Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic phosphorus compound – wherein the phosphorus is...
Reexamination Certificate
2002-06-20
2003-12-09
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic phosphorus compound, wherein the phosphorus is...
C558S090000, C558S092000, C558S208000, C252S400210
Reexamination Certificate
active
06660696
ABSTRACT:
This invention relates to thermally Stable phosphorothionates from cashew nut shell liquid for use as thermally stable, antioxidant, antiwear and extreme pressure additives in a lubricant composition. The said additive for use in a lubricant controls wear on metal parts and enhances its load carrying properties.
BACKGROUND
Lubrication involves the process of friction reduction, accomplished by maintaining a film of a lubricant between two surfaces which are moving with respect to each other. The lubricant prevents contact of the moving surfaces, thus greatly lowering the coefficient of friction. Since lubricants for different uses operate under different conditions, numerous additives have been developed to establish or enhance various properties of lubricants. Representative types of additives which are used include viscosity improvers, detergents, dispersants, antioxidants, extreme pressure additives, corrosion inhibitors and others. Frequently, combinations of additives are required.
Of particular importance in many applications are antiwear agents, many of which function by a process of interaction with the surfaces, thereby providing a chemical film which prevents metal-to-metal contact under high load conditions. Wear inhibitors which are useful under extremely high load conditions are frequently called “extreme pressure agents”. These extreme pressure agents are frequently selected from the following chemical types: zinc organodithiophosphates; sulfurized olefins, chlorinated waxes; amine salts of phosphate esters; phosphites; and others. Certain of these materials, however, must be used judiciously in certain applications due to their property of accelerating corrosion of metal parts, such as bearings. In addition, some applications require very low concentrations of certain elements, such as phosphorus, which restricts the utility of otherwise quite useful extreme pressure agents.
An exhaustive literature review was conducted to examine the types of chemistries in use as antiwear and EP additives. Example of antiwear and extreme pressure additives are: sulfur-and/or phosphorous-and/or halogen-containing compounds, such as sulfurized olefins and vegetable oils, zinc dialkyldithiophosphates, tritolyl phosphate, tricresyl phosphate, chlorinated paraffins, alkyl and aryl di- and trisulfides, amine salts of mono- and dialkyl phosphates, amine salts of methylphosphonic acid, diethanolaminomethyl tolyltriazole, di(2-ethylhexyl)-aminomethyltolyltriazole, derivatives of 2,5-dimercapto-1,3,4-thiadiazole, triphenylthiophosphate (triphenyl phosphorothioate), diphenylmonononylphenyl phosphorothioate, isobutylphenyl diphenyl phosphorothioate, derivatives of 2-mercaptobenzothiazole and ethoxycarbonyl 5-octyldithiocarbamate.
The object of the present invention is to provide for a thermally stable, antioxidant, antiwear and extreme pressure lubricant additive, derived from CNSL, a renewable and biodegradable product from vegetable sources and often available at very low price, which would amount to substantial overall reduction in the cost of quality, energy efficient lubricant/fuel formulations.
Another object of the present invention is to provide for a lubricant composition and more particularly, to lubricant compositions comprising oils of lubricating viscosity or greases thereof containing a minor thermally stable antioxidant, antiwear and extreme pressure additive derived from cashew nut shell liquid.
Cashew nut shell liquid (CNSL) occurs as a reddish brown viscous liquid in the soft honeycomb structure of the shell of cashewnut, a plantation product obtained from the cashew tree, Anacardium Occidentale L. Native to Brazil, the tree grows in the coastal areas of Asia & Africa. Cashewnut attached to cashew apple is grey colored, kidney shaped and 2.5-4 cm long. The shell is about 0.3 cm thick, having a soft leathery outer skin and a thin hard inner skin. Between these skins is the honeycomb structure containing the phenolic material popularly called CNSL. Inside the shell is the kernel wrapped in a thin brown skin, known as the testa.
The nut thus consists of the kernel (20-25%), the shell liquid (20-25%) and the testa (2%), the rest being the shell. CNSL, extracted with low boiling petroleum ether, contains about 90% anacardic acid and about 10% cardol. CNSL, on distillation, gives the pale yellow phenolic derivatives, which are a mixture of biodegradable unsaturated m-alkylphenols, including cardanol. Catalytic hydrogenation of these phenols gives a white waxy material, predominantly rich in tetrahydroanacardol.
CNSL and its derivatives have been known for producing high temperature phenolic resins and friction elements, as exemplified in U.S. Pat. Nos. 4,395,498 and 5,218,038. Friction lining production from CNSL is also reported in U.S. Pat. No. 5,433,774. Likewise, it is also known to form different types of friction materials, mainly for use in brake lining system of automobiles and coating resins from CNSL. However, the first application of CNSL in making lubricating oil additives was disclosed by us in U.S. Pat. Nos. 5,916,850 and 5,910,468.
Our U.S. Pat. No. 5,916,850 described development of multifunctional additives from cashew nut shell liquid or from saturated alkylphenols derived from cashew nut shell liquid. The patent relates to a process for preparing tri (alkylaryl) phosphorodithioate. The products of this invention were found to have better antifriction, extreme pressure and antiwear properties. In another U.S. Pat. No. 5,910,468, cashew nut shell liquid has been exploited for developing overbased calcium phenate detergents as additives for lubricant formulations. In another U.S. Pat. No. 6,339,052, additives derived from cashew nut shell liquid were exploited in lubricant compositions for internal combustion engines.
DETAILED DESCRIPTION OF THE INVENTION
To achieve the said objects, the present invention provides for CNSL phosphorothionates. It also provides for a process for the preparation of CNSL phosphorothionates for use as an thermally stable, antioxidant, antiwear and extreme pressure additive in a lubricant composition, comprising the steps of hydrogenating distilled technical cashew nut shell liquid (CNSL) with a catalyst as herein described to fully hydrogenate the olefinic chain and reacting said cashew nut shell liquid with phosphorus trihalides and sulphur, the reaction being carried out at a temperature ranging from 20 to 220° C.
The materials of the present invention are useful as additives for lubricants in which they can function primarily as thermally stable antiwear, antiscuff, and/or extreme pressure agents. They may be employed in a variety of lubricants based on diverse oils of lubricating viscosity, including natural and synthetic lubricating oils and mixtures thereof. These lubricants include crankcase lubricating oils for spark-ignited and compression-ignited internal combustion engines, including automobile and truck engines, two-cycle engines, aviation piston engines, marine and railroad diesel engines, and the like. They can also be used in gas engines, stationary power engines and turbines and the like. Automatic or manual transmission fluids, transaxle lubricants, gear lubricants, including open and enclosed gear lubricants, tractor lubricants, metal-working lubricants, hydraulic fluids and other lubricating oil and grease compositions can also benefit from the incorporation therein of the compositions of the present invention. They may also be used as wirerope, walking cam, way, rock drill, chain and conveyor belt, worm gear, bearing, and rail and flange lubricants.
The compounds of the invention can be incorporated into lubricating oils and power transmitting oils as an antiwear additive in an amount from between about 0.01 to 5 wt. %, preferably from between about 0.1 to 1.5 wt. %, most preferably from between about 0.2 to 1.0 wt. %. The oleaginous materials may be formulated to contain other additives such as viscosity modifiers, auxiliary antioxidants, friction modifiers, dispersants, antifoaming agents, auxiliary antiwear a
Arora Ajay Kumar
Bhatnagar Akhilesh Kumar
Ranjan Rajeev
Sarin Rakesh
Tuli Deepak Kumar
Howard Jacqueline V.
Indian Oil Corporation Limited
Sidley Austin Brown & Wood LLP
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