US2387323A - Antirusts - Google Patents

Description

'P atente st. 23?, 1945 White and Roger W. Watson, Ohicago, 111., assignors to Standard Oil Company, (Ibicago, 1111.,

a corporation of Indiana 'No Drawing. Application November 8, 1943, Serial No. 509,470

14 Claims.

This invention relates to novel compositions of matter having antirust or anti-corrosion properties and to methods for preventing the development of rust or corrosion in metals.

A wide variety of metals undergo more or less severe corrosion when they are exposed for a prolonged period of time to the action of water, aqueous fluids, steam, air, exhaust gases produced by internal combustion engines or other corrosive agencies.

Corrosion is especially prevalent and severe in ferrous metals, such as iron and non-stainless steels used as structural materials in oil circulation systems wherein purposive mixing or inadvertent contamination of the oil with water and/or steam occurs. Oil circulation systems answering the description given above include steam turbine oil circulation systems, especially in turbines operated at high temperature with high pressure steam, and cooling systems wherein a stream of a hydrocarbon oil is recirculated continuously as a thermophoric medium and wherein water or steam contamination may be prevalent at one or more points in the circuit.

Oils desirable for use in systems wherein contamination by water occurs, e. g. in the lubrication of steam turbine bearings and gears, must be capable of demulsifying entrained water rapidly. One of the standard methods for measuring the emulsifying tendency of oils under service conditions is the Herschel demulsibility test, described in the Bureau of Standards Technologic Paper No. 86 (1917). Water entrained or emulsified in oil reduces its lubricating quality with the consequence that the parts to be lubricated run hotter. Furthermore, the emulsion of water in oil iscorrosive to a variety of metals, including the ferrous metals, and the severity of corrosion increases with increasing temperature. Another consequence of the increased temperature is the increased tendency of the oil to oxidize and form organic acids which, with the water present, corrode the metals exposed thereto, with the resulting production of metal soaps of the organic acids. In turn, the soaps increase the capacity of the oil to emulsify water and air, which makes for an increased rate of corrosion. Furthermore, corrosion tends to produce metallic oxide grits which score bearing surfaces, and asphaltic oil oxidation products which are soluble in the circulating oil stream at high temperatures but which are not appreciably soluble at low temperatures so that they settle out in the cool parts of the oil circuit, resulting in the fouling and plugglng of strainers, tubing and heat exchangers through which the oil stream passes.

It is an object of this invention to provide novel compositions containing an amidoxime. Another object of this invention is to beneficiate various materials by incorporating a small proportion of an amidoxime therein.

An additional object of the present invention is to provide a method of preventing or inhibiting corrosion or rusting of metals by the application thereto of a novel type of antirust agent. Still another object of this invention is to provide novel oil compositions which will effectively inhibit the rusting or corrosion of metal surfaces, especially by water or steam.

A further object of this invention is to provide novel oil compositions adapted to provide prolonged lubrication of metal surfaces exposed to water or steam, while at the same time preventing corrosion of the metal surface being lubricated. These and other objects of our invention will become apparent as the description of our invention proceeds.

Briefly, we have found that metal rusting or corrosion, especially of ferrous metals, such as iron and various steels, can be prevented or inhibited by applying to the metal surface to be protected a novel type of antirust agent. Our invention is especially applicable to the treatment of metals normally in contact with oils,

but which rust due to partial displacement of the oil film from the metal surface by steam, water or corrosive aqueous solutions.

We have discovered that amidoximes, sometimes called oxamidines or hydroxyamidines, are effective antirust agents for metals normally subject to corrosion, especially for ferrous metals. The amidoximes are a class of organic compounds having the general formula N-OH R-L-NH: which is tautomeric with the formula H-N-OH R- =NH In the above general formulas, R can be: hydrogen, or an organic radical, such as Alkyl group: for example, C4H9, CsH1s, CsH17, C11H23-, C13H27, C15H31--, C17Hs5-, etc.,

Alkenyl group: for example, allyl, methallyl, or

oleyl,

Naphthenic or cycloparafiinic: cyclohexyl, methylcyclopentyl, mixtures of naphthenic groups such as are obtainable from petroleum,

Cyclo-olefinic: cyclohexene, methyl cyclohexenes and the like,

Aralkyl: benzyl, naphthomethyl, diphenylmethyl;

An aromatic radical, such as phenyl, naphthyl,

diphenyl, etc. and alkylated aryl groups;

Heterocyclic: thiophene, thiophane, furan,

tetrahydrofurane, pyridine, picolines, piperidine, pyrrol, pyrrolidine, quinoline, quinaldine. etc.

The R group given in the above formulas may contain as substituents a variety of radicals, e. g. halogen, hydroxyl, alkoxyl, aryloxyl, sulfonic, sulfonamide or other sulfur-bearing radicals; nitro, amino, imino, phosphorus containing radicals, etc. We can likewise use amine and ammonia salts of the amidoximes for the purposes of our invention. However, we prefer to use unsubstituted amidoximes.

It is not intended to imply that all amidoximes serve with identical efilciency as antirust or anticorrosion agents. They will exhibit some variation depending on the nature and severity of the service to which they are subjected, the nature of the metal to be inhibited, the relative solubility of the particular amidoxime in the liquid medium which may be used for application of them to the metal surface to be protected, and the relative stability of the amidoxime at the service temperature.

A number of methods is available for the preparation of amidoximes, including:

(1) The reaction between a nitrile and hi;- droxylamine the hydroxylamine may be added to the reaction mixture as a salt and liberated for reaction by the additionof a base to the reaction mixture;

(2) The reaction between a thioamide and hydroxylamine n IYFOH RQ-NH2+NHIOH=R-NHI+HIS (3) 'Ihereaction between an amidine and hydroxylamine The methods given above for the preparation of amidoximes are merely illustrative and form no part of the present invention.

In accordance with our invention, amidoximes can be used in small proportions as antirust or anti-corrosion agents for metals, particularly ferrous metals, in a wide variety of media. Thus, the amidoximes may be added in small proportions, for example, in the range of about 0.001 to about 0.5% by weight, to-

Motor fuels: for example, automobile or aviation gasolines, tractor fuels, Diesel engine fuels, alcohol-containing motor fuels;

Lighting and heating fuels: kerosene, stove oils, stove and lighting naphthas, furnace oils, fuel 0 S;

Solvent naphthas: cleaner naphthas, such as Stoddard solvent, V. M. and P.- naphthas, hydroformed naphthas;

Lubricating and dielectric oils: motor 0115, Diesel oils, aviation engine oils, marine engine lubricants, gear oils, oil field machinery lubricants, ice-machine oils, steam cylinder lubricants, transmission oils. soluble oils, textile oils, cutting oils, turbine oils, insulating oils;

Lubricating greases: stable gel-like or. solid dispersions of metal soaps in hydrocarbon oils;

Protective coatings: slushing oils and greases in which part or all of the hydrocarbon oil may be replaced by metal soaps and/or waxes such as the ester-type waxes, mineral waxes such as petrolatum and paraffin waxes, pitches, tars. asphalt, rosin asemas The amidoximes are useful in preventing rusting of metal parts which are brought into contact with the above oils, waxes, etc., in the presence of water, air, steam or other normally corrosive influences. Thus, in the stora'geof hydrocarbons a water seal is often used in the bottom of the storage tank. In addition the refining of hydrocarbon oils generally results in the intrusion of small proportions of water. Also, the storage and use of hydrocarbon oils generally results in more or less extensive contamination thereof with water. The amidoximes prevent rusting or corrosion of metals, especially ferrous metals, in hydrocarbon oil storage tanks, pipe lines, preheaters, etc.

Amidoximes may also be used as rust inhibitors and for other purposes in vegetable, animal and marine oils; in proportions varying from about 0.005% by weight to about 1% by weight or even more. Also, amidoximes can be added in small proportions to blends of the above t p s of oils with hydrocarbon oils.

The amidoximes may also be used as metal corrosion inhibitors in other media. For example, soluble amidoximes may be used as corrosion inhibitors in engine coolant liquids such as water, aqueous alcohols, slycols and the like.

A preferred class of applications of amidoximes as rusting inhibitors is in viscous highly refined hydrocarbon oils, such as steam turbine oils which are applied in services wherein contamination of the oil with water or steam induces rusting or metal parts, especially ferrous metal parts, encountered by the oil. Steam turbine oils generally have Saybolt Universal viscosities at 100 F. of from about 125 seconds to about 2000 seconds or even higher.

The capacity of turbine oils to form quickbreaking emulsions with water is essential to successful operation; therefore, no addition agent which will result in appreciable reduction of the demulsibility of the oil can be tolerated. In general, from about 0.001 to about 0.5% by weight of an amidoxime is sufllcient to confer adequate rust inhibition to viscous highly refined hydrocarbon oils without sensibly affecting their emulsifying properties.

The following illustrative examples relate to the application of amidoximes as antirust agents in turbine oils. The rusting characteristics of turbine oils containing these additives is demonstrated by the following test: 300 ml. of the oil to be tested are placed in a 400 ml. lipless glass beaker heated to about 167 F. in an oil bath and the oil is stirred by means of a stirrer maintained at about '150 R. P. M. When the temperature of the oil sample reaches about 167 F., a polished test strip of cold-rolled steel is suspended in the oil and stirring continued for 30 minutes to insure complete wetting of the steel specimen. Thirty ml, of distilled water are then carefully added by pouring down the side of the beaker, and stirring is continued for 24 hours. At the end of this time the steel specimen is removed from the beaker, washed with naphtha and inspected visually for the presence of rust. The method of carrying out this test has been described in National Petroleum News, Section 2, Volume 34, No. 30 (July 29, 1942) page R-216, except that the test temperature therein recommended is about F. instead of 167 F. and the duration of the test is 48 hours instead of 24 hours as in our tests.

The test pieces are rated numerically 1 to 5 according to increasing amounts of corrosion. A

rating of l is given to test pieces showing no rust or discoloration; a rating of is given to'severely rusted pieces resulting from tests on uninhibited oils.

In the following examples the control is a technical white oil having a viscosity of 145 seconds Saybolt Universal at 100 F. produced by treating a lubricating oil distillate with about 6 lbs. of

104.5% sulfuric acid per gallon of distillate, and normally used for steam turbine gear and bearing lubrication. All percentages are by weight based on the total composition.

In Example 4, above, the naphthenamidoximes were prepared from commercial mixed petroleum naphthenic acid.

Napthentic acids are complex mixtures of carboxylic acids which occur naturally in various crude petroleum oils, usually in proportions below 1 per cent, and may be extracted therefrom by the use of alkalies. Extensive research has demonstrated that petroleum naphthenic acids fall into at least three general categories; (1) allphatic acids having the general formula CnHZnOB and predominating in compounds wherein 11. is 6 or 7, (2) acids having the general formula CnHEn-QOB and shown to be cyclopentane derivatives C5H9' (CH2)=CO2H, where a: generally varies from 1 to about 4 and wherein the cyclo pentane ring may also contain one or more alkyl groups, (3) acids having the general formula cnH2n402, known to contain a bicyclic cycloaliphatic nucleus and containing about 12 to about 25 carbon atoms. The above classification presents a somewhat over-simplified picture. Some evidence has been adduced of the existence of even more complex acids in petroleum naphthenic acids, including triand tetra-cyclic cycloaliphatic-substituted aliphatic carboxylic acids.-

There is evidence that the molecular weights in the above classes overlap; thus, although the simple aliphatic acids predominate in Co or C1, small proportions of higher molecular weight fatty acids also occur and overlap into the molecular weights and boiling ranges of compounds falling into categories (2) and (3) above. Naphthenic acids obtained from different crudes and from various fractions of the same crude oil generally differ from each other somewhat in composition and character.

The naphthenamidoximes of Example 4 were prepared by converting the napthenic acids to the corresponding mixture of amides, dehydrating the amides to produce a mixture of nitriles and reacting the nitriles with a salt of hydroxylamine in the presence of a base.

Example 5 describes the use of an aryloxy alkyl amidoxime as an antitrust agent in a turbine oil.

In the above examples, it was found that the emulsifying characteristics of the control were substantially unchanged by the addition of the amidoximes, as revealed by the Herschel Demulsibility Test.

Although a wide variety of amidoximes can be used to confer rust preventive properties upon hydrocarbon oils, we prefer to use a mixture of naphthenamidoximes, such as are derivable from petroleum naphthenic acids. The naphthenamidoximes appear to confer somewhat improved protection, as compared with other amidoximea;

this improvement appears to be due, at least in 1 corrosion. For example, the amidoximes may be used in combination with about 10 to about by weight, based on the amidoxime, of hydroxylamine, hydroxamic acids, preferably naphthenhydroxamic acids, alkylamine salts of organic acids, e. g. amylamine salts of mahogany acids and the like.

The oils in which the amidoximes are usedmay, in addition, contain V. I. improvers, viscosity-increasing agents, bloom-producing agents, extreme pressure agents, antioxidants, dyes, and antiknock agents, as the case may be, provided only that these additional agents do not enter into appreciable chemical reaction with the amidoximes or precipitate them from the oils towhich they have been added.

Thus in turbine oils, we can, in addition to an amidoxime, add an antioxidant such as the polyhydric phenols and their alkyl derivatives, for example catechol, tertiary butyl catechol, octyl catechol. Other efiective antioxidants include beta-naphthol, amyl beta-naphthol, octyl betanaphthol, lauryl beta-naphthol, alpha-naphthol, amyl alpha-naphthol, N-phenyl alpha-naphthylamine, di-aJpha-naphthylamine and the like. The antioxidant may suitably be used in a proportion in the range of about 0.001 to about 0.25% by weight based on the oil.

We claim:

1. A composition of matter comprising a major proportion of an oil and a minor, corrosion-inhibiting proportion of an amidoxime.

2. A com-position of matter comprising a major proportion of a hydrocarbon oil and a minor, corrosion-inhibiting proportion of an amidoxime.

3. A composition of matter comprising a major proportion of a hydrocarbon oil and a minor, corrosion-inhibiting proportion of an amidoxime having the formula wherein R is an organic radical.

lIF-O R-C-NHa.

wherein R is an alkyl radical.

5. A composition of matter comprising a major proportion of a hydrocarbon oil-and a minor, corrosion-inhibiting proportion of an amidoxime having the formula N-OH R-E-NH, wherein R is an alkyl radical containing an aryloxyl radical as a substituent.

6. A composition of matter comprising a major proportion of a hydrocarbon oil and a minor, corrosion-inhibiting proportion of an amidoxime having the formula 1 x-on B-C-NH:

wherein R is an aromatic radical.

'7. A composition of matter comprising a major proportion of a hydrocarbon oil and a minor, corrosion inhibiting proportion of an amidoxime having the formula Ill-OH n-c-Nm wherein R is a naphthenic radical.

8. A composition of matter comprising a major proportion of a hydrocarbon oil and a. minor, corrosion inhibiting proportion of lauramidoxime.

9. A composition of matter comprising a major proportion of a hydrocarbon oil and a minor,

the presence of water in systems susceptible to corrosion by said water. comprising a major proportion of an oil and a minor. corrosion inhibiting proportion of an amidoxime having the formula ic-on wherein R is an alkyl radical.

12. A rust inhibiting oil composition for use in the presence of water in systems containing metal susceptible to corrosion bysaid water, comprising a major proportion 01' an oil and a minor, corrosion inhibiting proportion of an amidoxim having the formula lax-on B-C-NH: wherein R is an aromatic radical.

13. A rust inhibiting oil composition for use in v the presence of water in systems containing metal susceptible to corrosion by said water, comprising a major proportion of an oil and a minor, corrosion inhibiting proportion of an amidoxime having the formula n-c-mn wherein R is a naphthenic radical.

14.-. A composition of matter comprising a major proportion of 9, non-gaseous hydrocarbon and a minor, corrosion-inhibiting proportion of an amidoxime.

JAMES w. GAYNORH cLARoN N. WHITE. ROGER w. WATSON.