EP0155131B1

EP0155131B1 - Grease composition containing boron compound and hydroxy containing soap thickener

Info

Publication number: EP0155131B1
Application number: EP85301462A
Authority: EP
Inventors: John Phillips Doner; Andrew Gene Horodysky; John Antone Keller, Jr.
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1984-03-07
Filing date: 1985-03-05
Publication date: 1990-08-08
Anticipated expiration: 2005-03-05
Also published as: NZ211296A; AU3952585A; CA1280738C; DE3579015D1; BR8501026A; JPS60217298A; EP0155131A3; AU578070B2; EP0155131A2; JPH0635590B2; PH22814A

Description

The invention is concerned with the novel group of compositions. It more particularly relates to a synergistic grease composition comprising oil, hydroxy-containing soap thickener and borated amine, and optionally containing phosphorus and sulfur moieties.
US Patents, 3125523; 3125524 and 3125525 disclose lubricating greases thickened with hydroxy fatty acid soaps and comprising salts formed from amines and borate esters.
The present invention seeks to provide lubricating greases of improved dropping point.
According to one aspect of this invention, there is provided an improved grease composition which comprises:

i. a major proportion of a grease vehicle;
ii. thickener which contains at least 15% by weight of a hydroxy-containing soap thickener; and
iii. from 0.01 % to 10% by weight of a condensation product made by reacting boric acid with an amine of the formula:
wherein:
- x is 0 to 2;
- R, R', R³ or R⁴, which may be the same or different, each represents a hydrogen atom or a C, to C₃₀ hydrocarbyl group, a C_z to C₄ hydroxyalkyl group, a C₆ to C₂₀ polyalkoxylated group which may comprise sulfur or additional oxygen, with the proviso that at least one of R, R¹, R³ or R4 does not represent a hydrogen atom; and R represents a C₂ to C₄ alkylene group.

The presence of a phosphorus and sulfur moieties provides an even higher dropping point. The alkyl borates include the mono-, di- and trialkyl borates, i.e., those having the methyl, ethyl, propyl, butyl, pentyl and hexyl groups.
Preferably the amine is overborated. By "overborated" is meant the presence in the borated product of more than a stoichiometric amount of boron with respect to the amine.
Included within the scope of the amines as set forth in the above formula are (1) the primary amines such as hexylamine, octylamine, nonylamine, decylamine, dodecylamine, tetradecylamine, octadecylamine, eicosylamine, triacontylamine, oleylamine, stearylamine, isostearylamine, tallowamine and soyamine, (2) the secondary amines corresponding to (1) having both groups the same or having mixtures of such groups, (3) the corresponding tertiary amines where again all the groups in the same molecule can be the same or different and (4) diamines such as N-octyl-1,2-ethylenediamine or the N-octyl-1,3-propylenediamine, N-coco-1,2-ethylenediamine or the N-coco-1,3-propylenediamine, N-oleyl-1,2-ethylenediamine, or N-oleyl-1,3-propylenediamine, N-soya-1,2-ethylenediamine or the N-soya-1,3-propylenediamine and N-tallow-1,2-ethylenediamine or the N-tallow-1,3-propylenediamine. The secondary amines include N-ethyl-N-oleylamine, N-methyl-N-soyamine, and the tertiary amines include N,N-diethyl-N-oleylamine.
Alkoxylated amines included are bis(2-hydroxyethyl)olelylamine, bis(2-hydroxypropyl)oleylamine, bis(2-hydroxyethyl)tallowamine, bis(2-hydroxypropyl)tallowamine, (hydroxyethyl)(hydroxypropyl)tallowamine, polyethoxylated oleylamine (containing 7 ethoxy groups) and polyethoxylated tallowamine (containing 3 ethoxy groups). Included also are hydroxyalkyl amines made by the ethoxylation or propoxylation of hydrocarbyldiamines or hydrocarbyltriamines. Specifically included are aromatic or alkyl-or alkylene-substituted aromatic groups containing 6 to 30 carbon atoms. Further included are alkoxyalkylamines, such as dodecyloxypropylamine and triisodecyloxypropylamine and similar oxygen- containing amines, and the corresponding alkoxydiamines, such as the N-alkoxyhydrocarbylenediamines.
The reaction to form the condensation product (iii) can be carried out at from about 80°C to about 260°C, preferably from about 110°C to about 180°C. The temperature chosen will depend for the most part on the particular reactants and on whether or not a solvent is used. Reaction pressures can be vacuum, atmospheric or positive pressure. In carrying out this reaction, it is preferable that quantities of reactants be chosen such that the molar ratio of amine to boric acid be from about 0.2 to about 2, preferably from about 0.5 to about 0.9. The amine can be reacted with an excess of the boric acid to form a condensation product containing from about 0.1% by weight of boron to as much as 10% or more of boron.
While atmospheric pressure is generally preferred, the reaction can be advantageously run at from about 1 to about 5 atmospheres. Furthermore, where conditions warrant it, a solvent may be used. In general, any relatively non-polar, unreactive solvent can be used, including benzene, toluene, xylene and 1,4-dioxane. Other hydrocarbon and alcoholic solvents, which include propanol, butanol, hexamethylene glycol and the like, can be used. Mixtures of alcoholic and hydrocarbon solvents can also be used.
The times for the reactions are not critical. Thus, any phase of the process can be carried out from about 1 to about 20 hours.
A narrow class of thickening agents is preferred to make the grease of this invention. Included among the preferred thickening agents are those containing at least a portion of alkali metal, alkaline earth metal or amine soaps of hydroxy-containing fatty acids, fatty glycerides and fatty esters having from 12 to about 30 carbon atoms per molecule. The metals are typified by sodium, lithium, calcium and barium. Preferred is lithium. Preferred members among these acids and fatty materials are 12-hydroxystearic acid and glycerides and esters containing 12-hydroxystearates, 14-hydroxystearic acid, 16-hydroxystearic acid and 6-hydroxystearic acid.
The entire amount of thickener need not be derived from the aforementioned preferred members. Significant benefit can be attained using as little thereof as about 15% by weight of the total thickener. A complementary amount, i.e., up to about 85% by weight of a wide variety of thickening agents can be used in the grease of this invention. Included among the other useful thickening agents are alkali and alkaline earth metals soaps of methyl-12-hydroxystearate, diesters of a C₄ to C₁₂ dicarboxylic acid and tall oil or marine oil fatty acids. Other alkali or alkaline earth metal fatty acids containing from 12 to 30 carbon atoms and no free hydroxyl may be used. These include soaps of stearic and oleic acids.
Other thickening agents include salt and salt-soap complexes as calcium stearate-acetate (U.S. Patent No. 2,197,263), barium stearate acetate (U.S. Patent No. 2,564,561), calcium, stearate-caprylate-acetate complexes (U.S. Patent No. 2,999,065), calcium carpylate-acetate (U.S. Patent No. 2,999,066) and calcium salts and soaps of low-, intermediate- and high-mblecular weight acids of nut oil acids.
Another group of thickening agents comprises substituted ureas, phthalocyamines, indanthrene, pigments such as perylamides, pyromellitdiimides, and ammeline, as well as certain hydrophobic clays. These thickening agents can be prepared from clays which are initially hydrophilic in character, but which have been converted into a hydrophobic condition by the introduction of long-chain hydrocarbon 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 surface active agent, such as an onium compound. Typical onium compounds are tetraalkylammonium chlorides, such as dimethyl dioctadecyl ammonium chloride, dimethyl dibenzyl ammonium chloride and mixtures thereof. This method of conversion, being well known to those skilled in the art, is believed to require no further discussion, and does not form a part of the present invention.
Manufacture of the thickening agents can be done in a variety of grease making equipment such as in open kettles at reduced, atmospheric, or positive pressures; in higher pressure reaction chambers which may be operated to as high as 180 psig; or in continuous manufacturing equipment. The temperature range from the bulk grease under manufacture can range from 15°C (60°F) to 238°C (460°F).
The third member(s) that may be present in the grease composition are the phosphorus and sulfur moities. Both of these can be present in the same molecule, such as in a metal or non-metal phosphorodithioate of the formula
wherein R⁶ is a hydrocarbyl group containing 3 to 18 carbon atoms, M is a metal or non-metal, n is the valence of M and Z is oxygen or sulfur, at least one Z being sulfur.
In this compound, R⁶ is preferably an alkyl group and may be a propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl or octadecyl group, including those derived from propanol, isopropanol, butanol, isobutanol, sec-butanol, 4-methyl-2-pentanol, 2-ethylhexanol, oleyl alcohol, and mixtures thereof. Further included are alkaryl groups such as butylphenyl, octylphenyl, nonylphenyl and dodecylphenyl groups.
The metals covered by M include those in Groups IA, IIA, IIB and VIII of the Periodic Table. Some that may be mentioned are lithium, molybdenum, sodium, calcium, zinc, cadmium, silver and gold. Non- metallic ions include organic groups derived from vinyl esters such as vinyl acetate, vinyl ethers such as butyl vinyl ether, epoxides such as propylene oxide and 1,2-epoxydodecane and amine salts. They also include other nitrogenous compounds such as those derived from hydrocarbyl amines and diamines, including oleylamine and N-oleyl-1,3-propylenediamine and such as the imidazolines and oxazolines.
The phosphorus and sulfur can also be supplied from the combination of 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 sulfide such as sulfurized isobutylene, dibenzyl sulfide, sulfurized terpenes, phosphorodithionyl disulfide and sulfurized jojoba oil. The phosphites embrace the dibutyl, dihexyl, dioctyl, didecyl and similar phosphites. Phosphate esters containing 4 to 20 carbon atoms in each hydrocarbyl group, such as tributyl phosphate, tridecyl phosphate, tricresyl phosphate and mixtures of such phosphates, can also be used.
In summary, it is essential to the practice of this invention, in which greases having vastly improved dropping points are obtained, that at least the first two of the above-mentioned ingredients be formulated into the composition. Thus:

first, with respect to the preparation of the grease, the thickener will have at least about 15% by weight of a metal or non-metal hydroxy-containing soap therein, the total thickener being from about 3% to about 20% by weight of the total grease composition;
second, there will be added to the grease from about 0.01 % to about 10% by weight, preferably about 0.1 % to about 2%, of a condensation product, in which an amine, has been reacted with, preferably, at least an equimolar amount of boric acid and
as an optional third component, the composition may have therein from 0.01% to about 10% by weight, preferably from 0.2% to 2% by weight, of a compound containing both phosphorus and sulfur moieties or a mixture of two or more compounds which separately supply the phosphorus and sulfur moieties. If separate compounds are used, an amount of the mixture equivalent to the above concentration levels is used to supply desired amounts of phosphorus and sulfur.

It was noted that, when the hydroxy-containing thickener was used with the condensation product (iii), the dropping point of the grease was consistently unexpectedly higher than a grease from the same grease vehicle and the same reaction product, but with a different thickener, e.g., a non-hydroxy-containing thickener. Thus, the broad invention is to a grease composition comprising the two components mentioned.
In general, the reaction products of the present invention may be employed in any amount which is effective for imparting the desired degree of friction reduction, antiwear activity, antioxidant activity, high temperature stability or antirust activity. In many applications, however, the condensation product (iii) and the phosphorus- and/or sulfur-containing compound(s) are effectively employed in combined amounts of from about 0.02% to about 20% by weight, and preferably from about 0.2% to about 4% of the total weight of the composition.
The greases of the present invention can be made from either a mineral oil or a synthetic oil, or mixtures thereof. In general, mineral oils, both paraffinic, naphthenic and mixtures thereof, may be of any suitable lubricating viscosity range, as for example, from about 45 SSU at 100°F to about 6000 SSU at 100°F, and preferably from about 50 to about 250 SSU at 210°F. These oils may have viscosity indexes ranging up to about 100 or higher. Viscosity indexes from about 70 to about 95 are preferred. The average molecular weights of these oils may range from about 250 to about 800. In making the grease, the lubricating oil from which it is prepared is generally employed in an amount sufficient to balance the total grease composition, after accounting for the desired quantity of the thickening agent, and other additive components to be included 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 esters, di(2-ethylhexyl) sebacate, di(2-ethylhexyl) adipate, dibutyl phthalate, fluorocarbons, silicate esters, silanes, este'f's of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated synthetic oils, chain-type polyphenyls, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl esters typified by a butyl-substituted bis(p-phenoxy phenyl) ether, phenoxy phenylethers.
The metallic soap grease compositions containing one or more of the borated amines, and optionally, one or more of the sulfur and phosphorus combinations described herein provide advantages in increased dropping point, improved grease consistency properties, antirust characteristics and potential antifatigue, antiwear and antioxidant benefits unavailable in prior greases. The grease of this invention is unique in that it can be preferably manufactured by the admixture of additive quantities of the alcohol borates to the fully formed soap grease after completion of saponification.
The following Examples illustrate the invention.

Example 1

A mixture of 1295 g of N-oleyl-1,3-propylenediamine (obtained as Duomeen O from Armak Chemical Co.), 218 g of xylene, 437 g of n-butanol, 658 g of hexamethylene glycol and 1210 g of boric acid were placed in a reactor equipped with heater, agitator and Dean-Stark tube with condenser, and refluxed for about 10 hours until all water formed in the reaction azeotroped over (maximum temperature was about 195°C). The solvents were removed by vacuum distillation at 195°C and the product was filtered and then diluted with an equal amount of 100 second process oil to form a 50% concentrate of borated diamine in mineral oil. The concentrate was an orange colored viscous liquid.

Example 2

N-tallow-1,3-propylenediamine (obtained as Duomeen T obtained from Armak Chemical Co.) was borated with boric acid as generally described in Example 1. For convenience of handling, the borated N-tallow-1,3-propylenediamine was blended with an equal wt. of 100 second process oil to form a 50% concentrate in mineral oil.

Example 3

A lithium hydroxystearate grease thickener was prepared by saponification of a mixture containing 12-hydroxystearic acid (8%) and the glyceride thereof (9%) with lithium hydroxide in a mineral oil vehicle at about 177°C in a closed contactor.

Example 4

After depressuring and dehydration of the thickener in an open kettle, sufficient mineral oil was added to reduce the thickener content to about 9.0%. After cooling to about 99°C, a typical grease additive package, consisting of an amine antioxidant, phenolic antioxidant, metallic dithiophosphate (1.5 wt.% of zinc dialkyl phosphorodithioate, where the alkyl is derived from a mixture of C₃ to C₆ primary alcohols), sulfur-containing metal deactivator and nitrogen containing antirust additives, was added.

Example 5

To the base grease of Example 4, was added at about 110°C, 0.5 wt.% of the borated N-oleyl-1,3-propylenediamine of Example 1.

Example 6

To the base grease of Example 4, was added at about 115°C, 1.0 wt.% of the borated N-tallow-1,3-propylenediamine of Example 2.

Example 7

To the base grease of Example 3 was added 0.5 wt.% of the borated N-oleyl-1,3-propylenediamine of Example 1.

Example 8

Same as Example 7, except 2% of borated amine was used.

Example 9

Base grease thickened with the lithium soap of 50/50 (wt) mixture of stearic and palmitic acids, which are non-hydroxy-containing thickeners.

Example 10

50 wt.% of the base grease used in Example 4 plus 50 wt.% of the grease of Example 9, producing a 50-50 mixture of hydroxy- and non-hydroxy-containing thickeners.

Example 11

Base grease of Example 9 containing 2 wt.% of the borated amine of Example 2.
Results obtained in the ASTM D2265-78 grease dropping point test are shown in the following table.
Examples 5 and 6 show a significant effect upon dropping point improvement when borated amine is added to hydroxy-containing carboxylate soap thickened grease in the presence of a phosphorus and sulfur source.
Examples 7 and 8 show a significant effect upon hydroxy-containing carboxylate soap thickened grease when the borated amines described are used.
Examples 9, 10 and 11 clearly show no benefit of the borated amine upon the dropping point of a non-hydroxy-containing carboxylate soap thickened grease.

Claims

1. An improved grease composition which comprises:

i. a major proportion of a grease vehicle;

ii. thickener which contains at least 15% by weight of a hydroxy-containing soap thickener; and

iii. from 0.01 % to 10% by weight of a condensation product made by reacting boric acid with an amine of the formula:

wherein:

x is 0 to 2;

R, R', R³ or R⁴, which may be the same or different, each represents a hydrogen atom or a C₁ to C₃₀ hydrocarbyl group, a C₂ to C₄ hydroxyalkyl group, a C₆ to C₂₀ polyalkoxylated group which may comprise sulfur or additional oxygen, with the proviso that at least one of R, R', R³ or R⁴ does not represent a hydrogen atom; and R² represents a C₂ to C₄ alkylene group.

2. A composition according to Claim 1 additionally containing from about 0.01% to about 10% by weight of a compound containing both phosphorus and sulfur moieties or a mixture of phosphorus-containing and sulfur-containing compounds to supply an equivalent amount of phosphorus and sulfur.

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

4. A composition according to Claim 3 wherein the metal is sodium, lithium, calcium or barium.

5. A composition according to any preceding claim wherein the thickener is derived from 12-hydroxystearic acid, 14-hydroxystearic acid, 16-hydroxystearic acid, 6-hydroxystearic acid or the glyceride or ester thereof.

6. A composition according to any preceding claim wherein R, R¹, R³ or R⁴, which may be the same or different, each represents a hydrogen atom or a C₆ to C₂₀ alkyl group with the proviso that at least one of R, R', R³ or R" does not represent a hydrogen atom.

7. A composition according to any preceding claim wherein the amine is (1) hexylamine, octylamine, nonylamine, decylamine, dodecylamine, tetradecylamine, octadecylamine, eicosylamine, triacontylamine, oleylamine, stearylamine, isostearylamine, tallowamine, soyamine, (2) the secondary amines corresponding to (1) having both groups the same or having mixtures of such groups, (3) the corresponding tertiary amines wherein all the groups in each molecule are the same or different, or (4) N-octyl-1,2-ethylenediamine, N-octyl-1,3-propyleneamine, N-coco-1,2-ethylenediamine, N-coco-1,3-propylenediamine, N-oleyl-1,2-ethylenediamine, N-oleyl-1,3-propylenediamine, N-soya-1,2-ethylenediamine, N-soya-1,3-propylenediamine, N-tallow-1,2-ethylenediamine, N-tallow-1,3-propylenediamine, N-ethyl-N-oleylamine, N-methyl-N, soyamine, N,N-diethyl-N,oleylamine, bis(2-hydroxyethyl)oleylamine, bis(2-hydroxypropyl)oleylamine, bis-(2-hydroxy)tallowamine, bis(2-hydroxypropyl-tallowamine, (hydroxyethyl)(hydroxypropyl)tallowamine, polyethoxylatedoleylamine containing 7 ethoxy groups, polyethoxylated tallowamine containing 3 ethoxyl groups, hydroxyalkyl amines made by the ethoxylation or propoxylation of hydrocarbyldiamines or hydrocarbyltriamines, dodecyloxypropylamine or triisodecyloxypropylamine.

8. A composition according to any preceding claim wherein the phosphorus and sulfur moeities are supplied by a phosphorothioate of the formula

wherein R⁶ is a hydrorcarbyl group containing 3 to 18 carbon atoms, M is a metal or non-metal, n is the valence of M and Z is oxygen or sulfur, at least one Z being sulfur.

9. A composition according to Claim 8 wherein R⁶ is an alkyl group or an alkaryl group.

10. A composition according to Claim 9 wherein R⁶ is a propyl, butyl, pentyl, octyl, dodecyl, tetradecyl, octadecyl, butylphenyl, octylphenyl, nonylphenyl dodecylphenyl or oleyl group or a mixture thererof.

11. A composition according to Claim 10 wherein R⁶ is derived from propanol, isopropanol, butanol, isobutanol, sec-butanol, 4-methyl-2-pentanol, 2-ethylhexanol or a mixture thereof.

12. A composition according to any of claims 8 to 11 from Group IA, IIA, IIB or VIII of the Periodic Table.

13. A composition according to Claim 12 wherein the metal is lithium, sodium, silver, molybdenum, calcium, zinc, cadmium or gold.

14. A composition according to any of Claims 8 to 11 wherein M is derived from vinyl acetate, butyl vinyl ether, propylene oxide, 1,2-epoxydodecane or nitrogenous compound.

15. A composition according to any of Claims 1 to 7 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.

16. A composition according to Claim 15 wherein the phosphite is a dibutyl, dihexyl, dioctyl or didecyl phosphite or mixtures thereof.

17. A composition according to Claim 15 wherein the phosphate ester is a tributyl, tridecyl or tricresyl phosphate or mixtures thereof.

18. A composition according to Claim 1 wherein the amine is N-oleyl-1,3-propylenediamine, the thickener is 2-hydroxystearate and the phosphorus and sulfur are supplied by zinc C₃ to C₆ alkyl phosphorodithioate.

19. A composition according to Claim 1 wherein the amine is N-tallow-1,3-propylenediamine, the boron compound is boric acid, the thickener is lithium 12-hydroxystearate and the phosphorus and sulfur moieties are supplied by zinc C₃ to C₆ alkyl phosphorodithioate.

20. A composition according to any preceding claim wherein the grease vehicle is a mineral oil.

21. A composition according to any preceding claims wherein the grease vehicle is a synthetic oil.

22. A composition according to Claim 20 and 21 wherein the grease vehicle is a mixture of mineral and synthetic oils.

23. A composition according to any preceding claim wherein the total amount of the thickener is from about 3% to about 20% by weight of the total grease composition.

24. A method of improving the dropping point of a grease composition comprising a major proportion of a grease vehicle and from about 0.01% to about 10% by weight of a condensation product made by reacting boric acid with an amine of the formula

wherein:

x is 0 to 2;

R, R¹, R³ or R⁴ are hydrogen or hydrocarbyl groups containing from 1 to 30 carbon atoms, hydroxyalkyl groups containing 2 to 4 carbon atoms, a polyalkoxylated group containing 6 to 20 carbon atoms or the latter group containing sulfur or additional oxygen, at least one of R, R', R³ or R" being a non-hydrogen group and R is a C₂ to C₄ alkylene group with a boron compound, said method comprising thickening said grease with a thickener containing at least 15% by weight of a hydroxy-containing soap thickener.

25. A method according to Claim 24 in which the grease composition additionally contains from about 0.01% to about 10% by weight of a compound containing both phosphorus and sulfur or a mixture of phosphorus-containing and sulfur-containing compounds to apply an equivalent amount of phosphorus and sulfur.