US2371319A

US2371319A - Lubricant

Info

Publication number: US2371319A
Authority: US
Publication date: 1945-03-13
Anticipated expiration: 1962-03-13

Description

Patented Mar. 13, 1945 LUBRICANT William B.- Ross, Evanston, William J. Backofl, Elmhurst, and Norman D. Williams, Chicago, Ill., assignors to The Pure Oil Company. Chicago, 111., a corporation of Ohio No Drawing. Application July 16, 1942,

- Serial No. 451,218

2 Claims.

This invention relates to the problem of inhibiting bearingcorrosion and oil deterioration in internal combustion engines, and is more particularly directed to the use of' a particular'class of compounds as inhibitors in conjunction with mineral lubricating oils for the lubrication of moving parts of an internalcombustion engine.

In recent years alloys such as cadmium-silver, cadmium-silver-copper, cadmium-nickel-copper and copper-lead have been substituted -for babbitt as hearing metals. Although these alloys have mechanical advantages over Babbitt metal, under modern operating conditions they appear to promote oxidation of the lubricating oil, resulting in varnish and sludge formation with attendant. valve and ring sticking. The use of these bearings also is attended with high bearing losses, probably due to corrosion by acids formed by the oxidation of the oil.

Because of the rapid rate of deterioration of lubricating oils and the rapid rate of corrosion of bearings in modern internal combustion engines of the automotive type much research has been conducted on the problem of inhibiting deterioration and corrosion, and a large number of compounds have been developed which-are effective to some extent iii-inhibiting deterioration of the oil and corrosion of the bearings.

We have discovered a class of compounds which exhibit exceptional ability to inhibitdeterioration of "motor oil and corrosion of bearings when used in relatively small quantities.

An object of this invention is to inhibit deterioration of motor oiland to inhibit corrosion of bearings in internal combustion engines? A further object of the invention is to provide a composition of-matter capable of lubricating means for contacting the bearings and other moving parts of the internal combustion engine with an ester or salt of a thio-carbamic acid, in

the presence of mineral lubricating oil. Although the salt or ester of the thio-carbamic acid may be injected into the engine independently of the lubricating oil, we prefer to mix thematerial in small quantities with the lubricating oil prior to adding it to the engine. Although it is not essential that the salt or ester be soluble in the oil, we prefer to use a soluble material in order to insure against separation of the mate-.- rial from the on during use. The invention, however, contemplates the use of salts or esters which are not soluble but which are high] dispersed in and held in suspension in the oi; As

' examples of compounds which are suitable may be mentioned alkyl, aryl and aralkyl esters of mono-thio-carbamic, di thio carbamic, and thio phospho carbamic acids in which hydrogen in 7 stituted by aryl, alkyl,

internal combustion engines containing bearterioration during use.

Further objects of this invention will appear from the following description.

In accordance with our invention we provide or aralkyl radicals. Specific compounds which may be mentioned as examples are benzyl dibutyl dithio carbamate and the butyl ester of dibutyl dithiocarbamic acid.

As examples of salts may be mentioned the alkaline earth metal salts including barium, calcium, strontium and magnesium of mono-thio-car-i.

bamic, di-thio-carbamic and thio-phospho carbamic acids.

Although the aforesaid esters and salts are ef.-,

fectivewhen added to lubricating oil in amourit s as low as 5% by weight and amounts greater g y weight, the preferable rangeis from- .5 to 5% by weight based on the mineral oil.

In order to demonstrate the .emcacy of the thio carbamic acid esters and salts as inhibitors against bearing corrosion and motor oil deterioration, Underwood tests were made using various amounts of benzyl dibutyl'uithio carbamate and butyl ester of dibutyldithio car- -bamate acid in mineral lubricating oil and the bearing materials and their applications, by

A. F. Underwood, Journal of Society of Automotive Engineers, volume 43, pages 385-392, September 1938.

A catalyst consisting of .12% iron naphthenate by weight was added to the oil in each run. This percentage is equivalent to .01% iron as iron oxide. The use of an iron catalyst is standard practice for the Underwood test.

Additive #2=butyl ester dibutyl dithio carbamic acid. Additive #1=benzyl dibutyl dithio carbamate.

sludge were obtained in the following manner:

Naphtha insoluvle (insoluble sludge) Three grams of the oil is mixed in an Erlenmeyer fiask with 100 cc. of A. S. T. M. precipitation naphtha, of the type specified in A. S. T. M. Method D91-35. The oil and naphtha are thoroughly mixed and allowed to stand for three hours. The insoluble matter is then filtered through a tared Gooch porcelain crucible, previously prepared with an asbestos pad 1" thick and dried in an oven at 300 F. for 30 minutes. The insoluble residue is washed with 100 cc. A. S. T. M. naphtha and'dried in an oven at 300 F. for thirty minutes, cooled and weighed. The increase in weight is naphtha insoluble.

chloroform soluble The chloroform soluble is extracted'from the dried and weighed naphtha insoluble residueby pouring successive portions of chloroform through the filter pad using light suction. 100 cc. of chloroform is generally suflicient but the 'extraction should be continued until the filtrate is colorless. .,(With heavy naphtha insoluble residues the chloroform is allowed to stand in the crucible without suction for a few minutes before each portion of the chloroform is drawn through the crucible.)

Theresidue is then dried in an oven at 300 F. for 30 minutes, cooled and weighed. The loss in weight is chloroform soluble. The solubility in chloroform of the residue from the naphtha insoluble determination is affected by the time and temperature of drying. For this reason, in order to secure check results in the chloroform soluble" determination, the drying time and temperature, especially in the naphtha insoluble determination, should be carefully controlled.

It usually happens that in the Underwood test there is no particular difliculty in filtering, re-

gardless of whether the oils contain detergents 'or not. However, when these methods are applied to used crankcase oils it sometimes happens that oils which contain detergents will not give a clear filtrate. Under these conditions, the filtrate is refiltered through a second Gooch filter and Table Per cent by wt. additive .0 3 l 0. 5 Additive No None #1 #1 #1 #1 Hours run 1 l0 l0 10 CuPb loss .0198 0176 0318 0380 AgCd loss .0041 0030 .0045 .0071 Neutralization No 0. 69 0. 61 1. 40 1. 63 Per cent naph. insol. 0. 36 0. 42 0. 45 0. 61 Per cent CHCla sol-.. 2. 88 0. 21 0. 22 0. 29 0. 29 Per cent sol. sludge 8. 35 0. 23 0. 0. 87 1. 49 Per cent S. in blend from additive. 0 l. 085 661 217 1085 000M I S. on

aavns o the deposits from both crucibles added in reporting naphtha insoluble (and chloroform soluble).

Propane insoluble (soluble sludge) The filtrate from the naphtha insoluble is concentrated to 20 cc. by evaporation and is transferred quantitatively to the extraction apparatus described in Industrial 8; Engineering Chemistry April 15, 1939, page 183. The remaining naphtha is now completely removed from the oil sample by evaporation on a steam bath. The propane extraction is carried out as directed in the abovementioned article. The propane insoluble material remaining is calculated in percentage and reported as soluble sludge. I

The data 'in the tables show that benzyl d butyl di thio carbamate was eflective in amount:

' of from .5 to 5% in cutting downbearing lossir both copper lead and silver cadmium bearing: and. that it was effective in these percentages ir improving the neutralization number, the pei 'cent naphtha insoluble, the per cent chloroforir soluble, and the per cent soluble sludge. Th results further show that with respect to thi: particular additive the addition of 5% showec no material benefit over the addition of 3% tr the motor oil.

The table shows that when butyl ester of d butyl thio carbamic acid was used-as the additive the copper-lead bearing loss was worse than wher no additive was used, but in all other respect: the oil was markedly superior to the oil withoul the additive. The results on this particular additive also demonstrate that in general the effectiveness of the 5% additive wasgreater than 3% 'From the foregoing it is apparent that we havl discovered a new class of inhibitors for preventing deterioration of motor oils when, used in internal combustion engines and for inhibitim bearing corrosion in such engines and that WI have discovered a new type of lubricant which i: unusually stable under operating conditions i1 internal combustion engines and which gives eflicient operation of the engine because of the smal amount of acid, sludge and varnish formed.

We claim:

1. A lubricant for internal combustion engine: comprising a mineral lubricating oil and a smal amount, sufilcient to inhibit oxidation of said oi in use, of benzyl dibutyl dithio carbamate.

2. A lubricant in accordance with claim 1 ii which the amount of benzyl dibutyl dithio car baimate is from 0.5 to 5 by weight of the minera o1 WILLIAM B. ROSS; WILLIAM J. BACKOFF.- NORMAN D. WILLIAMS.