US2204620A - Lubricating composition - Google Patents

Description

Patented June 18, 1940 UNITED STATES PATENT OFFICE LUBRICATIN G COMPOSITION Carl F. Prutton, Cleveland, and Albert K.

Shaker Heights,

Smith,

Ohio, assignors, by mesne assignments, to The Lubri-Zol Development Corporation, Cleveland, Ohio, a corporation of Ohio 2 Claims.

As disclosed in the application of Carl F. Prutton Serial No. 635,701, filed September 30, 1932, certain desirable improvements in the lubrieating properties of lubricating oils may be secured by the combination therewith of certain halogenated additions, particularly halogenated or more specifically chlorinated carbon ring compounds.

We have discovered that certain oxygen bearing or containing halogenated organic compounds used independently or in combination with any suitable oil baseproduce a lubricating composition equal to, and in certain respects superior to, the results secured by the addition of halogenated carbon ring compounds to a suitable oil base. The lubricating composition according to our invention is particularly applicablefor use as an extreme pressure lubricant.

For the definition of extreme pressure lubrication and the distinction thereof over low pressure or thick film lubrication. reference may be had to the specificationof the above mentioned application.

It is among the objects of our invention, therefore, to provide a lubricating composition which shall be superior to any which has heretofore been available.

Other objects of our 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 one approved combination of ingredients embodying our invention, such disclosed means constituting, however, but one of various forms in which the principle of the invention may be used.

Broadly stated, this invention comprises the use as lubricants of oxygen and halogen bearing or containing organic ring compounds used either independently or in combination with any suitable oil base such as pure mineral oil or an oil which contains sulphur in solution or in a stable form of colloidal suspension, either in uncombined form, or in the form of a sulphur compound.

We have found that oxygen. and halogen bearing or containing carbon ring compounds have excellent lubricating properties when used alone and particularly for certain classes of uses.

We have also found that compounds of. this type are capable of improving the lubricating properties of lubricating oils when added thereto even in relatively small amounts and particularly when such oil is employed for "thin film or extreme pressure lubricating purposes.

We have also found that certain oxygen and halogen hearing or containing derivatives of organic ring compounds of the heterogeneous ring type, i. e., compounds in which atoms other than carbonare included in the ring structure may likewise be used as lubricants or additions to lubricating oils.

The addition of these oxygen and halogen bearing or containing organic ring compounds to a suitable oil base have been found to improve the properties thereof to an even greater extent than certain similar halogenated hydrocarbons, notably when added in very small amounts.

The oxygen and halogen containing or bearing organic ring compounds, above referred to may be classified as follows, viz:

I. Carbon ring type compounds ((1) Of the aromatic, or allied type, including derivatives of benzene, naphthalene, anthracene, etc., also compounds of the bridged ring type, such as the terpenes, and related compounds.

(17) Of the class including the cycloparafiins, cyclo-olefines. etc. Examples of this class are derivatives of the following:

(1) Hydrogenation products of benzene (e. g.,

cyclohexane, cyclohexene, cyclohexadiene) (2) Hydrogenation products of naphthalene (e. g. decahydronaphthalene, tetrahydronaphthalene etc.)

(3) Naphthenes, naphthenic acid, etc.

01 mixed type such as derivatives of indene, hydrindene, hydranthracene, etc.

II. Heterogeneous ring type compounds ((1) Of the aromatic or allied type including derivatives of pyridine, quinoline, etc.

(b) Other types such as furan and its derivatives and derivatives of thiophene, pyrrole etc.

The foregoing compounds may also be classified according to the nature of the attachment of the oxygen to the compound, viz:

I. Directly attached to one or more carbon atoms, as in the case of:

This theory is substantiated by the fact that when a chlorinated hydrocarbon is added to a hydrocarbon mineral oil and the mixture is thoroughlyfreed from moisture by the action 01 dehydrating agents, the film strength is no more than that of the oil alone. Exposure of the mixture to the atmosphere, so that it may adsorb a slight amount of moisture, will then cause an increase in the film strength. Since the presence of a large amount of moisture, and especially of free water, is objectionable in a lubricant, besides being ahighly variable factor in normal service, it is advisable to supply an oil-soluble substitute iorit in the form of an organic oxygen compound. Even a small amount, say 0.1% or less of such a compound in combination with a chlorinated hydrocarbon (or-other oxygen-free organic halogen compound) acts to increase the efiectiveness of the latter in raising the film strength of a mineral oil, or to improve the lubricating properties of the chlorinated compound when used without the addition of some other lubricant. The organic oxygen compound probably acts in the same way as water in making possible the formation of HCl as an intermediate step by some such reaction as:

(Nata-Since atomic hydrogen is always available in one or both of the organic radicles, R and R, it need not be attached to the oxygen atom in the form of hydroxyl, as in this example.)

In the case of organic oxygen compounds which are very strongly adsorbed by metal surfaces, (e. g., fatty acids and derivatives of them) if too much is added, the chlorine compound may be prevented from functioning to increase the fllm.,.strength, probably by being displaced from such surfaces. It is, therefore, advisable to determine the amount of the oxygen compound used which will have the optimum effect.

By combining in a single molecule the halogen and the oxygen atoms, still further improvement is eiiected in two ways: (1) the oxygen is always available at the exact point where required; and (2) the molecule is more strongly adsorbed by metal surfaces than similar halogen compounds which do not contain oxygen. The latter circumstance enhances the effect of small amounts of such compounds, because it is equivalent to an increase in concentration of the compound at the bearing surfaces.

Diphenyl ether is an example of a compound which may be directly halogenated, or specifically chlorinated, to form a preferred type of product. The chlorination may be carried out 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 temperatm'e at 150 C. or higher. A product containing up to 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 octachlordisphenyl ethers. 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 use,

of mineral lubricating oil when added in relatively small proportions.

The chlorinated diphenyl ether, prepared as described above may be further refined by vacuum distillation. (e. g., that boiling at 370 to 390 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 crankshaft and connecting rod bearings.

It is especially valuable for use in such engines running at high speeds and under high loads,

as to contain a substantial proportion of addition products (e. g., a mixture containing about 40% 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 The higher boiling fractions an alkali. This is conveniently done by heating A with crushed quick-lime to a temperature near the maximum temperature to be encountered by the material when. in use. For example, ior use as an addition to mineral oil to be used as a lubricant for slow-speed bearings, gears, etc. I

where very high unit pressures are encountered but the maximum temperature is low; the chlorinated diphenyl oxide containing chlorine addition products is advantageously treated with alkali at a temperature not to exceed, say, 50 C.

For use in a lubricant for high speed gears, op-

crating under high loads, the alkali treatment should be done at a higher temperature, say C. The higher the proportion of addition products in the material, and the lower the temperature of alkali treatment, the more eflective 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.

The same principles apply to the halogenatlon of other analogous compounds, e. g., di-aryl ethers (specifically dixenyl ether, dinaphthyl ether, etc.) and aryl alkyl ethers, and to other aryl compounds, both oxygen-containing, and otherwise, e. g., naphthalene, anthracene, diphenyl; and their homologs, such as methyl and ethyl naphthalene, dibenzyl, ditolyl, etc.

When it is necessary or desirable, to use any halogenated material which contains an appreciable proportion of halogen in the form of unstable or easily hydrolized compounds, the corrosive effect 01' such unstable compounds oil'ers a 1 serious objection. To overcome this corrosive ef- Iect, and actually improve the lubricating quality of the material, the same'treatment as described above for the improvement of the chlorinated diphenyl ether containingaddition products may be.

. proved product for certain uses is to use hydrosulphides, sulphides or polysulphides, etc. instead of oxides, hydroxides, carbonates, etc. In this case, the easily hydrolized halogen is replaced with sulphur or a sulphur-bearing radicle such as mercaptan.

Thesemethods of treatment are particularly valuable for the preparation of improved lubricants from chlorinated complex materials, such as petroleum oils and products derived from them, animal and vegetable oils or any other commercial complex organic material which may be chlorinated.

Halogen bearing derivatives of certain oi. the compounds referred to above cannot easily be prepared by direct halogenation, and are preferably obtained in other ways. For example, trichlor-triphenyl-phosphate may be obtained by the reaction of phosphorus oxychloride with chlorphenol. Similar phosphates may be prepared in the same way from other chlorination products oi phenol, cresols, xylenols, "tar acids, naphthols etc. From the same and similar chlorination products, derivatives of other acids may also be obtained. For example, those of the fatty acids may be prepared by reaction of the chlorinated phenol, or similar material, with the acid chloride, acid anhydride, or with the acid itself. Chlor phenol, or chlorphenyl phenol, for example,

' when heated with stearic acid will react to form chlorphenyl stearate, or chlorphenylphenyl'stearate, respectively. Since it is difllcult to carry the reaction with fatty acids to completion, a mixture of 50 to 60% of the reaction product to- Bother with the unreacted materials is conveniently prepared and is suitable for certain uses without further purification.

The presence of oxygen in the halogenated compound, if in relatively high proportion, has a tendency to lower the solubility of the product in mineral oil. This tendency may be overcome or oil'set, in four ways: (1) by hydrogenation; partial or complete, of the ring structure; (2) by the addition of alkyl radicles to the molecules containing the oxygen; (3) by complexity or molecular heterogeneity of the material used: and (4) by the addition 01' a liquid which will act as a mutual solvent, 1. e., a liquid in which the solid material is soluble and which iS completely miscible with mineral oil, for example,

alkyl derivatives of naphthalene.

The effect of hydrogenation is illustrated by the relative solubilities in mineral oils of phenol and cyclohexanol, and of the corresponding chlorinated compounds. The eiiect oi the addition of alkyl radicles is quite similar; cresol and the chlorcresols, for example, being more soluble than phenol and the corresponding chlor-phenols.

There areadditlonal advantages in having a complex mixture of more or less related compounds, because the resulting product, besides being more soluble in mineral oil, will be more easily handled andot a more suitable character for use as a lubricant by itself. This advantage is due to the fact that such mixtures have lower melting points and are usually relatively viscous liquids as compared with the pure components of the mixture. The complexity of the mixture may result from the multiplicity of compounds produced by chlorination of a single compound (e. g., as in the case of diphenyl ether, dixenyl ether, etc.) or may be still further enhanced by the use, as raw materials, of commercial products which are themselves of a complex nature,v such as cresol, "tar acids, naphthenic acids, etc.

While it is preferable to have both oxygen and a halogen present in the same molecule, the results effected by the use of a halogen-bearing organic ring compound which does not contain oxygen may be improved by the addition of an organic oxygen compound. Such organic oxygen compounds may be any of the organic ring compounds listed above and in addition, any similar organic oxygen compounds which do not contain ring structures, e. g., alkyl, allyl, etc., alcohols, ethers, aldehydes, ketones, acids, esters and salts. Of these compounds thecarboxylic acids and the esters and salts oi such acids are preferred, e. g., fatty oils, vegetable oils, oleic acid, stearic acid, amyl acetate, butyl stearate, dibutyl phthalate, methyl salicylate, naphthenic acid, butyl naphthenate; sodium, calcium and aluminum stearates and oleatesj sodium, calcium and lead naphthenates.

The above enumerated, additions to lubricating oils for the purpose of increasing the lubricating properties thereof may, as previously indicated, beadded to a pure hydrocarbon oil in order to improve its lubricating properties. Additionally improved results may be secured by the employment of these additions with an oil containing sulphur in some form.

The eil'ect of sulphur and of sulphur compounds in increasing film strength is enormously enhanced by the presence of halogenand oxygen-containing organic compounds, especially it the relative proportions of such sulphur and halogen compounds are within certain ranges. Sulphur compounds which have a negligible eifect in increasing fllm strength by themselves are very eflective when used in combination with the proper proportion oi halogenand oxygen-bearing organic compounds. 0rganic sulphides, disulphides, polysulphides, mercaptans, mercaptoles, thio-acids, dithioacids, sulphones, sulphoxides, sulphonlc acids, sulphinic acids, sulphone amides, sulphone chlorides, thio-amides, thio-anilides, etc., (which may or may not contain a ring structure) are examples of sulphur compounds which act in this way. The table below shows the results obtained when solutions in mineral oil of such compounds, alone and with chlorinated diphenyl ether, were tested on an Almen lubricant testing machine.

The chlorinated diphenyl ether contained a to- 'This material was an impure product containing about 10 per cent total sulphur and about 3 chlorine, the latter in non-hydrolizable mm. It was prepared by chlorinating boilin xylene until the boiling point reached 200 C. and allow ng the chlorinated xylene to react with sodium sulphide in alcoholic solution. The product separated as a heavier oily layer and was: treated with calcium oxide at 100 C.

Further improved results are obtained by the presence of a halogen in the compound containing the sulphur. For example, the sulphides, disuiphides and polysulphides, of chlor-phenyl, chlor-benzyl, chlor-cresyl, chlor-xylyl, etc. give improved results over the corresponding chlorine-free compounds. Still further improvement results from the introduction of oxygen into the same molecule with the sulphur, or with sulphur and chlorine. For example (1) dibenzoyl dimethyl disulphide is more effective than the dibenzyl compound and the chlor-dibenzoyl compound still more effective, and (2) mercapto acids, such as mercapto stearic, are more effective than mercaptans, and chlor-phenyl mercapto stearate is still more effective.

Instead of sulphur compounds of the type described above, certain sulphurized compounds containing sulphur in more active or loosely combined form may be used. Examples of such. materials are the products obtained by heating sulphur with certain mineral oils, or other petroleum derivatives, or with fixed oils (1. e., animal or vegetable oils), or sulphurized terpene (U. S. Patent No. 1,926,687) and other similar compounds. These materials are more or less effective when added to mineral oils by themselves, in increasing the film strength; but their eifectiveness is greatly increased by the addition, with them, of a halogen and oxygen bearing organic ring compound. An example is shown in the following data obtained on an Almen lubricant testing machine. The sulphurized cottonseed oil contained about 9 /2%. of sulphur. As above, the results are stated in terms of additional pounds of weight applied to the loading arm of the machine required to cause breakdown as compared H with the oil alone.

Percent 0! Percent of Increase in sulphurized chlorinated breakdown cottonseed oil diphenyl other load r cent total,

In order to protect bearings, gears, etc. from very severe overloads, it is sometimes advisable to use a halogen-containing compound which is so unstable as to be appreciably corrosive under pounds, such as (1) organic bases, aromatic and alkyl amines, triethanolamine, quinoline, etc., (2) organic phosphates, e. g., tri-butyi phosphate, tri-phenyl phosphate, tri-cresyl phosphate, etc. Also certain of the halogen and sulphur compounds referred to above have similar corrosioninhibiting eiiects, notably, (1) the phosphates of chlorinated ring compounds, e. g., tri-chlorphenyl phosphate, (2) mercaptens and chlor-mercaptans.

It has been found that suitable oil base containing from 0.10% to 2.50% of sulphur in free or combined form is best suited for use in a composition according to the present invention. These percentagesare not to be construed, however, as limitations but merely as an indication of the range of sulphur in the form defined for optimum results.

Since generally the addition of certain of the halogen-bearing compounds of the class including the above enumerated reduce the viscosity of produce a decided increase in the amount oi friction developed.

Optimum results are, therefore, obtained by using minimum quantities of those halogenated compounds which tend to reduce the viscosity of the oil base so that their beneficial effect in the region of "thin-film lubrication will not be overshadowed by their detrimental eifect in the region of "thick-film lubrication.

Our invention contemplates incorporating with a suitable oil base a total of less than 20% of at least one halogenated oxygen-containing organic ring compound of those enumerated above. The above limit applied to the use of halogenated oxygen-containing organic ring compounds with a suitable oil base for the purpose of producing a lubricating composition adapted for ordinary use. It is to be understood, however, and, as pointed out elsewhere herein, that certain of these compounds may be, for certain purposes and for certain types of use, employed in a substantially pure state and as such, function in a very desirable manner as the only lubricant employed.

The optimum amount of the halogenated compound to be employed will depend largelyupon the halogen content of the particular compound, its physical characteristics and especially its effect on the viscosity of the oil to which it is added. The particular. use for which the lubricant is intended is also a governing factor in determining the amount of the compound to be added.

For the purpose of lubricating and reducing the friction between the relatively movable parts of an internal combustion engine such as crankwell as piston rings and valves, a composition according to our invention comprises a large proportion of a suitable oil base such as mineral oil and concentrations of from one-tenth to two per cent. of halogenated compounds of the above class containing from 50% to 25% of chlorine. If the valve structure of the engine is to be lubricated separately from the remainder of the mechanism or by means acting in an auxiliary fashion,

the composition for such purposes will preferably contain a. larger amount of such halogenated compounds, i. e., from 1 to 10%.

The limit of the amount of the halogenated compounds which may be added to an oily base and which will produce improved results largely depends, as above indicated, upon the reduction in viscosity of the composition caused by the addition of such compounds. :Certain of the more viscous compounds, for example, chlorinated diphenyl ether containing about 50% chlorine, may be added in amounts exceeding 20% without causing too great a reduction of viscosity. For ordinary use the lubricating compositions embodying certain of the named addition agents may contain such agents up to 20% of the total composition.

When the halogenated compounds of the closed ring type, in contradistinction to the open chain type, are used, certain advantages are obtained which may be briefly explained as follows:

In case of oil in actual use in machinery of any kind and particularly in the crank case of in ternal combustion engines, moisture is always present to some extent and due to condensation. may even accumulate to form a separate layer. There is always sufficient water present, therefore, for hydrolysis to take place. particularly when the addition of a chlorinated compound is made to the extent of only a few per cent.

Experiments have shown that when compounds which readily hydrolize, such as certain chlorinated open chain compounds, are added to the oily base, hydrolysis will take place to such an extent that the metal parts of any machine being lubricated will be seriously attacked and corroded by the acid generated. On the other hand, the addition of chlorinated carbon ring compounds of the above enumerated class does not cause corrosion,

The composition comprising our invention has certain advantages when used as a lubricant, of which the following may be mentioned- First: By the use of this composition it is possible to extend the pressure range between the bearing surfaces because of the reduced tendency for bearing surfaces so lubricated to become scored or to seize at higher pressures than are allowable with ordinary lubricants.

Second: The friction between the bearing surfaces is reduced. especially in the higher pressure range, below that obtained with ordinary lubricants.

From the above description it will be noted that our invention comprises the combined use in a lubricating composition of oxygen and a halogen such as chlorine. It is also to be understood that while oxygen-bearing halogenated organic ring compounds have been specifically referred to in this description as the combined source of the oxygen and chlorine, nevertheless, these two elements may be present in available form in separate compounds and preferably in separate organic compounds. As above pointed out, the organic ring compounds are preferred over the open chain compounds for the reason that the chlorine is sufficiently stable in the ring compounds so that in the presence of water there will be no appreciable amount of hydrolysis which would result in corrosion of the metal parts with which the composition comes in contact. In the form of the ring compounds the chlorine is su-fflciently closely combined so that it will become available to chemically react with the bearing surfaces to produce the desired results only under the conditions imposed by the relative movement between such surfaces. In certain of the ring compounds, however, the chlorine is so closely attached that it is not made sufficiently available for the desired results even under the conditions imposed by the relative movement between thebearings. The additional presence of oxygen, however, cures this difficulty and it is this reason, among others, which may explain the unusual and unexpected results secured by the combined use in the composition of the oxygen and chlorme.

With regard to the use of sulphur-bearing oil in combination with halogenated compounds, it should be noted that for sufficiently desirable results, the major proportion of the ultimate composition need not consist entirely of sulphurtreated-oil, but a suitable oil base such as mineral oil may have added thereto minor quantities or proportions of either a sulphur-treated oil or a sulphur compound, and a halogenated compound.

In the appended claims where sulphur is included in the composition, it is to be understood that such sulphur is in solution or in a stable form of colloidal suspension either in uncombined form or in the form of a sulphur compound.

This application is a division of application Ser. No. 737,070, filed July 26. 1934, and a continuation-in-part of co-pending applications Ser. Nos. 755,988, filed December 4, 1934, and 649,734. filed December 31, 1932.

Other 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 employed.

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

1. A lubricating composition comprising a major proportion of mineral oil and minor proportions of both a halogenated organic compound and sulphurized mineral oil.

2. A lubricating composition which includes as a principal lubricating constituent the combination of a separate chlorinated organic compound and sulphurized mineral oil.

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