KR101525036B1 - Lubricant composition having improved low temperature properties - Google Patents

Abstract

The present invention relates to a lubricating oil composition comprising 80-90 wt% of lubricating base oil whose kinematic viscosity is 3 to 5 cSt at 40°C and 1 to 2 cSt at 100°C, and 150C NOACK evaporation loss is less than or equal to 16%; and 8-16 wt% of a polymethacrylate-based viscosity index improver whose a shear stability index is 45-55, and to lubricating oil whose low temperature viscosity (@-40°C Brookfield) is less than or equal to 600cP, a viscosity index is more than or equal to 300, evaporation loss (NOACK 150°C) is less than or equal to 15%, kinematic viscosity is 10.5 to 14.5 cSt at 40°C and more than or equal to 3.8 cSt at 100°C, and a flash point is more than or equal to 120°C. Accordingly, lubricating oil having excellent performances at low temperatures can be obtained.

Description

[0001] The present invention relates to a lubricant composition having improved low temperature performance,

More particularly, the present invention relates to a lubricating oil composition having excellent performance at a low temperature, a lubricating oil using the lubricating oil composition, and a method for producing the same.

It is most preferable that the viscosity of the lubricating oil is kept unchanged over a wide range from a low temperature to a high temperature. However, in most lubricating oils, properties such as viscosity characteristics are changed depending on the temperature, and performance as a lubricating oil is deteriorated at a high temperature or a low temperature. In order to improve the temperature characteristics of the lubricating oil, a viscosity index improver or a polymer compound serving as a pour point depressant has been mixed and has been improved in specific properties of the lubricating oil depending on the use of the lubricating oil.

Korean Patent Laid-Open Publication No. 2009-0050051 discloses a lubricating oil composition having a low viscosity, excellent low-temperature fluidity and oxidation stability, a long metal fatigue life, and particularly a lubricating oil composition suitable for a transmission of an automobile. , An ethylene -? - olefin copolymer having a specific range of molecular weights is blended at a predetermined ratio. However, the Brookfield viscosity at -40 ° C is still high at 7200 to 9200 cP and the viscosity index is also at 174 to 176 Only.

U.S. Patent No. 4,853,139 discloses a lubricating oil composition having a constant viscosity at a high temperature and a low temperature and having excellent shear stability and abrasion resistance. The composition has a kinematic viscosity of 1.5 to 50 cSt at 100 占 폚, a pour point of -25 占 폚 or less, Ethylene-alpha-olefin copolymer having a number average molecular weight of 1,000 to 8,000 and additives, but also has a very high Brookfield viscosity of 127,000 to 172,000 cP at -40 ° C and a viscosity index of 116 to 195 to be.

In order to maintain the performance of the lubricating oil, particularly the shock absorber lubricating oil even in a low temperature region, a low temperature viscosity (@ -40 캜 Brookfield) of 600 cP or less and a viscosity index of 300 or more are required. Therefore, In particular, when the viscosity index is low, changes in viscosity at low temperature and high temperature are increased, which causes many problems in the performance of the lubricant.

In order to solve the above problems, the inventors of the present invention have confirmed that lubricating oil, viscosity index improver, and additives having specific physical properties are excellent in the performance of lubricating oil at low temperatures of -40 ° to 0 °, It was completed.

The present invention relates to a lubricating oil composition capable of maintaining performance at low temperature by mixing a lubricating oil, a viscosity index improver and an additive having kinematic viscosity of 3 to 5 cSt at 40 ° C. separated from a low-temperature base oil and having a kinematic viscosity of 1 to 2 cSt at 100 ° C. To provide a lubricating oil production method.

The lubricating oil composition according to the present invention has a kinematic viscosity of 3 to 5 cSt at 40 DEG C, a lubricating oil having a kinematic viscosity of 1 to 2 cSt at 100 DEG C of 80 to 90 wt%, a PMA viscosity index improver of 8 to 16 wt% having a shear stability index of 45 to 55, And 2 to 4% by weight of an additive.

The PMA-based viscosity index improver may be a star-shaped copolymer or the PMA-based viscosity index improver may be non-dispersible, and the evaporation loss (NOACK 150 ° C) of the lubricant oil may be 15% by weight to 20% by weight.

The additive is selected from the group consisting of an antioxidant, an abrasion inhibitor, a metal deactivator, a friction modifier, and an antifoaming agent.

The lubricating oil comprises the above lubricating oil composition and has a low viscosity (@ -40 占 폚 Brookfield) of 600 cP or less, a viscosity index of 300 or more, a loss of evaporation (NOACK 150 占 폚) of 15 weight% or less, 40 占 폚 kinematic viscosity of 10.5 to 14.5, cSt or more, and the flash point may be 120 ° C or higher.

The lubricating oil composition according to the present invention and the method for producing the lubricating oil using the lubricating composition according to the present invention have an effect of obtaining a low temperature viscosity (@ -40 DEG C Brookfield viscosity) which is remarkably low as compared with a lubricating oil excellent in performance even at a low temperature, particularly a conventional lubricating oil.

Hereinafter, embodiments of the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

The terms "about "," substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation to or in the numerical value of the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.
In the present invention, 'low temperature viscosity (@ -40 캜 Brookfield)' means viscosity measured by Brookfield viscosity measurement method at -40 캜, and 'evaporation loss (NOACK 150 캜)' is conventionally used in the art Means the evaporation loss measured at 150 ° C by the NOACK method.

In the present invention, the low temperature may be -40 ° C to 0 ° C as a typical temperature range, but is not limited thereto, and may be a temperature at which the lubricant is used in the winter season, high latitude or polar region in the art. In the present invention, Brookfield viscosity and viscosity index are used as an index indicating the performance of the lubricating oil composition in the low temperature range, and the Brookfield viscosity is measured by ASTM D 2983. In the case of a conventional mineral oil-based transmission, the Brookfield viscosity at -40 ° C is 7,000 to 150,000 cP, 7,000 to 20,000 cP for power steering, and 1,000 to 3,000 cP for shock absorber.

The lubricating oil composition according to the present invention has a kinematic viscosity of 3 to 5 cSt at 40 DEG C, a lubricating oil having a kinematic viscosity of 1 to 2 cSt at 100 DEG C of 80 to 90 wt%, a PMA viscosity index improver of 8 to 16 wt% having a shear stability index of 45 to 55, And 2 to 4% by weight of an additive.

By the above lubricating oil composition, a lubricating oil having kinematic viscosity of 3 to 5 cSt and kinematic viscosity of 1 to 2 cSt at 100 占 폚 is separated from the mineral oil base oil at 40 占 폚, 80 to 90% by weight of the lubricating oil obtained in the separation step, Mixing 8 to 16% by weight of a PMA-based viscosity index improver having an index of 45 to 55 and 2 to 4% by weight of an additive to produce a lubricating oil excellent in performance at a low temperature.

A viscosity index of 300 or more, a weight loss (NOACK 150 DEG C) of 15 wt% or less, a 40 DEG C kinematic viscosity of 10.5 to 14.5, a 100 DEG C kinematic viscosity of 3.8 or more, A lubricating oil having a flash point of 120 ° C or higher is produced.

The low-temperature viscosity of the lubricating oil obtained in the present invention is remarkably lower than that of the conventional lubricating oil, and the viscosity index has a much higher value than that of the conventional lubricating oil. Thus, the lubricating oil shows excellent performance even at a low temperature. .

The lubricating oil of the present invention is used, for example, as an oil for a transmission of a vehicle, a power steering oil, a shock absorber oil, an engine oil, an automobile industrial gear oil, a hydraulic oil, a bearing oil, It is preferably used as a hydraulic oil or shock absorber bar oil used in a hydraulic device or a shock absorber which is susceptible to changes in viscosity due to changes.

The lubricant flow path used as a feed in the present invention is not particularly limited, and any of the mineral oil or synthetic oil which is conventionally used as a base oil of lubricating oil can be appropriately selected and used. As the optical oil system, for example, at least one of the solvent deasphalting, solvent extraction, hydrogenolysis, solvent deaeration, contact deaeration, hydrogenation purification and the like is performed on the lubricating oil distillate obtained by vacuum distillation of the normal pressure residue obtained by atmospheric distillation of crude oil Refined mineral oils or waxes, and mineral oils produced by isomerizing GTL WAX.

Examples of the synthetic oil system include polybutene, polyolefin (such as an? -Olefin homopolymer or copolymer (e.g., ethylene-? -Olefin copolymer)), various esters (e.g., polyol ester, dibasic acid ester, Phosphoric acid esters and the like), various ethers (e.g., polyphenyl ether and the like), polyglycols, alkylbenzenes, alkylnaphthalenes and the like. Of these synthetic oils, polyolefins and polyol esters are particularly preferred.

As additives, viscosity index improvers, dispersants, friction modifiers, antiwear agents, rust inhibitors, waterproofing agents, metal deactivators, antioxidants and antifoaming agents may be used, and lubricating and extreme pressure additives may be further added .

On the other hand, as the viscosity index improver, non-dispersion type viscosity index improvers such as polymers or copolymers of one kind or two or more kinds of monomers selected from various methacrylic acid esters or water additives thereof, or various methacrylic acid esters And a copolymerized dispersion type viscosity index improver.

In the present invention, a viscosity index improver having a star-shaped structure is used, and a copolymer having a star-shaped structure may have 3 or more, 5 or more, 7 or more, or 10 or more arms In general, the number of arms is 3 to 30, or 4 to 20.

Particularly, the viscosity index improver of the present invention is a polymethacrylate-based (PMA-based), which can be obtained by reacting alkyl methacrylate including divinylbenzene and stearyl methacrylate A star-shaped aggregate having a core portion derived from divinylbenzene and an arm portion being a polymer chain of the alkyl methacrylate.

The alkyl methacrylate constituting the arm portion may further contain an alkyl methacrylate having an alkyl group of 10 to 16 carbon atoms and may be an alkyl methacrylate The rate includes undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, heptadecyl methacrylate, and hexadecyl methacrylate.

By using such a star-shaped viscosity index improver, the temperature characteristic of viscosity, shear stability can be improved.

Examples of the wear resistance agent include phosphate ester, phosphorous ester, and thiophosphate ester, which are usually used as a wear-resistant agent for lubricating oil.

Examples of the rust inhibitor include benzotriazole type, tolyltriazole type, thiadiazole type, and glyoxaline type compounds.

Examples of the waterproofing agent include sulfonates, alkylbenzene sulfonates, zinonyl naphthalene sulfonates, alkenyl succinic acid esters, polyhydric alcohol esters, and the like. and polyhydric alcohols.

Examples of the metal inactive agent include imidazoline, pyrimidine derivatives, alkyl thiadiazole, mercapto benzothiazole, benzotriazole or derivatives thereof , Thiadiazolyl-2,5-bisglycyrrhotothiocarbamate, 2- (alkyldithio) thiadiazolyl-2,5-bisglycidylthiocarbamate, Benzimidazole, or? - (o-carboxy + @) benzylthio) propione nitrile, and the like.

Examples of the antioxidant include oxidant inhibitors such as 4,4'-methylenebis (2,6-di-tert-butylphenol), 4,4'-bis (2,6- phenol, such as phenol, tert-butylphenol, alkyl diphenyl amine, alkyl naphthyl amine, and the like, ashless antioxidant but are not limited to, oxidant inhibitors such as oxidant inhibitors, zinc-based, copper-based, and molybdenum-based oxidative inhibitors.

Examples of the antifoaming agent include a silicone oil having a kinematic viscosity of 1000 to 10000 mm ² / s at 25 ° C, an alkenyl succinic acid derivative, an ester of a polyhydroxy aliphatic alcohol and a long chain fatty acid, Methyl salicylate and o-hydroxy benzyl alcohol, and the like.

In the lubricating oil composition of the present invention, the lubricating oil has a kinematic viscosity of 3 to 5 cSt at 40 DEG C and a kinematic viscosity of 1 to 2 cSt at 100 DEG C. When the kinematic viscosity is lower than the above kinematic viscosity range, oil addition during use is required due to the evaporation loss, and viscosity index improver is frequently used, resulting in deterioration of shear stability. On the other hand, when the viscosity is higher than the above range, the low temperature performance is deteriorated.

More preferably, the lubricating oil has a kinematic viscosity of 3.5 to 4.5 cSt at 40 ° C and a kinematic viscosity of 1.2 to 1.7 cSt at 100 ° C, which is suitable as a lubricating oil composition having excellent performance at low temperatures.

The lubricating oil having excellent performance at a low temperature to be obtained in the present invention has a low temperature viscosity (@ -40 占 폚 Brookfield) of 600 cP or less, a viscosity index of 300 or more, a loss of weight (NOACK 150 占 폚) of 15 weight% or less, a 40 占 폚 dynamic viscosity of 10.5 to 14.5, A kinematic viscosity of not less than 3.8 at 100 캜 and a flash point of not less than 120 캜 and having a kinematic viscosity of 3 to 5 cSt at 40 캜 and a kinematic viscosity of 1 to 2 cSt at 100 캜 and 80 to 90% By weight.

The viscosity index improver includes 8 to 16% by weight, more preferably 10 to 15% by weight, and 2 to 4% by weight, and more preferably 2 to 3% by weight of a PMA system having a shear stability index of 45 to 55 do.

Here, the shear stability index is an indicator for determining how much the viscosity is lost during use of the lubricant. If the viscosity index improver molecule having a larger size than the oil molecule is exposed to various mechanical shearing environments, To be ineffective in maintaining the viscosity of the lubricating oil, which can be measured by CEC L-45-A-99. The Shear Stability Index measured after 20 hours of shearing with the KRL shear stability tester is preferably in the range of 45 to 50 in the present invention. When the shear stability index is lower than this range, since the viscosity is lowered and the viscosity index improver is used more frequently, the low temperature performance can be deteriorated. When the shear stability index is lower than this range, A change occurs.

In addition, the viscosity index improver may be composed of a star-shaped copolymer. In the case of the dispersant viscosity index improver, it is desirable that the viscosity index improver is non-dispersible because it acts on the metal surface in competition with existing additives,

The additives other than the viscosity index improver may be contained in an amount of up to 4% by weight based on the total weight of the lubricating oil composition. When the content exceeds 4% by weight, it is difficult to improve the performance by increasing the dosage, It is not preferable because of the formation of precipitates in accordance with the above.

In Table 1, properties and properties of the lubricating oil composition according to the present invention are shown together with comparative examples.

B1: Paraffin mineral oil, @ 40 ^o C Kinematic viscosity 4.2 cSt, @ 100 ^o C Kinematic viscosity 1.56 cSt, @ 150 ^o C NOACK Evaporation loss 15.5%

B2: Paraffin-based mineral oil, @ 4 ^{o 0} C Kinematic viscosity 4.1 cSt, @ 100 ^o C Kinematic viscosity 1.47 cSt, @ 150 ^o C NOACK Evaporation loss 15.2%

B3: Naphthenic mineral oil, @ 40 ^o C Kinematic viscosity 4.2 cSt, @ 100 ^o C Kinematic viscosity 1.46 cSt, @ 150 ^o C NOACK Evaporation loss 25.7%

B4: Paraffin mineral oil, @ 40 ^o C Kinematic viscosity 7.6 cSt, @ 100 ^o C Kinematic viscosity 2.25 cSt, @ 150 ^o C NOACK Evaporation loss 4.1%

B5: Synthetic ester base oil, @ 40 ^o C Kinematic viscosity 2.7 cSt, @ 100 ^o C Kinematic viscosity 1.06 cSt, @ 150 ^o C NOACK Evaporation loss 18.0%

B6: Naphthenic mineral oil, @ 40 ^o C Kinematic viscosity 3.7 cSt, @ 100 ^o C Kinematic viscosity 1.40 cSt, @ 150 ^o C NOACK Evaporation loss 23.2%

V1: Star type non-dispersing polymethacrylate, shear stability index 50

V2: non-dispersed polymethacrylate, shear stability index 65

V3: non-dispersed polymethacrylate, shear stability index 50

V4: non-dispersive polymethacrylate, shear stability index 55

A1: antioxidant (2,6-di-dert-butyl-p-cresol), abrasion inhibitor (tributyl phosphate), rust inhibitor (sorbitan monooleate), metal deactivator (benzotriazole) ) Mixture

As shown in Table 1, a star-shaped viscosity index improver was used in Comparative Example 1 in which a non-dispersed polymethacrylate having a relatively high value of 65 as the viscosity index improver was used instead of the star type improver, Comparative Example 2 in which the oil evaporation loss (NOACK 150 ° C) was 25.7% higher than that in the B1 and B2 lubricant oils and Comparative Example 3 in which the non-dispersed polymethacrylates were used had low temperature viscosities of 609 cP, 617 cP and 623 cP The viscosity values of Examples 1 to 3 are higher than those of Examples 1 to 3. Particularly, since Comparative Example 1 has a high shear stability index, the viscosity decrease becomes large during long-term use, and therefore, a lot of performance changes occur compared with the kinetic viscosity of initial oil.

In Comparative Example 4, a lubricant oil and a star-type viscosity index improver were used, in which B3 having a vapor loss (NOACK 150 ° C) of 25.7% was blended at a ratio of B2 and 11:10 with a loss of 15.2% In Comparative Example 6, the results of using the lubricating oil having a loss of 23.2% (NOACK 150 ° C) and the non-dispersing polymethacrylate were 19.7% and 21.5%, respectively, Which is higher than 14.0% ~ 14.5% of Example 3.

Comparative Example 5 and Comparative Examples 7 to 9, in which the composition ratio of the lubricant oil was 80 to 90% by weight and the viscosity index improver was a star-type non-dispersing polymethacrylate, exhibited a kinematic viscosity of 3 to 5 cSt And a viscosity index of 1 to 2 cSt at 100 DEG C, and the composition ratio of the viscosity index improver is in a range other than 8 to 16 wt%.

The physical properties of the lubricating oil prepared by this composition are in the range of physical properties showing the effect to be obtained in the present invention, that is, the low temperature viscosity (@ -40 占 폚 Brookfield), the viscosity index, the evaporation loss (NOACK 150 占 폚) It does not fall within the desired range of 캜 viscosity.

In Comparative Example 5, the kinematic viscosity at 100 DEG C and the viscosity index are lower than those of Examples 1 to 3, and the low temperature viscosity (@ -40 DEG C Brookfield) is much higher than the viscosity in the range of 887 cP.

Comparative Example 7 and Comparative Example 9 showed high kinematic viscosity at 40 ° C of 28.98 cSt and 19.37 cSt, respectively. The low temperature viscosity was 1,321 cP and 1,601 cP, and the viscosity was very high at low temperature. 100 ° C Kinematic viscosity, viscosity index does not belong to the range to be obtained.

Therefore, the low-temperature viscosity of the lubricating oil obtained in the present invention is remarkably lower than that of the conventional lubricating oil, and the viscosity index is also much higher than that of the conventional lubricating oil, so that the performance of the lubricating oil is excellent even at a low temperature It can be seen that it is excellent.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

Claims (7)

8 to 16% by weight of a polymethacrylate viscosity index improver having a kinematic viscosity of 3 to 5 cSt at 40 DEG C, a lubricant oil having a kinematic viscosity of 1 to 2 cSt at 100 DEG C and a shear stability index of 45 to 55, 4 wt%.
The lubricating oil composition according to claim 1, wherein the polymethacrylate-based viscosity index improver is a star-shaped copolymer. The lubricating oil composition according to claim 1, wherein the polymethacrylate-based viscosity index improver is non-dispersible. The lubricating oil composition of claim 1, wherein the evaporation loss (NOACK 150 DEG C) of the lubricant oil is 15 wt% to 20 wt%. The lubricating oil composition according to claim 1, wherein the additive is one or more selected from the group consisting of an antioxidant, an abrasion inhibitor, a metal deactivator, a friction modifier, and an antifoaming agent. A lubricating composition comprising a lubricating oil composition according to any one of claims 1 to 5 and having a low temperature viscosity (@ -40 占 폚 Brookfield) of 600 cP or less, a viscosity index of 300 or more, a loss of evaporation (NOACK 150 占 폚) ℃ Lubricating oil having kinematic viscosity of 10.5 ~ 14.5, kinematic viscosity at 100 ℃ of 3.8 cSt or more. The lubricating oil according to claim 6, wherein the lubricating oil has a flash point of 120 ° C or higher.