US2841555A - Metal nu-acyl sarcosinate thickened lubricating oils - Google Patents

Description

United States PZIt -t METAL N-ACYL SARCOSINATE THICKENED LUBRICATIN G OILS Joseph F. Lyons, Wappingers Falls, and Paul R. Thomas, Beacon, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application March 2, 1956 Serial No. 568,993

6 Claims. (Cl. 25233.6)

This invention relates to lubricating greases containing a novel thickener which also functions as an antioxidant and antirustagent.

The grease compositions of this invention comprise an alkali metal or alkaline earth metal salt of an N-C C acyl sarcosine as a thickening agent and an oleaginous lubricating base. The greases of this invention comprise 10 to 40 weight percent N-acyl sarcosine salt and 60 to 90 weight percent oleaginous lubricating base. Conventional grease additives, such as stabilizers, E. P. agents, etc., may also be added to the grease compositions of this invention.

The grease compositions of this invention display good oxidation resistance and antirust properties. As a consequence, these greases find particular application in the lubrication of marine machinery.

Sarcosine is N-methyl glycine. N-acyl sarcosines have the general formula RCONCHtCOOH wherein R is an aliphatic hydrocarbon radical. The N-acyl sarcosines whose salts are used as thickening agents contain 10 to 24 carbon atoms in the R component of the foregoing formula. Examples of N-acyl sarcosines used as thickening agent precursors are illustrated by the following: N-lauroyl sarcosine, N-stearoyl sarcosine, N-caproyl sarcosine, N-myristoyl sareosine, N-oleoyl sarcosine, N-palmitoyl sarcosine, and N-arachidoyl sarcosine.

The N-C C -acyl Sarcosine salts are generally formed in situ during the grease preparation which is conventional. The N-acyl sarcosine is saponified with alkali metal or alkaline earth metal hydroxide in a portion of the oleaginous lubricating base. The mixture of sarcosine salt and lubricating oil is dehydrated and subsequently brought to the desired consistency by the addition of further quantities of lubricating base. The details of preparation will be shown in the subsequent examples.

The N-acyl Sarcosine salts constitute 10 to 40 percent of the grease composition. The N-acyl Sarcosine salts are not as effective thickening agents as the fatty acids, as is evident from the 10 to 40 weight percent concentration range specified. Although the concentration required for the preparat-ion'of the greases varies with the metal, grease grade and the chain length of the acyl substituent, the usual concentration of N-acyl sarcosine salt falls between and 35 weight percent.

The oleaginous lubricating base may be a conventional mineral lubricating oil, a synthetic lubricating oil prepared by cracking and polymerizing products of the Fischer-Tropsch process and thelike or a synthetic oleaginous compound possessing lubricating characteristics and having an SUS viscosity within the lubricating oil viscosity range; The oleaginous base is usually a conventional mineral lubricating oil because of the cost fac- 2 tor, but a synthetic base material can be substituted in all or in part therefor.

The mineral lubricating oils can be a distillate or residual oil and can be derived from a parafin base, naphthene base or a mixed paraifin-naphthene base crude. These mineral lubricating Oils are subjected to greater or lesser degrees of refining and solvent dewaxing, depending upon the use intended for the grease composition. Broadly speaking, the greases of this invention can be formulated with mineral lubricating oils having an SUS viscosity at F. between 50 and 1000, but are usually prepared with base oils having an SUS viscosity at 100 F. between 50 and 300.

The synthetic lubricating bases are usually of the ester or ether type. High boiling esters of aliphatic dicarboxylic acids find particularly wide-spread use in greases adapted for extreme temperature lubrication, that is, lubrication at both high and low temperatures. Examples of the synthetic polyester lubricating bases are: di-2-ethylhexyl sebacate, di-Z-ethylhexyl azelate, di-n-a-myl sebacate, di-Z-ethylhexyl adipate,. and di-n-nonyl azelate. Polyalkylene ethers such as polyethylene glycol, polypropylene glycol, modified by etherification and esterification of the terminal hydroxy radicals, are also useful synthetic lubricating bases.

Additives to impart anti-oxidant and extreme pressure properties may be incorporated in the greases of the invention. Aromatic amine type inhibitors have been found particularly effective anti-oxidants; aromatic amines such as N,N,N,N-tetramethyl 4,4'-diamino diphenyl methane, diphenyl amine and phenyl alphanaphthyl amine are preferred. Extreme pressure additives which may be incorporated in the greases are sulfurized fats, sulfurized oils, chlorinated organic compounds such as chloro-substituted waxes, chloro-substituted aromatic compounds and chlorinated olefin polymers and sulfochlorinated compounds such as sulfo-chlorinated olefin polymers and olefins derived from waxes.

In the following examples there is illustrated the preparation of the novel grease compositions of this invention.

EXAMPLE 1 Into a grease kettle there were introduced 246 grams of N-stearoyl sarcosine, 250 grams of a naphthene base oil having an SUS at 100 F. of about 312, a pour point or" --20 F., and a flash COC of 355 F. minimum and 250 grams of water. grams of lithium hydroxide in a 10.3% aqueous solution was gradually added to the reaction mixture as the temperature was raised to about 210 F. After saponification at 210 F. for about 2 hours, .and dehydration at about 310 F. for about 1 hour, an additional 350 grams of the naphthene base distillate oil was slowly added to the reaction mixture as it slowly cooled. A number 1 grade grease was obtained having the following composition: 29.4 percent lithium N-stearoyl sarcosinate and 70.6 percent naphthene base oil. The properties of this grease are shown in Table I.

EXAMPLE 2 300 grams of N-stearoyl sarcosine, 300 grams of the naphthene base oil employed in Example 1, 38 grams of lime and 300 grams of water were charged to a grease kettle. After saponification at a temperature about 210 F. for 2 hours and dehydration at a temperature of about 3l0 F. for 1 hour, an additional 1200 grams of naphthene base oil was slowly added to the reaction mixture as it was cooled. After passage through a Premier colloid mill, a No. 2 grade grease was obtained having the following composition: 17.5 percent calcium N-stearoyl sarcosinate and 82.5 percent naphthene base oil. The properties of this grease are shown in Table I.

, 3 EXAMPLE 3 A mixed sodium-calcium N-stearoyl sarcosine grease was prepared as follows: 282 grams of N-stearoyl sarcosine, 300 grams of the naphthene base oil employed in Example 1, 300 grams of Water, 55.5 grams of sodium hydroxide in a 49.4% aqueous solution and 7.0 grams of lime constituted the charge to the grease kettle. After saponificaticn at 200 F. for about 2 hours and dehydration at 310 F. for about 1 hour, an additional 1000 grams of naphthene base was added as the mixture was slowly cooled. The product was a No. 1 grade grease having the following composition: 3.8 percent calcium N-stearoyl sarcosine, 15.0 percent sodium N-stearoyl sarcosinate and 81.2 percent naphthene base distillate oil. The properties of this grease are shown in Table I.

EXAMPLE 4 A lithium N-lauroyl sarcosine grease was prepared as follows: 275 grams of N-lauroyl sarcosine, 275 grams of naphthene base oil employed in Example 1, 275 grams of water and 246 grams of a 10.7 aqueous solution of lithium hydroxide constituted the charge to the grease kettle. After saponification of the grease mixture at 210 F. for 2 hours and dehydration at 310 F. for 1 hour, an additional 250 grams of naphthene base oil was added as the mixture was slowly cooled down to 200 F. The grease was drawn at 120 F. and had the following composition: 35% lithium N-lauroyl sarcosinate and 65% naphthene base distillate oil. The properties of this grease are also shown in the accompanying Table I.

4 an alkali metal or an alkaline earth metal N-acyl sarcosine salt as a grease thickening agent.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made with-' out departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A grease comprising a major portion of an oleaginous lubricating base and a metal salt of N-acyl sarcosine of the general formula RC ONCHaCO OH in which R is an aliphatic hydrocarbon radical containing 10 to 24 carbon atoms, said metal salt being present in an amount sufiicient to efiect thickening of said lubricating base to grease'consistency and said metal being selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof.

2. A grease comprising a major portion of an oleaginous lubricating base and the lithium salt of N-stearoyl sarcosine in an amount suflicient to thicken said lubricating base to grease consistency.

3. A grease comprising a major portion of an oleaginous lubricating base and the calcium salt of N-stearoyl sarcosine in an amount suflicient to thicken said lubricating base to grease consistency.

4. A grease comprising a major portion of an oleaginous lubricating base and a mixed calcium-sodium salt Table I PROPERTIES OF METAL N-ACYL SARCOSINE GREASES Li Grease of Ca Grease of Na-Ga Grease Li Grease of Example 1 Example 2 of Example 3 Example 4 Bomb Oxidation, 100 Hr. at 210 F.Pres- 1 to 2 p. s. i 5 1:0 6 p. s. i.

sure Drop.

Dropping Point 240 F 280 F. ASTM Penetration at 77 F;

Unworked 277.

Worked 323.

Worked, 100,000 Str 313. Water Washing and Rusting Test:

Grease in bearing, percent 17 6.

Condition of bearing No rust. Dynamic Water Resistance Test, percent loss 100.

Water Absorption, percent 100.

Penetration alter Absorption. Soft grease. Salt Spray, percent Rust 85. Appearance Light tan,

smooth.

The properties of the N-acyl sarccsine metal salt base greases are dependent to a great extent on the metal employed. The lithium l\acyl sarcosinate base greases of Examples 1 and 4 exhibit excellent anti-rust and anti-oxidant properties. The excellent anti-oxidant properties are shown in the bomb oxidation test and the anti-rust properties are shown in the water Washing and rusting test. The anti-rust properties of the lithium N-acyl sarcosinate greases are particularly surprising since a rust inhibitor is usually required for lithium soap greases in order to obtain a no rust rating in this test. The small change in consistency of the lithium N-stearoyl sarcosinate of Example 1 after water absorption is also surprising. The small loss in the dynamic Water resistance test and the 0% rust in the salt spray test obtained with the calcium N-stearoyl sarcosinate base grease of Example 2 show that the calcium base greases of this invention have excellent resistance to water and rust.

The properties of the greases shown in Table I illustrate that greases possessing unusual anti-oxidant, antirust, and water-resistant properties are obtained using RC ONCH2C O OH in which R is an aliphatic hydrocarbon radical containing 10 to 24 carbon atoms and said metal being selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,640,812 Bryant June 2, 1953 2,699,427 Smith et al. Jan. 11, 1955 2,756,213 Dixon July 24, 1956

Claims (1)

1. A GREASE COMPRISING A MAJOR PORTION OF AN OLEAGINOUS LUBRICATING BASE AND A METAL SALT OF N-ACYL-SARCOSINE OF THE GENERAL FORMULA