US3062742A

US3062742A - Lubricating greases

Info

Publication number: US3062742A
Application number: US796775A
Authority: US
Inventors: Pethrick Samuel Richard; Groszek Aleksander
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1958-03-05
Filing date: 1959-03-03
Publication date: 1962-11-06
Anticipated expiration: 1979-11-06

Description

s,oo2,742 LUBRTCATING GREASES Samuel Richard Pethrick and Aleksander Groszek, Sun

United States Patent r 3,662,742 Patented Nov. 6, lfi2 ice metal alcoholate to form a metaloxy fatty acid ester, and hydrolizin-g the latter material with a metal hydroxide, e.g. in part or all of the oil to be thickened, the grease Thickening agent precursor.

bury-on Thanres, England, assignors to The British Pe- 5 am 1.

c g thereafter formed 1n known manner. A particular- 7 n! jtgtgilgusrtrciorcrggrgazfiitw, London, England, a Bmlsh 1y suitable ester is hydrogenated castor 011 which consists N Drawing Filed Mar. 3, 1959, Ser. No. 796,775 essentially of glyceryl tr1-l2-hydroxystearate. The use Claims priority, application Great Britain Man g of esters, such as hydrogenated castor 011, prov1des the 13 Claims. (CL 252 41) simplest and cheapest method of producing greases ac- 1O cording to the invention, but the use of fatty acids or Thi i ti l t t lubricating greases fatty acid soaps as starting materials has the advantage According to th invention a lubricating grease mthat the greases formed do not contain any glycerol which position comprises a lubricating oil thickened to a grease is present in greases prepared from hydrogenated caster consistency with a thickening agent comprising a metaloils. oxy fatty acid soap. The lubricating oil is preferably 15 The amount of soap present in the grease compositions amineral lubricating oil. according to the invention is preferably 5 to 30% by By metaloxy fatty acid soap is meant a fatty acid soap weight especially 8 to 15% by weight. in which at least one carbon atom of a hydrocarbon A number of thickening agents were prepared, by way chain (R) of the soap is attached to an oxygen atom of eXample,inthe following manner: which is also attached to metal. The said metal is pref- Thickening agent Pflicllfsofs S3 and 34 erably a metal which forms an alcoholate, especially a l 1 below) were p p from y y lithium, sodium, barium or aluminium. Where it is a hy r y the r of hy r g d a r polyvalent metal it may be attached via oxygen atoms il). The hydrogenated Cas r i Was Placed to more than one hydrocarbon radical of a soap. Th in a flask, fitted with a stirrer and thermometer, and said hydrocarbon radical or radicals may contain one melted. The calculated Weight of lithium or sodium was or more other substituent groups, e.g. a hydroxyl group. then added and the temperature raised until the reaction The fatty acid soaps arepreferably those of the formm n t pp ly n then kept at mula (RCOO) ,,X(OI-l) where R is a hydrocarbon or a temperature between 200 and 250 C. until the reaction substituted hydrocarbon radical, preferably having 1230 0 was complete.

carbon atoms; X is any soap-forming metal or group, Thickening agent precursor S5 was prepared by addespecially an alkali or alkaline earth metal, magnesium mg lithium ethoxide to molten hydrogenated castor oil. or aluminium, x is the valency of X and n is 0 or a num- The mixture Was heated with stirring at 200 C. and ber smaller than x. the alcohol forming in the course of the reaction was It is to be understood that the grease consistency may or allowed to distil off. The alcohol remaining in solution be obtained by the use of a mixture of different metalin the oil on completion of thereaction was removed oxy fatty acid soaps or a mixture of metaloxy soap and by the application of a vacuum. other soaps, e.g. hydroxy fatty acid soaps. Thickening agent S6 was prepared from l2-hydroxy v The thickening agent may conveniently be prepared by stearic acid and lithium. The reaction was conducted reacting a hydroxy fatty acid, or a soap thereof, with a 40 under nitrogen. Small proportions of finely dispersed metal or metal alcoholate. A particularly suitable hylithium were added to the molten acid which was maindroxy acid is IZ-hydroxy stearic acid. The products obtained at a temperature of 220 C. The mixture was tained in this way can be used directly for the preparation vigorously stirred throughout the addition until each porof greases by known methods, e.g. by heating a mixture tion had reacted completely. After the last portion of of oil and thickening agent to a temperature at which lithium had been added, the reaction was completed by complete solution takes place (usually about 200 C.) heating at 250-260 C. for 1 /2 hours. and thereafter cooling rapidly to room temperature. The reactants used, temperature of reaction and data Alternatively, the thickening agent may 'be formed-by"- on the products in each case are given in Table 1.

Table 1 Reaotants Used Temper- Setting Thickening aturc of Point of Agent 7 reaction, Product, Appearance of Product Remarks Metal Hydroxy Acid 0. C.

or Ester S1 Lithium, 1.88 g 400 g. H00... 230 Greenish brown, opaque, Reaction complete in 34 soft greasy material. hours.

S2 Lithium, 6.7 g 400 g. 1100... 230 170 Light brown, opaque,soft, Reaction not complete in '6 amorphous solid. hours of heating.

S3 Lithium, 3.6 g. 400 g. H00." .220 160 Lighfz ioaown, opaque, Reaction complete in 6-8 SO SO 1 01] S.

S4 Sodium, 0.8 g 400 g. HCO 210 150 Light brown, opaque, Reaction complete in 3-4 waxy solid. hours.

S5 Lithiumethoxido, 400 g. 1100... 200 Straw coloured moder- Do.

11.5 g. itchy soft, wax-like,

S6 Lithium, 2.8 g g. HSA... 220 190 Hardfhrittle, translucent Reaction begins at 0. solid, light brown in Most; of the lithium reacts colour. at 220 C. and the last traces of lithium are eliminated by heating to 250- 260 0.

'IZ-hydroxy stearic acid.

The products of the reactions were then used for the preparation of greases G1-G6 (see Table 2), the procedure being as follows:

G1, G2 and G4: A mixture consisting of 200 g. each of acid-treated mineral lubricating oils having Redwood 1 viscosities at 140 F. of 140 and 50 seconds respectively was heated to 75 C. 400 g. of the thickening agent were then added followed by 46.2 g. lithium hydroxide monohydrate dissolved in 400 ml. of water at 65 C. The mixture was gradually heated to 120 C., 800 g. of the same mixture of oils were added and the temperature raised to 137 C. Subsequently, a mixture consisting of 140 parts of 160/95 oil (160 Redwood 1 seconds at 140 F. and viscosity index of 95) and 560 parts of a bright stock oil (620 Redwood 1 seconds at 160 F. and viscosity index of 95) were added and heating was continued till approximately 170 C. was reached. The mixture was then cooled to 135 C., poured, and milled through a roller mill at 0.003 inch gap.

G3 and G5: The method was the same as for G1, G2 and G4 but the oil used had a Redwood 1 viscosity at 140 F. of 150 seconds.

G6: The thickening agent was dissolved with stirring in a lubricating oil having a Redwood 1 viscosity at 140 F. of 150 seconds. The solution was cooled rapidly to room temperature, milled as before and deaerated.

By way of comparison, a lithium 12-hydroxy stearate grease (G7) was prepared as follows:

G7: A mixture consisting of 200 g. each of acid treated mineral lubricating oils having Redwood 1 viscosities at 140 F. of 140 and 50 seconds respectively was heated to 75 C. 400 g. of hydrogenated castor oil were added followed by 58 g. of lithium hydroxide monohydrate dissolved in 600 ml. of water at 65 C. The heating was continued and the temperature of the mixture raised to 90 C. whereupon another 100 ml. of water were added. Themixture was heated to 120 C., 800 g. of the same mixture of oils were added and the temperature raised to 137 C. Subsequently a mixture consisting of 140 parts of 160/95 oil 160 Redwood 1 seconds at 140 F. and viscosity index of 95) and 560 parts of a bright stock (620 Redwood 1 seconds at 160 F. and viscosity index of 95) was added and heating continued till approximately 190 C. was reached. The mixture Was then cooled to 135 C., poured, and milled through. a roller at 0.003 inch gap.

The composition and properties of the greases are given in Table 2.

4 tion (GI-G6) have good drop points and consistency. They also have much improved resistance to bleeding than the lithium hydroxy stearate grease (G7). Greases G1-G6 also contain less soap than grease G7.

Greases G1-G6 all had a very good texture, G6 in particular being a very smooth grease.

A rig test was carried out on grease G4 at ambient temperature using a roller bearing, mm. x mm. x 46 mm., rotating at a speed of 2500 r.p.m. A load of 851 kg. was applied radially and the direction of rotation changed every 24 hours. The total time of the test was 200 hours. The bearing was tested for wear on the tracks, rollers and cage and the assembly was checked for absence of leakage of the grease. No adverse efiects were noted.

The same rig test was carried out on grease G6 but for a period of 667 hours. The result again was a very good pass.

We claim:

1. A method of preparing a lubricating grease in which a saponifiable hydroxy fatty acid ester is reacted with a metalating agent selected from the group consisting of the alkali metals and their alcoholates, to produce a metaloxy compound, and in which the said metaloxy compound is dissolved in a lubricating oil and saponified by reacting the solution with a soap-forming metal base whereby the lubricating oil is thickened to a grease consistency.

2. A method according to claim 1, in which the hydroxy fatty acid ester is a glyceride.

.3. A method according to claim 1, in which the lubricating oil is amineral oil.

-4. Amethod according to claim 1, in which the hydroxy fatty acid contains 12-30 carbon atoms.

5. A method according to claim 1, in which the soapforming metal base is an alkali metal base.

6. A method according to claim 5, in which the alkali metal base is lithium hydroxide.

7. A method according to claim 1, in which the hydroxy fatty acid ester is an ester of 12-hydroxy stearic acid.

8. A method according to claim 1, in which the hydroxy fatty acid ester represents 5-30% by weight of the final composition.

9. A method according to claim 1, in which the hydroxy fatty acid ester represents 815% by weight of the final composition.

Table 2 Components of Grease Properties of Greases Grease Penetration at 70 F. Bleeding Number Test Drop Thickening Oil, g. M011. 1120, (DTD 825). Point Agent g. 60 100,000 Oil loss: C.

Unworked Strokes Strokes percent weight 400 g. S1" 215 217 262 0.8 186 400 g. S2 171 163 228 0.2 191 400 g. S3 284 309 265 nil g. 220 225 276 1. 9 187 400 g. S5 218 219 262 0.2 188 S6 88 200 252 332 1.1 187 400 g. HCO* 2, 500 58 246 295 2. 4 190 Hydrogenated castor oil. Thickening agent precursor.

Penetration (IP method 50/56) is a measure of the 10. A method of preparing a lubricating grease in consistency of a grease. The Bleeding Test (Ministry of 70 which an ester of 12-hydroxy stearic acid is reacted with Supply Specification DTD 825A) indicates the tendency of the liquid phase (oil) to separate from the grease structure. Drop point (IP method 31/57) gives the temperature at which a grease becomes fluid.

It will be seen that the greases according to the invena metalating agent selected from the group consisting of lithium and its alcoholates, to produce a lithoxy compound, and in which the said lithoxy compound is dissolved in a lubricating oil and saponified by reacting the solution of lithoxy compound in lubricating oil with lithium hydroxide whereby the lubricating oil is thickened to a grease consistency.

11. A method according to claim '10, in which the ester of 12-hydroxy stearic acid is a glyceride.

12. A method of preparing a lubricating grease in which an ester of 12-hydroxy stearic acid is reacted with a metalating agent selected from the group consisting of sodium and its alcoholates, to produce a sodoxy compound, and in which the said sodoxy compound is dissolved in a lubn'cating oil and saponified by reacting the solution of sodoxy compound in lubricating oil with lithium hydroxide whereby the lubricating oil is thickened to a grease consistency.

13. A method according to claim 12, in which the ester of 12-hydroxy stearic acid is a glyceride.

6 References Cited in the file of this patent UNITED STATES PATENTS 2,445,935 Bondi July 27, 1948 2,469,041 Jones May 3, 1949 2,582,833 Hunn Jan. 15, 1952 2,651,616 Matthews et a1. Sept. 8, 1953 2,883,342 Sproule et a1. Apr. 21, 1959 2,890,232 Rogers et al. June 9', 1959 2,957,009 Holmguist et a1 Oct. 18, 1960 OTHER REFERENCES Organic Chemistry, Karrer, Elsevier Pub. Co., Inc., N.Y., London, 1947, page 84.