JP2009203385A - Lubricating oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition exhibiting a low traction coefficient compared to a refined mineral oil and a hydrocarbon synthetic oil, and having a high flash point, application thereof, and a method of reducing the traction coefficient of the lubricating oil composition. <P>SOLUTION: This lubricating oil composition contains a component A and a component B, the component A is at least one monoester expressed by general formula (1) where R<SP>1</SP>, R<SP>2</SP>are each hydrocarbon groups and may be same or different from each other, and where total number of the R<SP>1</SP>, R<SP>2</SP>is 13-28, and the component B is at least one hydrocarbon synthetic oil having 20-3,000 mm<SP>2</SP>/s of kinetic viscosity at 100°C. In the lubricating oil composition, a content of the component A is 1-99 wt.%, a content of the component B is 99-1 wt.%, and the flash point is 170°C or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a lubricating oil composition, in particular, a low traction lubricating oil composition and a method for reducing the traction coefficient of the lubricating oil composition, and more specifically, for automobiles including rolling bearings, gears, cams and the like. The present invention relates to a lubricating oil composition used for lubricating gear mechanisms of gears and industrial gears.

In recent years, under the circumstances where countermeasures against global warming are indispensable, development of environmentally responsive lubricants having a large fuel saving effect has been strongly demanded as environmental protection measures for vehicles and other drive train power engines.
In response to such demands, as a method for reducing energy loss of drive system mechanical elements by lubricating oil, the stirring resistance has been reduced by lowering the viscosity of the lubricating oil, and the contact point between metals by the addition of a friction modifier. The friction is also reduced.

  Furthermore, energy loss reduction at the lubrication site of elastohydrodynamic lubrication (EHL) due to low traction is an effective means. Traction is the resistance of the lubricating oil itself to the shearing force acting on the oil film sandwiched between the rolling contact surfaces. Therefore, if such resistance can be controlled, it is presumed that energy loss at the lubrication site of the EHL can be suppressed.

  Under the above-mentioned development situation of the environment-friendly lubricating oil by reducing energy loss at the EHL lubrication site, as a low traction lubricating oil, for example, prior art 1 (US2006 / 0178279A1 (hereinafter “Patent Document 1”). )) Discloses a low traction lubricating oil prepared by a combination of a base oil and a traction reducing material. The patent document 1 describes a low-viscosity synthetic lubricating base oil and a monovalent fatty acid ester as traction reducing materials, and it is described that an effect of reducing the traction coefficient can be obtained.

  However, since the lubricating oil composition described in Patent Document 1 has a low-viscosity component, that is, a low molecular weight lubricating base oil, the lubricating oil used under high temperature conditions such as a gear mechanism is sufficient. The difficulty that a high flash point (for example, 170 ° C. or higher) cannot be obtained is included.

  In addition, lubricating oils comprising esters and high-viscosity base oils are already known, but the esters contained in conventional products are diesters and triesters produced using polybasic acids or polyhydric alcohols as raw materials. The traction coefficients of such esters are high levels of 0.035 and 0.04, respectively, and it is not possible to obtain a low traction lubricating oil using them. For example, Prior Art 2 (US Pat. No. 4,956,122 (hereinafter referred to as “Patent Document 2”) includes (a) a polyalphaolefin having a 100 ° C. kinematic viscosity of 40 to 100 cSt, and (b) a 100 ° C. kinematic viscosity. Wherein a lubricating oil composition comprising 1 to 10 cSt polyalphaolefin, (c) a substantially divalent fatty acid ester, and (d) an additive package is disclosed. Because it contains a low, low molecular weight polyalphaolefin, a high flash point cannot be obtained.

Prior art 3 (Japanese Patent Laid-Open No. 63-139150 (hereinafter referred to as “Patent Document 4”)) uses R ₁ —C _b —R ₂ (Cb is —O—CO— or -CO-O- monocarboxyl group) wherein R ₁ is a C ₄ -C ₁₀ tertiary alkyl group and R ₂ is a C ₁ -C ₂₀ alkyl group or a C ₂ -C ₂₀ alkenyl group. ing.

However, there is no disclosure or suggestion about either the traction coefficient or the flash point.
As described above, conventionally, environmentally friendly lubricating oil with low traction has been hardly proposed, and has been proposed slightly in the above-mentioned Patent Document 1, but the lubricating oil base exhibiting low traction disclosed therein is disclosed. The oil has a low flash point, and when used as a driving oil, there are practically difficult points, especially under high temperature conditions, and a lubricating oil having a low traction characteristic that can withstand use and a high flash point is disclosed. There was no situation.

US Publication No. 2006/0178279 US Pat. No. 4,956,122 JP-A-63-139150

  Therefore, in the first aspect of the present invention, in view of the development status of the conventional low traction lubricating oil as described above, refined mineral oil and polyalphaolefin (hereinafter referred to as “PAO”) by solvent refining or hydrotreating may be used. ) And ethylene alpha olefin copolymer (hereinafter sometimes referred to as “EAO”), etc., and a lubricating oil composition exhibiting a lower traction coefficient than that of a hydrocarbon-based synthetic oil and having a high flash point Is to provide.

A second problem is to provide a method for reducing the traction coefficient of a lubricating oil composition comprising a hydrocarbon-based synthetic oil such as PAO or EAO used as a lubricating base oil.
The third problem is to provide a method for producing a lubricating oil composition having a high flash point and a low traction coefficient using a hydrocarbon-based synthetic oil such as PAO and EAO.

A fourth object of the present invention is to provide a method of lubricating a gear device capable of suppressing energy loss in lubricating an automobile gear or an industrial gear.

  Therefore, as a result of intensive studies in order to solve the problems of the present invention, the present inventors cannot obtain a low traction coefficient with the diesters and triesters because the structural failure of such compounds. Based on the presumption that this is due to the large size, we focused on monoesters, which are expected to have fewer structural obstacles compared to diesters and triesters. Monoester has a smaller traction coefficient than diester or triester, and monoesters with hydrocarbon groups in a specific range have a low traction coefficient and a high flash point. Based on this, the present invention has been conceived.

Thus, according to the present invention,
A lubricating oil composition containing the following component A and component B,
The component A is represented by the following general formula (1):

(In the formula, R ¹ and R ² are each a hydrocarbon group, which may be the same or different from each other, and the total number of carbon atoms of R ¹ and R ² is 13 to 28.)
At least one monoester represented by:
Component B is at least one hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of ²⁰ to 3000 mm ² / s,
Based on the total weight of the total content of the component A and the component B,
The content of the component A is 1 to 99% by weight, the content of the component B is 99 to 1% by weight,
A lubricating oil composition is provided, wherein a flash point of the lubricating oil composition is controlled to 170 ° C. or higher.

Moreover, according to the present invention,
For a lubricating oil composition comprising a hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 20 to 3000 mm ² / s and a flash point of 170 ° C. or higher, the general formula (1);

(In the formula, R ¹ and R ² are each a hydrocarbon group, which may be the same or different from each other, and the total number of carbon atoms of R ¹ and R ² is 13 to 28.)
A method for reducing the traction coefficient of a lubricating oil composition comprising a hydrocarbon-based synthetic oil, comprising mixing an effective amount of at least one monoester represented by the following formula for the traction coefficient of the hydrocarbon-based synthetic oil: .

Furthermore, according to the present invention,
A lubricating oil composition containing the following component A and component B,
The component A is represented by the following general formula (1):

(In the formula, R ¹ and R ² are each a hydrocarbon group, which may be the same or different from each other, and the total number of carbon atoms of R ¹ and R ² is 13 to 28.)
At least one monoester represented by:
Component B is at least one hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of ²⁰ to 3000 mm ² / s,
Based on the total weight of the total content of component A and component B,
The content of the component A is 1 to 99% by weight, the content of the component B is 99 to 1% by weight,
There is provided a method for lubricating a gear mechanism, wherein the lubricating oil composition having a flash point controlled to 170 ° C. or higher is used for lubricating an automobile gear or an industrial gear.

According to the present invention, there is provided a lubricating oil composition comprising a monoester and a hydrocarbon-based synthetic oil, and further comprising at least one additive blended as necessary.
In addition, by mixing a monoester with a lubricating oil composition comprising a hydrocarbon-based synthetic oil, a method for reducing the traction coefficient of the lubricating oil composition while maintaining the flash point level is provided.
Further, although a method of lubricating a gear device using the lubricating oil composition is provided, further preferred embodiments include the following.

In the present specification, for convenience, the carbon number of the monoester hydrocarbon group R ¹ may be indicated as X, and the carbon number of R ² may be indicated as Y.
1) The lubricating oil composition, wherein the monoester and the hydrocarbon-based synthetic oil are lubricating base oils.
2) The said lubricating oil composition whose total carbon number (X + Y) of the said monoester is 14-25.
3) The said lubricating oil composition whose total carbon number (X + Y) of the said monoester is 14-25, and Y is 1-10.
4) The lubricating oil composition, wherein the hydrocarbon-based synthetic oil is a polyalphaolefin having a kinematic viscosity of 20 to 2000 mm ² / s at 100 ° C.
5) The lubricating oil composition, wherein the hydrocarbon-based synthetic oil is an ethylene-alphaolefin copolymer having a kinematic viscosity at 100 ° C. of 20 to 2000 mm ² / s.
6) The lubricating oil composition, wherein the polyalphaolefin has a kinematic viscosity at 100 ° C. of 40 to 1000 mm ² / s.
7) The lubricating oil composition, wherein the ethylene-polyalphaolefin copolymer has a kinematic viscosity at 100 ° C. of 40 to 2000 mm ² / s.
8) The lubricating oil composition comprising the monoester having a total carbon number (X + Y) of 14 to 25 and a polyalphaolefin having a kinematic viscosity of 20 to 2000 mm ² / s at 100 ° C.
9) The lubricating oil composition comprising the monoester having a total carbon number (X + Y) of 14 to 25 and an ethylene-alphaolefin copolymer having a kinematic viscosity of 20 to 2000 mm ² / s at 100 ° C.
10) A monoester having a total carbon number (X + Y) of 14 to 25 is mixed with a lubricating oil composition comprising a hydrocarbon-based synthetic oil having a traction coefficient exceeding 0.023, and the traction coefficient is set to 0.023. A method for reducing the traction coefficient of the lubricating oil composition, comprising:
11) The total number of carbon atoms in the lubricating oil composition composed of a hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 40 to 2000 mm ² / s and having a flash point of 170 ° C. or higher and a traction coefficient exceeding 0.023 ( A method for reducing the traction coefficient of the lubricating oil composition, comprising mixing a monoester having X + Y) of 14 to 25 and lowering the traction coefficient to 0.023 or less at a flash point of 170 ° C. or higher.
12) A lubricating oil composition comprising the above hydrocarbon-based synthetic oil is a polyalphaolefin having a kinematic viscosity at 100 ° C of 40 to 1000 mm ² / s or an ethylene-alphaolefin having a kinematic viscosity at 100 ° C of 40 to 2000 mm ² / s. A method for reducing the traction coefficient of the lubricating oil composition which is a copolymer.
13) The method for reducing the traction coefficient of the lubricating oil composition, wherein the conditions for measuring the traction coefficient are: peripheral speed; 3.1 m / sec average Hertz pressure; 0.7 GPa and oil temperature;
14) A method for lubricating a gear mechanism in which the automobile gear is an internal element of a manual transmission (MT), a manual transaxle (MTX), and a final reduction gear differential.

As described above, the lubricating oil composition according to the present invention comprises the specific component A and the specific component B, or when at least one additive for lubricating oil is blended, the following (1) and (2 ), The reciprocal performance can be satisfied at the same time.
(1) A traction coefficient lower than that of mineral oil and traction coefficients of hydrocarbon-based synthetic oils such as PAO and EAO is expressed.
(2) The flash point of the lubricating oil composition is 170 ° C. or higher.

In addition, such a low traction lubricating oil composition can contribute to smooth operation in a manual transmission (manual transmission (MT), manual transaxle (MTX), final reduction gear (diff)) as an automotive gear oil. In addition, as an energy-saving industrial gear oil, for example, it can be used efficiently even in the driving relationship of rolling equipment in ore and metal factories.

  According to the present invention, by mixing the above-mentioned specific monoester with a hydrocarbon-based synthetic oil such as polyalphaolefin or ethylene-alphaolefin copolymer having a traction coefficient exceeding 0.023, a hydrocarbon-based synthesis is performed. The oil traction coefficient can be significantly reduced.

Furthermore, according to the present invention, by mixing a specific hydrocarbon-based synthetic oil and a specific monoester, a traction coefficient lower than that of the hydrocarbon-based synthetic oil alone and the monoester alone can be obtained. It is possible to provide a simple and efficient method for producing a lubricating oil composition having a high flash point.

Hereinafter, the components of the lubricating oil composition according to the present invention will be described in detail.
1. Component A-Monoester A monoester that is a constituent of the lubricating oil composition according to the present invention is an ester derived from a monovalent carboxylic acid and a monohydric alcohol, and is represented by the following general formula (1);

The compound represented by these is included.

In the general formula (1), R ¹ and R ² are each a hydrocarbon group.
The hydrocarbon groups for R ¹ and R ² may be the same as or different from each other.
Further, an R ¹ and the total number of carbon atoms of the carbon atoms of each hydrocarbon group R ² (X + Y) is 13 to 28, preferably 14 to 25, more preferably from 15 to 25. Lubricating oil composition having a traction coefficient of 0.023 or less and a flash point of 170 ° C. or more by using a monoester having a total carbon number (X + Y) controlled to 13 to 28 as a constituent of the lubricating oil composition In contrast, when the total carbon number (X + Y) is 12 or less, there is a problem that a high flash point cannot be obtained. On the other hand, when the total carbon number (X + Y) is 29 or more, the melting point is high and the product tends to be solid. Therefore, the difficulty that it is difficult to use for practical use is included.

R ¹ is a hydrocarbon group, and the carbon number (X) of the hydrocarbon group is 1 to 27, has a low traction coefficient, and also from the viewpoint of realizing a lubricating oil composition with a high flash point. As shown, it is preferably 6-20, more preferably 7-18, and most preferably 7-17.

R ² is a hydrocarbon group having 1 to 27 carbon atoms, and preferably 1 to 20, more preferably 1 to 12, and most preferably 1 to 8 from the viewpoint of realizing a low traction coefficient and a high flash point. It is.

The hydrocarbon group for R ¹ and R ² is preferably an aliphatic hydrocarbon group, and may be either linear or branched. Further, it may be either a saturated or unsaturated hydrocarbon group, but it is more preferable that at least one of R ¹ and R ² is a saturated and branched aliphatic hydrocarbon group.

Therefore, in the general formula (1), the monoester having a total carbon number (X + Y) of R ¹ and R ² of 13 to 28 is an aliphatic hydrocarbon group having ¹ to 27 carbon atoms, and R ² is When it is a C1-C27 fatty acid hydrocarbon group, it can synthesize | combine by selecting from the group of the fatty acid and aliphatic alcohol of the following description, and combining.

Fatty acids include ethanoic acid (acetic acid), propanoic acid (propionic acid), butanoic acid (butyric acid), pentanoic acid (valeric acid), hexanoic acid (caproic acid), heptanoic acid (enanthic acid), octanoic acid (caprylic acid) ), Nonanoic acid (pelargonic acid), decanoic acid (capric acid), undecanoic acid (undecylic acid), dodecanoic acid (lauric acid), tridecanoic acid (tridecylic acid), tetradecanoic acid (myristic acid), pentadecanoic acid (pentadecylic acid) , Hexadecanoic acid (palmitic acid), heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid), nonadecanoic acid (nonadecyl acid), icosanoic acid (arachidic acid), heicosanoic acid, docosanoic acid (behenic acid), tricosanoic acid, tetracosanoic acid Acid (lignoceric acid), pentacosanoic acid, hexacosanoic acid ( Carotene acid), heptacosanoic acid, octacosanoic acid (distal acid) include nonacosanoic acid, and these unsaturated acids and branched acids.

As an unsaturated acid, it can select from the group illustrated below, for example.

2-propenoic acid, 2-butenoic acid, 3-butenoic acid, 2-pentenoic acid, 3-pentenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3-hexenoic acid, 4-hexenoic acid, 5-hexenoic acid, 2-heptenoic acid, 5-heptenoic acid, 2-octenoic acid, 3-octenoic acid, 2-nonenoic acid, 3-nonenoic acid, 2-decenoic acid, 9-decenoic acid, (caproleic acid), 9-hendenoic acid, 2-dodecenoic acid, 2-tridecenoic acid, 4-tetradecenoic acid, 5-tetradecenoic acid, 9-tetradecenoic acid, 2-pentadecenoic acid, 2-hexadecenoic acid, 7-hexadecenoic acid, 9-hexadecenoic acid, 2-heptadecenoic acid, 6-octadecenoic acid (cis) (petroceric acid), 6-octadecenoic acid (trans) (petrocelaidic acid), 9-octadecenoic acid (cis) (oleic acid), 9-octadecenoic acid (trans) (elaidin) ), 11-octadecenoic acid, 9-icosenoic acid, 11-docosenoic acid, 15-tetracosenoic acid, 17-hexacosenoic acid and the corresponding branched unsaturated acids in these linear unsaturated acid.

Examples of the aliphatic alcohol include methanol, ethanol, propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol (caprylyl), 1-nonanol (nonyl), 1-decanol (capryl). ), 1-undecanol, 1-dodecanol (lauryl), 1-tridecanol, 1-tetradecanol (myristyl), 1-pentadecanol, 1-hexadecanol (cetyl), 1-heptadecanol, 1-octa Decanol (stearyl), 1-nonadecanol, 1-icosanol (arakinyl), 1-hen ethanol, 1-docosanol, 1-tricosanol, 1-tetracosanol, 1-pentacosanol, 1-hexacosanol, 1-heptacosanol 1-octacosanol, - nonacosanol and the like, and these unsaturated alcohols and their branched alcohols.

Monoesters suitable as component A include R ¹ fatty acids having 6 to 17 carbon atoms and R ² aliphatic alcohols having 1 to 8 carbon atoms selected from the esters of the above fatty acids and aliphatic alcohols. A monoester composed of a combination, specifically, the following can be shown.

Methyl oleate, ethyl oleate, propyl oleate, butyl oleate, pentyl oleate, hexyl oleate, heptyl oleate, octyl oleate, octyl caprylate, octyl pelargonate, octyl caprate, butyl laurate, lauric acid Mention may be made of octyl, propyl myristate, octyl myristate, butyl palmitate, octyl palmitate, butyl stearate, octyl stearate and those in which one or both of R ¹ and R ² are branched.

Examples of particularly suitable monoesters for the lubricating oil composition according to the present invention include the following.
Caprylic acid, 2-ethylhexyl _{(C 7) COO (C 8} ) (X + Y = 15)
2-ethylhexyl pelargonate (C ₈ ) COO (C ₈ ) (X + Y = 16)
2-ethylhexyl caprate (C ₉ ) COO (C ₈ ) (X + Y = 17)
2-ethylhexyl laurate (C ₁₁ ) COO (C ₈ ) (X + Y = 19)
2-ethylhexyl myristate (C ₁₃ ) COO (C ₈ ) (X + Y = 21)
Isopropyl myristate (C ₁₃ ) COO (C ₃ ) (X + Y = 16)
2-ethylhexyl palmitate (C ₁₅ ) COO (C ₈ ) (X + Y = 23)
Methyl oleate (C ₁₇ ) COO (C ₁ ) (X + Y = 18)
Isobutyl oleate (C ₁₇ ) COO (C ₄ ) (X + Y = 21)
Stearate n- butyl _{(C 17) COO (C 4} ) (X + Y = 21)
Stearic acid 2-ethylhexyl _{(C 17) COO (C 8} ) (X + Y = 25)

The most preferred monoester has a total carbon number of 15 to 25, and specific examples include myristate-ethylhexyl, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, and isobutyl oleate.

The monoester can also be used as a mixture of two or more. When two or more esters are used as a mixture, R ¹ and R in the general formula (1) are used in the description of the lubricating oil composition. The number of carbons of ² shall mean each average value.

The blending amount of component A in the lubricating oil composition according to the present invention is 1 to 99%, preferably 5 to 95%, more preferably 15 to 1, with the total content of component A and component B being 1. 95%.

2. Component B-Hydrocarbon Synthetic Oil As the hydrocarbon synthetic oil that is a component of the base oil of the lubricating oil composition according to the present invention, the following hydrocarbon polymers and hydrocarbon copolymers are included. You can choose. Such polymers and copolymers include a wide range from low viscosity to high viscosity as described later, and oligomers and co-oligomers can also be selected.
(1) polyalphaolefin (PAO);
Examples of the polyalphaolefin that is a specific example of the hydrocarbon-based synthetic oil include poly (1-hexene), poly (1-octene), poly (1-decene), and the like, and mixtures thereof. Specific examples include a homopolymer of a C6-C12 alpha olefin such as 1-hexene, 1-octene and 1-decene, or a copolymer of mixed monomers, and a kinematic viscosity at 100 ° C. 20 to 2000 mm ² / s, particularly 20 to 1000 mm ² / s can be used. Incidentally, olefin monomers such polyalphaolefins, here is not limited to those described generally those alpha olefins C ₄ -C ₁₀ and alone or mixed is used as a polymerization raw material.

(2) Ethylene-alpha olefin copolymer (EAO)
Examples of the ethylene-alpha olefin copolymer include a copolymer of ethylene and an alpha olefin having 3 to 20 carbon atoms, specifically, ethylene and propylene, 1-butene, 1-hexene, 1-octene, 1 -A liquid copolymer with 1 type, or 2 or more types of mixtures of alpha olefins, such as a decene, can be mentioned.

As a liquid copolymer of ethylene and alpha olefin, 100 ° C. kinematic viscosity provided on the market is 10 mm ² / s, 20 mm ² / s, 40 mm ² / s, 100 mm ² / s, 150 mm ² / s, 600 mm ^2. Viscosity grades such as / s and 2000 mm ² / s can be selected and used. Such a liquid polymer preferably has a number average molecular weight (Mn) of 650 to 3600.

In the present invention, the hydrocarbon-based synthetic oil has a kinematic viscosity at 100 ° C. of 20 to 3000 mm ² / s, preferably 25 to 2500 mm ² / s, and more preferably 40 to 2000 mm ² / s. When the kinematic viscosity at 100 ° C. does not reach 20 mm ² / s or exceeds 3000 mm ² / s, the traction coefficient of the lubricating oil composition containing this as a constituent component exceeds 0.023. Can't offer things.

The blending amount of Component B is 99 to 1%, preferably 95 to 5%, and more preferably 85 to 5%, where the total content of Component A and Component B is 1.

3. Additives for lubricating oils The lubricating oil composition according to the present invention includes an antioxidant, a metal detergent, an ashless dispersant, a fluid, depending on the application, depending on the required performance, as long as the object of the present invention is not impaired. At least one additive for lubricating oil selected from the group consisting of point depressants, viscosity index improvers, extreme pressure agents, antiwear agents, oiliness agents, antifoaming agents, rust inhibitors, metal deactivators, etc. Can be blended.

In particular,
As the antioxidant, amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, 2,6-di-t-butylphenol, 4,4′-methylenebis (2 , 6-di-t-butylphenol), isooctyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like, and dilauryl-3,3′-thiodipropionate. Sulfur-based antioxidants such as phosphites, molybdenum-based antioxidants, molybdenum-based antioxidants, and zinc dithiophosphate, among others, amine-based antioxidants, phenol-based antioxidants, and combinations thereof Is preferably used. These are usually used at a ratio of 0.04 to 1% by weight.

As the metal detergent, alkaline earth metal sulfonate, alkaline earth metal salicylate, alkaline earth metal phenate or a mixture thereof is used. Alkaline earth metal sulfonates are alkaline earth metal salts of sulfonic acids such as long chain alkylbenzenes and alkylnaphthalenes.

Alkaline earth metal salicylates are alkaline earth metal salts of alkyl salicylic acid or sulfurized alkyl salicylic acid.
The alkaline earth metal phenate is an alkaline earth metal salt of alkylphenol or sulfurized alkylphenol.
Examples of alkaline earth metals of the sulfonate, salicylate and phenate include calcium, magnesium, barium and the like. These alkaline earth metal salts may be neutral salts, basic salts, or overbased salts.

Examples of the ashless dispersant include additives containing succinimide, succinic acid amide, benzylamine, succinic acid ester, succinic acid ester-amide, and the like, but a succinimide type is preferably used.
The metal detergent and ashless dispersant are used in a proportion of 0.2 to 10% by weight as a total amount.

Pour point depressants generally include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene, etc. Methacrylate is preferably used. These are usually used in a proportion of 0.02 to 5% by weight.

As the viscosity index improver, generally, polymethacrylate, dispersed polymethacrylate, olefin copolymer (polyisobutylene, ethylene-propylene copolymer), dispersed olefin copolymer, polyalkylstyrene, styrene-butadiene hydrogenated copolymer, Styrene-maleic anhydride ester copolymers, star-shaped isoprene and the like can be mentioned, and olefin copolymers (polyisobutylene, ethylene-propylene copolymers) are preferably used. In particular, the molecular weight of polyisobutylene or ethylene-propylene copolymer is particularly preferably those having a weight average molecular weight of 100,000 or more (polystyrene equivalent in GPC analysis). The dispersed olefin copolymer contains oxygen or nitrogen in the molecule. These are usually used in a proportion of 0.01 to 30% by weight.

Examples of extreme pressure agents generally include ashless sulfide compounds, sulfurized fats and oils, phosphate esters, phosphite esters, phosphate ester amine salts, and the like.

In particular, since a load bearing capacity is required for a lubricating oil composition used for lubricating a gear mechanism, a sulfur-based additive such as a hydrocarbon sulfide compound is used.

As an antiwear agent, zinc dithiophosphate, metal dithiophosphate (Sb, Mo, etc.), metal salt of dithiocarbamate (Zn, Sb, Mo, etc.), metal naphthenate, metal salt of fatty acid, boron compound, phosphate ester Phosphites, phosphate amine salts, phosphate metal salts, phosphate metal salts, phosphite metal salts and the like. Particularly preferred is zinc dialkyldithiophosphate. The extreme pressure agent and the antiwear agent are used in a proportion of 1 to 15% by weight.

Examples of the antifoaming agent include dimethylpolysiloxane and polyacrylate, and are usually added in a very small amount, for example, about 5 to 100 ppm.

Examples of the rust preventive include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers, and the like. Used in a proportion of 0.05 to 1% by weight.

Examples of the metal deactivator include benzotriazole, triazole derivatives, benzotriazole derivatives, thiadiazole, thiadiazole derivatives and the like, and these are used in a ratio of 0.02 to 1% by weight.

The total amount of the additive is adjusted to 50% or less, preferably 30 % or less, more preferably 20% or less, based on the total weight of the lubricating oil composition.

Moreover, the additive package which combined the various additives can also be used for the above additives.

4). Lubricating Oil Composition The lubricating oil composition according to the present invention comprises the component A and the component B, and comprises at least one lubricating oil additive blended as necessary. As the additive, an additive package configured according to the use of the lubricating oil can be used.

The flash point of the lubricating oil composition is 170 ° C. or higher, preferably 175 ° C. or higher.
The traction coefficient is 0.023 or less, preferably 0.022 or less. More preferably, it is 0.020 or less. If the traction coefficient exceeds 0.023, the resistance of gears and bearings increases, resulting in a problem that energy loss increases and fuel consumption decreases, and environmentally friendly lubricating oil cannot be provided.

Since the lubricating oil composition according to the present invention has low traction and high flash point characteristics, it can be used in automobile gear mechanisms such as manual transmission (manual transmission, MT), final reduction gear (differential, differential), and transmission. It can be used for manual transaxles (Manual Transaxle, MTX), etc., which integrates a diff and a differential, and energy loss can be reduced even in the case of lubrication with heavy loads on the MT helical gear and the differential hypoid gear.

The range of kinematic viscosity (KV value (40)) at 40 ° C. is 13 to ²⁰⁰ mm ² / s, preferably 15 to 90 mm ² / s. If the kinematic viscosity is lower than 13 mm ² / s, the oil film may be broken, so that the lubricating oil composition cannot be put to practical use.

5. Method for reducing traction coefficient The method for reducing the traction coefficient of the lubricating oil composition according to the present invention comprises mixing an effective amount of the monoester into a lubricating oil composition comprising a polyalphaolefin or an ethylene-alphaolefin copolymer. It will be.
The polyalphaolefin or ethylene-alphaolefin copolymer has a kinematic viscosity at 100 ° C. in the range of ²⁰ to 3000 mm ² / s, preferably 20 to 2000 mm ² / s, more preferably 40 to 2000 mm ² / s. belongs to.

Although the traction coefficient of such a hydrocarbon-based synthetic oil exceeds 0.023, the traction coefficient can be reduced to 0.023 or less without reducing the flash point to less than 170 ° C. by mixing the monoester. it can.
The monoester used in the method for reducing the traction coefficient of the lubricating oil composition has a total carbon number (X + Y) of 13 to 28. The effective amount in the mixing of the monoester is 1 to 99% by weight, preferably 5 to 95% by weight, more preferably 15 to 95% by weight.

In the method for reducing the traction coefficient in the present invention, a monoester having a total carbon number (X + Y) of 14 to 25, more preferably 18 to 25, is mixed with a hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 100 to 150 mm ² / s. Is particularly preferable in that the traction coefficient of the lubricating oil composition is lower than that of each of the hydrocarbon-based synthetic oil and the monoester.

Next, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples.
In addition, the traction coefficient and the flash point were measured by the methods described below as the lubricating base oils, additives, lubricating oil compositions used in Examples and Comparative Examples, and their viscosity properties and performance evaluation.

In Examples and Comparative Examples, “%” indicates wt%.
1. Lubricating base oil (1) Component A-monoester

(3) Component C-diester, etc.

2. Additives Commercial Additive Package for Gear Oil (1) Commercial Additive Package for MT Oil D ₁
(2) Additive package for commercial differential oil D ₂

3. Evaluation Method (1) Method for Measuring Maximum Traction Coefficient The measurement was performed under the following conditions using a four-cylinder traction tester.

Peripheral speed: 3.1m / sec
Average Hertz pressure: 0.7 GPa
Oil temperature: 40 ° C
(2) Flash point ASTM D92 compliant

Example 1
As component A (hereinafter referred to as “monoester”), 49.2% isopropyl myristate A ₁ having a total carbon number (X + Y) = 16 shown in Table 1 and component B (hereinafter referred to as “hydrocarbon synthetic oil”) A trial oil of 50.8% of the selected polyalphaolefin B ₂ shown in Table 2 was prepared.

The 40 ° C. kinematic viscosity of each trial oil was 26.7 mm ² / s, and a satisfactory result was obtained: traction coefficient: 0.022, flash point: 172 ° C.

Example 2
As in Example 1, isopropyl myristate A ₁ having a total carbon number (X + Y) = 16 was used, and ethylene-alpha olefin co-oligomer B ₁₀ was used instead of polyalphaolefin B ₂ used in Example 1. Trial oils were prepared at the ratios shown in Table 4.

Table 4 shows the viscosity properties and evaluation results of the prototype oil.

Examples 3-5
As monoester, X + Y = 16 isopropyl myristate A ₁ and as hydrocarbon-based synthetic oil mixed with selected polyalphaolefin B ₂ , polyalphaolefin B ₃ , ethylene-alphaolefin co-oligomer B ₁₀ respectively, blended additive package D _1, to prepare sample oils in the proportions shown in Table 4.

The viscosity properties and performance evaluation results of each trial oil are shown in the same table.

Examples 6-9
Methyl oleate A ₂ with X + Y = 18 is used as the monoester, and polyalphaolefin B ₂ , polyalphaolefin B ₄ , polyalphaolefin B ₆ , ethylene-polyalphaolefin co-oligomer B as the hydrocarbon-based synthetic oil Each of ₁₀ was used to prepare trial oils in the proportions shown in Table 4.

The viscosity properties and performance evaluation results of each trial oil are shown in the same table.

Examples 10-18
As monoester, X + Y = 18 methyl oleate A ₂ in the proportions shown in Table 4, and as hydrocarbon-based synthetic oil, selected polyalphaolefin B ₂ , polyalphaolefin B ₃ , polyalphaolefin B ₄ , poly After mixing with alpha olefin B ₅ , polyalpha olefin B ₆ , ethylene-alpha olefin co-oligomer B ₇ , and ethylene-alpha olefin co-oligomer B ₁₀ , additive package D ₁ was blended to prepare a trial oil.

In Example 14, additive package D ₂ was used instead of additive package D ₁ .
Example 19
After mixing n-butyl stearate A ₃ of X + Y = 21 as a monoester and a selected polyalphaolefin B ₃ as a hydrocarbon-based synthetic oil in the ratio shown in Table 4, the additive package D ₁ Was added to prepare a trial oil.

The viscosity properties and performance evaluation results of the prototype oil are shown in the same table.

Example 20
As monoester, X + Y = 21 isobutyl oleate A ₄ is mixed with the selected polyalphaolefin B ₃ as a hydrocarbon-based synthetic oil in the ratio shown in Table 4, and then added to the additive package D ₁ Then, a trial oil was prepared.

The viscosity properties and performance evaluation results of the prototype oil are shown in the same table.

Example 21
As monoester, stearic acid 2-ethylhexyl A ₅ of X + Y = 23, in the proportions shown in Table 4, were mixed with polyalphaolefins B ₃ selected as the hydrocarbon-based synthetic oil, blended additive package D ₁ A prototype oil was prepared.

The viscosity properties and performance evaluation results of the prototype oil are shown in the same table.

Examples 22-23
As monoester, X + Y = 25 2-ethylhexyl stearate A ₆ is mixed with selected polyalphaolefin B ₂ and ethylene-alphaolefin co-oligomer B ₁₀ as hydrocarbon-based synthetic oil in the proportions shown in Table 4, respectively. Then, a trial oil was prepared.

The viscosity properties and performance evaluation results of each trial oil are shown in the same table.

Examples 24-26
As monoester, the X + Y = 25 2-ethylhexyl A ₆ stearate, in the proportions shown in Table 1, the hydrocarbon-based synthetic oils, polyalphaolefins B ₂ selected, polyalphaolefins B _3, ethylene - alpha olefin copolymers After mixing with oligomer B ₁₀ respectively, additive package D ₁ was blended to prepare a trial oil.

The viscosity properties and performance evaluation results of each trial oil are shown in the same table.

Comparative Example 1
As a monoester, a trial oil consisting only of 2-ethylhexyl palmitate A _{5 with} X + Y = 23 was prepared. When the prototype oil was subjected to measurement of viscosity properties and performance evaluation, the results shown in Table 5 were obtained.

Comparative Example 2
Sample oils comprising only polyalphaolefin B ₃ selected as the hydrocarbon-based synthetic oil was prepared. When the prototype oil was subjected to measurement of viscosity properties and performance evaluation, the results shown in Table 5 were obtained.

Only the monoester of Comparative Example 1 and the polyalphaolefin of Comparative Example 2 had a high traction coefficient and deviated from the scope of the present invention.
Further, the 40 ° C. kinematic viscosity was remarkably large or remarkably small.

Comparative Example 3
As a monoester, isopropyl myristate A ₁ of X + Y = 16 was mixed with polyalphaolefin B ₁ selected as the hydrocarbon-based synthetic oil in the ratio shown in Table 5 to prepare a trial oil.

Table 5 shows the viscosity properties and performance evaluation results of the prototype oil. Even if X + Y of the monoester is within the range of the present invention, it is shown that the performance of the trial oil is remarkably lowered when the hydrocarbon synthetic oil departs from the range of the present invention.

Comparative Example 4
As monoesters, X + Y = 12 methyl laurate A ₇ and polyalphaolefin B ₄ selected as the hydrocarbon-based synthetic oil were used to prepare trial oils in the proportions shown in Table 5.

  Table 5 shows the viscosity properties and performance evaluation results of the prototype oil. According to Table 5, although a 40 degreeC kinematic viscosity fall of trial oil was not seen, although the traction coefficient fell, the flash point also fell.

Comparative Examples 5-10
Polyalphaolefin B ₁ , Polyalphaolefin B ₂ , Polyalphaolefin B ₃ , Polyalphaolefin B ₄ , Polyalphaolefin selected from methyl laurate A ₇ of X + Y = 12 as the monoester as the hydrocarbon-based synthetic oil After mixing with B ₅ and polyalphaolefin B _{6 in the} proportions shown in Table 5, additive package D ₁ was blended to prepare a trial oil.

The viscosity properties and performance evaluation results of each trial oil are shown in the same table.

Comparative Example 11
As monoester, blended additive package D ₁ to X + Y = 25 Stearic acid 2-ethylhexyl A _6, to prepare a sample oils.

Table 5 shows the viscosity properties and performance evaluation results of the prototype oil.
Monoester alone has a high traction coefficient and deviates from the scope of the present invention. However, as described later, the mixing effect by mixing with a hydrocarbon-based synthetic oil is remarkable, and is useful as a mixing component.

Comparative Example 12
After mixing 2-ethylhexyl stearate A ₆ (X + Y = 25) with polyalphaolefin B _{1 in the} ratio shown in Table 5, additive package D ₁ was blended to prepare a trial oil.

Table 5 shows the viscosity properties and performance evaluation results of the prototype oil.

Comparative Example 13
As shown in Table 5, it was selected to polyalphaolefin B ₁ by blending the additive package D ₁ to prepare sample oils as hydrocarbon-based synthetic oil.

The viscosity properties and performance evaluation results of the prototype oil are shown in the same table.

Comparative Example 14
As monoester, X-Y = 29 stearic acid n-dosider A ₈ was mixed with polyalphaolefin B ₃ selected as the hydrocarbon-based synthetic oil in the proportions shown in Table 5, and then additive package D ₁ was blended. However, stearic acid n-dosider A ₈ was in a solid state at X + Y = 29 and separated, and could not be used as a lubricating oil.

Comparative Examples 15-16
As shown in Table 5, the three components (Comparative Example 15) of the monoester of Component A, the hydrocarbon synthetic oil of Component B and the polyalphaolefin of 100 ° C. kinematic viscosity of 2 mm ² / s or of Component A a mixed oil of two-component (Comparative example 16) and polyalphaolefins of 100 ° C. kinematic viscosity 2 mm ² / s of the monoester and component C, and the sample oils was blended each additive package D ₁ was prepared.

Comparative Example 17
As shown in Table 5, the mixed oil of the polyalphaolefin B ₂ and diisodecyl adipate C _2, to prepare sample oils was blended additive package D _1.

The viscosity properties and performance evaluation results of the prototype oil are shown in the same table.

As a result of the performance evaluation of the trial oils obtained in Comparative Examples 15 to 17, the ternary system containing the low-viscosity polyalphaolefin has a low flash point, and the monoester and the low-viscosity polyalphaolefin Thus, it was found that the kinematic viscosity at 40 ° C. was lowered and the function as a lubricating oil targeted by the present invention was lacking.

  Furthermore, diesters have been shown to significantly increase the traction coefficient.

    From these results, a lubricating oil composition prepared by using a monoester as component A and a hydrocarbon-based synthetic oil composed of polyalphaolefin or ethylene-alphaolefin as component B has a traction coefficient of 0.023 or less and a flash point of 170. Observing at or above ° C. as a performance criterion revealed the following facts and revealed the specificity of the present invention.

1. Low traction by combining monoesters with a total carbon number (X + Y) in the range of 13-28 with polyalphaolefins or ethylene-alphaolefin co-oligomers with a 100 ° C. kinematic viscosity in the range of 20-2000 mm ² / s A lubricating oil composition having a coefficient and a high flash point can be provided (Examples 1 to 26).

2. Mixed oil obtained by mixing ^two monoesters having a total carbon number (X + Y) in the range of 13 to 28 of 21 and 25 with a polyalphaolefin having a kinematic viscosity at 100 ° C. of 100 mm ² / s, respectively. The following result was shown that the traction coefficient of was lower than the traction coefficient of either the monoester or the polyalphaolefin constituting the mixed oil.

Traction coefficient flash point (℃) KV40 (mm ² / s)
Comparative Example 11; 2-ethylhexyl stearate A ₆ 0.024 226 12.2
Comparative Example 2; Polyalphaolefin B ₃ 0.025 296 1292
Example _{25 A 6 / B 3 0.020 230} 28.0

Comparative Example 1; 2-ethylhexyl palmitate A ₅ 0.027 211 8.4
Comparative Example 2: Polyalphaolefin B ₃ 0.025 296 1292
Example _{21 A 5 / B 3 0.021 216} 27.7

3. Even when the total carbon number (X + Y) is a monoester in the range of 13 to 28, when combined with a polyalphaolefin having a kinematic viscosity at 100 ° C. of less than 20 mm ² / s, the traction coefficient hardly decreases, Moreover, even if it reduced, the result that a synergistic effect was not seen was obtained (comparative examples 11-13).

For example, a mixed oil of a monoester having a total carbon number (X + Y = 25) and a polyalphaolefin having a kinematic viscosity of 6 mm ² / s at 100 ° C. does not provide a mixing effect in reducing the traction coefficient as shown below. It was.

Traction coefficient flash point (℃) KV40 (mm ² / s)
Comparative Example 11; 2-ethylhexyl stearate A ₆ 0.024 226 12.2
Comparative Example 13: Polyalphaolefin B ₁ 0.027 244 34.6
Comparative Example 12 A ₆ / B ₁ 0.025 256 27.5

4). The monoester whose total carbon number (X + Y) does not reach 13 cannot satisfy both or either of the traction coefficient and the flash point regardless of the viscosity of the hydrocarbon-based synthetic oil (Comparative Examples 4 to 10). ).

5. When a diester typified by DIDA is used and mixed with a polyalphaolefin, unlike the case where a monoester is used, there is no mixing effect as shown in the above item 2, and the mixed oil with the polyalphaolefin is a traction The coefficient was remarkably high, and the low traction / high flash point lubricating oil composition intended by the present invention could not be realized. (Comparative Example 17). From these results, it became clear that specific monoesters have specificity.

Claims (6)

A lubricating oil composition containing the following component A and component B,
The component A is represented by the following general formula (1):

(In the formula, R ¹ and R ² are each a hydrocarbon group, which may be the same or different from each other, and the total number of carbon atoms of R ¹ and R ² is 13 to 28.)
At least one monoester represented by:
Component B is at least one hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of ²⁰ to 3000 mm ² / s,
Based on the total weight of the total content of component A and component B,
The content of the component A is 1 to 99% by weight, the content of the component B is 99 to 1% by weight,
A lubricating oil composition, wherein a flash point of the lubricating oil composition is controlled to 170 ° C or higher. In the general formula (1) of the component A, R ¹ and R ² are each an aliphatic hydrocarbon group, the total number of carbon atoms of R ¹ and R ² is 13 to 28, and the carbon number of R ² is The lubricating oil composition according to claim 1, which is 1 to 27. The lubricating oil composition according to claim 2, wherein in the general formula (1) of the component A, the total number of carbon atoms of R ¹ and R ² is 13 to 28, and the carbon number of R ² is 1 to 12. .   Furthermore, the component mix | blended is an at least 1 type of additive, The lubricating oil composition of Claim 1. General formula (1) for a lubricating oil composition comprising a hydrocarbon-based synthetic oil having a kinematic viscosity at 100 ° C. of 20 to 3000 mm ² / s and a flash point of 170 ° C. or higher;
(In the formula, R ¹ and R ² are each a hydrocarbon group, which may be the same or different from each other, and the total number of carbon atoms of R ¹ and R ² is 13 to 28.)
The traction coefficient of a lubricating oil composition comprising a hydrocarbon-based synthetic oil, characterized in that at least one monoester represented by the formula is mixed in an effective amount range for reducing the traction coefficient of the lubricating oil composition. Reduction method. A lubricating method for a gear mechanism, wherein the lubricating oil composition according to any one of claims 1 to 4 is used for lubricating an automobile gear or an industrial gear.