US3065177A

US3065177A - High temperature greases

Info

Publication number: US3065177A
Application number: US14514A
Authority: US
Inventors: Bruce W Hotten
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1960-03-14
Filing date: 1960-03-14
Publication date: 1962-11-20
Anticipated expiration: 1979-11-20

Description

3,065,177 Patented Nov. 20, 19162 seesaw HIGH TEMPERATURE GREASES Bruce W. Hotten, Grinds, Calh'r'., assignor to Caiiiornia Research orporation, San Francisco, tCaiiil, a corporation oi Delaware No Drawing. Filed Mar. 14, 1960, get. No. 1 3 524 5 Claims. (Cl. 252--49.6)

This invention relates to lubricating greases. More particularly, it relates to lubricating oil compositions composed of an oil of lubricating viscosity thickened by a thickening agent to grease-like consistency, such grease. being characterized by high melting points and wherein the thickening agent is nonmetallic.

This application is a continuation-impart of Hotten patent application Serial No. 606,993, filed August 30, 1956, and now abandoned.

It is prevailing practice to use salts of certain fatty acids or other suitable acids and certain metals to produce high melting point greases. Thus, sodium and lithium stearates, also sodium and lithium salts of cer tain mono-amides of polycarboxylic acids are employed as thickeners to produce high melting point greases. Metal salt thickeners are disadvantageous, however, because the metals therein promote oxidation.

Although nonmetalcontaining grease thickening agents have been proposed hereto-fore, most of these do not produce grease compositions having high dropping points (ASTM method D566-42).

It is an object of the present invention to provide greases having hi h dropping points and in which the thickeners are of the nonmetallic type.

It is a particular object of the invention to provide greases having dropping points in the neighborhood of 400 F. or more, preferably 500 F. or more, and wherein the thickeners are nonmetallic.

Yet another object of the invention is to provide novel compounds which can be prepared economically, which are nonmetallic in nature and which are useful, among other things, as grease thickeners.

These and other objects of the invention will be ap parent from the ensuing description and the appended claims.

In accordance with the present invention, it has been discovered that high melting grease compositions are obmined by incorporating in certain polysiloxane base oilsby the formula 1 ll II I (Rh H O O H wherein the Rs are alkyl radicals containing from 1 to 3 carbon atoms, and n is a number from to 1.

Esters of terepnthalarnic acids which are contemplated herein in combination with terephthaldiamides include those of the formula wherein represents hydrogen or the methyl or ethyl radicals, and R is an alkyl radical containing from 1 t0 2 carbon atoms.

The preferred diamides of terephthalic acid are those having the type formula The combination of terephthaldiarnides and terephthalamic acids or their esters effectively thickens to grease consistency certain methyl, phenyl polysiloxanes. These oils are characterized as polymethylphenylsiloxanes having a medium methyl-phenyl ratio. As determined by the infrared analysis procedure described in Naval Research Laboratory Report, P-2746 (1946), by Smith, French and ONeil, the methylphenyl ratios are evaluated according to the peaks observed in the infrared analysis; these ratios have values from 0.3 to 0.5; that is. the methyl radicals and the phenyl radicals are present in the polyrnethylphenylsiloxane in proportions such that the ratio of methyl radicals to phenyl radicals has values from 0.3 to 0.5, based on infrared analysis.

The combination of terephthaldiami es and terephthaiarnic acids (or esters th reof) is used in amounts of 15%, by weight, to 50%, preferably 20% to 30%. The weight ratio of tcrephthaldiarnides to terephthalamic acids (or esters thereof) is from 1:4 to 1:1.

The thickener combination of the invention may be incorporated in such base oils in varying amounts. Where a high dropping point is not important, the combination may be used in amounts as low as 5%, or less may be employed, but "t /here high dropping points (i.e., about 500 F. or higher) are desired, larger amounts of thickener combination should be employed, for example, or higher, all such percentages being by weight based on the finished grease. It is preferred to use no more than 30%. All percentages are by weight based on finished product.

The following specific examples will serve to illustrate the practice and advantages of the invention.

EXAMPLE I 5 Mixture of N,N'-Di-p-Tolylterepht/mldiamide and N-Zolylterephthalamic Acid 1284 grams (l2 mols) of p-toluidine and 582 grams (3 mols) of dimethyl terephthaiate were heated and stirred together at l70210 C. for 6 hours. The prodnot was washed three times with boiling benzene and was dried. A yield of 733 grams was obtained consisting of one-half N,N-di-p-tolyiterephthaldiamide and one-ha1f N-tolylterephthalarnic acid having the following formulas:

N,N-di-p-tlylterephthaldiamide HO-CO-QCO-NH-Q-Olia N-tolylterephthalamic acid The saponification number of the product was 154 and nitrogen content was 6.54%.

EXAMPLE II and 500+ F.; worked pentration (P of 348; and a high speed bearing life of 510 hours (average of two runs, 354 and 665 hours) at 450 F. and of 307 hours (average of two runs, 212 and 401 hours) at 500 F. The high speed bearing life test (quoted as MILG25013) was run as follows:

A 204K Conrad type 8-ball bearing packed with grease was operated at 10,000 rpm. continuously for 22 hours at the designated temperature. The bearing was then cooled to room temperature during a period of 2 hours, 'then run at 10,000 r.p.m. for another 22 hours. This cycle was repeated until the bearing failed.

Other greases containing thickener combinations of this invention are illustrated, together with test results, in Table I hercinbelow. The compositions were blended and treated by processes similar to those set forth in E ample II hereinabove.

The base oil in each of the compositions A, B, C, D and E was a polymethylphenylsiloxane wherein the methyl-phenyl ratio had a value of 0.4 (based on infrared It will, therefore, be apparent that nonmetallic grease thickeners described herein form greases which are characterized by high dropping points and, in many cases by exceptionally high dropping points. The latter characteristic is highly advantageous in view of the fact that the thickeners are nonmetallic.

Such greases may include other ingredients, such as oxidation and/ or corrosion inhibitors, etc.

I claim:

1. A grease composition comprising a major proportion of a polysiloxane base oil of lubricating viscosity and, in an amount sufficient to thicken said oil to the consistency of a grease, the combination of a terephthaldiamide having the type formula in M wherein the Rs are alkyl radicals containing from 1 to 3 carbon atoms, and n is a number from 0 to 1, and a compound of the formula wherein R is selected from the group consisting of hydrogen and alkyl radicals containing from 1 to 2 carbon atoms, and R is an alkyl radical containing from 1 to 2 carbon atoms, wherein said polysiloxane is a polymethylphenylsiloxane wherein the methyl-phenyl ratio has values from 0.3 to 0.5, and the weight ratio of terephthaldiamide to said compound is from 1:4 to 1:1.

2. A grease composition consisting essentially of a polymethylphenylsiioXane base oil and, from to by weight, of the combination of a terephthaldiamide of the formula h o in).

wherein the Rs are alkyl radicals containing from 1 to 3 TABLE I Amount, ASTM Bearing Composition Wt. Appearance Dropping P Life Percent Point, (Hours) a ass i 5 (b) Terephthalyl-di-p-toluidide 25 i B (a) Base Oil 75 do (b) Methyl,N-p-tolylterephthalamate 25 O (a) Base Oil 75 (b) Terephthalyl-di-p-toluidide. 12.5 Smooth Grease 494 382 l 529 (c) Methyl,N-p-tolylterephthalarnat 12.5

D (a) Base Oil 75 (b) Terephthalyl-di-p-toluidide do 500 348 l 307 (c) N-p-tolylterephthalamic acid 12.5

E (a) Base Oil 75 (b) Terephthalyl-di-p-toluidide- 18.75 d0 367 (c) N-tolylterephthalamic acid 6.25

F (a) Base oil 75 (b) Terephthalyi-di-p-toluidide 125 do 404 (c) N-p-tolylterephthalamie acid 12.5

1 Average of 2 runs.

carbon atoms, and n is a number from 0 to 1, and a compound of the formula wherein the Rs are alkyl radicals containing from 1 to 3 carbon atoms, and n is a number from 0 to 1, and a compound of the formula wherein R is selected from the group consisting of hydrogen and alkyl radicals containing from 1 to 2 carbon atoms, and R is an alkyl radical containing from 1 to 2 carbon atoms, wherein the methyl-phenyl ratio of said polysiloxane has values from 0.3 to 0.5, and wherein the weight ratio of said terephthaldiamide to said compound is from 1:4 to about 1:1.

4. A grease composition comprising a major proportion of a polymethylphenylsiloxane base oil, and from 20% to 30%, by weight, of the combination of a terephthaldiamide of N,N-di-p-to1yltercphthaldiamide and N- tolylterephthalamic acid, wherein the terephthaldiamideterephthalamic acid weight ratio is from 1:4 to 1:1.

5. A grease composition comprising a major proportion of a polymethylphenylsiloxane base oil, and from 20% to 30%, by weight, of the combination of equal parts, by weight, of N,N'-di-p-tolylterephthaldiamide and N- tolylterephthalamic acid, wherein the methyl-phenyl ratio of said polymethylphenylsiloxane has values from 0.3 to 0.5.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. A GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A POLYSILOXANE BASE OIL OF LUBRICATING VISCOSITY AND, IN AN AMOUNT SUFFICIENT TO THICKEN SAID OIL TO THE CONSISTENCY OF A GREASE, THE COMBINATION OF A TEREPHTHALDIAMIDE HAVING THE TYPE FORMULA