F-2), to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 7]
40 parts by mass of (A-1), 12 parts by mass of (B-1), 36 parts by mass of (B-2), 12 parts by mass of (C-a), 2 parts by mass of (E-1), 2 parts by mass of (F-1), and 1 part by mass of (F-2) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300 ° C., a screw rotation speed of 450 rpm, an extrusion rate of 400 kg / hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Example 9]
The resin composition was melt-kneaded under the same conditions as those for extrusion in Comparative Example 7, except that 12 parts by mass of (B-1) was replaced with (D-1), to obtain pellets of the resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 8]
40 parts by mass of (A-1), 28 parts by mass of (B-2), 12 parts by mass of (C-a), 20 parts by mass of (D-1), 2 parts by mass of (E-1), 2 parts by mass of (F-1), and 1 part by mass of (F-2) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300 ° C., a screw rotation speed of 450 rpm, an extrusion rate of 400 kg / hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

[Comparative Example 9]
80 parts by mass of (A-1), 5 parts by mass of (B-2), 5 parts by mass of (C-1), 10 parts by mass of (D-1), and 2 parts by mass of (E-1) were fed from the most upstream part (top feed) of a TEM58SS twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel number 13, screw diameter 58 mm, L/D = 53) (kneading disk L: 2, kneading disk R: 14, and kneading disk N: 2 screw pattern) at a cylinder temperature of 300°C, a screw rotation speed of 450 rpm, an extrusion rate of 400 kg/hr, and a vent vacuum degree of 7.998 kPa (60 Torr) to obtain pellets of a resin composition.
The evaluation results of the resulting resin composition are shown in Table 1 below.

As shown in Table 1, the resin compositions of Comparative Examples 1, 2, and 7 did not contain the component (D), and therefore had good rigidity (flexural strength, flexural modulus), impact resistance (Charpy impact strength), and retention molding stability, but the balance between heat resistance (DTUL) and molding fluidity (MFR) was insufficient.
The resin compositions of Examples 1 to 9 were excellent in balance between heat resistance and molding fluidity, and were also good in rigidity, impact resistance, and retention molding stability. In particular, Examples 2 to 4 and 6 to 9 showed a tendency to be particularly good in retention molding stability due to the inclusion of the heat stabilizer (E).
The resin composition of Comparative Example 3 did not contain the component (C) and therefore did not have sufficient impact resistance.
The resin compositions of Comparative Examples 4 to 6 contained a molding flowability modifier other than component (D), and therefore did not have sufficient retention molding stability, and other physical properties were not necessarily sufficient either.
The resin composition of Comparative Example 8 had a content of component (D) exceeding the upper limit of the range of the claims of the present application, and therefore showed a tendency for the retention molding stability to decrease, which was insufficient.
The resin composition of Comparative Example 9 was found to be insufficient in terms of the retention molding stability and impact resistance because the content of component (A) exceeded the upper limit of the range defined in the claims of the present application.

The resin composition of the present invention is a polyphenylene ether-based resin composition that has an excellent balance between molding flowability and heat resistance, and also significantly suppresses the occurrence of silver streaks during molding, making it possible to obtain molded products that can be used as thin-walled molded products with high appearance without painting. Therefore, it can be effectively used for decorative molded parts for home appliances and office automation equipment parts, electrical and electronic equipment, automotive applications, and various industrial products.

Claims (5)

The present invention comprises a polyphenylene ether (A), a styrene-based resin (B) (excluding the block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block) , a block copolymer (C) containing a styrene block and a hydrogenated conjugated diene compound block, and a terpene-phenol resin (D) having a softening point (measured by a ring and ball method) of 155° C. or higher,
the content of the (A) component is 35 to 75 parts by mass, the content of the (B) component is 5 to 50 parts by mass, the content of the (C) component is 1 to 20 parts by mass, and the content of the (D) component is 0.5 to 15 parts by mass, relative to 100 parts by mass in total of the (A), (B), (C), and (D) components;
A polyphenylene ether resin composition, characterized in that the total content of the components (A), (B), (C), and (D) is 90 mass% or more of the entire polyphenylene ether resin composition . The polyphenylene ether resin composition according to claim 1, which contains 0.05 to 3 parts by mass of a heat stabilizer (E) having a melting point of 200°C or higher, per 100 parts by mass of the total amount of the components (A), (B), (C), and (D). The polyphenylene ether resin composition according to claim 1 or 2, wherein the component (C) contains a copolymer (C-a) of a styrene block having a bound styrene content of 55% by mass or more and a hydrogenated conjugated diene compound block. The polyphenylene ether resin composition according to claim 3, further comprising a polyolefin resin (F), and the mass ratio ((C-a)/(F)) of the (C-a) component to the (F) component is within the range of 9/1 to 6/4. The polyphenylene ether-based resin composition according to any one of claims 1 to 4, wherein, when the polyamide-based resin and/or the polyolefin-based resin (F) is contained, a total content of the polyamide-based resin and the polyolefin-based resin (F) in the polyphenylene ether-based resin composition is 8 mass% or less .