US2370080A - Stabilized lubricant composition - Google Patents

Description

Patented Feb. 20, 1945 2,370,080 STABILIZED LUBRICANT COMPOSITION William Schreiber, Philadelphia, Pa., aleignor to.

The Atlantic Refining Company, Phiiadelp Pa., a corporation of Pennsylvania No Drawing. ApplieationFebruary 3, 1943,

Serial No. 474,615

6 Claims.

The present invention relates to lubricating compositions, and more particularly to lubricating oils containing metal salts or soaps as detergents, oxidation inhibitors,

form a haze in the oil in the presence of moisture.

An object of this invention is to prevent the formation of haze in ,oils containing metal salts or soaps, and especially in oils containing metal salts of acid esters of acids of phosphorus.

A further object of this invention is the use of phosphatldes or mixtures of the same to pre vent the formation of haze in lubricating oils containing metal salts, and particularly the alkaline earth metal salts of acid esters of the thio-acids of phosphorus.-

It has been proposed heretofore to add to lubricating oils various metal salts or soaps to function as detergents, antioxidants or anti-corrosion agents, and it has been found that the alkaline earth metal salts, and particularly the barium salts of the acid esters of the acids of phosphorus were highly efiective in this capacity, the only disadvantage being that these compounds tended to form a haze in thevoil in the presence of moisture.

I have discovered that the formation of haze in oils containing a metal salt of an acid ester of an acid of phosphorus may be reduced or prevented by the addition to the oil of a relatively small quantity of a phosphatide such as lecithin or cephalin. The-phosphatides belong to the class of compounds having the general formula wherein R and R are similar or dissimilar fatty acid radicals, such as those derived from stearic, palmitic, or oleic acids, and where X represents an amino alcohol group. In the case of lecithin, X or the amino alcohol group is choline T --CH2CH2N(CH3) :OH

and in the case of cephalin x is 'colamine anti-corrosion agents and the like, which compounds tend to phorus, whereby a hydrated compound is formed which is less soluble in the oil than the original compound. The action of the phosphatide or lecithin in reducing or preventing the formationof haze is at present unknown.

In accordance with my invention, I incorporate in a hydrocarbon oil, such as a lubricating oil of suitable viscosity, a detergent or inhibitor comprising a metal salt of an acid ester of an acid of phosphorus and a phosphatide, such as lecithin, in an amount suflicient to prevent the formation of. hazedue to the effect of moisture upon the soap contained in the oil. The detergents, or inhibitors may be employed in various quantities depending upon thetype of oil used and the service to which the oil is to be put. For ordinary service in internal combustion engines of passenger cars, light trucks, and the like, quantities of inhibitor of the order 012 0.01 per cent to about l per cent by weight have been found satisfactory. On the other hand, for heavy duty service in Diesel engines, tractor engines, and heavy truck or bus engines, considerably more inhibitor is'required, i. e., amounts of the order of 1 per cent to 5 per cent, and in many cases between 5 per cent and 10 per cent. The quantity of phosphatide required to reduce or prevent the formation of haze will vary depending upon the composition or nature of the inhibitor and the amount of such inhibitor incorporated in the oil. In general, the quantity of phosphatide required will range from about 10 per cent to per cent of the quantity of the inhibitor added to the oil.

The inhibitors which are employed in accordance with this invention in conjunction with the phosphatide comprise one or a mixture of two or more metal salts of acid esters of an acid of phosphorus, and particularly the alkt line earth metal salts of acid esters of a thin-acid of phosphorus. The metals may be exemplified by Ca,

Ba,'Sr, Mg, Na, K, Li, Cu, Zn, Pb, Sn, Ni, Co and" hydroaryi groups may be exemplified by phenyl, naphthyl, anthryl, cresyl, tolyl, xylyl, cyclohexyl, and naphthenyl. The mixed groups comprise propyl phenyl, butyl phenyl, amyl phenyl, hexyl naphthyl, cetyl cresyl, lauryl xylyl, as well as the mixed alkyl functions ethyl propyl, ethyl butyl, butyl hexyl, hexyl lauryl, and the like.

Specific examples of the metal salts of the acid esters of the acids of phosphorus are given in the following table.

Aluminum salt or lauryl cresyl acid ester of phosphoric acid Calcium salt of phenyl stearyl acid ester oi phosphoric acid.

The metal salts of the acid esters of the acids of phosphorus may be used in conjunction with a phosphatide, or may be used in admixture with other inhibitors or detergents such as metal sulionates, metal salts of phenol or phenol sulfides,

metal stearates, metal naphthenates or the like,

in conjunction with a phosphatide.

My invention may be further illustrated by I the following examples, which, however, are not to be construed as limiting the scope thereof. In these examples, samples of motor lubricating oil containing a metal salt of an acid ester an acid of phosphorus, as well as samples oi the oil containing the metal salt and in addition various amounts of lecithin, were in one case subjected to storage under normal conditions, and in the second case, were contacted with a minute amount or added water (1 drop of water per 100 cc. of oil sample), and then stored. The samples were examined periodically to determine the length of time before haze appeared in the oil. The results are shown in the following table.

Days storage before haze formation Oil composition Normal stor- In contact age with water 0ii+0.5% Ba salt of lauryl hexyl acid thiophosphate Less than 1 Less than i 0ii+0.5% Ba salt oi lauryl hexyl acid thiophosphate+0.25% lecithin 21+ l6+ Oil-+0.59}, Ba suit oi lauryl hexyl acid thiophoephate+0.t% lecithin 23+ Oil-wh z, Ba salt'oi dihexyl acid thichosp ate Less than i Less than i O 1+0.5% Ba salt oi dihexyi acid thicphosp ate-i-O.5% lecithin. 24+ 16+ ()il+0.57 Zn salt of lauryl hexyl acid thloph sphate 7 Less than 1 Oil+0.5% Zn salt of lauryl hexyl acid thiophosphate+0.25% lecithin 26+ 17+ (NH-0.5% Zn salt oi leuryl hcxyl acid thiophosphate+0.5% lecithin 29+ KH- The effect of lecithin upon lubricating oils containing a metal salt of an acid ester of an acid 01' phosphorus, when such oils are subjected to oxidation is shown in the following table. The oxidation test comprised heating cc. of the oil sample. to which had been added 0.1% oi iron naphthenate as an oxidation catalyst, at a temperature of 340 F. for 18 hours, while bubbling air through the sample at a rate oi 300 cc. per minute. At the completion oi the heating period, the neutralization number of the sample was determined by conventional methods. In the table, inhibitor A is a barium salt of lauryl hexyl acid thiophosphate and barium phenol sulfide, and inhibitor B is a barium salt of lauryl mixed hexyl acid thiophosphate and barium phenol sulfide.

Oil composition Neut. lv'o.

motor oil motor oil+0.25 0 inhibitor A motor oil+0.5 inhibitor A 30 motor oil .25 0 inhibitor A-i-0.25% lecithin. 30 motor oil 0.25% inhibitor A+0.5% lecithin. 30 motor oil+0.5% inhibitor .+0.25% lecithin. 30 motor 0ll+0.5% inhibitor A+0.6% lecithin.

. 30 motor oil-+0.25% inhibitor B 30 motor oll+0.5% inhibitor B 30 motor oll+0.25% inhibitor B+o.25% lecithin. 30 motor oil+0.25% inhibitor B+0.6 lecithin. 30 motor oil+0.6% inhibitor R+0.257 lecithin" 30 motor oil-+0.15% inhibitor B+0.5%leclthln.

It will be apparent from the results given here-- inabove that lecithin exerts a beneficial influence upon oils containing metal salts of acid esters of acids of phosphorus not only from the standpoint of preventing the formation of haze but also of decreasing the formation of acidity in the oils due to oxidation.

Furthermore, while the combination 01 these metal salts and lecithin is particularly adapted for use in connection with lubricants for internal combustion engines t maintain general engine cleanliness, such combination of compounds is also .0! utility in oils for cutting or shaping metals, in greases and gear lubricants, and in other com positions wherein stability against oxidation is of prime importance.

1 claim:

1. A lubricant comprising hydrocarbon oil con taining a metal salt of an acid ester of an acid of phosphorus, said salt being present in an amountwhich would normally result in the formation of a haze in said oil in the presence oi moisture, and a phosphatide in an amount sumcient to Rimm ng prevent said haze.

2. A lubricant comprising hydracaroon oil containing an alkaline earth metal salt or an acid ester or an acid of phosphorus, said salt beinr; present in an amount which would normally result in the formation of a haze in said oil in the presence of moisture, and a phosphatide in an amount suilicient to prevent said haze.

3. A lubricant comprising hydrocarbon oil containing an alkaline earth metal salt of an acid ester of a thio-acid of phosphorus, said salt being present in an amount which would normally result in the formation of a haze in said 011 in the presence of moisture, and a phosphatide in an amount sumcient to prevent said haze.

4. A lubricant comprising hydrocarbon oil containing a barium salt of an acid ester of a table-- acid of phosphorus, said salt being present in an amount which would normally result in the tormation or a haze in said oil in the presence of moisture, and a phosphatide in an amount sumcient to prevent said base.

5. A lubricant comprising hydrocarbon oil containing a barium salt of a hexyl lauryl acid ester taining 29. barium vszelt of a. dihexyl acid ester of of thiophosphorlc acid in an amount which would thiophosphoric acid in an amount which would normally result in the formation of a haze insald normally result in the formation of a. haze in oil in the presence of moisture, and lecithin in said oil in the presence of moisture, and lecithin 6 an amount suflicient to prevent said haze. in an amount sufiicient to prevent said haze. I v

6. A lubricant comprising hydrocarbon oil con- WILLIAM BCHREIBER.