Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic sulfur compound – wherein the sulfur is single bonded...
Reexamination Certificate
2000-06-02
2001-05-29
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic sulfur compound, wherein the sulfur is single bonded...
Reexamination Certificate
active
06239083
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to oil formulations employing overbased detergents containing calcite and to the method of clarifying such oil formulations.
BACKGROUND OF THE INVENTION
Among the materials that impart detergency to lubricating oils to keep internal engine parts clean and reduce sludge formation in the oil are overbased detergents, particularly calcium sulfonates. These sulfonates are known to be useful as additives for lubricating oils, particularly as a crankcase engine oil for internal combustion engines.
Overbased calcium sulfonates are generally produced by carbonating a mixture of hydrocarbons, sulfonic acid, calcium oxide or calcium hydroxide and promoters such as methanol and water. In carbonation, the calcium oxide or hydroxide reacts with the gaseous carbon dioxide to form calcium carbonate. The sulfonic acid is neutralized with an excess of CaO or Ca(OH), to form the sulfonate. The prior art known processes for overbasing calcium sulfonates produce high alkaline reserves of TBN of 300 to 400 mg KOH/gm or higher, which enables the formulator to use lower amounts of additive while maintaining equivalent detergency to protect the engine adequately under conditions of high acid formation in the combustion process.
The calcium carbonate component of the overbased calcium sulfonate forms the core of a calcium sulfonate micellar structure. The calcium carbonate is either in the amorphous and/or one or more of its crystalline forms particularly, calcite.
Dispersions of non amorphous or so called crystalline calcium carbonates are generally very cloudy and highly viscous materials. These are prepared by a variety of processes such as disclosed in U.S. Pat. No. 3,242,079, U.S. Pat. No. 3,376,222, U.S. Pat. No. 4,560,489, U.S. Pat. No. 4,597,880, U.S. Pat. No. 4,824,584 and U.S. Pat. No. 5,338,467. They find limited application as rust preventative coatings, rheology modifiers, extreme pressure (EP) metal working formulations and greases. Although colloidal dispersions comprising crystalline calcium carbonate are widely used in formulating greases, they generally cannot be used in formulated engine oil lubricants because it does not give acceptably transparent formulations and it provides very high viscosities. Calcite carbonates, however, have desirable antiwear properties so that it would be advantageous to use such materials in engine lubricating oils.
The lubricating oil art, particularly as directed to automotive crankcase and other engine oils, mandates a clear or substantially haze free product for requisite consumer aesthetics and acceptance. This need precluded the use of prior art detergents with haze producing crystalline calcium carbonate.
Papke, et al., U.S. Pat. No. 4,995,993, recognized that large micellar crystalline calcium carbonate structures caused haze, and overbased sulfonate products containing crystalline calcium carbonates are always undesirable and therefore crystallization was to be avoided at all costs. See col. 4, lines 39-42 of U.S. Pat. No. 4,995,993.
In “Colloidal Anti-wear Additives 2. Tribological Behavior of Colloidal Additives in Mild Wear Regime,” J. L. Mansot, et al.,
Colloids and Surfaces A: Physico Chemical and Engineering Aspects
, 75 (1993), pp. 25-31, it is indicated that for certain forms of an overbased sulfonate containing an amorphous calcium carbonate core, when in a 2% by weight dispersion in dodecane, and subjected to metallic friction surfaces, the calcium carbonate forms a polycrystalline film adherent to the metallic friction surfaces, which resultantly provides anti-wear protection. Mansot, et al. thereby directed one to providing an overbased calcium sulfonate with an amorphous micellar structure which would then, under a mild wear regime, undergo transformation to microcrystalline agglomerates through an amorphous intergranular phase. Mansot, et al., in this manner, further confirmed the direction of the prior art to providing amorphous calcium carbonate micellar dispersion overbased calcium sulfonate detergents.
In WO 0004113, a process for producing soluble overbased calcite-containing detergents are described which are suitable for use in engine oil formulations. However, for many purposes it would be more advantageous to be able to use a conventionally prepared calcite-containing detergent in an engine oil formulation.
SUMMARY OF THE INVENTION
A procedure has been developed whereby an oil dispersion comprising a conventionally prepared calcite-containing detergent material can be reacted with various acidic compounds to produce clear dispersions that find utility in engine oil applications to provide multi-functional benefits including corrosion protection, antiwear and extreme pressure benefits, detergency, and friction reduction properties.
Unlike the method of WO 0004113, which utilizes a process for converting an amorphous overbased calcium sulfonate into a clear calcite-containing product, the processes of the present invention start from dispersion of conventional calcite overbased products, post-reacting the dispersion with the acidic compound in the presence of a solvent or solvent blend to form a clear dispersion.
In one aspect the invention is a process for clarifying a hazy dispersion of a calcite-containing sulfonate detergent in oil, the process comprising:
a) adding to the dispersion at least one acidifying compound selected from the group consisting of carbon dioxide; sulfur dioxide; organosulfonic acids having a molecular weight of at least 350, and organic carboxylic acids, diacids and anhydrides, containing at least 7 carbon atoms,
b) reacting the dispersion in the presence of the acidifying compound, water, and at least one volatile organic solvent, and
c) removing volatiles from the so-reacted dispersion by vaporization.
Another aspect of the present invention is lubricating oils produced by said process.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is applicable to a wide variety of lubricating oils. The lubricating oil can be composed of one or more natural oils, one or more synthetic oils, or mixtures thereof. Natural oils include animal oils and vegetable oil (e.g., castor, lard oil), liquid petroleum oils and hydrorefined, solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic and mixed paraffinic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1hexenes), poly (1-octenes), poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2ethylhexyl)benzenes); polyphenyls (e.g. biphenyls, terphenyls, alkylated polyphenols); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof.
Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methylpolyisoprdpylene glycol ether having an average molecular weight of 1000, diphenyl ether of polyethylene glycol having a molecular weight of 500-1000, diethyl ether of polypropylene glycol having a molecular weight of 1000-1500); and mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C
3
-C
8
fatty acid esters and C
13
oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g. phthalic acid, succinic acids, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, mal
Crompton Corporation
Howard Jacqueline V.
Reitenbach, Esq. Dan
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