Polyether ether ketone resin composition and molded article

Abstract

Provided are: a polyether ether ketone resin composition containing (A) 40-80 mass% polyether ether ketone resin, (B) 5-30 mass% carbon fibers, (C) 5-25 mass% graphite, and (D) 5-25 mass% polytetrafluoroethylene; and a molded article formed by molding the polyether ether ketone resin composition. The (D) polytetrafluoroethylene preferably exhibits a weight loss rate of 0.5 mass% or less when heated from 30°C to 400°C at a temperature increase rate of 10°C / min in the presence of an airflow.

Description

Polyether ketone resin composition and molded article

[0001] The present invention relates to a polyether ketone resin composition and a molded article.

[0002] Wholly aromatic ether ketone resins are also known by the abbreviation PAEK (polyaryl ether ketone), and products on the market include PEEK (polyether ether ketone), PEK (polyether ketone), PEKK (polyether ketone ketone), PEKEKK (polyether ketone ether ketone ketone), etc. Wholly aromatic ether ketone resins are excellent in mechanical properties, heat resistance, chemical resistance, etc., and are widely used in fields where such properties are required.

[0003] On the other hand, even though the wholly aromatic ether ketone resin has the above-mentioned excellent properties, when it is used in a sliding member, it may be subject to wear. Therefore, a resin composition that imparts sliding properties, particularly to PEEK (polyether ether ketone), has been proposed (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2009-286956

[0005] While the resin composition containing PEEK of Patent Document 1 has the characteristic of excellent fluidity, such a resin composition with excellent fluidity is prone to generating burrs during molding, and requires post-processing such as deburring after molding. Furthermore, in order to maintain sliding properties, precise surface finishing and the like are added, which significantly reduces productivity.

[0006] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a polyether ketone resin composition and a molded article thereof which have excellent sliding properties and little generation of burrs.

[0007] One aspect of the present invention that solves the above-mentioned problems is as follows: (1) A polyether ketone resin composition containing (A) 40 to 80 mass% of a polyether ketone resin, (B) 5 to 30 mass% of a carbon fiber, (C) 5 to 25 mass% of graphite, and (D) 5 to 25 mass% of polytetrafluoroethylene.

[0008] (2) The polyether ketone resin composition according to (1), wherein the (D) polytetrafluoroethylene has a weight loss rate of 0.5% by mass or less when heated from 30°C to 400°C at a temperature increase rate of 10°C / min in an air flow.

[0009] (3) The polyether ketone resin composition according to (1) or (2), wherein the median diameter (D50) of the graphite (C) is 30 to 80 μm.

[0010] (4) The polyether ketone resin composition according to any one of (1) to (3), wherein the polyether ketone resin (A) has a fluoride ion concentration of 80 μg / g or less as measured by combustion ion chromatography.

[0011] (5) The polyether ketone resin composition according to any one of (1) to (4), which is for use in a sliding member.

[0012] (6) A molded article obtained by molding the polyether ketone resin composition according to any one of (1) to (5).

[0013] (7) The molded article according to (6) above, which is a sliding member.

[0014] According to the present invention, it is possible to provide a polyether ketone resin composition that has excellent sliding properties and generates little burrs.

[0015] The polyether ketone resin composition of the present embodiment contains (A) 40 to 80 mass% of polyether ketone resin, (B) 5 to 30 mass% of carbon fiber, (C) 5 to 25 mass% of graphite, and (D) 5 to 25 mass% of polytetrafluoroethylene.

[0016] While resin compositions with excellent fluidity have excellent fluidity, they suffer from the drawback of being prone to burr formation. In this embodiment, (A) polyether ketone resin has a faster crystallization rate than PEEK (polyether ether ketone), and therefore is less likely to generate burrs during molding compared to PEEK. Furthermore, (A) polyether ketone resin has excellent sliding properties, and since it contains (B) carbon fiber, (C) graphite, and (D) polytetrafluorotoluene in predetermined proportions, a resin composition with excellent sliding properties and reduced burr formation can be obtained. In other words, by containing all of components (A) to (D) in predetermined proportions, the roles of each component work together to achieve the above-mentioned effects. Each component will be described in detail below.

[0017] [(A) Polyetherketone Resin] The polyetherketone resin composition of this embodiment contains 40 to 80 mass% of (A) polyetherketone resin as a base resin. (A) Polyetherketone resin is a resin having a phenyl ketone structure and a phenyl ether structure as main structures. Polyetherketone resins are excellent in heat resistance, mechanical strength, moldability, etc., and have a faster crystallization rate than PEEK (polyetheretherketone), so they are less likely to produce burrs during molding.

[0018] In this embodiment, the polyether ketone resin (A) is contained in an amount of 40 to 80% by mass. If the amount is less than 40% by mass, the continuous layer of the resin becomes relatively small, and the force holding the other components in place under repeated stress, such as in a sliding field, is insufficient, causing them to fall off and preventing the improvement of sliding properties. If the amount exceeds 80% by mass, the amount of other components that improve the sliding properties must be reduced, preventing the improvement of sliding properties. The content of the polyether ketone resin (A) is preferably 42.5 to 77.5% by mass, more preferably 45 to 75% by mass, and even more preferably 47.5 to 72.5% by mass.

[0019] The polyether ketone resin (A) preferably has a fluoride ion concentration of 80 μg / g or less, more preferably 60 μg / g or less, and even more preferably 40 μg / g or less, as measured by combustion ion chromatography. A fluoride ion concentration of 80 μg / g or less can reduce the generation of hydrofluoric acid during melt-kneading and other processes. Polyether ketone resins can generally be obtained by reacting 4,4'-difluorobenzophenone with an excess amount of a bisphenol compound. Alternatively, they can be obtained by reacting a mixture of terephthalic acid dichloride and isophthalic acid dichloride with diphenyl ether in the presence of hydrogen fluoride and boron fluoride. However, such a synthesis method contaminates the product with fluorine compounds, which can cause the generation of hydrofluoric acid. Therefore, polyether ketone resins are preferably synthesized using the method described in JP 2009-227961 A. According to this method, since no fluorine-containing compound is used in the synthesis process, it is possible to suppress the inclusion of fluorine compounds in the product. That is, as described above, it is possible to obtain a polyether ketone resin having a fluoride ion concentration of 80 μg / g or less as measured by combustion ion chromatography.

[0020] The polyether ketone resin (A) preferably has a melt viscosity of 100 to 300 Pa s as measured in accordance with ISO 11443 using a capillary rheometer at a cylinder temperature of 400°C and a shear rate of 1000 / sec. The method for adjusting the melt viscosity is not particularly limited, but the melt viscosity can be adjusted to any desired value by controlling the reaction time in the above-mentioned method for synthesizing the polyether ketone resin.

[0021] [(B) Carbon Fiber] The polyether ketone resin composition of this embodiment contains 5 to 30 mass % of (B) carbon fiber, which contributes to improving sliding properties.

[0022] The (B) carbon fiber may be either a pitch-based or PAN-based fiber, as classified based on the raw material. The (B) carbon fiber is preferably a pitch-based carbon fiber, which has high sliding properties. The baking temperature of the (B) carbon fiber is not particularly limited, but graphitized (graphite) fibers baked at a high temperature of 2000°C or higher are preferred, as they are less likely to cause wear and damage to the mating material.

[0023] In this embodiment, the (B) carbon fiber can be obtained by, for example, using a carbon fiber raw material having a fiber length of 3 to 10 mm and a fiber diameter of 2 to 10 μm, and melt-kneading it together with other components.

[0024] In this embodiment, the (B) carbon fiber is contained in an amount of 5 to 30% by mass, but if the amount is less than 5% by mass, the sliding properties of the carbon fiber are not fully exhibited, and if the amount is more than 30% by mass, friction and wear increase due to collisions between the carbon fibers, making it impossible to obtain excellent sliding properties. The (B) carbon fiber content is preferably 5 to 27.5% by mass, more preferably 7.5 to 25% by mass, and even more preferably 7.5 to 22.5% by mass.

[0025] [Graphite (C)] The polyether ketone resin composition of this embodiment contains 5 to 25 mass % of graphite (C), which contributes to improving sliding properties.

[0026] The (C) graphite is not particularly limited, and includes flake graphite, scaly graphite, artificial graphite, and earthy graphite, and any of these can be used. The median diameter (D50) of the (C) graphite is preferably 30 to 80 μm, more preferably 35 to 75 μm, and even more preferably 40 to 70 μm. A median diameter of 30 to 80 μm can further improve sliding properties. The median diameter (D50) refers to the particle size (D50) at 50% cumulative volume in the particle size distribution of graphite determined by laser diffraction scattering.

[0027] In this embodiment, the graphite (C) is contained in an amount of 5 to 25% by mass, but if the amount is less than 5% by mass, the sliding properties of the graphite are not fully exhibited, and if the amount is more than 25% by mass, excessive graphite falls off, making it impossible to obtain excellent sliding properties. The amount of graphite (C) contained is preferably 5 to 22.5% by mass, and more preferably 7.5 to 22.5% by mass.

[0028] [(D) Polytetrafluoroethylene] The polyether ketone resin composition of the present embodiment contains 5 to 25 mass % of (D) polytetrafluoroethylene. By including (D) polytetrafluoroethylene, sliding properties can be imparted.

[0029] In this embodiment, the polytetrafluoroethylene (D) preferably has a weight loss rate of 0.5% by mass or less when heated from 30°C to 400°C at a temperature increase rate of 10°C / min in an air flow. If the weight loss rate is 0.5% by mass or less, heat resistance is high and generation of hydrofluoric acid can be suppressed. The weight loss rate is more preferably 0 to 0.3% by mass, and even more preferably 0 to 0.1% by mass.

[0030] In this embodiment, the polytetrafluoroethylene (D) is contained in an amount of 5 to 25% by mass, but if the amount is less than 5% by mass, the sliding properties of the polytetrafluoroethylene are not fully exhibited, and if the amount is more than 25% by mass, excessive polytetrafluoroethylene falls off, making it impossible to obtain excellent sliding properties. The content of the polytetrafluoroethylene (D) is preferably 5 to 22.5% by mass, and more preferably 7.5 to 22.5% by mass.

[0031] [Other Components] In the present embodiment, if necessary, one or more of general additives for thermoplastic resins, such as lubricants, release agents, antistatic agents, surfactants, flame retardants, organic polymer materials, inorganic or organic powdery or plate-like fillers, etc. may be added.

[0032] The polyether ketone resin composition of the present embodiment described above has excellent sliding properties and is therefore suitable for use in sliding members, of which the molded articles described below are examples.

[0033] <Molded Article> The molded article of the present embodiment contains the polyether ketone resin composition of the present embodiment described above, and therefore exhibits the effects of excellent sliding properties and reduced burr generation.

[0034] The method for producing the molded article of the present embodiment is not particularly limited, and any known method can be used. For example, the molded article can be produced by feeding the polyether ketone resin composition of the present embodiment into an extruder, melt-kneading the composition, and pelletizing the pellets, and then feeding the pellets into an injection molding machine equipped with a predetermined mold and injection molding the pellets.

[0035] The molded article of this embodiment has excellent sliding properties and can therefore be suitably used as a sliding member, for example, in the form of a gear, thrust, bearing, seal ring, etc. in parts such as engines, motors, brakes, transmissions, clutches, and dampers.

[0036] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0037] [Examples 1 to 10, Comparative Examples 1 to 11] In each Example and Comparative Example, the raw material components shown in Tables 1 and 2 were melt-kneaded in the proportions shown in Tables 1 and 2 using a twin-screw extruder ("ZSK26MEGA compounder" manufactured by Coperion Co., Ltd.) under the following extrusion conditions to obtain pellets of a polyether ketone resin composition. (Extrusion conditions) Cylinder temperature: 400°C (Examples 1 to 10, Comparative Examples 1 to 7) 380°C (Comparative Examples 8 to 11) Screw rotation speed: 200 rpm

[0038] Details of each raw material component used are shown below. (A) Polyether ketone resin PEK1: Polyether ketone resin produced by the production method described in JP 2009-227961 A (melt viscosity: 220 Pa·s, fluoride ions: not detected) PEK2: PEK, G22 manufactured by Victrex (melt viscosity: 190 Pa·s, fluoride ions: 759 μg / g) (A') Polyether ether ketone resin PEEK: PEEK, 450G manufactured by Victrex (melt viscosity: 400 Pa·s) (B) Carbon fiber CF: SGL Carbon Fibers carbon fiber, SIGRAFIL (registered trademark) C C6-4.0 / 240-T190 (chopped strand, fiber length: 6 mm, fiber diameter: 7 μm) (C) Graphite・GP1: Fuji Graphite Industrial Co., Ltd., artificial graphite, G70 (median diameter (D50): 66 μm) ・GP2: Fuji Graphite Industrial Co., Ltd., flake graphite, -199.5 (median diameter (D50): 57 μm) ・GP3: Fuji Graphite Industrial Co., Ltd., artificial graphite, G-4A (median diameter (D50): 4 μm) (D) Polytetrafluoroethylene ・PTFE1: Kitamura Co., Ltd., PTFE, KT-600M (weight reduction rate: 0 mass%) ・PTFE2: Kitamura Co., Ltd., PTFE, KTL-610 (weight reduction rate: 0.9 mass%)

[0039] <Evaluation of Raw Material Components> (1) Melt Viscosity The melt viscosity of the polyether ketone resin and the polyether ether ketone resin was measured in accordance with ISO 11443 using a capillary rheometer ("Capilograph 1D" manufactured by Toyo Seiki Seisaku-sho, Ltd.) with an orifice having an inner diameter of 2 mm and a length of 60 mm under the following conditions: (Measurement Conditions) Cylinder temperature: 400°C (PEK1, PEK2) 380°C (PEEK) Shear rate: 1000 / sec Residence time: 10 minutes (2) Fluoride Ion Concentration The fluoride ion concentration of the polyether ketone resin and the polyether ether ketone resin was measured by combustion ion chromatography under the following conditions: (Measurement conditions) Ion chromatograph: "ICS1600" manufactured by Thermo Fisher Scientific Combustion pretreatment device: "AQF-100" manufactured by Mitsubishi Chemical Analytech Co., Ltd. Sample: 50 mg Heater: Inlet Temp / 900°C, Outlet Temp / 1000°C Absorbent: H ２ O ２ 900ppm, internal standard: PO ４ ３－ 25 ppm (3) Weight Loss Rate The weight loss rate of polytetrafluoroethylene was measured when it was heated from 30°C to 400°C at a temperature increase rate of 10°C / min in an air flow using a thermogravimetric and differential thermal analyzer (TG / DTA, manufactured by Seiko Instruments Inc.).

[0040] <Evaluation of Resin Composition> (1) Amount of Hydrofluoric Acid Generated The concentration of hydrofluoric acid around the molten resin was measured 30 cm above the molten resin outlet of the extruder die using a gas sampler (GV-100 type, manufactured by Gastec Corporation) and a hydrofluoric acid detector tube (17LL, manufactured by Gastec Corporation). The measurement results are shown in Tables 1 and 2. The amount of hydrofluoric acid generated was rated as "good" when less than 3 ppm, "passable" when 3 to 10 ppm, and "unacceptable" when more than 10 ppm. (2) Coefficient of Friction The obtained pellets of the Examples and Comparative Examples were molded using a molding machine (α-S100iA, manufactured by Fanuc Corporation) under the following molding conditions to obtain flat plate-shaped test pieces of 80 mm x 80 mm x 3 mm. Using the obtained flat test pieces and cylindrical test pieces made of SUS304, the friction coefficient was measured using a friction and wear tester ("EFM-III-EN" manufactured by Orientec Co., Ltd.) under the following conditions. The measurement results are shown in Tables 1 and 2. A friction coefficient of less than 0.25 was considered "good", a friction coefficient of 0.25 to 0.30 was considered "passable", and a friction coefficient of more than 0.30 was considered "unacceptable". (Molding conditions) Cylinder temperature: 400°C (Examples 1 to 10, Comparative Examples 1 to 7) 380°C (Comparative Examples 8 to 11) Mold temperature: 200°C Injection speed: 20 mm / sec Holding pressure: 120 MPa (Measurement conditions) Form: Thrust Surface pressure: 0.49 MPa Rotation speed: 30 cm / s Time: 8 hours (3) Specific Wear Rate The specific wear rate was measured in the same manner as the friction coefficient. The measurement results are shown in Tables 1 and 2. The specific wear rate is 3.0 x 10 －３ (mm ３ / (N·km)) is "good" and 3.0×10 －３ ~5.0 x 10 －３ (mm ３ / (N km)) is "Acceptable", and 5.0 x 10 －３ (mm ３ / (N·km)) was rated as "unacceptable". (4) Presence or absence of burrs The obtained pellets of the examples and comparative examples were molded using an injection molding machine ("α-S100iA" manufactured by FANUC CORPORATION) under the following molding conditions to obtain flat plate-shaped test pieces of 80 mm x 80 mm x 3 mm. The obtained flat plate-shaped test pieces were visually observed for the presence or absence of burrs. When no burrs were generated, the evaluation was made as "absent", and when burrs were generated, the evaluation was made as "present". The evaluation results are shown in Tables 1 and 2. When burrs were "absent", the test piece was rated as "good", and when burrs were "present", the test piece was rated as "unacceptable". (Molding conditions) Cylinder temperature: 400°C (Examples 1 to 10, Comparative Examples 1 to 7) 380°C (Comparative Examples 8 to 11) Mold temperature: 200°C Injection speed: 20 mm / sec Holding pressure: 120 MPa (5) Overall evaluation In the evaluation of the above (1) to (4), points were assigned as follows: Good: 2, Fair: 1, and Poor: -1. When the total of the points was 7 or more, the evaluation was A, when it was 5 to 6, it was B, when it was 2 to 4, it was C, and when it was 1 or less, it was D.

[0041]

[0042]

[0043] As can be seen from Tables 1 and 2, in Examples 1 to 10, the evaluation results for the amount of hydrofluoric acid generated, the wear coefficient, the specific wear rate, and the presence or absence of burrs were all good. In contrast, at least one evaluation was poor in Comparative Examples 1 to 11. In particular, looking at Comparative Examples 1 to 7, it can be seen that the sliding properties are poor unless all of (B) carbon fiber, (C) graphite, and (D) polytetrafluoroethylene are contained as specified in this embodiment.

Claims

1. A polyetherketone resin composition containing: (A) 40 to 80 mass% polyetherketone resin; (B) 5 to 30 mass% carbon fiber; (C) 5 to 25 mass% graphite; and (D) 5 to 25 mass% polytetrafluoroethylene.

2. A polyether ketone resin composition as described in claim 1, wherein the (D) polytetrafluoroethylene has a weight loss rate of 0.5 mass% or less when heated from 30°C to 400°C at a heating rate of 10°C / min in an air flow.

3. The polyether ketone resin composition according to claim 1 or 2, wherein the median diameter (D50) of the graphite (C) is 30 to 80 μm.

4. A polyetherketone resin composition according to claim 1 or 2, wherein the polyetherketone resin (A) has a fluoride ion concentration of 80 μg / g or less as measured by combustion ion chromatography.

5. The polyether ketone resin composition according to claim 1 or 2, which is for use in sliding parts.

6. A molded article obtained by molding the polyether ketone resin composition according to claim 1 or 2.

7. The molded article according to claim 6, which is a sliding member.

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