US3082168A - Foam inhibited emulsifiable mineral oil composition - Google Patents

Description

Patented Mar. 19, 1953 3 FGAIW ENHEBHTED Elt iULSTFiABLE MINERAL 01L This invention relates to emulsifiable mineral oil compositions, sometimes referred to as soluble oils, and to oil-in-water emulsions prepared from such compositions, and in particular to an additive material for use in such compositions and emulsions in order to inhibit foaming of the emulsion.

It is well known in the art to prepare mixtures of mineral oil and emulsifying agents which are capable of being emulsified in Water to form emulsions for use as cutting fluids, metal rolling oils, textile oils, etc. A problem that is sometimes encountered in the use of such emulsions is the formation of foams which interfere with the handling of the emulsion. It has been proposed in the prior art to add vegetable or mineral waxes to the compositions in order to inhibit such foaming. However, the foam-inhibiting additives which have been prepared previously do not provide satisfactory results in all cases. When conditions are encountered which result in a strong foaming tendency, the additives employed in the prior art are sometimes inadequate to prevent foaming, at least when they are used in the relatively small amounts which are usually desired to be used. V

The present invention provides a composition contain: ing, as foam-inhibiting additives, partially oxidized petroleum microcrystalline waxes. It has been found that these oxidized waxes provide superior foam-inhibition to that which is obtained with the unoxidized microcrystalline waxes which have been employed in the prior art.

The emulsifiable compositions and emulsions to which the foam-inhibiting additive is added contains mineral oil and emulsifying agent, and preferably contains mineral oil, carboxylic acid salts and sulfonic acid salts. The mineral oil is employed in the amount of 70 to 90 weight percent of the total composition on the anhydrous basis, and is usually a lubricating oil distillate having viscosity within the range from 50 Saybolt Universal seconds at 100 F. to 300 Saybolt Universal seconds at 100 F. The foam inhibiting additives according to the invention are particularly advantageous for use in emulsifiable mineral oil compositions which contain mineral oil having Saybolt Universal viscosity in the range from 50 to 150 Saybolt Universal seconds at 100 F. The unoxidized microcrystalline waxes on the other hand are not effective in such compositions, apparently because of an adverse effect of the relatively low viscosity mineral oil on the foaminhibiting activity of the microcrystalline wax.

The invention is generally applicable to the known soluble oils containing mineral oil and containing soaps as emulsifiers. The known soaps for this use are generally suitable here. A preferred emulsifying agent is one containing both carboxylic acid salts and sulfonic acid salts.

Such carboxylic acid salts are in one embodiment employed in the amount from 6 to 12 weight percent of the total composition on the anhydrous basis, and are usually alkali metal or aliphatic amine salts of aliphatic or cycloaliphatic carboxylic acids, which acids have 12 to 30 carbon atoms per molecule. The carboxylic acid salts are conventional components of emulsifiable mineral oil compositions, and any of the known salts can be employed. Typical carboxylic acids for the formation of such salts are the fatty acids, petroleum naphthenic acids, acids produced by liquid phase partial oxidation of aliphatic or naphthenic hydrocarbons, or of mixtures containing aliphatic and naphthenic hydrocarbons, e.g. dearomatized petroleum fractions. In preferred embodiments of the invention, the carboxylic acid salts which are employed constitute a mixture of salts of petroleum naphthenic acids and salts of acids produced by liquid phase partial oxidation of a solvent-refined mixture of lubricating oil and low-melting wax, i.e. wax having melting point below F. Such compositions are described in more detail in Patent No. 2,797,197 which issued on June 25, 1957, to Norman Thompson and Willard K. Parcells.

The sulfonic acid salts which are employed in the composition in one embodiment are also conventional components of emulsifiable mineral oil compositions. Preferably the average molecular weight of the sulfonic acids which are employed to make the salts is within the approximate range from 425 to 525. Alkali metal or aliphatic amine salts of the sulfonic acids can be employed. The sulfonic acids are generally produced by the sulfonation of a solvent-refined petroleum lubricating oil in a manner which is well known in the art.

Suitable alkali metals and amines for the sulfonic and carboxylic salts include those which are known in the art for soluble oil emulsifying agents, e.g. sodium, potassium, lithium, isopropylamine, isopropanolamine, triethanolarnine, etc. Usually the amine has 2 to 12 carbon ate-ms per molecule.

The total amount of emulsifying agent in the composition according to the invention is preferably in the range from 7.5 to 15 weight percent on the anhydrous basis.

The oxidized microcrystalline wax employed in the composition of the invention is obtained by the liquid phase partial oxidation of petroleum microcrystalline wax. Such wax usually has melting point in the approximate range from 145 to 200 F. The procedure for partially oxidizing microcrystalline wax is well known in the art and usually involves blowing air or oxygen through the molten wax at a temperature in the range from 250 to 400 F. in the presentce of a metallic catalyst, for example manganese salts of petroleum naphthenic acids. The saponification number of the oxidized microcrystalline wax which is employed is preferably at least 40 mg. of KOH per gram. The upper limit is not critical but preferably the saponification number is in the approximate range from 40 to mg. of KOH per gram, although other saponification numbers can be used in some cases.

The oxidized microcrystalline wax is present in relatively small amount in the emulsifiable composition, e.g. in the range from 0.05 to 1.0 weight percent based on the total composition on the anhydrous basis. In order to obtain the foam inhibiting properties, it is necessary that this material be obtained from a microcrystalline wax, rather than from lower melting wax. Amounts of the oxidized microcrystalline wax greater than 1.0 weight percent are avoided in order to avoid detrimental effect on the low temperature properties of the composition.

Frequently, the emulsifiable mineral oil compositions contain, in addition to the components referred to previously, a coupling agent or mutual solvent which improves the stability of the emulsifiable composition prior to emulsification or of the emulsion produced therefrom or both. Many mutual solvents are known in the prior art, and the known mutual solvents are generally suitable for use according to the invention.

The emulsifiable mineral oil composition frequently contains a small amount of water, usually in the range from 1 to 5 weight percent of the total composition prior to emulsification.

Preferably the emulsifiable mineral oil composition according to the invention contains a small amount of free alkali, e.g. in the range from 0.01 to 0.2 weight percent as sodium hydroxide. It is within the scope of the invention, however, to prepare emulsifiable compositions which are on the acid side rather than the alkaline side.

In compositions which are on the alkaline side, the carboxylic acids in the oxidized microcrystalline wax are in the salt form, whereas in soluble oils which are on the acid side at least a portion of the carboxylic acids in the oxidized microcrystalline wax are in the free acid form. In either event the oxidized microcrystalline wax is effective as a foam inhibiting additive.

In one embodiment of the invention, the oxidized microcrystalline wax is employed in conjunction with a polymer of a vinyl aromatic compound such as styrene. The compositions containing such polymers and oxidized microcrystalline Wax are disclosed in application Serial No. 694,917 filed November 7, 1957 by Samuel E. Jolly now US. Patent 2,944,039. A typical preparation of such composition involves the following procedure. A partially oxidized microcrystalline wax having saponification number of 85.7 mg. of KOH per gram and Saybolt Universal viscosity at 210 F. of 552 seconds is prepared by partial oxidation of microcrystalline wax at 250 to 270 F. with air for 203.5 hours in the presence of manganese naphthenate in amount such that the oxidation mixture contains 0.04 weight percent of manganese. 250 grams of the partially oxidized wax are heated together with 100 ml. of xylene under refluxing conditions with mechanical stirring. To the heated solution of oxidized wax in xylene, 250 grams of styrene containing 2.5 grams of ditertiarybutyl peroxide are added dropwise with stirring. The reaction mixture is refluxed for 5 hours. The stirrer and condenser are then removed and unreacted styrene and xylene are stripped off. 467.5 grams of a homogeneous product having saponification number of 43.8 mg. of KOH per gram are left as residue. This product can be employed as the mixture of oxidized wax and polymer in the composition according to the invention.

In one embodiment, the foam inhibitor is obtained by admixing preformed polymer of a vinyl aromatic compound with oxidized wax. In another embodiment, the inhibitor is obtained by polymerizing a mixture of a vinyl aromatic monomer and oxidized wax. The amount of oxidized wax in the mixture with monomer or polymer is preferably in the range from 20 to 9.0, more preferably at least 50, weight percent of the mixture. The amount of oxidized wax in the emulsifiable composition in this embodiment is preferably in the range from 0.05 to 1.0 weight percent on the anhydrous basis, and the total amount of oxidized wax and vinyl aromatic polymer is preferably in the range from 0.1 .to 1.5 weight percent on the anhydrous basis. The vinyl aromatic monomers and polymers disclosed in the Jolly application referred to above are generally suitable for use according to the present invention.

Typically, the emulsiflable compositions of the invention are emulsified by agitating with hard or soft water at a temperature in the range from 45 to 180 F. to give emulsions containing 1 to weight percent of the nonaqueous constituents. However, other proportions and procedures can be employed.

The following examples illustrate the invention:

Example 1 The following composition is prepared:

Mineral oil 84.55

The mineral oil is mainly a distillate from naphthenic base crude, which distillate has Saybolt Universal viscosity of 110 seconds at 100 F. The mineral oil also includes Mid-Continent distillate lubricating oil, of about SUS/ 100 F. viscosity, introduced with the sulfonic acid salts, the amount of the latter mineral oil being about 60% of .the amount of sulfonic acid salts.

The carboxylic acid salts in the composition are a mixture of sodium naphthenates and sodium salts of carboxylic acids produced by liquid phase partial oxidation of a Mid-Continent lubricating oil containing about 40% 0f low-melting wax, i.e. about 40% of material which is crystallizable from methyl ethyl ketone at 0 F. and which has melting point below 100 F. The waxcontaining oil has Saybolt Universal viscosity at 100 F. of about 136 seconds and conforms generally to the foots oil described in Patent No. 2,797,197, referred to previously. The partial oxidation is conducted in the manner described in that patent and results in a product having saponification number of about 75 mg. of KOH per gram.

The naphthenic acids from which the sodium naphthenates are prepared have 10% point of about 350 F., 95% point of about 550 F. in distillation at 2 mm. of Hg absolute, and have saponification number of about 140 mg. of KOl-I per gram. Two volumes of the naphthenic acids are employed per volume of the partially oxidized foots oil having saponification number of 75 mg. of KOH per gram.

The sulfonic acid salts used in the composition are obtained by contacting an raflinate from furfural refining of lubricating oil with about 14 pounds of anhydrous SO per barrel of oil at ambient temperature, separating oil-insoluble Sulfonic acids from the product, extracting sodium salts of the oil-soluble sulfonic acids from the oil with aqueous isopropanol, and stripping off solvent to obtain the sodium salts for use in the composition. The sulfonic acids have average molecular Weight of about 450.

The oxidized rnicrowax employed in the above composition is obtained by the liquid phase partial oxidation of petroleum rnicrocrystalline wax having melting point of 178 F. The partial oxidation is conducted at about 260 F. by blowing with air for about 200 hours in the presence of 0.04 weight percent of manganese in the form of manganese naphthenate. The saponification number of the oxidized Wax is about 85 mg. of KOH per gram.

The emulsifiable composition is prepared by mixing the oxidized wax with the mineral oil at about 190 F.

to dissolve the oxidized wax in the oil, which is then cooled to about F. and is admixed with the petroleum naphthenic acids, the sulfonic acid salts and the oxidized foots oil, and with 50 B. sodium hydroxide in amount to neutralize the acids and provide the indicated amount of free alkali. The 2-methyl pentanediol as coupling agent is incorporated in the indicated amount, and the water content is adjusted to the indicated level.

A 2% emulsion of this composition in tap water containing 4050 parts per million total hardness is prepared at 63 F. and tested for foam-resisting characteristics by the following procedure: A 200 ml. sample is blown with air for 5 minutes in a ml. cylinder at room temperature. The air is supplied at a constant gauge pressure of 34 inches of water to a one-inch diameter spherical gas diffuser stone, as specified in A.S.T.M. Test D892-46T, through which it passes into the emulsion in the bottom of the cylinder. The emulsion passes the test since the foam which forms does not overflow the cylinder, and breaks completely within 15 seconds after shutting off the air supply.

To compare the oxidized microwax with an unoxidized microwax, a composition is prepared by identical procedure except that the microcrystalline wax is not oxidized but is employed directly in the unoxidized state as the foam inhibitor. In this case, the 2% emulsion overflows the 1000 ml. cylinder almost immediately upon introduction of air, and persists for more than seconds after the air is shut oif.

This example shows the superiority of the oxidized wax to the unoxidized wax as a foam inhibitor in mineral oil emulsions.

Exomple 2 The procedure of Example 1 is repeated, employing however a foam inhibitor obtained by polymerizing styrene in the presence of oxidized microcrystalline wax, in place of the oxidized microcrystalline wax of Example 1. The concentration of foam inhibitor is the same as in Example 1. The 2% emulsion passes the test described in Example 1. None of the foam inhibitor is deposited on the wall of the cylinder, whereas in Example 1, slight deposition of oxidized wax on the wall of the cylinder occurs during the air blowing.

This example shows that the polystyrene and oxidized wax composition provides the same improved foam suppression as the oxidized wax alone, and also is less subject to the precipitation of solid material.

The oxidized wax can be added to the emulsifiable composition or to the emulsion at any desired stage in the preparation. In cases where it is desired to add the oxidized Wax to an otherwise finished emulsifiable composition containing oil, soap and frequently small amounts of coupling agent and water, it is preferred to first dissolve the oxidized wax in a relatively small amount of oil to form a concentrated solution, which is then added to the emulsifiable composition in relatively small amount to provide the desired concentration of oxidized wax without unduly increasing the oil content. By adding a previously formed solution in oil, rather than the oxidized wax itself, to the emulsifiable composition, temperatures considerably below the melting point of the oxidized wax can be employed in the addition, thereby avoiding excessive vaporization of coupling agent or water from the emulsifi able composition during the addition. Any other suitable method of addition can be employed.

The invention claimed is:

1. A foam-inhibited emulsifiable mineral oil composition comprising the following components in the indicated ranges of proportions:

Mineral oil said carboxylic acid salts being selected from the group consisting of alkali metal and aliphatic amine salts of carboxylic acids selected from the group consisting of aliphatic and cycloaliphatic carboxylic acids having 12 to 30 carbon atoms per molecule, said sulfonic acid salts being selected from the group consisting of alkali metal and aliphatic amine salts of petroleum sulfonic acids, said oxidized microwax being the product of liquid phase partial oxidation of petroleum microcrystalline wax and having a saponification number of at least 40 mg. of KOH per gram, and said mineral oil being a petroleum lubricating oil having Saybolt Universal viscosity at 100 F. in the range from 50 to 300 seconds.

2. The composition according to claim 1 wherein the composition contains 0.1 to 1.5 weight percent of the product obtained by contacting partially oxidized petroleum microcrystalline wax with a monovinyl aromatic compound having the following formula:

where R is selected from the group consisting of hydrogen, methyl and ethyl radicals, A is selected from the group consisting of hydrogen, halogen and alkyl radicals having 1 to 3 carbon atoms inclusive, and B is selected from the group consisting of hydrogen, halogen and alkyl radicals having 1 to 3 carbon atoms inclusive, the amount of oxidized wax in the resulting mixture being in the range from 20 to weight percent of the mixture, said contacting being performed under conditions for polymerization of said'monovinyl aromatic compound, and the amount of oxidized wax in said product contained in said composition being in the range from 0.05 to 1.0 Weight percent of said composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,340,035 Zimmer et al. Jan. 25, 1944 2,545,677 Sperry Mar. 20, 1951 2,881,140 Schrum Apr. 7, 1959 2,944,039 Jolly July 5, 1960

Claims (1)

1. A FOAM-INHIBITED EMULSIFIABLE MINERAL OIL COMPOSITION COMPRISING THE FOLLOWING COMPONENTS IN THE INDICATED RANGES OF PROPORTIONS: