US2156265A - High pressure lubricant - Google Patents

Description

Patented May. 2, 1939.

UNITED STATES HIGH PRESSURE LUBRICANT Floyd L. Miller and Charles F. Smith, Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware no Drawing. Application November 21, 1933,

Serial No. 699,033

3 Claims.

The present invention relates to lubricants, especially to the class known. as extreme pressure lubricants and more particularly .to improved lubricants of this type and the method of manufacturing same.

The invention will be fully understood from the following description:

Within the last few years a considerable demand has arisen for lubricants, both solid and liquid, which are capable of withstanding loads which are inconsiderable excess of those possible withstraight or unblended hydrocarbon oils. This is especially the case for automobile transmissions and other power transferring mechanisms in which hypoid and other type gears are used. Among the compounds that have been proposed are those containing sulfur and chlorine in combination. These are fully capable of withstanding the pressures and otherwise give good lubricating characteristics but there are objections which have limited if not prevented general use. The main objection is that the compounds as ordinarily prepared are corrosive and since it is impossible to avoid small quantities of moisture, this results in discoloration of the gears and other mechanism, and 'in time, corrosion, pitting and rusting. Further, as a result of this corrosive action, there are formed oil insoluble abrasive materials which materially lower the lubricating value of such blends.

In the present invention a compound of the sulfur-chlorine type is proposed which while" carrying the load. only corrodes or rusts steel surfaces to a limited degree and then for only' a period of time whichi's short enough to be tolerated. Furthermore the present compound is effective over substantially the whole life of the oil, while in the case of many prior compounds the valuable load-carrying properties are lost after a relatively short period.

In the present high pressure compound use is made of a hydrocarbon base oil which is seiected for the particular use to which'the compound is to be adapted. Its viscosity is ordi-' narily'above 100 seconds Saybolt at 210 F. and may be in excess of 200 or even 300, depending on the particular service. The oil may be derived from ainaphthenic or a parafilniccrude and the cut may be a distillate or residue as desired. The flash point -isordinarily not of much significance for transmission oils but it is usually above 400 F. or 450 or even higher. The present compounds may be liquid or they may be solidified in which case aluminum, soda, or lime soaps such as those derived from tallow, stearic acid and the like may be added in proportions ranging from 10 to 50%. I

The sulfur-bearing compound is of the type 5 described as corrosive" which means that it discolors a bright copper strip immersed therein but it in fact has no appreciable action on steel gearsor metal containers in which it is kept. The amount of corrosive sulfur should be in excess of .2% and ordinarily from .30 to 3% or thereabout. Various compounds of sulfur may be used but it should be understood that sulfur exists in non-corrosive as well as "corrosive forms and therefore it is desirable to determine 16 the amount of corrosive sulfur and to blend od devised by the American Society for Testing ,Materials, D-l29-27, described in report of Committee D-2 on Petroleum Products and Lubricants and Method of Tests Relating to Petroleum. Products, page 174, 1928.

As to the sulfur-containing compounds, frac- 30 tions from certain crudes known to contain corrosive sulfur may be used and as an example of these residues from West Texas may be given, it being understood that other known crudes of the type may be used. Elemental sulfur may be added, alone or to fortify the other corrosive sulfur present. Animal, vegetable and fish oils may be sulfurized by treatment with raw or elemental sulfur at elevated temperatures. Organic polysulfldes may also be used. (0 For example, they may be prepared by chlorination of a mineral oil or wax by bubbling chlorine 'therethrough for a period of several hours or until itv contains from 5 to 30% chlorine. The

' chlorine may then be substituted by sulfur through the reaction with alkaline polysulfides,

I for example sodium or potassium polysulfldes."

In this way chlorine may be entirely replaced from the compound. It is important that the chlorine compound should be added separately so or in other words, that both the chlorine and sulfur be present in different compounds. This is important for it has been found that chlorinesulfur compounds, for example those produced by treating fatty oils with suifuryi chloride, 51

gradually lose chlorine on use and when chlorine is lost the sulfur is unable tocarry the. extreme pressure loads.

The chlorine compounds that can be used include chlorinated fatty oils and acids, chlorinated mineral oils and waxes such as paramn wax, carbon tetra chloride and the like. It will be understood that fluorine and bromine compounds are equivalents for the chlorine compounds and can be substituted therefor although the chlorine compounds are to be preferred. The halogen atom is preferably attached to an aliphatic car'- bon atom, but in many instances chlorine attached to aromatic rings is satisfactory.

It has been found that relatively small amounts of the chlorine compound are effective, for example, as little as .20 to .60% although somewhat more can'be used. In theproportion used the oil is not excessively corrosive even when first added in respect to the metal containers and machine parts, and it does not show rust or produce abrasive reaction products. The exact role of the chlorine is not understood but it is believed to be in the nature of an activator and in some manner permits the sulfur to take hold" gradually so that the friction-load curve is smooth and without sharp breaks. Whatever the action may be its effect is permanent in spite of the gradual loss of chlorine; for example it has been found that in automobile transmissions after or 200 miles the chlorine content has greatly diminished and c after 400 to .500 miles it has completely disappeared. This corresponds to a running-in period of from 10 to 15 hours use. The sulfur content is intact and it has remained in a corrosive" form. The oil, even after loss of chlorine is capable of withstanding high bearing and tooth pressures.

While not wishing to be limited to any particular theory of the roles of the two principal ingredients, it is believed that the chlorine serves to bring about reaction between the sulfur compound and the steel gear teeth and that once this has occurred to an extent sufiicient to properly activate a substantial portion of tooth area, no additional chlorine is required, the remaining corrosive sulfur gradually completing the reaction after elimination of the chlorine.

It will be seen from the above that the present compound is practically non-corrosive to steel surfaces in the sense that it does'not cause an appreciable rusting or formation of other abrasive compounds and furthermore that the chlorine is insuificiently small quantities so that it may be eliminated altogether in from 10 to 15 hours of use. By an eflective quantity it is intended to designate an amount suflicient to activate the Example I The base oil used in all of the following compounds is as follows:

Gravity degrees A. P. I

26.4 Viscosity at 210 F sec. Saybolt 120, Viscosity at 100 F .do 1565 Pour "F degrees Fahrenheit 5 Flash do 4'75 Color P To separate samples of the above .base stock are added: a

Sample 1, 8% ofsulfurized pine oil made by cooking such oil with sulfur at a temperature of 425 F. and thereafter containing 4.0% corrosive sulfur.

Sample 2, 8% of sulfurized pin oil and 1 of chlorinated paraflin wax containing 40% chlorine.

Sample 3, the base stock alone.

The following tests were made on the Almen machine as described in Automotive Industries vol. 67#21 p. 650. v The total number of weights carried in the tests, the weight at which friction increases suddenly (if such be the case) the final friction, temperature and condition of hearing are recorded for each test:

As a second example the following tests were run on the Almen machine. The base oil is a 100 sec. (Saybolt at 210 F.) Pennsylvania fraction. Various different solutions are added thereto in order to obtain the amounts of corrosive sulfur and chlorine as indicated. The number of weights carried is recorded, together with final friction, and comments as to bearing conditions. From an inspection of the table it will be seen that the best conditions are .2 t0.5% or more corrosive sulfur with .3 to .5% chlorine. All except one of the samples within this range carried the full 15 weights and the other one carried 14 weights. The oil alone fails at about 5 or 6 weights. None of the oils are corrosive toward the metal gears and do not produce appreciable quantities of solid abrasive solvents.

Almen test Percent Percent Bllgagd dfi diner. w hts F" iii 5 ur ne eig in Carried friction Bearing condition 0. 2 0. l 6 l5 Welded. 0.2 0.3 15 29 Good. 0. 2 0. 5 14 28 Welded. 0.5 0.1 15 57 Scratched. 0.5 0.3 15 63 Scratched. 0.5 0.5 15 35 Good. 1.0 0.1 15 55 Scratched (poor). 1. 0 0. 3 15 48 Scratched. l. 0 0. 5 15 53 Scratched.

Example III As an illustration of the effect of chlorine elimination during use, the samples made up according to the present invention and'samples of ordinary lubricants containing a so called extreme pressure agent produced by action of sulfur chloride on a fatty oil were subjected to treatment with steel 'wool at 300 F. for different periods of time. As indicated this treatment eliminated chlorine just as it is removed during use. Tests on the treated oils were then run on the Almen machine showing that the sulfur chloride oil rapidly lost its extreme pressure characteristics while the oil produced according to the present invention did not.

' Analysis of oil Almen mam or 1 8"! treatment chine test 6 steel '02:. a

Percent Percent Load Fricsullur carried on Commercial sullur chlorine lub 0 99 62 15 33 o 6 1. l1 49' 14 90 8 l. 15 34 6 46 Example blend..... 0 4 5 i6 l0 4 Trace 15 vcorroded and there is no evidence of rusting.

The present invention is not to be limited to any theory of the mechanism of extreme preseral lubricating oil and chlorinated petroleum wax and an agent containsure lubricants of the present tape, the efiect of sulfur and chlorine, nor to any par cular sulfur or chlorine containing compound, but only to the following claims in which it is desired to claim all novelty inherent in the invention.

We claim:

1. 'An improved lubricant for extreme pressure conditions comprising a. major proportion of a mineral lubricating oil. a minor proportion of halogenated petroleum wax and an agent containing "corrosive sulfur.

2. An improved lubricant for extreme pressure conditions comprising a major proportion of minminor proportions of ing corrosive sulfur selected from the group consisting of elemental sulfur, and sulfurized ani-' mal, vegetable, marine and mineral oils. 3. An improved lubricant for extreme conditions comprising a major proportion of mineral lubricating oil and minor amounts of chlorinated paraffin wax and corrosive sulfur compounds dissolved therein.

FLOYD L. m. CHARLES r. sum.