US2783203A - Corrosion preventing agent - Google Patents

Description

2,783,203 conRosroN PREVENTING AGENT John P. McDermott, Springfield, N. J., assignor to Ess-o Research and Engineering Company, a corporation of Delaware No Drawing. Application May 18, 1955, Serial No. 509,409

9 Claims. (Cl. 252,46.6)

The present invention relates to the improvement of hydrocarbon products derived from petroleum sources and more particularly to the preparation of improved mineral lubricating oil compositions by-the incorporation therein of a new class of additives which impart improved properties to such hydrocarbon products.

This application is a continuation-in-part of Serial No. 192,617, filed on October 27, 1950 and now abandoned.

in the development of petroleum lubricating oils the trend has been to use more and more eflicient refining methods in order to reduce the tendency of the oils to form carbon and deposits of solid matter or sludge. While such highly refined oils possess many advantages, their resistance to oxidation, particularly under conditions of severe service, is generally decreased and they are more prone to form soluble acidic oxidation products which are corrosive. They are generally less effective than the untreated oils in protecting the metal surfaces which they contact against rusting and corrosion due to oxygen and moisture. Although generally superior to lightly refined oils they may deposit films of varnis on hot metal surfaces,-such as the pistons of internal combustion engines, under very severe engine operating conditions.

In accordance with the present invention a new class of compounds has been discovered which when added to refined lubricating oils in small proportions substantially reduce the tendency of such oils'to corrode metal surfaces, and which are particularly eflective in inhibiting the corrosion of copper-lead and cadmium-silver bearings. They are likewise effective in inhibiting oxidation of such oils and other petroleum hydrocarbon products, as will be more fully explained hereinafter.

The new class of materials which have been found to possess the antioxidant and stabilizing qualities described above are oil-soluble reaction products of organo-substituted dithiophosphoric acids and styrene oxide. Such products may be defined broadly by the formula:

where R is an aliphatic, cycloaliphatic or aliphatic-aromatic organic radical, preferably a hydrocarbon radical, and where one of the symbols R1, R2, R3, and R4 represents aiphenyl radical and the others of the symbols R1, R2, R3 and R4 represent hydrogen atoms. Two dif ferent R radicals maybe present in the product. It is to be understood that the radicals represented by R in the above formula may also contain substituents such as halogen atoms or nitro groups. In general, the number of carbon atoms in the R radicals should be sufiicient to form a product having good oil solubility. Oil solubilizing radicals of about 3 to 30 carbon atoms are preferred. When R is an aliphatic hydrocarbon radical, it is preferred that it be an alkyl radical containing about 3 to 18 carbon atoms, particularly abut3 to-S carbon States Paten atoms; when R is an aliphatic-aromatic hydrocarbon radical, it is preferred that it be an alkyl phenyl radical containing about 4 to 18 carbon atoms, particularly 6 to 12 carbon atoms, in the alkyl group; and when R is a cycloaliphatic hydrocarbon radical, it is preferred that it be an alkyl cyclohexyl radical containing about 1 to 4 carbon atoms in the alkyl group. The preferred compounds are those where R is an aliphatic radical of relatively short chain length, preferably as stated above, an alkyl group containing about 3 to 8 carbon atoms.

' The following typical examples are representative of the dithiophosphoric acids which may be reacted with styrene oxide in accordance with the present invention:

Diisopropyl dithiophosphoric acid Di-n-butyl dithiophosphoric acid Diisobutyl dithiophosphoric acid Di-n-octyl dithiophosphoric acid Di-tert.-octyl dithiophosphoric acid Di-(ethylhexyl) dithiophosphoric acid Dinonyl dithiophosphoric acid Di-(Cs oXo) dithiophosphoric acid Dioleyl dithiophosphoric acid Dilauryl dithiophosphoric acid Di-(methylcyclohexyl) dithiophosphoric acid Di-(isopropylcyclohexyl) dithiophosphoric acid Di-(tert.-octylphenyl) dithiophosphoric acid Di-(2,4,6-triisobutylphenyl) dithiophosphoric acid The above listed dithiophosphoric acids may be prepared by reacting an alcohol or phenol with phosphorus pentasulfide by means well known in the art, and it is to be understood that the invention applies not only to simple acids but to mixtures of acids formed by reacting phosphorus pentasulfide with mixtures of alcohols, such, for example as the mixtures of C10 to C18 aliphatic alcohols known as Lorol alcohols, and the mixture of alcohols derived by the oxidation of paraffin wax. Included also are products derived from the mixture of branched chain aliphatic alcohols obtained in the 0x0 process.

The reaction between the dithiophosphoric acid and styrene oxide is a spontaneous exothermic reaction which takes place immediately upon contact of the reactants at normal room temperatures, and may be conveniently conducted by adding about one mole of the styrene oxide slowly to one mole of the dithiophosphoric acid while rapidly stirring the reaction mixture and controlling the temperature by means of a water or ice bath. General- 1y temperatures in the range of about 20 to C.

may be employed. No catalyst is required, and the time required for the completion of the reaction is not greater than two hours and is usually much less. Reaction times of about 0.2 to 2 hours may generally be employed. Solvents are not normally required, but in some cases it may be convenient to conduct the reaction in the presence of well known inert solvents such as ethylene dichloride, benzene, xylene, or a mineral oil.

The amount of the additives of the present invention which is to be employed in mineral lubricating oil compositions or other petroleum hydrocarbon compositions (which generally will contain a major proportion of the petroleum hydrocarbonoil) will normally range from about 0.02% to 5%, more generally from about 0.1 to about 2% by weight based on the total composition, and the particular amount in individual cases will be selected in accordance with the requirements of the case and in view of the properties of the base stock employed. For commercial purposes, it is convenient to prepare concentrated oil solutions in' which the amount of additive in the composition ranges from 25 to 50% by weight, and to transport and store them in such form. In preparing a lubricating oil composition for use as a crankcase lubricant the additive concentrate is merely blended with the base oil in the required amount.

The preparation and testing of the additives of the present invention are illustrated in the examples described below, but it is to be understood that the additives prepared and tested are illustrative only and are not to be construed as limiting the scope of the invention in any manner.

Example l.-Diisopropyl dithiophosphorz'c acid-styrene oxide reaction product A mixture of 120 g. (2 mols) of isopropanol and 111 g. (0.5 mol) of P255 was heated at 95 C. for 45 minutes in a H. 3-necked flask equipped with a stirrer, thermometer and reflux condenser. The product (diisopropyl dithiophosphoric acid) was then filtered to remove a small amount of unreacted P285, after which the filtrate was blown with nitrogen for 30 minutes on the steam bath.

The acid was then transferred to a 4-necked, 1-l. flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel. 120 g. of styrene oxide (1 mol) was then added over a period of 1 hour, keeping the temperature under 45 C. by means of a cold water bath. The reaction mixture was then stirred at room temperature for 1 hour. A pale yellow liquid was obtained which upon analysis was found to contain 8.7% phosphorus and 16.6% sulfur.

Example 2.Di-(methylcyclohexyl) dithiophosphoric acid-styrene oxide reaction product A mixture of 228 g. (2 mols) of methylcyclohexanol and 111 g. (0.5 mol) of P285 was heated at 105 C. for 1 hour. The product, di-(methylcyclohexyl) dithiophosphoric acid, was then filtered to remove a small amount of unreacted P285, after which the filtrate was blown with nitrogen for 20 minutes on the steam bath.

With rapid stirring, 120 g. (1 mol) of styrene oxide was added dropwise over a period of one hour keeping the temperature under 50 C. by means of a cold water bath. The reaction mixture was then stirred at room temperature for 1 hour followed by nitrogen blowing for 30 minutes. A viscous dark liquid was obtained which analyzed 5.4% phosphorus and 12.2% sulfur.

Example 3.Di-(nonylphenol) dithiophosphoric acidstyrene oxide reaction product A mixture of 440 g. (2 mols) of nonylphenol and 111 g.

(0.5 mol) of PzSs was heated at 150 C. for 1.5 hours. After cooling to room temperature, the viscous product was dissolved in an equal volume of carbon tetrachloride r Example 4.-S. O. D. Corrosion Test Blends were prepared containing 0.25% by weight of each of the products of Examples 1 to 3 in a paraffinic mineral lubricating oil of SAE 20 grade.

These blends and a sample of the unblended base oil were submitted to a corrosion test, known as the S. O. D.

Corrosion Test, designed to measure the effectiveness of the product in inhibiting the corrosiveness of a typical mineral lubricating oil toward the surfaces of copper-lead bearings. The test was conducted as follows: 500 cc. of the oils was placed in a glass oxidation tube (13 inches long and 2% inches in diameter) fitted at the bottom with a A inch air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heating bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area of 25 sq. cm. were attached to opposite sides of a stainless steel rod which was then immersed in the test oil and rotated at 600 R. P. M., thus providing sufficient agitation of the sample during the test. Air was then blown through the oil at the rate of 2 cu. ft. per hour. At the end of each 4-hour period the bearings were removed, washed with naphtha and weighed to determine the amount of loss by corrosion. The bearings were then repolished (to increase the severity of the test), reweighed, and then subjected to the test for additional 4-hour periods in like manner. The results are given in the following table as corrosion life, which indicates the number of hours required for the bearings to lose mg. in weight, determined by interpolation of the data obtained in the various periods.

Oil or oil blend Bearing corrosion life (hrs) The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, phosphites, thiophosphates, and thiophosphites, metal xanthates and thioxanthates, metal thiocarbamates, and the like. Other types of additives, such as phenols and phenol sulfides, may also be present.

The lubricating oil base stock used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraflinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced by solvent extraction with solvents such as phenol, sulfur dioxide, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils, prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products, or by the esterification of dicarboxylic acids with alcohols and/or glycols.

For the best results the base stock chosen should normally be an oil which with the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils, no strict rule can be laid down for the choice of the base stock. The additives are normally sulficiently soluble in the base stock, but in some cases auxiliary solvent agents may be used. The lubricating oils will usually range from about 40 to seconds (Saybolt) viscosity at 210 F. The viscosity index may range from 0 to 100 or even higher.

Other agents than those which have been mentioned may be present in the oil composition, such as dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, and the like.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having preferably 8-20 carbon atoms, e. g., octyl alcohol, lauryl alcohol, stearyl. alcohol, and the like.

In addition to being employed in lubricants, the additives of the present invention may also be used in other petroleum oil products such as motor fuels, heating oils, hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils, transformer oils, industrial oils, process oils, and the like, and generally as antioxidants in mineral oil products. They may also be used in gear lubricants, greases and other products containing mineral oils as ingredients.

What is claimed is:

l. A petroleum hydrocarbon product containing dissolved therein a corrosion inhibiting amount of an oilsoluble compound of the formulawhere R is an organic radical selected from the group consisting of aliphatic, cycloaliphatic and aliphatic-aromatic organic radicals; and Where one of the symbols R1, R2, R3, and R1 represents a phenyl radical and the others of the symbols R1, R2, R3 and R4 represent hydrogen atoms.

2. A composition according to claim 1 in which the petroleum hydrocarbon product is a lubricating oil fractron.

3. A composition according to claim 1 in which R represents a hydrocarbon radical.

4. A composition according to claim 1 in which R is an alkyl group containing 3 to 8 carbon atoms.

5. A composition according to claim 1 in which R represents a methyl-cyclohexyl radical.

6. A composition according to claim 1 in which R represents an isopropyl radical.

7. A composition according to claim 1 in which R represents a nonyl phenyl radical.

8. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and in the range of about 0.02 to 5% by weight, based on the total composition, of an oil-soluble compound of the formula where R is an organic radical selected from the group consisting of aliphatic, cycloaliphatic and aliphatic-aromatic organic radicals; and where one of the symbols R1, R2, R3, and R4 represents a phenyl radical and the others of the symbols R1, R2, R3 and R1 represent hydrogen atoms.

9. A composition consisting essentially of a mineral lubricating oil and about 25 to by weight of an oilsoluble compound of the formulawhere R is an organic radical selected from the group consisting of aliphatic, cycloaliphatic and aliphatic-aromatic organic radicals; and where one of the symbols R1, R2, R3, and R1 represents a phenyl radical and the others of the symbols R1, R2, R3 and R4 represent hydrogen atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,531,129 Hook et a1. Nov. 21, 1950

Claims (1)

1. A PETROLEUM HYDROCARBON PRODUCT CONTAINING DISSOLVED THEREIN A CORROSION INHIBITING AMOUNT OF AN OILSOLUBLE COMPOUND OF THE FORMULA-