Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2002-01-31
2003-07-29
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
Reexamination Certificate
active
06599867
ABSTRACT:
The present invention relates to overbased alkaline earth metal detergent lubricant additives.
The use of alkaline earth metal salts of organic carboxylic acids as detergent additives for lubricating oil compositions (or lubricants) is known in the art. When applied in lubricating oil compositions, they ensure that the inside of engine cylinders remains clean and that the deposition of carbonaceous products on pistons and in piston grooves is counteracted, so that piston ring sticking is prevented. They are also known in basic (or overbased) form. Overbasing provides an alkaline reserve which, when applied in lubricating oil compositions, reacts with and neutralizes acidic compounds formed during the operation of the engine in which the composition is applied. Thus, sludge which may arise is maintained in dispersion while acids which would enhance sludge formation are neutralized.
EP-A-248 465 and -267 658 describe such overbased materials and processes for making them comprising the neutralization of an organic carboxylic acid with alkaline earth metal hydroxides or oxides in the presence of a hydrocarbon solvent and an alcohol promoter and water to provide such overbased lubricating oil detergent additives, including the neutralization of alkyl salicylic acids to produce overbased calcium salts of such acids.
Such overbased additives are in the form of concentrates comprising colloidal particles of basic material stabilised in a liquid medium (or diluent or base oil) by ions of the acidic material, sometimes referred to as surfactant or soap. Desirable properties of such an additive include a high total base number (TBN), good handleability to enable it to be readily admixed to make a final lubricant, and a high active ingredient content to maximise the efficiency of the additive. Unfortunately, these desirable properties may conflict with one another: a high active ingredient content may generate handleability problems by causing the viscosity to become unacceptably high. EP-A-0 267 658, for example, describes overbased additives, wherein the surfactant is a salicylate, which, although having good basic and handleability properties, have active ingredient contents that do not exceed 60 mass %. Overbased detergents, wherein the surfactant is an organic carboxylate, having a high TBN and a handleable viscosity, that also have a high active matter content, have now surprisingly been provided.
Thus, a first aspect of the present invention is an overbased alkaline earth metal, such as Ca or Mg, detergent lubricant additive comprising, as a surfactant for the additive, a major proportion of an organic substantially aromatic carboxylate, the additive having:
(a) a TBN of 200 or greater, or 250 or greater, or 300 or greater such as 300 to 500, for example 300 to 400;
(b) an active ingredient content of 70 mass % or greater, such as up to 95, 90, 85 or 80, mass %, active ingredient being all matter other than base oil;
(c) a kinematic viscosity at 100° C. of less than 1000, such as from 50 to less than 1000, for example from 100 to 500, mm
2
s
−1
; and
(d) a basicity index (BI) of less than 13, preferably less than 10, more preferably less than 8.
A second aspect of the invention is a lubricating oil composition comprising an admixture of an oil of lubricating viscosity, in a major amount, and an additive according to the first aspect of the invention, in a minor amount.
A third aspect of the invention is a method of lubricating a marine diesel engine, such as a trunk piston engine, comprising supplying to the engine a lubricating oil composition according to the second aspect of the invention.
A fourth aspect of the invention is a combination comprising:
(a) mechanical parts to be lubricated of a marine diesel engine, such as a trunk piston engine; and
(b) a lubricating oil composition according to the second aspect of the invention.
In this specification:
“Major amount” means in excess of 50 mass % of the composition;
“Minor amount” means less than 50 mass % of the composition, both in respect of the stated additive and in respect of the total mass % of all of the additives present in the composition, reckoned as active ingredient of the additive or additives;
“Comprises or comprising” or cognate words are taken to specify the presence of stated features, steps, integers, or components, but does not preclude the presence or addition of one or more other features, steps, integers, components or groups thereof;
“TBN” is Total Base Number as measured by ASTM D2896;
“Oil-soluble” or “oil-dispersible” do not necessarily indicate that the additive(s) are soluble, dissolvable, miscible or capable of being suspended in oil, in all proportions. They do mean, however, that they are, for example, soluble or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired;
“substantially aromatic” means greater than 50% by weight, preferably greater than 70% by weight, more preferably greater than 80% by weight, most preferably greater than 90% by weight, of the carboxylate is aromatic; and
“basicity index (BI)” is defined as the equivalents ratio of the total alkaline earth metal to the total of organic acid.
It should be noted that the lubricating oil compositions of this invention comprise defined individual, i.e. separate, components that may or may not remain the same chemically before and after mixing.
The features of the invention will now be discussed in further detail as follows:
OVERBASED DETERGENT
In the detergents of the first aspect of the invention, suitable organic substantially aromatic carboxylate detergents are those derived from acids containing a benzene or naphthalene ring and an oil-solubilising group or group having a total of at least 8, in particular at least 12, carbon atoms. Preferred are hydrocarbyl-, particularly alkylsalicylic acids having at least 10 carbon atoms in the alkyl group or groups, in particular 12 to 26, such as 14 to 18 carbon atoms. Preferably, there is only one surfactant. Preferably, a salicylate constitutes the sole surfactant for the additive.
“Hydrocarbyl” means a group composed primarily of carbon and hydrogen atoms, connected via a carbon atom, and that may contain other atom(s) provided they do not substantially alter the hydrocarbon nature of the group.
Other suitable acids that may be used include substituted or unsubstituted aliphatic or cycloaliphatic acids. As examples, there may be mentioned naphthenic acids; and aliphatic acids having more than 8 carbon atoms such as stearic, isostearic, palmitic, myristic, oleic and hydroxystearic acids, and tertiary carboxylic acids.
The detergents may be prepared by treating with an overbasing agent, at a temperature of less than 100° C., a mixture of at least one organic substantially aromatic surfactant, at least one basic calcium compound and oil. The detergent is optionally subjected to at least one heat-soaking step. After heat-soaking, the detergent is preferably subjected to second treatment with an overbasing agent at a temperature less than 100° C. The second overbasing step is also preferably followed by a heat-soaking step. The detergent preferably has a TBN of at least 300 mgKOH/g. During heat-soaking, the mixture is maintained, without addition of any further chemical reagents, in a selected temperature range, which is normally equal to or higher than the temperature at which carbonation is effected. Temperatures at which heat-soaking may be carried out are typically in the range of from 15° C. to just below the reflux temperature of the reaction mixture, preferably 25 to 60° C.; the temperature should be such that substantially no materials (for example, solvents) are removed from the system during the heat-soaking step. Heat-soaking may be carried out for any suitable period, advantageously for at least 30 minutes, advantageously for at least 45 minutes, preferably for at
Hammond Steve
Price Mark A.
Skinner Philip
Howard Jacqueline V.
Infineum International Ltd.
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