KR102151399B1 - composition of lubricant for automatic transmission - Google Patents

Abstract

The present invention relates to a lubricating oil composition for an automatic transmission comprising 75 to 90% by weight of at least one mineral oil, 1 to 10% by weight of aliphatic diester and 5 to 20% by weight of additives. The lubricating oil composition for an automatic transmission according to the present invention has a feature of low low temperature viscosity, thereby improving low temperature fluidity, and improving low friction characteristics by using mineral oil with a high amount of paraffinic hydrocarbons in the mineral oil. effective. In addition, it has a feature of high viscosity at high temperatures, which prevents abrasion of parts inside the automatic transmission, thereby enhancing durability.

Description

Composition of lubricant for automatic transmission

The present invention relates to a lubricating oil composition for an automatic transmission, in particular, including 75 to 90% by weight of one or more mineral oils, 1 to 10% by weight of aliphatic diester, and 5 to 20% by weight of additives, and has low low temperature viscosity and improves fuel economy It relates to a lubricant composition for automatic transmission that can be.

Recently, as environmental problems such as reduction of carbon dioxide emission have emerged, energy savings in automobiles, that is, reduction of fuel economy, has become an urgent priority. Engines and automatic transmissions are strongly required to contribute to energy savings. Therefore, the lubricating oil used for these has previously been required to reduce agitation resistance and frictional resistance.

One of the means for reducing fuel consumption of an automatic transmission is to reduce the viscosity of the lubricant at low temperatures. For example, an automatic transmission for an automobile has a torque converter, a wet clutch, a gear bearing mechanism, an oil pump, and a hydraulic control mechanism, and by reducing the viscosity of the lubricating oil used for them at a lower temperature, the agitation resistance and friction resistance are reduced. By improving the power transmission efficiency, it becomes possible to improve the fuel efficiency of the vehicle.

However, when the lubricating oil used for these is reduced in viscosity, the fatigue life is significantly reduced, and resistance to friction decreases, which may cause problems in the transmission. In particular, it is generally difficult to reduce the viscosity because the fatigue life is remarkably deteriorated when phosphorus-based extreme pressure additives are incorporated in order to improve the extreme pressure properties of the low viscosity oil. In addition, the sulfur-based extreme pressure agent can improve the fatigue life of the lubricating oil, the oxidation stability is deteriorated, and a large amount of the antioxidant is required.

Conventional transmission oils for automobiles are capable of maintaining various performances such as transmission characteristics for a long time.For example, synthetic oils and/or mineral oil based lubricating base oils, abrasion inhibitors, extreme pressure agents, metal cleaners, ashless dispersants, friction modifiers, viscosity index It has been reported that the blending agent is optimized and formulated. However, since none of these compositions are intended to improve fuel economy, their kinematic viscosity is high, and the effect on the fatigue life when the lubricating oil is made low in viscosity has not been studied at all.

In addition, there has been proposed an automatic transmission oil with a low viscosity of a lubricant in existing documents (see Japanese Patent Laid-Open No. 2004-169025, Japanese Patent Laid-Open No. 2004-155924, and Japanese Patent Laid-Open No. 2004-155873). However, these lubricants have excellent shudder-resistant maintenance performance, low-temperature viscosity characteristics, and oxidation stability, but there is still room for improvement in order to obtain what satisfies both durability of friction characteristics, fuel economy reduction, and wear prevention performance.

Japanese Patent Publication 2004-155924 (June 17, 2004) Japanese Patent Publication 2004-155924 (June 03, 2004) Japanese Patent Publication 2004-155873 (June 03, 2004)

As a result of repeating research to solve the existing problems, the present inventors have low low-temperature viscosity and improve fuel economy, including 75 to 90% by weight of one or more mineral oils, 1 to 10% by weight of aliphatic diester, and 5 to 20% by weight of additives. It is an object of the present invention to provide an improved lubricating oil composition for an automatic transmission.

The present invention relates to a lubricating oil composition for an automatic transmission. More specifically, the present invention comprises 75 to 90% by weight of one or more mineral oils, 1 to 10% by weight of aliphatic diester and 5 to 20% by weight of additives, and the mineral oil has a kinematic viscosity at 100°C of 3 cSt or more, and paraffin It relates to a lubricating oil composition for an automatic transmission comprising 70 to 90% by weight of hydrocarbon-based and 10 to 30% by weight of naphthenic hydrocarbon.

Another aspect of the present invention relates to a lubricating oil composition for an automatic transmission in which the lubricating oil composition has a ccs low temperature viscosity at -30°C of 1,800 to 2,300 cP, and a BP low temperature viscosity at -40°C of 6,000 to 8,500 cP.

The embodiments described above are not limited to the contents described, and include all items that can be easily changed by a business operator in the same field. As an example, there may be cases where different types of devices are used for the purpose of implementing the same technology.

The lubricating oil composition for an automatic transmission according to the present invention has a feature of low low temperature viscosity, thereby improving low temperature fluidity, and improving low friction characteristics by using mineral oil with a high amount of paraffinic hydrocarbons in the mineral oil. effective. In addition, it has a feature of high viscosity at high temperatures, which prevents abrasion of parts inside the automatic transmission, thereby enhancing durability.

1 to 4 show the dynamic friction coefficient according to the temperature of the compositions prepared through Examples 1 and 2 and Comparative Examples 1 to 3 of the present invention.

Hereinafter, a lubricating oil composition for an automatic transmission according to the present invention will be described in detail with reference to specific examples. Specific examples introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention is not limited to the specific examples presented below and may be embodied in other forms.

The terms used in the present specification are only used to describe specific embodiments (sun, 態樣, aspect) (or examples), and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "may include" or "may consist of" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification. It is to be understood that it does not preclude the possibility of the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof.

In addition, if there is no other definition in the technical terms and scientific terms used in the specific examples, they have the meanings commonly understood by those of ordinary skill in the technical field to which this invention belongs, and the gist of the present invention is unnecessary in the following specific examples. Descriptions of known functions and configurations that may be blurred will be omitted.

The lubricating oil composition for an automatic transmission according to the present invention may include 75 to 90% by weight of one or more mineral oils, 1 to 10% by weight of aliphatic diester, and 5 to 20% by weight of additives.

In general, the most important function in lubricating oil for an automatic transmission is lubrication, which is aimed at reducing friction. The automatic transmission is assembled with many parts, and each part is filled with a film of oil to each other, and without this film, the parts will suffer severe wear. Therefore, lubricants need the ability to maintain a strong oil film of sufficient thickness between parts. The lubricating oil composition for an automatic transmission according to the present invention maintains a low viscosity even at a low temperature by appropriately adjusting the amount and viscosity of mineral oil, aliphatic diester and additives, and thereby has a strong oil film formation ability and an effect of reducing fuel economy. to be.

The mineral oil according to the present invention generally refers to those suitable for use as lubricating oil among petroleum oil products, and specifically, polymerized polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, Olefins such as poly(1-octene) and poly(1-decene); Alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes, dinoulbenzenes, di-(2-ethylhexylbenzenes, etc.), polyphenyls (e.g. biphenyls, terphenyls, alkylated polyphenyls) Etc.), alkylated diphenyls, ethers, alkylated diphenyl sulfides, and derivatives thereof; various alcohol groups (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene group) Recall diethylene glycol monoether, porophylene glycol, etc.) and carboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acid and alkenyl succinic acid maleic acid, azeraic acid, suberic acid, sebacic acid, fumaric acid, adip) Ester compounds of acids, alkenyl malonic acids, etc.); consisting of one or a mixture of polyalkyl-, polyaryl-, polyalcohol- or polyaryloxy-siloxane oils and silicate oils composed of a silicone base Can be used.

The mineral oil according to the present invention may comprise 70 to 90% by weight of paraffinic hydrocarbons and 10 to 30% by weight of naphthenic hydrocarbons. More preferably, it is preferable to contain 75 to 90% by weight of paraffinic hydrocarbons and 10 to 25% by weight of naphthenic hydrocarbons. In particular, the mineral oil according to the present invention is characterized in that the amount of paraffinic hydrocarbons is greater than that of mineral oils commonly used as lubricants in the art. When the amount of paraffinic hydrocarbons is less than 70 parts by weight, ccs low temperature viscosity increases, The effect of improving fuel economy may decrease.

In addition, the manufacturing method is not limited, and for example, the lubricating oil fraction obtained by atmospheric distillation and reduced pressure distillation of crude oil can be used for solvent deasphalation, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrogenation purification, sulfuric acid washing, clay treatment, etc. It can be prepared by performing purification alone or in combination of two or more appropriately. In addition, mineral oil may be used alone or in combination of two or more in any ratio.

The mineral oil according to the present invention may have a kinematic viscosity of 3 cSt or more at 100° C., more preferably, a kinematic viscosity of 4 to 7 cSt. The mineral oil according to the present invention satisfies the kinematic viscosity, so that even if the composition has a low low temperature viscosity, the fatigue life of the gear included in the automatic transmission may be prolonged, and the shudder prevention performance, oxidation stability, and friction characteristics may be increased.

In addition, the mineral oil according to the present invention may have a viscosity index of 130 or more, more preferably 130 to 150. If the viscosity index is less than 130, the viscosity change according to temperature is severe, and the effect on fatigue life may be reduced due to the occurrence of wax components.

The mineral oil according to the present invention is not particularly limited, but the sulfur content may be less than 1 ppm. When the sulfur content exceeds 1 ppm, the oxidation stability of the lubricant may be deteriorated, so it is preferable to contain less than 1 ppm.

When two or more types of mineral oils are used, a) a first mineral oil having a cold cranking simulator (ccs) low temperature viscosity of 2,000 cP or less at -30°C, and b) a ccs low temperature viscosity at -30°C. It may contain a second mineral oil of 4,000 cP or less. More specifically, the first mineral oil may have a ccs low temperature viscosity of 1,000 to 1,200 cP, and the second mineral oil may have a ccs low temperature viscosity of 3,500 to 4,000.

The ccs low temperature viscosity is a viscosity measured by ASTM using a measuring instrument called ccs (cold cranking simulator), and is closely related to the cranking speed and startability at low temperature. The lubricating oil composition according to the present invention may have a high film forming ability and excellent oil pumping performance even under low temperature by including two types of mineral oils having different ccs low temperature viscosity.

The lubricating oil composition according to the present invention may further include polyalphaolefins in one or more mineral oils in addition to containing two types of mineral oils having different ccs low temperature viscosity.

The polyalphaolefin according to the present invention has an effect of improving flowability inside an internal combustion engine at a high temperature, low volatility, excellent effect even at low temperatures, and increasing oxidation stability, hydrolysis stability, and oil film stability.

The polyalphaolefin according to the present invention is usually an oligomer or co-oligomer of an α-olefin having 2 to 32 carbon atoms, preferably 6 to 16, specifically 1-octene oligomer, 1-decene oligomer, ethylene- And propylene co-oligomers and hydrides thereof.

In the present invention, the method for producing the polyalphaolefin is not particularly limited, and examples thereof include aluminum trichloride, boron trifluoride; Polymerization of α-olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst containing a complex of boron trifluoride with an alcohol such as water ethanol, propanol, butanol, and an ester such as carboxylic acid or ethyl acetate or ethyl propionate. can do.

The polyalphaolefin according to the present invention preferably has a kinematic viscosity of 150 cSt or more at 100° C. and 1,500 cSt or more at 40° C. because of excellent low evaporation properties, coking resistance, and low fuel economy.

It is preferable that the polyalphaolefin according to the present invention contains 1 to 10 parts by weight, more preferably 2 to 5 parts by weight, based on 100 parts by weight of the total lubricating oil composition. If the polyalphaolefin is contained in less than 1 part by weight, the flowability of the entire lubricant may become busy and the lubricating characteristics may be deteriorated.If it is contained in more than 10 parts by weight, film stability or chemical resistance may increase, but the manufacturing cost increases. , There may be a problem of shrinking rubber sealing agents such as silicone or polyacrylate fluorocarbon contained inside the automatic transmission.

The aliphatic diester according to the present invention is added to improve the lubricating performance in the temperature range to which the lubricating oil composition is exposed, and when 1 mol of dihydric alcohol and 2 mol of monobasic acid are added, 2 mol of monohydric alcohol and 1 dibasic acid. As an ester to which mole is added, it may be a compound having an ester skeleton having 7 to 13 carbon atoms. Specifically, it is an aliphatic diester of a dicarboxylic acid, or dialkyl diesters of alkyl carboxylic acids such as di-2-ethylhexyl azerate, di-isodecyl adipate and di-tridecyl adipate can be used. have.

The aliphatic diester according to the present invention has a kinematic viscosity of 10 cSt or less at 40° C. and a kinematic viscosity of 4 cSt or less at 100° C. is excellent in miscibility with other compositions, and the lubricating property of the lubricating oil composition does not deteriorate even with temperature changes, so it is preferable. .

The aliphatic diester according to the present invention is preferably added in an amount of 1 to 10% by weight based on 100% by weight of the total lubricating oil composition. If less than 1% by weight is added, the desired lubricating properties may not appear in the present invention, and if it is more than 10% by weight, there may be a problem that the manufacturing cost of the composition increases.

The lubricating oil composition according to the present invention may contain any one or two or more selected from a detergent, a friction reducing agent, a sediment formation inhibitor, a corrosion inhibitor, an antioxidant, a rust inhibitor, an antiwear agent, an antifoam agent, a metal deactivator, an extreme pressure agent, and a dispersant. have.

The detergents according to the present invention are one or more overbased substances, which are also referred to as overbased or superbased salts, which are generally subject to the stoichiometry of metals and certain acidic organic compounds that react with the metals. Thus, it is a single-phase homogeneous Newtonian system characterized by an excess of metal content than can be present for neutralization. The overbased material is an acidic organic compound, a reaction medium containing at least one inert organic solvent (mineral oil, naphtha, toluene, xylene, etc.) for this acidic organic material, a stoichiometric excess of a metal base and a cocatalyst such as calcium chloride. , Acetic acid, phenol or alcohol, and an acidic substance (usually an inorganic acid or lower carboxylic acid, such as carbon dioxide). An acidic organic substance generally means having a sufficient number of carbon atoms to provide oil solubility.

In the present invention, the metal of the metal-containing detergent may be zinc, sodium, calcium, barium or magnesium, or a mixture thereof. In general, the metal of the metal-containing detergent may be sodium, calcium or magnesium, and in one embodiment is calcium.

An example of an overbased metal-containing detergent in the present invention may be selected from the group consisting of non-sulfur-containing phenates, sulfur-containing phenates, sulfonates, salixarates, salicylates and mixtures thereof, or borated equivalents thereof. I can. In one embodiment, the overbased detergent comprises calcium sulfonate having a metal ratio of 3.5 or higher. Sulfonate detergents, such as overbased calcium sulfonate detergents, are described in a number of publications including US Patent Application 2005-065045 and US Patent 5,037,565.

The friction reducing agent according to the present invention may include a fatty acid derivative, a fatty ester, or a derivative of a fatty epoxide having a linear carbon chain having 10 to 22 carbon atoms; Fatty imidazoline; Amine salts of alkylphosphoric acid; Fatty alkyl tartrate; Fatty alkyl tartrimide; Fatty alkyl tartamide; Fatty glycolate; And any one or two or more selected from fatty glyamides may be used.

Friction reducing agents that can be used in the present invention, for example, long chain fatty acid derivatives, fatty esters or fatty epoxides; Fatty imidazolines such as condensation products of carboxylic acids and polyalkylene-polyamines; Amine salts of alkylphosphoric acid; Fatty alkyl tartrate; Fatty alkyl tartrimide; Fatty alkyl tartamide; Fatty phosphonate; Fatty phosphite; Borated phospholipids, borated fatty epoxides; Glycerol ester; Borated glycerol esters; Fatty amines; Alkoxylated fatty amines; Borated alkoxylated fatty amines; Hydroxy and polyhydroxy fatty amines such as tertiary hydroxy fatty amines; Hydroxy alkyl amide; Metal salts of fatty acids; Metal salts of alkyl salicylate; Fatty oxazoline; Fatty ethoxylated alcohols; Condensation products of carboxylic acids and polyalkylene polyamines; Or a reaction product of a fatty carboxylic acid with guanidine, aminoguanidine, urea or thiourea, and salts thereof.

The sediment formation inhibitor according to the present invention has a structure of an oil soluble type surfactant, and thus serves to dissolve polar sediments attached to parts of an automatic transmission and disperse them into a lubricant. Such deposit formation inhibitors may include, for example, amides, polybuteksuccinimide, polyolefinamines, polyetheramines, and the like.

Corrosion inhibitors according to the present invention are used to reduce deterioration of metallic parts in contact with the lubricating oil composition, and suitable corrosion inhibitors may include thiadiazoles. As examples of such corrosion inhibitors, those described in US Patent Nos. 2,719,125, 2,719,126, and 3,087,932 can be used.

Antioxidants according to the present invention are intended to retard oxidative decomposition of the lubricating oil composition that may occur during use, which decomposition can create deposits on the metal surface or increase the viscosity of the lubricating oil composition. Suitable antioxidants may be phenolic or non-phenolic, examples of phenolic antioxidants include 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; 2-methyl-6-t-butyl-4-dodecyl phenol; 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; 2-methyl-6-t-butyl-4-dodecyl phenol; Any one or two or more selected from 4,4'-bis (2,6-di-t-butyl-phenol) and 4,4'-methylene-bis (2,6-di-t-butyl-phenol) Can include.

Examples of non-phenolic antioxidants include aromatic amines such as diphenylamine, phenyl naphthylamine, phenothiazine, imidodibenzyl, diphenyl phenylene diamine, p,p'-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; Phenyl-alphanaphthylamine; And p-octylphenyl-alpha-naphthylamine, or the like.

The rust inhibitor according to the present invention plays a role of preventing or removing rust of metallic parts in contact with the composition similar to the corrosion inhibitor. For example, in alkanolamines such as metal sulfonates, succinic acid esters, alkylamines and monoisopropanolamines. Any one or two or more selected may be used.

The antiwear agent according to the present invention is to prevent abrasion of metallic parts in contact with the lubricating oil composition, and phosphorus and sulfur compounds such as zinc dithiophosphate and/or sulfur, nitrogen, boron, molybdenum phosphorodithioate, molybdenum dithiocarba Various organomolybdenum including mate, including heterocyclic group (such as dimercaptothiadiazole, mercaptobenzothiadiazole, triazine, etc.), alicyclic group, amine, alcohol, ester, diol, triol, fatty amide, etc. Any one or two or more selected from derivatives may be used.

The antifoaming agent according to the present invention plays a role of delaying the formation of stable air bubbles, and polysiloxanes such as silicon oil, polysiloxane polysiloxane, and polydimethylsiloxane may be used.

The metal deactivator according to the present invention slows the oxidation rate of the composition by inhibiting the radical reaction catalytic action of metal salts that may be included in the lubricating oil composition, and any material that reacts with the metal surface to form an inactivation film can be used regardless of the type. Do. Examples of the metal inactive agent include derivatives of benzotriazole (generally tolyltriazole), 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole or 2-alkyldithiobenzothia Any one or two or more selected from sols and the like may be used.

The extreme pressure agent according to the present invention is to prevent the oil film from being destroyed on the lubrication surface under high load, and to prevent burning or abrasion, including chlorinated wax; Vulcanized olefins (e.g. vulcanized isobutylene), hydrocarbyl-substituted 2,5-mercapto-1,3,4-thiadiazole, or oligomers thereof, organic sulfides and polysulfides such as dibenzyldisulfide, bis -(Chlorobenzyl) disulfide, dibutyl tetrasulfide, vulcanized methyl ester of oleic acid, vulcanized alkylphenol, vulcanized dipentene, vulcanized terpene and vulcanized Diels-Elder adducts; Phosphorusulfated hydrocarbons such as terpentine or the reaction product of methyl oleate and phosphorus sulfide; Phosphorus esters such as bicarbonate phosphite and hydrogen tricarbonate phosphite, such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; Dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite; Metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptylphenol diacid; Amine salts or derivatives thereof of alkyl phosphoric acid and dialkyl phosphoric acid, such as dialkyldithiophosphoric acid, reacted with propylene oxide, and then further reacted with P2O5, amine salts of the reaction products, and the like.

The dispersant according to the present invention serves to prevent precipitation and deposition of oil-insoluble oxidation by-products that may occur during the operation of an automatic transmission, such as succinimide, succinate ester, succinate ester amide, alkylphenol-polyamine -Any one or two or more selected from the coupled Mannich add-ons can be used.

The additive composition according to the present invention may use any one of the materials described above, but a package including two or more materials may be used. The additive package that can be used in the present invention may use Afton's HiTEC series.

The additive composition according to the present invention may include 5 to 20% by weight, preferably 10 to 13% by weight, based on 100% by weight of the total lubricating oil composition. If the additive composition is added less than 5% by weight, it is difficult to properly express various effects of the additive, and if it is added in more than 20 parts by weight, the amount of base components such as mineral oil is relatively reduced, and the manufacturing cost is further increased. can do.

The lubricating oil composition according to the present invention may be prepared by mixing mineral oil, aliphatic diester, additives and/or polyalphaolefin together at a temperature of 40 to 60°C. At this time, mechanical stirring may be performed for uniform mixing, and a sufficient mixing time may be taken to ensure a uniform product. The lubricating oil composition according to the present invention is not limited to these production conditions, and can be freely changed within the range understood or practiced by a person skilled in the art.

The lubricating oil composition according to the present invention may be a multi-viscosity lubricating oil having a specific viscosity at low and high temperatures. More preferably, the ccs low temperature viscosity at -30°C is 1,800 to 2,300 cP, and the BP low temperature viscosity at -40°C may satisfy 6,000 to 8,500 cP. In addition, the lubricating oil composition according to the present invention may be used for an automatic transmission operating under conditions of lubrication, cooling and power transmission, and more particularly, it is characterized in that it satisfies the DEXRON standard of GM of the United States.

Hereinafter, the lubricating oil composition according to the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the Examples and Comparative Examples are only examples for describing the present invention in more detail, and the present invention is not limited thereto.

The specifications of the materials used in Examples and Comparative Examples of the present invention and physical properties of the prepared samples were measured as follows.

(Specification of material)

Specifications of the materials used in Examples and Comparative Examples are shown in Tables 1 to 3.

[Table 1]

[Table 2]

[Table 3]

(Kinematic viscosity)

Kinematic viscosity measurement was performed according to ASTM D 445 (Test Method for Kinematic Viscosity of Transparent and Opaque Liquids).

(ccs low temperature viscosity)

As a test method used to measure the viscosity when pumping engine oil at low temperatures, the viscosity was measured using a cold cranking simulator (ASTM D2602).

(Dynamic friction coefficient)

It was carried out using a Mini-Traction Machine manufactured by PCS Instruments. Specifically, it is composed of a steel bearing (SAE AISI 52100 steel) with a diameter of 19.05 mm forming an angle of 220° to a 46 mm diameter abrasive disk (SAE AISI 52100 steel), and the bearing is concentrically fixed on the motor drive shaft. , The polishing disc was fixed concentrically on the other motor drive shaft. Then, a sphere was loaded onto the disk to make point contact with minimal spin and skew parts. In addition, the sliding-to-rolling ratio (SRR) of 0 to 50% was maintained at the contact point, and the coefficients of dynamic friction were measured at a temperature of 60, 80, 100, and 120°C under a load of 50N and a speed of 2,000 mm/s. .

(Example 1)

The composition shown in Table 4 was put into a metal blender equipped with a stirrer and a heater, and stirred for 60 minutes while heating to 60°C. The coefficient of dynamic friction according to the physical properties and temperature (60, 80, 100, 120°C) of the prepared composition was measured and described in Table 5 and FIGS. 1 to 4.

(Examples 2 to 4 and Comparative Examples 1 to 2)

It was prepared in the same manner as in Example 1, except that the composition ratio of the composition was changed as described in Table 4 below. The physical properties and dynamic friction coefficient of the prepared composition were measured and described in Table 5 and FIG. 1.

[Table 4]

(In Table 4, the composition ratios all mean weight percent.)

[Table 5]

As shown in Table 5, it can be seen that the lubricating oil composition according to the present invention satisfies both the ccs low temperature viscosity at -30°C and the BP low temperature viscosity at -40°C. Through this, it was confirmed that the lubricating oil composition according to the present invention can achieve a low viscosity at a low temperature while maintaining an oil film at a high temperature. In addition, as shown in Figs. 1 to 4, compared with the currently commercially available lubricant composition (Comparative Example 2), the coefficient of dynamic friction is almost the same, so it was confirmed that the friction characteristics were almost the same as the existing products at lower cost.

Although a preferred embodiment of the present invention has been described above, it is clear that various changes, modifications, and equivalents can be used in the present invention, and the same can be applied by appropriately modifying the embodiment. Therefore, the contents described in the examples do not limit the scope of the present invention determined by the limits of the claims.

Claims (9)

A lubricating oil composition for an automatic transmission comprising 75 to 90% by weight of one or more mineral oils, 1 to 10% by weight of aliphatic diester, and 5 to 20% by weight of additives, wherein the mineral oil has a kinematic viscosity at 100°C of 3 cSt or more, Including 70 to 90% by weight of paraffinic hydrocarbons and 10 to 30% by weight of naphthenic hydrocarbons,
A lubricating oil composition for an automatic transmission having a ccs low temperature viscosity at -30°C of 1,800 to 2,300 cP, and a BP low temperature viscosity at -40°C of 6,000 to 8,500 cP. The method of claim 1,
The lubricating oil composition for an automatic transmission further comprises 1 to 10 parts by weight of polyalphaolefin based on 100 parts by weight of the lubricating oil composition. The method of claim 1,
The mineral oil is a lubricating oil composition for an automatic transmission comprising 70 to 90% by weight of a paraffinic hydrocarbon and 10 to 30% by weight of a naphthenic hydrocarbon. The method of claim 3,
The mineral oil is a lubricating oil composition for an automatic transmission comprising a first mineral oil having a ccs low temperature viscosity of 2000 cP or less at -30°C and a second mineral oil having a ccs low temperature viscosity of 4,000 cP or less at -30°C. The method of claim 4,
The mineral oil is a lubricating oil composition for an automatic transmission comprising 50 to 80% by weight of the first mineral oil and 20 to 50% by weight of the second mineral oil. The method of claim 1,
The aliphatic diester is a lubricating oil composition for an automatic transmission having a kinematic viscosity of 10 cSt or less at 40°C and 4 cSt or less at 100°C. The method of claim 2,
The polyalphaolefin is a lubricating oil composition for an automatic transmission having a kinematic viscosity of 150 cSt or more at 100° C. and a viscosity index of 200 or more. The method of claim 1,
The additive is a lubricant composition for an automatic transmission comprising any one or two or more selected from a detergent, a friction reducing agent, a sediment formation inhibitor, a corrosion inhibitor, an antioxidant, an rust inhibitor, an antiwear agent, an antifoam agent, a metal deactivator, an extreme pressure agent, and a dispersant. . delete

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