JP2023015635A - Polybutylene naphthalate resin composition and molded article using the same - Google Patents

Abstract

To provide a polybutylene naphthalate resin composition having excellent abrasion resistance, low friction coefficient, and high limit PV value, and to provide a molded article using the same.SOLUTION: There is provided a resin composition containing: (A) to 100 pts.wt. of polybutylene naphthalate resin (component A); (B) 5 to 30 pts.wt. of polytetrafluoroethylene (component B); (C) 5 to 50 pts.wt. of carbon fiber (component C); and (D) 5 to 50 pts.wt. of glass fiber (component D), wherein the content of component C in total 100 pts.wt. of the component C and the component D is 15 to 85 pts.wt.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polybutylene naphthalate resin composition having excellent abrasion resistance, a low coefficient of friction, and a high limit PV value when the molded article is slid, and a molded article using the same.

Aromatic polyester resins have conventionally been excellent in mechanical properties, heat resistance and chemical resistance, and have been widely used for electric and electronic parts, home appliances and automobile parts. Among them, polybutylene naphthalate resin is used for various gears and polishing pads because it is characterized by superior slidability and hydrolysis resistance compared to polybutylene terephthalate resin and the like. The characteristics required for resin members for sliding applications are wear resistance that does not wear the own material and the mating material, low coefficient of friction that suppresses temperature rise during sliding, and a wide range of load and sliding speed. To prevent a resin member from being fused due to being unable to withstand a load. The product of the limit surface pressure and speed at which fusion occurs is called the limit PV value, which is used as an index of the range in which the resin member can be used without fusion.

Patent Document 1 proposes a polybutylene naphthalate resin composition with excellent slidability and a resin composition comprising a polybutylene naphthalate resin, a high-density polyethylene resin and an acid-modified polyethylene resin as a sliding part using the same. It is However, since there is no description of the limit PV value and no reinforcing material is added, it is assumed that the usable range is limited. Patent Document 2 discloses a resin composition comprising an aromatic polyester resin, carbon fiber and tetrafluoroethylene resin, and Patent Document 3 discloses a resin composition having excellent wear resistance comprising a polyester resin, a tetrafluoroethylene resin and a fibrous filler. However, there is no description of polybutylene naphthalate resin and limit PV value, and further improvement of abrasion resistance is required.

JP 2010-111759 A JP-A-11-21408 JP-A-2000-7924

An object of the present invention is to provide a polybutylene naphthalate resin composition having excellent wear resistance, a low coefficient of friction and a high limiting PV value, and a molded article using the same.

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, achieved the above-mentioned objects by blending polytetrafluoroethylene, carbon fiber and glass fiber in a specific ratio with polybutylene naphthalate resin. This discovery led to the present invention.

That is, the above problems are (A) polybutylene naphthalate resin (A component) 100 parts by weight, (B) polytetrafluoroethylene (B component) 5 to 30 parts by weight, (C) carbon fiber (C component ) and 5 to 50 parts by weight of (D) glass fiber (component D), wherein the content of component C in the total 100 parts by weight of component C and component D is 15 to 85 parts by weight of the resin composition.

According to the present invention, it is possible to provide a polybutylene naphthalate resin composition having excellent slidability, particularly good wear resistance, a low coefficient of friction, and a high limit PV value. The resulting molded article can be suitably used for electrical and electronic parts, automobile parts and construction members.

Further details of the present invention will be described below.

<About A component>
The polybutylene naphthalate resin, which is component A of the present invention, comprises a dicarboxylic acid component mainly composed of naphthalenedicarboxylic acid and/or an ester-forming derivative of naphthalenedicarboxylic acid, and a glycol component mainly composed of 1,4-butanediol. can be manufactured using

As the naphthalenedicarboxylic acid component, 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid are used as main components, but other dicarboxylic acids may be used in combination as long as the properties are not impaired. Other dicarboxylic acids include, for example, terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenyl ether-4, Aromatic dicarboxylic acids such as 4'-dicarboxylic acid, adipic acid, sebacic acid, succinic acid, aliphatic dicarboxylic acids such as oxalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and the like, one or Two or more kinds may be used, and can be arbitrarily selected depending on the purpose. The amount of the other dicarboxylic acid used is preferably 30 mol % or less, more preferably 20 mol % or less, based on the total acid components. As the ester-forming derivative of naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate and dimethyl 2,7-naphthalenedicarboxylate are used as main components, but esters of other dicarboxylic acids are used as long as the properties are not impaired. Formable derivatives can be used in combination. Other ester-forming derivatives of dicarboxylic acids include, for example, terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid. acids, lower dialkyl esters of aromatic dicarboxylic acids such as diphenyl ether-4,4′-dicarboxylic acid, lower dialkyl esters of alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, adipic acid, sebacic acid, succinic acid, oxalic acid, etc. Lower dialkyl esters of aliphatic dicarboxylic acids and the like can be mentioned, and one or more of these may be used and can be arbitrarily selected depending on the purpose. The amount of other ester-forming derivative of dicarboxylic acid to be used is preferably 30 mol % or less, more preferably 20 mol % or less, relative to the total dicarboxylic acid ester-forming derivative component.

Also, a small amount of tri- or higher functional dicarboxylic acid component such as trimellitic acid may be used, and a small amount of acid anhydride such as trimellitic anhydride may be used. In addition, a small amount of hydroxycarboxylic acid such as lactic acid and glycolic acid or an alkyl ester thereof may be used, and can be arbitrarily selected depending on the purpose.

As the glycol component, 1,4-butanediol is used as the main component, but other glycol components can be used together as long as the characteristics are not impaired. Other glycol components include, for example, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentylene glycol, hexamethylene glycol, decamethylene glycol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, poly One or two or more of alkylene glycols such as (oxy)ethylene glycol, poly(oxy)tetramethylene glycol and poly(oxy)methylene glycol may be used, and can be arbitrarily selected depending on the purpose. In addition, small amounts of polyhydric alcohol components such as glycerin may be used. A small amount of epoxy compound may also be used. The amount of other glycol components used is preferably 30 mol % or less, more preferably 20 mol % or less, based on the total glycol components.

The amount of the glycol component to be used is preferably 1.1 times or more and 1.4 times or less by mol with respect to the dicarboxylic acid or the ester-forming derivative of the dicarboxylic acid. If the amount of the glycol component used is less than 1.1 times by mole, the esterification or transesterification reaction may not proceed sufficiently, which is not preferred. If the molar ratio is more than 1.4 times, the reaction rate will be slowed for unknown reasons, and the excess glycol component may generate a large amount of by-products such as tetrahydrofuran, which is not preferred.

A titanium compound is used as a polymerization catalyst in the production of polybutylene naphthalate resin. As the titanium compound used as the polymerization catalyst, tetraalkyl titanate is preferable, and specifically tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-sec-butyl titanate, tetra-t-butyl titanate, tetra-n-hexyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, tetrabenzyl titanate, etc., and a mixed titanate thereof may be used. Among these titanium compounds, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate are particularly preferred, and tetra-n-butyl titanate is most preferred. The amount of the titanium compound added is preferably 10 ppm or more and 60 ppm or less, more preferably 15 ppm or more and 30 ppm or less, as the titanium atom content in the produced polybutylene naphthalate. If the content of titanium atoms in the polybutylene naphthalate produced exceeds 60 ppm, the color tone and thermal stability of the resin composition of the present invention may deteriorate, which is not preferred. On the other hand, when the titanium atom content is less than 10 ppm, good polymerization activity cannot be obtained, and a polybutylene naphthalate resin having a sufficiently high intrinsic viscosity may not be obtained. The polybutylene naphthalate resin of the present invention comprises a dicarboxylic acid component mainly composed of naphthalene dicarboxylic acid and/or its ester-forming derivative and a glycol component mainly composed of 1,4-butanediol in the presence of a titanium compound. It is preferable to produce via an esterification or transesterification reaction step and a subsequent polycondensation reaction step, but the temperature at the end of the esterification or transesterification reaction is in the range of 180°C or higher and 220°C or lower. The temperature is preferably 180° C. or higher and 210° C. or lower. When the temperature at the end of the esterification reaction or the transesterification reaction exceeds 220°C, the reaction rate increases, but it is not preferred because by-products such as tetrahydrofuran may increase. Also, if the temperature is less than 180°C, the reaction may not proceed. The reaction product (bisglycol ether and/or its low polymer) obtained by the esterification or transesterification reaction is 0.4 kPa (3 Torr ) is preferably polycondensed under the following reduced pressure. If the polycondensation reaction temperature exceeds 270° C., the reaction rate rather decreases and coloration increases, which is not preferred.

<About B component>
Polytetrafluoroethylene, which is the B component of the present invention, can be a known one per se, and both calcined and uncalcined polytetrafluoroethylene can be used, but polytetrafluoroethylene does not reaggregate. Since it is easy to re-agglomerate, it is preferably in the form of a powder subjected to a calcination treatment, etc., and particularly preferably polytetrafluoroethylene calcined at a calcination temperature of 360° C. or higher. The melting point of polytetrafluoroethylene is preferably 320 to 335°C, more preferably 325 to 335°C, as measured by the DSC method so as to make reaggregation difficult. The average particle size of polytetrafluoroethylene is measured by a method of measuring a dispersion liquid dispersed in perchlorethylene by a light transmission method, and is preferably 0.1 μm to 100 μm, more preferably 1 μm to 40 μm, More preferably, it is 1 μm to 20 μm. The average particle size referred to here is the weight average particle size measured using the laser diffraction/scattering method (MICOTRAC method).

The polytetrafluoroethylene preferably has a number average molecular weight of 100,000 or more, more preferably 200,000 or more.

Examples of such polytetrafluoroethylene are commercially available from Kitamura Co., Ltd. as KTL-620, KTL-450A, KT-600M, and KT-400M, and are readily available.

The content of component B is 5 to 30 parts by weight, preferably 7 to 25 parts by weight, and more preferably 10 to 20 parts by weight, per 100 parts by weight of component A. If the content is less than 5 parts by weight or more than 30 parts by weight, the amount of wear during sliding increases. Furthermore, when the content is less than 5 parts by weight, the limit PV value is also lowered.

Component ^B is preferably dispersed in the resin matrix with a domain size within a specific range from the viewpoint of developing low wear properties. is 8-70 μm ² . The average area of the dispersed phase referred to here is obtained by photographing the cross section of the molded product using the resin composition with an electron scanning microscope at a magnification of 500 times, and using image analysis software Image J Fiji for 500 dispersed phases of the B component. It is the average area calculated by performing binarization processing. However, dispersed phases with an area of less than 1 μm ² were excluded from the calculation.

<About C component>
As the carbon fiber, which is the C component of the present invention, any carbon fiber generally called carbon fiber may be used. For example, PAN-based carbon fiber made from polyacrylonitrile, pitch-based carbon fiber made from petroleum tar or petroleum pitch, vapor-grown carbon fiber made from hydrocarbons, cellulose made from viscose rayon, etc. and carbon fiber.

Although the average fiber diameter of the carbon fibers is not particularly limited, it is preferably 2 to 20 μm, more preferably 6 to 15 μm, still more preferably 6 to 10 μm. Carbon fibers having an average fiber diameter within such a range may be able to exhibit good low wear properties without impairing the external appearance of the molded article. The average fiber diameter referred to here is obtained by photographing a cross section of a molded article using a resin composition with an electron scanning microscope at a magnification of 1800, measuring the fiber diameter of 100 carbon fibers, and obtaining the average value. Moreover, the carbon fibers may be subjected to a bundling treatment from the viewpoint of productivity and mechanical strength. Examples of the sizing agent include olefin-based resins, styrene-based resins, acrylic-based resins, polyester-based resins, epoxy-based resins and urethane-based resins, but are not particularly limited. From the standpoint of workability, the amount of the sizing agent is preferably 0-5% by weight, more preferably 0.1-4% by weight. The carbon fiber may be coated with a metal layer on the surface of the carbon fiber. Examples of metals include silver, copper, nickel, and aluminum, and nickel is preferable from the viewpoint of corrosion resistance of the metal layer.

The content of component C is 5 to 50 parts by weight, preferably 8 to 45 parts by weight, more preferably 10 to 40 parts by weight, and still more preferably 15 to 35 parts by weight with respect to 100 parts by weight of component A. . If the content of component C exceeds 50 parts by weight, the amount of carbon fibers falling off during sliding increases, resulting in an increase in the coefficient of friction. On the other hand, if the content is less than 5 parts by weight, the amount of wear during sliding increases and the limit PV value also decreases.

<About D component>
As the glass fiber used as component D in the present invention, any glass fiber generally referred to as glass fiber may be used. The glass composition of A glass, C glass, E glass and the like is not particularly limited, and may contain components such as TiO ₂ , SO ₃ and P ₂ O ₅ depending on the case. However, it is more preferable to mix E-glass (non-alkali glass) with polybutylene naphthalate resin. The glass fiber is obtained by stretching molten glass by various methods and quenching it to form a predetermined fibrous shape. The quenching and stretching conditions in such a case are not particularly limited either. In addition, the shape of the cross-section may be a circular shape, an elliptical shape, a cocoon shape, a trefoil shape, or other shape other than a perfect circle. When a fibrous filler is added, a glass fiber having an elliptical cross-section may be used to suppress anisotropy of physical properties. Also, those having a major axis of 15 to 45 μm, a minor axis of 3 to 15 μm, and an aspect ratio of 1.8 to 6 are preferably used. Furthermore, a mixture of circular glass fibers and non-circular glass fibers may be used. The glass fibers may be coated or bundled with resins such as ethylene/vinyl acetate copolymers, polyurethanes and epoxy resins.

The content of component D is 5 to 50 parts by weight, preferably 8 to 45 parts by weight, more preferably 10 to 40 parts by weight, and still more preferably 15 to 35 parts by weight with respect to 100 parts by weight of component A. . If the content of component D exceeds 50 parts by weight, the limiting PV value will decrease, while if it is less than 5 parts by weight, the amount of wear during sliding and the coefficient of friction will increase, and the limiting PV value will also decrease.

The content of component C in the total 100 parts by weight of components C and D in the present invention is 15 to 85 parts by weight, preferably 20 to 80 parts by weight, more preferably 25 to 75 parts by weight, still more preferably 30 parts by weight. ~70 parts by weight. If the content is less than 15 parts by weight, the amount of wear during sliding increases and the PV limit decreases. The PV value also decreases. Although the reasons for these are not clear, they can be inferred as follows. That is, the glass fiber-containing polybutylene naphthalate resin has a low coefficient of friction, but tends to have a high coefficient of friction at the initial stage of sliding. And, by using it together with carbon fiber, it is possible to maintain a low coefficient of friction over the entire sliding time while softening the rise in the initial coefficient of friction, so it is possible to have a high limit PV value and a low amount of wear. can.

The resin composition of the present invention may be blended with other thermoplastic resins within the scope of the present invention, and if necessary, antioxidants, impact modifiers, plasticizers, C components and D components. Inorganic fillers other than the above, non-halogenated flame retardants, colorants, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants other than B component, dispersants, flow modifiers, crystal nucleating agents, etc. can contain each additive.

<Method for producing resin composition>
Any method may be employed to produce the resin composition of the present invention. For example, a method of premixing each component and optionally other components, followed by melt-kneading and pelletizing can be mentioned. Means for premixing include a Nauta mixer, a V-type blender, a Henschel mixer, a mechanochemical device, an extrusion mixer, and the like. In the pre-mixing, granulation can be performed by an extrusion granulator, a briquetting machine, or the like. After pre-mixing, the mixture is melt-kneaded by a melt-kneader typified by a vented twin-screw extruder, and pelletized by a device such as a pelletizer. Other examples of the melt-kneader include a Banbury mixer, a kneading roll, a constant temperature stirring vessel and the like, but a vented twin-screw extruder is preferred. Alternatively, each component and, optionally, other components may be supplied independently to a melt-kneader typified by a twin-screw extruder without being premixed.

<About the compact>
A molded article using the resin composition of the present invention can be obtained by molding the pellets produced as described above. It is preferably obtained by injection molding or extrusion molding. In injection molding, not only ordinary molding methods, but also injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including the method of injecting supercritical fluid), insert molding, in-mold coating molding, heat insulation metal Mold molding, rapid heating and cooling mold molding, two-color molding, multi-color molding, sandwich molding, ultra-high speed injection molding and the like can be mentioned. For molding, either cold runner method or hot runner method can be selected. In extrusion molding, a molded body can be obtained by extruding a round bar and then cutting it into a disk shape, or by extruding a thick sheet and then punching it into a predetermined shape. can.

[EXAMPLES] Hereafter, although the form which implements this invention is demonstrated by an Example, this invention is not limited to these. Moreover, evaluation of various physical properties was carried out by the following methods.

[Evaluation of Resin Composition]
(1) Coefficient of dynamic friction After drying the pellets obtained by the following method at 120 ° C. for 5 hours, using an injection molding machine (EC130SXII-4Y manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 290 ° C. and a mold temperature of 120 ° C. A hollow cylindrical test piece having an outer diameter of 25.6 mm, an inner diameter of 20 mm and a height of 15 mm was molded according to the K7218A method. According to JIS K7218A method, the test piece was slid against a similarly shaped test piece made of carbon steel (S45C), and the dynamic friction coefficient was measured. The test was performed using a friction and wear tester (EFM-3-G, manufactured by Orientec Co., Ltd.) under the conditions of a surface pressure of 1.5 MPa, a sliding speed of 500 mm/s, and a sliding distance of 3000 m. The dynamic friction coefficient over a sliding distance of 300 to 3000 m was measured at intervals of 1 second, and the average value thereof was taken as the dynamic friction coefficient. The coefficient of dynamic friction must be 0.20 or less.

(2) Specific Wear Amount Pellets obtained by the following method were molded in the same manner as in (1) to obtain a hollow cylindrical test piece having an outer diameter of 25.6 mm, an inner diameter of 20 mm and a height of 15 mm. According to the JIS K7218A method, the test piece was subjected to a friction and wear tester (EFM -3-G, manufactured by Orientec Co., Ltd.). The weight loss of the test piece after sliding was weighed to the nearest 0.1 mg using an electronic balance, and the specific wear amount was calculated using the formula described in JIS K7218A method. The test was conducted 5 times, and the average value thereof was taken as the specific wear amount of the composition. The specific wear amount must be 7×10 ⁻⁶ mm ³ /N·m or less.

(3) Limit PV value A pellet obtained by the following method was molded in the same manner as in (1) to obtain a hollow cylindrical test piece with an outer diameter of 25.6 mm, an inner diameter of 20 mm and a height of 15 mm. The test piece was slid against a similarly shaped test piece made of carbon steel (S45C) according to the JIS K7218A method. The test was started with a load of 100 N and a sliding speed of 500 mm/s, and the load was increased by 100 N every 10 minutes. The load at which a load fluctuation of 50 N or more occurred was defined as -100 N, and the product of the limit load and the sliding speed was defined as the limit PV value. The test was performed 5 times, and the average value thereof was taken as the limiting PV value of the composition. The limit PV value must be 60 MPa·m/min or more.

(4) Average area of dispersed phase of B component After drying the pellets obtained by the following method at 120 ° C. for 5 hours, an injection molding machine (EC130SXII-4Y manufactured by Toshiba Machine Co., Ltd.) was used with a cylinder temperature of 290 ° C. and a mold. temperature 120
A hollow cylindrical test piece having an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm was molded at ℃ according to the JIS K7218A method. Next, the cross section of the test piece is photographed with an electron scanning microscope at a magnification of 500 times, and 500 dispersed phases of the B component are binarized using image analysis software Image J Fiji to calculate the area of the dispersed phase. The average value of 500 dispersed phases was taken as the average area. However, dispersed phases with an area of less than 1 μm ² were excluded from the calculation.

[Example 1-11, Comparative Example 1-9]
According to the addition amount shown in Table 1, A component and B component were separately supplied to the twin-screw extruder from the first supply port. Here, the first supply port is the root supply port. C component and D component were supplied separately from the second supply port using a side feeder. Extrusion is performed using a vented twin-screw extruder with a diameter of 30 mmΦ (manufactured by Japan Steel Works, Ltd.: TEX30α-31.5BW-2V), screw rotation speed of 200 rpm, discharge rate of 20 kg / h, vent vacuum degree of 3 kPa. It was melted and kneaded to obtain pellets. The extrusion temperature was 290°C.

[Example 12]
Pellets were obtained by melt kneading in the same manner as in Example 10, except that the extrusion temperature was 310°C.

The following materials were used in the examples and comparative examples of the present invention.
(A component)
AI: Polybutylene naphthalate resin obtained in Production Example I <Production Example I>
315.0 parts of 2,6-naphthalene dicarboxylic acid dimethyl ester, 200.0 parts of 1,4-butanediol, and 0.062 parts of tetra-n-butyl titanate were placed in a transesterification reactor, and the temperature of the transesterification reactor was 210°C. The transesterification reaction was carried out for 150 minutes while raising the temperature to . Then, the obtained reaction product was transferred to a polycondensation reactor to initiate the polycondensation reaction. In the polycondensation reaction, the pressure in the polycondensation reaction layer is gradually reduced from normal pressure to 0.13 kPa (1 torr) or less over 40 minutes, and at the same time the temperature is raised to a predetermined reaction temperature of 260°C. C. and a pressure of 0.13 kPa (1 torr), the polycondensation reaction was carried out for 140 minutes. When 140 minutes had passed, the polycondensation reaction was terminated, and the polybutylene naphthalate resin was extracted in the form of strands, which were cut into chips using a cutter while cooling with water. Next, the obtained polybutylene naphthalate resin was solid-phase polymerized for 8 hours at a temperature of 213° C. and a pressure of 0.13 kPa (1 Torr) or less to obtain a polybutylene naphthalate resin.
A-II: Polybutylene terephthalate resin: DURANEX 500FP (product name) (manufactured by Polyplastics Co., Ltd.)

(B component)
BI: Polytetrafluoroethylene: KT-600M (product name) (manufactured by Kitamura Co., Ltd., melting point 325-335° C., 50% particle size 14 μm)
B-II: Polytetrafluoroethylene: Rubron L-5 (product name) (manufactured by Daikin Industries, Ltd., melting point 326-328° C., average particle size 5-7 μm)
B-III: Polytetrafluoroethylene: KT-400M (product name) (manufactured by Kitamura Co., Ltd., melting point 325-335° C., 50% particle size 33 μm)
B-IV: Polytetrafluoroethylene: Lublon L-5F (product name) (manufactured by Daikin Industries, Ltd., melting point 327-330° C., average particle size 3-7 μm)

(C component)
CI: Carbon fiber: PAN-based carbon fiber HT P722 (trade name) (manufactured by Teijin Limited, cut length 3 mm, average fiber diameter 7 μm, polyimide sizing agent)
C-II: Carbon fiber: PAN-based carbon fiber IM P303 (trade name) (manufactured by Teijin Limited, cut length 3 mm, average fiber diameter 5 μm, epoxy sizing agent)

(D component)
DI: Glass fiber: CS-3PE944 (trade name) (manufactured by Nitto Boseki Co., Ltd., round cross section, fiber diameter 13 μm, cut length 3 mm)
D-II: Glass fiber: CSG-3PA830 (trade name) (manufactured by Nitto Boseki Co., Ltd., elliptical cross section, major axis 28 μm, minor axis 7 μm, cut length 3 mm)

<Examples 1 to 12>
For compositions within the claimed range, the results showed excellent wear resistance, low coefficients of friction and high critical PV values.

<Comparative Example 1>
Since the content of component D was less than the lower limit, the dynamic friction coefficient and specific wear amount were large, and the limit PV value was low.

<Comparative Example 2>
Since the content of the C component was less than the lower limit, the result was that the specific wear amount was large and the limit PV value was low.

<Comparative Example 3>
Since the content of the C component in the total of 100 parts by weight of the C component and the D component exceeded the upper limit, the dynamic friction coefficient and the specific wear amount were large, and the limit PV value was low.

<Comparative Example 4>
Since the content of the C component in the total of 100 parts by weight of the C component and the D component was less than the lower limit, the specific wear amount was large and the critical PV value was low.

<Comparative Example 5>
Since the content of the C component exceeded the upper limit, the dynamic friction coefficient and specific wear amount were large, and the limit PV value was low.

<Comparative Example 6>
Since the content of component D exceeded the upper limit, the limit PV value was low.

<Comparative Example 7>
Since the content of the B component was less than the lower limit, the result was that the specific wear amount was large and the limit PV value was low.

<Comparative Example 8>
Since the content of the B component exceeded the upper limit, the specific wear amount was large.

<Comparative Example 9>
Since the A component was not polybutylene naphthalate, the dynamic friction coefficient and specific wear amount were large, and the limit PV value was low.

Claims (4)

(A) Polybutylene naphthalate resin (A component) 100 parts by weight, (B) polytetrafluoroethylene (B component) 5 to 30 parts by weight, (C) carbon fiber (C component) 5 to 50 parts by weight and (D) 5 to 50 parts by weight of glass fiber (component D), wherein the content of component C is 15 to 85 parts by weight in a total of 100 parts by weight of component C and component D. A resin composition characterized by: 2. The resin composition according to claim 1, wherein the dispersed phase of component B has an average area of 5 to 80 μm ² . 3. The resin composition according to claim 1, wherein the C component has an average fiber diameter of 6 to 15 μm. A molded article made of the resin composition according to any one of claims 1 to 3.