US3827980A - Tertiary diamide based grease - Google Patents

Abstract

NOVEL GREASE COMPOSITIONS CONTAINING MAJOR AMOUNTS OF LIQUID TERTIARY DIAMIDES HAVING THE FOLLOWING STRUCTURAL FORMULA:

R''-N(-CH3)-CO-(CH2)N-CO-N(-CH3)-R''

WHEREIN

R'' = CH3-(CH2)M-CH(-R)-(CH2)X-

WHEREIN R=N, ALKYL RADICAL HAVING C1-C5, M= 2-8, X= 1-5 ARE DISCLOSED. THESE GREASES ARE USEFUL IN A HIGH AND/OR LOW TEMPERATURE ENVIRONMENT.

Description

United States Patent Oflice 3,827,980 Patented Aug. 6, 1974 3,827,980 TERTIARY DIAMIDE BASED GREASE Robert M. Thompson, Wilmington, Del., and Alfred F. Talbot, Wallingford, Pa., assignors to Sun Research and Development Co., Philadelphia, Pa. No Drawing. Filed Oct. 2, 1972, Ser. No. 293,983 Int. Cl. Cltlm 7/34 U.S. Cl. 252-28 9 Claims ABSTRACT OF THE DISCLOSURE Novel grease compositions containing major amounts of liquid tertiary diamides having the following structural formula:

wherein R=H, alkyl radical having C -C m=2-8, x: 1-5

are disclosed. These greases are useful in a high and/or low temperature environment.

CROSS-REFERENCE TO RELATED APPLICATIONS This invention is related to those described in the following listed applications:

Serial number Inventors 293,979 -R. M. Thompson. 293,980 R. M. Thompson. 293,981 R. M. Thompson. 293,982 R. M. Thompson. 293,984 R. M. Thompson.

and F. E. Didot.

All of the aforementioned applications filed the same date as this application. The first and second of the aforementioned applications relate to classes of novel diamides, the third and fourth relate to the use of tertiary diamides as lubricants, the fifth to the use of tertiary diamides as swelling agents.

SUMMARY OF THE INVENTION This invention pertains to a novel grease containing a major amount of a liquid tertiary diamide having the formula:

and about 5-45 weight percent of a thickening agent and a minor amount of grease additive. The thickening agent can be one of the following: a saponifiable fatty material and a saponifying agent, preformed soap; the non-soap thickeners; i.e., inorganic gel and modified clay. The grease has particular utility in a high and/or low temperature environment.

DESCRIPTION OF THE INVENTION It has now been discovered that a lubricating grease containing certain liquid tertiary diamides as a liquid lubricant is useful in a high and/or low temperature environment.

These diamides have the following general structural formula:

CH. CH;

wherein H R=CHa-( Hi)m (CHz) wherein R=H, alkyl radical having C -C m=28, x: 1-5.

The normal parafiinic diacid of equation (1) can contain 6-14 carbon atoms; preferably 8-12. Accordingly n of the diacid of equation (1) equals 4-12, preferably 6-10. Examples of such acids are suberic, azelaic and sebacic. The secondary amine of equation (1) contains a methyl and R. The latter,

wherein x=1-5, R=H or an alkyl radical containing C -C and m=2-8. A preferred R is one wherein x=l; more preferably 10:1 and R=H and m=3-6. Preparation of primary and secondary amines and the physical and chemical properties of the amines are given in Kirk- Othmer, Encyclopedia of Chemical Technology, 2nd edition, volume 2, Amines (Survey).

Another method involves reacting a normal paraflinic diacylhalogen, e.g. a diacylchloride, with a secondary amine wherein one radical is a methyl. This general reaction is illustrated by the following equation:

C10 0 (CHz)nC 0 C1 ZR'NHCH:

R'IIICO (CHDnCOIFIR' 2H0l CH3 CH3 In equation (2) n, as in equation (1), equals 4-12; preferably 6-10. R is the same as in general equation (1).

The lubricating grease of present invention is a solid or semi-fluid lubricant consisting of the aforementioned liquid lubricant and a thickening agent and an additive. The grease contains a major amount of the tertiary diamide; i.e., 50% or more.

The thickening agent can be one of the following: saponifiable fatty matter and a saponifying agent, preformed soap, inorganic gel and modified clay. The saponifiable fatty matter can be a fat or oil of animal, vegetable or marine origin. Also, the saponifiable fatty matter can be the fatty acid mixture obtained via splitting a fat. Furthermore, the fatty matter can be the fatty acid obtained via chilling and pressing a distilled fatty acid or obtained via fractional distillation and solvent crystallization. The fatty acid can also be modified via hydrogenation. Examples of suitable saponifiable fatty materials are hydrogenated castor oil, hydrogenated triglycerides of ricinoleic acid, hydrogenated ricinoleic acid, hydroxystearic acids and, in particular, l2-hydroxystearic acid, methyl or ethyl esters of hydroxystearic acid and, in particular, the methyl or ethyl ester of l2-hydroxystearic acid. The saponifying agent is the material which reacts with the aforementioned fatty materials to form a soap. The agent is normally an alkali. Examples of such alkalies are hydrated lime, calcium hydroxide, calcium oxide, calcium carbonate, caustic soda, sodium hydroxide, sodium oxide, sodium carbonate, barium hydroxide, lithium hydroxide, lithium oxide and lithium carbonate.

A preformed soap can be used in place of the saponifiable fatty matter and a saponifying agent. Use of a preformed soap in grease manufacture has the advantage of eliminating the saponification step. One class of preformed soaps are also referred to as metallic stearates. Included in the latter, in addition to calcium, lithium, barium, and sodium stearates, are aluminum, magnesium and zinc stearates. Preformed soaps also include metallic hydroxystearates such as lithium 12-hydroxystearate.

Non-soap thickeners, as used herein, refers to inorganic gels and clay derivatives. One well known example of an inorganic gel is colloidal silica; many others are listed and described in Manufacture and Application of Lubricating Greases, C. I. Boner, Library of Congress Catalog Card No. 541103l. Clay derivatives refer to chemical or physically modified clays, usually a natural clay. Organophilic bentonite is one well known family of clay derivatives and it is described in detail in the aforementioned reference.

The additives can be dyes, anti-oxidants, rust inhibitors, extreme pressure agents, odorizers and fillers. The latter includes graphite, asbestos, metal oxides, powdered metals, metal sulfides and carbon black.

The advantages of a grease composition containing a tertiary diamide compared to a petroleum lubricant based grease is that the former has superior physical properties at low temperature, e.g. 20 F. or at high temperature, e.g. 400 F. For example, as discussed in greater detail in Example 2, a tertiary diamide based grease had substantially the same physical properties at 20 F. as it did at room temperature; i.e., about 70 F. By comparison, the petroleum based grease showed substantial inferior differences in physical properties at 20 F. compared to its properties at room temperature. As to oxidative high temperature performance, the tertiary diamides based grease, for example, after being subjected to 400 F. for 70 hours suffered less weight loss than a comparative petroleum based grease. This last comparison is discussed in greater detail in Example 3.

The examples hereinafter describe how these diamide greases were prepared and their physical properties as well as comparisons with similar petroleum based greases.

EXAMPLES The procedure for making the greases shown in the accompanying table was as follows:

Example 1 92.4 parts by weight of the N,N'-dimethyl-N,N'-dioctylazelamide and 7.6 parts by weight of lithium IZ-hydroxystearate were placed in an open container. The resulting mixture was heated and agitated until the soap melted.

After the melting occurred, the homogeneous'mixture was agitated for about 5-10 minutes and then the mixture, with continued agitation, was rapidly cooled. Using the same procedure, but substituting a petroleum liquid for the diamide liquid, a petroleum lubricating grease was made. The consistencies of the two greases are shown in the accompanying Table.

The aforementioned diamide is a water-white liquid at ambient temperature. Its kinematic viscosities were 12.36 centistokes at 210 F. and at F. a calculated 108.5 centistokes. It has a boiling point of 176 C. at 0.17 mm. Hg.

The aforementioned petroleum lubricant is known also as Sunvis 51. Its kinematic viscosities are typically 11.4 centistokes at 210 F. and 109.6 centistokes at 100 F. It normally has an API gravity at 60 F. of 30.0.

Example 2 90.8 parts by weight of the diamide used in Example 1, and 9.2 parts by weight of lithium stearate were placed in an open container. The resulting mixture was heated and agitated until the soap melted. After the melting occurred, the molten mixture was agitated for about 5-10 minutes and then the mixture, with continued agitation, was rapidly cooled. Using the same procedure, but substituting the petroleum liquid of Example 1 for the diamide liquid, a petroleum lubricating grease was made. The consistencies of the two greases are shown in the Table.

The low temperature properties of the two different greases prepared in the previous paragraph were determined in the following manner. Equal weights of the two different greases were placed in separate testing devices. The devices were suspended in a constant temperature bath maintained at 20 F. After 20 minues, both were removed and examined visually for any change in consistency.

The petroleum based grease had become considerably harder than it had been at room temperature. Although the grease was still stringy, the strings that pulled away from the bulk of the grease were very short.

In contrast, the diamide based grease was only slightly more firm than it had been at room temperature. Also, it showed about the same degree of stringiness; i.e., as to length and number of strings, as it had at room temperature.

This low temperature comparison of the two greases indicates the superiority of the diamide grease over a petroleum based grease at 20 F.

Example 3 70 parts by weight of the diamide used in Examples 1 and 2 and 30 parts by weight of organophilic bentonite were placed in a container and agitated until smooth. Subsequently, a volume of acetone equivalent to one half of the total volume of the mixture was added to the mixture of the bentonite and diamide and agitation resumed. Shortly thereafter, the acetone completely evaporated and the grease examined as to consistency. The acetone was added to assist the taking up of the diamide by the bentonite.

The petroleum lubricating grease was prepared in the following manner. 69.7 parts by weight of the petroleum lubricant used in Example 1 was placed in a container along with some naphtha diluent. Also, 31.7 parts by weight of organophilic bentonite was added to the mixture in the container. The resulting three-component mixture was agitated until the naphtha evaporated. After the evaporation, a trace of iso-propanol was added to the mixture to assist in the taking up of the diamide by the bentonite. Also, for the same aforementioned reason, shortly thereafter, a volume of acetone, equal to one half of the volume of the total volume of the mixture, was added to the mixture of bentonite and lubricant. After the acetone evaporated, the grease was examined as to consistency.

The consistencies of the two greases made with the bentonite are shown in the Table.

The high temperature-oxidative properties of the two different greases prepared in the previous paragraph were determined in the following manner. Equal weights of the two different greases were placed in separate testin containers. These uncovered containers were placed in a circulating air oven maintained at 400 F. for 70 hours. Afterwards, the greases were removed and examined.

The petroleum based grease suffered a 25 weight percent loss. The remaining materials were black, friable, lumpy solids.

In contrast, the diamide based grease suffered a 19.6 weight percent loss. The remaining material was a black, hard, lumpy solid.

This high temperature-oxidative comparison of the two greases indicates the superiority of the diamide grease over a petroleum based grease at 400 F.

Example 4 80 parts by weight of the diamide used in Examples 1-3 were placed in an open container along with 20 parts of colloidal silica and a volume of naphtha equal to five times the volume of the diamide. The contents of the container were agitated at ambient temperature until homogeneous. Afterwards, the container was heated slightly to expel the naphtha. The same procedure was followed using the petroleum liquid of Examples 1-3 as a replacement for the diamide liquid. However, the result was dry granules rather than a grease-like product. By comparison, the diamide lubricating grease was grease-like and very thick.

Example 5 80 parts by weight of N,N-dimethyl-N,N-di-2-ethylhexylsebacamide and 20 parts by weight of colloidal silica were placed in an open container along with some naphtha diluent. The three-component mixture was agitated until a smooth uniform mix was obtained. The naphtha was allowed to slowly evaporate, after which the grease was examined as to consistency. The results of this examina- 40 tion are shown in the table.

The diamide used in Example 5 is a water-white liquid at ambient temperature. Its kinematic viscosities were 10.05 centistokes at 210 F. and 109.7 centistokes at 100 F. Its boiling point was 220 C. at 0.7 mm. Hg.

Greases prepared from tertiary diamides, other than those used in the examples, will have analogous physical properties as well as greases containing thickening agents other than those used in the examples.

TABLE Comparison of greases prepared with petroleum or diamide lubricant Consistency of grease weight percent in grease-like. Pet, 30 weight percent in 'amide). (4) Colloidal silica (20 Dry granu1es....;. Very thick,

weight percent). grease1ike. (5) do do Moderately firm,

smooth, greaselike, tends to lump.

1 The diamide was N,N-dimethyl-N,N-dioctylazela.mide.

2 The diamide was N,N-dimethyl-N,N-di-2-ethylhexylsebaeannde.

3 SUNVIS 51, a petroleum lubricating oil having a viscosity at room temperature similar to the wscosity of the diamides used.

6 What is claimed is: 1. A lubricating grease composition consisting essen tially of: i (a) a major amount of a tertiary diamide having the formula:

wherein wherein R=H, alkyl radical having C -C m=28, x=1-5;

(b) about 5-45 Weight percent of a thickening agent selected from the group consisting of saponifiable fatty matter and a saponifying agent, preformed soap, inorganic gel, and modified clay; and

(c) a minor amount of grease additive.

2. Composition according to Claim 1 wherein the diamide is N,N'-dimethyl-N,N-dihexylazelamide.

3. Composition according to Claim 1 wherein the diamide is N,N'-dimethyl-N,N-dioctylazelamide.

4. Composition according to Claim 1 wherein the diamide is N,N'-dimethyl-N,N'-di-Z-ethylhexylazelamide.

5. Composition according to Claim 1 wherein the diamide is N,N'dimethvl-N,N'-di-2-ethylhexylsebacamide.

6. Composition according to Claim 1 wherein the preformed soap is a metallic stearate.

7. Composition according to Claim 1 wherein the inorganic gel is a colloidal silica.

8. Composition according to Claim 1 wherein the modified clay is an organophilic bentonite.

9. Composition according to Claim 1 wherein the thickening agent is selected from the group consisting of lithium 12-hydroxystearate, lithium stearate, organophilic bentonite, and colloidal silica; and the tertiary diamide is N,N'-dimethyl-N,N-dioctylazelamide.

References Cited UNITED STATES PATENTS 4/1967 Low et a1 252-515 A 7/1971 Coshburn 252-515 A US. Cl. X.R. 252-42.4, 51.5 A