JPH05125381A - Lubricating oil additive and lubricating oil composition containing the same additive - Google Patents

Abstract

PURPOSE:To obtain the subject additive used for cleaning and dispersing agent for lubricating oil, having good heat resistance and water resistance by reacting an alkylsalicylic acid having a higher alkyl group with a divalent metal salt, dihydric alcohol and CO2 in a hydrocarbon and higher alcohol. CONSTITUTION:A divalent metal salt (e.g. slaked lime) of >=1 equivalent based on an alkylsalicylic acid having at least one or more 16-18C alkyl groups is added to the alkylsalicylic acid in a hydrocarbon solvent (e.g. toluene) and higher alcohol and then after a reaction accelerator of 2-4C dihydric alcohol (e.g. ethylene glycol) is added to the mixed solution, carbon dioxide is introduced therein to give a lipophilic basic salt solution and the solvent is distilled off from the solution by raising the temperature of the solution to 220 deg.C under reduced pressure and then an insoluble content is removed by filtration to provide the objective lubricating oil additive, excellent in both of heat resistance and water resistance and useful as a cleaning and dispersing agent for lubricating oil.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil additive having an oil-soluble basic salt useful as a detergent-dispersant for lubricating oil, and a lubricating oil composition containing the same.

[0002]

2. Description of the Related Art In crankcases, oil pans, etc., water in combustion gas is condensed,
Mix in engine oil. This moisture is NO _x or SO _x
It absorbs the acidic gas of and shows strong acidity. The engine oil is typically represented by an overbased divalent metal salt for the purpose of keeping the inside of the engine clean and neutralizing acidic substances such as sulfuric acid and nitric acid generated by the combustion of the fuel as described above. Various lubricating oil additives have been used. However, an acidic aqueous solution containing an acidic substance such as sulfuric acid or nitric acid generated by combustion of fuel promotes coarsening of the divalent metal salt in the metal-based detergent, and prevents the original action of the detergent, In particular, there is a demand for a metal-based detergent that is stable to an acidic aqueous solution, that is, has excellent water resistance.

Further, in recent years, the demand for higher output of automobile engines and the like has become higher, and it has been a subject to improve the thermal efficiency of the engine in order to improve fuel economy. It is getting hotter and hotter. Therefore, the lubricating oil additive is required to have further heat resistance.

As a lubricating oil additive having more excellent heat resistance than before, an aromatic carboxylic acid having an alkyl group, particularly an overbased divalent metal salt of alkylsalicylic acid (hereinafter referred to as salicylate) has been widely known. Has been. As a report on such an alkyl group of salicylate, a salicylate having an alkyl group having 12 or more carbon atoms (Japanese Examined Patent Publication No. 32112/1987) and a salicylate in which 70% or more of the salicylate is in the para position relative to the OH group (Japanese Examined Patent Publication 48-35
325), 60% mol or more of which is in the para position with respect to the OH group, and a part of the salicylate is bonded with a quaternary carbon (Japanese Patent Publication No. 50-3082). However, none of these lubricating oil additives describes the water resistance as described above, and the relationship between the carbon composition of the alkyl group and the heat resistance and water resistance is not described. Therefore, an object of the present invention is to provide a lubricating oil additive excellent in both heat resistance and water resistance and a lubricating oil composition containing the same by optimizing the alkyl composition of alkylsalicylic acid.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the composition of the alkyl group in alkylsalicylic acid greatly affects the performance. That is, the alkyl group has 12 to 1 carbon atoms.
In the composition of 4, the heat resistance is remarkably poor, and in the composition of 20 to 24 carbon atoms or 20 to 28 carbon atoms, the stability to water and the stability of the product are poor, and the alkyl group consisting of the composition of 16 to 18 carbon atoms The inventors have found that they all satisfy the requirements for stability in water, heat resistance, and solubility in lubricating base oils, leading to the present invention.

That is, the gist of the present invention is (1) an alkylsalicylic acid having 90% by weight or more of all alkyl groups having at least one or more alkyl groups having 16 to 18 carbon atoms in a hydrocarbon solvent and a higher alcohol. Two
A lubricating oil additive having a valent metal salt, a dihydric alcohol having 2 to 4 carbon atoms, and an oil-soluble basic salt obtained by reacting carbon dioxide, (2) a lubricating oil additive having the following steps Production method (a): a step of adding at least one equivalent of a divalent metal salt to an alkylsalicylic acid having at least one or more alkyl group having 16 to 18 carbon atoms in a hydrocarbon solvent and a higher alcohol, (B): a step of adding a dihydric alcohol having 2 to 4 carbon atoms to the mixed solution of step (a) and then introducing carbon dioxide to obtain an oil-soluble basic salt solution, and (c): step (B) a step of distilling off the solvent of the basic salt solution and then removing an insoluble matter to obtain an oil-soluble basic salt; (3) a natural oil and / or a synthetic oil as described in (1) above. 0.1 to 60% by weight of lubricating oil additive Yes is allowed to lubricating oil compositions comprising.

The alkylsalicylic acid having an alkyl group having 16 to 18 carbon atoms used in the present invention is a compound having at least one or more alkyl group having 16 to 18 carbon atoms, and is usually an alkyl group having various carbon numbers. It is a mixture of compounds having groups. Further, in the present invention, the carbon number is 16 to 1.
It is desirable that the total amount of alkyl groups of 8 is 90% by weight or more, preferably 95% by weight or more, based on the total amount of alkyl groups.
If it is less than 90% by weight, the stability against water and heat resistance are not sufficiently improved. For example, an alkyl group having 14 or less carbon atoms,
When it is present in an amount of more than 10% by weight in all alkyl groups, heat resistance is generally deteriorated, and when an alkyl group having 20 or more carbon atoms is present in an amount of more than 10% by weight in all alkyl groups, water stability is deteriorated and a base is formed. When the degree of activity is high, the solubility in the lubricating base oil is poor.

The number of carbon atoms used in the present invention is 16
The alkylsalicylic acid having ~ 18 alkyl groups can be easily produced, for example, by the following method.
That is, first, an alkylphenol is synthesized. As a catalyst for the alkylation of phenols, acidic activated clay, acidic ion exchange resins, boron trifluoride, aluminum chloride, and other acidic catalysts are generally used, and among them, acidic activated clay and acidic ion exchange resins are preferably used. Be done. Examples of the alkylating agent include alcohols and olefins, and olefins having high reactivity are preferable. Among the olefins, linear α-olefins are more preferable. Examples of the use of alcohols as the alkylating agent include a method of chlorinating a hydroxyl group of alcohol and then a Friedel-Crafts reaction, and a method of directly reacting with phenol using the above catalyst. When 12 or more higher alcohols are used, the reaction rate is low and not practical. As the most practical specific example, using acid activated clay as a catalyst, α-
Olefin and phenol (1 to α-olefin
3 equivalents) is reacted at 50 to 200 ° C., and then the catalyst and excess phenol are removed to obtain an alkylphenol. The amount of catalyst at this time is 1 to 10% by weight, preferably 2 to 5% by weight based on the total weight of α-olefin and phenol.
It is recommended to use the weight percent.

The alkylsalicylic acid is generally synthesized by the Kolbeschmitt reaction from the alkylphenol obtained as described above. That is, using an aqueous solution of caustic soda or an aqueous solution of caustic caustic, an alkylphenol is converted into a corresponding alkylphenolate, treated with carbon dioxide gas at 100 to 200 ° C. under 1 to 40 atm, and then treated with a mineral acid to give an alkyl salicylate. It can be prepared by liberating the acid. The alkylsalicylic acid synthesized by this method usually contains 5 to 30% by weight of unreacted alkylphenol.

The divalent metal salt used in the present invention is usually in the form of a hydroxide or oxide of an alkaline earth metal such as magnesium, calcium, strontium or barium. In particular, hydroxides or oxides of magnesium or calcium are preferably used because they are industrially easily available.

The dihydric alcohol having 2 to 4 carbon atoms in the present invention acts as a reaction accelerator and functions as ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 2, Examples thereof include 3-butanediol and 1,4-butanediol, and among them, ethylene glycol is preferable.

As the solvent used in the present invention,
Examples include hydrocarbon solvents and higher alcohols. Here, as the hydrocarbon solvent, a hydrocarbon fraction derived from petroleum refining containing an aromatic compound such as benzene, toluene, xylene or the like, or an aromatic compound such as naphtha, gasoline or light alkylate, and a kinematic viscosity at 100 ° C. of 3 to 30 cSt. Examples of low viscosity lubricating oils include Further, it should be taken into consideration that the higher alcohol has a boiling point sufficiently higher than the reflux temperature of the dihydric alcohol used as the reaction accelerator and is easily removed by distillation after the reaction. That is, a branched alcohol having 9 to 18 carbon atoms such as isononyl alcohol, isodecanol, isotridecanol, isopentadecanol, and isooctadecanol is preferable. Preferred are isononyl alcohol, isodecanol and isotridecanol.

The fatty acid in the present invention is broadly selected whether linear or branched, saturated or unsaturated. Preferably, acetic acid, lauric acid, palmitic acid, stearic acid, isostearic acid, oleic acid, α-
An α-branched fatty acid and / or a telomer acid obtained by radically adding an olefin. Addition of these fatty acids is preferable because it further improves the heat resistance. The addition amount is usually 0.01 to 10 equivalents, preferably 0.1 to 2 equivalents, relative to the alkylsalicylic acid. If it is less than 0.01 equivalent, the effect of addition is insufficient, and if it is added in excess of 10 equivalents, the solubility in the lubricating base oil deteriorates, which is not preferable.

The oil-soluble sulfonic acid in the present invention may be either synthetic or natural. Oil-soluble sulfonic acid 2
Examples of the valent metal salt include alkylnaphthalene sulfonic acid, dialkylbenzene sulfonic acid, monoalkylbenzene sulfonic acid, and divalent metal salts thereof. Examples of the divalent metal include zinc, barium, calcium, magnesium and the like. For example, Ca sulfonate commercially available as a lubricating oil additive can be used. Addition of such a sulfonic acid or a divalent metal salt thereof is preferable because it improves the stability of the product, particularly when a basic salt having a high basicity is obtained. The amount used in this case is usually
1 to 30% by weight of the product, preferably 5 to 1
It is 5% by weight. If the addition amount is less than 1% by weight, the effect of the addition is not recognized, and even if it exceeds 30% by weight, the improvement effect is not obtained.

The production of the lubricating oil additive of the present invention can be carried out through the following steps (a) to (c).
First, in step (a), an alkylsalicylic acid having at least one or more alkyl groups having 16 to 18 carbon atoms in an amount of 90% by weight or more based on the total amount of alkyl groups in a hydrocarbon solvent and a higher alcohol is used. This is a step of adding a divalent metal salt, and the divalent metal salt is usually used in an excess amount of 1 equivalent or more with respect to the alkylsalicylic acid.

Next, in step (b), a dihydric alcohol having 2 to 4 carbon atoms is added to the mixed solution obtained in step (a), and then carbon dioxide is introduced to form an oil-soluble basic salt solution. This is the process of obtaining, and the addition amount of dihydric alcohol here is 2
It is usually 0.5 to 2 equivalents, preferably 1 to 1 with respect to the valent metal salt.
It is 1.5 equivalents. If it is less than 0.5 equivalent, the amount of carbon dioxide absorbed is small and the amount of insolubles is large, and if it exceeds 2 equivalents, the viscosity of the product increases, which is not preferable.

The introduction of carbon dioxide may be carried out by any known method, particularly preferably in the presence of the above reaction accelerator. The amount of carbon dioxide used is usually 0.7 to 0.9 equivalent with respect to the divalent metal salt, and if it is less than 0.7 equivalent or more than 0.9 equivalent, the insoluble content increases, which is preferable. Absent.

Then, in the step (c), the step (b)
It is a step of distilling the solvent from the mixed solution obtained by the conventional method, and then obtaining an oil-soluble basic salt by removing the insoluble matter. Removal of the insoluble matter is usually carried out by known methods such as filtration and centrifugation. It can be easily performed by means. In the process of producing the lubricating oil additive of the present invention, fatty acid and / or oil-soluble sulfonic acid, or a divalent metal salt thereof may be allowed to coexist, but in that case, the usual process (a) or It is added after the introduction of carbon dioxide in step (b).
The lubricating oil additive of the present invention thus obtained is excellent in both heat resistance and water resistance.

The lubricating oil additive of the present invention thus obtained is added to a lubricating base oil of natural oil and / or synthetic oil,
The lubricating oil composition of the present invention can be obtained by adding normally 0.1 to 60% by weight, preferably 0.5 to 30% by weight. If the amount of the lubricating oil additive added is less than 0.1% by weight, the effect of addition cannot be obtained. Further, even if added in excess of 60% by weight, there is no further improvement effect and it is uneconomical, which is not preferable. The natural oil as used herein is an animal oil, a vegetable oil or a mineral oil, and is preferably a petroleum-derived paraffin-based, naphthene-based or paraffin-naphthene-based lubricating oil. Further, as synthetic oils, monocarboxylic acids or polycarboxylic acids having 4 to 18 carbon atoms (for example, adipic acid, sebacic acid, citric acid, tartaric acid, phthalic acid, trimellitic acid, succinic acid, fumaric acid, maleic acid, etc. ) Polyol or polyol ether (for example, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, etc.), a synthetic ester lubricating oil, and a high molecular hydrocarbon such as polyisobutene, polyalkylene glycol or poly-α-olefin. Includes lubricating oil.

The lubricating oil composition of the present invention thus obtained has excellent heat resistance and water resistance. Also,
The lubricating oil composition of the present invention optionally contains a phenate,
Metal-based detergents such as naphthenates, zinc dialkyldithiophosphates and / or zinc dialkylaryldithiophosphates, ashless dispersants such as succinimide type or benzylamine type, rust preventives, antioxidants, oiliness improvers,
Additives such as viscosity index improver and pour point depressant can be added.

[0021]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Comparative Experimental Examples, but the present invention is not limited to these Examples. Synthesis example of alkylsalicylic acid In a 3 liter flask equipped with a stirrer and a thermometer, 1155 g of α-olefin having 16 and 18 carbon atoms, 940 g of phenol and 84 g of acid activated clay were placed and reacted at 160 ° C. Acidic activated clay was removed from this reaction product by filtration, and excess phenol was distilled off to give a carbon number of 16: 1.
8 alkylphenol (hydroxyl value: 152.8) was obtained.

506 g of this alkylphenol having 16 or 18 carbon atoms and 217 g of 150 neutral oil (paraffin type lubricating oil having a kinematic viscosity of 4.2 cSt at 100 ° C.) of 217 g were placed in a 2 liter flask equipped with a stirrer, a thermometer and a water separator. The temperature was raised with stirring. Then 4 at 100 ° C
118 g of 8% aqueous sodium hydroxide solution was added over 30 minutes. Further, the pressure was gradually reduced to dehydrate. The temperature was raised to 170 ° C. and the vacuum degree of 30 mmHg was maintained for 30 minutes. Then, the mixture was cooled and returned to atmospheric pressure, and 45 liters of carbon dioxide gas was blown into it for 3 hours to obtain a brownish-brown liquid substance (alkyl salicylate Na salt mixture). 7% concentrated sulfuric acid was added to the reaction mixture.
0 g was added and decomposed at 80 ° C. for 4 hours to obtain free alkylsalicylic acid. At this time, the by-product Glauber's salt was washed off with water. The acid value (JIS K2501) of the thus obtained C16-C18 alkylsalicylic acid mixture was 80.9. Hereinafter, the alkylsalicylic acid mixtures used in Examples and Comparative Examples are those synthesized from the α-olefin corresponding to each alkyl chain length according to the above method. The carbon number ratio of the alkyl group is as shown in Table 1.

[0023]

[Table 1]

Example 1 C16 alkylsalicylic acid mixture (acid value 82.1 mg
341.7 g of KOH / g) was transferred to a 2 liter flask equipped with a stirrer, thermometer and water separator. Here, slaked lime 6
4.8 g, 138 g of isodecanol, and 35 g of 150 neutral oils were added, and it heated up to 152 degreeC. 50 on the way
Over the course of 4 minutes, 46.5 g of ethylene glycol was added. 1
After aging at 52 ° C. for 1 hour, 12 liters of carbon dioxide gas was blown in for 2 hours and 30 minutes. Then, the temperature was raised to 220 ° C. and the pressure was reduced to distill off the solvent. Insoluble matter was removed from the residue by filtration to obtain a basic salicylate. The base number of this salicylate (JIS K2501 perchloric acid method; hereinafter the same method for measuring the base number) was 213 mgKOH / g.

Example 2 C18 alkylsalicylic acid mixture (acid value 74.1 mg
378.6 g of KOH / g), 64.8 g of slaked lime, 138 g of isodecanol, 20 g of 150 neutral oil, 46.5 g of ethylene glycol and 12 liters of carbon dioxide were operated in the same manner as in Example 1 to obtain a basic salicylate. The base number of this salicylate is 203 mgKOH / g
Met.

Example 3 Mixture of alkylsalicylic acid having 16 and 18 carbon atoms (acid value 7
6.9 mg KOH / g) 364.8 g, slaked lime 64.8 g, isodecanol 138 g, 150 neutral oil 20 g, ethylene glycol 46.5 g and carbon dioxide gas 12 liters were operated in the same manner as in Example 1 to obtain basic salicylate. .. The base number of this salicylate is 209 m
It was gKOH / g.

Example 4 Alkyl salicylate mixture having 16 and 18 carbon atoms (acid value 8
0.9 mg KOH / g) 346.8 g, slaked lime 64.8 g, isodecanol 138 g, 150 neutral oil 30 g, ethylene glycol 46.5 g and carbon dioxide 12 liters were operated in the same manner as in Example 1 to obtain a basic salicylate. .. The base number of this salicylate is 213 m
It was gKOH / g.

Example 5 Alkylsalicylic acid mixture having 16 and 18 carbon atoms (acid value 8
0.9 mg KOH / g) 208.1 g, stearic acid (acid value 210.0
53.4 g of mgKOH / g), 64.8 g of slaked lime, 138 g of isodecanol, 60 g of 150 neutral oil, 46.5 g of ethylene glycol and 12 liters of carbon dioxide were operated in the same manner as in Example 1 to obtain a basic salicylate. The base number of this salicylate is 242 mg KOH
It was / g.

Example 6 Alkylsalicylic acid mixture having 16 and 18 carbon atoms (acid value 8
0.9 mg KOH / g) 138.7 g, slaked lime 62.9 g, isodecanol 178 g, 150 neutral oil 70 g, ethylene glycol 55.8 g and carbon dioxide gas 15 liters were operated in the same manner as in Example 1 to obtain a basic salicylate. .. The base number of this salicylate is 320 m
It was gKOH / g.

Example 7 C16-C18 alkylsalicylic acid mixture (acid value 8
0.9 mg KOH / g) 138.7 g, Ca sulfonate (C-2
5H) 12.6 g, slaked lime 62.9 g, isodecanol 178 g, 150 neutral oil 60 g, ethylene glycol 55.8 g and carbon dioxide gas 15 liters were operated in the same manner as in Example 1 to obtain a basic salicylate. The base number of this salicylate was 318 mg KOH / g.

Comparative Example 1 A mixture of alkylsalicylic acid having 12 and 14 carbon atoms (acid value 9
5.9 mg KOH / g) 292.5 g, slaked lime 64.8 g, isodecanol 138 g, 150 neutral oil 40 g, ethylene glycol 46.5 g and carbon dioxide gas 12 liters were operated in the same manner as in Example 1 to obtain a basic salicylate. .. The base number of this salicylate is 236 m
It was gKOH / g.

Comparative Example 2 320.6 g of a mixture of alkylsalicylic acid having 14, 16, and 18 carbon atoms (acid value 87.5 mgKOH / g) and slaked lime 64.8.
g, 138 g of isodecanol, 150 neutral oil 3
0 g, ethylene glycol 46.5 g and carbon dioxide gas 1
By operating 2 liters as in Example 1,
A basic salicylate was obtained. The base number of this salicylate was 226 mgKOH / g.

Comparative Example 3 362.0 g of a mixture of alkylsalicylic acid having 16, 18, and 20 carbon atoms (acid value 77.5 mgKOH / g), slaked lime 64.8
g, 138 g of isodecanol, 150 neutral oil 1
0 g, ethylene glycol 46.5 g and carbon dioxide gas 1
By operating 2 liters as in Example 1,
A basic salicylate was obtained. The base number of this salicylate was 215 mgKOH / g.

Comparative Example 4 440.4 g of a mixture of alkylsalicylic acid having 20, 22, and 24 carbon atoms (acid value 63.7 mg KOH / g) and slaked lime 64.8.
g, 138 g of isodecanol, 150 neutral oil 1
0 g, ethylene glycol 46.5 g and carbon dioxide gas 1
By operating 2 liters as in Example 1,
A basic salicylate was obtained. The base number of this salicylate was 183 mgKOH / g.

Comparative Example 5 176.2 g of a mixture of alkylsalicylic acid having 20, 22, and 24 carbon atoms (acid value 63.7 mgKOH / g) and slaked lime 62.9.
g, 178 g of isodecanol, 150 neutral oil 4
0 g, ethylene glycol 55.8 g and carbon dioxide gas 1
By operating 5 liters as in Example 1,
A basic salicylate was obtained. The base number of this salicylate was 312 mgKOH / g.

Comparative Example 6 190.8 g of a mixture of alkylsalicylic acid having 20, 22, 24, 26 and 28 carbon atoms (acid value 58.8 mg KOH / g), 62.9 g of slaked lime, 178 g of isodecanol, 30 g of 150 neutral oil, ethylene glycol The basic salicylate was obtained by the same procedure as in Example 1 except that 55.8 g and carbon dioxide gas of 15 liters were used. The base number of this salicylate was 307 mgKOH / g.

Comparative Experimental Example 1 The solubility of the salicylates obtained in Examples 1 to 7 and Comparative Examples 5 and 6 in a base oil (viscosity SAE 50 #) was compared. All the evaluation oils were prepared to 70 TBN (total number of bases: JIS K2501 shows base number by perchloric acid method). The test results are shown in Table 2. In the examples using alkylsalicylic acid having 16 and 18 carbon atoms, all were transparent and showed good solubility.

[0038]

[Table 2]

Comparative Experimental Example 2 The water stability test was conducted on the salicylates obtained in Examples 1 to 5 and Comparative Examples 3 and 4 by two methods. Method A: Put 100 g of the evaluation oil and 5 g of water in a pressure resistant bottle,
After 24 hours at 93 ° C. and 5 rpm, the evaluation oil was transferred to a centrifuge tube, the base number of the oil layer after centrifugation at 1500 rpm for 20 minutes was measured, and the retention rate (%) with respect to the base number before the test was determined. Method B: 0.42 g of concentrated sulfuric acid was added to 100 g of the evaluated oil, a part of the mixture was neutralized with sulfuric acid (corresponding to 15% of TBN), and then 5 g of water.
Was added and tested in the same manner as in Method A to determine the retention rate (%).

The compounding composition of the evaluation oil is as follows. Salicylate 35 TBN Succinimide ^{* 1} 2.0 wt% ZDTP ^{* 2} 0.5 wt% Lubricating oil base oil Viscosity SAE30 # * 1: Commercial succinimide (BP Chemical ADX211) * 2: Commercial zinc dialkyldithiophosphate (Amoco 198) A Table 3 shows the test results for each of the B and B methods.
The base number retention rate of salicylates obtained in ~ 5 was higher than that of the comparative example, which was a good result. Moreover, particularly in the evaluation by the B method, the comparative example showed a remarkably poor result,
In this case, the salicylate obtained in Example 5 was also better than the comparative example.

[0041]

[Table 3]

Comparative Experimental Example 3 An engine oil composition was prepared using the salicylates obtained in Examples 1 to 5 and Comparative Examples 1 and 2, and a panel caulking test was conducted as a heat resistance test. The test conditions and results are shown in Table 4. The evaluation oil used had the same composition as in Comparative Experimental Example 2. In the examples using salicylates having 16 and 18 carbon atoms, it was shown that both of them have a small amount of deposit and have excellent heat resistance.

[0043]

[Table 4]

Comparative Experimental Example 4 An engine oil composition was prepared using the salicylates obtained in Examples 4 and 5 and Comparative Example 2, and the engine for automobiles was used according to the standard M336 (using Nissan Diesel SD22) by the Society of Automotive Engineers of Japan. A cleanliness test of the lubricating oil was performed. However, the sulfur concentration of the fuel oil used was adjusted to 1.0% by weight.

The compounding composition of the evaluation oil is as follows. Salicylate 11TBN Succinimide ^{* 1} 1.5wt% ZDTP ^{* 3} 0.7wt% Lubricating oil base oil Viscosity SAE30 # * 1: Commercial succinimide (BP Chemical ADX211) * 3: Commercial zinc dialkyldithiophosphate (BP Chemical A)
DX304) Engine test results are shown in Table 5. In the examples using the salicylates obtained in Examples 4 and 5, the piston cleanliness was excellent and the heat resistance was good. Moreover, the ring wear amount was small and the result was good as an engine oil.

[0046]

[Table 5]

[0047]

The lubricating oil additive of the present invention is excellent in both heat resistance and water resistance, and is therefore useful as a detergent-dispersant for lubricating oil.

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Claims (4)

[Claims] 1. An alkylsalicylic acid having at least one or more alkyl group having 16 to 18 carbon atoms in an amount of 90% by weight or more based on all alkyl groups in a hydrocarbon solvent and a higher alcohol, a divalent metal salt, and 2 carbon atoms. ~ 4 dihydric alcohols,
And a lubricating oil additive having an oil-soluble basic salt obtained by reacting carbon dioxide. 2. The lubricating oil additive according to claim 1, obtained by reacting in the presence of a fatty acid and / or an oil-soluble sulfonic acid or a divalent metal salt thereof. 3. A method for producing a lubricating oil additive, which comprises the steps of: (A): a step of adding at least one equivalent of a divalent metal salt to an alkylsalicylic acid having at least one or more alkyl groups having 16 to 18 carbon atoms in a hydrocarbon solvent and a higher alcohol, (b) A step of adding a dihydric alcohol having 2 to 4 carbon atoms to the mixed solution of the step (a) and then introducing carbon dioxide to obtain an oil-soluble basic salt solution, and (c): the step (b) The step of distilling off the solvent of the basic salt solution of 1 and then removing the insoluble matter to obtain an oil-soluble basic salt. 4. A natural oil and / or a synthetic oil.
Alternatively, a lubricating oil composition containing 0.1 to 60% by weight of the lubricating oil additive described in 2.