Grease composition

Abstract

To provide a lubricating grease used for lubricating mechanical elements having a reciprocating sliding ball interposed therebetween, where anti-flaking performance is maintained even under a high load.SOLUTION: A grease composition comprises a base oil (a), a diurea compound (b), an amide compound (c), and a thiophosphorous compound or thiophosphoric acid ester compound (d), where the diurea compound (b) is represented by Formula 1 in the figure, where R1 and R3 each represent an acyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and R2 represents a diphenylmethane group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a grease composition.

Background Art

[0002] Generally, as mechanical elements with reciprocating sliding balls intervening, there are linear guides, ball screws, constant velocity joints, etc., and their usage environments are diverse. Also, in these mechanical elements, rolling and sliding can occur simultaneously, and the lubrication environment is severe. Under such conditions, contact between the surfaces of rolling members can easily occur, and when the contact is significant, wear and seizure occur.

[0003] As a method of preventing such wear and seizure and protecting mechanical elements, it is common to add extreme pressure agents to lubricants such as lubricating oils and greases. Known extreme pressure agents include sulfur-based extreme pressure agents, phosphorus-based extreme pressure agents, sulfur-phosphorus-based organic compounds, molybdenum compounds, etc. Among these, organic extreme pressure agents exhibit excellent extreme pressure performance, so they have become the mainstream of extreme pressure agents and are widely used in various lubricating oil compositions.

[0004] For example, Patent Document 1 discloses a grease composition for a sliding constant velocity joint characterized by containing a urea thickener, molybdenum dialkyldithiocarbamate sulfide, molybdenum disulfide, a sulfur-phosphorus-based extreme pressure agent such as zinc dithiophosphate and thiophosphate, and a fatty acid amide, which improves the lubricity of parts that are prone to wear and prone to problems such as abnormal vibration. According to the patent, in a constant velocity joint, the generation of induced thrust force has problems such as a decrease in the durability of the constant velocity joint, abnormal vibration of the vehicle, and deterioration of the riding comfort, but by using this patent, a technique for reducing wear, suppressing vibration, and improving durability is disclosed.

[0005] Patent Document 2 discloses a grease composition characterized by containing a urea thickener and an organic sulfonate, which can prevent peeling due to metal fatigue caused by thinning of the oil film without relying on thickening of the oil film and extend the peeling life due to metal fatigue.

[0006] Patent Document 3 discloses a grease composition for rolling bearings characterized by containing a urea thickener, benzotriazole and / or its derivative, which can prevent peeling due to metal fatigue caused by thinning of the oil film without relying on thickening of the oil film and can extend the peeling life.

[0007] Patent Document 4 discloses a grease composition for bearings characterized by containing a urea thickener, an alkyl phosphorothioate compound and an aliphatic amine compound, which discloses a technique for improving fretting resistance.

[0008] Patent Document 5 discloses a grease composition characterized by containing a urea thickener, molybdenum dithiocarbamate, zinc dithiocarbamate and zinc sulfonate, which can prevent metal contact even in lubrication under high speed and high surface pressure and maintain and form an additive film that reduces friction.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, although the lubricants and grease compositions of Patent Documents 1 to 5 exhibit good wear resistance and film-forming ability under certain conditions and specific mechanical elements, they have not reached the stage of providing a composition that can stably maintain overall balanced wear resistance performance and film-forming ability even in reciprocating sliding under various high loads. In particular, the effect on flaking generated by reciprocating sliding under various high loads has not been studied and may be insufficient.

[0011] The present invention has been made in view of such circumstances, and its object is to form a strong additive film in order to maintain and improve the life of mechanical parts even in a situation where metal contact occurs due to insufficient generation of an oil film and excessive friction and wear are likely to occur when rolling suddenly stops at the time of reversal during reciprocating sliding. Further, these are formed such that the formed film is stably maintained even after repeated operations, and gives stable lubricating characteristics. That is, the present invention lies in providing a grease composition that can be used for lubricating mechanical elements with reciprocating sliding balls that maintain anti-flaking performance even under high loads.

Means for Solving the Problems

[0012] As a result of intensive research to achieve the above object, a formulation technique has been found in which an amide compound, a thiophosphorous acid compound or a thiophosphate compound, and a specific diurea compound are blended, which can be used for mechanical elements with reciprocating sliding balls and improves anti-flaking performance, and the present invention has been completed.

[0013] That is, the present invention is as follows. The present invention (1) is a grease composition containing base oil (a), diurea compound (b), amide compound (c), thiophosphate compound (d), and amine compound (f) represented by the following formula 2, wherein the diurea compound (b) contains a compound represented by the following formula 1, which is a grease composition. (Formula 1) TIFF0007700295000001.tif14170(However, R1 and R3 represent acyclic aliphatic hydrocarbon groups having 8 to 20 carbon atoms, and R2 represents a diphenylmethane group) (Formula 2) TIFF0007700295000002.tif24145(However, R4 represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms, and R5 represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms) The present invention (2) is The diurea compound (b) contains a diurea compound (b) in which R1 and R3 in the formula 1 are either acyclic aliphatic hydrocarbon groups having 8 to 12 carbon atoms or acyclic aliphatic hydrocarbon groups having 14 to 20 carbon atoms, and is the grease composition of the invention (1). The present invention (3) is The grease composition of the invention (1) or (2), characterized by containing a saturated or unsaturated fatty acid having 4 to 18 carbon atoms or a metal salt (e) thereof The present invention (4) is The amide compound (c) contains an amide compound (c) represented by the following formula 3 or formula 4, and is any of the grease compositions of the inventions (1) to (3). (Formula 3) TIFF0007700295000003.tif16168(Formula 4) TIFF0007700295000004.tif15170(However, R6 represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms, and R7 represents a methylene group or an ethylene group) The present invention (5) is The thiophosphate ester compound contains a thiophosphate ester compound represented by the following formula 6, and is any of the grease compositions of the inventions (1) to (4). (Formula 6) TIFF0007700295000005.tif31132(However, R9 represents a saturated or unsaturated hydrocarbon group having 8 to 18 carbon atoms or an aryl group having 6 to 18 carbon atoms.)

Advantages of the Invention

[0014] According to the present invention, in a mechanical element with reciprocating balls interposed, it is possible to provide a grease composition that can be used for lubricating a mechanical element with reciprocating balls that maintains anti-flaking performance even under high loads.

Brief Description of the Drawings

[0015]

Figure 1

Modes for Carrying Out the Invention

[0016] In the present application, the “hydrocarbon group” refers to an atomic group obtained by removing a part of hydrogen atoms from a hydrocarbon.

[0017] In the present application, when only a compound name is shown, it shall include all isomers thereof.

[0018] In the present application, the amine compound that forms the diurea compound described later is referred to as a raw material amine compound. The raw material amine compound and the amine compound (f) may be the same or different. When the blending amount of the amine compound (f) is described in this specification, the raw material amine compound is not included.

[0019] The grease composition of the present invention contains a base oil (a), a diurea compound (b), an amide compound (c), and a thiophosphorous acid compound or a thiophosphate compound (d).

[0020] The diurea compound (b) according to the present invention includes a compound represented by the following formula 1. (Formula 1) TIFF0007700295000006.tif14170(However, R1 and R3 represent an acyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and R2 represents a diphenylmethane group)

[0021] The diurea compound (b) according to the present invention is generally produced by reacting an isocyanate with a primary amine (raw amine compound). It has become clear that the form of the thickener fiber exhibited by the diurea thickener varies depending on the combination of the isocyanate and the primary amine (raw amine compound), and the flow properties of the grease composition change significantly.

[0022] Among them, it was revealed that the aliphatic urea grease using the diurea compound (b) of formula 1 as a thickener has different flow characteristics from urea grease made of alicyclic amine or aromatic amine, and urea grease made of a mixture of aliphatic amine and alicyclic amine and / or aromatic amine. It was also revealed that the grease using the diurea compound (b) of formula 1 as a thickener tends to have excellent intervening properties at the lubrication interface, and therefore plays an important role in protecting machine elements. Furthermore, the grease using the diurea compound (b) of formula 1 as a thickener has good solubility in the base oil and intervenes at the lubrication interface together with the base oil, and is considered to interact with the good flow behavior due to the different fiber morphology described above, thereby providing effective lubrication. It was also revealed that this effect is prominent in aliphatic urea grease containing unsaturated aliphatic amine.

[0023] Furthermore, in the grease composition of the present invention containing the diurea compound (b), the amide compound (c), the thiophosphorous compound or the thiophosphate ester compound (d), a remarkable effect is shown in improving the flaking resistance, as described below, and it has been revealed that by blending a fatty acid, a fatty acid salt, or an amine compound (f) other than the raw amine compound for forming the diurea compound (b), an even greater effect is shown in improving the flaking resistance of a machine element having a reciprocatingly sliding ball therebetween.

[0024] This effect is due to the improved supply of the grease composition to the lubricating interface due to the excellent fluidity characteristics exhibited by the aliphatic diurea thickener in the fluid lubrication region where the reciprocating sliding speed is high, resulting in a thickening of the lubricating film. Furthermore, in addition to the lubricating film formed by the diurea compound (b), the synergistic thickening effect with the urea grease due to the fluidity characteristics exhibited by the amide compound (c), fatty acid or its fatty acid salt (e) and adsorption onto the metal surface further improves the wear resistance. Also, in the mixed lubrication region and boundary lubrication region where the oil film near the end point of reciprocating motion approaches zero, the thiophosphorous acid compound or thiophosphate ester compound (d) and amine compound (f) contained in the grease composition, which was abundantly supplied to the lubricating interface due to the excellent fluidity characteristics of the grease, adsorb onto the metal surface and form a strong film by tribochemical reaction at the interface, thereby exhibiting good anti-flaking performance.

[0025] <<<Grease composition>>> <<Components of the grease composition>> <Base oil (a)> The grease composition of the present invention contains a base oil (a). The base oil (a) according to the present invention is not particularly limited as long as it does not inhibit the effects of the present invention. As the base oil (a), for example, mineral oil, synthetic oil, animal and vegetable oil, and mixed oils thereof can be appropriately used. Specific examples include those in Groups 1 to 5 of the API (American Petroleum Institute) base oil category. Here, the API base oil category is a broad classification of base oil materials defined by the American Petroleum Institute for creating guidelines for lubricating oil base oils.

[0026] The mineral oil according to the present invention is not particularly limited, but as a preferred example, paraffinic or naphthenic mineral oil obtained by subjecting a lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil to one or more purification means such as solvent dewaxing, solvent extraction, hydrocracking, solvent deasphalting, catalytic deasphalting, hydrorefining, sulfuric acid washing, and clay treatment, etc., appropriately combined, can be mentioned. These can be used alone or in combination of a plurality.

[0027] The synthetic oil according to the present invention is not particularly limited, but poly-α-olefin (PAO) or hydrocarbon-based synthetic oil (oligomer) can be mentioned as preferred examples. PAO is a homopolymer or copolymer of α-olefin. For example, as α-olefin, it is a compound having a C-C double bond at the terminal, and examples include butene, butadiene, hexene, cyclohexene, methylcyclohexene, octene, nonene, decene, dodecene, tetradecene, hexadecene, octadecene, eicosene, etc. Examples of the hydrocarbon-based synthetic oil (oligomer) can include homopolymers or copolymers of ethylene, propylene, or isobutene. These can be used alone or in combination of a plurality. Also, as long as these compounds have a C-C double bond at the terminal, they may have any structure of possible isomeric structures, and may have a branched structure or a linear structure. Two or more of these structural isomers and positional isomers of double bonds can also be used in combination. Among these olefins, those having 5 or less carbon atoms have a low flash point, and those having 31 or more carbon atoms have a high viscosity and low practicality, so the use of linear olefins having 6 to 30 carbon atoms is more preferred.

[0028] In the present invention, GTL (gas to liquid) synthesized by the Fischer-Tropsch method of natural gas liquefaction technology can be used as the base oil (a). Compared with mineral oil base oil refined from crude oil, GTL has extremely low sulfur content and aromatic content, and a very high paraffin composition ratio, so it has excellent oxidation stability and very small evaporation loss, and thus can be suitably used as the base oil (a) of the present invention.

[0029] <Diurea compound (b)> The grease composition of the present invention contains a diurea compound (b) represented by the following formula 1. (Formula 1) TIFF0007700295000007.tif14170Here, R1 and R3 in Formula 1 represent an acyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and R2 represents a diphenylmethane group.

[0030] R1 and R3 may be any acyclic aliphatic hydrocarbon group, and may be a linear or branched, saturated or unsaturated aliphatic hydrocarbon group. R1 and R3 may have the same structure or different structures.

[0031] The diurea compound (b) according to the present invention can be obtained by the reaction of the following formula 7. (Formula 7) TIFF0007700295000008.tif39170

[0032] R1 and R3 are each preferably an acyclic aliphatic hydrocarbon group having 8 to 12 carbon atoms or an acyclic aliphatic hydrocarbon group having 14 to 20 carbon atoms, and it is more preferable that one of R1 and R3 is an acyclic aliphatic hydrocarbon group having 8 to 12 carbon atoms and the other is an acyclic aliphatic hydrocarbon group having 14 to 20 carbon atoms. When R1 and R3 have such a structure, a grease composition having more excellent wear resistance and anti-flaking properties can be obtained.

[0033] The diurea compound (b) according to the present invention can be used alone or in combination of a plurality.

[0034] <Amide compound (c)> The grease composition of the present invention contains an amide compound (c). The amide compound (c) according to the present invention is not particularly limited as long as it does not inhibit the effects of the present invention. As the amide compound (c) according to the present invention, for example, an aliphatic amide compound represented by the following formula 3 or an aliphatic bisamide compound represented by the following formula 4 is preferably used. When the amide compound (c) has such a structure, a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained. (Formula 3) TIFF0007700295000009.tif16168(Formula 4) TIFF0007700295000010.tif15170In the formula, R6 represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms, and R7 represents a methylene group or an ethylene group.

[0035] Specific examples of such an aliphatic amide compound or aliphatic bisamide compound include palmitic acid amide, palmitoleic acid amide, margaric acid amide, stearic acid amide, oleic acid amide, vaccenic acid amide, linoleic acid amide, linolenic acid amide, elaeostearic acid amide, arachidic acid amide, eicosadienoic acid amide, mead acid amide, arachidonic acid amide, erucic acid amide, behenic acid amide, methylene bispalmitic acid amide, methylene bispalmitoleic acid amide, methylene bismargaric acid amide, methylene bistearic acid amide, methylene bisoleic acid amide, methylene bisvaccenic acid amide, methylene bislinoleic acid amide, methylene bislinolenic acid amide, methylene biselaeostearic acid amide, ethylene bispalmitic acid amide, ethylene bispalmitoleic acid amide, ethylene bismargaric acid amide, ethylene bistearic acid amide, ethylene bisoleic acid amide, ethylene bisvaccenic acid amide, ethylene bislinoleic acid amide, ethylene bislinolenic acid amide, ethylene biselaeostearic acid amide. These can be used alone or in combination of two or more.

[0036] The grease composition of the present invention contains a thiophosphorous acid compound or a thiophosphate compound (d). The thiophosphorous acid compound or the thiophosphate compound (d) according to the present invention is not limited as long as it does not inhibit the effects of the present invention. Further, a thiophosphorous acid compound and a thiophosphate compound can be used in combination.

[0037] As the thiophosphorous acid compound or the thiophosphate compound according to the present invention, for example, a thiophosphorous acid compound represented by the following formula 5 or a thiophosphate compound represented by the following formula 6 is preferably used. When the thiophosphorous acid compound or the thiophosphate compound (d) has such a structure, a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained. (Formula 5) TIFF0007700295000011.tif18168 Here, R8 represents a saturated or unsaturated hydrocarbon group having 8 to 18 carbon atoms or an aryl group having 6 to 18 carbon atoms. (Formula 6) TIFF0007700295000012.tif31132 Here, R9 represents a saturated or unsaturated hydrocarbon group having 8 to 18 carbon atoms or an aryl group having 6 to 18 carbon atoms.

[0038] Specific examples of such a thiophosphorous acid compound or thiophosphate compound (d) include alkylthiophosphorous acids such as trilauryltrithiophosphite; aromatic esters of thiophosphoric acid such as triphenylphosphorothioate; and the like. Among these, when an alkylthiophosphorous acid is used, a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained. These can be used alone or in combination of two or more.

[0039] <Other Additives> The grease composition of the present invention can further contain the following components as optional components. By containing a fatty acid or its metal salt (e) and an amine compound (f), the grease composition of the present invention can obtain more excellent wear resistance and anti-flaking properties. When it contains a fatty acid or its metal salt (e) and an amine compound (f), even more excellent wear resistance and anti-flaking properties can be obtained.

[0040] (Fatty acid or its metal salt (e)) The grease composition of the present invention can contain a fatty acid or its metal salt (e). The fatty acid or its metal salt (e) according to the present invention is not limited as long as it does not inhibit the effects of the present invention. As the fatty acid or metal salt according to the present invention, saturated or unsaturated fatty acids having 4 to 18 carbon atoms or their metal salts are preferably used. When the grease composition of the present invention contains such a fatty acid or its metal (e) salt, a grease composition having even more excellent wear resistance and anti-flaking properties can be obtained.

[0041] Specific examples of such fatty acids include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, linoleic acid, linolenic acid, pinolenic acid, eleostearic acid, stearidonic acid, bosseopentaenoic acid, etc. These can be used alone or in combination of a plurality. Among these, unsaturated fatty acids are more preferable than saturated fatty acids in that they are more likely to adsorb on the metal surface, and thus a grease composition having more excellent wear resistance and anti-flaking properties can be obtained. Also, as the number of carbon atoms, the larger the number of carbon atoms, the more preferable it is. An example of such a fatty acid is oleic acid.

[0042] The metal elements that form salts with these fatty acids are not limited as long as the effects of the present invention are not inhibited. Specific metal elements include, for example, alkali metals such as lithium, sodium, potassium, rubidium, and cesium; beryllium; magnesium; alkaline earth metals such as calcium, strontium, and barium; aluminum; zinc; and the like. These can be used alone or in combination of a plurality. Among these, salts of calcium and aluminum are more preferably used in that a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained.

[0043] (Amine compound (f)) The grease composition of the present invention can contain an amine compound (f). The amine compound (f) according to the present invention is not limited as long as the effects of the present invention are not inhibited. As the amine compound (f) according to the present invention, an amine compound represented by the following formula 2 is preferably used. When the grease composition of the present invention contains such an amine compound, a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained. (Formula 2) TIFF0007700295000013.tif24145Here, R4 represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms, and R5 represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms.

[0044] Specific examples of such amine compound (f) include, for example, N-coconut alkyl-1,2-ethylenediamine, N-tallow alkyl-1,2-ethylenediamine, N-hardened tallow alkyl-1,2-ethylenediamine, N-coconut alkyl-1,3-propanediamine, N-tallow alkyl-1,3-propanediamine, N-hardened tallow alkyl-1,3-propanediamine, N-coconut alkyl-1,3-propylenediamine, N-tallow alkyl-1,3-propylenediamine, N-hardened tallow alkyl-1,3-propylenediamine, N-coconut alkyl-1,4-butanediamine, N-tallow alkyl-1,4-butanediamine, N-hardened tallow alkyl-1,4-butanediamine and the like. These can be used alone or in combination of two or more. Among these, N-tallow alkyl-1,3-propanediamine is more preferable in that a grease composition having more excellent abrasion resistance and anti-flaking property can be obtained.

[0045] (Others) The grease composition of the present invention can use a thickener other than the urea compound (other thickeners) together with the above thickener (urea). Examples of such other thickeners include tricalcium phosphate, alkali metal soap, alkali metal composite soap, alkaline earth metal soap, alkaline earth metal composite soap, alkali metal sulfonate, alkaline earth metal sulfonate, other metal soaps, terephthalamate metal salts, monourea, polyurea other than triurea monourethane or diurea or tetraurea, or clays, silica such as silica aerogel (silicon oxide), fluororesins such as polytetrafluoroethylene and the like, and one or more of these can be used in combination. In addition, any substance that can impart a thickening effect to the liquid substance can be used. When using the above-described fatty acid or its metal salt (e), the fatty acid or its metal salt (e) can be further used repeatedly as a thickener. When the fatty acid or its metal salt (e) is repeatedly used as a thickener, it can be blended separately from the blending amount of the fatty acid or its metal salt (e).

[0046] Unless it inhibits the present invention, the grease composition of the present invention may further contain an antioxidant, a rust inhibitor, an oiliness agent, an extreme pressure agent, an antiwear agent, a solid lubricant, a metal deactivator, a polymer, a non-metallic detergent, a coloring agent, a water repellent, etc. These can be used alone or in combination of two or more.

[0047] Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-p-cresol, p,p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, phenothiazine, etc.

[0048] Examples of the rust inhibitor include paraffin oxide, metal carboxylate, metal sulfonate, carboxylic acid ester, sulfonic acid ester, salicylic acid ester, succinic acid ester, sorbitan ester, and various amine salts.

[0049] Examples of the oiliness agent, extreme pressure agent, and antiwear agent include zinc dialkyldithiophosphate, zinc diallyldithiophosphate, zinc dialkyldithiocarbamate, zinc diallyldithiocarbamate, molybdenum dialkyldithiophosphate, molybdenum diallyldithiophosphate, molybdenum dialkyldithiocarbamate, molybdenum diallyldithiocarbamate, organic molybdenum complex, sulfurized olefin, triphenyl phosphite, triphenyl phosphorothionate, tricresyl phosphite, other phosphate esters, sulfurized oils and fats, etc.

[0050] Examples of the solid lubricant include molybdenum disulfide, graphite, boron nitride, melamine cyanurate, PTFE (polytetrafluoroethylene), tungsten disulfide, graphite fluoride, etc. Examples of the metal deactivator include N,N'-disalicylidene-1,2-diaminopropane, benzotriazole, benzimidazole, benzothiazole, thiadiazole, etc. Examples of the polymer include polybutene, polyisobutene, polyisobutylene, polyisoprene, polymethacrylate, etc.

[0051] Examples of the non-metallic detergent include succinimide, etc.

[0052] <<Method for Producing Grease Composition>> Next, the method for producing the grease composition according to this embodiment is not particularly limited, and each raw material can be measured and mixed by a known method for production. Regarding the blending amount of any component, it can be appropriately blended at the above-mentioned blending amount if necessary.

[0053] The blending amount of the base oil (a) is preferably 70 to 98% by mass, more preferably 75 to 97% by mass, and still more preferably 80 to 95% by mass, with the total grease composition being 100% by mass.

[0054] The blending amount of the diurea compound (b) according to the present invention can be preferably 1 to 25% by mass, more preferably 3 to 20% by mass, and still more preferably 5 to 15% by mass, with the total grease composition being 100% by mass. When further adding a thickener other than the diurea compound (b), the total of the blending amount of the diurea compound (b) and the blending amount of the thickener other than the diurea compound (b) is preferably 2 to 50% by mass, more preferably 4 to 40% by mass, and still more preferably 6 to 30% by mass, with the total grease composition being 100% by mass. When the compounding quantity of the dithiourea compound (b) is within such a range, the grease composition has an appropriate hardness as grease, is difficult to flow out from the lubricated part, and has excellent invasiveness to the lubricating interface, so that the intended lubricating performance can be sufficiently exhibited.

[0055] The compounding quantity of the amide compound (c) according to the present invention can be preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and still more preferably 0.3 to 3% by mass, based on 100% by mass of the whole grease composition.

[0056] The compounding quantity of the thiophosphorous acid compound or thiophosphate compound (d) according to the present invention can be preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and still more preferably 0.3 to 3% by mass, based on 100% by mass of the whole grease composition.

[0057] The compounding quantity of the fatty acid or its metal salt (e) according to the present invention can be preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and still more preferably 0.3 to 3% by mass, based on 100% by mass of the whole grease composition.

[0058] The compounding quantity of the amine compound (f) according to the present invention can be preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and still more preferably 0.3 to 3% by mass, based on 100% by mass of the whole grease composition.

[0059] As the compounding quantity of other additives, about 0.1 to 20 parts by mass can be compounded in total of optional components, based on 100 parts by mass of the whole grease composition.

[0060] <<Physical properties of the grease composition>> <Consistency> The grease composition of the present invention has a penetration range of No. 2 to No. 0 (265 to 385), preferably a penetration range of No. 4 to No. 00 (175 to 430), more preferably a penetration range of No. 3 to No. 0 (220 to 385), and even more preferably a penetration range of No. 2 to No. 1 (265 to 340). The penetration represents the physical hardness of the grease. Here, the method for measuring the penetration can be determined by measuring the penetration in accordance with "Grease Penetration Test Method" of JIS K2220 7.

[0061] <Drop point> The grease composition of the present invention has no performance-related relevance at the drop point, but as an index indicating that the thickener structure of the urea grease has reached its original bond, those with a drop point of 180°C or higher or exceeding are preferred. The drop point refers to the temperature at which the viscous grease loses its thickener structure as the temperature rises. Here, the measurement of the drop point can be carried out in accordance with JIS K2220 8 "Grease Drop Point Test Method".

[0062] <<Uses of the grease composition>> The grease composition of the present invention can generally be used in machinery, bearings, gears, ball screws, etc. that are commonly used, and can also exhibit excellent performance even in a harsher environment for grease lubrication. For example, in automobiles, it can be suitably used for lubricating various parts such as around the engine of the water pump, cooling fan motor, starter, alternator, and various actuators, propeller shaft, constant velocity joint (CVJ), wheel bearing, and clutch in the power train, electric power steering (EPS), electric power window, braking device, ball joint, door hinge, handle part, expander of the brake, etc. Furthermore, it is also preferably used for various shafts and mating parts that may reciprocate and slide in construction machinery such as power shovels, bulldozers, and crane trucks, the steel industry, the paper industry, forestry machinery, agricultural machinery, chemical plants, power generation facilities, railway vehicles, etc. Other uses include screw joints of seamless pipes and bearings of outboard motors, etc., and it is also suitable for these uses.

Examples

[0063] Hereinafter, the present invention will be described in more detail with reference to Examples, Reference Examples, and Comparative Examples, but the present invention is not limited to these Examples at all.

[0064] <<Manufacture of Grease Composition>> <Raw Materials> The abbreviations for the raw material components used in the Examples, Reference Examples, and Comparative Examples are as follows. (Base Oil (a)) · Base Oil A: Mineral oil having a kinematic viscosity at 40°C of 99.05 mm 2 / s and a kinematic viscosity at 100°C of 11.13 mm 2 / s · Base Oil B: Mineral oil having a kinematic viscosity at 40°C of 480.2 mm 2 / s and a kinematic viscosity at 100°C of 31.56 mm 2 / s · Base Oil C: Highly refined oil having a kinematic viscosity at 40°C of 43.88 mm 2 / s, a kinematic viscosity at 100°C of 7.774 mm 2 / s, a viscosity index of 146, %CA of 1 or less, %CN of 11.9, and %CP of 85 or more · Base Oil D: Polyα-olefin oil having a kinematic viscosity at 40°C of 396.5.3 mm 2 / s and a kinematic viscosity at 100°C of 39.99 mm 2 / s · Base Oil E: Alkyl diphenyl ether oil having a kinematic viscosity at 40°C of 102.2 mm 2 / s and a kinematic viscosity at 100°C of 12.64 mm 2 / s (Diurea Compound (b)) The diurea compound (b) was prepared by reacting the following raw materials according to the production method described later. · Diurea Compound A: Diphenylmethane-4,4'-diisocyanate (MDI) Octylamine Oleylamine · Diurea Compound B: Diphenylmethane-4,4'-diisocyanate (MDI) Octylamine (Amide compound (c)) · Amide compound A: Oleic acid amide (Armoslips CP manufactured by Lion) (Thiophosphorous acid compound or thiophosphate ester compound (d)) · Thiophosphorous acid compound A: Trilauryl trithiophosphite (JPS-312 manufactured by Johoku Chemical Industry Co., Ltd.) · Thiophosphate ester compound A: Triphenyl phosphorothioate (Irgalube TPPT manufactured by BASF) (Fatty acid or its metal salt (e)) · Fatty acid A: Oleic acid (NAA-35 manufactured by NOF Corporation) · Fatty acid metal salt A: Calcium stearate (Calcium stearate GP manufactured by NOF Corporation) · Fatty acid metal salt B: Aluminum stearate (Aluminum stearate 300 manufactured by NOF Corporation) (Amine compound (f)) · Amine compound A: N-Tallow alkyl-1,3-propanediamine (Lipomine DA-T manufactured by Lion).

[0065] <Reference Example 1> The base oil and MDI were heated in a kettle to dissolve the contents, and then a raw material obtained by mixing and dissolving octylamine, oleylamine, and the base oil was added and reacted to synthesize diurea compound A. Further, the mixture was heated to 170 °C while stirring and the temperature was maintained for about 30 minutes to complete the reaction. Then, it was rapidly cooled, and during the cooling process, various additives in the blending ratios shown in Table 1 were added, stirred and mixed, cooled to 80 °C, and then treated with a homogenizer to obtain grease.

[0066] <Example 13, Reference Examples 2 to 12, 14 to 18, and Comparative Examples 1 to 5> A grease composition was prepared in the same manner as in Reference Example 1, except that the raw materials to be blended were those shown in Table 1. Note that diurea compound B was adjusted by changing the raw materials of diurea compound A to the above-mentioned raw materials.

[0067] <<Evaluation of Grease Composition>> In order to compare the properties and performance of each example, reference example, and comparative example, the following measurements and tests were conducted.

[0068] <Consistency> For the grease compositions of each example, reference example, and comparative example, in accordance with the "Grease Consistency Test Method" of JIS K2220 7, the mixed consistency and non-mixed consistency were measured. The results are shown in Table 1.

[0069] <Drop point> For the grease compositions of each example, reference example, and comparative example, in accordance with the "Grease Drop Point Test Method" of JIS K2220 8, the drop point was measured. The results are shown in Table 1.

[0070] <Bearing peeling wear test> For the grease compositions of each example, reference example, and comparative example, the wear resistance and flaking resistance were evaluated by a bearing peeling wear test. The results are shown in Table 1. The evaluation method is as follows. Also, Figure 1 is a diagram showing the outline of the bearing peeling wear test machine. The weight of a clean test rolling bearing (7205 type angular ball bearing) was measured in advance, and 3 g of the grease composition was packed into the bearing and mounted on a bearing peeling wear test device. Then, the nut of the oscillating shaft was fixed with a tightening torque of 600 kg·m, and a thrust load was applied with the tightening torque to the shaft. Next, a radial load of 1.0 ton per bearing was applied with a hydraulic piston. The motor was started, and the oscillating shaft was reciprocated at 1.7 Hz. After 20 hours of oscillating operation, the bearing was taken out from the device, washed with a solvent such as n-hexane, and the grease composition was sufficiently removed. The weight of the clean bearing after the test was measured, and the weight difference from the bearing before the test was calculated and used as the bearing wear amount. The amount of bearing wear after the test and the flaking occurrence area of the sliding surfaces of the inner and outer rings were measured, and the quality was evaluated. The pass / fail determination was based on the total flaking occurrence area, with less than 50 mm 2 being considered a pass and 50 mm or more being considered a fail. The flaking occurrence area was observed and specified with a digital microscope (VHX-6000 manufactured by Keyence) for the part where flaking occurred, and then the area was measured. (Test Conditions) Test bearing: No.7205 (angular ball bearing) Grease filling amount: 3.0 g Oscillation: 1.7 Hz Thrust load: 600 Kg·m Radial load: 1.0 ton Temperature: 25 °C Time: 20 hours

[0071] <Evaluation Results> According to the above test method, the consistency, dropping point, and bearing peeling wear test were carried out. The properties of each obtained grease are shown in Table 1. The consistency of the grease in the examples is from No. 0 to No. 2 consistency, and the consistency of the grease in the comparative examples is from No. 2 to No. 2.5 consistency. The dropping point is a value not inferior to that of urea grease at 240 °C or higher for both the greases in the examples and the comparative examples. In the most important bearing peeling wear test in the present invention, the results of all the greases according to the examples achieved wear resistance with a bearing wear amount of less than 150 mg, and the flaking occurrence area was less than 50 mm 2 and it was a pass judgment. On the other hand, the grease according to the comparative example had a large amount of wear of the bearing after the bearing peeling wear test, and the flaking occurrence area of the sliding surfaces of the inner ring and the outer ring respectively exceeded 50 mm 2 and it was a fail judgment.

[0072]

Table 1

Explanation of Symbols

[0073] 1 Motor 2 Rotating shaft 3 Crank arm (1) 4 Strain gauge 5 Crank bending part 6 Crank arm (2) 7 Fitting retaining nut 8 Key material 9 Conical mating part 10 Nut 11 Collar 12 Bearing retaining block 13 Test rolling bearing 14 Bearing unit 15 Load control device 16 Auxiliary rolling bearing 17 Rocking shaft

Claims

1. A grease composition comprising a base oil (a), a diurea compound (b), an amide compound (c), a thiophosphate ester compound (d), and an amine compound (f) represented by the following formula 2: The grease composition, wherein the diurea compound (b) contains a compound represented by the following formula 1: (Formula 1) (However, R １ and R ３ represents an acyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms; R ２ indicates a diphenylmethane group) (Formula 2) (However, R ４ represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms; R ５ represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms.

2. The diurea compound (b) is represented by R １ and R ３ is either an acyclic aliphatic hydrocarbon group having 8 to 12 carbon atoms, or an acyclic aliphatic hydrocarbon group having 14 to 20 carbon atoms.

3. 3. The grease composition according to claim 1, further comprising (e) a saturated or unsaturated fatty acid having 4 to 18 carbon atoms or a metal salt thereof.

4. The grease composition according to any one of claims 1 to 3, characterized in that the amide compound (c) comprises an amide compound (c) represented by the following formula 3 or 4: (Formula 3) (Formula 4) (However, R ６ represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms; R ７ represents a methylene group or an ethylene group)

5. The grease composition according to any one of claims 1 to 4, characterized in that the thiophosphate ester compound contains a thiophosphate ester compound represented by the following formula 6: (Formula 6) (However, R ９ represents a saturated or unsaturated hydrocarbon group having 8 to 18 carbon atoms, or an aryl group having 6 to 18 carbon atoms.

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