Resin gear

Abstract

The present invention relates to a resin gear which can maintain excellent mechanical strength, has excellent durability, and reduces corrosion to a target member. This resin gear is made of a molded body of a resin composition containing a polyamide resin (A) and carbon fibers (B), and has a fracture toughness (K1c) of 8.0 MPa.m1 / 2 to 14.0 MPa.m1 / 2.

Description

Technical Field

[0001] The present invention relates to a resin gear formed from a molded body of a resin composition containing a polyamide resin. Background Art

[0002] Since polyamide resins generally have excellent mechanical properties, heat resistance, chemical resistance, etc., they are used in electrical and electronic components, automotive parts, etc. In various applications, they are also widely used in bearing retainers, resin gears, etc. because of their excellent sound insulation performance and self-lubricating properties.

[0003] In the past, between gears made of metal materials, there were problems such as vibration and noise caused by backlash. Therefore, in order to reduce vibration, noise, etc. caused by backlash, in recent years, resin gears using resin materials have been proposed. Moreover, in order to transmit a large stress, it is necessary to improve the durability and wear resistance of resin gears.

[0004] As one of the means for improving the slidability, wear resistance, and durability of resin gears, methods for improving the heat resistance, wear resistance, etc. of resin gears by mixing carbon fiber as a reinforcing fiber in aliphatic polyamide 46 and semi-aromatic polyamide MXD6 as shown in Patent Document 1 have been studied.

[0005] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011 - 131372 Summary of the Invention

[0006] Problems to be Solved by the Invention However, even according to the method described in Patent Document 1, it is still difficult to sufficiently improve the durability of resin gears, and there is a problem of high erosiveness to the target member.

[0007] An object of the present invention is to provide a resin gear that can solve this problem, maintain excellent mechanical strength, has excellent durability, and reduces the erosiveness to the target member.

[0008] Technical Means for Solving the Problems The present invention provides a resin gear having the following composition.

[0009] Item 1: A resin gear, wherein the resin gear is formed from a molded body of a resin composition containing a polyamide resin (A) and carbon fiber (B), and the fracture toughness K1c is 8.0 MPa·m 1 / 2 ~14.0 MPa·m 1 / 2 .

[0010] Item 2: The resin gear according to Item 1, wherein the resin composition further contains a silicone resin (C).

[0011] Item 3: The resin gear according to Item 1 or 2, wherein the resin composition further contains a reinforcing material (D), and the Mohs hardness of the reinforcing material (D) is 5 or less.

[0012] Item 4: The resin gear according to Item 3, wherein the reinforcing material (D) is at least one of potassium titanate fiber and wollastonite fiber.

[0013] Item 5: The resin gear according to any one of Items 1 to 4, wherein the polyamide resin (A) is an aliphatic polyamide resin.

[0014] Item 6: The resin gear according to any one of Items 1 to 5, wherein the content of the carbon fiber (B) in 100% by mass of the total amount of the resin composition is 10% to 40% by mass.

[0015] Item 7: The resin gear according to any one of Items 2 to 6, wherein the content of fumed silica in the silicone resin (C) is 20% to 40% by mass.

[0016] Item 8: The resin gear according to any one of Items 2 to 7, wherein the content of the silicone resin (C) in 100% by mass of the total amount of the resin composition is 0.1% to 8% by mass.

[0017] Effects of the Invention According to the present invention, there can be provided a resin gear that can maintain excellent mechanical strength, has excellent durability, and reduces the erosiveness to the target member. Detailed Embodiments

[0018] The preferred embodiments of the present invention will be described below. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments.

[0019] The resin gear of the present invention is formed from a molded body of the above resin composition, and the resin composition contains a polyamide resin (A) and a carbon fiber (B), and, as required, further contains a silicone resin (C) and a reinforcing material (D) having a Mohs hardness of 5 or less, etc.

[0020] The resin gear of the present invention is a resin gear composed of a molded body of a resin composition, and the fracture toughness K1c is in the range of 8.0 MPa·m 1 / 2 to 14.0 MPa·m 1 / 2 Within this range, the mechanical strength brought by the carbon fiber (B) of the resin gear can be maintained, and the durability is excellent, and the erosiveness to the target member can be reduced.

[0021] In the present invention, the fracture toughness K1c of the resin gear is 8.0 MPa·m 1 / 2 ~14.0 MPa·m 1 / 2 . The fracture toughness K1c of the resin gear is preferably 8.5 MPa·m 1 / 2 or more, more preferably 9.0 MPa·m 1 / 2 or more, preferably 13.5 MPa·m 1 / 2 or less, more preferably 13.0 MPa·m 1 / 2 or less, further preferably 12.0 MPa·m 1 / 2 or less, still further preferably 11.5 Pa·m 1 / 2 or less, particularly preferably 11.0 Pa·m 1 / 2 or less. The above fracture toughness K1c can be measured according to the standard of, for example, ASTM D5045-93.

[0022] In the present invention, it is preferred that the above resin composition further contains silicone resin (C). In this case, the static friction coefficient of the resin gear formed from the above resin composition can be further reduced, and it is expected to reduce vibrations and noises (quiet performance) caused by stick-slip, etc.

[0023] In the present invention, it is preferred to further contain a reinforcing material (D) with a Mohs hardness of 5 or less. The above reinforcing material (D) is preferably at least one of potassium titanate fibers and wollastonite fibers. In this case, the durability of the resin gear formed from the above resin composition will become better. In addition, by combining the silicone resin (C) and the reinforcing material (D), the static friction coefficient can be further reduced.

[0024] In the present invention, the above polyamide resin (A) is preferably an aliphatic polyamide resin. In this case, the toughness, self-lubricity, and quietness of the resin gear formed from the above resin composition can be improved at a higher level.

[0025] In the present invention, the content of the polyamide resin (A) in 100% by mass of the total amount of the resin composition is preferably 20% by mass to 88% by mass, more preferably 33% by mass to 80% by mass, further preferably 40% by mass to 80% by mass, still further preferably 45% by mass to 80% by mass, even further preferably 50% by mass to 75% by mass, yet further preferably 53% by mass to 75% by mass, still yet further preferably 53% by mass to 75% by mass, particularly preferably 60% by mass to 75% by mass.

[0026] In the present invention, the content of the carbon fiber (B) in 100% by mass of the total amount of the resin composition is preferably 10% by mass to 40% by mass, more preferably 20% by mass to 35% by mass, still more preferably 20% by mass to 30% by mass, and particularly preferably 22% by mass to 30% by mass. By setting the content of the carbon fiber (B) within the above range, the mechanical strength of the resin gear formed from the molded body of the above resin composition can be more effectively improved.

[0027] When the above resin composition contains the silicone resin (C), the content of the silicone resin (C) in 100% by mass of the total amount of the resin composition is preferably 0.1% by mass to 8% by mass, more preferably 0.5% by mass to 6% by mass, still more preferably 1% by mass to 5% by mass, still further preferably 1.5% by mass to 4.5% by mass, and particularly preferably 2% by mass to 4% by mass. By setting the content of the silicone resin (C) within the above range, the static friction coefficient of the resin gear formed from the molded body of the above resin composition can be further reduced.

[0028] When the above resin composition contains the silicone resin (C), the content of the fumed silica in the silicone resin (C) when the total amount of the silicone resin and the fumed silica is 100% by mass is preferably 20% by mass to 40% by mass, more preferably 25% by mass to 35% by mass, and still more preferably 28% by mass to 32% by mass. When the content of the fumed silica is within the above range, the durability of the resin gear formed from the molded body of the above resin composition can be made better, and the erosiveness to the target member can be further reduced.

[0029] When the above resin composition contains the reinforcing material (D), the content of the reinforcing material (D) in 100% by mass of the total amount of the resin composition is preferably 0.1% by mass to 35% by mass, more preferably 0.5% by mass to 10% by mass, still more preferably 1% by mass to 9% by mass, still further preferably 2% by mass to 8% by mass, and particularly preferably 3% by mass to 7% by mass. By setting the content of the reinforcing material (D) within the above range, the durability of the resin gear formed from the molded body of the above resin composition becomes better.

[0030] When the above resin composition contains the reinforcing material (D), the mass ratio of the polyamide resin (A) contained in the resin composition to the reinforcing material (D) (polyamide resin (A) / reinforcing material (D)) is preferably 1.5 to 500, more preferably 2.0 to 100, and still more preferably 10.0 to 30.0. By setting the mass ratio of the polyamide resin (A) to the reinforcing material (D) within the above range, the decrease in the fracture toughness K1c caused by the excessive increase in the reinforcing effect of the reinforcing material (D) can be further suppressed, and the moldability of the resin composition can be further improved.

[0031] When the above resin composition contains the reinforcing material (D), the mass ratio of the reinforcing material (D) contained in the resin composition to the carbon fiber (B) (reinforcing material (D) / carbon fiber (B)) is preferably 0.05 to 0.9, more preferably 0.1 to 0.5, and further preferably 0.1 to 0.3. By setting the mass ratio of the reinforcing material (D) to the carbon fiber (B) within the above range, the durability and mechanical strength of the resin gear formed from the above resin composition can be further improved.

[0032] When the above resin composition contains the silicone resin (C) and the reinforcing material (D), the mass ratio of the silicone resin (C) contained in the resin composition to the reinforcing material (D) (silicone resin (C) / reinforcing material (D)) is preferably 0.1 to 0.9, more preferably 0.2 to 0.8, further preferably 0.3 to 0.8, still more preferably 0.4 to 0.8, and particularly preferably 0.5 to 0.7. By setting the mass ratio of the silicone resin (C) to the reinforcing material (D) within the above range, the static friction coefficient of the resin gear formed from the above resin composition can be further reduced.

[0033] Since the resin gear of the present invention has excellent mechanical strength and excellent durability, and can reduce the erosion to the target member, it can be applied to small module gears, and particularly can be applied to small gears. Examples of such small gears include gears used in the folding mechanism or unfolding mechanism of flexible displays, and gears of reduction motors for small drive mechanisms such as smartphones, tablet computers, and PCs (personal computers).

[0034] In the application of automotive parts, it can be applied to resin gears for electric power steering devices, resin gears for speed reducers of electric vehicles, etc., and resin gears for electric parking brakes, etc., in which the resin gear of the present invention is used in the gear reduction mechanism. In the application of electrical and electronic components, it can be applied to resin gears for the casings of washing machines, vacuum cleaners, robots, etc.

[0035] Examples of the types of gears to which the resin gear of the present invention can be applied include spur gears, helical gears, internal gears, internal helical gears, wave gears, spiral gears, bevel gears, offset bevel gears, worm gears, racks, etc.

[0036] The following describes each component element of the resin composition constituting the resin gear of the present invention, etc.

[0037] <Resin composition> The resin composition used in the present invention contains a polyamide resin (A) and carbon fibers (B), and may also contain a silicone resin (C), a reinforcing material (D) with a Mohs hardness of 5 or less, and other additives as needed.

[0038] (Polyamide resin (A)) The polyamide resin (A) used in the present invention is a polymer having an amide bond (-NH-C(=O)-) in the main chain, and is a polymer containing structural units derived from monomer components such as aminocarboxylic acids, diamines, and dicarboxylic acids described later. The polyamide resin (A) may be a resin containing one structural unit or a resin containing multiple structural units. Examples of the resin containing one structural unit include polymers of aminocarboxylic acids. Examples of the resin containing multiple structural units include copolymers of diamines and dicarboxylic acids, copolymers of diamines, dicarboxylic acids, and aminocarboxylic acids, etc.

[0039] When the polyamide resin (A) is a copolymer containing multiple structural units, the copolymerization ratio, copolymerization form, etc. can be arbitrarily selected. Examples of the copolymerization form include random copolymers, block copolymers, alternating copolymers, etc.

[0040] Examples of the aminocarboxylic acid include aliphatic ω-aminocarboxylic acids having 5 to 20 carbon atoms such as 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid; aromatic diamines such as p-aminobenzoic acid, p-aminomethylbenzoic acid, etc. In addition, as the aminocarboxylic acid, cyclic lactams corresponding to the aliphatic ω-aminocarboxylic acid can also be used. These compounds can be used alone or in combination of two or more.

[0041] Examples of the diamine include aliphatic diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 2-methyl-1,5-diaminopentane, 3-methyl-1,5-diaminopentane, 2-ethyltetramethylenediamine; alicyclic diamines such as 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, 4,4'-diamino-3,3'-dimethylbicyclohexylmethane, isophoronediamine, piperazine; aromatic diamines such as p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, p-toluenediamine, o-toluenediamine, m-toluenediamine, etc. These diamines can be used alone or in combination of two or more.

[0042] As the dicarboxylic acid, examples include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2-methylterephthalic acid, naphthalenedicarboxylic acid, etc. These dicarboxylic acids can be used alone or in combination of two or more.

[0043] As specific examples of the polyamide resin (A), for example, there can be cited aliphatic polyamide resins such as polyamide 6 (polymer of 6-aminohexanoic acid), polyamide 66 (copolymer of hexamethylenediamine and adipic acid), polyamide 11 (polymer of 11-aminoundecanoic acid), polyamide 12 (polymer of 12-aminododecanoic acid), polyamide 46 (copolymer of tetramethylenediamine and adipic acid), polyamide 6 / 66 copolymer (copolymer of 6-aminohexanoic acid, hexamethylenediamine, and adipic acid), polyamide 6 / 12 copolymer (copolymer of 6-aminohexanoic acid and 12-aminododecanoic acid); semi-aromatic polyamide resins such as polyamide MXD 6 (copolymer of m-xylenediamine and adipic acid), polyamide 6T (copolymer of hexamethylenediamine and terephthalic acid), polyamide 9T (copolymer of 1,9-diaminononane and terephthalic acid), polyamide 10T (copolymer of 1,10-diaminodecane and terephthalic acid), polyamide 6T / 66 copolymer (copolymer of hexamethylenediamine, terephthalic acid, and adipic acid), etc. These polyamides can be used alone or in combination of two or more.

[0044] In the present invention, the aliphatic polyamide resin refers to a polyamide resin in which the structural unit of the polyamide resin (A) substantially does not contain a structural unit derived from an aromatic monomer. The semi-aromatic polyamide resin refers to a polyamide resin in which the structural unit of the polyamide resin (A) contains a structural unit derived from an aliphatic monomer and a structural unit derived from an aromatic monomer. As the aliphatic monomer, there can be cited the aliphatic dicarboxylic acid, aliphatic diamine, alicyclic diamine, aliphatic ω-aminocarboxylic acid, alicyclic dicarboxylic acid, etc. in the above monomer components. As the aromatic monomer, there can be cited the aromatic diamine, aromatic dicarboxylic acid, aromatic aminocarboxylic acid, etc. in the above monomer components.

[0045] In the present invention, from the perspective of more easily adjusting the fracture toughness K1c of the resin gear to the required range, the polyamide resin (A) is preferably an aliphatic polyamide resin, more preferably polyamide 66 (copolymer of hexamethylenediamine and adipic acid) or polyamide 46 (copolymer of tetramethylenediamine and adipic acid), and further preferably polyamide 66 (copolymer of hexamethylenediamine and adipic acid).

[0046] From the perspective of self-lubricity, the polyamide resin (A) used in the present invention is preferably a crystalline resin having a melting point. From the perspectives of suppressing deformation, discoloration, etc., the melting point is preferably 150°C or higher, more preferably 200°C or higher. In addition, from the perspective of suppressing thermal cracking of the polyamide resin (A) during melt compounding, extrusion molding, injection molding, etc., the melting point of the polyamide resin (A) is preferably 350°C or lower, more preferably 330°C or lower. In this specification, the melting point can be measured according to the standard of JIS-K7121.

[0047] The shape of the polyamide resin (A) is not particularly limited as long as it can be melt compounded. For example, any shape such as powder, fine powder, pellet, etc. can be used.

[0048] (Carbon fiber (B)) The carbon fiber (B) used in the present invention can be, for example, a polyacrylonitrile (PAN) - based carbon fiber, a pitch - based carbon fiber, a cellulose - based carbon fiber, a hydrocarbon - based chemical vapor deposition carbon fiber, a graphite fiber, etc. These carbon fibers can be used alone or in combination of two or more. Moreover, as the carbon fiber (B), a PAN - based carbon fiber is preferred.

[0049] The average fiber length of the carbon fiber (B) used in the present invention is preferably greater than 0.05 mm, more preferably greater than 0.08 mm, further preferably greater than 0.1 mm, and preferably 10 mm or less, more preferably 8 mm or less. Although the carbon fiber (B) can also be a product in which fibers are aggregated into a fibrous reinforcing material bundle through a sizing agent, etc., the average fiber diameter of the carbon fiber (B) is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 30 μm or less, more preferably 15 μm or less.

[0050] In addition, the average aspect ratio (average fiber length / average fiber diameter) of the carbon fiber (B) is preferably 5 or more, more preferably 10 or more, further preferably 20 or more, and preferably 1200 or less, more preferably 1000 or less, further preferably 950 or less.

[0051] As the carbon fiber (B), there is no particular limitation as long as it is for resin reinforcement use, and any of short - cut fibers and ground fibers can be used. However, from the perspective of increasing the mechanical strength of the tooth tip of the resin gear, ground fibers are preferred.

[0052] (Silicone resin (C)) The resin composition used in the present invention may also contain a silicone resin (C) as needed. The silicone resin (C) used in the present invention is an oligomer or polymer having a siloxane bond as a main skeleton and containing organic groups. As the silicone resin (C), silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, methanol-modified silicone oil, phenol-modified silicone oil, carboxyl-modified silicone oil, methylhydrogen silicone oil, mercapto-modified silicone oil, methacryloyl-modified silicone oil, polyether-modified silicone oil, aralkyl-modified silicone oil, fluoroalkyl-modified silicone oil, long-chain alkyl-modified silicone oil, higher fatty acid ester-modified silicone oil, phenyl-modified silicone oil, etc. can be cited; silicone rubbers having a linear dimethyl polysiloxane crosslinked structure; polymethylsilsesquioxane having a three-dimensional network structure represented by (CH3SiO 3 / 2 ); n ), and organosilicon resins having a three-dimensional network structure mainly composed of trifunctional siloxane units, etc. can be cited.

[0053] As a specific example of the silicone resin (C), an organosilicon resin represented by the following general formula (1) can be cited.

[0054]

[0055] In the general formula (1), R 1 represents an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group or an aryl group, and these groups may also have substituents. R 1 may be the same as or different from each other. l and m represent any integer of 1 or more. The bonding order of the repeating unit structures in the parentheses is not particularly limited.

[0056] As the alkyl group represented by R 1 , a linear or branched alkyl group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, can generally be cited. Specifically, the alkyl group represented by R 1 can be cited, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.

[0057] As the cycloalkyl group represented by R 1 , a cycloalkyl group having 3 to 10 carbon atoms can generally be cited. Specifically, it can be cited, for example, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.

[0058] As the alkenyl group represented by R 1 , a linear or branched alkenyl group having 2 to 20 carbon atoms, preferably an alkenyl group having 2 to 10 carbon atoms, can generally be cited. Specifically, it can be cited, for example, vinyl, 1-propenyl, 2-propenyl, isopropenyl, 1-butenyl, 2-butenyl, pentenyl, hexenyl, heptenyl, etc.

[0059] As R1 The cycloalkenyl group represented can be, for example, a cycloalkenyl group having 3 to 10 carbon atoms. Specifically, examples thereof include cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, etc.

[0060] As R 1 The aryl group represented can be, for example, an aryl group having 6 to 20 carbon atoms, preferably an aryl group having 6 to 12 carbon atoms. Specific examples thereof include phenyl, tolyl, xylyl, mesityl, naphthyl, etc.

[0061] R 1 The groups represented by R can each have a substituent. Examples of the substituent include, for example, amino, aryl (such as phenyl, etc.), or amino-substituted by a lower (for example, having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms) alkylamino, epoxy group, glycidyl group, mercapto group, carboxyl group, ether group, epoxycycloalkyl group (such as 3,4-epoxycyclohexyl, etc.), hydroxyl group, isocyanate group, ester group (such as alkoxycarbonyl having 1 to 20 carbon atoms, etc.), (meth)acryloyloxy group, ureido group (-NHCONH2), carbamoyl group (-CONH2), alkanolamide group (such as alkanolamide group having 1 to 20 carbon atoms, etc.), alkanolyloxy group (such as alkanolyloxy group having 1 to 20 carbon atoms, etc.), cycloalkyl group (such as cyclopentyl, cyclohexyl, etc.), cycloalkenyl group (such as cyclopentenyl, cyclohexenyl, etc.), aryl group (such as phenyl, etc.), halogen atom (such as fluorine atom, chlorine atom, bromine atom, etc.), etc.

[0062] As R 1 Suitable specific examples of the groups represented by R include, for example, the groups represented by the following general formulae (2a) to (2g).

[0063]

[0064] In general formulae (2a) to (2g), a to g can be the same or different and each represents an integer of 2 to 6. a to g preferably represent 2 or 3.

[0065] l is preferably an integer of 1 to 20,000, more preferably an integer of 1 to 10,000. m is preferably an integer of 1 to 20,000, more preferably an integer of 1 to 10,000.

[0066] In the present invention, the silicone resin represented by the above general formula (1) is preferably the silicone resin represented by the following general formula (3).

[0067]

[0068] In general formula (3), R 1AAn alkyl group substituted by 1 to 3 groups selected from an amino group, a phenyl group, or an amino group, an amino group substituted by an alkyl group having 2 to 4 carbon atoms, an epoxy group, a glycidyl group, a carboxyl group, a hydroxyl group, an isocyanate group, and an epoxycyclohexyl group. l and m are the same as those in the above general formula (1). The bonding order of the structures of each repeating unit in the parentheses is not particularly limited.

[0069] As R 1A , it is preferably the group exemplified as R 1 in the above general formula (1), and more preferably the group represented by the general formula (2a) to (2g).

[0070] As other preferred silicone resins represented by the above general formula (1), a silicone resin represented by the following general formula (4) can be cited.

[0071]

[0072] In the general formula (4), R 1B is an alkyl group substituted by 1 to 3 groups selected from a phenyl group, an amino group, an amino group substituted by an alkyl group having 2 to 4 carbon atoms, an epoxy group, a glycidyl group, a carboxyl group, a hydroxyl group, an isocyanate group, and an epoxycyclohexyl group. l and m are the same as those in the above general formula (1). The bonding order of the structures of each repeating unit in the parentheses is not particularly limited.

[0073] As R 1B , it is also preferably the group exemplified as R 1 in the above general formula (1), and more preferably the group represented by the general formula (2a) to (2g).

[0074] When the silicone resin represented by the general formula (1) is a liquid substance (such as silicone oil, etc.), the viscosity (25 °C) is usually 10 mm 2 / s to 2,000 mm 2 / s, preferably 10 mm 2 / s to 1,000 mm 2 / s. When the viscosity of the liquid substance is within this range, it will be easier to disperse more uniformly. It should be noted that the viscosity can be measured by a kinematic viscosity measuring device.

[0075] In addition, as the silicone resin, from the perspective of further improving the operability and further suppressing the bleeding of the resin composition, it is preferably a silicone resin in which the above silicone resin is carried on a porous fine particle carrier such as silica (silicon dioxide).

[0076] In addition, as the carrier, carbonates such as calcium carbonate and barium carbonate; silicates such as calcium silicate, barium silicate, and magnesium silicate; phosphates such as calcium phosphate, barium phosphate, magnesium phosphate, zirconium phosphate, and apatite; metal oxides such as alumina; graphite, zeolite, layered clay minerals, polyethylene, polyurethane, cellulose, polyamide, polyvinyl formal, phenolic resin, epoxy resin, urea resin, etc. can be used.

[0077] Among them, as the silica, fumed silica, precipitated silica, micro-ground silica, and / or calcined silica are preferably used as the carrier, and fumed silica is more preferably used as the carrier.

[0078] When the organosilicon resin (C) represented by the general formula (1) is solid (such as polymethylsilsesquioxane, organosilicon resin, etc.), its shape is not particularly limited as long as it can be melt-kneaded, and any shape of powder, fine powder, or pellet can be used.

[0079] These organosilicon resins (C) also include any one of commercially available known compounds and compounds that can be manufactured by those skilled in the art using known methods. As described later, for example, a resin composition can be obtained by mixing and heating (especially melt-kneading) the organosilicon resin (C) together with the polyamide resin (A) and the carbon fiber (B).

[0080] It should be noted that in the resin composition used in the present invention, as the organosilicon resin (C), one of the above compounds can be used alone, or two or more can be used in combination.

[0081] The resin composition used in the present invention can further improve the wear resistance of the resin gear by containing an organosilicon resin having a siloxane bond as the main skeleton in the polyamide resin (A).

[0082] (Reinforcing material (D)) The resin composition used in the present invention may contain a reinforcing material (D) as needed. The reinforcing material (D) used in the present invention is a powdery reinforcing material formed of particles having a Mohs hardness of 5 or less, preferably greater than 3 and 5 or less. The shape of the particles of the reinforcing material (D) is not particularly limited as long as it can improve the strength, stiffness, etc. of the resin composition. For example, fibrous reinforcing materials formed of powdery fibrous particles, plate-like reinforcing materials formed of powdery plate-like particles, etc. can be cited, and fibrous reinforcing materials are preferred. Specific examples of the fibrous reinforcing material can include inorganic fibers such as potassium titanate fiber, wollastonite fiber, zinc oxide fiber, basic magnesium sulfate fiber, alumina fiber, silicon carbide fiber, and boron fiber. These reinforcing materials (D) can be used alone or in combination of multiple kinds.

[0083] From the viewpoint of further suppressing the reduction of the reinforcing effect brought about by the fibrous reinforcing material and further improving the wear resistance, the average fiber length of the fibrous reinforcing material is preferably 300 μm or less, more preferably 1 μm to 300 μm, still more preferably 1 μm to 200 μm, particularly preferably 3 μm to 100 μm, and most preferably 5 μm to 50 μm. The average aspect ratio of the fibrous reinforcing material is preferably 3 to 200, more preferably 3 to 100, still more preferably 3 to 50, and particularly preferably 3 to 40.

[0084] In the present invention, the fibrous particle means a particle in which when the longest side of the rectangular parallelepiped having the smallest volume in the circumscribed rectangular parallelepiped of the particle is defined as the major axis particle size L, the next longest side is defined as the minor axis particle size B, and the shortest side is defined as the thickness T (B > T), both L / B and L / T are 3 or more. The major axis particle size L corresponds to the fiber length, and the minor axis particle size B corresponds to the fiber diameter. The plate-like particle means a particle in which L / B is less than 3 and L / T is 3 or more.

[0085] From the viewpoint of further suppressing the weakening of the reinforcing effect brought about by the reinforcing material (D) and further improving the wear resistance, the reinforcing material (D) is preferably at least one of potassium titanate fiber and wollastonite fiber, more preferably potassium titanate fiber or wollastonite fiber, and still more preferably potassium titanate fiber.

[0086] Examples of the potassium titanate fiber include single crystal fibers represented by the general formula K2O·nTiO2 (where n is an integer of 2 to 8). Specific examples thereof include 4-potassium titanate fiber, 6-potassium titanate fiber, 8-potassium titanate fiber, and mixtures thereof.

[0087] The size of the potassium titanate fiber is not particularly limited as long as it is within the above size range, but the average fiber length is preferably 1 μm to 50 μm, more preferably 3 μm to 30 μm, still more preferably 3 μm to 20 μm; the average fiber diameter is preferably 0.01 μm to 1 μm, more preferably 0.05 μm to 0.8 μm, still more preferably 0.1 μm to 0.7 μm; the average aspect ratio is preferably 10 or more, more preferably 10 to 100, still more preferably 15 to 35.

[0088] The wollastonite fiber is an inorganic fiber formed of calcium metasilicate, and known fibers in the past can be widely used. The size of the wollastonite fiber is not particularly limited as long as it is within the size range of the above fibrous reinforcing material, but the average fiber length is preferably 5 μm to 180 μm, more preferably 10 μm to 100 μm, still more preferably 20 μm to 40 μm; the average fiber diameter is preferably 0.1 μm to 15 μm, more preferably 1 μm to 10 μm, still more preferably 2 μm to 7 μm; the average aspect ratio is preferably 3 or more, more preferably 3 to 30, still more preferably 3 to 15.

[0089] The above average fiber length and average fiber diameter can be measured by observing with a scanning electron microscope, and the average aspect ratio (average fiber length / average fiber diameter) can be calculated based on the average fiber length and average fiber diameter. For example, multiple fiber reinforcements can be photographed with a scanning electron microscope, and 300 fibrous reinforcements can be arbitrarily selected from the observed images to measure their fiber lengths and fiber diameters. The sum of all fiber lengths is accumulated and divided by the number of fibers, and the resulting value is used as the average fiber length. The sum of all fiber diameters is accumulated and divided by the number of fibers, and the resulting value is used as the average fiber diameter.

[0090] In the present invention, from the perspective of further improving the wettability with the polyamide resin (A) and further improving physical properties such as the mechanical properties of the obtained molded body, a treatment layer containing a surface treatment agent can also be formed on the surface of the reinforcing material (D).

[0091] Examples of the surface treatment agent include silane coupling agents and titanium coupling agents. Among them, a silane coupling agent is preferred, and an amino-based silane coupling agent, an epoxy-based silane coupling agent, and an alkyl-based silane coupling agent are more preferred. The above surface treatment agents can be used alone or in combination of two or more.

[0092] Examples of the amino-based silane coupling agent include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N-(1,3-dimethylbutyl)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, etc.

[0093] Examples of the epoxy-based silane coupling agent include 3-glycidoxypropyl(dimethoxy)methylsilane, 3-glycidoxypropyltrimethoxysilane, diethoxy(3-glycidoxypropyl)methylsilane, triethoxy(3-glycidoxypropyl)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.

[0094] Examples of the alkyl-based silane coupling agent include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, etc.

[0095] As a method for forming a treatment layer containing a surface treatment agent on the surface of the reinforcing material (D), known surface treatment methods can be used. For example, a method of dissolving the surface treatment agent in a solvent that promotes hydrolysis (such as water, ethanol, or a mixed solvent thereof) to form a solution, and spraying the solution on the reinforcing material (D).

[0096] When the surface treatment agent treats the surface of the reinforcing material (D) used in the present invention, the dosage of the surface treatment agent is, for example, but not particularly limited to, spraying a solution of the surface treatment agent in an amount of 0.1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the reinforcing material (D). By setting the dosage of the surface treatment agent within the above range, the adhesion to the polyamide resin (A) can be further improved, and the dispersibility of the reinforcing material (D) can be further improved.

[0097] (Other additives) Within the range that does not impair the preferred physical properties of the resin composition used in the present invention, various other additives commonly mixed with the resin composition can also be added thereto. As other additives, for example, plate-like fillers such as mica, mica, sericite, illite, talc, kaolin, montmorillonite, boehmite, smectite, vermiculite, titanium dioxide, sodium titanate, potassium magnesium titanate, potassium lithium titanate, boehmite; fibrous reinforcing materials other than the above carbon fibers such as glass fibers, ground glass fibers, aramid fibers; polyolefin resins such as polytetrafluoroethylene resin, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene; solid lubricants such as graphite, molybdenum disulfide, tungsten disulfide, boron nitride; mold release agents such as saturated fatty acid esters, unsaturated fatty acid esters, polyolefin waxes; pigments and colorants such as carbon black, titanium dioxide; flame retardants such as bromine-based flame retardants, phosphorus-based flame retardants; ultraviolet absorbers such as benzophenone-based compounds, benzotriazole-based compounds, hydroxyphenyltriazine-based compounds, cyclic iminoester-based compounds, cyanoacrylate-based compounds; heat stabilizers such as phenolic antioxidants, phosphite antioxidants, carbodiimide-based compound-based hydrolysis inhibitors; heat conductive agents such as graphite powder, alumina, magnesia; antistatic agents such as polyether ester amide, glycerol monostearate. These additives can be used alone or in combination of two or more.

[0098] When the resin composition used in the present invention contains other additives, within the range that does not impair the preferred physical properties of the resin gear of the present invention, the addition amount thereof is not particularly limited. For example, the content of other additives in 100% by mass of the total amount of the resin composition is preferably 10% by mass or less, more preferably 5% by mass or less.

[0099] The resin composition used in the present invention may contain glass fiber, milled glass fiber, and aramid fiber, or may not contain glass fiber, milled glass fiber, and aramid fiber. For example, in 100% by mass of the total amount of the resin composition, the content of glass fiber, milled glass fiber, and aramid fiber is preferably less than 5% by mass, more preferably 3% by mass or less, and particularly preferably 1% by mass or less, and may not contain glass fiber, milled glass fiber, and aramid fiber. In this case, it is possible to more easily adjust the fracture toughness K1c of the resin gear to the target range.

[0100] <Manufacturing method of resin composition> The resin composition used in the present invention contains a polyamide resin (A) and carbon fiber (B), and can be manufactured by mixing an organosilicon resin (C), a reinforcing material (D) with a Mohs hardness of 5 or less, and other additives as needed and heating. The method of mixing and heating is preferably melt-kneading.

[0101] For melt-kneading, known melt-kneading devices such as twin-screw extruders can be used. Specifically, examples include (1) a method of premixing each component using a mixing device (drum, Henschel mixer, etc.), performing melt-kneading using a melt-kneading device, and performing granulation using a granulating device (granulator, etc.); (2) a method of preparing a masterbatch of the required components, mixing other components as needed, performing melt-kneading using a melt-kneading device, and performing granulation; (3) a method of supplying each component to a melt-kneading device for granulation, etc.

[0102] The processing temperature in melt-kneading is not particularly limited as long as it is a temperature at which the polyamide resin can be melted. Usually, the barrel temperature of the melt-kneading device used for melt-kneading is adjusted to this range. In this way, a resin composition capable of exhibiting the required effects can be manufactured.

[0103] <Manufacturing method and use of resin gear> The resin gear of the present invention is formed from the above resin composition. As a method of forming the above resin composition into the resin gear of the present invention, there is no particular limitation, and various methods known in the art can be adopted. For example, it can be manufactured by injecting the granular resin composition into an injection molding device equipped with a set mold. In addition, the resin gear of the present invention can be formed by performing conventional molding processes such as cutting on the resin composition after it is formed into a plate shape or a rod shape. In addition, a molding method combining the above molding methods can also be adopted.

[0104] By adopting the manufacturing method and molding method of the above resin composition, the fracture toughness K1c is set to 8.0 MPa·m 1 / 2 ~14.0 MPa·m 1 / 2, it is possible to improve the rigidity of the above resin gear, maintain excellent mechanical strength, and produce the resin gear of the present invention with excellent durability and capable of reducing the erosion to the target component.

[0105] It should be noted that the fracture toughness K1c of the resin gear can be adjusted by the contents of each component such as polyamide resin (A), carbon fiber (B), silicone resin (C) as required, reinforcing material (D) with Mohs hardness of 5 or less, and other additives in the resin composition, the type of polyamide resin (A), the average fiber length and / or average fiber diameter of carbon fiber (B), etc.

[0106] Examples The following is a specific description based on examples and comparative examples, but the present invention is not limited thereby. It should be noted that the raw materials used in the examples and comparative examples of the present invention are specifically as follows.

[0107] <Polyamide resins 1-3> Polyamide resin 1: Polyamide 66 (PA66), manufactured by DuPont, trade name "Zytel 103HSL", melting point 264 °C (DSC method) Polyamide resin 2: Polyamide 46 (PA46), manufactured by DSM, product name "Stanyl TW341-N", melting point 295 °C (DSC method) Polyamide resin 3: Semi-aromatic polyamide (PAMXD6), manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Nylon MXD6", melting point 237 °C (DSC method) <Carbon fiber> Carbon fiber: PAN-based carbon fiber, average fiber length 6 mm, average fiber diameter 7 μm <Silicone resin> Silicone resin: Silicone additive for thermoplastic resin (manufactured by WACKER SILICONES CORPORATION, trade name "GENIOPLAST ® PelletS", content of fumed silica: 30% by mass) <Reinforcing material> Potassium titanate fiber: average fiber length 15 μm, average fiber diameter 0.5 μm, Mohs hardness: 4 (manufactured by Otsuka Chemical Co., Ltd., trade name "TISMO D101") Glass fiber: average fiber length 3 μm, average fiber diameter 13 μm, Mohs hardness: 6-7 (manufactured by Nippon Electric Glass Co., Ltd., trade name "glass chopped strands ECS03T-297").

[0108] <Examples 1 to 3 and Comparative Examples 1 to 3> Using a twin-screw extruder, each material was melt-kneaded according to the mixing ratios shown in Table 1 to obtain pellets. It should be noted that the barrel temperature of the twin-screw extruder in Examples 1 to 3 and Comparative Examples 1 to 3 was 290°C in Example 1 and Comparative Example 1, 315°C in Example 2, 280°C in Example 3 and Comparative Example 2, and 260°C in Comparative Example 3.

[0109] The obtained pellets were molded into JIS test pieces and resin gears using an injection molding device to obtain JIS test pieces and resin gears as evaluation samples. It should be noted that the barrel temperature of the injection molding device in Examples 1 to 3 and Comparative Examples 1 to 3 was 300°C in Example 1, Example 3, Comparative Example 1, and Comparative Example 2, 320°C in Example 2, and 260°C in Comparative Example 3. The mold temperature was 120°C in Example 1, Example 3, Comparative Example 1, and Comparative Example 2, and 140°C in Example 2 and Comparative Example 3.

[0110] <Evaluation> The above evaluation samples obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated as follows.

[0111] (Fracture toughness) In accordance with ASTM D5045-93, the fracture toughness of the test pieces (4 mm in length, 63 mm in width, and 13 mm in height) of the examples and comparative examples prepared by injection molding was measured using the "Mechanical Tester AutoGraph AGS-J" manufactured by Shimadzu Corporation. The fracture toughness K1c is a parameter representing the resistance to crack propagation, and the higher the value, the higher the fracture toughness.

[0112] (Flexural strength, flexural modulus) In accordance with JIS K7271, the flexural strength and flexural modulus of the obtained evaluation samples were measured by a three-point bending test with a support span of 60 mm using AutoGraph AG-5000 (manufactured by Shimadzu Corporation).

[0113] (Static friction test) Using a static friction tester (manufactured by Kyowa Interface Science Co., Ltd., model "TRIBOSTAR TS 501"), under the conditions of a load of 100 g, a speed of 5 mm / second, and a moving distance of 20 mm, and with the test material being stainless steel (SUS304, φ3 mm), the static friction coefficient of the obtained evaluation samples was measured. The static friction coefficient was taken as the average value of 200 repetitions.

[0114] (Thrust wear test) In accordance with the method of JIS K7218 A, the specific wear rate (wear amount of the target member) of the friction and wear test pieces (hollow cylinders with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm) of the examples and comparative examples made by injection molding was measured using a Suzuki-type friction and wear tester (EFM-III-F, manufactured by A&D Company). The test conditions were a surface pressure of 1.0 MPa, a circumferential speed of 0.3 m / second, a continuous test for 7 hours, a lubrication condition of no lubrication, a temperature of room temperature (25°C ± 2°C), and the target member was carbon steel S45C (hollow cylinder with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm) or brass (hollow cylinder with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm). The test with the brass as the target member ended when the height change due to wear reached 2 mm.

[0115] (Gear Test) In accordance with JIS B1759, a life evaluation test was conducted on the gear test pieces (module: 1.0, number of teeth: 48, pitch diameter: 48.0 mm, outside diameter of the addendum circle: 50.0 mm, tooth width: 6.0 mm, pressure angle: 20°) of the examples and comparative examples made by injection molding using a gear durability tester (manufactured by Yuasa System Devices Co., Ltd.), and the torque transmission efficiency was measured. The test conditions were set as a load torque of 3.0 N·m, a rotational speed of 800 rpm, a lubrication condition of no lubrication, an ambient temperature of no temperature control (room temperature 25°C ± 2°C), and the target member was S45C (module: 1.0, number of teeth: 48, pitch diameter: 48.0 mm, outside diameter of the addendum circle: 50.0 mm, tooth width: 6.0 mm, pressure angle: 20°). The torque transmission efficiency (efficiency in Table 1) was measured using torque sensors assembled on the input shaft and output shaft of the tester, taking the ratio of the output torque to the input torque, and taking the average value during the period from the start of the test to the tooth breakage in the durability test. In addition, the number of durability cycles is the total number of rotations before cracks or breakages appear on the teeth.

[0116] The results are shown in Table 1 below.

[0117] [Table 1]

[0118] As can be seen from Table 1: Formed from a molded body of a resin composition containing polyamide resin (A) and carbon fiber (B) and, if necessary, also containing silicone resin (C) and reinforcing material (D), the fracture toughness K1c is 8.0 MPa·m 1 / 2 ~14.0 MPa·m 1 / 2The evaluation samples of Examples 1 to 3 maintained excellent mechanical strength, had excellent durability, and a low static friction coefficient. Moreover, from the results of the thrust wear test of the brass, which is softer than S45C in texture among the evaluation samples of Examples 1 to 3, used as the target member, it can be seen that even when carbon fiber with high erosiveness to the target member was added, the erosiveness to the target member was relatively low. Moreover, from the comparison between Example 1 and Example 3, it can be seen that by combining the reinforcing material and the silicone resin, not only the durability was improved, but also the static friction coefficient was further reduced.

Claims

1. A resin gear, characterized in that, the resin gear is made of a molded body of a resin composition containing polyamide resin (A) and carbon fiber (B), The fracture toughness K1c is 8.0 MPa·m 1 / 2 ~14.0 MPa·m 1 / 2 .

2. The resin gear according to claim 1, characterized in that, the resin composition further contains silicone resin (C).

3. The resin gear according to claim 1 or 2, characterized in that, the resin composition further contains a reinforcing material (D), and the Mohs hardness of the reinforcing material (D) is 5 or less.

4. The resin gear according to claim 3, characterized in that, the reinforcing material (D) is at least one of potassium titanate fiber and wollastonite fiber.

5. The resin gear according to claim 1 or 2, characterized in that, the polyamide resin (A) is an aliphatic polyamide resin.

6. The resin gear according to claim 1 or 2, characterized in that, the content of the carbon fiber (B) in 100% by mass of the total amount of the resin composition is 10% by mass to 40% by mass.

7. The resin gear according to claim 2, characterized in that, the content of fumed silica in the silicone resin (C) is 20% by mass to 40% by mass.

8. The resin gear according to claim 2 or 7, characterized in that, the content of the silicone resin (C) in 100% by mass of the total amount of the resin composition is 0.1% by mass to 8% by mass.

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