KR20010042033A - Fuel oil additive and fuel oil composition - Google Patents

Abstract

(a) an additive for fuel oil having an outflow temperature of at least 320 ° C, comprising (a) an alkenylsuccinic acid imide compound or an alkylsuccinic acid imide compound or a boron adduct thereof, (b) a lubricant improving agent, and (c) An additive for fuel oil containing the low temperature fluidity improver, and a fuel oil composition formed by adding the fuel oil additive to the fuel oil. In particular, with respect to diesel fuel having a reduced sulfur content, there is provided an additive for fuel oil and a fuel oil composition containing the same having excellent performance in improving the lubricity of the fuel injection pump and the cleanliness of the fuel injection nozzle.

Description

FUEL OIL ADDITIVE AND FUEL OIL COMPOSITION}

In recent years, in order to cope with the exhaust gas regulation, it is required to reduce the sulfur content even in diesel engine diesel oil, and since October 1997, the content is regulated to 0.05% by weight or less. However, it has been found that the lubricating performance of the gas oil products obtained when depth desulfurization is performed on such a gas oil base for low sulfidation. In other words, it is reported that such deterioration of lubrication performance increases wear of each part of a fuel injection pump of a diesel engine having lubrication as diesel fuel, resulting in unreasonable factors such as poor engine rotation and poor operability. . This is because such deterioration in lubricity of the diesel fuel removes polar compounds such as a nitrogen component and an aromatic component which have been imparted with the sulfur component at the time of hydrodesulfurization to remove the sulfur component from the diesel fuel. Although such a reduction in the lubricating performance of light oil has been made on the hard side, on the other hand, a response from the fuel side is required, and a study on this has been made, and various lubricant improving agents have been developed and added.

In addition, the amount of sulfuric acid particles in the exhaust gas of a diesel vehicle can be reduced by the low sulfation of light oil. However, it is reported that particle emission is also increased by the deterioration of the cleanliness of a fuel injection nozzle. Therefore, the addition of various cleaning agents is examined.

Generally, the lubricity improver can improve the lubricity of the fuel injection pump, but does not contribute to the cleanliness of the fuel injection nozzle. On the other hand, the cleaning agent may contribute to the cleaning of the fuel injection nozzle, but hardly contributes to improving the lubricity of the fuel injection pump. For example, Japanese Laid-Open Patent Publication No. 97-272880 discloses low sulfur diesel oil in which fatty acid ester of sorbitan is added, but it does not contribute to the cleanliness of the fuel injection nozzle. In addition, Japanese Patent Laid-Open No. 97-255973 discloses low-sulfur diesel oil containing a salt of a carboxylic acid and an aliphatic amine and the like, which contributes to both the lubricity of the fuel injection pump and the cleanliness of the fuel injection nozzle. Is insufficient. In addition, Japanese Patent Publication No. 98-513208 (Exon Chemical, WO96 / 23855; published on August 8, 1996) is a fuel oil containing 95% by weight or less of sulfur and containing no more than 0.05% by weight of sulfur. And an additive composition comprising (a) an acylated nitrogen compound and (b) an carboxylic acid having 2 to 50 carbon atoms or an ester of the carboxylic acid and an alcohol, the additive comprising (a) and (b) The composition discloses to improve the lubricity of the fuel oil and at the same time improve the solubility in the fuel oil. Accordingly, there is a demand for the appearance of an additive having excellent performance in improving the lubricity of the fuel injection pump and the cleanliness of the fuel injection nozzle. In addition, the improvement of the lubricity of the fuel injection pump and the cleanliness of the fuel injection nozzle is particularly important even in light oil which has not undergone low sulfurization.

An object of the present invention has been made in view of the above, and particularly for fuel oils having an outflow temperature of 320% or higher at 90% of sulfur content, having excellent performance in improving the lubricity of the fuel injection pump and the cleanliness of the fuel injection nozzle. It is to provide an additive for fuel oil and a fuel oil composition containing the same.

The present invention relates to fuel oil additives and fuel oil compositions, and more particularly, to fuel additives added to diesel fuel for diesel engines used in automobiles, ships, generators, and the like, and fuel oil compositions including the same.

As a result of intensive studies, the present inventors have found that the object of the present invention can be effectively achieved by using an alkenylsuccinic acid imide compound or an alkylsuccinic acid imide compound or a boron adduct thereof as one component of an additive. The invention is completed.

That is, the gist of the present invention is as follows.

(1) A fuel oil additive having an outflow temperature of at least 90%, comprising (a) an alkenylsuccinic acid imide compound or an alkylsuccinic acid imide compound or a boron adduct thereof, and (b) a lubricant improving agent.

(2) An exit temperature of 90% at 320% comprising (a) an alkenylsuccinic acid imide compound or an alkylsuccinic acid imide compound or a boron adduct thereof, (b) a lubricity improver, and (c) a low temperature fluidity improver. Additives for fuel oil that are above ℃.

(3) The additive for fuel oil as described in (1) or (2) whose lubricity improver is 1 or more types of C4-C22 unsaturated fatty acid, its dimer acid, or ester esters thereof.

(4) The fuel oil composition formed by adding the fuel oil additive in any one of (1)-(3) to fuel oil.

(5) The fuel oil composition as described in (4) whose addition amount of component (a) is 20-1,500 weight ppm on the basis of the fuel oil composition total amount.

(6) The fuel oil composition as described in (4) or (5) whose addition amount of component (b) is 5-300 ppm by weight based on the total amount of fuel oil composition.

(7) The fuel oil composition according to any one of (4) to (6), wherein the amount of the component (c) added is 50 to 500 ppm by weight based on the total amount of the fuel oil composition.

(8) The fuel oil composition according to any one of (4) to (7), wherein the fuel oil is diesel diesel oil.

(9) The fuel oil composition according to (8), wherein the sulfur component content in diesel diesel oil is 0.001 to 0.05% by weight.

(10) The fuel oil composition according to (4), wherein the outlet temperature at 90% of the fuel oil is 320 ° C or higher.

(1 l) The fuel oil composition according to (4), wherein the outlet temperature at 90% of the fuel oil is at least 330 ° C.

(12) The fuel oil composition according to (4), wherein the outlet temperature at 90% of the fuel oil is 340 ° C or higher.

(13) The fuel oil composition according to (4), wherein the outlet temperature at 90% of the fuel oil is 350 ° C or higher.

EMBODIMENT OF THE INVENTION Below, this invention is demonstrated in detail.

First, the alkenylsuccinic acid imide compound or alkyl succinic acid imide compound of these (a) component which comprises the additive for fuel oils which is 1st invention of this application, or these boron adducts is demonstrated. As said alkenylsuccinic acid imide compound and an alkyl succinic acid imide compound, the monobody of following formula (1) and the bis | body of formula (2) are mentioned.

Where

R ¹ , R ³ and R ⁴ may be the same as or different from alkenyl or alkyl groups having a number average molecular weight of 300 to 4,000,

R ⁵ and R ⁶ may be the same as or different from the alkylene group having 2 to 4 carbon atoms,

m is an integer from 1 to lO,

n is 0 or an integer of 1-10.

In the above formulas (1) and (2), the number average molecular weight of R ¹ , R ³ and R ⁴ is preferably 500 to 2,000, more preferably 500 to 1,000 alkenyl groups or alkyl groups, and as the alkenyl group, a polybutenyl group And ethylene-propylene copolymers. Water is added to these as an alkyl group.

In the present invention, both of the above mono or bis bodies can be used.

The alkenylsuccinic acid imide compound and the alkyl succinic acid imide compound are reacted with a polyamine by reacting a polyalkenylsuccinic anhydride usually obtained by reaction of polyolefin with maleic anhydride or polyalkylsuccinic anhydride obtained by adding water thereto. It can manufacture. The mono- and bis-body can be produced by changing the reaction ratio of polyalkenylsuccinic anhydride or polyalkylsuccinic acid imide and polyamine. As an olefin monomer which forms the said polyolefin, 1 type (s) or 2 or more types of C2-C8 alpha olefin can be mixed and used. On the other hand, as a polyamine, single diamines, such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene hexamine, di (methylethylene) triamine And polyalkylene polyamines such as dibutylene triamine, tributylene tetraamine and pentapentylene hexaamine.

In addition, the thing manufactured by the said method can be used for the boron adduct of an alkenyl succinic acid imide compound or an alkyl succinic acid imide compound. The preferred content of boron in this boron adduct is 0.1 to 6% by weight, more preferably 0.1 to 4% by weight.

The said (a) component can be used 1 type or in combination of 2 or more types.

Next, the lubricity improver of (b) component which comprises 1st invention of this application is demonstrated. The lubricity improver used in the present invention refers to an additive which is blended for the purpose of lowering the coefficient of friction. Although not particularly limited, unsaturated fatty acids having 4 to 22 carbon atoms or dimer acids or ester esters thereof, and the above acids and ester esters thereof Mixtures are preferably used. The unsaturated fatty acid may be linear or branched, and examples thereof include caproleic acid, inderic acid, tzuzuic acid, milistleic acid, oleic acid, cord phosphoric acid, erucic acid, linoleic acid, linolenic acid, and the like. As alcohol used for esterification, methyl alcohol, ethyl alcohol, oleyl alcohol, glycerin, etc. are mentioned. In addition, the esterified product may be a partial esterified product.

In addition, amide compounds such as stearic acid amide, oleic acid amide, stearic acid bis (polyethylene glycol) amide, dodecylamine, stearic acid amine, stearic acid dimethylamine, cyclohexylamine, and dodecylbis (diethylene glycol) as lubricant improving agents Amine compounds such as amines; In addition to the above, phenyl-α-naphthylamine, bisoctylphenylamine, bisnonylphenylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethyl Amine compounds such as phenothiazine; Disulfides such as dibutyl disulfide, dioctyl disulfide, and dododecyl disulfide; Chlorinated hydrocarbons such as chlorinated paraffin wax, chlorinated naphthalene and chlorinated alkylbenzene; phosphinates such as n-butyldi-n-octyl phosphinate; Phosphonates such as di-n-butylhexyl phosphonate and di-n-butylphenyl phosphonate; Phosphates such as tributyl phosphate, tricresyl phosphate, trioleyl phosphate and di-2-ethylhexyl phosphate; 2, 6-di-t-butyl-P-cresol, 2, 2'-methylenebis (4-methyl-6-t-butylphenol), 2, 2'-methylenebis (4-ethyl-6-t- Butylphenol), 2, 5-di-t-amylhydroquinone, 2, 5-di-t-butyl hydroquinone, 4, 4'-thiobis (6-t-butyl-m-cresol), octadecyl- 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3, 5-di-t-butyl-4-hydroxy-benzyl phosphonate-diethyl ester, triethylene glycol Phenols such as bis [3- (3-t-butyl-5-methyl-5-hydroxyphenyl) propionate], and the like.

The said (b) component can be used 1 type or in combination of 2 or more types.

The ratio of the component (a) and the component (b) is preferably 90:10 to 10:90 in terms of weight ratio, and the additive for fuel oil of the first invention is kerosene and / or an aromatic solvent having about 8 to 10 carbon atoms. Dilution with a diluent, such as, and further additives, such as antioxidants, metal inerts, microbial fungicides, freezing inhibitors, antistatic agents, corrosion inhibitors, antifoams, rust preventives, flame retardants, colorants, markers, if necessary (a) It is manufactured by making the total amount of a component and (b) component into 20 to 80 weight% preferably.

In the fuel oil additive of the first aspect of the present invention, when the low-temperature fluidity improver is added as the component (c) in addition to the component (a) and the component (b), the lubricity of the fuel oil can be further improved. Although it does not specifically limit as a low temperature fluidity improving agent of (c) component, The ester of a nitrogen-containing compound which has a hydroxyl group, and a linear saturated fatty acid (JP-A-82-1790993), the said ester, an olefin, ethylenically unsaturated Polymers of one or two or more monomers selected from carboxylic acid alkyls and saturated fatty acid vinyls (JP-A-83-138791) are preferably used. In addition, ethylene-vinyl acetate copolymer, ethylene-alkyl alkylate, polyalkyl acrylate, alkenylsuccinic acid amide, etc. are mentioned as a low temperature fluidity improving agent.

The said (c) component can be used 1 type or in combination of 2 or more types.

It is preferable that the ratio of the said (c) component shall be 30-150 weight part with respect to 100 weight part of total amounts of (a) component and (b) component. The fuel oil additive is diluted with (a), (b) and (c) components with a diluent such as kerosene or an aromatic solvent having 8 to 10 carbon atoms, and further, an antioxidant, a metal inert agent and a microbial fungicide as necessary. Additives such as anti-icing agent, antistatic agent, corrosion inhibitor, antifoaming agent, rust preventive agent, antifoaming agent, colorant, marker and the like, and the total amount of the components (a), (b) and (C) is preferably 20 to 80% by weight. It is manufactured by.

2nd invention of this application is a fuel oil composition formed by adding the said fuel oil additive to fuel oil. Examples of the fuel oil composition include various hydrocarbon-based fuel oils, but gasoline or diesel diesel is preferable in view of the required performance, and diesel diesel is particularly preferable. The diesel diesel oil satisfies the Japanese Industrial Standards (Jls K2204), and particularly preferably contains 0.001 to 0.05% by weight of sulfur. Further, preferably, the kinematic viscosity at 30 ° C. is 1.7 mm ² / s or more, and for example, hydrogenated desulfurized diesel oil (DGO), hydrocracked diesel oil (HCGO) or a mixture thereof may be used to produce sulfur content in the above range. have.

The diesel diesel oil composition of the present invention preferably contains 0.001 to 0.05% by weight of a sulfur component, but if the sulfur component content is outside this range, the effect of the fuel oil additive may be reduced.

Moreover, as distillation property, the distillation temperature of 90% point is preferable 320 degreeC or more, More preferably, it is 330 degreeC or more, More preferably, it is 340 degreeC or more, Most preferably, it is 350 degreeC or more, When it becomes less than 320 degreeC, The effect of the fuel oil additive becomes small.

In general, the hydrogenated desulfurized diesel oil (DGO) has a boiling point in the range of 140 to 390 ° C, and the density thereof is suitably used in the range of 0.80 to 0.90. As the hydrogenated desulfurized diesel oil (LGO), a sulfur component of 0.005 to 0.5% by weight can generally be used, but a 0.05% by weight or less can be suitably used.

In addition, the hydrogenated desulfurized diesel oil (DGO), specifically, in the presence of a catalyst such as Co-Mo / alumina catalyst, Ni-Mo / alumina catalyst using direct current gas oil (LGO) as a raw material oil using a hydrodesulfurization apparatus, At a temperature of 300 to 400 ° C., preferably 330 to 360 ° C., under a pressure of 30 to 100 kg / cm ² G, preferably 50 to 70 kg / cm ² G, the liquid space velocity (LHSV) 0.5 to 5 hr ⁻¹ , It is preferably obtained by desulfurization under the condition of 1 to 2 ^{hr −1} , and then removing hydrogen sulfide and naphtha with a stripper.

The hydrocracked gas oil (HCGO) is obtained by hydrocracking heavy gas oil (HGO), vacuum gas oil (VGO) or a mixture of these oils in the presence of a catalyst, and distilling off the cracked product oil. As (HCGO), a sulfur component content of 0.0001 to 0.2% by weight can generally be used.

Furthermore, in addition to the above-mentioned light oil base materials, light oil residual components generally used as necessary, such as direct current gas oil (LGO), by-product light oil (DSGO) from heavy oil direct desulfurization unit, by-product light oil (LCO) from catalytic cracking unit, Desulfurized LCO (DSLCO), by-product diesel from indirect desulfurization (VHLGO), dewaxed diesel (DWLGO), dewaxed desulfurized diesel (DWDGO), desulfurized kerosene residual (DK) and the like can be used in combination.

The addition amount of the additive for fuel oil can be made so that (a), (b) and (c) component become the following amounts.

The component (a) is preferably 20 to 1, 500 ppm by weight, more preferably 50 to 800 ppm by weight, based on the total amount of the composition. If it is less than 20 weight ppm, the cleanliness of a nozzle will not improve easily, and if it exceeds 1,500 weight ppm, the cleanliness of a nozzle may not improve effectively.

The component (b) is preferably 5 to 300 ppm by weight, more preferably 10 to 150 ppm by weight, based on the total amount of the composition. If it is less than 5 ppm by weight, the lubricity of the pump is less likely to be improved. If it exceeds 300 wt.

The component (c) is preferably 50 to 500 ppm by weight, more preferably 100 to 400 ppm by weight, based on the total amount of the composition. If it is less than 50 ppm by weight, the lubricity of the pump due to the synergistic effect with the component (b) is difficult to improve. If it exceeds 300 ppm by weight, the lubricity of the pump due to the synergistic effect with the component (b) does not improve effectively. have.

In the fuel oil composition of the present invention, antioxidants, metal inerts, microbial fungicides, freezing agents, antistatic agents, corrosion inhibitors, antifoaming agents, rust inhibitors, flame retardants, colorants, markers, etc., as necessary, so long as the effects of the present invention are not impaired. Additives, such as these, can be added suitably. These additives can be added separately from the said fuel additive, or are usually added as a package of the additive for fuel oil.

Although an Example demonstrates this invention more concretely below, this invention does not restrict | limit any by these examples.

Examples 1 to 3; Comparative Examples 1 and 2 and Reference Example 1

(1) Preparation of the diesel diesel composition of the present invention

(i) light oil provided for the test;

The deep desulfurization diesel oil shown in Table 1 below was used.

Item Measures How to measure Density (g / cm ³ , 15 ℃) 0.8321 JISK2249 Kinematic viscosity (mm ² / s, 30 ° C) 4.279 JISK2283 Pour point (℃) -5.0 JISK2269 Cloudy point (℃) 3.0 JISK2269 Cetane value 55.1 JISK2280 Clogging temperature (℃) 1.0 JISK2288 Sulfur component (% by weight) 0.026 JISK2541 Distillation phase (℃) 10 capacity% points 50 capacity% points 90 capacity% points 222.0288.5352.0 JISK2254

(ii) additives

The following additive was added and the diesel oil composition was added in the ratio shown in Table 2.

Succinic acid imide of (a) component

Polybutene succinimide prepared by adding polybutene having a number average molecular weight of 960 to maleic anhydride, and further adding tetraethylenepentamine was diluted with mineral oil having a viscosity of 40 ° C. of 32 mm ² / s, The concentration is 64% by weight.

(b) Lubrication improver of the component

The main component is a mixture of unsaturated fatty acids having 18 carbon atoms, which is composed of linoleic acid, oleic acid and linoleic acid as the main component (a mixture of 15 to 50% by weight of each acid and 90% by weight in total). Dilution with solvent brings the active ingredient to 20% by weight.

(c) low-temperature fluidity improver

A mixture of triethanol amine (25% by weight), tribehenic acid ester (50% by weight) and ethylene-vinyl acetate copolymer (25% by weight), diluted with an aromatic solvent having 10 carbon atoms to make the active ingredient 50% by weight. It is.

(2) evaluation of nozzle cleanliness

Nozzle cleanliness was evaluated for the gas oil composition prepared above as follows.

The diesel engine of a 2,400cc rated in-line combustion 4-cylinder diesel engine equipped with a slotted nozzle was operated for 18 hours at a speed of 2,400 rpm and a torque of 2.7 kg · m (load rate of 80%). Flow rate when air of 0.5 kg / cm ² flows into the injection port when the needle valve of the nozzle is raised to 0.00 to 0.6 mm by using an air flow rate measuring device to check the contamination state of the nozzle after the end of the operation. Was measured. The air flow rate for this needle valve lift amount was calculated by area, and the contamination degree of the nozzle was evaluated by comparing the area before and after the test (new article). When the flow rate area retention ratio according to the comparison of the area value of the air flow rate with respect to the needle valve lift amount before and after the test is 100%, it indicates that it is the same as the new product before the test and is not contaminated at all. On the contrary, 0% means that the fuel is not injected because it is completely blocked. The results are shown in Table 2.

(3) evaluation of lubrication performance

Load 200g, test oil temperature 60 ℃, vibration frequency 50Hz, test time 75 minutes, sample volume using HFRR (High Frequency Reciprocation Wear Rig) device by CEC-F-06-T94 of European Commission. The test piece was worn under the conditions of 2 ml. The spread amount of this wear trace was measured in the X (horizontal) and Y (vertical) directions using a microscope and averaged to obtain a wear width (μm). The results are shown in Table 2.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Reference Example 1 Amount of succinimide added ^* 500 500 100 0 500 0 Lubrication Enhancer Addition ^* 75 75 100 75 0 0 Low-temperature fluidity improving agent amount ^* 0 275 275 0 0 0 Nozzle Flow Area Retention Rate (%) 70 72 50 35 54 35 HFRR wear width (μm) 330 310 300 400 560 580 Note) * Weight ppm

From Table 2, it turns out that the gas oil composition to which the additive of this invention was added has a high nozzle flow volume area retention rate, and improves the cleanness of an injection nozzle. In addition, it can be seen that the wear width is small to improve the lubricity.

Examples 4 and 5

[PM reduction effect and cleanliness effect in exhaust gas]

The emissions of PM (also referred to as particulate matter and particulate matter) were compared with engines and evaluation conditions shown in Tables 3 and 4 below. That is, using the fuel shown in Table 1 (Example 4) and Table 5 (Example 5) and the engine of Table 3 and running 5000 km in the nozzle contamination conditions of Table 4, the nozzle cleanliness recovery conditions of Table 4 The nozzle was cleaned.

Next, PM emissions were measured by referring to the diesel vehicle particulate matter test method (TRIAS-24-5-1993) using the PM emission measurement engine conditions shown in Table 4 and the minidition tunnel system (manufactured by Horiba Seisakusho). . The results are shown in Table 6.

Comparative Examples 3 and 4

In addition, PM discharge | emission was measured like Example 4 and 5 except not using an succinimide and a low temperature fluidity improving agent. The results are shown in Table 7.

Main engine specifications Specifications Contents Cylinder arrangement 4 cylinders in series Combustion method Vortex Room Type Total displacement (cc) 2,982 Compression Ratio 21.2 Torque (Nm / rpm) 289/2000 Output (kw / rpm) 95.6 / 3600 Injection pump type Distribution type electronic control method

Engine evaluation conditions Nozzle Contamination Conditions Nozzle Cleanness Recovery Operating Conditions PM emission measurement condition Engine speed (rpm) 2000 2600 1500 Engine load factor (%) 80 25 80 Lubricant temperature (℃) 85 85 85 Engine coolant temperature (℃) 80 80 80 Intake air temperature (℃) 25 25 25 Intake air temperature (℃) 50 50 50 Fuel oil temperature (℃) 25 25 25 Driving time (hr) Up to 5000 km 8 0.5 / Test

Characteristics of Fuel Used Item Constellation How to measure Density (g / cm ³ , 15 ℃) 0.8274 JIS-K-2249 Kinematic viscosity (mm ² / s, 30 ° C) 3.535 JIS-K-2283 Cetane value 57.0 JIS-K-2280 Sulfur Component (wt%) 0.04 JIS-K-2541 Distillation phase (℃) 10 capacity% points 204.0 JIS-K-2254 50% by volume 283.0 90% by volume 330.0

PM emissions (examples) Example 4 Example 5 Succinate Imide Content * 1000 1000 Lubricant Enhancer Addition * 75 75 Low temperature fluidity improver amount * 275 275 PM emissions (g / kwh) 0.834 0.965 Fuel used Fuel of Table 1 Fuel of Table 5 Note) * Weight ppm

PM emissions (comparative) Example 3 Comparative Example 4 Succinate Imide Content * 0 0 Lubricant Enhancer Addition * 75 75 Low temperature fluidity improver amount * 0 0 PM emissions (g / kwh) 1.115 1.254 Used fuel Fuel of Table 1 Fuel of Table 5 Note) Weight ppm

According to the present invention, it is possible to provide an additive for fuel oil and a fuel oil composition containing the same, which have excellent performance in terms of improving lubricity of the fuel injection pump and improving cleanliness of the fuel injection nozzle, particularly for light oil having a reduced sulfur content.

Claims (13)

A fuel oil additive having a 90% point outflow temperature of 320 ° C. or more comprising (a) an alkenylsuccinic acid imide compound, an alkyl succinic acid imide compound or a boron adduct thereof, and (b) a lubricity improver. The 90% point outflow temperature which consists of (a) an alkenylsuccinic acid imide compound, an alkyl succinic acid imide compound, or its boron adduct, (b) a lubricity improver, and (c) a low temperature fluidity improver is 320 degreeC or more Additives for fuel oils. The method according to claim 1 or 2, The additive for fuel oil whose lubricity improver (b) is a C4-C22 unsaturated fatty acid, its dimer acid, or esterified products thereof. The fuel oil composition formed by adding the fuel oil additive of any one of Claims 1-3 to fuel oil. The method of claim 4, wherein A fuel oil composition wherein the amount of component (a) added is 20 to 1,500 ppm by weight, based on the total amount of fuel oil composition. The method according to claim 4 or 5, A fuel oil composition wherein the amount of component (b) added is 5 to 300 ppm by weight based on the total amount of fuel oil composition. The method according to any one of claims 4 to 6, A fuel oil composition wherein the amount of component (c) added is from 50 to 500 ppm by weight, based on the total amount of fuel oil composition. The method according to any one of claims 4 to 7, A fuel oil composition wherein the fuel oil is diesel diesel. The method of claim 8, A fuel oil composition having a sulfur component content of 0.001 to 0.05% by weight in diesel diesel oil. The method of claim 4, wherein The fuel oil composition whose outlet temperature of the 90% point of fuel oil is 320 degreeC or more. The method of claim 4, wherein The fuel oil composition whose outlet temperature of the 90% point of fuel oil is 330 degreeC or more. The method of claim 4, wherein The fuel oil composition whose outlet temperature of the 90% point of fuel oil is 340 degreeC or more. The method of claim 4, wherein The fuel oil composition whose outlet temperature of the 90% point of fuel oil is 350 degreeC or more.