US2154097A - Lubricating oil - Google Patents

Description

Patented Apr. 11, 1939 STATES PATNT mmmcs'rme on.

Clarence M. Loane, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing.

3 Claims.

This invention relates to lubricants and, in particular, to addition agents imparting improved properties to lubricants.

This invention has particular utility in improving the lubricating properties of lubricating oils and/or in preventing or inhibiting the corrosion of hard metal alloy bearings such as copperlead, cadmium-nickel and cadmium-silver bearings which, to a large ,extent, have replaced soft metal bearings, such as Babbitt metal, in the trend toward internal combustion engines having high compression ratios and increased acceleration and increased speed characteristics. The use of the hard metal bearings has created lubricating and corrosion problems, particularly in connection with highly refined oils, some of which may be very corrosive to bearings 01 the hard metal type.

As used herein highly refined lubricating 011 means viscous oils which have a minimum viscosity of S. A. E. 10 oils, or higher, and which have been subjected to such refining processes that the paraffinicity of the oil is markedly increased. It has been found that highly refined" lubricating oils cause corrosion to alloy bearings of the hard metal type such as cadmium-silver alloy bearings to the extent of about 5 mg/cm. and even greater when such bearings are submerged for 25 hours or less in an air agitated oil alloy bearings of the cadmium-silver type in the presence of highly refined lubricating oils can be inhibited by adding to the said oil up to 2%, but preferably 0.05% to 0.75% of certain organic compounds, particularly the bivalent radical substituted five membered ring compounds having sulfur and nitrogen in the ring, said compounds having the general formula in which x is a benzo radical or arylene derivative thereof and in which R is hydrogen or alkyl or aryl or SH or S alkyl or S aryl or Application November 27, 19136 Serial No. 112,993

or- NH2 or NH alkyl or -N- alkyl or mixtures thereof and/or R1 may be hydrogen or alkyl or halogen or amino or mercapto or alkyl substituted amino or substituted mercapto or substituted'benzothiazole group or groups and/or mixtures thereof.

Specific examples of the benzothiazoles having the general formula (6) in which R is hydrogen or alkyl or aryl or --SH or S alkylor -.--S-- aryl or S-Calkyl And the naphthothiazole derivatives of the a above such as:

Mercapto naphthothiazole Amino naphthothiazole Hexyl naphthothiazole Phenyl naphthothiazole In addition to the above compounds I have found that the benzo derivatives of the thio (AA) diazoles which are known as the piazothioles are effective corrosion inhibitors.

The effectiveness of compounds or the above type as corrosion inhibitors is demonstrated by merged in the air agitated oil at about 340 F.

the following test in which oils to which the inhibitor has been added were subjected to conditions which are more severe than those encountered in the actual operation of internal combustion engines.

Weighed cadmium-silver alloy bearings were submerged in samples of a highly refined oil with and without the addition of the compound to be tested and the oil air agitated while maintained at a temperature of about 341 F. At regular intervals the cadmium-silver alloy bearings were removed from the bath, washed free of oil, and weighed to determine the loss in Weight. The hearings were then replaced in the oil and further tested. The oil used was a motor oil refined to such an extent that a loss in weight of more than 5 mg/cm. is obtained in hours or less on a cadmium-silver alloy bearing subwhich oil has been preoxidized for 25 to 50 hours 7 at about 340 F.

Control v Confrol+.2% mercapto-benzothiazo e The following results were obtained on cadmium-silver alloy bearings when tested in the foregoing manner,

Duration of test Oil 25 hrs. hrs. hrs.

Loss in weight (mg/cmfi) The above data definitely show the high inhibiting efiect of the mercapto benzothiazole.

Although I prefer to use the compounds of the hereinabove type which are completely oil soluble, equally effective results are obtained with arcane? highly refined lubricating oils normally corrosive to said bearing metal alloys in internal combustion engines which comprises adding to said lubricating oils a mercapto benzothiazole in a small but sufiicient quantity to effect the retardation of said corrosion to said bearing metal alloys.

2. The method of-preventing corrosion of hard metal alloy bearings in the presence of highly refined lubricating oils normally corrosive to said hard metal alloy bearings in internal combustion engines which comprises adding to said lubricating oils a bivalent radical substituted five-membered ring compound having sulfur and nitrogen in the ring and having the general formula in which X is a radical selected from the group consisting of a benzo radical and an arylene de rivative of a benzo radical, R is a substituent refined'lubricating oils normally corrosive to said hard metal alloy bearings in internal combustion engines which comprises adding to said lubricating oils abenzothia zole having the general formula A Q N R1 C-R J s l in which R is a substituent selected from the group consisting of hydrogen, an alkyl radical and an .aryl radical, and R1 is a substituent selected from the group consisting of hydrogen, an alkyl radical, an aryl radical, a mercapto group and an amino group, said benzothiazole being added to said lubricating oil in a small but sufiicient quantity to efiectively inhibit the corrosion of said hard metal alloy bearings.

CLARENCE M. LOANE.