US3909215A

US3909215A - Rust inhibitors for hydrocarbon fuels

Info

Publication number: US3909215A
Application number: US345402A
Authority: US
Inventors: Louis R Kray
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1973-03-27
Filing date: 1973-03-27
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30

Abstract

A novel rust inhibitor mixture for use in hydrocarbon fuels comprising an Alpha -olefin-maleimide copolymer and a hydrocarbyl amine, amide or imidazoline is disclosed. A method of inhibiting rust in fuel oils is also disclosed.

Description

United States Patent 1191 Kray [ 1 Sept. 30, 1975 RUST INHIBITORS FOR HYDROCARBON FUELS [75] Inventor: Louis R. Kray, Novato, Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: Mar. 27, 1973 [21] Appl. No.: 345,402

[52] US. Cl. 44/62; 44/63; 252/405 [51] Int. Cl. CIOL 1/14 [58] Field of Search 44/62, 63; 252/405 [56] References Cited UNITED STATES PATENTS 4/1968 Limlstrom 44/62 11/1968 Mchmcdbasich 44/62 Otto et a1 44/63 X 3,459.518 8/1969 Mehmedbasich. 44/63 3,470,098 9/1969 OHalloran 44/63 X 3.658,495 4/1972 Dorer r l l 44/63 3.723.460 3/1973 Brannon et a1. 44/63 X Primary E.\aminerPaul F. Shaver Attorney, Agent, or Firm-G. F. Magdeburger; C. J. Tonkin 5 7 ABSTRACT 13 Claims, No Drawings RUST INHIBITORS FOR HYDROCARBON FUELS DESCRIPTION OF THE INVENTION This invention relates to a rust inhibitor composition and more particularly to an improved rust inhibiting composition for use in petroleum oils.

In the handling of hydrocarbon fuel oils, especially heating and furnace oils, it is frequently necessary to store the liquids for a considerable period. In the colder northern regions of the United States, home owners often store several months supply of heating or furnace oil in iron tanks. Small amountsof water inevitably derive access to the tank and form a thin film or water layer at the bottom of the tank. In the coastal regions, a great number of these tanks also tend to collect salt water thereby compounding the problems.

As a result of the presence of water in the metal ves- I sels, rusting or corrosion of the areas contacted by the water occurs. The rust formation is caused by both long cell and local cell corrosion with long cell corrosion being accentuated in the salt water environment. If the rusting processes are not checked, the tank will eventually develop weak or thin spots with ensuing leakage.

The formation of rust can be suppressed by adding a conventional water-soluble rust inhibitor to the system. Typical of these rust inhibitors include dichromate solutions, sodium nitrite pellets, water soluble amines,

etc.

These conventional inhibitors are effective in suppressing rust formation in the tank, but are burdened by several ancillary problems caused in part by the inhibitor in the application procedure. For examples, the inhibitors must be added to each tank by the tank owner. In the case of residential heating oil tanks, the home owner is often responsible for its addition which is often overlooked or forgotten. Another problem is that many of the additives cause in-line nozzles to become plugged. Typical nozzles which are often effected are those employed in-residential heating oil furnaces. Another problem is the adverse effect of these conventional inhibitors on the stability of the hydrocarbon fuel or other additives present therein, thereby causing precipitates to form within the liquid solution. In many instances, these precipitates are sufficient to cause blockage of in-line filters.

It is therefore an object of this invention to provide an improved rust inhibitor.

It is another object of this invention to provide an improved rust inhibitor for hydrocarbon fuels which does not cause precipitates within the fuel.

It is another object of this invention to provide a hydrocarbon fuel containing an improved rust inhibitor.

It is an additiona'lobject ofthis invention to provide a method for inhibiting rust.

Other and related objects of this invention will become apparent from the following description thereof and accompanying claims.

SUMMARY OF THE INVENTION The aforementioned objects and their attendant advantages are realized by adding to an oleophilic organic liquid 21 small amount of a mixture comprising l) a co polymer of an alpha-olefin having from 8 to 30 carbons and an N-substituted maleimide wherein the N- substituents onthe maleimides are organic radicals free of aromatic groups and having from 3 to 60 carbon atoms and from l to 5 amine nitrogens, and where the copolymer has from 4,to 20 repeating olefin-maleimide units, and (2) ahydrocarbyl amine, amide, imidazoline or mixtures thereof having from 3 to 60 carbons and from 1 to 10 nitrogen atoms with a carbon to nitrogen atomic ratio from 5 to 30: l. The ratio of the copolymer to the hydrocarbyl amine, amide or imidazoline generally varies within the range of 10 to 0.75 parts of copolymer per part of hydrocarbyl amine.

The above-defined rust inhibitor mixture is soluble within the oleophilic organic liquid and does not cause the organic liquid to become unstable or form precipitates. Also, the inhibitor mixture may be blended with the organic liquid prior to being transported and stored. In this embodiment a rust inhibitor does not have to be extraneously added to the organic liquid in each tank. The inhibitor mixture also does not induce nozzle plugging problems, and accordingly, may be successfully employed in heating oils without plugging the furnace jets.

Although the exact mechanism of the two components of the inhibitor mixture in effecting rust inhibi tion is not known, it is known that the components combine in a synergistic manner to effect superior rust inhibition over either component individually and over no additive.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the practice of this invention, improved rust inhibition can be realized with an oleophilic organic liquid by admixing with the liquid from 0.005 to 1 weight percent of an olefin-maleimide copolymer, more particularly defined hereinafter, and from 0.01 to 0.02 weight percent of a hydrocarbyl amine, amide, or imidazoline also defined hereinafter.

a-OLEFIN-MALEIMIDE COPOLYMER The oz-olefin-maleimide copolymers which may be employed in the practice of this invention are oil soluble alternating copolymers of N-substituted maleimides and aliphatic a-olefins of from 8 to 30 carbons. The copolymers have an average of 4 to 20 maleimide groups per molecule. That is, a succinimide group alternates with an alkyl substituted ethylene. The substituents on the nitrogen of the maleimide may be the same or different and are organic radicals composed essentially of carbon, hydrogen and nitrogen having a total of 3 to 60 carbon atoms and from I to 5 amine nitrogen atoms.

wherein A is "an organic radical of 3 to '60 'carbo'n atoms, more'usu'ally from 3 to 30 carbon atoms having from 1 to'S amine nitro'gens and freeof "aromatic unsaturation. The'symbol Aincludesaininoalkyl; polyalkyl- 1 erably from 6 to 16. The :symbol Y represents the -terv -minal end of the-chain and may be hydrogen, an ole-. finic group (CH=CHR) or One subgenus within the scope of the invention has i V the following formula wherein T is aminohydrocarbyl free of aromatic unsaturation, generally of S to 26 carbon atoms (aminohydrocarbyl free of aromatic unsaturation is a monovalent organic radical composed'essentlally of carbon,;

hydrogen and one nitrogen, wherein the nitrogen is v present only as primary, secondary or tertiary amines,

' and the radical is aliphatic, alicyclicor heterocyclichaving nitrogen as its only annular heteroatom); R is an alkyl radical of to 28 carbon'atoms', preferably of 8 to carbonat o'ms, n is an'integer from '4 to 20', more 'iis'ually from 6 to 16'. Yis defined supra.

diethylaminobutyl, N-abietyl 20 bo'n atoms,"- an d I1 is an'integer from 4 to 20, more usually from 6 to l6. Y is defined supra.

While, usually, the. alkylene polyamines will be unsubstituted, ifdesired, substituted alkylene polyamines may be used having from :1 to 2 aliphatic hydrocarbyl substituents "on'the nitrogen atoms.

The remaining 2 Valences of the polymer may be satisfied in a variety of ways; One or bothof-the valences may be satisfied by arad-ical derived from the polymer initiator; The polymeric chain may terminate by transfer,- coupling 'or disproportionation, resulting in end groups of hydrogen, alkyl groups, alkenyl groups, succinimideor maleyl groups or radicals derived from the initiator.

. illustrative of ,va-rious aminohydrocarbyl radicals are aminohexyl,- aminodecyl', aminooctadecyl, N- hexylaminohexyl; 'N-dec-lylaminopropyl, N- hexadecylaminohexyl, N-hexylpyrrolidinyl, N,N- 3-aminopropyl, N- dihydroabietyl 2-aminoethyl,- etc.

lllustrativeof various alkylene amine and polyalkylene polyamine radicals are; tetraethylenyl tetramine,

triethylenyl triamine, diethylenyl diarnine, dipropenyl diarnine,'tripropenyl triamine, ,etc.

A-particularly preferred group of compounds have repeating units of the, formula:

'wherein R is'an 'alkyl radical from 8 to' 20 carbon atoms, in i's an'in't'eger from 2 to 3,C indicates an ali- 'pha'tic'hydrocarbon radical having x number of carbon atoms 'whe'rein x is an integer from-8 to 20, i.e., C and If is an integer from 6 'tol 6.-*The aliphatic radical "may be straight chain or branched, free of aliphatic un- The particularly preferred compositions of the aminohydrocarbyl substituted compounds are those wherein the arninohydrocarbyl group is aliphatic of 5 to 26 carbonatomsiha'ving one secondary nitrogen atom separated by not more than'6 carbonatoms' from the succinimide nitrogen. The nitrogen atom maybe part of the chain or may be pendant from the chain.

The polyalkylene amine compositions will havethe' following formula:

wherein B and B are alkylene of 2 to 6 carbon atoms,

more usually from 2m 3 carbon atoms, m is an integer from 0 to 4, usually'from 0 to 3, R is an alkyl radical from 6 to 28 carbon atoms, preferably from 8 to 20 carsaturation or unsaturated, particularly olefinically unsaturated. Y is defined supra.

' illustrative-of the particularly preferred substituents on the succinimide nitrogen are .N-octyl 3- amino'propyl, -N-decyl, Z-aminoethyl, N-dodecyl 2- aminoethyl, N-hexadecenyl 2-aminoethyl, -N- octadecenyl 3;-aminopropyl, N-tetrapropenyl 2- aminoethyl, N-octadecadienyl 2-aminoethyl, N- hexadecenyl' '3-aminopropyl, N-octadecyl 3- aminopropyl, N-oct-adecenyl Z-aminoethyl, etc.

i The compounds of this invention are readily prepared by copolymerizing an aliphatic l -olefin-from 8 to 30 carbon atoms with maleic anhydride by means of free radical catalysis and then combining the resulting polymer. with-the desired amine at elevated temperatures to form the alternating N-substituted polysuccinimide. I

The-copolymeriiation'of maleic anhydride with ali- ,phatic l-olefins is well known in the art. See, for example, U.S.Y-Pat. No.'3.()5l,562.

r Theolefinswhich find use include clecene, dodecene,

tetradecene, hexadecene, octadecene, eicosene, docosene, tetracosene, hexacosene, octacosene, triacontene, tridecene, pentadecene, heptadecene. nonadecene, tetrapropylene. tetraisobutyl ene, hexapropylene,

etc. Preferably, a mixture of olefins will be used rather than a single olefin.When using mixed olefins, superior fuel solubility is obtained. The mixture will generally have not more than 50 per cent of any single olefin, and

preferably not more than 30 mole per cent of any single olefin.

The free radical catalyst may be any organic com pound which ata temperature in the range of 50 to 4 100C. decomposes to form free radicals which may then initiate the polymeric chain, although temperatures outside this range maybe used advantageously under some conditions. The most popular organic free radical agents are the peroxidic droperoxide, dihydrocarbyl peroxide, and diacyl perioxide-and azo compounds. Illustrative of hydroperoxide catalysts are cumyl hydroperoxide, pinane hydroperoxide, tert.-butyl hydroperoxide, p-methane hydroinitiators-hyperoxide, etc. Illustrative of dihydrocarbyl peroxides-- 1:1. The ratio of olefin to catalyst will generally be l:0.005O.l mole ratio, more usually 1:0.01O.1 mole ratio.

As already indicated, the temperatures will depend upon the catalyst. Temperatures in the range of 50 to 100C. may be used; more usually the temperature will be in the range of about 75 to 95C. The time for the reaction will depend on the catalyst used, the amount of material, and the other variables. Generally, at least one hour will be required, and usually the reaction will not be carried out for more than a period of 24 hours.

Depending on the amount of the materials, the catalyst may be added in a single addition or in aliquot por tions during the course'of'the reaction, maintaining a relatively constant concentration of free radicals in the reaction mixture.

The reaction of the copolymer with the relevant amine is readily carried out by combining the copolymer with the amine in an inert hydrocarbon solvent at elevated temperatures (50150C.) and removing the water as formed. Preferably, an aromatic hydrocarbon solvent is used which allows for azeotroping the water. When the stoichiometric amount of water has been obtained, the reaction is stopped.

HYDROCARBYL AMINE, AMIDE OR IMIDAZOLINE COMPONENT The hydrocarbyl amine, amide or imidazoline which constitutes the second required component of the claimed invention are oil soluble and have a total of 5 to 60 carbons, preferably from 12 to 30 carbons, and

from 1 to nitrogens, preferably from 1 to 5 nitro gens, and most preferably from 2 to 4 nitrogens. The atomic ratio of carbon to nitrogen in these compounds may vary between about 5 and 30 carbons per nitrogen,

and preferably from 5 to :1. I-Iydrocarbyl amines are preferred andmay be primary, secondary, tertiary, or combinations thereof.

The hydrocarbyl portion of the hydrocarbyl amine, amide'or imidazoline as employed herein, is a hydrocarbon radical composed essentially of hydrogen and carbon and may be aliphatic, aromatic, alicyclic, or

combinations'thereof; e.g., aralkyl, alkyl, aryl, cycloal kyl, alkyl'cycloalkyl, etc. ,.and. may be saturated or ethylenically unsaturated (one or more double bonded carbon pairs conjugated or non-conjugated).

Exemplary hydrocarbyl amines,.amides and imidazo- 1 lines, as maybe employed herein, include those with the following general formulae:

R, is a'hydrocarbyl having from 8 to 24 carbons, and i preferably'frorn 12 to 20 carbons;

R is the same or different univalent radical selectedfrom hydrogen, R,,OII, and R NH ,and preferably hydrogen; p is an integer from Oto 4, and preferably from I to "agand I Exemplary compounds falling within the definition of Formula I' include octylamine, laurylamine, oleylamine,

N-p'ropyloleylamine, N,N'-di (ethanol)oleylamine, N

(aminoethyl)-N-(aminopropyl)oleylamine, laurylacetamide, N- oleylacetamide, etc.

Compounds falling within the scope of Formula II include N-oleyl ethylene diamine, N-lauryl ethylene diamine, N-octyl trimethylene diamine, N-oleyl-2- aminoethyl ethylene diamine, N-lauryl diethylene triamine, N-oleyl-1,2-propylene diamine, N-oleyl triethylene tetramine, N-oleyl tetraethylene pentamine, N oleyl-N,N'-dimethylpropylene diamine, N-oleyl- N,N',N-trimethyl diethylene triamine, etc.

Compounds falling within the scope of Formula Ill include lauryl ethyl imidazoline, oleyl ethylol imidazoline, etc.

' OTHER COMPONENTS In addition to the aforementioned rust inhibitor components, other additives may be incorporated into the oleophilic liquid Without adversely affecting the superior rust inhibiting properties. One type of additive is a demulsifi'er. When the :rust inhibitor mixture is combined with the oleophilic, the combined solution becomes more susceptible to emulsify water. Thus, a part of the water present in storage tanks and vessels containing the oleophilic liquid, is emulsified within the liquid and transported from place to place with the oleophilic liquid. A demulsifier is therefore often advantageously employed to restore and to comprise the water tolerance properties of the oleophilic liquid.

Exemplary demulsifiers which may be employed in the practice of the claimed invention include poly(alkylphenol) formaldehyde condensates and the polyalkyleneoxy modified reaction products thereof. These compounds are prepared by reacting an alkylphenol with formaldehyde and thereafter reacting the reaction product of the above with a C to C alkylene oxide such as ethylene oxide and propylene oxide. The demulsifiers have a generalized structural formula:

wherein U is an alkylene of 2 to 3 carbons;

y is an integer averaging between 4 and x is an integer averaging between 4 and 10; and

R is an alkyl having from 4 to l5 carbons.

Preferred demulsifiers described by the above formula are polyethyleneoxy modified methylene bridged poly(alkylphenol) polymers having a polyethyleneoxy chain of 8 to 20 carbons and preferably from 10 to l6 carbons and at least about 75 number per cent of the polyethyleneoxy chains being within the range specified. The methylene bridged poly(alkylphenol) portion of the polymer has from 4 to 10 and preferably from 5 to 8 repeating methylene bridged alkylphenol units with 4 to and preferably 6 to 12 carbons in the alkyl group. In preferred embodiments, the alkyl groups is a mixture of alkyls having between 4 and 12 with a number average carbon atom range between 6 and I0.

Illustrative alkylphenols include, p-isobutylphenol, p-diisobutylphenol, p-hexylphenol, p-heptylphenol, poctylphenol, p-tripropylen ephenol, pdipropylenephenol, etc.

Another type of demulsifier component is an ammonia-neutralized sulfonated alkylphenol. These compounds have the general structure:

SC NE wherein R is a hydrocarbyl having from 4 to 15 carbons, preferably from 6 to l2.

These compounds are prepared by sulfonating an alkylated phenol and thereafter neutralizing the sulfonated product with ammonia.

Another type of demulsifier is an oxyalkylated glycol. These'compounds are prepared by reacting a polyhydroxy alcohol such as ethylene glycol, trimethylene glycol, etc., with ethylene or propylene oxide. Many of the compounds are commercially available from Wyandotte Chemical Company under the Pluronics trademark. They are polyethers terminated Iv by hydroxy groups and produced by the block copolymerization of ethylene oxide and propylene oxide. The ethylene oxide blocks act as the hydrophiles and the propylene oxide blocks as the hydrophobes. They are available in a wide rangeof molecular Weights and with varying ratios of ethylene oxide to propylene oxide blocks.

The above demulsifier components may be employed individually or in mixtures. A particularly active demulsifier is a mixture of 10 to parts of alkoxy-modified, methylene-bridged polyalkylphenol, 10 to 90 parts of ammonia-neutralized sulfonated alkylphenol, and 10 to 90 parts of an oxyalkylated glycol, per parts of total demulsifier employed.

The demulsifier may be added to the rust inhibitor mixture with or without the aid of a solvent. Generally, however, an inert, stable, organic solvent is employed. Exemplary solvents include those recited infra under the description of concentrates for the additive mixture,

OLEOPI-IILIC ORGANIC LIQUID The oleophilic liquid which can be improved with respect to its rust inhibiting properties encompasses a wide range of stable organic liquids. The term oleophilic", as employed herein, means oil miscible or haw ing an affinity for fats and oils. Another expression meaning the same as oleophilic is lipophilic or hydrophobic. The oleophilic liquids must also be relatively inert to the rust inhibitors and demulsifier if one is employed.

Typical oleophilic liquids include hydrocarbon oils, fuels, synthetic oils, natural fats and oils, mineral oils, etc. Exemplary oleophilic liquids which may be employed in the practice of this invention are hydrocarbons boiling between about 90 and 1,000F. and inclusive of fuel oils, furnace or heating oils, gas oils, lubricating oils, diesel oils, stove oils, jet fuels, motor gasoline, organic solvents, kerosene, etc.; synthetic oils such as alkylene polymers, alkylene oxide type polymers, carboxylic acid esters (e.g., those which were prepared by esterifying carboxylic acids such as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenyl succinic acid, fumaric acid, maleic acid, etc. with an alcohol such as butyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, pentacrythritol, etc), etc.

The particularly preferred oleophilic liquids are hydrocarbon oils boiling between about 300 and 750F.

The oleophilic liquid having the improved properties is prepared by simply admixing therein the inhibitor mixture and other additives as are necessary. Normally, the inhibitor mixture is prepared within. an organic solvent medium. This solvent may be removed prior to its addition to the oleophilic liquid by conventional means such as distillation, extraction, precipitation, etc. In most instances, however, the presence of the organic solvent within the oleophilic liquid does not adversely affect the liquids properties. In these instances the solvent is admixed with the oleophilic liquid along with the inhibitor mixture.

The concentration of the inhibitor mixture and other additives within the oleophilic liquid sufficient to impart the desired properties depends upon the additive selected, the oleophilic liquid used, the amount of water present within the system, the temperatures inyolv'ed, the metal storage tanks and vessels involved,

etc. Generally, however, the components will be present in the amounts shown in the following Table 1.

TABLE 1 COMPONENT CONCENTRATION Component Broad Range Preferred Range l.Oleophilic liquid Major 99--I00 Portion ZJnhibitor Mixture a.Copolymer (ppm) 25500 50-75 b.Hydrocarbyl amine, amide,

imidazoline or mixtures thereof (ppm) -500 355() 3.Demulsifler (ppm) 025 0. ll0 4.0ther Additives (ppm) 0-2000 10-500 The ratio of a-olefin-maleimide copolymer to the hydrocarbyl amine, amide or imidazoline present within the inhibitor mixture will generally be within the range of 10 to 0.75 parts of copolymer per part of amine, and preferably from 2 to 4 parts copolymer per part of amine. The amount of demulsifier will likewise vary depending upon the amounts of inhibitor mixture present. Generally, the demulsifier is present between about 1 and 5 parts, and probably between 1 and 2 parts per 100 parts of inhibitor mixture.

Concentrates of the inhibitor mixture can be made and provides a convenient means for transporting and storing the mixture without the necessity of very large storage tanks and vessels. When concentrates are employed, they may be transported to the site where blending of various additives is performed and simply blended or admixed with the oleophilic liquid. The concentrates generally contain from 50 to 100 weight percent, and preferably from 50 to 60 weight percent of the inhibitor mixture at the ratios above-described in a suitable organic solvent. Typically, the organic solvent is composed of the oleophilic liquid above mentioned, although other organic inert, stable solvents may be employed. Exemplary solvents include aliphatic and aromatic hydrocarbons, aliphatic ethers, halogenated hydrocarbons, and preferably mixed aromatics (i.e., xylenes from reformate fractions) or aliphatics boiling within the range of 300-700F. Other additives of the type mentioned supra may also be present within the concentrate in proportionately greater concentrations as recited in Table 1.

The following examples of specific embodiments of the practice of this invention are presented and should not be understood as limiting the claimed invention, as defined in the accompanying claims.

EXAMPLE 1 This example is presented to illustrate the preparation of a preferred a-olefin-maleimide copolymer which comprises one compound of the inhibitor mixture of this invention.

Into a reaction flask is introduced 243 g. (1.0 mole) of C1540 cracked wax a-olefins*, 98 g. (1.0 mole) of maleic anhydride and 341 g. of benzene. The mixture is stirred at a temperature of 140F., and 9.7 g. (0.04 mole) of benzoyl peroxide in a minimum of benzene is added. The solution is then heated at 185F. for 12 hours. The reaction product is recovered by precipitation with methanol and redissolved in benzene. The yield is 290 grams (85%).

*CIS-ZU No. of Carbon Atoms Mole 7:

l4 1 l5 l2 l6 l9 l7 l8 18 18 l9 17 20 14 21 l l-olefin 94 straight chain 86 Into another reaction flask is introduced 341 g. (1.0 gram equivalent based on anhydride groups) of a 50.0 weight percent solution of the copolymer prepared above in benzene, 324 g. (1.0 mole) (aminopropyl) oleylamine and 306 g. of xylene. The mixture is stirred at a temperature of 35 6F. for 6 hours at which time approximately 18 g. of water is collected in a trap. The mixture is then filtered through Celite. The yield is 582 g. (90%). The product is characterized by its infrared spectrum, showing the characteristic succinimide absorption. The molecular weight of the copolymer, as measured by (ThermoNAM), is 6,140.

EXAMPLE 2 This example is presented to illustrate the effectiveness of the inhibitor mixture in suppressing rust formation in storage tanks containing a fuel oil. The example also illustrates the improvement of the inhibitor mixture over the mixtures components when used individually and over the employment of no inhibitor.

In each of the experiments, gallons of a test hydrofined heating fuel oil boiling between about 300 and 550F. is charged into a new 1 l0-gallon steel storage tank. One liter of distilled water is then added to the tank. The test fuel oil is circulated 8 hours a day for 16 weeks through copper tubing, cotton filters, Webster pump and back to the tank. Once each month during the 16 week test period, the water bottoms and test fuel in each tank are agitated for 1 minute with compressed nitrogen to simulate tank filling. At the end of the 16 week test period, the fuel and water are drawn off and the tanks washed and cut in half for observa tion.

The tank rust is visually observed and rated in accordance with the rating schedule set forth in the following Table 2.

TABLE 2 RATING SCHEDULE Visual Observation Rating No rust metal bright Metal stained no rust Isolated rust spots Minor rust cover. less than 57:

Rust cover, 540% Rust cover, l0 50% Rust cover. 50-80% Rust cover, 80-90% of surface Severe rust cover, 100% of surface Severe corrosion pitting Three storage tanks are employed' in this example along with three different test fuel oils. One test oil contains no additive and is designated as the no additive test oil. Another test oil contains 100 parts per million of N-(aminopropyl) oleylamine and this oil is designed as the hydrocarbyl amine only test oil. The third test oil contains 50 parts per million of the hydrocarbyl amine and l50 ppm of a solution consisting of 12 wt. n-butanol, 1% of a standard demulsifier, 43.5 wt. of the copolymer prepared by the method of Example 1 and 43.5 wt. of an aromatic solvent. This third test oil is designated as the inhibitor mixture test oil.

The results from the 16 week rust experiments with the above test oils are presented below in Table 3.

TABLE 3 16 WEEK STORAGE TANK RUST TESTS Test Oil Rating 1. No additive 8 2. Hydrocarbylamine only I 3. Inhibitor mixture 3 The above Table illustrates an improvement of 2 points on the rating scale from utilizing the mixture of components rather than the hydrocarbyl amine alone and an improvement of 5 points over the fuel containing no inhibitor.

EXAMPLE 3 The test procedure of Example 2 is repeated with identical test oils except that one liter of sea water isg employed'in place of the distilled water. At the end of the 16 week storage tank rust test, the following results are observed andreported in Table 4.

The above Table again illustrates an improvement of 2 points on the rating scale from utilizing the mixture of components rather than the hydrocarbylamine alone, and an improvement of 4 points over the fuel containing no inhibitor.

I claim:

1. A composition of matter comprising in an admixture (l) a copolymer of an alpha-olefin having from 8 to 30 carbons and an N-substituted maleimide wherein the N-substituents are organic radicals having from 3 to 60 carbons and from 1 to 5 amine nitrogens, said copolymer having from 4 to 20 repeating olefinmaleimide units, and (2) a hydrocarbyl amine, having from 3 to 60 carbons and from 1 to 10 nitrogens, the ratio of said copolymer to said hydrocarbyl amine, being within the range of 10 to 0.75parts of copolymer per part of hydrocarbyl amine.

2. The composition defined in claim 1 wherein said copolymers have as'the repeating group, a unit of the following general structure:

wherein A is an aliphatic organic radical of 3 to carbons and l to 5 nitrogens; I v R is a hydrocarbyl having from 6 to 28 carbons; and

n is an integer from 4 to 20.

3. The composition defined in claim 2 wherein said hydrocarbyl amine, is N-(aminopropyl)oleylamine.

4. The composition defined in claim 2 wherein a demulsifier is also present within said admixture.

5. The. composition defined in claim 4 wherein said demulsifier is selected from the group consisting of 1) an alkoxy-modified methylene-bridged-polyalkyl phen01, (2) an ammonia neutralized sulfonated alkyl phenol, (3.) an oxyalkylated glycol, and (4) mixtures thereof.

6. The composition defined in claim 4 wherein said demulsifier hasthe following generalized structural formula:

wherein I 1 U is an alkylene'of 2 to 3 carbons; y is an'integer from 4 to 10;

;r is an integer from 4 to 10; and

R is an alkyl having from 4 to 15 carbons.

7. A'composition of mattencomprising in an admixture 1 a major-amount of an oleophilic organic liquid, (,2) from 25 to 500 weight parts per'million of a copolymer of an alpha-olefin having from 8 to 30 carbons and an N-substituted maleimide whereinthe N-substituents are organic radicals having from 3 to 60 carbons and from 1 to 5 nitrogens, said copolymer having from 4 to 20 repeating olefin-maleimide units, and (3) from 10 to 500 weight parts per million of a hydrocarbyl amine, having from 3 to 60carbons and from 1 to 10 nitrogens with a 'carbon'to nitrogen atomic ratio from 5 to 30:1.

8. Thecomposition defined in claim 7 wherein said oleophilic liquid is a'petroleum distillate fuel.

9. The composition defined in claim 8 wherein said copolymers have as the repeating group, a unit of the following general structure:

.wherein A is. an aliphatic organic radical of 3 to 60 carbons and 1 to 5 amine nitrogens; R is a hydrocarbyl having from 6 to 28 carbons; and n is an integer from 4 to 2O.

10. The composition defined in claim 9 wherein a demulsifier is also present within said admixture.

wherein U is an alkylene of 2 to 3 carbons; y is an integer from 4 to l0; x is an integer from 4 to 10; and R is an alkyl having from 4 to 15 carbons. 13. The composition defined in claim 8 wherein said hydrocarbyl amine, is N(amin0propyl)-oleylamine.

Claims

1. A composition of matter comprising in an admixture (1) a copolymer of an alpha-olefin having from 8 to 30 carbons and an N-substituted maleimide wherein the N-substituents are organic radicals having from 3 to 60 carbons and from 1 to 5 amine nitrogens, said copolymer having from 4 to 20 repeating olefin-maleimide units, and (2) a hydrocarbyl amine, having from 3 to 60 carbons and from 1 to 10 nitrogens, the ratio of said copolymer to said hydrocarbyl amine, being within the range of 10 to 0.75 parts of copolymer per part of hydrocarbyl amine.

2. The composition defined in claim 1 wherein said copolymers have as the repeating group, a unit of the following general structure:

5. The composition defined in claim 4 wherein said demulsifier is selected from the group consisting of (1) an alkoxy-modified methylene-bridged-polyalkyl phenol, (2) an ammonia neutralized sulfonated alkyl phenol, (3) an oxyalKylated glycol, and (4) mixtures thereof.

6. The composition defined in claim 4 wherein said demulsifier has the following generalized structural formula:

7. A COMPOSITION OF MATTER COMPRISING IN AN ADMIXTURE (1) A MAJOR AMOUNT OF AN OLEOPHILIC ORGANIC LIQUID (2) FROM 25 TO 500 WEIGHT PARTS PER MILLION OF A COPOLYMER OF AN ALPHAOLEFIN HAVING FROM 8 TO 30 CARBON AND AN N-SUBSTITUTED MALEIMIDE WHEREIN THE N-SUBSTITUENTS ARE ORGANIC RADICALS HAVING FROM 3 TO 60 CARBONS AND FROM 1 TO 5 NITROGENS SAID COPOLYMER HAVING FROM 4 TO 20 REPEATING OLEFIN-MALIMIDE UNITS AND (3) FROM 10 TO 500 WEIGHT PARTS PER MILLION OF A HYDROCARBYL AMINE HAVING FROM 3 TO 60 CARBONS AND FROM 1 TO 10 NITROGENS WITH A CARBON TO NITROGEN ATOMIC RATIO FROM 5 TO 30:1

8. The composition defined in claim 7 wherein said oleophilic liquid is a petroleum distillate fuel.

11. The composition defined in claim 10 wherein said demulsifier is selected from the group consisting of (1) an alkoxy-modified methylene-bridged-polyalkyl phenol, (2) an ammonia neutralized sulfonated alkyl phenol, (3) an oxyalkylated glycol, and (4) mixtures thereof.

12. The composition defined in claim 10 wherein said demulsifier has the following generalized structural formula:

13. The composition defined in claim 8 wherein said hydrocarbyl amine, is N-(aminopropyl)-oleylamine.