WO2007110780A2

WO2007110780A2 - Enhanced antistatic additives for hydrocarbon fuels & solvents

Info

Publication number: WO2007110780A2
Application number: PCT/IB2007/002070
Authority: WO
Inventors: Cyrus Pershing Henry, Jr.
Original assignee: Innospec Limited
Priority date: 2006-03-24
Filing date: 2007-03-23
Publication date: 2007-10-04
Also published as: AR060059A1; UY30240A1; US20070220803A1; WO2007110780A3; TW200745324A; PE20071294A1

Abstract

Described herein are enhanced performance of antistatic additive compositions for hydrocarbon fuels, the compositions comprising olefin-sulfur dioxide copolymers in combination with polymeric polyamines prepared using an ortho-xylene solvent.

Description

ENHANCED ANTISTATIC ADDITIVES FOR HYDROCARBON FUELS &

SOLVENTS

The present invention relates to an improved two-component antistatic additive for hydrocarbon fuels and solvents to render them electrically conductive. One component is an olefin-sulfur dioxide copolymer (polysulfone copolymer) prepared in orthoxylene, and the other component is a particular polymeric polyamine.

Hydrocarbon fuels normally are very poor conductors of electricity. Electrical charges, therefore, tend to accumulate in the fuel and can be discharged as sparks thus creating the danger of an explosion or fire should such charges ignite hydrocarbon-air admixtures that may be present.

Numerous materials have been suggested in the art to increase the electrical conductivity of hydrocarbon fuels. Suggested materials include two-component additives where one component is a polysulfone and the other is a quaternary ammonium compound. Another suggested two-component additive comprises polysulfone as one component and polyvalent metal organic compounds of metals having an atomic number of from 22 to 29 as the other component.

An important aspect is the solvent used for the polymerization of the polysulfone component. Typically, solvents such as benzene and toluene have been employed. These solvents contain impurities which may result in a potentially toxic situation. Thus, there is a clear need to employ a safer solvent.

The present invention seeks to provide an improved antistatic additive composition for hydrocarbon fuels and solvents to render them electrically conductive.

Typically, the two-component antistatic additives of the present invention are highly effective at low levels of usage and are ashless upon burning. Typically, the two- component antistatic additives are efficient even at relatively low concentrations and they provide the desired conductivity (measured in picomhos per meter, or picoSiemens/meter) in nearly all hydro-carbon fuels. This performance is typically enhanced when the solvent for polymerization of the olefin and sulfur dioxide is orthoxylene.

In the antistatic additive of this invention wherein the components are presented in a weight ratio of 100:1 to 1 :100, and wherein one component is a polysulfone copolymer prepared in ortho-xylene solvent comprising about 50 mol percent of units from sulfur dioxide, about 40 to 50 mol percent of units derived from one or more 1-alkenes each having from about 4 to 24 carbon atoms, and from about 0 to 10 mol perdent of units derived from an olefinic compound having the formula ACH=CHB wherein A is a group having the formula -(C_xH_2x)-COOH wherein x is from 1 to about 23, and B is hydrogen or carboxyl, with the proviso that when B is carboxyl, x is 0, and wherein A and B together can be a dicarboxylic anhydride group, the antistatic composition comprises, in combination with said polysulfone component, a polymeric polyamide of the formula

R¹ is an aliphatic hydrocarbyl group of 4 to 24 carbon atoms,

R² is an alkylene group of 2 to 6 carbon atoms,

R is R¹, or, an N-aliphatic hydrocarbyl alkylene group of the formula R¹NHR²,

a is an integer of 0 to 20,

b is an integer of 0 to 20,

c is an integer of 0 to 20, and

x is an integer of 1 to 2,

with the proviso that when R is R¹ then a is an integer of 2 to 20 and b=c=0, and when R is R¹NH-R² then a is 0 and b + c is an integer of 2 to 20.

Particular embodiments of this invention are those wherein the polysulfone copolymer is composed solely of units derived from sulfur dioxide and units derived from at least one 1-alkene of from 4 to 24 carbon atoms. A particular embodiment is that wherein the 1-alkene is 1-decene and is prepared in an ortho-xylene solvent.

One embodiment, with reference to the polyamine component, is that where R= R¹, wherein R¹ is an aliphatic hydrocarbyl group of 4 to 24 carbon atoms, especially where R¹ is the aliphatic hydrocarbyl group of tallowamine.

Also, with reference to the polyamine component, are embodiments where R is R¹NHR², wherein R¹ is an aliphatic hydrocarbyl group of 8 to 22 carbon atoms and R² is an alkylene group of 3 carbon atoms, especially where R¹ is the aliphatic hydrocarbyl group of tallowamine.

In one aspect of the invention, a polysulfone copolymer of the composition of the invention is 1-decene polysulfone copolymer having an molecular weight in the range of 10,000 to 1,500,000 amu and in a particular aspect, the polymeric polyamine is the polymeric 1:1.25 mol ratio reaction product of N-tallow-1 ,3-diaminopropane with epichlorohydrin.

The weight ratio of polysulfone copolymer to polymeric polyamine in the invention composition ranges from about 100:1 to 1:100, in one aspect from about 50:1 to 1:1, and in another aspect from about 20:1 to 1:1.

This invention also concerns the two-component additive as heretofore described together with a strong acid (oil-soluble sulfonic acid is suitable). Thus, a polyamine- sulfonic acid salt will be formed which has an improved resistance to precipitate- formation during long storage periods. This invention also concerns the additives in concentrate form in a solvent. One composition containing the antistatic additive, an acid to enhance precipitate-free storability, and a solvent, comprises, based on total weight:

i. from about 1 to 50 percent of the polysulfone copolymer, prepared in an ortho xylene solvent,

ii. from about 1 to 50 percent of the polymeric polyamine,

iii. from about 1 to 30 percent of oil-soluble sulfonic acid, and

iv. from about 3 to 97 percent of solvent.

A suitable sulfonic acid (iii) is mono and di sulfonates of alkylbenzenes, and in one aspect is dodecylbenzene sulfonic acid, or dinonylnaphthyl sulfonic acid.

This invention also concerns a composition comprising a liquid hydrocarbon fuel boiling in the range of from about 20° to 375⁰C, and from about 0.01 ppm to 40 ppm of the two-component polysulfone copolymer-polyamine antistatic additive composition and the additive composition stabilized with a strong acid as described herein. Although more than 40 ppm of the additive can be used, no significant benefit

5 is thereby derived. The additive composition can also be used in solvents, oils, and other mixtures such as paints and other formulations where improved conductivity is

- —desired— : —— - -

Certain co-additives which are known to provide good initial electrical conductivity in cooperation with the polysulfone copolymer component can also be included in the 0 composition of the present invention. Included are quaternary ammomium compounds which are more fully described in coassigned U.S. Pat. No. 3,811 ,848 (the entire teaching of which is herein incorporated in its entirety by reference).

It has been found that improved three-component antistatic compositions can be obtained by combining the polymeric polyamine described herein with a two- 5 component antistatic additive comprising:

(i) a polysulfone copolymer prepared in ortho-xylene comprising about 50 mol percent of units derived from sulfur dioxide from about 40 to 50 mol percent of units derived from 1-alkene of 4 to 24 carbon atoms and from 0 to about 10 mol percent of units derived from an olefin having the formula

A is a group having the formula -(C_xH_2x)-COOH wherein x is from about 0 to about 17, and B is hydrogen or carboxyl, with the proviso that when B is carboxyl, x is O₁ and wherein A and B together can be a dicarboxylic anhydride group and,

5

(ii) a quaternary ammonium compound having the formula:

wherein

AIk¹ and AIk² are the same or different alkyl groups having from 1 to 22 carbon atoms, Alk³ is selected from the group consisting of alkyl groups of 1 to 22 carbon atoms and

where AIk⁵ is hydrogen or methyl and n is 1 to 20,

AIk⁴ is selected from the group consisting of (a) an alkyl group having 1 to 22 carbon atoms, (b) an aralkyl group having from 7 to 22 carbon atoms, (c) a

group as defined above, (d) a

O

CH₂CH₂O P — -OCH₂CH(OCOAIk⁶)CH₂OCOAIk⁷

O

group wherein

AIk⁶ and AIk⁷ are the same or different alkyl groups having from 11 to 19 carbon atoms, and (e) an -AIk⁸ -CO₂ group wherein AIk⁸ is a hydrocarbyl group having from 1 to 17 carbon atoms, with the proviso that when AIk¹, AIk², AIk³ and AIk⁴ are each alkyl groups, at least one of them is an alkyl group having at least 8 carbon atoms,

A is an anion, z is 0 or 1 , z is 0 when AIk⁴ is (d) or (e), and

y is at least 1 , y is equal to the ionic valence of anion A when z is 1.

The ratio of the components are such that for each part of polysulfone copolymer there is 0.01 to 100 parts of each of the polymeric polyamine and the quaternary ammonium compound.

A suitable quaternary ammonium compound is dicocodimethyl ammonium nitrite wherein "coco" refers to a mixture of C₃ to C₁₈ alkyl radicals of cocoamine. The quaternary ammonium compound can be present in the amounts of from about 1 part to 25 parts per 100 parts of polysulfone copolymer. The presence of a quaternary ammonium compound further enhances the electrical conductivity of the present invention composition in many hydrocarbon fuels and maintains the composition ash- free.

Another embodiment of the present invention is directed to a fuel oil composition. This fuel composition can comprise a suitable fuel component and a suitable additive component. In one aspect, the composition comprises from about 99.99% fuel and about 0.0 1% of additive to about 99.9999% fuel to about 0.0001% of additive. A suitable additive includes those described herein.

The term "hydrocarbyl" employed herein refers to straight and branched-chain groups containing only carbon and hydrogen. Such groups can be saturated, unsaturated or aromatic.

The Polysulfone Copolymers:

The polysulfone copolymers often designated as olefin-sulfur dioxide copolymer, olefin polysulfones, or poly(olefin sulfone) are polymers wherein the structure is considered to be that of alternating copolymers of the olefins and sulfur dioxide, having a one-to-one molar ratio of the comonomers with the olefins in head to tail arrangement. The polysulfone copolymers used in this invention are readily prepared by the methods known in the art (cf. Encyclopedia of Polymer Science and Technology Vol. 9, lnterscience Publishers, page 460 etc, the entire teaching of which is incorporated herein by reference).

The weight average molecular weights of the polysulfone copolymers are in the range from about 10,000 to about 1 ,500,000, in one aspect the range is from about 50,000 to about 900,000, and in another aspect the molecular weights range from about 100,000 to about 500,000. Olefin polysulfones whose molecular weights are below about 10,000, while effective in increasing conductivity in hydrocarbon fuels, do not increase the conductivity values as much as olefin polysulfones of higher molecular weights. Olefin polysulfones whose molecular weights are above about 1 ,500,000 are difficult to produce and are more difficult to handle.

The molecular weights of the olefin polysulfones can be determined by any of the well-known methods, such as the light scattering method. It is generally more convenient, however, to determine the inherent viscosity of the polymer to derive the approximate molecular weight range of the polysulfone copolymers therefrom. Inherent viscosity is defined as η_inh = In.η_reι/C wherein In is the natural logarithm, η_reι is a relative viscosity, i.e., ratio of the viscosity of the polymer solution to the viscosity of the polymer solvent and C is concentration of polymer g/IOO mL The units of inherent viscosity are deciliters per gram (dl/g). The inherent viscosities of olefin poly-sulfones are conveniently measured in toluene at 3O⁰C as 0.5 weight percent solutions. It has been found by comparison with molecular weight determinations that polysulfone copolymers with inherent viscosities of between about 0.1 dl/g to 1.6 dl/g correspond to weight average molecular weights in the range of about 50,000 to 900,000.

The control of the molecular weights of the olefin polysulfones in the desired range is readily accomplished by those skilled in the art of polymer science by controlling the polymerization conditions such as the amount of initiator used, polymerization temperature and the like or by using molecular weight modifiers such as dodecyl mercaptan. The amount of molecular weight modifier required to obtain the desired molecular weight range will depend upon the particular 1 -olefin being polymerized with sulfur dioxide, and can be determined easily with few experiments. Generally, the amount of modifier, such as dodecyl mercaptan, used to obtain the molecular weights in the range of 50,000 to 900,000 is in the range of up to about 0.007 mole per mole of 1 -olefin.

The 1-alkenes useful for the preparation of the polysulfone copolymers are available commercially as pure or mixed olefins from petroleum cracking processes or from the polymerization of ethylene to a low degree. Included, but not limited to, are 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1- tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1- nonodecene, I-eicosene, 1-heneicosene, 1-docosene, 1-tricosene and 1-tetracosene. Polyunsaturated olefins such as butadiene and its analogs, and branched olefins and internal olefins are also utilizeable in the invention. Although branched-chain alkenes are useful, the straight-chain 1 -alkenes are also useful whether pure or in admixture with other straight-chain 1 -alkenes.

When the polysulfone copolymer contains up to 10 mol percent of the olefin AHC=CHB, as defined above, A and B can together form a dicarboxylic anhydride group. The dicarboxylic anhydride group is readily converted to two carboxyl groups by simple acid hydrolysis. The olefin, AHC=CH₂, is a terminally unsaturated alkenoic acid represented by CH₂=CH-(C_xH_2X)-COOH. The alkylene group bridging the vinyl and the carboxyl groups can have from 1 to 24 carbon atoms or it can be absent, and such alkylene group when present can be a straight chain group or branched chain. The useful acids are alkenoic acids of 3 to 20 carbon atoms wherein the olefinic group is a terminal group. Representative but nonlimiting examples of alkenoic acids with a terminal olefinic group include acrylic acid, 3-butenoic acid, 4-pentenoic acid, 5- hexenoic acid, 6-heptenoic acid, 7-octenoic acid, 8-nonenoic acid, 9-decenoic acid, I0- undecenoic acid, 1 1-dodenoic acid, 13-tetradecenoic acid, 15-hexadecenoic acid, 17- octadecenoic acid as well as branched chain alkenoic acids with terminal olefinic groups such as 2-ethyl-4-pentenoic acid, 2,2-dimethyl-4-pentenoic acid, 3-ethyl-6- heptenoic acid, 2-ethyl-6-heptenoic acid, 2,2-dimethyl-6-heptenoic acid, and the like. It should be understood that a mixture of alkenoic acids can be used.

The reaction leading to polysulfone copolymer formation is the art-known free-radical polymerization process. Nearly all types of radical initiators are effective in initiaing polysulfone copolymer formation. Radical initiators such as oxygen, ozonides, t- butylperoxy-pivalate, hydrogen peroxide, ascaridole, cumene peroxide, benzoyl peroxide, azobisisobutyronitrile are examples of some of the useful initiators. Free- radicals are generated from such radical initiators either thermally and/or by light activation in the presence of a mixture of sulfur dioxide and 1-alkene. The polymerization can be carried out in liquid phase, conveniently in a solvent such as benzene, toluene or xylene to facilitate the reaction. In one aspect of this invention, ortho-xylene ('o-xylene') is the solvent employed. Such solvent can be removed, e.g., by distillation, if desired, but it is generally more convenient to use the polysulfone copolymer as a concentrate in such solvent. Generally, it is typical to use an excess of sulfur dioxide since any unreacted sulfur dioxide is readily removed as by passing nitrogen gas into the polymer solution. An excess of 1-alkene can be used, however, and the excess subsequently removed as by distillation.

Using ortho-xylene has several advantages. For example, the use of o-xylene as a solvent leads to increased conductivity, an increase of approximately 15% was observed when o-xylene was used. (See Tables I and II, infra.) Ortho-xylene also facilitates the removal of toxins, e.g., ethyl benzene. One also observes an increase in flash point using o-xylene, as compared to toluene. This is mainly due to the difference in the flash points between o-xylene (86° C) and Toluene (40° C)

Table I: Comparison of the conductivity enhancement of a Static Dissipater formulation where the poly Sulfone polymer in the formulation was prepared in o- xylene, to that which was prepared in Toluene.

Formulation Conductivity pS/m Conductivity pS/m

1 PSI w/ o-xylene 369 425

2 PSI w/ o-xylene 342 388

3 PSI w/ toiuene 303 345

Conductivity measurements were performed using an Emcee 1153 conductivity meter in accordance with ASTM D2624. Each formulation included 3mg/l of the antistatic composition in lsopar M solvent.

Table II: Conductivity of a Static Dissipater formulations where the polysulfone polymer in the formulation was prepared in Toluene.

The particular ratio of 1-alkene to sulfur dioxide appears to be immaterial since the resultant polysulfone copolymer contains 1-alkene and sulfur dioxide in 1 :1 molar ratio regardless of the particular ratio used. However, for efficiency in utilization of the reactants and of the equipment, a slight excess of sulfur dioxide is often employed. The polymerization can be carried out at atmospheric or super-atmospheric pressures, the polymerization reaction being independent of the pressure. The polymerization temperature can be any convenient temperature below the ceiling temperature of the particular 1-alkene employed. Ceiling temperature is the temperature at which the rates of polymerization and depolymerization are equal so that no polymer formation takes place. The above mention "Encyclopedia of Polymer Science and Technology" on page 466 lists ceiling temperatures for various 1- alkenes. Generally, the convenient polymerization temperature range is from about 0° to about 50° C. The Polymeric Polyamines:

The polyamine component of the antistatic composition of the present invention is a polymeric reaction product of epichlorohydrin with an aliphatic primary monoamine or N-aliphatic hydrocarbyl alkylene diamine. The polymeric reaction products are prepared by heating an amine with epichlorohydrin in the molar proportions of from about 1:1-1.5 in the temperature range of about 50° to about 100⁰C. Generally, with aliphatic monoamines, R¹NH₂, the molar ratio is about 1 :1. The initial reaction product is believed to be an addition product as illustrated below with a primary momoamine, R¹NH₂,

The aminochlorohydrin (I) upon reaction with an inorganic base then forms an aminoepoxide (II).

(H)

The aminoepoxide (II), which contains a reactive epoxide group and a reactive amino- hydrogen, undergoes polymerization to provide a polymeric material containing several amino groups. The ratio of epichlorohydrin to amine and the reaction temperature used are such that the polymeric reaction product contains from 1 to 20 recurring units derived from the aminoepoxide represented by II.

The polymeric reaction product derived from epichlorohydrin and an aliphatic primary monoamine as defined is represented by subgeneric formula (A),

(A) where a is an integer from 1 to 20 and x is an integer of 1 to 2.

The aliphatic primary monoamines that can be used to prepare the polymeric reaction products with epichlorohydrin can be straight chain or branched chain and include, inter alia, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridedecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, heneicosylamine, docosylamine, tricosylamine, tetracosylamine and the corresponding alkenyl analogs. The aliphatic primary amine should have at least about 4 carbon atoms, in one aspect, about 12 to 24 carbon atoms to provide polymeric reaction products of sufficient solubility in hydrocarbon fuels. While aliphatic primary amines containing more than about 24 carbon atoms are useful, such amines are of limited availability.

Mixtures of aliphatic primary amines can also be used, and are typical since mixtures of primary amines derived from tall oil, tallow, soybean oil, coconut oil, cotton seed oil and other oils of vegetable and animal origin are commercially available and at lower cost than individual amines. The above mixtures of amines generally contain alkyl and alkenyl amines of from about 12 to 18 carbon atoms, although sometimes an individual amine mixture, depending upon the source, contains small amounts of primary amines having fewer or more carbon atoms. An example of a commercially available mixture of primary monoamines is hydrogenated tallow amine which contains predominantly hexadecyl- and octadecylamines with smaller amounts of tetradecylamine.

When the amine reacted with epichlorohydrin is an N-hydrocarbylalkyl-enediamine as defined, the polymeric reaction product is represented by subgeneric formula (B),

(B)

where R¹ is an aliphatic hydrocarbyl group of 4 to 24 carbon atoms, R² is an alkylene group of 2 to 6 carbon atoms, b and c are integers of 0 to 20 and b + c is an integer of 2 to 20 and x is 1 to 2. In the reaction of epichlorohydrin with an N-aliphatic hydrocarbylalkylenediamine, it is believed (because of the known greater reactivity of primary amino hydrogen over secondary amino hydrogen) that the initially formed aminochlorohydrin is of the formula Ia

and the subsequently formed aminoepoxide is of the formula Ha

When Ha undergoes further condensation, the recurring units in the product may be

or both, since (Ma) contains two reactive secondary aminohydrogens. Thus, in subgeneric formula (B), above, b is from O to 20, c is from 0 to 20 and b + c is from 2 to 20.

Illustrative examples of useful N-aliphatic hydrocarbyl alkylene diamines include, but not limited to, N-octyl, N-nonyl, N-decyl, N-undecyl, N-dodecyl, N-tridecyl, N- tetradecyl, N-pentadecyl, N-hexadecyl, N-heptadecyl, N-octadecyl, N-nonadecyl, N- eicosyl, N-uneicosyl, N-docosyl, N-tricosyl, N-tetracosyl, as well as the corresponding N-alkenyl derivatives of ethylenediamine, propylenediamine, butylenediamine, pentylenediamine and hexylenediamine. In one aspect, the N-aliphatic hydrocarbylalkylenediamine is N-aliphatic hydrocarbyl-1 ,3-propylenediamine. The N- aliphatic hydrocarbyl- 1 ,3-propylenediamines are commercially available and are readily prepared from aliphatic primary monoamines such as those described above by cyanoethylation with acrylonitrile and hydrogenation of the cyanoethylated amine. Mixtures of N-aliphatic hydrocarbyl-1 ,3-propylenediamines can also be advantageously used. A typical mixture is N-tallow-1 ,3-propylenediamine which is commercially available as "Duomeen T" wherein "tallow" represents predominantly mixtures of alkyl and alkenyl groups of 16 to 18 carbon atoms which can contain small amounts of alkyl and alkenyl groups of 14 carbon atoms.

The reaction between the amines (as defined) and epichlorohydrin is advantageously carried out in the presence of a solvent such as benzene, toluene, xylene, ortho- xylene, or other higher boiling mixtures of aromatic solvents, such as Aromatic 100 or Aromatic 150 which can also contain some hydroxylic component such as ethanol, propanol, butanol and the like.

After the initial reaction between the amine and epichlorohydrin to form an aminochlorohydrin intermediate as illustrated above by Products I and Ha, the reaction mass is treated with an inorganic base, such as sodium, potassium or lithium hydroxide, to form an aminoepoxide as represented by Products Il and Ha above, which under continued heating undergoes polymerization to yield the desired product represented above by the generic formula and subgenerics A and B. Inorganic chloride formed in the reaction is removed by filtration. The solvent used to facilitate the reaction can be removed if desired, e.g., by distillation, but generally it is more convenient to use the polymeric polyamine as a solution.

The above-described reactions of epichlorohydrin with amines to form polymeric products are well known and find extensive use in epoxide resin technology (cf "Epoxy Resins", Henry Lee and Kris Neville, The McGraw-Hill Book Co., 1957, the entire teaching of which is incorporated herein by reference). The polymeric reaction products of epichlorohydrin and amines are complex mixtures but it is believed that the above formulas of the polymeric polyamines fairly represent the composition and structures that are obtained.

The normally liquid hydrocarbon fuels to which the additives are added to render such hydrocarbon fuels electrically conductive are those boiling in the range of about 20° to about 375°C and include such commonly designated fuels as aviation gasoline, motor gasoline, jet fuels, naphtha, kerosene, diesel fuel and distillate burner fuel oil. The additive composition can be added in any conventional manner. Each individual component of the composition can be added to the hydrocarbon fuel separately or the composition can be added as a simple mixture or as a solution in a solvent, such as benzene, toluene, xylene, o-xylene, isopropanol, cyclohexane, Aromatic 100 and Aromatic 150 fuel oil, or in a mixture of such solvents. It is convenient to prepare both the polysulfone copolymer and the polymeric polyamine in a solvent, such as one or more of those mentioned above. Thus, it is typical to use such solutions of polysulfone copolymer and polymeric polyamine and to combine them. The combination, which can be termed a concentrate, can then be added to the hydrocarbon fuel. Such concentrate conveniently contains from about 1 to 40% by weight of polysulfone copolymer, from about 1 to about 40% by weight of polymeric polyamine and from about 20 to 98% by weight of a solvent or a mixture thereof as described. In one aspect, the concentrate will contain from about 5 to 25% by weight of polysulfone copolymer, from about 5 to 25% by weight of polymeric polyamine and from about 50 to 90% by weight of solvent.

When formulating concentrates, it is typical that the polymeric polyamine be present as a salt, particularly a sulfonic acid salt, for improved resistance to precipitate formation in storage. For example, when a concentrate as described comprising polymeric polyamine in the free base form is stored at elevated temperatures of about 44⁰C for a period of time of about 4 weeks, a small amount of precipitate sometimes forms. The presence of small amounts of precipitate in the concentrates have little or no effect on the usefulness of the present compositions as antistatic additives but are undesirable if only from an aesthetic point of view. It has been found that strong acids such as hydrochloric, sulfuric or a sulfonic acid can be used to limit precipitate formation in the concentrates. Oil-soluble sulfonic acids are typical because they effectively inhibit precipitate formation without substantial deleterious effect upon the electrical conductivity property of the composition. Any oil-soluble sulfonic acid such as an alkanesulfonic acid or an alkarylsulfonic acid can be used. A useful sulfonic acid is petroleum sulfonic acid resulting from treating oils with sulfuric acid.

Generally, the amount of sulfonic acid incorporated in the concentrate is an equivalent amount, that is, sufficient amount of sulfonic acid to neutralize all the amine groups of the polymeric polyamine, although lesser or greater than the equivalent amount can be used. Thus, one form of the concentrate of the present invention will contain from about 5 to 25% by weight of polysulfone copolymer, from about 5 to 30% by weight of polymeric polyamines, from about 5 to 30% by weight of, say, dodecylbenzenesulfonic acid, and from about 20 to 85% by weight of solvent. Typically an equivalent amount of dodecylbenzenesulfonic acid or dinonylnaphthyl sulfonic acid is used.

When a three-component additive is employed (where a quaternary ammonium compound is the third component), the concentrate composition will comprise, based on total weight of the composition: from about 5 to 25% of polysulfone copolymer, from about 5 to 25% of polyamine, from about 0.5 to 5% of quaternary ammonium compound, from about 5 to 25% of a sulfonic acid, say, dodecylbenzene sulfonic acid, and from about 20 to 84.5% of solvent.

The utility of the present invention composition as a highly effective antistatic additive for hydrocarbon fuels is demonstrated by the fact that the incorporation into hydrocarbon fuels of as little as 0.00003% by weight (0.3 part per million, ppm) of polysulfone copolymer and 0.00002% by weight (0.2 ppm) of polymeric polyamine is sufficient, in nearly all hydrocarbon fuels investigated, to provide electrical conductives of at least 100 CU. (conductivity units). In certain responsive fuels, as little as 0.0000018 weight % (0.018 ppm) polysulfone copolymer and 0.0000013 weight % (0.013 ppm) polymeric polyamine provide a conductivity of at least 100 CU. Thus, the present invention provides a highly effective ashless antistatic additive composition which confers increased electrical conductivity to hydrocarbon fuels at very low usage levels.

The antistatic effectiveness of the present invention composition is unexpected as the polysulfone copolymer product prepared in o-xylene and the correspondent composition derived from said polysulfone copolymer is superior to a similar composition derived from polysulfone copolymer prepared from toluene.

The hydrocarbon fuels into which the present composition is incorporated exhibit satisfactory water interaction properties as evidenced by satisfactory results in the water separation test according to ASTM D-2250-66T. The hydrocarbon fuel composition containing the composition of the invention can also contain conventional additives used in hydrocarbon fuels such as antiknock compounds, antioxidants, corrosion inhibitors, metal deactivators, rust preventatives, dyes, anti-icing agents and the like. The polysulfone copolymers, and poly amines evaluated in the present invention were prepared according to procedures outlined in U.S. 3,917,466. The examples cited therein are not intended to be a limit of the scope of the invention.

Another embodiment of the present invention is directed to a fuel oil composition. This fuel oil composition can comprise a suitable fuel oil component and a suitable additive component. In one aspect, the composition comprises from about 99.99% fuel and about 0.0 1% additive to^" about 99.9999% fuel to about 0.0001% additive. In one aspect, a suitable additive includes those described herein. The fuel oil can be a petroleum-based fuel oil, suitably a gasoline or middle distillate fuel oil. The fuel oils can comprise atmospheric or vacuum distillate, contain cracked gas oil in or a blend of any proportion of straight run or thermally or catalytically cracked distillates, and in many cases are hydrogen-treated or otherwise processed to improve properties.

Gasolines are low boiling mixtures of aliphatic, olefinic, and aromatic hydrocarbons, and optionally alcohols or other oxygenated components, boiling in the range from room temperature up to 225 ⁰C. Other fuel oils are kerosene, jet fuels, diesel fuel oils and home heating fuel oils (such as, middle distillate heating fuels), generally having flash points greater than 38 ⁰C. These fuels are higher boiling mixtures of aliphatic, olefinic, and aromatic hydrocarbons having a boiling point up to 350 ⁰C.

Conductivity of fuels and solvents comprising static dissipators are commonly measured using ASTM D 2624 or IP 274, a technically equivalent method. See,

ASTM D 2624-02, the entire teaching of which is incorporated herein by reference.

For comparative purposes, compositions can be tested according to the method described in ASTM in fuels, or in a standard solvent such as lsopar M. lsopar M is a high-flash solvent marketed by Exxon Mobil and is highly paraffinic. Results from testing in this solvent are directionally similar to those obtained in fuels such as motor gasoline, aviation gasoline, aviation turbine fuel, diesel fuels of various sulfur contents, and home heating fuels.

EXAMPLE 1 Preparation of 1-Decene Polysulfone Copolymer

A 1 litre pressure reactor equipped with a stirrer, thermometer and gas inlet tube was swept with dry nitrogen. The pressure reactor was then charged with 101g of 1- decene, 188.5g of orthoxylene and 2.Og of dodecyl mercaptan, and the resulting mixture stirred under nitrogen for 1 hour. Afterwhich and at a temperature of 21 ⁰C 3.Og of "Lupersol" 11 M75 (a 75% solution of t-butyl peroxypivalate in neutral mineral spirits) was added to the reactor. The reactor was sealed, swept twice with nitrogen and evacuated. Sulfur dioxide, 69g was then added to the reactor. The reaction mixture was heated to 38° to 42⁰C with agitation for 2 hours. The maximum pressure developed during the polymerization was 1.6 bar. The reactor was cooled to room temperature and purged with nitrogen at a temperature of 50 to 55 ⁰C for 5 hours to remove unreacted SO₂. Volatiles were then removed in vacuo to provide 321 g of 1- decene polysulfone copolymer.

EXAMPLE 2 Preparation of 1-Decene Polysulfone Copolymer

A 1 litre pressure reactor equipped with a stirrer, thermometer and gas inlet tube was swept with dry nitrogen. The pressure reactor was then charged with 105g of 1- decene, 189g of orthoxylene and 1.9g of dodecyl mercaptan, and the resulting mixture stirred under nitrogen for 1 hour. Afterwhich and at a temperature of 21 ⁰C 3.1g of "Lupersol" 11 M75 (a 75% solution of t-butyl peroxypivalate in neutral mineral spirits) was added to the reactor. The reactor was sealed, swept twice with nitrogen and evacuated. Sulfur dioxide, 68g was then added to the reactor. The reaction mixture was heated to 38° to 42⁰C with agitation for 2 hours. The maximum pressure developed during the polymerization was 1.4 bar. The reactor was cooled to room temperature and purged with nitrogen at a temperature of 50 to 55 ⁰C for 5 hours to remove unreacted SO₂. Volatiles were then removed in vacuo to provide 332g of 1- decene polysulfone copolymer.

EXAMPLES 3 to 8 Preparation of other Polysulfone Copolymers

Using the same procedure as described in Example 1 the following polysulfone copolymers were prepared:

1-Hexene polysulfone copolymer (Example3);

1-Octene polysulfone copolymer (Example 4);

1-Dodecene polysulfone copolymer (Example 5); 1-Hexadecene polysulfone copolymer (Example 6);

1-Octene/octadecene (10/1) polysulfone copolymer (Example 7); and

1-Decene/maleic anhydride (10/1) polysulfone copolymer (Example 8).

COMPARATIVE EXAMPLE A Preparation of 1-Decene Polysulfone Copolymer

A 1 litre pressure reactor equipped with a stirrer, thermometer and gas inlet tube was swept with dry nitrogen. The pressure reactor was then charged with 104g of 1- decene, 189g of toluene and 2.2g of dodecyl mercaptan, and the resulting mixture stirred under nitrogen for 1 hour. Afterwhich and at a temperature of 21 ⁰C 3.1g of "Lupersol" 11M75 (a 75% solution of t-butyl peroxypivalate in neutral mineral spirits) was added to the reactor. The reactor was sealed, swept twice with nitrogen and evacuated. Sulfur dioxide, 69g was then added to the reactor. The reaction mixture was heated to 38° to 42⁰C with agitation for 2 hours. The maximum pressure developed during the polymerization was 1.4 bar. The reactor was cooled to room temperature and purged with nitrogen at a temperature of 50 to 55 ⁰C for 5 hours to remove unreacted SO₂. Volatiles were then removed in vacuo to provide 32Og of 1- decene polysulfone copolymer.

EXAMPLE 9 Preparation of Polymeric Polyamine

lηto a reaction flask equipped with a stirrer, a reflux condenser, a thermometer and an addition funnel, and containing 110g (0.33 mole) of N-tallow-1 ,3-diaminopropane ("Duomeen T"), 110ml of xylene and 30ml of isopropanol heated at 55° to 6O⁰C, was added 31 g (0.33 mole) of epichlorohydrin in 75ml of xylene. The reaction mixture was kept at 55° to 6O⁰C for 1.5 hour. The temperature was then raised to 8O⁰C and held at 8O⁰C for 2.5 hours. Solid sodium hydroxide, 13.3g was then added, the temperature raised to 9O⁰C and kept at 9O⁰C for 2 hours. The reaction mixture was cooled to room temperature, and filtered to provide an amber solution. Removal of the solvents by distillation at reduced pressure provided the polymeric polyamine as a viscous polymer. 0

20

EXAMPLE 10 Preparation of Polymeric Polyamine

Using the same procedure as described in Example 9, polymeric polyamine was prepared from epichlorohydrin and N-tallow-1 ,3-diaminopropane wherein the molar ratio of epichlorohydrin to N-tallow-1 ,3-diaminopropane was 1.5:1.

EXAMPLES 11 to 17 Preparation of Antistatic Compositions

The compositions listed in Table 3 below were prepared. The solvent is toluene except that about 0.7% of isopropanol is included when dicocomethylammonium nitrate is present.

Table 3

Claims

1. A composition for use as an additive for hydrocarbon fuels comprising, based on total weight,

i. from about 1 to 50 percent of polysulfone copolymer,

ii. from about 1 to 50 percent of polymeric polyamine,

iii. from about 1 to 30 percent of oil-soluble sulfonic acid, and

iv. from about 3 to 97 percent of solvent,

said polysulfone copolymer of (i) comprising about 50 mol percent of units from sulfur dioxide, about 40 to 50 mol percent of units derived from one or more 1-alkenes each having from about 4 to 24 carbon atoms, and from about 0 to 10 mol percent of units derived from an olefinic compound having the formula ACH=CHB wherein A is a group having the formula -(C_xH_2X)-COOH wherein x is from about 0 to about 17, and B is hydrogen or carboxyl, with the proviso that when B is carboxyl, x is 0, and wherein A and B together can be a dicarboxylic anhydride group,

said polymeric polyamine of (ii) having the formula

wherein

R¹ is an aliphatic hydrocarbyl group of 8 to 24 carbon atoms,

R² is an alkylene group of 2 to 6 carbon atoms,

a is an integer of 0 to 20,

jb is an integer of 0 to 20, c is an integer of 0 to 20, and

x is an integer of 1 to 2,

with the proviso that when R is R¹ then a is an integer of 2 to 20 and b=c=0, and when R is R¹NH-R² then a is 0 and b + c is an integer of 2 to 20, and said solvent of (iv) being ortho-xylene.

2. The composition of claim 1, wherein said polysulfone copolymer has a molecular weight ranging from about 10,000, to about 1,500,000 amu.

3. The composition of claim 1 or 2, wherein said polysulfone copolymer is selected from the group consisting of 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1- undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1- heptadecene, 1-octadene, 1-nonodecene, 1-eicosene, 1-heneicosene, 1-docosene, 1- tricosene, and 1-tetracosene.

4. The composition as claimed in any one of the preceding claims, wherein said 1- alkene of said polysulfone copolymer is 1-decene.

5. The composition as claimed in any one of the preceding claims, wherein said polymeric polyamine is a polymeric reaction product of epichlorohydrin with an aliphatic primary monoamine or N-aliphatic hydrocarbyl alkylene diamine.

6. The composition of claim 5, wherein said aliphatic primary monoamine is selected from the group consisting of octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridedecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadadecylamine, nonadecylamine, eicosylamine, heneicosylamine, docosylamine, tricosylamine, and tetracosylamine.

7. The composition of claim 5, wherein said N-aliphatic hydrocarbyl alkylene diamine is selected from the group consisting of N-octyl, N-nonyl, N-decyl, N-undecyl, N-dodecyl, N-tridecyl, N-tetradecyl, N-pentadecyl, N-hexadecyl, N-heptadecyl, N- octadecyl, N-nonadecyl, N-eicosyl, N-uneicosyl, N-docosyl, N-tricosyl, N-tetracosyl, as well as the corresponding _N-alkenyl derivatives of ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, and hexylenediamine.

8. The composition as claimed in any one of the preceding claims, wherein a weight ratio of said polysulfone copolymer to said polyamine ranges from about 100:1 to about 1:100.

9. The composition of claim 8, wherein a weight ratio of said polysulfone copolymer to said polyamine ranges from about 50:1 to about 1:1.

10. The composition of claim 9, wherein a weight ratio of said polysulfone copolymer to said polyamine ranges from about 20:1 to about 1:1.

11. The composition as claimed in any one of the preceding claims, wherein said oil-soluble sulfonic acid is either a mono or di sulfonate of alkyl benzene.

12. The composition of claim 11, wherein said oil-solubie sulfonic acid is either dodecylbenzene sulfonic acid or dinonylnaphthyl sulfonic acid.

13. The composition as claimed in claim 12, wherein said oil-soluble sulfonic acid is dodecylbenzene sulfonic acid.

14. The composition as claimed in any one of the preceding claims, further including, based on total weight, from about 0.5 to 5 percent of quaternary ammonium compound, having the formula

wherein

AIk¹ and AIk² are the same or different alkyl groups having from 1 to 22 carbon atoms, AIk³ is selected from the group consisting of alkyl groups of 1 to 22 carbon atoms and

where AIk⁵ is hydrogen or methyl and n is 1 to 20,

AIk⁴ is selected from the group consisting of

(a) an alkyl group having 1 to 22 carbon atoms,

(b) an aralkyl group having from 7 to 22 carbon atoms,

(C) a

group as defined above,

(d) a O

CH₂CH₂O P OCH₂CH(OCOAIk⁶)CH₂OCOAIk⁷

O

group, wherein

AIk⁶ and AIk⁷ are the same or different alkyl groups having from 11 to 19 carbon atoms, and

(e) an -Alk⁸-CO₂ group wherein AIk⁸ is a hydrocarbyl group having from 1 to

17 carbon atoms, with the proviso that when AIk¹, AIk², AIk³ and AIk⁴ are each alkyl groups, at least one of them is an alkyl group having at least 8 carbon atoms,

A is an anion,

z is 0 or 1 , z is 0 when AIk⁴ is (d) or (e), and

y is at least 1 , y is equal to the ionic valence of anion A when z is 1.

15. The composition of claim 14, wherein said quaternary ammonium is dicocodimethyl ammonium nitrate.

16. A fuel oil composition comprising a major proportion of a fuel oil and a minor portion of the composition as defined in any one of claims 1 to 15.

17. The composition of claim 16, wherein said fuel oil is selected from the group consisting of a petroleum-based fuel, kerosene, jet fuel oil, middle distillate heating oils, and diesel fuel oil.

18. The composition of claim 17, wherein said petroleum-based fuel is a gasoline or middle distillate fuel oil.

19. The composition as claimed in any one of claims 16 to 18 wherein the composition as defined in any one of claims 1 to 15 is present in an amount of from about 0.01 ppm to about 40 ppm of said fuel oil composition.

20. The composition as claimed in any one of claims 16 to 19, wherein the fuel oil has a boiling range of from about 20 ⁰C to about 375⁰C.

21. Use of a composition as defined in any one of claims 1 to 15 for increasing the conductivity of a hydrocarbon fuel.

22. The composition as claimed in any one of claims 1 to 15 for use as an antistatic additive for a hydrocarbon fuel.