US2069274A - Nonsludging oil - Google Patents

Description

Patented Feb. 2, 1937 UNITED STATES NONSLUDGING OIL Raphael Rosen, Cranford, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 30, 1933,

Serial No. 704,764

12 Claims.

The present invention relates to lubricating oils and to a process of making the same and in particular to oils of low sludging characteristics especially adapted to high temperature service.

The invention will be fully understood from the following description.

Sludge formation is particularly objectionable in oils used for high temperature lubrication, for example, in the lubrication of automotive engines. The causes of sludging are not clearly understood but it appears to bear some relation to the oxidation characteristics of the oil and to be aggravated by the presence of moisture. Sludge formation appears to be some form of polymerization or agglomeration of materials which have a low ratio of hydrogen to carbon and when these materials reach a suiiicient degree of polymerization or agglomeration they become totally insoluble in the lubricating oil from which they are produced. They thereupon separate and de- 2 posit on the valves, rings, grooves, underface of piston and in the crankcase of the engine. It'

has been noted that many highly refined oils show a high oxidation rate and while this is not clearly understood, it is believed that the refining treatment has removed oxidation inhibitors on the one'hand and in same manner eliminated the natural agents which have sludge dispersing powers.

It has been found that sludge formation can be reduced considerably by the addition of certain dispersing agents. Just What action these materials have is obscure but it seems clear that the sludging tendency of the oil can be greatly 35 reduced as measured either in actual operation in the engine or by the Sligh numbers of the oils. As indicated above, the action of these materials is obscure but it is believed that the action is perhaps two-fold, reducing the degree of agglomeration or polymerization, and maintaining the materials which have agglomerated in a stable suspended form so that the deposition does not occur in the engine.

The substances having sludge dispersing prop-. 45 erties are hydrocarbon oils which are, in the first place, of the highest boiling range readily obtainable, that is to say, they are markedly heavier than the oils ordinarily used for motor lubricants and should preferably be substantially undistillable and'obtained as residuals. They should likewise be of a strongly parafinic nature; that is to say, with a ratio of hydrogen to carbon corresponding as closely as possible to the parafiin series of hydrocarbons but they should be freeflowing liquids. Heavy cuts of naturally occurring oils, for example of bright stocks cylinder oils or their extraction products and the like possess sludge dispersing powers to a noticeable degree but it is feeble at best and such large quantitles are required that these substances are im- 5 practical, for example, to 30% or even as much as 50% are required to give a result comparable with that produced by as little as 1% of the synthetic oils which will be disclosed below.

In a prior application,Serial No. 704,763, filed 10 December 20, 1933, by the present inventor, there is disclosed a similar composition of matter comprising on the one hand a wax-free oil; for example, an oil which has been dewaxed, with various sludge dispersers, some of which are capable 15 of exerting pour inhibiting powers, if they had been used in the presence of a wax-containing oil.

The present case clearly distinguishes from the above application in that it relates exclusively to compositions of waxy or wax-containing oils with 20 sludge dispersers of the type which are incapable of substantially reducing pour point. I

The sludge dispersers which are used inthe present invention are produced synthetically and the physical characteristics are quite similar to the heavy naturally occurring paraflinic resid-i uals except that the dispersers are of higher molecular -weight and. higher boiling point. Among the condensationproducts those produced from oily liquid lubricating fractions of paraffin or mixed base crudes may be used. Condensation is accomplished by first rendering them unsaturated either by cracking or by other equivalent means, for example chlorination and dechlorination, and this first step is followed by condensation by means of aluminum chloride or other known catalysts of the same type. Cracked waxes may-be so condensed and these various unsaturated'materials may be condensed either alone or with aromatic hydrocarbons such as benzol or naphthalene, which serve as a condensation nucleus. It is understood, however, that the amount of the aromatic material is sufiiciently small so that the character of the condensation .product is substantially that of a saturated hydrocarbon, as shown by its high ratio of hydrogen to carbon.

Chlorinated oils may be condensed in the same manner as indicated above, either alone or in the presence of an aromatic hydrocarbon. Chlorinated waxes may, of course, be condensed alone or with aromatics such as naphthalene or benzol, but these give rise to pour inhibitors, if condensation is conducted at low temperatures, say below 150 or preferably 125 F., and such materials do not fall within the scope of the present invention, but on the other hand, if the condensation temperature is raised to 200 or 250 C., the product has substantially no pour inhibiting properties and is contemplated for use in the present compositions. Also, by increasing the proportion of aromatics to parafdnic derivative, non-pour inhibitors can be produced even by condensation at low temperatures. Condensation of liquid hydrocarbons conducted by electrical means, that is by the action of high frequency electric discharges, may be used also for the present purposes, namely, as sludge dispersing agents, but the analogous condensation products of wax are not contemplated since those materials show definite pour inhibiting characteristics.

In making the various materials outlined above it is preferable to select the heaviest naturally occurring oils or waxes, and it is found that petrolatum, for example, is more suitable as a starting material than parafiin wax. The condensation products are more effective than the naurally occurring oils and are ordinarily useful in proportions of 1 to 2%, and they should not be used in very much larger quantities than men tioned above because for some unknown reason, if the quantity is too great, the sludge dispersing power is lost. It is always preferable to use less than 5% of the material. In such quantities the condensation products do not appreciably afiect the other properties of the motor oils to which they are added, for example, when used in the optimum quantities viscosity need not be raised more than 2 to 5 seconds Saybolt at 210 F.

The sludge dispersing agents which have been disclosed above are particularly desirable when used in combination with inhibitors for oxidation. These latter materials are well known in the art but it has been found that they almost invariably increase the Sligh number of the oil to which they are added. This defect is entirely corrected when a sludge disperser is added in combination with the oxidation inhibitor so as to produce a stable oil of low Sligh number and low sludging characteristics. .Any of the known oxidation inhibitors may'be used and among these are mentioned the phenolic compounds, especially the cresols, diand tri-hydroxy phenols and cresols, resorcinol, hydroquinone and pyrogallol. The naphthols, such as alpha naphthol and beta naphthol or their alkylated derivatives, are also used; likewise the aromatic disulphides and mercaptans are satisfactory, as well as the aromatic or aliphatic polysulphides, particularly the trisulphides which are not corrosive. Inhibitors containing hydroxyl, amino, disulphide and polysulphide groups attached to an aromatic nucleus to which is also attached stabilizer groups such as oxygen or sulphur as an ether are particularly desirable. These materials are merely mentioned as examples of a very large or well-known class. Any of these may be used in the present compositions in conjunction with sludge dispersers of the class mentioned above.

As has been indicated above, the lubricating oils used in the present compositions are those containing wax, so as to have relatively high pour points. On the other hand, the sludge disperss agents are those condensation products which do not possess in themselves a power of reducing the pour points. It should be underood, however, that in addition to the sludge dispersing agents pour inhibiting substances may be added, for example of the type disclosed in U. S: 1,815,022, or those prepared by the condensation of chlorinated and subsequently dechlorinated hydrocarbon waxes or the condensation products produced by the electrical treatment of hydrocarbon waxes. Other pour inhibitors such as zinc, magnesium and aluminum, and other metallic salts of the group of acids produced by the air oxidation of paraffin wax, may also serve, but it is of course preferred to use hydocarbon products throughout.

The following examples of oils made in accordance with the present invention will illustrate the composition and the action of the materials.

Example I To a motor oil S. A. E. 20 ,with a Saybolt viscosity of 58 seconds at 210 F. is added as a sludge inhibitor 1% of a material made by blending parts chlorinated petrolatum with 30 parts of naphthalene at relatively high temperature, so as to obtain a thick oily condensate without any substantial pour inhibiting properties. oil showed a Sligh number (24 hours) or 30.5, sec Proc. Am. Soc. for Treating Materials 24,964, 11 (1924). The Sligh value of the blend containing the disperser was 18.9. There was no change in the pour point within the accuracy of the determination.

Ezrample II To the same base oil used in Example I is added 5% of a disperser made from polymerized fractions of cracked wax. The blended oil showed a 24 hour Sligh of 14.2. The particular material added was not a pour inhibitor.

Example III To an oil of the composition shown in Example II is added as an oxidation inhibitor .1% of alpha naphthol.

Example IV To a 20 S. A. E. motor oil is added 1% of a heavy oil produced by condensing a vapor phase naphtha with 30% of benzol. The condensation was accomplished with aluminum chloride. The original pour point was unaffected and the original Sligh (24 hours) was reduced from 30.5 to about 1.0.

While the present invention is mainly directed to oils for automotive engine lubrication, it is to be understood that it is not limited entirely to this field, since the invention is useful in various other fields, for example, in turbine oils as well as cable or other insulating compounds.

The present invention is not to be limited by any theory of the action of sludge dispersers or of oxidation inhibitors, nor to any particular members of either of those classes of substances, but only to the following claims in which it is desired to claim all novelty inherent in the invention.

I claim:

1. An improved lubricating oil of reduced sludging tendencies which comprises a wax containing mineral lubricating oil and a small quantity of a dispersion agent prepared by condensation of high boiling hydrocarbons at such elevated temperatures as to produce condensates without pour inhibiting properties.

2. Composition according to claim 1 in which the condensation is efiected by means of aluminum chloride and at temperatures above 200 C.

The original 3. Composition according to claim 1 in which high boiling olefin hydrocarbons are condensed in the presence of aluminum chloride and at temperatures above 200 C.

4. Composition according to claim 1 in which high boiling olefins are condensed with aromatic hydrocarbons in the presence of aluminum chloride and at temperatures above 200 C.

5. Composition according to claim 1 in which chlorinated paraffinic hydrocarbons are condensed in the presence of aluminum chloride at temperatures above 200 C.

6. Composition according to claim 1 in which chlorinated paraffinic hydrocarbons are condensed with aromatics in the presence of aluminum chloride at temperatures above 200 C.

7. An improved lubricating oil of reduced sludging tendencies which comprises a wax containing mineral lubricating oil and a small quantity of a dispersion agent prepared by condensing chlorinated petrolatum with naphthalene at a temperature above 200 C., said agent when prepared at such temperature not having pour inhibiting properties.

8. Composition according to claim 7 in which less than 5% of the dispersion agent is added to the oil.

9. Composition according to claim 7 in which between 1 and 2% of the dispersion agent is added to the oil.

10. An. improved lubricating oil of reduced sludging tendencies, which comprises a wax-containing petroleum lubricating oil containing in solution a small quantity of a dispersion agent comprising a synthetic hydrocarbon prepared by condensing high-boiling olefin hydrocarbons, obtained by dehydrogenating a fraction of a paraffinic and mixed base petroleum, at such elevated temperature as to produce a condensate without pour inhibiting properties.

11. A composition according to claim 1, in which said dispersion agent is prepared by condensing high boiling olefin hydrocarbon with cyclic hydrocarbons at such elevated temperature as to produce condensates without pour inhibiting properties.

12. A composition according to claim 7 in which said dispersion agent is prepared by condensing chlorinated petrolatum with about 30% of naphthalene at a temperature above 200 C., said agent when prepared at such temperature not having pour inhibiting properties.

RAPHAEL ROSEN.