US2862882A - Metal amidophosphonate greases - Google Patents

Description

United States atent Cffice 2,862,882 Patented Dec. 2, 1958 METAL AMIDOPHOSPHON ATE GREASES Bruce W. Hotteu, Orinda, and Frederick 0. Johnson,

Berkeley, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application August 6, 1956 Serial No. 602,423

10 Claims. (Cl. 25232.5)

This invention relates to grease compositions. More particularly it relates to grease compositions of the multipurpose type having properties of high temperature serviceability, high water resistance and high work stability. In the preferred embodiment of the invention the greases are also characterized by good Wear characteristics.

In the lubrication of moving parts by greases, i. e., by oils thickened with a suitable thickening agent, several desiderata are present, some of which are more important in one type of service than others. Thus, in one type of service high temperatures may not be encountered, hence a high dropping point (ASTM method) is not important, but resistance to breakdown of the grease structure by water may be important. In other applications resistance to breakdown of the grease structure at high temperatures may be important; therefore, the grease should have a high dropping point although water resistance or some other property may be of secondary importance.

In some types of service, however, where greases are subjected to high temperatures, to contact with water and to high speed mechanical usage tending to break down the grease structure, a multipurpose grease having a high temperature stability, high Water resistance and high work stability is desirable. Even in ordinary automobile chassis lubrication, a multipurpose grease is useful if it can be used to lubricate different parts of the chassis, thereby avoiding the necessity of, stocking different types of grease and of taking the precautions and the time required to lubricate each fitting with a particular, specified type of grease. It will be apparent that if a multipurpose grease is available which is capable of lubricating all or most of the parts of an automobile chassis, such a grease would provide advantages of convenience and economy.

It is an object of the present invention to provide improved grease compositions.

It is a particular object of theinvention to provide grease compositions of the multipurpose type which are capable of effective lubrication under a variety of conditions and are characterized by high resistance to breakdown through contact with water, and to breakdown from high temperature and are characterized by high work stability.

Yet another object of the invention is to provide greases having high temperature and work stability. a

Yet another object is to provide greases having high temperature and work stability together With high water resistance. 1

Yet another object is to provide greases having high temperature and work stability, low wear properties and high resistance to water. i

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

In accordance with the invention oils of lubricating viscosity are thickened .with salts of phosphonic acids of thetype 8 wherein R is an aliphatic radial, preferably an alkyl radical, containing 6 to 24 carbon atoms, and R is hydrogen or a methyl or ethyl radical.

The preferred grease thickeners of the invention are compounds in which R contains 10 to 20 carbon atoms; R, is hydrogen (i. e., the group R CH is a methylene group); and both of the replaceable hydrogens of the phosphonic acid radical are replaced by a metal suitable for forming greases. The metal may be metals of Groups I and II of Mendeleefis Periodic Table and aluminum and lead. Particular metals include the alkali metals such as lithium, sodium and potassium; the alkaline earth metals such as calcium, strontium and barium; the metals cadium and magnesium; and the above-mentioned metals aluminum and lead. Preferred metals are lithium, sodium, calcium, barium and aluminum, and themost advantageous metal is lithium.

The preferred thickeners are, therefore, alkylamidophosphonates of the preferred metals.

Examples of amidomethane phosphonates suitable for use as grease thickeners in accordance with the invention are the di-sodium, di-lithium, calcium and barium salts of caprylamidomethane phosphonic acid Lubricating oils which are useful in the preparation of grease compositions of this invention include a wide variety of lubricating oils, such as naphthenic base, paraffinic base, and mixed base petroleum lubricating oils; other hydrocarbon lubricants, e. g., lubricating oils de- 3 rived from coal products, and synthetic oils, e. g., alkylene polymers (such as polymers of propylene, butylene, etc., and mixtures thereof). Also, alkylene oxide-type polymers, dicarboxylic acid esters, liquid esters of acids of phosphorus, alkylbenzene polymers, polymers of silicon, etc. Synthetic oils of the alkylene oxide-type polymers may be used, c. g., propylene oxide polymers produced by polymerizing propylene oxide in the presence of water or alcohols, e. g., ethyl alcohol; esters of ethylene oxidetype polymers, 6. g., acetylated propylene oxide polymers prepared by acetylating propylene oxide polymers contaiuing hydroxyl groups; polyethers prepared from alkylene glycols, e. g., ethylene glycol, etc.

The polymeric products prepared from the various alkylene oxides and alkylene glycols may be polyoxyalkylene diols or polyalkylene glycol derivatives; that is, the terminal hydroxy group can remain as such, or one or both of the terminal hydroxy groups can be removed during the polymerization reaction by esterification or etherification.

Synthetic oils of the dicarboxylic acid ester type include those which are prepared by esterifyiug such dicarboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenyl succinic acid, fumaric aid, maleic acid, etc., with alcohols such as butyl alcohol, hexyl alcohol, Z-ethylhexyl alcohol, dodecyl alcohol, etc.

Synthetic oils of the alkylbenzene type include those which are prepared by alkylating benzene (e. g., dodecylbenzene, tetradecylbenzene, etc.).

Synthetic oils of the type of polymers of silicon include the liquid esters of silicon and the polysiloxanes; The liquid esters of silicon and the polysiloxanes include those exemplified by tetra(2 ethylhexyl) silicate, tetra(1,3-dimethylbutyl) silicate, tetra(4-methyl-2-pentyl) silicate, tetra(4-methyl-2-pentoxy) disiloxane, hexa( 4- methyl 2 pentoxy)disiloxane, poly (methylsiloxane) poly(methylphenyl) siloxane, and poly-(siloxyglycols),

The above base oils may be used individually as. such, or in various combinations, wherevermis'cibleor'.wherever made so by the use of mutual'solvent s. i

The phosphonate compounds of the invention are em; ployed in quantity sufiicient to'thifck en the oil' ad eq uately. Thus, hard greases maybe produced by appropriateseleg tion of the base oil, the specific thickener and the quantity. of thickener. Proportions of'thick ener as low as 7%,; and as high as 50%' may be employed, but usually about 15 to 30% will be employed.

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

PREPARATION OF ALKYLAMIDOMETHANE PHOSPHONATES Examplev l.-Stearamidmethane phosphonate 305 grams (10.1 moles) of par aforma ldehyde were added quickly to 2400 grams (8.67 moles) of liquid Armid HI. The latter is the trademark of a product of Armour Company, Chicago, Illinois. It is a mixture of fatty amides obtained from hydrogenated tallow and consists of 22% hexadecanoylamide (C H -CO'NH 75% stearamide or octadecanoylamide and 3% 9-octadecenoylamide. Because of the predominance of stearamide this mixture is referred to hereinafter as steara'mide'and the reaction products as stearamido products. The reaction mixture .was heated to 230 F. in a four liter stainless steel beaker. The mixture was then heated at 265 F. for five minutes, cooled to 230 F. during ten minutes and pan cooled. The yieldof N methylol-stearamide was almost quantitative The reaction was substantially as follows:

1000 grams (2.6 moles) of the above N-methylolstearamide were added over. a period of four hours to 1300 ml. of chloroform and 865 grams (6.3 moles) of phosphorus trichloride. The mixture was stirred to facilitate dissolution of the methylolamide. 100 ml. (1.75 moles) of glacial acetic acid were added and the stoppered mixture was allowed to stand three days at room temperature. The initial reaction is given by Equation 2 and during the standing period a rearrangement took place in accordance with Equation 3:

7 017E250 QNHCHaOH P 013 CuHasC QNHCH O-QP CnHasC ONHCHr-O-P C 7H 5C O-NH-CHz B Cl 0 C1 The reaction mixture, clear at first, clouded on standing, thickened and formed a. two phase liquid-solid mixture. Most of the chloroform and excess PCl wereremoved by heating to dryness on a hot water bath. The amide product was purified by stirring with 3 liters of water at 160-170 F. for one hour, then cooling to room. temperature; adding a six-fold volume of methanol, suction filtering and washing with a 6:1 methanol-water mixture until free of chloride. The chlorine atoms of the product of Equation 3 are replaced by hydrolysis to yield the phosphonic acid, C H CQ-NH-CH PQ(OH) .Q

The resulting product, which was obtained in a 70% yield, analyzed as follows:

Calculated Found The steararnidomethanephosphonic acid is a white crystalline material which sinters at 226 F., and which is soluble in hot water, acetone, ethanol and toluene.

The lithium salt was readily obtained .by. treating the crude dichlorophosphonate (product of Equation 3 with warm aqueous lithium hydroxide solution and then wash ing the resulting lithium salt,

with water until it was neutral and free of chloride. Other salts, e. g., the disodium and barium salts, may be prepared by similar techniques.

Example 2.Preparati0n of.myristamidomethane phosphonic acid Example 3.- Preparati0n, 0 lauramidomethane phosphonic acid This phosphonic acid Was prepared by the same process set forth hereinabove, using 325 grams of phosphorus trichloride, 250 grams of methylollauramide, 45 grams of acetic acid, and 250 ml. of chloroform. The reaction pro'ducLcontained 9.6% phosphorus (theory=l0.6%); and the saponification number was 385 (theory=385).

Example 4.Preparati0n of caprylamidomethane phosphonic acid This phosphonic acid was prepared by the process set forth hereinabove, using 200 grams of methylolcaprylamide, 348 grams of phosphorus trichloride, 50 grams of acetic acid, and250 ml. of chloroform. The product p was obtained in 70% yield.

Salts of the alkylamidomethane phosphonic acids can be readily prepared by conventional methods, e. g., from the acids themselves or from the dichloride intermediates.

As described and exemplified in further detail below, grease compositions thickened with metal salts of alkylamidomethane phosphonic acids were prepared as follows: The alkylamidomethane phosphonic acid was dissolved in the base oil at temperatures of approximately 250 F., after which themixture was cooled to 200 F. An aqueous solution of the metal base (e. g., a metal hydroxide, such as lithium hydroxide) was added, and the whole mixture was heated to 350". F. until substantially dehydrated; then pan cooled. The resulting grease was milled in a laboratory jet mill at 4000 p. s. i. The wellknown Manton-Gaulin mill was used for the larger samples.

Example 5.Preparati0n of grease thickened with lithium stearamidomethane phosphonate 35 pounds of a grease were obtained by heating to 500 F. for 10 minutes a slurry consisting of 23% of lithium stearamidomethane phosphonate and 77% of a California naphthenic base oil having a viscosity of 1685 SSU at 100 F. The product was then pan cooled and milled through a Manton-Gaulin homogenizer at 4000 p. s. i. The resulting grease'had an ASTM dropping point of 500 R, an unworked penetration of 243, and worked penetrations of 303 (after 60 strokes in the ASTM worker packing the grease into two No.

loaded axially at 550 pounds. The bearings were rotated at a speed of 1750 R. P. M. for 18 hours at 250 F.

a After 1,000 hours izithe Shell Roll Test apparatus the Poo was 353. r

b The weight loss was only 1.6 mg. in the Almen steel-on-bronze wear test; and 0.1 mg. in the Falex 500 pound steel-on-steel wear test. This grease passed pounds in the Timken steel-on-steel test. v 7

at 77 F.) and 347 (after 100,000 strokes in the worker). After using this grease during a 9000-mile test run, the front wheel bearings of a city bus were in good condition.

The data set forth in Table I hereinbelow further illustrate the characteristics of grease compositions thickened with metal alkylamidomethane phosphonates. The alkyl radicals described in Table I are the alkyl radicals of the fatty acids used in the preparation of the alkylamidomethane phosphonates.

The base oil used in each instance was a California 'naphthenic base oil having a viscosity of 450 SSU at strokes (e. g., P i. e., 60 strokes at 77 B), after which the penetration value is obtained.

For the work stability test data, ASTM penetrations (after 60 strokes in the ASTM worker at 77 F.) were obtained on the grease to be tested. The grease was then packed into a No. 206 shielded ball bearing. The packed bearing was rotated at 3450 R. P. M. for 30 minutes at room temperature. The ASTM unworked penetration value of the grease at 77 F. was obtained. The AP data of Table I represent the changes in the ASTM worked penetration values obtained before the grease was packed into the bearing, and the ASTM unworked penetration values obtained after the bearing had been rotated.

The boiling water test was run by placing a S-gram sample of grease in boiling water and noting the time at which the grease began to disintegrate. A grease remaining intact for a period in excess of 60 minutes is considered to have excellent resistance to emulsification in water.

The Timken test and the Almen test are described in Lubricants and Lubrication, by CloWer, published by McGraW-Hill Book Company, 1939, pages 145-148. The Falex tests are described in the Journal of the Institute of Petroleum, vol. 32, April 1946.

The Shell roll test is run by placing 75 grams of grease in a Shell roll test apparatus which is described in Military Specification Test Mil-G-10924. However, whereas the Mil-G-10924 test specifies 10 R. P. M. for the apparatus, the data herein were obtained with the apparatus operating at 180 R. P. M. Any grease remaining as a grease for a period of at least 4 hours is considered to have an excellent work stability.

The loaded wheel bearing test data were obtained by Table II hereinbelow sets forth data obtained with grease compositions prepared from various synthetic base oils using lithium stearamidomethane phosphonate as the thickening agent. The silicate" base oil of Test No. 4 was a mixture of hexyl and octyl silicates.

TABLE II Percent, Dropping Base Oil by wt. P0 P00 Point,

Thickchar 1. Poly (methylphenyl) Siloxane. 25 263 294 500+ 2. Di (Z-ethylhexyl) Sebacate 25 294 338 500+ 3. Isooctyl Adipate 25 303 342 500+ 4. Silicate 25 266 330 500+ 5. Polypropylene-glycol Diethen 30 227 284 500+ In addition to the components noted hereinabove, the grease compositions may contain rust inhibitors, oxidation inhibitors, oiliness agents, antibleeding agents, corrosion inhibitors, extreme pressure agents, etc.

It will, therefore, be apparent that greases have been provided in which the major component is an oil of lubricating viscosity; such oil being thickened with a novel type of thickener; and that the greases have very advantageous properties such as resistance to breakdown due to mechanical action, resistance to water and high dropping points.

We claim:

1. A grease composition comprising a major proportion of an oil of lubricating viscosity and, in an amount sufficient to thicken said oil to the consistency of a grease, a metal salt of an arnidophosphonate of the formula R;CONHOH2P(OH)2 wherein R is an aliphatic radical containing from 6 to 24 carbon atoms, wherein said metal is a metal selected from the group consisting of alkali metals and alkaline earth metals.

2. A grease composition comprising a major proportion of an oil of lubricating viscosity and, in an amount suflicicnt to thicken said oil to the consistency of a grease, a metal salt of an amidophosphonate of the formula nlooNrronn wnn from the group consisting of alkali metals and alkaline earth metals.

20s. ball bearings, such that the bearings were full of thetestgrease. The-ball hearings were mounted on a splined shaft and spring.

3. A grease composition comprising a major proportion of a petroleum lubricating oi1 and, inan amount suflicient to thicken said oil to the consistency ofa grease; ametal amidopho'sphoinate of the formula l OLi t r RICONHCHIP E OLi wherein R is an alkyl radical containing= from to 20 carbon atoms. p

4. A grease composition comprising a major proportion of a petroleum lubricating oil and, in an amount sufficient to thicken said oiljto the consistency ofia grease, lithium stearamidor'phosphonate 5. Av-grease compositiomcomprising a petroleum mineraloil and from 7% to 50% byweight of a metal salt of an amidophosphonate ofthe formula moonnorn 'wnp eral oil and from to 30% by weight ofra metal salt of an amidophosphonateof the formula R1CONHCH21(OH)2 wherein R is analiphatic-radical containing from 6 to 24 carbon atoms, wherein said metal is a metal selected from the'group consisting of alkali metals, and alkaline ing viscosity and from 15 to 30% by weight of lithium wherein R is an aliphatic radicalcontaining from 6 to a ;caprylamidomethanephosphonate.

9. A grease composition comprising an oil of lubricating viscosity and from 15 to by weight of lithium myristamidomethanephosphonate.

' 10. A grease composition comprising an oil of lubricating viscosity and from 15 to 30% by weight of lithium lauramidomethanephosphonate.

References Cited in the file of this patent UNITED STATES PATENTS 2,304,156 Engelmann et a1. Dec. 3, 1942

Claims (1)

1. A GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OIL OF LUBRICATING VISCOSITY AND, IN AN AMOUNT SUFFICIENT TO THICKEN SAID OL TO THE CONSISTENCE OF A GREASE A METAL SALT OF AN AMIDOPHOSPHONATE OF THE FORMULA