US2454890A - Antioxidants for mineral oil lubricants and compositions containing the same - Google Patents

Description

Patented Nov. 30, 1948 2,454,890 ICE 2,454,890 ANTIOXIDANTS FOR MINERAL OILv LUBRI- CANTS AND COMPO THE SAME SITIONS CONTAINING Herschel G. Smith, Wallingford, and Troy L. Cantrell, Lansdowne, Pa... and John G. Peters, Audubon, N. J., assignors to Gulf Oil Corporation, Pittsburgh, ,vania 2a., a corporationof Pennsyl- No Drawing. Application April 9, 1947,

. Serial No. 740,482

This invention relates to antioxidants for mineral oil lubricants and compositions containing the same, and more particularly, it relates to addition agents for mineral oil lubricants which in- 3 hlbit the oxidative deterioration oi' said lubricants.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, plain mineral lubricating oils often prove unsatisfactory in service because of the oxidative deterioration of the oil, with the attendant deposition on the engine surfaces of varnish, gum or sludge. Furthermore, many lubricating oil compositions which may be highly satisfactory for the lubrication of other mechanisms have been found wholly unsuitable for use as turbine oils.

The formation of varnishes, gums and sludges on engine surfaces is due at least'in part to oxidation effects on mineral lubricating oils. In turbine oils the problem of oxidation is further aggravated, because in normal use turbine oils rapidly become contaminated with water.

It is an object of this invention, therefore, to provide an addition agent for mineral oil lubricants which will inhibit the oxidative deterioration of such lubricants.

It is further an object of this invention to pro- 16 Claims. (Cl. 252-515) 2 for the condensation ranges from 150 to 300 F. The proportions of the'reactants may vary over a relatively wide range. The benzyl benzoate may be employed in an amount of from 1 to 4 mols; N-

dimethylaniline may be employed in an amount 01 1 from 1 to 6 mols; and the amount of formaldehyde may range from 0.5 to 6 mols of formaldehyde per mol of benzyl benzoate. Ordinarily, it is preferred to use from-5 to 10 per cent by weight of the activated clay catalyst, based on the total weight of the reactants. However, smaller amounts, as low as 1 per cent by weight, and larger amounts, as high as 20 per cent by weight, may also be employed; but larger amounts than about 10 per cent by weight are ordinarily not necessary. a

In lieu of formaldehyde any formaldehydeyielding compound, such as paraformaldehyde,

dioxymethylene and trioxymethylene may be employed. In such case, the amount of formaldehyde-yielding compound used is based on the equivalent number of mols of formaldehyde yielded within the range of proportions of formaldehyde set forth hereinabove. Accordingly, as used in the appended claims, the term formaldehyde is intended .to include formaldehyde-yieldvide improved mineral oil lubricantcompositions which are remarkably stable against oxidation under service conditions.

. These and other objects are accomplished by the present invention wherein an addition agent for mineral oil lubricants is prepared by condensing benzyl benzoate, N-dimethylaniline and formaldehyde in the presence of an activated clay catalyst. and recoveringthe condensation prod uct. The condensation product so obtained is a light-colored product which, when added to mineral oil lubricants, confers a remarkable stability against deterioration by oxidation. Such condensation products and mineral oil lubricant compositions containing them are believed to be novel and are considered parts of our invention. Contrary to what may be expected from the nature of t he reactants, we do notobtain highly-condensed. .insoluble resinous products.- On the contrary,

ing compounds as well as formaldehyde itself.

Various activated clay catalystsmay be employed in accordance with our invention. Such materials are well known in the art and comprise a natural clay, such as bentonite, fullers earth, floridin and smectite, which has been acid treated in order to activate the clay.

In preparing our new addition agent the reactants and catalyst are placed into a reaction vessel which is then closedand the mixture is heated with agitation until all of the formaldehyde or formaldehyde-yielding compound has been consumed. At this time the water which is formed as a result of the condensation is removed, preferably under vacuum, and the dehydrated condensation product is then filtered to remove the activated clay catalyst. In some instances, it is desirable to prepare our new addition agent in a. concentrate in a mineral lubricating oil which may then-be diluted down with additional oil to the concentration desired in the final lubricating composition' In such instances, the mineral lubricating oil may be added in a suitable amount, say in a weight equal to the weight of reactants, to the reaction mixture in the reaction vessel, and the condensation product obtained will then be a concentrated solution of the addition agent in the mineral lubricating oil.

The condensation products obtained in accordance with our invention are liquids or crystalline solids. While we do not desire to be boundby any theory as to the reaction or reactions involved s,404,aao

or the chemical composition of the products, we believe that irr view of the multiple points of the respective molecules at which the reactants may aqueous) and 8.2 per cent by"weight of the total reactants of an activated clay catalyst. The mixture was refluxed and agitated at 220 F. for a period of twelve hours. The temperature was then raised to 280 F. and all water, both that added with the formaldehyde and formed in the reaction, was distilled off. The product was then filtered and had the following properties:

' Gravity: API

Color. NPA 1 1.75 Neutralization No 0.44

Example IL-An addition agent was prepared by reacting 2 mols of benzyl benzoate, 1 mol of N-dimethylaniline and 2 mols ofiformaldehyde in the presence of 5 per cent by weight of the total reactants of an activated clay catalyst under the conditions set forth in Example I. The product had the following properties: i,

Gravity: API

1.8 Color, NPA 1.5 Neutralization No 0.60

Example II I.-An addition agent was prepared by reacting 2 mols of benzyl benzoate, 4 mols of N-dimethylanilineand 6 mols of formaldehyde agents. In the following examples, the base oil and the same oil blended with our new addition agentsare subjected to a standard oxidation test which measures the stabilitly of the oils to oxidation. The oxidation test referred to is a standard test described in "ASTM Standards'on Petroleum Products and Lubricantsflf September1943, pages 17-20. Briefly, the test comprises subjecting the .011 sample to oxygen at a temperature of 05 C.

(203. F.) in the presence of water and an ironcopper catalyst, and determining the time required to build up a neutralization number of 2. The flow of oxygen is maintained at 3 liters per hour. The remarkably eflective stability to ox-,

idation of mineral oil lubricant compositions containing our new addition agents is illustrated by the results shown in the following examples.

& Example IV.To a motor oil, which had been highly refined by an aluminum chloride treatment, there was added 0.5 per cent by weight of the addition agent prepared in accordance with Example I. A comparison of the base oil and improved oil follows:

Base Oil Improved Oil Gravity: API 29.8 29.6 Viscosity. SUV, 210 F 78.0 76. 8 Color, PA 2. 0 2. 6 Neutralization No 0.01 0. 02 Oxidation Test, ASTM Proposed 203 F. 8 L. 0 gen per Time 0 dined. no 3500+ Neutralization No 2. 0

As shown in this example, the improved oil had an oxidation stability of more than 3500 hours, but

, the neutralization number had not yet reached 2.0.

in the presence of 6 per cent by weight of the total reactantsof an activated clay catalyst under the conditions set forth in Example I.- The product had the following properties:

Gravity: API 2.4 Color, NPA I 2.0 Neutralization No 0.52

The condensation products obtained in accordance with the above disclosure from benzyl benzoate. N-dimethylaniline and formaldehyde in the presence of an activated clay catalyst are excellent addition agents for mineral oil lubricants. They are readily soluble'in'all types of mineral oils, that is, paraillnic, naphthenic or mixed base mineral oils and can be blended with mineral oils in high 5 proportions toform concentratedsclutions thereof, which may then be diluted down to the proportions desired in the final mineral oil lubricant composition. As stated, our new addition agents are remarkably eil'ective'in inhibiting the oxidatlve deterioration of mineral oil lubricant compositions. For this purpose small amounts of our new addition agents are generally sufllcient. For example, our addition agents maybe added to min-' eral lubricating oils in minor amounts, say from 0.001 to l per cent by weight on the mineral oil,

suflicient to inhibit the oxidative deterioration-of.

the oil. Larger-amounts of our new addition agents may be used if desired but it is ordinarily unnecessary to do so. j

The following examples illustrate the remark- Example V.-An improved steam turbine oil was prepared by adding 0.5 per cent by weight of the addition agent prepared in accordance with Example II to a turbine oilbase. A comparison of the base oil and the base oil blended with the antioxidant showed the following results:

Base Oil Improved Oil Gravi =irr.'.- 2st 28.5 0x ide t 11 Iest, .ad'll Proposed 203 x n r rum Oxidfiedj Hrs 180 0000+ Neutralization No"... 2. 0

Here again, the improved oil showed an oxidation stability of more than 3000 hours, but the neutrallzation number had not yet reached 2.0.

The above examples show the remarkable oxidation stability imparted to mineral oil lubricant compositions by the use of our new addition agents. Mineral oil lubricant compositions containing our new addition agents are therefore hydroxybutanal) for formaldehyde.

eminently suited for use where the operating conditions are extremely severe, as in Diesel, tank and truck engines, and in the lubrication of steam turbines. F

The remarkable effects of our new addition agents cannot be readily accounted for and can- ;not be predicted from the nature of the reactants. Thus. condensation products prepared from .other functionally similar compounds have been found to be either prooxidant or to show no antioxidant eflects whatsoever. For example, we

have prepared a condensation product similar to our new addition agent by substituting aldol (3- The resulting condensation product was found to be entirely unsuitable for inhibiting the oxidative deterioraable antioxidant ei'iects or our new add tion 76 tlonof mineral oil lubricant compos ons.

' tion product being 1' to 6 mols of N-diinethylaniline and 0.5 to 6 mols of formaldehyde per mol of benzyl benzoate in the presence 'of an'activated clay catalyst at a temperature not in excess of 350 F., and recover?- ing the condensation product.

2. The process of preparing an addition agent for mineral oil lubricants which comprises condensng from 1 to 4 mols of benzyl benzoate, 1 to 6 mols of N-dimethylaniiine and 0.5 to 6 mols of formaldehyde per mol of benzyl benzoate in the presence of 5 to per cent by weight on the total reactants of an activated clay catalyst at a temperature of from 150 to 300 F-., and recovering the condensation product.

3. The process of preparing an addition agent for mineral oil lubricants which comprises adding from 1 to 4 mols of benzyl benzoate, 1 to 6 mols,

of N-dimethylaniline, 0.5 to 6 mols of formaldehyde per mol of benzyl benzoate, and an activated clay catalyst to a mineral lubricating oil, heating the mixture to a temperature not in excess of 350 F. to form a condensation product, and recovering a solution of the condensation product in the mineral lubricating oil. a

4. The process of preparing an addition agent 'for mineral oil lubricants which comprises condensing 1 mol of benz'yl benzoate, 6 mols of N-dimethylaniline, and 6 molsof formaldehyde in the presence of about 8 per cent by weight on the total reactants of an activated clay catalyst at a temperature of from 150 to 300 F.. and recovering the condensation product.

5. The process of preparing an addition agent for mineral oil lubricants which comprises condensing 2 mols of benzyl benzoate, 1 mol of N-- dimethylaniline and 2 mols of formaldehyde in the presence of about 5 per cent by weight on the total reactants of an activated clay catalyst at a temperature of from 150 to 300 F., and recovering the condensation product.

6. The process of preparing an addition agent for mineral oil lubricants which comprises condensing 2 mols of benzyl benzoate, 4 mols oi N-dimethylaniline and 6 mols of formaldehyde in the presence of about '6 per cent by wei ht on the total reactants of anactivated clay catalyst at a temperature of from 150 to 300 F., and recoverin; the condensation product. a

'7. A non-resinous condensation product of from 1 to 4 mols of benzyl benzoate, 1 to 6 mols oi N dimethylaniline and 0.5 to 6 mols of formaldehyde per moi of benzyl benzoate, said condensaobtained by the process of claim 1. v

8. A non-resinous condensation product of 1 moi of benzyl benzoate, 6 mols or N-dimethylaniline and 6 mols 0! formaldehyde, said condense-- tion product being obtained by the Process or claim 4.

9. A non-resinous condensation product of 2 mols oi benzyl benzoate, 1 mol oi-N-dimethyianiline and 2 mols of formaldehyde, said condensation product being obtained by the process of claim 5.

10. A non-resinous condensation product of 2 mols of benzyl benzoate, 4 mols of N-dime'thylani- 3 line and 6 mols of formaldehyde, said condensa- I amount, sufficient to inhibit the oxidative de.--

terioration of said 011 of a non-resinous condensertion'product of from 1 to 4 mols of benzyl benzoate, 1 to 6 mols of N-dimethylaniline and 0.5

to 6 mols of formaldehyde per mol of benzyl ben-' zoate, said condensation productbeing obtained by the process of claim 1. v

13. A lubricant composition comprising a major am'ountof a. mineral lubricating oil, and a minor amount, from 0.001 to 1.0 per cent by weight of said'oil, of a non-resinous condensation product of from 1 to 4 mols of benzyl benzoate, 1 to 6 mols of N-dimethylaniline and 0.5 to 6 mols or formaldehyde per mol of benzyl benzoate, said condensation product being obtained by the process of claim 1.

14. A lubricant composition comprising a major amount or a mineral lubricating oil, and a minor amount, suiiicient to inhibit the oxidative deterioration of said oilof a non-resinous condensation product of 1 mol of benzyl benzoate, 6 mols oi N-dimethylanillne and 6- mols of formaldehyde, said condensation product being obtained by the process of claim 4.

15. A lubricant composition comprising a major amount of a mineral lubricating oil, and a minor amount, sufficient to inhibit the oxidative deterioration of said oil of a non-resinous condensation product of 2 mols of benzyl benzoate, 1 mol of N -dimethylaniline and 2 mols of formaldehyde,

said condensation product being obtained by the process of claim 5.

16. A lubricant composition comprising a major amount of a mineral lubricating oil, and a minor amount, suilicient to inhibit thev oxi'dative deterioration of said oil of a non-resinous condensation product of 2 mols of benzyl benzoate, 4 mols of N-dimethylaniiine and 6 mols of formaldehyde,

said condensation product being obtained by theprocess of claim 6.'

HERSCHEL G. SMITH. TROY L. CANTRELL,

JOHN G. PETERS.

1 REFERENCES CITED The following references are of record in the file of this patent:

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