US2452693A - Mineral oil compositions resistant to foaming - Google Patents

Description

Patented Nov. 2, 194a MINERAL on.

COMPOSITIONS RESISTANT TO FOAMIN G Herschel G. Smith, Wallingford, and Troy L. Cantrell, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application October 4, 1946, Serial No. 701,072

This invention relates to improvedmineral oil compositions resistant to foaming.

In lubricating machinery and other devices with oils, in handling oils as by pumping, in handling oil under reduced pressures and in transmitting power with an oil medium, conditions are often such that the oil is subjected to violent agitation in the presence of air or other gases, thus-tending to produce foam or froth. In most cases foaming or frothing is quite objectionable. For example, in the lubrication of gears the foaming produced by the churning action of the gears on the lubricant gives rise to excessive leakage, improper lubricatiomand loss of lubricant past retainer rings, etc. Gears such as those used in transmission and differential gear assemblies often operate at very high speeds, as well as under hightooth pressures, and therefore they require a I very good lubricant to prevent or retard excessive wear due to surface-to-surface contact.

The lubricants employed usually are viscousoils, often containing a so-called extreme pressure agent to assist in maintaining an 011 film between the teeth. If the lubricant contains air dispersed through it, it' lacks proper'fllm forming properties. In reduction gears, particularly herringbone gears oil aerofoam is undesirable as it tends to produce pitting or corrosion at the point of maximum pressure. Moreover, foaming oil is usually much less effective in conducting violent agitation. The more viscous the oil, the

greater the amount of foam, and the longer it persists after agitation is stopped.

In pumping oils with rotary gears, displacement, or other type pumps, foam or gas pockets often interfere with the pumping of the oil, causing a reduction in the stream of oil flow. This condition may be caused by either the vacuum on the intake or by the entrainment of 'gas due to violent agitation. In placing oil under vacuum, it sometimes is found that the foaming characteristic of the oil is such as to cause loss of oil entrained in the gas removed. This loss of oil is objectionable. For example, as'an airplane climbs to high altitudes, the temperature 8 Claims. (Cl. 252-325) and pressure of the oil in the sump and oil lines may be decreased, conditions which promote foaming tendencies which are highly undesirable.

It is an object of our invention to provide mineral oil compositions resistant to foaming.

It is a further object of our invention to provide a mineral oil composition having a decreased tendency to foam or froth under severe conditions.

In our copending application Serial No. 582,402, filed March 12, 1945, now U. S. Patent No, 2,411,671, there is disclosed and claimed mineral oil compositions containing a class of compounds which function in an excellent manner to reduce the foaming tendency of mineral oils. These wherein R represents an alkyl group containing 1 to 18 carbon atoms, Y is a substituent of the class consisting of monovalent metals and alkyl groups, X represents a substituent of the class consisting of metals and an organic ammonium group derived from the class consisting of heterocyclie nitrogen bases and dialkylarylamines, m is a number corresponding to the valence of X, and n' is from 2 to 6. Representative of this class of compounds are potassium trioctyl ethylene diphosphate, dimethylaniline trioctyl ethylene diphosphate, potassium dimethylaniline dioctyl ethylene diphosphate and disodium dioctyl isobutylene diphosphate. As shown in our copending application, these compounds are prepared by reactingan alkylene glycol having from 2 to 6 carbon atoms and a saturated aliphatic monohydric alcohol having from 1 to 18 carbon atoms with phosphorus oxy-chloride or phosphorus pentoxide, and neutralizing the residual acidity with a base to yield a metal or organic ammonium salt of the alkyl alkylene diphosphate. As may be seen from the examples of our copending application, generally, the mol ratio of the alkylene glycol to the phosphorus compound is 1:2 in the case of phosphorus oxychloride and 1:1 in the case of phosphorus pentoxide. In other words, the molar equivalent of the phosphorus compound on the basis of available phosphorus yields a ratio of mols of alkylene glycol to molar equivalents of phosphorus compound of 1:2.

We have now discovered another class of compounds which are excellent inhibitors in mineral oil compositions for reducing the foaming .tendency of mineral oils. In accordance therewith, the objects of our invention are accomplished by providing a mineral oil composition comprising a mineral oil and a minor amount, at least suflicient to reduce the foaming tendency of the mineral oil, of a salt of (1) a salt-forming constituent selected from the class consisting of metals and an organic ammonium group derived from the class consisting of heterocyclic nitrogen bases and N-dialkylarylamines and (2) the viscous liquid reaction product of 1 mol of a glycol having from 2 to 6 carbon atoms, 1 molecular equivalent of a phosphorus compound selected from the class consisting of phosphorus oxychloride and phosphorus pentoxide and 1 mol of a saturated aliphatic monohydric alcohol having from 1 to 18 carbon atoms.

More particularly, we have found that when the number of mols of the glycol and the number of molar equivalents of the phosphorus compound are in the ratio of 1:1, the alkylene diphosphates described in our copending application are not obtained, but there is obtained instead a viscous liquid material of unknown constitution, which we believe to be polymeric in nature. By the term molar equivalent" or "molecular equivalent as used herein and in the appended claims, we mean the number of equivalents of phosphorus compound (based on the available phosphorus) which .combine with the glycol in accordance with our invention. Thus, both phosphorus pentoxide and phosphorus oxychloride have molar equivalents of one, even though phosphorus pentoxide contains two atoms of phosphorus. In other words, when phosphorus oxychloride is reacted with the glycol, one mol of each compound is used; whereas when phosphorus pentoxide is reacted with the glycol. there being two atoms of phosphorus in the phosphorus compound, one mol of glycol will be used for each half mol of phosphorus pentoxide.

In producing our new class of compounds, any of the alkylene glycols containing from 2 to 6 carbon atoms, as shown in our above-identified co-' pending application may be employed. Thus, we may use ethylene glycol, the propylene glycols, the butylene glycols, amylene glycol and hexylene glycol or mixtures thereof. Furthermore, we may also use in lieu of, or in admixture with, the alkylene glycols the polyglycols containing from 2 to 6 carbon atoms, such as diethylene glycol, triethylene glycol and the like. When mixtures of the various glycols are employed, the total amount of glycols present equals one mol for each molar equivalent of phosphorus compound to be reacted. As used herein and in the appended claims, the term a glycol" is intended to cover mixtures of the various glycols as well as the individual glycols themselves.

The saturated aliphatic monohydric alcohol employed contains from 1 to 18 carbon atoms.

Various alcohols falling within this class, such as methyl, ethyl, propyl, butyl, 2-ethyl-hexyl, noctyl, dodecyl, cetyl, octadecyl, and the like are suitable. Particularly good results are obtained with n-octyl alcohol. As previously shown, the alcohol is employed in the proportion of 1 mol for each mol of a glycol and each molar equivalent of a phosphorus compound.

In the preparation of our new compounds, a glycol and a saturated aliphatic monohydric alcohol are mixed together in equimolar proportions and a molar equivalent of the phosphorus compound is added in successive portions, with stirring,.at a suitably elevated temperature, say about 150 F. After all of the phosphorus compound has been added, the temperature of the mixture is increased to between about 250 F. and 300 F. and maintained at that point until a homogeneous viscous liquid mass is obtained. No fixed limits as to the time of reaction need be set forth other than to'state that the reaction should proceed to the point where a substantial increasein viscosity is obtained, but not to such an extent that the reaction mass solidifies upon cooling. Salts of the reaction products obtained within these limits in accordance with our invention are excellent foam inhibiting agents. After the reaction between the glycol, alcohol and phosphorus compound has proceeded to the desired point, the residual acidity of the mixture isneutralized by the addition of a salt-forming compound selected from the class consisting of metal bases and organic ammonium bases selected from the class consisting of heterocyclic nitrogen bases and N-dialkylarylamines. suitable metal bases are the alkali and alkaline earth metal hydroxides. Suitable heterocyclic nitrogen-bases comprise pyridine, nicotine, furazan and the like. We prefer to form the foam inhibiting salts with the N-dialkylarylamines, such as dimethylaniline, diethylaniline, etc.

The salts so obtained may then be diluted with inhibiting agent in mineral oil, which may be diluted to the concentrations desired for use under service conditions. Concentrates'of the salts need not necessarily be prepared, in which case the foam inhibiting agent may be dissolved directly in the mineral oil in the concentration desired for use. Our mineral oil compositions comprise a major amount of a mineral oil and a minor amount of our new foam inhibiting salt at least sufficient to reduce the foaming tendency of the mineral oil. Generally, a proportion of the foam inhibitor varying from 0.01 to 1.0 per cent by weight on the mineral oil is sufllcient to reduce the foaming tendency of the mineral oil.

While we do not desire to be limited by any theory as to the reaction which takes place between the glycol, phosphorus compound and the saturated aliphatic monohydric alcohol in the molar proportions stated. it is our present belief that apolymeric compound is formed. Evidence for this exists in the facts that (l) the glycol and the phosphorus compound are each polyfunctional, and (2) during the reaction there is a progressive increase in the viscosity of the reaction mass.

The following example is typical of the preparation of our new foam inhibiting compounds. As

may be seen from the example, the diethylene glycol and the ethylene glycol are employed in substantially equimolar amounts, and the mol ratio of glycols to octyl alcohol to phosphorus oxychloride is 1:1:1.

To a suitable vessel 160 lbs. of diethylene glycol, lbs. of ethylene glycol and 390* lbs. of octyl alcohol were added and mixed thoroughly and the temperature brought to 100 F. To this mixture 459 lbs. of phosphorus oxychloride were added over a period of four hours, during which time the temperature was maintained between F. and 160 F. Thereafter, the temperature of the mixture was increased to 275 F. and maintained at that point until the mass had substantially increased in viscosity. The temperature was then decreased to F., 5.0 per cent water added to Gravity, A. P. I 26.3 Viscosity, SUV:

210 .F 119.9 Flash, C: F. -4-.. 535' Fire, 00: "F 610 Pour, F. 0 Color; NPA 5.5 Carbon residue, per cent 0.54 Neutralization No. 0.05

The above-described lubricatingoil and the same oil with the above-described addition of 0.04 per cent dimethylaniline salt were each subjected to the Gulf No. 1 foam test, the details of which are fully described in our U. 8. Patent No. 2,397,-

I 3'17, March 26, 1946, with the following results:

Base Inhibited oil oil Volume of Oil and Foam Batioof vol not 3 l0 4 4.3 I,

The outstanding superiority of our new foam-inhibiting compositions is thusclearly evidenced.

Our foam inhibitors are eife'ctivein many types of oils, both uncompounded and compounded with other improvement agents. Although compounded oils containing our foam inhibitors are particu- 8 What we claim is:

1. A mineral oil composition resistant to foaming comprising a major amount of a mineral oil larly useful for applications where resistance to foaming'is an important consideration, the compounds described herein may impart one or more other desirable properties to mineral lubricating oil compositions. For example. the compounds described hereinabove inhibit the corrosion of alloy bearings and at the same time reduce the amount of wear produced as compared with a straight uncompounded mineral oil. Moreover, these compounds have mild detergent properties which are advantageous for certain types of lubrication. In general, the compounded mi'neral oils containing the foam inhibiting agents disclosed have better anti-foam, anti-oxidant, oiliness, pressure carrying and anti-ring sticking properties than-the sametype of imcompounded oils.

and an amount at least suflicient to reduce the.

foaming tendency of said 011 of a salt of (1) a salt-forming constituent selected from the class consisting of metals and an organic ammonium group derived from the class consisting of heterocyclic nitrogen bases and N-dialkarylamines and (2) the viscous liquid reaction product of heating at a temperature not exceeding 300 F. 1 mol of a glycol having from 2 to 6 carbon atoms, 1 molar equivalent of a phosphorus compound selected from the class consisting of phosphorus oxychloride and phosphorus pentoxide and 1 mol of a saturated aliphatic monohydric alcohol having from 1 to 18 carbon atoms.

2. The composition of claim 1 wherein the proportion of said salt is between 0.01 and 1.0 per cent by weight on the mineral oil.

3. The composition of claim 1 wherein the glycol is a mixture of a polyglycol and an alkylene glycol, each of which contains from 2 to 6 carbon atoms.

4. A mineral oil composition resistant to foaming comprising a major amount of a mineral oil and an amount at least sufiicient to reduce the foaming tendency of said oil of a salt of an N-dlalkylarylamine and the viscous liquid reaction product of heating at a temperature not exceeding 300 F. 1 mol of a glycol having from 2 to 6 carbon atoms, 1 molar equivalent of a phosphorus compound selected from the class consisting of phosphorus oxychloride and phosphorus pentoxide and 1 mol of a saturated aliphatic 'monohydric alcohol having from 1 to 18 carbon atoms.

5. A mineral oil composition resistant to foam- I ing comprising a major amount of a mineral oil and an amount at least sufficient to reduce the foaming tendency of said oil ofthe salt of dimethylaniline and the viscous liquid reaction product of heating at a temperature not exceeding 300 F. 1 mol of an equimolar mixture of diethylene glycol and ethylene glycol, 1 mol of phosphorus 'oxychloride and 1 mol of octyl alcohol.

6. The composition of claim 5 wherein the proportion of said salts isbetween 0.01 and 1.0 per cent by weight on the mineral oil.

' HERSCHEI. G. SMITH. TROY L. CANTRELL.

Romances crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,411,871 Smith Nov. 26, 1946