US2318630A - Lubricating composition - Google Patents

Description

Patented May 1 1, 1943 2,318,630 I LUBRICATING COMPOSITION Carl F. Prutton, Cleveland, Ohio, assignorto The Lubri-Zol Cotporation, Wickliffe, Ohio, a. corporation of Ohio No Drawing. Application August s, 1938,

Serial No. 223,694

5 Claims.

The present invention relates as indicated to lubrication and more particularly to methods of lubricating and lubricating compositions characterized by their ability to withstand extreme unit pressures between the'bearing surfaces which the same are called upon to lubricate, without the disadvantages of instability and gum-forming tendencies which characterize many similar lubricating compositions now commonly available.

This application is a continuation in part of my copending applications Serial No. 7373070. filed July 26, 1934, and Serial No. 193,960, filed March 4, 1938.

It is a principal object of this invention to provide a lubricating composition utilizing certain compounds of sulphur as the means for providing the improved type of lubrication above identified, such compounds being used either in their pure state or admixed with lubricating compositions such as mineral oils and the like.

By extreme pressures, as referred to above, is meant pressures of or in excess of 10,000 pounds per square inch, such pressures now being con1-- monly encountered in hypoid gears, bearings, contact surfaces of cylinders and piston rings in internal combustion engines, and many other points. Such pressures tend to cause the rupture of the continuous thick film of lubricant which separates bearing surfaces under more moderate conditions. A region of thin film lubrication results which is also sometimes described as boundary lubrication.

It is therefore an object of my invention to provide a lubricating composition and method of lubricating which will afiord efiicient lubrication and protection to the relatively moving metallic surfaces under conditions of extreme pressure,

bricating oil it is obvious that generally only such amounts of the addition agent may be included as are soluble in the specified 'amo nt of oil. By the term soluble as herein used it is intended to indicate the ability to form not only true solutions but also any form of substantially permanently homogeneous composition when,

incorporated in mineral oil. With most of the compounds there is usually little difficulty, especially if the incorporation is effected in the manner described in Cornell Patent No. 2,042,880, and since relatively small proportions usually give improved results it is seldom of importance that the addition agents be oil-soluble in all proportions. Also, certain compounds are of value as gelling or bodying agents when used in amounts greater than are strictly soluble.

While for certain specialized uses the mom,- and di-sulphides may be employed as the sole lubricant this invention contemplates that in general they will be employed as addition agents either the sole addition agent or in combination with others) to mineral lubricating oils in amounts ranging from about .2% to about by weight, based'on the amount of mineral oil. From about V2% to 7%, or preferably from about 1% to about 5% will be found to be a de- Sir able proportion for general use although larger Other objects of this invention will appear as the description proceeds.

To the accomplishment of the foregoing. and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain approvedcombinations -of ingredients embodying my invention, such disclosed means constituting, however, but certain of various forms in which the principle of the invention may be used.

Briefly stated, my invention comprises the discovery that a certain class of sulphur compounds, namely the organic monoand di-sulphides, although stable and relatively chemically inactive at ordinary temperatures and pressures, will, nevertheless, when present in a lubricant film and subjected to the conditions imposed on the bear- When used in conjunction with a mineral luamounts up to about 10% or more. may be found more advantageous for certain uses. The proportion added, however, is often limited by the limit of solubility in the particular oil. The final products should contain an amount of the addition agent sufiicient to increase the film strength of the lubricant, to a substantial degree. The required minimum amount will usually be found to be about 0.2%, in order that the lubricant may exhibit sufficient extreme pressure properties to be commercially feasible.

Although the oil base is referred to above as a mineral lubricating oil it is to be understood that any other suitable hydrocarbon lubricating oil, whether naturally occurring orsynthetic may be employed as the oil base. For most purposes mineral lubricating oils having a viscosity from about 50.to 250 second Saybolt at 210 F. are

entirely suitable, and for certain purposes, as for example'gear lubrication, a viscosity range of to 200 seconds is desirable. v

It' is aso within thev contemplation of this invention to provide the addition agent in the form of a concentrate in a suitable ,oil, said oil containing rather high percentagesof the addition agent. Such concentrates are employed for future blending with a lubricating oil in the proportions desired for the particular conditions of use.

When still greater resistance to extreme pressure conditions is desiredthan that afforded by the addition agent ofth is i nve tio l t v a 2 often be found advantageous to employ a small amount of a separate organic halogen compound in the lubricant which will cooperate with the addition agent of this invention to increase the film strength (e. g. as indicated on the Almen Machine) to a degree greater than the sum of Obviously the addtion agent chosen should be sufficiently oil-soluble so that the amount used the effects of either addition agent when employed alone. I Since, in general, the loss of the addition agent by volatilization will be less for compoundshaving a low volatility, the vapor pressure of the Coastal oils and lower for the viscous Pennsylcompounds should, for most purposes, be less.

than atmospheric pressure at temperatures up to 140 C. It is usually desirable, especially for use in internal combustion engines, that the vapor pressure be less than atmospheric at temperatures up to 170 C. In the case of compounds which are stable at temperatures up to their boiling-points, this condition may be expressed by stating that the boiling point of the compound should, in general, be higher than 140 C., and for certain uses, such as in internal combustion engines, higher than 70 C.

' Examples of the types of compounds which may be employed in accordance with my invention are the di-aryl and di-alkyl sulphides and di-sul-phides and also sulphides and di-sulphides containing both an alkyl and an aryl radicle, e. g.:

-Di'-alkyl sulphides, e. g.:

'Di-amyl sulphide Di-lauryl sulphide Arylated alkyl sulphides, e. g.:

Dibenzyl sulphide Di-aryl sulphides, e. g.-: Di-phenyl sulphide ni alkyl disulphides, e. g.:-

Di-ethyl disulphide Di-n-butyl disulphide Di-amyl disulphide Arylated alkyl disulphides, e. g.:

Di-benzyl disulphide Di-phenyl di-ethyl disulphide (CeHs-C2H4-S)2 Di-methyl di-benzyl disulphide (CH3CsH4-CH2-S) a Di-aryl disulphides, e. g.: Di-phenyl disulphide Alkylated aryl disulphides, e. g.:

Di-tolyl disulphide Di-xylyl disulphide Mixed aryl-alkyl sulphides and disulphides methyl phenyl sulphide and disulphide ethyl phenyl sulphide and disulphide amyl phenyl sulphide and disulphide .Certain classes of these sulphur compounds may be defined as:

( Disulphides having the general formula: R.-'S-s-R1, wherein R and R1 represent substituents selected from the group consisting of alkyl groups or hydrocarbon phenyl groups.

(2)' Organic sulphides having the general for mula R.SR.1, wherein R and R1 represent (a) alkyl groups containing at least 5 carbon atoms each, or (b) phenyl groups or akyl groups containing from 5 to 6 carbon atoms each. I

The alkyl derivatives of the aryl disulphides (e. g., di-xylyl disulphide) and the aryl derivatives .of alkyl disulphides (e. g., diphenyl diethyl disulphide) are particularly desirable not only because of their effectiveness but also because of their ready solubility in mineral oils.

vania oils in the case of mineral oils.

From the point of view of solubility, the most advantageous conditions would generally result from the use of a compound which is liquid and miscible with the oil-base used. An example of such compound is diphenyl sulphide.

While mineral oil generally is the principal ingredient of the lubricant, it isnot essential that it be the only ingredient other than the addition agent, provided that there be no additional ingredient which is incompatible with such addition agent. It is within the contemplation of this invention to include, if necessary or desirable, such other addition agents as are commonlyadded to improve the viscosity index or cold test of thelubricant and a lubricating composition according to this invention which also has a separate oiliness increasing agent has been found to be especially effective.

While the lubricating compositions which have been described herein as illustrating one embodiment of the invention have been generally referred to as oils, i. e., liquids, this invention is, however, also especially applicable tothe solid and semi-solid types of lubricants commonly referred to in the trade as greases, bodied oils, etc., and which may contain soaps such as sodium, calcium, lead and aluminum naphthenates, stearates and oleates.

It should be noted that the addition agents of this invention are relatively chemically stable and will therefore have no corrosive action upon the metal surfaces with which the lubricant comes in contact.

Other modes of applying the principle of my invention may be .employed instead of the one explained, change being made as regards the composition and method herein disclosed, provided the ingredients or steps stated by any of the following claims or the equivalent of such stated ingredients or steps be employed.

I therefore particularly point out and distinctly claim as my invention:

L'An improved lubricating composition comprising a major'proportionof mineral lubricating oil the film strength of which is increased by the inclusion therein of a liquid, oil-miscible organic sulphur compound selected-from the class consisting of the organic sulphides and organic disulphides. ,y 2. An improved lubricating composition comprising -a major proportion of mineral lubricating oil the film strength of which is increased by the inclusion therein of a liquid, oil-miscible organic sulphur compound selected from the class consisting of the aryl sulphides and aryl disulphides. I 3. An improved lubricating composition comprising a major proportion of mineral lubricating oil the film strength of which is increased by the inclusion thereinof. a liquid, oil-miscible organic sulphur compound selected from the class consisting of the aryl sulphides.

organic sulphides and disulphides.

5. An improved lubricating composition com prising a major proportion .of mineral lubricating oil, the film strength of which has been increased by the inclusion therein of a minor amount of a liquid, oil-miscible organic sulphurcompound selected from the class consisting of organic sulphides and disulphides of the type in which the sulphur is attached to a benzenoid ring structure.