JP2024051124A - Grease composition - Google Patents

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

The present invention relates to a grease composition.

Generally, machine elements that contain balls that slide back and forth include linear guides, ball screws, and constant velocity joints, and are used in a wide variety of environments. Furthermore, these machine elements are mechanisms in which rolling and sliding can occur simultaneously, and the lubrication environment is harsh. Under these conditions, contact between the surfaces of the rolling components can easily occur, and severe contact can result in wear and seizure.

To prevent such wear and seizure and protect machine 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 organic compounds, molybdenum compounds, etc. Among these, organic extreme pressure agents are the mainstream of extreme pressure agents because they exhibit excellent extreme pressure performance, and are widely used in various lubricating oil compositions.

For example, Patent Document 1 discloses a technology for improving the lubrication of parts that are prone to wear and malfunctions such as abnormal vibrations, using a grease composition for sliding constant velocity joints that contains a urea thickener, molybdenum sulfide dialkyldithiocarbamate, molybdenum disulfide, a sulfur-phosphorus extreme pressure agent such as zinc dithiophosphate or thiophosphate, and a fatty acid amide. According to this patent, the generation of induced thrust force in constant velocity joints has been problematic in that it reduces the durability of the constant velocity joint, causes abnormal vibration in the vehicle, and worsens the ride comfort, but this patent discloses a technology for reducing wear, suppressing vibration, and improving durability.

Patent Document 2 discloses a technology in which a grease composition containing a urea thickener and an organic sulfonate prevents peeling caused by metal fatigue due to a thin oil film without increasing the thickness of the oil film, thereby extending the life of peeling caused by metal fatigue.

Patent Document 3 discloses a technology in which a grease composition for rolling bearings, which is characterized by containing a urea thickener, benzotriazole and/or its derivatives, can prevent peeling caused by metal fatigue due to a thin oil film without increasing the thickness of the oil film, thereby extending the peeling life.

Patent Document 4 discloses a technology for improving the fretting resistance of a bearing grease composition that contains a urea thickener, an alkyl phosphorothioate compound, and an aliphatic amine compound.

Patent Document 5 discloses a technology in which a grease composition containing a urea thickener, molybdenum dithiocarbamate, zinc dithiocarbamate, and zinc sulfonate maintains and forms an additive film that prevents metal contact and reduces friction even when lubricated at high speeds and high surface pressures.

JP 2001-11481 A JP 2003-321694 A JP 2003-82374 A JP 2008-239687 A JP 2017-25189 A

However, while the lubricant and grease compositions of Patent Documents 1 to 5 exhibit good wear resistance and film-forming ability under certain conditions or with certain machine elements, they have not yet provided compositions that can maintain stable, overall balanced wear resistance and film-forming ability even during reciprocating sliding under various high loads. In particular, the effect on flaking that occurs due to reciprocating sliding under various high loads has not been examined, and there is a risk that it may be insufficient.

The present invention was made in consideration of these circumstances, and its purpose is to form a strong additive coating to maintain and improve the lifespan of mechanical parts even in situations where a sufficient oil film cannot be generated and metal contact occurs, making friction and wear excessive when the rolling stops momentarily during reversal of reciprocating sliding, and the formed coating is maintained stably even with repeated operations, providing stable lubrication properties. In other words, the purpose is to provide a grease composition that can be used to lubricate mechanical elements containing reciprocating sliding balls, maintaining flaking resistance even under high loads.

As a result of extensive research to achieve the above objective, the inventors discovered a formulation technology that improves flaking resistance and can be used for machine elements that contain reciprocating balls by blending an amide compound with a thiophosphorous compound or a thiophosphate ester compound with a specific diurea compound, thereby completing the present invention.

（但し、Ｒ_１及びＲ_３は、炭素数が８～２０である、非環式の脂肪族炭化水素基を示し、Ｒ_２は、ジフェニルメタン基を示す）
（式２）

（但し、Ｒ_４は、炭素数５～１８の、飽和又は不飽和の炭化水素基を示し、Ｒ_５は炭素数２～３の飽和又は不飽和の炭化水素基を示す）
本発明（２）は、
前記ジウレア化合物（ｂ）は、前記式１におけるＲ_１及びＲ_３が、炭素数が８～１２である非環式の脂肪族炭化水素基、又は、炭素数が１４～２０である非環式の脂肪族炭化水素基、のいずれかであるジウレア化合物（ｂ）を含むことを特徴とする、前記発明（１）のグリース組成物である。
本発明（３）は、
炭素数４～１８の飽和若しくは不飽和の脂肪酸又はその金属塩（ｅ）を含むことを特徴とする、前記発明（１）又は（２）のグリース組成物である。
本発明（４）は、
前記アミド化合物（ｃ）が、下式３又は下式４で表されるアミド化合物（ｃ）を含むことを特徴とする、前記発明（１）～（３）のいずれのグリース組成物である。
（式３）

（式４）

（但し、Ｒ_６は、炭素数１５～１７の、飽和又は不飽和の炭化水素基を示し、Ｒ_７はメチレン基又はエチレン基を示す）
本発明（５）は、
前記チオリン酸エステル化合物は、下式６で表されるチオリン酸エステル化合物を含むことを特徴とする、前記発明（１）～（４）のいずれかのグリース組成物である。
（式６）

（但し、Ｒ_９は、炭素数８～１８の、飽和又は不飽和の炭化水素基、若しくは、炭素数６～１８のアリール基を示す。） That is, the present invention is as follows.
The present invention (1) is
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 is characterized in that the diurea compound (b) contains a compound represented by the following formula 1:
(Equation 1)

(wherein _R1 and _R3 represent a non-cyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and _R2 represents a diphenylmethane group).
(Equation 2)

(wherein R ₄ represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms, and R ₅ represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms).
The present invention (2) is
The grease composition of the invention (1) is characterized in that it contains the diurea compound (b) in which R ₁ and R ₃ in formula 1 are either acyclic aliphatic hydrocarbon group having 8 to 12 carbon atoms or acyclic aliphatic hydrocarbon group having 14 to 20 carbon atoms.
The present invention (3) is
The grease composition according to the above invention (1) or (2) is characterized in that it contains (e) a saturated or unsaturated fatty acid having 4 to 18 carbon atoms or a metal salt thereof.
The present invention (4) is
The grease composition according to any one of inventions (1) to (3), wherein the amide compound (c) contains an amide compound (c) represented by the following formula 3 or 4:
(Equation 3)

(Equation 4)

(wherein R ₆ represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms, and R ₇ represents a methylene group or an ethylene group).
The present invention (5) is
The grease composition according to any one of inventions (1) to (4) is characterized in that the thiophosphate ester compound contains a thiophosphate ester compound represented by the following formula 6:
(Equation 6)

(wherein 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).

The present invention provides a grease composition that can be used to lubricate mechanical elements containing reciprocating balls, and that maintains flaking resistance even under high loads.

FIG. 1 is a diagram showing an outline of the anti-flaking test machine.

In this application, the term "hydrocarbon group" refers to an atomic group formed by removing some hydrogen atoms from a hydrocarbon.

In this application, when a compound name is mentioned, it is meant to include all isomers.

In this application, the amine compound that forms the diurea compound described below is referred to as the raw material amine compound. The raw material amine compound and the amine compound (f) may be the same or different. In this specification, when the amount of amine compound (f) is mentioned, the raw material amine compound is not included.

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 ester compound (d).

（但し、Ｒ_１及びＲ_３は、炭素数が８～２０である、非環式の脂肪族炭化水素基を示し、Ｒ_２は、ジフェニルメタン基を示す） The diurea compound (b) according to the present invention includes a compound represented by the following formula 1.
(Equation 1)

(wherein _R1 and _R3 represent a non-cyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and _R2 represents a diphenylmethane group).

The diurea compound (b) of 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 isocyanate and primary amine (raw amine compound), and the flow characteristics of the grease composition change significantly.

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

Furthermore, in the grease composition of the present invention containing the diurea compound (b), the amide compound (c), and the thiophosphorous acid compound or thiophosphate compound (d), a remarkable effect is shown in improving the flaking resistance performance, 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 performance of a machine element containing a reciprocatingly sliding ball.

In the fluid lubrication region where the sliding speed of the reciprocating motion is high, this effect is thought to be due to the thickening of the lubricating film caused by the improved supply of the grease composition to the lubrication interface due to the excellent flow properties of the aliphatic diurea thickener, and further, the lubricating film caused by the diurea compound (b), as well as the flow properties of the amide compound (c) and the fatty acid or its fatty acid salt (e) and the synergistic film thickening effect with the urea grease due to adsorption to the metal surface. In the mixed lubrication region and boundary lubrication region where the oil film near the end point of the reciprocating motion approaches zero, the thiophosphorous acid compound or thiophosphate ester compound (d) and amine compound (f) contained in the grease composition, which were abundantly supplied to the lubrication interface due to the excellent flow properties of the grease, are adsorbed to the metal surface and form a strong coating due to a tribochemical reaction at the boundary surface, which is thought to be the reason for the good flaking resistance.

<<<Grease composition>>>
<<Components of 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 impair 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 categories. Here, the API base oil categories are broad classifications of base oil materials defined by the American Petroleum Institute to create guidelines for lubricating base oils.

The mineral oil according to the present invention is not particularly limited, but preferred examples include paraffinic or naphthenic mineral oils obtained by applying one or more refining methods, such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment, in appropriate combination to the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil. These can be used alone or in combination.

The synthetic oil according to the present invention is not particularly limited, but preferred examples include poly-α-olefins (PAOs) or hydrocarbon synthetic oils (oligomers). PAOs are homopolymers or copolymers of α-olefins. For example, α-olefins are compounds with a C-C double bond at the end, such as butene, butadiene, hexene, cyclohexene, methylcyclohexene, octene, nonene, decene, dodecene, tetradecene, hexadecene, octadecene, and eicosene. Hydrocarbon synthetic oils (oligomers) can be homopolymers or copolymers of ethylene, propylene, or isobutene. These can be used alone or in combination. In addition, as long as these compounds have a C-C double bond at the end, they may have any of the possible isomeric structures, and may be branched or linear. Two or more of these structural isomers or positional isomers of the double bond can also be used in combination. Of these olefins, those with 5 or fewer carbon atoms have a low flash point, and those with 31 or more carbon atoms have a high viscosity and are less practical, so it is more preferable to use linear olefins with 6 to 30 carbon atoms.

In addition, in the present invention, GTL (gas-to-liquid) synthesized by the Fischer-Tropsch process, a technology for converting natural gas into liquid fuel, can be used as base oil (a). Compared to mineral oil base oils refined from crude oil, GTL has extremely low sulfur and aromatic content and an extremely high paraffin composition ratio, so it has excellent oxidation stability and very small evaporation loss, and can therefore be suitably used as base oil (a) in the present invention.

ここで、式１中のＲ_１及びＲ_３は、炭素数が８～２０である、非環式の脂肪族炭化水素基を示し、Ｒ_２は、ジフェニルメタン基を示す。 <Diurea Compound (b)>
The grease composition of the present invention contains a diurea compound (b) represented by the following formula 1:
(Equation 1)

Here, R ₁ and R ₃ in formula 1 represent acyclic aliphatic hydrocarbon groups having 8 to 20 carbon atoms, and R ₂ represents a diphenylmethane group.

_R1 and _R3 may be acyclic aliphatic hydrocarbon groups, and may be linear or branched, saturated or unsaturated aliphatic hydrocarbon groups. _R1 and _R3 may have the same structure or different structures.

The diurea compound (b) according to the present invention can be obtained by the reaction of the following formula 7.
(Equation 7)

It is preferable that _R1 and _R3 are each 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, it is possible to obtain a grease composition having better wear resistance and flaking resistance.

The diurea compound (b) of the present invention can be used alone or in combination with multiple compounds.

（式４）

式中のＲ_６は、炭素数１５～１７の、飽和又は不飽和の炭化水素基を示し、Ｒ_７はメチレン基又はエチレン基を示す。 <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 impair 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 better wear resistance and flaking resistance can be obtained.
(Equation 3)

(Equation 4)

In the formula, R ₆ represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms, and R ₇ represents a methylene group or an ethylene group.

Specific examples of such aliphatic amide compounds or aliphatic bisamide compounds 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, eleostearic acid amide, arachidic acid amide, eicosadienoic acid amide, mead acid amide, arachidonic acid amide, erucic acid amide, behenic acid amide, methylenebispalmitic acid amide, methylenebispalmitoleic acid amide, methylenebismargaric acid amide, methylenebis Examples of the amides include stearic acid amide, methylene bis oleic acid amide, methylene bis vaccenic acid amide, methylene bis linoleic acid amide, methylene bis linolenic acid amide, methylene bis eleostearic acid amide, ethylene bis palmitic acid amide, ethylene bis palmitoleic acid amide, ethylene bis margaric acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis vaccenic acid amide, ethylene bis linoleic acid amide, ethylene bis linolenic acid amide, and ethylene bis eleostearic acid amide. These can be used alone or in combination.

The grease composition of the present invention contains a thiophosphorous acid compound or a thiophosphate ester compound (d). The thiophosphorous acid compound or thiophosphate ester compound (d) of the present invention is not limited as long as it does not inhibit the effects of the present invention. In addition, a thiophosphorous acid compound and a thiophosphate ester compound can be used in combination.

ここで、Ｒ_８は、炭素数８～１８の、飽和又は不飽和の炭化水素基、若しくは、炭素数６～１８のアリール基を示す。
（式６）

ここで、Ｒ_９は、炭素数８～１８の、飽和又は不飽和の炭化水素基、若しくは、炭素数６～１８のアリール基を示す。 As the thiophosphorous acid compound or thiophosphate ester compound according to the present invention, for example, a thiophosphorous acid compound represented by the following formula 5 or a thiophosphate ester compound represented by the following formula 6 is preferably used. When the thiophosphorous acid compound or thiophosphate ester compound (d) has such a structure, a grease composition having more excellent wear resistance and flaking resistance can be obtained.
(Equation 5)

Here, R ₈ represents a saturated or unsaturated hydrocarbon group having 8 to 18 carbon atoms, or an aryl group having 6 to 18 carbon atoms.
(Equation 6)

Here, 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.

Specific examples of such thiophosphorous acid compounds or thiophosphate ester compounds (d) include alkylthiophosphorous acid such as trilauryl trithiophosphite; aromatic thiophosphate esters such as triphenyl phosphorothioate; and the like. Among these, the use of alkylthiophosphorous acid can provide a grease composition with better wear resistance and flaking resistance. These compounds can be used alone or in combination.

<Other additives>
The grease composition of the present invention may further contain the following components as optional components: By containing the fatty acid or a metal salt thereof (e) and the amine compound (f), the grease composition of the present invention can obtain better wear resistance and flaking resistance, and when the grease composition contains the fatty acid or a metal salt thereof (e), and the amine compound (f), it can obtain even better wear resistance and flaking resistance.

(Fatty acids or metal salts thereof (e))
The grease composition of the present invention may contain a fatty acid or a metal salt thereof (e). The fatty acid or metal salt thereof (e) according to the present invention is not limited as long as it does not impair the effects of the present invention. As the fatty acid or metal salt thereof according to the present invention, a saturated or unsaturated fatty acid having 4 to 18 carbon atoms or a metal salt thereof is preferably used. When the grease composition of the present invention contains such a fatty acid or a metal salt thereof (e), it is possible to obtain a grease composition having further excellent wear resistance and flaking resistance.

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, pentadecylic acid, palmitic acid, margaric acid, stearic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, linoleic acid, linolenic acid, pinoleic acid, eleostearic acid, stearidonic acid, and bosseopentaenoic acid. These can be used alone or in combination. Among these, unsaturated fatty acids are more preferred than saturated fatty acids in that they are more easily adsorbed onto metal surfaces, resulting in a grease composition with better wear resistance and flaking resistance. Similarly, the larger the carbon number, the more preferred it is. An example of such a fatty acid is oleic acid.

Metal elements that form salts with these fatty acids are not limited as long as they do not impair the effects of the present invention. 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 these, salts of calcium and aluminum are more preferably used since they provide a grease composition with superior wear resistance and flaking resistance.

ここで、Ｒ_４は、炭素数５～１８の、飽和又は不飽和の炭化水素基を示し、Ｒ_５は炭素数２～３の飽和又は不飽和の炭化水素基を示す。 (Amine Compound (f))
The grease composition of the present invention may contain an amine compound (f). The amine compound (f) according to the present invention is not limited as long as it does not impair the effects of the present invention. 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, it is possible to obtain a grease composition having better wear resistance and flaking resistance.
(Equation 2)

Here, R ₄ represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms, and R ₅ represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms.

Specific examples of such amine compounds (f) include 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-butylenediamine, N-tallow alkyl-1,4-butylenediamine, and N-hardened tallow alkyl-1,4-butylenediamine. These can be used alone or in combination. Of these, N-tallow alkyl-1,3-propanediamine is more preferred in that it provides a grease composition with better wear resistance and flaking resistance.

(others)
The grease composition of the present invention can use a thickener other than a urea compound (other thickener) together with the thickener (urea). Examples of such other thickeners include calcium triphosphate, alkali metal soap, alkali metal complex soap, alkaline earth metal soap, alkaline earth metal complex soap, alkali metal sulfonate, alkaline earth metal sulfonate, other metal soap, terephthalamate metal salt, monourea, triurea monourethane, polyurea other than diurea or tetraurea, clay, silica (silicon oxide) such as silica aerogel, fluororesin such as polytetrafluoroethylene, etc., and one or more of these can be used in combination. In addition to these, any other thickener that can impart a viscosity effect to a liquid substance can be used.
In addition, when the fatty acid or its metal salt (e) is used, the fatty acid or its metal salt (e) can be used as a thickener in addition to the fatty acid or its metal salt (e). When the fatty acid or its metal salt (e) is used as a thickener in addition to the fatty acid or its metal salt (e), it can be blended in separately from the amount of the fatty acid or its metal salt (e).

The grease composition of the present invention may further contain antioxidants, rust inhibitors, oiliness agents, extreme pressure agents, antiwear agents, solid lubricants, metal deactivators, polymers, non-metallic detergents, colorants, water repellents, etc., as long as they do not impair the present invention. These may be used alone or in combination.

Examples of antioxidants include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-paracresol, p,p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, and phenothiazine.

Examples of rust inhibitors include paraffin oxide, metal carboxylates, metal sulfonates, carboxylate esters, sulfonate esters, salicylate esters, succinate esters, sorbitan esters, and various amine salts.

Examples of oil agents, extreme pressure agents and anti-wear agents include zinc sulfide dialkyldithiophosphate, zinc sulfide diallyldithiophosphate, zinc sulfide dialkyldithiocarbamate, zinc sulfide diallyldithiocarbamate, molybdenum sulfide dialkyldithiophosphate, molybdenum sulfide diallyldithiophosphate, molybdenum sulfide dialkyldithiocarbamate, molybdenum sulfide diallyldithiocarbamate, organic molybdenum complexes, sulfurized olefins, triphenyl phosphite, triphenyl phosphothionate, tricresin phosphite, other phosphate esters, and sulfurized oils and fats.

Examples of solid lubricants include molybdenum disulfide, graphite, boron nitride, melamine cyanurate, PTFE (polytetrafluoroethylene), tungsten disulfide, and graphite fluoride. For example, metal deactivators include N,N'-disalicylidene-1,2-diaminopropane, benzotriazole, benzimidazole, benzothiazole, and thiadiazole. For example, polymers include polybutene, polyisobutene, polyisobutylene, polyisoprene, and polymethacrylate.

An example of a non-metallic detergent is succinimide.

<<Method for producing grease composition>>
Next, the method for producing the grease composition according to the present embodiment is not particularly limited, and the grease composition can be produced by weighing and mixing each raw material by a known method. Regarding the blending amount of optional components, they can be appropriately blended in the blending amounts described above, if necessary.

The amount of base oil (a) is preferably 70 to 98% by mass, more preferably 75 to 97% by mass, and even more preferably 80 to 95% by mass, based on 100% by mass of the entire grease composition.

The blending amount of the diurea compound (b) according to the present invention can be preferably 1 to 25 mass %, more preferably 3 to 20 mass %, and even more preferably 5 to 15 mass %, based on 100 mass % of the entire grease composition.
Furthermore, when a thickener other than the diurea compound (b) is further added, the total amount of the diurea compound (b) and the thickener other than the diurea compound (b) is preferably 2 to 50 mass %, more preferably 4 to 40 mass %, and even more preferably 6 to 30 mass %, relative to 100 mass % of the entire grease composition.
When the blending amount of the diurea compound (b) is within this range, the grease composition has an appropriate hardness as a grease, is less likely to flow out from the lubricated parts, and has excellent intervention into the lubrication interface, so that the intended lubricating performance can be fully exhibited.

The amount of the amide compound (c) according to the present invention is preferably 0.1 to 10 mass%, more preferably 0.2 to 5 mass%, and even more preferably 0.3 to 3 mass%, based on 100 mass% of the entire grease composition.

The amount of the thiophosphorous acid compound or thiophosphate ester compound (d) according to the present invention is preferably 0.1 to 10 mass%, more preferably 0.2 to 5 mass%, and even more preferably 0.3 to 3 mass%, based on 100 mass% of the entire grease composition.

The amount of the fatty acid or its metal salt (e) according to the present invention is preferably 0.1 to 10 mass%, more preferably 0.2 to 5 mass%, and even more preferably 0.3 to 3 mass%, based on 100 mass% of the entire grease composition.

The amount of the amine compound (f) according to the present invention is preferably 0.1 to 10 mass%, more preferably 0.2 to 5 mass%, and even more preferably 0.3 to 3 mass%, based on 100 mass% of the entire grease composition.

The amount of other additives to be blended can be about 0.1 to 20 parts by mass of any of the components combined, based on 100 parts by mass of the entire grease composition.

<<Physical properties of grease composition>>
<Consistency>
The grease composition of the present invention has a consistency range of No. 2 to No. 0 (265 to 385), preferably No. 4 to No. 00 (175 to 430), more preferably No. 3 to No. 0 (220 to 385), and even more preferably No. 2 to No. 1 (265 to 340). The consistency indicates the physical hardness of the grease. The consistency can be measured according to JIS K2220 7 "Grease consistency test method".

<Dropping point>
Although the grease composition of the present invention has no relation to the performance at the dropping point, it is preferable that the dropping point is equal to or higher than 180°C as an index that the thickener structure of the urea grease has reached the original bond. The dropping point is the temperature at which a viscous grease loses its thickener structure as the temperature is increased. The dropping point can be measured in accordance with JIS K2220 8 "Grease Dropping Point Test Method".

<<Applications of grease composition>>
The grease composition of the present invention can be used for machines, bearings, gears, ball screws, etc. that are generally used, and can also exhibit excellent performance under harsh environments for grease lubrication. For example, in automobiles, it can be suitably used for lubrication of various parts such as water pumps, cooling fan motors, starters, alternators, and engine peripheries of various actuators, propeller shafts, constant velocity joints (CVJs), wheel bearings, and clutches in power trains, electric power steering (EPS), electric power windows, braking devices, ball joints, door hinges, handlebars, and brake expanders. Furthermore, it is also suitable for use in various shafts and fittings that may slide back and forth in construction machines such as power shovels, bulldozers, and cranes, the steel industry, the paper industry, forestry machines, agricultural machines, chemical plants, power generation facilities, and railroad cars. Other applications include screw joints in seamless pipes and bearings in outboard motors, and it is also suitable for these applications.

The present invention will be described in more detail below with reference to examples, reference examples, and comparative examples, but the present invention is not limited to these examples in any way.

<<Production of Grease Composition>>
<Ingredients>
The abbreviations for 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 kinetic viscosity of 99.05 mm ² /s at 40°C and 11.13 mm ² /s at 100°C. Base oil B: mineral oil having a kinetic viscosity of 480.2 mm ² /s at 40°C and 31.56 mm ² /s at 100°C.
Base oil C: a highly refined oil having a kinetic viscosity at 40°C of 43.88 mm ² /s, a kinetic 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: poly-α-olefin oil having a kinetic viscosity of 396.5.3 mm ² /s at 40°C and 39.99 mm ² /s at 100°C. Base oil E: alkyl diphenyl ether oil having a kinetic viscosity of 102.2 mm ² /s at 40°C and 12.64 mm ² /s at 100°C (diurea compound (b)).
The diurea compound (b) was prepared by reacting the following raw materials using the production method described below.
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 (Armoslip 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 compound A: Triphenyl phosphorothioate (Irgalube TPPT manufactured by BASF)
(Fatty acids or metal salts thereof (e))
Fatty acid A: Oleic acid (NOF NAA-35)
Fatty acid metal salt A: Calcium stearate (NOF Calcium Stearate GP)
Fatty acid metal salt B: Aluminum stearate (NOF Aluminum Stearate 300)
(Amine Compound (f))
Amine compound A: N-tallow alkyl-1,3-propanediamine (Lipomin DA-T, manufactured by Lion).

<Reference Example 1>
The base oil and MDI were heated in a kettle to dissolve the contents, and then the raw material of octylamine, oleylamine, and base oil mixed and dissolved was added and reacted to synthesize diurea compound A. The mixture was further heated to 170°C while stirring, and the temperature was maintained for about 30 minutes to complete the reaction. After that, the mixture was quickly cooled, and during the cooling process, various additives were added in the blending ratios shown in Table 1, stirred and mixed, and cooled to 80°C, and then processed with a homogenizer to obtain grease.

<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 prepared by changing the raw materials of diurea compound A to the raw materials described above.

<<Evaluation of Grease Composition>>
In order to compare the properties and performance of each of the Examples, Reference Examples, and Comparative Examples, the following measurements and tests were carried out.

<Consistency>
The worked and unworked penetrations of the grease compositions of the Examples, Reference Examples and Comparative Examples were measured in accordance with "Grease Penetration Test Method" of JIS K2220 7. The results are shown in Table 1.

<Dropping point>
The dropping point of each of the grease compositions of the Examples, Reference Examples, and Comparative Examples was measured in accordance with JIS K2220 8 "Grease Dropping Point Test Method." The results are shown in Table 1.

<Bearing peeling wear test>
The grease compositions of the Examples, Reference Examples, and Comparative Examples were evaluated for wear resistance and flaking resistance by a bearing abrasion wear test. The results are shown in Table 1. The evaluation method is as follows. Figure 1 is a diagram showing an outline of the bearing abrasion wear tester.
The weight of a clean test rolling bearing (7205 type angular contact ball bearing) was measured in advance, and the bearing was filled with 3 g of the grease composition and mounted on a bearing peeling wear test device. After that, the nut of the rocking shaft was fixed with a tightening torque of 600 kg m, and a thrust load was applied to the shaft with the tightening torque. Next, a radial load of 1.0 ton per bearing was applied by a hydraulic piston. The motor was started, and the rocking shaft was reciprocated at 1.7 Hz. After 20 hours of rocking operation, the bearing was removed from the device and washed with a solvent such as n-hexane to thoroughly remove the grease composition. The weight of the clean bearing after the test was measured, and the weight difference from the weight of the bearing before the test was calculated to be the bearing wear amount.
After the test, the amount of bearing wear and the area of flaking on the sliding surfaces of the inner and outer rings were measured and evaluated. Pass/fail was determined based on the total area of flaking, with a pass of less than ⁵⁰ mm2 and a fail of more than 50 mm2. The area of flaking was measured by observing and identifying the areas where flaking had occurred using a digital microscope (Keyence VHX-6000) and then measuring the area.
(Test condition)
Test bearing: No. 7205 (angular contact ball bearing)
Grease filling amount: 3.0g
Oscillation: 1.7Hz
Thrust load: 600 kg m
Radial load: 1.0 ton Temperature: 25°C
Duration: 20 hours

<Evaluation Results>
The properties of each grease obtained are shown in Table 1.
The consistency of the greases in the examples is from No. 0 to No. 2, and the consistency of the greases in the comparative examples is from No. 2 to No. 2.5. The dropping points of both the greases in the examples and the comparative examples are 240° C. or higher, which is a comparable value for a urea grease.
In the bearing abrasion wear test, which is the most important in the present invention, all of the greases according to the examples achieved wear resistance with the bearing wear amount being less than 150 mg, and the flaking occurrence area was less than ⁵⁰ mm2, and were judged to pass. On the other hand, the greases according to the comparative examples showed a lot of bearing wear after the bearing abrasion wear test, and the flaking occurrence area on the sliding surfaces of both the inner and outer rings exceeded ⁵⁰ mm2, and were judged to fail.

1 Motor 2 Rotating shaft 3 Crank arm (1)
4 Strain gauge 5 Crank bend 6 Crank arm (2)
7 Fit retaining nut 8 Key material 9 Conical fit portion 10 Nut 11 Collar 12 Bearing retaining block 13 Test rolling bearing 14 Bearing unit 15 Load control device 16 Auxiliary rolling bearing 17 Swing shaft

Claims (5)

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:
(Equation 1)

(wherein _R1 and _R3 represent a non-cyclic aliphatic hydrocarbon group having 8 to 20 carbon atoms, and _R2 represents a diphenylmethane group).
(Equation 2)

(wherein R ₄ represents a saturated or unsaturated hydrocarbon group having 5 to 18 carbon atoms, and R ₅ represents a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms). The grease composition according to claim 1, characterized in that the diurea compound (b) contains a diurea compound (b) in which R ₁ and R ₃ in formula 1 are either a non-cyclic aliphatic hydrocarbon group having 8 to 12 carbon atoms or a non-cyclic aliphatic hydrocarbon group having 14 to 20 carbon atoms. The grease composition according to claim 1 or 2, characterized in that it contains (e) a saturated or unsaturated fatty acid having 4 to 18 carbon atoms or a metal salt thereof. 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:
(Equation 3)

(Equation 4)

(wherein R ₆ represents a saturated or unsaturated hydrocarbon group having 15 to 17 carbon atoms, and R ₇ represents a methylene group or an ethylene group). 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:
(Equation 6)

(wherein 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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