Grease composition

Abstract

To provide a grease composition that does not lose its viscosity when mixed with water.SOLUTION: The grease composition contains base oil (A), a thickener (B), and an aliphatic amide (C).SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Grease is a semi-solid lubricant made by dispersing a solid, highly lipophilic thickener in a base oil. Grease adheres more easily to lubricated parts and is less likely to leak out than lubricating oil. Therefore, using grease can simplify the mechanical structure of the lubrication system. Grease also leaks less than lubricating oil, creating a cleaner environment, and the replenishment interval can be shortened compared to lubricating oil. Grease is mainly used to lubricate machine elements such as rolling bearings, plain bearings, ball screws, linear guides, and gears. Rolling bearings are widely used in machine tool spindles, railroad car carriages, engine accessories such as automobile alternators, constant velocity joints, and wheels.

[0003] For example, Patent Document 1 describes a grease composition containing a thickener, a base oil, a wax, and a phosphate ester, but not containing an overbased Ca sulfonate, in which the thickener is a diurea compound or a complex Li soap having a specific structure, and the kinematic viscosity of the base oil at 40°C is 4 to 100 mm. 2 / s, the phosphate ester is at least one compound selected from the group consisting of acid phosphate esters and amine salts of acid phosphate esters, and the composition has a worked penetration of 265 to 385. It is disclosed that this grease composition can exhibit good anti-wear properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-006339 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional grease compositions such as that described in Patent Document 1, even if the viscosity of the grease composition is controlled to a specific range during production, the viscosity of the grease composition may decrease when the grease composition is used, and the desired effect may not be obtained. For example, a grease composition used in the sliding parts of a concrete pump that pumps fresh concrete at high pressure may experience a decrease in viscosity when it comes into contact with fresh concrete due to the effect of water contained in the fresh concrete.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a grease composition whose viscosity does not decrease even when water is mixed in. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following configuration. [1] A grease composition comprising a base oil (A), a thickener (B), and an aliphatic amide (C). [2] The grease composition according to [1], wherein the thickener (B) is a metal soap-based thickener (B1). [3] The grease composition according to [1] or [2], wherein the aliphatic amide (C) is an aliphatic bisamide. [4] The grease composition according to any one of [1] to [3], wherein the content of the thickener (B) is 0.05% by mass or more and 5.0% by mass or less, relative to 100% by mass of the total amount of the grease composition. [5] The grease composition according to any one of [1] to [4], which has a consistency of 400 to 500. [6] The grease composition according to any one of [1] to [5], which is used for sliding parts of a concrete pump. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a grease composition whose viscosity does not decrease even when water is mixed in. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Grease composition) The grease composition of the present embodiment contains a base oil (A), a thickener (B), and an aliphatic amide (C). One aspect of the grease composition of the present embodiment is a grease composition for concrete pumps. Generally, grease compositions have short replenishment intervals, but unlike other uses, grease compositions for concrete pumps are continuously injected into the sliding parts of the concrete pump through the pump, piping, and distributor as a centralized lubrication system. Therefore, it is preferable that the grease composition for a concrete pump has high consistency and relatively high fluidity so that it can be pumped by a pump.

[0010] The consistency of the grease composition of this embodiment is preferably 400 or more, more preferably 420 or more, and even more preferably 440 or more. The consistency of the grease composition of this embodiment is preferably 500 or less, more preferably 490 or less, and even more preferably 480 or less. For example, the consistency of the grease composition of this embodiment is preferably 400 or more and 500 or less, more preferably 420 or more and 490 or less, and even more preferably 440 or more and 480 or less. In this specification, the consistency refers to worked consistency measured in accordance with JIS K2220:2013.

[0011] <Base oil (A)> The grease composition of the present embodiment contains a base oil (A). The kinematic viscosity of base oil (A) at 40°C is 100mm 2 / s or more is preferable, 110mm 2 / s or more is preferable, 120mm 2 / s or more is even more preferable. The kinematic viscosity of base oil (A) at 40°C is 140mm 2 / s or less is preferable, 135mm 2 / s or less is preferable, and 130 mm 2 / s or less is even more preferable.

[0012] When the kinematic viscosity at 40°C of the base oil (A) of the grease composition of this embodiment is equal to or greater than the above-mentioned preferable lower limit, the lubricity of the grease composition is improved, and the effects of using the grease composition can be more fully obtained. When the kinematic viscosity at 40° C. of the base oil (A) of the grease composition of this embodiment is equal to or less than the above-mentioned preferable upper limit, the viscous resistance caused by the grease composition is further reduced.

[0013] For example, the kinematic viscosity of base oil (A) at 40°C is 100mm 2 / s or more 140mm 2 / s or less is preferable, 110 mm 2 / s or more 135mm 2 / s or less is preferable, and 120 mm 2 / s or more 130mm 2 / s or less is even more preferable.

[0014] The kinematic viscosity of base oil (A) at 100°C is 5.0 mm 2 / s or more is preferable, 8.0 mm 2 / s or more is preferable, and 10.0 mm 2 / s or more is even more preferable. The kinematic viscosity of base oil (A) at 100°C is 20.0 mm 2 / s or less is preferable, 18.0 mm 2 / s or less is more preferable, and 15.0 mm 2 / s or less is even more preferable.

[0015] When the kinematic viscosity at 100°C of the base oil (A) of the grease composition of this embodiment is equal to or greater than the above-mentioned preferable lower limit, the lubricity of the grease composition is improved, and the effects of using the grease composition can be more fully obtained. When the kinematic viscosity at 100° C. of the base oil (A) of the grease composition of this embodiment is equal to or less than the above-mentioned preferable upper limit, the viscosity resistance caused by the grease composition is further reduced.

[0016] For example, the kinematic viscosity of base oil (A) at 100°C is 5.0 mm 2 / s or more 20.0mm 2 / s or less is preferable, 8.0 mm 2 / s or more 18.0mm 2 / s or less is more preferable, and 10.0 mm 2 / s or more 15.0mm 2 / s or less is even more preferable.

[0017] In this specification, the kinematic viscosities at 40°C and 100°C refer to the kinematic viscosities at 40°C measured in accordance with JIS K2283:2000.

[0018] The base oil (A) of the grease composition of this embodiment may be a mineral oil or a synthetic oil.

[0019] <Mineral oil> As the mineral oil, a distillate obtained by atmospheric distillation of crude oil can be used. In addition, a lubricating oil fraction obtained by further vacuum distillation of the distillate obtained by the atmospheric distillation and then refining the distillate through various refining processes can also be used. The refining process may be a suitable combination of hydrorefining, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc. Mineral oil can be obtained by combining these refining processes in a suitable order. Furthermore, a mixture of a plurality of refined oils with different properties obtained by subjecting different crude oils or distillate oils to a combination of different refining processes may also be used.

[0020] As the mineral oil, API base oil classification Group I base oil (hereinafter referred to as "API Group I base oil"), Group II base oil (hereinafter referred to as "API Group II base oil"), or Group III base oil (hereinafter referred to as "API Group III base oil"), or a mixture thereof, can be used. API Group I base oils are mineral base oils having a sulfur content greater than 0.03 wt.% and / or a saturates content less than 90 wt.% and a viscosity index greater than or equal to 80 and less than 120. API Group II base oils are mineral base oils having a sulfur content of 0.03% by weight or less, a saturates content of 90% by weight or more, and a viscosity index of 80 or greater but less than 120. API Group III base oils are mineral base oils having a sulfur content of 0.03% by weight or less, a saturates content of 90% by weight or more, and a viscosity index of 120 or greater.

[0021] The base oil (A) of the grease composition of this embodiment may be a single mineral oil or a mixture of multiple mineral oils, the API classifications of which may be the same or different.

[0022] ≪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. Among the above synthetic oils, polyolefins are preferred, and poly-α-olefins (PAOs) are more preferred, from the viewpoints of availability, cost, viscosity characteristics, and oxidation stability. As the base oil (A) of the grease composition of this embodiment, one synthetic oil may be used alone, or a mixture of multiple synthetic oils may be used.

[0023] As the base oil (A) of the grease composition of this embodiment, either a mineral oil or a synthetic oil may be used, or a mixture of a mineral oil and a synthetic oil may be used.

[0024] The content of the base oil (A) in the grease composition of this embodiment is preferably 90 mass % or more, more preferably 92 mass % or more, and even more preferably 93 mass % or more, based on the total amount of the grease composition. The content of the base oil (A) in the grease composition of this embodiment is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, based on the total amount of the grease composition. For example, the content of base oil (A) in the grease composition of this embodiment is preferably 90% by mass or more and 99% by mass or less, more preferably 92% by mass or more and 98% by mass or less, and even more preferably 93% by mass or more and 97% by mass or less, based on the total amount of the grease composition.

[0025] <Thickener (B)> The grease composition of this embodiment contains a thickener (B). Specific examples of the thickener (B) include metal soap-based thickeners (B1) and urea-based thickeners (B2).

[0026] <Metal soap-based thickener (B1)> The metal soap-based thickener (B1) (hereinafter also referred to as "component (B1)") includes simple soaps and complex soaps. The simple soap is a metallic soap obtained by saponifying a fatty acid or fat with an alkali metal hydroxide or alkaline earth metal hydroxide. Complex soap is a compound soap that combines the fatty acids used in simple soap with organic acids of different molecular structures. The fatty acid may be a fatty acid derivative having a hydroxy group or the like. The fatty acid is preferably a monovalent or divalent aliphatic carboxylic acid. The fatty acid is preferably an aliphatic carboxylic acid having 6 to 20 carbon atoms, more preferably a monovalent aliphatic carboxylic acid having 12 to 20 carbon atoms or a divalent aliphatic carboxylic acid having 6 to 14 carbon atoms. Among the above, the fatty acid is preferably a monovalent aliphatic carboxylic acid containing one hydroxy group. As the organic acid to be combined with the fatty acid in the complex soap, a dibasic acid such as acetic acid, azelaic acid or sebacic acid, or benzoic acid is preferred.

[0027] As the metal for the metallic soap-based thickener (B1), an alkali metal such as lithium or sodium, an alkaline earth metal such as calcium, or an amphoteric metal such as aluminum can be used. The component (B1) may be used alone or in combination of two or more.

[0028] Of the above, the component (B1) is preferably a simple soap, more preferably a simple soap comprising a fatty acid derivative having a hydroxy group and an alkali metal, and even more preferably lithium 12-hydroxystearate soap.

[0029] <Urea-based thickener (B2)> Examples of the urea-based thickener (B2) (hereinafter also referred to as "component (B2)") include diurea compounds and polyurea compounds. A diurea compound is a compound obtained by reacting a diisocyanate with a monoamine, and has two urea groups (-NH-CO-NH-). In this specification, a polyurea compound refers to a compound obtained by reacting a diisocyanate with a monoamine or diamine, and having three or more urea groups (—NH—CO—NH—).

[0030] Diisocyanates Diisocyanates are compounds in which two hydrogen atoms of a hydrocarbon are replaced with an isocyanate group (-N=C=O). The hydrocarbon may be a cyclic hydrocarbon or a chain hydrocarbon, and may be an aromatic hydrocarbon or an aliphatic hydrocarbon. The number of carbon atoms in the hydrocarbon is preferably 4 to 20, and more preferably 8 to 18. In the present invention, "4 to 20 carbon atoms" means having 4 or more and 20 or less carbon atoms.

[0031] Specific preferred examples of diisocyanates include phenylene diisocyanate, tolylene diisocyanate, biphenyl diisocyanate (diphenyl diisocyanate), diphenylmethane-4,4'-diisocyanate (MDI), octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate. The diisocyanates may be used singly or in combination of two or more.

[0032] Monoamines A monoamine is a compound that contains one amino group per molecule. Preferred monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine (octadecylamine), oleylamine, aniline, p-toluidine, and cyclohexylamine. The monoamine may be a cyclic amine or a chain amine, and may also be an alicyclic amine, an aromatic amine, or an aliphatic amine. The monoamine preferably has 4 to 20 carbon atoms, and more preferably 8 to 18 carbon atoms.

[0033] Diamine A diamine is a compound that has two amino groups in one molecule. Preferred diamines include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and diaminodiphenylmethane. The diamine may be a cyclic amine or a chain amine, and may also be an alicyclic amine, an aromatic amine, or an aliphatic amine. The diamine preferably has 4 to 20 carbon atoms, and more preferably 8 to 18 carbon atoms.

[0034] The component (B2) may be used alone or in combination of two or more. Of the above, diurea compounds are preferred as component (B2). The diurea compound is preferably a compound obtained by reacting a diisocyanate having an aromatic hydrocarbon group with a monoamine. As the diisocyanate having an aromatic hydrocarbon group, diphenylmethane-4,4'-diisocyanate (MDI) is preferred. The monoamine is preferably an alicyclic amine or an aliphatic amine.

[0035] <Other thickeners (B3)> Specific examples of other thickeners (B3) (hereinafter also referred to as "component (B3)") include inorganic thickeners such as bentonite and silica gel. The component (B3) may be used alone or in combination of two or more.

[0036] As the thickener (B) of the grease composition of this embodiment, any one of the components (B1), (B2), and (B3) may be used, or a mixture of two or more of the components (B1), (B2), and (B3) may be used. The thickener (B) of the grease composition of this embodiment is preferably component (B1), and more preferably a single soap.

[0037] The proportion of the (B1) component in the thickener (B) of the grease composition of this embodiment is preferably 80 mass % or more, more preferably 90 mass % or more, based on the total amount of the thickener (B), and even more preferably 100 mass %, i.e., it is composed solely of the (B1) component. In one embodiment, the grease composition does not include a grease composition containing components (B2) and (B3) as the thickener (B).

[0038] The content of the thickener (B) in the grease composition of this embodiment is preferably 1.0 mass % or more, more preferably 1.5 mass % or more, and even more preferably 2.0 mass % or more, based on the total amount of the grease composition. The content of the thickener (B) in the grease composition of this embodiment is preferably 8.0 mass % or less, more preferably 5.0 mass % or less, and even more preferably 3.5 mass % or less, based on the total amount of the grease composition. For example, the content of the thickener (B) in the grease composition of this embodiment is preferably 1.0 mass% or more and 8.0 mass% or less, more preferably 1.5 mass% or more and 5.0 mass% or less, and even more preferably 2.0 mass% or more and 3.5 mass% or less, relative to the total amount of the grease composition.

[0039] <Aliphatic amide (C)> The aliphatic amide (C) is a compound in which at least one hydrogen atom of an aliphatic hydrocarbon is substituted with an amide group (-NH-CO-). Examples of the aliphatic amide (C) include a compound containing one amide group (aliphatic monoamide), a compound containing two amide groups (aliphatic bisamide), and a compound containing three amide groups (aliphatic triamide). Among these, aliphatic bisamide is preferred.

[0040] The aliphatic monoamide may be either an acid amide of a monoamine or an acid amide of a monoacid, and the aliphatic bisamide may be either an acid amide of a diamine or an acid amide of a diacid. The aliphatic amide (C) preferably has a melting point of 40°C or higher and 180°C or lower, more preferably 80°C or higher and 180°C or lower, and even more preferably 100°C or higher and 170°C or lower. The aliphatic amide (C) preferably has a molecular weight of 242 or more and 932 or less, more preferably 298 or more and 876 or less. Aliphatic monoamides, bisamides, and triamides are represented by the following general formula (1), general formulas (2) and (3), and general formula (4), respectively.

[0041] R 1 -CO-NH-R 2 ····(1) R 1 -CO-NH-A 1 -NH-CO-R 2 ····(2) R 1 -NH-CO-A 1 -CO-NH-R 2 ····(3) R 1 -MA 1 -CH(A 2-MR 3 )-A 3 -MR 2 ····(4) [In the formula, R 1 , R 2 , R 3 are each independently an aliphatic hydrocarbon group having 5 to 25 carbon atoms. 2 This includes cases where A is a hydrogen atom. 1 , A 2 , A 3 are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and M is an amide group.

[0042] For aliphatic monoamides, R 2 is preferably a hydrogen atom or a saturated or unsaturated chain hydrocarbon group having 10 to 20 carbon atoms. In the case of diamine acid amide, A 1 is preferably a saturated chain hydrocarbon group having 1 to 4 carbon atoms. Furthermore, in formulas (2) and (3), R 1 , R 2 , or A 1 In the hydrocarbon group represented by the formula (I), some of the hydrogen atoms may be substituted with hydroxyl groups (-OH).

[0043] Specific examples of the acid amide of the diamine represented by the general formula (2) include ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bisoleic acid amide, methylene bislauric acid amide, hexamethylene bisoleic acid amide, and hexamethylene bishydroxystearic acid amide. Specific examples of the bisamide of the diacid represented by the general formula (3) include N,N'-bisstearylsebacic acid amide. Among these aliphatic bisamides, R 1 and R 2 are each independently an aliphatic amide of a saturated chain hydrocarbon group or an unsaturated chain hydrocarbon group having 12 to 20 carbon atoms.

[0044] Examples of the aliphatic amide represented by the general formula (4) include N-acylamino acid diamide compounds. The N-acyl group of this compound is preferably a linear or branched, saturated or unsaturated aliphatic acyl group or aromatic acyl group having 1 to 30 carbon atoms, particularly caproyl, capryloyl, lauroyl, myristoyl, or stearoyl group. The amino acid is preferably aspartic acid or glutamic acid. The amine of the amide group is preferably a linear or branched, saturated or unsaturated aliphatic amine having 1 to 30 carbon atoms, particularly butylamine, octylamine, laurylamine, isostearylamine, or stearylamine. A particularly preferred specific compound is N-lauroyl-L-glutamic acid-α,γ-di-n-butylamide.

[0045] The aliphatic amide (C) is preferably an aliphatic bisamide represented by formula (2), of which ethylene bisstearic acid amide and ethylene bisoleic acid amide are more preferred.

[0046] The aliphatic amide (C) may be used alone or in combination of two or more kinds. The content of the aliphatic amide (C) is preferably 0.1 mass % or more, more preferably 0.2 mass % or more, even more preferably 0.5 mass % or more, and particularly preferably 0.7 mass % or more, based on the total amount of the grease composition. The content of the aliphatic amide (C) is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less, based on the total amount of the grease composition. For example, the content of the aliphatic amide (C) is preferably 0.1 mass% or more and 10 mass% or less, more preferably 0.2 mass% or more and 5.0 mass% or less, even more preferably 0.5 mass% or more and 2.0 mass% or less, and particularly preferably 0.7 mass% or more and 1.0 mass% or less, based on the total amount of the grease composition.

[0047] When the content of the aliphatic amide (C) is equal to or greater than the above-mentioned preferable lower limit, the viscosity of the grease composition is less likely to decrease even when water is mixed into the grease composition. When the content of the aliphatic amide (C) is equal to or less than the above-mentioned preferable upper limit, the fluidity of the grease composition is further improved, resulting in a grease composition.

[0048] <Optional ingredients> The grease composition of this embodiment may contain optional components other than the above-mentioned base oil (A), thickener (B), and aliphatic amide (C), such as solid lubricants, antiwear or extreme pressure agents, antioxidants, oiliness agents, rust inhibitors, and corrosion inhibitors.

[0049] Examples of solid lubricants include graphite, graphite fluoride, melamine cyanurate, polytetrafluoroethylene, molybdenum disulfide, antimony sulfide, boron nitride, and alkaline (earth) metal borates. When the grease composition contains a solid lubricant, the content thereof is, for example, 0.1 to 20 mass% relative to the total amount of the grease composition. One type of solid lubricant may be used alone, or multiple solid lubricants may be used in combination.

[0050] Examples of anti-wear agents or extreme pressure agents include organic zinc compounds such as zinc dialkyldithiophosphate and zinc dialkyldithiocarbamate; sulfur-containing compounds such as molybdenum dialkyldithiocarbamate, dihydrocarbyl polysulfide, sulfurized esters, thiazole compounds, and thiadiazole compounds; and phosphorus-based extreme pressure agents such as phosphate esters, acid phosphate esters, amine salts of acid phosphate esters, and phosphites. When the grease composition contains an anti-wear agent or extreme pressure agent, the content thereof is preferably, for example, 0.1 to 10 mass%, and more preferably 0.5 to 1.5 mass%, based on the total amount of the grease composition. One type of anti-wear agent or extreme pressure agent may be used alone, or multiple anti-wear agents or extreme pressure agents may be used in combination.

[0051] Examples of antioxidants 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, the content thereof is, for example, 0.5 to 10 mass% relative to the total amount of the grease composition. One type of antioxidant may be used alone, or multiple antioxidants may be used in combination.

[0052] Examples of oily agents include amines such as laurylamine, myristylamine, palmitylamine, stearylamine, and oleylamine; higher alcohols such as lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid; fatty acid esters such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate, and methyl oleate; and fats and oils such as glycerin oleate and glycerin stearate. When the grease composition contains an oily agent, the content thereof is, for example, 0.01 to 5% by mass relative to the total amount of the grease composition. One oily agent may be used alone, or multiple oily agents may be used in combination.

[0053] Examples of rust inhibitors include amines, neutral or overbased petroleum-based or synthetic oil-based metal sulfonates, metal carboxylates, esters, phosphoric acid, phosphates, etc. When the grease composition contains a rust inhibitor, the content thereof is, for example, 0.005 to 5 mass% relative to the total amount of the grease composition. One type of rust inhibitor may be used alone, or multiple rust inhibitors may be used in combination.

[0054] As the corrosion inhibitor, for example, known corrosion inhibitors such as benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, and imidazole-based compounds can be used. When the grease composition contains a corrosion inhibitor, the content thereof is, for example, 0.01 to 10 mass% relative to the total amount of the grease composition. The corrosion inhibitor may be used alone, or multiple corrosion inhibitors may be used in combination.

[0055] The grease composition of this embodiment contains a base oil (A), a thickener (B), and an aliphatic amide (C). If the grease composition consists only of the base oil (A) and the thickener (B), the viscosity will decrease when water is mixed into the grease composition. On the other hand, because the grease composition of this embodiment further contains the aliphatic amide (C), the viscosity will not decrease even when water is mixed into the grease composition of this embodiment. This is presumably due to the effect of the aliphatic amide (C) which improves the compatibility of the base oil (A) and the thickener (B) with water. [Example]

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0057] <Preparation of grease composition> The grease compositions of Examples 1 to 5 and Comparative Examples 1 to 5 were prepared according to the blending ratios shown in Tables 1 and 2. The values ​​in Table 1 indicate the blending ratio (% by mass) relative to the total amount of the grease composition. The total of all components is 100% by mass, and the value obtained by subtracting the content of each component from 100% by mass is the content of base oil (A).

[0058] (1) Base oil (A) ·(A)-1: Mineral oil (40℃ kinematic viscosity=126.2mm 2 / s, 100℃ kinematic viscosity=13.0mm 2 / s)

[0059] (2) Thickener (B) (B)-1: 12-hydroxystearate lithium soap

[0060] (3) Aliphatic amide (C) (C)-1: Ethylene bis oleic acid amide (C)-2: Ethylene bisstearic acid amide

[0061] (4) Additives X-1: Zinc dialkyldithiophosphate X-2: Polybutene X-3: Calcium sulfonate (mixed) X-4: Calcium sulfonate (overbased) X-5: Calcium sulfonate (neutral)

[0062] [Consistency evaluation] The worked penetration of each grease composition measured in accordance with JIS K2220:2013 is shown in Tables 1 and 2.

[0063] [Rotational viscosity measurement] The rotational viscosity of each grease composition and a mixed solution in which 10% by mass of water was added to 90% by mass of each grease composition was measured under the following measurement conditions. Equipment used: HAAKE MARS3 Measurement temperature: 25℃ Sensor used: Parallel plate type 25mm Sample thickness: 1 mm Shear rate: 0.01 (1 / s)

[0064] The rotational viscosity of each grease composition example is shown as "rotational viscosity vs. water content (0 mass%)," and the rotational viscosity of a mixed solution in which 10 mass% water was added to 90 mass% water in each grease composition example is shown as "rotational viscosity vs. water content (10 mass%)," in Table 1. The rate of change (viscosity at water content (10 mass%) / viscosity at water content (0 mass%)) is also shown in Table 1. A grease composition whose rotational viscosity does not decrease with the addition of water is preferred, and from the perspective of making the oil film thicker and lowering the coefficient of friction, a grease composition whose rotational viscosity improves with the addition of water is more preferred. Grease compositions with a rate of change (viscosity at water content (10% by mass) / viscosity at water content (0% by mass)) of 50% or more were judged to have good results. In other words, grease compositions with a viscosity decrease due to water content of 50% or more (viscosity at water content (10% by mass) becomes half of the viscosity at water content (0% by mass)) were judged to have good results.

[0065] [Table 1]

[0066] [Table 2]

[0067] As shown in Tables 1 and 2, the grease compositions of Examples showed less decrease in rotational viscosity even after the addition of water than the grease compositions of Comparative Examples. Furthermore, the rotational viscosity of the grease compositions of Examples 1 and 5 was further improved by adding water.

Claims

1. A grease composition comprising a base oil (A), a thickener (B), and an aliphatic amide (C).

2. 2. The grease composition according to claim 1, wherein the thickener (B) is a metal soap-based thickener (B1).

3. 3. The grease composition according to claim 1, wherein the aliphatic amide (C) is an aliphatic bisamide.

4. 3. The grease composition according to claim 1, wherein the content of the thickener (B) is 1.0 mass % or more and 8.0 mass % or less, relative to 100 mass % of the total amount of the grease composition.

5. 3. The grease composition according to claim 1, wherein the consistency is 400 to 500.

6. 3. The grease composition according to claim 1, which is used for sliding parts of a concrete pump.

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