US2963436A - Rust-preventive clay-thickened lubricants - Google Patents

Description

.cant having rust-inhibiting qualities.-

United States Patent 13 Claims. (Cl.

This invention relates to an improved thickened lubri- In a particular aspect, it relates to a thickened lubricant to which has been added a phosphite salt in order to impart rust-inhibiting qualities to said lubricant. In another aspect, this known as Bentone 34. v

Clay-thickened greases have many desirable features invention relates to themethod of producing a rust-inhibiting, clay-thickened grease. I

The use of inorganic gelling agents such as orpnophilic bentonite in the preparation of greases is well known in the art. Such a gelling agent as mentioned can be prepared from Wyoming bentonite by centrifuging a dispersion of the clay in water to remove the non-clay components. An amine dispersion is then mixed with. the centrifuged bentonite to yield a flocculated precipitate which is then dried and pulverized. A more detailed disclosure of the preparation of organophilic bentonite will be fund in US. Patent 2,531,427, issued to E. A. Hauser; Dimethyldioctadecyl ammonium bentonite is not found in ordinary soap-thickened greases, the principal advantage being lack of phase change during heating. The bentonite greases are outstanding in this respect in that they have very good temperature-consistency relationships, showing relatively little loss of consistency between ordinary temperatures and temperatures as high as 400 F. Ordinary soap greases melt at temperatures considerably below this, and consequently it is readily seen that the bentonite greases are most'useful in severe application.

The P cipal disadvantage of bentonite grease and other clay-thickened greases is that they have not exhibited good rust-preventive action. The answer to this problem in clay-thickened greases is not simple. At-

tempts have been made to remedy this defect by adding rust-preventives to the grease, but this has not been satisfactory because the additives have exerted a degelling action on the grease. It is with the remedy of this weakness that this invention is concerned.

I have found that the addition of a phosphite salt,

. than 0.1 weight percent can be used, but the ranges given are ordinarily the most desirable.

It is an object of this invention to provide an improved bodied lubricant having rust-inhibiting qualities.

It is another object of this invention to impart rust- I inhibiting characteristics to clay-thickened greases by the use of phosphite salts.

It is another object of this invention to provide a method for producing rust-inhibiting, clay-thickened grease.

v invention will become 2,963,436 Patented Dec. 6, 1960 2 advantages and features of the apparent from the following de-' variom other objects,

tailed description.

The bentonite greases mixing the organophilic bentonite with oil and a small amount of a dispersing agent such as acetone, methanol, or acetonitrile and mixing to form what is termed a pregel." After the pro-gel has been formed, it is mixed inacolloidmillorsimilarhighshearinilltoprodueethe final grease. The amounts of organophilic bentonites ordinarily employed in making these greases may vary from'zto l5 weightpercent. The oilswhichmaybe used in the manufacture of the greases of this invention are paraflinic or naphthenic oils in the viscosity range from SAE to a viscosity of about 225 SUS at 210' F., although the oils are preferably paraflinie oils ranging in viscosity from SAE to SAE 50.

Phosphite salts which are preferred for the practice of this invention are the orthophosphites of lithium, sodium, I potassium, rubidium, cesium. and ammonium. These salts ofier the best combination of high rust-preventive action and low degelling effects. Broadly and in lesser preference, this invention also includes use of the acid phosphites and other phosphites of the above-mentioned metals. The phosphites of group II metals exhibit such definite degelling effects upon clay-thickened greases that they are unusable. n

The greases of this invention can be made with the incorporation of the phosphite salt at any stage in which good dispersion of the salt throughout the grease is insured. The dry powder, preferably finely divided, may be added to the pre-gel" and mixed to obtain dispersion throughout the mixture, and the entire material then passed through the milling operation. A preferred way to obtain the dispersion is to add the phosphite salt to the pre-gel" as an aqueous solution, preferably a rather coneentrated solution, such as percent. Very good uniformity of phosphite salt content throughout the grease is obtained by mixing the solution with the pre-gel and sulilsequently passing the pre-gel" through the colloid m1 It should bepointed out that in the ordinary production of clay-thickened greases no heating of the in-process material is necessary. Similarly, no heating is required This is important from a commercial point of view since no additional'equipment for heating is necessary. An-

other favorable feature is the simple manner in which this additive can be introduced into the process requiring no additional process time.

Better understanding of this invention will be obtained upon reference to the following examples which are nieanttobeexemplaryandnottolimitundulythe Invention.

axamnps The following table of examples shows the efiect of adding a concentrated solution of sodium orthophosphite (Na HPOQ upon the consistency, work stability, and

rust-preventing properties of a Bentone grease. In the samples, Bentone 34" is dimethyldioctadeeyl ammonium bentonite. KC20-H lube stock is a solvent extracted SAE 20 lubricating oil. Oxidized KCZO-H is a solvent refined Mid Continent SAE 20 lubricating oil oxidized by use of ultraviolet light and air bubbled through the oil at a temperature range from to C. at atmospheric pressure until there has been an increase in the color rating of the oil to 5 units NPA color. The itzlt: performed were standard tests for the properties are commonly manufacture by Example I TABLE A.S.T.M. Percent Rusted in Penetration ANH-m Humidity Sam to Cabinet, 90 Hours Num Composition Percent 60 10,000 Panel 1 Pane 2 Strokes Strokes I Bentone M 5. 50 l KCSO-H Lube Stoek.-.-.. 93. 75 301 326 85 70 CILCN 0.75 Bentono 5. 6 2 iifi 5:5 as w 2 s.

35% NarHPOs---- 2. Baritone 34 6. KCm-H Lube Stock- 85. 5 3 Oxidized KCm-H. 5.0 293 338 g 3 CHINO! 2.0 N8lHPol---- 2. 0

Sample 1 was made by using the following procedure:

(1) The Bentone 34 was allowed to settle to the bottom of the oil.

(2) Oil and Bentone were stirred five minutes in a mixer to effect a smooth slurry.

(3) The dispersion aid (CH CN or CH NOQ was added.

(4) Stirring was continued for 30 minutes, in order to form the pro-gel.

(5) The pre-gel" was milled in a colloid mill in order to produce the "final gel, or grease.

In this series of samples, the colloid mill used was a Charlotte ND-l, with a "T-hea milling surfaces was 0.003 inch. The rate of milling was 257 milliliters per minute.

The samples containing sodium orthophosphite were made by use of the following modification of the above procedure.

A test in which Sample 2 was heated to about 400 F. showed that the addition of sodium orthophosphite and water did not affect the normal non-melting quality of the Bentone grease in any way.

The above data illustrates the marked improvement in rust-preventive characteristics which sodium orthophosphite effects in bentonite grease without appreciably afiecting its work stability. The portions of panels 1 and 2 coated with Sample 1 grease, which contain no rust-preventive additive, and exposed for 96 hours in the humidity cabinet showed rusting of 85 and 70 percent, respectively. The portions of these panels coated with Sample 2 grease, to which sodium orthophosphite had been added, evidenced only 2 and 3 percent rusting. Sample 3 contained sodium orthophosphite and an oxidized lubricant which in itself has certain rust-preventive qualities. Sample 3 showed rust-preventive qualities comparable to Sample 2 with a slight decrease in work stability. The heating test of Sample 2 showed that the desirable temperature-consistency relationship of bentonite grease is retained after the addition of the sodium orthophosphite. As can be seen from these data, this invention overcomes a serious weakness in clay-thickened greases while retaining their advantages,

The clearance of the Example 11 Three greases having the following compositions were prepared:

Composition, Wt. Percent Grease No.

Bentone 34 5.5 5. 5 5. 5 KCW-H S 92. 5 90. 5 90. 5 Potassium phosphlte L... 0 2.0 0 Ammonium phosphlte 0 0 2.0 Acetone 2.0 2.0 2.0

I As 40 weight percent aqueous solution.

The greases were prepared in a Waring Blendor using the following technique: (1) The batch size was set at 1600 grams, and the amounts of ingredients were calculated on that basis. (2) The oil was added to the Blendor.

(3) The Bentone was added to the Blendor and allowed to settle.

This method of preparing greases does not produce maximum consistency development for a given quantity of Bentone; hence, comparisons should be made only among these three greases which were all prepared by the same method.

The micropenetration of grease No. 10 was 232, that of grease No. 11A was 150, and that of grease No. 118 was 136, each value being the average of several determinations. These results show that the greases containing the aqueous solution of inhibitor exhibited better consistency development than the plain Bentone grease. Thus, instead of exerting the de-gelling action common to rust inhibitors, these inhibitors have the opposite effect.

The three greases were tested for corrosion prevention t fi fi 9f t e nail corrosion test. This is a simple screening test (not standard) comprising the following steps:

(l) The nails are polished by means of a wire bufling wheel, two nails being required for each grease tested.

(2) For each grease, one nail is coated with a thin layer of the grease (approximately W-inch thick); the other nail is coated with a thick layer of the grease (approximately At-inch thick).

(3) The nails are suspended in a jar containing water in such a manner that a length of the grease-coated nail is above the surface of the water and a length of it is below.

(4) The nails are left in this position for at least a week. In this series of tests, the nails were left for 19 days. The water is replenished occasionally.

(5) The nails are inspected both before and after removing the grease.

The following observations were made on the nails subjected to this test:

Grease No. 10.--Before wiping: two rust spots were visible through the grease on the thin-coated nail. After removing the grease: the thick-coated nail had a mottled surface; the thin coated nail had pits under the rust spots and the surface of the nail was mottled. (Rust spots and pitting represent more serious corrosion than mottling.)

Grease N0. 11A.-Before wiping: mottling visible through the grease on the thin-coated nail above the water line. After wiping: the surface of the thick-coated nail was unchanged; the surface of the thin coated nail was severely mottled.

Grease No, 11B.Before wiping: slight mottling visible through the grease on the thin-coated nail above the water line. After wiping: the surface of the thick-coated nail was unchanged; the surface of the thin-coated nail was mottled.

n the basis of the above-described observations, the greases were ranked in the following order of decreasing rust prevention: 11B 11A l0.

Thus it is clearly seen that these phosphite salts possess definite advantages as rust preventives for clay-thickened greases.

I claim:

1. A thickened lubricant consisting essentially of hydrocarbon lubricating oil, sufficient organophilic bentonite to thicken said oil to grease consistency, said bentonite having been rendered organophilic by treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds, and phosphite salt selected from the group consisting of alkali metal phosphites and ammonium phosphites, said phosphite salt being in an amount sufficient to impart rustinhibiting qualities to said lubricant without causing degelling.

2. A thickened lubricant according to claim 1 wherein said phosphite salt is ammonium orthophosphite.

3. A thickened lubricant according to claim .1 wherein said phosphite salt is ammonium orthophosphite in an amount of 0.1 to weight composition.

4. A thickened lubricant consisting essentially of hydrocarbon lubricating oil, suflioient organophilic bentonite to thicken said oil to grease consistency, said bentonite having been rendered organophilic by treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds, and alkali metal orthophosphite salt in an amount suflicient to impart rust-inhibiting qualities to said lubricant without causing degelling.

S. A lubricant composition according to claim 1, wherepercent based on the total in the alkali metal orthophosphite is potassium orthophosphite.

6. A lubricant composition according to claim 4, wherein the alkali metal orthophosphite is lithium orthophosphite.

7. A lubricant composition according to claim 4, wherein the alkali metal orthophosphite is sodium orthophos' phite.

8. A lubricant composition according to claim 4, wherein the alkali metal orthophosphite is rubidium orthophosphite.

9. A thickened lubricant consisting essentially of hydrocarbon lubricating oil, sufiicient organophilic bentonite to thicken said oil to grease consistency, said bentonite having been rendered organophilic by' treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds, and from 0.1 to 5 weight percent based on the total composition of alkali metal orthophosphite salt.

10. A thickened lubricant consisting essentially of paratfinic lubricating mineral oil having a viscosity in the range of SAE 20 to SAE 50, from about 2 to 15 weight percent organophilic bentonite, said bentonite having been rendered organophilic by treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds, a dispersing agent, and from 0.2 to 2 weight percent based on the total composition of alkali metal orthophosphite salt.

11. A grease composition according to claim 10 wherein said organophilic bentonite is dimethyldioctadec yl ammonium bentonite.

12. A method of imparting rust-inhibiting qualities to a clay-thickened grease formed from a hydrocarbon lubricating oil and suflicient organophilic bentonite to thicken said oil togrease consistency, said bentonite having been rendered organophilic by treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds which comprises adding to a'dispersion of said bentonite in said oil an aqueous solution of phosphite salt selected from the group consisting of alkali metal phosphites and ammonium phosphites, said phosphite salt being in an amount suflicient to impart said rust-inhibiting qualities without causing degelling, agitating the resulting mixtureuntil said phosphite salt is distributed throughout the mixture, and milling said mixture to produce the final grease composition.

13. A process for the production of a rust-inhibiting grease composition comprising dispersing sufficient organophilic bentonite in a hydrocarbon lubricating oil to thicken said oil to grease consistency, said bentonite havingbeen rendered organophilic by treatment with an organic compound selected from the group consisting of amines and quaternary ammonium compounds, adding to the oil-bentonite dispersion a concentrated aqueous solution of alkali metal orthophosphite salt in an amount from 0.1 to 5 weight percent based on the total composition, agitating the resultant mixture until said orthophosphite is distributed throughout the mixture, and milling said mixture to produce the final grease composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,332,209 Enquist 0a. 19, 1943 2,371,866 Barrett Mar. 20, 1945 2,650,198 Kronig s. Aug. 25, 1953 2,748,081 Peterson et a1 May 29, 1956 2,783,160 Taylor Feb. 26, 1951 FOREIGN PATENTS 727,153 Great Britain Mar. 30, 1955

Claims (1)

1. A THICKENED LUBRICANT CONSISTING ESSENTIALLY OF HYDROCARBON LUBRICATING OIL, SUFFICENT ORGANOPHILIC BENTONITE TO THICKEN SAID OIL TO GREASE CONSISTENCY, SAID BENTONITE HAVING BEING RENDERED ORGANOPHILIC BY TREATMENT WITH AN ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMINES AND QUATERNARY AMMONIUM COMPOUNDS, AND PHOSPHITE SALT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL PHOSPHITES AND AMMONIUM PHOSPHITES, SAID PHOSPHITE SALT BEING IN AN AMOUNT SUFFICENT TO IMPART RUSTINHIBITING QUALITIES TO SAID LUBRICANT WITHOUT CAUSING DEGELLING.