JPWO2015034091A1 - Transmission oil - Google Patents

Abstract

A transmission oil obtained by mixing calcium carbonate with a base oil, wherein the calcium carbonate is dispersed in the transmission oil as an aggregate structure, and a ratio of the aggregate structure having a particle diameter of 200 nm or more is included. The aggregate structure is based on the total amount of the aggregated structure and is 10% by mass or more and 35% by mass or less in terms of calcium, and the base number of the transmission oil by the hydrochloric acid method is 0.5 mgKOH / g or more and 4 mgKOH / g or less.

Description

  The present invention relates to transmission oil.

An automatic transmission (AT) is a transmission having a mechanism in which a transmission torque ratio is automatically set in accordance with a vehicle speed, a load size, and the like. A torque converter, a gear mechanism, a hydraulic mechanism, And a wet clutch. As a transmission, a continuously variable transmission (CVT) is often used, and a method of transmitting torque by friction between a metal belt or metal chain and a metal pulley is well known. Furthermore, in recent years, vehicles equipped with a dual clutch (DCT) have begun to appear on the market. DCT is a kind of AT, but dedicated clutches are prepared for odd-numbered and even-numbered gears, and the gears of the next gear are meshed in advance at the time of gear shifting, so that a quick gear shifting can be achieved simply by switching the clutch.
Various transmission oils have been proposed for such various transmissions. In particular, transmission oil having a high static friction coefficient (μs) and a high dynamic friction coefficient (μd) is required from the viewpoint of transmission torque capacity. For example, Patent Document 1 describes a lubricating oil composition obtained by blending a lubricating base oil with a polyol compound, an alkali metal borate, an ashless dispersant, and an alkaline earth metal sulfonate. According to this composition, the static friction coefficient (μs) and the dynamic friction coefficient (μd) of the wet clutch can be simultaneously increased (see paragraph [0073] [Effects of the invention]).

JP 2005-8695 A

In any of the above-described AT, CVT, and DCT, it is desirable that the coefficient of static friction (μs) is large in order to ensure the transmission torque capacity.
However, even the transmission oil described in Patent Document 1 described above is not necessarily sufficient for improving the coefficient of static friction (μs). Further, the structure of the transmission oil is complicated and there is a problem in cost.
Further, in any of the AT, CVT, and DCT described above, the dynamic friction coefficient (μd) of the transmission oil decreases over a long period of use, and vibration of the entire vehicle due to stick-slip phenomenon of the clutch sliding portion. (Shadder) is likely to occur. Therefore, from a practical point of view, a long clutch life, specifically, a long shudder life is required.
However, even the transmission oil described in Patent Document 1 described above does not necessarily have sufficient maintenance performance with respect to the dynamic friction coefficient (μd) after long-term use. Further, the structure of the transmission oil is complicated and there is a problem in cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission oil having a large static friction coefficient (μs) and a high dynamic friction coefficient (μd) for a long period of time while having a simple configuration, and having a long clutch life.

In order to solve the above problems, the present invention provides the following transmission oil.
A transmission oil obtained by mixing calcium carbonate with a base oil, wherein the calcium carbonate is dispersed in the transmission oil as an aggregate structure, and a ratio of the aggregate structure having a particle diameter of 200 nm or more is included. Transmission oil characterized in that it is 10 mass% or more and 35 mass% or less in terms of calcium based on the total amount of the aggregate structure, and the base number of the transmission oil according to hydrochloric acid method is 0.5 mgKOH / g or more and 4 mgKOH / g or less. .

  ADVANTAGE OF THE INVENTION According to this invention, although it is a simple structure, a static friction coefficient (microsecond) is large, a high dynamic friction coefficient (microd) can be maintained for a long time, and the transmission oil with a long clutch life can be provided.

  The present invention is a transmission oil in which calcium carbonate is blended with a base oil, and the calcium carbonate is dispersed in the transmission oil as an aggregated structure, and the aggregated structure has a particle diameter of 200 nm or more. The percentage of the aggregated structure is 10 mass% or more and 35 mass% or less in terms of calcium based on the total amount of the aggregated structure, and the base number of the transmission oil according to the hydrochloric acid method is 0.5 mgKOH / g or more and 4 mgKOH / g or less And The transmission oil of the present invention (hereinafter also referred to as “the present transmission oil”) will be described in detail below. Here, the transmission oil obtained by blending calcium carbonate with the base oil is not only a transmission oil containing the base oil and calcium carbonate, but the component is modified in place of at least one component of the base oil or calcium carbonate. It also means a composition containing a modified product or a composition containing a reaction product by reacting the component.

The base oil used for the transmission oil is not particularly limited, and may be at least one of mineral oil and synthetic oil, that is, each alone or in combination of two or more, or may be used in combination of mineral oil and synthetic oil. .
These mineral oils and synthetic oils are not particularly limited, but can be applied as long as they are generally used as base oils for transmissions. In particular, it is preferable to use a base oil having a kinematic viscosity at 100 ° C. of 1 mm ² / s to 50 mm ² / s, particularly 2 mm ² / s to 15 mm ² / s. If the kinematic viscosity at 100 ° C. of the base oil is 1 mm ² / s or more, an increase in wear at sliding parts such as a gear bearing and a clutch of the transmission is suppressed, and the kinematic viscosity at 100 ° C. of the base oil is 50 mm ² / s. If it is s or less, it is anticipated that low temperature viscosity will suppress deterioration.
Further, the pour point, which is an index of the low temperature fluidity of the base oil, is not particularly limited, but is preferably −10 ° C. or lower, particularly preferably −15 ° C. or lower.
Furthermore, although it does not restrict | limit especially as base oil, It is preferable that a saturated hydrocarbon component is 90 mass% or more, a sulfur content is 0.03 mass% or less, and a viscosity index is 100 or more. Here, when the saturated hydrocarbon component is 90% by mass or more, the amount of the deteriorated product can be reduced. Further, when the sulfur content is 0.03% by mass or less, the amount of deteriorated product can be reduced. Furthermore, when the viscosity index of the base oil is 100 or more, wear at high temperatures can be reduced.

Examples of such mineral oil include naphthenic mineral oil, paraffinic mineral oil, GTL WAX, and the like. Specific examples include light neutral oil, medium neutral oil, heavy neutral oil, bright stock and the like by solvent refining or hydrogenation refining.
On the other hand, as synthetic oil, polybutene or a hydride thereof, polyalphaolefin (1-octene oligomer, 1-decene oligomer, etc.), alkylbenzene, polyol ester, dibasic acid ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester, Examples include polyoxyalkylene glycol ethers, hindered esters, and silicone oils.

In the above base oil, it is preferable to blend (mix) polyalphaolefin (PAO) from the viewpoint of the effects of the invention. Examples of PAO include not only an alpha olefin homopolymer but also an alpha olefin copolymer. The proportion of PAO in the base oil is preferably 30% by mass or more, and more preferably 50% by mass or more. Also, 100 ° C. kinematic viscosity of PAO is preferably not more than ^{2 mm} 2 / s or more 200 mm ² / s.

  The transmission oil contains a specific form of calcium carbonate (hereinafter also referred to as “the present calcium carbonate”). The present calcium carbonate is dispersed in the transmission oil as an aggregate structure. Among such aggregate structures, the ratio of those having a particle diameter of 200 nm or more (hereinafter also referred to as “large particles”) is 10 mass% or more and 35 mass% or less based on the total mass of the aggregate structure and in terms of calcium. Yes, preferably 15% by mass or more and 30% by mass or less. When the large particles in the aggregated structure are in the above range, the coefficient of static friction (μs) is large when the transmission oil is used, and a high dynamic friction coefficient (μd) can be maintained for a long time. In addition, the above-described aggregate structure preferably has an average particle size of 10 nm to 180 nm, and more preferably 30 nm to 150 nm, from the viewpoint of the effects of the invention.

The above-mentioned aggregated structure can be determined for its particle size, particle size distribution, and average particle size by electrophoretic light scattering. For example, a particle size measurement system using ELSZ-1000S manufactured by Otsuka Electronics is suitable.
In order to obtain a transmission oil in which a large amount of large particles are dispersed by blending the present calcium carbonate with a base oil, for example, calcium carbonate having an aggregate structure having a predetermined particle size distribution is added to the base oil or an arbitrary transmission oil. You may mix | blend and you may mix | blend the overbased organic acid calcium salt compound (for example, overbased detergent) containing a predetermined aggregate structure. In the latter case, the calcium carbonate is attributed to the overbased organic acid calcium salt compound. The production method of calcium carbonate, which is an aggregate structure, is not particularly limited. For example, after neutralizing an organic acid with basic calcium oxide or hydroxide, excess basic calcium oxide or hydroxide is added. It can be obtained by carbonation.

The blending amount of the calcium carbonate is preferably 0.001% by mass or more and 0.3% by mass or less, and 0.001% by mass or more and 0.2% by mass or less in terms of calcium based on the total amount of the transmission oil. Is more preferable, and more preferably 0.01% by mass or more and 0.2% by mass or less. When the blending amount of the present calcium carbonate is within the above range, the static friction coefficient (μs) can be sufficiently increased, and a high dynamic friction coefficient (μd) can be maintained for a long time.
The ratio of large particles in the transmission oil is preferably 0.056% by mass or less, and more preferably 0.045% by mass or less, based on the total amount of the transmission oil. When the ratio of large particles in the transmission oil is in the above range, the static friction coefficient (μs) can be sufficiently increased, and the high dynamic friction coefficient (μd) can be maintained for a long time.

Among the overbased organic acid calcium salt compounds, the overbased detergent is preferably at least one of sulfonate, salicylate and finate from the viewpoint of the effect of the invention.
This transmission oil has a base number (JIS K2501) by the hydrochloric acid method of 0.5 mgKOH / g or more and 4 mgKOH / g or less, preferably 0.8 mgKOH / g or more and 3.5 mgKOH / g or less. When the base number is within the above range, the static friction coefficient (μs) can be sufficiently increased, and a high dynamic friction coefficient (μd) can be maintained for a long time.
The detergent itself may contain calcium carbonate and be overbased, and the base number is not particularly limited, but the total base number (JIS K2501) by the perchloric acid method is 10 mgKOH / g or more and 400 mgKOH / g or less. Preferably there is.
The transmission oil preferably has a kinematic viscosity at 100 ° C. of 3 mm ² / s or more and 8 mm ² / s or less, and more preferably 4 mm ² / s or more and 7 mm ² / s or less from the viewpoint of the effect of the invention. Moreover, it is preferable that the viscosity index of this transmission oil is 100 or more.

  The present transmission oil can contain various additives as long as the object of the present invention is not impaired. Examples of additives include viscosity index improvers, antioxidants, antiwear agents, friction modifiers, ashless dispersants, metal deactivators, rust inhibitors, antifoaming agents, pour point depressants, interfaces. An activator, a colorant, and the like are appropriately used.

Examples of the viscosity index improver include polymethacrylate, dispersed polymethacrylate, olefin copolymer (for example, ethylene-propylene copolymer), dispersed olefin copolymer, styrene copolymer (for example, styrene- Diene copolymer, styrene-isoprene copolymer, etc.). The blending amount of the viscosity index improver is about 0.5% by mass or more and 15% by mass or less on the basis of the total amount of the transmission oil in terms of blending effect.
As the pour point depressant, for example, polymethacrylate having a mass average molecular weight of about 10,000 to 150,000 is used. A preferable blending amount of the pour point depressant is about 0.01% by mass or more and 10% by mass or less based on the total amount of the transmission oil.

Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.
Examples of amine-based antioxidants include monoalkyl diphenylamines such as monooctyldiphenylamine and monononyldiphenylamine, 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, and 4,4 ′. -Dialkyldiphenylamines such as diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, polyalkyldiphenylamines such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine, α -Naphtylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α There may be mentioned naphthylamine systems such as -naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine, and nonylphenyl-α-naphthylamine. In particular, compounds having 4 to 24 carbon atoms, particularly 6 to 18 carbon atoms in the alkyl group are preferably used. These compounds may be used alone or in combination of two or more.

  As phenolic antioxidants, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4,4'-methylenebis (2,6-di-t-butylphenol) 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6- t-butylphenol), 4,4'-isopropylidenebisphenol, 2,4-dimethyl-6-t-butylphenol, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t -Butyl-4-hydroxybenzyl) benzene, and 2,6-di-t-butyl Examples include ru-4-ethylphenol.

As sulfur-based antioxidants, dialkylthiodipropionate, dialkyldithiocarbamic acid derivatives (excluding metal salts), bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide, mercaptobenzothiazole, pentasulfide The reaction product of phosphorus and an olefin, dicetyl sulfide, etc. are mentioned.
The various antioxidants described above are used alone or in combination of two or more. In particular, amines, phenols, zinc alkyldithiophosphates and the like are preferably used. These antioxidants are preferably blended at a ratio of 0.05% by mass or more and 3% by mass or less based on the total amount of the transmission oil.

Examples of antiwear agents include thiophosphate metal salts (Zn, Pb, Sb, etc.), thiocarbamic acid metal salts (Zn, etc.), sulfur compounds, phosphate esters (tricresyl phosphate), phosphites, etc. These are preferably blended at a ratio of about 0.05% by mass or more and 5% by mass or less based on the total amount of the transmission oil.
Examples of the friction modifier include polyhydric alcohol partial esters such as neopentyl glycol monolaurate, trimethylolpropane monolaurate, and glycerin monooleate (oleic acid monoglyceride). A preferable blending amount of the friction modifier is about 0.05% by mass or more and 4% by mass or less based on the total amount of the transmission oil.
Examples of the ashless dispersant include succinimides, boron-containing succinimides, benzylamines, boron-containing benzylamines, succinic esters, monovalent or divalent typified by fatty acids or succinic acid. Examples thereof include amides of carboxylic acids. 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 transmission oil.

As the metal deactivator, for example, benzotriazole, thiadiazole and the like are used alone or in combination of two or more. These metal deactivators are preferably blended at a ratio of about 0.01% by mass or more and 5% by mass or less based on the total amount of the transmission oil.
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, alkyl polyoxyethylene ether and the like. 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 transmission oil.
As the antifoaming agent, for example, a silicone compound, an ester compound, or the like is used alone or in combination of two or more. These antifoaming agents are preferably blended at a ratio of about 0.05% by mass or more and 5% by mass or less based on the total amount of the transmission oil.

As the pour point depressant, for example, polymethacrylate is used. The pour point depressant is preferably blended at a ratio of about 0.01% by mass or more and 10% by mass or less based on the total amount of the transmission oil.
For example, polyoxyethylene alkylphenyl ether is used as the surfactant. This surfactant is preferably blended at a ratio of about 0.01% by mass or more and 10% by mass or less based on the total amount of the transmission oil.

  Since the transmission oil of the present invention described above has a high static friction coefficient (μs), the transmission torque capacity is high, and since the high dynamic friction coefficient (μd) can be maintained for a long time, the clutch life is also long. The present invention can be preferably applied to various transmissions such as a step transmission (CV) and a dual clutch (DCT).

Next, the present invention will be described in more detail with reference to examples and comparative examples. In addition, this invention is not restrict | limited at all to description content, such as these Examples.
[Example 1, Comparative Examples 1-2]
Using PAO (100 ° C. kinematic viscosity 4.0 mm ² / s) as the base oil, 0.15% by mass of the overbased calcium sulfonate having the properties shown in Table 1 on the basis of the total amount of sample oil and converted to calcium, Sample oils having the properties shown in Table 1 were prepared (all were assumed for transmission). The viscosity index of each sample oil was 120 in all of Example 1, Comparative Example 1, and Comparative Example 2.
About the said overbased calcium, it was disperse | distributed to base oil and the structure of the aggregate structure was confirmed. Specifically, the dispersion state of the aggregate structure (large particles) in each sample oil was measured with ELSZ-1000S manufactured by Otsuka Electronics Co., Ltd., and the proportion of large particles in the aggregate structure composed of calcium carbonate (aggregate structure standard) , Mass%) and average particle size. The results are shown in Table 1.

〔Evaluation method〕
Using an LVFA friction tester, the static friction coefficient (μs) and dynamic friction coefficient (μd after 120 hours) of each sample oil were measured under the experimental conditions shown below (conforms to JASO M349-2001). The friction coefficient when the rotation speed was 3 rpm was μs. Practically, μs is preferably 0.08 or more, and μd is preferably maintained at 0.10 or more. The results are shown in Table 1.
Material: Cellulosic clutch material used in actual missions Surface pressure: 1.0 MPa
Oil temperature: 120 ° C
Number of revolutions: 1 rpm to 10 rpm (in steps of 1 rpm), 20 rpm, 30 rpm

〔Evaluation results〕
From the results of Table 1, the sample oil of Example 1 containing large particles (aggregated structure having a particle diameter of 200 nm or more) in a predetermined range has a practically sufficient coefficient of static friction (μs), and after a lapse of time. The coefficient of dynamic friction (μd) also shows a large value. That is, it can be seen that both high torque capacity and clutch life can be achieved. On the other hand, in the sample oils of Comparative Examples 1 and 2, since the proportion of large particles deviates from the predetermined range, even if the blending amount of the overbased calcium sulfonate and the base number of the sample oil are similar. The decrease in the coefficient of dynamic friction (μd) is much larger than that in Example 1. Therefore, the importance of including a large range of large particles in the transmission oil can be understood.

Claims (8)

A transmission oil comprising calcium carbonate in a base oil,
The calcium carbonate is dispersed in the transmission oil as an aggregate structure,
The ratio of the aggregate structure having a particle diameter of 200 nm or more is 10 mass% or more and 35 mass% or less in terms of calcium based on the total mass of the aggregate structure, and the base number by the hydrochloric acid method of the transmission oil is 0. Transmission oil characterized by being 5 mgKOH / g or more and 4 mgKOH / g or less. The transmission oil according to claim 1,
The calcium carbonate is derived from an overbased organic acid calcium salt compound;
The transmission oil characterized in that the blending amount of the calcium carbonate is 0.001% by mass or more and 0.3% by mass or less in terms of calcium based on the total transmission oil. The transmission oil according to claim 2,
The overbased organic acid calcium salt compound is an overbased detergent;
The transmission oil, wherein the overbased detergent is at least one of sulfonate, salicylate, and finate. In the transmission oil according to any one of claims 1 to 3,
The transmission oil characterized in that the base oil contains polyalphaolefin. The transmission oil according to claim 4,
The transmission oil characterized in that the proportion of polyalphaolefin in the base oil is 30% by mass or more. In the transmission oil according to claim 4 or 5,
A transmission oil, wherein the polyalphaolefin has a kinematic viscosity at 100 ° C. of 2 mm ² / s or more and 200 mm ² / s or less. In the transmission oil according to any one of claims 1 to 6,
The transmission oil has a 100 ° C. kinematic viscosity of 3 mm ² / s to 8 mm ² / s,
A transmission fluid characterized in that the transmission fluid has a viscosity index of 100 or more. In the transmission oil according to any one of claims 1 to 7,
Transmission oil characterized by being used in automatic transmissions or continuously variable transmissions.