US3870642A

US3870642A - Grease thickened with oxygen-linked polyureas

Info

Publication number: US3870642A
Application number: US420004A
Authority: US
Inventors: Eberhard Gegner
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1972-12-11
Filing date: 1973-11-29
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11
Also published as: DE2260496B2; DE2260496C3; NL7316855A; FR2209831A1; GB1406553A; FR2209831B1; JPS49102708A; DE2260496A1

Abstract

Grease thickened with oxygen-linked polyureas.

Description

United States Patent [191 Gegner GREASE THICKENED WITH OXYGEN-LINKED POLYUREAS [75] inventor: Eberhard Gegner, Hamburg,

Germany [73] Assignee: The British Petroleum Company Limited, London, England [22] Filed: Nov. 29, 1973 [211 App]. No.: 420,004

[30] Foreign Application Priority Data Dec. 11. 1972 Germany 2260496 [52] US. Cl. 252/515 A, 252/403 [51] Int. Cl. C10m 5/20, ClOm 7/32,C10m 7/30 1 Mar. 11, 1975 Primary E.\'aminerDelbert E. Gantz Assistant Examinerl. Vaughn 1 ABSTRACT Grease thickened with oxygen-1inked polyureas.

31 Claims, No Drawings GREASE THICKENED WITH OXYGEN-LINKED POLYUREAS This invention relates to a process for the production of novel polyureas and to a process for the production of greases thickened by such polyureas.

Greases containing polyureas as thickeners have been disclosed. Thus, for example US. Pat. No. 3243372 describes greases containing polyureas of general formula X CO-Nl-lR NH---COl\lHR in which R and R represent monovalent and R and R represent divalent hydrocarbon radicals and X is an integer from I to 3.

Greases in accordance with US. Pat. No. 3 243 372 are produced by dissolving a di-isocyanate in the lubricating oil which is to be thickened, optionally by making use of a further solvent, adding amines to this mixture and then heating the total mixture, the polyurea being formed in situ.

Greases with polyureas as thickeners are chemically resistant to water and oxidation; they decompose under the action of heat only at relatively high temperatures.

Our copending British Pat. application No. 2774/73 corresponding to U.S. Pat. application Ser. No. 329,686 filed Feb. 5, 1973, discloses that diamines containing sulphur and mixtures of aliphatic and aromatic mono-amines may be used as the amine components for the production of polyureas in lubricating oils. Greases thickened with such polyureas are distinguished byimproved mechanical stability and increased load-bearing capacity.

It has now surprisingly been found that greases with still further improved properties are obtained if the polyureas used as thickeners and produced in situ from a mono-amino, a diamino and a di-isocyanate component contain in their chains oxygen bridges as structural elements, and are partially asymmetrical in relation to the nature of the terminal groups.

Greases with such polyureas as thickeners are chemically resistant to water, oxidation and the action of heat; they also possess good load-bearing capacity and mechanical stability. Furthermore they are distinguished by a reduced tendency to gel or harden.

The last mentioned property is of great importance for the satisfactory lubrication of bearings. Gelling or hardening caused by purely thermal influences is caused by a structural alteration in a grease. It is true that this alteration can sometimes be reversed by mechanical stress. If portions of grease, however, occur in a bearing subject to great thermal stress outside the ranges of mechanical stress, and should these portions then gel or harden as mentioned, there is a risk that insufficient grease may be supplied for lubrication. This can cause dry running and hence the destruction of the bearing concerned. This risk is considerably reduced, however, for bearings which are lubricated with a grease according to the invention.

Thus according to the present invention there is provided a process for the production of a polyurea which process comprises reacting a monoamino, a diamino and a di-isocyanate component at a temperature in the range 20 to lC wherein a. the monoamino component comprises a mixture of at least two members selected from different groups of general formulae:

in which R is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R2 is a monovalent aromatic radical, R is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R is a divalent aliphatic radical containing 2 to 4 carbon atoms,

b. the diamino component comprises a dioxa-alkane diamine or a mixture of dioxa-alkanediamines of general formula:

in which R and R are divalent aliphatic radicals containing 2 to 4 carbon atoms and R is a divalent aliphatic radical containing 2 to 10 carbon atoms, and

c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic diisocyanates.

According to a further feature of the invention there is provided a process for the production of a grease which process comprises reacting a monoamino, a diamino and a di-isocyanate component in a lubricating oil at a temperature in the range 20to 150C wherein (a) the monoamino component comprises a mixture of at least two members selected from different groups of general formulae:

in which R is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R is a monovalent aromatic radical, R is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R is a divalent aliphatic radical containing 2 to 4 carbon atoms.

' b. the diamino component comprises a dioxaalkanediamine or a mixture of dioxa-alkanediamines of general formula:

in which R and R are divalent aliphatic radicals containing 2 to 4 carbon atoms, and R is a divalent aliphatic radical containing 2 to 10 carbon atoms, and

c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic diisocyanates. The components are preferably reacted at a temperature of in the range 40 to C.

If desired the reaction mixture is then heated further to a temperature of to 200C, preferably to about C. By this treatment under controlled conditions an additional improvement of the properties of the greases ofthe invention is achieved, which presumably can be attributed to trans-amidation and cross-linking reactions in the polyureas.

According to a further advantageous feature of the invention the di-isocyanate component, optionally at a temperature which is above its melting point, or dissolved in lubricating oil or in a solvent which is inert under the reaction conditions, is added to the mixture of mono-amino and diamino components and the lubricating oil. The di-isocyanate component is thus exposed during the reaction to an excess of amines, as a result of which the degree of branching or cross-linking il'lZCll oin several atpha ac menwamineethens: astnoaw -.rminoi :eornpeaenit; :the compounds .c otresp mane menarmino coanponerat; :the :eornpoands correspondi g Q -:tlre molar ratio of; a1

err using r mite mono-amines 2 and; :an; :aliphaiie: mono-amiaw en ing Q he formulae 1605i); the; molar; 'Q of; are

arnin mine-ether or aliph tic mono-aminoethers as iltlififitifis amino-ether or several aliphatic mono-amino-ethers as mono'amino component, the compounds corresponding to the formulae given previously, the molar ratio of aliphatic mono-amine or mono-amines to aromatic mono-amines or mono-amines to aliphatic monoamino-ether or aliphatic mono-amino-ethers is preferably about l:O.5:O.5.

For the production of polyurcas according to the invention the aliphatic mono-amine in the mono-amino component is preferably a straight-chained monoamine with 16 to 24 carbon atoms per molecule, or a mixture of such mono-amines.

The aromatic mono-amine in the mono-amino component is preferably aniline, toluidine or xylidine or a mixture of these amines. isomeric aromatic monoamines can be used individually or as an isomer mixture.

The aliphatic mono-amino-ether of the general formula is preferably one in which R is a monovalent aliphatic radical containing 4 to 6 carbon atoms and R is a divalent aliphatic radical containing 2 or 3 carbon atoms. These mono-amino-ethers can be used separately or as mixtures.

The dioxa-alkanediamine of the general formula is preferably one in which R and R are divalent alialiphatic: monmatnine or; sev r l; an phatie' ntone-amines and :aln aroirniatiic: mono amine: or

several aromatic mono-amines and an aliphatic mono- :of thickener: has: been produce cl; than is later: desired :in: the finished grease according :to the: invention 15in: the range from: =by:weight; u: 1 Araf'Ji usual lubricating OE plybaSi e hf d rzic:aleohols.imay aiso ibe used: fortheiproduction :lewing pie in: i mipros/e boundary; lubrication:

; Suitably the iGOEEGCFIEFQEliGU of: thickener .1

. :bei Fzor ex d labricat' paraffin-teased =or:naphthene-;base

. flab polysiloxanes :er ester; '0.

by ireacting monobasic a he monohydric. ilifidfOi' arbexvliie acid =Tlte ventioni is diamine, 63.6 g Genamin 20/22 R 100 D(mixture or I I I I I I primary amines with chain lengths of C C and C in the ratio 4:39:54:3), 22.2 g p-toluidine and 1,500 g of a mixed-base solvent raffinate (l4E/50C corresponding to lO5 est/50C) was heated to 60C with stirring At this temperature the amines dissolved in the mineral oil to form a clear solution. With constant intensive stirring 72.0 g. of Desmodur T (mixture of 65% 2,4-toluylene di-isocyanate and 35% 2,6-toluylene dioisocyanate) was added dropwise over a period of H) minutes. The turbidity which immediately set in increased rapidly, and the contents of the reactor thickened. For rinsing, a further g of the same base oil was added to the feed vessel for the di-isocyanates. The reaction mixture was then heated with further stirring to C, and when this temperature was reached the mixture was cooled to 100C. A mixture of 10 g of Amine T (corrosion inhibitor by Ciba-Geigy). 20 g Additin 30 (oxidation inhibitor by Farbenfabriken Buyer). 2 g Reomet SBT (metal de-activator by Ciba-Geigyi and 168 g base oil were then added and the mixture stirred until cold. When cold the grease was homoge' nised in a colloid mill.

The molar ratio of the reaction components (monoamine ll: mono-amine 2:4.9-dioxadodecane-l, l2- diaminezdi-isocyanate) was 1:1:l:2.

. 511 9 ils which :are;

Thickener content of lubricant grease 10% Drop point (DIN 51 Km. Sheet l) 220C Worked penetration (DINN 5] 804 Sheet 2) 287 -Contmued Corrosion index according to Emcor Test (DlN 51 802) Thickener content of the grease 10% Oll p r n (1P 121/63 1.37: by wt. Drop point (DIN 51 801, Sheet 1) 203C Mechanical/Dynamic SKF test (DlN S1 806): Worked penetration (DlN 51 804 Sheet 2) 268 A run (2,500 r.p.m. without heating) passed Corrosion index according to Emcor Test B run (1,500 r.p.m., 130C) passed (DlN 51 802) 0 Oil separation (1P 121/63) 2.1% by wt. Mechanical/Dynamic SKF test (DIN 51 806): A run (2,500 r.p.m. without heating) passed B run (1,500 r.p.m. at 130C) passed EXAMPLE 2 A mixture of 41.5 g. of 4,9-dioxadodecane-l,l2- diamine, 62.4 g of Genamin 20/22 R 100 D, 21.8 g of p-toluidine and 1,500 g of a mixed-base solvent raffinate (14C/50C corresponding to 105 cSt/50C) was heated to 60C with stirring. The amines formed a clear solution with the mineral oil at this temperature. Maintaining constant stirring, 74.3 g of Desmodur T 65 were added dropwise over minutes. The turbidity which immediately set in increased rapidly, and the contents of the reactor thickened. For rinsing, a further 100 g of the same base oil were added to the feed vessel for the di-isocyanates. The reaction mixture was then heated with further stirring to 175C, and after reaching this temperature the mixture was cooled to 100C. A mixture of 10 g of Amine T, g of Additin 30, 2 g of Reomet SBT and 168 of base oil was then added, and the mixture stirred until cold. When cold the grease was homogenised in a colloid mill.

The molar ratio of the reaction components (monoamine l: monoamine 2:4,9-dioxadodecarie-Ll2- diaminezdi-isocyanate was 1:111:21.

Thickener content of the lubricant grease [0% Drop point (DIN .51 801. Sheet 1) 244C Worked penetration (DlN 51 804, Sheet 1) 305 Corrosion index according to Emcor Test (DIN 51 802) 0 EXAMPLE 3 A mixture of 41.2 g of 4,9-dioxadodecane-1,12- diamine, 62.0 g of Genamin 20/22 R 100 D, 26.5 g of butoxypropylamine and 1,500 g of a mixed-base solvent raffinate 114E/50C corresponding to 105 est/50C) was heated to 60C with stirring. The amines formed a clear solution with the mineral oil at this temperature. With constant intensive stirring 70.3 g of Desmodur T 65 was added dropwise over 10 minutes. The turbidity which immediately set in increased rapidly, and the contents of the reactor thickened. For rinsing, a further 100 g of the same base oil were added to the feed vessel for the di-isocyanates. The reaction mixture was then heated with further stirring to 175C. When this temperature was reached the mixture was cooled to 100C, and a mixture of 10 g of Amine T, 20 g of Additin 30, 2 g of Reomet SBT and 168 g of base oil was then added. The mixture was then stirred until cold. when cold the grease was homogenised in a colloid mill.

The molar ratio of the reaction components monoamino 1: mono-amine 2: 4.9-dioxaodecane -1, 12 diaminczdi-isocyanatc was 1:1:l22.

EXAMPLE 4 A mixture of 40.1 gv of 4,9-dioxadodecane-l .12- diamine, 60.3 g of Genamin 20/22 R D, 31.2 g of hexyloxy-propylamine and 1,500 g of a mixed-base solvent raffinate (l4E/50C corresponding to est/50C) was heated to 60C with stirring. The amines formed a clear solution with the mineral oil at this temperature. Maintaining constant intensive stirring, 68.4 g of Desmodur T 65 were added dropwise over 10 minutes. The turbidity which set in immediately increased rapidly and the contents of the reactor thickened. For rinsing a further 100 g of the same base oil were added to the feed vessel for the di-isocyanates. The reaction mixture was then heated with further stirring to 175C. After reaching this temperature the mixture was cooled to 100C and a mixture of 10 g of Amine T, 20 g of Additin 30, 2 g of Reomet SBT and 168 g of base oil were then added. The mixture was then stirred until cold. When cold the lubricant grease was homogenised in a colloid mill.

The molar ratio of the reaction components (monoamine l: monoamine 2:4,9-dioxadodecanel. 12- diaminezdi-isocyanate) was 1 l :1 :2.

Thickener content of the lubricant grease 10% Drop point (DlN 51 801, Sheet 1) 205C Worked penetration (DIN 51 804, Sheet 2) 265 Corrosion index according to Emcor Test (DlN 51 802) 0 Oil separation (1P 121/63) 1.771 by wt. Mechanical/Dynamic SKF test (DlN 51 806):

A run (2,500 r.p.m. without heating) passed B run (1,500 r.p.m. at C) passed 1 claim:

1. A process for the production of a grease which process comprises reacting a monoamino, a diamino and a di-isocyanate component in a lubricating oil at a temperature in the range 20to C wherein a. the monoamino component comprises a mixture of at least two members selected from different groups of general forumulae:

R]-NH2 R NH and R O-R NH in which R is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R is a monovalent aro matic radical, R is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R" is a divalent aliphatic radical containing 2 to 4 carbon atoms, b. the diamino component comprises a dioxaalkanediaminc or a mixture of dioxaalkancdiamincs of general formula:

NH -R O-R -OR NH in which R and R are divalent aliphatic radicals containing 2 to 4 carbon atoms, and R is a divialent aliphatic radical containing 2 to 10 carbon atoms, and

c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic diisoeyanates wherein the molar ratio between monoamino, diamino and di isocyanate components is in the range of 2:1:2 to 2:2:3.75.

2. A process according to claim 1 wherein the reac tion is carried out at a temperature in the range 40 to 70C.

3. A process according to claim 1 wherein the reaction mixture is subsequently heated to a temperature in the range 150 to 200C.

4. A process according to claim l wherein the di isocyanate component is added to a mixture of the monoamino and diamino components.

5. A process according to claim 4 wherein the diisocyanate component is added in molten form or dis' solved in a lubricating oil or an inert solvent.

6. A process according to claim l wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:112 to 211:2.5.

7. A process according to claim 1 wherein the molar ratio between monoamino, diamino and di-isocyanate compounds is in the range 2:2:3 to 212:3.75.

8. A process according to claim 11 wherein two monoamino compounds are present in a molar ratio of 1:1.

9. A process according to claim 11 wherein three monoamino compounds are present in a molar ratio of 1:05:05

10. A process according to claim 1 wherein the monoamino component comprises a monoamine of general formula R -NH in which R is a monovalent aliphatic radical containing 16 to 24 carbon atoms.

11. A process according to claim 1 wherein the monoamino component comprises an aromatic monoamine which is aniline, toluidine. xylidine. or a mixture thereof.

12. A process according to claim 1 wherein the monoamino component comprises a monoamine of general formula R O-R*NH in which R is a monovalent aliphatic radical containing 4 to 6 carbon atoms and R is a divalent aliphatic radical containing 1 or 3 carbon atoms.

13. A process according to claim 1 wherein the diamino component comprises a straight chain dioxa-alkane diamine of general formula NH -R"O--R OR- l ll-i in which R and R are divalent aliphatic radicals containing 2 or 3 carbon atoms and R is a divalent aliphatic radical containing 4 to 6 carbon atoms.

14-. A process according to claim 1 wherein the diisocyanate component comprises phenylene, toluyleneditolylene-, naphthylene. or diphenylmethane diisocyanate, or mixtures thereof.

15. A process according to claim 1 wherein the lubrieating oil is a mineral oil, a polyaryl ether. 21 polyalkylene glycol. a polysiloxane or an ester.

16. A process according to claim 15 wherein the mineral lubricating oil is a paraffinic or naphthenic lubricating oil fraction or a mixture thereof.

17. A process according to claim 11 wherein the grease contains 3 to 30% by weight of the polyurea.

11%. A grease composition comprising a lubricating oil thickened by 3-30% by weight of a polyurea formed in situ, said composition being formed by a process which comprises reacting a monoamino component and a diamino component with a di-isocyanate component in a lubricating oil at a temperature in the range 20to C wherein a. the monoamino component comprises a mixture ol at least two members selected from the following general formulae:

in which R is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R is a monovalent aromatic radical, R is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R" is a divalent aliphatic radical containing 2 to 4 carbon atoms,

b. the diamino component comprises a dioxa-alkane diamine or a mixture of dioxa-alkanediamines of the general formula: NH R --OR-OR- NH in which R and R are divalent aliphatic radicals containing 2 to 4 carbon atoms and R is a divalent aliphatic radical containing 2 to 10 carbon atoms, and

c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic di' isocyanates wherein the molar ratio of the monoamino, diamino and di-isocyanate components is in the range of 2:132 to 21213.75.

19. The composition of claim 18 wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:1:2 to 2:l:2.5.

20. The composition of claim 18 wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:2:3.75.

21. The composition of claim 18 wherein two monoamino compounds are present in a molar ratio of 1:1.

22. The composition of claim 18 wherein three monoamino compounds are present in a molar ratio of l:O.5:O.5.

23. The composition of claim 18 wherein the monoamino component comprises a monoamine of the general formula RNH in which R is a monovalent aliphatic radical containing 16 to 24 carbon atoms.

24. The composition of claim 18 wherein the monoamino component comprises an aromatic monoamine which is aniline. toluidine, xylidine, or a mixture thereof.

25. The composition of claim 18 wherein the monoamino component comprises a monoamine of the general formula R O-RNH in which R is a monovalent aliphatic radical containing 4 to 6 carbon atoms and R is a divalent aliphatic radical containing 2 or 3 carbon atoms.

26. The composition of claim 18 wherein the diamino component comprises a straight chain dioxa-alkane diamine of the general formula NH R"O-R- "'O-R NH in which R and R are divalent aliphatic radicals containing 2 or 3 carbon atoms and R is a divalent aliphatic radical containing 4 to 6 carbon atoms.

oil fraction or a mixture thereof.

30. The composition of claim 18 wherein the reaction is carried out at a temperature in the range 40 to C.

31. The composition of claim 18 wherein the reaction mixture is subsequently heated to a temperature in the range to 200C.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,870,6A2 DATED March 11, 1975 NVENTOWS) Eberhard Gegner It is certified that error appears in the ab0ve-identified patent and that saidLefters Patent are hereby corrected as shown below:

Column 1, line 16, "nm-co-mm should be ---mr-{-oo-- NHR111; line 11, C0" should be fl CO e Column 3,

7 line 29, "men-amino" should be ---rnr no-=-am:lno--1 v line 42,

"mono-amines or mono-amines" should be --mono-amine or mpn o amines--; line 66, O R.7 should be G--=R Column 4, line 4]., Column 5, line 49 and Column 6 line 17,, "MT/50C", each occurrence, should read -l4 Cj50-. Column 4, line 29, "plybasic" should be --polybasic=-;

line 47, "dioisocyanate" should be -di-isocyanate-=-; line 68,. "DINN" should be --DIN--. Column 5, line 40,. "DInY' should be "DIN"; line 67, "dioxao'decane" should be dioxadodecane--. Column 6, line 40, 265" should be moved to right column of chart. Column 7, line 4, "divia-" should be --diva- ---3 line 49, the number "1." should be -2--.

fiigned and fiealed this thirtieth Day of September 1975 [SEAL] RUTH C. MASON C. MARSHALL DANN A IIPXIIHX Off/(0r Commr'sxroner of Parenrs and Tradrmarkr UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,870,642 DATED March 11, 1975 INVENTOR(S) Eberhard Gegner It is certified that error appears in the above-identified patent and that saidLetters Patent I are hereby corrected as shown below:

Column 1, line 10, rm-co-mm should be --m1-(-oo-- mm line 11, co" should be aco Column 3, line 29, "mom-amino" should be "mono-amino; line 2, "mono-amines or: mono-amines" should be mono-amine or mpnoamines-; line 66, O )R,7 should be -G'-R Column 4, line 41, Column 5, line 49 and Column 6 line 17, "l4E/50C", each occurrence, should read --l4C/50C-. Column 4, line 29, "plybasic" should be --polybasic-; line 47, "dioisocyanate" should be --di-isocyanate-'; line 68, "DINN" should be --DlN--. Column 5, line A0, "DInY' should be -DIN--; line 67, "dioxaodecane" should be --di.oxadodecane--. Column 6, line 40, "265" should be moved to right column of chart. Column 7, line 4, divia-" should be -divaline 49, the number "1" should be --2--.

Signed and Sealed this thirtieth Day of September 1975 [SEAL] A Nest:

RUTH C. MASON Allvslrng Ofjr'rer C. MARSHALL DANN Commr'ssroner of Parents and Trudrmarkr-

Claims

1. A process for the production of a grease which process comprises reacting a monoamino, a diamino and a di-isocyanate component in a lubricating oil at a temperature in the range 20*to 150*C wherein a. the monoamino component comprises a mixture of at least two members selected from different groups of general forumulae: R1-NH2 R2-NH2 and R3-O-R4-NH2 in which R1 is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R2 is a monovalent aromatic radical, R3 is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R4 is a divalent aliphatic radical containing 2 to 4 carbon atoms, b. the diamino component comprises a dioxa-alkanediamine or a mixture of dioxa-alkanediamines of general formula: NH2-R5-O-R6-O-R7-NH2 in which R5 and R7 are divalent aliphatic radicals containing 2 to 4 carbon atoms, and R6 is a divalent aliphatic radical containing 2 to 10 carbon atoms, and c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic di-isocyanates wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range of 2:1:2 to 2:2:3.75.

2. A process according to claim 1 wherein the reaction is carried out at a temperature in the range 40* to 70*C.

3. A process according to claim 1 wherein the reaction mixture is subsequently heated to a temperature in the range 150* to 200*C.

4. A process according to claim 1 wherein the di-isocyanate component is added to a mixture of the monoamino and diamino components.

5. A process according to claim 4 wherein the di-isocyanate component is added in molten form or dissolved in a lubricating oil or an inert solvent.

6. A process according to claim 1 wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:1:2 to 2:1:2.5.

7. A process according to claim 1 wherein the molar ratio between monoamino, diamino and di-isocyanate compounds is in the range 2:2:3 to 2:2:3.75.

8. A process according to claim 1 wherein two monoamino compounds are present in a molar ratio of 1:1.

9. A process according to claim 1 wherein three monoamino compounds are present in a molar ratio of 1:0.5:0.5.

10. A process according to claim 1 wherein the monoamino component comprises a monoamine of general formula R1-NH2 in which R1 is a monovalent aliphatic radical containing 16 to 24 carbon atoms.

11. A process according to claim 1 wherein the monoamino component comprises an aromatic monoamine which is aniline, toluidine, xylidine, or a mixture thereof.

12. A process according to claim 1 wherein the monoamino component comprises a monoamine of general formula R3-O-R4-NH2 in which R3 is a monovalent aliphatic radical containing 4 to 6 carbon atoms and R4 is a divalent aliphatic radical containing 1 or 3 carbon atoms.

13. A process according to claim 1 wherein the diamino component comprises a straight chain dioxa-alkane diamine of general formula NH2-R5-O-R6-O-R7-NH2 in which R5 and R7 are divalent aliphatic radicals containing 2 or 3 carbon atoms and R6 is a divalent aliphatic radical containing 4 to 6 carbon atoms.

14. A process according to claim 1 wherein the di-isocyanate component comprises phenylene, toluylene-, ditolylene-, naphthylene, or diphenylmethane di-isocyanate, or mixtures thereof.

15. A process according to claim 1 wherein the lubricating oil is a mineral oil, a polyaryl ether, a polyalkylene glycol, a polysiloxane or an ester.

17. A process according to claim 1 wherein the grease contains 3 to 30% by weight of the polyurea.

18. A GREASE COMPOSITION COMPRISING A LILUBRICATING OIL THICKENED BY 3-30% BY WEIGHT OF A POLYUREA FORMED IN SITU, SAID COMPOSITION BEING FORMED BY A PROCESS WHICH COMPRISES REACTING A MONOAMINO COMPONENT AND A DIAMINO COMPONENT WITH A DI-ISOCYANATE COMPONENT IN A LUBRAICATING OIL AT A TEMPERATURE IN THE RANGE 20* TO 350*C WHEREIN A. THE MONOAMINO COMPONENT COMPRISES A MIXTURE OF AT LEAST TWO MEMBERS SELECTED FROM THE FOLLOWING GENERAL FORMULAE:

18. A grease composition comprising a lubricating oil thickened by 3-30% by weight of a polyurea formed in situ, said composition being formed by a process which comprises reacting a monoamino component and a diamino component with a di-isocyanate component in a lubricating oil at a temperature in the ranGe 20*to 150*C wherein a. the monoamino component comprises a mixture of at least two members selected from the following general formulae: R1-NH2 R2-NH2 and R3-O-R4-NH2 in which R1 is a monovalent aliphatic radical containing 12 to 24 carbon atoms, R2 is a monovalent aromatic radical, R3 is a monovalent aliphatic radical containing 2 to 10 carbon atoms and R4 is a divalent aliphatic radical containing 2 to 4 carbon atoms, b. the diamino component comprises a dioxa-alkane diamine or a mixture of dioxa-alkanediamines of the general formula: NH2-R5-O-R6-O-R7-NH2 in which R5 and R7 are divalent aliphatic radicals containing 2 to 4 carbon atoms and R6 is a divalent aliphatic radical containing 2 to 10 carbon atoms, and c. the di-isocyanate component comprises an aromatic di-isocyanate or a mixture of aromatic di-isocyanates wherein the molar ratio of the monoamino, diamino and di-isocyanate components is in the range of 2:1:2 to 2:2:3.75.

19. The composition of claim 18 wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:1:2 to 2:1:2.5.

20. The composition of claim 18 wherein the molar ratio between monoamino, diamino and di-isocyanate components is in the range 2:2:3 to 2:2:3.75.

22. The composition of claim 18 wherein three monoamino compounds are present in a molar ratio of 1:0.5:0.5.

23. The composition of claim 18 wherein the monoamino component comprises a monoamine of the general formula R1-NH2 in which R1 is a monovalent aliphatic radical containing 16 to 24 carbon atoms.

24. The composition of claim 18 wherein the monoamino component comprises an aromatic monoamine which is aniline, toluidine, xylidine, or a mixture thereof.

25. The composition of claim 18 wherein the monoamino component comprises a monoamine of the general formula R3-O-R4-NH2 in which R3 is a monovalent aliphatic radical containing 4 to 6 carbon atoms and R4 is a divalent aliphatic radical containing 2 or 3 carbon atoms.

26. The composition of claim 18 wherein the diamino component comprises a straight chain dioxa-alkane diamine of the general formula NH2-R5-O-R6-O-R7-NH2 in which R5 and R7 are divalent aliphatic radicals containing 2 or 3 carbon atoms and R6 is a divalent aliphatic radical containing 4 to 6 carbon atoms.

27. The composition of claim 18 wherein the di-isocyanate component comprises phenylene, toluylene-, ditolylene-, naphthylene, or diphenylmethane di-isocyanate, or mixtures thereof.

28. The composition of claim 18 wherein the lubricating oil is a mineral oil, a polyaryl ether, a polyalkylene glycol, a polysiloxane or an ester.

29. The composition of claim 28 wherein the mineral lubricating oil is a paraffinic or naphthenic lubricating oil fraction or a mixture thereof.

30. The composition of claim 18 wherein the reaction is carried out at a temperature in the range 40* to 70*C.