KR20140129350A - Grease composition - Google Patents

Abstract

The present invention provides a grease composition having a high lubricity, particularly excellent abrasion resistance, and having little deterioration in abrasion resistance when used at high temperature for a long time. An amide compound, a solid lubricant and a urea-based thickener selected from the group consisting of a mineral oil and a synthetic lubricating base oil, and the amide compound is heated and melted at least once with the base oil.

Description

Grease composition {GREASE COMPOSITION}

The present invention relates to a grease composition using a urea thickener.

Greases are mainly used for sliding surfaces, sliding surfaces, rolling bearings, or sliding surfaces where it is difficult to maintain a film of lubricant attached due to the movement of the contact surface. Among them, so-called urea grease using a urea thickener Mechanical stability and heat resistance, it is widely used among metal sliding members of low speed but high load, for example, constant velocity joints of automobiles.

As such a grease composition for constant velocity joints, it has been proposed that an organic molybdenum compound such as base oil, dialkyldithiocarbamic acid molybdenum sulfide, molybdenum disulfide, a zinc dithiophosphate compound and an aliphatic amide are disclosed (Patent Documents 1 to 3).

However, the grease composition is insufficient in terms of lubricity, in particular, in abrasion resistance, and further, there is a problem that abrasion resistance is deteriorated in use for a long time at a high temperature.

Japanese Patent Application Laid-Open No. 2001-11481 Japanese Patent Application Laid-Open No. 2005-226038 Japanese Patent Application Laid-Open No. 2008-19288

A problem to be solved by the present invention is to provide a grease composition which has a high lubricity and is excellent in wear resistance, and which hardly deteriorates in abrasion resistance at a high temperature for a long time.

As a result of carrying out intensive studies in order to solve the above problems, the present inventors have found that when an amide compound is heated and melted in the presence of a lubricating base oil in comparison with a state in which amide compound powder is simply dispersed and mixed in grease, The lubricating oil base oil is retained in the amide compound and the abrasion resistance is remarkably improved and it is possible to obtain a grease composition which hardly deteriorates in abrasion resistance even at a high temperature for a long time.

The present invention has been made based on this finding, and includes the following.

(1) A grease composition comprising at least one base oil, amide compound, solid lubricant and urea thickener selected from a mineral oil base and a synthetic base oil base oil, wherein the amide compound is heated and melted at least once with the base oil .

(2) The grease composition according to the above (1), wherein the lubricating base oil of the optical oil system and the synthetic system has a kinematic viscosity at 40 DEG C of 1 to 1000 mm2 / s.

(3) The grease composition according to the above (1) or (2), wherein the amide compound has an alkyl group having 6 to 24 carbon atoms.

(4) The grease composition according to any one of (1) to (3), wherein the solid lubricant is at least one of melamine cyanurate, polytetrafluoroethylene and boron nitride.

(5) The grease composition according to any one of (1) to (4), wherein the urea-based thickener comprises at least one of an aliphatic diurea compound, an alicyclic diurea compound and an aromatic diurea compound.

(6) The grease composition according to any one of (1) to (5), which is used for lubricating the sliding members made of metal.

(7) A process for producing a grease composition comprising at least one base oil, an amide compound, a solid lubricant and a urea-based thickening agent selected from a mineral oil base and a synthetic base oil base oil, wherein at least the amide compound is contained in the base oil, And the mixture is heated and melted.

The grease composition of the present invention has excellent water resistance, mechanical stability, and heat resistance, and is excellent in abrasion resistance at a low speed and at a sliding portion between high-load metals, and is not remarkable in that abrasion resistance is not lowered in long- It is effective.

The grease composition of the present invention comprises a lubricating base oil, an amide compound, a solid lubricant and a urea thickener.

[Lubricating oil base oil]

As the lubricating base oil of the present invention, either a mineral oil system or a synthetic oil system can be used, but the kinematic viscosity at 40 캜 is preferably 1 to 1000 mm 2 / s, more preferably 20 to 300 mm 2 / s. If the kinematic viscosity at 40 DEG C deviates from 1 to 1000 mm < 2 > / s, it becomes difficult to easily produce a grease composition having a desired viscosity.

The lubricant base oil preferably has a density of 0.75 to 0.95 g / cm 3 at 15 캜 because of the high dispersibility of the solid lubricant. In order to produce a grease having excellent lubricity, the lubricant has a viscosity index of 90 or more, 250, a pour point of -10 占 폚 or lower, particularly -15 to -70 占 폚, and a flash point of 150 占 폚 or higher.

Examples of the mineral oil-based lubricating oil base oil include lubricating oil fractions obtained by purifying the distillate obtained by atmospheric distillation or further distillation of crude oil by various purification steps. The purification process includes hydrogenation purification, solvent extraction, solvent dewaxing, hydrogenation dewaxing, sulfuric acid cleaning, white soil treatment and the like, and they can be treated in a suitable order to obtain the base oil of the present invention. Mixtures of a plurality of refined oils differing in properties, obtained by a combination of different processes for different crude oils or effluents, in sequence, are also useful. By any method, the properties of the obtained base oil can be suitably used by adjusting to satisfy the above-mentioned physical properties.

As the synthetic base oil base oil, it is preferable to use a base material having excellent hydrolytic stability, and examples thereof include polyolefins such as poly-alpha -olefin, polybutene and copolymers of two or more kinds of various olefins, polyesters, polyalkylene glycols, Alkylbenzene, alkylnaphthalene, and the like. Among them, poly-alpha-olefins are preferable in terms of availability, cost, viscosity, oxidation stability, and compatibility with system members. The poly-a-olefin is more preferably a polymer in the form of 1-dodecene or 1-decene.

As the lubricant base oil, the exemplified synthetic systems may be used alone or in combination of two or more. It may also be used in combination with the above-mentioned optical oil system.

In the case of using a mixture of a plurality of lubricating base oils including a synthetic base oil, the individual base oils before mixing can be used even if they exceed the physical properties, provided that the base oil mixture satisfies the above properties. Therefore, it is not necessary for each synthetic synthetic base oil to satisfy the above physical properties, but it is preferable that the synthetic base oils are within the range of the physical properties described above.

The content of the lubricating base oil is preferably 50 to 95 mass%, more preferably 60 to 85 mass%, based on the whole amount of the grease composition. If the content of the lubricating base oil is out of the range of 50 to 95 mass%, it becomes difficult to easily produce a grease composition having a desired viscosity.

[Amide compound]

The amide compound to be used in the present invention is a monoamide having one amide group (-NH-CO-), bisamide having two amides, triamide having three amides, etc., and bisamide or triamide having a relatively small amount So that the frictional resistance in the east portion can be reduced.

The bisamide may be an acid amide of a diamine or an acid amide of a diacid.

The amide compound preferably used has a melting point of 40 to 180 캜, particularly preferably 80 to 180 캜, more preferably 100 to 170 캜, and a molecular weight of 242 to 932, particularly preferably 298 to 876.

Monoamides, bisamides and triamides are represented by the following formulas (1), (2), (3) and (4), respectively.

In the above formulas, R ¹ , R ² , and R ³ are each independently a hydrocarbon group having 5 to 25 carbon atoms, and may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. In the case of formula (1), R ² is hydrogen. A ¹ , A ² and A ³ are each independently a divalent hydrocarbon group of 1 to 10 carbon atoms, which is an aliphatic hydrocarbon group, alicyclic hydrocarbon group or aromatic hydrocarbon group having 1 to 10 carbon atoms, or a combination thereof, M is Amide group.

In the case of the monoamide, it is preferable that R ² is hydrogen or a saturated or unsaturated chain hydrocarbon group having 10 to 20 carbon atoms.

In the case of the acid amide of diamine, it is preferable that A ¹ is a divalent saturated chain hydrocarbon group having 1 to 4 carbon atoms.

In the formulas (2) and (3), a hydrocarbon group represented by R ¹ , R ² or A ¹ may have a part of hydrogen substituted with a hydroxyl group (-OH).

In the present specification, A ^1, A ² and A ³ is called an aliphatic hydrocarbon group, amide compound, an aliphatic amide that is, A ^1, A ² or A ³ is at least one aromatic polyamide of an aromatic hydrocarbon group, an amide compound of, A ¹ , And an amide compound in which at least one of A ² and A ³ is an alicyclic hydrocarbon group or an aromatic hydrocarbon group is referred to as a non-aliphatic amide.

In the case of an aliphatic amide, it is preferable that R ¹ , R ² and R ³ are saturated or unsaturated chain hydrocarbon groups having 10 to 20 carbon atoms.

In the case of an aromatic amide, it is preferable that R ¹ , R ² , and R ³ are a saturated hydrocarbon group or an unsaturated chain hydrocarbon group having 10 to 20 carbon atoms and an aromatic hydrocarbon group.

As the amide compound, a non-aliphatic amide can be used, but an aliphatic amide is preferable. In the case of the acid amide of the diamine (Formula 3), it is preferable that A ¹ is a divalent saturated saturated hydrocarbon group having 1 to 4 carbon atoms.

Specific examples of the monoamide include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide and hydroxystearic acid amide; unsaturated fatty acid amides such as oleic acid amide and erucic acid amide; Saturated or unsaturated long chain fatty acids such as stearic acid amide, oleyl oleic acid amide, oleyl stearic acid amide and stearyl oleic acid amide, and substituted amides by long chain amines.

Specific examples of the acid amide of the diamine represented by the formula (2) include ethylenebisstearic acid amide, ethylenebisisostearic acid amide, ethylenebisoleic acid amide, methylenebislauric acid amide, hexamethylenebisoleic acid amide, hexamethylenebishydroxystear Acid amides and the like. Specific examples of the bisamides of diacids represented by the formula (3) include N, N'-bistostearyl sebacate amide and the like.

Among these bisamides, it is preferable that R ¹ and R ² in formulas (2) and (3) are each independently an amide compound of a saturated chain hydrocarbon group or unsaturated chain hydrocarbon group having 12 to 20 carbon atoms.

There are a number of triamides represented by the formula (4), but specific examples of the compounds usable in the present invention include N-acyl amino acid diamide compounds. The N-acyl group of the compound includes a linear or branched, saturated or unsaturated aliphatic acyl group or aromatic acyl group having 1 to 30 carbon atoms, particularly a caproyl group, a caprylyl group, a lauroyl group, a myristoyl group, And the amide group is preferably a linear or branched saturated or unsaturated aliphatic amine having 1 to 30 carbon atoms, especially butylamine, octylamine, laurylamine, Isostearylamine, stearylamine and the like are preferable. In particular, N-lauroyl-L-glutamic acid-α, γ-di-n-butylamide is preferable as a specific compound.

These amide compounds may be used alone or in combination of two or more. The content of the amide is preferably 0.1 to 50 mass%, more preferably 3 to 35 mass%, based on the whole amount of the grease composition.

[Solid lubricant]

The solid lubricant is not particularly limited as long as it is generally used in a lubricant, but it is preferable to use a layered compound or fluororesin having excellent lubricity.

As the layered compound, a compound having a layered crystal structure such as melamine cyanurate, boron nitride, graphite, mica, graphite fluoride and the like is suitable. Further, a compound containing heavy metals or sulfur is not preferable in view of environmental pollution and the like.

Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene Ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE) and the like are suitable.

These solid lubricants may be used singly or in combination of two or more, and may be suitably selected from those having appropriate particle diameters depending on the intended use, and preferably have a particle diameter of 0.2 to 50 탆, particularly 1 to 10 탆.

The content of the solid lubricant is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, based on the total amount of the grease composition.

[Urea thickener]

As the urea thickener, for example, a diurea compound obtained by a reaction of a diisocyanate with a monoamine or a polyurea compound obtained by a reaction of a diisocyanate with a monoamine or a diamine can be used.

As the diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate and the like are preferable. As the monoamine, octylamine, dodecyl Preferred examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, p-toluenesulfonylamine, , Tolylene diamine, xylenediamine, diaminodiphenylmethane and the like are preferable.

The urea-based thickener may be one type or a mixture of plural types. The content of the thickener is not particularly limited as long as a desired viscosity can be obtained, and is preferably 2 to 30 mass%, more preferably 5 to 20 mass%, based on the total amount of the grease composition.

[Other additives]

The grease composition of the present invention may contain additives such as a detergent, a dispersing agent, a wear inhibitor, a viscosity index improver, an antioxidant, an extreme pressure agent, a rust inhibitor and a corrosion inhibitor which are generally used in lubricating oil or grease Can be added.

[Manufacturing method]

The grease composition of the present invention can be produced by a general grease production method, but it is preferable to heat the mixture at a temperature not lower than its melting point after mixing the amide compound.

That is, the amide compound and the lubricant base oil may be heated to a temperature not lower than the melting point of the amide compound and cooled, and then physically mixed with a general grease containing a solid lubricant, a thickener and a lubricant base oil. The components may be mixed and then heated to a temperature not lower than the melting point of the amide compound and cooled.

By heating the amide compound at least above the melting point of the amide compound in the presence of at least a lubricating base oil, the liquid lubricating base oil is retained in the amide compound forming the three-dimensional network structure to form a semi-solid phase gel. The lubricating base oil is moving freely in and around the reticular structure. This indicates that, for example, a liquid lubricant base in the gel can move from the gel to fine voids by capillary action when a composition having a gel state lubricity contacts porous fine pores, or vice versa, The three-dimensional structure of the gel becomes a capillary phenomenon, indicating that these extra liquid lubricant base oils are introduced into the gel. In this state, the viscosity is imparted by the urea-based thickener, and the effect that the abrasion resistance is not deteriorated in the long-term use at a high temperature besides the excellent water resistance, the mechanical stability and the heat resistance is remarkably excellent do.

<Examples>

1. Lubricant base oil

(1) mineral oil system

· Lubricant base oil obtained by solvent refining the effluent obtained by vacuum distillation of the atmospheric distillation residue

Kinematic viscosity at 40 占 폚; 68 mm2 / s

Density at 15 캜; 0.87 g / cm3

Viscosity index; 100

Pour point; -10 ° C

flash point; 250 ℃

(2) Synthetic system

Poly? -Olefin (Durasyn 170 manufactured by INEOS)

Kinematic viscosity at 40 占 폚; 68 mm2 / s

Density at 15 占 폚: 0.83 g / cm3

Viscosity index; 133

Pour point; -45 ° C

flash point; 250 ℃

2. Amide compounds

2-1. Aliphatic amide

(1) Ethylene bisstearic acid amide (exclusive reagent)

(2) Ethylene bisoleate amide (exclusive reagent)

(3) Stearammonoamid (fast reagent)

2-2. Aromatic amide

(1) m-xylylene bisstearic acid amide (exclusive reagent)

3. Solid lubricant

(1) melamine cyanurate (MCA, average particle diameter: 4 탆, MELAPUR MC25 manufactured by BASF)

(2) Polytetrafluoroethylene (PTFE, average particle size: 4 탆, KTL-8N manufactured by Kita-Kohmura Co., Ltd.)

(3) Boron nitride (average particle size: 2 탆, HP-P1 manufactured by Mizushima Kogyo Kintetsu)

The average particle diameter is measured by a laser diffraction method.

4. Urea thickener

(1) an aliphatic diurea comprising octadecylamine and methylene diphenyl diisocyanate

(2) alicyclic diureas including cyclohexylamine and methylenediphenyl diisocyanate

(3) aromatic diurea comprising p-toluidine and methylenediphenyl diisocyanate

5. Other additives

Diphenylamine was added to all as an antioxidant.

[Manufacturing method]

Each component was put into a container in a mixing amount (expressed in terms of% by weight) shown in Tables 1 and 2, heated to 150 ° C (melting point of the amide compound or higher), stirred with a magnetic stirring bar and cooled to room temperature. This was subjected to pressure dispersion treatment with a roller (three-axis roll) to prepare a grease composition.

For Comparative Example 7, the compounding amount shown in Table 2 was subjected to pressure dispersion treatment with a direct roller (triaxial roll) without heating and cooling to prepare a grease composition.

[Evaluation test]

A FALEX tester of a pin-vee block was used and a load of 350 lbf was applied for 15 minutes to evaluate the wear of the test piece. In order to evaluate the performance when grease was used under severe conditions as well as new oil, the grease was allowed to stand for 100 hours and 500 hours under an environment of 150 ° C, forcibly deteriorated, and the same FALEX test was carried out .

〔Evaluation results〕

When the mineral oil and the urea-based thickener were blended, the wear amount of the new oil was about 7 mg, but the wear amount of the degraded oil was particularly large (Comparative Example 6).

When the mineral oil and the urea thickener were mixed with the solid lubricant, the abrasion loss of the new oil was slightly reduced, but the abrasion loss of the degradation oil was large (Comparative Examples 1 to 5).

In the case where the aliphatic amide was not heated or melted, the abrasion amount of both the new oil and the deteriorated oil was large (Comparative Example 7).

When the mineral oil and the urea thickener, the solid lubricant and the aliphatic amide were blended, the worn amount of both the new oil and the deteriorated oil was greatly reduced (Examples 1 to 9).

The grease composition of the present invention has excellent water resistance, mechanical stability, and heat resistance, and is excellent in abrasion resistance at low speed and high load metal sliding portions, and does not deteriorate abrasion resistance when used at high temperature for a long time. The present invention can be applied to lubrication of various joints, gears, bearings, etc. having sliding portions between metals.

Claims (7)

An amide compound, a solid lubricant and a urea-based thickener selected from the group consisting of a mineral oil and a synthetic lubricating oil base oil, wherein the amide compound is heated and melted at least once with the base oil. The grease composition according to claim 1, wherein the lubricating base oil of the mineral oil system and the synthetic oil system has a kinematic viscosity at 40 DEG C of 1 to 1000 mm &lt; 2 &gt; / s. The grease composition according to claim 1 or 2, wherein the amide compound has an alkyl group having 6 to 24 carbon atoms. 4. The grease composition according to any one of claims 1 to 3, wherein the solid lubricant is at least one of melamine cyanurate, polytetrafluoroethylene, and boron nitride. The grease composition according to any one of claims 1 to 4, wherein the urea thickener comprises at least one of an aliphatic diurea compound, an alicyclic diurea compound, and an aromatic diurea compound. The grease composition according to any one of claims 1 to 5, which is used for lubricating metal sliding members. A solid lubricant and a urea-based thickener to at least one base oil selected from the group consisting of a mineral oil base oil and a synthetic base oil base oil, wherein the base oil contains at least the amide compound, Wherein the amide compound is melted.