Resin composition and molded article

Abstract

To provide a resin composition capable of producing a molded article enhanced in both abrasion resistance and durability, and a molded article using the resin composition as a molding material.SOLUTION: The resin composition contains a semi-aromatic polyamide having a structural unit represented by formula (1), a maleic anhydride-modified ultrahigh molecular weight polyethylene, and carbon fibers. In Formula (1), Ar1 represents a phenylene or naphthylene group, and a plurality of Ar1 contained in the semi-aromatic polyamide may be the same as or different from each other. P is an integer of 4 to 12. The mass ratio of the content of the carbon fiber to the semi-aromatic polyamide is 0.25 or more and 0.95 or less, and the mass ratio of the content of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 or more and 6.5 or less. [Chemical Formula 1] SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a resin composition and a molded article. [Background technology]

[0002] Polyamides are known to have excellent abrasion resistance and strength, and are widely used as molding materials for various components such as machine parts. For example, Patent Document 1 discloses a resin composition for extrusion molding that contains a semi-aromatic polyamide and a carbodiimide compound in a specific ratio. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-10587 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when applied to applications such as gears and other mechanical parts, further improvements are required in the durability and wear resistance under high surface pressure of molded articles made from conventional resin compositions containing polyamide resins as molding materials. An object of the present disclosure is to provide a resin composition capable of producing a molded article having improved durability and abrasion resistance under high surface pressure, and a molded article using this resin composition as a molding material. [Means for solving the problem]

[0005] In order to solve the above problems, the present disclosure includes the following aspects.

[0006] [1] A resin composition containing a semi-aromatic polyamide having a structural unit represented by the following formula (1), a maleic anhydride-modified ultra-high molecular weight polyethylene, and a carbon fiber, wherein the mass ratio of the content of the carbon fiber to the semi-aromatic polyamide is 0.25 or more and 0.95 or less, and the mass ratio of the content of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 or more and 6.5 or less.

[0007] [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12.

[0008] [2] The semi-aromatic polyamide is represented by the formula (1) Ar 1 The resin composition according to [1] above, which is a semi-aromatic polyamide having a structural unit in which represents a 1,4-phenylene group and p is 9 or 10.

[0009] [3] The resin composition according to [1] or [2], wherein the melt mass-flow rate (MFR) of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g is 1 g / 10 min or more and 300 g / 10 min or less.

[0010] [4] The resin composition according to any one of [1] to [3], wherein the content of the carbon fiber is 20 mass % or more based on the total mass of the resin composition. [5] The resin composition according to any one of [1] to [4], wherein the maleic anhydride-modified ultra-high molecular weight polyethylene has an intrinsic viscosity of 10 dL / g or more and 40 dL / g or less.

[0011] [6] A molded article comprising the resin composition according to any one of [1] to [5] above. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a resin composition that can be used to produce a molded article that has durability and reduced wear under high surface pressure, and a molded article that uses this resin composition as a molding material. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a photographed plan view of an example of a resin gear manufactured in an example. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Resin composition) One embodiment of the resin composition contains a semi-aromatic polyamide having a structural unit represented by formula (1), maleic anhydride-modified ultra-high molecular weight polyethylene, and carbon fibers. In the resin composition of this embodiment, the mass ratio of the carbon fiber to the semi-aromatic polyamide is 0.25 to 0.95, and the mass ratio of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 to 6.5.

[0015] <Semi-aromatic polyamide> The semi-aromatic polyamide in this embodiment is a semi-aromatic polyamide having a structural unit represented by the following formula (1).

[0016] [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12.

[0017] The semi-aromatic polyamide can be obtained as a polymer of an aliphatic diamine and an aromatic dicarboxylic acid. The aliphatic diamine may be an aliphatic diamine having 4 to 12 carbon atoms. Examples of the aliphatic diamine having 4 to 12 carbon atoms include 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine. The aliphatic diamine may be used alone or in combination of two or more. Examples of aromatic dicarboxylic acids include terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc. The aromatic dicarboxylic acids may be used alone or in combination of two or more.

[0018] From the viewpoint of excellent durability and heat resistance of the resulting molded article, Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p may be 9 or 10 from the viewpoint of being more excellent in low water absorbency.

[0019] From the viewpoint of obtaining a molded article with superior durability, Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 and may be the same or different. p may be 10 from the viewpoint that the effect of improving durability and wear resistance under high surface pressure by using it in combination with maleic anhydride-modified ultra-high molecular weight polyethylene is further improved.

[0020] The Ar 1 The phenylene group in Ar may be a 1,4-phenylene group or a 1,3-phenylene group. 1 The naphthylene group includes a 2,6-naphthylene group and a 2,7-naphthylene group.

[0021] Preferably, in the formula (1), Ar 1represents a 1,4-phenylene group, and p may be an integer of 4 to 12. More preferably, in the formula (1), Ar 1 represents a 1,4-phenylene group, and p may be 9 or 10. Particularly preferably, in the formula (1), Ar 1 represents a 1,4-phenylene group, and p may be 10.

[0022] In the semi-aromatic polyamide, the content of the structural unit represented by the formula (1) is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units in the semi-aromatic polyamide (100%).

[0023] In the semi-aromatic polyamide, the structural unit represented by the formula (1) is Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar groups contained in the semi-aromatic polyamide 1 may be the same or different, and the content of structural units in which p is 9 or 10 is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units in the semi-aromatic polyamide (100%).

[0024] In the semi-aromatic polyamide, the structural unit represented by the formula (1) is Ar 1 The content of structural units in which represents a 1,4-phenylene group and p is 9 or 10 is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units (100%) in the semi-aromatic polyamide.

[0025] In the semi-aromatic polyamide, the structural unit represented by the formula (1) is Ar 1The content of structural units in which represents a 1,4-phenylene group and p is 10 is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units (100%) in the semi-aromatic polyamide.

[0026] The melt mass flow rate (MFR) of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g may be 1 g / 10 min or more, 3 g / 10 min or more, or 5 g / 10 min or more. On the other hand, the MFR of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g may be 300 g / 10 min or less, 250 g / 10 min or less, or 200 g / 10 min or less. The upper and lower limits of the MFR of the semi-aromatic polyamides exemplified above can be freely combined. The MFR of the semi-aromatic polyamide, measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g, may be, for example, 1 g / 10 min or more and 300 g / 10 min or less, 3 g / 10 min or more and 250 g / 10 min or less, or 5 g / 10 min or more and 250 g / 10 min or less.

[0027] In another aspect, the MFR of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 320°C and a load of 2160 g may be 1 g / 10 min or more, 3 g / 10 min or more, or 5 g / 10 min or more. On the other hand, the MFR of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 320°C and a load of 2160 g may be 300 g / 10 min or less, 250 g / 10 min or less, or 200 g / 10 min or less. The upper and lower limits of the MFR of the semi-aromatic polyamides exemplified above can be freely combined. The MFR of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 320°C and a load of 2160 g may be, for example, 1 g / 10 min or more and 300 g / 10 min or less, 3 g / 10 min or more and 250 g / 10 min or less, or 5 g / 10 min or more and 200 g / 10 min or less.

[0028] A resin composition containing a semi-aromatic polyamide having an MFR within the above range can exhibit even better durability. The MFR of the semi-aromatic polyamide can be controlled by appropriately adjusting conditions related to the reaction efficiency of the polymerization reaction, such as the raw material monomer, catalyst, and reaction time.

[0029] The resin composition of the present embodiment may contain one type of semi-aromatic polyamide, or may contain two or more types of semi-aromatic polyamides. In the resin composition of this embodiment, the content of the semi-aromatic polyamide is, for example, 40 mass% or more, or may be 40 mass% or more and 80 mass% or less, or 45 mass% or more and 75 mass% or less, relative to the total mass of the resin composition.

[0030] <Maleic anhydride modified ultra-high molecular weight polyethylene> The maleic anhydride-modified ultra-high molecular weight polyethylene in this embodiment is a polymer obtained by modifying ultra-high molecular weight polyethylene with maleic anhydride, and has an intrinsic viscosity of 10 dL / g or more. The intrinsic viscosity of the maleic anhydride-modified ultra-high molecular weight polyethylene is preferably 10 dL / g or more and 40 dL / g or less, more preferably 15 dL / g or more and 35 dL / g or less, and even more preferably 20 dL / g or more and 30 dL / g or less.

[0031] The intrinsic viscosity of the maleic anhydride-modified ultra-high molecular weight polyethylene can be measured as follows. A maleic anhydride-modified ultra-high molecular weight polyethylene sample is diluted with decalin to obtain multiple diluted solutions with different sample concentrations. The flow time of each diluted solution is measured with a capillary viscometer at a measurement temperature of 135°C to determine the reduced viscosity. The relationship between sample concentration and reduced viscosity is plotted and extrapolated, and the intercept of the linear approximation is taken as the limiting viscosity (dL / g).

[0032] The molecular weight of the maleic anhydride-modified ultra-high molecular weight polyethylene in this embodiment is preferably 1,000,000 or more and 3,500,000 or less, and more preferably 1,250,000 or more and 3,000,000 or less. The molecular weight of the maleic anhydride-modified ultra-high molecular weight polyethylene can be determined by calculating the viscosity average molecular weight from the above-mentioned intrinsic viscosity based on the following formula (Mv-1). Viscosity average molecular weight Mv=5.37×10 4 ×[η] 1.37 ···(Mv-1) [η]: Intrinsic viscosity (dL / g), solvent: Decalin, measurement temperature: 135°C

[0033] The maleic anhydride-modified ultra-high molecular weight polyethylene may be a synthetic product or a commercially available product, such as Modified LUBMER (registered trademark) manufactured by Mitsui Chemicals, Inc.

[0034] The resin composition of the present embodiment may contain one type of maleic anhydride-modified ultra-high molecular weight polyethylene, or may contain two or more types of maleic anhydride-modified ultra-high molecular weight polyethylene. In the resin composition of the present embodiment, the content of the maleic anhydride-modified ultra-high molecular weight polyethylene may be 5% by mass or more, 5% by mass or more and 25% by mass or less, or 5% by mass or more and 20% by mass or less, relative to the total mass of the resin composition.

[0035] <Carbon fiber> The carbon fiber in this embodiment may be a typical carbon fiber obtained by firing a precursor (a fiber used as a raw material for carbon fiber) called a precursor. For example, the precursor is first flame-retarded in an oxidizing atmosphere, and the resulting flame-retarded fiber is then fired at approximately 800 to 2000°C in an inert gas atmosphere. If necessary, the fiber is further fired in an inert gas atmosphere at a higher temperature. The carbon fiber may have a sizing agent applied to its surface.

[0036] Examples of types of carbon fibers include polyacrylonitrile-based (hereinafter sometimes referred to as "PAN-based"), petroleum / coal pitch-based (hereinafter sometimes referred to as "pitch-based"), rayon-based, and lignin-based carbon fibers.

[0037] Examples of PAN-based carbon fibers include "TORAYCA (registered trademark)" manufactured by Toray Industries, Inc., "PYROFIL (registered trademark)" manufactured by Mitsubishi Chemical Corporation, and "TENAX (registered trademark)" manufactured by Toho Tenax Co., Ltd. Examples of pitch-based carbon fibers include "DIALEAD (registered trademark)" manufactured by Mitsubishi Chemical Corporation, "DONACARBO (registered trademark)" manufactured by Osaka Gas Chemicals Co., Ltd., and "KUREKA (registered trademark)" manufactured by Kureha Chemical Industry Co., Ltd.

[0038] The carbon fiber is preferably a carbon fiber bundle in which a plurality of single fibers are bundled together, or chopped carbon fiber.

[0039] The number average fiber diameter of the carbon fibers is, for example, 1 μm or more and 10 μm or less, and preferably 5 μm or more and 8 μm or less. When the number-average fiber diameter of the carbon fibers is 1 μm or more, the carbon fibers are easily dispersed in the semi-aromatic polyamide. Furthermore, the carbon fibers are easy to handle during the production of the resin composition. On the other hand, when the number-average fiber diameter of the carbon fibers is 10 μm or less, the carbon fibers efficiently reinforce the semi-aromatic polyamide. Therefore, excellent mechanical strength can be imparted to a molded article obtained by molding the resin composition. The number average fiber diameter of the carbon fibers is determined by observing the carbon fibers under a scanning electron microscope (1000x magnification) and measuring the fiber diameters of 50 carbon fibers, and the number average value is used.

[0040] The fiber diameter of the carbon fibers in the resin composition or molded article is hardly changed by melt-kneading, and is usually about the same as the fiber diameter of the carbon fibers before melt-kneading.

[0041] The number average fiber length of the carbon fibers in the resin composition is, for example, 10 μm or more and 400 μm or less, and preferably 100 μm or more and 350 μm or less. When the number average fiber length of the carbon fibers is equal to or greater than the above-mentioned lower limit, the durability of the molded article obtained by molding the resin composition is likely to be improved. On the other hand, when the number average fiber length of the carbon fibers is equal to or less than the above-mentioned upper limit, the reinforcement of the semi-aromatic polyamide by the carbon fibers is efficiently carried out.

[0042] [Method for measuring number average fiber length of carbon fibers in resin composition] The resin composition is heated under an air atmosphere to remove the resin, obtaining an ashing residue containing carbon fibers. The ashing residue is mixed with ethylene glycol to obtain a sample solution. Next, using a particle shape image analyzer, images of individual carbon fibers in a solution obtained by diluting the sample solution five times with ethylene glycol are taken. The captured carbon fibers are observed, and their longitudinal lengths are recorded as the fiber lengths. The measurement is terminated when the number of measured carbon fibers reaches 10,000, and the arithmetic mean value of the fiber lengths of the 10,000 carbon fibers obtained is calculated. This value is the number-average fiber length of the carbon fibers.

[0043] The resin composition of the present embodiment may contain one type of carbon fiber, or may contain two or more types of carbon fibers. In the resin composition of this embodiment, the content of the carbon fiber is, for example, 10 mass% or more relative to the total mass of the resin composition, and may be 10 mass% or more and 60 mass% or less, or 20 mass% or more and 40 mass% or less.

[0044] In the resin composition of the present embodiment, the mass ratio of the carbon fiber content to the semi-aromatic polyamide having a structural unit represented by formula (1) (carbon fiber / semi-aromatic polyamide) is 0.25 or more and 0.95 or less, and preferably 0.25 or more and 0.90 or less. If this mass ratio (carbon fiber / semi-aromatic polyamide) is equal to or less than the upper limit of the above-mentioned numerical range, wear between the carbon fibers (abrasive wear) is unlikely to occur when a molded article is formed. On the other hand, if the mass ratio is equal to or greater than the lower limit of the above-mentioned numerical range, adhesive wear is unlikely to occur at the interface with the mating material.

[0045] In the resin composition of this embodiment, the mass ratio of the carbon fiber content to the maleic anhydride-modified ultra-high molecular weight polyethylene (carbon fiber / maleic anhydride-modified ultra-high molecular weight polyethylene) is 0.8 or more and 6.5 or less, and preferably 1.0 or more and 6.0 or less. If this mass ratio (carbon fiber / maleic anhydride-modified ultra-high molecular weight polyethylene) is equal to or less than the upper limit of the above-mentioned numerical range, wear between the carbon fibers (abrasive wear) is unlikely to occur when the molded article is formed. On the other hand, if the mass ratio is equal to or greater than the lower limit of the above-mentioned numerical range, adhesive wear is unlikely to occur at the interface with the mating material with which the molded article comes into contact.

[0046] <Other ingredients> The resin composition of the present embodiment may contain other components that do not fall under any of the above-mentioned semi-aromatic polyamide, maleic anhydride-modified ultra-high molecular weight polyethylene, and carbon fiber. Examples of other components include fillers other than carbon fiber, additives, and resins other than the semi-aromatic polyamides and maleic anhydride-modified ultra-high molecular weight polyethylenes (hereinafter sometimes referred to as "other resins"). The other components may be used alone or in combination of two or more.

[0047] The filler other than carbon fiber may be a fibrous filler or a granular filler, and may be an inorganic filler or an organic filler. Examples of the additives include stabilizers, release agents, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, flame retardants, and colorants. Examples of other resins include thermoplastic resins such as polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether, polyetherimide, and fluororesin; and thermosetting resins such as phenolic resin, epoxy resin, polyimide resin, and cyanate resin.

[0048] In the resin composition of the present embodiment, the semi-aromatic polyamide having the structural unit represented by the above formula (1), the maleic anhydride-modified ultra-high molecular weight polyethylene, the carbon fiber, and other components are contained in such an amount that the total content (mass %) of these components does not exceed 100 mass %.

[0049] As described above, in the resin composition of the present embodiment, a semi-aromatic polyamide having a structural unit represented by the above formula (1), maleic anhydride-modified ultra-high molecular weight polyethylene, and carbon fiber are used in combination. (i) The maleic anhydride-modified ultra-high molecular weight polyethylene has a functional group that can react with the imino group (—NH—) of the semi-aromatic polyamide. Therefore, the maleic anhydride-modified ultra-high molecular weight polyethylene disperses well in the semi-aromatic polyamide. Furthermore, a transfer film with low intermolecular forces is formed on the surface of the mating material, which is thought to weaken the friction between the molded article containing the maleic anhydride-modified ultra-high molecular weight polyethylene and the mating material, resulting in excellent wear resistance. (ii) Furthermore, the resin composition of this embodiment contains carbon fiber in addition to the semi-aromatic polyamide and maleic anhydride-modified ultra-high molecular weight polyethylene. This is thought to increase the surface hardness of the molded article, making adhesive wear less likely to occur at the interface between the molded article and the mating material, and reducing the amount of wear, particularly under high surface pressure. (iii) Furthermore, in the resin composition of the present embodiment, the mixing ratio of the two components, semi-aromatic polyamide and maleic anhydride-modified ultra-high molecular weight polyethylene, to the carbon fiber is a specific value, which is thought to make it more difficult for adhesive wear to occur at the interface with the mating material and to prevent wear between the carbon fibers (abrasive wear). Therefore, the resin composition of this embodiment makes it possible to produce a molded article that is durable and can reduce the amount of wear under high surface pressure.

[0050] The resin composition of this embodiment is suitable as a molding material for machine parts such as gears, and is particularly suitable as a gear molding resin composition used as a molding material for gears.

[0051] The abrasion resistance of the molded body can be evaluated, for example, using the amount of abrasion of a hollow cylindrical test piece in the abrasion test described below as an index. [Wear test] Using the resin composition as the molding material, an injection molding machine was used to prepare hollow cylindrical test pieces (outer diameter 25.6 mm, inner diameter 20 mm, thickness 20 mm) under the following injection conditions: cylinder temperature 320 to 340°C, mold temperature 140°C, back pressure 8 MPa, screw rotation speed 80 rpm, injection speed 30 mm / s, injection pressure 150 MPa, injection time 0.7 seconds, dwell pressure 80 MPa, and cooling time 25 seconds. Using a Suzuki friction and wear tester (ring-on-ring), the amount of wear (mg) is measured in a room adjusted to 23°C under the wear test conditions shown below.

[0052] Wear test conditions Counterpart material: Carbon steel S45C hollow cylinder with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a thickness of 30 mm (Ra: 0.02 mm or less) Test temperature: 23℃ Test speed (circumferential speed): 60 m / min, rotation speed: 838 rpm Test time: 360 min

[0053] The durability of the molded article can be evaluated, for example, using the total number of revolutions until the resin gear breaks in the following [Durability Test] as an index. [Durability test] A metal master gear as a driving gear and a resin gear to be tested are meshed and set in a power absorption gear operation test machine specified in JIS B 1759. The test machine is operated under the following conditions: load torque of 5 N·m on the plastic gear, rotation speed of 1000 rpm, no lubrication, temperature of 23°C, and relative humidity of 50% RH, and the total number of rotations until the plastic gear breaks is measured. In this durability test, "breakage" of the plastic gear refers to a state in which power cannot be transmitted from the metal master gear of the driving gear to the plastic gear due to breakage of the teeth of the plastic gear or the like.

[0054] [Method of producing resin composition] The resin composition of the above-described embodiment can be produced by mixing a semi-aromatic polyamide having a structural unit represented by formula (1), maleic anhydride-modified ultra-high molecular weight polyethylene, carbon fiber, and other components as needed. The semi-aromatic polyamide, maleic anhydride-modified ultra-high molecular weight polyethylene, carbon fiber, and other components as needed are blended together so that the total content (mass %) of the semi-aromatic polyamide, maleic anhydride-modified ultra-high molecular weight polyethylene, carbon fiber, and other components as needed in the target resin composition does not exceed 100 mass %. The mass ratio of the carbon fiber to the semi-aromatic polyamide is 0.25 to 0.95, and the mass ratio of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 to 6.5. One embodiment of the method for producing such a resin composition is a production method including a step of mixing a semi-aromatic polyamide having a structural unit represented by the formula (1), maleic anhydride-modified ultra-high molecular weight polyethylene, and carbon fiber.

[0055] In another aspect, the present disclosure further includes the following embodiments.

[0056] [7] A resin composition containing a semi-aromatic polyamide having a structural unit represented by the following formula (1), maleic anhydride-modified ultra-high molecular weight polyethylene, and carbon fiber, a mass ratio of the content of the carbon fiber to the semi-aromatic polyamide is 0.25 or more and 0.95 or less; a mass ratio of the content of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 or more and 6.5 or less; A resin composition, wherein the content of the carbon fiber is 20 mass % or more based on the total mass of the resin composition.

[0057] [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12.

[0058] [8] The resin composition according to any one of [1] to [5] and [7], wherein the maleic anhydride-modified ultra-high molecular weight polyethylene has an intrinsic viscosity of 10 dL / g or more and 40 dL / g or less.

[0059] (Molded body) One embodiment of the molded article contains the resin composition of the above-described embodiment. An example of the molded article of this embodiment is a molded article made from the resin composition of the above-described embodiment as a molding material.

[0060] The method for molding the resin composition into a molded article is not particularly limited, but melt molding is preferred, and examples include extrusion molding, T-die molding, blow molding, and injection molding, and the molding method can be selected depending on the shape of the molded article, etc.

[0061] The molded article of this embodiment can be used in any application to which a resin composition can generally be applied. Examples of the molded article of this embodiment include electrical and electronic components such as connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, printed wiring boards, circuit boards, semiconductor packages, and computer-related parts; semiconductor manufacturing process-related parts such as IC trays and wafer carriers; home electrical appliance parts such as VTRs, televisions, irons, air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, and lighting fixtures; lighting fixture parts such as lamp reflectors and lamp holders; audio product parts such as compact discs, laser discs (registered trademark), and speakers; communication equipment parts such as ferrules for optical cables, telephone parts, facsimile parts, and modems; separation claws and heater holders. copier and printer related parts; mechanical parts such as impellers, fan gears, gears, bearings, motor parts and cases; automotive parts such as automotive mechanism parts, engine parts, engine room parts, electrical parts, and interior parts, cooking utensils such as microwave cooking pots and heat-resistant tableware; heat insulation and soundproofing materials such as flooring and wall materials, supporting materials such as beams and pillars, building materials such as roofing materials, civil engineering and construction materials; aircraft, spacecraft, and space equipment parts; radiation facility components such as nuclear reactors, marine facility components, cleaning jigs, optical equipment parts, valves, pipes, nozzles, filters, membranes, medical equipment parts and medical materials, sensor parts, sanitary equipment, sporting goods, leisure goods, and cable ties.

[0062] The molded article of this embodiment has improved durability because it uses the resin composition of the above-described embodiment as a molding material, and is therefore particularly suitable for sliding applications, particularly as mechanical parts such as seal members and gears in compressors, and is particularly suitable for use as gears. Types of gears include spur gears, helical gears, racks, internal gears, worm gears, worm wheel gears, bevel gears, hypoid gears, and the like. [Example]

[0063] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples.

[0064] <Production of Resin Composition> Each resin composition having the composition and mass ratio shown in Table 1 was produced. The semi-aromatic polyamide, maleic anhydride modified polyolefin, and carbon fiber used were as follows:

[0065] Semi-aromatic polyamide Semi-aromatic polyamide (P1): Ar in formula (1) 1 A semi-aromatic polyamide having a structural unit represented by formula (1), in which is a 1,4-phenylene group and p is 10. The melt mass-flow rate (MFR) at 330°C is 24 g / 10 min.

[0066] Semi-aromatic polyamide (P2): "Genestar (registered trademark) N1000A" manufactured by Kuraray Co., Ltd., Ar in formula (1) 1 A semi-aromatic polyamide having a structural unit represented by formula (1), in which is a 1,4-phenylene group and p is 9. The MFR at 330°C is 20 g / 10 min.

[0067] The MFR of the semi-aromatic polyamide was measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g.

[0068] Maleic anhydride modified polyolefin Maleic anhydride-modified polyolefin (1): Maleic anhydride-modified ultra-high molecular weight polyethylene, "Lubmer (registered trademark) LY1040" manufactured by Mitsui Chemicals, Inc., with an intrinsic viscosity [η] of 25 dL / g measured in decalin solvent at 135°C.

[0069] Maleic anhydride-modified polyolefin (2): Maleic anhydride-modified polyethylene, "Admer (registered trademark) HE810" manufactured by Mitsui Chemicals, Inc., with an intrinsic viscosity [η] of 1.2 dL / g measured in decalin solvent at 135°C.

[0070] Carbon fiber Mitsubishi Chemical Corporation's "Pyrofil (registered trademark) Chopped Fiber TR03M," a PAN-based carbon fiber with a fiber length of 3 mm and a number average fiber diameter of 7 μm.

[0071] (Examples 1 to 6, Comparative Examples 1 to 7) Semi-aromatic polyamide, maleic anhydride-modified polyolefin, and carbon fiber with the compositions shown in Table 1 were fed into a twin-screw extruder (PCM-30, manufactured by Ikegai Corporation), melt-kneaded while degassing under conditions of a barrel temperature of 310 to 350°C, a screw rotation speed of 150 rpm, and a discharge rate of 5 kg / min, and discharged in the form of strands through a circular nozzle (discharge port), passed through a water-cooled belt conveyor (manufactured by Isuzu Chemical Engineering Co., Ltd.), and pelletized with a strand cutter to obtain pellet-shaped resin compositions for each of the Examples and Comparative Examples.

[0072] <Manufacturing of plastic gears> The pellet-shaped resin composition was placed in an injection molding machine and injection molded under the following injection conditions: cylinder temperature 330-350°C, mold temperature 140°C, back pressure 10 MPa, screw rotation speed 100 rpm, injection pressure 100 MPa, injection speed 50 mm / s, injection time 8 seconds, dwell pressure 70 MPa, and cooling time 25 seconds, to produce a resin gear. The resin gear was manufactured with a gear shape of spur gear, module 1, number of teeth 48, pressure angle 20°, reference circle diameter 48 mm, tip circle diameter 50 mm, root circle diameter 45.5 mm, face width 8 mm, transition coefficient 0, and spanning tooth thickness 16.909 (number of spanning teeth 6). The configuration of the manufactured resin gear is shown in Figure 1.

[0073] <Evaluation> The manufactured resin gears were subjected to the following wear test and durability test.

[0074] [Wear test] Using pellets of each resin composition of the Examples and Comparative Examples as molding materials, hollow cylindrical test pieces (outer diameter 25.6 mm, inner diameter 20 mm, thickness 20 mm) were produced using an injection molding machine (injection molding machine SE100EV-A, manufactured by Sumitomo Heavy Industries, Ltd.) under injection conditions of cylinder temperature 320 to 340°C, mold temperature 140°C, back pressure 8 MPa, screw rotation speed 80 rpm, injection speed 30 mm / s, injection pressure 150 MPa, injection time 0.7 seconds, dwell pressure 80 MPa, and cooling time 25 seconds. Using a Suzuki friction and wear tester (manufactured by Takachiho Seiki Co., Ltd., ring-on-ring), the wear amount (mg) was measured under the following wear test conditions in a room adjusted to 23°C. This measurement was performed on five samples, and the average value was calculated. The results are shown in Table 1. In Table 1, "*1" indicates that the wear was so great that it could not be measured.

[0075] Wear test conditions Counterpart material: Carbon steel S45C hollow cylinder with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a thickness of 30 mm (Ra: 0.02 mm or less) Test temperature: 23℃ Test speed (circumferential speed): 60 m / min, rotation speed: 838 rpm Load (surface pressure): 176N, 58N Test time: 360 min

[0076] [Durability test] A metal master gear [material: SCM420, carburized, quenched, and tempered (surface hardening treatment), quench-hardened layer depth 0.8 to 1.2, hardness HRC 55 to 60, gear shape: spur gear, module 1, number of teeth 67, pressure angle 20°, reference circle diameter 67 mm, tip circle diameter 69 mm, root circle diameter 64.5 mm, face width 15 mm, transition coefficient 0, and spanning tooth thickness 23.079 (number of spanning teeth 8)] was installed as the drive gear in a power absorption gear operation test machine specified in JIS B 1759, and the manufactured resin gear was meshed with it. The test machine was operated under the following conditions: load torque of 5 N m, rotation speed of 1000 rpm, no lubrication, temperature of 23°C, relative humidity of 50%, and backlash in the normal direction of 0.1 mm, and the total number of rotations until the resin gear broke was measured. The results are shown in Table 1. In this durability test, "breakage" of the plastic gear refers to a state in which power cannot be transmitted from the metal master gear of the drive gear to the plastic gear due to breakage of the teeth of the plastic gear or the like.

[0077] [Table 1]

[0078] Wear test results: Comparing Example 2 with Comparative Example 3, it can be seen that the test piece made from pellets of a resin composition containing semi-aromatic polyamide (P1), carbon fiber, and maleic anhydride-modified polyolefin (1) as the molding material has a small amount of wear, especially under high surface pressure. Furthermore, it can be confirmed that the resin compositions of Examples 1 to 6, in which the mass ratio of the carbon fiber content to the semi-aromatic polyamide is 0.25 or more and 0.95 or less, and the mass ratio of the carbon fiber content to the maleic anhydride-modified polyolefin (1) is 0.8 or more and 6.5 or less, have superior wear resistance at high surface pressure compared to the resin compositions of Comparative Examples 1, 2, and 5, which do not satisfy the above mass ratio ranges. Furthermore, a comparison between Example 1 and Comparative Example 7 confirms that the test piece molded from pellets of a resin composition containing, in addition to semi-aromatic polyamide (P1) and carbon fiber, ultra-high molecular weight maleic anhydride-modified polyolefin (1) has superior wear resistance under high surface pressure.

[0079] Durability test results: It can be confirmed that the resin compositions of Examples 1 to 6 have a larger total number of revolutions until the resin gear breaks than the resin compositions of Comparative Examples 1 to 7, and that the durability of the molded article is further improved.

[0080] It was shown that the resin compositions of Examples 1 to 6 were useful molding materials that could be used to produce resin gears that were excellent in durability and wear resistance under high surface pressure.

[0081] The configurations and combinations thereof in each embodiment are examples, and modifications such as addition, omission, and substitution of configurations are possible within the scope of the present disclosure.

Claims

1. A semi-aromatic polyamide having a structural unit represented by the following formula (1): Maleic anhydride modified ultra-high molecular weight polyethylene, Carbon fiber and A resin composition comprising: a mass ratio of the content of the carbon fiber to the content of the semi-aromatic polyamide is 0.25 or more and 0.95 or less; A resin composition, wherein the mass ratio of the content of the carbon fiber to the maleic anhydride-modified ultra-high molecular weight polyethylene is 0.8 or more and 6.5 or less. 【Chemistry 1】 [In formula (1), Ar １ represents a phenylene group or a naphthylene group, and the plurality of Ar groups contained in the semi-aromatic polyamide １ may be the same or different, and p is an integer of 4 to 12.

2. The semi-aromatic polyamide is a polyamide represented by the formula (1) １ The resin composition according to claim 1, which is a semi-aromatic polyamide having a structural unit in which represents a 1,4-phenylene group and p is 9 or 10.

3. 2. The resin composition according to claim 1, wherein the semi-aromatic polyamide has a melt mass-flow rate (MFR) measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g of 1 g / 10 min or more and 300 g / 10 min or less.

4. The resin composition according to claim 1 , wherein the content of the carbon fiber is 20 mass % or more with respect to the total mass of the resin composition.

5. 2. The resin composition according to claim 1, wherein the maleic anhydride-modified ultra-high molecular weight polyethylene has an intrinsic viscosity of 10 dL / g or more and 40 dL / g or less.

6. A molded article comprising the resin composition according to any one of claims 1 to 5.

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