US2371631A - Lubricant - Google Patents

Description

Patented Mar. 20, 1945 LUBRIOAN '1 Bert H. Lincoln and Gordon D. Byrkit, Ponca City, Okla., assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware No Drawing. Application January 4,1941,

t Serial No. 3'l3,18\6

mime. (01. 252-48) This invention relates 'to improvements in 111- bricants. More specifically, this invention relates to improved materials which, when added to lubricants, greatly increase their resistance to oxidation and formation of corrosiv products during use and often improves other characteristics as well. This is a continuation-in-part of our'co-pending application, Serial No. 230,661,

- filed September 19, 1938. 1

Present-day mechanical devices require lubricating oils of high film strength and of high oiliness characteristics. It has been found that the of reacting with the metal surfaces, penetrating or adsorbing on the metal surfaces, and leaving a film of lubricant with high oiliness character, which remains on the metal surface irrespective of the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which may be easily discerned by the experienced operator or lubricating enpresent-day hydrocarbon lubricants of the very highest quality are deficient in .these two very important characteristics. Thesetwo properties are of vital importance under conditions of thin film lubrication where the lubricanthas been squeezed from between the friction surfaces because of high pressure, slow speeds, and other causes. It is readily seen that the viscosity or the body of the lubricant plays no part in this type of lubrication and that the remaining film of oil must have a very high film strength and be of high oiliness value to prevent rupture of the filmof the lubricant, which would cause seizure.

of mechanical devices.

Substantially all machines operate in part or at times totally under conditions of'boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of efficient operation.

Those skilled in the art of lubricant manufac-' ture or machine manufacture will readily appreciate the value of an invention that will improve the oiliness of these otherwise high-quality lu-' bricants.

In starting idle mechanical equipment which is lubricated from a sump by pumping or circulating the lubricant, there is always a short period of time in which the rubbing surfaces must operate under conditions of dry friction if ordinary hydrocarbon lubricants are used. With dry friction, the wear on friction surfaces is extreme;

and during cold weather when the lubricant is sluggish or during periods when the lubricating system is not functioning properly for one reason or another, rubbing surfaces may not only suffer considerable wear but may be damaged to the point where they must be replaced. The product p of our invention has a very important property gineer.

When the hydrocarbon lubricants are diluted with unburned fuel orv with other light hydrocarbons, the small degree of oiliness of the original hydrocarbon lubricant is greatly decreased. We have found that the addition of the products of our invention to hydrocarbon lubricants more than compensates for the loss in oiliness and load-carrying ability from dilution.

It is well known that, in order to obtain lubricants which are preeminently satisfactory from the standpoint of oxidation in use, it is neces-- sary to refine the oil thoroughly and then to add an inhibitor of oxidation. The thorough refining may consist of more and heavier acid treatments or solvent treating so as to remove a considerable part of the oil and leaveonly the most stable portion- Such'drastic refining is necessary in order to obtain stability with respect to sludge formation, but the oil is then subject to easy oxidation to form soluble acids and other corrosive materials. It is practically impossible to refine an oil so as to avoid all of thesedifficulties. It is better to refine the oil thoroughly and then add small amounts of materials which either prevent the formation of these corrosive products or by some action render them inert.

Many of these additive materials are effective when added to poorly refined or even wholly unrefined lubricants. The addends may thus be substituted in whole or in part for the usual refining processes.

In the prior art of applying these principlesto the manufacture of lubricants, many diverse types of materials have been suggested to be added to obtain improvement in various characteristics, but the esters of phosphorus acids with certain polyhydroxy organic compounds form a new type of material. We have found that the addition of these organic esters of the oxygen and sulfur acids of phosphorus improves film strength, oxidation resistance, noncorrosiveness, and other characteristics to an exceptional'degree.

One object of our invention is to provide improved inhibitors of oxidation and corrosion for addition to lubricants.

Another object of our invention is to provide film strength improving addition agents suitable for use in lubricants and especially in crankcase lubricants.

Other and further objects of our invention will appear in the course of the following description.

'chlorine or one of the other halogens, sulfur, or

nitrogen. Esters of these substituted polyhydroxy organic compounds contain considerably more phosphorus than esters of monohydroxy organic compounds and are thus considerably more efficient. The negative element (halogen,

sulfur, or nitrogen) in the organic radical apparently functions to make the phosphorus a more effective improver of film strength and/or inhibitor of oxidation. Some of the esters which are suitable for use according to our invention are chlororesorcinol phosphate, chloroethylene glycol phosphate, chlorocyclohexandiol phosphate, triethanolamine phosphite, thiodiglycol thiophosphate, and thiodiglycol phosphite.

Any of these compounds or other members of the classes represented or their derivatives within the limitations set forth above may be used within the scope of our invention. It will be noted that in addition to the elements C, H, O, and P our products contain halogen, sulfur, and/or other elements as well.

blended with ordinary lubricants. It will be obvious to those skilled in the art thatsuch a structure is impossible in the phosphorus esters of monohydric alcohols, phenols, and the like.

Compared with other esters of the acids of phosphorus and with other types of addends for lubricating oils, our materials are more stable to heat, pressure, and oxidation. When blended in lubricants, they produce oils which are less as little as 0.001 percent of some of these com- These materials form viscous liquids rather I (taking chloroethylene glycol and phosphoric acid, for example, as the reactants) 0 II If -OCHCICH2O TOCHCICHzO POCHCIGH2O FOCHClOHzO- H H OH Further reaction produces third dimensional condensation products:

0 l I I Heating the reactants further produces branches again on the preformed chains until an extremely large and viscous macro molecule results. We believe it is this uniqu type of structure of our products which lends such striking properties of film strength, viscosity index improvements, low cold test, and stability toward oxidation and formation of corrosive products during use when pounds, audit will be seen that a fairly insoluble material may dissolve to a sufiicient extent to be satisfactory for our purpose. In general, more than 0.001 per cent of our addition agents are used; and we may add one, two, or even five per cent or more.

Furthermore, it is well known that different types of oils have different capabilities of dissolving a given material. For some purposes therefore, we prefer parafiinic, for other purposes asphaltic, naphthenic or mixed base lubricants. Another method of obtaining a satisfactory mixture of addition agent with the hydrocarbon oil is the use of a mutual solvent to bring the addend into solution; Alternatively, peptizing agents may be added to maintain the ester in permanent suspension.

Many of the more difiicultly soluble materials are rendered more soluble by the introduction of alkyl groups, particularly those containing four or more carbon atoms. The isoamyl, octyl,

'lauryl, and octadecyl radicals and radicals from paraflin wax greatly increase the solubility of organic compounds in oil. One or more of such groups may-be introduced as required. For example, chlorohydroquinone phosphite is not very soluble in hydrocarbon lubricating oils but triamyl chlorohydroquinone phosphite is much more soluble.

The selection of a particular-compound or compounds to be used as an addition agent to the hydrocarbon oil is to be made considering the use to which the blend is put. If a particular added phosphorus, compound proves too volatile for its application, a higher boiling phosphorus compound should be used and the more volatile compound used for blending in a hydrocarbon oil intended for duty at lower temperature. In general, we prefer to use; compounds having boiling points over 250 degrees F.

It is sometimes advantageous to combine more than'one of these compounds in a blend to ob- ,tain particular properties.

' prove both the film strength and oxidation char- -very important, and these are markedly improved by our compounds. The ability to reduce friction is another feature contributed to lubricants by our phosphorus esters.

It is usually desirable to include in one and the same blend based on a hydrocarbon oil, in addition to the addends here described, other addends for specific purposes. point depressor such as a naphthalene-chlor wax condensation product anda viscosity index improver such as certain resins or polymerized hydrocarbons in addition to our phosphorus esters. Furthermore, various metallic compounds may be added to the blend without interfering with the action of our ingredients. Indeed, in some cases it is advantageous to combine with our phosphorus esters in a hydrocarbon oil blend such materials as calcium dichlorostearate, chromium oleate, tin octadecyl phthalate, aluminum stearate, and other metallic soaps.

Our addends are admirably adapted for use in lubricating oils of all types including those designed for use in automotive crankcases, Diesel oils, and any other'oils of lubricating viscosity. By an oil of lubricating viscosity in the appended claims, we mean to include the so-called hydrocarbon or mineral oils, animal and vegetable oils, including castor oil, corn oil, soybean oil, lard oil, fish oils, and various synthetically treated oils including aluminum chloride treated oils,

hydrogenated oils, voltolizedoils, and all types of synthetic lubricants. Our addends are advantageously blended in gasoline and other fuels either directly or after being blended first in a lubricating oil and then added to the fuel. Soapthickened mineral oils of all types ranging from those showing only a slight increase in viscosity over that of the mineral oil alone to the semisolid and solid-greases containing fifty per cent or more of soap are amenable to treatment according to our invention. In making these greases, the usual soaps such as sodium stearate, aluminum stearate, calcium soaps of beta fat, and the like may be used. Various other thick ening ingredients for other purposes may be added. These include yarn, hair, graphite, glycerol, water, lampblack, mica, zinc dust, litharge, and the like.

The following examples of blends of our addition agent are given as illustrations and not as limitations:

Example 1 I Per cent Mid-Continent paraflin base S. A. '13. 3'0 99.0

Diphenyl-chlorwax condensation product--- 0.5

Thus we may add a pour Chloro-ethylene glycol phosphate 1.0

Example 2 Per cent Mid-Continent mixed base 8. A. E. 30 98.4 Aluminum naphthenate 1.3 Chlororesorcinol phosphate 0.3

Example 3 Per cent Parafiin base bright stock 58.0 Paraflin base neutral oil 40.0

' Sulfurized methyl esters of corn oil fatty acids 0.2 Thiodiglycol phosphite 0.3 Calcium dichlorostearate 1.0

Example 4 Per cent Mid-Continent paraifin base S. A. E. 40.1... 93.8 Voltolized soybean oil 5.0 Chlorodiphenylene. oxide 1.0 0.2

Triethanolamine phosphite Example 5 In making a grease containing our addends, we may use:

Distillate (440 seconds at degrees F.)-. 76.0 Chloro-ethyl cellulose phosphate 0.2

Example 6 In making a lubricating gasoline, we blend 0.5

per cent of the product of Example 1 with, gasoline. The product has the composition:

Per cent Gasoline 99.5 Oil 0.495 Chloro-ethylene glycol phosphate 0.005

' It will be understood that certain features and sub-combinations may be employed without reference to other species or combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention.' It is therefore to be understood that our invention is not to be limited to the details described. i

Having thus described our invention, we claim: 1. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of an ester of an acid of phosphorus and a polyhydroxy organic compound which contains an element selected from the group consisting of halogens, sulfur, and nitrogen directly attached to a carbon atom of the polyhydroxy compound, said ester increasing the resistance of the lubricant to oxidation and to the formation of corrosive products during use.

2. A lubricant comprising an oil of lubricating viscosity and from 0.001 to 5 per cent of an ester of an acid of phosphorus and a polyhydroxy organic compoun which contains an element selected from the group consisting of halogens, sulfur, and nitrogen directly attached to a car- -bon atom of the" polyhydroxy compound, said ester increasing the resistance of thelubricant to oxidation and to the formation of corrosive products during use.

3. A lubricant comprising of oil of lubricating viscosity and a minor proportion of chloro-resorcinol phosphate.

4; A lubricant comprising a major proportion .of oil of lubricating viscosity and a minor propora major proportion