JPH10140174A - Lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant compsn. which can impart excellent load-bearing and extreme-pressure properties to a part to which it is applied by incorporating an ashless sulfur compd. having a heteroatom other than sulfur into the same. SOLUTION: Any ashless sulfur compd. can be used if it has a hetroatom other than sulfur and has no metal atom. The compd. pref. has a polysulfide group, a dithiocarbamic acid group, or a 1,3,4-thiadiazole group. 1,3,4-Thiadiazole is an example. The amt. of the compd. added is varied according to the type of the lubricant compsn., and a place to which it is applied, etc.; for instance, the amt. is in the range of 0.3-20wt.% in the case of a grease for bearings. As a base oil for preparing a grease, a paraffinic mineral oil is used as the mineral oil and a poly-α-olefin oil is used as a synthetic hydrocarbon oil. The incorporation of a synthetic oil, esp. an ester oil or an ether oil, is pref. in terms of lubricity and lubrication life at high temp. and high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant composition applied to rotating members and sliding members of various industrial machines and vehicles, and particularly to a load-bearing portion such as a portion subjected to a high load or a portion having a high slip ratio. The present invention relates to a lubricating composition suitable for a place where a property or an extreme pressure property is required or where abrasion is likely to occur.

[0002]

2. Description of the Related Art Grease, which is one of the lubricant compositions,
Widely applied to rotating and sliding members of various industrial machines and vehicles such as roller bearings, four-point contact ball bearings, cross roller bearings, linear motion guide devices (linear guides, ball screws, etc.), constant velocity joints, gears, etc. I have. In these rotating members and sliding members, bearings used under high loads, such as tapered roller bearings for roll necks of rolling mills in steel facilities, not only have excellent extreme pressure properties under high loads, but also have abrasion resistance. It is desirable to enclose grease which is excellent. Load-bearing and in order to impart extreme pressure is generally methods of adding extreme pressure grease, solid lubricant ₂ such MoS Conventionally, sulfur-based, phosphorus-based, sulfur - phosphorus-based organic compound Organic molybdenum compounds such as molybdenum dialkyldithiocarbamate (MoDTC) and molybdenum dialkyldithiophosphate (MoDTP); zinc dialkyldithiophosphate (ZnDT
Extreme pressure agents such as organic zinc compounds such as P) and organic antimony compounds are known. For example, Japanese Patent Publication No. 4-34590, Japanese Patent Publication No. 3-78920, Japanese Patent Application Laid-open No. Sho 60-47.
No. 099, MoDTC, MoDTP, ZnDT
It is described that an extreme pressure agent containing an organic molybdenum compound such as P or an organic zinc compound is particularly effective. It is also known that ashless dialkyldithiocarbamic acid is also effective.

[0003]

On the other hand, recently, in consideration of maintenance costs, it has been desired that a lubricant composition can be used once over a long period of time after being applied once. In addition, the use conditions tend to be 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 lubricant composition. . However, a lubricant composition containing an organic molybdenum-based compound, an organic zinc compound, an organic antimony compound, or the like, which has been conventionally considered to be preferable,
Such demands cannot be sufficiently satisfied, and the number of lubricating points that cannot be applied is increasing. The present invention has been made in view of the above circumstances, and provides a lubricant composition having excellent load resistance and extreme pressure properties more than before, and providing a longer lubricating life at an application place. It is the purpose.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, by including a specific ashless sulfur compound in a lubricant composition, the load resistance of the lubricant composition has been improved. It has been found that the extreme pressure property can be greatly improved, and the present invention has been completed. That is, the above purpose is
This is achieved by the lubricant composition according to the present invention, which comprises an ashless sulfur compound having a hetero atom other than sulfur in the molecule.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the lubricant composition of the present invention will be described in detail. The ashless sulfur compound used in the lubricant composition of the present invention is not particularly limited as long as it has a hetero atom other than sulfur in the molecule and does not contain a metal atom. For example, 1,3,4-thiadiazole, dibenzothiazyl disulfide, piperidine pentamethylenedithiocarbamate, 4,4-dithiomorpholine, 2-mercaptobenzothiazole, 2- (4 ′
-Morpholinodithio) benzothiazole, N-cyclohexyl-2-benzothiazolesulfenamide, N-
tert-butyl-2-benzothiazolesulfenamide, N, N-dicyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, dipentamethylenethiuram tetrasulfide, 2,5- Dimercapto-1,
3,4-thiadiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole, 2-mercaptobenzimidazole, 2-mercaptotoluimidazole, derivatives thereof, and the like can be used. A compound having a polysulfide group (disulfide group, tetrasulfide group, etc.), a dithiocarbamic acid group, or a 1,3,4-thiadiazole group in addition to a hetero atom other than sulfur. The above ashless sulfur compounds are added to the lubricant composition alone or in combination of two or more. In addition, the combination at the time of mixing and adding is not particularly limited. The amount of addition varies depending on the type of lubricant composition, the location of application, and the like. If it is less than this, sufficient effects cannot be obtained, and if it is more than this, further improvement of the effect cannot be expected. May decrease.

The above ashless sulfur compound acts as an extreme pressure agent, but it is also preferable to use a conventionally known extreme pressure agent in combination, whereby load resistance and extreme pressure properties can be further improved. Further, a known solid lubricant may be used in combination.

The lubricant composition of the present invention is used as a lubricant for various mechanical parts such as engine oil and gear oil. In addition, since these lubricant compositions are excellent in load resistance and extreme pressure, Particularly, it is suitable for grease sealed in various bearings to which a high load is applied and used at high temperature and high speed rotation. Hereinafter, a preferred embodiment when grease is used will be described.

[0008] As the base oil used for forming grease, mineral oil, 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.

The thickener is not particularly limited.
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 grease may be blended with the following known additives. [Antioxidant] rubber, plastic,
The antioxidant, antiozonant, and antioxidant to be added to the lubricating oil and the like are 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-dioctylphenothiazine,
amine compounds such as p, p'-dioctyldiphenylamine, N, N'-diisopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine; 2,6-di-tert-di A phenolic compound such as butylphenol 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.

Hereinafter, the lubricant composition of the present invention will be described in more detail with reference to Examples and Comparative Examples using grease as an example. The grease used in Examples and Comparative Examples was
Urea grease and lithium grease prepared as described below. Urea grease: base oil has a kinematic viscosity at 40 ° C of 150 cSt
Grease using a diurea compound obtained by reacting diphenylmethane-4,4-diisocyanate with octylamine using the above mineral oil as a thickener. Lithium grease: base oil has a kinematic viscosity at 40 ° C of 150 cS
grease using lithium stearate as a thickener, using mineral oil of t. The amount of thickener is finally 10% by weight in the grease.
Included.

Then, each compound was added to the grease as shown in Table 1 to prepare a test grease, and a seizure test and a bearing durability test were performed. Incidentally, all the seizure tests were performed, and only the typical bearing durability tests were performed. Each test method is as follows. 1. Seizure test This seizure test is performed to evaluate the extreme pressure property of the lubricant composition (in this case, grease), and is performed by a four-ball test method using a test apparatus specified by ASTM. That is, three test balls (steel balls for ball bearings SUJ21 /
2 ") are arranged and fixed in an equilateral triangle so as to be in contact with each other, and one test ball is placed on a depression formed in the center thereof. Then, the test placed with the test grease filled therein While rotating the ball at a constant rotation speed (4000 rpm), initially load 1 kg for 1 minute, then 50 kgf
The load was gradually increased at a rate of f / min, and the load at the time when the rotational torque sharply increased was determined as the seizure load. The evaluation criteria were that the seizure load was 60 kgf or more.

2. Bearing endurance test This bearing endurance test is based on the lubricant composition (in this case, grease).
The purpose of this is to evaluate the durability at high temperature of the sample, which was performed by the following method. That is, rolling bearings (call number:
HR30205J) was filled with 3 g of each test grease, rotated at a high speed of 10,000 rpm under a temperature of 120 ° C., a radial load of 50 kgf, and an axial load of 150 kgf, and measured the time until burning. The evaluation criteria were 1000 hours or more under the above conditions.

The results of the seizure test and the bearing durability test are also shown in Table 1.

[0017]

[Table 1]

From Table 1, it can be seen that the grease of the example is superior to the grease of the comparative example in both seizure load and durability time.

[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.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C10N 40:02 40:04 40:25 50:10 (72) Inventor Atsushi Yokouchi 1-5-50 Kumeinuma Shinmei 1-chome, Fujisawa City, Kanagawa Prefecture Nippon Seiko Co., Ltd. (72) Inventor Michiharu Naka 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa Nippon Seiko Co., Ltd.

Claims (1)

[Claims] 1. A lubricant composition comprising an ashless sulfur compound having a heteroatom other than sulfur in the molecule.