US2137784A - Lubricant and method of lubricating - Google Patents

Description

Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE LUBRICANT AND METHOD OF LUBRICATING tion of Delaware No Drawing. Application December 29, 1937, Serial No. 182,300

17 Claims.

This invention relates to lubricants and more particularly to compositions capable of providing efllcient lubrication under conditions of extreme pressure. It is also an object of this invention to provide a method of improving the lubricating properties of lubricating oils especially where relatively moving metallic surfaces acting with inter-surface pressures which may be considerably in excess of 10,000 pounds per square inch are encountered.

This application is a continuation in part of application Serial No. No. 31,720, filed July 16, 1935, application Serial No. 170,500, filed October 22, 1937, and application Serial No. 649,734, filed December 31, 1932. The problem of providing for the lubrication of relatively moving metallic surfaces acting with inter-surface pressures which may be considerably in excess of 10,000 pounds per square inch is becoming of increasing importance since such pressures are, for example, now commonly encountered in hypoid gears, bearings, and contact surfaces of cylinders and piston rings in internal combustion engines, and are becoming more prevalent with advances in modern machine design.

It is a principal object of this invention, therefore, to provide a method of lubricating and a method of improving the lubricating properties of lubricating oils.

A further object of this invention is to provide a lubricating composition which will prevent seizure and scoring of relatively moving metallic surfaces where the pressure per unit area between such surfaces may be substantially in excess of 10,000 pounds per square inch, or where, for any reason conditions of thin-film or boundary lubrication exist.

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 sets forth in detail certain approved combinations 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.

Broadly stated, this invention comprises a new lubricant comprising a halogenated ether as a primary or minor constituent when used in conjunction with lubricating oils, or, for certain purposes, as the sole lubricant.

The halogenated ethers, and especially the halogenated aromatic ethers, are unusually stable and have been found to be not only very effective extreme pressure addition agents to lubricating oils, generally the usual mineral oil lubricants, but also efiicient and desirable lubricants when used as the sole lubricating constituent under certain circumstances.

It is believed that under conditions of extreme pressure the halogenated ethers react chemically or physico-chemically with the metallic surfaces to form a non-fluxing surface which will not seize or score. This invention is not intended to be limited, however, by any particular theory or explanation of the action upon the metallic surfaces.

When used in conjunction with a lubricating oil an amount from about 0.1% and sometimes less to about 20% of the addition agent, based on the amount of oil, and often an amount ranging from about .25% to about 2%, is all that is required to render the finished lubricant eflicient under conditions of extreme pressure. In the case of gear lubricants, for example, somewhat larger quantities, from about 2% to about or more, may often be preferred but ordinary crank-case oils generally require no more than the lesser quantities indicated above, viz., about 0.1% to about 2%. When, however, the viscosity of the halogenated ether is sufficiently high (as for example, in the case of certain of the halogenated aromatic ethers, notably chlorinated diphenyl ether containing about 50% chlorine) or the particular usage requires little or no thickfllm lubrication the halogenated ethers may often beused in a substantially pure state or as the primary lubricating constituent, only that amount of mineral oil being present as may be required to afford the characteristics desired.

When used in conjunction with a mineral lubricating oil it is obvious that generally only such amounts of the addition agent may be included as are soluble in the specified amount 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 difilculty, especially if the incorporation is effected in the manner described in Cornell Patent No. 2,042,880, and since quite small percentages often give re markably improved results it is seldom of extreme 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.

Since, in general, the loss of the addition agent by volatilization will be less for compounds having a low volatility, the vapor pressure of the compounds should, for most purposes, be less than atmospheric pressure at temperatures up to 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. or preferably200 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 170 C., or preferably, 200 C.

All of the various halogens are effective when employed according to the present invention but chlorine is generally preferred inasmuch as it is the least expensive and one of the most effective of the halogens. Bromine and fluorine are more expensive and the latter is relatively dimcult to handle but they are each usable in accordance with this invention. Iodine is not so easily obtainable as the other halogens and is quite expensive but it also may be used to provide eifective addition agents in accordance with the present invention. It should also be noted that two or more ditl'erent halogens may be present in the same molecule. The brom-chlor and fluorinated chlorine or bromine compounds give especially satisfactory results.

Since halogenated diphenyl oxide is an excellent example of the halogenated aromatic ethers as disclosed in this invention, its properties and some methods of preparation will be discussed by way of illustration only and without any intent to limit the scope of the present invention.

Diphenyl ether may be halogenated, or more specifically chlorinated, so as to produce a material which consists almost entirely of substitution products by the use of a chlorine carrier such as iron, iron chloride, or aluminum chloride and maintaining the temperature at C. or higher. A product containing up to or about 45% chlorine may be easily prepared in this way. This product is a complex mixture of chlorine substitution products ranging from the monochlorup to and including the heptaor octachlor-diphenyl ethers. It is possible, however, to obtain halogenated diphenyl ether containing ten atoms of halogen and this invention is intended to include all of the various halogenated diphenyl ethers, whatever their halogen content. The product may be further refined by treating with solutions of alkalies, or solid alkalies, or alkaline earth oxides, to remove free acid and decompose such small amounts of addition products as may be present. The resulting product is itself a good lubricant with a high film strength; and may also be used to improve the lubricating quality, increase the film strength, and inhibit deterioration in useot mineral lubricating oil even when added in relatively small proportions.

The chlorinated diphenyl ether, prepared as tiescribed above, may be further refined by vacuum distillation. The higher boiling fractions (e. g. that boiling at 370 C. to 390 C. under atmospheric pressure) are extremely stable viscous liquids also having superior lubricating qualities and especially suitable as lubricants at high temperatures where high speeds are encountered (e. g. turbines operated with high-pressure superheated steam). The vacuum-distilled product also is a valuable addition-agent for mineral lubricating oils and notably improves such oils for use as lubricants in internal combustion engines; e. g. in lubrication of cylinder walls, valves, valve-stems, and crank-shaft and connecting-rod bearings. It is especially valuable for use in such engines running at high speeds and under high loads, e. g., aircraft engines, Diesel engines, etc.

The formation of chlorine addition products of diphenyl ether is favored by:

(1) Lower temperature (e. g. 100 C. or lower),

(2) Absence of chlorine carriers,

(3) Chlorination by a counter-flow process, i. e., where the flow of liquid is in a direction counter to that of the gas flow in a single container; or where, in a multiple-container apparatus, the liquid is advanced toward the source of chlorine.

When chlorinated diphenyl ether is prepared so as to contain a substantial proportion of addition products (e. g. a mixture containing about 45% chlorine with about one-fourth of the chlorine in the form of addition products), it is desirable to remove the less stable material by treatment with an alkali. This is conveniently done by heating with crushed quick-lime to a temperature near the maximum temperature to be encountered by the material when in use. For example, for use as an addition to mineral oil to be used as a lubricant for slow-speed bearings, gears, etc., where very high unit pressures are encountered but the maximum temperature is low, the chlorinated diphenyl ether containing chlorine addition products is advantageously treated with alkali at a temperature not to exceed, say 50 C. For use in a lubricant for highspeed gears, operating under high loads, the alkali treatment should be at a higher temperature, say 100 C. The higher the proportion of addition products in the mixture and the lower the temperature of alkali treatment, the more efiective the resulting product as an extreme pressure" lubricant or addition agent for increasing the film strength of other lubricants. However, it is advisable to carry out the alkali treatment at a high enough temperature to insure stability in service.

As above indicated, halogenated aromatic ethers may be prepared so as to be especially resistant to hydrolysis by attaching the halogen directly to a carbon atom which is part of the benzenoid ring structure. However, where operating temperatures of the lubricant are relatively low and film strength is a major desideratum, as in gear lubrication, it is generally desirable that the addition agent contain a substantial amount of halogenation products formed by an addition rather than a substitution reaction, since the compounds so formed provide unusually high film strengths. Where operating temperatures are relatively high, as in the ordinary crankcase, or where it is desired to use the lubricant in upper cylinder lubrication, ior example by adding the lubricant to the fuel, it is generally desirable that the addition agent contain only products formed by a substitution reaction since such products are of very high stability while still maintaining good film strength.

The following are other examples of halo-' genated ethers which may be used in accordance with the present invention:

Halogenated aromatic ethers Halogenated cli-aryl ethers Halogenated dibenzyl ether Halogenated dinaphthyl ether Halogenated dixenyl ether Halogenated alkyl aryl ethers Halogenated ethyl naphthyl ether Halogenated naphthol ethyl ether Halogenated phenyl amyl ether Halogenated phenyl ethyl ether Halogenated cyclic ethers (oxygen contained in the ring), e. g. furan Halogenated cyclo-aliphatic ethers, e. g. di-

cyclo-hexyl ether Halogenated aliphatic ethers.

It should be understood that the methods of preparation described above are intended to be merely explanatory and in no wise to limit the scope of the invention. The halogenated ethers may be prepared in any satisfactory way.

This invention is particularly advantageous when applied to oils intended for use in the crankcase of an internal combustion engine when such engine is equipped with bearings of the type illustrated by lead bronze, cadmium silver and cadmium nickel alloys, such alloys being especially subject to corrosion and the halogenated ethers, particularly the aromatic ethers generally, being remarkable for their chemical stability.

While mineral oil generally is the principal ingredient of the lubricant, it is not essential that it be the only ingredient other than the addition agent, provided that there should be no additional ingredient which is incompatible with said addition agent. It is within the contemplation of this invention to include, if necessary or desirable, such other addition agents as are commonly added to improve the viscosity index or cold test of the lubricant and a lubricating composition according to this invention which also has a separate oiliness-increasing agent has been found to be unusually effective.

Also, the halogenated ethers are entirely suitable as addition agents to such lubricating compositions as greases and bodied oils and perform the same functions therein as in crankcase oils.

Lubricating compositions containing halogenated ethers in accordance with this invention, depending upon the particular halogenated ether or combination of halogenated ethers employed, will possess one or more of the following desirable properties:

1. Increased film strength.

. Increased stability at high temperature. Increased oiliness.

Reduced wear.

. Lowered cold test.

. Increased specific gravity.

. Increased flash-point and fire point.

her modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the materials employed in carrying out the process, provided the ingredient or ingredients stated in any of the following claims or the equivalent of such stated ingredient or ingredients be em--*' ployed.

We, therefore, particularly point out and distinctly claim as our invention:

1. A lubricating composition including as a primary lubricating constituent a halogen-bearing ether in a lubricating oil vehicle.

2. A lubricating composition including" as a primary lubricating constituent a halogenbearing aromatic ether in a lubricating oil vehicle.

3. A lubricating composition including as a primary lubricating constituent a halogen-bearing cycle-aliphatic ether in a lubricating oil vehicle.

4. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition aifecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of a halogen-bearing ether.

5. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, 01' a halogen-bearing aromatic ether.

6. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition alfecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of a halogen-bearing cyclo-aliphatic ether.

7. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of

a halogen-bearing alkylated aromatic ether.

8. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition afiectingiits use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of a halogen-bearing alkyl-aryl ether having a vapor pressure less than atmospheric at a temperature of 140 C.

9. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein an eflfective amount up to based on the amount of mineral oil, of a halogenated ether.

10. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein an effective amount up to 10%, based on the amount of mineral oil, of a halogenated aromatic ether.

11. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein an effective amount up to 10%, based on the amount of mineral oil, of a halogenated cyclo-aliphatic ether.

12. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition improved by incorporating therein from about 0.25% to about 2%, based on the amount of mineral oil, of a halogenated ether. I

13. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition improved by incorporating therein from about 0.25% to about 2%, based on the amount or mineral oil, of a halogenated aromatic ether.

14. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition improved by incorporating therein from about 0.25% to about 2%, based on the amount of mineral oil, of a halogenated cycle-aliphatic ether.

15. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition aifecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of halogenated dixenyl ether.

16. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, of halogenated phenyl-ethyl ether.

17. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein a minor amount, based on the amount of mineral oil, oi halogenated di-cyclohexyl ether.

CARL F. PRU'I'ION. ALBERT K. SMITH.