US2351380A - Anti-ring-sticking lubricant - Google Patents

Description

ljatented June 13, 1944 I A UNITED STATES PATENT osnca ANTI-RING-STICKIN G LUBRICANT Ellis R. White, Albany, Calif., asslgnor to Shell Development Company, San Francisco, Calif., "a corporation of Delaware No Drawing. Application April 13, 1942,

Serial No. 438,726

10 Claims.

This application is a continuation-in-part of my co-pending application, Serialv No. 374,201, filed January 13, 1941.

This invention is related to improved lubricating oils, and more particularly deals with mineral lubricating oils containing dissolved therein one should expect, 1. e., cases-are known in which, for example, a lubricating oil containing the combination of an oil-soluble detergent salt and small amounts of oil-soluble aluminum salts of,

alpha-aromatic amino monocarboxylic acids capable of reducing ringsticking tendencies of the oil.

It is well known that in Diesel engines in particular pistonrings have a tendency to become stuck due to an accumulation of coke in the ring rooves. It is also known that the addition of oil-soluble detergents to the lubricating oil does 1n many instances reduce or even prevent such ringsticking. A class of detergents most active for this purpose comprises oil-soluble metal salts oi carboxylic and sulfonic acids,'such as soaps ofiatty acids, chlorinated fatty acids, aromatic fatgagcids, naphthenic acids, rosin acids, parafiin carboxylic acids (produced by oxidation of paraiiln wax), mahogany acids, alkyl derivatives of benzolc or hydroxy benzoic acids and many others. Salts of polyvalent metals are in gen- I efal most active, e. g.,' of Mg,

Ca, Sr, Ba, Zn, Cd, Al, Sn, Sb, Cr, Mn, Co, Ni, etc.

The addition of oil-soluble salts tolubricating oils in efiective amounts, e. g., in amounts ranging from about ..25% to 5.0%, however, in-- troduces at the sametime a number of difiiculties, one of the most serious of which is bearing corrosive but acquire induced corrosiveness, i. e.,

turn'corrosiveupon use under the ordinary lubricating conditions that are encountered in internal combustion engines. In some instances corrosion has been reduced, though not usually altogether overcome, by the addition of various auxiliary agents, such as 'anti-omdants, anticorrosives, etc. In this connection, it should be observed that. in some instances the addition of auxiliary agents has an effect contrary to what 55 than one oleiinic double bond.

a proven commercial anti-corrosive are more corrosive than the same oil containing the salt alone.

It is a purpose of this invention to produce relatively non-corrosive lubricating oils suitable 'for internal combustion engines containing a dissolved detergent soap. It is another purpose to produce improved oil-soluble detergent salts, which salts. when dissolved in mineral lubricating oils, combine an extraordinary degree of detergency with but little corroslveness.

I have discovered that relatively non-corrosive lubricating oils of high'detergency are produced by dissolving therein an oil-soluble aluminum salt of alpha-aromatic amino monocarboxylic acid of the general formula Ra RI N+COO)AI(OH)1J R1 R4 I wherein R1 is an aromatic hydrocarbon radical and R: and Rs are hydrogen or hydrocarbon radicals and R4 is a hydrocarbon radical, the total number of carbon atoms being such to result in an oil-soluble salt; and 3+1! equals 3, a: being at least 1. As a general rule, not less than 16, and preferably 20 or more carbon'atoms are required in the acid to confer oil-solubility on the aluminum salt. The presence of naphthenic rings alpha amine radicalmay be secondary or tertiary.

often results in greater solubility for a given number of carbon atoms. If desired, the R radicals may contain relatively stable polar substitution radicals, such as halogen, hydroxyl,

ether, hydrosulfide, sulfide, amine, imine, nitror,

nitro,, carboxylic ester, carboxyl, phosphorus,

phosphite, phosphate, thiophosphate, arsine, etc.

To be suitable forlubrication the acids should be relatively resistant to oxidation and therefore should not contain more than one olefinic double bond.

As may be seen from the above formula, the

Among the acids meeting the above requirements are several which are particularly useful, e. g.,"alpha-anilino, -toluidino, -pyridino, -methyl aniline, etc.. fatty acids, naphthenic acids or bon'atoms and wherein the fatty acid chaincontains at least 14 carbon atoms and not'more p'araffln carboxylic acids totaling 22 ormore car- .radical.

Thus acids of the following formulae among the preferred:

cimcm) ..cn-c on are A-on-cn j cH(cm),-cH-co0n A-CH- I n at 1Paraflln wax radical-OH-C 0 0H In these formulae, is an integer of at least 12, a: iszero or an integer greater than zero, R1 is an aromatic hydrocarbon radical probably mononuclear, and R2 is hydrogen or a hydrocar- The A radicals are hydrogen or albon radical. v kyl radicals (such as are contained in naphthenic acids naturally occurring inv petroleum oils).

Among the useful amino radicals are the'foilowing:

N-n- 1-4.. --Nn-' (A)= NH U Q (A); l-(A).

Aluminum salts of the alpha aromatic amino monocarboxylic acidsof this invention have the amino monocarboxylic acid is then converted to the metal salt by any conventional method. Thus, it may be' directly reacted with an oxide or hydroxide of aluminum, or its alkali metal salt may first be formed which is thien double-decomposed with a suitable salt containingaluminum.

As already stated, aluminum salts of alphaaromatic amino monocarboxylic acids are less corrosive than the same salt of corresponding acids not containingthe amino radical or containing an amino radical in a position other than the alpha position. While I do not wish to be bound by my theory, I believe that the following is explanation for the improved behavior. It apthe .chelate (inner ring) and the non-chelate form. The latter ionizes,'but the former does not. Thus the equilibrium may be illustrated as advantage of being more oleophilic than the corresponding salts of acids not having the amino many of the readily available detergents, such as This is of considerable advantage, as

the polyvalent metal soaps of ordinary fatty acids, e. g., lauric, palmitic, stearic, arachic, .behenic,

etc., acids form unstable solutionsin hydrocarbon oils,these soaps tending to precipitate from their solutions in the oils upon standing at ordinary room temperatures, thereby forming gels.

4 An: alpha-aromatic amino .monocarboxylic acid may be produced, for example, by starting with able alkyl halide containing say, 16 ormore carbon atoms such as chlorinated: paraflinwametc.

Another method for producingalpha-aromatic amino monocarbox'ylic acids comprises halogenating aliphatic carboxylic acids under conditions tointroduce at least one halogen atomin alpha position to the carboxyl radical. This may be accomplished by the Hell Volkard Zelinsky reaction (see Meyer and Jacobsen, vol. 1, part 2, page4'l9) whereby an alpha halo acid halideis produced;

This product is then hydrolyzed to liberate the alpha halo carboxylic acid. This acid is then simply heated, if necessary under pressure, with an aromatic amine. The freealpha-aromatic amount of ionized detergent salts display substan 1 tially as great dispersive action as larger amounts,

toluidino acetic acid and reacting it with a suit- )a= I n 0 \N' =01); an); f db: )1 V )l Ohelate iorm Ionized form If a chelate form is the preferred-one, relatively'few ions can form, and the corrosion is accordingly reduced. Simultaneously, however.

one would expect a similar reduction in detergent properties, becauseyas far as known, it is the ionized portion of the salt which is responsible for the detergent eflect. This is believed to be However, salts due to the fact that certain definite but small I while the corrosive property is more nearly proportional to the amounts of ions present. I Thus, from the point of view of detergency of the oil,

. it is only necessary to have in the oil at any one time the minimum'flamounts of active ionswhich are just sufllcient to disperse whatever sludge or sludge-like materials happen to" be contained in the oil at that moment. As the dispersion pro'- ceeds, these minimum amounts are used up and the oil would be left unprotected, unless 'newactive ions are introduced. Due to the 'presence'of relativelylarg'e, amounts of inactive non-deter- ,gent cheiates, eflectivequantities of these ions are quickly restcred, and thus continued detergency of the oil is assured. 1

' Concerning the equilibrium between the chelate and the non-chelate forms-of the normal and 2,so1,aso

asic salts, it appears that in the case of the nor- .mal. salt the chelate is preferred whereas in the asic salt the ionized form exists to a greater exent. As a result, it has been found that the normal salts of the alpha amino acids are even fess corrosive than the basic ones, whereas it was .ieretoiore believed necessary that to suppress corrosiveness one must employ the basic salts.

The above peculiar reversal of the rate of corrosiveness as afiected by alkalinity in the case after the test, the difiference in the weight representing the loss, sustained during the test.

of the alpha amino salts is of considerable im- 4 portance. One of the main causes for the type of corrosiveness which is induced upon the use of the oils containing detergent salts is believed to reside in a gradual reduction of the alkalinity bf the salt with a commensurate decrease in the pH value due to oxidation. In the case of my alpha amino salts, however, the transition from the basic to the normal salt has just the opposite effect, corrosion decreasing for reasons pointed out above, rather than increasing,

In the normal salts of some of the alpha amino acids the equilibrium in favor of the chelates is so pronounced that the amount of detergentactive ions formed may be less than the minimum required for truly satisfactory detergency. In such cases it may be desirable to use a basic salt or a mixture of normal and basic salts so as to result in an oil solution containing the required minimum amount of ions; or a mixture of a normal alpha aromatic amino monoca-rboxylic acid salt with a detergent salt; which is not subject to chelate formation, such as an ordinary oil-soluble naphthenate, sulfonate, aromatic fatty acid salt, paraffin wax carboxylic acid salt, etc., may be employed.

The following example serve to illustrate my invention: Stearic acid was brominated by the Hell Volhard Zelinsky reaction under conditions to insure complete conversion of all the stearic acid to the corresponding alpha bromo acid bromide. The resulting product was hydrolized with warm water, and the bromo acid thereby obtained was dried by solution in isopentane and subsequent crystallization. The alpha brom stearlc acid, which had a melting point of 60 0., was then heated with two equivalents of otoluidine for one hour at 12 -l50 C. At this point, all of the bromide was determinable with silver'nitrate.

The product was cooled, filtered from toluidino hydrobromide and crystalized from glacial acetic acid.

The above product was reacted with ammonium hydroxide in alcohol solution to form the ammonium salt. The alcohol solution of this salt was then mixed with an alcohol solution of alumimun hydroxide, the mol ratio of acid to aluminum being 3 to 1, until a precipitate formed. The filtered and dried precipitate was a rubbery substance which readily dissolved in hot oil.

A solution of 1.7% by weight of this material 7 in an S. A. E. 30 mineral lubricating oil was produced. The resulting blended lubricating oil was tested, and is compared in the table below with two recognized detergent salts for Diesel lubricating oils for corrosiveness and detergency.

In the corrosion test a hardenedsteel disc is made to rotate for 20 hours under constant pressure against 3 copper lead alloy bearings. The bearing assembly rests in a welded steel cup and is covered with the oil to be tested. During the test the temperature of the 'oil is maintained at 107 C. The bearings are weighed before and The detergency is measured by filtering a suspension of carbon black under standard conditrons through a column placed in a glass tube, which column consists of 1 cm. layers of a sand separated from each other by pieces of filter paper. As the oil filters through this column,

the carbon black is gradually filtered out and bev6-8, and in exceptional cases to 9 or 10.

Corrosion hearbig loss. rug/sq. cm. Detergency 1.7% aluminum a-toluidino stearate+ 25% phwylalphanaphthylamina. 1 0

In addition to the detergents of this invention, the lubricating oils may contain conventional oxidation inhibitors or retarders, anti-corrosives, extreme pressure agents, particularly those containing at least one of the elements S, Cl and P in relatively stable form, so as not to cause corrosion, blooming agents, dyes, etc. The amounts of the detergent required to retard or 'prevent ringsticking normally varies between about 25% and 5% and preferably from to 2.5% by weight of the oil.

I claim as my invention:

1. Lubricating oil comprising a mineral lubricating oil and dissolved at small amount of an oil-soluble aluminum salt of an alpha-aromatic amino monocarboxylic acid which contains a sufficient number of carbon atoms in the acid to make said salt oil-soluble and which is resistant to oxidation under normal lubricating conditions in internal combustion engines said amount being suificient to reduce ringsticking.

2. Lubricating ofl comprisin a mineral lubricating oil and dissolved a small amount of an oil-soluble aluminum salt of an alpha-aromatic amino monocarboxylic acid which contains a sufficient number of carbon atoms in the acid to make said salt oil-soluble and which is resistant to oxidation under normal lubricating conditions in internal combustion engines, the amino radical of said acid being a secondary amino radical said amount being suilicient to reduce ringsticking.

3. Lubricating oil comprising amineral lubricating oil and dissolved a small amount of an oil-soluble aluminum salt of an alpha-aromatic amino monocarboxylic acid which contains a sufficient number of carbon atoms in the acid to make said salt oil-soluble and which is resistant to oxidation under normal lubricating conditions in internal combustion engines, the amino radical of said acid being a tertiary amino radical said amount being sumcient to reduce ringsticking.

4. Lubricating oil comprising a mineral lubrimake said saltoil-soluble and which is resistant tooxidation under normal lubricating conditions in'internal combustion en nes.

5; Lubricating oil comprising a mineral lubri- -cating oil and dissolved a smaliamount of an oil-soluble aluminum salt of an alpha-aromatic amino fatty acid having at least 14 carbon atoms in the fatty acid chainand not more than a single olefinic double bond said amount being sumcient to reduce ringsticking. v v 6. Lubricating oil' comprising a mineral lubricating oil and dissolved a small amount of an oil-soluble aluminum salt of a'monocarboxylic acid having not more than one olefinic' double bond and having the formula:

- -coo Al(0H)' wherein R1 is an aromatic hydrocarbon radical,

R: and R3 are hydrogen or hydrocarbon radicals, and R4 is a hydrocarbon radical, the total number of carbon atoms being such to result in an oil-soluble salt, and :c+u'equais 3, aiming at least 1 said amount being sufllcient to reduce ringsticking;

'7. Lubricating oil comprising a mineral oil and dissolved a small amount of an oil-soluble alu I minum salt of an alpha-aromatic amino paraflin wax monocarboxylic acid of at least 22 carbon atoms said amount being suflicient to reduce ring sticking.

'8. Lubricating oil comprising a mineral lubrieating oil and dissolved a small amount of an oil-soluble aluminum salt of an alpha-aromatic amino paraffin wax monocarboxylic acid said amount being sumcient to reduce ringsticking.

9. Lubricating oil comprising a mineral lubrieating oil and dissolved a small amount of an oil-soluble aluminum salt of an alpha-aromatic amino fatty acid ofat least 16 carbon atoms and having not more than a single olefinicdouble bond said amount being suflicient to reduce ringsticking. v 10. Lubricating oil comprising a mineral lubricating oil and dissolved a small amount of aluminum alpha toluidino stearate said amount being sufficient to reduce ringsticking. I

A ELLIS R. WHITE.