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
2002-06-17
2004-02-10
McAvoy, Ellen M. (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...
C508S441000, C508S485000, C508S496000, C508S498000, C508S501000, C508S506000, C508S512000, C508S571000, C508S585000
Reexamination Certificate
active
06689726
ABSTRACT:
This invention relates to lubricating oil based on base stocks having a saturates content of 99 wt % or more, preferably essentially 100% saturates and containing sulfur-phosphorus containing anti-wear/extreme pressure additives and hindered phenol antioxidants which combination of anti-wear/extreme pressure agent and hindered phenol antioxidant are prone to crystal formation, wherein the formation of crystals is reduced or eliminated by the use of a crystallization suppressant.
Lubricating oils containing various antioxidants or esters or fatty acid amides or sulfur-phosphorus additives in combination with phenols are known in the literature.
U.S. Pat. No. 5,167,844 is directed to a formulation comprising a base oil, at least one sulfur phosphorus containing compound, at least one amine and at least one hindered phenol.
JP 07034078 is directed to a hydraulic oil comprising mineral oil with an aromatic content of up to 1.5 wt % and a phenolic and aminic anti-oxidant, an alkenyl succinic acid imide rust inhibitor and a phosphoric acid type anti wear agent.
U.S. Pat. No. 5,590,483 is directed for lubricating a refrigeration system compressor using a break-in lubricating oil which is an ester type oil. Additionally an adipate, phthalate, azelate, sebacate, corrosion inhibitors such as alkali and/or alkaline earth metal sulfonate, antioxidants such as aminic or phenolic antioxidants and metal deactivators such as triazoles.
WO 97/14776 is directed to hydraulic oils comprising base oils combined with an amine antioxidant, a phenolic antioxidant, a phosphate ester and a fatty acid amide and/or polyhydric alcohol ester.
U.S. Pat. No. 5,773,393 is directed to a composition comprising at least 70 wt % oil of lubricating viscosity and an amount effective to inhibit metal corrosion of a soluble additive comprising (a) at least one amide compound of a mono- or polycarboxylic acid or reactive derivative thereof and (b) at least 0.5 equivalents of at least one primary or secondary amine per mole of amide provided that when (a) is an amide of a dicarboxylic acid and the amine is an alkanol amine the mixture contains more than 0.5 equivalent of the amine (b) per equivalent of the amide.
The present invention is directed to a lubricating oil formulation having a reduced potential for the formation of crystals comprising a major amount of a lubricating oil base stock having a saturates content of 99 wt % or more, preferably essentially about 100 wt % and a minor amount of additives comprising a mixture of sulfur-phosphorus containing anti-wear/extreme pressure additive, hindered phenol antioxidant, and a di- or polycarboxylic acid, anhydride or mixture thereof and an ester, and to a method for reducing crystal formation in lubricating oil formulations comprising base oil having saturates content of 99 wt % or more, preferably essentially about 100 wt %, and containing sulfur phosphorus anti-wear/extreme pressure additive and hindered phenolic anti-oxidant wherein the crystals are attributable to the interaction between the sulfur-phosphorus containing anti-wear/extreme pressure agent and the hindered phenol, by adding to said lubricating oil a minor effective amount of di- or polycarboxylic acid, anhydride or mixture thereof and an ester.
The lubricating base oil is any oil of lubricating oil viscosity having a saturates content of 99 wt % or more, preferably essentially 100 wt %.
Lubricating oils meeting this criterion are any natural mineral or petroleum based lubricating oils derived from crude oil, tar sands, shale oil, etc., such that they have a saturates content in the recited range, or a mixture of natural mineral or petroleum based lubricating oils in combination with poly-alpha olefins, isormerized wax or isomerized Fischer-Tropsch wax, the combination or mixture of such oils being characterized as having a saturates content of 99 wt % or more, preferably essentially 100 wt %. Saturates content, for the purpose of this invention, is a measure of the absence of aromatic species, and was determined using high pressure liquid chromatography (HPLC) according to method IP 368, except where otherwise expressly indicated.
The lubricating oil base stocks useful in the present invention have the typical lubricating oil viscosity, usually possessing kinematic viscosities in the range of about 1.5 to 500 mm
2
/s at 100° C., preferably 5 to 120 mm
2
/s at 100° C.
Mineral or petroleum based lubricating oil base stocks can be derived from paraffinic, naphthenic and mixed base crudes. Conventional refinery techniques include distillation, solvent and/or catalytic dewaxing, solvent extraction, hydrofinishing, hydrocracking, vis breaking, deasphalting, etc. Preferred mineral or petroleum based base stocks include white oils, hydrocracked or hydroisomerised base stocks.
Synthetic lubricating oils that can be used include esters of di- and tri-basic acids, reacted with linear or branched aliphatic alcohols such as C
6
-C
15
alcohols, such as di-2-ethylhexyl sebacate, phthalates, esters of glycols such as C
13
oxo acid diester or tetraethylene glycol, or complex esters such as one formed from 1 mole of sebacic acid and 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid. Other synthetic oils that can be used include silicone oils, e.g., methyl polysiloxanes, etc.; polyglycol oils, e.g., those obtained by condensing butyl alcohol with propylene oxide; carbonate esters, e.g., the product of reacting C
6
oxo alcohol with ethyl carbonate to form a half ester followed by reaction of the latter with tetraethylene glycol, etc. The only requirement is that such oils be 100% saturated (that is, contain no unsaturation).
Other suitable oils are the polyol ester oils made by reacting an aliphatic polyol with carboxylic acid. Aliphatic polyols contain from 4 to 15 carbon atoms and has from 2 to 8 esterifiable hydroxyl groups. Examples of polyols are trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyl glycol, tripentaerythritol and mixtures thereof. The carboxylic acid reactant is selected from aliphatic moncarboxylic acid or mixtures of aliphatic mono carboxylic acids or mixtures of aliphatic mono- and di-carboxylic acids. The carboxylic acids contain 4 to 12 carbons and include straight and branched chain carboxylic acids.
Included in the group of synthetic oils are those recovered from tar sands, shale oil, light hydrocarbons produced via, for example, the Fischer-Tropsch process for converting synthesis gas (CO and hydrogen) into hydrocarbons, wax isomerate oils produced by the catalytic hydroisomerization of natural petroleum waxes (i.e., slack wax) or synthetic waxes (i.e., Fischer-Tropsch waxes) or mixtures of such waxes. See U.S. Pat. No. 5,059,299 and U.S. Pat. No. 5,158,671 for description of wax isomerization and the oils produced thereby. Other synthetic oils include the polyolefins such as polybutene, polyisobutenes and especially the polyalphaolefins, i.e., fluids formed by the oligomerzation of at least one 1-alkane hydrocarbon having from 6 to 20 carbons, preferable 8 to 16 carbons, more preferably 8 to 12 carbons.
Regardless of the source of the oil, for the purposes of the present invention the lube oil base stock, be it a single oil or a mixture of oils, is characterized as having a saturates content of 99 wt % or more, preferably about 99.8 wt % or more.
Sulfur-phosphorus containing anti wear/extreme pressure additives are well known in the industry, and are materials containing both sulfur and phosphorus in the same materials. For the purposes of the present specification and appended claims, sulfur-phosphorus containing anti-wear/extreme pressure additives are those which react with hindered phenol antioxidant to produce crystals. Those skilled in the formulation art can readily determine without expenditure of significant or inventive effort, whether a particular sulfur-phosphorus containing anti-wear/extreme pressure agent reacts with hindered phenol antioxidant to produce crystals. If it does not, it is not within the scope of this invention. Any sulfur-phosp
ExxonMobil Research and Engineering Company
Foss Norby L.
McAvoy Ellen M.
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