Grease composition

Abstract

To provide a grease composition having good wear resistance.SOLUTION: A grease composition comprises a base oil (A), a thickener (B), a molybdenum amine complex (C) represented by general formula (c-1), and zinc dialkyldithiophosphate (D1) or a sulfur phosphorus compound (D2). The content of the molybdenum amine complex (C) is 0.1 to 10 mass% relative to the total amount of the grease composition, and the total content of the zinc dialkyldithiophosphate (D1) and the sulfur phosphorus compound (D2) is 0.1 to 10 mass% relative to the total amount of the grease composition.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Grease is a lubricant obtained by dispersing a solid thickener having strong lipophilicity in a base oil to make it semi-solid. Grease is more likely to adhere to the lubricated part and less likely to flow out than lubricating oil. Therefore, by using grease, the mechanical structure of the lubrication system can be simplified. In addition, grease has less leakage than lubricating oil, can realize a clean environment, and can reduce the replenishment interval compared to lubricating oil. Grease is mainly used for lubricating mechanical elements such as rolling bearings, sliding bearings, ball screws, linear guides, and gears. Rolling bearings are widely used in the main shafts of machine tools, railway vehicle bodies, engine accessories such as alternators in automobiles, constant velocity joints, and wheels.

[0003] The characteristics required for a grease composition include lubricity, wear resistance, and the like. For example, Patent Document 1 discloses a grease composition containing a composite ester A, a base oil, and a thickener, wherein the composite ester A contains an ester obtained by at least condensing a polyhydric alcohol a1 having 3 or more valences, a polycarboxylic acid a2 having 5 or more carbon atoms, and a monohydric alcohol a3 having 6 or more carbon atoms. This grease composition is disclosed to be able to exhibit good lubricating performance and wear resistance at various temperatures and loads.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, higher levels of properties have been required for grease compositions, and in particular, grease compositions with high wear resistance have been demanded. In conventional grease compositions such as those shown in Patent Document 1, there is room for improvement from the viewpoint of wear resistance.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a grease composition having good wear resistance.

Means for Solving the Problems

[0007] The inventors conducted various studies on additives and found that by using a molybdenum amine complex represented by a specific structure in combination with zinc dialkyldithiophosphate or a sulfur-phosphorus compound and setting their contents within a specific range, the above problems can be solved, and the present invention has been completed. Specifically, the present invention employs the following configuration.

[0008] [1] A grease composition containing a base oil (A), a thickener (B), a molybdenum amine complex (C) represented by the following general formula (c-1), and zinc dialkyldithiophosphate (D1) or a sulfur-phosphorus compound (D2), wherein the content of the molybdenum amine complex (C) is 0.1 to 10% by mass based on the total amount of the grease composition, and the total content of the zinc dialkyldithiophosphate (D1) and the sulfur-phosphorus compound (D2) is 0.1 to 10% by mass based on the total amount of the grease composition.

[0009]

Chemical formula

Advantages of the Invention

[0010] According to the present invention, a grease composition having good abrasion resistance can be provided.

Embodiments for Carrying Out the Invention

[0011] (Grease Composition) The penetration of the grease composition of the present embodiment is preferably 190 to 240, more preferably 190 to 230, and even more preferably 200 to 220. When the penetration of the grease composition of the present embodiment is within the above preferred range, the abrasion resistance is further improved.

[0012] The grease composition of the present embodiment contains a base oil (A) (hereinafter also referred to as “component (A)”), a thickener (B) (hereinafter also referred to as “component (B)”), a molybdenum amine complex (C) represented by the following general formula (c-1) (hereinafter also referred to as “component (C)”), and zinc dialkyldithiophosphate (D1) (hereinafter also referred to as “component (D1)”) or a sulfur phosphorus compound (D2) (hereinafter also referred to as “component (D2)”).

[0013] <Base Oil (A)> (A) The kinematic viscosity of component (A) at 40 °C is 40 mm 2 / s or more, preferably 42 mm 2 / s or more, more preferably 44 mm2 It is more preferably / s or more. The preferable upper limit value of the kinematic viscosity of component (A) at 40°C is not particularly limited. For example, it is 2 preferably 100 mm 2 / s or less, more preferably 80 mm 2 / s or less, and even more preferably 60 mm

[0014] The kinematic viscosity at 40°C in this specification means the kinematic viscosity at 40°C measured in accordance with JIS K2283:2000.

[0015] Examples of component (A) of the grease composition of this embodiment include synthetic oil and mineral oil.

[0016] ≪Synthetic oil≫ Examples of synthetic oils include polyolefins such as poly-α-olefins, ester base oils such as diesters and polyol esters, polyalkylene glycols, alkylbenzenes, and alkylnaphthalenes. As component (A) of the grease composition of this embodiment, one synthetic oil may be used alone, or a plurality of synthetic oils may be mixed and used.

[0017] ≪Mineral oil≫ As the mineral oil, the distillate oil obtained by atmospheric distillation of crude oil can be used. Also, the distillate oil obtained by further vacuum distillation of this distillate oil, and the lubricating oil fraction purified by various purification processes can also be used. As the purification processes, hydrorefining, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc. can be appropriately combined. By combining these purification processes in an appropriate order and treating them, mineral oil can be obtained. Also, a mixture of a plurality of refined oils having different properties obtained by subjecting different crude oils or distillate oils to different combinations of purification processes may be used.

[0018] (Component (A) may consist of one type of mineral oil or may be a mixed base oil containing two or more types of mineral oils. It may also contain the synthetic oil described above.) (The content of component (A) is preferably 70 to 99% by mass, more preferably 80 to 99% by mass, based on the total amount of the grease composition.)

[0019] <Thickener (B)> (Examples of component (B) include simple metal soaps, metal complex soaps, urea compounds, and inorganic thickeners.)

[0020] ≪Simple metal soap≫ A simple metal soap is a simple metal soap obtained by saponifying a fatty acid or an oil and fat with a metal hydroxide.) As the fatty acid, a monovalent or divalent fatty acid is preferable.) As the fatty acid, a fatty acid having 6 to 20 carbon atoms is preferable, and a monovalent fatty acid having 12 to 20 carbon atoms or a divalent fatty acid having 6 to 14 carbon atoms is more preferable. In this specification, "6 to 20 carbon atoms" means having 6 or more and 20 or less carbon atoms.) The fatty acid may be a fatty acid derivative having a substituent such as a hydroxy group.)

[0021] Examples of the metal in the simple metal soap include alkali metals such as lithium and sodium, alkaline earth metals such as calcium, and amphoteric metals such as aluminum.)

[0022] ≪Metal complex soap≫ A metal complex soap is a metal soap obtained by saponifying carboxylic acids having a plurality of different molecular structures with a metal hydroxide and complexing them.) Specific examples of the metal complex soap include metal complex soaps obtained by reacting a metal hydroxide with a fatty acid and a dibasic acid or an aromatic carboxylic acid.) Examples of the metal in the metal complex soap include alkali metals such as lithium and sodium, alkaline earth metals such as calcium, and amphoteric metals such as aluminum. Among these metals, lithium and aluminum are preferred, and lithium is more preferred.

[0023] Examples of the fatty acid include the same ones as those in the single metal soap described above. Examples of the dibasic acid combined with the fatty acid in the metal complex soap include acetic acid, azelaic acid, sebacic acid, etc. Examples of the aromatic carboxylic acid combined with the fatty acid in the metal complex soap include benzoic acid, etc.

[0024] Among the above, as the metal complex soap, lithium complex soap obtained by reacting lithium hydroxide with a monobasic fatty acid having 6 to 20 carbon atoms containing one hydroxy group and a dibasic acid is preferred, lithium complex soap obtained by reacting lithium hydroxide with a monobasic fatty acid having 12 to 20 carbon atoms containing one hydroxy group and azelaic acid is more preferred, and lithium complex soap obtained by reacting lithium hydroxide with 12-hydroxystearic acid and azelaic acid is even more preferred.

[0025] ≪Urea compound≫ Examples of the urea compound include diurea compounds and polyurea compounds. The diurea compound is a compound obtained by reacting a diisocyanate with a monoamine, and is a compound having two urea groups (-NH-CO-NH-). In this specification, the polyurea compound is a compound obtained by reacting a diisocyanate with a monoamine or a diamine, and means a compound having three or more urea groups (-NH-CO-NH-).

[0026] ·Diisocyanate Diisocyanate is a compound in which two hydrogens of a hydrocarbon are substituted with isocyanate groups (-N=C=O). The hydrocarbon may be a cyclic hydrocarbon or a chain hydrocarbon. Further, the hydrocarbon may be an aromatic hydrocarbon or an aliphatic hydrocarbon. The number of carbon atoms of the hydrocarbon is preferably 4 to 20, more preferably 8 to 18.

[0027] Preferred specific examples of diisocyanate include phenylenediisocyanate, tolylene diisocyanate, biphenyl diisocyanate (diphenyl diisocyanate), diphenylmethane-4,4'-diisocyanate (MDI), octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc. Diisocyanate may be used alone or in combination of two or more.

[0028] · Monoamine Monoamine is a compound having one amino group in one molecule. Preferred monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine (stearylamine), oleylamine, aniline, p-toluidine, and cyclohexylamine, etc. Octadecylamine and cyclohexylamine are more preferred. Monoamine may be a cyclic amine or a chain amine. Further, monoamine may be an alicyclic amine, an aromatic amine, or an aliphatic amine. As monoamine, chain amines are preferred. The number of carbon atoms of the chain amine is preferably 4 to 20, more preferably 6 to 16, and still more preferably 6 to 10.

[0029] · Diamine Diamine is a compound having two amino groups in one molecule. As the diamine, ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylylenediamine, diaminodiphenylmethane, etc. are preferable. The diamine may be a cyclic amine or a chain amine. Further, the diamine may be an alicyclic amine, an aromatic amine, or an aliphatic amine. The number of carbon atoms of the diamine is preferably 4 to 20, more preferably 8 to 18.

[0030] Among the above, a diurea compound is preferable as the urea compound. The diurea compound is preferably a compound obtained by the reaction of a diisocyanate having an aromatic hydrocarbon group and a monoamine. As the diisocyanate having an aromatic hydrocarbon group, diphenylmethane-4,4'-diisocyanate (MDI) is preferable. From the viewpoint of reducing the friction coefficient at the contact portion, an aliphatic amine is preferable as the monoamine. An aliphatic amine having 6 to 18 carbon atoms is more preferable, and octadecylamine and cyclohexylamine are even more preferable.

[0031] ≪Inorganic thickener≫ Specific examples of the inorganic thickener include bentonite and silica gel.

[0032] Among the above, a urea compound is preferable as the component (B), and a diurea compound is more preferable.

[0033] The component (B) may be used alone or in combination of two or more. The content of the component (B) is preferably 1 to 20% by mass, more preferably 5 to 20% by mass, and even more preferably 8 to 16% by mass with respect to the total amount of the grease composition.

[0034] <Molybdenum amine complex (C)> (C) component is a compound represented by the following general formula (c-1).

[0035] [Chemical formula] [In the formula, X, Y, and Z are each independently an integer of 3 or less, and Rc 1 and Rc 2 are each independently an alkyl group or an aryl group.]

[0036] Rc 1 and Rc 2 Examples of the alkyl group in Rc Rc 1 and Rc 2 include linear or branched alkyl groups having 1 to 20 carbon atoms.

[0037] (C) component may be used alone or in combination of two or more. The content of (C) component is 0.1 to 10% by mass, preferably 0.1 to 8% by mass, more preferably 0.5 to 5% by mass, and even more preferably 0.5 to 3% by mass based on the total amount of the grease composition.

[0038] [Zinc dialkyldithiophosphate (D1)] Specific examples of (D1) component include compounds represented by the following general formula (d1-1).

[0039] [Chemical formula] [In the formula, R 21 , R 22 , R 23 , and R 24 are each independently an alkyl group having 1 to 24 carbon atoms.]

[0040] R 21 , R 22 , R 23 , and R 24It may be a linear alkyl group or a branched alkyl group. R 21 、R 22 、R 23 、and R 24 are preferably the same alkyl group. The number of carbon atoms of the alkyl group is from 1 to 24, preferably 2 or more, more preferably 3 or more, preferably 12 or less, more preferably 8 or less.

[0041] The method for producing the compound represented by the general formula (d1-1) is not particularly limited. For example, it can be obtained by reacting an alcohol having an alkyl group corresponding to R 21 、R 22 、R 23 、and R 24 with phosphorus pentasulfide to synthesize dithiophosphoric acid and neutralizing it with zinc oxide.

[0042] <Sulfur-phosphorus compound (D2)> Specific examples of the (D2) component include compounds represented by the following general formula (d2-1).

[0043] [Chemical formula] [In the formula, R 1 and R 2 are each independently a monovalent hydrocarbon group, R 4 is a hydrogen atom or a monovalent hydrocarbon group, and R 5 and R 6 are each independently a hydrogen atom or an alkyl group.]

[0044] R 1 and R 2 The number of carbon atoms of the monovalent hydrocarbon group in is each independently 1 or more, 2 or more, or 3 or more, and may be 10 or less, 9 or less, or 8 or less. The total number of carbon atoms in the monovalent hydrocarbon group represented by R 1 and R 2 may be 2 or more, 3 or more, or 4 or more, and may be 20 or less, 19 or less, or 18 or less. Examples of the monovalent hydrocarbon group include an alkyl group and an aryl group.

[0045] R 4 Examples of the monovalent hydrocarbon group in R 4 The number of carbon atoms in the monovalent hydrocarbon group represented by R

[0046] R 5 and R 6 each independently represent a hydrogen atom or an alkyl group. The alkyl group may be either linear or branched, and is preferably linear. The number of carbon atoms of the alkyl group may be, for example, 1 to 4, 1 to 3, or 1 to 2. R 5 and R 6 At least one of R R 5 and R 6 is preferably a hydrogen atom.

[0047] Specific examples of the compound represented by the general formula (d2-1) include 3-(diisobutoxy-thiophosphorylsulfanyl)-2-methyl-propionic acid, ethyl-3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate, 3-(O,O-diisopropyl-dithiophosphoryl)-propionic acid, 3-(O,O-diisopropyl-dithiophosphoryl)-2-methyl-propionic acid, 3-(O,O-diisobutyl-dithiophosphoryl)-propionic acid, 3-(O,O-diisobutyl-dithiophosphoryl)-2-methyl-propionic acid, and alkyl esters such as ethyl esters of these compounds.

[0048] (Component (D1) may be used alone or in combination of two or more. (Component (D2) may be used alone or in combination of two or more. The grease composition of this embodiment may contain only one of the components (D1) and (D2), or may contain both of them.

[0049] The total content of the components (D1) and (D2) is 0.1 to 10% by mass, preferably 0.1 to 8% by mass, more preferably 0.1 to 5% by mass, and still more preferably 0.1 to 3% by mass based on the total amount of the grease composition.

[0050] <Optional component> The grease composition of this embodiment may contain optional components other than the above-described components (A), (B), (C), (D1), and (D2). Examples of the optional components include antioxidants, rust preventives, corrosion inhibitors, defoamers, metal detergents, antiwear agents or extreme pressure agents, viscosity index improvers, pour point depressants, mist preventives, and demulsifiers. The grease composition of this embodiment preferably further contains an antioxidant and a rust preventive in addition to the above-described components (A), (B), (C), (D1), and (D2).

[0051] Examples of the antioxidant include phenolic compounds such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; and amine compounds such as diphenylamine, dialkyldiphenylamine, phenyl-α-naphthylamine, and p-alkylphenyl-α-naphthylamine. When the grease composition contains an antioxidant, its content is, for example, 0.5 to 10% by mass based on the total amount of the grease composition. The antioxidant may be used alone or in combination of two or more antioxidants.

[0052] Examples of the rust preventive include amines, neutral or overbased petroleum-based or synthetic oil-based metal sulfonates (specifically, calcium sulfonate, etc.), metal carboxylates, esters (specifically, sorbitan fatty acid esters, etc.), phosphoric acid, phosphates, and the like. When the grease composition contains a rust preventive, its content is, for example, 0.005% by mass or more and 5% by mass or less based on the total amount of the grease composition. The rust preventive may be used alone or in combination of two or more rust preventives.

[0053] Examples of the corrosion inhibitor include known corrosion inhibitors such as benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, and imidazole-based compounds. When the grease composition contains a corrosion inhibitor, its content is, for example, 0.01 to 10% by mass based on the total amount of the grease composition. The corrosion inhibitor may be used alone or in combination of two or more corrosion inhibitors.

[0054] Examples of the defoaming agent include silicone-based defoaming agents.

[0055] Examples of the antiwear agent or extreme pressure agent include sulfur-containing compounds such as molybdenum dialkyldithiocarbamate, dihydrocarbyl polysulfide, sulfurized ester, thiazole compound, and thiadiazole compound; phosphorus-based extreme pressure agents such as phosphate ester, acidic phosphate ester, amine salt of acidic phosphate ester, and phosphite ester. When the grease composition contains an antiwear agent or extreme pressure agent, its content is, for example, 0.1% by mass or more and 10% by mass or less based on the total amount of the grease composition. The antiwear agent or extreme pressure agent may be used alone or in combination of two or more antiwear agents or extreme pressure agents.

[0056] Examples of the viscosity index improver include non-dispersed or dispersed poly(meth)acrylate-based viscosity index improvers, non-dispersed or dispersed olefin-(meth)acrylate copolymer-based viscosity index improvers, styrene-maleic anhydride ester copolymer-based viscosity index improvers, and mixtures thereof.

Examples

[0057] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples.

[0058] <Blending of grease composition> The grease compositions of Examples 1 to 3 and the grease compositions of Comparative Examples 1 to 5 were prepared by blending each component at the blending ratios shown in Tables 1 and 2. In Tables 1 and 2, the numerical values of each component represent the content ratio (mass%) of each component with respect to the total amount of the grease composition.

[0059] (1) Component (A) A-1: Poly-α-olefin (kinematic viscosity at 40°C = 46 mm 2 / s) The kinematic viscosity at 40°C measured in accordance with JIS K2283:2000 for the mixture of each of the above (A) components used in the grease compositions of Examples 1 to 3 and the grease compositions of Comparative Examples 1 to 5 is also shown in Tables 1 and 2.

[0060] (2) Component (B) B-1: Diurea compound (diurea compound obtained by the reaction of MDI with cyclohexylamine and octadecylamine (cyclohexylamine:octadecylamine = 50:50))

[0061] (3) Component (C) C-1: Mo amine complex

[0062] (4) Component (D) D-1: Zinc dialkyldithiophosphate D-2: 3-(Diisobutoxythiophosphorylsulfanyl)-2-methylpropionic acid

[0063] (5) Other additives X-1: Dialkyldiphenylamine X-2: Triaaryl phosphate X-3: Ca sulfonate X-4: Sorbitan ester

[0064] [Measurement of consistency] The consistency of the grease compositions of each example measured in accordance with JIS K2220:2013 is shown in Tables 1 and 2.

[0065] [Evaluation of wear characteristics] The friction coefficient was evaluated by an SRV test. Specifically, the test was conducted for 30 minutes under the conditions of a disk temperature of 150°C, a load of 50 N, an amplitude of 1 mm, and a frequency of 50 Hz, and the average friction coefficient was measured. The results are shown in Tables 1 and 2.

[0066] [Table 1]

[0067] [Table 2]

[0068] As shown in Tables 1 and 2, it was confirmed that the grease compositions of the examples had better wear resistance than the grease compositions of the comparative examples.

Claims

Claim 1 A grease composition containing a base oil (A), a thickener (B), a molybdenum amine complex (C) represented by the following general formula (c-1), and zinc dialkyldithiophosphate (D1) or a sulfur-phosphorus compound (D2), wherein the content of the molybdenum amine complex (C) is 0.1 to 10% by mass based on the total amount of the grease composition, and the total content of the zinc dialkyldithiophosphate (D1) and the sulfur-phosphorus compound (D2) is 0.1 to 10% by mass based on the total amount of the grease composition. 【Chemical 1】 [wherein, X, Y, and Z are each independently an integer of 3 or less, and Rc １ and Rc ２ are each independently an alkyl group or an aryl group.] Claim 2 The grease composition according to claim 1, wherein the thickener (B) is a diurea compound obtained by the reaction of a diisocyanate and a monoamine. Claim 3 The base oil (A) has a kinematic viscosity at 40 °C of 40 mm ２ / s or more, The grease composition according to claim 1 or 2, wherein the base oil (A) includes a synthetic oil. Claim 4 The grease composition according to claim 1 or 2, wherein the penetration of the grease composition is 190 to 240. Claim 5 The grease composition according to claim 2, wherein the monoamine is cyclohexylamine or octadecylamine. Claim 6 The grease composition according to claim 1 or 2, which is used for a rolling bearing having a rolling element diameter of 10 mm or less.

Images