JPH05105891A - Lubricating oil additive and lubricating oil composition containing it - Google Patents

Abstract

PURPOSE:To improve the effect of reducing friction by using a specified divalent metal salt of an aromatic hydroxy carboxylic acid and a 2-6C polyhydric alcohol as constituents. CONSTITUTION:A divalent metal salt of an aromatic hydroxy carboxylic acid is mixed with an excess of an alkaline earth metal (hydroxide), and CO2 in an amount of 0.7-0.9 equivalent based on the divalent metal is introduced into the mixture to give a divalent metal salt of an aromatic hydroxy carboxylic acid having at least one 8-30C linear alkyl group on the benzene ring. The obtained metal salt is mixed with 0.05-0.5wt.% 2-6C polyhydric alcohol to give a lubricating oil additive. 3-40wt.% of this additive is added to a natural oil and/or a synthetic oil.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an additive for lubricating oil and a lubricating oil composition containing the additive. More specifically, the present invention relates to a lubricating oil additive that maintains a low friction coefficient and a lubricating oil composition containing the same.

[0002]

2. Description of the Related Art In recent years, it has been strongly desired to reduce friction between metal surfaces sliding against various lubricating oils for the purpose of saving energy consumption. In particular, as a lubricating oil for an internal combustion engine, an engine oil to which a friction reducing agent is added in order to reduce the amount of fuel consumed is becoming common. Known friction reducing agents include polyhydric alcohol derivatives, amine compounds, organic molybdenum compounds and the like, but these require a relatively large amount of addition in order to obtain practical effects. For example, as the polyhydric alcohol derivative, pentaerythritol monooleate (JP-A-55-80494),
Glycerin dimer acid ester (JP-A-57-3893)
Gazette), oleic acid partial ester of glycerin (JP-A-57-187394), fatty acid ester boric acid addition of glycerin (JP-A-58-8798), and the like. It is used in an amount of about 0.2 to 0.5% by weight. However, if a large amount of these friction reducing agents is added, there is a problem of corrosion due to deterioration products. Therefore, development of a lubricating oil additive containing a small amount of a friction reducing agent and a lubricating oil composition containing the same is expected.

[0003]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that a very small amount of polyhydric alcohol in a lubricating oil is remarkably combined with a specific detergent-dispersant. The inventors have found that the friction is reduced and have completed the present invention. That is, the gist of the present invention is to provide a hydroxyaromatic carboxylic acid divalent metal salt having at least one linear alkyl group having 8 to 30 carbon atoms on a benzene nucleus, and a divalent metal salt having 2 to 2 carbon atoms. The present invention relates to a lubricating oil additive containing 0.05 to 0.5% by weight of a polyhydric alcohol of 6 and a lubricating oil composition containing the same.

The hydroxyaromatic carboxylic acid divalent metal salt used in the present invention is a hydroxyaromatic carboxylic acid having at least one linear alkyl group having 8 to 30 carbon atoms on the benzene nucleus. Those having 12 to 20 carbon atoms are preferably used. Alkyl salicylic acid is preferably used as such a hydroxyaromatic carboxylic acid.

The hydroxyaromatic carboxylic acid divalent metal salt used in the present invention is not particularly limited, but for example, at least one carbon atom having 8 to 8 carbon atoms is present on the benzene nucleus.
It can be prepared from alkylphenols having 30 linear alkyl groups. The alkylphenol can be obtained, for example, by reacting a linear alpha-olefin having 8 to 30 carbon atoms obtained by ethylene oligomerization or wax decomposition with phenol in the presence of an acidic catalyst. Conversion of a hydroxyaromatic carboxylic acid divalent metal salt using the alkylphenol thus obtained is usually accomplished by converting the alkylphenol to an alkali metal salt or an alkaline earth metal salt and then contacting with carbon dioxide gas. To be done. When an alkali metal is used, it is decomposed with a mineral acid such as sulfuric acid or hydrochloric acid to obtain a free hydroxyaromatic carboxylic acid, and then neutralized with a divalent metal oxide and / or hydroxide. Alternatively, a divalent metal salt of hydroxyaromatic carboxylic acid can be obtained by metathesis with a divalent metal halide. The divalent metal used here is a metal belonging to Group 2 of the periodic table of elements, and examples thereof include alkaline earth metals such as magnesium, calcium, strontium, and barium, and zinc and copper. Preferred are calcium and magnesium.

In general, when a divalent metal salt is used as an engine oil additive, a divalent metal salt having an increased basicity is usually provided by dispersing an excess divalent metal salt in an aromatic carboxylic acid. This is because it is expected to have an effect of imparting basicity to the engine oil to neutralize an acid component generated during use and preventing acid corrosion. Also in the present invention, in order to increase the basicity of the lubricating oil additive, an excess amount of alkaline earth metal oxide and / or hydroxide is added to the hydroxyaromatic carboxylic acid and / or divalent metal salt thereof in the present invention. It is achieved by introducing carbon dioxide gas. When introducing carbon dioxide, any known method may be used, such as alcohols such as methanol and glycols such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, and hexylene glycol having 2 to 4 carbon atoms.
It is preferable to carry out the reaction in the presence of the polyhydric alcohol (1) as a reaction accelerator. The amount of carbon dioxide used is usually 0.7 to 0.9 equivalent relative to the divalent metal salt, and is 0.7
If the amount is less than the equivalent amount or more than 0.9 equivalent amount, the insoluble content increases, which is not preferable. In order to reduce the insoluble content, a monocarboxylic acid having 1 to 3 carbon atoms may be used together. Examples of such a monocarboxylic acid having 1 to 3 carbon atoms include formic acid, acetic acid, and propionic acid, and the addition amount thereof is usually 0.01 to 0.5 equivalent with respect to alkylsalicylic acid.

A hydrocarbon solvent and / or a higher alcohol may be used as the reaction solvent. Examples of the hydrocarbon solvent include aromatic hydrocarbons such as benzene, toluene and xylene, and low-viscosity lubricating oil derived from petroleum refining. For example, paraffinic mineral oil having a kinematic viscosity at 100 ° C. of 3 to 30 cSt is used. Further, as higher alcohols, octanol, nonanol, isononanol, decanol,
Examples are higher alcohols having 8 to 18 carbon atoms such as isodecanol, isoundecanol, isododecanol, isotridecanol, 2-ethylhexanol, isohexadecanol and isooctadecanol. Preferably C
Higher alcohols branch ₈ -C ₁₃ are used. These may be used alone as a solvent, but a combination of a paraffinic hydrocarbon and a higher alcohol is preferable. Next, the solvent is distilled off from the resulting mixed solution by a conventional method, and then the insoluble matter is removed. Usually, the insoluble matter can be easily removed by a known means such as filtration or centrifugation.

Examples of the polyhydric alcohol having 2 to 6 carbon atoms contained as a friction reducing agent in the present invention include dihydric alcohols having 2 to 6 carbon atoms and trihydric or higher alcohols. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexylene glycol, neopentyl glycol and the like. Examples of alcohols include glycerin, pentaerythritol, and trimethylolpropane. Above all, a polyhydric alcohol which is liquid at room temperature is preferably used.

In the lubricating oil additive of the present invention, the polyhydric alcohol contained as a friction reducing agent is a polyhydric alcohol such as glycols used as an accelerator during the production of a divalent metal salt of a hydroxyaromatic carboxylic acid. The polyhydric alcohol remaining in the reaction product may be used as it is as the friction reducing agent. That is, when these polyhydric alcohols are used as the accelerator when the hydroxyaromatic carboxylic acid divalent metal salt is produced, the lubricating oil additive of the present invention is obtained at one time by controlling the distillation conditions after the reaction. be able to. Further, when the amount of the polyhydric alcohol remaining in the obtained divalent metal salt is small, or when the polyhydric alcohol is not used as an accelerator, the necessary amount of the polyhydric alcohol is added to the lubricating oil of the present invention. Additives can be obtained. The content of the polyhydric alcohol is usually 0.05 to 0.5% by weight, preferably 0.1 to 0.
It is 3% by weight, and if it is less than 0.05% by weight, the friction reducing effect cannot be obtained. Addition of more than 0.5% by weight deteriorates oxidative stability.

In the lubricating oil additive of the present invention, a linear carboxylic acid having 10 to 22 carbon atoms and / or a divalent metal salt thereof is rubbed in addition to the hydroxyaromatic carboxylic acid divalent metal salt as described above. It may be added for the purpose of reduction. Examples of the linear carboxylic acid in this case include decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and docosanoic acid. The addition amount is usually 5 to 40% by weight, preferably 10 to 30% by weight. 40% by weight
If the amount is larger, the stability of the product is deteriorated, which is inconvenient.
In order to prepare a lubricating oil additive containing a linear carboxylic acid having 10 to 22 carbon atoms and / or a divalent metal salt thereof, it is not particularly limited, but it is usually obtained by mixing with an alkylsalicylic acid. You can

The lubricating oil additive having a divalent metal salt obtained by such a production method is usually added to a lubricating base oil such as natural oil and / or synthetic oil in an amount of 3 to 40% by weight, preferably 1%.
The lubricating oil composition of the present invention can be obtained by adding 0 to 30% by weight. As the natural oil here,
Animal oils, vegetable oils or mineral oils, preferably petroleum-derived paraffinic, naphthenic and paraffin-naphthenic mixed lubricating oils. Further, as synthetic oil, monocarboxylic acid or polyvalent carboxylic acid 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, polyisobutene,
Included are polymeric hydrocarbon lubricating oils such as polyalkylene glycols or poly-alpha-olefins.

The lubricating oil composition of the present invention thus obtained is excellent in reducing friction, as will be shown in Examples described later. Further, the lubricating oil composition of the present invention may contain a metal detergent such as phenate and naphthenate, zinc dialkyldithiophosphate and / or zinc dialkylaryldithiophosphate, and further succinimide type or benzylamine type, if necessary. Additives such as an ashless dispersant, a rust preventive, an antioxidant, an oiliness improver, a viscosity index improver, and a pour point depressant can be added.

[0013]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, but the present invention is not limited to these Examples. Example 1 680.1 g (2 mol) of an alkylphenol having a linear C 16-18 alkyl group and 290 g of 150 neutral oil (paraffinic mineral oil having a kinematic viscosity of 4.2 cSt at 100 ° C.) were stirred with a thermometer. And 2l with dehydrator
Was weighed into a 4-diameter flask and heated with stirring. 1
At 00 ° C., 166 g of 48% aqueous sodium hydroxide solution was added. It was further depressurized and dehydrated at 190 ° C. After that, it was cooled to 140 ° C. and 75 l of carbon dioxide gas was blown thereinto. The blowing took 5 hours. One part of this reaction mixture was decomposed with sulfuric acid to give free alkylsalicylic acid. The acid value (JI
The SK2501) was measured and found to be 82.6. After adding 565 g of isodecanol to 1050 g of the reaction product Na salicylate, concentrated sulfuric acid (98% product)
95g was added and it decomposed | disassembled at 80 degreeC for 4 hours. 540g of water
Was added, stirred for 30 minutes, and allowed to stand at 80 ° C. The lower layer aqueous solution was extracted, and the upper layer was dehydrated at 135 ° C.

Of 1600 g of the resulting decanol solution of alkylsalicylic acid, 549.6 g was transferred to another 2 l flask equipped with a stirrer, a thermometer and a dehydrator, and slaked lime 67.
5 g, 100 g of isodecyl alcohol and 80 g of 150 neutral oil were added and the temperature was raised to 155 ° C. On the way 1
50 g of ethylene glycol was added at 30 ° C. 14 L of carbon dioxide gas was blown in for two and a half hours. The solvent was distilled off under reduced pressure while raising the temperature to 200 ° C. The final distillation conditions were a liquid temperature of 200 ° C. and a pressure of 38 mmHg. The liquid that remained as the bottom was filtered to obtain basic salicylate. Base number (JIS K2501 perchloric acid method) is 182.5 mg
It was KOH / g. The ethylene glycol remaining in this salicylate additive was quantified by the following method. That is, the sample was dissolved in hexane, put in a separating funnel, extracted with water, the water was removed by water concentration, and then the sample was quantified by the periodic acid method. By this method the sample of Example 1 is 0.2% by weight
It was found to contain ethylene glycol.

Example 2 330 g of the alkylsalicylic acid of Example 1 was placed in a 2 liter flask equipped with a stirrer, a thermometer and a dehydrator, and slaked lime 6 was added.
7.5 g and 55.6 g of a linear fatty acid having 16 to 18 carbon atoms (Lunac S30 manufactured by Kao) were added, and the temperature was raised to 155 ° C. On the way, 50 g of ethylene glycol was added at 145 ° C. 14 L of carbon dioxide gas was blown in for two and a half hours. The solvent was distilled off under reduced pressure while raising the temperature to 200 ° C. The final distillation conditions were a liquid temperature of 200 ° C. and a pressure of 35 mmHg. The liquid that remained as the bottom was filtered to obtain basic salicylate. The base number (JIS K2501 perchloric acid method) was 259.3. The amount of ethylene glycol remaining in this product was 0.1% by weight.

Comparative Example 1 590.8 g of the alkylsalicylic acid obtained in Example 1
Was placed in a 2 L flask equipped with a stirrer, thermometer and dehydrator, slaked lime 80.8 g, methanol 80 g xylene 25
0 g was added, and the mixture was heated to 35 ° C. and stirred. Carbon dioxide 18L
Was introduced into the liquid over 2 hours and 40 minutes. Liquid temperature 140 ℃,
The solvent was distilled off at a pressure of 80 mmHg. The liquid remaining in the flask was filtered to obtain basic salicylate. Base number (JIS
K2501 perchloric acid method) is 180.6 mgKOH /
It was g. The polyhydric alcohol is not contained in the additive made of salicylate.

Examples 3 to 8 Using the basic salicylate obtained in Example 1 or Comparative Example 1, polyhydric alcohol was added to each salicylate in an amount of 0.1.
˜0.5 wt% was added separately, and the mixture was stirred and mixed at 120 ° C. for 1 hour to prepare a lubricating oil additive as shown in Table 1.

[0018]

[Table 1]

Test Example The lubricating oil additives obtained in Examples 1-8 were SAE10
Lubricating oil compositions were prepared by dissolving the same in mineral oils of Nos. 1 and 2 to obtain Compositions 1 to 8, respectively. The same additive formulation containing an amine dispersant (ADX210 from BP Chemicals), an antioxidant (ADX304 from BP Chemicals), and a viscosity index improver (TC9827 from Texaco) for all lubricating oil compositions. Used together. On the other hand, Comparative Compositions 1 and 2 using the lubricating oil additive obtained in Comparative Example 1 as it is as a comparative composition, and pentaerythritol monooleate, which is a known friction reducing agent, in the composition obtained in Comparative Example 1. Comparative composition 3 with 0.05 wt% addition to the lubricating oil composition
Were prepared in the same manner as compositions 1 to 8. As a control, a base composition oil to which none of the lubricating oil additives obtained in Examples or Comparative Examples was added was also tested.

In the test, the friction reduction effect was evaluated by measuring the friction coefficient before and after oxidative deterioration and obtaining the friction loss torque reduction rate. Regarding the oxidation deterioration, the temperature condition of the JIS K2514 lubricating oil oxidation stability test was set to 150 ° C. for 100 hours, and the friction coefficient was measured before and after the deterioration. The friction coefficient was measured using a pendulum type friction tester. The material of the test piece was SUJ-2. Conditions are full load 300g, oil temperature 4
The initial amplitude was 30 degrees at 0 ° C and 80 ° C. The torque test is a motoring test and the oil temperature is 80 ° C and the rotation speed is 500.
The friction loss torque was measured under the conditions of 1000 rpm and 1000 rpm. The test engine used was a twin-cam engine with a displacement of 2000 cc equipped with two compression rings and one oil ring. From these results, it was shown that the lubricating oil composition according to the present invention maintained a low coefficient of friction even after oxidative deterioration and was able to reduce friction loss even in a torque test.

[0021]

[Table 2]

[0022]

The lubricating oil additive of the present invention exerts an excellent friction reducing effect by containing a trace amount of polyhydric alcohol, and is therefore useful as a detergent-dispersant for lubricating oil.

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Claims (4)

[Claims] 1. A divalent metal salt of a hydroxyaromatic carboxylic acid having at least one linear alkyl group having 8 to 30 carbon atoms on a benzene nucleus, and a divalent metal salt having 2 carbon atoms.
A lubricating oil additive containing 0.05 to 0.5% by weight of a polyhydric alcohol of 6 to 6. 2. The lubricating oil additive according to claim 1, wherein the hydroxyaromatic carboxylic acid is an alkylsalicylic acid. 3. The additive according to claim 1, which has 10 to 2 carbon atoms.
2 straight-chain carboxylic acid and / or divalent metal salt thereof to 5
A lubricating oil additive contained in an amount of -40% by weight. 4. A lubricating oil composition comprising the lubricating oil additive according to any one of claims 1 to 3 in a natural oil and / or a synthetic oil in an amount of 3 to 40% by weight.