JPH10158673A - Grease composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grease composition which can impart excellent load- withstanding properties and extreme pressure properties to the area to which it is applied and can show a prolonged life of lubrication even when used at high temperatures by adding a sulfonamide derivative to a grease composition containing a base oil and a thickening agent. SOLUTION: 0.1-8wt.%, based on the entire weight of the grease, sulfonamide derivative, desirably one represented by the formula (R and R' are each a 6-18 C aryl, desirably phenyl or tolyl) is added to a grease composition prepared by mixing a base oil comprising a mineral oil usually used for grease, a synthetic oil usually used for grease or a mixture thereof with 5-35wt.% thickener such as a metal soap, a compound metal soap, a urea compound, an inorganic compound or the like. The obtained composition may optionally mixed with various conventional known additives (such as an extreme pressure additive, an antioxidant, a rust preventive, a metal inactivator or an oiliness improver).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition sealed in a rolling bearing incorporated in various industrial machines and vehicles, and more particularly to a grease composition suitable for a rolling bearing used at high temperature and high speed rotation.

[0002]

2. Description of the Related Art A grease composition is sealed in a rolling bearing incorporated in various industrial machines, vehicles and the like in order to impart lubricity. The grease composition is obtained by kneading a base oil and a thickener, and the base oil is a synthetic lubricating oil such as a mineral oil, an ester oil, a silicone oil, or an ether oil, and the thickener is a lithium soap. Metal soaps and urea compounds are generally used. In recent years, rolling bearings tend to be used at high speed rotation, and accordingly, grease compositions are required to have high temperature resistance. However,
When metal soap is used as a thickener, for example, 13
At a high temperature of 0 ° C. or higher, the metal acts as a catalyst to promote oxidation of the base oil and reduce the lubricating action. As for the base oil, a grease composition using a mineral oil as a base oil tends to be oxidized more easily than a grease composition using a synthetic lubricating oil as a base oil, and the lubrication life at high temperatures tends to be shorter. Therefore, in recent years, grease compositions using a synthetic lubricating oil as a base oil and a urea compound as a thickener have become mainstream for rolling bearings used particularly at high temperatures and high speed rotation.

[0003]

On the other hand, recently, in consideration of maintenance costs, it is desired that the grease composition can be used once over a long period after being applied once. In addition, the use conditions tend to become more severe with the miniaturization and high performance of the various mechanical members mentioned above, and accordingly, further lubrication performance and lubrication life are required for the grease composition. In particular, the demand for longer life at high temperatures is one of the most important issues for bearing manufacturers. In response to such demands, a measure is usually taken to add an antioxidant, a rust preventive or the like to the grease composition, but the effect has not yet been sufficiently obtained.
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a grease composition that prolongs the lubricating life of an application point particularly when used at a high temperature.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, by adding a sulfonamide derivative to a grease composition, the lubricating life at high temperatures can be greatly increased. They have found that they can be improved, and have completed the present invention. That is, the above object is achieved by the grease composition according to the present invention, comprising a base oil and a thickener, further comprising a sulfonamide derivative.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the grease composition of the present invention will be described in detail. As the base oil used in the present invention, a mineral oil, a synthetic oil, or a mixed oil thereof which is usually used for grease can be used. Specifically, mineral oils include paraffinic mineral oils and naphthenic mineral oils.Synthetic hydrocarbon oils include poly-α-olefin oils, and ether oils include dialkyl diphenyl ether oils, alkyl triphenyl ether oils, and the like. Alkyl tetraphenyl ether oils and the like, and ester oils include diester oils, polyol ester oils, and complex ester oils and aromatic ester oils thereof. Above all, in consideration of lubricating performance at high temperature and high speed and lubrication life, it is desirable to contain a synthetic oil, and particularly desirable to contain an ester oil and an ether oil.

[0006] Thickeners are not particularly limited, either.
For example, metal soaps such as aluminum, barium, calcium, lithium, and sodium, complex metal soaps such as lithium complex, calcium complex, and aluminum complex, urea compounds such as diurea, triurea, tetraurea, and polyurea, or inorganic compounds such as silica gel and bentonite Compounds, urethane compounds, urea / urethane compounds, sodium terephthalamate compounds and the like can be used as appropriate. By using a urea compound having excellent oxidation stability, the lubricating performance and lubricating life at high temperature and high speed rotation can be further improved. The amount of the thickener is usually 5 to 35% by weight.
It is.

The present invention is characterized in that a grease composition comprising the above base oil and a thickener contains a sulfonamide derivative. The sulfonamide derivative is not particularly limited, but is preferably one represented by the following general formula.

[0008]

Embedded image

In the formula, R and R 'are aryl groups having 6 to 18 carbon atoms, which may be the same or different. Preferably, a phenyl group, a tolyl group, an ethylphenyl group,
Isopropylphenyl group, tert-butylphenyl group, se
Examples thereof include a c-pentylphenyl group, an n-hexylphenyl group, a tertiary octylphenyl group, an isononylphenyl group, an n-dodecylphenyl group, and particularly preferred are a phenyl group and a tolyl group.

The content of these sulfonamide derivatives is as follows:
It is preferably from 0.1 to 8% by weight, especially from 0.5 to 6% by weight of the total amount of grease. If the content is less than 0.1% by weight, the effect of the present invention cannot be sufficiently obtained. On the other hand, 8% by weight
When the amount exceeds, not only the effect corresponding to the increase of the content cannot be expected, but also the sulfonamide derivative aggregates in the grease, which may cause an undesirable phenomenon such as an increase in torque.

The grease composition of the present invention comprises the above base oil,
Although a thickener and a sulfonamide derivative are essential components, the following additives, which are conventionally added to a grease composition, can be added. [Extreme pressure agent] By using a conventionally known extreme pressure agent together, the load resistance and the extreme pressure property can be improved. For example, the following compounds can be used. Examples of organometallic compounds include molybdenum dithiocarbamate, organic molybdenum compounds such as molybdenum dithiophosphate, zinc dithiocarbamate, zinc dithiophosphate, organic zinc compounds such as zinc phenate, antimony dithiocarbamate, and antimony compounds such as antimony dithiophosphate; Organic selenium compounds such as selenium dithiocarbamate; organic bismuth compounds such as bismuth naphthenate and bismuth dithiocarbamate; organic iron compounds such as iron dithiocarbamate and iron octylate; organic copper compounds such as copper dithiocarbamate and copper naphthenate; naphthenic acid Organic lead compounds such as lead and lead dithiocarbamate; organotin compounds such as tin maleate and dibutyltin sulfide; or organic sulfonates, phenates and phosphates of alkali metals and alkaline earth metals Sulfonates, gold, silver, titanium, an organometallic compound such as cadmium can also be used if necessary. As the sulfur compound, sulfides such as dibenzyl disulfide or polysulfide compounds, sulfurized oils and fats, ashless carbamic acid compounds, thiourea compounds, thiocarbonates and the like can be used. As the phosphoric acid extreme pressure agent, a phosphoric ester compound such as a phosphoric ester such as trioctyl phosphate and tricresyl phosphate, an acidic phosphoric ester, a phosphite, an acidic phosphite is used. be able to. In addition, halogen-based extreme pressure agents such as chlorinated paraffin, molybdenum disulfide, tungsten disulfide, graphite, PTF
Solid lubricants such as boron compounds such as E, antimony sulfide, and boron nitride can be used. Among these extreme pressure agents, dithiocarbamic acid compounds and dithiophosphoric acid compounds can be suitably used.

[Antioxidant] As the antioxidant, an antioxidant, an ozone deterioration inhibitor and an antioxidant which are added to rubber, plastic, lubricating oil and the like can be appropriately selected and used. For example, the following compounds can be used. That is, phenyl-1-naphthylamine, phenyl-
2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-
Amine compounds such as dioctylphenothiazine, p, p'-dioctyldiphenylamine, N, N'-diisopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine; 2,6-di- t
Phenol compounds such as ert-dibutylphenol can be used.

[Rust Inhibitor / Metal Deactivator] As the rust inhibitor, for example, the following compounds can be used. That is, an ammonium salt of an organic sulfonic acid, an alkali metal such as barium, zinc, calcium, or magnesium, an organic sulfonate or an organic carboxylate of an alkaline earth metal, a phenate, a phosphonate, or an alkyl or alkenyl such as an alkyl or alkenyl succinate. Succinic acid derivatives, partial esters of polyhydric alcohols such as sorbitan monooleate, hydroxy fatty acids such as oleoyl sarcosine, mercapto fatty acids such as 1-mercaptostearic acid or metal salts thereof, higher fatty acids such as stearic acid, Higher alcohols such as isostearyl alcohol, esters of higher alcohols and higher fatty acids, 2,5
Thiazoles such as dimercapto-1,3,4-thiadiazole and 2-mercaptothiadiazole, imidazole compounds such as 2- (decyldithio) -benzimidazole and benzimidazole, or 2,5-bis (dodecyldithio) benzimidazole Or a phosphoric acid ester such as trisnonylphenyl phosphite, a thiocarboxylic acid ester compound such as dilauryl thiopropionate, or the like. Further, nitrite and the like can also be used. As the metal deactivator, for example, a triazole-based compound such as benzotriazole or tolyltriazole can be used.

[Oiling agent] As the oiling agent, for example, the following compounds can be used. That is, fatty acids such as oleic acid and stearic acid, fatty acid alcohols such as oleyl alcohol, fatty acid esters such as polyoxyethylene stearic acid ester and polyglyceryl oleate, phosphoric acid, tricresyl phosphate, lauric acid ester and polyoxyethylene oleyl. Phosphate esters such as ether phosphoric acid can be used.

The grease composition of the present invention can be further clarified by the following examples. However, the present invention is not limited at all by these examples. (Examples 1 to 5 and Comparative Examples 1 to 5) As shown in Tables 1 and 2, a thickener and a base oil were selected to adjust the base grease. Was blended. The amount of the thickener was finally adjusted to be 10% by weight in the grease. For comparison, a commercially available urea-based high temperature grease was also used. In addition, 1% by weight of zinc sulphonate was added as a rust preventive to the base greases of all Examples and Comparative Examples except for the commercially available products. Was blended. For each of the above greases, the life up to seizure was evaluated using a 6305 type bearing life tester. The test method and test conditions are as follows. That is, rolling bearings (call number:
6305VVC3E), 2.8 g of each test grease is filled, the outer diameter of the bearing outer ring is 170 ° C, and the radial load is 10k.
gf, 3500 rpm under an axial load of 10 kgf
At a high speed, and the time until burning was measured. The test results are also shown in Table 1.

[0016]

[Table 1]

[0017]

[Table 2]

From Tables 1 and 2, it can be seen that the greases of the examples have much better seizure life than the grease of the comparative example and the commercially available grease for high temperature.

[0019]

As described above, the lubricant composition of the present invention contains a specific ashless sulfur compound, so that the applied portion has much higher load carrying capacity and extreme pressure property than the conventional one. Can be granted.

Claims (1)

[Claims] 1. A grease composition comprising a base oil and a thickener, wherein the grease composition further comprises a sulfonamide derivative.