Polybutylene naphthalate resin composition and molded article using the same

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

[0001] The present invention relates to a polybutylene naphthalate resin composition having excellent wear resistance, a low coefficient of friction, and a high limiting PV value when a molded article is slid, and a molded article using the same.

Background Art

[0002] Conventionally, aromatic polyester resins have been excellent in mechanical properties, heat resistance, and chemical resistance, and have been widely used in applications such as electric and electronic parts, household appliances, and automotive parts. Among them, polybutylene naphthalate resin has characteristics of being excellent in slidability and hydrolysis resistance compared with polybutylene terephthalate resin and the like, and is therefore used in various gears and polishing pad applications. The properties required for resin members used in sliding applications are wear resistance that does not wear the self-material and the mating material, a low coefficient of friction that suppresses temperature rise during sliding, and preventing the resin member from being unable to withstand the load and fusing within a wide range of load and sliding speed. The product of the limiting surface pressure and speed at which fusion occurs is called the limiting PV value, and is used as an index for the range in which the resin member can be used without fusing.

[0003] Patent Document 1 proposes a resin composition comprising a polybutylene naphthalate resin, a high-density polyethylene resin, and an acid-modified polyethylene resin as a polybutylene naphthalate resin composition excellent in slidability and a sliding part using the same. However, there is no description regarding the limiting PV value, and it is assumed that the usable range is limited because no reinforcing material is added. Patent Document 2 proposes a resin composition comprising an aromatic polyester resin, carbon fiber, and tetrafluoroethylene resin, and Patent Document 3 proposes a resin composition excellent in wear resistance comprising a polyester resin, tetrafluoroethylene resin, and fibrous filler, but there is no description regarding polybutylene naphthalate resin and the limiting PV value, and further improvement in wear resistance is required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] 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.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that by blending polybutylene naphthalate resin with polytetrafluoroethylene, carbon fiber, and glass fiber in specific ratios, the above object can be achieved, and thus the present invention has been completed.

[0007] That is, the above problems are solved by a resin composition containing (A) 100 parts by weight of polybutylene naphthalate resin (component A), (B) 5 to 30 parts by weight of polytetrafluoroethylene (component B), (C) 5 to 50 parts by weight of carbon fiber (component C), and (D) 5 to 50 parts by weight of glass fiber (component D), and the content of component C in 100 parts by weight in total of component C and component D is 15 to 85 parts by weight.

Effects of the Invention

[0008] 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 limiting PV value, and the molded article obtained from the resin composition of the present invention can be suitably used for electric and electronic parts, automotive parts, and building members.

Modes for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described in more detail.

[0010] <Regarding Component A> The polybutylene naphthalate resin, which is Component A of the present invention, can be produced using 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.

[0011] As the naphthalenedicarboxylic acid component, 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid are the main components. However, other dicarboxylic acids can be used in combination as long as the properties are not impaired. Examples of other dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and diphenylether-4,4'-dicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, and oxalic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. One or more of these can be used and can be arbitrarily selected depending on the purpose. The amount of other dicarboxylic acids used is preferably 30 mol% or less, more preferably 20 mol% or less, based on the total acid component. As the ester-forming derivatives of naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate and dimethyl 2,7-naphthalenedicarboxylate are the main components. However, ester-forming derivatives of other dicarboxylic acids can be used in combination as long as the properties are not impaired. Examples of ester-forming derivatives of other dicarboxylic acids include lower dialkyl esters of aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and diphenylether-4,4'-dicarboxylic acid; lower dialkyl esters of alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and lower dialkyl esters of aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, and oxalic acid. One or more of these can be used and can be arbitrarily selected depending on the purpose. The amount of ester-forming derivatives of other dicarboxylic acids used is preferably 30 mol% or less, more preferably 20 mol% or less, based on the total ester-forming derivative component of dicarboxylic acids.

[0012] In addition, a trifunctional or higher polycarboxylic acid component such as a small amount of trimellitic acid may be used, and a small amount of an acid anhydride such as trimellitic anhydride may also be used. Further, a small amount of a hydroxycarboxylic acid such as lactic acid or glycolic acid or its alkyl ester etc. may be used, and it can be arbitrarily selected according to the purpose.

[0013] As the glycol component, 1,4 - butanediol is the main component, but other glycol components can be used in combination within a range that does not impair the properties. Examples of other glycol components include one or more of alkylene glycols such as ethylene glycol, 1,3 - propylene glycol, 1,2 - propylene glycol, neopentyleneglycol, hexamethylene glycol, decamethylene glycol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, poly(oxy)ethylene glycol, poly(oxy)tetramethylene glycol, poly(oxy)methylene glycol, etc. , which can be arbitrarily selected according to the purpose. Further, a small amount of a polyhydric alcohol component such as glycerin may be used. Also, a small amount of an epoxy compound may be used. The usage amount of other glycol components is preferably 30 mol% or less, more preferably 20 mol% or less, based on the total glycol components.

[0014] The usage amount of such a glycol component is preferably 1.1 molar times or more and 1.4 molar times or less with respect to the dicarboxylic acid or the ester - forming derivative of the dicarboxylic acid. When the usage amount of the glycol component is less than 1.1 molar times, the esterification or transesterification reaction may not proceed sufficiently, which is not preferable. Also, when it exceeds 1.4 molar times, although the reason is not clear, the reaction rate becomes slow, and the amount of by - products such as tetrahydrofuran generated from the excess glycol component may be large, which is not preferable.

[0015] In the production of polybutylene naphthalate resin, a titanium compound is used as a polymerization catalyst. As the titanium compound used as the polymerization catalyst, tetraalkyl titanate is preferable. 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. may be mentioned, and these may be used as a mixed titanate. Among these titanium compounds, tetra-n-propyl titanate, tetraisopropyl titanate, and tetra-n-butyl titanate are particularly preferable, and tetra-n-butyl titanate is most preferable. The addition amount of the titanium compound is preferably 10 ppm or more and 60 ppm or less as the titanium atom content in the produced polybutylene naphthalate, and more preferably 15 ppm or more and 30 ppm or less. When the titanium atom content in the produced polybutylene naphthalate exceeds 60 ppm, it is not preferable because the color tone and thermal stability of the resin composition of the present invention may decrease. On the other hand, when the titanium atom content is less than 10 ppm, good polymerization activity cannot be obtained, and it may not be possible to obtain a polybutylene naphthalate resin having a sufficiently high intrinsic viscosity, which is not preferable. The polybutylene naphthalate resin of the present invention is preferably produced via an esterification or transesterification reaction step of a dicarboxylic acid component mainly composed of naphthalenedicarboxylic acid and / or its ester-forming derivative and a glycol component mainly composed of 1,4-butanediol in the presence of a titanium compound, followed by a polycondensation reaction step. However, the temperature at the end of the esterification or transesterification reaction is preferably in the range of 180°C or more and 220°C or less, and more preferably 180°C or more and 210°C or less. When the temperature at the end of the esterification reaction or transesterification reaction exceeds 220°C, the reaction rate increases, but the amount of by-products such as tetrahydrofuran may increase, which is not preferable. Also, when it is less than 180°C, the reaction may not proceed.The reaction product (bis glycol ether and / or its low polymer) obtained by an esterification or transesterification reaction is preferably polycondensed under a reduced pressure of 0.4 kPa (3 Torr) or less at a temperature not lower than the melting point of the polybutylene naphthalate resin and not higher than 270 °C. When the polycondensation reaction temperature exceeds 270 °C, the reaction rate rather decreases and the coloring becomes significant, which is not preferable.

[0016] <Regarding Component B> As the polytetrafluoroethylene which is Component B of the present invention, those known per se can be used, and either fired or unfired polytetrafluoroethylene can be used. However, since polytetrafluoroethylene is liable to reaggregate, powdery polytetrafluoroethylene subjected to a firing treatment or the like is preferable in order to make it difficult to reaggregate. Particularly, polytetrafluoroethylene fired at a firing treatment temperature of 360 °C or higher is preferable. The melting point of polytetrafluoroethylene is preferably 320 to 335 °C as measured by the DSC method in order to make it difficult to reaggregate, more preferably 325 to 335 °C. Further, the average particle size of polytetrafluoroethylene is measured by a method of measuring a dispersion liquid dispersed in perchloroethylene by a light transmission method, and is preferably 0.1 μm to 100 μm more preferably 1 μm to 40 μm, still more preferably 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).

[0017] Further, this polytetrafluoroethylene preferably has a number average molecular weight of 100,000 or more, more preferably 200,000 or more.

[0018] Examples of such polytetrafluoroethylene are commercially available as KTL-620, KTL-450A, KT-600M, and KT-400M from Kitamura Co., Ltd. and are easily available.

[0019] The content of component B is 5 to 30 parts by weight, preferably 7 to 25 parts by weight, more preferably 10 to 20 parts by weight, based on 100 parts by weight of component A. When the content is less than 5 parts by weight and exceeds 30 parts by weight, the wear amount during sliding increases. Furthermore, when the content is less than 5 parts by weight, the limiting PV value also decreases.

[0020] From the viewpoint of achieving low wear properties, it is preferable that component B is dispersed in the resin matrix with a domain size within a specific range. The average area of the dispersed phase of the preferable component B is 5 to 80 μm 2 and more preferably 8 to 70 μm. 2 Here, the average area of the dispersed phase is the average area calculated by performing binarization processing on 500 dispersed phases of component B using image analysis software Image J Fiji with a magnification of 500 times for a cross-section of a molded body using the resin composition and photographing it with a scanning electron microscope. However, dispersed phases with an area of less than 1 μm 2 were excluded from the calculation.

[0021] <Regarding component C> As the carbon fiber which is component C of the present invention, any carbon fiber generally referred to as carbon fiber may be used. For example, PAN-based carbon fibers using polyacrylonitrile as a raw material, pitch-based carbon fibers using petroleum tar or petroleum pitch as a raw material, vapor-grown carbon fibers using hydrocarbons or the like as a raw material, cellulose-based carbon fibers using viscose rayon or the like as a raw material, and the like can be mentioned.

[0022] The average fiber diameter of the carbon fiber is not particularly limited, but is preferably 2 to 20 μm, more preferably 6 to 15 μm, and even 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 appearance of the molded body. The average fiber diameter referred to here was obtained by photographing a cross-section of the molded body using the resin composition with an electron scanning microscope at a magnification of 1800 times, measuring the fiber diameters of 100 carbon fibers, and taking the average value thereof. Further, the carbon fiber may be subjected to a sizing treatment from the viewpoints of productivity and mechanical strength. Examples of the sizing agent include olefin resins, styrene resins, acrylic resins, polyester resins, epoxy resins, and urethane resins, etc., but are not particularly limited. From the viewpoint of processability, the preferable amount of the sizing agent is 0 to 5% by weight, more preferably 0.1 to 4% by weight. The carbon fiber may be coated with a metal layer on the surface of the carbon fiber. Examples of the metal include silver, copper, nickel, and aluminum, etc., and nickel is preferable from the viewpoint of the corrosion resistance of the metal layer.

[0023] The content of the C component is 5 to 50 parts by weight, preferably 8 to 45 parts by weight, more preferably 10 to 40 parts by weight, and even more preferably 15 to 35 parts by weight with respect to 100 parts by weight of the A component. When the content of the C component exceeds 50 parts by weight, the amount of carbon fibers that fall off during sliding increases, so the friction coefficient increases, and accordingly, the temperature rise of the sliding surface accelerates, so the limiting PV value also decreases. On the other hand, when the content is less than 5 parts by weight, the wear amount during sliding increases, and the limiting PV value also decreases.

[0024] <Regarding the D component> As the glass fiber used as the D component of the present invention, any glass fiber may be used as long as it is generally referred to as glass fiber. The glass compositions such as A glass, C glass, and E glass are not particularly limited, and may contain components such as TiO2, SO3, and P2O5 in some cases. However, E glass (alkali-free glass) is more preferable when blended with polybutylene naphthalate resin. The glass fiber is obtained by rapidly cooling molten glass while stretching it by various methods to form a predetermined fibrous shape. The rapid cooling and stretching conditions in such cases are not particularly limited. In addition to a circular cross-section, glass fibers having a shape other than a circle, such as an elliptical shape, a mayu shape, or a three-lobed shape, may be used. When adding a fibrous filler, glass fibers having an elliptical cross-section may be used to suppress the anisotropy of physical properties. In the present invention, glass fibers having an elliptical cross-section may also be used from the same viewpoint. 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 glass fibers having a shape other than a circle may also be used. The glass fiber may be coated or bundled with a resin such as an ethylene / vinyl acetate copolymer, polyurethane, or epoxy resin.

[0025] The content of the D component 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 the A component. When the content of the D component exceeds 50 parts by weight, the limiting PV value decreases. On the other hand, when it is less than 5 parts by weight, the wear amount and the friction coefficient during sliding increase, and the limiting PV value also decreases.

[0026] In the present invention, the content of Component C in a total of 100 parts by weight of Component C and Component D is 15 to 85 parts by weight, preferably 20 to 80 parts by weight, more preferably 25 to 75 parts by weight, and still more preferably 30 to 70 parts by weight. When the content is less than 15 parts by weight, the wear amount during sliding increases and the limiting PV also decreases. On the other hand, when it exceeds 85 parts by weight, the dynamic friction coefficient and the wear amount during sliding increase, and the limiting PV value also decreases. Although the reasons for these are not clear, they can be speculated as follows. That is, the polybutylene naphthalate resin containing glass fiber has a low friction coefficient, while the friction coefficient at the initial stage of sliding tends to be high. By using it in combination with carbon fiber, while alleviating the increase in the initial friction coefficient, the low friction coefficient over the entire sliding time can be maintained low, so that a high limiting PV value and a low wear amount can be obtained.

[0027] In addition, the resin composition of the present invention can contain other thermoplastic resins within a range not contrary to the gist of the present invention, and optionally antioxidants, impact modifiers, plasticizers, inorganic fillers other than Component C and Component D, non-halogen flame retardants, colorants, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants excluding Component B, dispersants, flow modifiers, crystal nucleating agents and other additives.

[0028] <Manufacturing method of resin composition> To produce the resin composition of the present invention, any method can be adopted. For example, a method of preliminarily mixing each component and optionally other components, then melt-kneading and pelletizing can be mentioned. As means for preliminary mixing, a Nauta mixer, V-type blender, Henschel mixer, mechanochemical device, extrusion mixer, etc. can be mentioned. In preliminary mixing, granulation can also be carried out in some cases by an extrusion granulator, briquetting machine, etc. After preliminary mixing, melt-kneading is carried out with a melt-kneading machine typified by a vented twin-screw extruder, and pelletizing is carried out with equipment such as a pelletizer. Other melt-kneading machines include a Banbury mixer, kneading rolls, a constant-temperature stirring container, etc., but a vented twin-screw extruder is preferred. Alternatively, a method can also be adopted in which each component and optionally other components are independently supplied to a melt-kneading machine typified by a twin-screw extruder without preliminary mixing.

[0029] <Regarding the molded article> A molded article made using the resin composition of the present invention can be obtained by molding the pellets produced as described above. Preferably, it is 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 a supercritical fluid), insert molding, in-mold coating molding, adiabatic mold molding, rapid heating and cooling mold molding, two-color molding, multi-color molding, sandwich molding, and ultra-high-speed injection molding, etc. can be mentioned. Also, the molding can be selected from either the cold runner system or the hot runner system. In extrusion molding, a method of obtaining a molded article by extruding a round bar and then cutting it into a disc shape, or a method of obtaining a molded article by extruding a thick sheet and then punching it into a predetermined shape can be adopted. [Examples]

[0030] Hereinafter, embodiments of carrying out the present invention will be described by way of examples, but the present invention is not limited thereto. Also, the evaluation of various physical properties was carried out by the following methods.

[0031] [Evaluation of the resin composition] (1) Coefficient of kinetic friction The pellets obtained by the following method were dried at 120 °C for 5 hours and then injection-molded by 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 in accordance with JIS K7218A method to form 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 coefficient of kinetic friction when the test piece was slid against a test piece of the same shape made of carbon steel (S45C) in accordance with JIS K7218A method was measured. The test was carried out 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 coefficient of kinetic friction between 300 and 3000 m of sliding distance was measured at 1-second intervals, and their average value was taken as the coefficient of kinetic friction. The coefficient of kinetic friction needs to be 0.20 or less.

[0032] (2) Specific wear rate The pellets obtained by the following method were 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 test piece of the same shape made of carbon steel (S45C) 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 using a friction and wear tester (EFM-3-G, manufactured by Orientec Co., Ltd.) in accordance with JIS K7218A method. 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 rate was calculated using the calculation formula described in JIS K7218A method. The test was carried out 5 times, and their average value was taken as the specific wear rate of the composition. The specific wear rate needs to be 7×10 -6 mm 3 / N·m or less.

[0033] (3) Limiting PV value The pellets obtained by the following method were molded in the same manner as (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 test piece of the same shape made of carbon steel (S45C) in accordance with JIS K7218A method. The test started at 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 deformation of the test piece, generation of rapid wear powder, and inability to control the pressing force (load fluctuation of ±50 N or more from the set load) occurred" - 100 N was defined as the limiting load, and the product of the limiting load and the sliding speed was defined as the limiting PV value. The test was conducted 5 times, and the average value was defined as the limiting PV value of the composition. The limiting PV value needs to be 60 MPa·m / min or more.

[0034] (4) Average area of the dispersed phase of component B The pellets obtained by the following method were dried at 120°C for 5 hours and then injection molded at a cylinder temperature of 290°C and a mold temperature of 120 °C in accordance with JIS K7218A method to form 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. Next, the cross-section of the test piece was photographed with an electron scanning microscope at a magnification of 500 times, and binarization processing was performed on 500 dispersed phases of component B using image analysis software Image J Fiji to calculate the area of the dispersed phase, and the average value of 500 dispersed phases was defined as the average area. However, dispersed phases with an area of less than 1 μm 2 were excluded from the calculation.

[0035] [Examples 1-11, Comparative Examples 1-9] According to the addition amounts shown in Table 1, component A and component B were separately supplied to a twin-screw extruder from the first supply port. Here, the first supply port refers to the supply port at the root. Component C and component D were separately supplied using a side feeder from the second supply port. Extrusion was performed using a vented twin-screw extruder with a diameter of 30 mmΦ (manufactured by Japan Steel Works, Ltd.: TEX30α-31.5BW-2V) at a screw rotation speed of 200 rpm, a discharge rate of 20 kg / h, and a vent vacuum degree of 3 kPa to obtain pellets. The extrusion temperature was 290°C.

[0036] [Example 12] Pellets were obtained by melt-kneading in the same manner as in Example 10, except that the extrusion temperature was 310°C.

[0037] The following materials were used in the examples and comparative examples of the present invention. (Component A) A-I: Polybutylene naphthalate resin obtained in Production Example I [Production Example I]< 315.0 parts of dimethyl 2,6-naphthalenedicarboxylate, 200.0 parts of 1,4-butanediol, and 0.062 part of tetra-n-butyl titanate were placed in a transesterification reaction tank, and the transesterification reaction was carried out for 150 minutes while raising the temperature so that the transesterification reaction tank reached 210°C. Then, the obtained reaction product was transferred to a polycondensation reaction tank to start the polycondensation reaction. The polycondensation reaction was gradually depressurized from normal pressure to 0.13 kPa (1 torr) or less over 40 minutes in the polycondensation reaction layer, and at the same time, the temperature was raised to a predetermined reaction temperature of 260°C. Thereafter, the polycondensation reaction was carried out for 140 minutes while maintaining the polycondensation reaction temperature at 260°C and the pressure at 0.13 kPa (1 torr). When 140 minutes had elapsed, the polycondensation reaction was terminated, and the polybutylene naphthalate resin was extruded in a strand shape and cut into chips using a cutter while cooling with water. Next, the obtained polybutylene naphthalate resin was subjected to solid-phase polymerization for 8 hours under the conditions of 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.)

[0038] (Component B) B-I: Polytetrafluoroethylene: KT-600M (product name) (manufactured by Kitamura Co., Ltd., melting point 325 - 335°C, 50% particle diameter 14 μm) B-II: Polytetrafluoroethylene: Rubron L-5 (product name) (manufactured by Daikin Industries, Ltd., melting point 326 - 328°C, average particle diameter 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: Rubron L-5F (Product Name) (manufactured by Daikin Industries, Ltd., melting point 327 - 330 °C, average particle size 3 - 7 μm)

[0039] (Component C) C-I: Carbon fiber: PAN-based carbon fiber HT P722 (Trade Name) (manufactured by Teijin Limited, cut length 3 mm, average fiber diameter 7 μm, polyimide-based 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-based sizing agent)

[0040] (Component D) D-I: 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)

[0041]

Table 1

[0042] <Examples 1 - 12> Since it is a composition within the scope of the claims, it showed excellent wear resistance, low friction coefficient and high limiting PV value as a result.

[0043] <Comparative Example 1> Since the content of Component D was less than the lower limit, the dynamic friction coefficient and specific wear rate were large, and the limiting PV value was low as a result.

[0044] <Comparative Example 2> Since the content of Component C was less than the lower limit, the specific wear rate was large, and the limiting PV value was low as a result.

[0045] <Comparative Example 3> Since the content of Component C exceeded the upper limit in a total of 100 parts by weight of Components C and D, the kinetic friction coefficient and the specific wear rate were large, resulting in a low limiting PV value.

[0046] <Comparative Example 4> Since the content of Component C was less than the lower limit in a total of 100 parts by weight of Components C and D, the specific wear rate was large, resulting in a low limiting PV value.

[0047] <Comparative Example 5> Since the content of Component C exceeded the upper limit, the kinetic friction coefficient and the specific wear rate were large, resulting in a low limiting PV value.

[0048] <Comparative Example 6> Since the content of Component D exceeded the upper limit, the limiting PV value was low.

[0049] <Comparative Example 7> Since the content of Component B was less than the lower limit, the specific wear rate was large, resulting in a low limiting PV value.

[0050] <Comparative Example 8> Since the content of Component B exceeded the upper limit, the specific wear rate was large.

[0051] <Comparative Example 9> Since Component A was not polybutylene naphthalate, the kinetic friction coefficient and the specific wear rate were large, resulting in a low limiting PV value.

Claims

1. (A) A resin composition containing 100 parts by weight of polybutylene naphthalate resin (component A), 5 to 30 parts by weight of particulate polytetrafluoroethylene (component B), 5 to 50 parts by weight of carbon fiber (component C), and 5 to 50 parts by weight of glass fiber (component D), wherein the content of component C in a total of 100 parts by weight of components C and D is 15 to 85 parts by weight.

2. The average area of the dispersed phase of component B is 5 to 80 µm ２ The resin composition according to claim 1, characterized in that it is so.

3. The resin composition according to claim 1 or 2, wherein the average fiber diameter of component C is 6 to 15 μm.

4. A molded article comprising the resin composition according to any one of claims 1 to 3.

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