GB1575395A - Preparation of overbased metal naphthenate lubricating oil composition - Google Patents

Description

(54) PREPARATION OF OVERBASED METAL NAPHTHENATE LUBRICATING OIL COMPOSITION (71) We, TEXACO DEVELOPMENT CORPORATION, a Corporation organized and existing under the laws of the State of Delaware, United States of America, of 135 East 42nd Street, New York, New York 10017, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the preparation of lubricating oil compositions overbased metal naphthenates.

Overbased metal salts of organic acids which contain an amount of metal in excess of that theoretically required to replace the acidic hydrogen atoms of the acids have found utility as components of lubricating oil composition. These salts impart to the lubricating compositions an alkaline reserve which neutralizes sulfur-containing and other acids formed during combustion of the fuel thereby reducing corrosion of the engine and decreasing wear of piston rings and cylinders.

Various methods for producing metal naphthenates are already known such as those described in U.S. Patents 2,938,828; 2,865,956 and Japanese Patents 48,094,814; 48,084,815 and 49,010,906.

Although these prior art methods can produce highly overbased metal naphthenate lube oil compositions, they often have the drawback of having relatively slow filtration rates thereby requiring costly and extensive filtration apparatus in order to obtain any meaningful production. Filtration of the final overbased naphthenate lube oil composition is normally necessary since customers require a clear solution and the product in a crude state often contains considerable solids, predominantly undispersable, agglomerated calcium carbonate particles, which require removal.

The invention pertains to a method of producing overbased metal naphthenate lubricating oil compositions which have superior filtration properties, i.e. are readily filterable under conditions which produce a clear product.

The reactions occurring in the method can be summarized as follows: 1) Preparation of the Metal Naphthenate

solvent 2RCO2H + M(OH)2 o ptiontal ' (RCO2)2M + H2O 2) Overbasing

CO (RCO2)2M + XM(OH)2 solvent (RCO2)2M.XMCO3 In the above X ranges from 1 to 10. R represents a hydrocarbyl radical having from 15 to 40 carbon atoms, M may be any divalent metallic ion but preferably is an alkaline earth metal such as, but not limited to Ca+2, Ba+2, and Sr+2. For the sake of simplicity however, the invention will be illustrated mainly with reference to the preparation of calcium naphthenate-containing compositions. in the above equations, isolation of the normal metal naphthenate [(RCO2)2M] is optional; the entire amount of M(OH)2 may be added initially.

More specifically, the present invention provides a method of preparing a clarified overbased metal naphthenate lubricating oil composition, which comprises contacting a reaction mixture containing: (i) a metal naphthenate having a metal ratio from 1 to 2 and derived from a naphthenic acid having a molecular weight from 230 to 600; (ii) from 1 to 10 moles of a metal hydroxide per mole of metal naphthenate; (iii) a hydrocarbon lubricating oil, in a weight ratio of oil: metal naphthenate (calculated as naphthenic acid) from 1:1 to 6:1; and (iv) an alcohol selected from alkanols and alkoxy-alkanols having 1 to 5 carbon atoms, in a weight ratio of alcohol: metal naphthenate (calculated naphthenic acid) from 1:2 to 1:6; with from 0.75 to 1.1 moles of carbon dioxide per mole of metal hydroxide at a temperature from 57 to 700C, allowing the mixture to stand for from 1 to 100 hours, filtering the mixture, and recovering the clarified overbased metal, naphthenate lubricating oil composition from the resulting filtrate.

Preferably the clarified overbased metal naphthenate lubricating oil composition obtained in the invention has a degree of overbasing (i.e. the ratio of the number of moles of carbonate, expressed by X in equation (2) above, to the number of moles of naphthenate) of from 1 to 10, and a total base number (TBN), as defined by ASTM D 2896, of 50 to 500, or even higher, most desirably between 280 and 450. Preferably, the initial reaction mixture, of metal naphthenate, metal hydroxide, alcohol and lubricating oil, has a water content of less than 1 wt. %.

Optionally and preferably the reaction mixture includes a volatile inert liquid hydrocarbon diluent preferably having a boiling point from 65 to 1500C, and preferably in a weight ratio of diluent metal naphthenate reactant of from 1:1 to 3:1.

In examples of the practice of the invention, the naphthenic acid, diluent oil, hydrocarbon diluent and one equivalent of slaked lime were charged to a nitrogen blanketed 3-liter, 3-neck flask fitted with an air driven stainless steel stirrer and reflux condenser equipped with a water separator. The stirrer was started and the flask was heated until overhead water formation ceased. The crude soap mixture was then transferred to a 2000 ml. Parr stirred autoclave fitted with two turbine impellers. The remaining slaked lime and the methanol were added. The mixture was heated to 60-70"C. CO2 was added through a sparger. During runs at greater than 6:1 overbasing ratios, the reactor system was bled, as required, to hold reactor pressure at a maximum of 0.7 Kp/cm2 gauge. This resulted in a substoichiometric charge of CO2, basis metal hydroxide. The previously recognized phenomenon referred to as "overcarbonation" was found not to occur when overbasing ratios of less than 6 moles M(OH)2/mol metal naphthenate were used, but does appear to occur at higher overbasing ratios. Overcarbonation must be avoided to assure that the product is filterable. After CO2 charge was complete, the temperature was held at 60-70"C.

for 30 minutes. Five percent by weight of a filter aid was added and the product was filtered through blotter paper in a pressure bomb filter. The product was then stripped on a rotary vacuum stripper using a bath temperature of 121"C. Further details concerning preparation of five bench-scale batches of overbased calcium naphthenate are presented in Table II, together with tests on the products.

Two pilot unit batches of the 10:1 calcium carbonate overbased calcium soap were made.

The procedure was the same as that used for the bench-scale batches, except that both the crude soap preparation and the over-basing reaction were carried out in a 37.85 litre reactor and the above described admix filtration was carried out on a 0.186 m2 sparkler filter precoated with 225 g. of a filter aid. Details are shown in Tables III and 1V.

Unexpectedly, it was found that an aging step involving storing of the mixture in an air blanketed vessel for 1 to 100 hours did not significantly affect the filtration rate and in some cases improved it. This phenomenon is not understood but is a part of this invention.

The filtration of the crude overbased naphthenate lubricating oil composition is normally conducted through a stainless steel or cloth plate which may be precoated with filter materials such as diatomaceous silica, diatomaceous silica mixed with wood fibers, cellulose derived from wood pulp, or natural glass derived from volcanic action, at a temperature between 10 and 93"C. Further, to aid filtration, filter aids are preferably employed in the crude mixture in amounts of between 1.0 and 15.0 wt % based on the crude mixture.

Standard filter apparatus may be employed, such as frame filters and bomb filters, preferably filtration is conducted under pressure to speed filtration, e.g. between 0.7 and 7.0 Kp/cm2 gauge. Normally, from a commercial standpoint filtration rates greater than 4 m-'lhrlm2 of filter area are acceptable.

The hydrocarbon lubricating oil employed may be any liquid hydrocarbon material having lubricating properties (e.g. mineral oils) and a viscosity of between 50 and 300 SUS at 37.8"C, but normally is a paraffinic base or naphthenic base lubricating oil, preferably having a viscosity at 37.80C of between 75 and 150 SUS.

Specific examples of the alcohols contemplated herein are methanol, ethanol, propanol, butanol, methoxy-ethanol and ethoxyethanol. Methanol is the most preferred.

In regard to the preferably employed volatilizable hydrocarbon diluent, any inert liquid hydrocarbon material may be employed having boiling points substantially below the lubricating oil vehicle and the decompositon temperature of the reaction mixture.

Specifically, examples of such materials are heptane, isoheptane, benzene, toluene, xylene, and petroleum naphthas having a boiling point of between 65 and 1500C.

Typical tests on a naphthenic acid suitable for use in this invention are shown in Table I.

TABLE I Density (g cam~3) 0.9705 Gravity, API 14.3 Neut. No. 154 Sap. No. 142.9 Non Sap., Wt. % 19.2 Strong Acid No. None Mol. Wt., Calc. Neut. No. 362 Sulfate None TABLE II Bench scale preparation of overbased calcium soaps of naphthenic acids Overbasing Ratio' 4/1 6/1 8/1 10/1 10/1 Charge Stock -Wts., gm Naphthenic acid 362 181 181 181 181 Slaked Lime 185 129.5 166.5 203.5 203.5 Dehexanized raffinate gasoline 350 260 350 430 430 CH3OH 62 47 63 79 79 Diluent Oil 362 181 205 237 237 CO2 95 73 80 99 99 CO2/Ca(OH)2 mol ratio 2 1 1.1 0.9 0.9 0.9 Reaction Conditions Soap Formations Temp. "C 69.4-96.1 93.3-99 82.2-93.3 87.8-90.5 90.5 Time, hrs. 2 2 1 1.5 2 Mixed Speed, rpm 600 750 750 750 750 Overbasing Temp. "C. 60-69.5 60-65.5 57.2-60 57.2-60 57.2-6 CO2 Add'n. time, hrs. 2.5 1 1 1.1 0.9 Mixer Speed, rpm 2000 1900 2000 2000 2000 Product Yields, gm Crude overbased Soap 1180 794 999 1190 1214 Aqueous Overhead 6 1.4 1.3 0.3 0.1 Filtration Admix, gm 59 40 50 60 61 Filtrate, gm 847 562 663 723 824 Rate, m3/hrlm2 4.8 25.6 6 2 7.2 Throughput, m3/m2 9.2 6.4 8 8 9.2 Stripped Filtrate, gm 687 355 388 442 489 Product TBN 218 256 336 378 385 TBN, Calc. 297 379 420 455 455 % of Theory 73.4 67.5 80.0 83.1 84.6 Viscosity, 210 F, SUS 163.6 142.9 212.4 527.5 Appearance of 25% Blend in Sl.Haze Bright & Bright & Bright & solvent neutral oil Clear Clear Clear molts excess slaked lime charged/mol calcium naphthenate prepared 2Mols CO2/Mol excess slaked lime TABLE III Pilot unit preparations Charge Composition, wt. % Reactants Naphthenic Acid 12.7 12.7 Slaked Lime 28.4 28.4 CO2 6.5 6.5 Diluent Diluent Oil 16.7 16.7 Solvents Dehexanized raffinate gasoline 30.2 30.2 CH3OH (Absolute) 5.5 5.5 Total 100.0 100.0 Reaction Conditions Soap Formation Heat to Reflux, hrs 1.0 1.5 Temp, "C 37.7-77.8 41.7-92.2 Reflux Period, hrs 3;0 3.0 Temp, "C 77.8-88.3 41.7-96.7 Cooling to hrs 1.0 1.0 Carbonation CO2 Chg Time, hrs 4.5 35 Temp, "C 60-69 59-61 Bomb Filtration Data Rate, m3/hr/m2 Not Bomb 3.6 Throughput, m3/m2 Filtered 4.4 Sparkler Filtration Rate, kg/hr/m2 17.1 13.2 Throughput, kg/m2 53.7 73.7 Naphthenate Yield, kg. 6.08 6.81 Wt % basis Naphthenic Acid 148 166 TABLE IV Pilot unit product inspection test results Sp Gr 15.5/15.5"C 1.1734 1.1945 Viscosity, SUS 99"C 567 737 Flash, COC, "C 171 191 Color, ASTM D 1500 5.5 dil TBN 376 375 Calculated 455 455 TBN, % of Theory 82.6 82.4 Calcium, wt % 12.4 12.4 Calculated 16.2 16.2 Appearance, 25 vol. % Blend in solvent neutral oil Bright & Clear TABLE V Diesel cylinder oils composition and bench performance test results Composition, wt. % A B C D 68.8 65.1 71.1 E 0.5 0.5 0.5 F 1.0 1.0 1.0 G 9.8 9.8 9.8 H 3.4 3.4 3.4 I 6.5 6.5 6.5 J 10.0 K - 13.7 L 7.7 Sp. Grav., 15.5"/15.5"C 0.952 0.951 0.950 Kin. Vise at 99"C, Cs. 21.81 21.74 22.01 Total Base Number 66.0 69.6 70.0 6 Hr. 330 C Panel Coker Test Deposits, mg. 10.6 13.7 6.9 Color/Streaks 45/v.sl. 50/sl. 35/sl.

4-Ball E.P. Value, KG 60.5 69.4 68.7 Weld Pt, kg. 251 282 251 4-Ball Wear Test 5 Hr. 1800 RPM Scar Diam, mm Fresh 0.313 0.337 0.342 After Panel Coker 0.333 0.375 0.364 D - Lubricating Oil E - Zinc dialkyldithiophosphate F - B-hydroxyethylpolyisobutylene dithiophosphonate G - 55 wt % 10% CaCO3 overbased sulfurized calcium alkylphenolate 45 wt % mineral oil H - 50wt % of 2/1 CaCOX overbased sulfurized calcium alkyl phenolate and 50% diluent oil having an API gravity of 27.0 to 31 and an SUS viscosity of 96-104 at 37.8 C I - 60% Nominal 18:1 overbased calcium sulfonate 40% mineral oil - Overbased calcium naphthenate (TBN250) made by OSCA Kaguku K - Overbased calcium naphthenate (TBN207) made by Shell (N70C) L - Overbased calcium naphthenate of the invention Bench performance testing results Data on three diesel cylinder lubricants formulated using three different overbased naphthenates, Osca 255N Osca Kagaku Kogyo KK), Shell N-70C and-that of the invention (nominal 380 TBN) are presented in Table V. All finished lubricants were blended so as to exhibit a nominal Total Base Number of 70. The naphthenates of the invention had the following advantages: 1) Since higher TBN'S can be realized by employing the technology herein described, a low overbased naphthenate dosage is required when the instant composition is used (Formulation C. Table V).

2) The formulation of the invention (C) was definetely superior in the Panel Coker Test, both in the level of deposits observed and in used oil color.

3) The formulation of the invention (C) was superior in EP properties to the OSCA 255N containing formulation (A) and equivalent to the Shell N70C containing formulation (B).

WHAT WE CLAIM IS: 1. A method of preparing a clarified overbased metal naphthenate lubricating oil composition, which comprises contacting a reaction mixture containing: (i) a metal naphthenate having a metal ratio from 1 to 2 and derived from a naphthenic acid having a molecular weight from 230 to 600; (ii) from 1 to 10 moles of a metal hydroxide per mole of metal naphthenate; (iii) a hydrocarbon lubricating oil, in a weight ratio of oil: metal naphthenate (calculated as naphthenic acid) from 1:1 to 6:1, and (iv) an alcohol selected from alkanols and alkoxy-alkanols having 1 to 5 carbon atoms,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. TABLE V Diesel cylinder oils composition and bench performance test results Composition, wt. % A B C D 68.8 65.1 71.1 E 0.5 0.5 0.5 F 1.0 1.0 1.0 G 9.8 9.8 9.8 H 3.4 3.4 3.4 I 6.5 6.5 6.5 J 10.0 K - 13.7 L 7.7 Sp. Grav., 15.5"/15.5"C 0.952 0.951 0.950 Kin. Vise at 99"C, Cs. 21.81 21.74 22.01 Total Base Number 66.0 69.6 70.0 6 Hr. 330 C Panel Coker Test Deposits, mg. 10.6 13.7 6.9 Color/Streaks 45/v.sl. 50/sl. 35/sl. 4-Ball E.P. Value, KG 60.5 69.4 68.7 Weld Pt, kg. 251 282 251 4-Ball Wear Test 5 Hr. 1800 RPM Scar Diam, mm Fresh 0.313 0.337 0.342 After Panel Coker 0.333 0.375 0.364 D - Lubricating Oil E - Zinc dialkyldithiophosphate F - B-hydroxyethylpolyisobutylene dithiophosphonate G - 55 wt % 10% CaCO3 overbased sulfurized calcium alkylphenolate 45 wt % mineral oil H - 50wt % of 2/1 CaCOX overbased sulfurized calcium alkyl phenolate and 50% diluent oil having an API gravity of 27.0 to 31 and an SUS viscosity of 96-104 at 37.8 C I - 60% Nominal 18:

1 overbased calcium sulfonate 40% mineral oil - Overbased calcium naphthenate (TBN250) made by OSCA Kaguku K - Overbased calcium naphthenate (TBN207) made by Shell (N70C) L - Overbased calcium naphthenate of the invention Bench performance testing results Data on three diesel cylinder lubricants formulated using three different overbased naphthenates, Osca 255N Osca Kagaku Kogyo KK), Shell N-70C and-that of the invention (nominal 380 TBN) are presented in Table V. All finished lubricants were blended so as to exhibit a nominal Total Base Number of 70. The naphthenates of the invention had the following advantages: 1) Since higher TBN'S can be realized by employing the technology herein described, a low overbased naphthenate dosage is required when the instant composition is used (Formulation C. Table V).

2) The formulation of the invention (C) was definetely superior in the Panel Coker Test, both in the level of deposits observed and in used oil color.

3) The formulation of the invention (C) was superior in EP properties to the OSCA 255N containing formulation (A) and equivalent to the Shell N70C containing formulation (B).

WHAT WE CLAIM IS: 1. A method of preparing a clarified overbased metal naphthenate lubricating oil composition, which comprises contacting a reaction mixture containing: (i) a metal naphthenate having a metal ratio from 1 to 2 and derived from a naphthenic acid having a molecular weight from 230 to 600; (ii) from 1 to 10 moles of a metal hydroxide per mole of metal naphthenate; (iii) a hydrocarbon lubricating oil, in a weight ratio of oil: metal naphthenate (calculated as naphthenic acid) from 1:1 to 6:1, and (iv) an alcohol selected from alkanols and alkoxy-alkanols having 1 to 5 carbon atoms,

in a weight ratio of alcohol: metal naphthenate (calculated as naphthenic acid) from 1:2 to 1:6; with from 0.75 to 1.1 moles of carbon dioxide per mole of metal hydroxide at a temperature from 57 to 700C, allowing the mixture to stand for from 1 to 100 hours, filtering the mixture, and recovering the clarified overbased metal naphthenate lubricating oil composition from the resulting filtrate.

2. A method as claimed in Claim 1 wherein the reaction mixture also contains an inert, volatilizable hydrocarbon liquid diluent in a weight ratio of diluent: metal naphthenate reactant from 1:1 to 3:1.

3. A method as claimed in Claim 2 wherein the volatilizable liquid diluent is a dehexanized raffinate gasoline.

4. A method as claimed in any preceding claim wherein the alcohol is methanol.

5. A method as claimed in any preceding claim wherein the lubricating oil is a solvent neutral oil.

6. A method as claimed in Claim 1 and substantially as hereinbefore described.

7. A clarified overbased metal naphthenate lubricating oil composition when prepared by a method as claimed in any of the preceding claims.