CA1209982A

CA1209982A - Grease composition

Info

Publication number: CA1209982A
Application number: CA000446423A
Authority: CA
Inventors: John A. Keller, Jr.; Andrew G. Horodysky; John P. Doner
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1983-08-03
Filing date: 1984-01-31
Publication date: 1986-08-19
Also published as: JPS6040200A; AU566667B2; BR8401750A; DE3468122D1; ZA844087B; EP0134063B1; NZ206931A; ATE31425T1; EP0134063A2; AU2395484A; JPH0662987B2; EP0134063A3

Abstract

GREASE COMPOSITION

ABSTRACT

Grease compositions, wherein the grease is thickened with a metal hydroxyl-containing soap grease thickener are provided. Other essential ingredients of the compositions include borated hydrocarbyl epoxides and phosphorus and sulfur moieties.

Description

GREASE CO~POSITION

The invention is concerned with a novel group of compositions. It more particularly relates to a synergistic grease co~position comprising grease, metal hydroxy~containing soap thickener, borated epoxide and phosphorus an~ sulfur moities.
U.S. Patent No. 4,410,438 relates to lubricant compositions, including greases, comprising borated epoxides in wnich boron is present in excess. Also, certsin other forms of epoxides have been used in lubricants. For example, U. 5. 4,~44,829 describes the use of epoxidized fatty acid esters as lubrlcity agen~s in lubricating oils.
In accordance with the invention, there is provided a grease composition containing (1) a metal hydroxyl-containing soap thickener,

(2) a compound prepared by reacting an epoxide of the ~ormula A

R

wherein R, Rl, R2 and R3 are hydrogen or a C8 to C30 hydrocarbyl yroup, at least one o~ which is hydrocarbyl, with at least a molar amount o~ boric acid, boric oxide or an alkyl borate of the ~ormula (R4Q)xB(oH~y .
wherein x is 1 tn 3, y is O to 2, their sum being 3, and R4 is an alkyl group containing ~rom 1 to 6 ~arbon~atoms and (3) phosphorus and suIfur moieties.
` Pre~erably the boratéd produc~ contains more than a stoichiometric amount of boron.
The borated epoxides of the invention can be made by reacting an epoxide with boron compound, such as boric oxide, boric acid or an alkyl borate, or mixtures thereof. The resulting products are .. . .
.

, primarily monoborate esters, but other ~ossible products present are the products of reaction between epoxide dimers, or higher oligomers, and a boron compound to form the corresponding borate esters.
Included within the scope of the epoxides as set forth above, are 1,2-epoxyoctane, 1,2-epoxydecane~ 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1,2-epoxyheptadecane~ 1,2-epoxyoctadecane, 1,2-epoxyeicosane and mixtures o~ such epoxides, as well as mixtures of other epoxides.
These include epo~ides of mixtures o~ C22 to C30 ole~ins and o~
mlxtures of C24 to C28 ole~ins. Also included are epoxides ~rom dimers of octene, dimers of decene~ dimers o~ mixed octene and decene, epoxides ~rom decene trimers and the like~ Hydrocarbyl is meant to include alkyl, aryl, cycloalkyl or cycolalkenyl groups containing from 8 to 30 carbon atoms, pre~erably lû to 22 carbon a~oms. Pre~erably, hydrocarbyl is an alkyl group.
As noted hereinabove, the boron compound used is boric acid, boric oxide or an alkyl bora~e, preferably boric acid. The alkyl borates include the mono-, di- and trialkyl borates, such as the mono-, di- and triethyl borates.
The reaction to ~orm the borate ester can be carried out at from 80C to 260~C9 preferably from 110C to 180C. The te~perature chosen will depend ~or the most part on the particular reactants and on whe~her or not a solvent is used. In carrying out this reaction, it is preferable that quantities o~ reactants be chosen suc~ that the molar ratio o~ epoxide to boron co~poun~ be ~rom 0.2 to 1, pre~erably ~rom 0.5 to 0.9. The epoxide can be reacted with an excess of the borating species to form a borate ester containing from 0.1% by weight of boron to more than 10~ of boron.
While atmospheric pressure is generally preferred, the reactiQn can be advantageously run at from 1 to 5 atmospheres.
Furthermure, where conditions warrant it, a solvent may be used. In general, any relatively non~polar~ unreactive solvent can be used, including benzene, toluenep xylene and 1,4-dioxane. Other hydrocarbon and alcoholic soluents, which include propanol and butanol can be used. Mixtures of alcoholic and hydrocarbon solvents can be used also.
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The times for the reactions are not critical. Thus, any phase of the process can be carried out in from 1 to 20 hours.
A narrow class of thickening agents is preferred to make the grease o~ this inventionq Included among the preferred thickening agents are those containing at least a portion of alkali and alkaline earth metal soaps of hydroxyl~containing fatty acids, fatty glycerides and fatty esters having from 12 to about 30 carbon atoms per molecule. The metals are typified by sodiumt lithium9 calcium and barium. Pre~erred is lithium. Pre~erred members among these acids and fatty materials are 12 hydroxystearic acid and glycerides containing 12-hydroxystearates.
The entire amount o~ thickener need not be derived from the aforementioned preferred members. Signi~icant bene~it can be attained using as little thereo~ as about 15~ by w~ight of the ~otal thickener. A complementary amount; such as up to about 85% by weight of a wide variety of thickening agents, can be used in the grease of thls invention. Included among the other useful thickenins agents are alkali and alkaline earth metal soaps o~ methyl-12 hydroxystearate, diesters of a C4 to C12 dicarboxylic acid and tall oil ~atty acids. Other alkali or alkaline earth metal ~atty acids containing from 12 to 30 carbon atoms and no free hydroxyl may be used. These include soaps o~ stearic and oleic aclds.
Other thickening agents include salt and salt-soap complexes as calcium stearate~acetate (U.S. Patent No. 2,1979263~, barium stearate acetate (U.S. Patent No. 295649561), calcium, stearate-caprylate-acetate complexes (U.S. Patent No. 2,99~,û65)7 calcium caprylate-acetate (U.S Patent No. 2,999,066), and calcium sal~s and soaps o~ low-, intermediate- and high-molecular weight acids and o~ nut oil acids.
Another g¢oup of thickening agents co~prises substituted ureas, phthalocyamines, indanthrene, pigments such as perylimides, pyro~ellitdiimides, and ammeline, as well as c~rtain hydrophobic clays. These thickening agents can be prepared from clays which are initially hydrophilic in character, but which have b~en convert~d into a hydrophobic condition by the introduction of long-chain hydrocaron .
.

radicals into the surface of the clay particles prior to their use as a component of a grease composition, as, for example, by being subjected to a preliminary treatment with an organic cationic sur~ace active agent, such as an onium compound. Typical onium compounds are tetraalkylammonium chloridesj such as dimethyl dioctadecyl ammonium chloride, dimethyl dibenzyl ammonium chloride and mixtures thereof.
This method o~ conversion, being well known to those skilled in the art9 is believed to require no further discussion.
; The third member(s) of the grease composition of the instant invention are the phosphorus and sulfur moieties. Both of these can be present in the same molecule, such as in a metal or non-metal - phosphorodithioate of the formula ~ X
(R50)2 PS n M

wherein R5 is a hydrocarbyl group containing ~ to 18 carbon atoms, M
is a metal cr non-metal, n is the valence of M and X is oxygen or sulfur.
In this compound, R5 is preferably an alkyl group and may be a propyl, butyl, pentyl, hexyl, octyl, decyl9 dodecyl, tetradecyl or octadecyl group, including those ~erived ~rom isopropanul, butanol9 isobutanol, sec-butanol~ 4-methyl-2-pen~anol9 2-ethylhe~anol, oleyl alcohol9 and mixtures thereof. Further included are alkaryl groups such as butylphenyl, octylphenyl9 nonylphenyl and dodecylphenyl ~roups.
The metals covered by M include those in Groups I~9 IIA~ IIB
and YIII o~ the Periodic Table. Some that may be mentioned are lithium, sodium, calcium, zinc9 cadmium, silver and gold~
Non-metallic ions include organic groups derived ~rom vinyl esters such as vlnyl acetate, vinyl ethers such as b~tyl vinyl ether and epoxides such as propylene oxide and }9~-epoxydodecane.
The phosphorus an~ sulfur can also be supplied From the ccmbination Qf two separate compounds, such as the combination of (1) a dihydrocarbyl phosphite having 2 to 10 carbon atoms in each hydrocarbyl group or mixtures of phosphites and (2) a sul~ide such as sulfurized isobutylene, dibenzyl disulfide, sulfurized terpenes, . ~, 8~

phosphorodithi~nyl disulfide and sulfurized jojoba oil. Thephosphites embrace the dibutyl, dihexyl, dioctyl, didec~l and similar phosphites. Phosphate esters containing 4 to 20 carbon atoms in eacn hydrocarbyl group, such as tributyl phosphate, tridecyl phosphate, tricresyl phosphate and mixtures of such phospha~es, can also be used.
In summary, it is critical to the practice of this invention, in which greases having vas~ly improved dropping points are obtained, that all three of the above-mentioned ingredients be ~ormula~ed into the composition. Thus:
firs~, with respect to ~he preparation of the grease, the thickener must have at least about 15% by weight o~ a metal or non-metal hydroxyl containing soap therein;
secon~, there must be added to the grease from 0.01% to 10 by weight, preferably 0.1% to 2%, of a borated epoxide, in which the borat~d epoxide has been reacted with at least an equimolar amount of boron; and third9 the composition must have therein from 0.01~ to about 10% by weight preferably, from 0.2% to 2X by weight of phosphorus- and sulfur-containing compounds or a mixture of two or more compounds which separately supply the phosphorus and sul~ur moieties. I~
separate compounds are used, an amount of the mixture equivalent to the above concentration levels is used to supply equimolar amounts of phosphorus and sulfur.
In general, the reaction products of the present invention may be employed in any amount which is effective for imparting the desired degree of ~riction reduction, antiwear activity, antioxidant activity, hish temperature stability or antirust activity. In many applications, however9 the borated epoxide and the phosphorus- and/or sulfur-containing compound(s) are eMectively employed in combined amounts ~rom 0.02% to 2Q% by weight, and preferably from 0.2% to 4~ of the total weight of the composition.
The greases o~ the present invention can be made from either a mineral oil or a synthetic oil, or mixtures thereof. In general, mineral oils/ both paraf~inic7 naphthenic and mixtures thereo~, may be of any suitable lubricating viscosity range, as ~or example~ from ~ , .
. ~

~z~
f-23~1 - 6 45 SSU at 100F to 6000 SSU at 100F, and preferably ~rom 50 to 250 SSU at 210F. These oils may have viscosity indexes ranging to 100 or higher. Viscosity indexes from 70 to 95 are preferred. The average molecular weights of these oils may range from 250 to 800. In making the grease, the lubricating oil from which it is prepared is gen2rally employed in an amount suf~icient ~o balance the total grease composition, after accounting for the desired quantity of the thickening agent, and other additive components to be mcluded in the grease formulation.
In instances where synthetic oils are desired, in preference to mineral oils, various compounds of this type may be successfully utilized. Typical synthetic vehicles include polyisobutylene, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters9 di(2-ethylhexyl) sebacate, di(2-ethylhexyl) adipate, dibutyl phthalate, ~luorocarbons, silicate esters, silanes, esters of phosphorus-containing acids9 liquid ureas, ferrocene derivatives, hydrogenated synthetic oils9 chain-type polypheny~s, siloxanes and silicones tPolYsiloxanes), alkyl-substi~uted diphenyl ethers typi~ied by a butyl-s~bstituted bis(p-phenoxy phenyl) e~her, phenoxy phenylethers.

Approximately 1440g of 1,2-epoxyhexa~ecane (obtained commerclally from Union Carbide), 500g of toluene and 5009 of boric acid were charged to a 5 liter glass reactor equipped with heater agitator and Dean-Stark tube with condenser. The conten~s were heated up to 144~C with agitation until water evolution stopped. This took place over a period of about 10 hours. The solvènt was removed by vacuum distillation at about 160C, and the product was ~iltered at about 120QC through diatomaceous earth to yield a clear amber fluid as an amber waxy fluid upon cooling.
~' F-2~41 _ 7 A lithium hydroxystearate grease thickener was prepared by saponification o~ 12-hydroxystearic acid (8%) and glyceride (9%) with lithium hydroxide monohydrate (2.5%) in a mineral oil vehicle (about 76~) at about 177C and ~inal pressure of about 110 psig in a closed contactor. All percentages were percentages by weight o~ the total weight of the thickener.

After dehydrating the thickener in an open kettle, l.~ by weight o~ a boron ester was added to the grease concentrate. The boron-containing ester was prepared by piacing 1440 9 o~ 1,2-epoxy-hexadecane, 500 9 of toluene and 500 9 of boric acid in a glass reactor equipped with heater, agi~a~or and Dean-Stark tube with condenser. The reaction mixture was heated up to 144~C until water evolution as a result of azeotropic distillation ceased. The solvent was removed by vacuum distill~tinn and the crude borate ester was ~iltered through diatomaceous earth to form a clear amber fluid which became waxy a~ter cooling.
After the above boron additive was introduced into the grease concentrate thickener, moderate heat was applied and sufficient oil was then added to reduce the thlckener content to about 9.o% and consequently the boron additive cuntent to 1%. The boron content of the resulting grease was approximately 0.04~ by weight. After cooling to 99C~ antioxidant9 antirust, extreme pressure and antiwear additives including 1.5% zinc dialkyl phosphorodithioate, the dialkyl group heing derived ~rnm a mixture of C3 secondary and C6 primary alcohols, were incorporated in the grease. Results obtaine~ in the ~STM D2265-78 grease dropping poi~t test are shown in the following table~

Table l D2265 Dropping Sample ~oint, C.
~ase Grease ~ Dehydrated grease thickener 199C
Example 1 - " " " + 1.4 wt~
borated epoxide 257C
Example 2 - Dehy~rated grease thickener ~ l.0 wt.
bora~ed epoxide + diluent mineral oil 307C
+ additive package (containing amine antioxidant, phenolic antioxidant~ metallic dithiophosphate, sulfur-contalning metal deactivator and nitrogen-containing an~irust additives) Fully Dehydrated grease ~hickener + diluent formulated mineral oil 193C
base grease + normal additive package without (containing amine antioxidant, phenolic boron antioxidant, metallic dithiophosphate9 additive sulfur-containing metal deactivator and nitrogen containing antirust additlves) The dropping ~oint o~ the dehydrated thickener without borated epoxide was 199C. Adding 1.4 wt.~ of borated epoxide ~o the thickener increased the dropping point to 257C. A~ter the normal grease addi~ive package was added to produce~a ~inished gre~se, the dropping point increased ~ur~her to 307C. The dropping point of an identical~ fully formulated finished grease~with metallic dithiophospha~e but without the borated epoxide:was 193C.

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Claims

Claims:

1. A grease composition consisting essentially of (1) a major amount of a grease and at least about 15% by weight of a hydroxyl-containing soap thickener (2) from 0.01% to 10% by weight of a reaction product made by reacting an epoxide of the formula wherein R, R1, R2 and R3 are hydrogen or a hydrocarbyl group containing from 8 to 30 carbon atoms at least 1 of which is hydrocarbyl, with at least a molar amount of a boron compound selected from boric acid, boric oxide and an alkyl borate of the formula (R4O)xB(OH)y wherein x is 1 to 3, y is 0 to 2, their sum being 3, and R4 is an alkyl group having 1 to 6 carbon atoms and (3) from about 0.1% to about 10% by weight of a phosphorus and sulfur compound or a mixture of phosphorus-containing and sulfur-containing compounds to supply a like amount of phosphorus and sulfur.

2. The composition of Claim 1 wherein the thickener is an alkali metal or an alkaline earth metal soap of a hydroxyl-containing fatty acid, fatty glyceride or fatty ester containing 12 to 30 carbon atoms.

3. The composition of Claim 2 wherein the metal is sodium, lithium, calcium or barium.

4. The composition of Claim 2 wherein the thickener is derived from 12-hydroxystearic acid.

5. The composition of Claim 1 wherein the epoxide is 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane, 1,2-epoxyeicosane, epoxides of mixtures of C22 to C30 olefins, epoxides of mixtures of C24 to C28 olefins, epoxides from decene trimers or epoxides from: dimers of octene;
dimers of decene; or dimers of mixed octene and decene.

6. The composition of Claim 1 wherein the phosphorus and sulfur moieties are supplied by a phosphorothioate of the formula wherein R5 is a hydrocarbyl group containing 3 to 18 carbon atoms, M
is a metal or non-metal, n is the valence of M and X is oxygen or sulfur.

7. The composition of Claim 6 wherein R5 is an alkyl group.

8. The composition of Claim 7 wherein R5 is a propyl, butyl, pentyl, hexyl, octyl, dodecyl, tetradecyl, octadecyl or oleyl group or mixtures thereof.

9. The composition of Claim 8 wherein R5 is derived from isopropanol, butanol, isobutanol, sec-butanol, 4-methyl-2-pentanol, 2-ethylhexanol or mixtures thereof.

10. The composition of Claim 6 wherein M is a metal from Group IA, IIA, IIB or VIII of the Periodic Table.

11. The composition of Claim 10 wherein the metal is lithium, sodium, calcium, zinc, cadmium or gold.

12. The composition of Claim 6 wherein M is derived from vinyl acetate, butyl vinyl ether, propylene oxide or 1,2-epoxydodecane.

13. The composition of Claim 1 wherein the phosphorus and sulfur moieties are supplied by a combination of (1) a dihydrocarbyl phosphite having 2 to 6 carbon atoms in each hydrocarbyl group, mixtures of such phosphites, or a phosphate ester having 4 to 20 carbon atoms in each hydrocarbyl group and (2) a sulfide selected from sulfurized isobutylene, dibenzyl disulfide, sulfurized terpenes, phosphorodithionyl disulfide and sulfurized jojoba oil

14. The composition of Claim 13 wherein the phosphite is a dibutyl, dihexyl, dioctyl or didecyl phosphite or mixtures thereof.

15. The composition of Claim 13 wherein the phosphate ester is a tributyl, tridecyl or tricresyl phosphate or mixtures thereof.

16. The composition of Claim 13 wherein the epoxide is 1,2-epoxyhexadecane, the boron compound is boric acid and the phosphorus- and sulfur-containing compound is zinc dialkyl phosphorodithioate wherein the alkyl group is derived from mixed C3 secondary and C6 primary alcohols.

17. The composition of Claim 1 wherein the grease vehicle is a mineral oil, synthetic oil or mixtures thereof.