Oil-Soluble Adducts of Benzotriazole and Dialkylamines and Lubricant Compositions Containing the Same

1. Field of the Invention

This invention relates to a new addiitive composition constituting the reaction product adduct of benzotriazole and a specified dialkylamine.

This invention further relates to lubricant compositions which normally cause or induce oxidative deterioration and/or corrosion of metallic surfaces with which said compositions are in contact. More particularly, in one of its aspects, the invention relates to lubricant compositions, particularly petroleum derived compositions, such as mineral lubricating oils, automotive oils, gear oils, transmission fluids, hydraulic fluids, way lubricants, heavy circulating oils, greases and other forms of lubricant compositions normally requiring the presence of anticorrosion additives and which contain a minor proportion of the aforenoted additive.

2. Description of the Prior Art

Prior to the present invention, benzotriazole has been employed in lubricants as a metal deactivator. Benzotriazole-maleic anhydride adducts have also been known and are disclosed in "Elisa Shigi and Franca Rocchi," Gass. Chim. Ital. 84, 183 (1955). It is found, however, that these adducts are not effective anticorrosion agents inasmuch as they are not oil-soluble.

In accordance with the present invention, it has been found that anticorrosion properties can be effectively incorporated into lubricant compositions by including an anticorrosion amount of an adduct of benzotriazole and a specified dialkylamine. These adducts are soluble in organic compositions, such as the aforementioned lubricating oils, automotive oils, gear oils, transmission fluids, greases and other forms of lubricating compositions normally requiring the presence of anticorrosion additives and exhibit excellent anticorrosion properties.

Therefore, the invention herein described and claimed is more particularly drawn to an adduct of benzotriazole and a dialkylamine prepared by reacting benzotriazole with a suitable dialkylamine and to a lubricant composition comprising a major proportion of an oil of lubricating viscosity or grease prepared therefrom and a minor amount sufficient to impart anticorrosion properties thereto of said adduct.

The dialkylamines suitable herein include those having the general formula R.sub.1 R.sub.2 NH where R.sub.1 and R.sub.2 are alkyl groups of 4 to 20 carbon atoms. The groups may be either identical or dissimilar, providing they contain a number of carbon atoms within the aforenoted range. Also, it is contemplated that R.sub.1 +R.sub.2 may be cycloalkyl, in which instance the cycloalkyl group may contain from 4 to 40 carbon atoms. Thus, the dialkylamines can be symmetrical such as dioctylamine or unsymmetrical such as heptyloctylamine.

Exemplary of the dialkylamines useful in forming the described benzotriazole adduct are dioctylamine, didecylamine, didodecylamine and distearylamine.

The adduct can be effectively employed in any amount which is useful for imparting the desired degree of anticorrosion properties. In many applications, the adduct is effectively employed in an amount from about 0.001% to about 20%, by weight, and preferably in an amount from about 0.5% to about 5%, by weight, of the total weight of the lubricant composition.

In general, the adduct of benzotriazole and the specified dialkylamines are preferably reacted in a mole ratio of benzotriazole and dialkylamine of from about 1:1.5 to about 1:5. This reaction can be conducted at a temperature from about 80.degree. C., to about 150.degree. C. and preferably from about 90.degree. C. to about 110.degree. C.

The above-described benzotriazole-dialkylamine adducts, as previously mentioned, may be incorporated in any lubricating media, which may comprise, for example, liquid lubricating oils. These oils may be in the form of either a mineral oil or a synthetic oil in the form of a grease in which any of the aforementioned oils are employed as a vehicle. In general, mineral oils, employed as the lubricating or grease vehicle, may be of any suitable lubricating viscosity range, as for example, from about 45 SSU at 100.degree. F. to about 6,000 SSU at 100.degree. F., and, preferably, from about 50 to about 250 SSU at 210.degree. F. These oils may have viscosity indexes varying from below zero to about 100 or higher. Viscosity indexes from about 70 to about 95 are preferred. The average molecular weights of these oils may range from about 250 to about 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, or synthetic oils employed as the vehicle for the grease, are desired in preference to mineral oils, or in combination therewith, various compounds of this type may be successfully utilized. Typical synthetic vehicles include polyisobutylene, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, di(2-ethyl hexyl) sebacate, di(2-ethyl hexyl) adipate, dibutyl phthalate, fluorocarbons, silicate esters, silanes, esters of phosphorous-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chain-type polyphenyls, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl ethers typified by a butyl-substituted bis (p-phenoxy phenyl) ether, and phenoxy phenylethers.

The following examples and comparative data will serve to illustrate the novel adducts of the present invention and their anticorrosion properties in organic media, particularly lubricant compositions, containing them.

A mixture of di-n-octylamine (3 grams) and benzotriazole (1 gram) was stirred at 95.degree. C. for 5 minutes. The product was then tested for oil solubility and anticorrosion activity as described below.

The product was prepared and tested as described in Example 1, except that di-n-decylamine was substituted for di-n-octylamine.

The product was prepared and tested as described in Example 1, except that di-n-dodecylamine was substituted for di-n-octylamine.

The product was prepared and tested as described in Example 1, except that distearylamine was substituted for di-n-octylamine.

A mixture of di-n-octylamine (9 grams) and benzotriazole (1 gram) was stirred at 95.degree. C. for 5 minutes. The product was then tested for oil solubility as described below.

The product was prepared and tested as in Example 5 except that di-n-dodecylamine was substituted for di-n-octylamine.

The product was prepared and tested as in Example 5 except that distearylamine was substituted for di-n-octylamine.

The additives were tested for solubility in a 150 SUS solvent-refined mineral oil by measuring the time required to dissolve at 65.degree. C., and the time required for formation of haze at 25.degree. C. All additives were tested at the 0.1% benzotriazole level. A comparison with unreacted benzotriazole is shown in Table 1 below.

Representative additives were then evaluated with respect to their abilities to protect copper and steel against corrosion by elemental sulfur in oil. The oil blend used for testing the aforementioned was an Arabian Light 150 SUS oil containing 50 ppm of elemental sulfur. The Modified ASLE-64-9 Corrosion Test was used.

Place clean polished pieces.sup.(1) of copper and carbon steel rods (approximate 0.25 inches diameter by 3.0 inches long) in a 100-cc Griffin beaker containing 35 to 40 grams of oil sample. Put beaker and contents into an electric drying oven for 24 hours, maintaining a temperature of 210.degree..+-.2.degree. F. (99.degree..+-.1.degree. C.). Test period may be extended 72 hours, if necessary.

Test results:

Condition of Steel Rod

Condition of Copper Rod

Precipitate or Sludge

Evaporation Loss % Wt.

Specimens should be rated "as is" when removed from the oil (no washing); copper and steel rods are rated by comparing them and assigning the number from 1 (clean) to 10 (completely covered with corrosion) which most closely resembles their condition.

The data summarized in the Tables clearly establish that lubricant compositions of effective anticorrosion characteristics are provided when the reaction product of benzotriazole and a dialkylamine as defined herein are added in minor amounts thereto.

It is apparent to those skilled in the art that the present invention has been described with reference to preferred emobidments and that departure therefrom can be effectively made and are within the scope of the specification.