Background Art Adhesion of a deposit to the intake valves and combustion chamber walls of an internal combustion engine exerts adverse influences on the engine functions, exhaust gas, etc. Various additives are hence added to fuel oils for detergent purposes such as the removal of deposits, deposition prevention, and cleaning.

For example, monoamino ether compound type additives and polyamino ether compound type additives are disclosed in U. S.

Patent 3,440,029, European Patent 310,875, JP-B-56-48556 (the term"JP-B"as used herein means an"examined Japanese patent publication"), JP-A-3-128933 (the term"JP-A"as used herein means an"unexamined published Japanese patent application"), JP-A-3-229797, JP-A-6-322381, etc.

This kind of amino ether compounds basically show a satisfactory cleaning effect. However, their cleaning effect is

insufficient under severe driving conditions including repetitions of frequent acceleration and deceleration, and a further improvement in performance is desired. In addition, these compounds have a problem, for example, that they give reaction products containing halogens such as chlorine. The halogens (especially chlorine) remaining in the reaction products yield acid gases and the like, and this may cause problems such as metal corrosion within the engine.

Disclosure of the Invention Accordingly, an object of the present invention is to provide a detergent for fuel oils which has excellent detergency and has no fear of corroding metals or other materials.

Another object of the present invention is to provide a fuel oil composition.

The present inventors made intensive investigations in order to accomplish the above objects. As a result, they have found that a specific polyether compound exhibits excellent effects when used as or in a fuel oil detergent or fuel oil composition. The present invention has been achieved based on this finding.

The present invention provides a detergent for fuel oils which comprises a polyether compound (A) represented by the following general formula (1), the polyether compound (A) having a weight-average molecular weight of from 1,000 to 3,500, a hydroxyl value of from 15 to 40, a solubility parameter (SP value) of from 8.8 to 9.4, an HLB value of from 2.5 to 6.0, a viscosity

at 40°C of 700 mm2/s or lower, and a chlorine content of 10 ppm by mass or lower. The present invention further provides a fuel oil composition containing the detergent.

H2N~ (C2H40) m~ (XO) n-H (1) In general formula (1), X represents an alkylene group having 2 to 4 carbon atoms; m represents an integer of 1 to 3; and n represents an integer of 15 to 50.

Best Mode for Carrying out the Invention The detergent and composition will be explained below in detail.

In general formula (1), which represents the polyether compound (A) according to the present invention, X is an alkylene group having 2 to 4 carbon atoms (e. g., ethylene, propylene, or butylene) and is preferably a propylene or butylene group. If X is the alkylene group having one carbon atom, the polyether compound may have poor solubility in fuel oils. If the number of carbon atoms in X exceeds 4, the polyether compound may have a lessened cleaning effect. Consequently, such too small or too large carbon atom numbers are undesirable. Furthermore, m is an integer of 1 to 3, preferably 1, and n is an integer of 15 to 50, preferably 20 to 50, more preferably 25 to 40. If n is smaller than 15, the effect of cleaning combustion chambers may be lessened. If n exceeds 50, the effect of cleaning intake valves may be lessened. Consequently, the values of n outside the above range are undesirable.

The weight-average molecular weight of the polyether

compound (A) is from 1,000 to 3,500, preferably 1,300 to 3,500, more preferably from 1,500 to 3,250, more preferably from 1,500 to 3,000. If the weight-average molecular weight thereof is lower than 1,000, the effect of cleaning combustion chambers may be lessened. If it exceeds 3,500, the effect of cleaning intake valves may be lessened. Consequently, the molecular weights thereof outside the above range are undesirable. The term molecular weight herein means weight-average molecular weight measured by gel permeation chromatography and calculated for polyethylene.

The hydroxyl value of the polyether compound (A) is from 15 to 40, preferably from 18 to 35, more preferably from 20 to 30. If the hydroxyl value thereof is lower than 15, the effect of cleaning combustion chambers may be lessened. If it exceeds 40, the effect of cleaning intake valves may be lessened.

Consequently, the hydroxyl values thereof outside the above range are undesirable.

The solubility parameter (SP value) of the polyether compound (A) is from 8.8 to 9.4, preferably from 8.8 to 9.2, more preferably from 8.8 to 9.0. If the SP thereof is lower than 8.8 or exceeds 9. 4, the polyether compound may have reduced solubility in fuel oils and a lessened cleaning effect. Consequently, the SP values thereof outside the above range are undesirable. The values of solubility parameter (SP) in the present invention are those calculated by the Fedors method Polym. Eng. Sci., 14 (2) 152, (1974)].

The HLB value of the polyether compound (A) is from 2.5

to 6.0, preferably from 3.0 to 5.5, more preferably from 3.5 to 5.0. If the HLB value of the compound (A) is lower than 2.5, the polyether compound may have reduced solubility in gasolines and a lessened cleaning effect. If it exceeds 6.0, the polyether compound has reduced separability from water and may pose problems such as corrosion and rusting in fuel tanks, engines, etc.

Consequently, the HLB values thereof outside the above range are undesirable. The values of HLB in the present invention are those calculated by the Oda method (described in Oda and Terada,"Kaimen Kasseizai No Gosei To Sono oyo (Synthesis and Application of Surface Active Agents)", p. 501, published by Maki Shoten (1957)).

The viscosity at 40°C of the polyether compound (A) is 700 mm2/s or lower, preferably 500 mm'/s or lower, more preferably 350 mm2/s or lower. The lower limit of the viscosity at 40°C of the polyether compound (A) is preferably 10 mm'/s, more preferably 30 mm2/s, mostpreferably50mm2/s. Viscositiesthereofexceeding 700 m2/s are undesirable in that the polyether compound having such a high viscosity may have a lessened cleaning effect.

Although the 100°C viscosity of the polyether compound (A) is not particularly limited, it isgenerallyl00mm2/sorlower, preferably 80 mm2/s or lower, more preferably 50 mm2/s or lower.

The lower limit of the viscosity at 100°C of the polyether compound (A)ispreferablylmm2/s, morepreferably 5mm2/s, mostpreferably 10 mm2/s.

The chlorine content of the polyether compound (A) is 0 to 10 ppm by mass, preferably 0 to 7 ppm by mass, more preferably 0 to 5 ppm by mass. Chlorine contents thereof exceeding 10 ppm

by mass are undesirable in that the polyether compound having such a high chlorine content may pose problems such as metal corrosion in engines.

Methods for synthesizing the polyether compound (A) are not particularly limited. However, from the standpoint of avoiding the use of any dangerous compound (hydrogen gas, ammonia, halogen, etc.), a preferred method is to synthesize the compound (A) by hydrolyzing an imino group-containing polyether compound.

A more preferred synthesis method is to hydrolyze an imino group-containing polyether compound represented by the following general formula (2).

R'R2C=N- (C2H40) m- (XO),-H (2) In general formula (2), R'and R'each represents a hydrocarbon group having 1 to 8 carbon atoms, provided that in at least one of Rl and R2, the carbon atom adjacent to the imino group is secondary or tertiary carbon; X represents an alkylene group having 2 to 4 carbon atoms; m represents an integer of 1 to 3; and n represents an integer of 20 to 50.

Examples of the hydrocarbon group having 1 to 8 carbon atoms represented by each of Rl and R2 include methyl, ethyl, n-propyl, isopropyl, isobutyl, t-butyl, isooctyl, 2-ethylhexyl, and 1-phenylethyl. Examples of the alkylene group having 2 to 4 carbon atoms are the same as those enumerated hereinabove.

The imino group-containing ether compound can be synthesized, for example, by heating a compound having both a primary amino group and a hydroxyl group (e. g., monoethanolamine) together with a ketone to dehydrate the amino compound and thereby

obtain an imino compound containing an active hydrogen group and then etherifying the imino compound.

Examples of the ketone used above include methyl isobutyl ketone, diisopropyl ketone, diisobutyl ketone, and di-t-butyl ketone.

The reaction for introducing an imino group can be conducted by an ordinary method. For example, the hydroxyl- containing primary amine compound is heated to 100 to 140°C in the presence of a ketone in an amount of from 0.5 to 2 equivalents to the primary amino group of the amine compound to dehydrate the same, whereby the imino compound containing an active hydrogen group can be easily obtained. This reaction may be conducted in the presence of a reflux solvent forming an azeotrope with water, such as toluene.

The etherification reaction can be carried out by adding an alkylene oxide to the hydroxyl-containing ketimine compound with heating, if desired in an appropriate solvent (e. g., toluene or xylene), in the presence of a catalyst (e. g., sodium hydroxide or potassium hydroxide). The reaction temperature is generally from 70 to 140°C, preferably from 90 to 130°C.

If the ketimine compound containing an active hydrogen group is one obtained with a ketone showing reduced steric hindrance (e. g., acetone, methyl ethyl ketone, or diethyl ketone), there are cases where side reactions thought to be attributable to imino group elimination proceed in the above reaction at temperatures exceeding 80°C to yield by-products (secondary amine compounds, etc.). However, in the case where the ketimine

compound containing an active hydrogen group is one obtained through imino introduction with a ketone showing enhanced steric hindrance, as in the present invention, such side reactions can be inhibited to an exceedingly low level and a compound having excellent detergency is finally obtained.

By hydrolyzing the above-described imino group- containing ether compound, a polyether compound (A) is obtained which has both a primary amino group and a hydroxyl group and is represented by general formula (1).

H,N-(C,H,0),-(XO),-H(1) In general formula (1), X represents a hydrocarbon group having 2 to 4 carbon atoms; m represents an integer of 1 to 3; and n represents an integer of 15 to 50.

The hydrolysis is accomplished, for example, by heating the ether compound in the presence of excess water. The reaction temperature is generally from 90 to 140°C, preferably from 95 to 125°C The ether compound (A) containing a primary amino group is not particularly limited in weight loss on pyrolysis. However, from the standpoint of detergency, the ether compound (A) generally has a weight loss on pyrolysis at 200°C of below 5 wt% and a weight loss on pyrolysis at 300°C of 95 wt% or more when heated from room temperature at a rate of 25 °C/min. Preferably, the weight loss on pyrolysis thereof at 200°C is below 3 wt% and that at 300°C is 97 wt% or more. More preferably, the weight loss on pyrolysis thereof at 200°C is below 1 wt% and that at 300°C is 99 wt% or more.

A second ingredient such as, e. g., a carrier oil, may be incorporated into the fuel oil detergent of the present invention.

Examples of the second ingredient include aromatic hydrocarbons (e. g., toluene, xylene, triethylbenzene, and ethylbenzene), aliphatic hydrocarbons (e. g., decane, decene, dodecane, dodecene, and cyclohexane), and hetero group-containing hydrocarbons (e. g., pyridine, pyrrolidone, morpholine, and dimethylformamide). The second ingredient (B) preferably is such a hydrocarbon having an SP of from 8.8 to 9.6, a flash point of from 40 to 100°C, and a boiling point of from 150 to 250°C from the standpoints of solubility in gasolines and detergency. More preferably, the second ingredient (B) is an aromatic hydrocarbon having an SP value of from 8.8 to 9.6, a flash point of from 40 to 100°C, and a boiling point of from 150 to 250°C.

The amount of the second ingredient (B) which may be contained in the fuel oil detergent of the present invention is such that the weight ratio of (B)/ (A) + (B)] is generally from 0 to 0.97, preferably from 0.10 to 0.95.

The fuel oil additive of the present invention, which comprises the polyether compound (A), can be added to various fuel oils, e. g., all fuels usable for internal combustion engines, including petroleum fractions, alcohols, LNG, and vegetable oils.

Preferably, the detergent is added to the gasolines and gas oil for use in internal combustion engines. In this case, the detergent is exceedingly effective in cleaning the intake system and combustion chambers of a gasoline engine and in cleaning the injection nozzles and combustion chambers of a Diesel engine.

More preferably, the detergent is added to the gasolines for use in internal combustion engines.

The gasolines for use in internal combustion engines are not particularly limited. However, the gasolines generally are nonleaded gasolines, and are preferably those which satisfy all of the following requirements (1) to (11) and at least one of the following requirements (12) to (14).

(1) to have a research octane number of 89 or higher; (2) to have a sulfur content of 80 ppm by mass or lower; (3) to have a 50% running temperature of from 75 to 100°C; (4) to have a 90% running temperature of from 110 to 160°C; (5) to have a distillation termination point of from 130 to 210°C; (6) to have an unwashed gum content of 20 mg/100 ml or lower and a washed gum content of 3 mg/100 ml or lower; (7) to have an oxygenic compound content of from 0 to 2.7 wt% in terms of oxygen atom amount; (8) to have a density (15°C) of from 0.715 to 0.770 g/cm3; (9) to have a total calorific value of 40,000 J/g or higher; (10) to have an oxidative stability of 480 minutes or higher; (11) to have a copper plate corrosion of 1; (12) to have the following aromatic contents: 1 V (Ar): s35 vol% [2] V (Bz): 0-5 vol% 3 V (Tol): 0-25 vol% [4] V (C8A): 0-15 vol% 5 V (C9A): 0-15 vol% [6] V (C10+A): 0-15 vol%

7 [V (C9A) + V (C10+A)/ V (Tol) + V (C8A)]: 0-0.2 [8] V (PA) =0; or when V (PA) 0, V (MA)/V (PA) is 21; In 1 to [8] above, V (Ar), V (Bz), V (Tol), V (C8A), V (C9A), V (C10+A), V (MA), and V (PA) represent the contents of all aromatics, benzene, toluene, aromatics having 8 carbon atoms, aromatics having 9 carbon atoms, aromatics having 10 or more carbon atoms, monoalkyl-substituted aromatics, and aromatics substituted with 2 or more alkyl groups, respectively, based on the whole nonleaded gasoline.]; (13) to have the following aliphatic contents: [1] V (C5): 15-40 vol% [2] V (C6): 10-35 vol% 3 V (C7+P): 5-30 vol% [wherein V (C5), V (C6), and V (C7+P) represent the contents of aliphatic hydrocarbons having 5 carbon atoms, aliphatic hydrocarbons having 6 carbon atoms, and aliphatic hydrocarbons having 7 or more carbon atoms, respectively, based on the whole nonleaded gasoline]; (14) to have a content of hydrocarbons having 4 carbon atoms of from 0 to 5 vol%.

The amount of the fuel oil detergent of the present invention to be added to a fuel oil is not particularly limited.

However, from the standpoint of detergency, the addition amount thereof is generally from 50 to 20,000 ppm by mass, preferably from 70 to 10,000 ppm by mass, of the fuel oil.

If desired and necessary, other additives such as, e. g., an antioxidant, metal deactivator, rust preventive, and dehydrant

may be incorporated into the fuel oil containing the fuel oil detergent of the present invention.

Examples of the antioxidant include N, N'-diisopropyl- p-phenylenediamine, N, N'-diisobutyl-p-phenylenediamine, and hindered phenols such as 2,6-di-t-butyl-4-methylphenol.

Examples of the metal deactivator include amine/carbonyl condensation compounds such as N, N'-disalicylidene-1,2- diaminopropane. Examples of the rust preventive include organic carboxylic acids and derivatives thereof. Examples of the dehydrant include lower alcohols and sorbitan esters.

The present invention will be explained below in more detail by reference to Examples, but the invention should not be construed as being limited thereto.

The abbreviations used for feed materials in Examples and Comparative Examples have the following meanings.

[Amine Compounds] MEA: monoethanolamine DBA: dibutylmonoethanolamine [Ketone] DIBK: diisobutyl ketone [Alkylene Oxides] EO: ethylene oxide PO: propylene oxide BO: butylene oxide EXAMPLES 1 TO 6 Into a pressure reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet were introduced an

amine compound and the ketone in the respective amounts shown in Table 1. After the air present in the reactor was replaced with nitrogen gas, the contents were heated at 125°C for 8 hours to conduct dehydration and ketimine-forming reaction. After the ketimine-forming reaction, the reaction mixture was cooled to 60°C.

Thereto was added 13.0 g of potassium hydroxide as an addition catalyst. After the atmosphere in the reactor was replaced with nitrogen gas, the reactor was closed and the contents were heated to 100°C. Thereafter, the internal pressure was reduced to 2,000 Pa to remove the water containing the addition catalyst over 1.5 hours. Subsequently, the internal pressure was returned to ordinary pressure with nitrogen gas and the reactor was closed.

An alkylene oxide (AO-1) was added thereto in the amount shown in Table 1 and the resultant mixture was reacted at 125°C for 8 hours. Furthermore, an alkylene oxide (AO-2) was added thereto in the amount shown in Table 1 and the resultant mixture was reacted at 125°C for 8 hours. After completion of the reaction, the contents were cooled to 60°C, subsequently neutralized with hydrochloric acid, and then filtered to remove the addition catalyst. Thereafter, 80 g of water was added to the filtrate to conduct hydrolysis reaction at 105°C for 8 hours. Finally, the reaction mixture was heated to 120°C at ordinary pressure and the internal pressure was then reduced to 2,000 Pa to distill off the ketone and excess water over 1. 5 hours. The residue was cooled to room temperature to obtain an ether compound containing a primary amino group according to the present invention. The weight-average molecular weight, hydroxyl value, SP value, HLB value, 40°C viscosity, chlorine content, and weight loss on pyrolysis of the sample obtained are shown in Table 3.

Table 1 Amine Ketone Alkylene oxide Feed compound amount AO-1 AO-2 Example MEA DIBK BO 1425 g 1 61 g 142 g 1440 g (1 mol) (1 mol) (20 mol) Example MEA DIBK BO 2101 g 2 61 g 142 g 2160 g (1 mol) (1 mol) (30 mol) Example MEA DIBK EO BO 2152 g 3 61 g 142 g 44 g 2160 g (1 mol) (1 mol) (1 mol) (30 mol) Example MEA DIBK EO BO 2192 g 4 61 g 142 g 88 g 2160 g (1 mol) (1 mol) (2 mol) (30 mol) Example MEA DIBK PO 2285 g 5 61 g 142 g 2320 g (1 mol) (1 mol) (40 mol) _ Example MEA DIBK PO 2813 g 6 61 g 142 g 2900 g (1 mol) (1 mol) (50 mol)

EXAMPLE 7 To 800 g of the sample obtained in Example 2 was added 200 g of trimethylbenzene as a second ingredient. This mixture was homogenized by stirring to obtain a sample of Example 7.

COMPARATIVE EXAMPLES 1 TO 3 Into a pressure reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet were introduced an amine compound in the amount shown in Table 2 and 13.0 g of potassium hydroxide as an addition catalyst. After the atmosphere in the reactor was replaced with nitrogen gas, the reactor was closed and the contents were heated to 100°C.

Thereafter the internal pressure was reduced to 2, 000 Pa to remove the water containing the addition catalyst over 1.5 hours.

Subsequently, the internal pressure was returned to ordinary pressure with nitrogen gas. An alkylene oxide (AO-1) was added thereto in the amount shown in Table 2 and the resultant mixture was reacted at 125°C for 8 hours. After completion of the reaction, the contents were cooled to 60°C, subsequently neutralized with hydrochloric acid, and then filtered to remove the addition catalyst. Thus, polyether compounds were obtained as comparative samples 1 to 3. The weight-average molecular weight, hydroxyl value, SP value, HLB value, 40°C viscosity, chlorine content, and weight loss on pyrolysis of each of the samples obtained are shown in Table 3.

Table 2 Amine Alkylene Feed com- oxide Amount pound AO-1 Comparative DBA BO 1195 g Example 1 173 g 1440 g (1 mol) (20 mol) Comparative DBA BO 3193 g Example 2 173 g 2160 g (1 mol) (30 mol) Comparative DBA PO 3021 g Example 3 173 g 2900 g (1 mol) (50 mol) Table 3 Weight-Hydr-SP HLB 40°C Chlo-Weight loss average oxyl Value Value visco-rine on pyrolysis molecu-Value sity cont- (wt%) lar ent weight (Ppm by mass) 200°C 300°C Example 1600 37 8.95 4.0 120 2 0.5 99. 4 1 Example 2320 26 8.85 3.6 215 #2 0.3 99.4 2 Example 2330 25 8.86 3.7 218 #2 0.3 99.5 3 Example 2450 25 8.86 3.8 225 #2 0.4 99.6 4 Example 2500 24 8.92 4.9 248 s2 0.8 99. 8 5 Example 3040 19 8.86 4.8 320 s2 0.7 99. 6 6 Compa- rative 1700 33 8.82 3.6 125 #2 1.3 99.7 Example 1 Compa- rative 2500 22 8.76 3.5 220 #2 0.3 98.9 Example 2 Compa- rative 3150 16 8.76 4.3 324 2 0.3 94. 9 Example 3 1

The samples obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were examined for detergency through evaluation tests with an engine. The results obtained are shown in Table 4.

Evaluation Test 1 An automobile having a multipoint injection type engine having a total displacement of 2,000 cc was driven with a gasoline alone for 120 hours by repeating the following driving mode, in which one cycle took 30 minutes. Thereafter, the amount of the deposit adherent to the intake valves was measured.

Driving mode: idling (1 min)-1, 250 rpm (15 min) -2, 500 rpm (10 min)-stop (4 min) Subsequently, the intake valves were mounted without removing the deposit. The gasoline containing each of the samples in an amount of 100 ppm by mass was used to drive the automobile for 48 hours by repeating the above driving mode, in which one cycle took 30 minutes. After the test, the amount of the deposit adherent to the intake valves was measured. The difference between this deposit amount and the amount of the deposit adherent before the use of the gasoline containing the sample in an amount of 100 ppm by mass was determined, and this difference was taken as a measure of the effect of cleaning the intake system of deposits.

Evaluation Test 2 An automobile having a multipoint injection type engine having a total displacement of 2,000 cc was driven at 1,800 rpm for 120 hours using a gasoline containing each of the samples in

an amount of 100 ppm by mass. Thereafter, the amount of the deposit adherent to the combustion chamber walls was measured.

The difference between this deposit amount and the amount of the deposit adhering to the combustion chamber walls in driving with the gasoline containing none of the samples was determined.

Table 4 Evaluation Test 1 Evaluation Test 2 Difference in Difference in deposit amount deposit amount in in intake system combustion chambers (mg/intake valve) (mg/cylinder) Example 1-60.1-10.5 Example 2-63.4-10.9 Example 3-60.3-9.2 Example 4-62.9-7.8 Example 5-47.5-9.6 Example 6-35.5-4.9 Example 7-50.0-4.1 Comparative Example 1 +2.2 +15.2 Comparative Example 2 +3.9 +13.0 Comparative Example 3 +1.9 +18.5

Industrial Applicability The results of the above evaluations clearly show the following. The fuel oil additives of the Comparative Examples exerted adverse influences on detergency with respect to intake system deposits and combustion chamber deposits. In contrast, the fuel oil additives according to the present invention exhibited excellent detergency with respect to both intake system deposits and combustion chamber deposits.