US3434972A - Lubricant compositions containing rust inhibitors - Google Patents

Description

United States Patent 3,434,972 LUBRICANT COMPOSITIONS CONTAINING RUST INHIBITORS Warren Lowe, El Cerrito, Calif., assignor to Chevron Research Company, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Nov. 30, 1966, Ser. No. 597,876 Int. Cl. C10m N32 US. Cl. 25251.5 5 Claims ABSTRACT OF THE DISCLOSURE Lubricant composition having improved rust inhibiting properties containing an alkenyl succinimide detergent additive and as a rust inhibiting additive a diurethane of a pentaerythritol monocarboxylate.

This invention relates to lubricant compositions inhibited from rusting. More particularly, it relates to lubricants containing ashless nitrogen-containing detergents which have a propensity to promote rusting and as an inhibitor for the rusting, a diurethane formed from a pentaerythritol monocarboxylate.

Within recent years, it has become common practice to impart improved properties to lubricants by the addition of certain additives. Of particular importance in the operation of internal combustion engines is the use of certain compounds which function to present the accumulation of deposits such as varnish-like coating on pistons, cylinder walls and other operating parts of engines. These Compounds which act to disperse accumulated solids in the oil are known as dispersant or detergent-type additives.

Among the more successful detergent additives which have been introduced are the oil-soluble, high molecular weight basic nitrogen-containing compounds. Included among these materials are alkenyl succinimides and hydrocarbyl polyamines. These materials possess superior detergent characteristics and are employed in a variety of lubricant compositions. One of the primary reasons for employing these types of materials is their so-called ashless quality. That is, when they enter the combustion chamber of the engine and along with the fuel are combusted, they do not leave metallic ion-containing deposits which contribute to engine wear and loss of efiiciency. However, concomitant with their increased detergency and lack of metal-containing deposits, these materials have a tendency to promote oxidation of iron and steel surfaces. Thus, a lubricant containing one of these types of detergents will often fail to inhibit and often promote rusting of engine surfaces, particularl when the engine is at rest. It is thus desirable to incorporate in the lubricants materials which will inhibit rusting.

It has now been found that ashless lubricant compositions possessing excellent detergency characteristics and nonrusting characteristics can be formulated from a major portion of an oil of lubricating viscosity and minor portions of free amino group containing detergents, such as alkenyl succinimides of polyalkylene polyamines and hydrocarbyl-substituted polyalkylene polyamines, and as a rust inhibitor, a diurethane of the formula:

3,434,972 Patented Mar. 25, 1969 in which X and Y represent hydrogen or a carboxy acyl group of from about 10 to 24 carbon atoms, Ar represents an arylene group of from 6 to 15 carbon atoms, and one X and one Y are carboxy acyl.

The rust inhibitors of this invention can be most conveniently described as diurethanes or arylene diisocyanates and pentaerythritol monocarboxylate. The acyl radicals are derived from alkyl or alkenyl carboxylic acids or anhydrides of 10 to 24 carbon atoms. Thus, examples of suitable acids are decanoic, undecanoic, tridecanoic acids, etc. Also included among the suitable acids are the fatty acids or naturally occurring straight-chain, saturated and unsaturated aliphatic acids such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc.

Ar is derived from an arylene diisocyanate. Examples of suitable diisocyanates include the various benzene diisocyanates, tolylene diisocyanates, xylylene diisocyanates, biphenylene diisocyanate, cumene diisocyanate, diphenylmethane diisocyanate, etc.

The diurethane additive of this invention is most conveniently prepared by simply heating together two mols of the pentaerythritol monocarboxylate and one mol of the arylene diisocyanate at temperatures in the range of from 40 to about 125 C.

The following example illustrates the Preparation of the diurethane additive.

EXAMPLE 800 gms. (2 mols) of pentaerythritol monooleate was charged to a 3-necked flask equipped with a thermometer, water condenser, heating mantle and stirrer. The material was heated with stirring to about 50 C. and a total of 184 grams (1 mol) of tolylene diisocyanate was added slowly. The temperature of the reaction mixture was raised and heated at a temperature of from about to C. for a period of eight hours. The reaction mixture was allowed to cool, yielding a rather viscous material.

In order to demonstrate the rust-inhibiting characteristics of the lube compositions of this invention, the compositions were subjected to the CLR Rusting Test. This test, employing the single cylinder Cooperative Lubrication Research Engine, involved operating the engine under the following conditions:

Engine speed r.p.m 1800 Fuel rate lbs./hr 4.4 Air to fuel ratio a- 14/1 Jacket water temperature, out F Oil temperature F Intake air moisture grams H O/lb. of air 80 Intake air temperature F The test was conducted according to the following procedure: Two rusting test strips were placed in the crankcase, and the crankcase was filled with the subject test oil. The engine was operated for 15 hours under the above-described conditions. The engine was then stopped and the parts removed and inspected for rusting. The parts were then given a CRC Rust Rating on a scale of zero to 10, with zero being completely rust-covered and 10 being clean. An average rating was determined for the following parts: valve lifter body, plunger, and ball check; push rods, oil pressure relief ball, and crankcase test strips. When the average rating 'was above eight, the engine was reassembled and run under the standard operating condition for the additional five hours. The engine was then disassembled and the parts again rated. This procedure was repeated until the average rusting rating dropped below eight.

Rusting tests were performed using as a lubricant base a solvent-refined paraflinic neutral oil of SAE 20 grade containing 2.0% by weight of a polybutenyl succinimide detergent additive. The detergent was prepared by heating one mol of polybutenyl succinic anhydride having about 65 carbon atoms in the alkenyl chain with 0.9 mol of tetraethylene pcntamine. In addition, the oil contained 10 mm./kg. of a zinc ditisobutyl-mixed primary hexyl) dithiophosphate and 2 mrn./l g. of zinc di(polypropylphenyl)dithiophosphate. Comparative tests were made using the reference oil containing the diurethane and samples of the reference oil containing tetrapropenyl succinic acid, and highly successful commercial rust inhibitor. The testing sequence was performed by running the engine with the reference oil and the succinic acid inhibitor, determining the rust rating, cleaning the engine parts and running the test with the reference oil plus various amounts of the diurethane inhibitor. Data from these tests is given in the following table:

TABLE.(.LR ENGINE RUST TEST As can be seen from these data, the subject diurethane inhibitor compares very favorably with the substituted succinic acid as a rust inhibitor, giving a 27 hour test at 2% concentration.

The diurethane inhibitor of this invention is employed in amounts sufficient to inhibit oxidation of ferrous surfaces, generally of from about 0.5 to 5% by weight of the lubricant composition. Amounts of from about 1 to 4% are preferred.

The detergents employed in the compositions of this invention are the recently developed nitrogen-containing nonmetallic acid detergents. Examples of these detergents are those derived from alkenyl succinic anhydrides having 30, preferably 50 or more, carbon atoms in the al kenyl group and amine compounds such as tetraethylene pentamine, N-aminoethyl piperazine, dimethyl aminopropylene, etc. The detergent additive is generally obtained by adding one mol of an alkenyl succinic anhydride with at least 0.5 mol of an amine.

The substituted succinic anhydrides contemplated as reactants in the process can be readily obtained by heating maleic anhydride with a high molecular weight olefin or with a chlorinated high molecular weight olefin at a temperature of from about 150 to 200 C. Typical high molecular weight olefins which may be so employed are polyethylene, polypropylene, polyisobutylene, etc. Polyisohutylene is preferred.

Examples of suitable polyalkylene polyamine reactants are ethylene diamine, diethylene triamine, tetraethylene pentamine, and the like. Tetraethylene pentamine is the preferred polyamine reactant.

A preferred embodiment of the detergent additive is the product obtained by heating one mol of a polyisobutenyl succinic anhydride having about 65 carbon atoms in the olefin chain with 0.9 mol of tetraethylene pentamine.

The detergent additive is employed in the lubricant composition in an amount sufiicient to impart detergency. Generally, amounts of from 0.1 to 10% by Weight are preferred.

Any of the well-known types of lubricating oils can be used as the base oil for the compositions of this invention. These oils are corrosive to metal surfaces under normal operating conditions. Examples of such base oils are naphthenic base, paraflin base, and mixed base mineral oils; synthetic oils, e.g., alkylene polymers, such as polymers of propylene, butylene, etc. and mixtures thereof; alkylene oxide type polymers; clicarboxylic acid esters; phosphorus esters; silicone esters, such as silicates and polysiloxanes; and alkyl aromatic hydrocarbons.

The additives of this invention are effective in lubricant compositions containing additional conventional additives, such as oxygen inhibitors, supplementary detergents, sludge inhibitors, pour depressants, VI improvers, antifoarning agents, rust inhibitors, oiliness agents, wear inhibitors, dyes, etc.

While the character of this invention has been described in detail, this has been done by way of illustration only and without limitation of the invention. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples can be made in the practice of the invention Within the scope of the appended claims.

I claim:

1. A lubricant composition comprising a major portion of an oil of lubricating viscosity, a minor portion sufiicient to impart detergency of an alltenyl succinimide detergent and a minor portion sufiicient to inhibit rusting of ferrous surfaces at diurethane of the formula:

in which X and Y are hydrogen or a carboxy acyl group of 10 to 24 carbon atoms, Ar is an arylene group of 6 to 15 carbon atoms and only one X and one Y are carboxy acyl.

2. The composition of claim 1 in which the carboxy acyl groups are oleyl.

.3. The composition of claim 2 in which Ar is tolylene.

4. The composition of claim 1 in which the detergent additive is a polybutenyl succinimide prepared from a polybutenyl succinic anhydride having about 65 carbon atoms in the alkenyl chain and tetraethylene pentamine.

5. The composition of claim 4 wherein the polybutenyl succinimide is present in the amount of from 0.1 to 10% by weight and the diurethane from about 0.5 to 5% by weight.

References Cited UNITED STATES PATENTS 2,987,515 6/1961 Stromberg et al. 3,096,285 7/1963 Huttenlocher et al. 3,172,892 3/1965 Le Suer et al. 3,189,629 6/1965 Huttenlocher et al. 3,361,673 1/1968 Stuart et a1.

PATRICK l. GARVIN, Primary Examiner.

U.S. Cl. X.R. 252392