Grease composition and control cable

Abstract

Provided is a grease composition capable of improving total performance of abrasion resistance and stick slip resistance by being applied to the outer peripheral surface or the like of an inner cable. This grease composition contains a base oil, a modified silicone, a thickener, and a solid lubricant. The solid lubricant contains two or more melamine cyanurates having different volume average particle diameters.

Description

Grease composition and control cable

[0001] This invention relates to a grease composition and a control cable.

[0002] A control cable transmits force or movement from a user's hand to a location far away from the user. It consists of an inner cable slidably inserted into an outer casing. For example, when transmitting the movement of a car's gear shift lever to the transmission via a control cable, when the user operates the gear shift lever, the inner cable is pushed and pulled, thereby transmitting the user's operating force to the transmission.

[0003] In such control cables, grease is often applied to the outer surface of the inner cable. This reduces the resistance (sliding resistance) that occurs when the inner cable slides against the inner surface of the outer casing, thereby preventing a decrease in load efficiency.

[0004] Patent Document 1 describes a grease composition containing a silicone base oil, a thickener, a layered compound powder, and polytetrafluoroethylene powder, which can prevent a decrease in the load efficiency of a control cable.

[0005] Japanese Patent Publication No. 2012-255094

[0006] The polytetrafluoroethylene used in Patent Document 1 is highly stable, but concerns have been raised about its impact on the natural environment and human health, and its use is expected to be restricted by environmental regulations. Therefore, alternative materials to polytetrafluoroethylene are being considered, and it has become necessary to investigate formulations that compensate for the performance degradation resulting from the reduction or elimination of polytetrafluoroethylene.

[0007] The present invention aims to provide a grease composition that can improve the overall performance of wear resistance and stick-slip resistance by being applied to the outer surface of an inner cable, etc.

[0008] The inventors of the present invention have found that a grease composition containing a base oil, a modified silicone, a thickener, and a solid lubricant containing two or more kinds of melamine cyanurates having different volume average particle diameters can solve the above problems, and have completed the present invention.

[0009] That is, the present invention provides: [1] A grease composition containing a base oil, a modified silicone, a thickener, and a solid lubricant, wherein the solid lubricant contains two or more kinds of melamine cyanurates having different volume average particle diameters; [2] The grease composition according to [1] above, wherein the solid lubricant contains melamine cyanurate (MCA1) having a volume average particle diameter of 6.0 μm or less and melamine cyanurate (MCA2) having a volume average particle diameter of 10 to 30 μm, and the mass content ratio of MCA1 and MCA2 in the solid lubricant is 60:40 to 99.9:0.1; [3] The grease composition according to [1] or [2] above, wherein the total content of melamine cyanurate in the grease composition is 1 to 30% by mass; [4] The grease composition according to any one of [1] to [3] above, wherein the base oil contains a silicone base oil, and the content of the silicone base oil in the grease composition is 45% by mass or more and 70% by mass or less; [5] The modified silicone is represented by the following general formula (1), (2), or (3): [In the formula, R 1 , 2 and R 2 each independently represents -W 1 -COOH, or -W 1 -NH2; R 3 when there are a plurality, each independently represents -W 1 -COOH, -W 1 -NH2, or -W 1 -NH-W 2 -NH2; R represents a linear or branched alkyl group having 1 to 30 carbon atoms; R 4 represents -W 1 -COOH; W 1 and W 2The present invention relates to a grease composition according to any one of [1] to [4] above, wherein the grease composition is one or more modified silicones selected from the group consisting of compounds represented by [1] to [4] above, wherein if there are multiple, each independently represents a linear or branched alkylene group having 1 to 30 carbon atoms; and m and n each independently represent 1 or more repeating units], [6] the grease composition according to any one of [1] to [5] above, wherein the content of the modified silicone in the grease composition is 0.01 to 10% by mass, and [7] a control cable in which the grease composition according to any one of [1] to [6] above is applied to the outer surface of the inner cable.

[0010] According to the present invention, a grease composition is provided that, when applied to the outer surface of an inner cable or the like, can improve the overall performance of wear resistance and stick-slip resistance.

[0011] This is a cross-sectional view of a control cable according to one embodiment of the present invention. This is a cross-sectional view showing another embodiment of the control cable. This is a schematic plan view of an apparatus used for durability testing.

[0012] A method for manufacturing a control cable, including a method for manufacturing a grease composition according to this embodiment, will be described in detail below. However, the following description is illustrative for explaining this embodiment and is not intended to limit the technical scope of the present invention to this scope only. In this specification, when a numerical range is indicated using "~", it includes the numerical values ​​at both ends of that range.

[0013] <Grease Composition> The grease composition according to this embodiment contains a base oil, modified silicone, a thickener, and a solid lubricant as essential components. The solid lubricant is characterized by containing two or more types of melamine cyanurates with different volume-average particle sizes. The content of each of the above components contained in the grease composition according to this embodiment can be appropriately selected from the range described so that the total content in the grease composition is 100% by mass or less.

[0014] (Base oil) The base oil is not particularly limited as long as it is a common base oil used in greases, but examples include mineral oil, synthetic hydrocarbon oil, synthetic ester oil, vegetable oil, animal oil, silicone base oil, polyglycol-based synthetic oil, phenyl ether-based synthetic oil, fluorine-based synthetic oil, etc. Among these, from the viewpoint of lubrication characteristics over a wide temperature range, it is preferable to include silicone base oil, and a base oil consisting only of silicone base oil is also acceptable. The base oil may be used alone or in combination of two or more types.

[0015] Examples of silicone base oils include dimethyl silicone oils such as dimethylpolysiloxane (dimethicone) and highly polymerized methylpolysiloxane; methylphenyl silicone oils such as methylphenylpolysiloxane; cyclic silicone oils such as methylcyclopolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; modified silicones such as polyether-modified silicones, carboxy-modified silicones, fatty acid-modified silicones, alcohol-modified silicones, aliphatic alcohol-modified silicones, epoxy-modified silicones, fluorine-modified silicones, and alkyl-modified silicones; and methylhydrogenpolysiloxane and dimethiconol. These silicone base oils may be used individually or in combination of two or more. Note that the modified silicones described later are not included in the silicone base oils.

[0016] The kinematic viscosity of the base oil at 25°C is 50 to 2000 mm². 2 / s is preferred, and 100 to 1500 mm 2 / s is more preferable, 200 to 1000 mm 2 / s is even more preferable. Kinematic viscosity of 50 mm 2 By setting the kinematic viscosity to 2000 mm² or higher, a sufficient oil film is formed on the outer surface of the inner cable or the inner surface of the outer casing. This suppresses wear on the outer surface of the inner cable or the inner surface of the outer casing, preventing a decrease in load efficiency. On the other hand, if the kinematic viscosity is 2000 mm² or higher... 2By setting the value to less than / s, the amount of grease composition that penetrates between the outer surface of the inner cable and the inner surface of the outer casing is reduced, preventing an increase in sliding resistance. The kinematic viscosity of the base oil in this specification is measured at 25°C using a glass capillary viscometer in accordance with JIS K 2283:2000.

[0017] The proportion of silicone base oil in the base oil is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0018] From the viewpoint of the effects of the present invention, the content of base oil (preferably silicone base oil) in the grease composition is preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more. Furthermore, the content of base oil (preferably silicone base oil) in the grease composition is preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably less than 57% by mass, and particularly preferably 55% by mass or less.

[0019] (Modified Silicone) The grease composition according to this embodiment contains modified silicone as an essential component. By using melamine cyanurate and modified silicone in combination, the decrease in load efficiency of the grease composition can be suppressed and the stick-slip resistance can be significantly improved. The modified silicone is not particularly limited, but examples include carboxyl-modified silicone, amino-modified silicone, carbinol-modified silicone, polyether-modified silicone, epoxy-modified silicone, etc. These modified silicones may be used individually or in combination of two or more. In particular, from the viewpoint of the effects of the present invention, one or more modified silicones selected from the group consisting of carboxyl-modified silicone and amino-modified silicone are preferred, and carboxyl-modified silicone is more preferred.

[0020] Examples of the carboxyl-modified silicone include silicone modified with a carboxyl group at the terminal, silicone modified with a carboxyl group in the side chain, etc., and silicone modified with a carboxyl group in the side chain is preferred.

[0021] Examples of the amino-modified silicone include silicone modified with an amino group at the terminal, silicone modified with an amino group in the side chain, etc., and silicone modified with an amino group in the side chain is preferred.

[0022] Specific examples of the carboxyl-modified silicone and the amino-modified silicone include, for example, the following general formulas (1), (2), or (3): [In the formula, R 1 and R 2 each independently represent -W 1 -COOH, or -W 1 -NH2; when there are a plurality of R 3 they each independently represent -W 1 -COOH, -W 1 -NH2, or -W 1 -NH-W 2 -NH2; R represents a linear or branched alkyl group having 1 to 30 carbon atoms (preferably 2 to 24); R 4 represents -W 1 -COOH; W 1 and W 2 each independently represent a linear or branched alkylene group having 1 to 30 carbon atoms (preferably 2 to 24) when there are a plurality of them; m and n each independently represent a repeating number of 1 or more]. One or more modified silicones selected from the group consisting of compounds represented by these formulas are included. Among them, one or more modified silicones selected from the group consisting of compounds represented by formula (2) are preferred, and one or more carboxyl-modified silicones (that is, when R 3 is -W 1 8]-COOH) selected from the group consisting of compounds represented by formula (2) are more preferred.

[0023] The kinematic viscosity at 25°C of the modified silicone (preferably, one or more modified silicones selected from the group consisting of carboxyl-modified silicone and amino-modified silicone; more preferably, one or more modified silicones selected from the group consisting of the compounds represented by the general formula (1), (2), or (3)) is preferably 100 to 10,000 mm 2 / s, more preferably 300 to 7,500 mm 2 / s, even more preferably 500 to 5,000 mm 2 / s, particularly preferably 700 to 3,000 mm 2 / s.

[0024] From the viewpoint of the effects of the present invention, the content of the modified silicone in the grease composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, still more preferably 1.0% by mass or more, and particularly preferably 1.5% by mass or more. On the other hand, from the viewpoint of suppressing the curing of the grease composition over time, it is preferably 10% by mass or less, more preferably 8.0% by mass or less, even more preferably 6.0% by mass or less, and particularly preferably 4.0% by mass or less.

[0025] (Thickener) The thickener is not particularly limited as long as it is a material commonly used as a thickener for grease. Specific examples of the thickener include, for example, metal soap-based thickeners, composite metal soap-based thickeners, urea-based compounds, etc., with metal soap-based thickeners being preferred and lithium soap-based thickeners being more preferred. The thickener may be used alone or in combination of two or more.

[0026] The lithium soap-based thickener (lithium soap) is not particularly limited, but examples include lithium salts of higher fatty acids having 10 to 28 carbon atoms, lithium salts of higher hydroxy fatty acids having 10 to 28 carbon atoms and having one or more hydroxyl groups, or mixtures thereof. Examples of the higher fatty acids include lauric acid, palmitic acid, stearic acid, linoleic acid, arachidic acid, myristic acid, pentadecanoic acid, heptadecanoic acid, oleic acid, arachidonic acid, and behenic acid, but stearic acid is preferred because it has a good consistency yield (degree of hardening of the grease). Examples of the higher hydroxy fatty acids include 12-hydroxystearic acid, 12-hydroxylauric acid, and 16-hydroxypalmitic acid, but 12-hydroxystearic acid is preferred because it is readily available and inexpensive.

[0027] Specific examples of lithium soaps include lithium laurate, lithium stearate, lithium 12-hydroxystearate, and mixtures thereof.

[0028] From the viewpoint of preventing a decrease in load efficiency, the content of the thickener (preferably metal soap, more preferably lithium soap) in the grease composition is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. On the other hand, from the viewpoint of ensuring the lifespan of the grease composition, it is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less.

[0029] (Solid Lubricant) The grease composition according to this embodiment contains two or more melamine cyanurates with different volume-average particle sizes as a solid lubricant. By using two or more melamine cyanurates with different volume-average particle sizes in combination, it is possible to suppress the decrease in load efficiency of the grease composition and significantly improve its stick-slip resistance.

[0030] The solid lubricant according to this embodiment can, for example, contain melamine cyanurate with a small particle size having a volume-average particle diameter of 8.0 μm or less and melamine cyanurate with a large particle size having a volume-average particle diameter greater than 8.0 μm. Preferably, it contains melamine cyanurate (MCA1) with a volume-average particle diameter of 6.0 μm or less (preferably 0.1 to 6.0 μm, more preferably 1.0 to 6.0 μm) and melamine cyanurate (MCA2) with a volume-average particle diameter of 10 to 30 μm (preferably 10 to 20 μm). Note that the volume-average particle diameter in this specification is a value measured according to the laser diffraction scattering method.

[0031] From the viewpoint of the effects of the present invention, the mass content ratio of small-particle melamine cyanurate to large-particle melamine cyanurate (preferably MCA1 and MCA2) in the solid lubricant is preferably 55:45 to 99.9:0.1, more preferably 60:40 to 99.9:0.1, even more preferably 65:30 to 99:1, even more preferably 70:30 to 98:2, even more preferably 75:25 to 97:3, and particularly preferably 80:20 to 96:4.

[0032] In addition to melamine cyanurate, other solid lubricants that can be used include polytetrafluoroethylene, tungsten disulfide, molybdenum disulfide, graphite, graphite fluoride, mica, boron nitride, and transition metal dichalcogenides.

[0033] From the viewpoint of the effects of the present invention, the total content of the solid lubricant (preferably melamine cyanurate) in the grease composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more. Furthermore, the total content of the solid lubricant (preferably melamine cyanurate) in the grease composition is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0034] The proportion of melamine cyanurate (preferably MCA1 and MCA2) in the solid lubricant is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass. In other words, it may also be a solid lubricant consisting only of melamine cyanurate.

[0035] From the viewpoint of environmental impact, the polytetrafluoroethylene content in the grease composition is preferably less than 4.8% by mass, more preferably less than 3.0% by mass, even more preferably less than 1.0% by mass, even more preferably less than 0.5% by mass, even more preferably less than 0.1% by mass, even more preferably less than 0.01% by mass, and particularly preferably 0% by mass.

[0036] (Other Additives) The grease composition according to this embodiment may further contain one or more of the additives listed below. Examples of additives include: metal-based detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates; detergent dispersants such as alkenyl succinimide, alkenyl succinimide borylated modified products, benzylamine, and alkyl polyamines; anti-wear agents such as methylene bisdithiocarbamate, polycarboxylate, zinc-based anti-wear agents, sulfur-based anti-wear agents, and phosphorus-based anti-wear agents; thickeners such as polymethacrylate, ethylene-propylene copolymer, styrene-isoprene copolymer, styrene-isoprene copolymer hydride, and polyisobutylene; alkylphenols such as 2,6-di-tert-butyl-p-cresol, and 4,4'-methylenebis-(2,6-di-t- Antioxidants include bisphenols such as butylphenol, phenolic compounds such as n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and aromatic amine compounds such as naphthylamines or dialkyldiphenylamines; extreme pressure agents such as sulfurized olefins, sulfurized oils and fats, methyl trichlorostearate, chlorinated naphthalene, benzyl iodide, fluoroalkylpolysiloxane, and lead naphthenate; rust inhibitors such as carboxylic acids such as stearic acid, dicarboxylic acids, metal soaps, carboxylic acid amine salts, metal salts of heavy sulfonic acids, and carboxylic acid partial esters of polyhydric alcohols; and corrosion inhibitors such as benzotriazole and benzimidazole.

[0037] The grease composition according to this embodiment is produced by mixing predetermined amounts of a base oil, modified silicone, thickener, and solid lubricant by a known method, and adding at least one of the above-mentioned additives as needed.

[0038] <Control Cable> The control cable according to this embodiment is constructed by inserting an inner cable into an outer casing, and applying the grease composition according to this embodiment to the outer surface of the inner cable. The outer surface of the inner cable is made of resin or metal, and the inner surface of the outer casing is made of resin.

[0039] The amount of grease composition applied per unit area to the outer surface of the inner cable should be 45 to 220 g / m², from the viewpoint of balancing wear suppression effect and lubrication performance. 2 Preferably, 50 to 210 g / m² 2 This is more preferable. The amount applied per unit area to the outer surface of the inner cable can be the amount of grease composition interposed per unit area between the outer surface of the inner cable and the inner surface of the outer casing.

[0040] Here, we will describe the "outer surface of the inner cable" which serves as the basis for determining the amount of grease composition to be applied. The outer surface of the inner cable is a virtual circumferential surface that is in contact with the outermost strand portion in the radial direction of the inner cable. As shown in Figure 1, if a coating layer 69 is provided on the radially outer side of the strand wire 63, the outer surface of the inner cable becomes the outer surface of the coating layer 69. As shown in Figure 2, the surface of the strand wire 22 facing radially outward becomes the outer surface of the inner cable.

[0041] This embodiment is not limited to the configurations of the inner cable and outer casing. The following outlines the configurations of the inner cable and outer casing.

[0042] The inner cable is preferably constructed by twisting strand side wires onto the outer surface of a shaft or strand core wire. A coating layer or clearance may also be provided on the radially outer side of the strand side wires. The shaft is preferably made of a material that has moderate rigidity while also possessing toughness, such as carbon steel wire or carbon fiber. The strands, like the shaft, are preferably made of a material that has moderate rigidity while also possessing toughness. The coating layer covers the strands and may be made of a material with moderate rigidity, similar to the shaft, or of a resin such as nylon 66.

[0043] The outer casing preferably consists of three layers: a liner through which the inner cable is inserted, a shield wire, and a coating layer. The liner may be made of a resin such as polypropylene or polyester. The shield wire is arranged on the outer surface of the liner and twisted in a predetermined direction, and may be made of a material that has appropriate rigidity and toughness, similar to the shaft of the inner cable. The coating layer covers the shield wire and may be made of a resin such as polypropylene or polyester.

[0044] The embodiments will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0045] In this example, the following raw materials were used: Base oil: Dimethylpolysiloxane (kinematic viscosity at 25°C: 500 mm) 2 / s) Modified silicone 1: DOWSIL BY 16-880 Fluid manufactured by Dow Toray Ltd. (represented by general formula (2), a silicone modified with carboxyl groups in the side chains, kinematic viscosity at 25°C: 2200 mm) 2 / s) Modified Silicone 2: DOWSIL CF 1029 (represented by general formula (2), a silicone modified with amino groups in the side chains, manufactured by Dow Toray Ltd., kinematic viscosity at 25°C: 1200 mm) 2 / s) Thickener: S7000 (Lithium Stearate) manufactured by Sakai Chemical Industry Co., Ltd. MCA1: Melamine cyanurate (Volume average particle size: 5.0 μm) MCA2: Melamine cyanurate (Volume average particle size: 14.0 μm) PTFE: Polytetrafluoroethylene (Volume average particle size: 4.0 μm)

[0046] <Preparation of Grease Compositions> Following the formulations described in Table 1, various raw materials were thoroughly stirred in a heat-resistant container to disperse the thickener, and then milled to obtain each test grease composition.

[0047]

[0048] <Fabrication of Control Cable 50> Using the obtained grease composition, the control cable 50 shown in Figure 1 was fabricated. Figure 1 is a schematic diagram showing a cross-section of the control cable 50.

[0049] Specifically, an inner cable 60 and an outer casing 70 constituting the control cable 50 were prepared. The inner cable 60 consists of a strand core wire 61, strand side wires 63, and a coating layer 69. In the strand side wires 63, six second strand side wires 65 are arranged on the outer surface of the strand core wire 61 and twisted in the Z direction, while six third strand side wires 67A and six first strand side wires 67B are arranged outside the second strand side wires 65 so as to alternate in the circumferential direction and are twisted in the S direction. The strand side wires 63 thus constructed are covered with a coating layer 69.

[0050] The strand core wire 61, the second strand side wire 65, the third strand side wire 67A, and the first strand side wire 67B are made of carbon steel wire rods specified in JIS G 3506 SWRH62B that have been galvanized, and the coating layer 69 is made of nylon 66 resin (product name "Leona" manufactured by Asahi Kasei Corporation).

[0051] The outer diameter of the inner cable 60 is 4.3 mm, the wire diameter of the strand core wire 61 is 0.65 mm, the wire diameter of the second strand side wire 65 is 0.6 mm, the wire diameter of the third strand side wire 67A is 0.7 mm, and the wire diameter of the first strand side wire 67B is 0.5 mm.

[0052] Furthermore, the outer casing 70 consists of a liner 71 through which the inner cable 60 is inserted, 20 shield wires 73, and a coating layer 75. The shield wires 73 are arranged on the outer surface of the liner 71 and twisted in the Z direction, and are covered with the coating layer 75.

[0053] The liner 71 is made of a thermoplastic resin containing potassium titanate fibers (product name "Pochicon" manufactured by Otsuka Chemical Co., Ltd.), the shield wire 73 is made of a carbon steel wire rod specified in JIS G 3506 SWRH62A that has been zinc-plated, and the coating layer 75 is made of a polyester thermoplastic elastomer (product name "Perprene" manufactured by Toyobo Co., Ltd.).

[0054] The outer diameter of the outer casing 70 is 9.0 mm, the outer diameter of the liner 71 is 6.0 mm, the inner diameter of the liner 71 is 4.6 mm, and the wire diameter of the shield wire 73 is 0.884 mm.

[0055] Then, each of the obtained test grease compositions was applied at a rate of 63 g / m² per unit area. 2 The inner cable 60 was coated with the coating on its outer surface, and the inner cable 60 was inserted into the liner 71 of the outer casing 70 to obtain the control cable 50.

[0056] <Durability Test> A durability test was conducted on the obtained control cable 50. Figure 3 is a schematic plan view of the apparatus used for the durability test.

[0057] Specifically, the control cable 50 was routed in the shape described in "Routing" in Table 9 and placed inside the constant temperature bath 91. Then, a spring 95 was connected to one end of the inner cable 60 to apply a test load W, and the other end of the inner cable 60 was moved back and forth using a push-pull force measuring instrument 93 at a speed of 30 cpm (cycle / min) and a stroke length of 30 mm. The unloaded sliding resistance and operating load F (tensile force) were measured initially and after 1 million cycles, respectively. The load efficiency was then calculated initially and after 1 million cycles using the formula (Load Efficiency (%)) = {(Test Load W) / (Operating Load F)} × 100. This test was performed by changing the temperature of the constant temperature bath 91 to 130°C, 25±5°C, and -40°C, and evaluated according to the evaluation criteria in Tables 2, 3, and 4. A higher load efficiency indicates that wear on the outer surface of the inner cable and the inner surface of the outer casing is suppressed. The results are shown in Table 8.

[0058]

[0059]

[0060]

[0061] <Stick-Slip Test> Under the conditions of the durability test described above, the stick-slip ratio of the inner cable 60 was calculated initially and after 1 million cycles. Specifically, the operating load F1 derived from the static friction coefficient required to start the inner cable 60 from a stationary state, and the operating load F2 derived from the dynamic friction coefficient required to move the inner cable 60 at a constant speed were monitored, and the stick-slip ratio F1 / F2 was calculated. This test was conducted by changing the temperature of the constant temperature chamber 91 to 130°C, 25±5°C, and -40°C, and the stick-slip resistance performance was evaluated according to the evaluation criteria in Tables 5, 6, and 7. The results are shown in Table 8.

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] <Fabrication of Control Cable 10> Using the obtained grease composition, the control cable 10 shown in Figure 2 was fabricated. Figure 2 is a schematic diagram showing a cross-section of the control cable 10.

[0068] Specifically, an inner cable 20 and an outer casing 30 that constitute the control cable 10 were prepared. The inner cable 20 consists of a shaft 21 and 12 strands of wire 22, the strands of wire 22 are arranged on the outer surface of the shaft 21 and twisted in the S direction.

[0069] The shaft 21 is made of carbon steel wire rod specified in JIS G 3506 SWRH72A that has been subjected to oil tempering treatment, and the strand wire 22 is made of carbon steel wire rod specified in JIS G 3506 SWRH62B that has been zinc-plated.

[0070] The outer diameter of the inner cable 20 is 2.2 mm, the outer diameter of the shaft 21 is 1.4 mm, and the wire diameter of the stranded wire 22 is 0.4 mm. Here, the outer diameter of the inner cable 20 can be the diameter of the circumscribed circle 41 of the stranded wire 22.

[0071] Furthermore, the outer casing 30 consists of a liner 31 through which the inner cable 20 is inserted, 20 shield wires 33, and a coating layer 35. The shield wires 33 are arranged on the outer surface of the liner 31 and twisted in the Z direction, and are covered with the coating layer 35.

[0072] The liner 31 is made of polybutylene terephthalate resin (product name "Duranex" manufactured by Polyplastics Co., Ltd.), the shield wire 33 is made of carbon steel wire rod specified in JIS G 3506 SWRH62A which has been zinc-plated, and the coating layer 35 is made of polyester thermoplastic elastomer (product name "Perprene" manufactured by Toyobo Co., Ltd.).

[0073] The outer diameter of the outer casing 30 is 7.1 mm, the outer diameter of the liner 31 is 3.95 mm, the inner diameter of the liner 31 is 2.35 mm, and the wire diameter of the shield wire 33 is 0.7 mm.

[0074] Then, each of the obtained test grease compositions was applied at a rate of 103 g / m² per unit area. 2 The inner cable 20 was coated with the coating on its outer surface, and the inner cable 20 was inserted into the liner 31 of the outer casing 30 to obtain the control cable 10.

[0075] <Durability Test> A durability test was conducted on the obtained control cable 10. Figure 3 is a schematic plan view of the apparatus used for the durability test.

[0076] Specifically, the control cable 10 was routed in the shape described in "Routing" in Table 17 and placed inside the constant temperature bath 91. Then, a spring 95 was connected to one end of the inner cable 20 to apply a test load W, and the other end of the inner cable 20 was moved back and forth using a push-pull force measuring instrument 93 at a speed of 30 cpm (cycle / min) and a stroke length of 30 mm. The unloaded sliding resistance and operating load F (tensile force) were measured initially and after 1 million cycles, respectively. The load efficiency was then calculated initially and after 1 million cycles using the formula (Load Efficiency (%)) = {(Test Load W) / (Operating Load F)} × 100. This test was performed by changing the temperature of the constant temperature bath 91 to 130°C, 25±5°C, and -40°C, and evaluated according to the evaluation criteria in Tables 10, 11, and 12. A higher load efficiency indicates that wear on the outer surface of the inner cable and the inner surface of the outer casing is suppressed. The results are shown in Table 16.

[0077]

[0078]

[0079]

[0080] <Stick-Slip Test> Under the conditions of the durability test described above, the stick-slip ratio of the inner cable 60 was calculated initially and after 1 million cycles. Specifically, the operating load F1 derived from the static friction coefficient required to start the inner cable 60 from a stationary state, and the operating load F2 derived from the dynamic friction coefficient required to move the inner cable 60 at a constant speed were monitored, and the stick-slip ratio F1 / F2 was calculated. This test was conducted by changing the temperature of the constant temperature chamber 91 to 130°C, 25±5°C, and -40°C, and the stick-slip resistance performance was evaluated according to the evaluation criteria in Tables 13, 14, and 15. The results are shown in Table 16.

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] The results in Tables 8 and 16 show that a control cable coated with the grease composition according to this embodiment, which contains a base oil, modified silicone, thickener, and two or more types of melamine cyanurate with different volume-average particle sizes, maintains or reduces no-load sliding resistance over a wide temperature range, and comprehensively improves wear resistance and stick-slip resistance, compared to a case where PTFE is used as a solid lubricant.

[0087] 10 Control cable 20 Inner cable 21 Shaft 22 Strand wire 30 Outer casing 31 Liner 33 Shield wire 35 Coating layer 41 Circumscribed circle 50 Control cable 60 Inner cable 61 Strand core wire 63 Strand side wire 65 Second strand side wire 67A Third strand side wire 67B First strand side wire 69 Coating layer 70 Outer casing 71 Liner 73 Shield wire 75 Coating layer 91 Constant temperature bath 93 Push-pull force measuring instrument 95 Spring

Claims

1. A grease composition comprising a base oil, a modified silicone, a thickener, and a solid lubricant, wherein the solid lubricant comprises two or more melamine cyanurates with different volume average particle sizes.

2. The grease composition according to claim 1, wherein the solid lubricant comprises melamine cyanurate (MCA1) having a volume-average particle diameter of 6.0 μm or less and melamine cyanurate (MCA2) having a volume-average particle diameter of 10 to 30 μm, and the mass content ratio of MCA1 to MCA2 in the solid lubricant is 60:40 to 99.9:0.

1.

3. The grease composition according to claim 1 or 2, wherein the total content of melamine cyanurate in the grease composition is 1 to 30% by mass.

4. The grease composition according to any one of claims 1 to 3, wherein the base oil contains a silicone base oil, and the content of the silicone base oil in the grease composition is 45% by mass or more and 70% by mass or less.

5. The modified silicone is one or more modified silicones selected from the group consisting of compounds represented by the following general formulas (1), (2), or (3): [wherein, R 1 and R 2 each independently represents -W 1 -COOH, or -W 1 -NH2; when there are plural Rs 3 each independently represents -W 1 -COOH, -W 1 -NH2, or -W 1 -NH-W 2 -NH2; R represents a linear or branched alkyl group having 1 to 30 carbon atoms; R 4 represents -W 1 -COOH; W 1 and W 2 each independently represents a linear or branched alkylene group having 1 to 30 carbon atoms when there are plural Ws; m and n each independently represent a repetition number of 1 or more], the grease composition according to any one of claims 1 to 4.

6. The grease composition according to any one of claims 1 to 5, wherein the content of the modified silicone in the grease composition is 0.01 to 10% by mass.

7. A control cable in which the grease composition according to any one of claims 1 to 6 is applied to the outer surface of the inner cable.

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