WO1997025392A1

WO1997025392A1 - Gasoline detergent compositions

Info

Publication number: WO1997025392A1
Application number: PCT/GB1996/003244
Authority: WO
Inventors: Trevor John Russell; Antony Cooney
Original assignee: The Associated Octel Company Ltd.
Priority date: 1996-01-04
Filing date: 1996-12-31
Publication date: 1997-07-17
Also published as: GB9600076D0; AU1204997A

Abstract

A gasoline comprising: i) from 10 to 5000 ppm by weight, preferably 50 to 1000 ppm by weight of a polyisobutenyl succinimide wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 500 to 5000, and ii) from 10 to 5000 ppm by weight, preferably 50 to 1500 ppm by weight, of a carrier oil comprising a polyinternal olefin having a viscosity of 4 to 20 cSt at 100 °C, and additive compositions for use in the preparation thereof.

Description

GASOLINE DETERGENT COMPOSITIONS

FIELD OF THE INVENTION

This invention relates to multi-functional detergent- containing additive compositions for hydrocarbon fuels. More particularly, the invention relates to alkenyl succinimide-based detergent compositions for hydrocarbon fuels and especially gasoline.

BACKGROUND AND DESCRIPTION OF PRIOR ART

It is well known in the art that during the operation of an internal combustion engine, fuel and lubricant deposits accumulate at various points in the inlet system. It is known that in order to avoid these disadvantages, multi-functional detergent-containing additive compositions are used which have to satisfy a large number of criteria, including:

(1) Elimination of carburettor and injector fouling.

(2) Good detergency in the inlet port and valve region.

An important property of fuel additive compositions, in addition to meeting the above criteria, is the avoidance of undesirable effects on engine operation such as prevention of valve stem sticking and tolerance of the package to water.

Valve stem sticking is a problem often associated with the use of high molecular weight detergents, particularly those with a polyisobutene backbone. The detergent layer on the valve stem may become so viscous under low temperature conditions that the valves stick. This leads to compression loss and even engine failure.

Another potential problem is that of the package separating in the presence of water. In some circumstances additive storage conditions can be such that contamination with water accumulating at the bottom of storage tanks may result in the separation of package components.

Both of these problems are thought to be related to the miscibility between the detergent and carrier. Therefore it is particularly advantageous that compatibility between the additives is such that the combinations of detergent and carrier fluid do not lead to phase separation.

WO93/20170 discloses gasoline compositions containing a polyisobutenyl succinimide detergent wherein the polyisobutenyl substituent of the succinimide has a number average mol.wt. in the range 500-5000, and a carrier oil component comprising a mono end capped polypropylene glycol ether having a mol.wt. in the range 500-5000 or an ester thereof.

Certain combinations of polyisobutenyl succinimides and mono end capped polypropylene glycol ethers/esters are not compatible with each other. As those skilled in the art will appreciate it is possible to produce a broad range of fully miscible formulations by appropriate combination of particular succinimide detergents and particular polyoxyalkylene carrier fluids.

EP 588429 discloses a gasoline composition comprising a minor amount of a polyalphaolefin having a viscosity at 100°C of 2-20cSt, and a minor amount of a polyoxyalkylene compound selected from glycols, mono and diethers thereof, having a number average mol.wt. in the range 400-3000. The composition additionally contains a minor amount of an ashless dispersant, preferably a polyolefin substituted succinimide wherein the polyolefin has a number average mol.wt. in the range 800-5000. The patent discloses that instability/immiscibility between a particular succinimide and a particular polyoxyalkylene compound can be overcome by the addition of the polyalphaolefin component.

US 5,298,039 discloses a gasoline composition comprising

(a) from 10-5000ppm of a nitrogen containing detergent component which is or contains a polyisobutylamine and

(b) from 10-5000ppm of a dialkyl phenol initiated alkoxylate. The thrust of this patent is that full miscibility is obtained between the detergent and the dialkyl alkoxylate compared to the mono alkyl alkoxylate which is immiscible with the detergent.

US 5,405,419 discloses the use of polyolefin amine detergents, polyolefins and mono end capped polypropylene glycols in detergent compositions.

GB 2261441 discloses a fuel composition for controlling engine deposits which comprises (a) a polyoxyalkylene compound having a mol.wt. of 200-5000 and (b) a hydrocarbyl succinimide. An additive concentrate containing (a) and (b) may be made up with a mineral oil.

US 3,901,665 discloses a liquid hydrocarbon fuel composition comprising (a) from 0.01-0.06%wt of a 3 or 4 carbon olefin, preferably polyisobutene with a mol.wt. from 400-1400, preferably about 400-900 and (b) from 0.008-0.016%wt of a polyoxyalkylene compound of formula R(OCH2CH(CH3) )xOH, where R is C_1-20 alkyl, preferably ^cιo-ιβ ^{an< x nas a} value of 4-20. The additives are effective as anti-icing agents, as carburettor detergents and can reduce intake valve deposits.

US 3,658,494 discloses a fuel composition comprising an additive combination of (a) an oxy compound which is a monoether of a glycol or polyglycol and (b) a dispersant which could be a succinimide. In the examples the oxy compounds are typically ethylene glycol monobutyl ether.

JP 5117671 discloses an additive composition to reduce intake valve deposits comprising a mixture of mono and bis succinimides, a polyoxyalkylene glycol or an ether thereof and a lubricating oil fraction having a viscosity of 3-35cst at 100°C. The polyoxyalkylene glycols and their ethers are of average mol.wt. of 500- 5000.

OBJECT OF THE INVENTION

It is an object of the present invention to provide combinations of additives for gasoline engines which are highly effective detergents, for example synergistically effective in detergency, and are also compatible with each other i.e. do not separate, thereby ensuring no problems with valve stem sticking, package instability and water tolerance.

SUMMARY OF INVENTION

The present invention provides a novel fuel additive composition comprising a combination of a polyisobutenyl succinimide as a detergent/dispersant and a carrier fluid which is a polyintemal olefin, optionally together with a polyalkylene glycol .

Among other factors, the present invention is based on the surprising discovery that the unique combination of a polyisobutenyl succinimide and a polyintemal olefin optionally also including a polyalkylene glycol provides compositions that are highly effective, for example synergistically effective in detergency, and also compatible with one another i.e. do not separate.

DETAILED DECRIPTION

The present invention thus provides a gasoline comprising (i) from 10 to 5000 ppm by weight, preferably 50 to 1000 ppm by weight of a polyisobutenyl succinimide wherein the polysiobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 500 to 5000, and (ii) from 10 to 5000 ppm by weight, preferably 50 to 1500 ppm by weight, of a carrier oil comprising a polyintemal olefin having a viscosity of 4 to 20 cst at 100°C.

Preferably the carrier oil comprises a combination of said polyintemal olefin and a polyalkylene glycol of formula R' -O- (RO) n-R" where R' and R" independently represent hydrogen atoms or hydrocarbyl groups of up to 30 carbon atoms and R represents a C₂.₈ alkylene radical, having a molecular weight in the range 500 to 5000, wherein the weight ratio of said polyintemal olefin to said polyoxyalkylene glycol is in the range 0.1:1 to 1:0, preferably 0.1:1 to 10:1.

The invention also provides an additive composition suitable for addition to a hydrocarbon fuel, particularly a gasoline, comprising (i) a polyisobutenyl succinimide detergent wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 500 to 5000; (ii) a carrier oil comprising a polyintemal olefin having a viscosity of 4 to 20 cSt at 100^CC, and optionally a polyalkylene glycol of formula R' -O- (RO)n-R" where R' and R" independently represent hydrogen atoms or hydrocarbyl groups of up to 30 carbon atoms and R represents a C₂.₈ alkylene radical, having a molecular weight in the range 500 to 5000; and (iii) optionally a hydrocarbon solvent having a boiling point in the range 66 to 270°C wherein the weight ratio of (ii) to (i) is in the range 0.2:1 to 5:1 the weight ratio of said polyintemal olefin to said polyoxyalkylene glycol is in the range 0.1:1 to 1:0, preferably 0.1:1 to 10:1, and the hydrocarbon solvent is present in an amount from 0 to 70% by weight of the total composition, preferably 20 to 70% by weight. As used herein, "gasoline" refers to motor fuels meeting ASTM Standard D-439, and includes blends of distillate hydrocarbon fuels with oxygenated fuels, such as ethanol, as well as the distillate fuels themselves. The fuels may be leaded or unleaded, and may contain, in addition to the additive compositions of this invention, any of the other additives conventionally added to gasolines as, for example, scavengers, anti-icing additives, octane requirement improvers etc.

PgTERSENT

As indicated, the detergent component in this invention is a polyisobutenyl succinimide obtained for example by reacting a polyisobutenyl substituted succinic acid or anhydride with a polyalkylenepolyamine.

The polyisobutenyl substituent of the succinimide will generally have a number average molecular weight within the range 500-5000, preferably 800-1300.

The preparation of the polyisobutenyl substituted succinic anhydrides may be effected by reacting a polyolefin of appropriate molecular weight (with or without chlorine) with maleic anhydride by analogy to processes known in the art. Suitable processes include thermally reacting a polyolefin with maleic anhydride (see for example US patents 3,361,673 and 3,018,250) and reacting a halogenated, in particular a chlorinated, polyolefin with maleic anhydride (see for example US patent 3,172,892). Alternatively, the alkenyl substituted succinic anhydride can be prepared by mixing the polyolefin with maleic anhydride and passing chlorine through the mixture (see for example GB 949,981) .

The alkyl or alkenyl substituted succinimides may be made by reaction of the desired hydrocarbyl substituted succinic acid or anhydride with a suitable polyalkylene polyamine of formula :

H₂N- (RNH) _n-R-NH₂

where R is an alkylene radical from 1 to 5 carbon atoms; n is an integer whose value or average value is 1 to 10, preferably 1 to 6. The preferred polyalkylene polyamines are polyethylene polyamines of formula:

H₂N(CH₂CH₂NH)_XH

where x is 1 to 6. They include for example ethylene diamine, diethylene diamine, triethylene tetramine, tetraethylene pentamine and pentaethylene hexamine. As will be appreciated this reactant may be a commercially available mixture which can contain amounts of branched and cyclic species.

Usually the polyisobutenyl substituted succinic acid or anhydride will be reacted with the polyalkylenepolyamine in a molar ratio from 0.2:1 to 5:1, preferably 0.2:1 to 2.5:1 and most preferably from 1:1 to 2:1. The reaction will usually be carried out at a temperature of at least 80°C, and preferably at a temperature in the range 125 to 250°C. Usually the detergent component will be added to the additive compositions of this invention in admixture with an aromatic solvent and containing from 20-70% by weight or more of the active detergent.

As used herein, the term succinimide is meant to encompass all the reaction products which may be obtained by reacting a hydrocarbyl substituted succinic acid or anhydride with a polyalkylenepolyamine such as amides, salt linkages, etc, in addition to the imide linkage of the type that results from the reaction of the primary amino group and the anhydride moiety. It will be appreciated that commercially available materials may contain a greater or lesser amount of such alternative linkage reaction products and these commercially available mixtures are of course included in the term "succinimide".

C RRIER Ol

The polyintemal olefins used in the invention are branched isoparaffins. They are commonly mixtures of dimers (for example 40-95% w/w) , trimers (for example 5- 45% w/w) and tetramers (for example 0-15% w/w) of C₁₂- C₂₀, preferably C₁₅-C₁₆, internal olefins, that is olefins wherein the olefinic linkage is other than in the alpha position, and thus they possess branching ratios (CH₂/CH₃) somewhat different from branching ratios of polyalpha olefins.

As stated above the polyintemal olefins have viscosities of 4 to 20 cSt at 100°C. A suitable source for such materials is Mixoil SpA in Milan, Italy.

The polyoxyalkylene compounds optionally present in the carrier oil may be represented by the following formula

R'-O- (RO)n-R"

where R¹ and R" independently represent hydrogen atoms or hydrocarbyl groups of up to 30 carbon atoms, i.e. including glycols, mono and diethers thereof, having a molecular weight in the range 500 to 5000. R represents a C₂-₈ alkylene radical, preferably propylene.

The preferred compounds are polypropylene glycol monoethers represented by the formula,

RO(CH₂CH(CH₃)0)_nH

where R' is a hydrocarbyl group of up to 30 carbon atoms, preferably straight chain C_x.₃₀ alkyl, more preferably straight chain C₄.₂₀ alkyl and most preferably ^ci₂-i₈ alkyl, and n is an integer whose value or average value is in the range 10-50, preferably 12 to 20.

DILUENT

An additional component of the additive compositions of this invention may be a diluent or solvent added primarily to reduce the viscosity of the mix, thereby to improve its handling properties and to facilitate the blending of the additive with the gasoline. Generally the solvent will be an aromatic hydrocarbon having a boiling point in the range 66 to 270°C, e.g. toluene or xylene or more especially the aromatic solvent mixtures sold by Shell under the trade marks Shellsol AB, Shellsol R and by Esso under the trade mark Solvesso 150, and boiling in the range 180 to 270°C. The amount of solvent to be incorporated will depend upon the desired final viscosity, but will usually be from 20 to 70% of the final composition on a weight basis.

MINOR INGREDIENTS

As indicated, the gasolines of the present invention will usually contain a number of minor ingredients, often added to meet specific customer requirements. Included amongst these are dehazers, usually an alkoxylated phenol formaldehyde resin, added to minimise water adsorption and to prevent a hazy or cloudy appearance, and a corrosion inhibitor, usually of the type comprising a blend of one or more fatty acids and amines. Either or both can also be present in the additive compositions of the present invention in amounts ranging from 1 to 5%, usually 1 to 3% each, based on the total weight of the composition.

Other specific purpose minor ingredients which may be added to the gasolines or to the additive compositions include anti-oxidants, anti-icing agents, anti-foam agents, metal deactivators, dyes and the like. In general terms the total amount of such minor functional ingredients in the additive compositions will not exceed about 10% by weight, more usually not exceeding about 5% by weight.

Such minor additives are conventional in the art.

The additive compositions of this invention are blended into gasoline in amounts sufficient to provide from 10 to 5000 ppm (weight basis) of active detergent in the gasoline. Preferred amounts range from 50 to 1000 ppm. The quantity of carrier oil incorporated in the gasoline will usually be in the range 10 to 5000 ppm (weight basis) , preferably 50 to 1500 ppm.

The invention will be further understood from the following illustrative examples which are not to be construed in any way as limiting the scope of the invention.

In the examples which follow, amounts of detergent are quoted as amounts of solution.

Additive concentrates in accordance with the invention and comparative examples were prepared and the results are presented in Tables 1-3. PG is polyalkylene glycol. PIO is polyinte al olefin. The aromatic solvent used throughout is Shellsol AB as described above.

TABLE 1

EXAMPLE Detergent PG PIO (g) Ratio COMMENTS

(g) (9) PG: PIO

1 6.7 4 -- 1:0 immiscible

2 6.7 2 2 1:1 clear

3 6.7 3 1 3:1 immiscible

4 6.7 1 3 1:3 clear

5 6.7 -- 4 0:1 clear

6 6.7 4 4 1:1 clear

7 10 20 -- 1:0 immiscible

8 10 10 10 1:1 clear

9 10 2 -- 1:0 clear

10 10 4 -- 1:0 immiscible

11 10 6 -- 1:0 immiscible

12 6.7 4 -- 1:0 immiscible

13 6.7 2 2 1:1 clear

14 6.7 4 -- 1:0 immiscible

15 6.7 2 2 1:1 clear

TABLE 2

EXAMPLE Detergent PG PIO (g) Ratio COMMENTS

⁽g⁾ (g) PG: PIO

16 8.3 5 - 1:0 clear

17 8.3 5 - 1:0 clear

18 6.7 8 - 1:0 turbid

19 6.7 7 1 7:1 turbid

20 6.7 6 2 3:1 miscible

21 6.7 4 - 1:0 immiscible

22 6.7 2 2 1:1 clear

23 6.7 3 1 3:1 immiscible

24 6.7 1 3 1:3 clear

27 6.7 4 - 1:0 immiscible

28 6.7 2 2 1:1 clear

29 6.7 3 1 3:1 clear

30 6.7 4 - 1:0 immiscible

31 6.7 2 2 1:1 clear

32 6.7 3 1 3:1 clear

33 6.7 4 - 1:0 immiscible

34 6.7 2 2 1:1 clear

35 6.7 3 1 3:1 clear

TABLE 3

EXAMPLE Detergent PG PIO (g) Ratio COMMENTS

⁽g) (g) PG: PIO

38 6.7 4 - 1:0 immiscible

39 6.7 2 2 1:1 immiscible

40 6.7 1 3 1:3 turbid

41 6.7 0.5 3.5 1:7 clear

42 6.7 4 - 1:0 clear

43 6.7 4 - 1:0 clear

44 6.7 4 - 1:0 immiscible

45 6.7 2 2 1:1 clear

46 6.7 3 1 3:1 immiscible

COMPOSITION DESCRIPTIONS

Table 1 shows comparative examples where the detergent is a 60%w/w solution in an aromatic solvent of the reaction product of a polyisobutylene succinic anhydride in which the polyisobutene has a number average mol.wt. from 940-1000 and a polyamine which is tetraethylene pentamine in a molar ratio of anhydride:amine of 1.7:1.0.

The PG is a polypropylene glycol monoether prepared using a C₁₂.₁₅ alcohol initiator, having a mol.wt. in the range 1200-1500 and a kinematic viscosity at 40°C in the range 55-66cst.

The PIO is a polyintemal olefin having a viscosity at 100°C of 6cst.

Compositions 1-11 have also been prepared using PIO's having viscosities of 4 and 8cst @ 100°C.

Compositions 12 and 13 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide derived from a polyisobutene succinic anhydride in which the polyisobutene has a number average mol.wt. from 940-1000 and a polyamine which is tetraethylene pentamine in a molar ratio of 1.0:1.0.

Compositions 14 and 15 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide derived from a polyisobutene succinic anhydride in which the polyisobutene has a number average mol.wt. from 940-1000 and a polyamine which is tetraethylene pentamine in a molar ratio of 2.0:1.0.

Table 2 shows illustrative examples of the invention using different succinimide chemistries.

Composition 16 contains a 60%w/w solution in an aromatic solvent of polyisobutene succinimide derived from a polyisobutene succinic anhydride in which the polyisobutene has a number average mol.wt. around 780 and a polyamine which is tetraethylene pentamine in a molar ratio of 1.0:1.0.

Composition 17 contains a 60%w/w solution in an aromatic solvent of polyisobutene succinimide derived from a polyisobutene succinic anhydride in which the polyisobutene has a number average mol.wt. around 780 and a polyamine which is tetraethylene pentamine in a molar ratio of 2.0:1.0.

Compositions 18-20 contains a 60%w/w solution in an aromatic solvent of polyisobutene succinimide derived from a polyisobutene succinic anhydride in which the polyisobutene has a number average mol.wt. around 780 and a polyamine which is tetraethylene pentamine in a molar ratio of 1.6:1.0.

Compositions 21-24 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide in which the polyisobutene has a number average mol.wt. around 1300 and polyamine which is tetraethylene pentamine in a molar ratio of 1.6:1.0.

Compositions 27-29 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide in which the polyisobutene is derived from a polyisobutene of number average mol.wt. from 940-1000 and a polyamine which is pentaethylene hexamine in a molar ratio of 1.6:1.0.

Compositions 30-32 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide in which the polyisobutene is derived from a polyisobutene of number average mol.wt. from 940-1000 and a polyamine which is diethylene tetramine in a molar ratio of 1.6:1.0

Compositions 33-35 contain a 60%w/w solution in an aromatic solvent of polyisobutene succinimide in which the polyisobutene is derived from a polyisobutene of number average mol.wt. from 940-1000 and a polyamine which is triethylene tetramine in a molar ratio of 1.6:1.0.

Table 3 shows illustrative examples of the invention using a range of glycol chemistries.

Compositions 38-41 contain a 60%w/w solution of a polyisobutene succinimide derived from 940-1000 mol.wt. polyisobutene and tetraethylene pentamine in a molar ratio of 1.4:1.0. The carrier is a polypropylene glycol of mol.wt. around 1000.

Compositon 42 contains a 60%w/w solution of a polyisobutene succinimide derived from 940-1000 mol.wt. polyisobutene and tetraethylene pentamine in a molar ratio of 1.7:1.0. The carrier is a polypropylene glycol monoether prepared using a C12-15 alcohol initiator, having a molecular-weight around 700 and a kinematic viscosity at 40°C around 28cst.

Composition 43 contains the same succinimide detergent as in example 42 but the carrier is a polybutylene glycol monoether prepared from a C12 alcohol and has a kinematic viscosity at 40°C of 41 cst.

Compositions 44-46 contain the same succinimide as in example 42 but the carrier is a polypropylene glycol monoether having a viscosity at 40°C of 95cst.

WATER TOLERANCE TESTING

Compositions are evaluated by shaking 20ml of the package under investigation with 1ml of water. After leaving overnight in a freezer at -18°C the packages are observed for signs of separation. Any separation is regarded as a fail by this test.

Composition Result

1 Fail

2 Pass

21 Fail

22 Pass

27 Fail

28 Pass 42 Pass

5 Pass

30 Fail

31 Pass

44 Fail

45 Pass

Claims

Claims :

1. A gasoline comprising i) from 10 to 5000 ppm by weight of a polyisobutenyl succinimide wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 500 to 5000; and ii) from 10 to 5000 ppm by weight of a carrier oil comprising a polyintemal olefin having a viscosity of 4 to 20 cSt at 100°C.

2. A gasoline according to claim 1 comprising from 50 to 1000 ppm by weight of the polyisobutenyl succinimide.

3. A gasoline according to claim 1 comprising from 50 to 1500 ppm by weight of the carrier oil.

4. A gasoline according to any of the preceding claims wherein the carrier oil comprises a combination of said polyintemal olefin and a polyalkylene glycol of formula:

R'-O- (RO)_n-R"

wherein R' and R" independently represent hydrogen atoms or hydrocarbyl groups of up to 30 carbon atoms and R represents a C₂-₈ alkylene radical, having a molecular weight in the range 500 to 5000, wherein the weight ratio of said polyintemal olefin to said polyalkylene glycol is in the range 0.1:1 to 1:0.

5. A gasoline according to claim 4 wherein said weight ratio is 0.1:1 to 10:1.

6. An additive composition suitable for addition to a hydrocarbon fuel comprising i) a polyisobutenyl succinimide detergent wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 500 to 5000; and ii) a carrier oil comprising a polyintemal olefin having a viscosity of 4 to 20 cSt at 100°C;

wherein the weight ratio of ii) to i) is in the range 0.2:1 to 5:1.

7. An additive composition according to claim 6 wherein the carrier oil further comprises a polyalkylene glycol of formula R' -0- (R0)_n-R" wherein R¹ and R" independently represent hydrogen atoms or hydrocarbyl groups of up to 30 carbon atoms and R represents a C₂.₈ alkylene radical, having a molecular weight in the range 500 to 5000.

8. An additive composition according to claim 7 wherein the weight ratio of said polyintemal olefin to said polyalkylene glycol is in the range 0.1:1 to 1:0.

9. An additive composition according to claim 7 wherein the weight ratio of said polyintemal olefin to said polyalkylene glycol is in the range 0.1:1 to 10:1.

10. An additive composition according to any one of claims 6 to 9 further comprising a hydrocarbon solvent having a boiling point in the range 66 to 270°C.

11. An additive composition according to claim 10 wherein said hydrocarbon solvent is present in an amount from 0 to 70% by weight of the total composition.

12. An additive composition according to any one of claims 6 to 11 wherein the polyisobutenyl substituent of the succinimide has a number average molecular weight (Mn) in the range 800 to 1300.

13. An additive composition according to claim 7 wherein the polyalkylene glycol is represented by the formula:

R'-O- (CH₂CH(CH₃)0)_n-H

wherein R' is a hydrocarbyl group of up to 30 carbon atoms and n is an integer whose value or average value is in the range 10 to 50.

14. A composition as claimed in any one of the preceding claims further comprising a number of minor functional ingredients in an amount not exceeding 10% by weight.