Title:
Lubricating oil and process for improving same
United States Patent 2104796


Abstract:
This invention relates to improved lubricating oils and to processes for improving lubricating oils. It is well known that lubricating oils, during use, have a tendency to form sludge which is extremely undesirable. It has been proposed to add various compounds, particularly phenolic compounds,...



Inventors:
Dietrich, Melvin A.
Application Number:
US9857836A
Publication Date:
01/11/1938
Filing Date:
08/29/1936
Assignee:
Pont DU.
Primary Class:
Other Classes:
106/285, 252/403, 508/470, 560/220, 560/222
View Patent Images:



Description:

This invention relates to improved lubricating oils and to processes for improving lubricating oils.

It is well known that lubricating oils, during use, have a tendency to form sludge which is extremely undesirable. It has been proposed to add various compounds, particularly phenolic compounds, to lubricating oils to improve their stability against sludge formation.

It has also been proposed to add various materials to lubricating oils for the purpose of improving the viscosity-temperature relationships which relationships are indicated by the viscosity index. Among the materials which have been proposed for this purpose have been rubber, hydrogenated rubber, and highly polymerized hydrocarbons generally. Such agents have been more or less successful but have the undesirable property of having a pronounced thickening effect on the oils.

An object of the present invention is to provide new compounds for addition to lubricating oils" to improve the resistance of the oils to oxidation and sludging. A further object, is to provide compounds to be added to oils which will improve the resistance of the oils to oxidation and sludging and also improve the viscosity-temperature relationships of the oils. A still further object is to provide lubricating oils having improved resistance to oxidation and sludging or improved resistance to oxidation and sludging and improved viscosity-temperature relationships. Other objects are to provide new compositions of matter and to advance the art. Still other objects will appear hereinafter.

These objects may be accomplished in accordance with our invention by incorporating in a lubricating oil, preferably a mineral lubricating oil, a small amount of a compound selected from the oil-soluble polymerized acrylic and alphaalkyl substituted acrylic acid esters of amino alcohols and oil-soluble long-chain fatty acid salts of polymerized acrylic and alpha-alkyl substituted acrylic acid esters of amino alcohols. While polymers having a molecular weight as low as 800 may be used, it is preferable to employ those having a molecular weight of 2000 or more, particularly for improving the viscosity-temperature relationships of the oils. The compounds of this type have been found to be very effective for stabilizing the mineral lubricating oils against color formation, oxidation, and sludge formation during use. In addition, the free bases have the desirable property of improving the vis85 cosity-temperature relationships of the oils. The use of these polymers results in a minimum amount of undesirable thickening action on the oils.

These compounds may be represented by the formula Ri R=C--COOR2 wherein R represents an alkylene radical, Ri represents hydrogen or an alkyl radical and R2 an amino substituted aliphatic radical derived from 10 an amino alcohol or its salt. Preferably, the amino alcohol contains a tertiary nitrogen atom in which the substituents attached to the nitrogen are aliphatic hydrocarbon radicals. The polymeric esters derived from N-substituited 15 amino alcohols in which the substituents are aliphatic hydrocarbon radicals of at least 4 carbon atoms will, in general, be found to be sufficiently soluble in the oil as the free base and hence can be used as such; whereupon they not 20 only stabilize the oil against oxidation and sludge formation but also improve its viscosity-temperature relationships. The polymeric esters derived from amino alcohols containing a lesser number of carbon atoms will be less soluble in the 25 oils and it will generally be necessary to employ these polymers in the form of long-chain fatty acid salts in order to render them sufficiently soluble to enable the desired amount to be added and retained in the oil. 30 When "aliphatic" and "alkyl" radicals are referred to herein and in the claims, it will be understood that such terms include cyclo-aliphatic, such as cyclohexyl and pentamethyl, as well as straight and branched chain aliphatic radicals. 35 Also the term "long-chain fatty acid" as employed herein and in the claims, means the aliphatic acids of 8 or more carbon atoms.

The concentration of the polymer in the oils will be determined by the nature and character- 40 istic of the oil and by the nature and the degree of improvement which is desired. When the compounds are added solely for improving the resistance of the oil to oxidation and sludge formation, a concentration of about 0.5% to about 45 2% will generally be sufficient. When the compounds are added for improving the viscositytemperature relationships, amounts as high as 30% may be employed. However, it will in general be preferred to use between about 1 to about 50 10% based on the oil. It has been found that from about 1% to about 2% is satisfactory in most cases, both for inhibiting sludge formation and improving the viscosity-temperature relationships.

While it is preferable to add the polymer to the oil, a similar effect may be secured by dissolving the monomer in the oil and subsequently polymerizing it, or by adding the constituents necessary to make the monomer to the oil by causing the constituents to react and polymerize directly in the oil. The compounds may be incorporated in the oils by adding them to the oils at 150" C. with vigorous stirring.

In order more clearly to illustrate this invention the preferred modes of carrying the same into effect and the advantageous results thereof, the following examples are given: .Example I 1 10 parts of a mineral lubricating oil containing 0.5% of beta-dicyclohexylaminoethyl methacrylate polymer were heated in a flat bottom dish at 135° C. for 50 hours in the presence of a hot air blast. The oil became only slightly darker in color than the original and no sludge was deposited. A control sample, under the same conditions, became very dark in color and deposited a noticeable quantity of sludge.

The above experiment was duplicated using the corresponding acrylate polymer with analogous results.

Example II 10 parts of a mineral lubricating oil containing 0.50% of the stearate of polymerized betadiethylaminoethyl methacrylate were treated as in Example I. In this case, also, the oil darkened only slightly and deposited no sludge. The free polymer was difficultly soluble in the oil and hence the stearate was employed to improve its solubility.

Substitution of the corresponding acrylate polymer for the stearate of polymerized betadiethylaminoethyl methacrylate in the above experiment gave analogous results.

Example III 2 parts of beta-dicyclohexylaminoethyl methacrylate polymer were dissolved in 98 parts of 45 mineral lubricating oil by heating the mixture to 150* C. with stirring. The improvement in the viscosity-temperature relationship of the oil was measured by determining the viscosity at 1000 F. and 210* F. and calculating the viscosity index according to the method described by Dean and Davis in Chem. and Met. Eng. 36, 618 (1929).

This index serves as a measure of the flatness of the viscosity-temperature curve of the oil, increasing values of the index-resulting as the curves become flatter. The flatness of the curve is a measure of the suitability of the oil as a lubricant over a wide temperature range. The results of this test are shown in the following table: Saybolt universal viscosity at viscosity SIndex 100° F. 210° F.

-Oil alone (asphaltic base crude)..- 243 sec. 44.6 sec. 7 Oil + 2% beta-dicyclohexylaminoethyl methacrylate polymer.. 277 47.6 52 70 The above examples are illustrative only and are not to be construed as limiting the invention.

Various other materials of the same class may be employed, for example, the polymers of esters of acrylic and methacrylic acids derived from other amino alcohols such as beta-propylamino ethanol, beta-di-isopropylamino ethanol, betadi-n-propylamino ethanol, beta-dilaurylamino ethanol, gamma-diethylamino propanol, deltadiethylamino butanol, delta-dibutylamino butanol, delta-di-isobutylamino butanol, beta-diisobutylamino ethanol, beta-ethylamino ethanol, gamma-methylamino propanol, delta-butylamino butanol, delta-isobutylamino butanol, beta-cyclohexylamino

Also, polymers derived from esters of other alpha hydrocarbon substituted acrylic acids which may be used are: alpha-ethyl acrylic esters, alpha-propyl acrylic esters, alpha-iso- In propyl acrylic esters, alpha-butyl acrylic esters, alpha-amyl acrylic esters, alpha-hexyl acrylic esters, alpha-cyclohexyl acrylic esters, alphahexahydrotolyl acrylic esters.

When it is desired to use the fatty acid salts it will generally be found preferable to employ the salts of stearic, palmitic, oleic and naphthenic acids.

Among other polymers which may be employed as the free bases or as the salts may be specifically mentioned: 2-aminocyclohexyl methacrylate, beta-N-dibutylaminoethyl methacrylate, beta-dimethylaminoethyl methacrylate, 2-diethylaminocyclohexyl methacrylate, 1 (beta-methacrylyloxyethyl) piperidene, 4(beta-methacrylyloxyethyl) morpholine, didodeCylaminoethyl methacrylate, dioctylaminoethyl methacrylate, (1-beta-acrylyloxyethyl) piperidene, gamma-diethylaminoN-propyl acrylate. The compounds of this invention may be prepared by reacting an acrylic or an alpha-alkyl substituted acrylic acid, its anhydride, acid halide or ester with an amino alcohol or amino alcoholate in an inert solvent such as benzene, toluene and the like under reflux. The resulting compounds are preferably polymerized by first converting them to salts and then subjecting the salts to polymerizing conditions.

In order more fully to illustrate the method, the following example is given: Example IV A solution of one mol. of beta-diethylamino ethanol, 4 mols of methyl methacrylate, 500 ,o grams of dry benzene and 30 grams of p-phenylenediamine was prepared. This solution was heated in an oil bath under a 48" fractionating column fitted with a distilling head arranged for controlling the reflux. As soon as the removal of the water, in the form of the water-benzene binary, was completed, 2 grams of sodium in 20 cc. of dry methanol were added dropwise to the refluxing reaction mixture over a period of 6 hours. The benzene-methanol binary was collected at the head of the column. Upon completion of the reaction, the mixture was cooled, filtered, and fractionally distilled. The fraction boiling at 85 plus or minus 5° C. at 5 mm. was collected. This fraction, after washing and drying, was used for preparation of the polymer.

While numerous polymerization catalysts may be used, the preferred procedure consists in converting the monomer to the acetate salt in aqueous solution, adjusting to 10% concentration, adding 1% of powdered benzoyl peroxide based on the monomer, and heating for 24 hours at 100* C. The resulting material, purified by filtration, washing, and drying, is converted to the free polymeric base by mixing with an excess of sodium bicarbonate and heating to liberate carbon dioxide.

The precipitated polymer may be converted Into a fatty acid salt by solution In ethanol followed by addition of the theoretical amount of the acid, for'example, stearic acid.

The methods of preparing these compounds Sare described in more detail in the applications of G. D. Graves, Serial No. 21,807 filed May 16, 1935 and Serial No. 42,054 filed September 25, 1935, and the application of J. Harmon, Serial No. 21,810-filed May 16, 1935. These three applications also disclose many other compounds falling within the scope of this invention and which may be used for applicant's purpose.

While the preferred embodiments of this Invention and the preferred modes of practicing the same have been disclosed, it will be apparent to those skilled in the art that many modifications may be made therein without departing from the spirit thereof. Accordingly, this invention is to be limited solely by the appended claims, construed as broadly as is permissible in view of the prior art.

I claim: 1. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800 selected from the oil-soluble polymerized acrylic and alpha-alkyl substituted acrylic acid esters of amino alcohols and oil-soluble longchain fatty acid salts of polymerized acrylic and alpha-alkyl substituted acrylic acid esters of amino alcohols, in which the amino alcohols are 2.5 N-aliphatic substituted mono-hydric amino alcohols devoid of substituents other than aliphatic hydrocarbon radicals.

2. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-alkyl substituted acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

3. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least ;o 800, which compound is an oil-soluble polymerized alpha-methyl acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals. 5.) 4. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized acrylic acid ester of an amino alcohol, which ,O amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

5. A lubricant comprising a lubricating oil having incorporated therein a small amount of a c-, compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-alkyl substituted acrylic acid ester of an amino alcohol in which the amino nitrogen carries at least 1 aliphatlc hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

6. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized acrylic acid ester of an amino alcohol in which the amino nitrogen carries at least 1 aliphatic hydrocarbon radical containing at least 4 . carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

7. A lubricant comprising a lubricating oil having Incorporated therein a small amount of a 0o compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-methyl acrylic acid ester of an amino alcohol in which the amino nitrogen carries at least 1 aliphatic hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is a mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

8. A lubricant comprising a lubricating oil, having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-alkyl substituted acrylic acid ester of a mono-hydric N-di-aliphatic amino alcohol in which each aliphatic substituent is a hydrocarbon radical containing at least 4 carbon atoms, and which amino alcohol is devoid of substituents other than aliphatic hydrocarbon radicals.

9. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble polymerized alpha-alkyl substituted acrylic acid ester of a mono-hydric N-di-cyclohexyl amino alcohol, 235 which amino alcohol is devoid of substituents other than aliphatic hydrocarbon radicals.

10. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is, polymerized beta-(Ndicyclohexyl) aminoethyl methacrylate.

11. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble longchain fatty acid salt of a polymerized alpha-alkyl substituted acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

12. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized alpha-methyl acrylic acid ester of an amino alcohol, which amnino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals. 13. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized acrylic acid ester of an amino alcohol, which amino alcohol is an N-substituted mono-hydric amino alcohol devoid of substituents other than aliphatic hydrocarbon radicals.

14. A lubricant comprising a lubricating oil having Incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized alpha-alkyl substituted acrylic acid ester of a mono-hydric Ndi-aliphatic amino alcohol in which each allphatic substituent is a hydrocarbon radical, the aliphtic substituents containing a total of at least 4 carbon atoms, and which amino alcohol is devoid of substituents other than aliphatic hydrocarbon radicals.

15. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is an oil-soluble long-chain fatty acid salt of a polymerized alpha-methyl acrylic acid ester of a mono-hydric N-di-aliphatic amino alcohol in which each aliphatic substituent is a hydrocarbon radical, the aliphatic substit18 uents containing a total of at least 4 carbon atoms, and which amino alcohol is devoid of substituents other than aliphatic hydrocarbon radicals.

16. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which cjmpound is an oil-soluble long-chain fatty acid salt of a polymerized beta-diethylaminoethyl methacrylate.

17. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is the stearate of polymerized diethylaminoethyl methacrylate.

18. A lubricant comprising a lubricating oil having incorporated therein a small amount of a compound having a molecular weight of at least 800, which compound is polymerized 1(beta- 18 acrylyloxyethyl) piperidene.

MELVIN A. DIETRICH.