JP2023136324A - Polyphenylene ether resin composition pellet for injection molding, and method for producing the same - Google Patents

Abstract

To provide a polyphenylene ether resin composition pellet for obtaining an injection molding keeping high elastic modulus even at high temperature.SOLUTION: A polyphenylene ether resin composition pellet contains 10-95 mass% of a thermoplastic resin (A), 5-90 mass% of an inorganic filler (B), and 0-3 mass% of an antioxidant (C), wherein 80 mass% or more of the thermoplastic resin (A) is a polyphenylene ether resin.SELECTED DRAWING: None

Description

The present invention relates to polyphenylene ether resin composition pellets for injection molding that maintain a high elastic modulus even at high temperatures, and a method for producing the same.

Polyphenylene ether resins are widely used because they have excellent mechanical properties, electrical properties, and heat resistance, as well as excellent dimensional stability. However, polyphenylene ether resin alone has poor moldability. In order to improve moldability, a technique has been proposed in which polystyrene resin, polyamide resin, etc. are blended with polyphenylene ether resin. Various improvements have been made to polyphenylene ether resin since then, and it is now a material used in a wide variety of applications.

In recent years, there has been an increasing demand for lighter and stronger products, especially as electronic and electrical components have become thinner and vehicle parts have become smaller. things are wanted.

As mentioned above, polyphenylene ether resin has poor moldability due to its high melt viscosity, and this problem has been overcome by alloying polyphenylene ether resin with other resins with good fluidity. Patent Document 1 discloses a technique of polymer alloying a styrene resin to a polyphenylene ether resin.

However, while increasing the proportion of styrene resin improves fluidity, it also reduces flammability (heat resistance). Conversely, if the proportion of styrene resin is reduced, flammability (heat resistance) will improve, but fluidity will decrease. Flammability (heat resistance) and fluidity are in a trade-off relationship, and from the viewpoint of fluidity, it is difficult to handle polyphenylene ether resin alone.

Furthermore, Patent Document 2 examines flame retardants added to polyphenylene ether resin by alloying polyamide resin, but polyphenylene ether resin and polyamide resin are preferred from the viewpoints of heat resistance, chemical resistance, and processability. The ratio of resin is described, and polyphenylene ether resin alone is not assumed.

Patent Document 3 is a patent relating to an extrusion method using polyphenylene ether resin alone, but it is a technology for producing modified polyphenylene ether by adding a vinyl monomer assumed to be maleic anhydride to polyphenylene ether resin, and It is not assumed that inorganic fillers, etc. will be kneaded into the product.

Thinner-walled and smaller-sized parts can be obtained by injection molding, but with conventional technology, pellets for injection molding of resin compositions made by kneading inorganic fillers etc. with polyphenylene ether alone cannot be obtained. .

Japanese Patent Application Publication No. 2005-302146 Japanese Patent Application Publication No. 2010-260995 Patent No. 3782186

The present invention was devised in view of the current state of the conventional problems described above, and its purpose is to provide polyphenylene ether resin composition pellets for obtaining injection molded products that maintain a high elastic modulus even at high temperatures. be.

As a result of intensive studies to achieve this objective, the present inventors have discovered that by adding a polyphenylene ether resin with a high glass transition point and an inorganic filler in a certain range of amounts and compounding under specific manufacturing conditions, It has been found that it is possible to obtain polyphenylene ether resin composition pellets that can be molded into injection molded products that exhibit a high elastic modulus (in particular, a flexural modulus of 7 GPa or more at 150° C.).

That is, the present invention is as follows.

(1) Contains 10 to 95% by mass of thermoplastic resin (A), 5 to 90% by mass of inorganic filler (B), and 0 to 3% by mass of antioxidant (C), A polyphenylene ether resin composition pellet for injection molding, characterized in that 80% by mass or more is polyphenylene ether resin.
(2) The polyphenylene ether resin composition according to (1), wherein the molded article obtained by injection molding the polyphenylene ether resin composition pellets has a flexural modulus of 7 GPa or more at 150°C. pellet.
(3) The polyphenylene ether resin composition pellet according to (1) or (2), wherein the inorganic filler is carbon fiber.
(4) A method for producing polyphenylene ether resin composition pellets according to any one of (1) to (3), wherein an opening is provided downstream from the supply port for supplying the thermoplastic resin (A). Twin-screw extrusion having a barrel, a vent port having a nitrogen injection line and a gas venting part provided above the opening, and a partition plate separating the nitrogen injection line and the gas venting part inside the vent. A method for producing polyphenylene ether resin composition pellets, the method comprising melt-kneading using a machine.
(5) The set temperature of the barrel responsible for melting and kneading is within the range of 250 to 350°C, and the oxygen concentration in the collecting hopper installed above the supply port for supplying the thermoplastic resin (A) is 3 vol% or less The method for producing polyphenylene ether resin composition pellets according to (4).
(6) An injection molded article comprising pellets of the polyphenylene ether resin composition according to any one of (1) to (3).

By carefully specifying the types of polyphenylene ether resin and inorganic filler, as well as the operating conditions when compounding with a twin-screw extruder, the polyphenylene ether resin composition pellets of the present invention can be produced even at unprecedented high temperatures. It is possible to obtain an injection molded article that maintains its elastic modulus. Depending on the selection of the inorganic filler, it can have an elastic modulus of 7 GPa or more even under high temperature conditions of 150°C, and due to the characteristics of polyphenylene ether resin, it has high dimensional stability and low water absorption, so it can be used for the housing of electrical and electronic equipment. It is extremely useful as parts for the body, interior and exterior parts of automobiles, leisure equipment, and play equipment.

The polyphenylene ether resin composition pellets for injection molding of the present invention contain a thermoplastic resin (A) and an inorganic filler (B), and 80% by mass or more of the thermoplastic resin (A) is a polyphenylene ether resin. be.

The polyphenylene ether resin that accounts for 80% by mass or more of the thermoplastic resin (A) used in the present invention will be explained. Examples of polyphenylene ether resins include poly(2,6-dimethylphenylene ether), poly(2-methyl-6-ethylphenylene ether), poly(2-methyl-6-phenylphenylene ether), and poly(2,6-dimethylphenylene ether). -dichlorophenylene ether), and copolymers of 2,6-dimethylphenol and other phenols (for example, copolymers with 2,3,6-trimethylphenol as described in Japanese Patent Publication No. 17880/1983). Examples include polyphenylene ether copolymers such as copolymers and copolymers with 2-methyl-6-butylphenol.

Among these, more preferred are poly(2,6-dimethylphenylene ether), copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol, and mixtures thereof.

These polyphenylene ether resins may be used alone or in combination of two or more.

When using the above copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, the amount of 2,3,6-trimethylphenol is 2,6-dimethylphenol and 2,3,6-trimethylphenol. The amount is preferably within the range of 15 to 40 mol% based on the total amount of 6-trimethylphenol.

The method for producing the polyphenylene ether resin used in this embodiment is not particularly limited as long as it is a known method. For example, U.S. Pat. No. 3,306,874, U.S. Pat. No. 3,306,875, U.S. Pat. No. 3,257,357, U.S. Pat. , and the manufacturing method described in JP-A-63-152628.

The reduced viscosity of the polyphenylene ether resin used in this embodiment (0.5 g/dL chloroform solution, 30° C., measured with an Ubbelohde viscosity tube) is preferably in the range of 0.20 to 0.70 dL/g.

The polyphenylene ether resin used in this embodiment may be a blend of two or more polyphenylene ether resins having different reduced viscosities.

The polyphenylene ether resin used in this embodiment may be a wholly or partially modified polyphenylene ether resin. Modified polyphenylene ether resin refers to polyphenylene ether resin modified with one or more modifying compounds. Here, the modified compound is selected from the group consisting of one or more carbon-carbon double bonds and/or triple bonds in the molecular structure, and carboxylic acid groups, acid anhydride groups, amino groups, hydroxyl groups, and glycyl groups. Refers to a compound that has one or more groups.

The method for producing the modified polyphenylene ether resin is not particularly limited, and examples include methods (1) to (3) below.
(1) A method of reacting a polyphenylene ether resin with a modified compound without melting it in the presence or absence of a radical initiator at a temperature in the range of 100° C. or higher and lower than the glass transition temperature of the polyphenylene ether resin.
(2) A method in which a polyphenylene ether resin and a modified compound are melt-kneaded and reacted at a temperature in the range from the glass transition temperature of the polyphenylene ether resin to 360° C. in the presence or absence of a radical initiator.
(3) A method in which a polyphenylene ether resin and a modified compound are reacted in a solution at a temperature below the glass transition temperature of the polyphenylene ether in the presence or absence of a radical initiator.

Among these, method (1) or (2) above is preferred.

Having a certain number or more carbon-carbon double bonds and/or triple bonds in the molecular structure, and one or more groups selected from the group consisting of carboxylic acid groups, acid anhydride groups, amino groups, hydroxyl groups, and glycidyl groups; One or more modifying compounds can be suitably used in the above method. These modified compounds will be specifically explained below.

Modified compounds having both a carbon-carbon double bond and a carboxylic acid or acid anhydride group in their molecular structure are not particularly limited, but include, for example, maleic acid, citric acid, itaconic acid, fumaric acid, and chloromaleic acid. , and cis-4-cyclohexene-1,2-dicarboxylic acid, itaconic acid, maleic anhydride and fumaric acid, more preferably citric acid, itaconic acid and maleic anhydride. The modified compound may also be one in which one or two of the two carboxyl groups in these unsaturated dicarboxylic acids are esters.

Modified compounds having both a carbon-carbon double bond and a glycidyl group in their molecular structure are not particularly limited, but include, for example, allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, and epoxidized natural fats and oils. Among them, glycidyl acrylate and glycidyl methacrylate are preferred.

Modified compounds having both a carbon-carbon double bond and a hydroxyl group in their molecular structure are not particularly limited, but common examples include allyl alcohol, 4-penten-1-ol, 1,4-pentadien-3-ol, etc. Examples include unsaturated alcohols represented by the formulas C _n H _2n-3 OH, C _n H _2n-5 OH, and C _n H _2n-7 OH (n is a positive integer).

The above-mentioned modified compounds may be used alone or in combination of two or more.

The amount of the modified compound added when producing the modified polyphenylene ether resin is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, per 100 parts by mass of the polyphenylene ether resin.

When producing a polyphenylene ether resin modified using a radical initiator, the preferred amount of the radical initiator is 0.001 to 1 part by weight per 100 parts by weight of the polyphenylene ether resin.

Further, the addition rate of the modified compound to the modified polyphenylene ether resin is preferably 0.01 to 5% by mass. More preferably, it is 0.10 to 3% by mass.

In the modified polyphenylene ether, an unreacted modified compound and/or a polymer of the modified compound may remain in an amount of less than 1% by mass.

In the present invention, 80% by mass or more of the thermoplastic resin (A) is polyphenylene ether resin. The proportion of polyphenylene ether resin in the thermoplastic resin (A) is preferably 90% by mass or more, more preferably 95% by mass or more, and may be 100% by mass. Examples of thermoplastic resins other than polyphenylene ether resins that can be used as the thermoplastic resin (A) include polystyrene resins, ABS resins, polyolefin resins, polyamide resins, saturated polyester resins, and polyphenylene sulfide resins.

The inorganic filler (B) used in the present invention will be explained. As the inorganic filler (B), reinforcing fibers are preferred.

The reinforcing fibers are not particularly limited, but typical examples include inorganic fibers such as carbon fibers, silicon carbide fibers, and glass fibers, metal fibers such as boron fibers, and organic fibers such as aramid fibers. From the viewpoint of cost and the elastic modulus and mechanical strength of the resulting molded product, inorganic fibers such as glass fibers and carbon fibers are preferred, especially from the viewpoint of achieving an elastic modulus of 7 GPa or more even under high temperature conditions of 150 ° C. Carbon fiber is preferred.

By increasing or decreasing the amount of inorganic filler (B) blended into the polyphenylene ether resin, it is possible to bring out desired mechanical properties. It is important that the blending (containing) ratio is 10 to 95% by mass of the thermoplastic resin (A) and 5 to 90% by mass of the inorganic filler (B) in the pellet of the polyphenylene ether resin composition. A) 50 to 90% by mass, inorganic filler (B) 10 to 50% by mass are preferred, thermoplastic resin (A) 60 to 85% by mass, and inorganic filler (B) 15 to 40% by mass are more preferred. If the amount of inorganic filler (B) is less than 5% by mass, the expected reinforcing effect may not be obtained, and if the amount of inorganic filler (B) is more than 90% by mass, it may not be possible to obtain the reinforcing effect in the polyphenylene ether resin. Inorganic filler (B) cannot be uniformly dispersed.

The polyphenylene ether resin composition according to this embodiment may further contain an antioxidant (C).

The antioxidant (C) can be either a primary antioxidant that acts as a radical chain inhibitor or a secondary antioxidant that has the effect of decomposing peroxides. That is, by using an antioxidant, it is possible to scavenge radicals that may be generated in terminal methyl groups or side chain methyl groups when polyphenylene ether resin is exposed to high temperatures for a long period of time (primary antioxidant), or The radicals can decompose peroxides generated in terminal methyl groups or side chain methyl groups (secondary antioxidant), and therefore, oxidative crosslinking of the polyphenylene ether resin can be prevented.

As the primary antioxidant, mainly hindered phenolic antioxidants can be used, and specific examples include 2,6-di-t-butyl-4-methylphenol, pentaerythritoltetrakis [3-(3, 5-di-t-butyl-4-hydroxyphenyl)propionate], n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(4-methyl) -6-t-butylphenol), 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-[1-(2-hydroxy-3 , 5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), alkylated bisphenol, tetrakis[ Methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl) )-propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxyspiro[5,5]undecane and the like.

As the secondary antioxidant, phosphorous antioxidants can mainly be used. Specific examples of phosphorous antioxidants include trisnonylphenyl phosphite, triphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and bis(2,4-di-t-butylphenyl). Pentaerythritol-di-phosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite, 3,9-bis(2,6-di-tert-butyl-4 -methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane and the like.

Further, as other antioxidants, metal oxides such as zinc oxide and magnesium oxide, and metal sulfides such as zinc sulfide can be used in combination with the above antioxidants.

Among these, in order to improve the toughness of the molded article and the mechanical properties after long-term exposure to high temperatures, phosphorus-based antioxidants, which are secondary antioxidants, are preferred, and phosphite-based antioxidants are more preferred.

The content of the antioxidant (C) is preferably 0 to 3% by mass based on 100% by mass of the polyphenylene ether resin composition pellets. From the viewpoint of suppressing oxidative deterioration of the resin during injection molding processing, the content is preferably 0.0001% by mass or more, and from the viewpoint of maintaining the surface appearance of the molded product, the content is preferably 3% by mass or less.

The polyphenylene ether resin composition pellets of the present invention may also contain other known additives within a range that does not impair the effects of the present invention. Examples of known additives include colorants such as pigments, heat stabilizers, ultraviolet absorbers, light stabilizers, plasticizers, modifiers, antistatic agents, flame retardants, dyes, and the like. The total content of these additives in the polyphenylene ether resin composition pellets is preferably 10% by mass or less, more preferably 5% by mass or less.

It is preferable that the flexural modulus at 150° C. of the molded article obtained by injection molding the polyphenylene ether resin composition pellets of the present invention is 7 GPa or more. If a particularly high elastic modulus is not required, a bending elastic modulus of 5 GPa or more can be said to have a high elastic modulus at high temperatures.

A method for producing polyphenylene ether resin composition pellets of the present invention will be explained. In a preferred embodiment, polyphenylene ether resin composition pellets are produced by melt-kneading each raw material using a twin-screw extruder, cooling the discharged strand in water, and cutting it with a strand cutter to form pellets. be.
In addition, by employing the manufacturing conditions described below, the polyphenylene ether resin composition can be formed into pellets.

The twin-screw extruder used has a barrel with an opening downstream from the supply port (first supply port) for supplying the thermoplastic resin (A), and a nitrogen injection line and a gas injection line above the opening. It is important that a vent port with a cutout is provided. Normally, during extrusion, it is originally desirable to devolatilize under reduced pressure in a vacuum vent in order to remove residual volatile components in the raw material components, but in this case, it is necessary to devolatilize the material under reduced pressure at the vacuum vent and the surrounding barrels. Outside air may be sucked in through the gap, accelerating the deterioration of the molten resin due to oxidative crosslinking, thereby increasing the viscosity. In that case, it may be preferable to extrude without devolatilizing under reduced pressure using a vacuum vent. If you remove the vacuum vent and plug the top of the barrel, the pressure inside the barrel will increase due to the gas generated from the molten resin during extrusion, making the discharge of the molten resin from the die nozzle unstable and making it difficult to take off the strand during extrusion. Therefore, a vent port with a nitrogen injection line and a gas vent is installed at the opening at the top of the barrel, and nitrogen is injected from the nitrogen injection line into the vent port and sprayed onto the molten resin at the vent opening. It is preferable to extrude gas components and nitrogen gas generated from the molten resin while discharging them from the gas venting section. Further, for the purpose of reliably discharging the gas components generated from the molten resin, it is desirable to have a structure in which the inside of the vent is separated from the nitrogen injection line and the gas vent by a partition plate. By providing a partition plate in the vent, the discharge efficiency is improved compared to the vent by using the nitrogen injection pressure for the generated gas, and it can be expected to be more effective in preventing the molten resin from coming into contact with oxygen. Note that the supply port (first supply port) for supplying the thermoplastic resin (A) is preferably the most upstream input port of the twin-screw extruder.

The flow rate of nitrogen gas injected into the vent port is preferably within the range of 1 to 50 L/min, more preferably within the range of 5 to 30 L/min, and still more preferably within the range of 10 to 25 L/min. From the viewpoint of sufficient contact between the resin and nitrogen gas, the flow rate is preferably 1 L/min or more, and from the viewpoint of consideration to the surrounding environment, the flow rate is preferably 50 L/min or less.

The set temperature of the barrel responsible for kneading, melting, and transporting the resin in the twin-screw extruder is preferably within the range of 250 to 350°C, more preferably within the range of 280 to 330°C. From the viewpoint of production stability, the temperature is preferably 250°C or higher, and from the viewpoint of suppressing thermal deterioration of the polyphenylene ether resin, the temperature is preferably 350°C or lower.

The set temperature of the resin composition discharge section (die head) in the twin-screw extruder is preferably within the range of 250 to 350°C. Preferably it is within the range of 280 to 330°C. From the viewpoint of production stability, the temperature is preferably 250°C or higher, and from the viewpoint of suppressing thermal deterioration of the polyphenylene ether resin, the temperature is preferably 350°C or lower.

When producing the resin composition pellets used in this embodiment using a twin-screw extruder, it is important to note that the resin composition pellets may contain oxidative deterioration from the polyphenylene ether resin, which is the component (A). The contamination of the resulting gels and carbides causes deterioration of physical properties such as surface appearance and toughness of the molded product.
Therefore, it is preferable to input the component (A) from the first supply port and set the oxygen concentration inside the collecting hopper provided above the first supply port to 3 vol% or less. The oxygen concentration inside the collecting hopper is more preferably 2 vol% or less, still more preferably 1 vol% or less, particularly preferably 0.5 vol% or less. The lower limit of the oxygen concentration inside the collection hopper is not particularly limited, but is generally 0.1 vol% or more.

To adjust the oxygen concentration, replace the inside of the raw material storage hopper with sufficient nitrogen, and seal the feed piping line from the raw material storage hopper to the first supply port of the twin-screw extruder to prevent air from entering or exiting. This can be done by adjusting the amount of nitrogen feed and the opening degree of the gas vent.

In addition, in the production of resin composition pellets in this embodiment, all raw materials are supplied from the first supply port to ensure sufficient oxygen concentration inside the collecting hopper at the first supply port, which is the most upstream input port. It is preferable from this point of view, and also preferable from the viewpoint of suppressing oxidative deterioration of the component (A) and sufficiently achieving the effects required for the use of the present invention.

The oxygen concentration inside the collecting hopper is measured using an oxygen concentration meter, and by installing the sensor part of the oxygen concentration meter in the center of the collecting hopper, constant measurement is possible during extrusion. It is possible to do so.

In addition, when the molten resin (composition) extruded from the die nozzle of a twin-screw extruder comes into contact with air, the molten resin (composition) adhering to the edge of the nozzle progresses to deteriorate due to oxidative crosslinking, resulting in the formation of smear. , may contribute to growth. As production progresses over a long period of time, it may grow on the edges of the nozzle and eventually get mixed into the resin composition, causing poor appearance and deterioration of physical properties. It is also desirable to spray.

The amount of nitrogen gas sprayed to the die nozzle is preferably within the range of 1 to 50 L/min, more preferably within the range of 5 to 30 L/min, and still more preferably within the range of 10 to 25 L/min. From the viewpoint of sufficient contact between the resin composition and nitrogen gas, the flow rate is preferably 1 L/min or more, and from the viewpoint of consideration to the surrounding environment, the flow rate is preferably 50 L/min or less.

In producing the resin composition pellets of this embodiment, the screw rotation speed of the twin-screw extruder is preferably 100 to 800 rpm. More preferably, it is within the range of 200 to 600 rpm. The speed is preferably 100 rpm or more from the viewpoint of sufficient melting and kneading of the resin composition, and preferably 800 rpm or less from the viewpoint of suppressing thermal deterioration of the resin composition due to shear heat generation.

The shape and size of the polyphenylene ether resin composition pellets of the present invention are not particularly limited. The shape of the pellet is generally cylindrical, but is not limited to this. In the case of a cylindrical shape, the length is preferably 2 to 5 mm, the cross section is preferably circular, and the diameter is preferably 1.5 to 4.0 mm.

The molded article made of the polyphenylene ether resin composition pellets of this embodiment can be obtained by molding the resin composition obtained by the above-mentioned manufacturing method.
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, with injection molding being more preferably used, particularly from the viewpoint of molded appearance. .

The molding temperature during molding of the resin composition pellets is preferably within the range of the maximum barrel setting temperature of 250 to 350°C, and more preferably within the range of 280 to 330°C. From the viewpoint of sufficient processability, the molding temperature is preferably 250°C or higher, and from the viewpoint of suppressing thermal deterioration of the resin and maintaining physical properties, the molding temperature is preferably 350°C or lower.

The mold temperature during molding of the resin composition pellets is preferably within the range of 50 to 150°C, more preferably 80 to 130°C. From the viewpoint of maintaining sufficient appearance of the molded product, the mold temperature is preferably 50°C or higher, and from the viewpoint of molding stability, it is preferably 150°C or lower.

Suitable molded products in this embodiment include applications to various electronic and electrical parts, automobile applications, various industrial products, etc. that take advantage of the property of maintaining a high elastic modulus even at high temperatures.

Hereinafter, this embodiment will be described in more detail with reference to Examples and Comparative Examples, but this embodiment is not limited to these Examples.

The following raw materials were used.

[Polyphenylene ether resin]
(A-1) Polyphenylene ether resin (abbreviation: PPE, manufactured by Sabic, brand name: PPO640, poly(2,6-dimethylphenylene ether), reduced viscosity 0.4 dL/g)
Hereinafter, thermoplastic resins other than polyphenylene ether resin were used as comparative examples, but numbers (A-2) to (A-5) were assigned for convenience.
(A-2) Polyamide 6 resin (abbreviation: PA6, manufactured by Zig Sheng Industrial, brand name: ZISAMIDE (registered trademark) TP4208)
(A-3) Polyamide 66 resin (abbreviation: PA66, manufactured by BASF, brand name: Ultramid A24E)
(A-4) Polybutylene terephthalate resin (abbreviation: PBT, manufactured by CHANG CHUN PLASTICS, brand name: 1200-211M)
(A-5) Polyethylene terephthalate resin (abbreviation: PET, manufactured by Hengli, brand name: S-Bright)

[Inorganic filler (B)]
(B-1) Carbon fiber (fiber diameter 5 μm, manufactured by Nihon Polymer Sangyo Co., Ltd., brand name: UW-MC-HS C-6)
(B-2) Carbon fiber (fiber diameter 7 μm, manufactured by Nihon Polymer Sangyo Co., Ltd., brand name: UW-MC C-6)
(B-3) Glass fiber (fiber diameter 11 μm, manufactured by Nippon Electric Glass Co., Ltd., brand name: ECS 03 T-127H)

[Antioxidant (C)]
It was not used in this example and comparative example.

[Examples 1 to 4]
Polyphenylene ether resin and carbon fiber with the composition shown in Table 1 were fed to the first feed port of a twin-screw extruder (CM-MTE31 manufactured by Continent Machinery) set to the conditions shown in the table, and melted and mixed in the barrel. After kneading, the strand discharged from the die was cooled in water, cut into 3.0 mm lengths using a strand cutter, and pelletized to obtain polyphenylene ether resin composition pellets. Note that a collecting hopper is provided above the first supply port of the twin-screw extruder, and nitrogen is introduced into the collecting hopper. A vent port was installed in which the nitrogen injection line and gas vent were separated by a partition plate.

[Example 5]
This is the same level as the compositions shown in Examples 1 to 4 except that the inorganic filler was changed to glass fiber. The kneading was carried out without changing the other kneading conditions. Note that the proportion of glass fiber was 30% by mass.

[Comparative Examples 1 to 6]
With the composition shown in Table 1, the kneading conditions using a twin-screw extruder were the same as in Examples 1 to 4.

[Comparative Example 7]
This is the same level as in Example 2, except that the melt-kneading device was changed from a twin-screw extruder to a single-screw extruder. The melt viscosity of polyphenylene ether was too high, and the single-screw extruder caused torque overflow, making it impossible to obtain resin composition pellets. Note that production was performed by introducing nitrogen into the collecting hopper into which the resin was charged, as in the case of using a twin-screw extruder.

[Comparative example 8]
In Example 2, the vent used was changed to a vacuum vent instead of a vent port having a nitrogen injection line and a gas vent. As a result, the viscosity of the polyphenylene ether inside the cylinder was significantly increased due to deterioration, and resin composition pellets could not be obtained due to overtorque of the apparatus.

The various resin composition pellets thus obtained were vacuum-dried at 80° C. overnight, molded into dumbbell test pieces using an injection molding machine, and subjected to a bending test. Injection molding was performed under the molding conditions shown in Table 1. The glass transition points of the various resin composition pellets were also measured by DSC (differential scanning calorimetry) (according to ISO 11357, a heating rate of 20 K/min was adopted).

The bending elastic modulus was evaluated as the bending elastic modulus at 150°C in accordance with ISO178.

Examples 1 to 4 have high elastic modulus (7 GPa or more) at all levels, as shown by the results of the 150°C bending test. Note that as the amount of carbon fibers contained increases, the elastic modulus tends to improve, and as the fiber diameter becomes thinner from 7 μm to 5 μm, the elastic modulus tends to increase.

In Example 5, the 150°C bending test showed a lower tendency, and the elastic modulus was less than 7 GPa, compared to the level in which carbon fiber was used as the inorganic filler (Examples 1 to 4). Note that this value is higher than the elastic modulus of Comparative Examples 1 to 4, which will be described later.

In Comparative Examples 1 to 4, the flexural modulus at 150° C. in all four levels was significantly smaller than 5.0 GPa, and did not satisfy the target of 7 GPa. All of the resins used have glass transition points lower than 100°C, so elastic modulus at 150°C cannot be expected.

In Comparative Examples 5 and 6, the inorganic filler was carbon fiber, but the elastic modulus at 150° C. for both levels was smaller than 5.0 GPa, which did not satisfy the target of 7 GPa.

The polyphenylene ether resin composition of the present invention is a resin composition that maintains a high elastic modulus even at high temperatures, and has an elastic modulus of 5 GPa or more, or 7 GPa or more even under a high temperature condition of 150°C. Therefore, in addition to mechanical properties, it can be suitably used in various applications such as housings of electrical and electronic equipment, interior and exterior parts of automobiles, leisure equipment, and play equipment, which require high dimensional stability and low water absorption.

Claims (6)

Contains 10 to 95% by mass of thermoplastic resin (A), 5 to 90% by mass of inorganic filler (B), and 0 to 3% by mass of antioxidant (C), and 80% by mass of the thermoplastic resin (A). A polyphenylene ether resin composition pellet for injection molding, characterized in that the above is a polyphenylene ether resin. The polyphenylene ether resin composition pellet according to claim 1, wherein the molded article obtained by injection molding the polyphenylene ether resin composition pellet has a flexural modulus at 150°C of 7 GPa or more. The polyphenylene ether resin composition pellet according to claim 1 or 2, wherein the inorganic filler is carbon fiber. The method for producing polyphenylene ether resin composition pellets according to any one of claims 1 to 3, comprising a barrel provided with an opening downstream from a supply port for supplying the thermoplastic resin (A), Melting is carried out using a twin-screw extruder in which a vent port having a nitrogen injection line and a gas vent is provided above the opening, and the nitrogen injection line and the gas vent are separated by a partition plate inside the vent. A method for producing polyphenylene ether resin composition pellets, which comprises kneading. The set temperature of the barrel responsible for melting and kneading is within the range of 250 to 350 ° C., and the oxygen concentration in the collecting hopper provided above the supply port for supplying the thermoplastic resin (A) is 3 vol% or less, A method for producing polyphenylene ether resin composition pellets according to claim 4. An injection molded article comprising pellets of the polyphenylene ether resin composition according to any one of claims 1 to 3.