US3033788A

US3033788A - Foam inhibited lubricating oil composition

Info

Publication number: US3033788A
Application number: US722391A
Authority: US
Inventors: Charles E Trautman
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1958-03-19
Filing date: 1958-03-19
Publication date: 1962-05-08
Anticipated expiration: 1979-05-08

Description

products of combustionyand the like.

United States atent if fitice 3,033,788 Patented May 8, 1962 I 3,033,788 FOAM INHIBITED LUBRICATlNG OIL COMPOSITION Charles E; Trautman, Ches'wick, Pa.,=assignor to Gulf Research-=8: Development Company, Pittsburgh, Pa., a

corporation of Delaware NoDrawing. Filed'Mar. 19,1958,jSel'.' No. 722,391 21 Claims. (Cl. 252-496) volume of foam or froth produced is many times that of the original oil, and even with mild agitation, substantialamounts of foam are produced in many oil compositions. In preparing and using such oils and oil. compositions commercially, they are subjected to agitation under a wide range cof conditions i and frequently undesirable amounts "of; foam or.- froth are produced.

Various meansof combating such foaming of oilsand oil compositions have been proposed. For instance, mechanical devices have been proposed for .destroying or-xbreaking-foam as it is formed. Usually such devices have been cumbersome or inefficient, or both, and they are not generally used commercially. Likewise, the incorporation of certain oil-soluble compounds in .the oil has been proposed as a means for preventing foaming, such ,compounds being called anti-foam agents. Unfortunately, no agent of this type has been found which is completely satisfactory in all types of oils under all conditions'of use. While some agents have effectively reduced foaming of oils maintained at room temperature, i.e., about 70 to about 80 F., the agents have been less effective in oils maintained at an elevated temperature. Some agents have effectively reduced foaming in light oils but they have been less effective in heavier oils, i.e., oils havinga viscosity above about 100- SUS at v100 F. Some of the prior so called .anti-foam agents have been found even to increase the amount of foam formed in mineral oils maintained at about 200 F., particularly in theheavier-oils, i.e., oil s having a viscosity above about 100 SUS at 100 F.

It is important to provide an oil which is markedly resistant to foaming atian elevated temperature as well as at room temperature. For example, in the lubrication of internal combustion engines such as automotive, aviation, diesel and like engines, the temperature of the oil in the crankcase during engine operation is usually within the range'of about'l00" to about 225 F. In lubricating such engines, appreciable foaming of the oil seria ously interferes with effective lubrication. By the present inventionsuch foaming is eifectively reduced. My

new anti-foam agents and=compositions are also useful in other hydrocarbon oils and oil compositions in which they are substantially insoluble whether used as a lubricaritforvnotand whether the temperature of the oil is at room-temperature or at an elevated temperature. The anti-foam agents and compositions of the present invention, however, are particularly eifective in combating foaming'in :mineral oils, especially the heavier mineral oils and lubricants at temperatures between about 100 and 225 'F.

It xis therefore among thewobjects achieved by this invention to-provide an improved method of; preventing foaming of hydocarbon oils, particularly mineral oils and oil compositions containing them, in which the normal foaming tendency .of the oil is effectively: abated or suppressed for long periods of use without deleteriously affectingthe otherproperties of the :oil.

Another object achieved by he presentinvention isthe provision of new 'andimproved anti-foam agents and compositions capable .of abating andinhibiting foaming of hydrocarbonoils and oil. compositions when dispersed 1 therein in minute amounts.

A further object achieved by the present invention is the provision of newand improvedoil compositions, particularly improved mineral oils and lubricants having marked resistance tofoaming and other advantageous properties including resistance to emulsification and containing minute amounts of .an oil-insoluble anti-foam agent finely dispersed therein.

1 have discovered that the foaming of hydrocarbon oils, particularly mineral oils and compositions containing them, can be eifectively suppressed .or prevented without substantial modification of the desirable properties of'such oils by forming in the oil a stable, fine dispersion of a small amount of an organo-silicate which has'been subjected to ionizing radiation for a time suflicient for said organo-silicate to absorb at least about 6 megareps. of radiation. I have found that an oil con- -taining such an irradiated organo-silicate as va stable,

finely dispersed phase is markedly resistant to: foaming even under the most violent conditions encountered in commercial practice. The presence of'the finely dis persed irradiated organo-silicate in the oil apparently causes the film of the oil foam to ruptu-rethereby quickly destroying the foam. .In fact, particularly when an adequate amount of irradiated organo-silicate is used, its presence so rapidly breaks the oil foam that substantially all foam is destroyed as fast as it is formed.

.1 have found-that an anti-foam agent comprising an organo-silicate can'be converted to an improvedproduct bysubjecting the organo-silicate to ionizing radiation for 'a time sufficient for said organo-silicate to absorb at least about 6 megareps. of radiation while removing heat therefrom at a rate sufiicientto maintain the bulb temperature of the organo-silicate below its decomposition or vaporization point. For example, I have found that in order to obtain a product which will materially reduce the foaming of an oil having a viscosity above. about 100 SUS atl100 F.1at temperatures up to about 225 F., the total amount of energy absorbed by the organosilicate should be at least about 6, preferably between about 6 and about 1000 megareps. If less than 6 megareps. of energy is absorbed, the irradiated product is .not substantially improved with respect to its anti-foam properties for heavy oils over the unirradiated organosilicate. While more than about 1000 megareps, of energy can be absorbed by the organo-silicate, the increment of improvement per megarep. of energy absorbed may be progressively smaller, thus rendering further irradiation economically unattractive. A megarep. (mrep.) is equal to one million reps. A 'rep. is defined as that dose of any ionizing radiation which produces energy absorption of 83.8 ergs pergram of material.

While the total amount of energy which must be absorbed by the organo-silicate to obtain-the desired product is critical, extreme care must be exercised in irradiating the organo-silicate. During irradiation the organosilicate absorbs the high energy particles which are moving at a high rate of speed. This movement is transferred upon absorption in part into heat. If irradiation is left no controlled and is perrnitted to proceed at too great a tion and degradation thereof takesplace. Desirably the organo-silicate being irradiated should be maintained during the irradiation period at a temperature as near the organo-silicate input temperature as possible so that the changes taking place in the organo-silicate are those resulting from irradiation rather than from heat.

Heat resulting from irradiation can be removed from the organo-silicate in many ways. One method comprises subjecting the organo-silicate to ionizing radiation, removing the organo-silicate from the radiation zone as the temperature thereof rises, reducing the temperature of the organo-silicate to a low temperature, such as about 70 to about 150 F., by recycling to a cooling zone, recycling said cooled organo-silicate to the radiation zone, and thereafter continuing such cycle until the organosilicate has absorbed the required amount of energy. Another method, though not preferred, because of the poor heat conductivity of an organo-silicate, resides in the use of cooling coils immersed in the organo-silicate being irradiated to remove the heat therefrom.

The time required for irradiation is extremely important from an economic point of view. When the process is carried out over an extended period of time, it becomes unattractive for commercial use. At the same time, irradiating the organo-silicate in too short a time makes it extremely difiicult to control the reaction and to maintain the organo-silicate within the desired temperature limits. I have found, for example, that an irradiation period per gram of material being irradiated of about 0.1 to about 20 seconds is sufficient to eiiect the desired result if a 2 million volt Van de Graalf accelerator producing an electron beam at an output of 500 watts is used. With other power sources, or" course, the time will be changed in accordance with the power of the source. Provided heat is removed at a rate sufiicient to prevent substantial decomposition or vaporization of the organo-silicate, any irradiation rate can be employed, though extremely high rates may involve technical difliculties.

I do not wish to limit this invention to any particular method of radiation inasmuch as the etfects of radiation on organo-silicates are essentially the same insofar as anti-foam characteristics are concerned regardless of the radiation source. Ionizing radiations can be obtained, for example, using radio isotopes, nuclear reactors or high energy particle accelerators. Examples of radio isotopes which can be used are cobalt 60 for gamma and strontium 90 for beta. Operating nuclear reactors of intermediate or full power size can be used as a source for either gamma rays or neutrons or both. Particle accelerators such as the cyclotron, bevatron, synchrotron, Van de Graafif, or X-ray machines can also be used.

In effecting irradiation of the organo-silicate, the organo-silicate can be introduced into a well in a nuclear reactor or through a tube which traverses the reactor. In some instances where it is desirable to expose the organo-silicate to fast or high energy neutrons only, and in the substantial absence of beta and gamma radiation, the irradiation can be conducted outside of the reactor using a collimated beam of fast neutrons. Such a collimated beam of fast neutrons can be obtained, for example, as described in U.S. Patent No. 2,708,656 to Enrico Fermi and Leo Szilard, by inserting a hollow shaft or tube into the central portion of the reactor. Gamma rays can be screened from the fast neutron beam by means of a sheet of bismuth metal extending across the path of the beam.

A neturon-free radiation source can be obtained directly from a homogeneous reactor by separating the radioactive fission gases, xenon and krypton, from the reactor core by conventional or modified gas-liquid separating means. A continuous supply of the radioactive fission gases could be obtained from such a reactor. The fission gases have a very high intensity of beta and gamma radiation but a very short half life. These gases possess about one percent of the total fission energy. The gases are chemically inert and therefore would not form undesired side reaction products.

While I am not certain as to the exact nature of the changes which take place when an organo-silicate is subjected to ionizing radiation, it is possible that some cross linking occurs. However, I have noted no significant change in viscosity of a tetra alkyl ortho silicate when irradiated to dosages of 6 to 50 megareps. of radiation. The viscosity and acid values of unirradiated and irradiated tetra(diisobutyl carbinyl)silicate for example, are as follows:

VISCOSITY F 210 F. Neut. Value Dosage Mreps. ASTM (D-974) CS SUS CS SUS It will be noted that the viscosity and acid values of tetra(diisobutyl carbinyl)silicate were not significantly changed by irradiation.

In the practice of this invention, various irradiated oilinsoluble liquid organo-silicates having a surface tension lower than that of the oil and capable of being stably and finely dispersed in the oil may be employed as antifoam agents.

The organo-silicates which are irradiated for use according to this invention are composed of one or more silicon atoms, each silicon atom having attached to it at least one (OR) radical.

When more than one silicon atom is present, the silicon atoms are linked together through an oxygen atom. Typical organo-silicates which are suitable for the purpose of the invention are the irradiated liquid alkyl ortho silicates, aryl ortho silicates, aralkyl ortho silicates, aralkyl ortho silicates, alkaryl ortho silicates and heterocyclic ortho silicates, including their irradiated condensation or polymerization products.

The organo-silicates when polymerized may be straight chain products or they may be products of cross polymerization or a mixture of straight chain and cross linked polymers. Thus, the organo-silicates useful for the purpose of my invention may be represented by the formulae (I) R ()R R0- Si0 -SiOR o R OR and (II) (I) R 0 R (I) R RO sr-o si-o-st-oR OR OR (I) R (I) R RO- Si-O -SiO-SIOR OR a OR OR in which the several Rs represent the same or different alkyl, aryl, aralkyl, alkaryl or heterocyclic group and n is a number from 0 to 100 or higher depending upon the number of organo-silicate residues in the complex molecule. It will be understood that the formula showing cross polymerization is merely illustrative of cross polymerization products suitable for the purpose of my in vention and such products may take other forms in which two or more cross linkings between polymers are estabis zero or more.

lished. Such compounds may take a form in which they resemble cyclic compounds for example:

in which the several Rs may be similar or dissimilar alkyl, aryl, aralkyl, alkaryl or heterocyclic groups.

The molecular weight and other properties of the organo-silicate vary withthe particular organic radicals The organo-silicatesrepresented by Formulae I and II above wherein R is an alkyl group form a preferred class of compounds in that these compounds are generally more receptive to ionizing radiation than the compounds containing aryl or heterocyclic groups. Of the alkyl substituted compounds, it is preferred to employ those wherein the alkyl radical contains from 1 to 16 carbon atoms and n is a number from 0 to 100. While compounds containing higher alkyl groups can be utilized, if they are liquids insoluble in mineral oils, such compounds may be less effective. Regardless of whether the organo-silicate is a monomer, dimer, trimer or higher polymerized product, the organo-silicate preferably contains a minimum total of carbon atoms. Thus, in Formula I above when R is a methyl radical, n is preferably at least 3.

When R in Formula I is an ethyl radical, n is preferably at least 1. When R in Formula I is a propyl radical, n In Formula II, when R is a methyl radical, n is zero or more. Generally preferred for the present purpose are the relatively high molecular weight irradiated monomers where n is zero and R is an alkyl group containing from 8 to 16 carbon atoms. Thus, a preferred class of compounds include tetra octyl ortho silicate, tetra nonyl ortho silicate, tetra decyl ortho silicate, tetra undecyl ortho silicate, tetra dodecyl ortho silicate, tetra tridecyl ortho silicate, tetra tetradecyl ortho silicate, tetra pentadecyl ortho silicate, and tetra hexadecyl ortho silicate. I

The lower molecular weight compounds, such as when R is a methyl or ethyl radical, are polymerized relatively easily and n in such a case may range from 3 to 100 or more. The higher molecular weight compounds, such as when R is a cety-l radical, are more difficult to condense or polymerize so that the resulting condensation or polymerization product may be only a dimer or trimer. Whether the silicate is only a monomer or a highly'p'olymerized product, I prefer to employ an irradiated organo silicate containing a minimum total of 10 carbon atoms. Particularly good anti-foam characteristics are obtained with an irradiated organo-silicate containing a minimum total of 32 to 40 carbon atoms and especially tetra(diisobutyl carbinyDsilicate which contains a total of 36 carbon atoms.

Many of the organo-silicates' utilized according to the present invention are available commercially and therefore their .preparation constitutes no part of the invention. Thus, commercially available organo-silicates are time suificient for them to absorb at least about 6 megareps. of radiation. The irradiated organo-silicates are then dispersed in the oil.

In the preparation of the lower molecular weight monomers, such as tetra methyl ortho silicate and tetra ethyl ortho silicate, one mol of a silicon halide such as silicon tetrachloride is reacted with four mols of the corresponding alcohol. To obtain the corresponding condensation products the tetra alkyl ortho silicates are further heated at refluxing temperature in the presence of water. In the course of preparing the monomers, four mols of hydrogen chloride are produced for every mol of tetra alkyl ortho silicate. The hydrogen chloride thus formed usually converts some of the alcohol to the ether or alkyl halide and produces water. The Water thus formed may give rise to the condensation of the intermediate alkoxychlorosilane to form condensed esters such as hexaal-koxydisiloxane, octaalkoxytrisiloxane, decaalkoxytetrasiloxane, and the like.

The higher molecular weight ortho silicates can be 'obtained by an ester exchange reaction with a lower mole'c-ular weight ortho silicate. Tetra octyl ortho silicate can, for example, be prepared by an ester exchange reaction wi-th tetra methyl ortho silicate or tetra ethyl ortho silicate. The ester exhange reaction can be effected, for example, by heating tetra ethyl ortho silicate with the desired alcohol or mercaptan in the presence of a catalyst such as benzene sulfonic acid or sodium ethoxide. The ester exchange reaction is conducted at a temperature of about 100 to 200 C. for a time sufficient to drive off the methyl or ethyl alcohol. Thus, in preparing the tetra C to C alkyl ortho silicates, an ester exchange reaction is effected between tetra ethyl ortho silicate and an alcohol selected from the group'consisting of octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl and hexadecyl alcohols.

The organo-silicate condensation products may be obtained as the polymerized hydrolysis products of the esters of ortho silicic acid by controlled hydrolysis of the tetra orthosilicate esters with water. Hydrolysis and condensation or polymerization take place simultaneously with the formation of liquid products which are in general substantially insoluble in hydrocarbon oils and have surface tensions lower than the surface tensions of such oils. Normally mixtures of products in various degrees of polymerization are first obtained. These mixtures after irradiation may be used directly as anti-foam agents.

It is generally more advantageous, however, to isolate the higher liquid polymerization products from the total products. In general the effectiveness of the irradiated organo-silicates in preventing foam formation increases with increased molecular weight and boiling point. Also, the higher molecular weight organo-silica'tes are less soluble in the hydrocarbon oils. Consequently, it is advantageous to irradiate the higher boiling liquid fractions of the products. Separation of the desired fractions may be accomplished by vacuum distillation of the total reaction products.

The irradiated organo-silicates as defined hereinabove are effective foam inhibitors in very low concentration and although they are substantially insoluble in hydrocarbon oils, they are readily dispersible in such oils to form compositions containing stable, fine dispersions of the organo-silicate in hydrocarbon oils, which are substantially resistant to foam formation, without deleteriously modifying the advantageous properties of the oil. Insofar as the organo-silicate condensation products are concerned, the organo-silicate condensation products containing simple organic radicals, such as methyl, ethyl and short-chain alkyl groups are most advantageous inasmuch as they have exceedingly small solubility in most hydro carbon oils. For example, an irradiated fraction of the total reaction products obtained on hydrolysis and polymerization of tetramethyl orthosilicate and fractionation at 220 to 240 C. at 0.75 mm., which consists predominantly of a condensation product in which n is of the order of 3, is markedly etfective in concentrations as low as 0.1 percent and less. A similar irradiated fraction obtained by hydrolysis and polymerization of tetraethyl orthosilicate and fractionation of the products to recover the compounds boiling above 290 C. at 1 mm. are also effective in concentrations as low as 0.005 percent and less.

The organo-silicates as defined hereinabove are for all practical purposes substantially oil-insoluble. They are also substantially insoluble in water and aqueous solutions. On the other hand, they can be readily dispersed in hydrocarbon oils to form stable dispersions containing extremely fine particles of irradiated products. In fact, I have prepared oil compositions containing such irradiated organo-silicates dispersed therein, in which a majority of the dispersed particles range from 2.0 to 0.3 micron in diameter or less. Such fine dispersions of these irradiated silicates in oils are very stable and are markedly resistant to foaming. Some oil compositions containing from 5 to 100 parts per million of these compounds finely dispersed therein yield little or no foam when subjected to drastic foaming tests. In fact, some compositions containing as low as 0.05 part per million of a dispersed irradiated silicate show a measurable resistance to foaming. The heavier mineral oils generally require from about 0.00001 to I percent by weight to eflfectively reduce foaming. While the irradiated organo-silic-ates are for the most part insoluble in mineral oils, some of the organo-silicates may be soluble to a very slight degree. When the irradiated silicate is slightly soluble, the amount of the irradiated silicate used should be sufiiciently in excess of its solubility in the oil to give the required amount of dispersed phase necessary to prevent foaming under service conditions. For this reason, the irradiated organo-silicates which are substantially oilinsoluble are most advantageous.

The particle size of the irradiated organo-silicate dispersed in the hydrocarbon oil has a marked effect upon the resistance to foaming so imparted to the oil compositions. In general, oil compositions containing dispersions of the irradiated organo-silicate in which the particles are about 2.0 microns and less in diameter are particularly advantageous for the present purpose. Such oil compositions are very stable in storage and under service conditions, and they have a high resistance to foaming which they retain over long periods of use.

Since good resistance to foaming can be readily obtained with exceedingly small proportions of my new antifoam agents finely dispersed in the oil, the anti-foam agents of my invention do not deleteriously modify the other properties of such compositions. Accordingly, the desired foam-resisting properties can be imparted to such oils without impairing their effectiveness as lubricants or for other intended uses.

In the commercial practice of this invention, oil compositions may be produced directly in which the antifoam agent is present in the desired small amount and fine dispersion. However, in certain embodiments of the invention, oil compositions initially containing relatively coarse dispersions and relatively high concentrations of the anti-foam agent may be first prepared and the desired finely dispersed agent concentration may be produced in the oil during use by agitation thereof in the lubricating system, such as by gear pumps and other mechanisms.

Such production of the desired fine dispersions in situ in the oil during use is sometimes advantageous. Of course, the amount of anti-foam agent and the fineness of the dispersion necessary to prevent foaming in a given case vary somewhat with the particular oil and agent employed as well as the service conditions to which the oil composition is subjected.

In preparing my improved oil compositions, the anti foam agent may be incorporated in the oil or oil composition by any suitable method capable of producing a stable fine dispersion of the agent in the oil. For example, where the anti-foam agent is to be added to a heavy mineral oil, it may first be incorporated in a hydrocarbon oil lighter than the oil to be improved, or other suitable carrier, such as mineral seal oil, gasoline, naphtha, hexane and benzene, and this anti-foam composition may then be introduced into the oil to which it is desired to give anti-foam properties. After such an anti-foam composition has been formed it may be incorporated in the oil or oil composition simply by mixing and agitating the solution therewith. A fine dispersion of the anti-foam agent in the oil is thus obtained. A convenient antifoam concentrate for such use would contain 1.0 percent of active anti-foam agent. To add 0.001 percent anti foam agent to the final oil would require the addition of 0.1 percent of the anti-foam concentrate. Where it is desired to form directly a dispersion of the anti-foam agent in the oil, various commercial colloid mills may be employed to disperse finely the agent in the oil. Also, gear pumps may be employed to disperse the anti-foam agent in the oil. The use of such gear pumps is advantageous in many embodiments of this invention, particularly those wherein fine dispersions of the anti-foam agents are produced in situ in the oil. In some instances, the organo-silicate can be added to the oil and then the entire mixture subjected to ionizing radiation. Where such technique is employed, the vehicle should be one that is relatively insensitive to radiation under the conditions employed. Other methods and apparatus may also be employed in dispersing these irradiated agents in oils or oil compositions.

It is sometimes advantageous to first disperse the liquid anti-foam agent in part of the oil and then add this concentrate dispersion to the remainder of the oil. Such concentrate dispersions can be readily prepared as stable uniform compositions. For instance, a mixture of oil and anti-foam agent in the desired proportions may be continuously circulated through a gear pump until a stable concentrate containing a uniform dispersion of the agent is obtained. Thus, standardized concentrates can be prepared which can be added to lubricating compositions as needed. In such case, the desired amount of concentrate is added to the oil composition and the mixture is agitated until uniform.

Also, such concentrates are themselves valuable antifoam compositions. As they contain a preformed, dispersed, insoluble liquid phase of the desired particle size, they quickly break oil foams, as Well as suppress foaming in general. For instance, when added to oil or oil com positions which have foamed, they rapidly destroy the foam present and stop further foaming. In such cases, they can be quickly blended with oils, oil compositions and crude oil and uniformly incorporated therein before serious foaming occurs.

For such purposes, oil concentrates containing from 0.1 to 10 percent by weight and more of finely dispersed anti-foam agent are advantageous. By adding from 0.01 to 10 percent by weight of such concentrates to mineral lubricating oils, improved lubricants having marked'resistance to foaming are readily and easily obtained.

fatty oils, and high molecular weight ketones and esters;

viscosity index improvers, such as theihigh molecular and aponr point 0150 F. The'tetra(diisobutyl carbinyl)- silicate which'was subjectedto radiation hada viscosity of 78 SUS at 100 F.. and 37.5 SUS at 210 F. The

' irradiated product as shown hereinabove had no significant change in viscosity and acid value. There was also no noticeable change in color.

Table I Composition, percent by weight A B O D E F G Base 011, 27.9API-.-1169 SUS at-100 F 100 99. 95 99.95 99.05 99.- 95 99. 98 99. 9

Tetra (diisobutyl carbinyl) silicate, irradiation dosage, mreps.:

p 50. Foam TestKASTM D892-.46T), Foaming Tendency, m1. at 5 min;

At 7 I At 200 F "weight polymers of isobutylene and the polymers of "metlraerylic esters; pour point depressants, such as a condensation product of chlorinated wax and naphthalene and a condensation product of chlorinated wax and phenol followed by further condensation of this reaction product with organic acids; an anti-rust agent such as cocoamine isoa-myl octyl orfliophosphate; and corrosion and oxidation inhibitors, such as 2,6-di-tertia-ry butyl-4- methyl 'phenol,*tri-phenyl phosphite, tributylphosphite,

beta naphthol, and'phenyl beta naphthylamine.

Many of these agents tend to'promote foaming. The anti-foam product of my invention, however, can suppress the foaming caused 'by the addition ofsuch agents to an oil without deleteriously affecting the beneficial characteristics given to the oil by these additives.

irradiated to various dosages in a Van de Graaff accelerator. The bulk temperature of the tetra(diisobutyl carbinyllsilicate was maintained between about 70 and 200 F.' during irradiation. The total energy absorption is shown in connection with the'various specific examples. In preparing samples of oil for the foam test, the agent was added directly to the oil. The mixture thus formed was then blended in aWaring'Blendorfor at least five minutes.

The data summarized in Table I will illustrate the advantageous results obtained by incorporating in a mineral lubricating oil tetra(diisobutyl carbinyl)silicate which had been subjected to irradiation dosages of 6 to 50 megareps. of radiation. A comparison is also made between an oil containing no tetra (diisobutyl carbinyl)silicate and also the same oil containing irradiated and unirradiated tetradiisob'utyl earbinyD'silicate.

The mineral ilubricating oilused in preparing the compositions illustrated in Table I was a highly refined paraffinic mineral lubricating oil of SAE '50'grade having an APYgravity' ot 27.9,1aviscosity of 1169 SUS'at-100" F. and 100 SUS ED12210 F., 'a'viscosity index of 101, a flash perm OQC.) "of 570F., a firepoint '(iO.C.)"0f 625 F.

As shown by the data summarized in TableI, the addition of unirradiated tetra(diisobutyl carbinyl)si1icate decreasedthe amount of foam formedin the oil when tested at 75 F. However, when the same-oil'was maintained at 200 F., the unirradiated tetra(diisobutyl carbinyl)silicate increased the foaming tendency of the oil. The addition of tetra(diisobutyl carbinyl)silicate which was irradiatedto dosages of 6 to 50.megareps. re-

duced the foaming tendency of the oil at 75 F. and also at 200 F. The improved anti-foam characteristics of compositions of the invention, for example,- compositions C to G, is thus readily apparent.

Other specific organo-silicates which when irradiated are useful for the present purpose are tetra methyl .ortho silicate condensation products and tetra ethyl ortho silicate condensation products wherein nin Formula I shown hereinabove is 3. The condensationproducts of tetra methyl ortho silicate and tetra ethylaortho silicate can be obtained by heating the respective silicates at refluxing'temperature' for about 2m 3 hours in the presence of'the corresponding alcohols and water in such proportion as to provide about 0.8 mol of water per mol of silicate. The alcohol and uncondensed ortho silicate are then distilled off at atmospheric pressure. The condensation products are then fractionally distilled at about 1 mm. of mercury pressure. The-fractions thus obtained are then subjected to ionizing radiation for a time suflicient for the condensation product to absorb at least 6 megareps; ofradiation.

Still other specific organo-silicates include irradiated tetra propyl ortho silicate, tetra butyl orthosilicate, tetra pentyl .ortho silicate, tetra 'hexyl ortho silicate, tetra heptyl ortho silicate, tetra octyl ortho silicate, tetra nonyl ortho silicate, tetra decyl ortho silicate, tetra undecyl orthosilicate, tetra dodecyl ortho silicate, tetra tridecyl ortho silicate, tetra tetradecyl ortho silicate, tetra pentadecyl ortho silicate, tetra'hexadecyl'ortho silicate, 'tetra phenyl ortho silicate, tetra tolyl ortho silicate, tetra benzyl ortho silicate, tetra furyl ortho silicate, tetra thienyl orho silicate, tetra pyrryl ortho silicate, tetra"pyridyl ortho silicate, tetra dichloro phenyl ortho silicate, dimethyl dibutyl ortho silicate, dibutyl'dioctyl ortho silicate, dimethyl diphenyl ortho silicate, tetra decenyl' ortho silicate, tetra 'butoxyethyl ortho'silicate, and their condensation or polymerization products.

I 1 stantially the same as those of the base oil as shown by the inspection data in the following Table II.

Table II Mineral Oil+0.05% by weight 50 mrep lrradiate tra (diisobutyl carbinyl) silicate Composition Mineral Oil Gravity, API Viscosity, SUS:

at 100 F Viscosity Inde. Flash Point F- Fire Point (00), F-.- Pour Point, F Color, ASTM Union. Ash, Percent While my invention has been described above with reference to various specific examples and embodiments, it Will be understood that the invention is not limited to such illustrative examples and embodiments, and may be variously practiced within the scope of the claims hereinafter made.

I claim:

1. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dispersing in said oil a small amount, sufficient to improve said foaming tendencies, of a liquid organo-silicate which has been subjected to ionizing radiation for time sufficient for said organo-silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the organo-silicate below its decomposition temperature, said organo-silicate being selected from the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic ortho silicates containing a minimum total of 10 carbon atoms.

2. The process of claim 1 wherein the amount of organo-silicate dispersed in said oil is about 0.00001 to about 1.0 percent by weight of the oil.

3. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dispersing in said oil a small amount, sufficient to improve said foaming tendencies, of a liquid alkyl ortho silicate which has been subjected to ionizing radiation for a time sufficient for said alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the alkyl ortho silicate below its decomposition temperature, said alkyl ortho silicate containing a minimum total of 10 carbon atoms.

4. The process of claim 2 wherein the alkyl radical of said alkyl ortho silicate contains from 1 to 16 carbon atoms.

5. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dispersing in said oil a small amount, sufficient to improve said foaming tendencies, of a liquid tetra alkyl ortho silicate which has been subjected to ionizing radiation for a time suflicient for said tetra alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the tetra alkyl ortho silicate below its decomposition temperature, said tetra alkyl ortho silicate containing a minimum total of 10 carbon atoms.

6. The process of claim wherein the tetra alkyl ortho silicate is tetra(diisobutyl carbinyl)silicate.

7. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dis persing in said oil a small amount, sufiicient to improve said foaming tendencies, of a liquid ethyl ortho silicate condensation product which has been subjected to ionizing radiation for a time suflicient for said condensation product to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the condensation product below its decomposition temperature, said condensation product containing a minimum total of 10 carbon atoms.

8. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dispersing in said oil a small amount, sufiicient to improve said foaming tendencies, of a liquid methyl ortho silicate condensation product which has been subjected to ionizing radiation for a time sufficient for said con densation product to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the condensation product below its decomposition temperature, said condensation product containing a minimum total of 10 carbon atoms.

9. A process of suppressing foaming in a mineral lubricating oil having foaming tendencies comprising dispersing in said oil a small amount, sufiicient to improve said foaming tendencies, of a liquid organo-silicate which has been subjected to ionizing radiation for a time sufiicient for said organo-silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the condensation product below its decomposition temperature, the dispersion in said oil having been formed by dispersing a mixture of said organo-silicate in a hydrocarbon oil lighter than the oil in which foaming is to be suppressed, said mixture containing about 0.1 to about 10 percent by weight of said organo-silicate and said organo-silicate being selected from the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic ortho silicates containing a minimum total of 10 carbon atoms.

10. A lubricating oil composition of reduced foaming properties comprising a major. amount of a mineral lubricating oil having foaming tendencies and a small amount, sufiicient to improve said foaming tendencies, of a liquid organo-silicate which has been subjected to ionizing radiation for a time sufficient for said organo-silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the organo-silicate below its decomposition temperature and which is stably dispersed in the oil, said organo-silicate being selected from the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic ortho silicates, containing a minimum total of 10 carbon atoms.

11. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and a small amount, sufficient to improve said foaming tendencies, of a liquid alkyl ortho silicate which has been subjected to ionizing radiation for a time sufficient for said alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the alkyl ortho silicate below its decomposition temperature and which is stably dispersed in the oil, said alkyl ortho silicate containing a minimum total of 10 carbon atoms.

12. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and a small amount, sufiicient to improve said foaming tendencies, of a liquid alkyl ortho silicate which has been subjected to ionizing radiation for a time sufficient for said alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the alkyl ortho silicate below its decomposition temperature and which is stably dispersed in the oil, said alkyl ortho silicate containing a minimum total of 10 carbon atoms and the alkyl radical in said alkyl ortho silicate containing from 1 to 16 carbon atoms.

13. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and a small amount, sufiicient to improve said foaming tendencies, of a liquid tetra alkyl ortho silicate which has been subjected to ionizing radiation for a time suificient for said tetra alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the tetra alkyl ortho silicate below its decomposition temperature and which is stably dispersed in the oil, saidtetra alkyl ortho silicate containing a minimum total of 10 carbon atoms.

14. The lubricating oil composition of claim 13 wherein the tetra alkyl ortho silicate is tetra(diisobutyl carbinyl)silicate.

15. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and a small amount, sufficient to improve said foaming tendencies, of a liquid ethyl ortho silicate condensation product which has been subjected to ionizing radiation for a time sufficient for said condensation product to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the condensation product below its decomposition temperature and which is stably dispersed in the oil, said condensation product containing a minimum total of 10 carbon atoms.

16. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and a small amount, sufiicient to improve said foaming tendencies, of a liquid methyl ortho silicate condensation product which has been subjected to ionizing radiation for a time sufficient for said condensation product to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the condensation product below its decomposition temperature and which is stably dispersed in the oil, said condensation product containing a minimum total of 10 carbon atoms.

17. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and about 0.00001 to about 1.0 percent by weight sufficient to improve said foaming tendencies of a liquid organo-silicate which has been subjected to ionizing radiation for a time sufiicient for said organo-silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the organo-silicate below its decomposition temperature and which is stably dispersed in the oil, said organo-silicate being selected from the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic ortho silicates containing a minimum total of 10 carbon atoms.

18. A lubricating oil composition of reduced foaming properties comprising armajor amount of a mineral lubricating oil having foaming tendencies and about 0.00001 to about 1.0 percent by weight suflicient to improve said foaming tendencies of a liquid tetra alkyl ortho silicate which has been subjected to ionizing radiation for a time sufiicient for said tetra alkyl ortho silicate to absorb about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the tetra alkyl ortho silicate below its decomposition temperature and which is stably dispersed in the oil, said tetra alkyl ortho silicate containing a minimum total of 10 carbon atoms.

19. The lubricating oil composition of claim 18 wherein the tetra alkyl ortho silicate is tetra(diisobutyl carbinyl) silicate.

20. A composition adapted to impart foam resisting properties to a mineral lubricating oil having foaming tendencies when added thereto in an amount corresponding to about 0.01 to about 10 percent by weight, comprising a major amount of a hydrocarbon liquid containing from about 0.1 to about 10 percent by Weight of a liquid organo-silicate which has been subjected to ionizing radiation for a time sufiicient for said organo-silicate to absorb at least about 6 to about 1000 megareps. of radiation while maintaining the bulk temperature of the organo-silicate below its decomposition temperature, said organo-silicate being selected from the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic ortho silicates containing a minimum total of 10 carbon atoms.

21. A lubricating oil composition of reduced foaming properties comprising a major amount of a mineral lubricating oil having foaming tendencies and about 0.00001 to about 1.0 percent by weight, sufficient to improve said foaming tendencies, of tetra(diisobutyl carbinyl)silicate,

which has been subjected to ionizing radiation for a time suflicient to absorb about 6 to about megareps. of radiation while maintaining the bulk temperature of the tetra(diisobutyl carbinyl)silicate below its decomposition temperature.

References Cited in the file of this patent UNITED STATES PATENTS 2,375,007 Larsen et al. May 1, 1945 2,416,504 Trautman et al. Feb. 25, 1947 2,632,736 Currie Mar. 24, 1953 2,702,793 Smith Feb. 22, 1955 2,766,220 Kantor Oct. 9, 1956 2,904,481 Lawton et al. Sept. 15, 1959 OTHER REFERENCES Charlesby: Effect of Molecular Weight on the Cross- Linking of Siloxanes by High-energy Radiation, Nature, vol. 173, April 10, 1954, pp. 679,680.

UNITED STATES P ATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 O33, 788 May 8 1962 Charles E, Trautman It is hereby certified that error appears in 1: ant requiring correction and that the s corrected below.

Column 2, line 6, for "he" read the column 4 line 42, strike out "aralkyl ortho silicates,"; column 1.1 line 54, for the claim reference numeral "2" read 3 S1gned and sealed th1s 28th day of August .1962

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents

Claims

10. A LUBRICATING OIL COMPOSITION OF REDUCED FOAMING PROPERTIES COMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL HAVING FOAMING TENDENCIES AND A SMALL AMOUNT, SUFFICIENT TO IMPROVE SAID FOAMING TENDENCIES, OF A LIQUID ORGANO-SILICATE WHICH HAS BEEN SUBJECTED TO IONIZING RADIATION FOR A TIME SUFFICIENT FOR SAID ORGANO-SILICATE TO ABSORB ABOUT 6 TO ABOUT 1000 MEAGAREPS. OF RADIATION WHILE MAINTAINING THE BULK TEMPERATURE OF THE ORGANO-SILICATE BELOW ITS DECOMPOSITION TEMPERATURE AND WHICH IS STABLY DISPERSED IN THE OIL, SAID ORGANO-SILICATE BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL, ARYL, ARALKYL, ALKARYL AND HETEROCYCLIC ORTHO SILICATES, CONTAINING A MINIMUM TOTAL OF 10 CARBON ATOMS.