JP5961097B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition suitable for a continuously variable transmission.

  In recent years, improvement in fuel efficiency has become an important issue for automobiles due to global environmental problems, and the efficiency of continuously variable transmission (CVT) is more efficient than multi-stage automatic transmission (AT). The mounting ratio is increasing. In CVT, a metal push belt type is the mainstream, and it is mounted on a wide range of vehicles with a displacement of 0.6L to 3.5L. Recently, a chain type CVT, which is considered to be more efficient, is also installed. In these CVTs, since power is transmitted by friction between the pulley and the belt or between the pulley and the chain, the CVT is pressed with a large force in order to prevent slippage between them. Between the belt and the pulley or between the chain and the pulley is lubricated with CVT oil. Since the reduction of the pressing force during this time leads to an improvement in fuel efficiency, the CVT oil requires a high coefficient of friction between metals. Further, in order to further improve fuel efficiency, a mechanism for slip-controlling a lock-up clutch with a built-in torque converter is often employed. Therefore, many CVT oils have a friction characteristic with respect to wet clutches. However, as the metal friction coefficient of CVT oil increases, vibration and noise between the pulley and the belt or between the pulley and the chain often become a problem. In order to suppress this problem, CVT oil is also desired to be excellent in a friction coefficient between metal and a sliding speed characteristic (hereinafter also referred to as “inter-metal μ-V characteristic”) in addition to a high friction coefficient between metals. ing.

  For example, in Patent Document 1, a combination of a high base number and a low base number alkaline earth metal salt, an imide compound and a phosphorus compound are combined to increase the coefficient of friction between metals and improve the friction characteristics of the wet clutch. is suggesting. In Patent Document 2, by adding an alkaline earth metal salt, a boron-containing succinimide, a triazole compound, an (alkyl) aryl phosphite, and an imide or amine friction modifier, the transmission torque capacity is increased, Furthermore, it has been proposed to improve the wear resistance and friction characteristics of wet clutches. In Patent Document 3, it is proposed that the friction coefficient between metals is increased by a phosphorus compound and succinimide to suppress clogging of the wet clutch. Patent Document 4 proposes that an organic acid metal salt, a phosphorus compound, and succinimide are combined to increase the coefficient of friction between metals and suppress clogging of the wet clutch. Moreover, there exists patent document 5 regarding the suppression of noise. Specifically, a combination of a relatively low base number alkaline earth metal sulfonate and a phosphite, and a friction modifier consisting of a sarcosine derivative or a reaction product of a carboxylic acid and an amine suppresses scratch noise. I can do it.

Japanese Patent No. 4377505 JP 2007-126543 A JP 2010-189479 A JP 2011-006705 A Japanese Patent No. 4117043

The technologies described in Patent Documents 1 to 4 described above all relate to the friction coefficient between the metal and the friction characteristics of the wet clutch, and suppress vibration and noise between the pulley and the belt or between the pulley and the chain. Is not considered. Even the proposed oil of Patent Document 5 is not necessarily sufficient for suppressing vibration and noise.
Moreover, at present, a higher transmission torque capacity (coefficient of friction between metals) is required, and compatibility with vibration and noise prevention performance is desired.

  An object of the present invention is to provide a lubricating oil composition having a sufficiently high coefficient of friction between metals and capable of suppressing vibration and noise due to friction between metals.

In order to solve the above problems, the present invention provides the following lubricating oil composition. (1) A base oil is blended with (a) an alkaline earth metal sulfonate having a base number of 200 mgKOH / g or more, (b) a sulfur-containing phosphorus compound, and (c) an aliphatic primary amine. ) The blending amount of the component is 150 mass ppm or more and 900 mass ppm or less in terms of alkaline earth metal based on the total composition amount, the carbon number of the component (c) is 14 or less, and the blending amount is based on the total composition amount. 700 mass ppm der less than 100 ppm by mass of nitrogen in terms of the amount of is, the lubricating oil composition, characterized in der Rukoto continuously variable automatic transmission.
(2) The lubricating oil composition as described in (1) above, wherein the component (a) is at least one selected from calcium sulfonate and magnesium sulfonate.
(3) In the lubricating oil composition according to (1) or (2) above, the component (b) is at least one selected from sulfur-containing phosphites and sulfur-containing phosphates. A lubricating oil composition.
(4) In the lubricating oil composition according to any one of (1) to (3), the component (c) is at least one selected from alkylamines and alkenylamines. A lubricating oil composition.
(5 ) The lubricating oil composition according to any one of ( 1 ) to (4) , wherein the continuously variable automatic transmission is a metal belt type or a chain type. Composition.
(6) The lubricating oil composition according to any one of (1) to (5) above, wherein the lubricating oil composition does not contain an aliphatic dicarboxylic acid.

  According to the lubricating oil composition of the present invention, the transmission torque capacity (coefficient of friction between metals) of the metal belt CVT and the chain CVT is kept high, and the inter-metal μ-V characteristics related to vibration and noise are excellent.

  The lubricating oil composition of the present invention (hereinafter also simply referred to as “the present composition”) comprises, as a base oil, (a) an alkaline earth metal sulfonate, (b) a sulfur-containing phosphorus compound, and (c) aliphatic 1 It is formed by blending a secondary amine. Details will be described below.

[Base oil]
The base oil in the present composition is not particularly limited, and any mineral oil or synthetic oil can be used as long as it can be used as an ATF or a continuously variable transmission (CVTF).
Examples of the mineral oil include paraffin-based mineral oil, intermediate-based mineral oil, and naphthene-based mineral oil, and specific examples include light neutral oil, medium neutral oil, heavy neutral oil, bright stock, and the like. . Of these, paraffin-based mineral oil is particularly preferable in terms of viscosity-temperature characteristics. Examples of the synthetic oil include polybutene, polyolefin (α-olefin homopolymer and copolymer (for example, ethylene-α-olefin copolymer)), and various esters (for example, polyol ester, dibasic acid). Ester, phosphate ester, etc.), various ethers (eg, polyphenyl ether), polyoxyalkylene glycol, alkylbenzene, alkylnaphthalene and the like. Of these, polyolefins and polyol esters are particularly preferred from the viewpoint of lubricity.
In the present invention, as the base oil, one kind of the mineral oil may be used, or two or more kinds may be used in combination. Moreover, the said synthetic oil may be used 1 type and may be used in combination of 2 or more types. Further, one or more types of mineral oil and one or more types of synthetic oil may be used in combination.

[(A) component]
Component (a) in the present composition is an alkaline earth metal sulfonate having a base number of 200 mg KOH / g or more by the perchloric acid method, and functions as a metal detergent. Specific examples thereof include calcium sulfonate, magnesium sulfonate, and barium sulfonate. From the viewpoint of the effect of the invention, calcium sulfonate and magnesium sulfonate are particularly preferable.
As the above-mentioned alkaline earth metal sulfonates, those having a base number of 200 mgKOH / g or more may be used alone, or two or more kinds may be used in combination. This alkaline earth metal sulfonate is obtained by overbasing with alkaline earth metal hydroxide or carbonate, and has a base number of 200 mgKOH / g or more by the perchloric acid method.
However, if the base number of the alkaline earth metal sulfonate as the component (a) exceeds 500 mgKOH / g, the intermetallic μ-V characteristics may be deteriorated. Therefore, the base number of the component (a) is preferably 200 mgKOH / g or more and 500 mgKOH / g or less, and more preferably 250 mgKOH / g or more and 450 mgKOH / g or less.
In addition, the alkaline earth metal sulfonate which is the component (a) is mixed with one or more kinds of low basic alkali earth metal sulfonates having a base number of less than 200 mgKOH / g and low basic alkali earth metal salsylates. In addition, it can be used in combination in a blending amount within a range that does not significantly deteriorate the μ-V characteristics between metals.

The blending amount of the component (a) in the present composition is 150 mass ppm or more and 900 mass ppm or less based on the total amount of the composition.
If the metal content is less than 150 ppm by mass based on the total amount of the composition, the coefficient of friction between metals cannot be sufficiently increased, and the problem of the present invention cannot be solved. On the other hand, if the metal content exceeds 900 ppm by mass, the inter-metal μ-V characteristics are deteriorated. Moreover, in order to further increase the coefficient of friction between metals and further improve the inter-metal μ-V characteristics, the metal content is preferably set to 200 mass ppm to 600 mass ppm, more preferably 300 mass ppm to 500 mass ppm. More preferably.

[Component (b)]
The component (b) in this composition is a sulfur-containing phosphorus compound. In particular, the phosphite or phosphate ester containing sulfur in the molecule as shown in the following general formulas (1) and (2) improves the intermetallic friction coefficient, improves the intermetallic friction coefficient, and intermetallic μ-V characteristics. It is preferable from the viewpoint of improvement. These may be used alone or in combination of two or more.

In the above formula (1), R ¹ independently represents a hydrocarbon group having 6 to 20 carbon atoms, specifically, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, Alkyl groups such as dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, and hexadecyl group, cycloalkyl groups such as cyclohexyl group, methylcyclohexyl group, ethylcyclohexyl group, propylcycloalkyl group, and dimethylcycloalkyl group, phenyl group, Aryl group such as methylphenyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, and naphthyl group, benzyl group , Phenylethyl group And arylalkyl groups such as methylbenzyl group, phenylpropyl group, and phenylbutyl group.
Among these, an alkyl group having 8 to 16 carbon atoms is preferable from the viewpoint of improving the coefficient of friction between metals and improving the μ-V characteristic between metals.

In the above formula (1), m and n are either 0, 1 or 2 but are not 0 at the same time, and m + n from the viewpoint of improving the intermetallic friction coefficient and improving the intermetallic μ-V characteristics. Is preferably 2 or less.
In the above formula (1), R ² and R ³ independently represent an alkylene group having 1 to 6 carbon atoms, but the number of carbon atoms is from the viewpoint of improving the intermetallic friction coefficient and improving the intermetallic μ-V characteristics. It is preferably 1 or 2.

  Specific examples of the phosphite of the above formula (1) include mono (octylthioethyl) phosphite, mono (dodecylthioethyl) phosphite, mono (hexadecylthioethyl) phosphite, di (octylthioethyl) Phosphite, di (dodecylthioethyl) phosphite, di (hexadecylthioethyl) phosphite, mono (octyloxyethylthioethyl phosphite), mono (dodecyloxyethylthioethyl) phosphite, mono (hexadecyloxyethylthio) Examples include ethyl) phosphite, di (octyloxyethylthioethyl) phosphite, di (dodecyloxyethylthioethyl) phosphite, and di (hexadecyloxyethylthioethyl) phosphite.

In the above formula (2), R ⁴ represents a hydrocarbon group having 2 to 20 carbon atoms, and it is the same as R ^{1 in the} above formula (1) to improve the intermetallic friction coefficient and reduce the intermetallic μ It is preferable from the viewpoint of improvement of -V characteristics.
In the formula (2), p represents an integer of 0 to 3, preferably 2 or 3, and more preferably 3.

  Specific examples of the phosphate ester of the above formula (2) include tributyl thiophosphate, trioctyl thiophosphate, tridecyl thiophosphate, tridodecyl thiophosphate, trihexadecyl thiophosphate, trioctadecyl thiophosphate, triphenyl thiophosphate. , Tricresyl thiophosphate, tributylphenyl thiophosphate, trihexylphenyl thiophosphate, trioctylphenyl thiophosphate, tridecylphenyl thiophosphate, and the like.

When the blending amount of the component (b) is small, the intermetallic friction coefficient cannot be sufficiently increased, and good intermetallic μ-V characteristics may not be obtained. Therefore, the blending amount of the component (b) is preferably 100 ppm by mass or more in terms of phosphorus on the basis of the total amount of the composition. On the other hand, when the amount of the component (b) is excessive, the intermetallic μ-V characteristics may be deteriorated. Therefore, the amount of the component (b) is 600 ppm by mass or less in terms of phosphorus. Is preferred. Further, in order to further increase the coefficient of friction between metal surfaces and further improve the inter-metal μ-V characteristics, the amount of component (b) should be 200 ppm by mass or more and 500 ppm by mass or less in terms of phosphorus. Preferably, it is more preferable to set it to 200 mass ppm or more and 400 mass ppm or less.
It should be noted that phosphorous ester, phosphite ester or their amine salts that do not contain sulfur compared to the sulfur-containing phosphorus compound of component (b) as the phosphorus compound, the intermetallic friction coefficient or intermetallic μ-V characteristics are significantly deteriorated. You may use it combining in the range which does not make it.

[Component (c)]
The component (c) in the present composition is an aliphatic primary amine and is effective for improving the intermetallic μ-V characteristics. In particular, at least one selected from alkylamines and alkenylamines is preferable.
Here, if the number of carbon atoms of the component (c) is too large, for example, if the alkyl group or alkenyl group is too long, it is difficult to satisfy both the intermetal friction coefficient and the intermetal μ-V characteristics. Therefore, the carbon number of the component (c) is 14 or less.
On the other hand, if the number of carbon atoms in the component (c) is too small, for example, if the alkyl group or alkenyl group is too short, the intermetallic μ-V characteristics may be deteriorated, and the component may not be dissolved in the base oil. Accordingly, the number of carbon atoms in component (c) is preferably 6 or more.
The number of carbon atoms in the component (c) is more preferably in the range of 8 to 14, and further preferably in the range of 8 to 12.

The above-described alkyl group or alkenyl group may be linear or branched, but is preferably linear from the viewpoint of improving the intermetallic μ-V characteristics.
Specific examples of the alkylamine and alkenylamine include hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexenylamine, octenylamine, decenylamine, dodecenylamine, and tetradecenylamine. Natural materials such as amines may be used.

When the amount of the component (c) is small, sufficient inter-metal μ-V characteristics cannot be obtained. When the amount is excessive, the intermetallic friction coefficient may be lowered. It is the range of 100 mass ppm or more and 700 mass ppm in terms of nitrogen based on the total amount.
Furthermore, in order to improve the intermetal friction coefficient and the intermetal μ-V characteristics, the amount of the component (c) is preferably 130 mass ppm or more and 500 mass ppm or less in terms of nitrogen, and 200 mass. More preferably, it is at least ppm and at most 400 mass ppm.
In addition, a secondary or tertiary amine or a primary amine having 15 or more carbon atoms may be used in combination with the component (c) as long as the friction coefficient between metals and the metal μ-V characteristics are not significantly deteriorated.

  The above-described composition keeps the transmission torque capacity (coefficient of friction between metals) of the metal belt CVT and the chain CVT high, is excellent in inter-metal μ-V characteristics related to vibration and noise, and can maintain these characteristics for a long period of time. . Therefore, in an automobile equipped with a metal belt CVT or a chain CVT, it is effective for improving and maintaining riding comfort and improving fuel consumption, and has high utility value as a CVT lubricant. Of course, it goes without saying that the composition is also suitable as a lubricating oil (ATF) for a multi-stage automatic transmission.

[Other additives]
In the present composition, other additives such as an antioxidant, a viscosity index improver, an ashless dispersant, a sulfur-based extreme pressure agent, copper, and the like are added as necessary, as long as the effects of the present invention are not impaired. You may mix | blend an inactivator, a rust preventive agent, a friction modifier, an antifoamer, etc.

Examples of the antioxidant include amine-based antioxidants (diphenylamines and naphthylamines), phenol-based antioxidants, sulfur-based antioxidants, and the like. A preferable blending amount of the antioxidant is about 0.05% by mass or more and 7% by mass or less.
As the viscosity index improver, for example, polymethacrylate, dispersed polymethacrylate, olefin copolymer (for example, ethylene-propylene copolymer), dispersed olefin copolymer, styrene copolymer (for example, Styrene-diene copolymer, styrene-isoprene copolymer, etc.). A preferable blending amount of the viscosity index improver is about 0.5% by mass or more and 15% by mass or less based on the total amount of the composition from the viewpoint of blending effect.

Examples of the ashless dispersant include a succinimide compound, a boron imide compound, and an acid amide compound. A preferable blending amount of the ashless dispersant is about 0.1% by mass or more and 20% by mass or less based on the total amount of the composition.
Examples of the sulfur-based extreme pressure agent include thiadiazole-based compounds, polysulfide-based compounds, thiocarbamate-based compounds, sulfurized fat and oil-based compounds, and sulfurized olefin-based compounds. Among these sulfur compounds, thiadiazole compounds and polysulfide compounds are preferable from the viewpoints of seizure resistance of metals and wear resistance between metals. These sulfur compounds may be used alone or in combination of two or more. A preferable blending amount of the sulfur-based extreme pressure agent is about 0.02 mass% or more and 2 mass% or less.

Examples of the copper deactivator include benzotriazole, benzotriazole derivatives, triazole, triazole derivatives, imidazole, imidazole derivatives, thiadiazole, and thiadiazole derivatives. A preferable compounding amount of the copper deactivator is about 0.01% by mass or more and 5% by mass or less based on the total amount of the composition.
Examples of the rust inhibitor include fatty acid, alkenyl succinic acid half ester, fatty acid soap, alkyl sulfonate, polyhydric alcohol fatty acid ester, fatty acid amide, oxidized paraffin, and alkyl polyoxyethylene ether. A preferable blending amount of the rust inhibitor is about 0.01% by mass or more and 3% by mass or less based on the total amount of the composition.

Examples of the friction modifier include carboxylic acids, carboxylic acid esters, oils and fats, carboxylic acid amides, and sarcosine derivatives. A preferable blending amount of the friction modifier is about 0.01% by mass or more and 5% by mass or less.
Examples of antifoaming agents include silicone compounds, fluorinated silicone compounds, and ester compounds. A preferable blending amount of the antifoaming agent is about 0.01% by mass or more and 5% by mass or less based on the total amount of the composition.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited at all by these examples. In addition, the performance (coefficient of friction between metals, μ-V characteristics between metals) of the lubricating oil composition (sample oil) in each example was obtained by the following method.

(1) Coefficient of friction between metals It evaluated using the block on-ring tester (made by Farex) based on ASTM D2714. The higher the coefficient of friction between metals, the greater the transmission torque capacity. The evaluation conditions are as follows.
<Running condition>
Surface pressure: 0.8 GPa
Oil temperature: 80 ° C
Sliding speed: 0.5m / s
Time: 30 minutes <Measurement conditions>
Surface pressure: 0.8 GPa
Oil temperature: 80 ° C
Sliding speed: 0.2m / s
<Specimen material>
Steel-steel

(2) μ-V characteristics between metals (μ ratio)
Evaluation was carried out using a cylinder-on-block type reciprocating friction tester (manufactured by Cameron Print). As the μ ratio is smaller, vibration and noise are less likely to occur. The evaluation conditions are as follows.
<Running condition>
Surface pressure: 0.8 GPa
Oil temperature: 80 ° C
Average sliding speed: 0.16 m / s
Time: 10 minutes <Measurement conditions>
Surface pressure: 0.8 GPa
Oil temperature: 80 ° C
Average sliding speed: 0.03 m / s, 0.1 m / s
<Specimen material>
Steel-steel (cylinder: diameter 15 mm, contact length 3 mm)
<Calculation method of μ ratio>
μ ratio = (friction coefficient at 0.03 m / s) / (friction coefficient at 0.1 m / s)

[Examples 1 to 13, Comparative Examples 1 to 13]
A lubricating composition for a transmission (sample oil) was prepared according to the formulation shown in Tables 1 and 2 using the following lubricating base oil and various additives. Each performance of the sample oil was evaluated by the method described above. The results are shown in Tables 1 and 2.

The details of the base oils and additives used in Tables 1 and 2 are as follows.
1) Base oil: paraffinic mineral oil (kinematic viscosity at 40 ° C .: 21 mm ² / s, kinematic viscosity at 100 ° C .: 4.5 mm ² / s)
2) High base number Ca sulfonate: calcium sulfonate having a base number of 300 mg KOH / g 3) High base number Mg sulfonate: Magnesium sulfonate having a base number of 400 mg KOH / g 4) Low base number Ca sulfonate: Calcium sulfonate having a base number of 10 mg KOH / g 5) Sulfur-containing phosphorus compound A: Di (octylthioethyl) phosphite 6) Sulfur-containing phosphorus compound B: Triphenylthiophosphate 7) Phosphite ester: Dioleyl hydrogen phosphite 8) Neutral phosphate ester: tricresyl Phosphate 9) Other additives: Antioxidants, viscosity index improvers, ashless dispersants, sulfur extreme pressure agents, copper deactivators, rust inhibitors, friction modifiers, and defoamers 10) Commercial CVTF : SUBARRU CVT C-30
11) Commercial ATF: VW ATF G052516A2

〔Evaluation results〕
Reference Example 1 in Table 2 is a commercially available CVTF, and Reference Example 2 is a commercially available ATF. Commercially available CVTF has a high coefficient of friction between metals, but is insufficient because the μ ratio is large. On the other hand, the μ ratio of commercially available ATF is small and good, but it is insufficient because the coefficient of friction between metals is small. Therefore, the required performance of the lubricating oil composition is that the coefficient of friction between metals is equal to or higher than that of commercially available CVTF, and the μ ratio is equal to or lower than that of commercially available ATF.

As shown in Tables 1 and 2, the lubricating oil compositions of the present invention (Examples 1 to 13) were prepared by blending a predetermined alkaline earth metal sulfonate, a sulfur-containing phosphorus compound and an aliphatic primary amine into the base oil. Therefore, the coefficient of friction between metals is high, and the inter-metal μ-V characteristic (μ ratio) is excellent.
On the other hand, the lubricating oil compositions of Comparative Examples 1 to 10 were insufficient in the characteristics of either or both of the coefficient of friction between metals and the μ ratio. For example, in Comparative Examples 1 and 2, a primary amine having an alkyl group with 18 carbon atoms is blended, but both the intermetal friction coefficient and the μ ratio cannot be satisfied. In Comparative Example 3, a large amount of tertiary amine was blended, but the effect of improving the μ ratio was not observed. In Comparative Example 4, since the blending amount of the octylamine as the component (c) is excessive, the friction coefficient between metals decreases. On the other hand, when the blending amount of octylamine is small as in Comparative Example 5, the μ ratio is large. It is had. In Comparative Example 6, only a low base as Ca sulfonate was blended, but both the intermetal friction coefficient and the μ ratio were insufficient. In Comparative Example 7, since the blending amount of the high base number Ca sulfonate of the component (a) is small, the intermetallic friction coefficient cannot be increased. On the other hand, the blending amount of the high base number Ca sulfonate is as in Comparative Example 8. If it was excessive, the μ ratio was increased. In Comparative Examples 9 and 10, a phosphorus compound not containing sulfur was blended, but the intermetal friction coefficient and μ ratio were not satisfactory.

Claims (6)

The base oil is blended with (a) an alkaline earth metal sulfonate having a base number of 200 mgKOH / g or more, (b) a sulfur-containing phosphorus compound, and (c) an aliphatic primary amine,
The blending amount of the component (a) is 150 mass ppm or more and 900 mass ppm or less in terms of alkaline earth metal conversion amount based on the total amount of the composition,
Wherein (c) the number of carbon atoms of the component is 14 or less, the amount is Ri 700 mass ppm der less than 100 ppm by mass of nitrogen in terms of the amount of the total amount of the composition,
The lubricating oil composition characterized by Ru der variable-type automatic transmission. The lubricating oil composition according to claim 1, wherein
The lubricating oil composition, wherein the component (a) is at least one selected from calcium sulfonate and magnesium sulfonate. The lubricating oil composition according to claim 1 or 2,
The lubricating oil composition, wherein the component (b) is at least one selected from sulfur-containing phosphites and sulfur-containing phosphates. In the lubricating oil composition according to any one of claims 1 to 3,
The lubricating oil composition, wherein the component (c) is at least one selected from alkylamines and alkenylamines. In the lubricating oil composition according to any one of claims 1 to 4 ,
The continuously variable automatic transmission is a metal belt type or a chain type. In the lubricating oil composition according to any one of claims 1 to 5,
The lubricating oil composition does not contain an aliphatic dicarboxylic acid
A lubricating oil composition characterized by that.