Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2001-06-21
2002-10-15
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S481000, C508S482000, C508S591000
Reexamination Certificate
active
06465400
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a lubricant composition for a high temperature. More specifically, it relates to a lubricant composition for a high temperature which is used in a chain, a roller chain, a chain conveyor, a bearing and the like.
BACKGROUND OF THE INVENTION
Since a lubricant which is used ina chain, a roller chain, a chain conveyor, a bearing and the like is exposed to a high temperature, an amount of a lubricant evaporated greatly influences a life of an apparatus. Thus, a lubricant loses an ordinary viscosity under a condition of a high temperature and becomes a thin film, so that an amount of a lubricant evaporated has to be controlled under severer conditions. As an ordinary lubricant for a high temperature, high-molecular oil with a high viscosity has been used to control an amount evaporated. Although an amount of such oil evaporated is small, a power loss is great, and it is undesirable in view of a total performance of a lubricant. Further, when such oil is exposed to a thin film and a high temperature, a residual amount is large, but it is solidified. Not only are characteristics as a liquid lost, but also it becomes a solidified sludge to prevent flow of oil, inviting poor lubrication of a lubricating portion. Accordingly, a lubricant for a high temperature of which the amount evaporated in a thin film at a high temperature is controlled and of which the fluidity is maintained for a long period of time has been in demand.
From this standpoint, the present invention has been made, and it aims to provide a lubricant composition for a high temperature of which the amount evaporated in a thin film at a high temperature is controlled and of which the fluidity is maintained for a long period of time.
DISCLOSURE OF THE INVENTION
The present inventors have assiduously conducted investigations, and have consequently found that the aim of the present invention can be achieved by using a specific aromatic ester compound as base oil. This finding has led to the completion of the present invention.
That is, the gist of the present invention is as follows.
(1) A lubricant composition for a high temperature which is obtained by mixing a base oil composition comprising (a) 20 to 100% by weight of an aromatic ester compound represented by the following general formula (I)
(wherein R
1
represents an alkyl group having 6 to 16 carbon atoms, and n represents an integer of 1 to 6)
and (b) 0 to 80% by weight of another base oil with (c) 0.1 to 10% by weight, based on the total amount of the lubricant composition, of an antioxidant.
(2) The lubricant composition for the high temperature as recited in the above (1), wherein the base oil composition comprises (a) 30 to 80% by weight of the aromatic ester compound and (b) 20 to 70% by weight of another base oil.
(3) The lubricant composition for the high temperature as recited in the above (1) or (2), wherein the aromatic ester compound (a) is one selected from a trimellitic acid alkyl ester and a pyromellitic acid alkyl ester.
(4) The lubricant composition for the high temperature as recited in any of the above (1) to (3), wherein another base oil (b) is one type or two or more types selected from an &agr;-olefin oligomer, an ethylene-&agr;-olefin oligomer, polybutene and hydrogenated substances thereof.
(5) The lubricant composition for the high temperature as recited in any of the above (1) to (4), wherein the antioxidant (c) is one containing sulfur and/or phosphorus in a molecule.
(6) The lubricant composition for the high temperature as recited in any of the above (1) to (5), wherein the antioxidant is one selected from a dithiophosphoric acid salt and a thiophosphoric acid ester.
(7) The lubricant composition for the high temperature as recited in any of the above (1) to (5), wherein the antioxidant is 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol.
BEST MODE FOR CARRYING OUT THE INVENTION
The mode for carrying out the present invention is described below.
The base oil composition constituting the lubricant composition for the high temperature in the present invention comprises (a) 20 to 100% by weight of the aromatic ester compound represented by the above general formula (I) and (b) 0 to 80% by weight of another base oil.
With respect to the aromatic carboxylic acid constituting the aromatic ester compound as component (a), the number of carboxylic acids bound to benzene is preferably 3 or 4. Among others, trimellitic acid and pyromellitic acid are preferable. As an aliphatic alcohol used in the aromatic carboxylic acid ester, a linear or branched alcohol having 6 to 16 carbon atoms is preferable. Specific examples thereof can include tri-n-hexyl trimellitate, tri-2-ethylhexyl trimellitate, tri-n-octyl trimellitate, tri-3,5,5-trimethylhexyl trimellitate, tetra-n-hexyl pyromellitate, tetra-2-ethylhexyl pyromellitate, tetra-n-octyl pyromellitate, tetra-3,5,5-trimethylhexyl pyromellitate and the like. Incidentally, the aromatic carboxylic acid esters may be used either singly or in admixture of two or more types, and a partial ester may be contained in a full ester.
As another base oil (b), any mineral oil type or synthetic oil type that is used as base oil of ordinary equipment oil can be used. As the mineral oil-type base oil, for example, refined oil which is formed by refining a lubricant fraction resulting from atmospheric distillation or vacuum distillation of paraffin base crude oil, intermediate base crude oil or naphthene base crude oil by an ordinary method such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrogenation refining, sulfuric acid treatment, clay treatment or the like.
Further, as the synthetic oil-type base oil, various substances such as an &agr;-olefin oligomer, an ethylene-&agr;-oligomer, a polybutene, a dibasic acid ester, a polyalkylene glycol, a hindered ester, an alkylbenzene, an alkylnaphthalene, a polyether and the like can be used. Of these, an &agr;-olefin oligomer, an ethylene-&agr;-oligomer, a polybutene or hydrogenated substances thereof are preferable because the fluidity can be maintained for a long period of time. Incidentally, as component (b), one type or a mixture of two or more types may be used, and a mixture of mineral oil and synthetic oil may be used.
The proportions of the aromatic carboxylic acid ester (a) and another base oil (b) are that component (a) is 20 to 100% by weight and component (b) is 0 to 80% by weight, and preferably component (a) is 30 to 80% by weight and component (b) is 20 to 70% by weight. When component (a) is less than 20% by weight, the effect of the invention is not provided.
Next, with respect to the antioxidant as component (c) mixed with base oil, an amine-type antioxidant and a phenolic antioxidant can be used. In view of the effect, an antioxidant containing sulfur and/or phosphorus in a molecule is preferable.
Examples of the amine-type antioxidant include monoalkyldiphenylamines such as monooctyldiphenylamine, monononyldiphenylamine and the like; dialkyldiphenylamines such as 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4,4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine, 4,4′-dinonyldiphenylamine and the like; polyalkyldiphenylamines such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine and the like; and naphthylamines such as &agr;-naphthylamine, phenyl-&agr;-naphthylamine, butylphenyl-&agr;-naphthylamine, pentylphenyl-&agr;-naphthylamine, hexylphenyl-&agr;-naphthylamine, heptylphenyl-&agr;-naphthylamine, octylphenyl-&agr;-naphthylamine, nonylphenyl-&agr;-naphthylamine and the like.
Examples of the phenolic antioxidant can include monophenols such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol and the like; and diphenols such as 4,4′-methylenebis(2,6-di-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol) and the like.
Examples of the antioxidant containing sulfur and/
Kamimura Hideto
Nagakawa Hiroshi
Idemitsu Kosan Co. Ltd.
McAvoy Ellen M.
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