Borated Adducts of Diamines and Alkoxides, as Multifunctional Lubricant Additives, and Compositions Thereof

This application is related to copending application Ser. No. 566,069, filed even date herewith entitled Multifunctional Lubricant Additives.

Borated adducts of hydrocarbyl diamines with long chain hydrocarbylene alkoxides and low molecular weight carboxylic acids have been found to be highly effective multifunctional high temperature stabilizing and friction reducing additives for both hydrocarbyl lubricants and fuels. In addition, minor amounts of these borated amino compounds improve high temperature stability of lubricants, greases and other solid lubricants prepared therefrom and possess potential detergency/dispersancy properties when blended into hydrocarbyl lubricants and fuels.

Many amine reaction products have been widely used as petroleum product additives in fuel and lubricant applications. In many instances these amine reaction products have been used to provide dispersancy/detergency and/or antirust properties. Also, amines, amides and their borated adducts have found widespread use in various petroleum products.

U.S. Pat. No. 4,389,322 describes certain ethoxylated amides and borated adducts thereof as being effective friction reducing additives.

U.S. Pat. No. 4,382,006 describes ethoxylated amines and their borated derivatives as being effective friction modifying additives for various hydrocarbyl lubricants. U.S. Pat. No. 4,328,113 describes alkylamines, alkyldiamines and borated adducts of alkylamines and diamines as effective friction reducing additives when incorporated into lubricating oils. Thus, many boron containing compositions have proven useful in fuel and lubricant compositions. They often provide brake fluid stabilizing or special gasoline enhancing properties to such compositions.

U.S. Pat. No. 4,368,129 describes metal salts of partially borated partially phosphosulfurized polyols and hydroxyl-containing esters as effective multifunctional friction reducing antioxidant and copper strip passivating additives when used in lubricating media such as hydraulic oils, brake oils, power transmission oils and the like.

It has now been found that borated adducts of hydrocarbyl diamines, hydrocarbylene epoxyalkanes and low molecular weight carboxylic acids possess at minor concentrations significant effective friction reducing and high temperature stabilizing properties when incorporated into hydrocarbyl lubricants and fuels. They also are expected to be effective antirust agents.

In accordance with the invention there is provided unique novel additives and compositions thereof which are borated reaction products of diamines such as N-coco-1,3-propylenediamine and long chain alkoxides such as epoxyalkanes and low molecular weight carboxylic acids such as formic acid. These novel reaction products provide multifunctional high temperature stabilizing and friction reducing additives for lubricants and fuels.

The borated adducts of hydrocarbyl diamines and hydrocarbylene alkoxides in accordance with the invention may be prepared as described below. ##STR1## where R is C.sub.8 -C.sub.20 hydrocarbyl, preferably alkyl or hydrocarbyloxy

R.sup.1 is C.sub.2 -C.sub.4 hydrocarbylene, preferably ethylene or propylene

R.sup.2 is C.sub.6 -C.sub.20 hydrocarbyl

R.sup.3 is hydrogen or C.sub.1--C.sub.6 hydrocarbyl

Useful hydrocarbyldiamines and hydrocarbyloxydiamines include, for example, N-tallow-1,3-propylenediamine; N-soya-1,3-propylenediamine; N-oleyl-1,2-ethylenediamine; N-tallow-1,2-ethylenediamine; N-soya-1,2-ethylenediamine; N-coco-1,2-ethylenediamine; N-triisodecyloxy-1,3-propylenediamine; N-coco-1,3-propylenediamine; N-oleyl-1,3-propylenediamine and mixtures thereof. Useful alkoxides or epoxyalkanes include 1,2-epoxypentadecane; 1,2-epoxyhexadecane; 1,2-epoxyheptadecane; 1,2-epoxydodecane; 1,2-epoxytetradecane; epoxidized isobutylenetrimer, epoxidized propylenetetramer; 1,2-epoxyoctadecane or mixtures thereof. Mixtures are, depending on such as the specific reactants and reaction conditions, on occasion preferred.

The carboxylic acids used include, but are not limited to such acids as formic acid, acetic acid, propionic acid and the like. Preferred are C.sub.1 to about C.sub.8 acids and especially formic acid.

Boronating species can include boric acid, low molecular weight trialkyl borates and other suitable boron carriers.

The borated derivatives may be prepared by treating the reaction product of the diamine and alkoxide with up to or essentially molar quantities of carboxylic acid and then borating. Reaction with the carboxylic acid and boration can be done concurrently. The amines and alkoxides are also usually present in molar quantities but a ratio of from about 2:1 to about 1:2 may be used. For example, the derivatives described herein may be prepared by treating the reaction product of a diamine, low molecular weight carboxylic acid and an epoxyalkane with boric acid in the presence of an alcoholic or hydrocarbon solvent. The presence of a solvent is not essential. However, if one is used, it may be reactive or non-reactive. Suitable non-reactive solvents include benzene, toluene, xylene and the like. Suitable reactive solvents include isopropanol, butanol, the pentanols and the like. In general, reaction temperatures may vary from about 70.degree. to about 250.degree. with 80.degree. to about 180.degree. C. being preferred. Generally stoichiometric amounts of boric acid or other borating species are used. However, amounts in excess of this can be used to obtain compounds of varying degrees of boration. Boration can therefore be complete or partial. Boration levels may vary in the instant compounds from about 0.05 to about 7 wt. %. The diamines embodied herein, however, may be borated by any means known in the art. In general, the adducts of this invention possess greater friction reducing properties than similar non-borated derivatives. For example, as little as 0.02 wt. % up to about 1 to 2% wt. % of these additive compounds may reduce friction of a fully blended automotive engine oil as much as 39%. However, amounts up to 5-10% may be used if desired.

These products may be incorporated into various lubricating media, for example, liquid hydrocarbon oils in the form of either a mineral oil or a synthetic oil, or in the form of a grease, in which any of the aforementioned oils are employed as a vehicle. These lubricants can also contain detergents and dispersants, as well as inhibitors, antiwear, extreme pressure, antifoam, pour depressant, and viscosity index improving additives without negating the beneficial properties of the novel additives/products of this invention.

In general, mineral oils employed as the lubricant or grease vehicle may be of any suitable lubricating viscosity range, for example, from about 45 SSU at 100.degree. F. to about 6,000 SSU at 100.degree. F., and preferably from about 50 SSU at 210.degree. F. to about 250 SSU at 210.degree. F. These oils may have viscosity indexes varying from below 0 to about 100 or higher. Viscosity indexes from about 70 to about 95 are preferred. The average molecular weight of these oils may range from about 250 to 800. Where the lubricant is to be employed in the form of a grease, the lubricating oil is generally employed in an amount sufficient to balance the total grease composition, after accounting for the desired quantity of the thickening agent, and other additive components to be included in the grease formulation.

In instances where synthetic oils are employed as the vehicle for the grease, in preference to mineral oils or in combination therewith, various compounds of this type may be successfully utilized. Typical synthetic vehicles include polyisobutylenes, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, di(2-ethylhexyl) sebacate, di(2-ethylhexyl) adiptate, di(butylphthalate) fluorocarbons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chain-type polyphenols, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl ethers typified by a butyl-substituted bis(p-phenoxy phenyl) ether, phenoxy phenylethers, etc.

The lubricating vehicles of the aforementioned greases of the present invention, containing the above described products, are combined with a grease forming quantity of a thickening agent. For this purpose, a wide variety of material may be employed. These thickening or gelling agents may include any of the conventional metal salts or soaps, which are dispersed in the lubricating vehicle in grease-forming quantities in such degree as to impart to the resulting grease composition the desired consistency. Other thickening agents that may be employed in the grease formulation may comprise the non-soap thickeners, such as surface modified clays and silicas, aryl ureas, calcium complexes and similar materials. In general, grease thickeners may be employed which do no melt and dissolve when used at the required temperature within the particular environment, however, in all other respects any materials which are normally employed for thickening or gelling hydrocarbon fluids for forming greases, can be used in preparing improved greases in accordance with the present invention. Alkali and alkaline earth metal soaps of hydroxyl-containing fatty acids, glycerides and esters having from 12 to 30 carbon atoms per molecule are often preferred. The metals as typified by sodium, lithium, calcium and barium. Lithium is preferred. Thickeners containing a portion of the above soaps are also preferred.

Other additives that can be used beneficially with the invention include but are not limited to zinc dialkyl or diaryl dithiophosphates, metallic phenates and sulfonates and succinimide-type or ester ashless dispersants. The metallic phenates and sulfonates are preferably calcium or magnesium or overbased calcium or magnesium phenates or sulfonates. High temperature properties are often benefitted in the presence of 0.1-3 wt. % of a zinc dithiophosphate derived from low molecular alcohols such as isopropanols, butanols, pentanols, hexanols, decanols and the like.

The following examples and evaluation thereof will specifically illustrate the invention. It will be understood that they are meant to be illustrations and of not limitations to the invention.

Approximately 720 g of N-oleyl-1,3-propylenediamine (commercially obtained as Duomeen O from Armak Chemical Co.), 150 g toluene and 480 g of 1,2-epoxyhexadecane (commercially obtained as a C.sub.16 alpha-olefin epoxide) were charged to a 3 liter reactor equipped with heater, agitator, and provision for blanketing the vapor space with nitrogen. The reaction mixture was heated at 120.degree. C. for a period of 14 hours. The solvent was then removed by vacuum distillation to form the intermediate adduction product.

Approximately 120 g of the above adduction intermediate product were charged to a reactor equipped with heater, agitator, Dean-Stark tube with condenser and provision for blanketing the vapor space with nitrogen. Approximately 100 g toluene were added and the reactor contents were warmed to about 60.degree. C. Approximately 12 g formic acid were added, followed by the addition of 6 g boric acid. The reaction mixture was slowly heated to 160.degree. C. over a period of 8 hours until water evolution during the azeotropic distillation ceased. The solvent and other volatile materials were removed by vacuum distillation at 160.degree. C. The product was cooled to 110.degree. C. and filtered through diatomaceous earth.

Approximately 720 g of N-oleyl-1,3-propylenediamine (commercially obtained as Duomeen O from Armak Chemical Co.), 150 g toluene and 480 g of 1,2-epoxyhexadecane (commercially obtained as a C.sub.16 alpha-olefin epoxide) were charged to a 3 liter reactor equipped with heater, agitator, and provision for blanketing the vapor space with nitrogen. The reaction mixture was heated at 120.degree. C. for a period of 14 hours. The solvent was then removed by vacuum distillation to form the intermediate adduction product.

Approximately 120 g of the above adduction intermediate product were charged to a reactor equipped with heater, agitator, Dean-Stark tube with condenser, and provision for blanketing the vapor space with nitrogen. Approximately 100 g toluene were added and the reactor contents were warmed to about 60.degree. C. Approximately 12 g formic acid was added and the reactor temperature was slowly raised to 150.degree. C. over a period of 41/2 hours until water evolution during azeotropic distillation ceased. The reactor contents were cooled to 90.degree. C. and 100 g toluene and 18 g boric acid were added. The reaction mixture was again heated to 160.degree. C. over a period of 5 hours until water evolution during azeotropic distillation ceased. The crude product was vacuum distilled at 160.degree. C. The product was cooled to 110.degree. C. and filtered through diatomaceous earth.

The formic acid treated adducts of the alkyl diamines and the epoxyalkanes were blended into fully formulated synthetic and mineral oil based lubricants containing ashless dispersants, metallic phenates and sulfonates, zinc dialkyl dithiophosphates derived from butanols and pentanols and polymeric viscosity index improving additives. The formulations were then evaluated for friction reducing properties using the Low Velocity Friction Apparatus. As can be seen in Tables 1 and 2, the compositions reduced fruction by up to 39%.

The formic acid treated adducts of the alkyl diamines and the epoxyalkanes were also blended into a solvent refined paraffinic neutral lubricating oil and tested for resistance to oxidation using the Catalytic Oxidation Test. The data therefrom is shown in Table 3. The composition of this application exhibited good control of acidity increase and good control of viscosity increase.

The products in accordance with the invention were evaluated in the below described manner.

The Low Velocity Friction Apparatus (VFA) is used to measure the coefficient of friction of test lubricants under various loads, temperatures, and sliding speeds. The LVFA consists of a flat SAE 1020 steel surface (diameter 1.5 in.) which is attached to a drive shaft and rotated over a stationary, raised, narrow ringed SAE 1020 steel surface (area 0.08 in..sup.2). Both surfaces are submerged in the test lubricant. Friction between the steel surfaces is measured as a function of the sliding speed at a lubricant temperature of 250.degree. F. The friction between the rubbing surfaces is measured using a torque arm-strain gauge system. The strain gauge output, which is calibrated to be equal to the coefficient of friction, is fed to the Y axis of an X-Y plotter. The speed signal from the tachometer-generator is fed to the X-axis. To minimize external friction, the piston is supported by an air bearing. The normal force loading the rubbing surfaces is regulated by air pressure on the bottom of the piston. The drive system consists of an infinitely variable-speed hydraulic transmission driven by a 1/2 HP electric motor. To vary the sliding speed, the output speed of the transmission is regulated by a lever-cammotor arrangement.

The rubbing surfaces and 12-13 ml of test lubricants are placed on the LVFA. A 240 psi load is applied and the slidig speed is maintained at 40 fpm at ambient temperature for a few minutes. A plot for coefficients of friction (U.sub.k) vs. speed were taken at 240, 300, 400, and 500 psi. Freshly polished steel specimens are used for each run. The suface of the steel is parallel ground to 4 to 8 microinches. The results in Table 1 refer to percent reduction in friction compared to the unmodified oil. That is, the formulation mentioned above was tested without an additive compound of this invention and this became the basis for comparison. The results were obtained at 250.degree. F. and 500 psi, and 40 fpm sliding speed. Freshly polished steel specimens are used for each run. The surface of the steel is parallel ground to 4 to 8 microinches. The percentages by weight are percentages by weight of the total lubricating oil composition, including the usual additive package. The data are percent decrease in friction according to: ##EQU1## Thus, the corresponding value for the oil alone would be zero for the form of the data used in Table 1 and Table 2 below.

Examples 1 and 2 were also tested for antioxidant characteristics in the B-10 Catalytic Oxidation Test at 325.degree. F. for 40 hours. Present in the composition comprising a 200 seconds paraffinic neutral oil in addition to the additive compound were metals commonly used as materials to construct engines namely:

(a) 15.6 sq. in of sand-blasted iron wire;

(b) 0.78 sq. in. of polished copper wire;

(c) 0.87 sq. in. of polished aluminum wire; and

(d) 0.107 sq. in. of polished lead surface. The test results as noted hereinbefore are reported below in Table 3.

It is clear that the use of borated adducts of hydrocarbyl diamines and hydrocarbylene alkoxides or epoxyalkanes and lower molecular weight carboxylic acids such as formic acid when incorporated into premium quality lubricant greases and fuels improve the high temperature stabilizing, antiwear characteristics and fuel economy properties without adverse affect upon other key performance areas. These families of novel multifunctional additives are non-corrosive in nature since chloride, sulfur and other potentially active species are absent. Accordingly, it is concluded that these borates also contribute to the anti-rust/anti-corrosion properties of fully formulated lubricants and fuels.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims.